sentences
stringlengths 2.76k
3.11M
| labels
class label 9
classes |
|---|---|
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of forming a semiconductor device.
2. Related Background Art
A radio-frequency (RF) plasma CVD method facilitates formation of a device with a large area or at a low temperature and thus has an advantage in that a process throughput is improved. Therefore, the method is regarded as promising as a method of forming a silicon thin film.
Taking a solar cell as an example of a semiconductor device having a semiconductor junction composed of silicon thin films, the solar cell formed of the silicon thin films is advantageous in terms of inexhaustible energy source and clean power generation process as compared with existing energy utilizing fossil fuels. However, the solar cell needs to, for its widespread use, attain a lower unit price per generated power. To that end, significant technical issues to consider are as follows: establishment of a producing technique capable of realizing a low cost, a technique of enhancing a photoelectric conversion efficiency, a technique regarding a uniformity for forming semiconductor devices having desired characteristics in a stable manner, and a technique of improving an environmental resistance in consideration of actual use conditions (in many cases, the solar cell is placed outdoors).
As a method of producing the semiconductor device having the semiconductor junction composed of the silicon thin films, there have been known a method of sequentially forming semiconductor layers of desired conductivity types in a single semiconductor forming vessel, and a so-called batch method in which a p-type layer, an i-type layer, and an n-type layer are formed in separate semiconductor forming vessels for preventing an impurity gas from mixing therein, and the like. In addition, disclosed in U.S. Pat. No. 4,400,409 as a production method capable of avoiding mixing of impurities and realizing cost reduction is a continuous plasma CVD method employing a roll to roll system. From the viewpoint of further improving characteristics and productivity, Japanese Patent Application Laid-Open No. 2002-170973 discloses a method of forming a semiconductor device characterized by including the step of exposing a semiconductor layer to an oxygen atmosphere at a semiconductor interface.
The disclosed RF plasma CVD method is an excellent semiconductor device forming method. However, in the case of including plural pin junctions and using a multi-layer structure of the p-type layer, the i-type layer, and the n-type layer, the method involves the increased number of requisite semiconductor forming vessels. Suppose a case where all the semiconductor forming vessels are continuously connected with one another to continuously form the semiconductor layers in a step of forming the semiconductor device. In such a case, an operation of the entire system needs to be stopped each time the need for maintenance, inspection, or repair arises in part of the semiconductor forming vessels. Further, when taking out it to the outside (in the air) midway through the semiconductor formation, lots may vary from one another in their characteristics, in particular, photoelectric conversion efficiencies, although depending on deposition conditions, environmental conditions, or storage conditions.
SUMMARY OF THE INVENTION
The present invention has an object to provide a method of forming a semiconductor device, which enables efficient formation of a semiconductor device having a multi-layer structure where a number of silicon thin films are laminated, a method of forming a semiconductor device having less variation in characteristics among lots and having more excellent uniformity and characteristics, and a method of forming a semiconductor device excelling in adhesion and environmental resistance.
The present invention provides a method of forming a semiconductor device that has a plurality of pin junctions comprising silicon films formed on a substrate using a radio-frequency plasma CVD method, the method comprising, in sequence: a first formation step for forming a first semiconductor layer; a covering step for covering a surface of the first semiconductor layer with a member containing water content of 0.01 to 0.5 wt % so as to contact each other; a removing step for removing the member; and a second formation step for forming a second semiconductor layer on the first semiconductor layer.
In the method according to the present invention, preferably, the member is brought into contact with the surface of the first semiconductor layer at a pressure of 10 g/cm 2 to 100 g/cm 2 , more preferably 20 g/cm 2 to 80 g/cm 2 .
In the method according to the present invention, preferably, the surface of the first semiconductor layer has a higher temperature in the covering step than a temperature of the surface of the first semiconductor layer in the removing step and the temperature of the surface is gradually decreased between the covering step and the removing step.
In the method according to the present invention, preferably, the method further includes a keeping step for keeping the device in the air at at least a part between the covering step and the removing step. It is preferable that the covering step be performed in a vacuum and then the substrate on which the first semiconductor layer has been formed and the surface of the semiconductor has been covered with the member, be kept in the air and that the removing step be performed in a vacuum. However, the covering step and the removing step may be performed in the air. Further, the substrate on which the first semiconductor layer has been formed and the surface of the semiconductor has been covered with the member, is preferably kept in a dry nitrogen atmosphere. Also, the substrate on which the first semiconductor layer has been formed and the surface of the semiconductor has been covered with the member, is preferably kept in an airtight space.
In the method according to the present invention, preferably, the member is formed of nonwoven cloth.
According to a preferable aspect of the present invention, the first semiconductor layer is formed of a semiconductor having one conductivity type and the second semiconductor layer is formed of a semiconductor having another conductivity type different from the one conductivity type or the first semiconductor layer and the second semiconductor layer are formed of semiconductors having the same conductivity type.
According to another preferable aspect of the present invention, the radio-frequency plasma CVD method includes a roll to roll method.
According to the present invention, it is possible to efficiently form a semiconductor device having a multi-layer structure where a number of silicon thin films are laminated, having less variation in characteristics among lots and having more excellent uniformity and characteristics, and to form a semiconductor device excelling in adhesion and environmental resistance.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A , 1 B, 1 C, 1 D and 1 E are schematic diagrams for illustrating a method of forming a semiconductor device according to an embodiment of the present invention.
FIGS. 2A and 2B are schematic diagrams for illustrating a method of forming a semiconductor device according to another embodiment of the present invention.
FIG. 3 is a schematic sectional view showing an example of a photovoltaic device including a semiconductor device, to which a formation method according to the present invention is preferably applicable.
FIG. 4 is a schematic sectional view showing an example of a deposited film forming apparatus for forming a semiconductor device, to which the formation method according to the present invention is preferably applicable.
FIG. 5 is a graph illustrative of distribution regarding a photoelectric conversion efficiency of each photovoltaic device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, preferred embodiments of the present invention are described but the present invention is not limited to those embodiments.
In a roll to roll method, aramid paper or a PET film has been used so far, for example, for separating a substrate. When taking out it to the outside (in the air) midway through semiconductor formation, lots may vary in their characteristics, in particular, photoelectric conversion efficiencies, although depending on deposition conditions, environmental conditions, or storage conditions. The inventor of the present invention have made extensive studies and finally found that the variation in photoelectric conversion efficiency correlates to a water content of a member covering a semiconductor surface, which content is influenced by a treating method for the member or the way of handing a roll. This is supposedly because the water from the member for separating the substrate affects the surface of a semiconductor layer.
To that end, a semiconductor device is half-completed by using aramid paper “NOMEX” (available from Du Pont Co.) having a thickness of 0.05 mm as a member and a water content changed according to a procedure described later with reference to FIGS. 1A , 1 B, 1 C, 1 D and 1 E. The half-completed device is left standing a day in an airtight space under a dry nitrogen atmosphere, followed by completing the whole semiconductor device. As a result, in some regions, the photoelectric conversion efficiency largely varies depending on the water content of the member. If the water content is larger than 0.5%, it is likely that the photoelectric conversion efficiency falls and the variation in photoelectric conversion efficiency among the lots increases. If the water content is smaller than 0.01%, the variation in photoelectric conversion efficiency among the lots tends to increase.
The cause of the variation in photoelectric conversion efficiency is not specifically known. However, the variation is supposed to occur owing to: an effect of a fine oxygen atom layer suppressing diffusion of dopants, the oxygen atom layer being formed at a semiconductor layer interface as appropriate; and modification of a semiconductor layer due to adsorption of the water in the semiconductor layer or due to bonding thereof. Note that if the water content is excessively increased, the semiconductor layer is further modified, leading to an increase in series resistance and reduction in fill factor (hereinafer, referred to as FF). As a result, the photoelectric conversion efficiency may fall and vary. In contrast, with the small water content, it is found that the member has an increased stiffness and cannot come into uniform contact with the semiconductor surface. This supposedly causes the non-uniform formation of the modified semiconductor layer and increases the variation in photoelectric conversion efficiency.
As presumed from the above, the variation in photoelectric conversion efficiency is induced unless the uniform contact is attained. According to the findings of the inventor of the present invention, a pressure at which the member contacts the semiconductor layer preferably ranges from 10 g/cm 2 to 100 g/cm 2 .
According to the present invention, it is preferable that the surface of the first semiconductor layer have a higher temperature in the covering step for covering the surface of the first semiconductor layer with the member so as to contact each other than a temperature of the surface of the first semiconductor layer in the removing step for removing the member and the temperature of the surface be gradually decreased between the two steps. The higher the temperature, the more easily the reaction proceeds. Also, the reaction itself slows down as the reaction proceeds. Therefore, in the case where the temperature is high immediately after the layer contacts the member and is gradually decreased afterward, the semiconductor layer is modified at a rather high rate at the beginning and is then gradually modified according as the temperature decreases and the thickness increases. As a result, the uniform thickness may be attained with few irregularities and the variation in photoelectric conversion efficiency may be lessened. In addition, the above is assumed to relax a stress that acts on the interface, improving an adhesion therebetween.
According to the present invention, more stable conditions are achieved under storage in a reduced pressure atmosphere, for example, in a vacuum. Meanwhile, an apparatus for keeping the vacuum atmosphere is necessary, for instance. By inserting the step of keeping the device in the air at at least one point between the covering step for covering the first semiconductor surface with the member so as to contact each other and the removing step for removing the member, a part of pin junction is formed in the semiconductor device as needed and the device can be kept in an apparatus any maintenance of which is omitted. Therefore, its productivity can be enhanced in total. Also, plural semiconductor forming apparatuses are prepared and thus the semiconductor layers with high maintenance frequency are formed by the greater number of semiconductor forming apparatuses. The productivity can be further enhanced. At this time, if the device is kept in a dry nitrogen atmosphere or an airtight space, the environmental conditions such as temperature conditions are more stabilized, which leads to the small variation in the photoelectric conversion efficiency. Accordingly, the device is preferably kept in the dry nitrogen atmosphere, more preferably the airtight space.
The member may be formed of, for example, fibrous non-woven cloth or resins such as polyethylene, polyester, PET, polyimide, and polyamide. Among those, the non-woven cloth is a preferred material in terms of appropriate water retention.
Consider a case where the first semiconductor layer is formed of a semiconductor having one conductivity type and the second semiconductor layer is formed of a semiconductor having another conductivity type different from the one conductivity type. For example, the first semiconductor layer is constituted of a p-type layer and the second semiconductor layer is constituted of an n-type layer. Alternatively, the first semiconductor layer is constituted of the n-type layer and the second semiconductor layer is constituted of the p-type layer. In such a case, the interface constitutes a reverse junction, so that the photoelectric conversion efficiency falls if the device exhibits rectifying characteristics. Therefore, it is important to cause a current to flow through as many defects as possible, for example. In addition, excessive mutual-diffusion of the impurities needs to be suppressed for maintaining characteristics of the layer with the conductivity type. In the present invention, the modified semiconductor layer is formed, making it possible to attain the less mutual-dispersion of the impurities and the many defects in the interface. Therefore, the above effect is further exerted, which is preferable.
In a case where the first semiconductor layer and the second semiconductor layer are made of semiconductors with the same conductivity type, the semiconductor layer modified with the water is formed between the layers with the conductivity type. Thus, the modified layer can suppress the diffusion of the dopants into the first semiconductor layer even when appropriately increasing the dopant concentration of the dopants in the second semiconductor layer formed on the pn interface (pn junction) side. Also, the modified semiconductor layer is formed therein to thereby achieve a wide band gap and suppress absorption of incident light, which is preferable. The modified semiconductor layer has an effect of scattering the incident light and thus is expected to increase the amount of incident light absorbed in a light absorption layer.
A roll to roll method is cited as an example where the present invention is preferably applied.
FIGS. 1A , 1 B, 1 C, 1 D, and 1 E each illustrate a method of forming a semiconductor device according to an embodiment of the present invention. In FIGS. 1A , 1 B, 1 C, 1 D and 1 E, reference numeral 101 denotes a substrate and 102 denotes a member. In the present invention, the device is formed according to the following procedure:
(a) Up to the first semiconductor layer is formed on the substrate 101 ( FIG. 1A ). (b) The substrate 101 formed up to the first semiconductor layer is made in contact with the member 102 such that the member 102 covers the substrate 101 ( FIG. 1B ). (c) Storage is done in the state where the substrate 101 formed up to the first semiconductor layer is in contact with the member 102 ( FIG. 1C ). FIG. 1C shows the case where plural sets of the substrate 101 and the member 102 are laminated and storaged. (d) The member 102 is removed from the substrate 101 formed up to the first semiconductor layer ( FIG. 1D ). (e) The second semiconductor layer and the rest are formed on the substrate 101 formed up to the first semiconductor layer ( FIG. 1E ).
FIGS. 2A and 2B show an example of a case of using a flexible substrate.
FIG. 2A shows the step of covering the substrate with a member.
A member 203 is fed from a member feeding device 204 and taken up by a take-up bobbin 202 alternate with a flexible substrate 201 . In this case, the flexible substrate 201 is wound under a tensile stress. The member 203 is pressed against the flexible substrate 201 at a given pressure. At this time, a pressure P for winding up the flexible substrate is represented by P=f/r/d, where f represents a tensile stress, r represents a radius, and d represents a width of the substrate.
Similarly, FIG. 2B shows the step of removing the member.
A member take-up device 206 rewinds and removes the member 203 from a feeding bobbin 205 around which the member and the flexible substrate 201 have been alternately wound. The flexible substrate is fed.
A photovoltaic device disclosed in Japanese Patent Application Laid-Open No. 2002-170973 is given as an example of a semiconductor device to which the formation method of the present invention is preferably applied.
In examples described hereinafter, the present invention is described in detail taking a solar cell as an example of the semiconductor device. However, those examples should not be construed as limiting the scope of the present invention.
EXAMPLE 1
A photovoltaic device shown in FIG. 3 was formed using a deposited film forming apparatus 401 shown in FIG. 4 according to the following procedure. FIG. 3 is a schematic sectional view showing an example of a photovoltaic device 301 having a silicon thin film according to the present invention. In FIG. 3 , reference numeral 302 denotes a substrate; 303 , a reflective layer; 304 , a photovoltaic device having a first pin junction; 305 , a photovoltaic device having a second pin junction; and 306 , a transparent electrode.
FIG. 4 is a schematic sectional view showing an example of a deposited film forming apparatus for forming a silicon thin film and manufacturing a photovoltaic device according to the present invention. The deposited film forming apparatus 401 of FIG. 4 is composed by connecting between a substrate feeding vessel 408 , semiconductor forming vacuum vessels 410 to 413 , and a substrate take-up vessel 409 through each gas gate 414 . A band-shaped, conductive substrate 402 was set in the deposited film forming apparatus 401 while passing through the respective vessels and gas gates. The band-shaped, conductive substrate 402 was wound off from a feeding bobbin 404 installed in the substrate feeding vessel 408 and rewound around a take-up bobbin 405 in a substrate take-up vessel 409 . At this time, the feeding bobbin 404 rewound the member 403 from a member take-up device 406 . The take-up bobbin 405 rewound the member 403 from a member feeding device 407 . The semiconductor forming vacuum vessels 410 to 413 were each composed of a deposition chamber for forming a plasma generating region and in addition, a heater 416 for heating the substrate 402 .
A radio-frequency (RF) introducing portion (not shown) was applied with an RF power from an RF power source (not shown) to induce glow discharge to thereby decompose a material gas for allowing the semiconductor layer to deposit on the conductive substrate 402 . Also, the semiconductor forming vacuum vessels 410 to 413 were each connected to a gas introducing pipe 415 for introducing the material gas or diluent gas and also to an exhaust system (not shown).
First, a band-shaped substrate made of stainless steel (SUS 430BA) (width: 50 cm, length: 1,500 m, and thickness: 0.125 mm) was well degreased and washed, and mounted to a continuous sputtering apparatus (not shown). Thus, Ag was deposited into a thin film with a thickness of 100 nm using an Ag electrode as a target through sputter deposition. Further, a ZnO thin film with a thickness of 2.0 μm was formed on the Ag thin film using a ZnO target through sputter deposition to form the band-shaped, conductive substrate 402 .
Next, the feeding bobbin 404 , around which the conductive substrate 402 had been wound, was attached to the substrate feeding vessel 408 . The conductive substrate 402 was inserted up to the substrate take-up vessel 409 through the gas gate 414 at a carry-in side, the semiconductor forming vacuum vessels 410 to 413 , and the gas gate 414 at a carry-out side. The tensile stress of 80 kg was applied to the band-shaped, conductive substrate 402 so as not to sag. The pressure varies along with an increase in radius. However, the substrate was wound at the pressure of about 20 to 60 g/cm 2 .
At this time, the aramid paper “NOMEX” (available from Du Pont Co.) having a thickness of 0.05 mm and an adjusted water content was set on the member feeding device 407 and taken up by the take-up bobbin 405 together with the substrate 402 . A vacuum pumping system including a vacuum pump (now shown) sufficiently evacuated the substrate feeding vessel 408 , the semiconductor forming vacuum vessels 410 to 413 , and the substrate take-up vessel 409 down to 6.7×10 −4 Pa (5×10 −6 Torr) or less. The water content in the member was adjusted by controlling a time of drying in a 130° C.-oven.
The water content in the member was determined by cutting the member into fragments of 1.0 g each and measuring the water content in each fragment using a Karl Fischer moisture titrator “MKC-510” (manufactured by Kyoto Electronics Manufacturing Co., Ltd.). The measurements are listed in Table 1 below.
The material gas and the diluent gas were supplied to the semiconductor forming vacuum vessels 411 , 412 , and 413 from each gas introducing pipe 415 while operating the vacuum pumping system. An H 2 gas was simultaneously supplied as a gate gas to each gas gate 414 from each gate gas supplying pipe (not shown) at a flow rate of 500 sccm. In this state, the exhaust capacity of the vacuum pumping system was adjusted to adjust a pressure inside the semiconductor forming vacuum vessels 411 , 412 , and 413 to a predetermined pressure. The formation conditions are as listed in Table 2 below.
After the pressure inside the semiconductor forming vacuum vessels 411 , 412 , and 413 stabilized, the conductive substrate 402 started moving in a direction from the substrate feeding vessel 408 to the substrate take-up vessel 409 .
Next, the glow discharge was induced inside the deposition chambers inside the semiconductor forming vacuum vessels 411 , 412 , and 413 . An amorphous n-type semiconductor layer, a microcrystalline i-type semiconductor layer, and a microcrystalline p-type semiconductor layer were formed on the conductive substrate 402 to thereby form a pin junction of a bottom cell. After forming the p-type layer, the substrate was not forcedly cooled but brought into contact with the member and taken up by the take-up bobbin 405 .
On completion of formation of the pin junction of the bottom cell, the substrate take-up vessel 409 underwent vacuum leak, and the conductive substrate 402 was taken out and kept for 24 hours in an airtight atmosphere under a dry nitrogen atmosphere until the deposited film forming apparatus 401 was ready for operation.
After that, a pin junction of a top cell was subsequently formed. The bobbin around which the conductive substrate 402 had been wound, was attached to the substrate feeding vessel 408 . The conductive substrate 402 was inserted up to the substrate take-up vessel 409 through the gas gate 414 at a carry-in side, the semiconductor forming vacuum vessels 410 to 413 , and the gas gate 414 at a carry-out side. The tensile stress of 80 kg was applied such that the band-shaped, conductive substrate 402 does not sag. Then, a vacuum pumping system including a vacuum pump (not shown) sufficiently evacuated the substrate feeding vessel 408 , the semiconductor forming vacuum vessels 410 to 413 , and the substrate take-up vessel 409 down to 6.7×10 −4 Pa (5×10 −6 Torr) or less.
The material gas and the diluent gas were supplied to the semiconductor forming vacuum vessels 411 , 412 , and 413 from each gas introducing pipe 415 while operating the vacuum pumping system. An H 2 gas was simultaneously supplied from each gate gas supplying pipe (not shown) as a gate gas to each gas gate 414 at a flow rate of 500 sccm. In this state, the exhaust capacity of the vacuum pumping system was adjusted to adjust a pressure inside the semiconductor forming vacuum vessels 411 , 412 , and 413 to a predetermined pressure. The formation conditions are as listed in Table 3 below.
After the pressure inside the semiconductor forming vacuum vessels 411 , 412 , and 413 stabilized, the conductive substrate 402 started moving in a direction from the substrate feeding vessel 408 to the substrate take-up vessel 409 .
Next, the glow discharge was induced inside the deposition chambers within the semiconductor forming vacuum vessels 411 , 412 , and 413 . An amorphous n-type semiconductor layer, an amorphous i-type semiconductor layer, and a microcrystalline p-type semiconductor layer were formed on the conductive substrate 402 to thereby form the pin junction of the top cell.
Subsequently, the band-shaped photovoltaic device thus formed was processed into a solar cell module with a size of 36 cm×22 cm by using a continuous modularizing apparatus (not shown). In the same way, five samples (Examples 1-A to 1-C, and Comparative Examples 1-A and 1B) were prepared by changing the water content in the member. 1,000 modules were arbitrarily selected from among those prepared for each sample (10 lots per sample) and evaluated for current-voltage characteristics under the irradiation of light at a spectrum of AM 1.5 and intensity of 100 mW/cm 2 by using a solar simulator “YSS-150” (manufactured by Yamashita Denso K. K.). A photoelectric conversion efficiency (η (%)) was obtained from the measured current-voltage characteristics. Further, the following cycle was repeated 100 times. That is, in the cycle, the module is first kept under conditions of 85° C. (temperature) and 85% (relative humidity) for 30 minutes and then cooled down to −20° C. in 70 minutes and kept for 30 minutes, and subsequently caused to return to the initial conditions of 85° C. (temperature) and 85% (relative humidity) in 70 minutes. After that, the adhesion was examined by using a cross-cut tape method (1 mm-interval between cuts and 100 squares).
The results thereof are shown in FIG. 5 as relative values of the photoelectric conversion efficiency distribution with an average value of the modules of Example 1-B set as 1. In addition, the results are summarized in Table 5 below.
As shown in FIG. 5 , the results reveal that Comparative Example 1-A involves slight decrease in average value of the photoelectric conversion efficiency and increase in variation of the photoelectric conversion efficiency. Examples 1-A to 1-C show almost the same distribution. Comparative Example 1-B involves the substantially similar average value but has a slight increase in variation of the photoelectric conversion efficiency. The measurements of the adhesion are as follows. In Examples 1-A to 1-C, and Comparative Example 1-A, the tape is peeled in 0 to 3 squares. In contrast, only in Comparative Example 1-B, the tape is peeled in a slightly large number of squares, i.e., 9 squares.
As understood from the above, when the water content falls within a range of 0.01% to 0.5%, the photoelectric conversion efficiency is satisfactory, the photovoltaic device with less variation in photoelectric conversion efficiency is obtained, and higher adhesion and environmental resistance are attained.
EXAMPLE 2
The photovoltaic device shown in FIG. 3 was formed using the deposited film forming apparatus 401 shown in FIG. 4 according to the following procedure.
The formation was conducted similar to Example 1 except using conditions of Tables 2 and 4 below.
The results are summarized in Table 6 below.
Comparative Example 1-A involves slight decrease in average value of the photoelectric conversion efficiency and increase in variation of the photoelectric conversion efficiency. Examples 1-A to 1-C show almost the same distribution. Comparative Example 1-B involves the substantially similar average value but has a slight increase in variation of the photoelectric conversion efficiency. The measurements of the adhesion are as follows. In Examples 1-A to 1-C, and Comparative Example 1-A, the tape is peeled in 0 to 4 squares. In contrast, only in Example 1-B, the tape is peeled in a slightly large number of squares, i.e., 11 squares.
As understood from the above, when the water content falls within a range of 0.01% to 0.5%, the photoelectric conversion efficiency is satisfactory, the photovoltaic device with less variation in photoelectric conversion efficiency is obtained, and higher adhesion and environmental resistance are attained.
TABLE 1
Water content (wt %)
Comparative Example 1-A
1.1
Example 1-A
0.5
Example 1-B
0.08
Example 1-C
0.01
Comparative Example 1-B
0.006
TABLE 2
Gas for film formation
(cm 3 /min(normal))
Power
PH 3
BF 3
density
Substrate
Film
(diluted
(diluted
(mW/cm 3 )
Pressure
temperature
thickness
SiH 4
H 2
with 2% H)
with 2% H)
RF
VHF
(Pa)
(° C.)
(nm)
n1
20
100
30
50
350
250
20
i1
100
5000
400
350
250
2000
p1
10
800
100
300
350
200
10
TABLE 3
Gas for film formation
(cm 3 /min(normal))
Power
PH 3
BF 3
density
Substrate
Film
(diluted
(diluted
(mW/cm 3 )
Pressure
temperature
thickness
SiH 4
H 2
with 2% H)
with 2% H)
RF
VHF
(Pa)
(° C.)
(nm)
n2
20
100
50
50
250
250
20
i2
300
3000
100
250
250
500
p2
10
800
100
300
250
200
7
TABLE 4
Gas for film formation
(cm 3 /min(normal))
Power
PH 3
BF 3
density
Substrate
Film
(diluted
(diluted
(mW/cm 3 )
Pressure
temperature
thickness
SiH 4
H 2
with 2% H)
with 2% H)
RF
VHF
(Pa)
(° C.)
(nm)
p2
10
800
100
300
250
200
3
n2
20
100
50
50
250
250
20
i2
300
3000
100
250
250
500
p2
10
800
100
300
250
200
7
TABLE 5
Photoelectric
conversion
Variation in
efficiency
photoelectric
(average
conversion
value)
efficiency
Peeling
Example 1-A
∘
∘
∘
Example 1-B
∘
∘
∘
Example 1-C
∘
∘
∘
Comparative
∘
Example 1-A
Comparative
∘
Example 1-B
∘: No reduction of 1% or more with respect to photoelectric conversion efficiency (average value)
∘: Standard deviation of 0.01 or less with respect to variation in photoelectric conversion efficiency
∘: 5 or smaller squares where a tape is peeled
TABLE 6
Photoelectric
conversion
Variation in
efficiency
photoelectric
(average
conversion
value)
efficiency
Peeling
Example 1-A
∘
∘
∘
Example 1-B
∘
∘
∘
Example 1-C
∘
∘
∘
Comparative
∘
Example 1-A
Comparative
∘
Example 1-B
∘: No reduction of 1% or more with respect to photoelectric conversion efficiency (average value)
∘: Standard deviation of 0.01 or less with respect to variation in photoelectric conversion efficiency
∘: 5 or smaller squares where a tape is peeled | 4y
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a truss making apparatus. In one of its aspects, the invention relates to an apparatus for making floor trusses from wooden members wherein the apparatus is adjustable to make trusses of different lengths, widths and bracing patters.
2. State of the Prior Art
Wooden trusses for both roofs and floors have been used for making trusses of dimensional lumber and nail or connector plates. The connector or nail plates are made of 14-20 gauge metal sheets from which are punched a multiplicity of closely spaced jagged projections. These projections extend outwardly from a face of the nail plates and are driven into the lumber at the joints to join the lumber together.
Normally, the trusses are assembled on a table, the nail plates are placed over the top of the wooden truss members and driven into the joints. For this purpose, special jigging is available. A gantry roller press is provided to pass over the truss and press the nail plates into place. After one side of the truss is completed, the truss is turned over, the nail plates are placed at the joints of the second side and a roller press is again rolled over the truss to drive the second set of nail plates into the truss members at the joints.
A truss making apparatus for making roof trusses is disclosed in U.S. Pat. No. 3,255,943 issued to Arthur C. Sanford on June 14, 1966. The Sanford apparatus comprises supporting pads which are mounted on rails for adjustable movement along the rails for making different height trusses. The rails themselves are supported on other rails and are mounted for movement toward and away from each other so that different shapes and sizes of trusses can be made.
Black, in U.S. Pat. No. 3,100,301, issued Aug. 13, 1963, and in U.S. Pat. No. 2,996,721, issued Aug. 22, 1961, discloses a truss making apparatus similar to the Sanford apparatus except that the nail plates are pressed into the joints by a hydraulic cylinder from beneath and a pressure plate is positioned over the joint to react to the pressure from the cylinder to press the nail plates on top of the truss into the lumber truss members. In the later Black patent, the trusses are prestressed by urging upper chords toward the lower chords during the joining operation. The resulting truss is somewhat compressed between the top and bottom chords.
Another truss making apparatus is disclosed in the U.S. Pat. No. 3,241,585 to Jureit, issued Mar. 22, 1966. In the Jureit apparatus, the jigs are supported on rails, one of which is adjustable toward and away from the other. The Jureit apparatus as well as the other aforementioned apparatus is generally designed for making roof trusses and is generally not appropriate for making floor trusses.
SUMMARY OF THE INVENTION
According to the invention, there is provided an apparatus for making floor or roof trusses which have parallel first and second elongated truss plates, end truss plates at the ends of the first and second truss plates and angle plates disposed and braced between the first and second truss plates. The apparatus includes a supporting base, first and second rails mounted on the base and means for evenly adjusting the spacing between the first and second rails to adjust for the different truss heights. A plurality of first positioning pads are adjustably secured to the first rail in spaced relationship to each other, at least end ones of the first positioning pads have stop means to retain end truss plates thereon perpendicular to the first and second rails. The end and the other of the first positioning pads also have a means for retaining the first elongated truss plate parallel to the first rail and means for retaining nail plates on each of the positioning pads in a given predetermined location.
A plurality of second positioning pads are adjustably mounted on the second rail in spaced relationship to each other. At least the end ones of the positioning pads have stop means to retain an end truss plate thereon perpendicular to the first and second rails, the end ones and the other of the second positioning pads having means for retaining second elongated truss plates parallel to the second rail. Means are provided for retaining a nail plate on each of the second positioning pads at a given predetermined location. Further, means are provided for applying pressure to the second elongated truss plate to firmly seat all of the truss plates together for the joining operation.
The first and second positioning pads are so spaced and aligned so as to support the opposite ends of all of the angle truss members extending between the first and second truss members. Means are provided for at least partially pressing the nail plates simultaneously into the top and the bottom of the trusses at the joints of the truss members.
The first and second rails have a slight congruent curvature so that the resulting truss has a slight camber or curvature. This camber or curvature is automatically built into the trusses regardless of the size and results in a prestressing of the trusses in a manner so as to strengthen the trusses under load. Desirably, the curvature results in a deviation of about 0.21% from linearity but can range from 0.10-0.40% in deviation. In terms of a 40-foot truss, for example, the preferred deviation would be about 1 inch. Because the camber is built into the rails, each truss will have the same radius of curvature regardless of size.
At least one of the first and second positioning pads has means for aligning the truss angle plate ends at a given position from the pads to assure uniformity and accuracy of the resulting trusses. These alignment means can be in the nature of scribed lines on the positioning pad.
Desirably, the second positioning pads further comprise stop means for retaining the second truss members in a given position against the force of the pressure applying means so that the size of the truss is accurately ascertained.
The pressure applying means on the second positioning pads comprise a plate pivotably actuated between a first position in nonengaging relationship with the second truss member and a second position in bracing relationship with respect to the second truss plate. Means are provided for actuating pivotable movement of the plate between the first and second positions. Further, lock means are provided on the second pads for locking the plate rigidly in the second position. In the event that the nail plates are not completely seated by the first pressing operation, means are provided for transferring the assembled trusses to a second conveyor by which the truss is conveyed through a means for completely seating the nail plates in the truss.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to the accompanying drawings in which:
FIG. 1 is a perspective view of a truss on a truss making machine according to the invention;
FIG. 2 is a top view of a section of the truss making machine without the truss members thereon;
FIG. 3 is a side view in section of the truss making machine taken along lines 3--3 of FIG. 2;
FIG. 4 is an enlarged view of a portion of the truss machine;
FIG. 5 is an enlarged view of another portion of the machine;
FIG. 6 is a side view similar to FIG. 3 illustrating the manner in which the completed truss is removed from the truss making machine; and
FIG. 7 is a schematic view showing the method of making the truss members according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, and to FIG. 1 in particular, there is illustrated a truss 10 formed from a top plate 12, a bottom plate 14 and a plurality of angle plates 16 positioned between the top and bottom plates 12 and 14. End plates 18 are positioned at each end of the truss between the top and bottom plates 12 and 14 respectively. Nail plates 20 are positioned at the joints between the angle plates 16 and the top, bottom and end plates 12, 14 and 18 to secure the plates together. In the art, the top and bottom plates 12 and 14 are sometimes referred to as top and bottom chords and the angle plates are referred to as web markers.
A truss making machine 22 supports the truss 10 and comprises a plurality of bottom pads 24 and a plurality of top pads 26. Each of the bottom and top pads is positioned at each joint between the angle or end plates and the top and bottom plates. Pressure cylinders 28 having linkages 30 are provided on the top pads 26 for securely bracing the truss between the bottom of top pads 24 and 26 during the initial joining operation.
Referring now to FIGS. 2 and 3, a base support 32 having various vertical and horizontal members joined together provides support for the top and bottom pad assemblies. The bottom pad assembly comprises a pair of elongated channel members 34 and 36 joined at the bottom portion through a base plate 38. A pair of rail members 40 are secured to the top of the channel members 34 and 36, leaving a narrow slot therebetween. The channel members 34 and 36 are welded in place on the base support 32. The opening between the channel members 34 and 36 is slightly curved between the ends of the rails so that a slight curvature can be built into the resulting truss.
The bottom pad 24 has a pair of recessed holes 42 extending therethrough and in registry with the narrow slot between the rail members 40. A bolt 44 having a nut 46 extends through recessed hole 42 and through a clamp plate 48 to releasably secure the bottom pad 24 in a given adjusted position along the rail slot formed by the rail members 40.
A movable support 50 for the top pads 26 is similar in construction and comprises a base plate 54 secured to a pair of channel members 56 and 58. However, the base plate 54 is not secured to the base support 32 so that the movable support 50 is slidable along the top of the base support 32. A pair of rail plates 60 are secured to the top of the channel members 56 and 58 and form a narrow slot therebetween. Bolts 62 are positioned through recessed holes 68 in the top pads 26 and extend through a clamp plate 66 to secure the top pads 26 in various adjusted positions along the rail plates 60. To this end, a nut 64 threadably engages the bolt 62 at the bottom portion thereof so that the bolt clamps the rail plates 60 between the top pad 26 and the clamp plate 66.
The opening between the channel members 56 and 58 has a curvature congruent with that of the channel members 34 and 36 so that the top plate member 12 will have the same curvature as the bottom plate 14. The degree of curvature of these rails can vary but is generally selected so as to give a slight upward curvature to the resulting truss without resulting in a loss of substantial squareness at the ends of the truss.
A block 70 having a threaded hole 74 therethrough is secured to the channel members 56 and 58 through supports 72. A threaded rod 76 threadably engages the threaded hole 74 of block 70 and is journaled in journal plates 80 which are mounted on the channel members 34 and 36. A handle 78 is provided on one end of the threaded rod 76 for ease of rotating the rod as desired. A shield 82 is secured to channel member 34 above the threaded rod 76 and extends laterally above the rod 76 for protective purposes. To this end, the shield 82 extends through the channel members 56 and 58 and through the block 70.
A plurality of threaded rods 76 are provided along the length of the machine so that the movable support 50 can be uniformly moved toward or away from the fixed support which mounts the bottom pads 24. In order to synchronize the rotation of all threaded rods together, each threaded rod has mounted thereto a sprocket 84. A chain 86 is trained around the sprockets 84 so that the sprockets 84 and the threaded rods 76 are all driven in unison as the handle 78 is turned. Alternatively two or more cranks and chain assemblies can be provided to separate segments of the apparatus 22 for adjusting the spacing between the top and bottom pads in separate operations.
The threaded rods 76 connect the two sets of rails together near to the positioning pads. By this construction, the positioning pads are braced with respect to each other so that the appropriate lateral pressure can be applied to the trusses during joining while maintaining dimensional tolerances in a manner which will be described hereinafter.
Referring now to FIGS. 3 and 4, the bottom pads 24 have a stop plate 88 secured at a bottom edge thereof through a plurality of bolts 89. Tapped holes 96 are also provided for movement of the stop plate 88 to the very back edge of the bottom pad 24. A plurality of threaded central holes 92 are also provided forwardly of the plate 88. Each of the holes 92 contains a nail plate positioning lug 94 which projects slightly above the surface of the pad 24. The positioning lugs 94 are sized so as to fit in the openings in the nail plates 20 which are positioned on the pads 24. Thus, various sizes of nail plates can be positioned on the pads 24 due to the fact that the pads are engaged on the bottoms by the lugs 94. The lugs 94 have a threaded outer surface and an upper narrow blade end which projects into openings in the nail plate. The threaded body of the positioning lugs 94 makes them vertically adjustable with respect to the surface of the pads for precise vertical positioning.
A scribe center line 98 is provided in a central location of the pad 24 perpendicular to the stop plate 88. The scribe center line gives a visual reference for positioning the angle plate 16 in a correct location on the pads 24. A pair of tapped holes 100 are provided at the side edge of the bottom pad 24 and can be used to position an end retainer plate 90 (see FIG. 1) or stop pins in the pad which is used at the end of the truss. Each of the bottom pads has tapped holes at one side thereof so that it can be used as an end pad if desired. By this structure, the apparatus can be quickly and easily modified to accommodate shorter or longer trusses. The end pads can be easily converted to a pad which retains an end plate.
A tapped hole 102 is also provided on the center line 98. A threaded pin can be positioned within the tapped hole 102 for alignment purposes when setting up the pads for a new truss size. To this end, a spacer bar (not shown) having holes at each end is provided for spacing the pads. The holes in the spacer bar fit over the pins in the end pad and an adjacent pad. The pads are then tightened in place. The spacer bar is removed and the process is repeated using a properly aligned pad and an adjacent pad which is unaligned until all pads are spaced a desired distance apart.
Reference is now made to FIGS. 3 and 5 for a description of the top pads 26. These pads are quite similar to the bottom pads 24 except for a pressure-applying mechanism in lieu of the stop plates 88. Stop pins 104 are provided at the sides of the pads 26. A plurality of tapped holes 110 are provided at the bottom and sides of the pad 26 for positioning other stop pins so that the pad can be used as an end pad if necessary. As in the case of the bottom pads 24, each top pad 26 is preferably provided with the hole 110 on one side or the other of the pad so that any pad in the line is convertible to an end pad. In such a circumstance, threaded rods (not shown), like pins 104, or an end plate 108 (FIG. 1) are secured to the top pads to provide stops for the end plates of the truss. A scribe center line 112 is provided in a central location perpendicular to the rails for aligning the angle plates 16 with respect to the top plates 12. A tapped alignment hole 113 is provided at the scribed line 112 for alignment of the top plates in a manner which has been described hereinabove with respect to tapped holes 102 in the bottom pads 24.
Tapped central holes 114 are provided with threaded nail plate positioning lugs 116 for retaining the nail plates. The lugs 116 have narrow blades which extend slightly above the surface of the top pad 26 so that they project slightly into the holes in the nail plates. The threaded bodies of the lugs 116 make them vertically adjustable for precise positioning with respect to the top surface of the pad 26.
Retaining stops and locks 118 and 120 are provided on top of the positioning pads 26. A pressure plate 122 is pivotally mounted on pin 128 for movement from the position illustrated in FIG. 5 to a position aligned with the scribe center line 112 as shown in FIG. 1. In the latter position, the pressure plate 122 is in engagement with the retaining stops and locks 118 and 120. A connecting link 124 is pivotably mounted to an end of the pressure plate 122 and is pivotably mounted at the other end thereof to the piston rod of pressure cylinder 28 through a clevis mounting 126. As the cylinder 28 is operated to extend the piston rod, the linkage 124 pulls the right end of the pressure plate 122 (as viewed in FIG. 5) downwardly to swing the other end thereof firmly against the top plate in the truss (not shown in FIG. 5). In this position, the other end of the pressure plate 122 rigidly abuts the retaining stop and lock 120 and braces the truss in a slightly stressed condition, as seen in FIG. 1.
Reference is now made to FIG. 6 for a description of the manner in which the partially completed trusses are removed from the truss making machine and transferred to a roller conveyor for completion of pressing of the nail plate into the truss. As illustrated in FIG. 6, the truss making apparatus 22 is positioned adjacent and parallel to a roller conveyor 130. Upright side supports 132 and 134 rotatably mount roller 136 and comprise the roller conveyor 130. A roller press 138, which can be a two high roller press (not shown), is provided at the end of the roller for completely pressing the nail plates into the truss apparatus. The roller press can be any conventional roller press, such as a Gantry press disclosed in U.S. Pat. No. 3,255,943, to Sanford or U.S. Pat. No. 3,464,348 to McGlinchey, or U.S. Pat. No. 3,538,843 to Lubin. Alternatively, a stationary two high roller press, such as that manufactured by Clary Corporation, Ft. Worth, Tex., or Sanford Industries, Pompano Beach, Fla., can be employed.
A plurality of transfer rods 140 are rotatably mounted at 142 at one side of the roller conveyor 130. The rods extend across the roller conveyor 130 but beneath the top surface of the roller 136 and rest on an elongated pipe 144 at the opposite side of the roller conveyor. Transfer rods 140a extend across the truss making apparatus 22 and rest on pipes 156 and 160. Fluid pressure cylinders 154 and 158 support the pipes 156 and 160, respectfully. The rods 140a in normal position illustrated in FIG. 6 are positioned beneath the top surfaces of the bottom pad 24 and top pad 26.
The pipe 144 is supported on the end of extendible rods of a plurality of fluid pressure cylinders 146. When the cylinders 146, 154 and 158 are operated to extend the rods thereof, the pipes 144, 156 and 160 are raised, thereby raising the transfer rod 140 about pivot point 142, and thereby raising rod 140a. The raised positions of the transfer rods 140 and 140a are illustrated in phantom lines in FIG. 6. When the rods 140a are raised, the truss 10 is also raised from the pads 24 and 26. The truss can be pushed onto the rods 140 and will slide down the incline formed by the rods 140 onto the rollers 136. The transfer rods 140 and 140a are then lowered and the truss is propelled by means (not shown) which drive the rollers 136 through the roller press 138.
A rail 148 is positioned at each side of the truss making apparatus 22 at the left side (as viewed in FIG. 6) of the roller conveyor 130 for transporting the roller press 152 over the truss 10 to initially press the nail plates into the truss.
Reference is now made to FIG. 7 which schematically shows the apparatus according to the invention. As seen in FIG. 7, the press 152 rides on rails 148 and 150 which are positioned outside of the truss making apparatus 22. The press 152 can be any conventional movable Gantry press, such as disclosed, for example, in U.S. Pat. No. 3,538,843 to Lubin. The roller conveyor 130 is positioned adjacent to the truss making apparatus 22 and the roller press 138 is positioned at an end of the roller conveyor 130 opposite to the normal position of the roller press 152.
In operation, the top and bottom pads 26 and 24 are positioned in a desired location along their respective rails. The alignment of the pads can be accomplished with the use of a spacer bar at the tapped holes 120 in the bottom pads and 113 in the top pads as described above. Further, the spacing between the pad supporting rails is set as desired by rotating crank 78 for variance in height of the truss. The rails for the top and bottom pads have a slight camber or arc congruent with each other so that the resulting truss has a slight camber. Generally the radius of curvature of the rails is such that the deviation from linearity is in the range of 0.1-0.4%, preferably about 0.21%. In any given position, the rods 140 may interfere with the top and bottom pads 26 and 28. However, the rods 140 and 140a are slidably mounted at the pivot points 142 so that adjustment of the transfer rods 140 and 140a with respect to the top and bottom pads 26 and 24 can be easily accomplished. During the adjustment process for the top and bottom pads 26 and 24, the transfer rod 140a can be positioned in a raised position illustrated in phantom lines in FIG. 6 to facilitate alignment of the pads 24 and 26. After alignment, the rods are dropped to the position illustrated in FIG. 6. The distance between the positioning pads 24 and 26 can thereafter be adjusted by rotating crank handle 78 to rotate the threaded rods 76.
When the pads 24 and 26 have been tightened into adjusted position, nail plates are positioned on each of the pressure pads with the nail plates, for example, engaging the lugs 116 in the top pads 26 and engaging the lugs 94 in the bottom pads 24. The top plate 12, bottom plates 14, angle plates 16 and end plates 18 are then positioned in proper location on the pads 24 and 26. During this positioning process, the cylinders 28 are in retracted condition so that the pressure plate 122 will be in retracted position as illustrated in FIG. 5. After the various truss elements are positioned on the pads over the bottom nail plates, the cylinders 28 are then actuated to rotate the pressure plates 122 into locking position abutting the top plates 12 and pressing the top plate 12 against stop pins 104. Additional nail plates are then placed on top of the truss members at each joint thereof. Subsequent to placing of the top nail plates, the roller press 152 is rolled along tracks 148 and 150 over the assembled truss, thereby pressing the top nail plate and bottom nail plate at least partially into the truss members at the joints. Generally, the top nail plate will be completely pressed into the truss but the bottom nail plate will only be partially pressed into the truss plates. In this manner, the truss is locked together even though the nail plates may not be completely seated in the joints. The pads are held rigidly with respect to each other by the threaded rods 76 during the nailing operation. The cylinders are then deactuated to rotate the pressure plates 122 to a nonengaging position as illustrated in FIG. 5. The cylinders 146, 154 and 158 are actuated to raise the transfer rods 140 and 140a and the truss 10 to the position illustrated in phantom lines in FIG. 6. The truss then slides down the transfer rods onto the roller conveyor 130. The cylinders 146, 154 and 158 then retract their piston rods, thereby lowering pipe 144 and the transfer rods 140 and 140a. Subsequently the roller conveyor 130 is driven to drive the truss through the roller press 138 which is driven to completely seat the nail plates in the truss.
Whereas the invention has been described with respect to the making of floor trusses, the invention could also be used for making parallel chord roof trusses, i.e., trusses which have parallel top and bottom plates, as used for example in flat roof constructions.
Reasonable variation and modification are possible within the scope of the foregoing disclosure, the drawings and appended claims without departing from the spirit of the invention. | 4y
|
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuing application of PCT Application No. PCT/JP01/07954 filed on Sep. 13, 2001, designating U.S.A. and now pending.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to laser processing methods and laser processing apparatus used for cutting objects to be processed such as semiconductor material substrates, piezoelectric material substrates, and glass substrates.
[0004] 2. Related Background Art
[0005] One of laser applications is cutting. A optical cutting process effected by laser is as follows: For embodiment, a part to be cut in an object to be processed such as a semiconductor wafer or glass substrate is irradiated with laser light having a wavelength absorbed by the object, so that melting upon heating proceeds due to the laser light absorption from the surface to rear face of the object to be processed at the part to be cut, whereby the object to be processed is cut. However, this method also melts surroundings of the region to become the cutting part in the surface of the object to be cut. Therefore, in the case where the object to be processed is a semiconductor wafer, semiconductor devices located near the above-mentioned region among those formed in the surface of the semiconductor wafer might melt. In the specification, “wafer shape” means a shape similar to a semiconductor wafer made of silicon of which thickness is about 100 μm, for example, a thin circular shape having a orientation flat therein.
[0006] Known as embodiments of methods which can prevent the surface of the object to be processed from melting are laser-based cutting methods disclosed in Japanese Patent Application Laid-Open No. 2000-219528 and Japanese Patent Application Laid-Open No. 2000-15467. In the cutting methods of these publications, the part to be cut in the object to be processed is heated with laser light, and then the object is cooled, so as to generate a thermal shock in the part to be cut in the object, whereby the object is cut.
[0007] When the thermal shock generated in the object to be processed is large in the cutting methods of the above-mentioned publications, unnecessary fractures such as those deviating from lines along which the object is intended to be cut or those extending to a part not irradiated with laser may occur. Therefore, these cutting methods cannot achieve precision cutting. When the object to be processed is a semiconductor wafer, a glass substrate formed with a liquid crystal display device, or a glass substrate formed with an electrode pattern in particular, semiconductor chips, liquid crystal display devices, or electrode patterns may be damaged due to the unnecessary fractures. Also, average input energy is so high in these cutting methods that the thermal damage imparted to the semiconductor chip and the like is large.
SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to provide laser processing methods and laser processing apparatus which generate no unnecessary fractures in the surface of an object to be processed and do not melt the surface.
[0009] The laser processing method in accordance with an aspect of the present invention comprises a step of irradiating an object to be processed with laser light with a light-converging point located therewithin, so as to form a modified region caused by multiphoton absorption within the object along a cutting line along which the object should be cut. If there is a certain start region in the part to be cut in the object to be processed, the object to be processed can be broken by a relatively small force so as to be cut. In the laser processing method in accordance with this aspect of the present invention, the object to be processed is broken along the line along which the object is intended to be cut using the modified region as the starting point, whereby the object can be cut. Hence, the object to be processed can be cut with a relatively small force, whereby the object can be cut without generating unnecessary fractures deviating from the line along which the object is intended to be cut in the surface of the object.
[0010] The laser processing method in accordance with this aspect of the present invention locally generates multiphoton absorption within the object to be processed, thereby forming a modified region. Therefore, laser light is hardly absorbed by the surface of the object to be processed, whereby the surface of the object will not melt. Here, the light-converging point refers to the position where the laser light is converged. The line along which the object is intended to be cut may be a line actually drawn on the surface or inside of the object to be cut or a virtual line.
[0011] The laser processing method in accordance with an aspect the present invention comprises a step of irradiating an object to be processed with laser light with a light-converging point located therewithin under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 μs or less at the light-converging point, so as to form a modified region caused by multiphoton absorption within the object along a line along which the object is intended to be cut in the object.
[0012] The laser processing method in accordance with this aspect of the present invention irradiates an object to be processed with laser light with a light-converging point located therewithin under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 μs or less at the light-converging point. Therefore, a phenomenon known as optical damage caused by multiphoton absorption occurs within the object to be processed. This optical damage induces thermal distortion within the object to be processed, thereby forming a crack region within the object to be processed. The crack region is an embodiment of the above-mentioned modified region, whereby the laser processing method in accordance with this aspect of the present invention enables laser processing without generating melt or unnecessary fractures deviating from the line along which the object is intended to be cut in the surface of the object. An embodiment of the object to be processed in this laser processing method is a member including glass. Here, the peak power density refers to the electric field intensity of pulse laser light at the light-converging point.
[0013] The laser processing method in accordance with an aspect the present invention comprises a step of irradiating an object to be processed with laser light with a light-converging point located therewithin under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 μs or less at the light-converging point, so as to form a modified region including a molten processed region within the object along a line along which the object is intended to be cut in the object.
[0014] The laser processing method in accordance with this aspect of the present invention irradiates an object to be processed with laser light with a light-converging point located therewithin under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 μs or less at the light-converging point. Therefore, the inside of the object to be processed is locally heated by multiphoton absorption. This heating forms a molten processed region within the object to be processed. The molten processed region is an embodiment of the above-mentioned modified region, whereby the laser processing method in accordance with this aspect of the present invention enables laser processing without generating melt or unnecessary fractures deviating from the line along which the object is intended to be cut in the surface of the object. An embodiment of the object to be processed in this laser processing method is a member including a semiconductor material.
[0015] The laser processing method in accordance with an aspect of the present invention comprises a step of irradiating an object to be processed with laser light with a light-converging point located therewithin under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 ns or less at the light-converging point, so as to form a modified region including a refractive index change region which is a region with a changed refractive index within the object along a line along which the object is intended to be cut in the object.
[0016] The laser processing method in accordance with this aspect of the present invention irradiates an object to be processed with laser light with a light-converging point located therewithin under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 ns or less at the light-converging point. When multiphoton absorption is generated within the object to be processed with a very short pulse width as in this aspect of the present invention, the energy caused by multiphoton absorption is not transformed into thermal energy, so that a permanent structural change such as ionic valence change, crystallization, or polarization orientation is induced within the object, whereby a refractive index change region is formed. This refractive index change region is an embodiment of the above-mentioned modified region, whereby the laser processing method in accordance with this aspect of the present invention enables laser processing without generating melt or unnecessary fractures deviating from the line along which the object is intended to be cut in the surface of the object. An embodiment of the object to be processed in this laser processing method is a member including glass.
[0017] Modes employable in the foregoing laser processing methods in accordance with the present invention are as follows: Laser light emitted from a laser light source can include pulse laser light. The pulse laser light can concentrate the energy of laser spatially and temporally, whereby even a single laser light source allows the electric field intensity (peak power density) at the light-converging point of laser light to have such a magnitude that multiphoton absorption can occur.
[0018] Irradiating the object to be processed with a light-converging point located therewithin can encompass a case where laser light emitted from one laser light source is converged and then the object is irradiated with thus converged laser light with a light-converging point located therewithin, for embodiment. This converges laser light, thereby allowing the electric field intensity of laser light at the light-converging point to have such a magnitude that multiphoton absorption can occur.
[0019] Irradiating the object to be processed with a light-converging point located therewithin can encompass a case where the object to be processed is irradiated with respective laser light beams emitted from a plurality of laser light sources from directions different from each other with a light-converging point located therewithin. Since a plurality of laser light sources are used, this allows the electric field intensity of laser light at the light-converging point to have such a magnitude that multiphoton absorption can occur. Hence, even continuous wave laser light having an instantaneous power lower than that of pulse laser light can form a modified region. The respective laser light beams emitted from a plurality of laser light sources may enter the object to be processed from the surface thereof. A plurality of laser light sources may include a laser light source for emitting laser light entering the object to be processed from the surface thereof, and a laser light source for emitting laser light entering the object to be processed from the rear face thereof. A plurality of laser light sources may include a light source section in which laser light sources are arranged in an array along a line along which the object is intended to be cut.
[0020] This can form a plurality of light-converging points along the line along which the object is intended to be cut at the same time, thus being able to improve the processing speed.
[0021] The modified region is formed by moving the object to be processed relative to the light-converging point of laser light located within the object. Here, the above-mentioned relative movement forms the modified region within the object to be processed along a line along which the object is intended to be cut on the surface of the object.
[0022] The method may further comprise a cutting step of cutting the object to be processed along the line along which the object is intended to be cut. When the object to be processed cannot be cut in the modified region forming step, the cutting step cuts the object. The cutting step breaks the object to be processed using the modified region as a starting point, thus being able to cut the object with a relatively small force. This can cut the object to be processed without generating unnecessary fractures deviating from the line along which the object is intended to be cut in the surface of the object.
[0023] Embodiments of the object to be processed are members including glass, piezoelectric material, and semiconductor material. Another embodiment of the object to be processed is a member transparent to laser light emitted. This laser processing method is also applicable to an object to be processed having a surface formed with an electronic device or electrode pattern. The electronic device refers to a semiconductor device, a display device such as liquid crystal, a piezoelectric device, or the like.
[0024] The laser processing method in accordance with an aspect of the present invention comprises a step of irradiating a semiconductor material with laser light with a light-converging point located therewithin under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 μs or less at the light-converging point, so as to form a modified region within the semiconductor material along a line along which the object is intended to be cut in the semiconductor material. The laser processing method in accordance with an aspect of the present invention comprises a step of irradiating a piezoelectric material with laser light with a light-converging point located therewithin under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 μs or less at the light-converging point, so as to form a modified region within the piezoelectric material along a line along which the object is intended to be cut in the piezoelectric material. These methods enable laser cutting without generating melt or unnecessary fractures deviating from the line along which the object is intended to be cut in the surface of the object to be processed for the same reason as that in the laser processing methods in accordance with the foregoing aspects of the present invention.
[0025] In the laser processing method in accordance with an aspect of the present invention, the object to be processed may have a surface formed with a plurality of circuit sections, while a light-converging point of laser light is located in the inside of the object to be processed facing a gap formed between adjacent circuit sections in the plurality of circuit sections. This can reliably cut the object to be processed at the position of the gap formed between adjacent circuit sections.
[0026] The laser processing method in accordance with an aspect of the present invention can converge laser light at an angle by which a plurality of circuit sections are not irradiated with the laser light. This can prevent the laser light from entering the circuit sections and protect the circuit sections against the laser light.
[0027] The laser processing method in accordance with an aspect the present invention comprises a step of irradiating a semiconductor material with laser light with a light-converging point located within the semiconductor material, so as to form a molten processed region only within the semiconductor material along a line along which the object is intended to be cut in the semiconductor material. The laser processing method in accordance with this aspect of the present invention enables laser processing without generating unnecessary fractures in the surface of the object to be processed and without melting the surface due to the same reasons as mentioned above. The molten processed region may be caused by multiphoton absorption or other reasons.
[0028] The laser processing method in accordance with an aspect of the present invention comprises a step of irradiating an object to be processed with laser light such that a light-converging point of laser light elliptically polarized with an ellipticity of other than 1 is located within the object to be processed while the major axis of an ellipse indicative of the elliptical polarization of the laser light extends along a line along which the object is intended to be cut, so as to form a modified region caused by multiphoton absorption along the line along which the object is intended to be cut within the object to be processed.
[0029] The laser processing method in accordance with this aspect of the present invention forms a modified region by irradiating the object to be processed with laser light such that the major axis of an ellipse indicative of the elliptical polarization of laser light extends along the line along which the object is intended to be cut in the object to be processed. The inventor has found that, when elliptically polarized laser light is used, the forming of a modified region is accelerated in the major axis direction of an ellipse indicative of the elliptical polarization (i.e., the direction in which the deviation in polarization is strong). Therefore, when a modified region is formed by irradiating the object to be processed with laser light such that the major axis direction of the ellipse indicative of the elliptical polarization extends along the line along which the object is intended to be cut in the object to be processed, the modified region extending along the line along which the object is intended to be cut can be formed efficiently. Therefore, the laser processing method in accordance with this aspect of the present invention can improve the processing speed of the object to be processed.
[0030] Also, the laser processing method in accordance with the present invention restrains the modified region from being formed except in the direction extending along the line along which the object is intended to be cut, thus making it possible to cut the object to be processed precisely along the line along which the object is intended to be cut.
[0031] Here, the ellipticity refers to half the length of the minor axis/half the length of major axis of the ellipse. As the ellipticity of laser light is smaller, the forming of modified region is accelerated in the direction extending along the line along which the object is intended to be cut but suppressed in the other directions. The ellipticity can be determined in view of the thickness, material, and the like of the object to be processed. Linear polarization is elliptical polarization with an ellipticity of zero.
[0032] The laser processing method in accordance with an aspect of the present invention comprises a step of irradiating an object to be processed with laser light such that a light-converging point of laser light elliptically polarized with an ellipticity of other than 1 is located within the object to be processed while the major axis of an ellipse indicative of the elliptical polarization of the laser light extends along a line along which the object is intended to be cut under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 μs or less at the light-converging point, so as to form a modified region including a crack region along the line along which the object is intended to be cut within the object to be processed.
[0033] The laser processing method in accordance with this aspect of the present invention irradiates the object to be processed with laser light such that the major axis of the ellipse indicative of the elliptical polarization of laser light extends along the line along which the object is intended to be cut in the object to be processed, thus making it possible to form the modified region efficiently and cut the object precisely along the line along which the object is intended to be cut as in the laser processing method in accordance with the above-mentioned aspect of the present invention.
[0034] The laser processing method in accordance with an aspect of the present invention comprises a step of irradiating an object to be processed with laser light such that a light-converging point of laser light elliptically polarized with an ellipticity of other than 1 is located within the object to be processed while the major axis of an ellipse indicative of the elliptical polarization of the laser light extends along the line along which the object is intended to be cut under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 μs or less at the light-converging point, so as to form a modified region including a molten processed region along the line along which the object is intended to be cut within the object to be processed.
[0035] The laser processing method in accordance with this aspect of the present invention irradiates the object to be processed with laser light such that the major axis of the ellipse indicative of the elliptical polarization of laser light extends along the line along which the object is intended to be cut in the object to be processed, thus making it possible to form the modified region efficiently and cut the object precisely along the line along which the object is intended to be cut as in the laser processing method in accordance with the above-mentioned aspect of the present invention.
[0036] The laser processing method in accordance with an aspect of the present invention comprises a step of irradiating an object to be processed with laser light such that a light-converging point of laser light elliptically polarized with an ellipticity of other than 1 is located within the object to be processed while the major axis of an ellipse indicative of the elliptical polarization of the laser light extends along a line along which the object is intended to be cut under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 ns or less at the light-converging point, so as to form a modified region including a refractive index change region which is a region with a changed refractive index within the object along a line along which the object is intended to be cut in the object.
[0037] The laser processing method in accordance with this aspect of the present invention irradiates the object to be processed with laser light such that the major axis of the ellipse indicative of the elliptical polarization of laser light extends along the line along which the object is intended to be cut in the object to be processed, thus making it possible to form the modified region efficiently and cut the object precisely along the line along which the object is intended to be cut as in the laser processing method in accordance with the above-mentioned aspect of the present invention.
[0038] Modes employable in the laser processing methods in accordance with the foregoing aspects of the present invention are as follows:
[0039] Laser light having elliptical polarization with an ellipticity of zero can be used. Linearly polarized light is obtained when the ellipticity is zero. Linearly polarized light can maximize the size of the modified region extending along the line along which the object is intended to be cut and minimize the sizes in the other directions. The ellipticity of elliptically polarized light can be adjusted by the angle of direction of a quarter-wave plate. When a quarter-wave plate is used, the ellipticity can be adjusted by changing the angle of direction alone.
[0040] After the step of forming the modified region, the object to be processed may be irradiated with laser light while the polarization of laser light is rotated by about 90° by a half-wave plate. Also, after the step of forming the modified region, the object to be processed may be irradiated with laser light while the object to be processed is rotated by about 90° about the thickness direction of the object to be processed. These can form another modified region extending in a direction along the surface of the object to be processed and intersecting the former modified region. Therefore, for embodiment, respective modified regions extending along lines along which the object is intended to be cut in X- and Y-axis directions can be formed efficiently.
[0041] The laser processing method in accordance with an aspect of the present invention comprises a step of irradiating an object to be processed with laser light such that a light-converging point of laser light elliptically polarized with an ellipticity of other than 1 is located within the object to be processed while the major axis of an ellipse indicative of the elliptical polarization of the laser light extends along a line along which the object is intended to be cut, so as to cut the object to be processed along the line along which the object is intended to be cut.
[0042] The laser processing method in accordance with this aspect of the present invention irradiates the object to be processed with laser light such that the major axis of the ellipse indicative of the elliptical polarization of laser light extends along the line along which the object is intended to be cut in the object to be processed. Therefore, the object to be processed can be cut along the line along which the object is intended to be cut. The laser processing method in accordance with this aspect of the present invention can cut the object to be processed by making the object absorb laser light so as to melt the object upon heating. Also, the laser processing method in accordance with this aspect of the present invention may generate multiphoton absorption by irradiating the object to be processed with laser light, thereby forming a modified region within the object, and cut the object while using the modified region as a starting point.
[0043] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; ellipticity adjusting means for making the pulse laser light emitted from the laser light source attain elliptical polarization with an ellipticity of other than 1; major axis adjusting means for making a major axis of an ellipse indicative of the elliptical polarization of the pulse laser light adjusted by the ellipticity adjusting means extend along a line along which the object is intended to be cut in an object to be processed; light-converging means for converging the pulse laser light adjusted by the major axis adjusting means such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; means for locating the light-converging point of the pulse laser light converged by the light-converging point within the object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along the line along which the object is intended to be cut.
[0044] The laser processing apparatus in accordance with this aspect of the present invention enables laser cutting without generating melt or unnecessary fractures deviating from the line along which the object is intended to be cut in the surface of the object to be processed for the same reason as that in the laser processing methods in accordance with the above-mentioned aspects of the present invention. Also, it irradiates the object to be processed with laser light such that the major axis of the ellipse indicative of the elliptical polarization of laser light extends along the line along which the object is intended to be cut in the object to be processed, thus making it possible to form the modified region efficiently and cut the object precisely along the line along which the object is intended to be cut with the laser processing methods in accordance with the above-mentioned aspects of the present invention.
[0045] Modes employable in the laser processing apparatus in accordance with the present invention are as follows:
[0046] It may comprise 90° rotation adjusting means adapted to rotate the polarization of the pulse laser light adjusted by the ellipticity adjusting means by about 90°. Also, it may comprise rotating means for rotating a table for mounting the object to be processed by about 90° about a thickness direction of the object. These can make the major axis of the ellipse indicative of the elliptical polarization of pulse laser light extend along another line along which the object is intended to be cut which extends in a direction along a surface of the object to be processed while extending in a direction intersecting along the former line along which the object is intended to be cut. Therefore, for embodiment, respective modified regions extending along lines along which the object is intended to be cut in X- and Y-axis directions can be formed efficiently.
[0047] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less and linear polarization; linear polarization adjusting means for making the direction of linear polarization of the pulse laser light emitted from the laser light source align with a line along which the object is intended to be cut in an object to be processed; light-converging means for converging the pulse laser light adjusted by the linear polarization adjusting means such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; means for locating the light-converging point of the pulse laser light converged by the light-converging point within the object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along the line along which the object is intended to be cut.
[0048] The laser processing apparatus in accordance with this aspect of the present invention enables laser cutting without generating melt or unnecessary fractures deviating from the line along which the object is intended to be cut in the surface of the object to be processed for the same reason as that in the laser processing methods in accordance with the above-mentioned aspects of the present invention. Also, as with the laser processing methods in accordance with the above-mentioned aspects of the present invention, the laser processing apparatus in accordance with this aspect of the present invention makes it possible to form the modified region efficiently and cut the object precisely along the line along which the object is intended to be cut.
[0049] (3) The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; power adjusting means for adjusting the magnitude of power of the pulse laser light emitted from the laser light source according to an input of the magnitude of power of pulse laser light; light-converging means for converging the pulse laser light adjusted by the linear polarization adjusting means such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; means for locating the light-converging point of the pulse laser light converged by the light-converging means within an object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; the laser processing apparatus further comprising correlation storing means having stored therein a correlation between the magnitude of power of pulse laser adjusted by the power adjusting means and the size of modified spot; size selecting means for choosing, according to an inputted magnitude of power of pulse laser light, a size of the modified spot formed at this magnitude of power from the correlation storing means; and size display means for displaying the size of modified spot chosen by the size selecting means.
[0050] The inventor has found that the modified spot can be controlled so as to become smaller and larger when the power of pulse laser light is made lower and higher, respectively. The modified spot is a modified part formed by one pulse of pulse laser light, whereas an assembly of modified spots forms a modified region. Control of the modified spot size affects cutting of the object to be processed. Namely, the accuracy in cutting the object to be processed along the line along which the object is intended to be cut and the flatness of the cross section deteriorate when the modified spot is too large. When the modified spot is too small for the object to be processed having a large thickness, on the other hand, the object is hard to cut. The laser processing apparatus in accordance with this aspect of the present invention can control the size of modified spot by adjusting the magnitude of power of pulse laser light. Therefore, it can cut the object to be processed precisely along the line along which the object is intended to be cut, and can obtain a flat cross section.
[0051] The laser processing apparatus in accordance with this aspect of the present invention also comprises correlation storing means having stored therein a correlation between the magnitude of power of pulse laser adjusted by the power adjusting means and the size of modified spot. According to an inputted magnitude of power of pulse laser light, the size of modified spot formed at this magnitude of power is chosen from the correlation storing means, and thus chosen size of modified spot is displayed. Therefore, the size of modified spot formed at the magnitude of power of pulse laser light fed into the laser processing apparatus can be seen before laser processing.
[0052] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; a light-converging lens for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; numerical aperture adjusting means for adjusting the size of numerical aperture of an optical system including the light-converging lens according to an inputted size of numerical aperture; means for locating the light-converging point of the pulse laser light converged by the light-converging lens within an object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; the laser processing apparatus further comprising correlation storing means having stored therein a correlation between the size of numerical aperture adjusted by the power adjusting means and the size of modified spot; size selecting means for choosing, according to an inputted magnitude of power of pulse laser light, a size of the modified spot formed at this size of numerical aperture from the correlation storing means; and size display means for displaying the size of modified spot chosen by the size selecting means.
[0053] The inventor has found that the modified spot can be controlled so as to become smaller and larger when the numerical aperture of the optical system including the light-converging lens is made greater and smaller, respectively. Thus, the laser processing apparatus in accordance with this aspect of the present invention can control the size of modified spot by adjusting the size of numerical aperture of the optical system including the light-converging lens.
[0054] The laser processing apparatus in accordance with this aspect of the present invention also comprises correlation storing means having stored therein a correlation between the size of numerical aperture and the size of modified spot. According to an inputted size of numerical aperture, the size of modified spot formed at this magnitude of power is chosen from the correlation storing means, and thus chosen size of modified spot is displayed. Therefore, the size of modified spot formed at the size of numerical aperture fed into the laser processing apparatus can be seen before laser processing.
[0055] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; and lens selecting means including a plurality of light-converging lenses for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point, the lens selecting means being adapted to select among a plurality of light-converging lenses, a plurality of optical systems including the light-converging lenses having respective numerical apertures different from each other; means for locating the light-converging point of the pulse laser light converged by a light-converging lens chosen by the lens selecting means within an object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; the laser processing apparatus further comprising correlation storing means having stored therein a correlation between sizes of numerical apertures of a plurality of optical systems including the light-converging lenses and the size of modified spot; size selecting means for choosing, according to a size of numerical aperture of an optical system including a chosen light-converging lens, a size of the modified spot formed at this size of numerical aperture from the correlation storing means; and size display means for displaying the size of modified spot chosen by the size selecting means.
[0056] The laser processing apparatus in accordance with the present invention can control the size of modified spot. Also, the size of modified spot formed at the size of numerical aperture of the optical system including the chosen light-converging lens can be seen before laser processing.
[0057] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; power adjusting means for adjusting the magnitude of power of pulse laser light emitted from the laser light source according to an inputted magnitude of power of pulse laser light; a light-converging lens for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; numerical aperture adjusting means for adjusting the size of numerical aperture of an optical system including the light-converging lens according to an inputted size of numerical aperture; means for locating the light-converging point of the pulse laser light converged by the light-converging lens within an object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; the laser processing apparatus further comprising correlation storing means having stored therein a correlation between a set of the magnitude of power of pulse laser light adjusted by the power adjusting means and the size of numerical aperture adjusted by the numerical aperture adjusting means and the size of modified spot; size selecting means for choosing, according to an inputted magnitude of power of pulse laser light and an inputted size of numerical aperture, a size of the modified spot formed at thus inputted magnitude and size; and size display means for displaying the size of modified spot chosen by the size selecting means.
[0058] The laser processing apparatus in accordance with this aspect of the present invention can combine power adjustment with numerical aperture adjustment, thus being able to increase the number of kinds of controllable dimensions of modified spots. Also, for the same reason as that of the laser processing apparatus in accordance with the present invention, the size of modified spot can be seen before laser processing.
[0059] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; power adjusting means for adjusting the magnitude of power of pulse laser light emitted from the laser light source according to an inputted magnitude of power of pulse laser light; lens selecting means including a plurality of light-converging lenses for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point, the lens selecting means being adapted to select among a plurality of light-converging lenses, a plurality of optical systems including the light-converging lenses having respective numerical apertures different from each other; means for locating the light-converging point of the pulse laser light converged by a light-converging lens chosen by the lens selecting means within an object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; the laser processing apparatus further comprising correlation storing means having stored therein a correlation between a set of the magnitude of power of pulse laser light adjusted by the power adjusting means and sizes of numerical apertures of a plurality of optical systems including the light-converging lenses and the size of modified spot; size selecting means for choosing, according to an inputted magnitude of power of pulse laser light and an inputted size of numerical aperture, a size of the modified spot formed at thus inputted magnitude and size; and size display means for displaying the size of modified spot chosen by the size selecting means.
[0060] For the same reason as that of the laser processing apparatus in accordance with the above-mentioned aspect of the present invention, the laser processing apparatus in accordance with this aspect of the present invention can increase the number of kinds of controllable dimensions of modified spots and can see the size of modified spots before laser processing.
[0061] The laser processing apparatus explained in the foregoing may comprise image preparing means for preparing an image of modified spot having the size selected by the size selecting means, and image display means for displaying the image prepared by the image preparing means. This allows the formed modified spot to be grasped visually before laser processing.
[0062] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; power adjusting means for adjusting the magnitude of power of pulse laser light emitted from the laser light source; light-converging means for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; means for locating the light-converging point of the pulse laser light converged by the light-converging means within an object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; the laser processing apparatus further comprising correlation storing means having stored therein a correlation between the magnitude of power of pulse laser light adjusted by the power adjusting means and the size of modified spot; power selecting means for choosing, according to an inputted size of modified spot, a magnitude of power of pulse laser light adapted to form this size from the correlation storing means; the power adjusting means adjusting the magnitude of power of pulse laser light emitted from the laser light source such that the magnitude of power chosen by the power selecting means is attained.
[0063] The laser processing apparatus in accordance with this aspect of the present invention comprises correlation storing means having stored therein the magnitude of power of pulse laser light and the size of modified spot. According to an inputted size of the modified spot, the magnitude of power of pulse laser light adapted to form this size is chosen from the correlation storing means. The power adjusting means adjusts the magnitude of power of pulse laser light emitted from the laser light source so as to make it become the magnitude of power chosen by the power selecting means. Therefore, a modified spot having a desirable size can be formed.
[0064] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; a light-converging lens for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; numerical aperture adjusting means for adjusting the size of numerical aperture of an optical system including the light-converging lens according to an inputted size of numerical aperture; means for locating the light-converging point of the pulse laser light converged by the light-converging lens within an object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; the laser processing apparatus further comprising correlation storing means having stored therein a correlation between the size of numerical aperture adjusted by the numerical aperture adjusting means and the size of modified spot; and numerical aperture selecting means for choosing, according to an inputted size of modified spot, the size of numerical aperture adapted to form thus inputted size; the numerical aperture adjusting means adjusting the size of numerical aperture of the optical system including the light-converging lens such that the size of numerical aperture chosen by the numerical aperture selecting means is attained.
[0065] The laser processing apparatus in accordance with this aspect of the present invention comprises correlation storing means having stored therein the size of numerical aperture and the size of modified spot. According to an inputted size of modified spot, the size of numerical aperture adapted to form thus inputted size is chosen from the correlation storing means. The numerical aperture adjusting means adjusts the size of numerical aperture of the optical system including the light-converging lens such that the size of numerical aperture chosen by the numerical aperture selecting means is attained. Therefore, modified spots having a desirable size can be formed.
[0066] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; lens selecting means including a plurality of light-converging lenses for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point, the lens selecting means being adapted to select among a plurality of light-converging lenses, a plurality of optical systems including the light-converging lenses having respective numerical apertures different from each other; means for locating the light-converging point of the pulse laser light converged by a light-converging lens chosen by the lens selecting means within an object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; the laser processing apparatus further comprising correlation storing means having stored therein a correlation between sizes of numerical apertures of a plurality of light-converging lenses and the size of modified spot; and numerical aperture selecting means for choosing, according to an inputted size of modified spot, a size of numerical aperture adapted to form thus inputted size; the lens selecting means selecting among a plurality of light-converging lenses such that the size of numerical aperture chosen by the numerical aperture selecting means is attained.
[0067] According to an inputted size of modified spot, the laser processing apparatus in accordance with this aspect of the present invention chooses the size of numerical aperture adapted to form thus inputted size. The lens selecting means selects among a plurality of light-converging lenses such that the size of numerical aperture chosen by the numerical aperture selecting means is attained. Therefore, modified spots having a desirable spots can be formed.
[0068] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; power adjusting means for adjusting the magnitude of power of pulse laser light emitted from the laser light source; a light-converging lens for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; numerical aperture adjusting means for adjusting the size of numerical aperture of an optical system including the light-converging lens; means for locating the light-converging point of the pulse laser light converged by the light-converging lens within an object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; the laser processing apparatus further comprising correlation storing means having stored therein a correlation between a set of the magnitude of power of pulse laser light adjusted by the power adjusting means and the size of numerical aperture adjusted by the numerical aperture adjusting means and the size of modified spot; and set selecting means for choosing, according to an inputted size of modified spot, a set of the magnitude of power and size of numerical aperture adapted to form this size; the power adjusting means and numerical aperture adjusting means adjusting the magnitude of power of pulse laser light emitted from the laser light source and the size of numerical aperture of the optical system including the light-converging lens such that the magnitude of power and size of numerical aperture chosen by the set selecting means are attained.
[0069] According to an inputted size of modified spot, the laser processing apparatus in accordance with this aspect of the present invention chooses a combination of the magnitude of power and size of numerical aperture adapted to form thus inputted size from the correlation storing means. Then, it adjusts the magnitude of power of pulse laser light and the size of numerical aperture of the optical system including the light-converging lens so as to attain the chosen magnitude of power and size of numerical aperture. Therefore, modified spots having a desirable size can be formed. Also, since the magnitude of power and the size of numerical aperture are combined together, the number of kinds of controllable dimensions of modified spots can be increased.
[0070] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; power adjusting means for adjusting the magnitude of power of pulse laser light emitted from the laser light source; lens selecting means including a plurality of light-converging lenses for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point, the lens selecting means being adapted to select among a plurality of light-converging lenses, a plurality of optical systems including the light-converging lenses having respective numerical apertures different from each other; means for locating the light-converging point of the pulse laser light converged by a light-converging lens chosen by the lens selecting means within an object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; the laser processing apparatus further comprising correlation storing means having stored therein a correlation between a set of the magnitude of power of pulse laser light adjusted by the power adjusting means and sizes of numerical apertures of a plurality of optical systems including the light-converging lenses and the size of modified spot; and set selecting means for choosing, according to an inputted size of modified spot, a set of the magnitude of power and size of numerical aperture adapted to form thus inputted size from the correlation storing means; the power adjusting means and lens selecting means adjusting the magnitude of power of pulse laser light emitted from the laser light source and selecting among a plurality of light-converging lenses so as to attain the power and size of numerical aperture chosen by the set selecting means.
[0071] According to an inputted size of modified spot, the laser processing apparatus in accordance with this aspect of the present invention chooses a combination of the magnitude of power and size of numerical aperture adapted to form thus inputted size from the correlation storing means. It adjusts the magnitude of power of pulse laser light emitted from the laser light source and selects among a plurality of light-converging lenses so as to attain the chosen magnitude of power and size of numerical aperture, respectively. Therefore, modified spots having a desirable size can be formed. Also, since the magnitude of power and the size of numerical aperture are combined together, the number of kinds of controllable dimensions of modified spots can be increased.
[0072] The laser processing apparatus in accordance with this aspect of the present invention may further comprise display means for displaying the magnitude of power chosen by the power selecting means, display means for displaying the size of numerical aperture chosen by the numerical aperture selecting means, and display means for displaying the magnitude of power and size of numerical aperture of the set chosen by the set selecting means. This makes it possible to see the power and numerical aperture when the laser processing apparatus operates according to an inputted size of modified spot.
[0073] The laser processing apparatus can form a plurality of modified spots along a line along which the object is intended to be cut within the object to be processed. These modified spots define a modified region. The modified region includes at least one of a crack region where a crack is generated within the object to be processed, a molten processed region which is melted within the object to be processed, and a refractive index change region where refractive index is changed within the object to be processed.
[0074] An embodiment of modes of power adjusting means is one including at least one of an ND filter and a polarization filter. In another mode, the laser light source includes a pumping laser whereas the laser processing apparatus comprises driving current controlling means for controlling the driving current of the pumping laser. These can adjust the magnitude of power of pulse laser light. An embodiment of modes of numerical aperture adjusting means includes at least one of a beam expander and an iris diaphragm.
[0075] The laser processing method in accordance with an aspect of the present invention comprises a first step of irradiating an object to be processed with pulse laser light while locating a light-converging point of the pulse laser light within the object, so as to form a first modified region caused by multiphoton absorption within the object along a first line along which the object is intended to be cut in the object; and a second step of irradiating the object with pulse laser light while making the pulse laser light attain a power higher or lower than that in the first step and locating the light-converging point of the pulse laser light within the object, so as to form a second modified region caused by multiphoton absorption within the object along a second line along which the object is intended to be cut in the object.
[0076] The laser processing method in accordance with an aspect of the present invention comprises a first step of irradiating an object to be processed with pulse laser light while locating a light-converging point of the pulse laser light within the object, so as to form a first modified region caused by multiphoton absorption within the object along a first line along which the object is intended to be cut in the object; and a second step of irradiating the object with pulse laser light while making an optical system including a light-converging lens for converging the pulse laser light attain a numerical aperture greater or smaller than that in the first step and locating the light-converging point of the pulse laser light within the object, so as to form a second modified region caused by multiphoton absorption within the object along a second line along which the object is intended to be cut in the object.
[0077] When respective directions which are easy to cut and hard to cut exist due to the crystal orientation, for embodiment, the laser processing methods in accordance with these aspects of the present invention decreases the size of modified spot constituting a modified region formed in the easy-to-cut direction and increases the size of modified spot constituting another modified region formed in the hard-to-cut direction. This can attain a flat cross section in the easy-to-cut direction and enables cutting in the hard-to-cut direction as well.
[0078] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; frequency adjusting means for adjusting the magnitude of a repetition frequency of the pulse laser light emitted from the laser light source according to an inputted magnitude of frequency; light-converging means for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; means for locating the light-converging point of the pulse laser light converged by the light-converging means within an object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; and wherein a plurality of modified spots are formed along the line along which the object is intended to be cut within the object to be processed by irradiating the object to be processed with a plurality of pulses of pulse laser light while locating the light-converging point within the object and relatively moving the light-converging point along the line along which the object is intended to be cut; the laser processing apparatus further comprising distance calculating means for calculating a distance between modified spots adjacent each other according to an inputted magnitude of frequency; and distance display means for displaying the distance calculated by the distance calculating means.
[0079] The inventor has found that, when the light-converging point of pulse laser light has a fixed relative moving speed, the distance between a modified part (referred to as modified spot) formed by one pulse of pulse laser light and a modified spot formed by the next one pulse of laser light can be made greater by lowering the repetition frequency. It has been found that, by contrast, the distance can be made shorter by increasing the repetition frequency of pulse laser light. In the present specification, this distance is expressed as the distance or pitch between adjacent modified spots.
[0080] Therefore, the distance between the adjacent modified spots can be controlled by carrying out adjustment for increasing or decreasing the repetition frequency of pulse laser light. Changing the distance according to the kind, thickness, and the like of the object to be processed enables cutting in conformity to the object to be processed. Forming a plurality of modified spots along a line along which the object is intended to be cut within the object to be processed defines a modified region.
[0081] The laser processing apparatus in accordance with this aspect of the present invention calculates the distance between adjacent modified spots according to the inputted magnitude of frequency, and displays thus calculated distance. Therefore, with respect to modified spots formed according to the magnitude of frequency fed into the laser processing apparatus, the distance between adjacent spots can be seen before laser processing.
[0082] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; light-converging means for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; means for locating the light-converging point of the pulse laser light converged by the light-converging means within an object to be processed; moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; and speed adjusting means for adjusting the magnitude of relative moving speed of the light-converging point of pulse laser light caused by the moving means according to an inputted magnitude of speed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; and wherein a plurality of modified spots are formed along the line along which the object is intended to be cut within the object to be processed by irradiating the object to be processed with a plurality of pulses of pulse laser light while locating the light-converging point within the object and relatively moving the light-converging point along the line along which the object is intended to be cut; the laser processing apparatus further comprising distance calculating means for calculating a distance between modified spots adjacent each other according to an inputted magnitude of speed; and distance display means for displaying the distance calculated by the distance calculating means.
[0083] The inventor has found that, when the light-converging point of pulse laser light has a fixed relative moving speed, the distance between adjacent modified spots can be made shorter and longer by decreasing and increasing the relative moving speed of the light-converging point of pulse laser light, respectively. Therefore, the distance between adjacent modified spots can be controlled by increasing or decreasing the relative moving speed of the light-converging point of pulse laser light. As a consequence, a cutting process suitable for an object to be processed is possible by changing the distance according to the kind, thickness, and the like of the object to be processed. The relative movement of the light-converging point of pulse laser light may be achieved by moving the object to be processed while fixing the light-converging point of pulse laser light, by moving the light-converging point of pulse laser light while fixing the object to be processed, or by moving both.
[0084] The laser processing apparatus in accordance with this aspect of the present invention calculates the distance between adjacent modified spots according to the inputted magnitude of speed, and displays thus calculated distance. Therefore, with respect to modified spots formed according to the magnitude of speed fed into the laser processing apparatus, the distance between adjacent spots can be seen before laser processing.
[0085] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; frequency adjusting means for adjusting the magnitude of a repetition frequency of the pulse laser light emitted from the laser light source according to an inputted magnitude of frequency; light-converging means for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; means for locating the light-converging point of the pulse laser light converged by the light-converging means within an object to be processed; moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; and speed adjusting means for adjusting the magnitude of relative moving speed of the light-converging point of pulse laser light caused by the moving means according to an inputted magnitude of speed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; and wherein a plurality of modified spots are formed along the line along which the object is intended to be cut within the object to be processed by irradiating the object to be processed with a plurality of pulses of pulse laser light while locating the light-converging point within the object and relatively moving the light-converging point along the line along which the object is intended to be cut; the laser processing apparatus further comprising distance calculating means for calculating a distance between modified spots adjacent each other according to inputted magnitudes of frequency and speed; and distance display means for displaying the distance calculated by the distance calculating means.
[0086] The laser processing apparatus in accordance with this aspect of the present invention adjusts both the magnitude of a repetition frequency of pulse laser light and the magnitude of relative moving speed of the light-converging point, thereby being able to control the distance between adjacent modified spots. Combining these adjustments makes it possible to increase the number of kinds of controllable dimensions concerning the distance. Also, the laser processing apparatus in accordance with this aspect of the present invention allows the distance between adjacent modified spots to be seen before laser processing.
[0087] These laser processing apparatus may further comprise size storing means having stored therein the size of a modified spot formed by the laser processing apparatus; image preparing means for preparing an image of a plurality of modified spots formed along a line along which the object is intended to be cut according to the size stored in the size storing means and the distance calculated by the distance calculating means; and image display means for displaying the image prepared by the image preparing means. This allows a plurality of modified spots, i.e., modified region, to be grasped visually before laser processing.
[0088] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; frequency adjusting means for adjusting the magnitude of a repetition frequency of the pulse laser light emitted from the laser light source according to an inputted magnitude of frequency; light-converging means for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; means for locating the light-converging point of the pulse laser light converged by the light-converging means within an object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; and wherein a plurality of modified spots are formed along the line along which the object is intended to be cut within the object to be processed by irradiating the object to be processed with a plurality of pulses of pulse laser light while locating the light-converging point within the object and relatively moving the light-converging point along the line along which the object is intended to be cut; the laser processing apparatus further comprising frequency calculating means for calculating, according to an inputted magnitude of distance between modified spots adjacent each other, the magnitude of repetition frequency of the pulse laser light emitted from the laser light source so as to attain thus inputted magnitude of distance between the modified spots adjacent each other; the frequency adjusting means adjusting the magnitude of repetition frequency of the pulse laser light emitted from the laser light source such that the magnitude of frequency calculated by the frequency calculating means is attained.
[0089] According to an inputted magnitude of distance between adjacent modified spots, the laser processing apparatus in accordance with this aspect of the present invention calculates the magnitude of a repetition frequency of the pulse laser light emitted from the laser light source such that this magnitude of distance is attained between the adjacent modified spots. The frequency adjusting means adjusts the magnitude of repetition frequency of the pulse laser light emitted from the laser light source such that the magnitude of frequency calculated by the frequency calculating means is attained. Therefore, a desirable magnitude of distance can be attained between adjacent modified spots.
[0090] The laser processing apparatus in accordance with this aspect of the present invention may further comprise frequency display means for displaying the magnitude of frequency calculated by the frequency calculating means. When operating the laser processing apparatus according to the inputted magnitude of distance between adjacent modified spots, this allows the frequency to be seen before laser processing.
[0091] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; light-converging means for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; means for locating the light-converging point of the pulse laser light converged by the light-converging means within an object to be processed; moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; and speed adjusting means for adjusting the magnitude of relative moving speed of the light-converging point caused by the moving means; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; and wherein a plurality of modified spots are formed along the line along which the object is intended to be cut within the object to be processed by irradiating the object to be processed with a plurality of pulses of pulse laser light while locating the light-converging point within the object and relatively moving the light-converging point along the line along which the object is intended to be cut; the laser processing apparatus further comprising speed calculating means for calculating, according to an inputted magnitude of distance between modified spots adjacent each other, the magnitude of relative moving speed of the pulse laser light so as to attain thus inputted magnitude of distance between the modified spots adjacent each other; the speed adjusting means adjusting the magnitude of relative moving speed of the light-converging point of pulse laser light caused by the moving means such that the magnitude of relative moving speed calculated by the speed calculating means is attained.
[0092] According to an inputted magnitude of distance between adjacent modified spots, the laser processing apparatus in accordance with this aspect of the present invention calculates the magnitude of relative moving speed of the light-converging point of pulse laser light caused by the moving means. The speed adjusting means adjusts the magnitude of relative moving speed of the light-converging point of pulse laser light caused by the moving means such that the magnitude of relative moving speed calculated by the frequency calculating means is attained. Therefore, a desirable magnitude of distance can be attained between adjacent modified spots.
[0093] The laser processing apparatus in accordance with this aspect of the present invention may further comprise speed display means for displaying the magnitude of relative moving speed calculated by the speed calculating means. When operating the laser processing apparatus according to the inputted magnitude of distance between adjacent modified spots, this allows the relative moving speed to be seen before laser processing.
[0094] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; frequency adjusting means for adjusting the magnitude of a repetition frequency of the pulse laser light emitted from the laser light source; light-converging means for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; means for locating the light-converging point of the pulse laser light converged by the light-converging means within an object to be processed; moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed; and speed adjusting means for adjusting the magnitude of relative moving speed of the light-converging point caused by the moving means; wherein one modified spot is formed within the object to be processed by irradiating the object to be processed with one pulse of pulse laser light while locating the light-converging point within the object; and wherein a plurality of modified spots are formed along the line along which the object is intended to be cut within the object to be processed by irradiating the object to be processed with a plurality of pulses of pulse laser light while locating the light-converging point within the object and relatively moving the light-converging point along the line along which the object is intended to be cut; the laser processing apparatus further comprising combination calculating means for calculating, according to an inputted magnitude of distance between modified spots adjacent each other, a combination of the magnitude of repetition frequency of the pulse laser light emitted from the laser light source and the magnitude of relative moving speed of the light-converging point of pulse laser light caused by the moving means so as to attain thus inputted magnitude of distance between the modified spots adjacent each other; the frequency adjusting means adjusting the magnitude of repetition frequency of the pulse laser light emitted from the laser light source such that the magnitude of frequency calculated by the combination calculating means is attained; the speed adjusting means adjusting the magnitude of relative moving speed of the light-converging point of pulse laser light caused by the moving means such that the magnitude of relative moving speed calculated by the combination calculating means is attained.
[0095] The laser processing apparatus in accordance with this aspect of the present invention calculates, according to an inputted magnitude of distance between adjacent modified spots, a combination of the magnitude of repetition frequency of pulse laser light and the relative moving speed of the light-converging point of pulse laser light such that thus inputted magnitude of distance is attained between the adjacent modified spots. The frequency adjusting means and speed adjusting means adjust the magnitude of repetition frequency and the magnitude of relative moving speed of the light-converging point of pulse laser light so as to attain the values of calculated combination. Therefore, a desirable magnitude of distance can be attained between adjacent modified spots.
[0096] The laser processing apparatus in accordance with the present invention may comprise display means for displaying the magnitude of frequency and magnitude of relative moving speed calculated by the combination calculating means. When operating the laser processing apparatus according to the inputted magnitude of distance between adjacent modified spots, this allows the combination of frequency and relative moving speed to be seen before laser processing.
[0097] The laser processing apparatus in accordance with all the foregoing aspects of the present invention can form a plurality of modified spots along a line along which the object is intended to be cut within the object to be processed. These modified spots define a modified region. The modified region includes at least one of a crack region where a crack is generated within the object to be processed, a molten processed region which is melted within the object to be processed, and a refractive index change region where refractive index is changed within the object to be processed.
[0098] The laser processing apparatus in accordance with all the foregoing aspects of the present invention can adjust the distance between adjacent modified spots, thereby being able to form a modified region continuously or discontinuously along a line along which the object is intended to be cut. Forming the modified region continuously makes it easier to cut the object to be processed while using the modified region as compared with the case where it is not formed continuously. When the modified region is formed discontinuously, the modified region is discontinuous along the line along which the object is intended to be cut, whereby the part of the line along which the object is intended to be cut keeps a strength to a certain extent.
[0099] The laser processing method in accordance with an aspect of the present invention comprises a step of irradiating an object to be processed with laser light while locating a light-converging point of laser light within the object to be processed, so as to form a modified region caused by multiphoton absorption within the object along a line along which the object is intended to be cut in the object, and changing the position of the light-converging point of laser light in the direction of incidence of the laser light irradiating the object to be processed with respect to the object to be processed, so as to form a plurality of modified regions aligning with each other along the direction of incidence.
[0100] By changing the position of the light-converging point of laser light irradiating the object to be processed in the direction of incidence with respect to the object to be processed, the laser processing method in accordance with this aspect of the present invention forms a plurality of modified regions aligning with each other along the direction of incidence. This can increase the number of positions to become starting points when cutting the object to be processed. Therefore, the object to be processed can be cut even in the case where the object to be processed has a relatively large thickness and the like. Embodiments of the direction of incidence include the thickness direction of the object to be processed and directions orthogonal to the thickness direction.
[0101] The laser processing method in accordance with an aspect of the present invention comprises a step of irradiating an object to be processed with laser light while locating a light-converging point of laser light within the object to be processed, so as to form a modified region within the object along a line along which the object is intended to be cut in the object, and changing the position of the light-converging point of laser light in the direction of incidence of the laser light irradiating the object to be processed with respect to the object to be processed, so as to form a plurality of modified regions aligning with each other along the direction of incidence. The laser processing method in accordance with an aspect of the present invention comprises a step of irradiating an object to be processed with laser light while locating a light-converging point of laser light within the object to be processed under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 μs or less at the light-converging point, so as to form a modified region within the object to be processed along a line along which the object is intended to be cut in the object, and changing the position of the light-converging point of laser light in the direction of incidence of the laser light irradiating the object to be processed with respect to the object to be processed, so as to form a plurality of modified regions aligning with each other along the direction of incidence.
[0102] For the same reason as that in the laser processing methods in accordance with the foregoing aspects of the present invention, the laser processing methods in accordance with these aspects of the present invention enable laser cutting without generating melt or unnecessary fractures deviating from the line along which the object is intended to be cut in the surface of the object to be processed, and can increase the number of positions to become starting points when cutting the object to be processed. The modified region may be caused by multiphoton absorption or other reasons.
[0103] The laser processing methods in accordance with these aspects of the present invention include the following modes:
[0104] A plurality of modified regions may be formed successively from the side farther from an entrance face of the object to be processed on which laser light irradiating the object to be processed is incident. This can form a plurality of modified regions while in a state where no modified region exists between the entrance face and the light-converging point of laser light. Therefore, the laser light will not be scattered by modified regions which have already been formed, whereby each modified region can be formed uniformly.
[0105] The modified region includes at least one of a crack region where a crack is generated within the object to be processed, a molten processed region which is melted within the object to be processed, and a refractive index change region where refractive index is changed within the object to be processed.
[0106] The laser processing method in accordance with an aspect of the present invention comprises a step of irradiating an object to be processed with laser light while locating a light-converging point of laser light within the object to be processed through a light entrance face of the laser light with respect to the object to be processed and locating the light-converging point at a position closer to or farther from the entrance face than is a half thickness position in the thickness direction of the object to be processed, so as to form a modified region within the object along a line along which the object is intended to be cut in the object.
[0107] In the laser processing method in accordance with the present invention, the modified region is formed on the entrance face (e.g., surface) and on the side of the face (e.g., rear face) opposing the entrance face within the object to be processed within the object to be processed when the light-converging point of laser light is located at a position closer to and farther from the entrance face than is a half thickness position in the thickness direction, respectively. When a fracture extending along a line along which the object is intended to be cut is generated on the surface or rear face of an object to be processed, the object can be cut easily. The laser processing method in accordance with this aspect of the present invention can form a modified region on the surface or rear face side within the object to be processed. This can make it easier to form the surface or rear face with a fracture extending along the line along which the object is intended to be cut, whereby the object to be processed can be cut easily. As a result, the laser processing method in accordance with this aspect of the present invention enables efficient cutting.
[0108] The laser processing method in accordance with this aspect of the present invention may be configured such that the entrance face is formed with at least one of an electronic device and an electrode pattern, whereas the light-converging point of laser light irradiating the object to be processed is located at a position closer to the entrance face than is the half thickness position in the thickness direction. The laser processing method in accordance with this aspect of the present invention grows a crack from the modified region toward the entrance face (e.g., surface) and its opposing face (e.g., rear face), thereby cutting the object to be processed. When the modified region is formed on the entrance face side, the distance between the modified region and the entrance face is relatively short, so that the deviation in the growth direction of crack can be made smaller. Therefore, when the entrance face of the object to be processed is formed with an electronic device or an electrode pattern, cutting is possible without damaging the electronic device or the like. The electronic device refers to a semiconductor device, a display device such as liquid crystal, a piezoelectric device, or the like.
[0109] The laser processing method in accordance with an aspect of the present invention comprises a first step of irradiating an object to be processed with pulse laser light while locating a light-converging point of the pulse laser light within the object, so as to form a first modified region caused by multiphoton absorption within the object along a first line along which the object is intended to be cut in the object; and a second step of irradiating, after the first step, the object with pulse laser light while locating the light-converging point of laser light at a position different from the light-converging point of laser light in the first step in the thickness direction of the object to be processed within the object, so as to form a second modified region caused by multiphoton absorption extending along a second line along which the object is intended to be cut and three-dimensionally crossing the first modified region within the object.
[0110] In a cutting process in which cross sections of an object to be processed cross each other, a modified region and another modified region are not superposed on each other at a location to become the crossing position between the cross sections in the laser processing method in accordance with this aspect of the present invention, whereby the cutting precision at the crossing position can be prevented from deteriorating. This enables cutting with a high precision.
[0111] The laser processing method in accordance with this aspect of the present invention can form the second modified region closer to the entrance face of the object to be processed with respect to the laser light than is the first modified region. This keeps the laser light irradiated at the time of forming the second modified region at the location to become the crossing position from being scattered by the first modified region, whereby the second modified region can be formed uniformly.
[0112] The laser processing methods in accordance with the foregoing aspects of the present invention explained in the foregoing have the following modes:
[0113] When the object to be processed is irradiated with laser light under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 μs or less at the light-converging point, a modified region including a crack region can be formed within the object to be processed. This generates a phenomenon of an optical damage caused by multiphoton absorption within the object to be processed. This optical damage induces a thermal distortion within the object to be processed, thereby forming a crack region within the object to be processed. This crack region is an embodiment of the above-mentioned modified region. An embodiment of the object to be processed in this laser processing method is a member including glass. The peak power density refers to the electric field intensity of pulse laser light at the light-converging point.
[0114] When the object to be processed is irradiated with laser light under a condition with a peak power density of at least 1×10 6 (W/cm 2 ) and a pulse width of 1 μs or less at the light-converging point, a modified region including a molten processed region can be formed within the object to be processed. Here, the inside of the object to be processed is locally heated by multiphoton absorption. This heating forms a molten processed region within the object to be processed. This molten processed region is an embodiment of the above-mentioned modified region. An embodiment of the object to be processed in this laser processing method is a member including a semiconductor material.
[0115] When the object to be processed is irradiated with laser light under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 ns or less at the light-converging point, a modified region including a refractive index change region which is a region with a changed refractive index can also be formed within the object to be processed. When multiphoton absorption is generated within the object to be processed with a very short pulse width as such, the energy caused by multiphoton absorption is not transformed into thermal energy, so that a permanent structural change such as ionic valence change, crystallization, or polarization orientation is induced within the object, whereby a refractive index change region is formed. This refractive index change region is an embodiment of the above-mentioned modified region. An embodiment of the object to be processed in this laser processing method is a member including glass.
[0116] Adjustment of the position of the light-converging point of laser light irradiating the object to be processed in the thickness direction can include a first calculating step of defining a desirable position in the thickness direction of the light-converging point of laser light irradiating the object to be processed as a distance from the entrance face to the inside and dividing the distance by the refractive index of the object to be processed with respect to the laser light irradiating the object, so as to calculate data of a first relative movement amount of the object in the thickness direction; a second calculating step of calculating data of a second relative movement amount of the object in the thickness direction required for positioning the light-converging point of laser light irradiating the object to be processed at the entrance face; a first moving step of relatively moving the object in the thickness direction according to the data of second relative movement amount; and a second moving step of relatively moving the object in the thickness direction according to the data of first relative movement amount after the first moving step. This adjusts the position of the light-converging point of laser light in the thickness direction of the object to be processed at a predetermined position within the object. Namely, with reference to the entrance face, the product of the relative movement amount of the object to be processed in the thickness direction of the object and the refractive index of the object with respect to the laser light irradiating the object becomes the distance from the entrance face to the light-converging point of laser light. Therefore, when the object to be processed is moved by the relative movement amount obtained by dividing the distance from the entrance to the inside of the object by the above-mentioned refractive index, the light-converging point of laser light can be aligned with a desirable position in the thickness direction of the object.
[0117] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; light-converging means for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; first moving means for relatively moving the light-converging point converged by the light-converging means along a line along which the object is intended to be cut in an object to be processed; storing means for storing data of a first relative movement amount of the object to be processed in the thickness direction for locating the light-converging position of pulse laser light converged by the light-converging means at a desirable position within the object to be processed, the data of first relative movement amount being obtained by defining the desirable position as a distance from the entrance face where the pulse laser light emitted from the laser light source enters the object to be processed to the inside thereof and dividing the distance by the refractive index of the object to be processed with respect to the pulse laser light emitted from the laser light source; calculating means for calculating data of a second relative movement amount of the object to be processed in the thickness direction required for locating the light-converging point of the pulse laser light converged by the light-converging means at the entrance face; and second moving means for relatively moving the object to be processed in the thickness direction according to the data of first relative movement amount stored by the storage means and the data of second relative movement amount calculated by the calculating means.
[0118] The laser processing apparatus in accordance with an aspect of the present invention comprises a laser light source for emitting pulse laser light having a pulse width of 1 μs or less; light-converging means for converging the pulse laser light emitted from the laser light source such that the pulse laser light attains a peak power density of at least 1×10 8 (W/cm 2 ) at a light-converging point; means for locating the light-converging point of the pulse laser light emitted from the laser light source within an object to be processed; means for adjusting the position of the pulse laser light converged by the light-converging means within the thickness of the object to be processed; and moving means for relatively moving the light-converging point of pulse laser light along a line along which the object is intended to be cut in the object to be processed.
[0119] For the same reason as that in the laser processing methods in accordance with the above-mentioned aspects of the present invention, the laser processing apparatus in accordance with these aspects of the present invention enable laser processing without generating melt or unnecessary fractures deviating from the line along which the object is intended to be cut in the surface of the object to be processed, and laser processing in which the position of the light-converging point of pulse laser light is regulated in the thickness direction of the object to be processed within the object.
[0120] The present invention will be more fully understood from the detailed description given hereinbelow and the accompanying drawings, which are given by way of illustration only and are not to be considered as limiting the present invention.
[0121] Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific embodiments, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will be apparent to those skilled in the art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0122] FIG. 1 is a plan view of an object to be processed during laser processing by the laser processing method in accordance with an embodiment;
[0123] FIG. 2 is a sectional view of the object to be processed shown in FIG. 1 taken along the line II-II;
[0124] FIG. 3 is a plan view of the object to be processed after laser processing effected by the laser processing method in accordance with the embodiment;
[0125] FIG. 4 is a sectional view of the object to be processed shown in FIG. 3 taken along the line IV-IV;
[0126] FIG. 5 is a sectional view of the object to be processed shown in FIG. 3 taken along the line V-V;
[0127] FIG. 6 is a plan view of the object to be processed cut by the laser processing method in accordance with the embodiment;
[0128] FIG. 7 is a graph showing relationships between the electric field intensity and the magnitude of crack in the laser processing method in accordance with the embodiment;
[0129] FIG. 8 is a sectional view of the object to be processed in a first step of the laser processing method in accordance with the embodiment;
[0130] FIG. 9 is a sectional view of the object to be processed in a second step of the laser processing method in accordance with the embodiment;
[0131] FIG. 10 is a sectional view of the object to be processed in a third step of the laser processing method in accordance with the embodiment;
[0132] FIG. 11 is a sectional view of the object to be processed in a fourth step of the laser processing method in accordance with the embodiment;
[0133] FIG. 12 is a view shoring a photograph of a cross section in a part of a silicon wafer cut by the laser processing method in accordance with the embodiment;
[0134] FIG. 13 is a graph showing relationships between the laser light wavelength and the transmittance within a silicon substrate in the laser processing method in accordance with the embodiment;
[0135] FIG. 14 is a schematic diagram of a laser processing apparatus usable in the laser processing method in accordance with a first embodiment of the embodiment;
[0136] FIG. 15 is a flowchart for explaining the laser processing method in accordance with the first embodiment of the present invention;
[0137] FIG. 16 is a plan view of an object to be processed for explaining a pattern which can be cut by the laser processing method in accordance with the first embodiment of the embodiment;
[0138] FIG. 17 is a schematic view for explaining the laser processing method in accordance with the first embodiment of the embodiment with a plurality of laser light sources;
[0139] FIG. 18 is a schematic view for explaining another laser processing method in accordance with the first embodiment of the embodiment with a plurality of laser light sources;
[0140] FIG. 19 is a schematic plan view showing a piezoelectric device wafer in a state held by a wafer sheet in the second embodiment of the embodiment;
[0141] FIG. 20 is a schematic sectional view showing a piezoelectric device wafer in a state held by the wafer sheet in the second embodiment of the embodiment;
[0142] FIG. 21 is a flowchart for explaining the cutting method in accordance with the second embodiment of the embodiment;
[0143] FIG. 22 is a sectional view of a light-transmitting material irradiated with laser light by the cutting method in accordance with the second embodiment of the embodiment;
[0144] FIG. 23 is a plan view of the light-transmitting material irradiated with laser light by the cutting method in accordance with the second embodiment of the embodiment;
[0145] FIG. 24 is a sectional view of the light-transmitting material shown in FIG. 23 taken along the line XXIV-XXIV;
[0146] FIG. 25 is a sectional view of the light-transmitting material shown in FIG. 23 taken along the line XXV-XXV;
[0147] FIG. 26 is a sectional view of the light-transmitting material shown in FIG. 23 taken along the line XXV-XXV when the light-converging point moving speed is made lower;
[0148] FIG. 27 is a sectional view of the light-transmitting material shown in FIG. 23 taken along the line XXV-XXV when the light-converging point moving speed is made further lower;
[0149] FIG. 28 is a sectional view of a piezoelectric device wafer or the like showing a first step of the cutting method in accordance with the second embodiment of the embodiment;
[0150] FIG. 29 is a sectional view of the piezoelectric device wafer or the like showing a second step of the cutting method in accordance with the second embodiment of the embodiment;
[0151] FIG. 30 is a sectional view of the piezoelectric device wafer or the like showing a third step of the cutting method in accordance with the second embodiment of the embodiment;
[0152] FIG. 31 is a sectional view of the piezoelectric device wafer or the like showing a fourth step of the cutting method in accordance with the second embodiment of the embodiment;
[0153] FIG. 32 is a sectional view of the piezoelectric device wafer or the like showing a fifth step of the cutting method in accordance with the second embodiment of the embodiment;
[0154] FIG. 33 is a view showing a photograph of a plane of a sample within which a crack region is formed upon irradiation with linearly polarized pulse laser light;
[0155] FIG. 34 is a view showing a photograph of a plane of a sample within which a crack region is formed upon irradiation with circularly polarized pulse laser light;
[0156] FIG. 35 is a sectional view of the sample shown in FIG. 33 taken along the line XXXV-XXXV;
[0157] FIG. 36 is a sectional view of the sample shown in FIG. 34 taken along the line XXXVI-XXXVI;
[0158] FIG. 37 is a plan view of the part of object to be processed extending along a line along which the object is intended to be cut, in which a crack region is formed by the laser processing method in accordance with a third embodiment of the embodiment;
[0159] FIG. 38 is a plan view of the part of object to be processed extending along a line along which the object is intended to be cut, in which a crack region is formed by a comparative laser processing method;
[0160] FIG. 39 is a view showing elliptically polarized laser light in accordance with the third embodiment of the embodiment, and a crack region formed thereby;
[0161] FIG. 40 is a schematic diagram of the laser processing apparatus in accordance with the third embodiment of the embodiment;
[0162] FIG. 41 is a perspective view of a quarter-wave plate included in an ellipticity regulator in accordance with the third embodiment of the embodiment;
[0163] FIG. 42 is a perspective view of a half-wave plate included in a 90° rotation regulator part in accordance with the third embodiment of the embodiment;
[0164] FIG. 43 is a flowchart for explaining the laser processing method in accordance with the third embodiment of the embodiment;
[0165] FIG. 44 is a plan view of a silicon wafer irradiated with elliptically polarized laser light by the laser processing method in accordance with the third embodiment of the embodiment;
[0166] FIG. 45 is a plan view of a silicon wafer irradiated with linearly polarized laser light by the laser processing method in accordance with the third embodiment of the embodiment;
[0167] FIG. 46 is a plan view of a silicon wafer in which the silicon wafer shown in FIG. 44 is irradiated with elliptically polarized laser light by the laser processing method in accordance with the third embodiment of the embodiment;
[0168] FIG. 47 is a plan view of a silicon wafer in which the silicon wafer shown in FIG. 45 is irradiated with linearly polarized laser light by the laser processing method in accordance with the third embodiment of the embodiment;
[0169] FIG. 48 is a schematic diagram of the laser processing apparatus in accordance with a fourth embodiment of the embodiment;
[0170] FIG. 49 is a plan view of a silicon wafer in which the silicon wafer shown in FIG. 44 is irradiated with elliptically polarized laser light by the laser processing method in accordance with the fourth embodiment of the embodiment;
[0171] FIG. 50 is a plan view of the object to be processed in the case where a crack spot is formed relatively large by using the laser processing method in accordance with a fifth embodiment of the embodiment;
[0172] FIG. 51 is a sectional view taken along LI-LI on the line along which the object is intended to be cut shown in FIG. 50 ;
[0173] FIG. 52 is a sectional view taken along LII-LII orthogonal to the line along which the object is intended to be cut shown in FIG. 50 ;
[0174] FIG. 53 is a sectional view taken along orthogonal to the line along which the object is intended to be cut shown in FIG. 50 ;
[0175] FIG. 54 is a sectional view taken along LIV-LIV orthogonal to the line along which the object is intended to be cut shown in FIG. 50 ;
[0176] FIG. 55 is a plan view of the object to be processed shown in FIG. 50 cut along the line along which the object is intended to be cut;
[0177] FIG. 56 is a sectional view of the object to be processed taken along the line along which the object is intended to be cut in the case where a crack spot is formed relatively small by using the laser processing method in accordance with the fifth embodiment of the embodiment;
[0178] FIG. 57 is a plan view of the object to be processed shown in FIG. 56 cut along the line along which the object is intended to be cut;
[0179] FIG. 58 is a sectional view of the object to be processed showing a state where pulse laser light is converged within the object by using a light-converging lens having a predetermined numerical aperture;
[0180] FIG. 59 is a sectional view of the object to be processed including a crack spot formed due to the multiphoton absorption caused by irradiation with laser light shown in FIG. 58 ;
[0181] FIG. 60 is a sectional view of the object to be processed in the case where a light-converging lens having a numerical aperture greater than that of the embodiment shown in FIG. 58 is used;
[0182] FIG. 61 is a sectional view of the object to be processed including a crack spot formed due to the multiphoton absorption caused by irradiation with laser light shown in FIG. 60 ;
[0183] FIG. 62 is a sectional view of the object to be processed in the case where pulse laser light having a power lower than that of the embodiment shown in FIG. 58 is used;
[0184] FIG. 63 is a sectional view of the object to be processed including a crack spot formed due to the multiphoton absorption caused by irradiation with laser light shown in FIG. 62 ;
[0185] FIG. 64 is a sectional view of the object to be processed in the case where pulse laser light having a power lower than that of the embodiment shown in FIG. 60 is used;
[0186] FIG. 65 is a sectional view of the object to be processed including a crack spot formed due to the multiphoton absorption caused by irradiation with laser light shown in FIG. 64 ;
[0187] FIG. 66 is a sectional view taken along LXVI-LXVI orthogonal to the line along which the object is intended to be cut shown in FIG. 57 ;
[0188] FIG. 67 is a schematic diagram showing the laser processing apparatus in accordance with the fifth embodiment of the embodiment;
[0189] FIG. 68 is a block diagram showing a part of an embodiment of overall controller provided in the laser processing apparatus in accordance with the fifth embodiment of the embodiment;
[0190] FIG. 69 is a view showing an embodiment of table of a correlation storing section included in the overall controller of the laser processing apparatus in accordance with the fifth embodiment of the embodiment;
[0191] FIG. 70 is a view showing another embodiment of the table of the correlation storing section included in the overall controller of the laser processing apparatus in accordance with the fifth embodiment of the embodiment;
[0192] FIG. 71 is a view showing still another embodiment of the table of the correlation storing section included in the overall controller of the laser processing apparatus in accordance with the fifth embodiment of the embodiment;
[0193] FIG. 72 is a schematic diagram of the laser processing apparatus in accordance with a sixth embodiment of the embodiment;
[0194] FIG. 73 is a view showing the convergence of laser light caused by a light-converging lens in the case where no beam expander is disposed;
[0195] FIG. 74 is a view showing the convergence of laser light caused by the light-converging lens in the case where a beam expander is disposed;
[0196] FIG. 75 is a schematic diagram of the laser processing apparatus in accordance with a seventh embodiment of the embodiment;
[0197] FIG. 76 is a view showing the convergence of laser light caused by the light-converging lens in the case where no iris diaphragm is disposed;
[0198] FIG. 77 is a view showing the convergence of laser light caused by the light-converging lens in the case where an iris diaphragm is disposed;
[0199] FIG. 78 is a block diagram showing an embodiment of overall controller provided in a modified embodiment of the laser processing apparatus in accordance with the embodiment;
[0200] FIG. 79 is a block diagram of another embodiment of overall controller provided in the modified embodiment of the laser processing apparatus in accordance with the embodiment;
[0201] FIG. 80 is a block diagram of still another embodiment of overall controller provided in the modified embodiment of the laser processing apparatus in accordance with the embodiment;
[0202] FIG. 81 is a plan view of an embodiment of the part of object to be processed extending along a line along which the object is intended to be cut, in which a crack region is formed by the laser processing method in accordance with an eighth embodiment of the embodiment;
[0203] FIG. 82 is a plan view of another embodiment of the part of object to be processed extending along the line along which the object is intended to be cut, in which a crack region is formed by the laser processing method in accordance with the eighth embodiment of the embodiment;
[0204] FIG. 83 is a plan view of still another embodiment of the part of object to be processed extending along the line along which the object is intended to be cut, in which a crack region is formed by the laser processing method in accordance with the eighth embodiment of the embodiment;
[0205] FIG. 84 is a schematic diagram of a Q-switch laser provided in a laser light source of the laser processing apparatus in accordance with the eighth embodiment of the embodiment;
[0206] FIG. 85 is a block diagram showing a part of an embodiment of overall controller of the laser processing apparatus in accordance with the eighth embodiment of the embodiment;
[0207] FIG. 86 is a block diagram showing a part of another embodiment of overall controller of the laser processing apparatus in accordance with the eighth embodiment of the embodiment;
[0208] FIG. 87 is a block diagram showing a part of still another embodiment of overall controller of the laser processing apparatus in accordance with the eighth embodiment of the embodiment;
[0209] FIG. 88 is a block diagram showing a part of still another embodiment of overall controller of the laser processing apparatus in accordance with the eighth embodiment of the embodiment;
[0210] FIG. 89 is a perspective view of an embodiment of the object to be processed within which a crack region is formed by using the laser processing method in accordance with a ninth embodiment of the embodiment;
[0211] FIG. 90 is a perspective view of the object to be processed formed with a crack extending from the crack region shown in FIG. 89 ;
[0212] FIG. 91 is a perspective view of another embodiment of the object to be processed within which a crack region is formed by using the laser processing method in accordance with the ninth embodiment of the embodiment;
[0213] FIG. 92 is a perspective view of still another embodiment of the object to be processed within which a crack region is formed by using the laser processing method in accordance with the ninth embodiment of the embodiment;
[0214] FIG. 93 is a view showing the state where a light-converging point of laser light is positioned on the surface of the object to be processed;
[0215] FIG. 94 is a view showing the state where a light-converging point of laser light is positioned within the object to be processed;
[0216] FIG. 95 is a flowchart for explaining the laser processing method in accordance with the ninth embodiment of the embodiment;
[0217] FIG. 96 is a perspective view of an embodiment of the object to be processed within which a crack region is formed by using the laser processing method in accordance with a tenth embodiment of the embodiment;
[0218] FIG. 97 is a partly sectional view of the object to be processed shown in FIG. 96 ;
[0219] FIG. 98 is a perspective view of another embodiment of the object to be processed within which a crack region is formed by using the laser processing method in accordance with the tenth embodiment of the embodiment;
[0220] FIG. 99 is a partly sectional view of the object to be processed shown in FIG. 98 ; and
[0221] FIG. 100 is a perspective view of still another embodiment of the object to be processed within which a crack region is formed by using the laser processing method in accordance with the tenth embodiment of the embodiment.
[0222] FIG. 101 is a flowchart for explaining the laser processing method in accordance with the eleventh embodiment of the present invention;
[0223] FIG. 102 is a sectional view of the object including a crack region during laser processing in the modified region forming step in accordance with the eleventh and twelfth embodiments.
[0224] FIG. 103 is a sectional view of the object including a crack region during laser processing in the stress step in accordance with the eleventh embodiment.
[0225] FIG. 104 is a flowchart for explaining the laser processing method in accordance with the twelfth embodiment of the present invention.
[0226] FIG. 105 is a sectional view of the object including a crack region during laser processing in the stress step in accordance with the twelfth embodiment.
[0227] FIG. 106 shows an film expansion apparatus used in the thirteenth embodiments.
[0228] FIG. 107 is for explanation of the expansion status of the adhesive and expansive sheet in the thirteenth embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0229] In the following, a preferred embodiment of the present invention will be explained with reference to the drawings. The laser processing method and laser processing apparatus of an embodiment in accordance with the present invention is embodiment form a modified region by multiphoton absorption. The multiphoton absorption is a phenomenon occurring when the intensity of laser light is made very high. First, the multiphoton absorption will be explained in brief.
[0230] A material becomes optically transparent when the energy hυ of a photon is lower than the band gap E G of absorption of the material. Therefore, the condition under which absorption occurs in the material is hυ>E G . Even when optically transparent, however, absorption occurs in the material under the condition of nhυ>E G (n=2, 3, 4, . . . ) when the intensity of laser light is made very high. This phenomenon is known as multiphoton absorption. In the case of pulse wave, the intensity of laser light is determined by the peak power density (W/cm 2 ) of laser light at the light-converging point, whereas the multiphoton absorption occurs under the condition with a peak power density of at least 1×10 8 (W/cm 2 ), for embodiment. The peak power density is determined by (energy of laser light at the light-converging point per pulse)/(beam spot cross-sectional area of laser light×pulse width). In the case of a continuous wave, the intensity of laser light is determined by the electric field intensity (W/cm 2 ) of laser light at the light-converging point.
[0231] The principle of laser processing in accordance with the embodiment utilizing such multiphoton absorption will now be explained with reference to FIGS. 1 to 6 . FIG. 1 is a plan view of an object to be processed 1 during laser processing. FIG. 2 is a sectional view of the object 1 shown in FIG. 1 taken along the line II-II. FIG. 3 is a plan view of the object 1 after laser processing. FIG. 4 is a sectional view of the object 1 shown in FIG. 3 taken along the line IV-IV. FIG. 5 is a sectional view of the object 1 shown in FIG. 3 taken along the line V-V. FIG. 6 is a plan view of the cut object 1 .
[0232] As shown in FIGS. 1 and 2 , the object 1 has a surface 3 with a line 5 along which the object is intended to be cut. The line 5 along which the object is intended to be cut is a linearly extending virtual line. In the laser processing of an embodiment in accordance with the present invention, the object 1 is irradiated with laser light L while locating a light-converging point P within the object 1 under a condition generating multiphoton absorption, so as to form a modified region 7 . The light-converging point refers to a location at which the laser light L is converged.
[0233] By relatively moving the laser light L along the line 5 along which the object is intended to be cut (i.e., along the direction of arrow A), the light-converging point P is moved along the line 5 along which the object is intended to be cut. This forms the modified region 7 along the line 5 along which the object is intended to be cut only within the object 1 as shown in FIGS. 3 to 5 . In the laser processing method in accordance with the embodiment, the modified region 7 is not formed by heating the object 1 due to the absorption of laser light L therein. The laser light L is transmitted through the object 1 , so as to generate multiphoton absorption therewithin, thereby forming the modified region 7 . Therefore, the laser light L is hardly absorbed at the surface 3 of the object 1 , whereby the surface 3 of the object 1 will not melt.
[0234] If a starting point exists in a part to be cut when cutting the object 1 , the object 1 will break from the starting point, whereby the object 1 can be cut with a relatively small force as shown in FIG. 6 . Hence, the object 1 can be cut without generating unnecessary fractures in the surface 3 of the object 1 .
[0235] The following two cases seem to exist in the cutting of the object to be processed using the modified region as a starting point. The first case is where, after the modified region is formed, an artificial force is applied to the object, whereby the object breaks while using the modified region as a starting point, and thus is cut. This is cutting in the case where the object to be processed has a large thickness, for embodiment. Applying an artificial force includes, for embodiment, applying a bending stress or shearing stress to the object along the line along which the object is intended to be cut in the object to be processed or imparting a temperature difference to the object so as to generate a thermal stress. Another case is where a modified region is formed, so that the object naturally breaks in the cross-sectional direction (thickness direction) of the object while using the modified region as a starting point, whereby the object is cut. This can be achieved by a single modified region when the thickness of the object is small, and by a plurality of modified regions formed in the thickness direction when the thickness of the object to be processed is large. Breaking and cutting can be carried out with favorable control even in this naturally breaking case, since breaks will not reach the part formed with no modified region on the surface in the part to be cut, so that only the part formed with the modified region can be broken and cut. Such a breaking and cutting method with favorable controllability is quite effective, since semiconductor wafers such as silicon wafers have recently been prone to decrease their thickness.
[0236] The modified region formed by multiphoton absorption in the embodiment includes the following (1) to (3):
[0237] (1) Case where the modified region is a crack region including one or a plurality of cracks
[0238] An object to be processed (e.g., glass or a piezoelectric material made of LiTaO 3 ) is irradiated with laser light while the light-converging point is located therewithin under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 μs or less at the light-converging point. This magnitude of pulse width is a condition under which a crack region can be formed only within the object to be processed while generating multiphoton absorption without causing unnecessary damages to the surface of the object. This generates a phenomenon of optical damage caused by multiphoton absorption within the object to be processed. This optical damage induces thermal distortion within the object to be processed, thereby forming a crack region therewithin. The upper limit of electric field intensity is 1×10 12 (W/cm 2 ), for embodiment. The pulse width is preferably 1 ns to 200 ns, for embodiment. The forming of a crack region caused by multiphoton absorption is described, for embodiment, in “Internal Marking of Glass Substrate by Solid-state Laser Harmonics”, Proceedings of 45 th Laser Materials Processing Conference (December 1998), pp. 23-28.
[0239] The inventor determined relationships between the electric field intensity and the magnitude of crack by an experiment. Conditions for the experiment are as follows:
[0240] (A) Object to be processed: Pyrex glass (having a thickness of 700 μm)
[0241] (B) Laser
Light source: semiconductor laser pumping Nd:YAG laser Wavelength: 1064 nm Laser light spot cross-sectional area: 3.14×10 −8 cm 2 Oscillation mode: Q-switch pulse Repetition frequency: 100 kHz Pulse width: 30 ns Output: output <1 mJ/pulse Laser light quality: TEM 00 Polarization characteristic: linear polarization
[0251] (C) Light-converging lens
Transmittance with respect to laser light wavelength: 60%
[0253] (D) Moving speed of a mounting table mounting the object to be processed: 100 mm/sec
[0254] The laser light quality of TEM 00 indicates that the light convergence is so high that light can be converged up to about the wavelength of laser light.
[0255] FIG. 7 is a graph showing the results of the above-mentioned experiment. The abscissa indicates peak power density. Since laser light is pulse laser light, its electric field intensity is represented by the peak power density. The ordinate indicates the size of a crack part (crack spot) formed within the object to be processed by one pulse of laser light. An assembly of crack spots forms a crack region. The size of a crack spot refers to that of the part of dimensions of the crack spot yielding the maximum length. The data indicated by black circles in the graph refers to a case where the light-converging glass (C) has a magnification of ×100 and a numerical aperture (NA) of 0.80. On the other hand, the data indicated by white circles in the graph refers to a case where the light-converging glass (C) has a magnification of ×50 and a numerical aperture (NA) of 0.55. It is seen that crack spots begin to occur within the object to be processed when the peak power density reaches 10 11 (W/cm 2 ), and become greater as the peak power density increases.
[0256] A mechanism by which the object to be processed is cut upon formation of a crack region in the laser processing in accordance with the embodiment will now be explained with reference to FIGS. 8 to 11 . As shown in FIG. 8 , the object to be processed 1 is irradiated with laser light L while locating the light-converging point P within the object 1 under a condition where multiphoton absorption occurs, so as to form a crack region 9 therewithin. The crack region 9 is a region including one or a plurality of cracks. As shown in FIG. 9 , the crack further grows while using the crack region 9 as a starting point. As shown in FIG. 10 , the crack reaches the surface 3 and rear face 21 of the object 1 . As shown in FIG. 11 , the object 1 breaks, so as to be cut. The crack reaching the surface and rear face of the object to be processed may grow naturally or grow as a force is applied to the object.
[0257] (2) Case where the modified region is a molten processed region
[0258] An object to be processed (e.g., a semiconductor material such as silicon) is irradiated with laser light while the light-converging point is located therewithin under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 μs or less at the light-converging point. As a consequence, the inside of the object to be processed is locally heated by multiphoton absorption. This heating forms a molten processed region within the object to be processed. The molten processed region refers to at least one of a region once melted and then re-solidified, a region in a melted state, and a region in the process of re-solidifying from its melted state. The molten processed region may also be defined as a phase-changed region or a region having changed its crystal structure. The molten processed region may also be regarded as a region in which a certain structure has changed into another structure in monocrystal, amorphous, and polycrystal structures. Namely, it refers to a region in which a monocrystal structure has changed into an amorphous structure, a region in which a monocrystal structure has changed into a polycrystal structure, and a region in which a monocrystal structure has changed into a structure including an amorphous structure and a polycrystal structure, for embodiment. When the object to be processed is a silicon monocrystal structure, the molten processed region is an amorphous silicon structure, for embodiment. The upper limit of electric field intensity is 1×10 12 (W/cm 2 ), for embodiment. The pulse width is preferably 1 ns to 200 ns, for embodiment.
[0259] By an experiment, the inventor has verified that a molten processed region is formed within a silicon wafer. Conditions for the experiment is as follows:
[0260] (A) Object to be processed: silicon wafer (having a thickness of 350 μm and an outer diameter of 4 inches)
[0261] (B) Laser
Light source: semiconductor laser pumping Nd:YAG laser Wavelength: 1064 nm Laser light spot cross-sectional area: 3.14×10 −8 cm 2 Oscillation mode: Q-switch pulse Repetition frequency: 100 kHz Pulse width: 30 ns Output: 20 μJ/pulse Laser light quality: TEM 00 Polarization characteristic: linear polarization
[0271] (C) Light-converging lens
Magnification: × 50 NA: 0.55 Transmittance with respect to laser light wavelength: 60%
[0275] (D) Moving speed of a mounting table mounting the object to be processed: 100 mm/sec
[0276] FIG. 12 is a view showing a photograph of a cross section in a part of a silicon wafer cut by laser processing under the above-mentioned conditions. A molten processed region 13 is formed within a silicon wafer 11 . The size of the molten processed region formed under the above-mentioned conditions is about 100 μm in the thickness direction.
[0277] The forming of the molten processed region 13 by multiphoton absorption will be explained. FIG. 13 is a graph showing relationships between the wavelength of laser light and the transmittance within the silicon substrate. Here, respective reflecting components on the surface and rear face sides of the silicon substrate are eliminated, whereby only the transmittance therewithin is represented. The above-mentioned relationships are shown in the cases where the thickness t of the silicon substrate is 50 μm, 100 μm, 200 μm, 500 μm, and 1000 μm, respectively.
[0278] For embodiment, it is seen that laser light transmits through the silicon substrate by at least 80% at 1064 nm, which is the wavelength of Nd:YAG laser, when the silicon substrate has a thickness of 500 μm or less. Since the silicon wafer 11 shown in FIG. 12 has a thickness of 350 μm, the molten processed region caused by multiphoton absorption is formed near the center of the silicon wafer, i.e., at a part separated from the surface by 175 μm. The transmittance in this case is 90% or greater with reference to a silicon wafer having a thickness of 200 μm, whereby the laser light is absorbed within the silicon wafer 11 only slightly and is substantially transmitted therethrough. This means that the molten processed region is not formed by laser light absorption within the silicon wafer 11 (i.e., not formed upon usual heating with laser light), but by multiphoton absorption. The forming of a molten processed region by multiphoton absorption is described, for embodiment, in “Processing Characteristic evaluation of Silicon by Picosecond Pulse Laser”, Preprints of the National Meeting of Japan Welding Society , No. 66 (April 2000), pp. 72-73.
[0279] Here, a fracture is generated in the cross-sectional direction while using the molten processed region as a starting point, whereby the silicon wafer is cut when the fracture reaches the surface and rear face of the silicon wafer. The fracture reaching the surface and rear face of the object to be processed may grow naturally or grow as a force is applied to the object. The fracture naturally grows from the molten processed region to the surface and rear face of the silicon wafer in one of the cases where the fracture grows from a region once melted and then re-solidified, where the fracture grows from a region in a melted state, and where the fracture grows from a region in the process of re-solidifying from a melted state. In any of these cases, the molten processed region is formed only within the cross section after cutting as shown in FIG. 12 . When a molten processed region is formed within the object to be processed, unnecessary fractures deviating from a line along which the object is intended to be cut are hard to occur at the time of breaking and cutting, which makes it easier to control the breaking and cutting.
[0280] (3) Case where the modified region is a refractive index change region
[0281] An object to be processed (e.g., glass) is irradiated with laser light while the light-converging point is located therewithin under a condition with a peak power density of at least 1×10 8 (W/cm 2 ) and a pulse width of 1 ns or less at the light-converging point. When multiphoton absorption is generated within the object to be processed with a very short pulse width, the energy caused by multiphoton absorption is not transformed into thermal energy, so that a permanent structural change such as ionic valence change, crystallization, or polarization orientation is induced within the object, whereby a refractive index change region is formed. The upper limit of electric field intensity is 1×10 12 (W/cm 2 ), for embodiment. The pulse width is preferably 1 ns or less, more preferably 1 μs or less, for embodiment. The forming of a refractive index change region by multiphoton absorption is described, for embodiment, in “Formation of Photoinduced Structure within Glass by Femtosecond Laser Irradiation”, Proceedings of 42 th Laser Materials Processing Conference (November 1997), pp. 105-111.
[0282] Specific embodiments according to the present invention will now be explained.
First Embodiment
[0283] The laser processing method in accordance with a first embodiment of the present invention will be explained. FIG. 14 is a schematic diagram of a laser processing apparatus 100 usable in this method. The laser processing apparatus 100 comprises a laser light source 101 for generating laser light L; a laser light source controller 102 for controlling the laser light source 101 so as to regulate the output and pulse width of laser light L and the like; a dichroic mirror 103 , arranged so as to change the orientation of the optical axis of laser light L by 90°, having a function of reflecting the laser light L; a light-converging lens 105 for converging the laser light L reflected by the dichroic mirror 103 ; a mounting table 107 for mounting an object to be processed irradiated with the laser light L converged by the light-converging lens 105 ; an X-axis stage 109 for moving the mounting table 107 in the X-axis direction; a Y-axis stage 111 for moving the mounting table 107 in the Y-axis direction orthogonal to the X-axis direction; a Z-axis stage 113 for moving the mounting table 107 in the Z-axis direction orthogonal to X- and Y-axis directions; and a stage controller 115 for controlling the movement of these three stages 109 , 111 , 113 .
[0284] The Z-axis direction is a direction orthogonal to the surface 3 of the object to be processed 1 , thus becoming the direction of focal depth of laser light L incident on the object 1 . Therefore, moving the Z-axis stage 113 in the Z-axis direction can locate the light-converging point P of laser light L within the object 1 . This movement of light-converging point P in X(Y)-axis direction is effected by moving the object 1 in the X(Y)-axis direction by the X(Y)-axis stage 109 ( 111 ). The X(Y)-axis stage 109 ( 111 ) is an embodiment of moving means.
[0285] The laser light source 101 is an Nd:YAG laser generating pulse laser light. Known as other kinds of laser usable as the laser light source 101 include Nd:YVO 4 laser, Nd:YLF laser, and titanium sapphire laser. For forming a crack region or molten processed region, Nd:YAG laser, Nd:YVO 4 laser, and Nd:YLF laser are used preferably. For forming a refractive index change region, titanium sapphire laser is used preferably.
[0286] Though pulse laser light is used for processing the object 1 in the first embodiment, continuous wave laser light may also be used as long as it can generate multiphoton absorption. In the present invention, laser light means to include laser beams. The light-converging lens 105 is an embodiment of light-converging means. The Z-axis stage 113 is an embodiment of means for locating the light-converging point within the object to be processed. The light-converging point of laser light can be located within the object to be processed by relatively moving the light-converging lens 105 in the Z-axis direction.
[0287] The laser processing apparatus 100 further comprises an observation light source 117 for generating a visible light beam for irradiating the object to be processed 1 mounted on the mounting table 107 ; and a visible light beam splitter 119 disposed on the same optical axis as that of the dichroic mirror 103 and light-converging lens 105 . The dichroic mirror 103 is disposed between the beam splitter 119 and light-converging lens 105 . The beam splitter 119 has a function of reflecting about a half of a visual light beam and transmitting the remaining half therethrough, and is arranged so as to change the orientation of the optical axis of the visual light beam by 90°. A half of the visible light beam generated by the observation light source 117 is reflected by the beam splitter 119 , and thus reflected visible light beam is transmitted through the dichroic mirror 103 and light-converging lens 105 , so as to illuminate the surface 3 of the object 1 including the line 5 along which the object is intended to be cut and the like.
[0288] The laser processing apparatus 100 further comprises an image pickup device 121 and an imaging lens 123 disposed on the same optical axis as that of the beam splitter 119 , dichroic mirror 103 , and light-converging lens 105 . An embodiment of the image pickup device 121 is a CCD (charge-coupled device) camera. The reflected light of the visual light beam having illuminated the surface 3 including the line 5 along which the object is intended to be cut and the like is transmitted through the light-converging lens 105 , dichroic mirror 103 , and beam splitter 119 and forms an image by way of the imaging lens 123 , whereas thus formed image is captured by the imaging device 121 , so as to yield imaging data.
[0289] The laser processing apparatus 100 further comprises an imaging data processor 125 for inputting the imaging data outputted from the imaging device 121 , an overall controller 127 for controlling the laser processing apparatus 100 as a whole, and a monitor 129 . According to the imaging data, the imaging data processor 125 calculates foal point data for locating the focal point of the visible light generated in the observation light source 117 onto the surface 3 . According to the focal point data, the stage controller 115 controls the movement of the Z-axis stage 113 , so that the focal point of visible light is located on the surface 3 . Hence, the imaging data processor 125 functions as an auto focus unit. Also, according to the imaging data, the imaging data processor 125 calculates image data such as an enlarged image of the surface 3 . The image data is sent to the overall controller 127 , subjected to various kinds of processing, and then sent to the monitor 129 . As a consequence, an enlarged image or the like is displayed on the monitor 129 .
[0290] Data from the stage controller 115 , image data from the imaging data processor 125 , and the like are fed into the overall controller 127 . According to these data as well, the overall controller 127 regulates the laser light source controller 102 , observation light source 117 , and stage controller 115 , thereby controlling the laser processing apparatus 100 as a whole. Thus, the overall controller 127 functions as a computer unit.
[0291] With reference to FIGS. 14 and 15 , the laser processing method in accordance with a first embodiment of the embodiment will now be explained. FIG. 15 is a flowchart for explaining this laser processing method. The object to be processed 1 is a silicon wafer.
[0292] First, a light absorption characteristic of the object 1 is determined by a spectrophotometer or the like which is not depicted. According to the results of measurement, a laser light source 101 generating laser light L having a wavelength to which the object 1 is transparent or exhibits a low absorption is chosen (S 101 ). Next, the thickness of the object 1 is measured. According to the result of measurement of thickness and the refractive index of the object 1 , the amount of movement of the object 1 in the Z-axis direction is determined (S 103 ). This is an amount of movement of the object 1 in the Z-axis direction with reference to the light-converging point of laser light L positioned at the surface 3 of the object 1 in order for the light-converging point P of laser light L to be positioned within the object 1 . This amount of movement is fed into the overall controller 127 .
[0293] The object 1 is mounted on the mounting table 107 of the laser processing apparatus 100 . Then, visible light is generated from the observation light source 117 , so as to illuminate the object 1 (S 105 ). The illuminated surface 3 of the object 1 including the line 5 along which the object is intended to be cut is captured by the image pickup device 121 . Thus obtained imaging data is sent to the imaging data processor 125 . According to the imaging data, the imaging data processor 125 calculates such focal point data that the focal point of visible light from the observation light source 117 is positioned at the surface 3 (S 107 ).
[0294] The focal point data is sent to the stage controller 115 . According to the focal point data, the stage controller 115 moves the Z-axis stage 113 in the Z-axis direction (S 109 ). As a consequence, the focal point of visible light from the observation light source 117 is positioned at the surface 3 . According to the imaging data, the imaging data processor 125 calculates enlarged image data of the surface 3 of the object including the line 5 along which the object is intended to be cut. The enlarged image data is sent to the monitor 129 by way of the overall controller 127 , whereby an enlarged image of the line 5 along which the object is intended to be cut and its vicinity is displayed on the monitor 129 .
[0295] Movement amount data determined at step S 103 has been fed into the overall controller 127 beforehand, and is sent to the stage controller 115 . According to the movement amount data, the stage controller 115 causes the Z-axis stage 113 to move the object 1 in the Z-axis direction at a position where the light-converging point P of laser light L is located within the object 1 (S 111 ).
[0296] Next, laser light L is generated from the laser light source 101 , so as to irradiate the line 5 along which the object is intended to be cut in the surface 3 of the object with the laser light L. Since the light-converging point P of laser light is positioned within the object 1 , a molten processed region is formed only within the object 1 . Subsequently, the X-axis stage 109 and Y-axis stage 111 are moved along the line along which the object is intended to be cut, so as to form a molten processed region along the line 5 along which the object is intended to be cut within the object 1 (S 113 ). Then, the object 1 is bent along the line 5 along which the object is intended to be cut, and thus is cut (S 115 ). This divides the object 1 into silicon chips.
[0297] Effects of the first embodiment will be explained. Here, the line 5 along which the object is intended to be cut is irradiated with the pulse laser light L under a condition causing multiphoton absorption while locating the light-converging point P within the object 1 . Then, the X-axis stage 109 and Y-axis stage 111 are moved, so as to move the light-converging point P along the line 5 along which the object is intended to be cut. As a consequence, a modified region (e.g., crack region, molten processed region, or refractive index change region) is formed within the object 1 along the line 5 along which the object is intended to be cut. When a certain starting point exists at a part to be cut in the object to be processed, the object can be cut by breaking it with a relatively small force. Therefore, breaking the object 1 along the line 5 along which the object is intended to be cut while using a modified region as a starting point can cut the object 1 with a relatively small force. This can cut the object 1 without generating unnecessary fractures deviating from the line 5 along which the object is intended to be cut in the surface 3 of the object 1 .
[0298] Also, in the first embodiment, the object 1 is irradiated with the pulse laser light L at the line 5 along which the object is intended to be cut under a condition generating multiphoton absorption in the object 1 while locating the light-converging point P within the object 1 . Therefore, the pulse laser light L is transmitted through the object 1 without substantially being absorbed at the surface 3 of the object 1 , whereby the surface 3 will not incur damages such as melting due to the forming of a modified region.
[0299] As explained in the foregoing, the first embodiment can cut the object 1 without generating unnecessary fractures deviating from the line 5 along which the object is intended to be cut and melt in the surface 3 of the object. Therefore, when the object is a semiconductor wafer, for embodiment, a semiconductor chip can be cut out from the semiconductor wafer without generating unnecessary fractures deviating from the line along which the object is intended to be cut and melt in the semiconductor chip. The same holds for objects to be processed whose surface is formed with electrode patterns, and those whose surface is formed with electronic devices such as piezoelectric wafers and glass substrates formed with display devices such as liquid crystals. Therefore, the first embodiment can improve the yield of products (e.g., semiconductor chips, piezoelectric device chips, and display devices such as liquid crystal) prepared by cutting the object to be processed.
[0300] Also, since the line 5 along which the object is intended to be cut in the surface 3 of the object 1 does not melt, the first embodiment can decrease the width of the line 5 along which the object is intended to be cut (the width being the interval between regions to become semiconductor chips in the case of a semiconductor wafer, for embodiment). This increases the number of products prepared from a single object to be processed 1 , whereby the productivity of products can be improved.
[0301] Since laser light is used for cutting the object 1 , the first embodiment enables processing more complicated than that obtained by dicing with a diamond cutter. For embodiment, even when the line 5 along which the object is intended to be cut has a complicated form as shown in FIG. 16 , the first embodiment allows cutting. These effects are similarly obtained in embodiments which will be explained later.
[0302] Not only a single laser light source but also a plurality of laser light sources may be provided. For embodiment, FIG. 17 is a schematic view for explaining the laser processing method in the first embodiment of the embodiment in which a plurality of laser light sources are provided. Here, the object 1 is irradiated with three laser beams emitted from respective laser light sources 15 , 17 , 19 from different directions while the light-converging point P is located within the object 1 . The respective laser beams from the laser light sources 15 , 17 are made incident on the object 1 from the surface 3 thereof. The laser beam from the laser light source 19 is made incident on the object 1 from the rear face 21 thereof. Since a plurality of laser light sources are used, this makes it possible for the light-converging point to have an electric field intensity with such a magnitude that multiphoton absorption occurs, even when laser light is continuous wave laser light having a power lower than that of pulse laser light. For the same reason, multiphoton absorption can be generated even without a light-converging lens. Though the light-converging point P is formed by the three laser light sources 15 , 17 , 19 , the present invention is not restricted thereto as long as a plurality of laser light sources exist therein.
[0303] FIG. 18 is a schematic view for explaining another laser processing method in accordance with the first embodiment of the embodiment in which a plurality of laser light sources are provided. This embodiment comprises three array light source sections 25 , 27 , 29 each having a plurality of laser light sources 23 aligning along the line 5 along which the object is intended to be cut. Among the array light source sections 25 , 27 , 29 , laser beams emitted from laser light sources 23 arranged in the same row form a single light-converging point (e.g., light-converging point P 1 )— This embodiment can form a plurality of light-converging points P 1 , P 2 , along the line 5 along which the object is intended to be cut, whereby the processing speed can be improved. Also, in this embodiment, a plurality of rows of modified regions can be formed at the same time upon laser-scanning on the surface 3 in a direction orthogonal to the line 5 along which the object is intended to be cut.
Second Embodiment
[0304] A second embodiment of the present invention will now be explained. This embodiment is directed to a cutting method and cutting apparatus for a light-transmitting material. The light-transmitting material is an embodiment of the objects to be processed. In this embodiment, a piezoelectric device wafer (substrate) having a thickness of about 400 μm made of LiTaO 3 is used as a light-transmitting material.
[0305] The cutting apparatus in accordance with the second embodiment is constituted by the laser processing apparatus 100 shown in FIG. 14 and the apparatus shown in FIGS. 19 and 20 . The apparatus shown in FIGS. 19 and 20 will be explained. The piezoelectric device wafer 31 is held by a wafer sheet (film) 33 acting as holding means. In the wafer sheet 33 , the face on the side holding the piezoelectric device wafer 31 is made of an adhesive resin tape or the like, and has an elasticity. The wafer sheet 33 is set on a mounting table 107 while being held with a sample holder 35 . As shown in FIG. 19 , the piezoelectric device wafer 31 includes a number of piezoelectric device chips 37 which will be cut and separated later. Each piezoelectric device chip 37 has a circuit section 39 . The circuit section 39 is formed on the surface of the piezoelectric device wafer for each piezoelectric device chip 37 , whereas a predetermined gap a (about 80 μm) is formed between adjacent circuit sections 39 . FIG. 20 shows a state where minute crack regions 9 as modified parts are formed within the piezoelectric device wafer 31 .
[0306] Next, with reference to FIG. 21 , the method of cutting a light-transmitting material in accordance with the second embodiment will be explained. First, a light absorption characteristic of the light-transmitting material (piezoelectric device wafer 31 made of LiTaO 3 in the second embodiment) to become a material to be cut is determined (S 201 ). The light absorption characteristic can be measured by using a spectrophotometer or the like. Once the light absorption characteristic is determined, a laser light source 101 generating laser light L having a wavelength to which the material to be cut is transparent or exhibits a low absorption is chosen according to the result of determination (S 203 ). In the second embodiment, a YAG laser of pulse wave (PW) type having a fundamental wave wavelength of 1064 nm is chosen. This YAG laser has a pulse repetition frequency of 20 Hz, a pulse width of 6 ns, and a pulse energy of 300 μJ. The spot diameter of laser light L emitted from the YAG laser is about 20 μm.
[0307] Next, the thickness of the material to be cut is measured (S 205 ). Once the thickness of the material to be cut is measured, the amount of displacement (amount of movement) of the light-converging point of laser light L from the surface (entrance face for laser light L) of the material to be cut in the optical axis direction of laser light L is determined so as to position the light-converging point of laser light L within the material to be cut according to the result of measurement (S 207 ). For embodiment, in conformity to the thickness and refractive index of the material to be cut, the amount of displacement (amount of movement) of the light-converging point of laser light L is set to ½ of the thickness of the material to be cut.
[0308] As shown in FIG. 22 , due to the difference between the refractive index in the atmosphere (e.g., air) surrounding the material to be cut and the refractive index of the material to be cut, the actual position of the light-converging point P of laser light is located deeper than the position of the light-converging point Q of laser light L converged by the light-converging lens 105 from the surface of the material to be cut (piezoelectric device wafer 31 ). Namely, the relationship of “amount of movement of Z-axis stage 113 in the optical axis direction of laser light L×refractive index of the material to be cut=actual amount of movement of light-converging point of laser light L” holds in the air. The amount of displacement (amount of movement) of the light-converging point of laser light L is set in view of the above-mentioned relationship (between the thickness and refractive index of the material to be cut). Thereafter, the material to be cut held by the wafer sheet 33 is mounted on the mounting table 107 placed on the X-Y-Z-axis stage (constituted by the X-axis stage 109 , Y-axis stage 111 , and Z-axis stage 113 in this embodiment) (S 209 ). After the mounting of the material to be cut is completed, light is emitted from the observation light source 117 , so as to irradiate the material to be cut with thus emitted light. Then, according to the result of imaging at the image pickup device 121 , focus adjustment is carried out by moving the Z-axis stage 113 so as to position the light-converging point of laser light L onto the surface of the material to be cut (S 211 ). Here, the surface observation image of piezoelectric device wafer 31 obtained by the observation light source 117 is captured by the image pickup device 121 , whereas the imaging data processor 125 determines the moving position of the Z-axis stage 113 according to the result of imaging such that the light emitted from the observation light source 117 forms a focal point on the surface of the material to be cut, and outputs thus determined position to the stage controller 115 . According to an output signal from the imaging data processor 125 , the stage controller 115 controls the Z-axis stage 113 such that the moving position of the Z-axis stage 113 is located at a position for making the light emitted from the observation light source 117 form a focal point on the material to be cut, i.e., for positioning the focal point of laser light L onto the surface of the material to be cut.
[0309] After the focus adjustment of light emitted from the observation light source 117 is completed, the light-converging point of laser light L is moved to a light-converging point corresponding to the thickness and refractive index of the material to be cut (S 213 ). Here, the overall controller 127 sends an output signal to the stage controller 115 so as to move the Z-axis stage 113 in the optical axis direction of laser light L by the amount of displacement of the light-converging point of laser light determined in conformity to the thickness and refractive index of the material to be cut, whereby the stage controller 115 having received the output signal regulates the moving position of the Z-axis stage 113 . As mentioned above, the placement of the light-converging point of laser light L within the material to be cut is completed by moving the Z-axis stage 113 in the optical axis direction of laser light L by the amount of displacement of the light-converging point of laser light L determined in conformity to the thickness and refractive index of the material to be cut (S 215 ).
[0310] After the placement of the light-converging point of laser light L within the material to be cut is completed, the material to be cut is irradiated with laser light L, and the X-axis stage 109 and the Y-axis stage 111 are moved in conformity to a desirable cutting pattern (S 217 ). As shown in FIG. 22 , the laser light L emitted from the laser light source 101 is converged by the light-converging lens 105 such that the light-converging point P is positioned within the piezoelectric device wafer 31 facing a predetermined gap (80 μm as mentioned above) formed between adjacent circuit sections 39 . The above-mentioned desirable cutting pattern is set such that the gap formed between the adjacent circuit sections 39 in order to separate a plurality of piezoelectric device chips 37 from the piezoelectric device wafer 31 is irradiated with the laser light L, whereas the laser light L is irradiated while the state of irradiation of laser light L is seen through the monitor 129 .
[0311] Here, as shown in FIG. 22 , the laser light L irradiating the material to be cut is converged by the light-converging lens 105 by an angle at which the circuit sections 39 formed on the surface of the piezoelectric device wafer 31 (the surface on which the laser light L is incident) are not irradiated with the laser light L. Converging the laser light L by an angle at which the circuit sections 39 are not irradiated with the laser light L can prevent the laser light L from entering the circuit sections 39 and protect the circuit sections 39 against the laser light L.
[0312] When the laser light L emitted from the laser light source 101 is converged such that the light-converging point P is positioned within the piezoelectric device wafer 31 while the energy density of laser light L at the light-converging point P exceeds a threshold of optical damage or optical dielectric breakdown, minute crack regions 9 are formed only at the light-converging point P within the piezoelectric device wafer 31 acting as a material to be cut and its vicinity. Here, the surface and rear face of the material to be cut (piezoelectric device wafer 31 ) will not be damaged.
[0313] Now, with reference to FIGS. 23 to 27 , the forming of cracks by moving the light-converging point of laser light L will be explained. The material to be cut 32 (light-transmitting material) having a substantially rectangular parallelepiped form shown in FIG. 23 is irradiated with laser light L such that the light-converging point of laser light L is positioned within the material to be cut 32 , whereby minute crack regions 9 are formed only at the light-converging point within the material to be cut 32 and its vicinity as shown in FIGS. 24 and 25 . The scanning of laser light L or movement of the material to be cut 32 is regulated so as to move the light-converging point of laser light L in the longitudinal direction D of material to be cut 32 intersecting the optical axis of laser light L.
[0314] Since the laser light L is emitted from the laser light source 101 in a pulsating manner, a plurality of crack regions 9 are formed with a gap therebetween corresponding to the scanning speed of laser light L or the moving speed of the material to be cut 32 along the longitudinal direction D of the material to be cut 32 when the laser light L is scanned or the material to be cut 32 is moved. The scanning speed of laser light L or the moving speed of material to be cut 32 may be slowed down, so as to shorten the gap between the crack regions 9 , thereby increasing the number of thus formed crack regions 9 as shown in FIG. 26 . The scanning speed of laser light L or the moving speed of material to be cut may further be slowed down, so that the crack region 9 is continuously formed in the scanning direction of laser light L or the moving direction of material to be cut 32 , i.e., the moving direction of the light-converging point of laser light L as shown in FIG. 27 . Adjustment of the gap between the crack regions 9 (number of crack regions 9 to be formed) can also be realized by changing the relationship between the repetition frequency of laser light L and the moving speed of the material to be cut 32 (X-axis stage or Y-axis stage). Also, throughput can be improved when the repetition frequency of laser light L and the moving speed of material to be cut 32 are increased.
[0315] Once the crack regions 9 are formed along the above-mentioned desirable cutting pattern (S 219 ), a stress is generated due to physical external force application, environmental changes, and the like within the material to be cut, the part formed with the crack regions 9 in particular, so as to grow the crack regions 9 formed only within the material to be cut (the light-converging point and its vicinity), thereby cutting the material to be cut at a position formed with the crack regions 9 (S 221 ).
[0316] With reference to FIGS. 28 to 32 , the cutting of the material to be cut upon physical external force application will be explained. First, the material to be cut (piezoelectric device wafer 31 ) formed with the crack regions 9 along the desirable cutting pattern is placed in a cutting apparatus while in a state held by a wafer sheet 33 grasped by the sample holder 35 . The cutting apparatus has a suction chuck 34 , which will be explained later, a suction pump (not depicted) connected to the suction chuck 34 , a pressure needle 36 (pressing member), pressure needle driving means (not depicted) for moving the pressure needle 36 , and the like. Usable as the pressure needle driving means is an actuator of electric, hydraulic, or other types. FIGS. 28 to 32 do not depict the circuit sections 39 .
[0317] Once the piezoelectric device wafer 31 is placed in the cutting apparatus, the suction chuck 34 approaches the position corresponding to the piezoelectric device chip 37 to be isolated as shown in FIG. 28 . A suction pump apparatus is actuated while in a state where the suction chuck 34 is located closer to or abuts against the piezoelectric device chip 37 to be isolated, whereby the suction chuck 34 attracts the piezoelectric device chip 37 (piezoelectric device wafer 31 ) to be isolated as shown in FIG. 29 . Once the suction chuck 34 attracts the piezoelectric device chip 37 (piezoelectric device wafer 31 ) to be isolated, the pressure needle 36 is moved to the position corresponding to the piezoelectric device chip 37 to be isolated from the rear face of wafer sheet 33 (rear face of the surface held with the piezoelectric device wafer 31 ) as shown in FIG. 30 .
[0318] When the pressure needle 36 is further moved after abutting against the rear face of the wafer sheet 33 , the wafer sheet 33 deforms, while the pressure needle 36 applies a stress to the piezoelectric device wafer 31 from the outside, whereby a stress is generated in the wafer part formed with the crack regions 9 , which grows the crack regions 9 . When the crack regions 9 grow to the surface and rear face of the piezoelectric device wafer 31 , the piezoelectric device wafer 31 is cut at an end part of the piezoelectric device chip 37 to be isolated as shown in FIG. 31 , whereby the piezoelectric device chip 37 is isolated from the piezoelectric device wafer 31 . The wafer sheet 33 has an adhesiveness as mentioned above, thereby being able to prevent cut and separated piezoelectric device chips 37 from flying away.
[0319] Once the piezoelectric device chip 37 is separated from the piezoelectric device wafer 31 , the suction chuck 34 and pressure needle 36 are moved away from the wafer sheet 33 . When the suction chuck 34 and pressure needle 36 are moved, the isolated piezoelectric device chip 37 is released from the wafer sheet 33 as shown in FIG. 32 , since the former is attracted to the suction chuck 34 . Here, an ion air blow apparatus, which is not depicted, is used for sending an ion air in the direction of arrows B in FIG. 32 , whereby the piezoelectric device chip 37 isolated and attracted to the suction chuck 34 , and the piezoelectric device wafer 31 (surface) held by the wafer sheet 32 are cleaned with the ion air. Here, a suction apparatus may be provided in place of the ion air cleaning, such that the cut and separated piezoelectric device chips 37 and piezoelectric device wafer 31 are cleaned as dust and the like are aspirated. Known as a method of cutting the material to be cut due to environmental changes is one imparting a temperature change to the material to be cut having the crack regions 9 only therewithin. When a temperature change is imparted to the material to be cut as such, a thermal distortion can occur in the material part formed with the crack regions 9 , so that the crack regions grow, whereby the material to be cut can be cut.
[0320] Thus, in the second embodiment, the light-converging lens 105 converges the laser light L emitted from the laser light source 101 such that its light-converging point is positioned within the light-transmitting material (piezoelectric device wafer 31 ), whereby the energy density of laser light at the light-converging point exceeds the threshold of optical damage or optical dielectric breakdown, which forms the minute cracks 9 only at the light-converging point within the light-transmitting material and its vicinity. Since the light-transmitting material is cut at the positions of thus formed crack regions 9 , the amount of dust emission is very small, whereby the possibility of dicing damages, chipping, cracks on the material surface, and the like occurring also becomes very low. Since the light-transmitting material is cut along the crack regions 9 formed by the optical damages or optical dielectric breakdown of the light-transmitting material, the directional stability of cutting improves, so that cutting direction can be controlled easily. Also, the dicing width can be made smaller than that attained in the dicing with a diamond cutter, whereby the number of light-transmitting materials cut out from one light-transmitting material can be increased. As a result of these, the second embodiment can cut the light-transmitting material quite easily and appropriately.
[0321] Also, a stress is generated within the material to be cut due to physical external force application, environmental changes, and the like, so as to grow the formed crack regions 9 to cut the light-transmitting material (piezoelectric device wafer 31 ), whereby the light-transmitting material can reliably be cut at the positions of formed crack regions 9 .
[0322] Also, the pressure needle 36 is used for applying a stress to the light-transmitting material (piezoelectric device wafer 31 ), so as to grow the formed crack regions 9 to cut the light-transmitting material (piezoelectric device wafer 31 ), whereby the light-transmitting material can further reliably be cut at the positions of formed crack regions 9 .
[0323] When the piezoelectric device wafer 31 (light-transmitting material) formed with a plurality of circuit sections 39 is cut and separated into individual piezoelectric device chips 37 , the light-converging lens 105 converges the laser light L such that the light-converging point is positioned within the wafer part facing the gap formed between adjacent circuit sections 39 , and forms the crack regions 9 , whereby the piezoelectric device wafer 31 can reliably be cut at the position of the gap formed between adjacent circuit sections 39 .
[0324] When the light-transmitting material (piezoelectric device wafer 31 ) is moved or laser light L is scanned so as to move the light-converging point in a direction intersecting the optical axis of laser light L, e.g., a direction orthogonal thereto, the crack region 9 is continuously formed along the moving direction of the light-converging point, so that the directional stability of cutting further improves, which makes it possible to control the cutting direction more easily.
[0325] Also, in the second embodiment, dust-emitting powders hardly exist, so that no lubricating/cleaning water for preventing the dust-emitting powders from flying away is necessary, whereby dry processing can be realized in the cutting step.
[0326] In the second embodiment, since the forming of a modified part (crack region 9 ) is realized by non-contact processing with the laser light L, problems of durability of blades, their replacement frequency, and the like in the dicing caused by diamond cutters will not occur. Also, since the forming of a modified part (crack region 9 ) is realized by non-contact processing with the laser light L, the second embodiment can cut the light-transmitting material along a cutting pattern which cuts out the light-transmitting material without completely cutting the same. The present invention is not limited to the above-mentioned second embodiment. For embodiment, the light-transmitting material may be a semiconductor wafer, a glass substrate, or the like without being restricted to the piezoelectric device wafer 31 . Also, the laser light source 101 can appropriately be selected in conformity to an optical absorption characteristic of the light-transmitting material to be cut. Though the minute regions 9 are formed as a modified part upon irradiation with the laser light L in the second embodiment, it is not restrictive. For embodiment, using an ultra short pulse laser light source (e.g., femto second (fs) laser) can form a modified part caused by a refractive index change (higher refractive index), thus being able to cut the light-transmitting material without generating the crack regions 9 by utilizing such a mechanical characteristic change.
[0327] Though the focus adjustment of laser light L is carried out by moving the Z-axis stage 113 in the laser processing apparatus 100 , it may be effected by moving the light-converging lens 105 in the optical axis direction of laser light L without being restricted thereto.
[0328] Though the X-axis stage 109 and Y-axis stage 111 are moved in conformity to a desirable cutting pattern in the laser processing apparatus 100 , it is not restrictive, whereby the laser light L may be scanned in conformity to a desirable cutting pattern.
[0329] Though the piezoelectric device wafer 31 is cut by the pressure needle 36 after being attracted to the suction chuck 34 , it is not restrictive, whereby the piezoelectric device wafer 31 may be cut by the pressure needle 36 , and then the cut and isolated piezoelectric device chip 37 may be attracted to the suction chuck 34 . Here, when the piezoelectric device wafer 31 is cut by the pressure needle 36 after the piezoelectric device wafer 31 is attracted to the suction chuck 34 , the surface of the cut and isolated piezoelectric device chip 37 is covered with the suction chuck 34 , which can prevent dust and the like from adhering to the surface of the piezoelectric device chip 37 .
[0330] Also, when an image pickup device 121 for infrared rays is used, focus adjustment can be carried out by utilizing reflected light of laser light L. In this case, it is necessary that a half mirror be used instead of the dichroic mirror 103 , while disposing an optical device between the half mirror and the laser light source 101 , which suppresses the return light to the laser light source 101 . Here, it is preferred that the output of laser light L emitted from the laser light source 101 at the time of focus adjustment be set to an energy level lower than that of the output for forming cracks, such that the laser light L for carrying out focus adjustment does not damage the material to be cut.
[0331] Characteristic features of the present invention will now be explained from the viewpoints of the second embodiment.
[0332] The method of cutting a light-transmitting material in accordance with an aspect of the present invention comprises a modified part forming step of converging laser light emitted from a laser light source such that its light-converging point is positioned within the light-transmitting material, so as to form a modified part only at the light-converging point within the light-transmitting material and its vicinity; and a cutting step of cutting the light-transmitting material at the position of thus formed modified part.
[0333] In the method of cutting a light-transmitting material in accordance with this aspect of the present invention, the laser light is converged such that the light-converging point of laser light is positioned within the light-transmitting material in the modified part forming step, whereby the modified part is formed only at the light-converging point within the light-transmitting material and its vicinity. In the cutting step, the light-transmitting material is cut at the position of thus formed modified part, so that the amount of dust emission is very small, whereby the possibility of dicing damages, chipping, cracks on the material surface, and the like occurring also becomes very low. Since the light-transmitting material is cut at the position of thus formed modified part, the directional stability of cutting improves, so that cutting direction can be controlled easily. Also, the dicing width can be made smaller than that attained in the dicing with a diamond cutter, whereby the number of light-transmitting materials cut out from one light-transmitting material can be increased. As a result of these, the present invention can cut the light-transmitting material quite easily and appropriately.
[0334] Also, in the method of cutting a light-transmitting material in accordance with this aspect of the present invention, dust-emitting powders hardly exist, so that no lubricating/cleaning water for preventing the dust-emitting powders from flying away is necessary, whereby dry processing can be realized in the cutting step.
[0335] In the method of cutting a light-transmitting material in accordance with this aspect of the present invention, since the forming of a modified part is realized by non-contact processing with laser light, problems of durability of blades, their replacement frequency, and the like in the dicing caused by diamond cutters will not occur. Also, since the forming of a modified part is realized by non-contact processing with the laser light, the method of cutting a light-transmitting material in accordance with this aspect of the present invention can cut the light-transmitting material along a cutting pattern which cuts out the light-transmitting material without completely cutting the same.
[0336] Preferably, the light-transmitting material is formed with a plurality of circuit sections, whereas laser light is converged such that the light-converging point is positioned within the light-transmitting material part facing the gap formed between adjacent circuit sections in the modified part forming step, so as to form the modified part. With such a configuration, the light-transmitting material can reliably be cut at the position of the gap formed between adjacent circuit sections.
[0337] When irradiating the light-transmitting material with laser light in the modified part forming step, it is preferred that the laser light be converged by an angle at which the circuit sections are not irradiated with the laser light. Converging the laser light by an angle at which the circuit sections are not irradiated with the laser light when irradiating the light-transmitting material with the laser light in the modified part forming step as such can prevent the laser light from entering the circuit sections and protect the circuit sections against the laser light.
[0338] Preferably, in the modified part forming step, the light-converging point is moved in a direction intersecting the optical axis of laser light, so as to form a modified part continuously along the moving direction of the light-converging point. When the light-converging point is moved in a direction intersecting the optical axis of laser light in the modified part forming step as such, so as to form the modified part continuously along the moving direction of the light-converging point, the directional stability of cutting further improves, which makes it further easier to control the cutting direction.
[0339] The method of cutting a light-transmitting material in accordance with an aspect of the present invention comprises a crack forming step of converging laser light emitted from a laser light source such that its light-converging point is positioned within the light-transmitting material, so as to form a crack only at the light-converging point within the light-transmitting material and its vicinity; and a cutting step of cutting the light-transmitting material at the position of thus formed crack.
[0340] In the method of cutting a light-transmitting material in accordance with this aspect of the present invention, laser light is converged such that the light-converging point of laser light is positioned within the light-transmitting material, so that the energy density of laser light at the light-converging point exceeds a threshold of optical damage or optical dielectric breakdown of the light-transmitting material, whereby a crack is formed only at the light-converging point within the light-transmitting material and its vicinity. In the cutting step, the light-transmitting material is cut at the position of thus formed crack, so that the amount of dust emission is very small, whereby the possibility of dicing damages, chipping, cracks on the material surface, and the like occurring also becomes very low. Since the light-transmitting material is cut at the position of the crack formed by an optical damage or optical dielectric breakdown, the directional stability of cutting improves, so that cutting direction can be controlled easily. Also, the dicing width can be made smaller than that attained in the dicing with a diamond cutter, whereby the number of light-transmitting materials cutout from one light-transmitting material can be increased. As a result of these, the present invention can cut the light-transmitting material quite easily and appropriately.
[0341] Also, in the method of cutting a light-transmitting material in accordance with this aspect of the present invention, dust-emitting powders hardly exist, so that no lubricating/cleaning water for preventing the dust-emitting powders from flying away is necessary, whereby dry processing can be realized in the cutting step.
[0342] In the method of cutting a light-transmitting material in accordance with this aspect of the present invention, since the forming of a crack is realized by non-contact processing with laser light, problems of durability of blades, their replacement frequency, and the like in the dicing caused by diamond cutters will not occur. Also, since the forming of a crack is realized by non-contact processing with the laser light, the method of cutting a light-transmitting material in accordance with this aspect of the present invention can cut the light-transmitting material along a cutting pattern which cuts out the light-transmitting material without completely cutting the same.
[0343] Preferably, in the cutting step, the light-transmitting material is cut by growing the formed crack. Cutting the light-transmitting material by growing the formed crack in the cutting step as such can reliably cut the light-transmitting material at the position of the formed crack.
[0344] Preferably, in the cutting step, a stress is applied to the light-transmitting material by using a pressing member, so as to grow a crack, thereby cutting the light-transmitting material. When a stress is applied to the light-transmitting material in the cutting step by using a pressing member as such, so as to grow a crack, thereby cutting the light-transmitting material, the light-transmitting material can further reliably be cut at the position of the crack.
[0345] The apparatus for cutting a light-transmitting material in accordance with an aspect of the present invention comprises a laser light source; holding means for holding the light-transmitting material; an optical device for converging the laser light emitted from the laser light source such that a light-converging point thereof is positioned within the light-transmitting material; and cutting means for cutting the light-transmitting material at the position of a modified part formed only at the light-converging point of laser light within the light-transmitting material and its vicinity.
[0346] In the apparatus for cutting a light-transmitting material in accordance with this aspect of the present invention, the optical device converges laser light such that the light-converging point of laser light is positioned within the light-transmitting material, whereby a modified part is formed only at the light-converging point within the light-transmitting material and its vicinity. Then, the cutting means cuts the light-transmitting material at the position of the modified part formed only at the light-converging point within the light-transmitting material and its vicinity, whereby the light-transmitting material is reliably cut along thus formed modified part. As a consequence, the amount of dust emission is very small, whereas the possibility of dicing damages, chipping, cracks on the material surface, and the like occurring also becomes very low. Also, since the light-transmitting material is cut along the modified part, the directional stability of cutting improves, whereby the cutting direction can be controlled easily. Also, the dicing width can be made smaller than that attained in the dicing with a diamond cutter, whereby the number of light-transmitting materials cut out from one light-transmitting material can be increased. As a result of these, the present invention can cut the light-transmitting material quite easily and appropriately.
[0347] Also, in the apparatus for cutting a light-transmitting material in accordance with this aspect of the present invention, dust-emitting powders hardly exist, so that no lubricating/cleaning water for preventing the dust-emitting powders from flying away is necessary, whereby dry processing can be realized in the cutting step.
[0348] In the apparatus for cutting a light-transmitting material in accordance with this aspect of the present invention, since the modified part is formed by non-contact processing with laser light, problems of durability of blades, their replacement frequency, and the like in the dicing caused by diamond cutters will not occur as in the conventional techniques. Also, since the modified part is formed by non-contact processing with the laser light as mentioned above, the apparatus for cutting a light-transmitting material in accordance with this aspect of the present invention can cut the light-transmitting material along a cutting pattern which cuts out the light-transmitting material without completely cutting the same.
[0349] The apparatus for cutting a light-transmitting material in accordance with an aspect of the present invention comprises a laser light source; holding means for holding the light-transmitting material; an optical device for converging laser light emitted from the laser light source such that a light-converging point thereof is positioned within the light-transmitting material; and cutting means for cutting the light-transmitting material by growing a crack formed only at the light-converging point of laser light within the light-transmitting material and its vicinity.
[0350] In the apparatus for cutting a light-transmitting material in accordance with this aspect of the present invention, the optical device converges laser light such that the light-converging point of laser light is positioned within the light-transmitting material, so that the energy density of laser light at the light-converging point exceeds a threshold of optical damage or optical dielectric breakdown of the light-transmitting material, whereby a crack is formed only at the light-converging point within the light-transmitting material and its vicinity. Then, the cutting means cuts the light-transmitting material by growing the crack formed only at the light-converging point within the light-transmitting material and its vicinity, whereby the light-transmitting material is reliably cut along the crack formed by an optical damage or optical dielectric breakdown of the light-transmitting material. As a consequence, the amount of dust emission is very small, whereas the possibility of dicing damages, chipping, cracks on the material surface, and the like occurring also becomes very low. Since the light-transmitting material is cut along the crack, the directional stability of cutting improves, so that cutting direction can be controlled easily. Also, the dicing width can be made smaller than that attained in the dicing with a diamond cutter, whereby the number of light-transmitting materials cut out from one light-transmitting material can be increased. As a result of these, the present invention can cut the light-transmitting material quite easily and appropriately.
[0351] Also, in the apparatus for cutting a light-transmitting material in accordance with this aspect of the present invention, dust-emitting powders hardly exist, so that no lubricating/cleaning water for preventing the dust-emitting powders from flying away is necessary, whereby dry processing can be realized in the cutting step.
[0352] In the apparatus for cutting a light-transmitting material in accordance with this aspect of the present invention, since the crack is formed by non-contact processing with laser light, problems of durability of blades, their replacement frequency, and the like in the dicing caused by diamond cutters will not occur as in the conventional techniques. Also, since the crack is formed by non-contact processing with the laser light as mentioned above, the method of cutting a light-transmitting material in accordance with this aspect of the present invention can cut the light-transmitting material along a cutting pattern which cuts out the light-transmitting material without completely cutting the same.
[0353] Preferably, the cutting means has a pressing member for applying a stress to the light-transmitting material. When the cutting means has a pressing member for applying a stress to the light-transmitting material as such, a stress can be applied to the light-transmitting material by using the pressing member, so as to grow a crack, whereby the light-transmitting material can further reliably be cut at the position of the crack formed.
[0354] Preferably, the light-transmitting material is one whose surface is formed with a plurality of circuit sections, whereas the optical device converges the laser light such that the light-converging point is positioned within the light-transmitting material part facing the gap formed between adjacent circuit sections. With such a configuration, the light-transmitting material can reliably be cut at the position of the gap formed between adjacent circuit sections.
[0355] Preferably, the optical device converges laser light by an angle at which the circuit sections are not irradiated with the laser light. When the optical device converges the laser light by an angle at which the circuit sections are not irradiated with the laser light as such, it can prevent the laser light from entering the circuit sections and protect the circuit sections against the laser light.
[0356] Preferably, the apparatus further comprises light-converging point moving means for moving the light-converging point in a direction intersecting the optical axis of laser light. When the apparatus further comprises light-converging point moving means for moving the light-converging point in a direction intersecting the optical axis of laser light as such, a crack can continuously be formed along the moving direction of the light-converging point, so that the directional stability of cutting further improves, whereby the direction of cutting can be controlled further easily.
Third Embodiment
[0357] A third embodiment of the present invention will be explained. In the third embodiment and a fourth embodiment which will be explained later, an object to be processed is irradiated with laser light such that the direction of linear polarization of linearly polarized laser light extends along a line along which the object is intended to be cut in the object to be processed, whereby a modified region is formed in the object to be processed. As a consequence, in the modified spot formed with a single pulse of shot (i.e., a single pulse of laser irradiation), the size in the direction extending along the line along which the object is intended to be cut can be made relatively large when the laser light is pulse laser light. The inventor has confirmed it by an experiment. Conditions for the experiment are as follows:
[0358] (A) Object to be processed: Pyrex glass wafer (having a thickness of 700 μm and an outer diameter of 4 inches)
[0359] (B) Laser
Light source: semiconductor laser pumping Nd:YAG laser Wavelength: 1064 nm Laser light spot cross-sectional area: 3.14×10 −8 cm 2 Oscillation mode: Q-switch pulse Repetition frequency: 100 kHz Pulse width: 30 ns Output: output <1 mJ/pulse Laser light quality: TEM 00 Polarization characteristic: linear polarization
[0369] (C) Light-converging lens
Magnification: × 50 NA: 0.55 Transmittance with respect to laser light wavelength: 60%
[0373] (D) Moving speed of a mounting table mounting the object to be processed: 100 mm/sec
[0374] Each of Samples 1 , 2 , which was an object to be processed, was exposed to a single pulse shot of pulse laser light while the light-converging point is located within the object to be processed, whereby a crack region caused by multiphoton absorption is formed within the object to be processed. Sample 1 was irradiated with linearly polarized pulse laser light, whereas Sample 2 was irradiated with circularly polarized pulse laser light.
[0375] FIG. 33 is a view showing a photograph of Sample 1 in plan, whereas FIG. 34 is a view showing a photograph of Sample 2 in plan. These planes are an entrance face 209 of pulse laser light. Letters LP and CP schematically indicate linear polarization and circular polarization, respectively. FIG. 35 is a view schematically showing a cross section of Sample 1 shown in FIG. 33 taken along the line XXXV-XXXV. FIG. 36 is a view schematically showing a cross section of Sample 1 shown in FIG. 34 taken along the line XXXVI-XXXVI. A crack spot 90 is formed within a glass wafer 211 which is the object to be processed.
[0376] In the case where pulse laser light is linearly polarized light, as shown in FIG. 35 , the size of crack spot 90 formed by a single pulse shot is relatively large in the direction aligning with the direction of linear polarization. This indicates that the forming of the crack spot 90 is accelerated in this direction. When the pulse laser light is circularly polarized light, by contrast, the size of the crack spot 90 formed by a single pulse shot will not become greater in any specific direction as shown in FIG. 36 . The size of the crack spot 90 in the direction yielding the maximum length is greater in Sample 1 than in Sample 2 .
[0377] The fact that a crack region extending along a line along which the object is intended to be cut can be formed efficiently will be explained from these results of experiment. FIGS. 37 and 38 are plan views of crack regions each formed along a line along which the object is intended to be cut in an object to be processed. A number of crack spots 90 , each formed by a single pulse shot, are formed along a line 5 along which the object is intended to be cut, whereby a crack region 9 extending along the line 5 along which the object is intended to be cut is formed. FIG. 37 shows the crack region 9 formed upon irradiation with pulse laser light such that the direction of linear polarization of pulse laser light aligns with the line 5 along which the object is intended to be cut. The forming of crack spots 9 is accelerated along the direction of the line 5 along which the object is intended to be cut, whereby their size is relatively large in this direction. Therefore, the crack region 9 extending along the line 5 along which the object is intended to be cut can be formed by a smaller number of shots. On the other hand, FIG. 38 shows the crack region 9 formed upon irradiation with pulse laser light such that the direction of linear polarization of pulse laser light is orthogonal to the line 5 along which the object is intended to be cut. Since the size of crack spot 90 in the direction of the line 5 along which the object is intended to be cut is relatively small, the number of shots required for forming the crack region 9 becomes greater than that in the case of FIG. 37 . Therefore, the method of forming a crack region in accordance with this embodiment shown in FIG. 37 can form the crack region more efficiently than the method shown in FIG. 38 does.
[0378] Also, since pulse laser light is irradiated while the direction of linear polarization of pulse laser light is orthogonal to the line 5 along which the object is intended to be cut, the forming of the crack spot 90 formed at the shot is accelerated in the width direction of the line 5 along which the object is intended to be cut. Therefore, when the crack spot 90 extends in the width direction of the line 5 along which the object is intended to be cut too much, the object to be processed cannot precisely be cut along the line 5 along which the object is intended to be cut. By contrast, the crack spot 90 formed at the shot does not extend much in directions other than the direction aligning with the line 5 along which the object is intended to be cut in the method in accordance with this embodiment shown in FIG. 37 , whereby the object to be processed can be cut precisely.
[0379] Though making the size in a predetermined direction relatively large among the sizes of a modified region has been explained in the case of linear polarization, the same holds in elliptical polarization as well. Namely, as shown in FIG. 39 , the forming of the crack spot 90 is accelerated in the direction of major axis b of an ellipse representing elliptical polarization EP of laser light, whereby the crack spot 90 having a relatively large size along this direction can be formed. Hence, when a crack region is formed such that the major axis of an ellipse indicative of the elliptical polarization of laser elliptically polarized with an ellipticity of other than 1 aligns with a line along which the object is intended to be cut in the object to be processed, effects similar to those in the case of linear polarization occur. Here, the ellipticity is half the length of minor axis a/half the length of major axis b. As the ellipticity is smaller, the size of the crack spot 90 along the direction of major axis b becomes greater. Linearly polarized light is elliptically polarized light with an ellipticity of zero. Circularly polarized light is obtained when the ellipticity is 1, which cannot make the size of the crack region relatively large in a predetermined direction. Therefore, this embodiment does not encompass the case where the ellipticity is 1.
[0380] Though making the size in a predetermined direction relatively large among the sizes of a modified region has been explained in the case of a crack region, the same holds in molten processed regions and refractive index change regions as well. Also, though pulse laser light is explained, the same holds in continuous wave laser light as well. The foregoing also hold in a fourth embodiment which will be explained later.
[0381] The laser processing apparatus in accordance with the third embodiment of the present invention will now be explained. FIG. 40 is a schematic diagram of this laser processing apparatus. The laser processing apparatus 200 will be explained mainly in terms of its differences from the laser processing apparatus 100 in accordance with the first embodiment shown in FIG. 14 . The laser processing apparatus 200 comprises an ellipticity regulator 201 for adjusting the ellipticity of polarization of laser light L emitted from a laser light source 101 , and a 90° rotation regulator 203 for adjusting the rotation of polarization of the laser light L emitted from the ellipticity regulator 201 by about 90°.
[0382] The ellipticity regulator 201 includes a quarter wave plate 207 shown in FIG. 41 . The quarter wave plate 207 can adjust the ellipticity of elliptically polarized light by changing the angle of direction θ. Namely, when light with linear polarization LP is made incident on the quarter wave plate 207 , the transmitted light attains elliptical polarization EP with a predetermined ellipticity. The angle of direction is an angle formed between the major axis of the ellipse and the X axis. As mentioned above, a number other than 1 is employed as the ellipticity in this embodiment. The ellipticity regulator 201 can make the polarization of laser light L become elliptically polarized light EP having a desirable ellipticity. The ellipticity is adjusted in view of the thickness and material of the object to be processed 1 , and the like.
[0383] When irradiating the object to be processed 1 with laser light L having linear polarization LP, the laser light L emitted from the laser light source 101 is linearly polarized light LP, whereby the ellipticity regulator 201 adjusts the angle of direction θ of the quarter wave plate 207 such that the laser light L passes through the quarter wave plate while being the linearly polarized light LP. Also, the laser light source 101 emits linearly polarized laser light L, whereby the ellipticity regulator 201 is unnecessary when only laser light of linear polarization LP is utilized for irradiating the object to be processed with laser.
[0384] The 90° rotation regulator 203 includes a half wave plate 205 as shown in FIG. 42 . The half wave plate 205 is a wavelength plate for making polarization orthogonal to linearly polarized incident light. Namely, when linearly polarized light LP 1 with an angle of direction of 45° is incident on the half wave plate 205 , for embodiment, transmitted light becomes linearly polarized light LP 2 rotated by 90° with respect to the incident light LP 1 . When rotating the polarization of laser light L emitted from the ellipticity regulator 201 by 90°, the 90° rotation regulator 203 operates so as to place the half wave plate 205 onto the optical axis of laser light L. When not rotating the polarization of laser light L emitted from the ellipticity regulator 201 , the 90° rotation regulator 203 operates so as to place the half wave plate 205 outside the optical path of laser light L (i.e., at a site where the laser light L does not pass through the half wave plate 205 ).
[0385] The dichroic mirror 103 is disposed such that the laser light L whose rotation of polarization is regulated by 90° or not by the 90° rotation regulator 203 is incident thereon and that the direction of optical axis of laser light L is changed by 90°. The laser processing apparatus 200 comprises a O-axis stage 213 for rotating the X-Y plane of the mounting table 107 about the thickness direction of the object to be processed 1 . The stage controller 115 regulates not only the movement of stages 109 , 111 , 113 , but also the movement of stage 213 .
[0386] With reference to FIGS. 40 and 43 , the laser processing method in accordance with the third embodiment of the present invention will now be explained. FIG. 43 is a flowchart for explaining this laser processing method. The object to be processed 1 is a silicon wafer. Steps S 101 to S 111 are the same as those of the first embodiment shown in FIG. 15 .
[0387] The ellipticity regulator 201 adjusts the ellipticity of laser light L having linear polarization LP emitted from the laser light source 101 (S 121 ). The laser light L having elliptical polarization EP with a desirable ellipticity can be obtained when the angle of direction θ of the quarter wave plate is changed in the ellipticity regulator 201 .
[0388] First, for processing the object to be processed 1 along the Y-axis direction, the major axis of an ellipse indicative of the elliptical polarization EP of laser light L is adjusted so as to coincide with the direction of the line 5 along which the object is intended to be cut extending in the Y-axis direction of the object to be processed 1 (S 123 ). This is achieved by rotating the O-axis stage 213 . Therefore, the θ-axis stage 213 functions as major axis adjusting means or linear polarization adjusting means.
[0389] For processing the object 1 along the Y-axis direction, the 90° rotation regulator 203 carries out adjustment which does not rotate the polarization of laser light L (S 125 ). Namely, it operates so as to place the half wave plate to the outside of the optical path of laser light L.
[0390] The laser light source 101 generates laser light L, whereas the line 5 along which the object is intended to be cut extending in the Y-axis direction in the surface 3 of the object to be processed 1 is irradiated with the laser light L. FIG. 44 is a plan view of the object 1 . The object 1 is irradiated with the laser light L such that the major axis indicative of the ellipse of elliptical polarization EP of laser light extends along the rightmost line 5 along which the object is intended to be cut in the object 1 . Since the light-converging point P of laser light L is positioned within the object 1 , molten processed regions are formed only within the object 1 . The Y-axis stage 111 is moved along the line 5 along which the object is intended to be cut, so as to form a molten processed region within the object to be processed 1 along the line 5 along which the object is intended to be cut.
[0391] Then, the X-axis stage 109 is moved, so as to irradiate the neighboring line 5 along which the object is intended to be cut with laser light L, and a molten processed region is formed within the object 1 along the neighboring line 5 along which the object is intended to be cut in a manner similar to that mentioned above. By repeating this, a molten processed region is formed within the object 1 along the lines along which the object is intended to be cut successively from the right side (S 127 ). FIG. 45 shows the case where the object 1 is irradiated with the laser light L having linear polarization. Namely, the object 1 is irradiated with laser light such that the direction of linear polarization LP of laser light extends along the line 5 along which the object is intended to be cut in the object 1 .
[0392] Next, the 90° rotation regulator 203 operates so as to place the half wave plate 205 ( FIG. 42 ) onto the optical axis of laser light L. This carries out adjustment for rotating the polarization of laser light emitted from the ellipticity regulator 219 by 90° (S 219 ).
[0393] Subsequently, the laser light 101 generates laser light L, whereas the line along which the object is intended to be cut extending in the X-axis direction of the surface 3 of the object 1 is irradiated with the laser light L. FIG. 46 is a plan view of the object 1 . The object 1 is irradiated with the laser light L such that the direction of the major axis of an ellipse indicative of the elliptical polarization EP of laser light L extends along the lowest line 5 along which the object is intended to be cut extending in the X-axis direction of the object 1 . Since the light-converging point P of laser light L is positioned within the object 1 , molten processed regions are formed only within the object 1 . The X-axis stage 109 is moved along the line 5 along which the object is intended to be cut, so as to form a molten processed region within the object 1 extending along the line 5 along which the object is intended to be cut.
[0394] Then, the Y-axis stage is moved, such that the immediately upper line 5 along which the object is intended to be cut is irradiated with the laser light L, whereby a molten processed region is formed within the object 1 along the line 5 along which the object is intended to be cut in a manner similar to that mentioned above. By repeating this, respective molten processed regions are formed within the object 1 along the individual lines along which the object is intended to be cut successively from the lower side (S 131 ). FIG. 47 shows the case where the object 1 is irradiated with the laser light L having linear polarization LP.
[0395] Then, the object 1 is bent along the lines along which the object is intended to be cut 5 , whereby the object 1 is cut (S 133 ) This divides the object 1 into silicon chips.
[0396] Effects of the third embodiment will be explained. According to the third embodiment, the object 1 is irradiated with pulse laser light L such that the direction of the major axis of an ellipse indicative of the elliptical polarization EP of pulse laser light L extends along the line 5 along which the object is intended to be cut as shown in FIGS. 44 and 46 . As a consequence, the size of crack spots in the direction of line 5 along which the object is intended to be cut becomes relatively large, whereby crack regions extending along lines along which the object is intended to be cut can be formed by a smaller number of shots. The third embodiment can efficiently form crack regions as such, thus being able to improve the processing speed of the object 1 . Also, the crack spot formed at the shot does not extend in directions other than the direction aligning with the line 5 along which the object is intended to be cut, whereby the object 1 can be cut precisely along the line 5 along which the object is intended to be cut. These results are similar to those of the fourth embodiment which will be explained later.
Fourth Embodiment
[0397] The fourth embodiment of the present invention will be explained mainly in terms of its differences from the third embodiment. FIG. 48 is a schematic diagram of this laser processing apparatus 300 . Among the constituents of the laser processing apparatus 300 , those identical to constituents of the laser processing apparatus 200 in accordance with the third embodiment shown in FIG. 40 will be referred to with numerals identical thereto without repeating their overlapping explanations.
[0398] The laser processing apparatus 300 is not equipped with the 90° rotation regulator 203 of the third embodiment. A θ-axis stage 213 can rotate the X-Y plane of a mounting table 107 about the thickness direction of the object to be processed 1 . This makes the polarization of laser light L emitted from the ellipticity regulator 201 relatively rotate by 90°.
[0399] The laser processing method in accordance with the fourth embodiment of the present invention will be explained. Operations of step S 101 to step S 123 in the laser processing method in accordance with the third embodiment shown in FIG. 43 are carried out in the fourth embodiment as well. The operation of subsequent step S 125 is not carried out, since the fourth embodiment is not equipped with the 90° rotation regulator 203 .
[0400] After step S 123 , the operation of step S 127 is carried out. The operations carried out so far process the object 1 as shown in FIG. 44 in a manner similar to that in the third embodiment. Thereafter, the stage controller 115 regulates the 8-axis stage 213 so as to rotate it by 90°. The rotation of the 8-axis stage 213 rotates the object 1 by 90° in the X-Y plane. Consequently, as shown in FIG. 49 , the major axis of elliptical polarization EP can be caused to align with a line along which the object is intended to be cut intersecting the line 5 along which the object is intended to be cut having already completed the modified region forming step.
[0401] Then, like step S 127 , the object 1 is irradiated with the laser light, whereby molten processed regions are formed within the object to be processed 1 along line 5 along which the object is intended to be cut successively from the right side. Finally, as with step S 133 , the object 1 is cut, whereby the object 1 is divided into silicon chips.
[0402] The third and fourth embodiments of the present invention explained in the foregoing relate to the forming of modified regions by multiphoton absorption. However, the present invention may cut the object to be processed by irradiating it with laser light while locating its light-converging point within the object so as to make the major axis direction of an ellipse indicative of elliptical polarization extend along a line along which the object is intended to be cut in the object without forming modified regions caused by multiphoton absorption. This can also cut the object along the line along which the object is intended to be cut efficiently.
Fifth Embodiment
[0403] In a fifth embodiment of the present invention and sixth and seventh embodiments thereof, which will be explained later, sizes of modified spots are controlled by regulating the magnitude of power of pulse laser light and the size of numerical aperture of an optical system including a light-converging lens. The modified spot refers to a modified part formed by a single pulse shot of pulse laser light (i.e., one pulse laser irradiation), whereas an assembly of modified spots forms a modified region. The necessity to control the sizes of modified spots will be explained with respect to crack spots by way of embodiment.
[0404] When a crack spot is too large, the accuracy of cutting an object to be cut along a line along which the object is intended to be cut decreases, and the flatness of the cross section deteriorates. This will be explained with reference to FIGS. 50 to 55 . FIG. 50 is a plan view of an object to be processed 1 in the case where crack spots are formed relatively large by using the laser processing method in accordance with this embodiment. FIG. 51 is a sectional view taken along LI-LI on the line 5 along which the object is intended to be cut in FIG. 50 . FIGS. 52 , 53 , and 54 are sectional views taken along lines LII-LII, LIII-LIII, and LIV-LIV orthogonal to the line 5 along which the object is intended to be cut in FIG. 50 , respectively. As can be seen from these drawings, the deviation in sizes of crack spots 9 becomes greater when the crack spots 90 are too large. Therefore, as shown in FIG. 55 , the accuracy of cutting the object 1 along the line 5 along which the object is intended to be cut becomes lower. Also, irregularities of cross sections 43 in the object 1 become so large that the flatness of the cross section 43 deteriorates. When crack spots 90 are formed relatively small (e.g., 20 μm or less) by using the laser processing apparatus in accordance with this embodiment, by contrast, crack spots 90 can be formed uniformly and can be restrained from widening in directions deviating from that of the line along which the object is intended to be cut as shown in FIG. 56 . Therefore, as shown in FIG. 57 , the accuracy of cutting the object 1 along the line 5 along which the object is intended to be cut and the flatness of cross sections 43 can be improved as shown in FIG. 57 .
[0405] When crack spots are too large as such, precise cutting along a line along which the object is intended to be cut and cutting for yielding a flat cross section cannot be carried out. If crack spots are extremely small with respect to an object to be processed having a large thickness, however, the object will be hard to cut.
[0406] The fact that this embodiment can control sizes of crack spots will be explained. As shown in FIG. 7 , when the peak power density is the same, the size of a crack spot in the case where the light-converging lens has a magnification of ×10 and an NA of 0.8 is smaller than that of a crack spot in the case where the light-converging lens has a magnification of ×50 and an NA of 0.55. The peak power density is proportional to the energy of laser light per pulse, i.e., the power of pulse laser light, as explained above, whereby the same peak power density means the same laser light power. When the laser light power is the same while the beam spot cross-sectional area is the same, sizes of crack spots can be regulated so as to become smaller (greater) as the numerical aperture of a light-converging lens is greater (smaller).
[0407] Also, even when the numerical aperture of the light-converging lens is the same, sizes of crack spots can be regulated so as to become smaller and larger when the laser light power (peak power density) is made lower and higher, respectively.
[0408] Therefore, as can be seen from the graph shown in FIG. 7 , sizes of crack spots can be regulated so as to become smaller when the numerical aperture of a light-converging lens is made greater or the laser light power is made lower. On the contrary, sizes of crack spots can be regulated so as to become greater when the numerical aperture of a light-converging lens is made smaller or when the laser light power is made higher.
[0409] The crack spot size control will further be explained with reference to the drawings. The embodiment shown in FIG. 58 is a sectional view of an object to be processed 1 within which pulse laser light L is converged by use of a light-converging lens having a predetermined numerical aperture. Regions 41 are those having yielded an electric field intensity at a threshold for causing multiphoton absorption or higher by this laser irradiation. FIG. 59 is a sectional view of a crack spot 90 formed due to the multiphoton absorption caused by irradiation with the laser light L. On the other hand, the embodiment shown in FIG. 60 is a sectional view of an object to be processed 1 within which pulse laser light L is converged by use of a light-converging lens having a numerical aperture greater than that in the embodiment shown in FIG. 58 . FIG. 61 is a sectional view of a crack spot 90 formed due to the multiphoton absorption caused by irradiation with the laser light L. The height h of crack spot 90 depends on the size of regions 41 in the thickness direction of the object 1 , whereas the width w of crack spot 90 depends on the size of regions 41 in a direction orthogonal to the thickness direction of the object 1 . Namely, when these sizes of regions 41 are made smaller and greater, the height h and width w of crack spot 90 can be made smaller and greater, respectively. As can be seen when FIGS. 59 and 61 are compared with each other, in the case where the laser light power is the same, the sizes of height h and width w of crack spot 90 can be regulated so as to become smaller (greater) when the numerical aperture of a light-converging lens is made greater (smaller).
[0410] The embodiment shown in FIG. 62 is a sectional view of an object to be processed 1 within which pulse laser light L having a power lower than that in the embodiment shown in FIG. 58 is converged. In the embodiment shown in FIG. 62 , since the laser light power is made lower, the area of regions 41 is smaller than that of regions 41 shown in FIG. 58 . FIG. 63 is a sectional view of a crack spot 90 formed due to the multiphoton absorption caused by irradiation with the laser light L. As can be seen when FIGS. 59 and 63 are compared with each other, in the case where the numerical aperture of the light-converging lens is the same, the sizes of height h and width w of crack spot 90 can be regulated so as to become smaller (greater) when the laser light power is made lower (higher).
[0411] The embodiment shown in FIG. 64 is a sectional view of an object to be processed 1 within which pulse laser light L having a power lower than that in the embodiment shown in FIG. 60 is converged. FIG. 65 is a sectional view of a crack spot 90 formed due to the multiphoton absorption caused by irradiation with the laser light L. As can be seen when FIGS. 59 and 65 are compared with each other, the sizes of height h and width w of crack spot 90 can be regulated so as to become smaller (greater) when the numerical aperture of the light-converging lens is made greater (smaller) while the laser light power is made lower (higher).
[0412] Meanwhile, the regions 41 indicative of those yielding an electric field intensity at a threshold for electric field intensity capable of forming a crack spot or higher are restricted to the light-converging point P and its vicinity due to the following reason: Since a laser light source with a high beam quality is utilized, this embodiment achieves a high convergence of laser light and can converge light up to about the wavelength of laser light. As a consequence, the beam profile of this laser light attains a Gaussian distribution, whereby the electric field intensity is distributed so as to become the highest at the center of the beam and gradually lowers as the distance from the center increases. The laser light is basically converged in the state of a Gaussian distribution in the process of being converged by a light-converging lens in practice as well. Therefore, the regions 41 are restricted to the light-converging point P and its vicinity.
[0413] As in the foregoing, this embodiment can control sizes of crack spots. Sizes of crack spots are determined in view of a requirement for a degree of precise cutting, a requirement for a degree of flatness in cross sections, and the magnitude of thickness of the object to be processed. Sizes of crack spots can be determined in view of the material of an object to be processed as well. This embodiment can control sizes of modified spots, thus making it possible to carry out precise cutting along a line along which the object is intended to be cut and yield a favorable flatness in cross sections by making modified spots smaller for objects to be processed having a relatively small thickness. Also, by making modified spots greater, it enables cutting of objects to be processed having a relatively large thickness.
[0414] There are cases where an object to be processed has respective directions easy and hard to cut due to the crystal orientation of the object, for embodiment. When cutting such an object, the size of crack spots 90 formed in the easy-to-cut direction is made greater as shown in FIGS. 56 and 57 , for embodiment. When the direction of a line along which the object is intended to be cut orthogonal to the line 5 along which the object is intended to be cut is a hard-to-cut direction, on the other hand, the size of crack spots 90 formed in this direction is made greater as shown in FIGS. 57 and 66 . Here, FIG. 66 is a sectional view of the object 1 shown in FIG. 57 taken along LXVI-LXVI. Hence, a flat cross section can be obtained in the easy-to-cut direction, while cutting is possible in the hard-to-cut direction as well.
[0415] Though the fact that sizes of modified spots are controllable has been explained in the case of crack spots, the same holds in melting spots and refractive index change spots. For embodiment, the power of pulse laser light can be expressed by energy per pulse (J), or average output (W) which is a value obtained by multiplying the energy per pulse by the frequency of laser light. The foregoing holds in sixth and seventh embodiments which will be explained later.
[0416] The laser processing apparatus in accordance with the fifth embodiment of the present invention will be explained. FIG. 67 is a schematic diagram of this laser processing apparatus 400 . The laser processing apparatus 400 will be explained mainly in terms of its differences from the laser processing apparatus 100 in accordance with the first embodiment shown in FIG. 14 .
[0417] The laser processing apparatus 400 comprises a power regulator 401 for adjusting the power of laser light L emitted from a laser light source 101 . The power regulator 401 comprises, for embodiment, a plurality of ND (neutral density) filters, and a mechanism for moving the individual ND filters to positions perpendicular to the optical axis of the laser light L and to the outside of the optical path of laser light L. An ND filter is a filter which reduces the intensity of light without changing the relative spectral distribution of energy. A plurality of ND filters have respective extinction factors different from each other. By using one of a plurality of ND filters or combining some of them, the power regulator 401 adjusts the power of laser light L emitted from the laser light source 101 . Here, a plurality of ND filters may have the same extinction factor, and the power regulator 401 may change the number of ND filters to be moved to positions perpendicular to the optical axis of laser light L, so as to adjust the power of laser light L emitted from the laser light source 101 .
[0418] The power regulator 401 may comprise a polarization filter disposed perpendicular to the optical axis of linearly polarized laser light L, and a mechanism for rotating the polarization filter about the optical axis of laser light L by a desirable angle. Rotating the polarization filter about the optical axis by a desirable angle in the power regulator 401 adjusts the power of laser light L emitted from the laser light source 101 .
[0419] Here, the driving current for a pumping semiconductor laser in the laser light source 101 can be regulated by a laser light source controller 102 which is an embodiment of driving current control means, so as to regulate the power of laser light L emitted from the laser light source 101 . Therefore, the power of laser light L can be adjusted by at least one of the power regulator 401 and laser light source controller 102 . If the size of a modified region can attain a desirable value due to the adjustment of power of laser light L by the laser light source controller 102 alone, the power regulator 401 is unnecessary. The power adjustment explained in the foregoing is effected when an operator of the laser processing apparatus inputs the magnitude of power into an overall controller 127 , which will be explained later, by using a keyboard or the like.
[0420] The laser processing apparatus 400 further comprises a dichroic mirror 103 disposed such that the laser light L whose power is adjusted by the power regulator 401 is incident thereon whereas the orientation of the optical axis of laser light L is changed by 90°; a lens selecting mechanism 403 including a plurality of light-converging lenses for converging the laser light L reflected by the dichroic mirror 103 ; and a lens selecting mechanism controller 405 for controlling the lens selecting mechanism 403 .
[0421] The lens selecting mechanism 403 comprises light-converging lenses 105 a , 105 b , 105 c , and a support plate 407 for supporting them. The numerical apertures of respective optical systems including the light-converging lenses 105 a , 105 b , 105 c differ from each other. According to a signal from the lens selecting mechanism controller 405 , the lens selecting mechanism 403 rotates the support plate 407 , thereby causing a desirable light-converging lens among the light-converging lenses 105 a , 105 b , 105 c to be placed onto the optical axis of laser light L. Namely, the lens selecting mechanism 403 is of revolver type.
[0422] The number of light-converging lenses attached to the lens selecting mechanism 403 is not restricted to 3 but may be other numbers. When the operator of the laser processing apparatus inputs a size of numerical aperture or an instruction for choosing one of the light-converging lenses 105 a , 105 b , 105 c into the overall controller 127 , which will be explained later, by using a keyboard or the like, the light-converging lens is chosen, namely, the numerical aperture is chosen.
[0423] Mounted on the mounting table 107 of the laser processing apparatus 400 is an object to be processed 1 irradiated with the laser light L converged by one of the light-converging lenses 105 a to 105 c which is disposed on the optical axis of laser light L.
[0424] The overall controller 127 is electrically connected to the power regulator 401 . FIG. 67 does not depict it. When the magnitude of power is fed into the overall controller 127 , the latter controls the power regulator 401 , thereby adjusting the power.
[0425] FIG. 68 is a block diagram showing a part of an embodiment of the overall controller 127 . The overall controller 127 comprises a size selector 411 , a correlation storing section 413 , and an image preparing section 415 . The operator of the laser processing apparatus inputs the magnitude of power of pulse laser light or the size of numerical aperture of the optical system including the light-converging lens to the size selector 411 by using a keyboard or the like. In this embodiment, the input may choose one of the light-converging lenses 105 a , 105 b , 105 c instead of the numerical aperture size being directly inputted. In this case, the respective numerical apertures of the light-converging lenses 105 a , 105 b , 105 c are registered in the overall controller 127 beforehand, and data of the numerical aperture of the optical system including the chosen light-converging lens is automatically fed into the size selector 411 .
[0426] The correlation storing section 413 has stored the correlation between the set of pulse laser power magnitude and numerical aperture size and the size of modified spot beforehand. FIG. 69 is an embodiment of table showing this correlation. In this embodiment, respective numerical apertures of the optical systems including the light-converging lenses 105 a , 105 b , 105 c are registered in the column for numerical aperture. In the column for power, magnitudes of power attained by the power regulator 401 are registered. In the column for size, sizes of modified spots formed by combinations of powers of their corresponding sets and numerical apertures are registered. For embodiment, the modified spot formed when the power is 1.24×10 11 (W/cm 2 ) while the numerical aperture is 0.55 has a size of 120 μm. The data of this correlation can be obtained by carrying out experiments explained in FIGS. 58 to 65 before laser processing, for embodiment.
[0427] When the magnitude of power and numerical aperture size are fed into the size selector 411 , the latter chooses the set having their corresponding values from the correlation storing section 413 , and sends data of size corresponding to this set to the monitor 129 . As a consequence, the size of a modified spot formed at thus inputted magnitude of power and numerical aperture size is displayed on the monitor 129 . If there is no set corresponding to these values, size data corresponding to a set having the closest values is sent to the monitor 129 .
[0428] The data of size corresponding to the set chosen by the size selector 411 is sent from the size selector 411 to the image preparing section 415 . According to this size data, the image preparing section 415 prepares image data of a modified spot in this size, and sends thus prepared data to the monitor 129 . As a consequence, an image of the modified spot is also displayed on the monitor 129 . Hence, the size and form of modified spot can be seen before laser processing.
[0429] The size of numerical aperture may be made variable while the magnitude of power is fixed. The table in this case will be as shown in FIG. 70 . For embodiment, the modified spot formed when the numerical aperture is 0.55 while the power is fixed at 1.49×10 11 (W/cm 2 ) has a size of 150 μm. Alternatively, the magnitude of power may be made variable while the size of numerical aperture is fixed. The table in this case will be as shown in FIG. 71 . For embodiment, the modified spot formed when the power is fixed at 1.19×10 11 (W/cm 2 ) while the numerical aperture is fixed at 0.8 has a size of 30 μm.
[0430] The laser processing method in accordance with the fifth embodiment of the present invention will now be explained with reference to FIG. 67 . The object to be processed 1 is a silicon wafer. In the fifth embodiment, operations of steps S 101 to S 111 are carried out as in the laser processing method in accordance with the first embodiment shown in FIG. 15 .
[0431] After step S 111 , the magnitude of power and numerical aperture size are fed into the overall controller 127 as explained above. According to the data of power inputted, the power of laser light L is adjusted by the power regulator 401 . According to the data of numerical aperture inputted, the lens selecting mechanism 403 chooses a light-converging lens by way of the lens selecting mechanism controller 405 , thereby adjusting the numerical aperture. These data are also fed into the size selector 411 of the overall controller 127 ( FIG. 68 ). As a consequence, the size and form of a melting spot formed within the object 1 upon irradiation of one pulse of laser light L are displayed on the monitor 129 .
[0432] Then, operations of steps S 113 to S 115 are carried out as in the laser processing method in accordance with the first embodiment shown in FIG. 15 . This divides the object 1 into silicon chips.
Sixth Embodiment
[0433] A sixth embodiment of the present invention will now be explained mainly in terms of its differences from the fifth embodiment. FIG. 72 is a schematic diagram of this laser processing apparatus 500 . Among the constituents of the laser processing apparatus 500 , those identical to constituents of the laser processing apparatus 400 in accordance with the fifth embodiment shown in FIG. 67 are referred to with numerals identical thereto without repeating their overlapping explanations.
[0434] In the laser processing apparatus 500 , a beam expander 501 is disposed on the optical axis of laser light L between a power regulator 401 and a dichroic mirror 103 . The beam expander 501 has a variable magnification, and is regulated by the beam expander 501 so as to increase the beam diameter of laser light L. The beam expander 501 is an embodiment of numerical aperture regulating means. The laser processing apparatus 500 is equipped with a single light-converging lens 105 instead of the lens selecting mechanism 403 .
[0435] The operations of the laser processing apparatus 500 differ from those of the laser processing apparatus of the fifth embodiment in the adjustment of numerical aperture based on the magnitude of numerical aperture fed into the overall controller 127 . This will be explained in the following. The overall controller 127 is electrically connected to the beam expander 501 . FIG. 72 does not depict this. When the size of numerical aperture is fed into the overall controller 127 , the latter carries out control for changing the magnitude of beam expander 501 . This regulates the magnification of beam diameter of the laser light L incident on the light-converging lens 105 . Therefore, with only one light-converging lens 105 , adjustment for increasing the numerical aperture of the optical system including the light-converging lens 105 is possible. This will be explained with reference to FIGS. 73 and 74 .
[0436] FIG. 73 is a view showing the convergence of laser light L effected by the light-converging lens 105 when the beam expander 501 is not provided. On the other hand, FIG. 74 is a view showing the convergence of laser light L effected by the light-converging lens 105 when the beam expander 501 is provided. As can be seen when FIGS. 73 and 74 are compared with each other, the sixth embodiment can achieve adjustment so as to increase the numerical aperture with reference to the numerical aperture of the optical system including the light-converging lens 105 in the case where the beam expander 501 is not provided.
Seventh Embodiment
[0437] A seventh embodiment of the present invention will now be explained mainly in terms of its differences from the fifth and sixth embodiments. FIG. 75 is a schematic diagram of this laser processing apparatus 600 . Among the constituents of the laser processing apparatus 600 , those identical to constituents of the laser processing apparatus in accordance with the fifth and sixth embodiments are referred to with numerals identical thereto without repeating their overlapping explanations.
[0438] In the laser processing apparatus 600 , an iris diaphragm 601 is disposed on the optical axis of laser light L instead of the beam expander 501 between a dichroic mirror 103 and a light-converging lens 105 . Changing the aperture size of the iris diaphragm 601 adjusts the effective diameter of the light-converging lens 105 . The iris diaphragm 601 is an embodiment of numerical aperture regulating means. The laser processing apparatus 600 further comprises an iris diaphragm controller 603 for changing the aperture size of the iris diaphragm 601 . The iris diaphragm controller 603 is controlled by an overall controller 127 .
[0439] The operations of the laser processing apparatus 600 differ from those of the laser processing apparatus of the fifth and sixth embodiments in the adjustment of numerical aperture based on the size of numerical aperture fed into the overall controller 127 . According to the inputted size of numerical aperture, the laser processing apparatus 600 changes the size of aperture of the iris diaphragm 601 , thereby carrying out adjustment for decreasing the effective diameter of the light-converging lens 105 . Therefore, with only one light-converging lens 105 , adjustment for decreasing the numerical aperture of the optical system including the light-converging lens 105 is possible. This will be explained with reference to FIGS. 76 and 77 .
[0440] FIG. 76 is a view showing the convergence of laser light L effected by the light-converging lens 105 when no iris diaphragm is provided. On the other hand, FIG. 77 is a view showing the convergence of laser light L effected by the light-converging lens 105 when the iris diaphragm 601 is provided. As can be seen when FIGS. 76 and 77 are compared with each other, the seventh embodiment can achieve adjustment so as to increase the numerical aperture with reference to the numerical aperture of the optical system including the light-converging lens 105 in the case where the iris diaphragm is not provided.
[0441] Modified embodiments of the fifth to seventh embodiments of the present invention will now be explained. FIG. 78 is a block diagram of the overall controller 127 provided in a modified embodiment of the laser processing apparatus in accordance with this embodiment. The overall controller 127 comprises a power selector 417 and a correlation storing section 413 . The correlation storing section 413 has already stored the correlation data shown in FIG. 71 . An operator of the laser processing apparatus inputs a desirable size of a modified spot to the power selector 417 by a keyboard or the like. The size of modified spot is determined in view of the thickness and material of the object to be modified and the like. According to this input, the power selector 417 chooses a power corresponding to the value of size identical to thus inputted size from the correlation storing section 413 , and sends it to the power regulator 401 . Therefore, when the laser processing apparatus regulated to this magnitude of power is used for laser processing, a modified spot having a desirable size can be formed. The data concerning this magnitude of power is also sent to the monitor 129 , whereby the magnitude of power is displayed. In this embodiment, the numerical aperture is fixed while power is variable. If no size at the value identical to that of thus inputted value is stored in the correlation storing section 413 , power data corresponding to a size having the closest value is sent to the power regulator 401 and the monitor 129 . This is the same in the modified embodiments explained in the following.
[0442] FIG. 79 is a block diagram of the overall controller 127 provided in another modified embodiment of the laser processing apparatus in accordance with this embodiment. The overall controller 127 comprises a numerical aperture selector 419 and a correlation storing section 413 . It differs from the modified embodiment of FIG. 78 in that the numerical aperture is chosen instead of the power. The correlation storing section 413 has already stored the data shown in FIG. 70 . An operator of the laser processing apparatus inputs a desirable size of a modified spot to the numerical aperture selector 419 by using a keyboard or the like. As a consequence, the numerical aperture selector 419 chooses a numerical aperture corresponding to a size having a value identical to that of the inputted size from the correlation storing section 413 , and sends data of this numerical aperture to the lens selecting mechanism controller 405 , beam expander 501 , or iris diaphragm controller 603 . Therefore, when the laser processing apparatus regulated to this size of numerical aperture is used for laser processing, a modified spot having a desirable size can be formed. The data concerning this numerical aperture is also sent to the monitor 129 , whereby the size of numerical aperture is displayed. In this embodiment, the power is fixed while numerical aperture is variable.
[0443] FIG. 80 is a block diagram of the overall controller 127 provided in still another modified embodiment of the laser processing apparatus in accordance with this embodiment. The overall controller 127 comprises a set selector 421 and a correlation storing section 413 . It differs from the embodiments of FIGS. 78 and 79 in that both power and numerical aperture are chosen. The correlation storing section 413 has stored the correlation between the set of power and numerical aperture and the size in FIG. 69 beforehand. An operator of the laser processing apparatus inputs a desirable size of a modified spot to the set selector 421 by using a keyboard or the like. As a consequence, the set selector 421 chooses a set of power and numerical aperture corresponding to thus inputted size from the correlation storing section 413 . Data of power in thus chosen set is sent to the power regulator 401 . On the other hand, data of numerical aperture in the chosen set is sent to the lens selecting mechanism controller 405 , beam expander 501 , or iris diaphragm controller 603 . Therefore, when the laser processing apparatus regulated to the power and numerical aperture of this set is used for laser processing, a modified spot having a desirable size can be formed. The data concerning the magnitude of power and size of numerical aperture is also sent to the monitor 129 , whereby the magnitude of power and size of numerical aperture is displayed.
[0444] These modified embodiments can control sizes of modified spots. Therefore, when the size of a modified spot is made smaller, the object to be processed can precisely be cut along a line along which the object is intended to be cut therein, and a flat cross section can be obtained. When the object to be cut has a large thickness, the size of modified spot can be enhanced, whereby the object can be cut.
Eighth Embodiment
[0445] An eighth embodiment of the present invention controls the distance between a modified spot formed by one pulse of laser light and a modified spot formed by the next one pulse of pulse laser light by regulating the magnitude of a repetition frequency of pulse laser light and the magnitude of relative moving speed of the light-converging point of pulse laser light. Namely, it controls the distance between adjacent modified spots. In the following explanation, the distance is assumed to be a pitch p. The control of pitch p will be explained in terms of a crack region by way of embodiment.
[0446] Let f (Hz) be the repetition frequency of pulse laser light, and v (mm/sec) be the moving speed of the X-axis stage or Y-axis stage of the object to be processed. The moving speeds of these stages are embodiments of relative moving speed of the light-converging point of pulse laser light. The crack part formed by one shot of pulse laser light is referred to as crack spot. Therefore, the number n of crack spots formed per unit length of the line 5 along which the object is intended to be cut is as follows:
[0000]
n=f/v.
[0447] The reciprocal of the number n of crack spots formed per unit length corresponds to the pitch p:
[0000] p= 1 /n.
[0448] Hence, the pitch p can be controlled when at least one of the magnitude of repetition frequency of pulse laser light and the magnitude of relative moving speed of the light-converging point is regulated. Namely, the pitch p can be controlled so as to become smaller when the repetition frequency f (Hz) is increased or when the stage moving speed v (mm/sec) is decreased. By contrast, the pitch p can be controlled so as to become greater when the repetition frequency f (Hz) is decreased or when the stage moving speed v (mm/sec) is increased.
[0449] Meanwhile, there are three ways of relationship between the pitch p and crack spot size in the direction of line 5 along which the object is intended to be cut as shown in FIGS. 81 to 83 . FIGS. 81 to 83 are plan views of an object to be processed along the line 5 along which the object is intended to be cut, which is formed with a crack region by the laser processing in accordance with this embodiment. A crack spot 90 is formed by one pulse of pulse laser light. Forming a plurality of crack spots 90 aligning each other along the line 5 along which the object is intended to be cut yields a crack region 9 .
[0450] FIG. 81 shows a case where the pitch p is greater than the size d. The crack region 9 is formed discontinuously along the line 5 along which the object is intended to be cut within the object to be processed. FIG. 82 shows a case where the pitch p substantially equals the size d. The crack region 9 is formed continuously along the line 5 along which the object is intended to be cut within the object to be processed. FIG. 83 shows a case where the pitch p is smaller than the size d. The crack region 9 is formed continuously along the line 5 along which the object is intended to be cut within the object to be processed.
[0451] In FIG. 81 , the crack region 9 is not continuous along the line 5 along which the object is intended to be cut, whereby the part of line 5 along which the object is intended to be cut keeps a strength to some extent. Therefore, when carrying out a step of cutting the object to be processed after laser processing, handling of the object becomes easier. In FIGS. 82 and 83 , the crack region 9 is continuously formed along the line 5 along which the object is intended to be cut, which makes it easy to cut the object while using the crack region 9 as a starting point.
[0452] The pitch p is made greater than the size d in FIG. 81 , and substantially equals the size d in FIG. 82 , whereby regions generating multiphoton absorption upon irradiation with pulse laser light can be prevented from being superposed on crack spots 90 which have already been formed. As a result, deviations in sizes of crack spots 90 can be made smaller. Namely, the inventor has found that, when a region generating multiphoton absorption upon irradiation with pulse laser light is superposed on crack spots 90 which have already been formed, deviations in sizes of crack spots 90 formed in this region become greater. When deviations in sizes of crack spots 90 become greater, it becomes harder to cut the object along a line along which the object is intended to be cut precisely, and the flatness of cross section deteriorates. In FIGS. 81 and 82 , deviations in sizes of crack spots can be made smaller, whereby the object to be processed can be cut along the line along which the object is intended to be cut precisely, while cross sections can be made flat.
[0453] As explained in the foregoing, the eighth embodiment of the present invention can control the pitch p by regulating the magnitude of repetition frequency of pulse laser light or magnitude of relative moving speed of the light-converging point of pulse laser light. This enables laser processing in conformity to the object to be processed by changing the pitch p in view of the thickness and material of the object and the like.
[0454] Though the fact that the pitch p can be controlled is explained in the case of crack spots, the same holds in melting spots and refractive index change spots. However, there are no problems even when melting spots and refractive index change spots are superposed on those which have already been formed. The relative movement of the light-converging point of pulse laser light may be realized by a case where the object to be processed is moved while the light-converging point of pulse laser light is fixed, a case where the light-converging point of pulse laser light is moved while the object is fixed, a case where the object and the light-converging point of pulse laser light are moved in directions opposite from each other, and a case where the object and the light-converging point of pulse laser light are moved in the same direction with their respective speeds different from each other.
[0455] With reference to FIG. 14 , the laser processing apparatus in accordance with the eighth embodiment of the present invention will be explained mainly in terms of its differences from the laser processing apparatus 100 in accordance with the first embodiment shown in FIG. 14 . The laser light source 101 is a Q-switch laser. FIG. 84 is a schematic diagram of the Q-switch laser provided in a laser light source 101 . The Q-switch laser comprises mirrors 51 , 53 which are disposed with a predetermined gap therebetween, a laser medium 55 disposed between the mirrors 51 and 53 , a pumping source 57 for applying a pumping input to the laser medium 55 , and a Q-switch 59 disposed between the laser medium 55 and the mirror 51 . The material of the laser medium 55 is Nd:YAG, for embodiment.
[0456] A pumping input is applied from the pumping source 57 to the laser medium 55 in a state where the loss in a resonator is made high by utilizing the Q-switch 59 , whereby the population inversion of the laser medium 55 is raised to a predetermined value. Thereafter, the Q-switch 59 is utilized for placing the resonator into a state with a low loss, so as to oscillate the accumulated energy instantaneously and generate pulse laser light L. A signal S (e.g., a change in a repetition frequency of an ultrasonic pulse) from a laser light source controller 102 controls the Q-switch 59 so as to make it attain a high state. Therefore, the signal S from the laser light source controller 102 can regulate the repetition frequency of pulse laser light L emitted from the laser light source 101 . The laser light source controller 102 is an embodiment of frequency adjusting means. The repetition frequency is regulated when an operator of the laser processing apparatus inputs the magnitude of repetition frequency to an overall controller 127 , which will be explained later, by using a keyboard or the like. The foregoing are details of the laser light source 101 .
[0457] During the laser processing, the object to be processed 1 is moved in the X- or Y-axis direction, so as to form a modified region along a line along which the object is intended to be cut. Therefore, when forming a modified region in the X-axis direction, the speed of relative movement of the light-converging point of laser light can be adjusted by regulating the moving speed of the X-axis stage 109 . When forming a modified region in the Y-axis direction, on the other hand, the speed of relative movement of the light-converging point of laser light can be adjusted by regulating the moving speed of the Y-axis stage 111 . The adjustment of the respective moving speeds of these stages is controlled by the stage controller 115 . The stage controller 115 is an embodiment of speed adjusting means. The speed is regulated when the operator of laser processing apparatus inputs the magnitude of speed to the overall controller 127 , which will be explained later, by using a keyboard or the like. The speed of relative movement of the light-converging point of pulse laser light can be adjusted when, while the light-converging point P is made movable, its moving speed is regulated.
[0458] The overall controller 127 of the laser processing apparatus in accordance with the eighth embodiment further adds other functions to the overall controller 127 of the laser processing apparatus in accordance with the first embodiment. FIG. 85 is a block diagram showing a part of an embodiment of the overall controller 127 of the laser processing apparatus in accordance with the eighth embodiment. The overall controller 127 comprises a distance calculating section 141 , a size storing section 143 , and an image preparing section 145 . To the distance calculating section 141 , the magnitude of repetition frequency of pulse laser light and respective magnitudes of moving speeds of the stages 109 , 111 are inputted. These inputs are effected by the operator of laser processing apparatus using a keyboard or the like.
[0459] The distance calculating section 141 calculates the distance (pitch) between adjacent spots by utilizing the above-mentioned expressions (n=f/v, and p=1/n). The distance calculating section 141 sends this distance data to the monitor 129 . As a consequence, the distance between modified spots formed at the inputted magnitudes of frequency and speed is displayed on the monitor 129 .
[0460] The distance data is also sent to the image preparing section 145 . The size storing section 143 has already stored therein sizes of modified spots formed in this laser processing apparatus. According to the distance data and the size data stored in the size storing section 143 , the image preparing section 145 prepares image data of a modified region formed by the distance and size, and sends thus prepared image data to the monitor 129 . As a consequence, an image of the modified region is also displayed on the monitor 129 . Hence, the distance between adjacent modified spots and the form of modified region can be seen before laser processing.
[0461] Though the distance calculating section 141 calculates the distance between modified spots by utilizing the expressions (n=f/v, and p=1/n), the following procedure may also be taken. First, a table having registered the relationship between the magnitude of repetition frequency, the moving speeds of stages 109 , 111 , and the distance between modified spots beforehand is prepared, and the distance calculating section 141 is caused to store data of this table. When the magnitude of repetition frequency and the magnitudes of moving speeds of stages 109 , 111 are fed into the distance calculating section 141 , the latter reads out from the above-mentioned table the distance between modified spots in the modified spots formed under the condition of these magnitude.
[0462] Here, the magnitudes of stage moving speeds may be made variable while the magnitude of repetition frequency is fixed. On the contrary, the magnitude of repetition frequency may be made variable while the magnitudes of stage moving speeds are fixed. Also, in these cases, the above-mentioned expressions and table are used in the distance calculating section 141 for carrying out processing for causing the monitor 129 to display the distance between modified spots and an image of the modified region.
[0463] As in the foregoing, the overall controller 127 shown in FIG. 85 inputs the magnitude of repetition frequency and the stage moving speeds, thereby calculating the distance between adjacent modified spots. Alternatively, a desirable distance between adjacent modified spots may be inputted, and the magnitude of repetition frequency and magnitudes of stage moving speeds may be controlled. This procedure will be explained in the following.
[0464] FIG. 86 is a block diagram showing a part of another embodiment of the overall controller 127 provided in the eighth embodiment. The overall controller 127 comprises a frequency calculating section 147 . The operator of laser processing apparatus inputs the magnitude of distance between adjacent modified spots to the frequency calculating section 147 by using a keyboard or the like. The magnitude of distance is determined in view of the thickness and material of the object to be processed and the like. Upon this input, the frequency calculating section 147 calculates a frequency for attaining this magnitude of distance according to the above-mentioned expressions and tables. In this embodiment, the stage moving speeds are fixed. The frequency calculating section 147 sends thus calculated data to the laser light source controller 102 . When the object to be processed is subjected to laser processing by the laser processing apparatus regulated to this magnitude of frequency, the distance between adjacent modified spots can attain a desirable magnitude. Data of this magnitude of frequency is also sent to the monitor 129 , whereby this magnitude of frequency is displayed.
[0465] FIG. 87 is a block diagram showing a part of still another embodiment the overall controller 127 provided in the eighth embodiment. The overall controller 127 comprises a speed calculating section 149 . In a manner similar to that mentioned above, the magnitude of distance between adjacent modified spots is fed into the speed calculating section 149 . Upon this input, the speed calculating section 149 calculates a stage moving speed for attaining this magnitude of distance according to the above-mentioned expressions and tables. In this embodiment, the repetition frequency is fixed. The speed calculating section 149 sends thus calculated data to the stage controller 115 . When the object to be processed is subjected to laser processing by the laser processing apparatus regulated to this magnitude of stage moving speed, the distance between adjacent modified spots can attain a desirable magnitude. Data of this magnitude of stage moving speed is also sent to the monitor 129 , whereby this magnitude of stage moving speed is displayed.
[0466] FIG. 88 is a block diagram showing a part of still another embodiment of the overall controller 127 provided in the eighth embodiment. The overall controller 127 comprises a combination calculating section 151 . It differs from the cases of FIGS. 86 and 87 in that both repetition frequency and stage moving speed are calculated. In a manner similar to that mentioned above, the distance between adjacent modified spots is fed into the combination calculating section 151 . According to the above-mentioned expressions and tables, the combination calculating section 151 calculates a repetition frequency and a stage moving speed for attaining this magnitude of distance.
[0467] The combination calculating section 151 sends thus calculated data to the stage controller 115 . The laser light source controller 102 adjusts the laser light source 101 so as to attain the calculated magnitude of repetition frequency. The stage controller 115 adjusts the stages 109 , 111 so as to attain the calculated magnitude of stage moving speed. When the object to be processed is subjected to laser processing by thus regulated laser processing apparatus, the distance between adjacent modified spots can attain a desirable magnitude. Data of thus calculated magnitude of repetition frequency and magnitude of stage moving speed are also sent to the monitor 129 , whereby thus calculated values are displayed.
[0468] The laser processing method in accordance with the eighth embodiment of the present invention will now be explained. The object to be processed 1 is a silicon wafer. In the eighth embodiment, operations from steps S 101 to S 111 are carried out in a manner similar to that of the laser processing method in accordance with the first embodiment shown in FIG. 15 .
[0469] After step S 111 , the distance between adjacent melting spots in the melting spots formed by one pulse of pulse laser, i.e., the magnitude of pitch p, is determined. The pitch p is determined in view of the thickness and material of the object 1 and the like. The magnitude of pitch p is fed into the overall controller 127 shown in FIG. 88 .
[0470] Then, in a manner similar to that of the laser processing method in accordance with the first embodiment shown in FIG. 15 , operations of step S 113 to S 115 are carried out. This divides the object 1 into silicon chips.
[0471] As explained in the foregoing, the eighth embodiment can control the distance between adjacent melting spots by regulating the magnitude of repetition frequency of pulse laser light, and regulating the magnitudes of moving speeds of X-axis stage 109 and Y-axis stage 111 . Changing the magnitude of distance in view of the thickness and material of the object 1 and the like enables processing inconformity to the aimed purpose.
Ninth Embodiment
[0472] A ninth embodiment of the present invention changes the position of the light-converging point of laser light irradiating the object to be processed in the direction of incidence to the object, thereby forming a plurality of modified regions aligning in the direction of incidence.
[0473] Forming a plurality of modified regions will be explained in terms of a crack region by way of embodiment. FIG. 89 is a perspective view of an object to be processed 1 formed with two crack regions 9 within the object 1 by using the laser processing method in accordance with the ninth embodiment of the present invention.
[0474] A method of forming two crack regions 9 will be explained in brief. First, the object 1 is irradiated with pulse laser light L, while the light-converging point of pulse laser light L is located within the object 1 near its rear face 21 and is moved along a line 5 along which the object is intended to be cut. This forms a crack region 9 ( 9 A) along the line 5 along which the object is intended to be cut within the object 1 near the rear face 21 . Subsequently, the object 1 is irradiated with the pulse laser light L, while the light-converging point of pulse laser light L is located within the object 1 near its surface 3 and is moved along the line 5 along which the object is intended to be cut. This forms a crack region 9 ( 9 B) along the line 5 along which the object is intended to be cut within the object 1 near the surface 3 .
[0475] Then, as shown in FIG. 90 , cracks 91 naturally grow from the crack regions 9 A, 9 B. Specifically, the cracks 91 naturally grow from the crack region 9 A toward the rear face 21 , from the crack region 9 A ( 9 B) toward the crack region 9 B ( 9 A), and from the crack region 9 B toward the surface 3 . This can form cracks 9 elongated in the thickness direction of the object in the surface of object 1 extending along the line 5 along which the object is intended to be cut, i.e., the surface to become a cross section. Hence, the object 1 can be cut along the line 5 along which the object is intended to be cut by artificially applying a relatively small force thereto or naturally without applying such a force.
[0476] As in the foregoing, the ninth embodiment forms a plurality of crack regions 9 , thereby increasing the number of locations to become starting points when cutting the object 1 . As a consequence, the ninth embodiment makes it possible to cut the object 1 even in the cases where the object 1 has a relatively large thickness, the object 1 is made of a material in which cracks 91 are hard to grow after forming the crack regions 9 , and so forth.
[0477] When cutting is difficult by two crack regions 9 alone, three or more crack regions 9 are formed. For embodiment, as shown in FIG. 91 , a crack region 9 C is formed between the crack region 9 A and crack region 9 B. Cutting can also be achieved in a direction orthogonal to the thickness direction of the object 1 as long as it is the direction of incidence of laser light as shown in FIG. 92 .
[0478] Preferably, in the ninth embodiment of the present invention, a plurality of crack regions 9 are successively formed from the side farther from the entrance face (e.g., surface 3 ) of the object to be processed on which the pulse laser light L is incident. For embodiment, in FIG. 89 , the crack region 9 A is formed first, and then the crack region 9 B is formed. If the crack regions 9 are formed successively from the side closer to the entrance face, the pulse laser L irradiated at the time of forming the crack region 9 to be formed later will be scattered by the crack region 9 formed earlier. As a consequence, deviations occur in sizes of the crack part (crack spot) formed by one shot of pulse laser light L constituting the crack region 9 formed later. Hence, the crack region 9 formed later cannot be formed uniformly. Forming the crack regions 9 successively from the side farther from the entrance face does not generate the above-mentioned scattering, whereby the crack region 9 formed later can be formed uniformly.
[0479] However, the order of forming a plurality of crack regions 9 in the ninth embodiment of the present invention is not restricted to that mentioned above. They may be formed successively from the side closer to the entrance face of the object to be processed, or formed randomly. In the random forming, for embodiment in FIG. 91 , the crack region 9 C is formed first, then the crack region 9 B, and finally the crack region 9 A is formed by reversing the direction of incidence of laser light.
[0480] Though the forming of a plurality of modified regions is explained in the case of crack regions, the same holds in molten processed regions and refractive index change regions. Though the explanation relates to pulse laser light, the same holds for continuous wave laser light.
[0481] The laser processing apparatus in accordance with the ninth embodiment of the present invention has a configuration similar to that of the laser processing apparatus 100 in accordance with the first embodiment shown in FIG. 14 . In the ninth embodiment, the position of light-converging point P in the thickness direction of the object to be processed 1 is adjusted by the Z-axis stage 113 . This can adjust the light-converging point P so as to locate it at a position closer to or farther from the entrance face (surface 3 ) than is a half thickness position in the thickness direction of the object to be processed 1 , and at a substantially half thickness position.
[0482] Here, adjustment of the position of light-converging point P in the thickness direction of the object to be processed caused by the Z-axis stage will be explained with reference to FIGS. 93 and 94 . In the ninth embodiment of the present invention, the position of light-converging point of laser light in the thickness direction of the object to be processed is adjusted so as to be located at a desirable position within the object with reference to the surface (entrance face) of the object. FIG. 93 shows the state where the light-converging point P of laser light L is positioned at the surface 3 of the object 1 . When the Z-axis stage is moved by z toward the light-converging lens 105 , the light-converging point P moves from the surface 3 to the inside of the object 1 as shown in FIG. 94 . The amount of movement of light-converging point P within the object 1 is Nz (where N is the refractive index of the object 1 with respect to the laser light L). Hence, when the Z-axis stage is moved in view of the refractive index of the object 1 with respect to the laser light L, the position of light-converging point P in the thickness direction of the object 1 can be controlled. Namely, a desirable position of the light-converging point P in the thickness direction of the object 1 is defined as the distance (Nz) from the surface 3 to the inside of the object 1 . The object 1 is moved in the thickness direction by the amount of movement (z) obtained by dividing the distance (Nz) by the above-mentioned refractive index (N). This can locate the light-converging point P at the desirable position.
[0483] As explained in the first embodiment, the stage controller 115 controls the movement of the Z-axis stage 113 according to focal point data, such that the focal point of visible light is located at the surface 3 . The laser processing apparatus 1 is adjusted such that the light-converging point P of laser light L is positioned at the surface 3 at the position of Z-axis stage 113 where the focal point of visible light is located at the surface 3 . Data of the amount of movement (z) explained in FIGS. 93 and 94 is fed into and stored in the overall controller 127 .
[0484] With reference to FIG. 95 , the laser processing method in accordance with the ninth embodiment of the present invention will now be explained. FIG. 95 is a flowchart for explaining this laser processing method. The object to be processed 1 is a silicon wafer.
[0485] Step S 101 is the same as step S 101 of the first embodiment shown in FIG. 15 . Subsequently, the thickness of the object 1 is measured. According to the result of measurement of thickness and the refractive index of object 1 , the amount of movement (z) of object 1 in the Z-axis direction is determined (S 103 ). This is the amount of movement of object in the Z-axis direction with reference to the light-converging point of laser light L positioned at the surface 3 of object 1 in order for the light-converging point P of laser light L to be located within the object 1 . Namely, the position of light-converging point P in the thickness direction of object 1 is determined. The position of light-converging point P is determined in view of the thickness and material of object 1 and the like. In this embodiment, data of a first movement amount for positioning the light-converging point P near the rear face within the object 1 and data of a second movement amount for positioning the light-converging point P near the surface 3 within the object 1 are used. A first molten processed region to be formed is formed by using the data of first movement amount. A second molten processed region to be formed is formed by using the data of second movement amount. Data of these movement amounts are fed into the overall controller 127 .
[0486] Steps S 105 and S 107 are the same as steps S 105 and S 107 in the first embodiment shown in FIG. 15 . The focal point data calculated by step S 107 is sent to the stage controller 115 . According to the focal point data, the stage controller 115 moves the Z-axis stage 113 in the Z-axis direction (S 109 ). This positions the focal point of visible light of the observation light source 117 at the surface 3 . At this point of Z-axis stage 113 , the focal point P of pulse laser light L is positioned at the surface 3 . Here, according to imaging data, the imaging data processor 125 calculates enlarged image data of the surface of object 1 including the line 5 along which the object is intended to be cut. The enlarged image data is sent to the monitor 129 by way of the overall controller 127 , whereby an enlarged image in the vicinity of the line 5 along which the object is intended to be cut is displayed on the monitor 129 .
[0487] The data of first movement amount determined by step S 103 has already been inputted to the overall controller 127 , and is sent to the stage controller 115 . According to this data of movement amount, the stage controller 115 moves the object 1 in the Z-axis direction by using the Z-axis stage 113 to a position where the light-converging point P of laser light L is located within the object 1 (S 111 ). This inside position is near the rear face of the object 1 .
[0488] Next, as in step S 113 of the first embodiment shown in FIG. 15 , a molten processed region is formed within the object 1 so as to extend along the line 5 along which the object is intended to be cut (S 113 ). The molten processed region is formed near the rear face within the object 1 .
[0489] Then, according to the data of second movement amount as in step S 111 , the object 1 is moved in the Z-axis direction by the Z-axis stage 113 to a position where the light-converging point P of laser light L is located within the object 1 (S 115 ). Subsequently, as in step S 113 , a molten processed region is formed within the object 1 (S 117 ). In this step, the molten processed region is formed near the surface 3 within the object 1 .
[0490] Finally, the object 1 is bent along the line 5 along which the object is intended to be cut, and thus is cut (S 119 ). This divides the object 1 into silicon chips.
[0491] Effects of the ninth embodiment of the present invention will be explained. The ninth embodiment forms a plurality of modified regions aligning in the direction of incidence, thereby increasing the number of locations to become starting points when cutting the object 1 . In the case where the size of object 1 in the direction of incidence of laser light is relatively large or where the object 1 is made of a material in which cracks are hard to grow from a modified region, for embodiment, the object 1 is hard to cut when only one modified region exists along the line 5 along which the object is intended to be cut. In such a case, forming a plurality of modified regions as in this embodiment can easily cut the object 1 .
Tenth Embodiment
[0492] A tenth embodiment of the present invention controls the position of a modified region in the thickness direction of an object to be processed by adjusting the light-converging point of laser light in the thickness direction of the object.
[0493] This positional control will be explained in terms of a crack region by way of embodiment. FIG. 96 is a perspective view of an object to be processed 1 in which a crack region 9 is formed within the object 1 by using the laser processing method in accordance with the tenth embodiment of the present invention. The light-converging point of pulse laser L is located within the object 1 through the surface (entrance face) 3 of the object with respect to the pulse laser light L. The light-converging point is adjusted so as to be located at a substantially half thickness position in the thickness direction of the object 1 . When the object to be processed 1 is irradiated with the line 5 along which the object is intended to be cut under these conditions, a crack region 9 is formed along a line 5 along which the object is intended to be cut at a half thickness position of the object 1 and its vicinity.
[0494] FIG. 97 is a partly sectional view of the object 1 shown in FIG. 96 . After the crack region 9 is formed, cracks 91 are naturally grown toward the surface 3 and rear face 21 . When the crack region 9 is formed at the half thickness position and its vicinity in the thickness direction of the object 1 , the distance between the naturally growing crack 91 and the surface 3 (rear face 21 ) can be made relatively long, for embodiment, in the case where the object 1 has a relatively large thickness. Therefore, a part to be cut extending along the line 5 along which the object is intended to be cut in the object 1 maintains a strength to a certain extent. Therefore, when carrying out the step of cutting the object 1 after terminating the laser processing, handling the object becomes easier.
[0495] FIG. 98 is a perspective view of an object to be processed 1 including a crack region 9 formed by using the laser processing method in accordance with the tenth embodiment of the present invention as with FIG. 96 . The crack region 9 shown in FIG. 98 is formed when the light-converging point of pulse laser light L is adjusted so as to be located at a position closer to the surface (entrance face) 3 than is a half thickness position in the thickness direction of the object 1 . The crack region 9 is formed on the surface 3 side within the object 1 . FIG. 99 is a partly sectional view of the object 1 shown in FIG. 98 . Since the crack region 9 is formed on the surface 3 side, naturally growing cracks 91 reach the surface 3 or its vicinity. Hence, fractures extending along the line 5 along which the object is intended to be cut are likely to occur in the surface 3 , whereby the object 1 can be cut easily.
[0496] In the case where the surface 3 of the object 1 is formed with electronic devices and electrode patterns in particular, forming the crack region 9 near the surface 3 can prevent the electronic devices and the like from being damaged when cutting the object 1 . Namely, growing cracks 91 from the crack region 9 toward the surface 3 and rear face 21 of the object 1 cuts the object 1 . Cutting may be achieved by the natural growth of cracks 91 alone or by artificially growing cracks 91 in addition to the natural growth of crack 91 . When the distance between the crack region 9 and the surface 3 is relatively long, the deviation in the growing direction of cracks 91 on the surface 3 side becomes greater. As a consequence, the cracks 91 may reach regions formed with electronic devices and the like, thereby damaging the electronic devices and the like. When the crack region 9 is formed near the surface 3 , the distance between the crack region 9 and the surface 3 is relatively short, whereby the deviation in growing direction of cracks 91 can be made smaller. Therefore, cutting can be effected without damaging the electronic devices and the like. When the crack region 9 is formed at a location too close to the surface 3 , the crack region 9 is formed at the surface 3 . As a consequence, the random form of the crack region 9 itself appears at the surface 3 , which causes chipping, thereby deteriorating the accuracy in breaking and cutting.
[0497] The crack region 9 can also be formed while the light-converging point of pulse laser light L is adjusted so as to be located at a position farther from the surface 3 than is a half thickness position in the thickness direction of the object 1 . In this case, the crack region 9 is formed on the rear face 21 side within the object 1 .
[0498] As with FIG. 96 , FIG. 100 is a perspective view of the object 1 including crack regions formed by using the laser processing method in accordance with the tenth embodiment of the present invention. The crack region 9 in the X-axis direction shown in FIG. 100 is formed when the light-converging point of pulse laser light L is adjusted so as to be located at a position farther from the surface (entrance face) 3 than is a half thickness position in the thickness direction of the object 1 . The crack region 9 in the Y-axis direction is formed when the light-converging point of pulse laser light L is adjusted so as to be located at a position closer to the surface 3 than is the half thickness position in the thickness direction of the object 1 . The crack region 9 in the X-axis direction and the crack region in the Y-axis direction cross each other three-dimensionally.
[0499] When the object 1 is a semiconductor wafer, for embodiment, a plurality of crack regions 9 are formed in parallel in each of the X- and Y-axis directions. This forms the crack regions 9 like a lattice in the semiconductor wafer, whereas the latter is divided into individual chips while using the lattice-like crack regions as starting points. When the crack region 9 in the X-axis direction and the crack region 9 in the Y-axis direction are located at the same position in the thickness direction of the object 1 , there occurs a location where the crack region 9 in the X-axis direction and the crack region 9 in the Y-axis direction intersect each other at right angles. At the location where the crack regions 9 intersect each other at right angles, they are superposed on each other, which makes it difficult for the cross section in the X-axis direction and the cross section in the Y-axis direction to intersect each other at right angles with a high accuracy. This inhibits the object 1 from being cut precisely at the intersection.
[0500] When the position of the crack region 9 in the X-axis direction and the position of the crack region 9 in the Y-axis direction differ from each other in the thickness direction of the object 1 as shown in FIG. 100 , the crack region 9 in the X-axis direction and the crack region 9 in the Y-axis direction can be prevented from being superposed on each other. This enables precise cutting of the object 1 .
[0501] In the crack region 9 in the X-axis direction and the crack region 9 in the Y-axis direction, the crack region 9 to be formed later is preferably formed closer to the surface (entrance face) 3 than is the crack region 9 formed earlier. If the crack region 9 to be formed later is formed closer to the rear face 21 than is the crack region 9 formed earlier, the pulse laser light L irradiated when forming the crack region 9 to be formed later is scattered by the crack region 9 formed earlier at the location where the cross section in the X-axis direction and the cross section in the Y-axis direction intersect each other at right angles. This forms deviations between the size of a part formed at a position to become the above-mentioned intersecting location and the size of a part formed at another position in the crack region 9 to be formed later. Therefore, the crack region 9 to be formed later cannot be formed uniformly.
[0502] When the crack region 9 to be formed later is formed closer to the surface 3 than is the crack region 9 formed earlier, by contrast, scattering of the pulse laser light L does not occur at a position to become the above-mentioned intersecting location, whereby the crack region 9 to be formed later can be formed uniformly.
[0503] As explained in the foregoing, the tenth embodiment of the present invention adjusts the position of light-converging point of laser light in the thickness direction of an object to be processed, thereby being able to control the position of a modified region in the thickness direction of the object. Changing the position of light-converging point in view of the thickness and material of the object to be processed and the like enables laser processing in conformity to the object.
[0504] Though the fact that the position of a modified region can be controlled is explained in the case of a crack region, the same holds in molten processed regions and refractive index change regions. Though the explanation relates to pulse laser light, the same holds for continuous wave laser light.
[0505] The laser processing apparatus in accordance with the tenth embodiment of the present invention has a configuration similar to the laser processing apparatus 100 in accordance with the first embodiment shown in FIG. 14 . In the tenth embodiment, the Z-axis stage 113 adjusts the position of light-converging point P in the thickness direction of object 1 . This can adjust the light-converging point P so as to locate it at a position closer to or farther from the entrance face (surface 3 ) than is a half thickness position in the thickness direction of the object 1 or at a substantially half thickness position, for embodiment. These adjustment operations and the placement of the light-converging point of laser light within the object can also be achieved by moving the light-converging lens 105 in the Z-axis direction. Since there are cases where the object 1 moves in the thickness direction thereof and where the light-converging lens 105 moves in the thickness direction of the object 1 in the present invention, the amount of movement of the object 1 in the thickness direction of the object 1 is defined as a first relative movement amount or a second relative movement amount.
[0506] The adjustment of light-converging point P in the thickness direction of the object to be processed caused by the Z-axis stage is the same as that in the ninth embodiment explained with reference to FIG. 93 and FIG. 94 .
[0507] The imaging data processor 125 calculates focal point data for locating the focal point of visible light generated by the observation light source 117 on the surface 3 according to the imaging data in the tenth embodiment as well. According to this focal point data, the stage controller 115 controls the movement of the Z-axis stage 113 , so as to locate the focal point of visible light at the surface 3 . The laser processing apparatus 1 is adjusted such that the light-converging point P of laser light L is located at the surface 3 at the position of Z-axis stage 113 where the focal point of visible light is located at the surface 3 . Hence, the focal point data is an embodiment of second relative movement amount of the object 1 in the thickness direction thereof required for locating the light-converging point P at the surface (entrance face) 3 . The imaging data processor 125 has a function of calculating the second relative movement amount.
[0508] Data of the movement amount (z) explained with reference to FIGS. 93 and 94 is fed into and stored in the overall controller 127 . Namely, the overall controller 127 has a function of storing data of the relative movement amount of the object to be processed 1 in the thickness direction of the object 1 . The overall controller 127 , stage controller 115 , and Z-axis stage 113 adjust the position of light-converging point of pulse laser light converged by the light-converging lens within the range of thickness of the object 1 .
[0509] The laser processing method in accordance with the tenth embodiment will be explained with reference to the laser processing apparatus in accordance with the first embodiment shown in FIG. 14 and the flowchart for the laser processing method in accordance with the first embodiment shown in FIG. 15 . The object to be processed 1 is a silicon wafer.
[0510] Step S 101 is the same as step S 101 of the first embodiment shown in FIG. 15 . Subsequently, as in step S 103 of the first embodiment shown in FIG. 15 , the thickness of object 1 is measured. According to the result of measurement of thickness and the refractive index, the amount of movement (z) in the Z-axis direction of object 1 is determined (S 103 ). This is the amount of movement of object 1 in the Z-axis direction with reference to the light-converging point of laser light L positioned at the surface 3 of object 1 required for positioning the light-converging point P of laser light L within the object 1 . Namely, the position of light-converging point P in the thickness direction of object 1 is determined. The amount of movement (z) in the Z-axis direction is one embodiment of data of relative movement of the object 1 in the thickness direction thereof. The position of light-converging point P is determined in view of the thickness and material of the object 1 , effects of processing (e.g., easiness to handle and cut the object), and the like. This data of movement amount is fed into the overall controller 127 .
[0511] Steps S 105 and S 107 are similar to steps S 105 and S 107 of the first embodiment shown in FIG. 15 . The focal point data calculated by step S 107 is data of a second movement amount in the Z-axis direction of object 1 .
[0512] This focal point data is sent to the stage controller 115 . According to this focal point data, the stage controller 115 moves the Z-axis stage 113 in the Z-axis direction (S 109 ). This positions the focal point of visible light of the observation light source 117 at the surface 3 . At this position of Z-axis stage 113 , the light-converging point P of pulse laser light L is positioned at the surface 3 . According to imaging data, the imaging data processor 125 calculates enlarged image data of the surface of object 1 including the line 5 along which the object is intended to be cut. This enlarged image data is sent to the monitor 129 by way of the overall controller 127 , whereby an enlarged image near the line 5 along which the object is intended to be cut is displayed on the monitor 127 .
[0513] Data of the relative movement amount determined by step S 103 has already been inputted to the overall controller 127 , and is sent to the stage controller 115 . According to this data of movement amount, the stage controller 115 causes the Z-axis stage 113 to move the object 1 in the Z-axis direction at a position where the light-converging point P of laser light is located within the object 1 (S 111 ).
[0514] Steps S 113 and S 115 are similar to steps S 113 and S 115 shown in FIG. 15 . The foregoing divides the object 1 into silicon chips.
[0515] Effects of the tenth embodiment of the present invention will be explained. The tenth embodiment irradiates the object to be processed 1 with pulse laser light L while adjusting the position of light-converging point P in the thickness direction of object 1 , thereby forming a modified region. This can control the position of a modified region in the thickness direction of object 1 . Therefore, changing the position of a modified region in the thickness direction of object 1 according to the material and thickness of object 1 , effects of processing, and the like enables cutting in conformity to the object 1 .
Eleventh Embodiment
[0516] A Eleventh embodiment of the present invention will now be explained. The laser processing method in accordance with the eleventh embodiment comprises a modified region forming step (first step) of forming a modified region caused by multiphoton absorption within an object to be processed, and a stress step (second step) of generating a stress at a part where the object is cut. In the eleventh embodiment, the same laser light irradiation is carried out in the modified region forming step and stress step. Therefore, a laser processing apparatus, which was explained above, emits laser light twice under the same condition in the modified region forming step and stress step, respectively.
[0517] With reference to FIGS. 14 and 101 , the laser processing method in accordance with the eleventh embodiment will now be explained. FIG. 101 is a flowchart for explaining the laser processing method.
[0518] Steps S 101 , S 103 , S 105 , S 107 , S 109 and S 111 shown in FIG. 101 , are the same as theses shown in FIG. 15 , and therefore, the detailed explanations of the Steps S 101 , S 103 , S 105 , S 107 , S 109 and S 111 are omitted.
[0519] After Step S 111 , laser light L is generated from the laser light source 101 , so as to irradiate the line 5 along which the object is intended to be cut 5 in the surface 3 of the object 1 therewith. FIG. 102 is a sectional view of the object 1 including a crack region 9 during laser processing in the modified region forming step. Since the light-converging point P of laser light L is positioned within the object 1 as depicted, the crack region 9 is formed only within the object 1 . Subsequently, the X-axis stage 109 and Y-axis stage 111 are moved along the line to be cut 5 , so as to form the crack region 9 within the object 1 along the line 5 along which the object is intended to be cut (S 1113 ).
[0520] After the modified region is formed, the crack region 9 is irradiated with the laser light L having for example, wavelength of 1064 nm (YAG laser) along the line 5 along which the object is intended to be cut in the surface 3 of the object 1 again under the same condition (i.e., the light-converging point P is located in the crack region 9 that is a modified region). The laser light L has a transparent characteristics to non-molten processed region of the object, that is, except for the molten processed region of the object, and a high absorption characteristics to the molten processed region comparing with the non-molten processed region. As a consequence, the absorption of laser light L due to scattering by the crack region 9 or the like or the generation of multiphoton absorption in the crack region 9 heats the object 1 along the crack region 9 , thereby generating a stress such as a thermal stress due to a temperature difference (S 1114 ). FIG. 103 is a sectional view of the object 1 including the crack region 9 during laser processing in the stress step. As depicted, the crack is further grown by the stress step while using the crack region 9 as a start point, so as to reach the surface 3 and rear face 21 of the object 1 , thus forming a cut section 10 in the object 1 , whereby the object 1 is cut (S 1115 ). As a consequence, the object 1 is divided into chips.
[0521] Though the eleventh embodiment carries out the same laser light irradiation as that of the modified region forming step in the stress step, it will be sufficient if laser light transmittable through an unmodified region which is a region not formed with a crack region in the object to be processed but more absorbable by the crack region than by the unmodified region is emitted. This is because of the fact that the laser light is hardly absorbed at the surface of the object, whereas the object is heated along the crack region, whereby a stress such as a thermal stress due to a temperature difference occurs in this case as well.
[0522] Though the eleventh embodiment relates to a case where a crack region is formed as the modified region, the same applies to cases where the above-mentioned molten processed region and refractive index change region are formed as the modified region, whereby a stress can occur upon irradiation with laser light in the stress step, so as to generate and grow a crack while using the molten processed region and refractive index change region as a start point and thereby cut the object.
[0523] Even when the crack grown by the stress step while using the modified region as a start point fails to reach the surface and rear face of the object in the case where the object has a large thickness or the like, the object can be broken and cut by applying an artificial force such as a bending stress or shearing stress thereto. This artificial force can be kept smaller, whereby unnecessary fractures deviating from the line to be cut can be prevented from occurring in the surface of the object.
[0524] Effects of the eleventh embodiment will now be explained. In the modified region forming step of this embodiment, the line 5 along which the object is intended to be cut is irradiated with pulse laser light L while locating the light-converging point P within the object to be processed 1 under a condition causing multiphoton absorption. Also, the X-axis stage 109 and Y-axis stage 111 are moved, so as to shift the light-converging point P along the line 5 along which the object is intended to be cut. This forms a modified region (e.g., crack region, molten processed region, or refractive index change region) within the object 1 along the line 5 along which the object is intended to be cut. When an object to be processed has a start point in a part to be cut, the object can be broken and cut with a relatively small force. In the stress step of the eleventh embodiment, the same laser light irradiation as that of the modified region forming step is carried out in the stress step, so as to generate a stress such as a thermal stress due to a temperature difference. As a consequence, the object 1 can be cut by a relatively small force, e.g., a stress such as a thermal stress due to a temperature difference. Therefore, the object 1 can be cut without generating unnecessary fractures deviating from the line 5 along which the object is intended to be cut in the surface 3 of the object 1 .
[0525] Since the object 1 is irradiated with the pulse laser light L while locating the light-converging point P within the object 1 under a condition causing multiphoton absorption in the modified region forming step, the pulse laser light L is transmitted there through and is hardly absorbed at the surface 3 of the object 1 in the eleventh embodiment. In the stress step, the same laser light irradiation as that of the modified region forming step is carried out. Therefore, the surface 3 does not incur damages such as melt caused by irradiation with laser light.
[0526] As explained in the foregoing, the eleventh embodiment can cut the object 1 without generating unnecessary fractures deviating from the line 5 along which the object is intended to be cut or melt in the surface 3 of the object 1 . Therefore, in the case where the object 1 is a semiconductor wafer, for embodiment, semiconductor chips can be cut out from the semiconductor wafer without generating unnecessary fractures deviating from lines along which the object is intended to be cut or melt in the semiconductor chips. The same holds in objects to be processed having a surface formed with electrode patterns, and those having a surface formed with electronic devices such as piezoelectric device wafers and glass substrates formed with display devices such as liquid crystals. Hence, this embodiment can improve the yield of products (e.g., semiconductor chips, piezoelectric device chips, display devices such as liquid crystals) made by cutting objects to be processed.
[0527] Also, in the eleventh embodiment, the line 5 along which the object is intended to be cut in the surface 3 of the object 1 does not melt, whereby the width of the line 5 along which the object is intended to be cut (which is the gap between regions to become semiconductor chips in the case of a semiconductor wafer, for embodiment) can be reduced. This can increase the number of products prepared from a single object to be processed 1 , and improve the productivity of products.
[0528] Since laser light is used for cutting and processing the object 1 , the eleventh embodiment enables processing more complicated than that in dicing with a diamond cutter. For the eleventh embodiment, cutting and processing can be carried out even when lines 5 along which the object 1 is intended to be cut 5 have a complex form as shown in FIG. 16 also.
[0529] The laser processing method in accordance with the eleventh embodiment according to the present invention can cut an object to be processed without generating melt or unnecessary fractures deviating from the line to be cut in the surface of the object. Therefore, the yield and productivity of products (e.g., semiconductor chips, piezoelectric device chips, and display devices such as liquid crystals) manufactured by cutting objects to be processed can be improved.
[0530] Besides, in the above eleventh embodiments, the crack which is grown from the crack region 9 in the stress step reaches the surface 3 and rear face 21 of the object 1 , but the crack which is grown from the crack region 9 in the stress step the laser light L may be grown so as not to reach the surface 3 and rear face 21 of the object.
Twelfth Embodiment
[0531] The twelve embodiment according to the present invention will now be explained. The laser processing method in accordance with the twelfth embodiment comprises a modified region forming step of forming a modified region caused by multiphoton absorption within an object to be processed, and a stress step of generating a stress at a part where the object is cut, as similar to the eleventh embodiment.
[0532] A laser processing apparatus for the twelfth embodiment is the same as that of the first embodiment as shown in FIG. 14 , and the detailed explanation of the laser processing apparatus is omitted.
[0533] An absorbable laser irradiating apparatus used in the stress step of the twelfth embodiment employs the same configuration as that of the above-mentioned laser processing apparatus 100 as shown in FIG. 14 except for the laser light source and diachronic mirror. The laser light source in the absorbable laser irradiating apparatus uses CO 2 laser with a wavelength of 10.6 μm for generating continuous wave laser light. This is because of the fact that it is absorbable by the object 1 to be processed, which is a Pyrex glass wafer. Alternatively, the laser diode may be used as a light source for generating the absorbable laser light with a wavelength of 808 nm, 14 W as output power and beam size of about 200 μm. The laser light generated by such laser light source has a absorption characteristics to the object 1 and will hereinafter be referred to as “absorbable laser light”. Here, its beam quality is TEM 00 , whereas its polarization characteristic is that of linear polarization. This laser light source has an output of 10 W or less in order to attain such an intensity that the object to be processed 1 is heated but not melted thereby. The diachronic mirror of the absorbable laser irradiating apparatus has a function of reflecting the absorbable laser light, and is arranged so as to change the orientation of the optical axis of absorbable laser light by 90°.
[0534] With reference to FIGS. 14 and 104 , the laser processing method in accordance with the twelfth embodiment will now be explained. FIG. 104 is a flowchart for explaining the laser processing method.
[0535] Steps S 101 , S 103 , S 105 , S 107 , S 109 and S 111 shown in FIG. 104 , are the same as theses shown in FIG. 15 , and therefore, the detailed explanations of the Steps S 101 , S 103 , S 105 , S 107 , S 109 and S 111 are omitted.
[0536] Firstly, as shown in FIG. 104 , steps S 101 and S 103 are executed and next step S 104 is executed. In the step S 104 , the object 1 is mounted on the mounting table 107 of the laser processing apparatus 100 (S 104 ). Next steps S 105 , S 107 , S 109 , and S 111 are executed. After Step 111 of FIG. 104 , laser light L is generated from the laser light source 101 , so as to irradiate the line 5 along which the object is intended to be cut in the surface 3 of the object 1 therewith. FIG. 102 is a sectional view of the object 1 including a crack region 9 during laser processing in the modified region forming step. Since the light-converging point P of laser light L is positioned within the object 1 as depicted, the crack region 9 is formed only within the object 1 . Subsequently, the X-axis stage 109 and Y-axis stage 111 are moved along the line 5 along which the object is intended to be cut, so as to form the crack region 9 within the object 1 along the line 5 along which the object is intended to be cut (S 1213 ).
[0537] After the modified region is formed by the laser processing apparatus 100 , the object 1 is transferred to the mounting table 107 of the absorbable laser irradiating apparatus, so as to be mounted thereon (S 1215 ). The object 1 does not break into pieces, since the crack region 9 in the modified region forming step is formed only therewithin, and thus can easily be transferred.
[0538] The object 1 is illuminated in step 1217 , focal point data for positioning the focal point of visible light from the observation light source at the surface 3 of the object 1 is calculated in step 1219 , and the object 1 is moved in the Z-axis direction so as to position the focal point at the surface 3 of the object 1 in step 1221 , thereby locating the light-converging point of absorbable laser light L 2 at the surface 3 of the object. Here, details of operations in the steps 1217 , 1219 , and 1221 are similar to those of steps 105 , 107 , and 109 in the above-mentioned laser processing apparatus 100 .
[0539] Next, absorbable laser light L 2 is generated from the laser light source of the absorbable laser irradiating apparatus, so as to irradiate the line 5 along which the object is intended to be cut in the surface 3 of the object 1 therewith. Here, the vicinity of the line 5 along which the object is intended to be cut may be irradiated as well. Then, the X-axis stage and Y-axis stage of the absorbable laser irradiating apparatus are moved along the line 5 along which the object is intended to be cut, so as to heat the object 1 along the line 5 along which the object is intended to be cut, thereby generating a stress such as thermal stress caused by a temperature difference at a part where the object 1 is cut along the line 5 along which the object is intended to be cut (S 1223 ). Here, since the absorbable laser has such an intensity that the object 1 is heated but not melted thereby, the surface of the object does not melt.
[0540] FIG. 105 is a sectional view of the object 1 including the crack region 9 during laser processing in the stress step. As depicted, upon irradiation with absorbable laser light, the crack further grows while using the crack region 9 as a start point, so as to reach the surface 3 and rear face 21 of the object 1 , thus forming a cut section 10 in the object 1 , whereby the object 1 is cut (S 1225 ). As a consequence, the object 1 is divided into silicon chips.
[0541] Though the twelfth embodiment relates to a case where a crack region is formed as the modified region, the same applies to cases where the above-mentioned molten processed region and refractive index change region are formed as the modified region, whereby a stress can occur upon irradiation with absorbable laser light, so as to generate and grow a crack while using the molten processed region and refractive index change region as a start point and thereby cut the object.
[0542] Even when the crack grown by the stress step while using the modified region as a start point fails to reach the surface and rear face of the object in the case where the object has a large thickness or the like, the object can be broken and cut by applying an artificial force such as a bending stress or shearing stress thereto. This artificial force can be kept smaller, whereby unnecessary fractures deviating from the line to be cut can be prevented from occurring in the surface of the object.
[0543] Effects of the twelfth embodiment will now be explained. In the modified region forming step of this embodiment, the line 5 along which the object is intended to be cut is irradiated with pulse laser light L while locating the light-converging point P within the object to be processed 1 under a condition causing multiphoton absorption. Also the X-axis stage 109 and Y-axis stage 111 are moved, so as to shift the light-converging point P along the line 5 along which the object is intended to be cut. This forms a modified region (e.g., crack region, molten processed region, or refractive index change region) within the object 1 along the line 5 along which the object is intended to be cut. When an object to be processed has a start point in a part to be cut, the object can be broken and cut with a relatively small force. In the stress step of this embodiment, the object 1 is irradiated with absorbable laser light along the line 5 along which the object is intended to be cut, so as to generate a stress such as a thermal stress due to a temperature difference. As a consequence, the object 1 can be cut by a relatively small force, e.g., a stress such as a thermal stress due to a temperature difference. Therefore, the object 1 can be cut without generating unnecessary fractures deviating from the line 5 along which the object is intended to be cut in the surface 3 of the object 1 .
[0544] Since the object 1 is irradiated with the pulse laser light L while locating the light-converging point P within the object 1 under a condition causing multiphoton absorption in the modified region forming step, the pulse laser light L is transmitted there through and is hardly absorbed at the surface 3 of the object 1 in this embodiment. In the stress step, the absorbable laser light has such an intensity that the object 1 is heated but not melted thereby. Therefore, the surface 3 does not incur damages such as melt caused by irradiation with laser light.
[0545] As explained in the foregoing, this embodiment can cut the object 1 without generating unnecessary fractures deviating from the line 5 along which the object is intended to be cut or melt in the surface 3 of the object 1 . Therefore, in the case where the object 1 is a semiconductor wafer, for embodiment, semiconductor chips can be cut out from the semiconductor wafer without generating unnecessary fractures deviating from lines along which the object is intended to be cut or melt in the semiconductor chips. The same holds in objects to be processed having a surface formed with electrode patterns, and those having a surface formed with electronic devices such as piezoelectric device wafers and glass substrates formed with display devices such as liquid crystals. Hence, this embodiment can improve the yield of products (e.g., semiconductor chips, piezoelectric device chips, display devices such as liquid crystals) made by cutting objects to be processed.
[0546] Also, in this embodiment, the line 5 along which the object is intended to be cut in the surface 3 of the object 1 does not melt, whereby the width of the line S along which the object is intended to be cut (which is the gap between regions to become semiconductor chips in the case of a semiconductor wafer, for embodiment) can be reduced. This can increase the number of products prepared from a single object to be processed 1 , and improve the productivity of products.
[0547] Since laser light is used for cutting and processing the object 1 , this embodiment enables processing more complicated than that in dicing with a diamond cutter. For embodiment, cutting and processing can be carried out even when line 5 along which the object is intended to be cut have a complex form as shown in FIG. 16 .
[0548] The laser processing method of the twelfth embodiment according to the present invention can cut an object to be processed without generating melt or unnecessary fractures deviating from the line to be cut in the surface of the object. Therefore, the yield and productivity of products (e.g., semiconductor chips, piezoelectric device chips, and display devices such as liquid crystals) manufactured by cutting objects to be processed can be improved.
[0549] Besides, in the above eleventh embodiments, the crack which is grown from the crack region 9 in the stress step reaches the surface 3 and rear face 21 of the object 1 , but the crack which is grown from the crack region 9 in the stress step the laser light L may be grown so as not to reach the surface 3 and rear face 21 of the object.
Thirteenth Embodiment
[0550] The thirteenth embodiment according to the present invention will now be explained. The laser processing method in accordance with the thirteenth embodiment comprises attaching step of adhesively attaching an object to be processed to an adhesive and expansive sheet, a modified region forming step of forming a modified region in the object, and cutting/separation step of cutting the object at the modified region thereof and separating the cut parts of the object so as to make the space there between.
[0551] The above modified region forming step of the thirteenth embodiments may be any one of the first to twelfth embodiments stated above. Further, in the modified region forming step, the object may be cut at the modified region. In this case that the object is cut at the modified region in the modified region forming step, in the separation step, the cut parts of the object are spaced to each other by a predetermined distance by expansion of the adhesive and expansion sheet. Alternatively, when in the modified region forming step, although the modified region is formed in the body as a molten processed region, the object is not cut, in the separation step, the object is cut and the cut parts of the object are separated to each other with a predetermined space therebetween.
[0552] FIG. 106 shows a film expansion apparatus 200 and the apparatus 200 has a ring shape holder 201 and a column like expander 203 . The adhesive and expansive sheet on which the object to be cut is attached is set to the ring shape holder 201 . After setting of the adhesive and expansive sheet 204 on the ring shape holder 201 at peripheral edge of the sheet, the modified region is formed in the object along a line along which the object is intended to be cut. After the formation of the modified region in the object, the column like expander 203 is moved up against the adhesive and expansive sheet 204 so that a part of the sheet is pushed upward as shown in FIG. 107 . The movement of the part of the sheet 204 causes the expansion of the sheet along a lateral direction thereof so that the sheet 204 is expanded as shown in FIG. 107 . As the result of the expansion of the sheet 204 , the parts of the object which is cut in the modified region forming step are separated to each other with a predetermined space therebetween. So, the pick up of the parts of the object from the adhesive and expansive sheet 204 is performed easily and surely.
[0553] When the object is not cut in the modified region formation step, the expansion of the sheet 204 caused by the upward movement of the expander 203 causes the separation of the object into parts of the object in the modified region and thereafter the cut parts of the object are separated to each other with a predetermined space therebetween.
[0554] The laser processing method and apparatus in accordance with the present invention can cut an object to be processed without generating melt or fractures deviating from lines along which the object is intended to be cut on a surface of the object. Therefore, the yield and productivity of products (e.g., semiconductor chips, piezoelectric device chips, and display devices such as liquid crystal) prepared by cutting objects to be processed can be improved.
[0555] The basic Japanese Application No. 2000-278306 filed on Sep. 13, 2000 and No. 2001-278768 filed on Sep. 13, 2001 and PCT Application No. PCT/JP01/07954 filed on Sep. 13, 2001 are hereby incorporated by reference.
[0556] From the invention thus described, it will be obvious that the embodiments of the invention may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended for inclusion within the scope of the following claims. | 4y
|
This disclosure is a continuation of patent application Ser. No. 08/233,939, filed Apr. 28, 1994, now abandoned.
BACKGROUND OF THE INVENTION
The present invention relates to an intelligent battery power system adoptable for a portable computer, which can perform suspend and resume operations based on the installation state of a battery.
In general, portable electronic systems such as notebook computers or pen-based personal computers incorporate battery power, and are convenient to carry but cannot be operated constantly for long periods of time due to the limited supply power, i.e., batteries. Therefore, most such systems are equipped with a countermeasure feature for saving power. For example, a battery-powered system has the function of shutting off the power supply to sections which draw large amounts of current if it is determined that the user is not using the system. Also, most of these systems include switches for selecting the power supply, that is, to receive power from the batteries or from an external power source via an AC adapter, at the user's discretion.
Therefore, if it is determined that the battery has been discharged to a dangerously low state, the user can be warned accordingly. Upon recognizing such a condition, the user should connect the AC adapter to an external power source and operate a power switch so that power can be supplied through the AC adapter. If an external power connection is unavailable, the batteries must be changed, and, in the case of a portable computer, data should be saved on a disk in order to prevent volatile data from being lost at the time of interrupting the power. The performance of such steps is troublesome and inconvenient to the user.
To solve such a problem, U.S. Pat. No. 5,230,074 discloses a power management system in which interrupts are executed in a low battery power state. Here, the power supply for a dynamic random access memory (DRAM) is maintained with a standby battery during main battery replacement. Computer operation is resumed after installing another main battery.
However, in the above patent, if a low battery state is not detected and the main battery becomes detached or is removed for any reason, such as user carelessness, a suspend interrupt is not generated. Therefore, although the DRAM power supply is maintained by the standby battery, since the central processing unit (CPU) power supply is cut off without its information being stored in the DRAM, data is lost.
Moreover, during normal operation, the main battery charges the standby battery which supplies power to the DRAM, thus shortening the life of the main battery. Also, the standby battery can only be charged up to the state of the main battery, which may be low. Therefore, unless the main battery is removed and replaced with sufficient speed, the power supply to the DRAM will stop prematurely due to the unusually short supply of standby power, thereby resulting in data loss.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide an intelligent battery power system which can solve the above problems.
To accomplish the object, there is provided a battery power system having a main battery and a swap battery, the system comprising: battery presence detecting means for detecting the presence of the main battery; and power control means for operating the system in a suspend mode and applying power from the swap battery to the system, when the battery presence detecting means detects that the main battery is absent, and for interrupting the power from the swap battery with power supplied from the main battery to operate the system in a resume mode when the battery presence detecting means detects that the main battery is present.
BRIEF DESCRIPTION OF THE DRAWINGS
The above objects and advantages of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings in which:
FIG. 1 is a block diagram of a conventional battery power system;
FIG. 2 is a flowchart for explaining the operation of the power controller shown in FIG. 1;
FIG. 3 is a block diagram of the battery power system according to a first embodiment of the present invention;
FIGS. 4A and 4B are diagrams showing the structure of the battery presence detector shown in FIG. 3 according to a first embodiment of the present invention;
FIG. 5 is a flowchart for explaining the operation of the power controller shown in FIG. 3;
FIG. 6 is a block diagram of the battery power system according to a second embodiment of the present invention;
FIG. 7 is a flowchart for explaining the operation of the power controller shown in FIG. 6;
FIG. 8 is a block diagram of the battery power system according to a third embodiment of the present invention;
FIG. 9 is a flowchart for explaining the operation of the power controller shown in FIG. 8;
FIG. 10 is a block diagram of the battery power system according to a fourth embodiment of the present invention; and
FIG. 11 is a flowchart for explaining the operation of the power controller shown in FIG. 10.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram of a conventional battery power system. The system includes a battery 101, a battery status detector 102, a power controller 103, a battery status display 104, a power switch 105, a main system 106, an AC adapter 107 and a plug 108.
In FIG. 1, battery status detector 102 compares the voltage output from battery 101 with a predetermined voltage and thereby checks the charged or discharged status of the battery. That is to say, if the voltage output from battery 101 is less than or equal to the predetermined voltage, it is determined that the battery is discharged. Otherwise, it is determined that the battery is charged. Then, the result is applied to power controller 103. Battery status display 104 displays the result detected from battery status detector 102, thus notifying the user of a discharged state of battery 101. Power switch 105 is operated to select the power supplied to main system 106, either from battery 101 or from an external power source via AC adapter 107 which converts alternating current (AC) power into direct current (DC) power. To supply external power to main system 106 through the AC adapter, plug 108 must be connected to an outlet 109.
FIG. 2 is a flowchart for explaining the operation of the power controller shown in FIG. 1.
Referring to FIG. 2, step 201 determines whether battery power or external power has been selected, and the operation proceeds to step 202 if battery 101 is selected and to step 205 if external power is selected. In step 202, the battery power from battery 101 is supplied to main system 106, and in step 205, the external power is supplied to main system 106 via AC adapter 107. If it is determined in step 201 that battery power is selected, step 203 determines the charge status of the battery using the output signal of battery status detector 102. It battery 101 is discharged, the operation proceeds to step 204 where battery status display 104 displays the discharged status. The above steps are continuously carried out as long as power is supplied to power controller 103.
However, with the apparatus connected to an external source, the user may not properly set power switch 105 for external power, so that main system 106 still operates via battery power. Under these conditions, the main system 106 may be shut down without preparation, even though the discharged state of the battery 101 is displayed in step 204, whereby the data of main system 106 is lost.
Although not shown in FIG. 1, there is a conventional system having a standby battery. In such a case, although the power switch is not operated after step 204 is performed, the power is supplied from the standby battery. However, the conventional standby battery has only a small capacity, thereby enabling only about four to five minutes of normal battery use at a few amperes. Therefore, the user should carry out the battery replacement operation quickly and within a couple of minutes.
FIG. 3 is a block diagram of the battery power system according to a first embodiment of the present invention. The battery power system includes a main battery 301, a battery presence detector 302, a power controller 103a, a swap battery 304, a reverse-current blocking diode 305 and a field-effect transistor 306 connected in parallel, a main system 106, and a power status display 303. A first power line 307 connects the main battery 301 to the swap battery 304 through diode 305 and transistor 306. A second power line 308 connects the first power line 307 to the power controller 103a.
In FIG. 3, upon receiving power, main system 106 performs its various functions. In the case of a notebook computer, the main system includes the core logic, a hard disk drive (HDD), a floppy disk drive (FDD) and a liquid crystal panel, the supplied power being controlled by power controller 103a.
The swap battery 304, being internally installed and separate from main battery 301, has a current capacity and output voltage level which are somewhat less than the main battery and is connected to power controller 103a by the parallel connection of reverse-current blocking diode 305 and field-effect transistor 306.
The battery presence detector 302, which detects whether the main battery is installed, can be manufactured variously and one embodiment thereof will be described later with reference to FIGS. 4A and 4B.
The power status display 303 displays the installation status of main battery 301. For example, power status display 303, such as a light-emitting diode, is made to flash whenever main battery 301 is detached, and thereby prompt a user to reinstall the main battery.
The power controller 103a is composed of a power management processor which controls the power supplied to main system 106 and will now be described with reference to FIG. 5.
Referring to FIG. 5, in step 501, a logic signal is received from battery presence detector 302 in order to determine whether main battery 301 is installed. If the main battery 301 is installed, the process proceeds to step 502 whereby power is supplied from the main battery 301. At this time, since the output voltage of the main battery 301 is higher than that of the swap battery 304, the reverse-current blocking diode 305 is reverse-biased (off), so that there is no current output from the swap battery. However, if it is determined in step 501 that main battery 301 is not installed, i.e., the main battery has been removed, the process proceeds to step 503 and reverse-current blocking diode 305 conducts so that power continues to be supplied, but from swap battery 304, and the power status display 303 displays that main battery 301 has been detached. That is, if power controller 103a detects the removal of the main battery, field-effect transistor 306 is turned on to provide a continuous supply of power through the field-effect transistor 306. Then, if power controller 103a is equipped with a suspend mode function, step 504 switches the power supply mode to the suspend mode because the capacity of swap battery 304 is generally less than that of main battery 301. By switching to the suspend mode, the time during which power can be supplied from swap battery 304 becomes longer, so that a sufficient amount of time is secured for the user to exchange the main battery 301.
The power supply mode of the power controller is a predetermined mode in which only the necessary power is applied, depending on a detected status of system usage, thereby curbing the consumption of electricity. Such a feature is commonplace for any system whose power is supplied through batteries. Table 1 shows various power supply modes which may be adopted in a notebook computer system.
TABLE 1______________________________________mode Power Supply Status______________________________________"ON" power supplied to all units normally"DOZE" CPU clock frequency lowered"SLEEP" CPU clock frequency lowered, liquid crystal panel turns off, and HDD motor stopped"SUSPEND" CPU, HDD, FDD, liquid crystal panel, etc. turned off, and DRAM, VRAM, etc. kept on______________________________________
This is only one example and various modes can be provided by the manufacturer. Here, the particular functions which are turned on or off are set according to the respective modes, but the suspend mode is generally provided by all manufacturers. In the suspend mode, all power is shut off except for that which is required for the continuation of system operations. For example, the processed data is placed in a predetermined area of DRAM where it is stored during the suspend mode. (A discussion of system suspend and resume operations can be found in U.S. Pat. No. 5,021,983.)
Referring again to FIG. 5, step 505 determines whether the user has reinstalled main battery 301, and if so, operation proceeds to step 506 where the power supply is switched so that power is again supplied from main battery 301. Then, step 507 performs a resume operation which restores the system to the original mode, that is, the mode prior to step 504. Here, the data stored in the predetermined DRAM memory area is reloaded in the operation areas. The steps of FIG. 5 are performed as long as the power is supplied.
In other words, power controller 103a of FIG. 3 controls the power to be supplied from main battery 301 whenever battery presence detector 302 detects the proper installation of main battery 301, and controls the power to be supplied from the swap battery 304 if it is detected that the main battery 301 has been detached.
FIGS. 4A and 4B show the structure of battery presence detector 302 according to one embodiment of the present invention, for determining whether main battery 301 is installed. Here, conductive surfaces 402 on the rear side of hooks 401 are supported by springs 403, with the position of each hook 401 depending on the installation state of main battery 301. Thus, with main batteries 301 installed, conductive surfaces 402 are connected to a pair of contact points 403 to complete a circuit and apply a predetermined signal (Vcc) to logical product means 405. The logical product means 405 receives the predetermined signals and performs a logical multiplication operation becoming non-active if either of the main batteries 301 is detached. Reference numerals 406 and 407 denote contact terminals and reference numeral 408 denotes a battery holder. Battery presence detector 302 may also be realized via optical means instead of the above construction.
FIG. 6 is a block diagram of the battery power system according to a second embodiment of the present invention. In addition to the components shown in FIG. 3, the system of FIG. 6 further includes a battery status detector 102. Here, battery status detector 102 compares the voltage output from main battery 301 with a predetermined voltage to check the charged or discharged status thereof and outputs the status signal to a power controller 103b. With such a composition, the power status display 303 can perform the additional function of displaying the charge/discharge status of main battery 301 so that the user can visually confirm the main battery status, thereby facilitating the timely exchange of the main batteries.
FIG. 7 is a flowchart for explaining the operation of power controller 103b of FIG. 6.
Referring to FIG. 7, step 701 determines whether main battery 301 is installed, based on the output of battery presence detector 302. If main battery 301 is installed, the process proceeds to step 702, and if not, power status display 303 displays that main battery 301 is detached and the process proceeds to step 704. In step 702, it is determined whether the installed main battery 301 is charged or discharged, based on the output of battery status detector 102. If main battery 301 is charged, the process proceeds to step 703 where power is supplied from the main battery, but if step 702 determines that main battery 301 is discharged, the power status display 303 indicates the discharged state thereof and the process advances to step 704. Therefore, unless a fully charged main battery is properly installed, step 704 is performed to switch the power supply path so that the power is supplied from swap battery 304. Then, in the event of power controller 103b being equipped with the function of supplying power according to a predetermined mode, i.e., the suspend mode, step 705 is performed to switch the power supply mode as in step 504 of FIG. 5. Thereafter, step 706 determines whether main battery 301 is reinstalled, and if so, the process proceeds to step 707 which checks the charge/discharge condition of the main battery. If it is determined in step 707 that the installed main battery 301 is charged, the process proceeds to step 708 which switches the power supply to the main battery. Thereafter, the process proceeds to step 709 in which a resume operation as described with respect to step 507 of FIG. 5 is performed. The above steps are performed as long as power is supplied to power controller 103b.
That is, power controller 103b functions such that when main battery 301 is installed and charged, the system power is supplied from the main battery. Otherwise, the power is supplied from swap battery 304.
FIG. 8 is a block diagram of the battery power system according to a third embodiment of the present invention. In addition to the components shown in FIG. 3, the system of FIG. 8 further includes an AC adapter 107 with a power plug and a power switch 105. The AC adapter 107 having a plug 108 is connected with an outlet 109 as an external power source. Here, power switch 105 is connected to a power controller 103c and allows the user to select the power supply source. For example, in the case of state "A" of power switch 105, external power is supplied through AC adapter 107, and in the case of state "B," power is supplied from either main battery 301 or swap battery 304. With such a configuration, swap battery 304 is automatically converted to a charge mode and charged when external power is supplied and the swap battery itself is not used.
The operation of power controller 103c having the above configuration will be described with reference to FIG. 9.
In FIG. 9, step 901 determines whether the battery or the external power source is selected. If power switch 105 is switched to the battery (state "B"), the process proceeds to step 902, but if the power switch 105 is switched to the external power source (state "A"), the process proceeds to step 907 and external power is supplied to the system. Meanwhile, when the battery is selected, step 902 determines whether main battery 301 is installed, based on the output of battery presence detector 302. If main battery 301 is installed, the process proceeds to step 903 and power is supplied from the main battery 301. Otherwise, after power status display 303 displays that main battery 301 is detached, the process proceeds to step 904 where it is again determined whether power switch 105 is switched to state "B" or to state "A." If external power is selected, the process proceeds to step 907 in which the external power is applied. On the contrary, if the battery is selected (state "B"), step 905 supplies power from swap battery 304 and the suspend mode is set in step 906. Then, in step 908, it is again determined whether power switch 105 is switched to the battery (state "B") or the external power source (state "A"). If external power is selected, the process proceeds to step 910 and external power is supplied, and then the process proceeds to step 912. Otherwise, the process advances to step 909 which determines whether main battery 301 is installed. If it is determined in step 909 that main battery 301 is installed, the process proceeds to step 911 in which power is supplied from main battery 301 and thereafter proceeds to step 912. Otherwise, the process returns to step 908. Step 912 is performed when the power is first supplied from the swap battery and then from the external power or main battery 301 and thereafter the resume operation is performed. The above steps are performed as long as power is supplied to power controller 103c.
In the operation of power controller 103c, power is supplied through AC adapter 107 when power switch 105 is set for external power. However, if power switch 105 is switched to the battery, the power is supplied from main battery 301 only if the output of battery presence detector 302 indicates that the main battery is installed. Otherwise, the power is supplied from swap battery 304. Also, the suspend mode is operated when the power is supplied from swap battery 304, and the resume operation is performed when the power supply changes back from swap battery 304.
FIG. 10 is a block diagram of the battery power system according to a fourth embodiment of the present invention. In addition to the components shown in FIG. 8, the system of FIG. 10 further includes a battery status detector 102. Here, battery status detector 102 detects the charge/discharge status of main battery 301, as described with respect to FIG. 6, and supplies the status signal to a power controller 103d. Also, in such a configuration, if external power is supplied and the swap battery 304 itself is not used, similar to the case of FIG. 8, the swap battery is automatically converted into a charge mode and charged.
The operation of power controller 103d will be described with reference to FIG. 11.
Referring to FIG. 11, step 1101 determines which power source is selected by power switch 105. If power switch 105 is set for battery operation (state "B"), the process proceeds to step 1102. If power switch 105 is set for external power operation (state "A"), the process proceeds to step 1114 and external power is supplied. Meanwhile, if power switch 105 selects the battery, step 1102 determines whether main battery 301 is installed based on the output of battery presence detector 302. Thus, if main battery 301 is installed, the process proceeds to step 1103 which determines whether the installed main battery 301 is charged or discharged based on the output of battery status detector 102. On the other hand, if main battery 301 is detached, power status display 303 displays this information and the process proceeds to step 1104. If it is determined in step 1103 that main battery 301 is discharged, battery status detector 102 displays this information and the process proceeds to step 1114. If it is determined that main battery 301 is charged, the process proceeds to step 1113 and the power is supplied from the main battery. In step 1104, it is again determined whether power switch 105 is set to state "B" or state "A." If external power is selected (state "A"), the process proceeds to step 1114 and external power is supplied. On the contrary, if the battery is selected (state "B"), the power is supplied from swap battery 304 in step 1105 and then the suspend mode function is performed in step 1106. In step 1107, the state of power switch 105 is again determined. If external power is selected, the process proceeds to step 1111 and external power is supplied, and then the process proceeds to step 1112. Otherwise, the process proceeds to step 1108 which determines whether main battery 301 is installed. If it is determined in step 1108 that main battery 301 is installed, the process proceeds to step 1109 to then determine whether the installed main battery 301 is charged or discharged. Here, if it is determined that main battery 301 is not installed or that an installed main battery is not charged, the process returns to step 1107, but if the installed main battery 301 is charged, the process proceeds to step 1110 and power is supplied from main battery 301. Step 1112 is performed when the power is first supplied from the swap battery and then from the external power or main battery 301 and thereafter the resume operation is performed. The above steps are performed as long as the power is supplied to power controller 103d.
As described above, the intelligent battery power system according to the present invention can maintain data by means of a swap battery by performing a suspend operation, even when the main battery is removed, and can lengthen the life of the swap battery. | 4y
|
This is a division of application Ser. No. 07/357,791 filed May 30, 1989, now abandoned.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a gas-impermeable resinous composition and particularly to such composition used for forming members or parts which are required to have an excellent flexibility and heat resistance together with a high gas impermeability.
2. Discussion of the Prior Art
Conventionally resin such as nylon 6 has been used for forming members or parts which are required to have high gas impermeability. However, the nylon 6 and other gas-impermeable resins are comparatively rigid, and therefore such materials are not suitable for forming members which are additionally required to have high flexibility.
Referring to FIG. 5 there is shown a conventional refrigerant-transporting hose used as piping of car coolers, air conditioners and the like of automotive vehicles. The hose has a three-laminated or -layered structure consisting of an inner and an outer rubber tube 101, 103 and a reinforcing fiber layer 102 interposed between the inner and outer tubes 101, 103. The rubber hose has a high flexibility and therefore is handled with ease, for example in providing a refrigerant-using device with piping. On the other hand, rubber materials have a comparatively high gas permeability, that is, a comparatively low gas impermeability. Thus, the rubber hose suffers from the problem of progressive leakage of the refrigerant gas conveyed therethrough. Accordingly, it is necessary to often charge the refrigerant-using device with the refrigerant for compensating for lost fractions to maintain an optimum cooling capacity of the device. It goes without saying that is very troublesome.
There is a tendency that refrigerant discharged from the compressor of a cooling system for an automotive engine has raised temperature, which tendency results from raised speed of rotation of the engine. There is also a tendency that ambient air around an engine has increased temperature, which tendency results from small-sized engine room. Thus, it is necessary that refrigerant transporting hoses have excellent heat resistance. However, the above-mentioned conventional rubber hose has the problem that cracks are likely to be produced in the inner rubber tube if the hose is used at raised temperatures for a long period of time. That is, the hose does not have a reliable quality. In the case where hoses are formed of rubber material with high heat resistance, then such rubber material has an unsatisfactory gas impermeability, resulting in hoses produced with a low gas impermeability when compared with the above-mentioned conventional hose.
In the background described above, it has been proposed to form the inner tube of a hose of a resin which is excellent in both gas impermeability and heat resistance, in place of or in combination with rubber. However, in the case where nylon 6 is used as the resin, the material has a very high rigidity, and when used for producing hoses the material extremely lowers the flexibility of the hoses produced. Thus, nylon 6 is not suitable for practical use. In the case where a resin with a lower rigidity, such as nylon 6-66 copolymer and nylon 6-12 copolymer, is used to improve the flexibility of hoses, such resins have a melting point considerably lower than nylon 6 and do not satisfy the requirement of sufficient heat resistance.
The conventional gas-impermeable resins are unsatisfactory with regard to flexibility, and the resins with increased flexibility suffer from low heat resistance. Thus, none of the conventional resins have been suitable as material for forming members, such as refrigerant-transporting hoses, packings or the like, which are required to have high flexibility and heat resistance together with high gas impermeability.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a transverse cross sectional view of a refrigerant transporting hose including a resinous layer formed of the gas-impermeable resinous composition embodying the present invention;
FIGS. 2 through 4 are transverse cross sectional views of other hoses including resinous layers formed of the resinous composition according to the invention; and
FIG. 5 is a transverse cross sectional view of a conventional hose.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a gas-impermeable resinous composition used for forming a member or part thereof which has excellent gas impermeability, heat resistance and flexibility.
The Inventors have searched for a resinous material which is satisfactory with regard to gas impermeability, heat resistance and flexibility, by testing various resins, and have found that common polyamide resins such as nylon 6 and nylon 6-66 copolymer are not suitable and that a specific polyamide resin produced by condensation polymerization of hexamethylene diamine and an aliphatic dicarboxylic acid whose molecule has 8 to 16 carbon atoms (hereinafter, referred to as "CPA resin"), is suitable for that purpose. That is, the CPA resin is satisfactory with regard to the three requirements, i.e. high gas impermeability, flexibility and heat resistance. Based on these findings the present invention has been developed.
According to the present invention, there is provided a gas-impermeable resinous composition comprising a major component thereof a polyamide resin produced by the reaction of hexamethylene diamine and an aliphatic dicarboxylic acid whose molecule has from eight to sixteen carbon atoms.
The gas-impermeable resinous composition according to the invention is used as a material for forming members or parts thereof which are satisfactory with regard to gas impermeability, flexibility and heat resistance. Consequently the instant composition is very suitable for forming refrigerant-transporting hoses, packings and the like of car coolers, air conditioners and other refrigerant-using devices which are required to have excellent heat resistance, seal characteristics and gas impermeability for a long period of service. Further, the composition is advantageously used for producing containers for containing therein food, medicine or the like, packaging materials, and wrapping films.
As mentioned above, the CPA resin contained in the resinous composition of the invention is produced by condensation polymerization of hexamethylene diamine and an aliphatic dicarboxylic acid.
It is essential that the aliphatic dicarboxylic acid used for producing the CPA resin, have eight to sixteen carbon atoms. The dicarboxylic acid is expressed by the following formula:
HOOC--R--COOH
where R is an aliphatic residue having carbon atoms ranging from six to fourteen. In the case where the number of carbon atoms of the aliphatic residue R is less than six, an article formed of the composition containing the CPA resin produced by using such aliphatic dicarboxylic acid, is extremely rigid, that is, unsatisfactory with regard to flexibility. For example, if a refrigerant-transporting hose is formed of the composition, the hose produced suffers from low flexibility. On the other hand, in the case where the number is more than fourteen, the produced article, for example hose has a low melting point and suffers from low gas impermeability.
As the aliphatic dicarboxylic acid having 8 to 16 carbon atoms, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, tridecanedicarboxylic acid, tetradecanedicarboxylic acid, pentadecanedicarboxylic acid, and hexadecanedicarboxylic acid are preferably used. In particular, sebacic acid and dodecanedicarboxylic acid are suitable. These acids may be used solely or in combination. In other words, the hexamethylene diamine is reacted with at least one of the acids to obtain the CPA resin.
The gas-impermeable resinous composition may consist of the CPA resin. In this case, the resinous composition contains 100% of the CPA resin.
Where the gas-impermeable resinous composition further contains saponified ethylene-vinyl acetate copolymer in addition to the CPA resin, the resinous composition exhibits more effective characteristics. The saponified ethylene-vinyl acetate copolymer has a heat resistance comparable to the CPA resin and an excellent gas impermeability.
It is recommended that the saponified ethylene-vinyl acetate copolymer contain not more than 40 mol % of ethylene and not less than 90 mol % of the vinyl acetate of the ethylene-vinyl acetate copolymer be saponified. If the proportion of the ethylene exceeds 40 mol %, or if the degree of saponification of the vinyl acetate is below 90 mol %, the heat resistance of the product formed of the resinous composition tends to be lowered to an insufficient level.
It is preferred that the gas-impermeable resinous composition contain not more than 250 parts by weight of the saponified ethylene-vinyl acetate copolymer per 100 parts by weight of the CPA resin. If the proportion of the copolymer exceeds 250 parts by weight, the flexibility of the product is insufficiently low, though the gas impermeability thereof is increased.
The gas-impermeable resinous composition of the invention may be prepared by a known resin-composition preparing method by using the above-described material(s). For example, in the case of the gas-impermeable resinous composition consisting of the mixture of CPA resin and saponified ethylene-vinyl acetate copolymer, pellets of the two substances are subjected to dry blend and subsequently kneaded by a twin-screw extruder.
In addition to the above-indicated component(s), the resinous composition according to the invention may further contain, if necessary, halogen-containing rubber such as chlorosulfonated polyethylene rubber (CSM), chlorinated polyethylene (CPE), epichlorohydrin rubber (CHC, CHR) and chlorinated isobutylene-isoprene rubber (Cl-IIR), and/or rubber such as ethylene propylene diene rubber (EPDM) and acrylonitrile-butadiene rubber (NBR). In this case, it is preferred that the resinous composition contain not more than 70 parts by weight of the additional rubber per 100 parts by weight of the CPA resin. If the proportion of the rubber exceeds 70 parts by weight, the gas impermeability of the product is insufficient.
The gas-impermeable resinous composition is used for providing, for example, an inner tube of a refrigerant-transporting hose as shown in FIG. 1. The hose consists of a resinous layer 11 through which refrigerant is transported, an outer rubber layer 12 located radially outwardly of the resinous layer 11, an outer rubber tube 14 located radially outwardly of the outer rubber layer 12, and a reinforcing fiber layer 13 interposed between the outer rubber layer 12 and the outer rubber tube 14 such that the intermediate fiber layer 13 and the other layers and tube 11, 12, 14 constitute an integral tubular body. The resinous layer 11 is formed of a resinous composition which contains as a major component thereof the CPA resin or the mixture of CPA resin and saponified ethylene-vinyl acetate copolymer, each previously described. Reference numerals 15 designate spiking holes formed through the outer rubber tube 14 from an exposed, outer surface of the outer tube 14 to the fiber layer 13. The spiking holes 15 serve to prevent the refrigerant gas from being trapped between the four laminates 11, 12, 13, 14, by relieving the gas into outside space.
Referring next to FIGS. 2 to 4 there are shown other refrigerant-transporting hoses. The hoses of FIGS. 2-4 are different from the hose of FIG. 1 with respect to the inner tube consisting of the resinous layer 11 and the outer rubber layer 12. In FIG. 2 there is shown the hose whose inner tube consists of a single resinous layer 11 formed of the resinous composition containing as major components thereof at least one of polyester polyamide resin and polyetherester polyamide resin, and saponified ethylene-vinyl acetate copolymer. In FIG. 3 there is shown the hose whose inner tube consists of a three-layered structure which includes an innermost rubber layer 10 and an outer rubber layer 12 between which is interposed a resinous layer 11 formed of the same resinous composition as that of the resinous layer 11 of the hose of FIG. 2. In FIG. 4 there is shown the hose whose inner tube consists of a resinous layer 11 and an innermost rubber layer 10 positioned radially inwardly of the resinous layer 11, in contrast to the inner tube (11, 12) of the hose of FIG. 1.
Each of the refrigerant-transporting hoses of FIGS. 1-4 are excellent in flexibility, heat resistance and gas impermeability due to the high flexibility, heat resistance and gas impermeability of the resinous layer 11 of the inner tube thereof, which layer is formed of the specific resinous composition according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to TABLE I there are shown seven gas-impermeable resinous compositions (Examples A through G) according to the present invention. Each of the compositions were prepared by the previously-described known method by using the material(s) indicated in the table. The table also shows the proportion of each material used in the compositions.
TABLE I______________________________________ INVENTION RESINOUS COMPOSITIONS A B C D E F G______________________________________POLYAMIDE 100 -- -- -- -- -- 71RESIN 1 *1POLYAMIDE -- 100 100 100 100 100 29RESIN 2 *2ETHYLENE- -- -- 40 200 -- -- --VINYL ACETATECOPOLYMER 1 *3ETHYLENE- -- -- -- -- 40 -- --VINYL ACETATECOPOLYMER 2 *4CHR -- -- -- -- -- 40 40______________________________________ *1: Condensated copolymer of hexamethylene diamine and sebacic acid *2: Condensated copolymer of hexamethylene diamine and dodecanedicarboxylic acid *3: The proportion of the ethylene is 32 mol %; the degree of saponification of the vinyl acetate is 95 mol % *4: The proportion of the ethylene is 38 mol %; the degree of saponification of the vinyl acetate is 90 mol %
Hoses having a structure similar to that of the hose of FIG. 1, were prepared by using the resinous compositions A through G by the following manufacturing method, except for the case of the hoses whose inner tube consists of a three-layered structure, in which at the beginning unvulcanized rubber composition was extruded from an extruder on the rubber mandrel to form a tubular body, i.e. inner rubber layer of the inner tube:
Initially, a resinous composition (i.e., each of Examples A-G) is molten by heat, and the heat-molten resin is extruded from a resin extruder on a rubber mandrel so as to provide a resinous layer 11 thereon, and then the resinous layer is cooled.
Second, adhesive is applied to an outer surface of the resinous layer 11, and unvulcanized rubber composition for the outer rubber layer 12 is extruded thereon from an extruder so as to provide a double-layered inner tube.
Subsequently, adhesive is applied to an outer surface of the inner tube, and a reinforcing fiber layer 13 is formed thereon by braiding, spiralling or knitting with a suitable thread.
Next, adhesive is applied to an outer surface of the reinforcing fiber layer 13, and unvulcanized rubber composition is extruded from an extruder thereon so as to provide an outer rubber tube 14.
Last, the thus-obtained laminated tube is vulcanized to produce an integrally bonded end product, i.e., hose, and then the rubber mandrel is removed from the hose. The vulcanizing temperature is selected at 145° to 170° C., and the vulcanizing time is selected at 30 to 90 minutes.
The material and thickness of each of the laminates of the hoses produced are indicated in an upper portion of TABLE II. Hoses 1 through 8 include resinous layers formed of the resinous compositions A-G. Meanwhile, the first comparative hose (Hose 9) has an inner tube consisting of a single layer formed of NBR. The second comparative hose (Hose 10) has a resinous layer formed of nylon 6, while the third comparative hose (Hose 11) has a resinous layer formed of nylon 6-66 copolymer.
Each of Hoses 1 through 11 was tested with regard to flexibility, gas impermeability and heat resistance. The test results are shown in a lower portion of TABLE II.
The flexibility, gas impermeability and heat resistance were evaluated as follows:
Flexibility
Each of the eleven hoses was cut into a 300 and a 400 mm long specimen, and one of opposite ends of each cut hose was fixed to a plate and the other end thereof was progressively bent to contact the plate. With the other end contacting the plate, the bending stress exerted to the other end was measured. The flexibility of the hoses was evaluated by measurements of the bending stress. Smaller measurement values indicate higher degrees of flexibility.
Gas Impermeability
Each of the eleven hoses was cut into a 500 mm long specimen, and the hose was charged with 40 g of Flon 12 and gas-tightly sealed at opposite ends thereof. The gas-charged hose was maintained at 100° C. for 72 hours. Subsequently the overall weight of the specimen was measured, and was compared with its initial weight immediately after the charging of the Flon gas. The reduced amount (g) of the Flon gas, which had permeated through the wall of the hose into ambient atmosphere, was calculated. Smaller values indicate higher degrees of gas impermeability.
Heat Resistance
Each of the eleven hoses was cut into a 400 mm long specimen, and was placed in an oven at 140° C. for 168 hours. Subsequently the cut hose was wound around a mandrel with a radius of 50 mm, and was inspected for any cracks produced in the inner tube thereof.
TABLE II__________________________________________________________________________ HOSES INCLUDING RESINOUS LAYERS COMPARATIVE FORMED OF INVENTION COMPOSITIONS HOSES 1 2 3 4 5 6 7 8 9 10 11__________________________________________________________________________STRUCTURE OF HOSEINNER TUBEINNER MATERIAL -- -- -- -- NBR CSM -- -- NBR NBR NBRRUBBER THICKNESS -- -- -- -- 0.5 0.5 -- -- 3.4 0.5 0.5LAYER (mm)RESIN- MATERIAL A B C D E B F G -- Ny6 Ny6-66OUS *1 *2LAYER THICKNESS 0.2 0.2 0.15 0.15 0.15 0.15 0.25 0.25 -- 0.15 0.15 (mm)OUTER MATERIAL NBR NBR NBR NBR NBR CSM NBR NBR -- NBR NBRRUBBER THICKNESS 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 -- 1.0 1.0LAYER (mm)REINFORCING MATERIAL PeF PeF PeF PeF PeF PeF PeF PeF PeF PeF PeFFIBER LAYER *3OUTER MATERIAL EPDM EPDM EPDM EPDM EPDM EPDM EPDM EPDM EPDM EPDM EPDMRUBBER THICKNESS 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4 1.4TUBE (mm)EVALUATIONFLEXIBILITY LENGTH OF 1.4 1.4 1.3 1.4 1.3 1.4 1.3 1.3 1.3 2.0 1.4(kgf) HOSES: 300 mm LENGTH OF 0.7 0.8 0.8 0.8 0.8 0.9 0.8 0.8 0.6 1.0 0.8 HOSES: 400 mmGAS IMPERMEABILITY 7 7 5 5 5 7 10 9 28 1 6(g/m/72 hours)HEAT RESISTANCE N N N N N N N N P N P *4 *5__________________________________________________________________________ *1: Nylon 6 *2: Nylon 666 copolymer *3: Polyester fiber *4: No crack was observed. *5: Cracks were observed.
As is apparent from the test results shown in TABLE II, all of the hoses (Hoses 1 through 8) including a resinous layer formed of the composition A through G, exhibit excellent characteristics all with regard to flexibility, gas impermeability and heat resistance. In contrast thereto, the first comparative hose (Hose 9) whose inner tube consists of a single NBR layer, suffers from the problem of permitting a large amount of refrigerant gas to permeate therethrough. Therefore, Hose 9 is not suitable for practical use. The second comparative hose (Hose 10) whose inner tube includes a resin layer formed of nylon 6, has an excellent gas impermeability but is unsatisfactory with regard to flexibility. The third comparative hose (Hose 11) whose inner tube includes a resin layer formed of nylon 6-66 copolymer, is satisfactory with regard to flexibility and gas impermeability but suffers from low heat resistance.
While the present invention has been described in its presently preferred embodiments with a certain degree of particularity, it is to be understood that the invention is not limited to the precise details of the illustrated embodiments, but may be embodied with various changes, modifications and improvements which may occur to those skilled in the art without departing from the spirit and scope of the invention defined in the following claims. | 4y
|
TECHNICAL FIELD
This invention concerns computers, particularly the file management aspects of computer operating systems.
BACKGROUND OF THE INVENTION
Personal computers allow users to do an almost unlimited number of tasks. Examples of typical tasks include drafting term papers, resumes, and letters, organizing recipes and addresses, tracking personal checking accounts and stock portfolios, communicating via electronic mail with other computer users, generating blueprints for home improvements, and even making electronic photo albums. To accomplish these and other tasks, the typical computer system includes application programs—specific sets of instructions—that work with other components of the computer system to provide specific functions, such as word processing. Application programs are often called software to distinguish from the physical equipment, or hardware, of the computer system.
More particularly, the typical computer includes a central processing unit, a memory, a set of user-interface devices, and a display. The processing unit generally performs the computations and other data manipulations for performing, or executing, the instructions of application programs. The memory, which may take a variety forms such as a memory chip or a floppy disk, stores the application programs as well as data generated using the programs. User-interface devices, such as the keyboard and mouse, allow the user to input information into the application programs. For example, a user may input words or commands into the application program by typing on a keyboard, or select options from menus using a mouse or other pointing device. The display, sometimes called a monitor, not only provides a visible representation of application program operations, but also cooperates with the keyboard and mouse to provide a graphical user interface for intuitively interacting with and controlling application programs.
The typical computer system also includes an operating system—a special kind of software that coordinates or facilitates execution of application programs. Application programs logically combine functions or services of the operating system with those of the central processor to achieve more complex functions, such as word processing. Examples of typical operating-system functions include transferring data between the central processing unit and the memory, initial processing of inputs from the keyboard and mouse, managing the storage and retrieval of files in memory, and displaying graphical-user-interface menus and dialog windows. Operating-system functions relating to file storage and retrieval are generally said to constitute a file, or document, management system. In one sense, the file management system is the heart of the computer system, since a great majority of the tasks that users use computers for involve creating, storing, and retrieving documents of various types from memory. (The terms file and document are used interchangeably throughout this patent to broadly encompass any form of electronically stored information.)
The file management system usually organizes the memory of the computer system as a file cabinet comprising a number of folders, with each folder comprising one or more documents. Each application program typically has its own folder which stores the application program itself and the documents created using the application program. The file management system includes features which allow users to define their own folders and to logically group documents according to subject matter, date-of-creation, indeed any criteria they choose. However, because using these features requires extra effort and attention, a great many users allow the application programs to store their documents in the folders containing the applications used to create them. For example, many users allow the word processing application to store their documents in the word processing folder, the photograph-editing application to store its documents in the photo-editing folder, and so forth.
This approach of allowing separate application programs to store documents in their own folders ultimately scatters the users documents across numerous folders. Many of these folders have abbreviated and hard-to-remember names which at times make it difficult for users, who forget which application programs were used to create which documents, to find specific documents without considerable frustration and effort.
One partial solution to this problem entailed programming a family of four application programs, to store, or save, their documents to a common folder, unless users specified otherwise. In other words, the suite of four application programs were programmed to use a common default folder, instead of the four different folders containing the application programs. A commercial example of this approach is the Office 95 (tm) family of business software from Microsoft Corporation of Redmond, Wash. This software family included application programs for word processing, spread sheeting, desktop publishing, and information management, all of which were programmed to save documents by default, that is, unless otherwise instructed, to a folder named My Documents.
However, this approach to default document storage applied only to application programs in the software family, not to the many other application programs that a typical computer system includes. Moreover, it did nothing to provide users with more convenient, straightforward access to the default folder, which can be difficult to find among a large number of folders. Accordingly, there is a need not only for a more general approach to default document storage, but also for more convenient ways of accessing the default folder.
SUMMARY OF THE INVENTION
To address these and other problems, the inventors devised an operating system which, rather than relying on application programs to set a common folder for default document storage, provides a common default folder to all application programs using the operating system. Moreover, for convenient access to the common default folder, some forms of the operating system include a graphical user interface which provides one-button access to the default folder at the highest level of the interface, eliminating the need for users to search through a hierarchical list of folders for the default folder. Additionally, other versions of the operating system includes a service that not only provide a list of most-recently-used documents but also one-button access to the common default folder. And still other versions of the operating system include a document sending feature that allows users to send any document, for example, an electronic mail message, to the default folder, and a document finding feature that allows users to focus computerized, document-searching efforts on the default document directory to save time.
The present invention encompasses systems, operating systems, computers, methods, and computer-readable media of varying scope. In addition to the aspects and advantages of the present invention described in this summary, further aspects and advantages of the invention will become apparent in view of the drawings and detailed description that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a block diagram of an exemplary computer system 10 embodying the invention;
FIG. 1B is a partial block diagram of operating system 35 in computer system 10 ;
FIG. 2A is a flowchart illustrating an exemplary method of the present invention, in which operating system 35 of system 20 defines a folder named My Documents folder as the common default folder for application programs 36 in system 10 ;
FIG. 2B is a flowchart illustrating an exemplary algorithm used with the method of FIG. 2A;
FIG. 3A is an illustration of a file menu displayed during execution of the FIG. 2A method;
FIG. 3B is an illustration of a file-open dialog window displayed during execution of the FIG. 2A method;
FIG. 3C is an illustration of a file-save dialog window displayed during execution of the FIG. 2A method;
FIG. 4A is an illustration of a desktop in a graphical user interface of operating system 35 , including a link to the default file-storage container named My Document;
FIG. 4B is an illustration of file-open dialog window including a link to the desktop of the graphical user interface;
FIG. 4C is an illustration of a dialog window for a file find service of operating system 35 , presenting several search options including to search for files or folders;
FIG. 4D is an illustration of a file menu in the graphical user interface, including a list of most-recently-used files and a link to the default file-storage container My Documents; and
FIG. 4E is an illustration of a file menu with a file send function and an associated submenu with a link to the My Documents default file-storage container.
DETAILED DESCRIPTION OF THE INVENTION
The following detailed description, which references and incorporates FIGS. 1A-4E, describes and illustrates one or more exemplary embodiments of the invention. These embodiments, offered not to limit but only to exemplify and teach the invention, are shown and described in sufficient detail to enable those skilled in the art to practice the invention. Thus, where appropriate to avoid obscuring the invention, the description may omit certain information known to those of skill in the art.
Overview
In the context of a computer system, the invention concerns document-management interactions among an operating system, one or more application programs, and a user-interface which allows users to view and enter data into the computer system. More particularly, the operating system takes advantage of normal interactions with application programs during access to basic file open and file save functions to present a common default storage folder called My Documents to the application programs. In addition, the operating system promotes further use of the My Documents folder at other file-access points in its graphical user interface. Another set of inventive features relate to using the My Documents folder in a network environment to facilitate the sharing of documents between users of different computer system.
Exemplary Computer System Embodying the Invention
FIG. 1A shows an exemplary computer system 10 which embodies the invention. The following description of system 10 is intended to provide a brief, general description of suitable computer hardware and a suitable computing environment in which the invention can be implemented. Although not required, the invention is described in the general context of computer-executable instructions, such as program modules, being executed by a computer, such as a personal computer. Generally, program modules include routines, programs, objects, components, data structures, and so forth, that perform particular tasks or implement particular abstract data types.
Moreover, those skilled in the art will appreciate that the invention may be practiced with other computer system configurations, including hand-held devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, network PCS, minicomputers, mainframe computers, and the like. The invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.
More particularly, computer system 10 includes a general purpose computing device in the form of a computer 20 , including a processing unit 21 , a system memory 22 , and a system bus 23 that operatively couples various system components including the system memory to processing unit 21 . There may be only one or there may be more than one processing unit 21 , such that the processor of computer 20 comprises a single central-processing unit (CPU), or a plurality of processing units, commonly referred to as a parallel processing environment. Computer 20 may be a conventional computer, a distributed computer, or any other type of computer. Thus, the invention is not limited to a particular computer.
System bus 23 may be any of several types of bus structures including a memory bus or memory controller, a peripheral bus, and a local bus using any of a variety of bus architectures. The system memory, which may also be referred to as simply the memory, includes a read only memory (ROM) 24 ,and a random access memory (RAM) 25 . ROM 24 stores a basic input/output system (BIOS) 26 containing the basic routines that help to transfer information between elements within the computer 20 , such as during start-up. Computer 20 further includes a hard disk drive 27 for reading from and writing to a hard disk, not shown, a magnetic disk drive 28 for reading from or writing to a removable magnetic disk 29 , and an optical disk drive 30 for reading from or writing to a removable optical disk 31 such as a CD ROM or other optical media.
Hard disk drive 27 , magnetic disk drive 28 , and optical disk drive 30 are connected to system bus 23 by a hard disk drive interface 32 , a magnetic disk drive interface 33 , and an optical disk drive interface 34 , respectively. The drives and their associated computer-readable media provide nonvolatile storage of computer-readable instructions, data structures, program modules and other data for computer 20 . It should be appreciated by those skilled in the art that any type of computer-readable media which can store data accessible by a computer, such as magnetic cassettes, flash memory cards, digital video disks, Bernoulli cartridges, random access memories (RAMs), read only memories (ROMs), and the like, may be used in the exemplary operating environment.
A number of program modules may be stored on the hard disk, magnetic disk 29 , optical disk 31 , ROM 24 , or RAM 25 , including an operating system 35 , one or more application programs 36 , other program modules 37 , and program data 38 . Operating system 35 provides numerous basic functions and services to application programs 36 stored by system memory 22 , hard-disk drive 27 , and/or hard-disk drive 50 . The invention, however, is not limited to a particular operating-system type or architecture. Indeed, the invention can be incorporated in any number of existing operating systems, such as the Microsoft Windows 95 operating system, the Microsoft Windows NT 4.0 operating system, the IBM OS/2 operating system, and the Apple Computer MacOS operating system.
FIG. 1B, a partial block diagram, shows that exemplary operating system 35 includes three modules 35 a , 35 b , and 35 c which perform the primary functions of the invention, that is to define and promote a common default storage container for application programs 36 . The embodiment of FIG. 1B specifically contemplates versions of the Microsoft Windows operating system, such as Windows 95, Windows 98, and Windows NT operating systems. Module 35 a provides shell, or interface, functions between the application programs and various portions of operating system 35 . Module 35 a is a standard part of versions of the Microsoft Windows operating system, according to one embodiment of the invention, and embodiments of the invention utilizing this module modify the module to provide functionality that is described in later sections of the detailed description. Module 35 b includes most of the program instructions related specifically to promoting the My Documents folder as a default document storage container. And, module 35 c defines and controls common dialog windows, such as the file-open and file-save dialog windows typically accessed by application programs. Module 35 c is also a standard part of versions of the Microsoft Windows operating system, according to one embodiment of the invention, and embodiments of the invention utilizing this module also modify the module to provide functionality that is described in later sections of the detailed description. However, the invention is not limited to any particular division of functions.
Additionally, the invention is not limited any particular set or number of application programs 36 . Examples of some applications the invention can be used with include the Microsoft Word word processing software, Microsoft Excel spreadsheet software, Microsoft Outlook information management software, Microsoft Publisher desktop-publishing software, and Microsoft Internet Explorer to name a few. These are available from Microsoft Corporation of Redmond, Wash. Other exemplary application programs include the Quarterdeck drawing program HijaakPro and Micrografx drawing programs: ABC Flowcharter, Designer, and Picture Publisher.
A user may enter commands and information into personal computer 20 through input devices such as a keyboard 40 and pointing device 42 . Other input devices (not shown) may include a microphone, joystick, game pad, satellite dish, scanner, or the like. These and other input devices are often connected to processing unit 21 through a serial port interface 46 that is coupled to the system bus, but may be connected by other interfaces, such as a parallel port, game port, or a universal serial bus (USB). A monitor 47 or other type of display device is also connected to system bus 23 via an interface, such as a video adapter 48 . In addition to the monitor, computers typically include other peripheral output devices (not shown), such as speakers and printers.
Computer 20 may operate in a networked environment using logical connections to one or more remote computers, such as remote computer 49 . These logical connections are achieved by a communication device coupled to or a part of the computer 20 . However, the invention is not limited to a particular type of communications device. Remote computer 49 , which may be another computer, a server, a router, a network personal computer (PC), a client, a peer device or other common network node, typically includes many or all of the elements of computer 20 , although FIG. 1 only shows a memory storage device 50 . The logical connections depicted in FIG. 1 include a local-area network (LAN) 51 and a wide-area network (WAN) 52 . Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets and the Internet.
When used in a LAN-networking environment, computer 20 is connected to the local network 51 through a network interface or adapter 53 , which is one type of communications device. When used in a WAN-networking environment, computer 20 typically includes a modem 54 , a type of communications device, or any other type of communications device for establishing communications over wide area network 52 , such as the Internet. Modem 54 , which may be internal or external, is connected to system bus 23 via serial port interface 46 . In a networked environment, program modules depicted relative to personal computer 20 , or portions thereof, may be stored in the remote memory storage device. It is appreciated that the network connections shown are exemplary and other means of and communications devices for establishing a communications link between the computers may be used.
The exemplary computer may be a conventional computer, a distributed computer, or any other type of computer, since the invention is not limited to any particular computer. A distributed computer typically includes one or more processing units as its processor, and a computer-readable medium such as a memory. The computer may also include a communications device such as a network adapter or a modem, so that it is able to communicatively couple with other computers to form a computer network.
Operation of the Exemplary Computer System
This embodiment of the invention primarily concerns interactions among operating system 35 , application programs 36 , mouse 42 , and monitor 47 , particularly document management aspects of operating system 35 . In general, operating system 35 provides a common default folder (or directory)—named My Documents—to application programs 36 and thus makes it easy for a user to consolidate document storage for these application program into a single folder, rather than in the numerous folders which contain the application programs. The embodiment of the invention described in this section of the detailed description relates specifically to versions of the Microsoft Windows operating system; however, the invention is not so limited.
FIG. 2A shows an exemplary method of operating computer system 10 . In particular, the method begins at step 60 with a user starting one of application programs 36 , for example the Microsoft Paint application program. Step 60 occurs under the assumption that computer system 10 has already been appropriately booted and so forth.
In step 62 , the user selects a file command menu 100 and file open option 100 a as shown in FIG. 3 A. In this exemplary embodiment, the user selects the file open option using mouse 42 to highlight and click on field 100 a , which is labeled Open. In response, operating system 35 , namely module 35 c which generally defines common dialog windows (or boxes), presents a file-open dialog window 102 as shown in FIG. 3 B. FIG. 3B illustrates one example of the unlimited number of forms that file-open dialog window 102 can take. File-open dialog window 102 includes a look-in field 102 a which by default specifies the My Documents folder.
However, before actually presenting the My Documents folder as a default document storage option to the user via the graphical user interface, the exemplary embodiment of a operating system 35 determines whether presenting My Documents would override or conflict with another definition of a default document storage folder for the application program. FIG. 2B illustrates an algorithm of module 35 b which makes this determination. The algorithm begins with step 64 with module 35 b determining whether the application program specified a folder other than the My Documents folder during selection of the file open dialog window. If the application program specified a folder, then module 35 c of operating system 35 causes monitor 47 to display an label for that folder in look-in field 102 a of window 102 . However, if the application program did not specify a different folder, module 35 b proceeds to step 66 .
In step 66 , module 35 b determines whether the application program has changed the current folder since (the last time) the file-open dialog window was invoked. If the current folder has changed, module 35 b treats the new current file folder as the default document storage folder for the application program and displays it in look-in field 102 a . However, if there has been no change in the current folder, module 35 b executes step 68 .
In step 68 , module 35 b determines whether any documents in the current file folder, which is typically the folder containing the application program, meet the document-type requirements of the application program. In the exemplary embodiment this entails scanning the current document folder for documents having particular suffixes, or extensions, appended to their names. (Examples of extensions include “doc,” “txt,” and “bmp”). If any documents in the current document folder match the extension(s) specified by the application program, module 35 b treats the current folder as the default folder and presents its name in look-in field 102 a . However, if none are found, module 35 b of operating system 35 proceeds to step 70 , in which it presents My Documents as the default document folder for the application program, by presenting it in look-in field 102 a.
In the case of file save for a new document or a saving of a document under a new name, one would invoke save option 100 b or save-as option 100 c of file menu 100 in FIG. 3 A. In either case, operating system 35 , specifically module 35 c , would cause monitor 47 to display a file-save dialog window, such as window 104 in FIG. 3C, which presents the My Documents folder as a default document storage container in save-in field 104 a . One should appreciate however that exemplary operating system 35 follows the same procedure outlined in FIG. 2B to avoid contradicting another definition of a default document storage folder for the application program.
Although the method described above and illustrated in FIGS. 2A and 2B is straightforward for those of ordinary skill, one should appreciate that the subtleties of particular operating-system modules and architectures in relation to specific application programs, may require special attention. For example, in the exemplary implementation, it was useful, though not essential, to enhance the shell or other program modules of the Microsoft Windows 95 operating system—as recited in the previous section of the detailed description—to handle some special-case, or non-conforming, application programs.
Specifically, it is useful to keep a list of special-case application programs. Such programs include, for example, the Lotus Wordpro program, and the 1995 and 1997 versions of the Microsoft Word, Access, Powerpoint, and Binder programs. In this highly particular implementation of the invention, module 35 b include instructions to check the window-class name of the calling application program (that is, the application calling for a common file dialog window) against the list of special-case applications. If the calling application program is on the list, module 35 b returns what would otherwise be incorrect results or data to the application to work around bad assumptions or “bugs” in the application programs, thereby allowing the operating system to specify the My Documents folder as the default document storage container for that application program.
Relatedly, the shell is also enhanced in one specific embodiment of the invention to allow a shell extension to be queried for attributes and parsing information which had previously been static declarations in the shell registry. In the prior art, the shell only allows shell extension attributes to be statically specified in the registry. Additionally, for the RegItems listed in the registry, as such items are known within the art, all work for the IShellFolder::GetDisplayNameOf function is done by the shell for the SFGAO_FORPARSING flag. The shell is changed to allow the shell extension to specify not only that it wants to be called for its attributes dynamically, but also that it wants to handle the IShellFolder::GetDisplayNameOf call, as also known in the art. Without these changes, it is generally more difficult to operate this implementation of the invention with the special-case applications.
Convenient Access to the My Documents Default Storage Folder
Another facet of the invention promotes use of the My Documents folder by presenting it as a user-selectable option at various file access points in the graphical-user-interface of operating system 35 . The embodiments of the invention described in this section of the detailed description also relate specifically to versions of the Microsoft Windows operating system; however, the invention itself is not so limited. As FIG. 4A shows, one way to promote use of the My Documents folders is to insert an icon 106 a for the My Documents folder at the highest or most visible level of the graphical user interface, that is, on the metaphorical desktop, denoted 106 . Moreover, icon 106 a has a unique appearance which distinguishes from other folder icons 106 b , 106 c , and 106 d on the desktop and throughout the graphical user interface. In particular, icon 106 a is a perspective view of a partially open file folder with a text-bearing document inside, with the file, document, and text being of different colors. In constrast, conventional folder icons 106 b-d provide only side views of closed folders.
FIG. 4B shows a second way. Specifically, FIG. 4B shows a common file-open dialog window 108 which includes a selectable desktop icon 108 a . The figure also illustrates that selecting the icon not only causes operating system 35 to display the icon and the label desktop cause in a look-in field 108 b , but also to display links to desktop-document-storage containers in field 108 c . In addition to a link to the My Documents folder, these include links to the My Computer folder, the Network Neighborhood container, and an On-line Services container. (The invention also encompasses the inclusion of the desktop icon on other common file-access windows, such as file-save window as shown in FIG. 3C.) In one sense, this feature gives users who may at times become disoriented in the graphical user interface a easy way of returning to the familiar territory of the desktop.
FIG. 4C shows that a third way of providing convenient access to the My Documents default storage folder integrates the My Documents folder into a file finding feature of operating system 35 . More particularly, FIG. 4C shows a find dialog window 110 which includes a look-in field 110 a for targeting search to particular containers. Further, window 110 includes a browse button (hidden in this view) and a pull-down options menu 110 b with predetermined options for look-in field 110 a . Among the options on menu 110 b is an option for a Document Folders container which includes a link not only to the desktop ( 106 in FIG. 4A) but also a link to the My Documents folder.
A fourth way of providing convenient access to the My Documents folder is to provide a link the folder in a list of most-recently-used documents. For example, FIG. 4D shows a Start menu 112 which has been invoked on desktop 106 to show a Documents submenu 112 a . A section 112 b of the submenu. includes a list of most-recently-used documents which includes a link 112 c to the My Documents folder. Thus, if the list lacks a particular documents that a user wants to access, the user may easily check the My Documents folder for it. In addition, this most-recently-used documents feature is also included within a file-open dialog window. Those of skill in the art, however, will understand that this augmented most-recently-used documents list may be placed anywhere in the graphical user interface. (An extension to this approach is to supplement or substitute the list of most-recently-used documents with a list of most-recently-accessed document folders.)
A fifth way is to incorporate a link to the My Documents folder in a file send feature as shown in FIG. 4 E. This figure shows a Send To menu with an option to send a file to a floppy disk drive, to the desktop, to a mail recipient, or to the My Documents folder.
Two Uses of My Documents Default Storage Folder in Network Environments
One computer-network application of the My Documents folder allows network administrators more flexibility in maintaining links to document shares for users. Within the prior art, to maintain links to shared documents in a network, a network administrator would has to insert special link files, known as short cuts in versions of the Microsoft Windows operating systems, on all the computers of all the users within a computer network. This is a time consuming process. For example, when a new shared destination is desired for all the users on a project, the network administrator has to manually save shortcuts to this destination on all the users' computers. To overcome this problem, exemplary operating system 35 , specifically module 35 b , looks in the shell registry for these pointers instead of in files. As those of ordinary skill within the art can appreciate, the registry is easily updated remotely, over a network, instead of having to physically go to each person's computer.
Another network aspect of the invention allows a network administrator to set and control the target of the default-storage folder, in other words, the storage device or devices or portions of these devices which actually store the contents of the folder. (These storage devices may be network or local storage devices.) Within the prior art, a short cut file typically specifies the target, or destination folder, such that the link to this folder cannot be easily changed; the administrator may have to physically go to a user's computer, delete the old short cut file, and create a new short cut file when the destination related to the short cut file changes.
One way of overcoming this problem is to store the target of each user's My Documents folder, or any other destination folder, in the shell registry of the user's operating system. The network administrator can then update the shell registry two ways: first, by updating a centralized network user registry which is propagated upon log-in to a user's shell registry; and second by simply “reaching into” and modifying the user's local shell registry. In both cases, the administrator can easily change or update the target for each user without any user intervention.
For example, when the destination folder changes from being on a hard disk drive specified by a drive letter “h:” to another hard disk drive specified by a drive letter “j:,” the administrator only has to use available network administration tools to change the registry of each user's computer to reflect this change via the My Documents folder, instead of having to manually go to each user's computer and arranging for a new short cut file.
Conclusion
In furtherance of the art, the inventors have presented an operating system which provides a common default storage folder for one or more application programs in a computer system. In addition, the inventors provided the operating system with a graphical user interface that includes several conveniently placed links to the common default storage folder. The embodiments described above are intended only to illustrate and teach one or more ways of practicing or implementing the present invention, not to restrict its breadth or scope. The actual scope of the invention, which embraces all ways of practicing or implementing the concepts of the invention, is defined only by the following claims and their equivalents. | 4y
|
BACKGROUND OF THE INVENTION
[0001] Several forms of arrayed hybridization reactions are currently being developed under the common rubric of “sequencing by hybridization” (SBH). Included are “format 1” versions of SBH, involving stepwise hybridization of different oligonucleotide probes with arrays of DNA samples gridded onto membranes, and “format 2” implementations, involving hybridization of a single nucleic acid “target sequence” to an array of oligonucleotide probes tethered to a flat surface or immobilized within a thin gel matrix. The term “genosensor” has heretofore referred to a form of SBH in which oligonucleotides are tethered to a surface in a two-dimensional array and serve as recognition elements for complementary sequences present in a nucleic acid “target” sequence. The genosensor concept further includes microfabricated devices in which microelectronic components are present in each test site, permitting rapid, addressable detection of hybridization across the array.
[0002] The present invention provides a novel flow-through genosensor, in which nucleic acid recognition elements are immobilized within densely packed pores or channels, arranged in patches across a wafer of solid support material. Known microfabrication techniques are available for producing microchannel or nanochannel glass and porous silicon useful as support wafers. Flow-through genosensors utilize a variety of conventional detection methods, including microfabricated optical and electronic detection components, film, charge-coupled-device arrays, camera systems and phosphor storage technology.
[0003] The following advantages for the novel flow-through apparatus herein as compared to known flat surface designs are obtained:
[0004] (1) improved detection sensitivity due to the vastly increased surface area which increases the quantity of nucleic acid bound per cross sectional area;
[0005] (2) minimization of a rate-limiting diffusion step preceding the hybridization reaction (reducing the time required for the average target molecule to encounter a surface-tethered probe from hours to milliseconds), speeding hybridization and enabling mismatch discrimination at both forward and reverse reactions;
[0006] (3) enablement of the analysis of dilute nucleic acid solutions because of the ability to gradually flow the solution through the porous wafer;
[0007] (4) facilitation of subsequent rounds of hybridization involving delivery of probes to specific sites within the hybridization array;
[0008] (5) facilitation of the recovery of bound nucleic acids from specific hybridization sites within the array, enabling the further analysis of such recovered molecules; and
[0009] (6) facilitation of the chemical bonding of probe molecules to the surface within each isolated region due to the avoidance of the rapid drying of small droploets of probe solution on flat surfaces exposed to the atmosphere.
[0010] Accordingly, the present invention provides an improved apparatus and method
for the simultaneous conduct of a multiplicity binding reactions on a substrate, which substrate is a microfabricated device comprising a set of discrete and isolated regions on the substrate, such that each such discrete and isolated region corresponds to the location of one such binding reaction, in which each such discrete and isolated region contains an essentially homogeneous sample of a biomolecule of discrete chemical structure fixed to such bounded region, such that upon contact between the substrate and a sample (hereinafter, “test sample”) containing one or more molecular species capable of controllably binding with one or more of the pre-determined biomolecules, the detection of the bounded regions in which such binding has taken place yields a pattern of binding capable of characterizing or otherwise identifying the molecular species in the test sample.
[0017] The present invention specifically provides novel high-density and ultra-high density microfabricated, porous devices for the conduction and detection of binding reactions. In particular, the present invention provides improved “genosenors” and methods for the use thereof in the identification or characterization of nucleic acid sequences through nucleic acid probe hybridization with samples containing an uncharacterized polynucleic acid, e.g., a cDNA, mRNA, recombinant DNA, polymerase chain reaction (PRC) fragments or the like, as well as other biomolecules.
[0018] During the past decade microfabrication technology has revolutionized the electronics industry and has enabled miniaturization and automation of manufacturing processes in numerous industries. The impact of microfabrication technology in biomedical research can be seen in the growing presence of microprocessor-controlled analytical instrumentation and robotics in the laboratory, which is particularly evident in laboratories engaged in high throughput genome mapping and sequencing. The Human Genome Project is a prime example of a task that whose economics would greatly benefit from microfabricated high-density and ultra-high density hybridization devices that can be broadly applied in genome mapping and sequencing.
[0019] Hybridization of membrane-immobilized DNAs with labeled DNA probes is a widely used analytical procedure in genome mapping. Robotic devices currently enable gridding of 10,000-15,000 different target DNAs onto a 12 cm×8 cm membrane. Drmanac, R., Drmanac, S., Jarvis, J. and Labat, 1. 1993. in Venter, J. C. (Ed.), Automated DNA Sequencing and Analysis Techniques, Academic Press, in press, and Meier-Ewert, S., Maier, E., Ahmadi, A., Curtis, J. and Lehrach, H. 1993. Science 361:375-376. Hybridization of DNA probes to such filters has numerous applications in genome mapping, including generation of linearly ordered libraries, mapping of cloned genomic segments to specific chromosomes or megaYACs, cross connection of cloned sequences in cDNA and genomic libraries, etc. Recent initiatives in “sequencing by hybridization” (SBH) aim toward miniaturized, high density hybridization arrays. A serious limitation to miniaturization of hybridization arrays in membranes or on flat surfaces is the quantity of DNA present per unit cross sectional area, which (on a two-dimensional surface) is a function of the surface area. This parameter governs the yield of hybridized DNA and thus the detection sensitivity.
[0020] Genosensors, or miniaturized “DNA chips” are currently being developed in several laboratories for hybridization analysis of DNA samples. DNA chips typically employ arrays of DNA probes tethered to flat surfaces, e.g., Fodor, S. P. A., Read, J. L., Pirrung, M. C., Stryer, L., Lu, A. T. and Solas, D. 1991. Science 251:767-773, Southern, E. M., Maskos, U. and Elder, J. K. 1992. Genomics 13:1008-1017, Eggers, M. D., Hogan, M. E., Reigh, R. K., Lamture, J. B., Beattie, K. L., Hollis, M. A., Ehrlich, D. J., Kosicki, B. B., Shumaker, J. M., Varma, R. S., Burke, B. E., Murphy, A. and Rathman, D. D. 1993. Advances in DNA Sequencing Technology, SPIE Conference, Los Angeles, Calif., and Beattie, K., Eggers, M., Shumaker, J., Hogan, M., Varma, R., Lamture, J., Hollis, M., Ehrlich, D. and Rathman, D. 1993. Clin. Chem. 39:719-722, to acquire a hybridization pattern that reflects the nucleotide sequence of the target DNA. The detection limit for hybridization on flat-surface genosensors, as in membrane hybridization, is limited by the quantity of DNA that can be bound to a two dimensional area
[0021] Another limitation of these prior art approaches is the fact that a flat surface design introduces a rate-limiting step in the hybridization reaction, i.e., diffusion of target molecules over relatively long distances before encountering the complementary probes on the surface. In contrast, the microfabricated apparatus according to the present invention is designed to overcome the inherent limitations in current solid phase hybridization materials, eliminating the diffusion-limited step in flat surface hybridizations and increasing the cross sectional density of DNA.
[0022] Typically microfabricated genosensor devices are characterized by a compact physical size and the density of components located therein. Known microfabricated binding devices are typically rectangular wafer-type apparatuses with a surface area of approximate one cm 2 , e.g., 1 cm×1 cm. The bounded regions on such devices are typically present in a density of 10 2 -10 4 regions/cm 2 , although the desirability of constructing apparatuses with much higher densities has been regarded as an important objective. See Eggers and Beattie, cited above, for discussion of strategies for the construction of devices with higher densities for the bounded regions.
[0023] The microfabricated apparatuses as described herein are known to be useful for a variety of analytical tasks, including nucleic acid sequence analysis by hybridization (SBH), analysis of patterns of gene expression by hybridization of cellular mRNA to an array of gene-specific probes, immunochemical analysis of protein mixtures, epitope mapping, assay of receptor-ligand interactions, and profiling of cellular populations involving binding of cell surface molecules to specific ligands or receptors inmobilized within individual binding sites. Although nucleic acid analysis is one principal use for such an microapparatus, it is advantageously applied to a broad range of molecular binding reactions involving small molecules, macromolecules, particles, and cellular systems. See, for example, the uses described in PCT Published Application WO 89/10977.
[0024] Ordinarily the microfabricated apparatus is used in conjunction with a known detection technology particularly adapted to discriminating between bounded regions in which binding has taken place and those in which no binding has occurred and for quantitating the relative extent of binding in different bounded regions. In DNA and RNA sequence detection, autoradiography and optical detection are advantageously used. Autoradiography is performed using 32 P or 35 S labelled samples. For traditional DNA sequence analysis applications, nucleic acid fragments are end-labeled with 32 P and these end-labeled fragments are separated by size and then placed adjacent to x-ray film as needed to expose the film, a function of the amount of radioactivity adjacent to a region of film. Alternatively, phophorimager detection methods may be used.
[0025] Optical detection of fluorescent-labelled receptors is also employed in detection. In traditional sequencing, a DNA base-specific fluorescent dye is attached covalently to the oligonucleotide primers or to the chain-terminating dideoxynucleotides used in conjunction with DNA polymerase. The appropriate absorption wavelength for each dye is chosen and used to excite the dye. If the absorption spectra of the dyes are close to each other, a specific wavelength can be chosen to excite the entire set of dyes. One particularly useful optical detection technique involves the use of ethidium bromide, which stains duplex nucleic acids. The fluorescence of these dyes exhibits an approximate twenty-fold increase when it is bound to duplexed DNA or RNA, when compared to the fluorescence exhibited by unbound dye or dye bound to single-stranded DNA. This dye is advantageously used to detect the presence of hybridized polynucleic acids.
[0026] A highly preferred method of detection is a charge-coupled-device array or CCD array. With the CCD array, a individual pixel or group of pixels within the CCD array is placed adjacent to each confined region of the substrate where detection is to be undertaken. Light attenuation, caused by the greater absorption of an illuminating light in test sites with hybridized molecules, is used to determine the sites where hybridization has taken place. Lens-based CCD cameras can also be used.
[0027] Alternatively, a detection apparatus can be constructed such that sensing of changes in AC conductance or the dissipation of a capacitor placed contiguous to each confined region can be measured. Similarly, by forming a transmission line between two electrodes contiguous to each confined region hybridized molecules can be measured by the radio-frequence (RF) loss. The preferred methods for use herein are described in, Optical and Electrical Methods and Apparatus for Molecule Detection, PCT Published Application WO 93/22678, published Nov. 11, 1993, and expressly incorporated herein by reference.
[0028] Methods for attaching samples of substantially homogeneous biomolecules of a pre-determined structure to the confined regions of the microapparatus are likewise known. One preferred method of doing so is to attach these biomolecules covalently to surfaces such as glass or gold films. For example, methods for attachments of oligonucleotide probes to glass surfaces are known. A primary amine is introduced at one terminus during the chemical synthesis thereof. Optionally, one or more triethylene glycol units may be introduced therebetween as spacer units. After derivatizing the glass surface in the confined region with epoxysilane, the primary amine terminus of the oligonucleotide can be covalently attached thereto.
[0029] See Beattie, et al., cited above, for a further description of this technology for fixing the pre-determined biomolecules in the bounded regions of the microfabricated apparatus.
RELATED ART
[0030] Khrapko, K. R., et al., A method for DNA sequencing by hybridization with oligonucleotide matrix, J. DNA Sequencing and Mapping, 1:375-388 (1991), Drmanac, Radoje, et al., Sequencing by hybridization: Towards an automated sequencing of one million M 13 clones arrayed on membranes Electrophoresis 13:566-573 (1992), Meier-Ewert, Sebastian, An automated approach to generating expressed sequence catalogues, Nature 361:375-376 (1993), Drmanac, R., et al., DNA Sequence Determination by Hybridization: A Strategy for Efficient Large - Scale Sequencing, Science 260:1649-1652 (1993), Southern, E. M., et al., Analyzing and Comparing Nucleic Acid Sequences by Hybridization to Arrays of Oligonucleotides: Evaluation Using Experimental Models, Genomics 13:1008-1017 (1992), and Saiki, Randall K., et al., Genetic analysis of amplified DNA with immobilized sequence - specific oligonucleotide probes, Proc. Natl. Acad. Sci. USA 86:6230-6234 (1989) describe sequence-by-hybridization determinations, including via the use of arrays of oligonucleotides attached to a matrix or substrate. Eggers, Mitchell D., et al., Genosensors: microfabricated devices for automated DNA sequence analysis, SPIE Proceedings Series, Advances in DNA Sequence Technology, Proceedings Preprint, The International Society for Optical Engineering, 21 Jan. 1993; Beattie, Kenneth, et al., Genosensor Technology, Clinical Chemistry 39:719-722 (1993); Lamture, J. B., et al., Direct detection of nucleic acid hybridization on the surface of a charge coupled device, Nucl. Acids Res. 22:2121-2124 (1994); and Eggers, M., et al., A microchip for quantitative detection of molecules utilizing luminescent and radioisotope reporter groups, Biotechniques 17:516-525 (1994) describe the general strategies and methodologies for designing microfabricated devices useful in sequencing by hybridization (SBH) for DNA.
SUMMARY OF THE INVENTION
[0000] The present invention particularly provides:
[0031] (a) In a microfabricated device comprising—
[0032] (1) a substrate containing a multiplicity of discrete and isolated regions arrayed across a surface thereof and adapted to interact with or integrally interacting with a detecting means capable of identifying and addressing each of said regions and determining and reporting whether a binding reaction has taken place therein, and
[0033] (2) essentially homogeneous samples of biomolecules of pre-determined structures fixed in each of said discrete and isolated regions, such that the detection of a binding reaction between said biomolecules in one or more of said regions and a test sample provides information capable of identifying or otherwise characterizing the molecular species in said test sample,
[0000] the improvement that comprises:
[0034] discrete and isolated regions that extend through said substrate and terminate on a second surface thereof such that said test sample upon contact with said substrate is capable of penetrating therethrough during the course of said binding reaction.
[0035] (b) The improvement above wherein said biomolecules are oligonucleotides and said test sample comprises polynucleic acids.
[0036] (c) The improvement above wherein said substrate is a nanoporous glass wafer.
[0037] (d) The improvement above wherein said discrete and isolated regions comprise tapered conical wells bonded to one face of said nanoporous glass wafer.
[0038] (e) The improvement above comprising a high density array, wherein each of said discrete and isolated regions on said nanoporous glass wafer has a largest diameter of about 100 μm, the spacing between adjacent regions is about 500 μm, said wafer is about 100 μm in thickness, whereby the volume of said region within the wafer is about 40 nL and the density of said regions on said wafer is about 400 regions/cm 2 .
[0039] (f) The improvement above comprising an ultra-high density array, wherein each of said discrete and isolated regions on said nanoporous glass wafer has a largest diameter of about 50 μm, the spacing between adjacent regions is about 150 μm, said wafer is about 50 μm in thickness, whereby the volume of said region within the wafer is about one nL and the density of said regions on said wafer is about 4,400 regions/cm 2 .
[0040] (g) The improvement above comprising an array, wherein each of said discrete and isolated regions on said nanoporous glass wafer has a largest diameter of from about 5 μm to about 2000 μm, the spacing between adjacent regions is from about 0.1 to 10 times said largest diameter, and said wafer is from about 10 μm to about 500 μm in thickness.
[0041] (h) The improvement above wherein the contact between said test sample and said discrete and isolated regions is by flooding the first surface of said substrate with said test sample and placing said second surface of said substrate under negative pressure relative to said first surface, whereby the resulting vacuum facilitates the flow through said substrate.
[0042] (i) The improvement above wherein said oligonucleotides are fixed in said isolated and discrete regions on said substrate by attaching a terminal primary amine derivative of said oligonucleotide to a glass substrate derivatized with epoxysilane.
[0043] (j) The improvement above wherein said oligonucleotide-silane fixation comprises the incorporation of one or more triethylene glycol phosphoryl units, whereby optimal spacing between said glass surface and the base pairs of said oligonucleotide is achieved.
[0044] (k) The improvement above wherein said oligonucleotides are fixed in said isolated and discrete regions on said substrate by attaching a terminal bromoacetylated amine derivative of said oligonucleotide to a platinum or gold substrate derivatized with a dithioalkane.
[0045] (l) The improvement above wherein said detection of said binding reaction is detection by a charge-coupled device (CCD) employed to detect hybridization of radioisotope-, fluorescent-, or chemiluminescent-labelled polynucleic acids.
[0046] (m) A microfabricated device for simultaneously conducting a multiplicity of binding reactions, comprising:
[0047] (1) a substrate providing a rigid support for said device;
[0048] (2) an array of discrete and isolated regions arranged across a surface of said substrate and extending therethrough to a second surface of said substrate, thereby forming pores in said substrate;
[0049] (3) substantially homogeneous samples of a pre-determined set of biomolecules, each such sample being fixed in one or more of said regions, such that one or more of said biomolecules is capable of binding with a molecular species in a test sample passing therethrough; and
[0050] (4) a detection means capable of determining for each such region whether a binding reaction has taken place and reporting the result thereof.
[0051] (n) A device as described above further comprising a means for providing fluidic flow through the substrate.
[0052] (o) In a method for using a microfabricated device for the identification of the molecular species contained in a test sample, said device comprising—
[0053] (1) a substrate containing a multiplicity of discrete and isolated regions arrayed across a surface thereof and adapted to interact with or integrally interacting with a detecting means capable of characterizing or otherwise identifying and addressing each of said regions and determining and reporting whether a binding reaction has taken place therein, and
[0054] (2) essentially homogeneous samples of biomolecules of pre-determined structures fixed in each of said discrete and isolated regions, such that the detection of a binding reaction between said biomolecules in one or more of said regions and said test sample provides information capable of characterizing or otherwise identifying the molecular species in said test sample,
[0000] the improvement that comprises:
[0055] allowing said test sample, during the course of said binding reaction, to penetrate through said discrete and isolated regions by constructing said regions to contain pores that extend through said substrate and terminate on a second surface thereof.
[0056] The devices of the present invention are used to characterize or otherwise identify molecular species capable of controllably binding to biomolecules in the same manner and using the same binding regimens as are known in the art. Although uses of these novel devices include antibody-antigen and ligand-receptor binding, a major use of the present invention is in the field of nucleic acid sequence analysis. Two fundamental properties of DNA are vital to its coding and replicational functions in the cell.
[0057] (1) The arrangement of “bases” [adenenine (A), guanine (G), cytosine (C) and thymine (T)] in a specific sequence along the DNA chain defines the genetic makeup of an individual. DNA sequence differences account for the differences in physical characteristics between species and between different individuals of a given species
[0058] (2) One strand of DNA can specifically pair with another DNA strand to form a double-stranded structure in which the bases are paired by specific hydrogen bonding: A pairs with T and G pairs with C. Specific pairing also occurs between DNA and another nucleic acid, ribonucleic acid (RNA), wherein uracil (U) in RNA exhibits the same base pairing properties as T in DNA.
[0059] The specific pattern of base pairing (A with T or U and G with C) is vital to the proper functioning of nucleic acids in cells, and also comprises a highly specific means for the analysis of nucleic acid sequences outside the cell. A nucleic acid strand of specific base sequence can be used as a sequence recognition element to “probe” for the presence of the perfectly “complementary” sequence within a nucleic acid sample (Conner, et al., Proc. Natl. Acad. Sci., U.S.A., 80:278-282 (1983)). Thus, if a sample of DNA or RNA is “annealed” or “hybridized” with a nucleic acid “probe” containing a specific base sequence, the probe will bind to the nucleic acid “target” strand only if there is perfect (or near-perfect) sequence complementarity between probe and target. The hybridization event which indicates the presence of a specific base sequence in a nucleic acid sample is typically detected by immobilization of the nucleic acid sample or the probe on a surface, followed by capture of a “tag” (for example, radioactivity or fluorescence) carried by the complementary sequence.
[0060] DNA hybridization has been employed to probe for sequence identity or difference between DNA samples, for example in the detection of mutations within specific genetic regions (Kidd, et al., N. Engl. J. Med., 310:639-642 (1984); Saiki, et al., N. Engl. J. Med., 319:537-541 (1988); Saiki, et al., Proc. Natl. Acad. Sci., U.S.A., 86:6230-6234 (1989)). Although DNA probe analysis is a useful means for detection of mutations associated with genetic diseases, the current methods are limited by the necessity of performing a separate hybridization reaction for detection of each mutation. Many human genetic diseases, for example, cancer (Hollstein, et al., Science, 253:49-53 (1991)) are associated with any of a large number of mutations distributed at many locations within the affected genes. In these cases it has been necessary to employ laborious DNA sequencing procedures to identify disease-associated mutations. The problem is compounded when there is a need to analyze a large number of DNA samples, involving populations of individuals. Detection of mutations induced by exposure to genotoxic chemicals or radiation is of interest in toxicology testing and population screening, but again, laborious, costly and time consuming procedures are currently necessary for such mutational analyses.
[0061] In addition to causing genetic diseases, mutations are also responsible for DNA sequence polymorphisms between individual members of a population. Genetic polymorphisms are DNA sequence changes at any given genetic locus which are maintained in a significant fraction of the individuals within a population. DNA sequence polymorphisms can serve as useful markers in genetic mapping when the detectable DNA sequence changes are closely linked to phenotypic markers and occur at a frequency of at least 5% of the individuals within a population. In addition, polymorphisms are employed in forensic identification and paternity testing. Currently employed methods for detecting genetic polymorphisms involve laborious searches for “restriction fragment length polymorphisms” (RFLPS) (Lander and Bottstein, Proc, Natl. Acad, Sci., U.S.A., 83:7353-7357 (1986)), the likewise laborious use of gel electrophoretic DNA length analysis, combined with a DNA amplification procedure which utilizes oligonucleotide primers of arbitrary sequence (Williams, et al., Nucl. Acids Res., 18:6531-6535 (1991); Welsh and McClelland, Nucl. Acids Res., 18:7213-7218 (1991)), and the gel electrophoretic analysis of short tandem repeat sequences of variable length) in genomic DNA. Weber, James L., Genomics 7: 524-530 (1990) and Weber, James L., Am. J. Hum. Genet. 44: 388-396 (1989).
[0062] Another kind of DNA sequence variation is that which occurs between species of organisms, which is of significance for several reasons. First, identification of sequence differences between species can assist in the determination of the molecular basis of phenotypic differences between species. Second, a survey of sequence variation within a specific gene among numerous related species can elucidate a spectrum of allowable amino acid substitutions within the protein product encoded by the gene, and this information is valuable in the determination of structure-function relationships and in protein engineering programs. However, this type of targeted DNA sequence comparison is extremely laborious, time consuming and costly if carried out by current DNA sequencing methodology. Additionally, genetic sequence variation can form the basis of specific identification of organisms, for example, infectious micro-organisms.
[0063] The apparatus of the present invention is employed in a variety of analytical tasks, including nucleic acid sequence analysis by hybridization, analysis of patterns of gene expression by hybridization of cellular mRNA to an array of gene-specific probes, immunochemical analysis of protein mixtures, epitope mapping, assay of receptor-ligand interactions, and profiling of cellular populations involving binding of cell surface molecules to specific ligands or receptors immobilized within individual binding sites. Although nucleic acid analysis is specifically taught in this disclosure, the present invention can be equally applied to a broad range of molecular binding reactions involving small molecules, macromolecules, particles, and cellular systems.
BRIEF DESCRIPTION OF THE DRAWINGS
[0064] FIG. 1 depicts the use of an array of tapered sample wells that comprise a rigidifying support member for the porous wafer containing 0.1-10 micron diameter channels comprising the bonding region for the biomolecules fixed therein. As described below, the binding region is a microporous or nanoporous glass wafer to which the upper polymeric layer is attached.
[0065] FIG. 2 depicts the packaging of a wafer substrate in a sealed lower chamber to which a vacuum may be applied such that material applied to an upper reservoir contacts with the upper surface of the porous substrate is driven through the sample wells. Specifically depicted in FIG. 2 is the use of a Delrin O-Ring comprising the wafer-lower chamber seal.
[0066] FIG. 3 depicts a porous silicon wafer with integral sample wells. Procedures for constructing the depicted device are described in Example 3.
[0067] FIG. 4 depicts the same vacuum-containing wafer-lower chamber apparatus of FIG. 2 with an additionally optioral pressurized upper chamber. Again, as depicted, the upper chamber is sealed by use of a Delrin O-Ring.
[0068] FIG. 5 provides an idealized schematic depiction of the results of an hprt mutation detection assay on a device in accordance with the present invention. The sequence depicted on the left side of the figure corresponds to nucleotides 23-55 of SEQ ID NO:2. One of the two sequences in the right side of the figure corresponds to nucleotides 3-22 of SEQ ID NO:4 (sequence with A in the 16th position from the left) and the other to nucleotides 3-22 of SEQ ID NO:5 (bottom sequence with G replacing A at position 16).
[0069] FIG. 6 provides an idealized schematic depiction of a hybridization assay performed to profile gene expression under different experimental conditions. Details of the assay procedure are provided in Example 11.
DETAILED DESCRIPTION
[0070] The present invention is more readily understood through the following preferred embodiments:
EXAMPLE 1
Nanochannel Glass (NCG) Wafers
[0071] Two types of nanochannel glass arrays developed at the Naval Research Laboratory are used as high surface area nanoporous support structures to tether DNA targets or probes for hybridization. NCG materials are unique glass structures containing a regular geometric array of parallel holes or channels as small as 33 nm in diameter or as large as several micrometers in diameter. See Tonucci, R. J., Justus, B. L., Campillo, A. J. and Ford, C. E. 1992. Science 258:783-785. These nanochannel glass structures can possess packing densities in excess of 3×10 10 channels per square centimeter, fabricated in various array configurations. A variety of materials can be immobolized or fixed to the glass surfaces within the channels of the NCG array, to yield a high surface area to volume ratio.
[0072] Nanochannel glass arrays are fabricated by arranging dissimilar glasses in a predetermined configuration, where at least one glass type is usually acid etchable. Construction of a two-dimensional hexagonal close packing array begins by insertion of a cylindrical acid etchable glass rod (referred to as the channel glass) into an inert glass tube (referred to as the matrix glass) whose inner dimensions match that of the rod. The pair is then drawn under vacuum to reduce the overall cross-section to that of a fine filament. The filaments are then stacked, re-fused and redrawn. This process is continued until appropriate channel diameters and the desired number of array elements are achieved. By adjusting the ratio of the diameter of the etchable glass rod to that of the outside dimension of the inert glass tubing, the center-to-center spacing of the rods and their diameters in the finished product become independently adjustable parameters.
[0073] Once the fabrication process is complete, the NCG material is wafered perpendicular to the direction of the channels with a diamond saw and then polished to produce 0.1-1.0 mm sections of material. The channel glass of the array structure is then etched away with an acid solution.
[0074] A hexagonal close packing arrangement of channel glasses, after acid etching, contains typically 10 7 channels and is uniform throughout. The channel diameter is typically 450 nm and the center-to-center spacing is approximately 750 nm. The type of array structure described above is useful in the NCG array hybridization assembly in accordance with the present invention. In this configuration, the tapered sample well structure defines each group of channels serving as a specific hybridization test site.
[0075] A second type of hexagonal array structure, in which separated clusters of channels are formed during the fabrication process, exhibits an open array structure with typical channel diameters of 300 nm. The overall glass structure consists of an array of 18 μm diameter subarrays, each serving to contain a specific DNA probe or target, and spaced typically 25 μm apart from neighboring arrays.
EXAMPLE 2
Well Arrays Defining Discrete and Isolated Binding Regions
[0076] The NCG hybridization arrays described in Example 1 are bonded on the upper side to a polymeric layer containing an array of orifices which align with the array of nanochannel bundles and serve as sample wells for placement of a substantially homogeneous sample of a biomolecule (e.g., a single DNA species) within each hybridization site. This polymeric sample well array also provides physical support to the fragile NCG wafer.
[0077] The polymeric array of orifices are fabricated using methods known in the art. For example, this polymeric layer suitable for use herein can be obtained from MicroFab Technologies, Inc. The orifices are fabricated using excimer laser machining. This method is preferred because existing technology is employed allowing for low cost/high volume manufacturing, as is currently being done in the microelectronics industry.
[0078] Development of the polymeric array comprises four task: (1) materials selection; (2) ablation tooling and process development; (3) lamination tooling and process development; and (4) production of high density and ultra-high density polymeric arrays. These tasks are undertaken as follows:
[0079] Part A: Materials Selection.
[0080] The materials useful in the polymeric array are filled polymers, epoxy resins and related composite (e.g., “circuit-board”-type) materials. Because it is a standard process in the microelectronics industry, the present invention most advantageously employs polymeric materials with the adhesive applied by the commercial vendor of the material for example, a polyamide with a 12 μm thick layer of a B-stage (heat curing) adhesive
[0081] The primary requirements for the polymeric array material to be used are:
[0000] 1. High Suitability for Excimer Laser Machinability:
[0082] i. high absorption in UV (e.g., >4×10 5 /cm at 193 nm),
[0083] ii. high laser etch rate (e.g., 0.5 μm/pulse ) and low hole taper (reduction in hole diameter with depth into material, e.g., <3°);
[0000] 2. Obtainable in thicknesses up to 1 mm;
[0000] 3. Obtainable with B-stage adhesive on one side which is both laser ablatable and suitable for bonding to the nanoporous wafer;
[0000] 4. High rigidity and thermal stability (to maintain accurate alignment of samplewell and NCG wafer features during lamination);
[0000] 5. Compatibility with DNA solutions (i.e., low nonspecific binding)
[0084] Part B: Ablation Tooling and Processing
[0085] Contact mask excimer laser machining is a preferred processing technique because it is a lower cost technique than projection mask excimer laser machining. A projection mask is, however, employed when the feature size less than 50 μm. One or more masks with a variety of pattern sizes and shapes are fabricated, along with fixtures to hold the mask and material to be ablated. These masks are employed to determine the optimal material for laser machining and the optimal machining conditions (i.e., mask hole size, energy density, input rate, etc.). Scanning electron microscopy and optical microscopy are used to inspect the excimer laser machined parts, and to quantify the dimensions obtained, including the variation in the dimensions.
[0086] In addition to ablating the sample wells into the polymeric material, the adhesive material is also ablated. This second ablation is undertaken so that the diameter of the hole in the adhesive is made larger than diameter of the sample well on the adhesive side of the polymeric material. This prevents the adhesive from spreading into the sample well and/or the nanoporous glass during lamination.
[0087] Part C: Lamination Tooling and Processing
[0088] Initial lamination process development is carried out using unablated polymeric material (or alternatively, using glass slides and/or silicon wafers). Cure temperature, pressure, and fixturing are optimized during this process development. Thereafter, the optimized processing parameters are employed to laminate both nanoporous wafers and polymeric arrays. The final lamination is done such that the alignment of the two layers creates functional wells.
[0089] Part D: Production of Polymeric Arrays
[0090] The optimal mask patterns and excimer laser parameters are determined and thereafter employed in the manufacture of contact masks and material holding fixtures. Typically, fabrication is done so as to produce a large number (>100) of parts as the masks wear out with use).
EXAMPLE 3
Porous Silicon Wafers
[0091] Two general types of porous silicon devices are prepared according to the process described herein. First, known microfabrication methods are used to fabricate wafers, bounded by integral sample wells. Second, uniformity porous wafer structures are bonded to the same orifice sample well arrays that were described previously (Example 2) for NCG glass arrays. Porous silicon designs are advantageously employed herein because of their adaptability to low cost mass production processes and their ability to incorporate in the fabrication process structural elements that function in fluidic entry and exit from the hybridization site and structures (e.g., electrodes) that may function in hybridization detection. Stable, open-cell porous materials are used to accomplish enhancements and to introduce qualitatively new features in these devices, whereby the surface area of discrete and isolated binding regions is increased by a factor of 100 to 1000 in hybridization-based electronic, fluorescence and radiation-based DNA detectors. In accomplishing this objective, controlled introduction of high-surface-area supports at the surface detection site is employed.
[0092] Thin-film processing technology is used to deposit chemically inert and thermally stable microporous materials. Materials and processing methods are selected to achieve low-cost semiconductor batch fabrication of integrated semiconductor detectors. The microchip device provides in situ multisite analysis of binding strength as ambient conditions are varied. Porous silicon materials are fabricated in oriented, pore arrays or random interconnected networks and with pore diameters selected over the range from 2 nm to several micrometers.
[0093] Porous silicon is produced most easily through electrochemical etching. It can be processed into two important pore structures, interconnected networks and oriented arrays. The pore diameter is tailored from approximately 2 nm to micrometer dimensions by selection of doping and electrochemical conditions. For n-type material, etching is thought to proceed through a tunneling mechanism in which electrons are injected into the pore surface through field concentration effects. In the case of p-type material the mechanism seems to be through moderation of carrier supply at the electrolyte/silicon interface. In practice, the following structures can be fabricated:
[0094] i) a dense interconnected network layer with porosity of 40-60% and silicon filament size in the nanometer size regime. This is most easily obtained in lightly doped (<1 Ω-cm resistivity) p-type silicon.
[0095] ii) a interconnected branched network of pores of typically 10-nm diameter, axis preferentially oriented along <100> direction, and porosity of 30-80% depending on etching conditions. This is obtained in p-type material of 10 −1 to 10 −2 Ω-cm resistivity.
[0096] iii) dense oriented arrays of pores oriented with axis along <100 > direction and with pore diameters in the range of 10 to 100 nm. Obtained in p-type material with resistivity less than 10 −2 Ω-cm.
[0097] iv) dense oriented arrays of pores oriented along <100> direction and with pore diameters in the range less than 10 nm. Obtained in n-type material with resistivity between 10 −1 and 10 −2 Ω-cm.
[0098] v) dense oriented arrays of rectangular pores oriented with axis along <100 > direction, rectangle side defined by {001} planes, and with pore diameters in the range less than 100 nm. Obtained in p-type material with resistivity between 10 −1 and 10 −2 Ω-cm.
[0099] vi) low density interconnected networks of large (1-μm-diameter) pores. This occurs in lightly doped n-type material.
[0100] These materials are fabricated on the device structures described above.
[0101] Characterization can be undertaken by scanning electron microscopy. The surface wetting properties are varied using vapor treatment with silylation materials and chlorocarbons.
[0102] High-porosity dielectrics which function as molecular sieves are produced by nuclear track etching. While nuclear track etching is used to produce these molecular sieves in a wide range of inorganic materials, it is most often used with dielectrics such as mica and sapphire. In this method, described in U.S. Pat. No. 3,303,085 (Price, et al.), a substrate is first bombarded with nuclear particles (typically several MeV alpha particles) to produce disturbances or “tracks” within the normal lattice structure of the material and then wet-etched to produce pores which follow the tracks caused by the nuclear particles. More specifically, Price et al. disclose that the exposure of a mica substrate to heavy, energetic charged particles will result in the formation of a plurality of substantially straight tracks in its lattice structure and that these tracks can be converted into pores by wet etching the substrate.
[0103] Pore sizes and overall porosity are variably controllable with pores typically 0.2 μm in diameter and densities on the order of 10 9 /cm 2 . Particle track depths are energy dependent on the incident particle beam, but resulting pores can be extended through an entire 500-μm-thick substrate. Incorporation of these materials on the device structures shown above is readily accomplished. In addition, the use of implantation-etched dielectrics as the sensor element has advantages versus the porous silicon approach since the material is hydrophilic.
[0104] A preferred device is the porous silicon array wafer with integral sample wells illustrated in FIG. 3 . This may be constructed as follows: A four inch diameter, 100 μm thick wafer of crystalline silicon (n-type, doped with 10 15 P/cm 3 ) with axis oriented along <100> direction is coated with photoresist and exposed to light through a mask to define a 50×50 array of 200 μm square areas having 200 μm space between them across the 2 cm×2cm central area of the wafer. The process described by V. Lehmann ( J. Electrochem. Soc. 140(100):2836-2843 (1993)) is then used to create patches of closely spaced pores of diameter 2-5 μm, oriented perpendicular to the wafer surface, within each square area defined in the photolithographic step. A 300 μm thick wafer of silicon dioxide is coated with photoresist and exposed to light through the same mask used to define 200 μm square porous regions in the silicon wafer, and acid etching is conducted to create 200 μm square holes in the silicon dioxide wafer. The silicon dioxide wafer is then aligned with and laminated to the porous silicon wafer using a standard wafer bonding process to form the integral structure shown in the figure. During the high temperature annealing step, the silicon surface of each pore is oxidized to form a layer of silicon dioxide. The epoxysilane-amine linkage procedure described in EXAMPLE 4 is then carried out to covalently attach amine-containing biopolymer species to the walls of the pores.
EXAMPLE 4
Oligonucleotide Attachment to Glass/SiO 2
[0105] Part A: Epoxysilane Treatment of Glass
[0106] A stock solution of epoxysilane is freshly prepared with the following proportions: 4 ml 3-glycidoxypropyl-trimethoxysilane, 12 ml xylene, 0.5 ml N,N-diisopropylethylamine (Hunig's base). This solution is flowed into the pores of the wafer, then the wafer is soaked for 5 hours in the solution at 80° C., then flushed with tetrahydrofuran, dried at 80° C., and placed in a vacuum desiccator over Drierrite or stored in a desiccator under dry argon.
[0107] Part B: Attachment of Oligonucleotide
[0108] Oligonucleotide, bearing 5′- or 3′-alkylamine (introduced during the chemical synthesis) is dissolved at 10 μM -50 μM in water and flowed into the porous silica wafer. After reaction at 65° C. overnight the surface is briefly flushed with water at 65° C., then with 10 mM triethylamine to cap off the unreacted epoxy groups on the surface, then flushed again with water at 65° C. and air dried. As an alternative to attachment in water, amine-derivatized oligonucleotides can be attached to epoxysilane-derivatized glass in dilute (eg., 10 mM -50 mM) KOH at 37° C. for several hours, although a higher background of nonspecific binding of target sample DNA to the surface (independent of base pairing) may occur during hybridization reaction.
EXAMPLE 5
Robotic Fluid Delivery
[0109] A Hamilton Microlab 2200 robotic fluid delivery system, equipped with special low volume syringes and 8-position fluid heads, capable of delivering volumes of 10-100 nl at 500 μm xyz stepping and a few percent precision. Using this equipment 40-nl samples of biomolecules (e.g., DNA, olgionucleotides and the like) are placed into the wells of the high density NCG wafer. A piezoelectrically controlled substage custom fitted for the Microlab 2200 permits xy positioning down to submicron resolution. For 1-nl samples, custom fabricated needles are employed. The eight-needle linear fluid head is operated in staggered repetitive steps to generate the desired close spacing across the wafer. The system has a large stage area and rapid motion control, providing the capacity to produce hundreds of replicate hybridization wafers.
[0110] Part A: Microfab Microfluidic Jets
[0111] Methods are known in the art (Microfab Technologies, Inc.) for delivering sub-nanoliter microdroplets of fluids to a surface at submicron precision. A microjet system capable of delivering subnanoliter DNA solutions to the wafer surface is employed as follows: For placement of DNA into individual hybridization sites within ultra-high density wafers, with volumes of one nl (corresponding to a 130 μm sphere or 100 μm cube) commercially available dispensing equipment using ink-jet technology as the microdispensing method for fluid volume below is employed. The droplets produced using ink-jet technology are highly reproducible and can be controlled so that a droplet may be placed on a specific location at a specific time according to digitally stored image data. Typical droplet diameters for demand mode ink-jet devices are 30-100 μm, which translates to droplet volumes of 14-520 pl. Droplet creation rates for demand mode ink-jet devices are typically 2000-5000 droplets per second. Thus, both the resolution and throughput of demand mode inkjet microdispensing are in the ranges required for the ultrahigh density hybridization wafer.
[0112] Part B: Microdispensing System
[0113] The microdispensing system is modified from a MicroFab drop-on-demand ink-jet type device, hereafter called a MicroJet device such that this type of device can produce 50 μm diameter droplets at a rate of 2000 per second. The operating principles of this type of device are known (D. B. Wallace, “A Method of Characteristics Model of a Drop-On-Demand Ink-Jet Device Using an Integral Drop Formation Method,” ASME publication 89-WA/FE4, December 1989) and used to effect the modification. To increase throughput, eight of these devices are integrated into a line array less than 1 inch (25 mm) long. The eight devices are loaded with reagent simultaneously, dispense sequentially, and flush simultaneously. This protocol is repeated until all of the reagents are dispensed. Most of the cycle time is associated with loading and flushing reagents, limiting the advantages of a complex of parallel dispensing capability. Typical cycle time required is as on the following order: 1 minute for flush and load of 8 reagents; 30 seconds to calibrate the landing location of each reagent; 15 seconds to dispense each reagent on one location of each of the 16 genosensors, or 2 minutes to dispense all 8 reagents. Total time to load and dispense 8 reagents onto 16 sensors is thus 3.5 minutes. Total time for 64 reagents onto 16 sensors would be 28 minutes. The microdispensing system will consist of the subsystems listed below:
[0114] A. MicroJet Dispense Head—An assembly of 8 MicroJet devices and the required drive electronics. The system cost and complexity are minimized by using a single channel of drive electronics to multiplex the 8 dispensing devices. Drive waveform requirements for each individual device are downloaded from the system controller. The drive electronics are constructed using conventional methods.
[0115] B. Fluid Delivery System—A Beckman Biomec is modified to act as the multiple reagent input system. Between it and the MicroJet dispense head are a system of solenoid valves, controlled by the system controller. They provide pressurized flushing fluid (deionized water or saline) and air to purge reagent from the system and vacuum to load reagent into the system.
[0116] C. X-Y Positioning System—A commercially available precision X-Y positioning system, with controller, is used. Resolution of 0.2 μm and accuracy of 2 μm are readily obtainable. The positioning system is sized to accommodate 16 sensors, but MicroJet dispense head size, purge station, and the calibration station represent the main factors in determining overall size requirements.
[0117] D. Vision System—A vision system is used to calibrate the “landing zone” of each MicroJet device relative to the positioning system. Calibration occurs after each reagent loading cycle. Also, the vision system locates each dispensing site on each sensor when the 16 sensor tray is first loaded via fiducial marks on the sensors. For economy, a software based system is used, although a hardware based vision system can be advantageously employed.
[0118] E. System Controller—A standard PC is used as the overall system controller. The vision system image capture and processing also reside on the system controller.
EXAMPLE 6
Liquid Flow-Through
[0119] In order to bind DNA probes or targets within the pores of the microfabricated hybridization support, carry out the hybridization and washing steps, process the material for re-use, and potentially recover bound materials for further analysis, a means is provided for flow of liquids through the wafer. To enable flow of liquid through the hybridization wafer, it is packaged within a 2 mm×4 mm polypropylene frame, which serves as an upper reservoir and structure for handling. A polypropylene vacuum chamber with a Deltin o-ring around its upper edge to permit clamping of the wafer onto the vacuum manifold to form a seal is employed. The vacuum assembly is illustrated in FIG. 4 . For control of fluid flow through the wafer a screw-drive device with feedback control is provided.
EXAMPLE 7
Synthesis and Derivatization of Oligonucleotides
[0120] Oligonucleotides to be used in the present invention are synthesized by the phosphoramidite chemistry (Beaucage, S. L. and Caruthers, M. H. 1981. Tet. Lett. 22:1859-1862) using the segmented synthesis strategy that is capable of producing over a hundred oligonucleotides simultaneously (Beattie, K. L., Logsdon, N. J., Anderson, R. S., Espinosa-Lara, J. M., Maldonado-Rodriguez, R. and Frost, J. D. III. 1988. Biotechnol. Appl. Biochem. 10:510-521; Beattie, K. L. and Fowler, R. F. 1991. Nature 352:548-54926,27). The oligonucleotides can be derivatized with the alkylamino function during the chemical synthesis, either at the 5′-end or the 3′-end.
[0121] Part A: Chemistry of Attachment to Glass
[0122] Optimal procedures for attachment of DNA to silicon dioxide surfaces are based on well-established silicon chemistry (Parkam, M. E. and Loudon, G. M. (1978) Biochem. Biophys. Res. Commun., 1: 1-6; Lund, V., Schmid, R., Rickwood, D. and Hornes, E. (1988) Nucl. Acids Res. 16: 10861-10880). This chemistry is used to introduce a linker group onto the glass which bears a terminal epoxide moiety that specifically reacts with a terminal primary amine group on the oligonucleotides. This versatile approach (using epoxy silane) is inexpensive and provides a dense array of monolayers that can be readily coupled to terminally modified (amino- or thiol-derivatized) oligonucleotides. The density of probe attachment is controlled over a wide range by mixing long chain amino alcohols with the amine-derivatized oligonucleotides during attachment to epoxysilanized glass. This strategy essentially produces a monolayer of tethered DNA, interspersed with shorter chain alcohols, resulting in attachment of oligonucleotides down to 50 Å apart on the surface. Variable length spacers are optionally introduced onto the ends of the oligonucleotides, by incorporation of triethylene glycol phosphoryl units during the chemical synthesis. These variable linker arms are useful for determining how far from the surface oligonucleotide probes should be separated to be readily accessible for pairing with the target DNA strands. Thiol chemistry, adapted from the method of Whitesides and coworkers on the generation of monolayers on gold surfaces (Randall lee, T., Laibinis, P. E., Folkers, J. P. and Whitesides, G. M. (1991) Pure & Appl. Chem. 63: 821-828 and references cited therein.), is used for attachment of DNA to gold and platinum surfaces. Dithiols (e.g., 1,10-decanedithiol) provide a terminal, reactive thiol moiety for reaction with bromoacetylated oligonucleotides. The density of attachment of DNA to gold or platinium surfaces is controlled at the surface-activation stage, by use of defined mixtures of mono- and dithiols.
[0123] Part B: Surface Immobilization of Recombinant Vector DNA , cDNA and PCR Fragments
[0124] The chemical procedures described above are used most advantageously for covalent attachment of synthetic oligonucleotides to surfaces. For attachment of longer chain nucleic acid strands to epoxysilanized glass surfaces, the relatively slow reaction of surface epoxy groups with ring nitrogens and exocylic amino groups along the long DNA strands is employed to achieve immobilization. Through routine experimentation, optimal conditions for immobilization of unmodified nucleic acid molecules at a few sites per target are defined, such that the bulk of the immobilized sequence remains available for hybridization. In the case of immobilization tonanochannels coated with platinum or gold, hexylamine groups are first incorporated into the target DNA using polymerization (PCR or random priming) in the presence of 5-hexylamine-dUTP, then a bromoacetylation step is carried out to activate the DNA for attachment to thiolated metal surfaces. Again, routine experimentation is employed (varying the dTTP/5-hexylamine-dUTP ratio and the attachment time) to define conditions that give reproducible hybridization results.
[0125] The foregoing procedure (omitting the bromoacetylation step) can also serve as an alternative method for immobilization of target DNA to glass surfaces.
[0126] Part C: DNA Binding Capacity
[0127] Based upon quantitative measurements of the attachment of labeled oligonucleotides to flat glass and gold surfaces, the end attachment places the probes 50-100 Å apart on the surface, corresponding to up to 10 8 probes in a 50 μm×50 μm area. Approximately 10 10 -10 11 oligonucleotide probes can be tethered within a 50 μm cube of porous silicon in the nanofabricated wafer. The density of bound oligonucleotides per cross sectional area is estimated by end-labeling prior to the attachment reaction, then quantitating the radioactivity using the phosphorimager. Known quantities of labeled oligonucleotides dried onto the surface are used to calibrate the measurements of binding density. From data on the covalent binding of hexylamine-bearing plasmid DNA to epoxysilanized flat glass surfaces in mild base, it is known that at least 10 7 pBR322 molecules can be attached per mm 2 of glass surface. Based on this density within the pores of the nanofabricated wafer, immobilization of 10 9 -10 10 molecules of denatured plasmid DNA per mm 2 of wafer cross section are achieved.
EXAMPLE 8
Hybridization Conditions
[0128] Part A: Sample Preparation
[0129] The target DNA (analyte) is prepared by the polymerase chain reaction, incorporating [ 32 P]nucleotides into the product during the amplification or by using gamma- 32 P[ATP]+polynucleotide kinase to 5′-label the amplification product. Unincorporated label is removed by Centricon filtration. Preferably, one of the PCR fragments is 5′-biotin-labeled to enable preparation of single strands by streptavidin affinity chromatography. The target DNA is dissolved in hybridization buffer (50 mM Tris-HCl, pH 8, 2 mM EDTA, 3.3M tetramethylammonium chloride) at a concentration of at least 5 nM (5 fmol/μl) and specific activity of at least 5,000 cpm/fmol. PCR fragments of a few hundred bases in length are suitable for hybridization with surface-tethered oligonucleotides of at least octamer length.
[0130] Part B: Hybridization.
[0131] The target DNA sample is flowed into the porous regions of the chip and incubated at 6° C. for 5-15 minutes, then washed by flowing hybridization solution through the porous chip at 18° C. for a similar time. Alternatively, hybridization can be carried out in buffer containing 1M KCL or NaCl or 5.2M Betaine, in place of tetramethylammonium chloride. Part C: Optimization of Hybridization Selectivity (Discrimination Against Mismatch-Containing Hybrids
[0132] Although the experimental conditions described above generally yield acceptable discrimination between perfect hybrids and mismatch-containing hybrids, some optimization of conditions may be desirable for certain analyses. For example, the temperature of hybridization and washing can be varied over the range 5° C. to 30° C. for hybridization with short oligonucleotides. Higher temperatures may be desired for hybridization using longer probes.
EXAMPLE 9
Quantitative Detection of Hybridization
[0133] Part A: Phosphorimager and Film Detection
[0134] The detection and quantitation of hybridization intensities is carried out using methods that are widely available: phosphorimager and film. The Biorad phosphorimager has a sample resolution of about 100 μm and is capable of registering both beta emission and light emission from chemiluminescent tags. Reagent kits for chemiluminescence detection available from Millipore and New England Nuclear, which produce light of 477 and 428 nm, respectively, are advantageously used with the Biorad instrument. Chemiluminescent tags are introduced into the target DNA samples (random-primed vector DNA or PCR fragments) using the procedures recommended by the supplier. Thereafter, the DNA is hybridized to the nanoporous wafers bearing oligonucleotide probes. Radioactive tags ( 32 P and 33 P, incorporated by random priming and PCR reaction) are also used in these experiments. Film exposure is used for comparison. In the case of hybridization of labeled oligonucleotides with surface-immobilized target DNAs, most preferably the radioactive tags (incorporated using polynucleotide kinase) are used, since optimal chemiluminescent tagging procedures for oligonucleotides are generally not available.
[0135] Part B: CCD Detection Devices
[0136] CCD genosensor devices are capable of maximum resolution and sensitivity and are used with chemiluminescent, fluorescent and radioactive tags (Lamture, J. L., Varma, R., Fowler, R., Smith, S., Hogan, M., Beattie, K. L., Eggers, M., Ehrlick, D., Hollis, M. and Kosicki, B. 1993. Nature, submitted).
EXAMPLE 10
Genosensor Experiment; Mutation Detection in Exon 7/8 Region of Hamster hprt Gene
[0137] The hprt gene is used extensively as a model system for studies of mutation. The gene has been cloned and sequenced from several mammals. A variety of mutations in this gene are known and were characterized by DNA sequencing, in the hamster (induced by chemicals and radiation in Chinese Hamster Ovary cell lines) and from humans (associated with Lesch Nyhan syndrome). A significant fraction of hprt mutations are found in a short region of the gene encoded by exons 7 and 8. The nucleotide sequence of the normal and mutant genes are found in the following references: Edwards, A., Voss, H., Rice, P., Civitello, A., Stegemann, J., Schwager, C., Zinimermann, J., Erfle, H., Caskey, C. T. and Ansorge, W. (1990), Automated DNA Sequencing of the Human HPRT Locus, Genomics, 6:593-608; Gibbs, R., Nguyen, P.-N., Edwards, A., Civitello, A. and Caskey, C. T. (1990), Multiplex DNA Deletion Detection and Exon Sequencing of the Hypoxanthine Phosphoribosyltransferase Gene in Lesch-Nyhan Families, Genomics, 7:235-244; Yu, Y., Xu, Z, Gibbs, R. and Hsie, A. (1992), Polymerase chain reaction-based Comprehensive Procedure for the Analysis of the Mutation Spectrum at the Hypoxanthine-guanine Phosphoribosyltransferase locus in Chinese Hamster Cells, Environ. Mol. Mutagen., 19:267-273; and Xu, Z., Yu, Y., Gibbs, R., Caskey, C. T. and Hsie, A. (1993), Multiplex DNA Amplification and Solid-phase Direct Sequencing at the hprt Locus in Chinese Hamster Cells, Mutat. Res., 282:237-248. The nucleotide sequence of the cDNA of hamster hprt exon 7/8 region is listed as follows:
(SEQ ID NO: 1) 500 520 540 GCAAGCTTGC TGGTGAAAAG GACCTCTCGA AGTGTTGGAT ATAGGCCAGA CTTTGTTGGA 560 580 600 TTTGAAATTC CAGACAAGTT TGTTGTTGGA TATGCCCTTG ACTATAATGA GTACTTCAGG GATTTGAATC
[0138] The following represents the nucleotide sequence of hamster hprt genomic DNA in the exon 7/8 region where the CHO mutations are depicted above (l) and the human (h) and mouse (m) sequence differences below (l). The DNA sequence which begins with “5′-aacagCTTG” and which ends with “5′-GACTgtaag” is designated as SEQ ID NO:2 for sequences of hamster, human and mouse and SEQ ID NO:3 for the sequence of CHO cells. The remaining DNA, beginning with “5′-tacagTTGT” and ending with “GAATgtaat” is designated as SEQ ID NO:4 for sequences of hamster, human and mouse and SEQ ID NO:5 the sequence of CHO cells.
---------- ↑ -aacagCTTGCTGGTGAAAAGGACCTCTC GAAGTGTTGG ATATAGGCCAG ↓ ↓ ↓ ↓ C A C A h h m h G - ↑ ↑ ACTgtaag----tacagTTGTTGGATTTG A AATTCCAG A CAAGTTTGTTG +A C ↑ ↑ TTGGATATGCCCTTGACTAT AA TGAGTACTTCAG G ATTTGAATgt aat- ↓ ↓ ↓ A A A h h h
[0139] The small letters in the beginning of the sequence represent intron sequence on the 5′-side of exon 7. Some flanking intron sequence between exons 7 and 8 is shown (in small letters) on the second line, and at the end there is again a small stretch of intron sequence following exon 8. Underlined bases in the sequence represent mutations for which DNA samples are available, which can be used to demonstrate that a DNA chip targeted to this region can detect and identify mutations. Above the sequences are displayed mutations in hamster (CHO) cells induced by chemicals and radiation, including a 10-base deletion (top line), single base deletion (second line), single base insertion (third line) and single base substitutions (second and third lines). Below the sequences are shown single base differences between hamster and human (h) and mouse (m).
[0140] The set of oligonucleotide probes (of 8 mer-10 mer in length) overlapping by two bases across the exon 7/8 region is depicted below for SEQ ID Nos:2-5:
----2---- ----4---- ----6---- ----1---- ----3---- ----5---- --7-- -aacagCTTGCTGGTGAAAAGGACCTCTC GAAGTGTTGG ATATAGGCCAG ↓ ↓ ↓ ↓ ↓ C A -10 C A ----8----- ----10---- -12- -7- ----9----- ----11--- ACTgtaag----tacagTTGTTGGATTTG A AATTCCAG A CAAGTTTGTTG ↓ ↓ G - --12- ----14--- ----16---- ----18--- ----13--- ----15--- ----17--- TTGGATATGCCCTTGACTAT AA TGAGTACTTCAGG G ATTTGAATgtaat ↓ ↓ ↓ ↓ A +A A A C
[0141] This set of probes is selected to detect any of the mutations in this region, and the lengths are adjusted to compensate for base composition effects on in duplex stability (longer probes for AT-rich regions). The sequences of probes and primers are given in Table I, as follows:
TABLE I OLIGONUCLEOTIDES FOR hprt MUTATION DETECTION PCR primers for exons 7 & 8: Name Sequence (5-3) MHEX71 GTTCTATTGTCTTTCCCATATGTC (SEQ ID NO:6) MHEX82 TCAGTCTGGTCAAATGACGAGGTGC (SEQ ID NO:7) HEX81 CTGTGATTCTTTACAGTTGTTGGA (SEQ ID NO:8) HEX82 CATTAATTACATTCAAATCCCTGAAG (SEQ ID NO:9) 9mer with amine at 5′-end: Name Sequence (5′->3′) −A (554) TGCTGGAAT +A (586/7) ACTCATTTATA (SEQ ID NO: 10) −10 (509-518) TATATGAGAG (SEQ ID NO: 11) A-G (545) ATTCCAAATC (SEQ ID NO: 12) G-C (601) CAAATGCCT 1 AGCAAGCTG 2 TTTCACCAG 3 AGGTCCTTT 4 CTTCGAGAG 5 TCCAACACT 6 GCCTATATC 7 AGTCTGGC 8 TCCAACAACT (SEQ ID NO:13) 9 ATTTCAAATC (SEQ ID NO: 14) 10 GTCTGGAAT 11 ACAAACTTGT (SEQ ID NO: 15) 12 TCCAACAAC 13 GGGCATATC 14 TAGTCAAGG 15 ACTCATTATA (SEQ ID NO: 16) 16 CTGAAGTAC 17 CAAATCCCT 18 AATTACATTCA (SEQ ID NO: 17)
[0142] A high-density or ultra-high density microfabricated device according to the above examples is constructed and attachment of oligonucleotide probes is carried out within the bounded regions of the wafer. Included are the normal probes (1-18) plus the specific probes that correspond to five different known mutations, including the above mutations (sites 19 and 20, respectively). The foregoing uses two sets of PCR primers (Table I) to amplify the exons 7/8 region of hamster genomic DNA. A radioactive label ( 32 P) is incorporated into the PCR fragments during amplification, which enables detection of hybridization by autoradiography or phosphorimager. FIG. 5 illustrates the results when the above probes are attached at one end to the surface at specific test sites within the DNA chip (numbered as above). Idealized hybridization patterns for two of the mutants (10-base deletion on left and A-G transition on right) are shown at the bottom.
EXAMPLE 11
Profiling of Gene Expression Using cDNA Clones Arrayed in Porous Silicon
[0143] Part A: Fabrication of Porous Silicon Wafer
[0144] The procedure outlined in EXAMPLE 3 for fabrication of a porous silicon wafer with integral sample wells is followed, to yield a wafer with a 50×50 array of 200 μm square patches of pores, spaced 400 μm apart (center-to-center) over the surface of the wafer. The pores of the wafer are activated to bind amine-derivatized polynucleotides by reaction with epoxysilane, as described in EXAMPLE 4.
[0145] Part B: Formation of cDNA Array
[0146] A set of 2,500 M13 clones, selected from a normalized human cDNA library, is subjected to the polymerase chain reaction (PCR) in the presence of 5′-hexylamine-dUTP to amplify the cDNA inserts and incorporate primary amines into the strands. The PCR products are ethanol-precipitated, dissolved in water or 10 mM KOH, heat-denatured at 100° C. for 5 min., then quenched on ice and applied to individual sample wells of the porous wafer suing a Hamilton Microlab 2200 fluid delivery system equipped with an 8-needle dispensing head. After all cDNA fragments are dispensed, a slight vacuum is briefly applied from below to ensure that fluid has occupied the pores. Following incubation at room temperature overnight or at 60° C. for 30-60 minutes, the porous wafer is flushed with warm water, then reacted with 50 mM triethylamine to cap off the unreacted epoxy groups on the surface, then flushed again with warm water and air dried.
[0147] Part C: Preparation of Labeled PCR Fragments Representing the 3′-regions of Expressed Genes
[0148] Cytoplasmic RNA is extracted from cultured cells by the method of Chomczynski and Sacchi ( Anal. Biochem. 162:156-159 (1993)), treated with DNAse I to remove DNA contamination, then extracted with phenol/chloroform and ethanol precipitated. Reverse transcriptions and PCR are performed as described in the “differential display” protocol of Nishio et al. ( FASEB J. 8:103-106 (1994)). Prior to hybridization, PCR products are labeled by random priming in the presence of [A- 32 P]dNTPs, and unincorporated label is removed by Centricon filtration.
[0149] Part D: Hybridization of Expressed Sequences to cDNA Array
[0150] Prior to hybridization, a solution of 1% “Blotto” or 50 mM tripolyphosphate is flowed through the porous silicon wafer to minimize the nonspecific binding of target DNA, then the porous silicon array is washed with hybridization solution (50 mM Tris-HCl, pH 7.5, 1 mM EDTA, 1M NaCl). Labeled PCR fragments representing the 3′-end of expressed genes are recovered from the Centricon filtration units in hybridization buffer, and the entire porous wafer is flooded with this DNA solution. The porous hybridization module is placed at 65° C. and a peristaltic pump, connected to the lower vacuum chamber, is used to gradually flow the labeled DNA through the pores of the wafer over the course of 30-60 minutes. The porous wafer is washed three times with hybridization buffer at 65° C.
[0151] Part E: Quantitation of Hybridization Signals
[0152] Following hybridization and washing, the porous wafer is briefly dried, then placed onto the phosphor screen of a phosphorimager and kept in the dark for a period of time determined by the intensity of label. The phosphor screen is then placed into the phosphorimager reader for quantitation of individual hybridization signals arising from each porous region in the array.
[0153] FIG. 6 illustrates results obtainable from a hybridization experiment. Total cytoplasmic mRNA is isolated from cells cultured under two conditions and subjected to the “differential display” procedure described above to prepare fragments representative of individual mRNA species present under the two conditions. These samples are hybridized to two identical cDNA arrays, to yield the two hybridization signal patterns shown. These patterns represent the profile of expressed genes under the two different culture conditions (for example in the presence and absence of a drug or chemical that induces a change in the expression of some genes). Note that overall, the pattern of hybridization is similar for the two conditions, but as expected for a diffential expression of certain genes under the two conditions, there are a few hybridization signals that are seen only for culture condition 1 and a few that are seen only for culture condition 2. The box in the lower left, reproduced at the bottom of the figure to assist visual comparison, represents several differences in the gene expression profile. The squares represent sites where hybridization has occurred and the darkness of the squares is proportional to the number of labeled fragments present at each site. | 4y
|
PRIORITY CLAIM
[0001] The present disclosure claims benefit of U.S. Provisional Application No. 61/368,846 filed on Jul. 29, 2010, PCT Application No. PCT/US2011/024699 filed on Feb. 14, 2011 and is a continuation of U.S. patent application Ser. No. 13/812,959 filed on Jan. 29, 2013, for “ELECTRICITY GENERATING SHOCK ABSORBERS,” the entire contents and disclosure of which, are expressly incorporated by reference herein as if fully set forth herein.
TECHNICAL FIELD
[0002] The present disclosure is generally related to energy recovery. Specifically, the present disclosure is related to regenerative suspension systems.
BACKGROUND
[0003] Among all the sources of pollutants in the atmosphere, the transportation industry generally is a significant contributor. For example, in the United States, the transportation industry consumes a majority of the crude oil, much of which is used by automobiles. Hence, any advances in energy efficiency, especially in the transportation industry, may correspondingly lead to reduction in energy consumption, which not only cumulatively decreases energy costs, but also cumulatively contributes to a greener environment and greater energy independence and security.
[0004] Increasing demand for better fuel economy has led to improvements and developments in hybrid vehicles, electric vehicles and vehicles powered by fuel cells or diesel fuel. Efforts on the part of the automotive industry to increase fuel economy have included, but are not limited to, reductions in vehicle mass, improved aerodynamics, active fuel management, direct injection engines, homogeneous charge compression ignition engines and hybrid engines. Still, other mechanisms, techniques and energy sources that will improve fuel economy are continually being sought.
[0005] Currently, about 10 to 16% of the available fuel energy is used to drive an automobile, overcoming the friction and drag force from the road and wind. Besides engine cycle efficiency, one important mechanism of energy loss in automobiles is the dissipation of kinetic energy during vehicle vibration and motion. In the past hundred years, the automotive industry has been working hard to dissipate the motion and vibration energy into waste heat by optimal design of braking and suspension systems and by employing active controls, such as anti-lock braking systems or active suspensions. During the past ten years, energy recovery from braking has achieved great commercial success in hybrid vehicles. However, regenerative vehicle suspensions, which have the advantage of continuous energy recovery, have generally not come into practice due to various factors, such as insufficient vibration control, unsatisfactory energy harvesting, prohibitive costs, high complexity, practical incompatibility and relative inefficiency.
[0006] In view of the foregoing, it would be desirable to provide a regenerative vehicle suspension technology that takes into account the aforementioned factors.
BRIEF SUMMARY
[0007] An exemplary embodiment of the disclosed technology is directed to an electricity generating shock absorber comprising: a coil assembly having a length of electrically conducting material wrapped around an outside perimeter, and along a length, of a hollow tube formed of electrically resistant material; a magnet unit formed of at least one annular axial magnet; a central shaft having a magnetic reluctance on which a plurality of the magnet units are mounted, the central shaft dimensioned for insertion through a central opening of the at least one annular axial magnet, the central shaft combined with the plurality of magnet units forming a magnet assembly dimensioned to slideably insert into a central cavity of the hollow tube; and a cylindrical shell having a first end attached to a terminal end of the magnet assembly, the cylindrical shell extending a length of the magnet assembly, the cylindrical shell having an inner diameter sized to slideably accommodate an outside diameter of the coil assembly.
[0008] An exemplary embodiment of the disclosed technology is directed to a method of manufacturing an electricity generating shock absorber, the method comprising: at least once, winding a coil around a hollow tube having an electrical resistance; stacking a first pair of permanent magnets on a shaft having a magnetic reluctance; adapting the stacked shaft to be moveable in relation to a hollow cavity of the hollow tube; attaching the shaft to a first base; separating the first pair of magnets between each other on the shaft by a first magnetically-permeable spacer; aligning the first pair of magnets with like-poles facing each other; and encapsulating at least a part of the wound coil via a concentric outer cylinder attached at one end to the first base.
[0009] An exemplary embodiment of the disclosed technology is directed to a method of using an electricity generating shock absorber for generating electricity, the method comprising: moving a magnet assembly in relation to a coil assembly, the coil assembly comprising: a coil at least once wound around a hollow tube having an electrical resistance and a hollow cavity, the magnet assembly comprising: a first pair of permanent magnets stacked on a shaft having a magnetic reluctance, the shaft attached to a first base, the first pair of magnets separated between each other on the shaft by a first magnetically-permeable spacer, the first pair of magnets aligned with like-poles facing each other; and a concentric outer cylinder encapsulating at least a part of the coil assembly, the cylinder attached at one end to the first base.
[0010] An exemplary embodiment of the disclosed technology is directed to electricity generating shock absorber comprising: a first case comprising: a rack attached to the inner surface of the first case; and a second case comprising: a pinion in contact with the rack and attached to the inner surface of the second case via a first shaft mounted on a first base, a bevel gear box comprising a first and second bevel gear in contact with each other, the first bevel gear mounted on the first shaft, the second gear mounted on a second shaft coupled via a coupler to a rotational motor attached to the inner surface of the second case.
[0011] An exemplary embodiment of the present invention is directed to a method for generating electricity from mechanical vibrations, the method comprising: providing an electricity generating shock absorber having a magnet assembly including a first pair of magnets stacked horizontally along a shaft constructed of magnetic reluctant material and a coil assembly including a coil wound around a hollow tube having an electrical resistance, the first pair of magnets aligned with like-poles facing each other, the first pair of magnets, an insertion end of the magnet assembly being slidably inserted into an open end of the hollow tube of the coil assembly, a concentric outer cylinder encapsulating at least a part of the coil assembly, the cylinder attached at a base end of the magnet assembly opposite the insertion end; coupling a closed end of the hollow tube to a first mass; coupling the base end of the magnet assembly to a second mass, the electricity generating shock absorber providing vibration dampening between the first mass and the second mass; inducing relative motion between the magnet assembly and the coil assembly to generate electromotive voltage in the coil; and capturing the electromotive voltage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The objects, features and advantages of the disclosed technology will become apparent to a skilled artisan in view of the following detailed description taken in combination with the attached drawings, in which:
[0013] FIG. 1 a symbolically illustrates an exemplary embodiment of a linear electromagnetic shock absorber;
[0014] FIG. 1 b symbolically illustrates a cross-section view of an exemplary embodiment of a magnet assembly;
[0015] FIG. 2 symbolically illustrates an exemplary embodiment of a single layer electricity generating shock absorber with radial magnets;
[0016] FIG. 3 symbolically illustrates an exemplary embodiment of a double layer electricity generating shock absorber;
[0017] FIG. 4 symbolically illustrates an exemplary embodiment of a gear-based electricity generating shock absorber; and
[0018] FIG. 5 symbolically illustrates an alternative arrangement of the magnets of the electromagnetic embodiments of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] As used herein, a vehicle is a device that is designed or used to transport people or cargo. Vehicles may be land-based, such as automobiles, buses, trucks, trains, or marine-based, such as ships, boats, or aeronautical, such as airplane, helicopter, spacecraft.
[0020] As used herein, a shock absorber is an energy dissipating device generally used in parallel with the suspension spring to reduce the vibration generated by surface irregularities or during acceleration and braking
[0021] While, for simplicity and clarity, the following description of the figures is described in reference to land-based vehicles, the disclosed technology is not limited to land-based vehicles. Rather, the disclosed technology may be implemented and used with any device that is designed or used to transport people or cargo.
[0022] FIG. 1 a symbolically illustrates an exemplary embodiment of a linear electromagnetic shock absorber and FIG. 1 b symbolically illustrates a cross section view of an exemplary embodiment of a magnet assembly.
[0023] As shown in FIG. 1 a, a regenerative shock absorber 100 is in a configuration of a linear induction generator. In an exemplary embodiment, shock absorber 100 includes a magnet assembly 110 moveable in relation to a coil assembly 120 . In an exemplary embodiment, shock absorber 100 includes a coil assembly 120 movable in relation to a magnet assembly 110 . In an exemplary embodiment, magnet assembly 110 and coil assembly 120 are both movable in relation to each other.
[0024] In an exemplary embodiment, shock absorber 100 works in two cycles—a compression cycle and an extension cycle. In an exemplary automotive implementation where coil assembly 120 is attached to an automobile's frame and magnet assembly 110 is attached to the automobile's suspension system, the compression cycle occurs as coil assembly 120 moves downward and the extension cycle occurs as magnet assembly 110 moves upward (the relative movement of the coil and magnet assemblies 110 and 120 may be different upon a different configuration). Thus, if the compression cycle controls the motion of the vehicle's unsprung weight, then extension controls the motion of the heavier, sprung weight. Consequently, via alternation of cycles, due to, for example, road irregularities or during acceleration and braking, shock absorber 100 converts a kinetic energy of suspension vibration between an automobile wheel and a sprung mass into useful electrical power, as further described below.
[0025] In an exemplary embodiment, magnet assembly 110 is composed of ring-shaped, i.e. annular, permanent magnets 111 separated by ring-shaped high magnetically permeable spacers 114 stacked on a shaft 113 of high reluctance material. In an exemplary embodiment, the material is aluminum. In an exemplary embodiment, magnets 111 are rare-earth permanent magnets. In an exemplary embodiment, spacers 114 are steel spacers. In an exemplary embodiment, magnet assembly includes 12 magnets 111 and 13 spacers 114 .
[0026] As illustrated in FIG. 1 b, magnets 111 are arranged with like-poles of adjacent magnets 111 facing each other to redirect a magnetic flux in a radial direction. A concentric outer cylinder 112 made of high magnetically permeable material is used to protect the coils and reduce the reluctance of magnetic loops, to further increase magnetic flux density in the coils i.e. in order to further “pull” the magnetic flux outward.
[0027] Coil assembly 120 is composed of coils 121 wound around a tube 122 having a high electrical resistance. In an exemplary embodiment, coils 121 are composed of copper and tube 122 is composed of polyoxymethylene. In an exemplary embodiment, the height of one coil is equal to half of the total height of magnet 111 and spacer 114 . In an exemplary embodiment, coils 121 align with magnet assembly 110 . In an exemplary embodiment, the total number of coils 121 is 16 . In an exemplary embodiment, coils 121 are connected to a rectifier set-up.
[0028] In an exemplary embodiment, power generated in shock absorber 100 is related to the total volume of coils 121 . However, voltage is related with the winding of coils 121 around tube 122 . In an exemplary embodiment where the total volume of coils 121 is constant and coils 121 with a small diameter are used, then more windings of coils 121 are expected, thus generating a higher voltage. In an exemplary embodiment, coils 121 are wound in a range between 250 and 300 turns, which generates about 10V of output voltage.
[0029] In an exemplary embodiment, all the coils together will form a four-phase design where the 0 degree and 180 degree phases generate maximum positive and negative voltages and the 90 degree and 270 degree phases have zero voltage. Although the voltage or power of each phase may depend on the relative position of coil assembly 120 in the magnetic field, the total power generation does not. As coils 121 vibrate in relation to the magnetic field created by magnet assembly 110 , an electromotive force is generated, thus producing electricity. Also, the electromotive force serves as a damping force to reduce the vehicle vibration. In an exemplary embodiment, shock absorber 100 maintains a constant performance of power generation for movement (compression and extension cycles) between about 2 to about 4 inches.
[0030] For example, when shock absorber 100 is placed in an automobile suspension system, vibrations in the suspension system, due to road irregularities or during acceleration and braking, cause the coil assembly 120 to move in relation to the magnetic assembly 110 i.e. compression and extension cycles, thus generating an electromotive force, which can then be used to recharge the automobile's battery. In an exemplary embodiment, the peak output voltage is inversely proportional to the square of coils 121 diameter and the peak power depends on the total volume of conducting material in the coils.
[0031] FIG. 2 symbolically illustrates an exemplary embodiment of a single layer electricity generating shock absorber, where radial magnets are used to increase the magnetic flux density.
[0032] In an exemplary automotive implementation, shock absorber 200 converts a kinetic energy of suspension vibration between a wheel and a sprung mass into useful electrical power. In an exemplary embodiment, shock absorber 200 includes a magnet assembly 210 movable in relation to a coil assembly 220 in direction V. In an exemplary embodiment, shock absorber 200 includes a coil assembly 220 movable in relation a magnet assembly 210 in direction V. In an exemplary embodiment, magnet assembly 210 and coil assembly 220 are both movable in relation to each other.
[0033] In an exemplary embodiment, magnet assembly 210 is composed of radial magnets 211 . a and axial magnets 211 . b stacked on a shaft 213 of high reluctance material. In an exemplary embodiment, the material is aluminum. In an exemplary embodiment, the magnets are rare-earth permanent magnets. In an exemplary embodiment, shaft 213 is attached to a first base 224 . In an exemplary embodiment, a first mounting ring 215 is attached to first base 224 . In an exemplary embodiment, mounting ring 215 connects to an axle, near an automotive wheel, i.e., the unsprung weight.
[0034] As further exemplarily illustrated in FIG. 2 , radial magnets 211 . a and axial magnets 211 . b are arranged with like-poles of adjacent magnets 211 . a and 211 . b facing each other to redirect a magnetic flux in clockwise and counter-clockwise directions 216 . In an exemplary embodiment, a concentric outer cylinder 212 made of high magnetically permeable material is used to protect the coils and reduce the reluctance of magnetic loops, to further increase magnetic flux density in the coils i.e. in order to further “pull” the magnetic flux outward.
[0035] Coil assembly 220 is composed of coils 221 wound around a tube 222 having a high electrical resistance. In an exemplary embodiment, coils 221 are composed of copper and tube 222 is composed of polyoxymethylene. In an exemplary embodiment, tube 222 is connected to a second base 225 . In an exemplary embodiment, a second mounting ring 223 is attached to second base 225 . In an exemplary embodiment, second mounting ring 223 connects to an automobile frame, i.e., the sprung weight. In an exemplary embodiment, coils 221 are connected to a rectifier set-up.
[0036] For example, when shock absorber 200 is placed in an automobile suspension system, vibrations in the suspension system, due to road irregularities or during acceleration and braking, cause the coil assembly 220 to move in relation to the magnetic assembly 210 i.e. compression and extension cycles, thus generating an electromotive force, which can then be used to recharge the automobile's battery. In an exemplary embodiment, the relative motion generates alternating current (“AC”). The generated AC passes through a rectifier and via a rectification process gets converted to direct current (“DC”). Subsequently, a power converter, such as a DC to DC converter, is used to maintain a suitable voltage for charging a typical automobile battery. In an exemplary embodiment, shock absorber 200 harvests between about 2 to about 8 W of energy at 0.25-0.5 m/s RMS suspension velocity, which charges a typical car battery in about 7.5 hours.
[0037] FIG. 3 symbolically illustrates an exemplary embodiment of a double layer electricity generating shock absorber.
[0038] In an exemplary automotive implementation of the disclosed technology, shock absorber 300 converts a kinetic energy of suspension vibration between a wheel and a sprung mass into useful electrical power. In an exemplary embodiment, shock absorber 300 includes a magnet assembly 310 moveable in relation to a coil assembly 320 in direction V. In an exemplary embodiment, shock absorber 300 includes a coil assembly 320 movable in relation to a magnet assembly 310 in direction V. In an exemplary embodiment, magnet assembly 310 and coil assembly 320 are both movable in relation to each other.
[0039] In an exemplary embodiment, magnet assembly 310 is composed of double layers (inner and outer) of radial magnets 311 . a and axial magnets 311 . b stacked on a shaft 313 of high reluctance material. In an exemplary embodiment, the material is aluminum. In an exemplary embodiment, the magnets are rare-earth permanent magnets. In an exemplary embodiment, shaft 313 is attached to a first base 324 . In an exemplary embodiment, a first mounting ring 315 is attached to first base 324 . In an exemplary embodiment, mounting ring 315 connects to an axle, near an automotive wheel, i.e., the unsprung weight.
[0040] Double layers of radial magnets 311 . a and axial magnets 311 . b are arranged with like-poles of adjacent magnets 311 . a and 311 . b facing each other to redirect a magnetic flux in clockwise and counter-clockwise directions 316 . In an exemplary embodiment, as coils 321 vibrate in relation to and between double layers of radial magnets 311 . a and axial magnets 311 . b , a magnetic flux, which has increased power density over an exemplary embodiment described in FIGS. 2 a and 2 b , is generated. In an exemplary embodiment, a concentric outer cylinder 312 made of high magnetically permeable material is used to protect the coils and reduce the reluctance of magnetic loops, to further increase magnetic flux density in the coils i.e. in order to further “pull” the magnetic flux outward.
[0041] Coil assembly 320 is composed of coils 321 wound around a tube 322 having a high electrical resistance. In an exemplary embodiment, coils 321 are composed of copper and tube 322 is composed of polyoxymethylene. In an exemplary embodiment, the polyoxymethylene tube is connected to a second base 325 . In an exemplary embodiment, a second mounting ring 323 is attached to second base 325 . In an exemplary embodiment, second mounting ring 323 connects to an automobile frame, i.e., the sprung weight. In an exemplary embodiment, coils 321 are connected to a rectifier set-up.
[0042] For example, when shock absorber 300 is placed in an automobile suspension system, vibrations in the suspension system, due to road irregularities or during acceleration and braking, cause the coil assembly 320 to move in relation to the magnetic assembly 310 i.e. compression and extension cycles, thus generating an electromotive force, which can then be used to recharge the automobile's battery.
[0043] Alternatively, the arrangement of radial and axial magnets, shown in FIGS. 2 a , 2 b and 3 , are arranged as shown in FIG. 5 . Specifically, radial rare-earth magnets 502 are dimensioned to be thinner than the radial magnets disclosed above with respect to FIGS. 2 a , 2 b and 3 . Spacers 504 , constructed of a material having high magnetic permeability such as iron, are stacked onto the radial rare-earth magnets 502 so that the stacked assembly of the radial rare-earth magnet 502 and the spacer 504 has the same height as adjacent axial magnets 506 . In other words, the annular radial magnet 502 includes an inlayed spacer 504 , having an annular shape. The cross-sectional aspect of the combination of radial magnet 502 and spacer 504 is identical to the cross-sectional aspect of the axial magnet 506 in that the central opening diameter and the outside diameter of the combined radial magnet 502 and spacer 504 is the same as the respective diameters of the axial magnet.
[0044] The radial rare-earth magnets 502 , Axial magnets 506 and spacers 504 are positioned between an aluminum shaft 508 and linearly disposed coils 510 similar to the arrangement shown in FIGS. 2 a and 2 b . Moreover, in the double layer embodiment of FIG. 3 , the radial rare-earth magnets in both layers can be replaced with the stacked assembly shown in FIG. 5 .
[0045] The stacked assembly of the radial rare-earth magnet 502 and the spacer 504 , shown in FIG. 5 , advantageously similar or even higher magnetic density than a full height radial rare-earth magnet at a significantly reduced cost. The advantages are obtained because iron has a greater permeability than rare-earth materials, such as NdFeB, used for rare-earth permanent magnets. Moreover, iron is significantly less expensive than rare-earth permanent magnets. Thus, a cost savings can be realized by using smaller dimensioned radial rare-earth magnets 502 with the spacers 504 over using full height radial rare-earth magnets in the configurations shown in FIGS. 2 a , 2 b and 3 .
[0046] FIG. 4 symbolically illustrates an exemplary embodiment of a gear-based electricity generating shock absorber. Shock absorber 400 includes an outer case 410 and an inner case 410 .
[0047] In an exemplary embodiment, outer case 410 includes a toothed rack 413 attached to inner surface of outer case 410 via a first base 412 . A first mounting ring 411 is attached to an outer surface of outer case 410 .
[0048] In an exemplary embodiment, inner case 420 includes a toothed pinion 424 , which is mounted near a first end of a first shaft 423 , engaging rack 413 for converting linear motion into rotational motion. Hence, since vehicle vibration is periodic linear motion, the vibration is converted into rotational motion via the movement of rack 413 up to the limit of its travel, against pinion 424 , causing pinion 424 to rotate on its axis. First end of first shaft 423 is attached to a base 422 mounted on inner surface of inner case 420 .
[0049] In an exemplary embodiment, a bevel gear 425 . a engages a bevel gear 425 . b within a bevel gearbox 429 . Bevel gear 425 . a is mounted on a second end of first shaft 423 . Bevel gear 425 . b is mounted on a second end of a second shaft 426 attached to a rotational motor 428 . As bevel gear 425 . a transfers rotational motion from rack 413 and pinion 424 to bevel gear 426 . b , rotational motor 428 is driven via a rotation of second shaft 426 about its axis. A coupler 427 attaches motor 428 to second shaft 426 . A second mounting ring 421 is attached to an outer surface of inner case 420 .
[0050] In an exemplary embodiment, when rotational motor 428 is driven by rack 413 and pinion 424 via bevel gear 425 . a and 425 . b , rotational motor 428 generates a back electromotive force, thus producing electricity. While in the typical shock absorber, the electromotive force acts as the damping force as the vibration is mitigated by dissipating the vibration energy into heat, shock absorber 400 vibration is mitigated by dissipating the vibration energy into electric energy.
[0051] Exemplary embodiments of electricity generating shock absorbers maintain or enhance the required suspension damping performance and provide an effective way to adjust the suspension damping according to driver need or road conditions. Furthermore, the vibration mitigation performance is maintained or enhanced since the electricity-generating shock absorbers can provide back electromagnetic force, acting as the damping or control force. Also, exemplary embodiments of electricity generating shock absorbers enable energy harvesting in a typical passenger vehicle estimated to be on the same order of scale as a vehicle alternator as under normal driving conditions. Moreover, the generated power can be used to charge a battery, power the electrical accessories, such as lights or radio, or drive the wheels of a hybrid vehicle.
[0052] Further, exemplary embodiments of electricity generating shock absorbers enable an easy implementation of regenerative active suspension: a combination of energy harvesting and active suspension control. Additionally, exemplary embodiments of electricity generating shock absorbers are retrofittable, which means it can be used for new cars, or just to replace the traditional viscous shock absorber in the existing cars.
[0053] It should further be known that the present invention is not limited to application in motor vehicles. Rather, the electricity generating shock absorber can be advantageously utilized in any application where sufficient vibrational forces are present to operate the shock absorbers. In all embodiments, the electricity generating shock absorbers of the present invention are intended to be properly sized to accommodate the loads and forces experienced by the electricity generating shock absorbers in the particular application. Thus, any specific values provided in the disclosure above, are intended for illustrative convenience only and should not be taken as the full range of values acceptable for implementing the present invention.
[0054] In contrast to other regenerative shock absorbers, exemplary embodiments of electricity generating shock absorbers have high energy density, low weight and good compactness. Unlike ball-screw based systems, exemplary embodiments of electricity generating shock absorber also have little interference with vehicle dynamics. | 4y
|
BACKGROUND OF THE INVENTION
This invention was made in the course of, or under, a contract with the Energy Research and Development Administration.
Many toroidal plasma producing devices can be characterized in terms of two main magnetic fields, toroidal and poloidal, oriented orthogonally, that combine to form a resultant helical magnetic field, wherein the plasma produced in the device is a diffuse toroidal column confined on a nested complex of magnetic surfaces composed of the helical magnetic field lines.
In these devices, the toroidal component is set up by a circular array of coils known as the toroidal field coils (or simply TF coils) that are distributed around the toroidal plasma chamber. The poloidal component in these devices comes from a toroidal electric current that flows inside the plasma column itself and coils wound in the toroidal direction. This plasma toroidal current is created by a toroidal electric field produced by a transformer which consists of a set of primary windings that were wrapped around an external iron core and yoke, and the plasma current itself constitutes the single-turn secondary winding of the transformer. The primary windings are also known as the primary ohmic heating (primary-OH) windings.
Without the toroidal electric current, the plasma cannot be maintained in equilibrium in the toroidal magnetic field. In the presence of the toroidal current, however, equilibrium becomes possible. Expansion in the direction of the major radius is restricted by the effects of either a conducting shell surrounding the plasma or by another set of windings that produce what is known as the equilibrium magnetic field or vertical field (VF). Even when a conducting shell is sufficient to prevent the plasma expansion, a VF winding is still used for precise control of the position of the plasma column.
The poloidal field system will be understood herein to include the components for producing the equilibrium field in addition to those for initiating and driving the main plasma current. A number of poloidal systems are now in use or planned worldwide, and they represent a variety of design philosophies. It is convenient to group these alternative designs according to whether an iron core or an air core is used. The traditional choice for the poloidal system is an iron core because air cores have servere stray magnetic field problems not present in iron core designs. In iron core systems the stray magnetic flux is channeled into an iron yoke.
If an unsaturated iron core is present, the primary windings may be wrapped directly on the iron core. Alternatively, they may be closely wrapped near the plasma to reduce the stored magnetic energy in which case they will also shield the TF coils from stray magnetic flux. In some machines, the leakage flux from the primary winding is used to provide part of the equilibrium vertical field. For air core machines, the primary windings may be either wrapped inside or outside of the toroidal field coils.
With regard to the production of the vertical magnetic field in either iron or air core machines, the equilibrium vertical field was provided in all the earlier devices by eddy currents in a conducting shell and this was supplemented by externally-driven vertical field windings. More recently, machines without a conducting shell have been operated successfully, thereby making the use of a shell not necessarily essential.
In order to produce a large hot plasma having a high plasma current in one of these toroidal devices and thereby produce a copious quantity of neutrons, it will probably be necessary to provide superconducting coils for the confining toroidal magnetic field. This is in order to minimize electrical power dissipation in the coils.
An iron core system is not desirable because, for toroidal coils of a given bore, it is desirable to minimize the major radius. This, however, restricts the area available for an iron core. Iron saturates at approximately 16-16 kilogauss, so by restricting the amount of iron, the available volt-seconds value is limited. Since the volt-seconds requirement for a large device is very imprecise, there is considerable doubt that an iron core can provide sufficient volt-seconds for a high plasma current machine. A less important objection is that a back-biased iron core only stores a small amount of energy, meaning that the inductively stored energy is less than an air core design can provide.
To counter these problems, an air core transformer is used. The primary windings in such a system are run at full reverse current before the plasma discharge is initiated. An air core system thus has the advantage of providing a large inductive energy stored for initiating the plasma discharge. On the other hand, it has a much larger total energy requirement than an equivalent iron core system.
Air core systems in the past have not had to contend with superconducting TF windings. Instead, cooled copper toroidal coils, not subject to quenching due to stray magnetic fields, have been utilized. Specifically, these stray fields are pulsed fields that originate both in the windings that generate poloidal fields and from the changing plasma current, and they are especially prevalent during disruptive plasma instabilities.
Since rapidly changing poloidal fields may be utilized or required for plasma initiation in a large device, there exists a problem in that such changing fields can possibly quench the superconductors utilized in the magnetic coils. Other problems of stray fields in air core systems include the contribution of these fields to the stored energy requirements, particularly those that are required for the air core systems. It should also be noted that the use of an iron transformer is not desired or necessarily required in the operation of air core systems.
Thus, since the use of iron cores is not desirable, there exists a need to overcome the above-mentioned problems when an air core system is used in a large device. The present invention was conceived to meet this need in a manner to be described hereinbelow.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide an air core poloidal magnetic system for a plasma producing device of toroidal configuration that meets the demand for a large transformer flux swing to drive large, extended plasma current pulses in the presence of a limited central core area, to shield the superconducting toroidal field coils of the device from stray pulsed fields, and to reduce the stored energy requirements.
The above object has been accomplished in the present invention by providing an air core primary-OH winding for driving the plasma current, a shield-VF winding, and a decoupling winding; all arranged and operated in a unique fashion. The air core primary winding is located outside the superconducting TF coils and provides the principal plasma driving voltage. Its windings are distributed so that its magnetic flux does not intersect the TF coils. The shield-VF winding is closely coupled to the plasma inside the TF coils and consists of a distribution of series-connected conductors that approximately reproduce the eddy current distribution of a closed conducting shell. The shield-VF winding is connected in series with the decoupling winding that has an equal but opposite number of turns, and the decoupling winding is located with the primary winding so as to generate the same magnetic field pattern as the primary winding. The shield-VF winding provides the shielding function for the TF coils and in addition serves to produce the equilibrium vertical field. The shield coil can provide for precise plasma centering at a particular value of plasma pressure. Alternatively, and perhaps preferably, a further set of coils, called vertical trim coils, that are located outside of the TF coils can be provided to perform the centering function. The above coils can all be superconducting except the shield-VF coil, which is a cooled copper conductor, for example.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial schematic illustration of the poloidal magnetic field system of the present invention, and
FIG. 2 is a cut-away view of the invention implemented in a toroidal plasma producing device illustrating the arrangement of the various magnetic coils.
DESCRIPTION OF THE PREFERRED EMBODIMENT
A toroidal device for producing a hot plasma that illustrates the present invention is shown in FIG. 2 of the drawings. The device utilizes conventional toroidal field coils and an air core ohmic heating winding, and in accord with the present invention provides a shield winding and a decoupling winding arranged and operated in a unique manner to substantially reduce the amount of electrical energy normally required for air core transformers of the prior art, while at the same time shielding the toroidal field coils from poloidal magnetic flux in a manner to be described below.
In the device of FIG. 2, a blanket 4 encompasses the annular plasma volume, and a neutron shield 3 encompasses the blanket 4.
Encompassing the shield 3 are a plurality (20, for example) of toroidal field coils 2 and these field coils are oval in shape, for example. It should be understood that the device of FIGS. 1 and 2 is an example of one device in which the present invention may be utilized, and that the presence of a blanket and neutron shield are not necessary to the operation of the present invention.
It should be understood that the device of FIG. 2 may be provided with a plurality of injectors, not shown, for the injection of deuteron (neutral ions) into the toroidal annular plasma forming chamber.
Torus vacuum pumping for the device of FIG. 2 is provided by means of a plurality of cryosorption pumps, not shown, connected to the torus plasma containing chamber by means of associated 1 meter diameter ports, not shown.
An air core, ohmic heating primary winding W1 is provided for driving the plasma current and is located outside of the TF coils 2 (see also FIG. 1). A shield-VF winding W2 is closely coupled to the plasma inside the TF coils and consists of a distribution of series-connected conductors that approximately reproduce the eddy current distribution of a closed conducting shell. A decoupling winding W3 is also located outside of the TF coils 2 and is wound adjacent to the winding W1, as shown in FIGS. 1 and 2.
The shield-VF winding W2 is connected in series with the decoupling winding W3 that has an equal but opposite number of turns. Winding W3 is located with the primary-OH winding W1 so as to generate the same magnetic field pattern as the primary-OH winding W1. The shield-VF winding W2 provides the shielding function for the TF coils 2 and in addition serves to produce the equilibrium vertical field. The shield winding also provides plasma centering at a particular plasma pressure. Alternatively, and preferably, a further set of trim windings W4 that are located outside of the TF coils can perform this centering function, with only a small additional vertical field.
Any or all of the above coil windings may be superconducting except the shield-VF winding, which must be nonsuperconducting. The shield-VF winding is a cooled copper conductor coil, or alternatively a liquid metal conductor coil, for example. The shield-VF coil can be operated at cryoresistive temperatures if desired.
The main source of electromotive force for the plasma 5 is the air core ohmic heating winding W1 where the flux is returned externally by the air core winding W1 and supplies the principal volt-seconds capability of the device. For a large device of FIGS. 1 and 2, the magnetic field in the constricted midplane region of the torus due to W1 can reach several Tesla, allowing a much larger flux swing than would be possible with an iron core device. The primary winding W1 is driven by a V1 power circuit 9 as illustrated in FIG. 1.
The winding W2 is wrapped inside the toroidal field coils 2 in a closely-coupled fashion to the plasma 5. By means of a feedback control 7, as governed by a sensing coil 6, the total current flow in winding W2 is arranged to be equal and opposite to the plasma current in order to make the magnetic field outside winding W2 due to the plasma approximately zero, i.e., to cancel the poloidal magnetic field of the plasma at the toroidal field coils 2. The winding W2 is distributed in such a manner as to provide the equilibrium vertical field with the correct magnitude and decay index for the plasma.
The analogy of a closed perfectly-conducting shell gives a good demonstration of the winding W2's dual function. If a current is generated inside a conducting shell, eddy currents in the shell wall will prevent any plasma magnetic field from appearing outside the shell. Also, if the plasma shifts, eddy currents will generate a compensating vertical field. In practice, such a winding design is obtained by the superposition of two current distributions which require: (1) a winding with full plasma current that creates zero magnetic field in the plasma region, and (2) a vertical field winding with a total of zero ampere turns and having an optimal decay index for vertical and horizontal stability. The closeness of the winding W2 to the plasma allows flexibility in the choice of decay index. A value of 0.5, for example, gives good stability against plasma vertical displacements.
One effect of having a winding such as W2 in the poloidal magnetic system is that any voltage produced by a flux change in winding W1 would normally produce a current in winding W2. Therefore, the winding W3, which is closely wrapped to winding W1 has an equal and opposite number of turns as winding W2. Winding W3 is thus a decoupling winding, functioning to decouple the shield winding W2 from the ohmic heating driving voltage that is applied to W1. The winding W3 must have its currents distributed in the same fashion as winding W1 in order to create the same flux pattern. Windings W2 and W3 are connected in series with a V2 power circuit 8 so that winding W1 induces no net voltage in W2 and W3. Due to the locations of the respective windings, the plasma coupling to winding W2 is very good, and to winding W3 is very poor. Thus, the plasma current tends to keep an equal and opposite current to that in winding W2 (allowing for the turns ratio). To keep these currents exactly equal, a plasma current sensing circuit 6 measures the flux outside winding W2 and drives the power circuit 8 by means of the control 7 so as to keep the flux at zero. In other words, the V2 power circuit 8 maintains equality of the total plasma and shield-VF coil currents at a relatively low level of energy expenditure, aside from resistive losses. In steady operation, the plasma, W2, and W3 currents are constant and the W1 changing flux provides for the plasma resistive losses. The combination of the shield (W2) and decoupling (W3) coils can thus be viewed as an open resistive, conducting shell with a fixed current distribution providing a field free region between its surfaces.
In constructing the shield coil to exactly equal the plasma current for shielding purposes (shielding can only be complete when the shield coil current is equal and opposite to the plasma current), some of the plasma position stabilizing flexibility is sacrificed. To provide the remainder of the vertical field, a set of trimming VF windings W4 are wrapped around the torus, outside of the TF coils 2, and carry a net zero ampere-turns. The shielding and trim currents are separately controlled. The power circuits for the coils W4 are not shown in the drawings.
This added vertical field due to the trim coils W4 intersects the TF coils, but is nevertheless acceptable because it needs to change only slowly in time as the poloidal magnetic field pressure increases during the quasi-stationary phase of the plasma discharge. Whether or not the trim coils W4 are used depends on how perfectly one wants to cancel plasma effects with the shield VF coils.
As discussed above, the principal object of the present invention is to shield the toroidal field coils in a toroidal plasma producing device from stray pulsed magnetic fields, thus resulting in a substantial reduction in the total electrical energy requirements of the various magnetic systems of the device. A typical operating cycle for the various magnetic coils of the present invention is as follows:
1. Starting from zero current, the primary winding W1 is charged to full reverse current with zero current in the other windings W2, W3, and W4. This may take a number of seconds.
2. This reverse current is then driven toward full forward current with the V1 power circuit 9, inducing a current in the plasma but not directly in the shield VF (W2 winding) and decoupling circuit (W3 winding). The plasma current induces nearly equal and opposite amp-turns in the shield-VF coils W2, depending upon the relative coupling. The V2 power circuits 8 increases the current level in the shield (W2) and decoupling (W3) windings to that of the plasma. Most of the current in the shield winding is thus produced by induction from the plasma, and the magnetic flux external to the shield winding W2 is greatly reduced over conventional designs.
3. The primary-OH winding W1 voltage is changed at a suitable rate by the V1 supply to bring the plasma current to full value. During this time (up to a few seconds) the ohmic heating coil (W1) current rises to some fraction of its original value, but with the opposite sign. During the time the plasma is maintained, the primary-OH current increases slowly while supplying the plasma resistive losses. The current in the trim VF windings W4 is varied to keep the plasma centered. The shield (W2) and plasma currents are maintained in equality, since if they differ, undesired stray magnetic flux will appear.
4. A negative voltage is applied to the primary winding to drive the plasma current to zero.
The above cycle is repeated over and over again for as many cycles as is desired, and during each cycle when a hot plasma is being maintained in the torus vacuum chamber, there are produced a substantial number of neutrons directed at the wall of the vacuum chamber. Thus, the device has a utility as a neutron source.
It can be seen from the above described device that the arrangement of the various magnetic windings (W2, W3 and W4) with respect to the primary-OH winding W1 provides a system which is substantially capable of shielding the toroidal field coils of the device from stray magnetic flux. It has been determined that the above arrangement and operation of the windings W2, W3 and W4 should result in a reduction of at least a factor of 6 in the pulsed fields in the vicinity of the toroidal field coils compared to the field that the plasma alone would produce at the toroidal field coils.
This invention has been described by way of illustration rather than by limitation and it should be apparent that it is equally applicable in fields other than those described. For example it can find application in experimental research devices leading to the ultimate goal of producing controlled thermonuclear reactions. An example of one such device is described in the Oak Ridge National Laboratory Report: ORNL-TM-5042, dated November 1975. | 4y
|
This application is a continuation of application Ser. No. 07/341,320, filed Apr. 19, 1989, now U.S. Pat. No. 4,992,422.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to compositions comprising a physiologically-active agent and a 1-alkyl azacycloalkane, which may be substituted by sulfur pendant from the alpha carbon atom of the ring, in an amount effective to enhance the penetration of the physiologically-active agent through the skin or other membrane of the body of an animal.
2. Background of the Art
Many physiologically active agents are best applied topically to obtain desirable results. Topical application, as contrasted to systemic application, can avoid metabolic degradation of the agents, largely avoids side effects of the agents and permits high local concentrations of the agents.
The greatest problem in applying physiologically active agents topically is that the skin is such an effective barrier to penetration. The epidermis of the skin has an exterior layer of dead cells called the stratum corneum which is tightly compacted and oily and which provides an effective barrier against gaseous, solid or liquid chemical agents, whether used alone or in water or oil solutions. If a physiologically active agent penetrates the stratum corneum, it can readily pass through the basal layer of the epidermis and into the dermis.
Although the effectiveness of the stratum corneum as a barrier provides great protection, it also frustrates efforts to apply beneficial agents directly to local areas of the body. The inability of physiologically active agents to penetrate the stratum corneum prevents their effective use to treat such conditions as inflammation, acne, psoriasis, herpes simplex, eczema, infections due to fungus, virus or other microorganisms, or other disorders or conditions of the skin or mucous membranes, or of conditions beneath the exterior surface of the skin or mucous membranes. The stratum corneum also prevents the skin from absorbing and retaining cosmetic-type materials such as sunscreens, perfumes, mosquito repellants and the like.
Physiologically active agents may be applied to locally affected parts of the body through the vehicle system described herein. Vehicles such as USP cold cream, ethanol and various ointments, oils, solvents, and emulsions have been used heretofore to apply physiologically active ingredients locally. Most such vehicles are not effective to carry significant amounts of physiologically active agents through the skin. One such vehicle is dimethyl sulfoxide.
The 1-lower alkyl substituted azacyclopentan-2-ones having 1-4 carbon atoms in the alkyl group are known to moderately enhance percutaneous absorption of chemicals, e.g. drugs. It was earlier recognized that it would be desirable to obtain the same or higher level of percutaneous absorption with substantially lower concentrations of the penetration-enhancing compound. Therefore, a new class of N-substituted azacycloalkan-2-ones were invented having the desired properties. This new class of penetration-enhancing agents are described in U.S. Pat. Nos. 3,989,815; 3,989,816; 3,991,203; 4,122,170; 4,316,893; 4,405,616; 4,415,563; 4,423,040; 4,424,210; and 4,444,762, which are hereby incorporated by reference.
It is an object of this invention to provide new penetration-enhancing agents having the desirable property of enhancing the percutaneous absorption of physiologically-active agents at concentrations lower than the 1-lower alkyl substituted azacyclopentan-2-ones.
It is also an object of this invention to provide penetration-enhancing agents that are equivalent to the aforesaid new class penetration-enhancing agents described in the above U.S. patents.
Other objects and advantages of the instant invention will be apparent from a careful reading of the specification below.
In this description, the term "animal" includes human beings as well as other forms of animal life, and especially domesticated animals and pets.
SUMMARY OF THE INVENTION
This invention relates to compositions for carrying physiologically active agents through body membranes such as skin and for retaining these agents in body tissues. More specifically, the invention relates to compositions useful in topically administering a physiologically active agent to a human or animal comprising the agent and an effective, non-toxic amount of a compound having the structural formula ##STR3## wherein X may represent sulfur or two hydrogen atoms; R' is H or a lower alkyl group having 1-4 carbon atoms; m is 2-6; n is 0-18 and R is --CH 3 , ##STR4## wherein R" is H or halogen.
Preferably R is --CH 3 and R' is H.
In a more preferred embodiment of the present invention R is --CH 3 , R' is H and m equals 4. Even more preferably n is 4-17, e.g. 11.
It has been found that the physiologically active agents are carried through body membranes by the above penetration-enhancing agents and are retained in body tissue.
The invention further relates to the penetration-enhancing agents themselves and their method of making.
DETAILED DESCRIPTION OF THE INVENTION
The N-alkyl substituted azacycloalkanes useful as penetration-enhancing additives in the compositions of the instant invention may be made by the methods described below. Typical examples of compounds represented by the above structural formula include:
1-n-Dodecylazacycloheptane,
1-n-Dodecylazacycloheptan-2-thione,
1-n-Butylazacyclohexan-2-thione,
1-n-Butylazacyclopentan-2-thione,
1-n-Octylazacyclopentan-2-thione,
1-n-Dodecylazacyclopentan-2-thione,
1-n-Butylazacycloheptan-2-thione,
1-n-Octylazacycloheptan-2-thione,
1,1'-Hexamethylenediazacyclopentan-2-thione,
1-n-Dodecylazacyclohexan-2-thione,
1-n-Decylazacycloheptane,
1-n-Hexadecylazacyclobeptane,
1-n-Octadecylazacycloheptane,
1-n-Undecylazacycloheptane,
1-n-Tetradecylazacycloheptane.
Certain of the compounds represented by the above general formula, wherein X represents two hydrogen atoms, may be prepared by reacting the corresponding azacycloalkan-2-one with lithium aluminum hydride. The reaction may be carried out under anhydrous conditions in an ether solvent, for example, diethyl ether at room temperature for about 5 hours in an inert atmosphere, for example, argon.
Any of the above compounds wherein X is sulfur may be made by reacting the corresponding oxygen compound with phosphorus pentasulfide.
The amount of 1-substituted azacycloalkane which may be used in the present invention is an effective, non-toxic amount for enhancing percutaneous absorption. Generally, this amount ranges between about 0.01 to about 5 and preferably about 0.1 to 2 percent by weight of the composition.
The subject compositions may find use with many physiologically active agents which are soluble in the vehicles disclosed.
Fungistatic and fungicidal agents such as, for example, thiabendazole, chloroxine, amphotericin B, candicidin, fungimycin, nystatin, chlordantoin, clotrimazole, miconazole nitrate, pyrrolnitrin, salicylic acid, fezatione, tolnaftate, triacetin and zinc and sodium pyrithione may be dissolved in the penetration-enhancing agents described herein and topically applied to affected areas of the skin. For example, fungistatic or fungicidal agents so applied are carried through the stratum corneum, and thereby successfully treat fungus-caused skin problems. These agents, thus applied, not only penetrate more quickly than when applied in the vehicles of the prior art, but additionally enter the animal tissue in high concentrations and are retained for substantially longer time periods whereby a far more successful treatment is effected.
For example, the subject compositions may also be employed in the treatment of fungus infections on the skin caused by candida and dermatophytes which cause athletes foot or ringworm, by dissolving thiabendazole or similar antifungal agents in one of the above-described penetration-enhancing agents and applying it to the affected area.
The subject compositions are also useful in treating skin problems, for example, herpes simplex, which may be treated by a solution of iododeoxyuridine dissolved in one of the penetration-enhancing agents or such problems as warts which may be treated with agents such as podophylline dissolved in one of the penetration-enhancing agents. Skin problems such as psoriasis may be treated by topical application of a solution of a conventional topical steroid in one of the penetration-enhancing agents or by treatment with theophylline or antagonists of β-adrenergic blockers such as isoproterenol in one of the penetration-enhancing agents. Scalp conditions such as alopecia areata may be treated more effectively by applying steroids such as triamcinolone acetonide dissolved in one of the penetration-enhancing agents of this invention directly to the scalp.
The subject compositions are also useful for treating mild eczema, for example, by applying a solution of fluocinolone acetonide or its derivatives; hydrocortisone, triamcinolone acetonide, indomethacin, or phenylbutazone dissolved in one of the penetration-enhancing agents to the affected area.
Examples of other physiologically active steroids which may be used with the vehicles include corticosteroids such as, for example, cortisone, cortodoxone, flucetonide, fluorocortisone, difluorsone diacetate, flurandrenolone acetonide, medrysone, amcinafel, amcinafide, betamethasone and its esters, chloroprednisone, clocortelone, descinolone, desonide, dexamethasone, dichlorisone, defluprednate, flucloronide, flumethasone, flunisolide, fluocinonide, flucortolone, fluoromethalone, fluperolone, fluprednisolone, meprednisone, methylmeprednisolone, paramethasone, preunisolone and preunisone.
The subject compositions are also useful in antibacterial chemotherapy, e.g. in the treatment of skin conditions involving pathogenic bacteria. Typical antibacterial agents which may be used in this invention include sulfonamides, penicillins, cephalosporins, penicillinase, erythromycins, lincomycins, vancomycins, tetracyclines, chloramphenicols, streptomycins, etc. Typical examples of the foregoing include erythromycin, erytbromycin ethyl carbonate, erythromycin estolate, erythromycin glucepate, erythromycin ethylsuccinate, erythromycin lactobionate, lincomycin, clindamycin, tetracycline, chlortetracycline, demeclocycline, doxycycline, methacycline, oxytetracycline, minocycline, etc.
The subject compositions are also useful in protecting ultra-sensitive skin or even normally sensitive skin from damage or discomfort due to sunburn. Thus, dermatitis actinica may be avoided by application of a sunscreen, such as para-aminobenzoic acid or its well-known derivatives dissolved in one of the above-described penetration-enhancing agents, to skin surfaces that are to be exposed to the sun; and the protective paraaminobenzoic acid or its derivatives will be carried into the stratum corneum more successfully and will therefore be retained even when exposed to water or washing for a substantially longer period of time than when applied to the skin in conventional vehicles. This invention is particularly useful for ordinary suntan lotions used in activities involving swimming because the ultraviolet screening ingredients in the carriers of the prior art are washed off the skin when it is immersed in water.
The subject compositions may also find use in treating scar tissue by applying agents which soften collagen, such as aminopropionitrile or penicillamine dissolved in one of the penetration-enhancing agents of this invention topically to the scar tissue.
Agents normally applied as eye drops, ear drops, or nose drops are more effective when dissolved in the penetration-enhancing agents of this invention.
Agents used in diagnosis may be used more effectively when applied dissolved in one of the penetration-enhancing agents of this invention. Patch tests to diagnose allergies may be effected promptly without scratching the skin or covering the area subjected to an allergen when the allergens are applied in one of the penetration-enhancing agents of this invention.
The subject compositions are also useful for topical application of cosmetic or esthetic agents. For example, compounds such as melanin-stimulating hormone (MSH) or dihydroxyacetone and the like are more effectively applied to skin to stimulate a suntan when they are dissolved in one of the penetration-enhancing agents of this invention. The agent is carried into the skin more quickly and in greater quantity when applied in accordance with this invention. Hair dyes also penetrate more completely and effectively when dissolved in one of the penetration-enhancing agents of this invention.
The effectiveness of such topically applied materials as insect repellants or fragrances, such as perfumes and colognes, can be prolonged when such agents are applied dissolved in one of the penetration-enhancing agents of this invention.
It is to be emphasized that the foregoing are simply examples of physiologically active agents including therapeutic and cosmetic agents having known effects for known conditions, which may be used more effectively for their known properties in accordance with this invention.
In addition, the penetration-enhancing agents of the present invention may also be used to produce therapeutic effects which were not previously known. That is, by use of the penetration-enhancing agents described herein, therapeutic effects heretofore not known can be achieved.
As an example of the foregoing, griseofulvin is known as the treatment of choice for fungus infections of the skin and nails. Heretofore, the manner of delivery of griseofulvin has been oral. However, it has long been known that oral treatment is not preferred because of side effects resulting from exposure of the entire body to griseofulvin and the fact that only the outer layers of affected skin need to be treated. Therefore, because fungal infections are generally infections of the skin and nails, it would be advantageous to utilize griseofulvin topically. However, despite a long-felt need for a topical griseofulvin, griseofulvin has been used orally to treat topical fungus conditions because there was not heretofore known any formulation which could be delivered topically which would cause sufficient retention of griseofulvin in the skin to be useful therapeutically.
However, it has now been discovered that griseofulvin, in a range of therapeutic concentrations between about 0.1% and about 10% may be used effectively topically if combined with one of the penetration-enhancing agents described herein.
As a further example, acne is the name commonly applied to any inflammatory disease of the sebaceous glands; also acne vulgaris. The microorganism typically responsible for the acne infection is Corynebacterium acnes. Various therapeutic methods for treating acne have been attempted including topical antibacterials, e.g. hexachlorophene, and systemic antibiotics such as tetracycline. While the systemic antibiotic treatments are known to be partially effective, the topical treatments are generally not effective.
It has long been known that systemic treatment of acne is not preferred because of side effects resulting from exposure of the entire body to antibiotics and the fact that only the affected skin need be treated. However, despite a long-felt need for a topical treatment for acne, antibiotics generally have been used only systemically to treat acne because there was not heretofore known an antibacterial formulation which could be used topically which would be effective therapeutically in the treatment of acne. However, it has now been discovered that antibiotics, especially those of the lincomycin and erythromycin families of antibiotics, may be used in the treatment of acne topically if combined with one of the penetration-enhancing agents described herein.
The antibiotics composition so applied is carried into and through the epidermis and deeper layers of the skin as well as into follicles and comedones (sebum-plugged follicles which contain C. acnes) in therapeutically effective amounts and thereby successfully may be used to temporarily eliminate the signs and symptoms of acne.
The term "physiologically active agent" is used herein to refer to a broad class of useful chemical and therapeutic agents including physiologically active steroids, antibiotics, antifungal agents, antibacterial agents, antineoplastic agents, allergens, antihistaminic agents, anti-inflammatory agents, ultraviolet screening agents,diagnostic agents, perfumes, insect repellants, hair dyes, etc.
Dosage forms for topical application may include solution nasal sprays, lotions, ointments, creams, gels, suppositories, sprays, aerosols and the like. Typical inert carriers which make up the foregoing dosage forms include water, acetone, isopropyl alcohol, freons, ethyl alcohol, polyvinylpyrrolidone, propylene glycol, fragrances, gel-producing materials, mineral oil, stearyl alcohol, stearic acid, spermaceti, sorbitan monooleate, "Polysorbates", "Tweens", sorbital, methyl cellulose, etc.
The amount of the composition, and thus of the physiologically active agent therein, to be administered will obviously be an effective amount for the desired result expected therefrom. This, of course, will be ascertained by the ordinary skill of the practitioner. Due to enhanced activity which is achieved, the dosage of physiologically active agent may often be decreased from that generally applicable. In accordance with the usual prudent formulating practices, a dosage near the lower end of the useful range of the particular physiologically active agent may be employed initially and the dosage increased as indicated from the observed response, as in the routine procedure of the physician.
The invention is further illustrated by the following examples which are illustrative of various aspects of the invention, and are not intended as limiting the scope of the invention as defined by the appended claims.
EXAMPLE 1
56.2 g (0.2 mol) of 1-dodecylazacycloheptan-2-one in 100 ml diethyl ether was added dropwise to a suspension of 7.6 g (0.2 mol) lithium aluminum hydride in 100 ml diethyl ether under argon at room temperature. After 5 hours of stirring, 20 ml saturated sodium sulfate was added dropwise. The mixture was filtered and the filtrate was dried with magnesium sulfate, filtered and concentrated. The resulting oil was distilled (130°/.03 mm) to yield 50.03 g (93.5%) of 1-n-dodecylazacycloheptane.
EXAMPLE 2
To a solution of 5 g (17.7 mmol) of 1-n-dodecylazacycloheptan-2-one in 150 ml of benzene was added 4.18 g (9.4 mmol) of phosphorus pentasulfide and the mixture was refluxed for 1 hr. After cooling to room temperature, the mixture was filtered and the solid was washed with chloroform and ethanol. The filtrate was concentrated in vacuo and the residue was subjected to flash chromatography, (silica; (95:5)V/V hexane/ethyl acetate) to give 2.11 g (40%) of 1-n-dodecylazacycloheptane-2thione.
EXAMPLE 3
The compounds of Examples 1 and 2 were tested as penetration enhancing agents according to the below procedure:
Skin from female hairless mice, 4-6 weeks old, was removed from the animal and placed over penetration wells with normal saline bathing the corium. A plastic cylinder 1.4 cm in diameter was glued onto each piece on the epidermal side. 0.1% triamcinolone acetonide 3 H was applied (0.01 cc) to the epidermal surface within the 1.4 cm diameter cylinder. The skin was incubated at room temperature and ambient humidity.
At 6 hours and 24 hours, 2 cc were removed from the 10 cc reservoir of normal saline bathing the corium. The 2 cc of normal saline removed were replaced after the 6 hour sample with 2 cc of normal saline.
The 2 cc aliquots were put into scintillation fluid and the radioactivity determined in a scintillation counter. The amount penetrating was calculated as per cent of dose applied.
In every experiment the 3 H triamcinolone acetonide was dissolved in ethanol and the penetration-enhancing agent to be tested was added to the desired concentration.
The controls were ethanol, alone, and 1-n-dodecylazacycloheptan-2-one, a compound described in the U.S. patents, noted above, as having superior penetration-enhancing properties. Five separate tests for each compound and the controls were made and the results averaged.
The results, as reported in the Table below, show that the compounds of Examples 1 and 2 have penetration-enhancing properties.
TABLE______________________________________Penetration-Enhancing Percent PenetrationAgent 6 hr. 24 hr.______________________________________Example 1 3.54 11.44Example 2 9.42 48.581-n-Dodecylcycloheptan-2-one 16.64 60.94Ethanol (only) 0.56 6.78Ethanol (only, repeat) 0.5 5.64______________________________________
As can be shown from the above results the compounds of Examples 1 and 2 have penetration-enhancing properties as compared to the ethanol control.
EXAMPLE 4
The following formulation is prepared:
______________________________________ Solution (%)______________________________________Griseofulvin 11-n-dodecylazacycloheptan-2-thione 1Isopropyl myristate 5Fragrance 0.1Ethanol 92.9______________________________________
This formulation is effective in the treatment of fungus infections.
EXAMPLE 5
An aerosol form of the formulation of Example 4 is prepared by preparing the following mixture:
______________________________________ Formulation 25% Freon.sup.1 75%______________________________________ .sup.1 Freon is 75/25 Freon 114/12.
EXAMPLE 6
The following cream formulation is prepared:
______________________________________ %______________________________________Clindamycin base 1.0Stearyl alcohol, U.S.P. 12.0Ethoxylated cholesterol 0.4Synthetic spermaceti 7.5Sorbitan monooleate 1.0Polysorbate 80, U.S.P. 3.01-n-Dodecylazacycloheptan-2-thione 0.5Sorbitol solution, U.S.P. 5.5Sodium citrate 0.5Chemoderm #844 Fragrance 0.2Purified water 68.4______________________________________
This formulation is effective in the treatment of acne.
EXAMPLE 7
The following solution formulations are prepared:
______________________________________ A (%) B (%)______________________________________Clindamycin base -- 1.0Clindamycin phosphate acid 1.3 --Sodium hydroxide 0.077 --1.0 M Hydrochloric acid -- 2.27Disodium edetate:2H.sub.2 O 0.003 0.003Fragrances 0.5 0.51-n-Dodecylazacycloheptan-2-thione 1.0 1.0Purified water 20.0 17.73Isopropanol 77.12 77.497______________________________________
These solutions are effective for the treatment of acne in humans.
EXAMPLE 8
The following solution formulation is prepared:
______________________________________ %______________________________________Neomycin sulfate 0.5Lidocaine 0.5Hydrocortisone 0.251-n-Dodecylazacycloheptan-2-thione 0.5Propylene glycol 98.25______________________________________
This solution is effective for the treatment of otitis in domestic animals.
EXAMPLE 9
The following sunscreen emulsion is prepared:
______________________________________ %______________________________________p-Aminobenzoic acid 2.0Benzyl alcohol 0.51-n-Dodecylazacycloheptan-2-thione 1.0Polyethylene glycol 500-MS 10.0Isopropyl lanolate 3.0Lantrol 1.0Acetylated lanolin 0.5Isopropyl myristate 5.0Light mineral oil 8.0Cetyl alcohol 1.0Veegum 1.0Propylene glycol 3.0Purified water 64.0______________________________________
EXAMPLE 10
The following antineoplastic solution is prepared:
______________________________________ %______________________________________5-Fluorouracil 5.01-n-Dodecylazacycloheptan-2-thione 0.1Polyethylene glycol 5.0Purified water 89.9______________________________________
EXAMPLE 11
The following insect repellant atomizing spray is prepared:
______________________________________ %______________________________________Diethyltoluamide 0.11-n-Dodecylazacycloheptan-2-thione 0.1Ethanol 99.8______________________________________
EXAMPLE 12
The following lotion formulation may be prepared containing about 0.001 to 1 percent, with preferably 0.1 percent fluocinolone acetonide:
______________________________________ %______________________________________Fluocinolone acetonide 0.001-1Cetyl alcohol 15.0Propylene glycol 10.0Sodium lauryl sulfate 15.01-n-Dodecylazacycloheptan-2-thione 1.0Water (to make 100%)______________________________________
The steroid is dissolved in the vehicle and added to a stirred, cooling melt of the other ingredients. The preparation is particularly useful for the treatment of inflamed dermatoses by topical application to the affected skin area. The amount and frequency of application is in accordance with standard practice for topical application of this steroid. Penetration of the steroid into the inflamed tissue is enhanced and a therapeutic level is achieved more rapidly and sustained for longer duration than when the steroid is applied in conventional formulations.
EXAMPLE 13
Examples 4-12 are repeated except that 1-n-Dodecylazacycloheptan-2-thione is replaced with the following penetration-enhancing agent:
1-n-dodecylazacycloheptane Comparable results are obtained.
While particular embodiments of the invention have been described it will be understood of course that the invention is not limited thereto since many obvious modifications can be made and it is intended to include within this invention any such modifications as will fall within the scope of the appended claims. | 4y
|
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. §119 to the following U.S. Provisional Patent Application, which is hereby incorporated by reference in its entirety: U.S. Ser. No. 61/474,504 filed on Apr. 12, 2011.
COPYRIGHT STATEMENT
[0002] A portion of the disclosure of this patent application document contains material that is subject to copyright protection including the drawings. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure as it appears in the Patent and Trademark Office file or records, but otherwise reserves all copyright rights whatsoever.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The present application relates to fastening means to a cord as a way of identifying ownership of the cord. The application also relates to the organizing or bundling of a cord.
[0005] 2. Description of the Prior Art
[0006] There are cord tagging and labeling devices available in the market, but none are configured to be customizable to reflect the personality, profession, characteristics, philosophy, education, loyalty, and other unique representations of the owner. In addition, the devices available on the market do not present inter-connectable customizable cord marking and/or organizing solutions in a simple unit. The present application seeks to address these concerns.
SUMMARY OF THE INVENTION
[0007] Illustrative embodiments of the present invention shown in the drawings are more fully described in the Detailed Description section. It is to be understood that there is no intention to limit the invention to the forms described in this Summary of the Invention or in the Detailed Description. One skilled in the art can recognize that there are numerous modifications, equivalents, and alternative constructions that fall within the spirit and scope of the invention as expressed in the claims.
[0008] The present invention can provide a system and method for identifying the ownership of a cord. One illustrative embodiment is a system for attaching a cord identifier to a cord, the system comprising a body having at least two deformable prongs that form a portion of a channel within the body. Additionally, a portion of the outer surface of the body has an identifying mark indicative of or associated with the owner of the cord.
[0009] Another embodiment includes a body comprising three detents, wherein two of the detents are configured to receive a portion of a cord and the third detent configured to receive a decorative accessory.
[0010] In another embodiment, an identifier is comprised of a plurality of detents configured to turn an electronic cord into a decorative necklace or bracelet.
[0011] These and other embodiments are described in more detail herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIGS. 1A-1B illustrate perspective views of the top and bottom of a cord identifier.
[0013] FIG. 1C illustrates a side elevational view of a cord identifier.
[0014] FIG. 1D illustrates a side perspective view of a cord identifier, showing a cord identification clip attached to a cord and interconnected with a second cord identifier.
[0015] FIG. 1E illustrates a side view of a cord identifiers having flat customizable surfaces.
[0016] FIG. 1F illustrates a top view of a cord identifiers having flat customizable surfaces.
[0017] FIG. 1G illustrates variations of uni-body cord identifiers ranging from having a single channel or cavity to a plurality of channels or cavities configured to receive a portion of a cord.
[0018] FIGS. 2A-2G illustrate a plurality of cord identifiers.
[0019] FIG. 3 illustrates a cord identifier configured to receive a decorative accessory.
[0020] FIG. 4 illustrates personalizing an electronic cord using a plurality of decorative cord identifiers.
[0021] FIGS. 5A-5G illustrate additional embodiments of cord identifiers.
[0022] FIGS. 6A-6C illustrate cord identifiers configured with alpha-numeric and other symbols.
[0023] FIG. 6D illustrates cord identifiers similar to FIGS. 6A-6C but further adapted to be attachable with each other.
[0024] FIG. 7 illustrates cord identifiers configured with alpha-numeric symbols or accessories.
[0025] FIG. 8 illustrates additional embodiments of cord identifiers.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] Customization of personal electronic products has become not only a way of recognizing one's personal belonging, but a way of establishing an image or reflection of one's personality and/or interests. There continues to be an increase of use and ownership of electronic products, including: mobile phones, smart phones, digital media players, handheld gaming devices, headphones, ear-buds and so forth. With each device there is generally provided a power cord and/or data cord unique to the particular device. Many of these devices allow for data input, data output or recharging of internal batteries. Electronic cords are provided to transfer power and/or data accordingly. With the increase of individuals owning electronic devices, or a plurality of devices, comes an increasing need to identify the cord associated with each particular device or the cord owned by a particular person. Confusion arises particularly in situations where individuals are using devices that utilize the same or similar cord, thus creating a need to identify cord ownership.
[0027] The present application seeks to provide a solution to the aforementioned problem by creating customizable and decorative cord identifiers configured to attach to electronic cords, whereby identifying the ownership of a particular cord is possible. The cord identifiers further create an external symbol indicative of, or associated with, the owner's loyalty to certain sports teams, stance on political issues, affiliation with a religious institution, profession, idea, philosophical viewpoint, cultural or ethnic backgrounds, groups, clubs or associations, and so forth. Additionally, the unique combination of cord identifiers can be used to support causes, show creativity, or any other expression desired.
[0028] Within the scope of the application is contemplated a business method of utilizing the decorative and personalizable aspects to raise money, and or awareness for a particular market. These steps may include, identifying a particular cause or purpose, identifying users of a particular device that tend to be supportive of the stated cause or purpose, developing a cord identifier customized to show support of the cause or purpose, and distributing the customized cord identification system to the identified group. An example of causes to raise money for could include cancer awareness or fundraising, introducing a new team or company, introduction of a new product, and fundraising for local schools or universities.
[0029] For purposes of this application, a detent may refer to any of a cavity, hole, channel, opening, slit, or other mechanism configured to temporarily keep a component in a certain position relative to that of another, and wherein the components may be released from each other by applying a force to one or both components. In addition, an identifier as described herein includes, but is not limited to, a device configured to attach to or receive, in at least one place, a portion of a cord, accessory, or another identifier. Cords defined herein include but are not limited to electronic cords, data transfer cords, non-electronic cords, necklaces, cord-like features, such as some linked chains.
[0030] FIGS. 1A-1C , illustrate various views of an identifier 130 having multiple cavities or channels ( 136 , 138 ). The uni-body shape of identifier 130 has at least one detent 132 contained within an outer surface and configured to receive a post or other male-connector portion of a decorative accessory. A narrow slit 139 runs along one edge of identifier 130 . This slit opens into a first cavity or channel 138 configured to partially encompass or encircle a cord 102 . A second channel or cavity 136 is formed within an adjacent portion of the body and is configured to receive a second portion of a cord or alternatively slideably interlock with a protruding portion 134 extending from a second identifier 130 of similar shape. The second channel 137 allows for the cord to be press-fit into the channel and held by the deformable elastic nature of the identifier and/or elastic nature of a rubberized cord that has been press-fit into the channel. Channels 136 and 138 may align parallel to each other, and in some variations, channels 136 and 138 may be align perpendicular to each other.
[0031] FIG. 1D illustrates identifier 130 being used in a manner where two 130 identifiers are interlocked together. This interlocking is aided by a protruding portion 134 that fits within second channel 136 . The interlocking configuration aides in bundling a cord together and keeping it organized. In some instances, looping the cord around an object may prevent the cord from sliding off the object. Looping can be accomplished by press-fitting two portions of the cord into the first and second cavities of a single identifier to complete a loop. A loop may also be created by interlocking two or more identifiers. In another configuration, identifier 130 may be used to create a necklace or bracelet out of a cord. Additionally, the core may be decorated with a decorative accessory attached to detent 132 . FIGS. 1E-1F showadditional embodiments of the uni-body identifier depicted in FIGS. 1A-1D , however, in these embodiments, the identifier has a more level or flat surface on opposing sides, wherein surface portion 133 may be used to identify the cord. For instance, surface portion 133 may be configured to receive ink, stickers, or some other mark-able material to identify a person, cause, symbol and so forth.
[0032] FIG. 1G illustrates multiple identifier embodiments having one or more slots or channels having an oval-shaped side-view. For example, identifier 150 a has narrow slit (not labeled) that runs along one of its edges. The slit opens into a first cavity or channel (as shown) configured to partially encompass or encircle a cord. A second channel or cavity may be formed within an adjacent portion of the body and is configured to receive a portion of a cord or alternatively, it may slideably interlock or press-fit with a protruding portion extending from a second identifier of similar shape. In other embodiments that an oval-shaped side-view, it is contemplated that there be only one cavity or channel, as demonstrated by identifier 150 b. Also consistent with the present disclosure are identifiers 150 c and 150 d, each having an oval-shaped body and have a first narrow slit opening into a first cavity or channel and a second narrow slit opening into a second cavity or channel, the cavities or channels each being configured to receive a cord. Identifier 150 c also having a detent. As demonstrated by identifiers 150 c and 150 d, the first channel and the second channel may align in a symmetrical manner across an axis, the channels may be parallel or perpendicular to each other, or the direction of the channels may not have a defined relationship with respect to each other.
[0033] As mentioned, identifier 130 has at least one detent 132 contained within at least an outer surface. In the embodiments shown in FIGS. 1A-1D , a detent is positioned on one side of the identifier. In other variations, it is contemplated that a detent be positioned on an opposing surface, side, or any other surface. Likewise, multiple detents may be placed on each side or surface of the identifier including some that extend from the main body portion of the identifier. In the case of multiple detents, it is contemplated that the detents may be placed a specified distance from each other or in a specified orientation. It is also contemplated that the detents may be angled with respect to one another.
[0034] It is also contemplated that a detent may be placed in a lobe or other protrusion extending from the body of an identifier. For example, an identifier with a cube-like base has a lobe, half-circle, or other protrusion extending from the base with a detent positioned within the inner portion of the lobe or half-circle (not shown). In another example, multiple lobes or protrusions may extend from the body or base of a single identifier.
[0035] The detents or holes may receive a decorative accessory through applying a force to a portion of the receiving member or interlocking a portion of the decorative accessory. For example, the detent may be a hole, wherein the male-portion of a decorative accessory is pressed into the detent. In other embodiments, the detent may have a ridge, wherein the male-portion of a decorative accessory is snapped into the detent. In yet another embodiment, the detent may be threaded, and thus, the male-portion of a decorative accessory is rotatably connected to the detent through a turning motion.
[0036] FIGS. 2A-2D illustrate samples of cord identifier embodiments, as well as exemplary ways to personalize one's electronic cord 102 .
[0037] FIG. 2A illustrates one embodiment of a cord identifier, wherein the identifier 110 a is shaped in a tube-like manner with an opening or slit along an edge, such that the tube may be configured to wrap around a cord 102 . As shown in FIG. 2B , end views 210 a of identifier 110 a show a slit or opening (not labeled) that may be spread apart. FIG. 2C illustrates another embodiment, wherein the identifier 110 b is shaped in an elongated tube-like manner. End view 210 b of identifier 110 b, as shown in FIG. 2D , illustrates a single slit from the center of 110 b to the outer edge and a partial slit from the center that does not extend fully to the outer edge on the opposite internal side of 110 b. The additional partial slit allows for the slit portion to open with less force when the identifier tube is opened to wrap around a cord 102 . FIG. 2E illustrates an identifier 110 c which is shaped in an elongated tube-like manner having an end view 210 c, shown in FIG. 2F , wherein the identifier is hinged at one point about which the two arms pivot. In this embodiment a male protruding portion on the end of one of the arms may clasp or connected with a cavity or detent portion on the opposing arm allowing for 102 c to be wrapped around cord 102 and snapped into place. In other embodiments, not shown, the slit or opening of the tubes as shown in FIGS. 2A-2F may form prongs that conform to the diameter or shape of the particular cord. FIG. 2G illustrates an identifier 120 having prongs that conform to the diameter of a cord.
[0038] FIGS. 2A-2F further demonstrate multiple embodiments of how an identifier can be personalized. For example, FIGS. 2A-2F may include a person's name, a web-address, a company name or logo, symbol, picture, phrase, or the like. Additionally, the prongs of identifiers 120 in FIG. 2G are configured to illustrate caricatures of animals' appendages, such as the arms and legs of a frog or bear.
[0039] The material of the identifiers shown in FIGS. 2A-2G may be elastically deformable such that identifier 110 a, 110 b, 110 c, and/or 120 can be deformed, bent or reshaped momentarily to enlarge the slot for a portion of the cord to be inserted into the channel portion of the tube, after which, the slot elastically returns/retracts to its original form. The side view of each of embodiment illustrates various deformable or hinged identifiers. For example, 210 a shows a single slit that can be spread open; 210 b illustrates single slit with a partial slit on the opposite internal surface allowing for slit portion to open with less force; and 210 c illustrates a hinged/pinned cross-section which two sections of the tube-like identifier may rotate about. Thus materials may include: rubber, plastic, silicone, or any other material demonstrating the desired properties mentioned above. Once a cord is inserted and the opening of the slot is released the identifier returns to its original shape. Alternatively, as mentioned above, some identifiers, such as 210 c, may be hinged about a pin wherein elastic deformation is not required.
[0040] In other embodiments, such as those shown in FIG. 3 , a plurality of detents 132 or holes may be included on 130 to receive additional decorative accessories 140 . These decorative accessories 140 may include shapes of baseballs, flowers, crowns or other ornamental design desired. It may also be a holder to attach an LED light for use in the dark when trying to plug in the particular cord or for other practical purposes for having an LED light attached to the cord.
[0041] Some embodiments, not shown, contemplate embedding a chip within the identifier to be used with the GPS, or other radio embedded technology of an electronic portable device, to send and receive a signal in order to find the lost or misplaced cord. For instance, an owner may locate the cord receiver using a software application on their smart phone that tells them how close they are to the cord. Other applications contemplated include those sending a signal to the chip embedded in an identifier along with other electronic components such as a capacitor or battery and a light or speaker. The signal can then cause the cord to beep or light up. The software application may also be designed to automatically have the cord light up or beep when the portable electronic device has gone outside a particular range, or on the other side, the software application of the portable device may alert the owner that the cord has gone out of range. This may help remind owners to not leave their particulars cords behind when traveling.
[0042] FIG. 4 is illustrative of the mix and matching of a variety of cord identifiers to create an array of identifiers indicating ownership by a particular person.
[0043] FIGS. 5A-5C illustrate other contemplated designs configure to have at least two channels for receiving at least two portions of a cord or in some cases portions of two different cords. FIG. 5A illustrates slightly transparent and gem-like structures where one channel encircles the cord more fully and act as a more permanent fixture while the second channel has a wider slot more conducive for press-fitting the cord in and out repeatedly. This may be helpful when bundling and unbundling a cord.
[0044] FIG. 5B shows a variety of sport-shaped identifiers with two-internal channels. Access to the internal channels is achieved through the same opening in the sidewall of the identifiers.
[0045] FIG. 5C illustrates channels adjacent with access to each channel on opposite sides. These particular identifiers further include protruding male components and female detents or holes configured to be connected with each other.
[0046] FIGS. 5D-5E show additional shapes contemplated in the present disclosure, the additional shapes having male-female connection points. For example, FIG. 5D has a male connection point having a similar size and shape as that of a cord. Thus, the female connection port can either accept a cord or the male connection point of a similar shaped identifier. FIG. 5E illustrates an embodiment similar to that shown in FIG. 5D , however, the male and female connection points are configured in a square/rectangular shape.
[0047] Additional two-channel cord identifiers are illustrated in FIGS. 5F-5G , more specifically, FIG. 5F uses honey comb shape to connect with other honey-comb shaped cord identifiers, while FIG. 5G illustrates a 3-dimensional shape configured to attach to at least one a cord.
[0048] FIGS. 6A-6D illustrate block-shaped cord identifiers with flat edges configured to be marked by alpha-numeric and other symbols. In FIG. 6A , block 600 has a slit 639 from the corner of the block into the channel 638 . Additionally, block 600 has an alpha-numeric character 610 on each side.
[0049] A cross-sectional elastically deformed view of identifier 650 is shown in FIG. 6B . Similar to block 600 in FIG. 6A , 650 has a slit from the corner of the block into the channel or opening of the block with the slot having a male connection point 652 and a female connection point 654 to secure the block identifier 650 when clasping or wrapping around a cord. FIG. 6C is an exemplary embodiment of how a cord owner might assemble letters on cord 102 . Compiling individual letters allows the cord owner to spell their name or write-out their telephone number. As with most of the cord identifiers described herein, the identifiers are capable of being customized by color, shape, design, logo, letters, fonts, and any other indicia sought for. FIG. 6D shows a block identifier having a slit 639 from the corner of the block into the channel 638 , the identifier also shows protruding points 660 on orthogonal sides. Not shown are detents or holes on opposite sides of each protruding portion. Again, designed to snap or press together, which may aide in bundling and organizing a cord(s). FIGS. 7-8 illustrate examples of how a cord may look with multiple identifiers attached thereto. Shown in both FIGS. 7-8 are uni-body identifiers with decorative accessories attached thereon as well as block-shaped identifiers, including block-shaped identifiers having alpha-numeric symbols.
[0050] Many of the embodiments shown employ a uni-body design, though it should not be construed that the invention is limited to such a design. However, the uni-body design allows for certain manufacturing advantage as well as simplicity when attaching to a cord.
[0051] While several embodiments have been described herein that are exemplary of the present invention, one skilled in the art will recognize additional embodiments within the spirit and scope of the invention. | 4y
|
REFERENCE TO RELATED APPLICATIONS
This is a continuation-in-part of applicant's co-pending application Ser. No. 545,193, filed Oct. 25, 1983.
BACKGROUND OF THE INVENTION
This invention relates to a rotary device such as a rotary gear pump in which the inner rotor has an outer tooth profile in the shape of the inner envelope of an epitrochoidal curve.
In a known rotary pump, the outer rotor has a tooth profile whose cross section is defined by a plurality of circular arcs of same radius of curvature centered at equal intervals on a circle of larger diameter defining the respective outer rotor teeth, the circular arcs being located inside the larger circle, and the adjacent circular arcs being connected by radially outwardly curved arcs inside the larger circle.
The inner rotor of this known rotary device has an outer profile in the shape of an inner envelope of an epitrochoidal curve. In an effort to obtain maximum discharge from within the limited volume available between the inner and outer rotors while minimizing pulsation of the discharge and/or reducing cavitation under high speed rotation, prior pumps of this type have been designed with a balancing of maximization of the number of teeth and minimizing the space taken up by the teeth so as to leave as much space as possible for the discharge. This has resulted in a tooth profile defining narrow and/or more sharply angled teeth.
The inventor has found that the parameters selected for the design of the inner rotor in order to meet these criteria have resulted in profiles having edges (discontinuities in slope) which, during use of the rotor in the pump, result in a bearing stress (Hertz stress) at the edge portion which increases to promote wear or settling thereat, thereby resulting in eventual deterioration in pump performance causing vibrations and/or noises. If, as sometimes occurs when the rotor designer becomes aware of the edge portion during the design stage, the edge portion is "smoothed over" during the design stage, and the resulting rotor will not operate at its maximum efficiency, but rather, will operate from the start as if the edge portion had become worn during use.
The present invention has been designed to overcome this problem, to provide a rotary device of the type described above in which the outer rotor is of the type described above with inwardly extending circularly arched teeth and the inner rotor is formed with an outer profile which is an inner envelope of the epitrochoidal curve, but without any edge portions.
SUMMARY OF THE INVENTION
The inventor has found that the edge portions of the inner rotor based on the inner envelope of an epitrochoidal curve are eliminated if parameters of the locus circle in the epitrochoidal curve are appropriately selected. In particular, if the locus circle has a diameter C, and the eiptrochoidal curve is defined by a base circle of diameter A, a rolling circle of diameter B, and an eccentricity of length e, so that the eccentricity ratio f e =e/B, the locus circle ratio f c =C/B and the base circle ratio n=A/B are defined, then the inner envelope curve will be smooth without any edge portions if f c /K i ≦1.0, wherein K i =(n+1)×|1-2f e |. When such an inner gear rotor is mounted for eccentric rotation in an outer rotor having circularly arched radially inwardly extending teeth which mesh with the teeth of the inner rotor, efficient operation of the resultant rotary pump device is obtained. In the preferred embodiment, circular arcs of the outer rotor have radii of curvature approximately equal to C/2 centered with equal spacing on an outer circle of diameter d 0 ≅A+B, whereby during rotation of the inner rotor in the outer rotor a small gap between continuously changing ones of the inner teeth and the outer teeth is maintained.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other aspects and features of the invention will be better understood from the following detailed description of the preferred embodiments when taken with the accompanying drawings in which:
FIG. 1 is an explanatory view of the formation of an inner envelope of an epitrochoidal curve for use in designing an inner rotor;
FIG. 2A is a schematic drawing of a portion of an epitrochoidal envelope formed in accordance with the prior art with a duplication portion;
FIG. 2B is a schematic drawing of a portion of an epitrochoidal envelope having an edge portion without a duplication portion;
FIG. 2C is an explanatory partial cross-sectional view of an inner rotor formed with the curve shown in FIG. 2A in relation to an outer rotor;
FIG. 3A is a partial cross-sectional view of a prior art rotor in which the edge portions have been removed or worn down;
FIG. 3B is a partial view of an epitrochoidal envelope of the type illustrated in FIG. 2B with edge portion rounded off;
FIG. 3C is a partial view of an epitrochoidal curve of the type illustrated in FIG. 2A, with the duplication portion rounded off;
FIG. 4A is a partial cross sectional view of an inner rotor in accordance with the present invention;
FIG. 4B is an enlarged view of a portion of FIG. 4A;
FIG. 5A is a partial cross-sectional view of an inner rotor having a duplication portion;
FIG. 5B is an enlarged view of a portion of FIG. 5A;
FIG. 6 is an explanatory view of an epitrochoidal envelope for an inner rotor in accordance with the present invention;
FIG. 7 is an explanatory drawing of a curve utilized in forming an outer rotor in accordance with the present invention.
FIG. 8 is an explanatory drawing of part of FIG. 7;
FIG. 9 is an explanatory drawing showing the major and minor diameters of the drawing shown in FIG. 8;
FIG. 10 is an explanatory drawing of an inner rotor assembled in an outer rotor;
FIGS. 11 and 12A are drawings similar to FIGS. 7 and 8, respectively, for an outer rotor in accordance with a second embodiment of the invention;
FIG. 12B is an explanatory drawing showing a portion of FIG. 12A;
FIGS. 13 and 14 are explanatory drawings showing a modification of the embodiment of the outer rotor illustrated in FIG. 11; and
FIG. 15 is a graph showing the relationships between tip clearance, rotor speed and volumetric efficiency.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In a rotary pump of this invention having inner and outer rotors and inlet and outlet ports as illustrated in FIG. 10 in which the inner and outer surfaces of the inner and outer gear rotors are defined utilizing the epitrochoidal curve, the periphery of the inner rotor is defined as is illustrated in FIG. 1 by first generating an epitrochoidal curve T as a locus of a fixed point inside the rolling circle of diameter B distanced from its center by an eccentricity e when the rolling circle is rolled on a base circle of diameter A without any slip. The outer periphery of the inner rotor (the inner rotor gear tooth shape or profile) TC can be formed in accordance with the prior art as the locus of points defined by a point on a circle of diameter C nearest the center of the base circle of diameter A as the center of the locus circle moves along the epitrochoidal curve T. The inner rotor will have a number of teeth n i equal to n=A/B. Referring to FIG. 6, it is well known that such a rotor will have a major diameter d 3 defined by: ##EQU1## Similarly, the minor diameter d 4 of the inner rotor is defined by: ##EQU2## Thus, it is clear that such an inner rotor tooth profile is determined by four parameters, either (A, B, C, e) or (n, B, C, e) or (n, A, C, e).
A known, theoretical outer rotor for use with the above-described inner rotor is formed utilizing the same parameters as were used for the inner rotor. Referring to FIGS. 7 and 8, the outer rotor tooth profile is formed of two portions including the dashed portions H and the solid line portions I (the inner portions of the circles G). The dashed portions H have the same profile as the tooth portions of the inner outer profile described above. The circles G are equiangularly spaced on a circle F of diameter d 0 where
d.sub.0 =A+B=(n+1)B
The circles G have a diameter C (the same as the diameter of the locus circles described above). The number of circles G is equal to n+1.
Referring to FIG. 9, illustrating the outer rotor tooth profile, the outer rotor tooth profile has a major diameter d 1 given by: ##EQU3## Similarly, the minor diameter d 2 of the outer rotor to the profile is given by: ##EQU4## Thus, the profile of the outer rotor tooth profile is also given by four parameters, that is, (A, B, C, e) or (n, B, C, e) or (n, A, C, e).
An inner rotor of the type described mounted on an outer rotor of the type described in schematically illustrated in FIG. 10.
The inner tooth profile of another outer rotor which may be utilized in accordance with the present invention is illustrated in FIGS. 11, 12A and 12B. This embodiment differs from the above-described embodiment only in that the portions J of the profile between the circularly arched portions K (of diameter C) are primarily portions of a circle of diameter less than d 0 , and thus such profile is a function of d 0 and C, or three parameters, that is, (A, B, C) or (n, B, C) or (n, A, C) since d o =A+B and n=A/B as indicated above. The portions J may be rounded slightly at their intersections with portions K.
In an actual prior rotary device utilizing the above-described inner rotor and second above-described embodiment of the outer rotor, the dimensions of the outer rotor teeth are reduced somewhat in order to provide a clearance known as a combinational gap, between an inner tooth and an adjacent outer tooth as the inner rotor rotates, so as to permit smoother rotation of the inner rotor. An improvement to this arrangement is described in applicant's co-pending application Ser. No. 448,503, now U.S. Pat. No. 4,504,202. Referring to FIGS. 13 and 14 illustrating this improvement, by increasing the radius d 0 /2 of the circle F by an amount ΔB and increasing the radius C/2 of the circles G by an amount ΔC, smooth rotation of the inner rotor will be retained while creating almost constant clearance between the inner and outer rotors provided that ΔB and ΔC satisfy the following in equalities: ##EQU5## The improvement is equally applicable to the above-described first embodiment of the outer rotor. This outer rotor design can be utilized in accordance with the rotary device of the present invention.
As is described above, the use of the above-described inner rotor with either of the above described outer rotors permits a generally uniform tip clearance to be obtained. However, if the inner rotor has an edge portion as is generally described above and described in detail below, it will be worn away during use in such a manner that the uniform tip clearance will not be retained, even in the case of the modifications of the outer rotor by ΔB and ΔC as described above, thereby promoting wear and deterioration of pump performance. The present invention overcomes this problem by eliminating the edge portion.
Referring to FIG. 2A, when the inner rotor in accordance with the prior art was designed, in forming the inner envelope, an edge portion was defined because small loops were created at particular locations along the envelope TC. Such loops are illustrated in FIG. 2A wherein the loops L are enlarged out of proportion to their normal size so that they can be seen by the naked eye. Loops, hereinafter to be referred to as "duplication portions", which, of course, are not present in the actual inner rotor, appear to be present in the mathematical analysis of the relation between the inner rotor and the outer rotor to obtain a theoretically ideal fit. As illustrated in FIG. 2C, since the actual inner rotor will not include the "duplication portion" and the edge will be removed either during initial manufacture or worn away during use, the tip clearance between the inner rotor and the outer rotor is not ideal, but becomes large and non-uniform, resulting in a reduction in pumping efficiency and an increase in noise. An exaggerated profile of the edge portion E of an actual rotor is illustrated in FIG. 2B and the same rotor either worn or intentionally smooth at the edge portion is illustrated in FIG. 3A. FIG. 2C shows in exaggerated form a gap between an inner rotor tooth and an outer rotor tooth resulting from the "duplication portion" which is shown in dashed line.
As indicated above, the profile illustrated in FIG. 2A does not represent a realizable rotor profile, the actual rotor having a profile without the "duplication portion". In this case, the actual inner rotor used in a rotary device having an outer rotor as described above, will experience bearing stress (Hertz stress) at the edge portion so as to promote wear or settling at the edge with the effects as described above. Therefore, in accordance with the prior art, the edge portion has been initially corrected as illustrated in FIG. 3A by rounding of the edge portions of the envelope and actual tooth profiles respectively illustrated in FIGS. 2A and 2B as shown in FIGS. 3B and 3C in which W 1 is the width of the edge including the loop L in FIG. 2A and W 2 is the size of the actual edge E in FIG. 2B.
However, such correction will result in a reduction in the size of each tooth profile so that the resulting inner rotor profile differs from the theoretically ideal epitrochoidal envelope curve of the inner rotor, which is quite similar in effect to a rotor which has worn by an amount W 1 after use, thus resulting in the same reduction in performance of the rotary pump device as would be produced by wear.
The decrease in pumping efficiency caused by the increase in tip clearance is particularly striking under such operating condition as low speed of, and high pressure and low viscosity fluid in, the rotary device. For example, for a speed of 700 rpm, a discharge pressure of 5 kg/cm 2 , a viscosity of 10 cst and a side clearance of 0.05 mm between the pump housing and rotor set. The decreasing volumetric efficiency with increasing tip clearance and decreasing rotor speed is illustrated in FIG. 15. The inventor has observed that even with the improved outer rotor disclosed in the inventor's U.S. Pat. No. 4,504,502 as discussed above, the tip clearance variation during rotation cannot be reduced as much as desired with the prior art inner rotor having an edge portion based on a design with the duplication portion on the epitrochoid envelope profile.
In order to eliminate the duplication portion from the epitrochoid envelope of the inner rotor design and the edge portion of the actual inner rotor profile which are illustrated in FIGS. 5A and 5B, the inventor determined after detailed study that if the parameters of the inner envelope of the epitrochoidal curve defining the cross section of the inner rotor are represented by a base circle diameter A, a rolling circle diameter B, a locus circle diameter C, an eccentricity e, and eccentricity ratio f e =e/B and locus circle ratio f c =C/B and base circle ratio n=A/B, then the duplicate portion and edge portion will be eliminated as illustrated in FIGS. 4A and 4B if the following inequality is satisfied: ##EQU6##
The inventor has also found that the duplication portion can be substantially eliminated if f c /K i is in the range 1.0 to 1.1, and the number of teeth n i on the inner rotor is equal to the closest integer to d 4 /2e where d 4 is the minor diameter of the inner rotor (see FIG. 6). Also, the inventor has found that irrespective of the number of teeth, the duplication portion will be maintained small within an acceptable range for some applications such as low pressure usage or high viscosity fluid usage, i.e., within the range 0.01-0.02 mm, for f c /K i =1.1 if the size of the inner rotor is not too large, i.e., an inner rotor corresponding to an outer diameter of the outer rotor no greater than approximately 100 mm.
To illustrate the effect on the duplication portion of proper selection of the ratio f c /K i , examples of the parameters and the size of the duplication portion of known prior inner rotors are listed in Table 1 below for comparison to the parameters and size of the duplication portion of inner rotors, in accordance with the present invention of substantially the same overall size as the prior rotors, which are listed in Table 2 below. In the Tables, the symbols φ23 and φ40 indicate the outer diameters of the outer rotors of the rotary devices in which the inner rotors are positioned.
TABLE 1______________________________________DimensionItem d.sub.4 /2e n.sub.i f.sub.c /K.sub.i δ______________________________________φ23 5.976 7 2.01 0.03˜0.05φ40 3.345 4 1.20 0.01˜0.03______________________________________
TABLE 2______________________________________DimensionsItem d.sub.4 /2e n.sub.i f.sub.c /Ki δ______________________________________φ23 5.976 6 1.01 0φ40 3.346 3 0.91 0______________________________________
Thus, as is apparent from a comparison of Tables 1 and 2, even for f c /K i =1.01, the size of the duplication portion is substantially zero.
While particular embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope and spirit of the invention which is limited only by the appended claims. | 4y
|
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for processing XML data and, more particularly, for developing security views of information contained within a larger assembly or organization of such information.
DESCRIPTION OF THE BACKGROUND ART
XML (Extensible Markup Language) is rapidly emerging as the new standard for data representation and exchange on the Internet. As corporations and organizations increasingly employ the Internet as a means of improving business-transaction efficiency and productivity, it is increasingly common to find operational data and other business information in XML format. In light of the sensitive nature of such business information, securing XML content and ensuring the selective exposure of information to different classes of users based on their access privileges is important. Specifically, for an XML document T there may be multiple user groups who want to query the same document. For these user groups, different access policies may be imposed, specifying what elements of T the users are granted access.
Access control models for XML data have been proposed; however, these models suffer from various limitations. For example, such models may reject proper queries and access, incur costly runtime security checks for queries, require expensive view materialization and maintenance, or complicate integrity maintenance by annotating the underlying data. More specifically, for a number of different users, having corresponding different access policies, each node in the XML document (i.e., the actual XML data) would have to be annotated to define such users' with the various levels of access allowed based on their individual user profiles. While such annotating may be easily performed if there are only a few user groups, annotating becomes increasingly complex as the number of user groups and corresponding access policies increases. There is also an undesirable possibility of generating errors in the XML document or in the XML data during the annotation process. Maintenance costs of the XML data also increases if it desired to modify a document at some point in the future. For example, adding a subtree of new elements in the XML data will require further annotating for each of the existing user groups again with the possibility of errors being generated in the data during this process.
Additionally, and with regard to user views, it is conceivable that many hundreds or possibly thousands of different views must be generated to satisfy all of the combinations of queries and users that the XML document serves. Such views are costly to prepare and maintain, as well as providing the specific XML data (which may be subject to tampering or error generation) as a result of view usage. Additionally, users are not provided with the exact structure of the data. As such, they do not know how to properly formulate a query which creates an overall inefficient system for storing, maintaining and subsequently accessing data. A more subtle problem is that none of these earlier models provides users with a Document Type Definition (DTD) characterizing the information that users are allowed to access. Some models expose the full document DTD to all users, and make it possible to employ (seemingly secure) queries to infer information that the access control policy was meant to protect. Accordingly, there is a need to provide access to XML data of an XML document without corrupting or otherwise changing the XML data and provide suitable query interaction with such data.
SUMMARY OF THE INVENTION
Various deficiencies of the prior art are addressed by the present invention of a method for providing controlled access to an XML document by defining at least one access control policy for a user of the XML document and deriving a security view of the XML document for the user based upon said access control policy and schema level processing of the XML document. The invention also includes a step of translating a user query based on the security view of the XML document to an equivalent query based on the XML document.
Deriving a security view includes invoking a first sub process that determines if a first accessible element type of an XML document DTD representing said XML document has been previously processed. If the first accessible element type has not been previously processed, then the first sub process performs the steps of computing a query annotation for each child element in a production rule of the first accessible element type computing a view production rule for first accessible element type in a view DTD representing an accessible portion of the XML document and computing a security view for each child element in the production rule of the first accessible element type. Computing a security view for each child element in the production rule of the first accessible element type includes invoking a second sub process if a child element in the production rule of the first accessible element type is inaccessible; otherwise, the first sub process is invoked for said child element. Translating the user query based on the security view of the XML document includes iteratively computing at least one local translation corresponding to at least one subquery of the first accessible element type that is part of the user query. The method can be practiced by a computer readable medium containing a program which, when executed, performs these operations.
Additionally, the invention includes an apparatus for performing an operation of securely providing access to XML data of an XML document that includes means for defining an access control policy for a user of the XML document and means for deriving a security view of the XML document for the user based on said access control policy and schema level processing of the XML document. The apparatus also includes means for translating a user query based on the security view of the XML document to an equivalent query based on the XML document.
The means for defining the access control policy includes an access specification that annotates a document DTD representing the XML document. Such an access specification can be derived by a database manager of the XML document. The means for deriving a security view of the XML document for the user includes a security view definition that defines query annotations in a document DTD representing the XML document. The means for translating a user query based on the security view of the XML document to an equivalent query based on the XML document includes a query evaluator that maps one or more nodes in the security view to corresponding one or more nodes in the document DTD representing the XML document. In this way, access of specific information in the XML document is provided only to those having the proper access specification and corresponding view without having to annotate or otherwise process the actual data in the XML document.
BRIEF DESCRIPTION OF THE DRAWINGS
The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:
FIG. 1 depicts a conceptual model of the subject invention and how it interacts with an XML document;
FIG. 2 depicts an exemplary document DTD that is managed in accordance with the subject invention;
FIG. 3 is a security view of the exemplary document DTD of FIG. 2 for one particular user or user group having a first user access profile or specification;
FIG. 4 depicts a graphical representation of the first user access profile or specification in comparison to the exemplary document DTD of FIG. 2 ;
FIG. 5 depicts a preferred embodiment of a method of deriving a security view based upon a security specification shown in pseudo code;
FIG. 6 depicts a preferred embodiment of a method of rewriting queries by a first user using the security view shown in pseudo code;
FIG. 7 depicts a series of diagrams to account for query rewriting of a recursive view DTD;
FIG. 8 depicts a preferred embodiment for optimizing query rewriting in accordance with the subject invention;
FIG. 9 depicts a flow chart for practicing the method and pseudo code of FIG. 5 ;
FIG. 10 depicts a flow chart for practicing a first sub process of the method and pseudo code of FIG. 5 ;
FIG. 11 depicts a flow chart for practicing a second sub process of the method and pseudo code of FIG. 5 ;
FIG. 12 depicts a flow chart for practicing the method and pseudo code of FIG. 6
FIG. 13 depicts a flow chart for practicing a first sub process of the method and pseudo code of FIG. 6 ;
FIG. 14 depicts a flow chart for practicing a second sub process of the method and pseudo code of FIG. 6 ;
FIG. 15 depicts a flow chart for practicing the method and pseudo code of FIG. 8 ; and
FIG. 16 depicts a apparatus for deriving security views of XML documents in accordance with the subject invention.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.
DETAILED DESCRIPTION
This invention will be described within the context of Extensible Mark Up Language (XML). Consider an XML document T having any number of data elements arranged therein. A Document Type Definition (DTD) D is associated with T which governs the organization or exact structure of the data (also referred to as schema information). Multiple access control policies are declared over T at the same time, each specifying, for a class of users, what elements in T the users are granted, denied, or conditionally granted access to. A language is defined for specifying fine-grained access control policies. An access specification S expressed in the language is an extension of the document DTD D associating element types with security annotations (i.e., XPath qualifiers), which specify structure- and content-based accessibility of the corresponding elements of these types in T. Since the primary concern is with querying XML data, the specification language adopts a simple syntax instead of the conventional (subject, object, operation) syntax.
An access specification S is enforced through an automatically-derived security view V=(D v ,σ), where D v is a view DTD and σ is a function defined via XPath queries. The view DTD D v exposes only accessible data with respect to S, and is provided to users authorized by S so that they can formulate their queries over the view. The function ca is transparent to authorized users, and is used to extract accessible data from T. The only structural information about T that the users are aware of is D v , and no information beyond the view can be inferred from user queries. Thus, the security views support both access/inference control and schema availability. An efficient algorithm is provided that, given an access specification S, derives a security view definition V, i.e., V characterizing all and only those accessible elements of T with respect to S based on schema level processing of the DTD D rather than merely annotating data within the document T.
Accordingly, an access control model 100 based on security views for an XML document 104 is presented and conceptually depicted in FIG. 1 . For each access control policy, a security administrator (or DBA) defines a specification S 102 1 . . . 102 k by annotating a document DTD D associated with the XML document 104 (e.g., through a simple GUI tool). For each specification S l . . . k , a security view definition V 1 . . . V n 106 is automatically derived by a view-derivation algorithm. A corresponding security-view DTD D v is exposed to users authorized by S so that they can formulate and pose their queries 108 over the security view V. The security view is virtual, and a query 108 labeled p over V is evaluated 110 by efficiently rewriting to an equivalent query p t over the original document T 104 by incorporating XPath queries in σ. Additionally, the subject invention includes algorithms to optimize p t by exploiting the document DTD D. Finally, the optimized query p t is executed over T and its result is returned to the users. Note that S, σ, and D are invisible to users. Security issues are handled at the query-rewriting level and are completely hidden from users of the view. In this manner, the invention provides a flexible, secure framework for querying XML data that overcomes the limitations of earlier proposals.
The concepts of the subject invention are best realized when considering the following specification concurrently with the figures as follows. For example, FIG. 2 depicts a document type definition (DTD) of a hospital document that is accessed by a large number of users (doctors, nurses, patients and the like). The DTD is represented as a graph 200 having a plurality of nodes 202 x interconnected by a plurality of edges 204 x . (Note: not all of the nodes and edges have been labeled for sake of clarity). Each of the nodes 202 x represents a different data element in the DTD while the edges 204 x represent the mapping (in this example a tree type mapping) that identifies the relationship between each of the elements in the DTD 200 . Consider that in such a DTD, a hospital wants to impose a security policy that authorizes nurses to access all patient data except for information concerning whether a patient is involved in clinical trials. In order to provide access to approved information yet prevent access to unapproved information, a security or access specification is required for nurses that conforms to this DTD.
FIG. 3 depicts a security view 300 resulting from the creation and evaluation of a security or access specification 400 in accordance with the subject invention and seen in greater detail in FIG. 4 . In particular, the access specification 400 is an extension of the document DTD 200 associating security annotations with productions of D. The access specification 400 has nodes 202 x and edges 204 x similar to the DTD of FIG. 2 , only with specific regard to the material that a nurse will have access to. Specifically, D is defined to be (D, ann), where ann is a partial mapping such that, for each production A→α and each element type B in α, ann (A,B), if explicitly defined, is an annotation of the form:
ann( A,B )::=Y|[q]|N,
where [q] is a qualifier in a fragment C of XPath. Intuitively, a value of Y, [q], or N for ann (A,B) indicates that the B children of A elements in an instantiation of D are accessible, conditionally accessible, and inaccessible, respectively. If ann (A,B) is not explicitly defined, then B inherits the accessibility of A. On the other hand, if ann (A,B) is explicitly defined it may override the accessibility of A. The root of D is annotated Y by default. This specification is depicted in FIG. 4 , where bold edges (e.g. 404 , not all labeled, but plainly visible) represent ‘Y’ or ‘[q]’ annotations, while normal edges 406 represent ‘N’ annotations. Thus, nurses can only access the patient and staff information in a dept having a certain ward (restricted by the qualifier q 1 ). Moreover, they are not authorized to know which patients are involved in clinical trials as well as the form of treatment, except for bill and medication information.
For an XML instance T of a DTD D, an access specification S=(D, ann) can be easily defined, e.g., using a simple GUI tool over D's DTD graph. Furthermore, S unambiguously defines the accessibility of document nodes in T. To see this, note that DTD D must be unambiguous by the XML standard. Since T is an instance of D, this implies that each B element υ of T has a unique parent A element and a unique production that “parses” the A subtree; thus, υ's accessibility ann (υ) can be defined to be exactly the ann (A,B) associated with the production for A. We say that υ is accessible with respect to S if and only if either
(1) ann(υ) is Y or ann(υ) is [q] and [q] is true at υ, and, moreover, for all ancestors υ′ of υ such that ann(υ′)=[q′], the qualifier [q′], is true at υ′; or, (2) ann(υ) is not explicitly defined but the parent of υ is accessible with respect to S. Note that for υ to be accessible, the qualifiers associated with all ancestors of υ must be true. Referring to the example of FIGS. 2 , 3 and 4 , for a nurse to access the information of a department d, the qualifier q 1 (see FIG. 4 ) associated with dept must be true at d, so that the nurse is prevented from unauthorized access to information of different departments.
FIG. 3 depicts a security view υ 300 from the access specification 400 discussed previously to a view DTD D υ for nurses. The view DTD removes information about inaccessible nodes such as “clinicalTrial”, and introduces “dummy” labels 302 dummy 1 , dummy 2 to hide the label information of regular and trial, while retaining the disjunctive semantics at the accessible “treatment” node. Recall that ε denotes the empty path. The view DTD is provided to the nurses, while the XPath mapping σ, is not visible to them. Since the nurses can not see the document DTD, they have no knowledge about what the dummies stand for.
A security view 300 defines a mapping from instances of a document DTD D to instances of a view DTD D υ that is automatically derived from a given access specification 400 . Let S=(D,ann) be an access specification. A security view definition (or simply a security view) V from S to a view DTD D υ , denoted by V:S→D υ , is defined as a pair V=(D υ,σ ), where σ defines XPath query annotations used to extract accessible data from an instance T of D. Specifically, for each production A→α in D υ and each element type B in α, σ(A,B) is an XPath query (in our class C) defined over document instances of D such that, given an A element, σ(A,B) generates its B sub elements in the view by extracting data from the document. A special case is the unary parameter usage with σ(r υ )=r, where r υ is the root type of D υ and r is the root of D, i.e., σ maps the root of T to the root of its view.
The semantics of a security view definition V:S→D υ are given by presenting a materialization strategy for V. Given an instance T of the document DTD, a view of T is built, (denoted by T υ ) that conforms to the view DTD D υ and consists of all and only accessible nodes of T with respect to S. Then, a top-down computation is performed by first extracting the root of T and treating it as the root of T υ , and then iteratively expanding the partial tree by generating the children of current leaf nodes. Specifically, in each iteration each leaf υ is inspected. Assume that the element type of υ is A and that the A production in D υ is P(A)=A→α. The children of υ are generated by extracting nodes from T via the XPath annotation σ(A,B) for each child type B in α. The computation is based on the structure of production P(A) as follows:
(1) Nothing needs to be done when P(A) is A→ε
(2) P(A)=A→str. Then, the query p defined in (A,str) is evaluated at context node υ in T. If υ[[p]] returns a single text node in T that is accessible with respect to S, then the text node is treated as the only child of υ; otherwise, the computation aborts.
(3) P(A)=A→B 1 . . . , B n Then, for each i ∈ [1,n], the query p i =σ(A,B i ) is evaluated at context node υ in T. If for all i ∈ [1,n], υ[[p i ]] returns a single node υ i accessible with respect to S, then υ i is treated as the B i child of υ; otherwise, the computation aborts.
(4) P(A)=A→B 1 + . . . +B n . Then, for each i ∈ [1,n], the XPath query p i =σ(A, B i ) is evaluated at context node υ in T. If there exists one and only one i ∈ [1,n] such that υ[[p i ]] returns a single node accessible with respect to S, then the node is treated as the single child of υ; otherwise, the computation aborts.
(5) P(A)=A→B*. Then, the query p=σ(A,B) is evaluated at context node υ in T. All the nodes in υ[[p]] accessible with respect to S are treated as the B children of υ, ordered by the document order of T. Note that, if υ[[p]] is empty, no children of υ are created.
A novel algorithm (termed “derive”) is presented that, given an access specification S=(D,ann), automatically computes a security view definition V=(D υ σ) with respect to S such that, for any instance T of the document DTD, if the computation of T υ terminates (i.e., does not abort), it comprises all and only accessible elements of T with respect to S. One embodiment of algorithm “derive” is shown in FIG. 5 as a series of pseudo code steps 500 . When building V=(D υ σ), the algorithm hides inaccessible nodes in the document DTD D by either short-cutting them, or renaming them using dummy labels. It uses two procedures, Proc_Acc(S,A) and Proc_InAcc(S,A), to deal with accessible and inaccessible element types A of D, respectively. It traverses the document DTD D top-down by invoking Proc_Acc(S,r), where r is the root element type of D. For each accessible element type A encountered, Proc_Acc(S,A) constructs a production P υ (A)=A→α in the view DTD D υ , and computes appropriate XPath queries σ(A,B)=p B for each type B in α, based on the A-production in the document DTD D (cases 1-4 presented above). More specifically,
(a) if B is accessible, then p B is simply ‘B’ (steps 6 , 7 );
(b) if B is conditionally accessible (i.e., ann(A,B)=[q]), then p B is ‘B’[q], i.e., qualifiers in S are preserved (steps 8 , 9 ); and,
(c) if B is inaccessible, then the algorithm either prunes the entire inaccessible subgraph below B if B does not have any accessible descendants (step 11 ), or ‘shortcuts’ B by treating the accessible descendants of B as children of A if this does not violate the DTD-schema form of Section 2 (steps 12 - 15 ), or renames B to a “dummy” label to hide the label B while retaining the DTD structure and semantics (steps 16 - 20 ). Children of the B node are then processed in the same manner. In this way, the resultant view DTD D υ , preserves the structure and semantics of the relevant and accessible parts of the original document DTD.
The procedure Proc InAcc(S,A) processes an inaccessible node A in a similar manner. One difference is that it computes (1) reg(A) instead of a in the A-production A→α in the view DTD D υ , and (2) path [A,B] for each element type B in reg(A) rather than σ(A,B). Intuitively, reg(B) is a regular expression identifying all the closest accessible descendants of B in D, and path [A,B] stores the XPath query that captures the paths from A to B in the document DTD. Another difference concerns the treatment of recursive node. If an inaccessible A is encountered again in the computation of Proc_InAcc(S,A), then A is renamed to a dummy label and retained in the regular expression returned.
To efficiently compute V, Algorithm “Derive” associates two Boolean variables visited[A, acc] and visited[A, inacc] (initially false) with each element type A in the document DTD D. These variables indicate whether A has already been processed as an accessible or inaccessible node, respectively, to ensure that each element type of D is processed only once in each case. In light of this, the algorithm takes at most O(|D| 2 ) time, where |D| is the size of the document DTD.
A more general depiction of the inventive concept is shown in FIG. 9 . Specifically, FIG. 9 depicts a flow chart 900 having a series of steps for practicing the algorithm “Derive”. Specifically, the method begins at step 902 and proceeds to step 904 wherein the Boolean variables “visited” are initialized. In this particular example, the initialization of value is “false”. Additionally at step 904 , R is initialized to be the root element type of the DTD D which is being processed. At step 906 , processing of the security view begins by invoking an accessible element procedure with respect to the predetermined security specification S and the root element R. In this manner, the aforementioned top down processing of each element type in the DTD D is analyzed and appropriate productions, queries or regular expressions are subsequently assigned to compute a security view V. In one embodiment of the invention, the invoked procedure is referred to as “Proc_Acc (S,R)” and is described in greater detail below. The method ends at step 908 .
FIG. 10 depicts Proc_Acc (as identified in step 906 of FIG. 9 ) as a series of method steps 1000 . Specifically, algorithm Proc_Acc begins at step 1002 and proceeds to step 1004 where a first element type (for example element type A underneath root R) goes under a query to determine if such element type has been previously processed. In one particular example, the query is determined by evaluating the visited (A, acc) variable. If the answer to the query is yes (that element type A has been previously processed) the method proceeds to step 1012 where the algorithm ends.
If the element type has not been previously processed, the method moves to step 1006 where a first computation is performed. Specifically, query annotation (for example denoted by the function σ) is computed for each child element B i in the production rule for the element type A currently being processed. In one particular example, the query annotation is XPath query annotation. Once the query annotation is computed, the method proceeds to step 1008 to compute a view production rule P v (A) for the element type A in the view DTD D v . Once the computation of the view production rule is completed, the method moves to step 1010 where a security view for each child element B i in the production rule for A is computed. In one embodiment of the invention, this computation is performed by invoking a process for inaccessible nodes if the child element B i is inaccessible (with respect to A) otherwise the accessible element procedure for such B i is called. After the security view is computed for each element B i , the method ends at step 1012 .
FIG. 11 depicts the algorithm for inaccessible nodes (referred to in one embodiment of the invention as Proc_InAcc) as a series of method steps 1100 . Proc_InAcc is similar in execution to Proc_Acc with the difference being in the values that are computed based on the inaccessibility of the elements as detailed below. Specifically, the method starts at step 1102 and proceeds to step 1104 where a first query is performed to determine if the element type A currently being evaluated has been previously processed. As discussed above, this is accomplished via analysis of the Boolean variable visited (A, InAcc). If the answer to the query is yes, the method proceeds to step 1112 and the method ends.
If the answer to the query is no, the method moves to step 1106 where a path for each child element B i in the production of A is computed. Particularly and in one embodiment of the invention, the path is computed as Path [A, B i ] which is a value that stores the XPath query that captures the paths from A to B in the document DTD as discussed previously. Once the path has been computed, the method moves to step 1108 where a regular expression for A is computed. More specifically and as previously discussed, the value reg [A] is computed instead of α (reg[A] is defined as a regular expression identifying all the closest descendants of A in D). Once the regular expression for A has been computed, the method moves to step 1110 where the security view for each child element B i in the production rule for A is computed. Specifically in one embodiment of the invention the security view is computed by calling Proc_InAcc if such child element B i is inaccessible with respect to A, otherwise, Proc_Acc is called for B i . Once the security view for each child element B i is computed, the method ends at step 1112 .
Once an access policy is determined, and a corresponding security view is derived for a particular user or user group, such user or user group can pose a query on the security view. The query allows the user to access information in the DTD according to such access policy without reviewing information that the user is not allowed to have access to. Further, in accordance with the subject invention, the actual data in the DTD or XML document is not accessed or made otherwise made available to the user for the possible situation of unauthorized tampering or otherwise error-creating accessing of the information. This is accomplished by the novel method of the query rewriting. That is, given an query p over the security view, p is automatically transformed to another XPath query p t over the document DTD D such that, for any instance T of D, p over T υ and p t yield the same answer. In other words, p over the view is equivalent to p t over the original document (i.e., p t (T)=p(T υ )). This eliminates the need for materializing views and its associated problems.
Specifically, given a query p over the view DTD D υ , a rewriting algorithm “evaluates” p over the DTD graph D υ . For each node A reached via p from the root r of D υ , every label path leading to A from r is rewritten by incorporating the security-view annotations σ along the path. As a maps view nodes to document nodes, this yields a query p t over the document DTD D.
To implement this idea, the algorithm works over the hierarchical, parse-tree representation of the view query p and uses the following set of variables. For any sub-query p′ of p and each node A in D υ , rw(p′,A) is used to denote the local translation of p′ at A, i.e., a query over D that is equivalent to p′ when p′ is evaluated at a context node A. Thus, rw(p,r)=p t is what the algorithm needs to compute. Reach (p′,A) is also used to denote the nodes in D υ that are reachable from A via p′. Finally, N is used to denote the list of all the nodes in D υ , and Q to denote the list of all sub-queries of p in “ascending” order, such that all sub-queries of p′ (i.e., its descendants in p's parse tree) precede p′ in Q.
Given the above, one embodiment of this Algorithm is identified as “Rewrite” and is presented in FIG. 6 as a series of pseudo code steps 600 . The algorithm is based on dynamic programming, that is, for each sub-query p′of p and node A in D υ , Algorithm “Rewrite” computes a local translation rw (p′,A). To do this, “Rewrite” first computes rw (p i , B i ) for each (immediate) sub-query p i of p′ at each possible view DTD node B i under A; then, it combines these rw(p i , B i )'s to get rw(p′,A). The details of this combination are determined based on the formation of p′ from its immediate sub-queries p i , if any. The computation is carried out bottom-up via a nested iteration over the lists of sub-queries Q and DTD nodes N. Each step of the iteration computes rw(p′,A) for some p′ and A, starting from the “smallest” sub-queries of p. At the end of the iteration pt=rw(p,r) is obtained.
In one embodiment of the method for query rewriting, the algorithm is generally shown as a series of method steps 1200 in FIG. 12 . The algorithm receives as input a Security View V and a query p over the view DTD D v and outputs an equivalent query p t over the entire document DTD D. This is accomplished by starting the method at step 1202 and proceeding to step 1204 where a series of parameter value initializations are performed. Examples of such parameter initializations are selected from the group consisting of Q (which denotes a sequence of sub-queries of p in reverse in topological order), N (which denotes a sequence of nodes in the view DTD in reverse topological order), arrays for values rw and reach and p′ (which denotes a first sub-query in Q).
Once the initializations are performed, the method proceeds to step 1206 where a first sub process is called to compute a variable reach (//A) for each node A in the view DTD. Reach(//,A) is the set of descendant nodes of A in the view DTD D v . The method then proceeds to step 1208 where the value of A is initialized to be the first node in N. The method then proceeds to step 1210 where computations of the values for rw (p′, a) and reach (p′a) are computed based on the type of sub-query p′.
Once those values are computed, the method moves to 1212 where an inquiry is made if a next node A from the sequence of nodes N is available. If the answer to the inquiry is yes, the method loops back to step 1210 where values for rw and reach are computed for the next node A value. If the answer to the query is no, the method moves to step 1214 where another query is posed. Specifically, if there is a next sub-query in the present node N in the sequence of sub-queries Q, then the method loops back to step 1208 to reinitialize A as the first node in N. If the answer to the query is no, the method proceeds to step 1216 where the equivalent query pt is assigned the value of rw(p,r) where r is the root of the view DTD Dv. The method ends at step 218 .
Earlier per step 1206 a first subroutine was introduced that computes the value reach (//,A). This particular subroutine in one embodiment of the invention is identified as algorithm “recProc” and is shown as a series of method steps 1300 in FIG. 13 . Algorithm recProc receives a node A in the view DTD as input and calculates the value reach (//,A) and a value recrw (AB) for each child B in the value reach (//,A). Specifically, the method starts at step 1302 and proceeds to step 1304 where values for the arrays recrw and visited are initialized. One the initialization is complete, the method moves to 1306 where a second sub process is called to compute the value reach (//,A) and (recrwAB) for each child node B of A. Subsequently, the method ends at the 1308.
As discussed earlier with respect to step 1306 of algorithm recProc above, the second sub process to compute, reach and recrw in one embodiment of the invention is a series of method steps 1400 as shown in FIG. 14 . Specifically, the series of method steps are identified as “Algorithm Traverse” which accepts as an input a node x in the DTD and outputs a value for reach (//,X) and (recrw X, Y) for each child node Y of X. Specifically, the method begins at step 1402 and proceeds to step 1404 where the value Y is initialized to be the first child node of X in the view DTD D v . At step 1406 , the value of (recrw X, Y) is updated using query annotation. In one embodiment of the invention, XPath query annotation is used such as the annotation σ (X, Y). This updated value of rcrw represents all paths from X to Y in the view DTD D v . Once the updating has been completed, the method proceeds to step 1408 where a decision is performed as to whether the node Y has been processed before. If the node has been processed before, the method jumps to step 1412 where another decision is performed. Specifically, a decision is made as to whether to get the next child node Y of X. If the next child node Y of X is not to be obtained, the answer to the query is no and the method ends at step 1414 . If the answer to the query is yes, the method loops back to step 1406 where the updating is performed again.
If the answer to the inquiry at step 1408 is no, that is that node Y has not previously been processed, then the method proceeds to step 1410 where the parameter reach (//,X) is updated and then the subject Algorithm Traverse is called again with respect to child node Y of the presently processed node X. The parameter reach (//,X) represents all the descendant nodes in the view DTD that are reachable from X with an additional node Y.
Query rewriting becomes more intriguing when the view DTD is recursive. For example, consider the view DTD 704 shown in FIG. 7 ( b ), which is derived from the specification S 706 of FIG. 7 ( c ) (where, as in FIG. 4 , normal edges point to inaccessible nodes). Consider query //b 702 over the view 704 . Although the view DTD 704 is merely a sub-graph of the document DTD d for S, this query cannot be evaluated directly over instances of d since it returns the inaccessible b child of a. Algorithm “Rewrite” no longer works here since a direct translation of ‘//’ leads to infinitely many paths. Although the query is equivalent to the regular expression (a/c)*/b, such regular expressions are beyond the expressive power of the XPath standard; thus, it is not always possible to rewrite an XPath query over a recursive view to an equivalent XPath query over a document DTD.
A solution to this problem is by unfolding recursive nodes. Unfolding a recursive DTD node A is defined as creating distinct children for A following the A production. Referring to FIG. 7 ( b ), unfolding node “c” by one level means creating a distinct a child for node “c” instead of referring to the existing “a” node, as shown in diagram 708 of FIG. 7 ( d ). Remember that a security view V:S→D υ is defined over a concrete XML document T. Since the height of T is known, one can determine by how many levels recursive nodes need to be unfolded, and such an unfolding yields a non-recursive (DAG) view DTD that the document is guaranteed to conform to. This allows use of Algorithm “rewrite” as before. Unfolding D υ , to a DAG is possible since, as long as D υ is consistent (i.e., there exist documents conforming to it), each recursive A must have a non-recursive rule. For example, a→b is the non-recursive rule for a→a|b, and a→b,ε is the non-recursive rule for a→b,a*. Thus, for a fixed T, one can determine the unfolding levels and apply the non-recursive rules at certain stages. Note that when T is updated, the adjustment to the DTD unfolding is rather mild and does not introduce any serious overhead. Additionally, while access-control specifications, security views and their derivation are all conducted at the schema-level (i.e., on DTDs only), query rewriting over recursive security views needs the height information of the concrete XML tree over which the queries are evaluated.
As presented earlier, the rewriting algorithm transforms a query over a security view to an equivalent query over the original document. However, the rewritten query may not be efficient. Accordingly, query optimization in the presence of a DTD D is considered. In other words, given an XPath query p, find another query p o such that over any instance T of D,
(1) p and p o are equivalent, i.e., p(T)=p o (T); and
(2) p o is more efficient than p, i.e., p o (T) takes less time/space to compute than p(T). This is not only important in our access control model where queries generated by Algorithm “Rewrite” are optimized using the document DTD, but is also useful for query evaluation beyond the security context.
Algorithm “Optimize”, is shown in one embodiment in FIG. 8 as a series of pseudo code steps 800 . Given a DTD D and a C − query p, Algorithm “Optimize(D,r,p)” rewrites p to an equivalent yet more efficient p o , where r is the root of D. The algorithm uses the following variables:
(1) For each sub-query p′ of p and each type A in the DTD D, opt (p′,A) denotes optimized p′ at A, i.e., a query equivalent to but more efficient than p′ when being evaluated at an A element. The variable is initially ‘⊥’ indicating that opt(p′,A) is not yet defined, which ensures that each sub-query is processed at each DTD node at most once.
(2) reach (p′,A) is the set of nodes in D reachable from A via p′, with an initial value φ.
(3) image (p′,A) is the image graph of p′ at A.
The algorithm also invokes the following procedures:
(1) recProc(A,B) is a mild variation of the version given in FIG. 6 . It precomputes reach (//,A) and moreover, for each B in reach (//,A), derives a query recrw (A,B) that captures all the paths from A to B. It differs from the one of FIG. 6 in that there is no need to substitute annotations for a node label.
(2) simulate(image (p 1 ,A), image (p 2 ,A)) checks whether image (p 1 ,A) is simulated by image (p 2 ,A), as described earlier.
(3) evaluate([q],A) evaluates a qualifier q at A by exploiting the DTD constraints, as given earlier.
A general description of Algorithm Optimize is seen as a series of method steps 1500 in FIG. 15 . In one embodiment of the method 1500 , Algorithm Optimize takes a DTD, an element type A in D and a query p over D as inputs and outputs in optimized query over D that is equivalent to p at the A elements. Specifically, the method begins at step 1502 and proceeds to step 1504 wherein an array variable is initialized. In one embodiment, the array is opt as described earlier. Once the initialization process is complete, the method continues to step 1506 where a determination is made as to whether the input query p is a combination of two sub-queries p 1 and p 2 . If the answer to the inquiry is yes, the method moves to step 1508 where optimization of the sub-queries p 1 and p 2 are performed by appropriate calls to the subject algorithm at elements A or elements reachable from A via the sub-queries. Once the optimization of sub-queries p 1 , p 2 are performed, the method moves to step 1510 where updating of algorithm variables are performed. In one example, the variables reach (p,A) and opt (p,A) are updated based on the form of query p. The method ends at step 1510 .
FIG. 16 details the internal circuitry of exemplary hardware that is used to execute the above-identified algorithms in the matter described to create the security views based on the security specifications and the original document DTD D. The hardware may be contained within the access control model 100 of FIG. 1 as a computer or other type of processing device or an external computing device having the necessary programming information (i.e., pseudo code of the above-identified figures) to remotely run the necessary algorithms. Specifically, the computing device comprises at least one central processing unit (CPU) 1630 , support circuits 1634 , and memory 1636 . The CPU 1630 may comprise one or more conventionally available microprocessors. The support circuits 1634 are well known circuits that comprise power supplies, clocks, input/output interface circuitry and the like. Memory 1636 may comprise random access memory, read only memory, removable disk memory, flash memory, and various combinations of these types of memory. The memory 1636 is sometimes referred to as main memory and may in part be used as cache memory or buffer memory. The memory 1636 stores various software packages that dictate security view creation based on security view specification information and the document DTD; thus, in totality, forming a special purpose machine for doing same when running said software packages or a corresponding ASIC.
Experimental results clearly demonstrate both the efficiency of the subject query rewriting approach over a straightforward query rewriting approach (that is based on element-level security annotations) as well as the benefits of the subject optimization techniques, particularly for large documents. Specifically, the subject query rewriting approach can achieve an improvement by up to a factor of 40 over naive query rewriting, which can be further improved by up to factor of 2 using the subject optimization algorithm. Experimental data sets were generated with the real-life Adex DTD, which is a standard proposed by the Newspaper Association of America for electronic exchange of classified advertisements. XML documents were generated using IBM's XML Generator tool by varying the maximum branching factor parameter to obtain four documents: D1(3.2 MB), D2(16.7 MB), D3(51.55 MB), and D4(77.0 MB). For the Adex DTD, a security view for a user was created where he is permitted to access only data related to real estate advertisements and data related to buyers. This security view is created by simply annotating the children of the root element adex as “N” and both the real-estate and buyer-info descendants as “Y” in the Adex DTD. The following four XPath queries on the Adex security view were considered:
Q1: //buyer-info/contact-info Q2: //house/r-e.warranty|//apartment/r-e.warranty Q3: //buyer-info[company-id and contact-info] Q4: //house[//r-e.asking-price and //r-e.unit-type]
where Q1 simply retrieves the contact information of all buyers; Q2 retrieves the real estate warranty information for houses and apartments; Q3 retrieves information of buyers who have both company-id and contact-info sub elements and Q4 retrieves houses that have both asking price and unit type information.
Three different approaches (naive, rewrite, optimize) were compared in these experiments, all of which are based on the use of security views for querying. The first (“naïve”) approach, which does not use DTD for query rewriting, requires the data documents to be annotated with additional element accessibility information and works as follows. A new attribute called “accessibility” is defined for each element in the XML document which is used to store the accessibility value of that element. The naive approach uses two simple rules to rewrite an input query to ensure that (a) it accesses only authorized elements and (b) it is converted to a query over the document. The first rule adds the qualifier [@accessibility=“1”] to the last step of the query to ensure (a). The second rule replaces each child axis in the query with the descendant axis to ensure (b). The second rule is necessary since an edge in a security view DTD can represent some path in the document DTD. Thus, the naive approach represents a simple rewriting approach that relies on element-level annotations instead of DTD for query rewriting. The second (“rewrite”) approach is the subject method of rewriting queries using DTD. The third (“optimize”) approach is an enhancement of the second approach that further optimizes the rewritten queries using the subject optimizations. To compare the performance of the three approaches, a state-of-the-art XPath evaluation implementation was used that has been shown to be more efficient and scalable than several existing XPath evaluators. The experiments were conducted on a 2.4 GHz Intel Pentium IV machine with 512 MB of main memory running Microsoft Windows XP.
The experimental results are shown in Table 1, where each row compares the query evaluation time (in seconds) of naive, rewrite, and optimize approaches for a given document and query. For queries that can not be further improved by the optimize approach, we indicate this with a “−” value under the optimize column.
The naive approach evaluates Q1 as //buyer-info//contactinfo[@ accessibility=“1”], while the rewrite approach utilizes the DTD to expand Q1 into a more precise query /adex/head/buyerinfo/contact-info.
The naive approach rewrites Q2 to //house//r-e.warranty [@accessibility=“1”]| //apartment//r-e.warranty [@accessibility=“1”] while the rewrite approach expands the query to /adex/body/adinstance/real-estate/house/r-e.warranty. Note that the rewrite approach has simplified the second sub-expression to empty since the r-e.warranty element is not a sub-element of apartment.
The naive approach evaluates Q3 as //buyerinfo[//company-id and //contact-info][@accessibility=“1”], while the rewrite approach expands the query to /adex/head/buyerinfo[company-id and contact-info]. The optimize approach further exploits the co-existence constraint that each buyer-info element has both company-id and contact-info sub-elements to simplify the rewritten query to /adex/head/buyer-info.
Query Q4 shows the benefit of exploiting the exclusive constraint. The rewrite approach expands the query to /adex/body/adinstance/real-estate [house/r-e.asking-price and apartment/r-e.unittype], which is further refined by the optimize approach to an empty query since the real-estate element can not have both house and apartment sub-elements; thus the evaluation of Q4 can be avoided.
TABLE 1
Query
Data Set
Naïve
Rewrite
Optimize
Q1
D1
4.12
0.44
—
D2
39.75
2.69
—
D3
416.85
12.09
—
D4
917.64
22.53
—
Q2
D1
8.49
0.54
—
D2
72.41
2.81
—
D3
916.15
11.42
—
D4
1406.56
19.16
—
Q3
D1
4.1
0.54
0.50
D2
41.20
2.92
2.67
D3
464.66
11.39
8.15
D4
1128.12
36.07
15.89
Q4
D1
3.89
0.51
0
D2
40.58
3.17
0
D3
466.61
11.31
0
D4
1021.51
38.03
0
Overall, the experimental results demonstrate the effectiveness of the proposed query rewriting technique for processing secured XML queries. The results also emphasize the importance of using DTD constraints to optimize the evaluation of XPath queries on large XML documents. Given these, Algorithm Optimize (D,A,p) rewrites query p at A elements based on the structures of p and A. It recursively prunes redundant sub-queries of p by exploiting the structural constraints of the DTD D.
Several embodiments of the present invention are specifically illustrated and/or described herein. However, it will be appreciated that modifications and variations of the present invention are covered by the above teachings and within the purview of the following claims without departing from the spirit and intended scope of the invention. | 4y
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to heavy duty pneumatic radial tires exhibiting less railway wear, and is to diminish extraordinarily irregular wear, particularly railway wear, which are apt to occur in such tires when continuously travelling at a high speed over a long distance, by an improvement of a tread in the tire.
2. Description of the Prior Art
In general, radial tires provided with at least two metal cord layers as a belt reinforcement have excellent resistance to wear, puncture and the like as compared with conventional bias tires because a highly stiff belt layer is arranged between the tread rubber and the carcass ply. On the other hand, radial tires are somewhat defective in the comfort degree owing to the rigid reinforcing effect with such belt. Accordingly, these radial tires have usually been developed for use on good roads as distinguished from unimproved ones. Recently, the demand for such tires has considerably increased in association with the remarkable improvement of road circumstances such as the development of networks of highways and the like.
In such applications, zigzag-type ribs extending circumferentially of tire are usually provided in the tread of tire. Generally, tires having such a tread pattern are called as a rib-type tire.
In the rib-type tire, ribs are usually continuous toward the circumferential direction of tire and may be discontinuous toward the circumferential direction due to the presence of traverse grooves arranged along the widthwise direction of tire. In any case, when a vehicle provided with such tires goes continuously straight on a highway at a high speed over a long distance, there are caused extraordinarily irregular wear (hereinafter referred to as eccentric wear) which have never been observed under the conventional common travelling conditions.
Namely, as shown in FIG. 1, the eccentric wear is locally caused in a shadowed region A near a top of a convex part 3 of a circumferential rib 2 formed in a tread of a tire T, said convex part being projected in a widthwise direction of the tire T toward a groove 1 extending zigzag along a circumferential direction of the tread, and then gradually increases to form a region A having stepwise height h and a width w in section as shown in FIG. 2. The region A of the eccentric wear gradually grows with the increase of the travelling distance and finally communicates with adjoining regions A. As a result, these regions are continuously joined with each other in the circumferential direction of tire T. Moreover, the stepwise height h and the width w are gradually enlarged with the increase of the travelling distance.
The above eccentric wear is generally called railway wear, which produces not only the recess of the groove 1 to render the appearance of the tire T awkward, but also considerably deteriorates the life of tire.
The eccentric wear begins to occur only in the vicinity of the top at the convex part 3 of the zigzag-type circumferential rib 2 and does not start from a concave part 4 of the circumferential rib 2 in opposition to the convex part 3 along the widthwise direction of the tire T. However, the concave part 4 is also subjected to railway wear in due time with the evolution of the eccentric wear.
SUMMARY OF THE INVENTION
It is an object of the invention to improve the form of zigzag grooves in the rib-type tire to fundamentally prevent the occurrence of such railway wear.
The inventors have pursued the cause of the railway wear with respect to heavy duty pneumatic radial tires having rib-type patterns of various sizes in order to solve the above problem. As a result, it has been found that the railway wear depends considerably upon an amplitude W 1 and a pitch P of zigzags of the groove 1.
According to the invention, there is provided a heavy duty pneumatic radial tire having a tread pattern formed in a tread divided into a plurality of circumferential ribs along a widthwise direction of tire by at least two zigzag grooves extending circumferentially of the tread, said tread being reinforced with a belt layer composed of metal cords, each of said zigzag grooves having a width, amplitude and pitch of 4.5 to 7.5%, 0.5 to 2.0% and 2.0 to 7.0%, respectively, based on a width of the tread.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in greater detail with reference to the accompanying drawings, wherein:
FIG. 1 is a partial schematic view illustrating the eccentric wear caused in the conventional heavy duty pneumatic radial tire;
FIG. 2 is a cross-sectional view taken along the line II--II in FIG. 1;
FIG. 3 is a graph showing a relation between the ratio of amplitude to tread width in the zigzag groove and the width of railway wear;
FIG. 4 is a graph showing a relation between the ratio of pitch to tread width in the zigzag groove and the width of railway wear;
FIG. 5 is a partial schematic view of an embodiment of the tread pattern according to the invention;
FIG. 6 is a partly detailed plan view of the zigzag groove according to the invention;
FIG. 7 is a cross-sectional view of the zigzag groove according to the invention; and
FIG. 8 is a partial schematic view of another embodiment of the tread pattern according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The inventors have made various studies with respect to the relation between the width w of railway wear and the ratio of amplitude W 1 to tread width B when the pitch P of zigzags of the groove is set to 11 mm in the rib-type radial tire having a size of 10.00 R 20, 14 PR and four grooves. As a result, it has been found that when the ratio W 1 /B is within a range of 0.5 to 2.0%, preferably less than 1.7%, the railway wear decreases considerably as seen from the graph of FIG. 3. When the ratio W 1 /B exceeds 2.0%, the railway wear is apt to be caused, while when the ratio W 1 /B is less than 0.5% or the edge of the zigzag groove becomes straight, the railway wear is also caused.
The term "tread width B" used herein means a ground contact width of the tire as shown in FIG. 1. Further, the degree of railway wear is generally expressed by the stepwise height h formed in the convex part 3 of the circumferential rib 2 facing to the zigzag groove 1 as shown in FIG. 2. However, since the stepwise height h and the width w are correlative with each other, the larger the stepwise height h, the larger the width w. Therefore, the inventors have evaluated the railway wear by the width w in FIG. 3.
In FIG. 4 is shown the relation between the ratio of pitch P to tread width B and the width w of railway wear when the amplitude W 1 is constant. From the result of FIG. 4, it has been found that the ratio P/B should be within a range of 2.0 to 7.0%, preferably 2.5 to 6.0% in order to diminish the railway wear. When the ratio P/B is less than 2.0%, there are many problems in the production and effect of the zigzag groove, while when the ratio P/B exceeds 7.0%, the railway wear itself increases considerably.
In the above mentioned rib-type radial tires, the number of the zigzag groove is usually at least two, preferably four. Moreover, a width W 2 of the groove should be within a range of 4.5 to 7.5%, preferably 5.0 to 7.0% of the tread width B considering the draining performance and the like during the travelling on wet road. Particularly, in case of the heavy duty pneumatic radial tires for truck and the like, the width of the zigzag groove cannot unreasonably be enlarged because it is necessary to ensure a wide area for the rib in order to improve the wear life of tire.
The width W 2 of the zigzag groove is a distance between the two sides or extention lines thereof defining the groove 1 measured in a direction perpendicular to the side of the groove as shown in FIG. 1.
The invention will be described with reference to the following examples.
In FIG. 5 is shown an embodiment of the tread pattern according to the invention wherein zigzag grooves 1 extending in a circumferential direction of tread are arranged at substantially equal intervals in a widthwise direction of tire. In the embodiment of FIG. 6 showing the enlarged groove portion of FIG. 5, the tire has the following relations, i.e. W 2 /B=6.9%, W 1 /B=1.1% and P/B=5.6%, provided that the tread width B is set to 180 mm.
Further, this tire has the following dimension and construction;
Size: 10.00 R 20 14 PR
Carcass: One ply of metal cords (Cord angle is 90° with respect to the circumferential direction of tire.)
Belt: Three layers of metal cords (Cord angle of each layer is 15° with respect to the circumferential direction of tire.)
Then, the railway wear was actually tested with respect to the above tire and the tire of the prior art (the zigzag groove having a width W 2 of 9.6 mm, an amplitude W 1 of 5.0 mm and a pitch P of 25 mm is used in accordance with the tread pattern shown in FIG. 1, i.e. W 2 /B=5.3%, W 1 /B=2.8%, P/B=13.9%) to obtain the following results.
Test conditions:
Vehicle: large-sized flat body truck
Load: maximum load
Inner pressure: 7.25 kg/cm 2
Road course: high speed road 70%, general road 30%
Speed: 80 km/hr for high speed road, 40 km/hr for general road
Travelling distance: 35,000 km
Mounting position for tire: front wheel (the tires were changed in its right and left positions every 5,000 km.)
Test result:
The degree of railway wear is measured to obtain a result expressed by h and w defined in FIG. 2 as shown in the following table.
______________________________________ h (stepwise height) w (width)______________________________________Tire of the prior art 1.2 mm 7.0 mmTire of the invention 0.4 mm 0.8 mm______________________________________
As seen from the above data, the tire of the invention considerably improves the railway wear when compared with the tire of the prior art and contributes to improve durability and tire performances in the rib-type heavy duty pneumatic radial tire by the provision of zigzag grooves extending circumferentially of tire in the shape apart from the conventional rib-type tread pattern.
In FIG. 7 is shown a cross section of a practically preferred zigzag groove 1 wherein the side wall of the groove is substantially 90° with respect to a tread outer surface over a height from the tread outer surface h 1 corresponding to at least not more than 30% of a depth H of the groove. Such a cross section of the zigzag groove 1 further diminishes the railway wear.
As shown in FIG. 8, sipes 6 may be provided in an edge 5 of a circumferential rib 2 defined between the zigzag grooves 1 extending in a circumferential direction of the tread, particularly convex parts 3, said sipes being parallel to an axial direction of tire and opened toward the groove 1, whereby the wet performance of tire can be further improved.
In the sipe 6, the opened width is preferably 0.3 to 1.0 mm, the depth is preferably not less than 50% of the depth of the groove, and the length in the axial direction of tire is preferably within a range of 75 to 150% based on the amplitude W 1 of the groove 1. Moreover, the sipes 6 are usually located at intervals corresponding to the zigzag pitch P in the circumferential direction of tire or may be arranged in concave parts 4 of the circumferential rib 2 or at a middle position between the convex part 3 and the concave part 4. In any case, when the length of the sipe 6 is too long, the wet performance is improved, but an eccentric wear known as heal-and-toe wear is caused in the tread portion around the sipe 6, so that the use of the very long sipe 6 is not favorable.
As mentioned above, according to the invention, eccentric wear, particularly railway wears in the heavy duty pneumatic radial tires can considerably be diminished. | 4y
|
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application serial No. 60/218,871, filed Jul. 18, 2000.
STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT
The U.S. Government has a paid up license in this invention and the right in limited circumstances to require the patent owner to license others on reasonable terms as provided for by the terms of Program Solicitation Number DE-PS26-99FT40613 awarded by the U.S. Department of Energy.
REFERENCE TO A “MICROFICHE APPENDIX”
(Not Applicable)
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to gas cleaning systems, and more specifically to a biologically-based absorbing apparatus and method to reduce emissions from fossil burning units.
2. Description of the Related Art
The U.S. produces an estimated 1.7 billion tons of CO 2 annually from the combustion of fossil fuels. CO 2 is a reflector of infrared radiation, so its presence helps “keep” heat in the atmosphere, making the surface temperature warmer than if there was no CO 2 in the atmosphere. It is estimated that at present growth rates, CO 2 levels in the atmosphere will increase from 350 ppmv (at present) to 750 ppmv in as little as 80 years. In fact, to level CO 2 concentrations at 550 ppmv, we will have to reduce net CO 2 emissions by over 60% from 1990 levels during the next 100 years.
Even if an expensive option for CO 2 removal is discovered, which is by no means a certainty, CO 2 “disposal” is problematic. U.S. industries consume only 40 million tons of CO 2 , produced at a much lower price than possible by removing CO 2 from flue gas. Therefore, increased consumption of CO 2 appears limited, and options for expanded use appear limited and costly.
Sequestration of CO 2 in large bodies of water or in deep mines appears to be the most viable present option. However, sending CO 2 into the ocean or an abandoned mine is a limited solution. There is no known exact time scale for storage of CO 2 ; it may be centuries, but it also may only be decades. At best, these are temporary solutions. Further, the transportation issues are considerable, even for the less than 30% of all U.S. fossil-fuel burning power plants that are within 100 miles of an ocean. Existing power plants, with capital values in the hundreds of billions of dollars, are at risk if tens of thousands of miles of specialized pipelines must be installed to transport separated CO 2 .
The use of ocean-based sinks could present significant problems. It will be necessary to add large amounts of iron to the ocean to use the vast quantities of CO 2 stored in the sinks, resulting in uncontrolled growth of certain organisms. Weed plankton, the most likely organisms to grow, will not provide sufficient nutrients for the food webs, and there is a high probability of significant negative environmental impact. In the case of CO 2 stored at the bottom of the ocean in lakes, the adverse effects on the ocean-floor ecosystem cannot be predicted, but are likely to be considerable.
Another existing option involves biological carbon sequestration in outdoor ponds. However, there are inherent inefficiencies related to this solution for CO 2 sequestration, primarily due to the amount of cyanobacteria that can be grown in a given volume. For example, if 2,000,000 m 2 of photosynthetic surface area is required for 25% reduction of CO 2 emissions from a power plant, that is equivalent to almost 500 acres of surface. Very few existing plants have 500 acres available to them and fewer could afford to convert 500 acres to a shallow lake or raceway cultivator. Also, there are serious questions about how to distribute the flue gas (or separated CO 2 ) into the lake for maximum growth, not to mention what to do with the gas once it bubbles to the surface. The flue gas would have to be collected again and redirected up a stack to meet other emission requirements. Further, maintaining such a large “lake” during a Midwestern winter would be problematic.
Clearly, other approaches for CO 2 control are needed. Research to develop a robust portfolio of carbon management options, including safe and effective photosynthetic carbon recycling, will enable continued use of coal in electrical power generation. Despite the large body of research in this area, virtually no work has been done to create a practical system for greenhouse gas control, one that could be used with both new and existing fossil units.
BRIEF SUMMARY OF THE INVENTION
A method for removing a carbon-containing compound from a flowing gas stream is performed by interposing in the stream a membrane having photosynthetic microbes, such as algae and cyanobacteria, deposited thereon. Applying water and nutrients to the membrane sustains the growth of the microbes, and increasing the volume of water harvests the microbes from the membrane.
The invention also contemplates an apparatus for removing a carbon-containing compound from a flowing gas stream has a membrane interposed in the stream. The membrane has photosynthetic microbes, such as algae and cyanobacteria, deposited thereon.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a diagram illustrating the carbon sequestration process.
FIG. 2 is a front view illustrating a membrane.
FIG. 3 is a diagram illustrating a solution supply and recirculation system.
FIG. 4 is a diagram illustrating a flue gas flowing over membrane.
FIG. 5 is a side view in section illustrating the membrane arrangement in the hydrating solution delivery system.
In describing the preferred embodiment of the invention which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. For example, the word connected or term similar thereto are often used. They are not limited to direct connection, but include connection through other elements where such connection is recognized as being equivalent by those skilled in the art.
DETAILED DESCRIPTION OF THE INVENTION
Enhanced natural sinks are the most economically competitive and environmentally safe carbon sequestration options for fossil-fuel burning power plants, because they neither require pure CO 2 , nor incur the costs (and dangers) of separation, capture, and compression of CO 2 gas. Among the options for enhanced natural sinks, optimizing the growth of existing photosynthetic organisms in an engineered system is low risk, low cost, and benign to the environment. Additionally, an engineered photosynthesis system has the advantage of being at the source of the emissions to allow measurement and verification of the system effects, rather than being far removed from the emissions source, as is the case with forest-based and ocean-based natural sinks. The invention is suitable for application at existing and future fossil units.
Even though CO 2 is a fairly stable molecule, it is also the basis for the formation of complex sugars (food) through photosynthesis in green plants, algae, and cyanobacteria. The relatively high content of CO 2 in flue gas (approximately 14% compared to the 350 ppm in ambient air) has been shown to significantly increase growth rates of certain species of cyanobacteria. Therefore, this photosynthetic process is ideal for a contained system engineered to use specially selected strains of cyanobacteria to maximize CO 2 conversion to biomass and emitting less of the greenhouse gas to the atmosphere. In this case, the cyanobacteria biomass represents a natural sink for carbon sequestration.
A diagram of the well-understood process of photosynthesis is shown in FIG. 1 . Photosynthesis reduces carbon by converting it to biomass. As shown in FIG. 1, if the composition of typical cyanobacteria (normalized with respect to carbon) is CH 1.8 N 0.17 O 0.56 , then one mole of CO 2 is required for the growth of one mole of cyanobacteria. Based on the relative molar weights, the carbon from 1 kg of CO 2 could produce increased cyanobacteria mass of 25/44 kg, with 32/44 kg of O 2 released in the process, assuming O 2 is released in a one-to-one molar ratio with CO 2 . A conservative estimate indicates that a 2,000,000 m 2 facility powered by collected solar energy could process 25% of the effluent CO 2 from a 200 MW coal-fired power plant, producing over 140,000 tons of dry biomass per year. Dried biomass could be used in the production of fertilizer, fermented or gasified to produce alcohols and light hydrocarbons, or directly as a fuel to meet biomass mandates in pending deregulation legislation. Therefore, a photosynthetic system provides critical oxygen renewal along with the recycling of carbon into potentially beneficial biomass.
Optimization of this process in the present invention is based on design of a mechanical system to best utilize photosynthetic microbes. Photosynthetic microbes are microorganisms, such as algae and cyanobacteria, which harness photons to fix carbon-containing gas into carbon-based biomass. Cyanobacteria have been chosen as photosynthetic agents, because they are one of only two groups of organisms capable of growing at the fossil-fired environmental temperatures of 50-75° C. For example, Cyanidium calderium has been shown to be able to fix CO 2 under the conditions of the flue gas remediation apparatus at 70-75° C. and below. Cyanobacteria are small in size and grow attached to sediment particles in thermal streams. This is an essential property for growth in a fixed cell bioreactor. Another advantage to using cyanobacteria is amenability to manipulation in the laboratory and thus to a power plant setting. Cyanobacteria in general are mechanically robust making them ideal organisms for use in bioreactors.
Referring to FIG. 2, the photosynthetic microbes populate a growth surface 10 , which is composed of a membrane 14 fastened within a frame 12 . The information contained in U.S. Patent Application Serial. No. 60/258,168 to Pasic, et al., is incorporated herein by reference. The growth surface 10 shown in FIG. 2 is rectangular, and the membrane 14 is twenty-one inches long by ten and one-half inches wide, mounted in a frame one half inch thick. However, the size of the membrane 14 may vary depending on the requirements of the power plant in which the inventive apparatus is applied.
The material selection for the membrane 14 is dictated by the mechanical properties necessary for the optimal design in a containment chamber 16 shown in FIG. 3 . The membrane 14 should be an inorganic material, such as plastic, to avoid problems with fungi growth. The membrane 14 must be composed of a material that suits the specific microbe used, being non-toxic to the microbe and supporting adhesion. It is essential that microbes supplied to the growth surface 10 be able to grow in the attached state. The growth surface 10 needs to provide reliable structural integrity when exposed to the flue gas environment.
The cyanobacteria are distributed evenly over the membrane 14 to maximize the photosynthetic surface area. Directly pouring a microbial solution over the membrane 14 , applying the solution using a pump or an organism-entrained water flow through the membrane accomplishes even distribution.
The growth surface 10 is introduced to a carbon-containing gas 21 when placed in the containment chamber 16 , which is in the flow path of the gas 21 as shown in FIG. 4. A light source 20 for the microbes uses fiber optics to supply photons for driving photosynthesis. The light source 20 may be positioned above the chamber 16 as in FIG. 4, or in a position relative to the membrane 14 to optimize cyanobacterial growth and carbon dioxide uptake.
In FIG. 4, each growth surface 10 is oriented in the containment chamber 16 . The growth surface 10 can be oriented at an angle of ninety degrees relative to the chamber 16 , but the angle may vary depending on the needs of a specific unit. The growth surfaces 10 may be fixed in place within the chamber 16 , movable in increments, or continuously movable to optimize exposure to the flue gas. The orientation of the growth surface 10 provides minimum power loss due to flow obstruction when in the containment chamber 16 .
Experiments were performed at Ohio University using an experimental system called a Carbon Recycling Facility (CRF), which simulates a flue gas environment by having the membrane 14 populated with microbes and contained as shown in FIG. 4 . Experiments include weight and visual analysis of the algae grown and harvested.
Harvesting is the removal of mature photosynthetic microbes from the membrane 14 of the growth surface 10 . Harvesting is advantageous, because the rate of carbon dioxide consumption decreases as the growth rate of cyanobacteria slows. Therefore, harvesting cyanobacteria to make space for further growth maximizes carbon dioxide uptake. The harvesting method involves flushing the membrane 14 at periodic intervals with a large volume of liquid. The momentum from the large volume of flushing liquid is sufficient to overcome adhesive forces that hold the microbes on the membrane, so many of the microbes are displaced from the membrane 14 .
Harvesting occurs in the containment chamber 16 by a differential pressure water supply system, which functions as a nutrient delivery drip system at low delivery pressures and algal harvesting system at high delivery pressures. Under normal conditions the membrane 14 is hydrated by capillary action. Under harvesting conditions, the fluid delivery action is increased, creating a high flow sheeting action that displaces a substantial percentage of the microbes from the membrane 14 .
FIG. 5 shows the preferred arrangement for the manifold water delivery system within the containment chamber 16 . A pipe 25 receives the growth solution from the supply line 36 . The solution flows to the membrane 14 through an opening 27 in the pipe 25 . As shown in FIG. 5, in the preferred embodiment an edge of the membrane 14 is held in contact with the inside of the pipe 25 , and the rest of the membrane 14 is draped through the opening 27 . Because the membrane has capillary passages through which the solution can flow, the solution never has to be sprayed if spraying is desired to be avoided. Instead, capillary flow can supply solution to the algae through the membrane.
Harvesting that results in partial cleaning of the membrane 14 is preferred. Partial cleaning means that after cleaning, enough cyanobacteria remain adhered to repopulate the membrane 14 . This is desirable to avoid a growth lag, thereby maximizing carbon dioxide uptake in the system. The harvested cells accumulate in a slurry at the bottom of the containment chamber 16 . The harvested cells are removed, and fresh growth solution is applied to the young cells that remain on the membrane 14 .
In an alternative embodiment shown in FIG. 3, harvesting is accomplished by administering water and the growth medium by a nozzle 19 , either separately or by the same nozzle 19 . Harvesting by this method is accomplished through a stream of pressurized water that flows out the nozzle 19 and onto the membrane 14 . The force of the impact dislodges the cyanobacteria from the membrane 14 . Sufficient cleaning occurs when the water stream is set at a shallow incidence angle and a relatively low velocity, for example between 30 and 40 degrees relative to the growth surface 10 . A 90-degree low-flow, full cone whirl nozzle provides a good balance between covering a large area with the water jet, and a gentle partial cleaning. A flat-fan nozzle is also effective when swept or rotated across the coverage area.
Alternatively, or in addition, a solution may be used to chemically promote removal of the microbes from the membrane 14 . Most microorganisms have a cation requirement for adhesion, usually calcium (Cooksey and Wigglesworth-Cooksey, 1995). Thus, they can be removed from a surface with calcium ion-complexing agents such as EDTA or EGTA (Cooksey and Cooksey, 1986).
The partially cleaned membrane 14 can be repopulated with actively growing cells removed while cleaning the membrane 14 . After cleaning, the slurry of cells and growth solution is agitated to disperse any clumps of algae into individual cells. Then, selective filtration of the slurry separates the large microbial cells that are old or dead from the small cells that are young and alive, and the young actively growing cells are reapplied to the growth surface 10 to repopulate the membrane 14 .
In the alternative embodiment shown in FIG. 3, the microbes washed from the membrane 14 may be removed, and the growth solution may be recirculated to the membrane 14 after harvesting. A recirculation system can continuously administer the growth solution to the microbes, while they are subjected to the high temperature gas flowing through the containment chamber 16 . As shown in FIG. 3, a growth solution dripping manifold 18 is located at the top of the containment chamber 16 . The manifold 18 continuously delivers the growth solution to the algae through a solution supply line 36 , through which a solution supply-isolating valve 37 regulates the flow of solution. The growth solution accumulates at the bottom of the containment chamber 16 .
The growth solution flows from the containment chamber 16 through a drain line 22 . A drain-isolating valve 24 regulates the flow, and the solution is drained into a lower holding tank 26 . A pump isolation valve 28 opens a solution recirculation pump 30 and draws the growth solution from the lower holding tank 26 , through an inline filter 33 , and upwardly to the upper holding tank 38 .
The growth solution is pumped into the upper holding tank 38 , where a float 39 and a level switch 40 regulate the level of growth solution inside. An electric signal line 34 leads from the level switch 40 to the solution recirculation pump 30 , which is activated when the solution reaches a predetermined level in the upper holding tank 38 . The level of solution in the upper holding tank 38 is maintained constant by the level switch 40 and the recirculation pump 30 .
An alternative or additional step in the process may include nutrient enhancement and delivery. Cyanobacteria mostly easily fix carbon and nitrogen in aqueous form. One possible way to increase carbon and nitrogen content is to use technology known as translating slug flow. Using translating slug flow technology increases concentrations of nutrients, lowers flue gas temperatures, and increases humidity. Slugs create zones of greatly enhanced gas-liquid mass transfer, putting CO 2 and NOx into the water as soluble species for the cyanobacteria. Optimal levels of these nutrients maximize cyanobacterial growth.
The cyanobacteria react positively to the conditions established by a translating slug flow reactor immediately upstream of the bioreactor. Translating slugs, which have leading edges of greatly enhanced mass transfer, increase the content of soluble carbon and nitrogen in the liquid used to grow the cyanobacteria. Slugs result when the gas to liquid flow reaches unstable conditions in nearly horizontal pipes. In fact, a slight vertical inline can substantially increase slug frequency and thus increase the rate at which CO 2 is transferred to the water.
The process of inducing slug flow (gas-liquid mass transfer) results in vastly enhanced CO 2 absorption in the water used to grow the cyanobacteria, and it produces several other advantages. By absorbing CO 2 in the water in the slug flow reactor, the flue gas might never need to come directly in contact with the bioreactor. If the CO 2 is already in solution, then some cyanobacteria do not require gaseous CO 2 for photosynthesis. This offers the advantage of using less thermo tolerant cyanobacteria, because the water temperature from the slug flow reactor is between 35-40° C. If a dual CO 2 delivery method is used (some in the aqueous phase, some in the gaseous phase), the interaction of large volumes of cooled water with the flue gas, and the subsequent saturation of the growth surfaces with the enhanced level of soluble carbon and nitrogen increases growth rate of the photosynthetic organism.
The use of mature cyanobacteria is an advantage to using this process. Mature cyanobacteria can produce value-added products and energy. One advantageous use for the post-processed cyanobacteria is in the combustion of cyanobacteria and coal as a blended fuel in fluidized bed combustion to power Stirling cycle free piston engines. With pending electric deregulation legislation requiring as much as 7.5% utilization rate of biomass, a viable biofuel and method for utilizing that fuel needs to be found. Dried cyanobacteria have been shown to have a suitable higher heating value, high volatile content, and have suitable ignition characteristics to be co-fired with coal in pulverized coal-fired generation units.
Another benefit is oxygen production. Oxygen is a natural product of photosynthesis. If it is assumed that 1 mole of O 2 is formed for each mole of CO 2 consumed during photosynthesis, then for every kg of CO 2 consumed, (32/44) or 0.73 kg of O 2 are produced. This is a significant benefit.
Another benefit is the potential for reduction of other pollutants, sulfur and nitrogen species. In fact, work by Yoshihara et al. (1996) shows considerable nitrogen fixation from NOx species bubbled through a bioreactor, one with poorer mass transfer characteristics than would be found in the process described here.
While this process claims carbon sequestration as its goal, carbon is actually being recycled in this process. Carbon recycling is fundamentally different than sequestration, with several advantages. In sequestration, the carbon is no longer available for use. While CO 2 use for enhanced oil recovery has a benefit, CO 2 or carbon has little use in other forms of sequestration. With photosynthetic carbon recycling, useful carbon-containing biomass and oxygen are produced from the carbon dioxide. As described, biomass has a number of beneficial uses, including as a fuel to offset the use of fossil fuels, as a soil stabilizer, fertilizer, or in the generation of biofuels (such as ethanol or biodiesel) for transportation use. In addition, the light collection and transmission system designed for the preferred embodiment provides additional electrical power (using the previous example parameters) by converting a portion of the filtered infrared spectrum using photovoltaics.
A first experiment was performed at 120° F. under controlled parameters of CO 2 concentration. Experiment I was illuminated at 18.25 μmol-s −1 m −2 measured at the base of the experimental containment after the algae samples were loaded over the screens in the containment. Again the amount of algae sample loaded over each screen was 3000 ml giving total loading of 12000 ml in the reactor. Table 1.1 gives the weight analysis of 25 ml samples drawn through paper filters for calculation of the weight of algae used for testing.
TABLE 1.1
Dry weight analyses for test samples for Experiment I.
Filter
Weight before
Weight after
Number
Volume
filtering sample
filtering sample
Difference
#1
25 ml
1.7282 gm
1.7435 gm
0.0153 gm
#2
25 ml
1.6294 gm
1.6455 gm
0.0161 gm
#3
25 ml
1.8189 gm
1.8368 gm
0.0179 gm
#4
25 ml
1.7889 gm
1.8066 gm
0.0177 gm
#5
25 ml
1.7488 gm
1.7663 gm
0.0175 gm
Total =
125 ml
0.0845 gm
The effective amount of algae loaded was 8.112 gm. The simulated flue gas at 120° F. contained 10.0% O 2 , 5.7% CO 2 , 700 ppm CO, 1.87 slpm natural gas and 23.92 slpm air.
The light intensity passing through the containment was measured (at the bottom of the reactor), as shown in Table 1.2.
TABLE 1.2
Light intensity passing through the containment for Experiment I.
Time
Light intensity
(hours)
mV
umol-s −1 m −2
0
48.7
18.25
21
51.2
19.19
45
57.6
21.58
58
67.8
25.41
70
79.2
29.68
77
83.8
31.41
83
88.1
33.02
93
89.8
33.65
97
91.6
34.33
109
92.6
34.70
118
93.6
35.08
120
94.2
35.30
The Difference in dry weight of four numbers of screens and inline filter was calculated and effective weight was compared with the weight of algae samples loaded. Table 1.3 tabulates the measured dry and differential weights.
TABLE 1.3
Weight analysis of screens and filter for Experiment I.
Before trial
After trial
Difference
Screen #1
149.1 gm
150.5 gm
1.4
gm
Screen #2
155.6 gm
157.3 gm
1.7
gm
Screen #3
149.7 gm
151.3 gm
1.6
gm
Screen #4
151.7 gm
151.4 gm
−0.3
gm
Filter
189.1 gm
193.6 gm
4.5
gm
Total = 8.9
gm
It was observed during the experiment that Nostoc 86-3 did not change color and remained green, but with reduced density on the screens. In addition, the amount of light intensity passing through the containment showed a continuous rise with time. The observation also supports the decrease in micro algae density as more light passed over the screens. However, the amount of cyanobacteria obtained after trial was more than that initially loaded, indicating a positive growth.
Experiment II was conducted at 120° F. under an illumination of 22.11 μmol-s −1 m −2 measured at the base of the experimental containment chamber after the algae samples were loaded. Again the amount of algae samples loaded over each screen was 3000 ml giving total loading of 12000 ml in the reactor. Table 2.1 displays the weight analysis of 25 ml samples drawn through paper filters for calculation of the weight of algae for testing.
TABLE 2.1
Dry weight analysis for test samples for Experiment II.
Filter
Weight before
Weight after
Number
Volume
filtering sample
filtering sample
Difference
#1
25 ml
1.7666 gm
1.7921 gm
0.0255 gm
#2
25 ml
1.7011 gm
1.7266 gm
0.0255 gm
#3
25 ml
1.7402 gm
1.7668 gm
0.0266 gm
#4
25 ml
1.8402 gm
1.8677 gm
0.0275 gm
#5
25 ml
1.6527 gm
1.6778 gm
0.0251 gm
Total =
125 ml
0.1302 gm
The effective amount of algae loaded was 12.500 gm. The simulated flue gas at 120° F. contained 9.5% O 2 , 6.0% CO 2 , 500 ppm CO, 1.73 slpm natural gas and 21.33 slpm air.
For this experiment, the illumination was maintained under ON-OFF mode (12 hour cycle) to support the light and dark reactions of cyanobacterial photosynthesis. The light intensity passing through the containment was measured after every 12 hours (at the bottom of the reactor), as shown in Table 2.2.
TABLE 2.2
Light intensity passing through the containment for Experiment II.
Time
Light intensity
(hours)
mV
umol-s −1 m −2
0
48.7
18.25
12
74.6
27.96
24
73.4
27.51
36
76.4
28.64
48
77*7
29.12
60
77.5
29.05
72
74.0
27.74
84
80.4
30.14
96
84.5
31.67
108
88.6
33.21
After 120 hours the growth screens and filter were removed and dried. Table 2.3 tabulates the measured dry and differential weights.
TABLE 2.3
Weight analysis of screens and filter for Experiment II.
Before trial
After trial
Difference
Screen #1
146.8 gm
151.1 gm
5.3
gm
Screen #2
148.1 gm
151.5 gm
3.4
gm
Screen #3
150.1 gm
152.8 gm
2.7
gm
Screen #4
148.3 gm
151.1 gm
2.8
gm
Filter
137.6 gm
145.9 gm
8.3
gm
Total = 22.5
gm
The light intensity passing through the containment showed a continuous but gradual rise in jumps at various intervals. It was also observed that the Nostoc 86-3 changed color to light brown. Cellular study testified that the species were of consistent size with the batch culture of algae and maintained the filamentous morphology of Nostoc. The species were found to be maintaining healthy coloration and were not dying. These results indicate that species Nostoc 86-3 can tolerate 120° F. as observed from the color of the samples after the experiment.
While certain preferred embodiments of the present invention have been disclosed in detail, it is to be understood that various modifications may be adopted without departing from the spirit of the invention or scope of the following claims. | 4y
|
RELATED APPLICATION
This application claims the benefit of prior U.S. Provisional Patent Application Ser. No. 60/066,771 filed Nov. 24, 1997.
FIELD OF THE INVENTION
The present invention relates generally to monitoring and controlling therapeutic beds and mattress systems. More particularly, the invention relates to a system and methods for detecting and monitoring the distance between a patient and a reference point on a mattress and for controlling the mattress in relation to such distance.
BACKGROUND OF THE INVENTION
For years those who suffer from limited mobility due to age, disease or immobilizing physical condition have sought relief from decubitus ulcers, cramping and discomfort as a result of being bedridden for long periods of time. A wide range of therapeutic supports for bedridden patients, such as inflatable mattresses, mattress overlays and mattress replacements, have been made commercially available in the United States. One such support is commercially available from Kinetic Concepts, Inc. (of San Antonio, Tex.) under the “TheraKair” designation, as a mattress which provides pulsating action through inflatable support cushions as described in U.S. Pat. No. 5,267,364.
Therapeutic mattresses are often designed to reduce “interface pressures,” which are the pressures that are exerted by a mattress on skin of the patient (or vice versa) while the patient is lying on the mattress. Given time, elevated interface pressures can reduce local blood circulation around the skin and, as a result, may contribute to bedsores and other complications. With inflatable mattresses, as the inflation air pressure decreases, a patient's susceptibility to encountering elevated interface pressures also tends to decrease, thereby reducing the likelihood that the patient will develop bedsores.
A problem with deflation, however, is the increased risk of “bottoming-out”, which is a widely known effect where the upper surface of an air mattress converges and comes into direct contact with the lower surface. Bottoming out can negate much of the benefit of an air mattress by increasing the patient's pressures at the point of bottoming-out and, therefore, increase the risk of bedsores. Abrupt bottoming-out, such as when the patient is initially positioned on the mattress, could increase the risk of further injury to an already frail, bedridden patient. There has been a long felt need to have an inflatable mattress which self-adjusts the air pressure in inflatable cushions for optimal therapeutic purposes while significantly diminishing the risks of bottoming-out.
Some concepts of regulating air supply within a mattress for the prevention of bedsores and some concepts for the mitigation of bottoming-out effects are known. For example, U.S. Pat. No. 4,694,520 describes methods for detecting inadequate inflation while the patient is situated on the mattress. By contrast, the present invention detects the patient not only when positioned on the bed but also before the patient is even placed on the bed, thereby preventing the risks of rapid bottoming-out by “pre-inflating”.
U.S. Pat. No. 4,873,737 provides for the detection of mattress thickness to supply a mean air pressure while the patient is situated thereon.
U.S. Pat. Nos. 4,745,647 and 4,768,249 provide force activated sensors to detect whether a patient has bottomed-out on a mattress but does not contemplate detecting the patient as the patient nears the bed.
U.S. Pat. No. 4,542,547 provides for mattress inflation through the detection of reflected and pulsed light while the present invention, by contrast, detects diffuse light.
SUMMARY OF THE INVENTION
It is an object of the present invention to enhance patient care and to overcome the obstacles and inadequacies of the prior art.
The present invention includes features and/or components that have been invented or selected for their individual and combined benefits and superior performance as an apparatus and a method for minimizing patient interface pressures by sensing patient distance and, if necessary, adjusting that distance to some predetermined or calculated level to optimize the therapeutic effects of the patient's mattress. The system is a combination of components and methods that together have new and novel features. Each of the individual components work in association with the others and are optimally mated for performances.
The present invention circumvents current laborious requirements of manually adjusting a mattress for optimal therapeutic inflation or allowing a patient to be filly positioned on the bed before sensing means are activated. The present invention offers a unique “hands-free” approach to controlling a mattress's air supply while a patient is lying thereon. Through the use of a heterodyning proximation detector similar benefits are achieved even before a patient lies upon the mattress. With such benefits there is less need for extra personnel and training costs to operate a mattress's air supply system. In addition, the present invention further reduces any risks for rapidly bottoming-out as a patient is initially placed on a mattress. Accordingly, the heterodyning proximation detector detects a patient as the patient nears a mattress and allows for air supply in the mattress to be increased before the patient is ever positioned atop the mattress.
The heterodyning proximation detector is an improved version of a somewhat obscure musical instrument that had been developed in the United States during the 1920s called a “Theremin”. The present invention improves on the musical instrument's ability to sense a human's natural reactance, or electrical characteristics, and applies this improvement to therapeutically regulating an air mattress. The heterodyning proximation detector is effectively an antenna referenced to a conducting plate with a large surface area that variably responds to the dielectric constants of different materials. The heterodyning proximation detector may also be used to control air supply while the patient is on the mattress along with, or separately from, a force-responsive distance sensing apparatus or a light-responsive distance sensing apparatus, thus reducing the risks for gradual bottoming-out as well.
Aspects of the present invention feature a force-responsive distance sensing apparatus for continuously determining how high the patient is being supported on the mattress in real-time while the patient is on the mattress. The depth that the patient sinks into the mattress is used for controlling air supply to the mattress. The patient's height (or depth) distance is represented as variations in height of a compliant, force transmitting member that is placed relative to the mattress. Thus, a change in height of the patient generates a change of force applied to a force sensitive component coupled to the force transmitting member.
Other aspects of the present invention relate to a light-responsive distance sensing apparatus using either visible light or infrared radiation. The mattress upon which the patient rests may be physically divided into sections, such as independently inflatable air-cells, or logically divided into sections, where no physical barrier isolates the air inside the mattress. A section, logical or physical, of the mattress's initial shape becomes deformed in response to a patient being set atop the air mattress. A light emitter and light detector are situated in a fashion such that a deformation in the mattress shape reduces the amount of light that reaches the detector from the emitter, thereby generating a control signal to adjust the air pressure within the mattress accordingly. The preferred embodiments contain certain elements which include, but are not limited to:
a frame for supporting a mattress;
a therapeutic mattress set upon the frame where both frame and mattress cooperate in tandem to define a therapeutic bed;
a controlled air supply for selectively inflating one or multiple air cells upon receiving data relating directly or indirectly to the height of the patient relative to the bottom of the air mattress.
In one preferred embodiment, a heterodyning proximation detector is significantly influenced by the reactance of certain objects within a known distance of the detector. Such an embodiment depends on the electrical signature left by the particular dielectric constant of that object and the field pattern of the heterodyning proximation detector. In particular, the heterodyning proximation detector is either a conducting plate or wire referenced to a ground plane that is responsive to a body's natural reactance and, thus, functions as an antenna. The antenna is variably connected to a tank circuit having a capacitor and a variable inductor. A frequency oscillator is operatively connected to the tank circuit as well. Thus, as a body nears the antenna, the body's reactance changes the electrical fields induced into the antenna, resulting in a change in the natural frequency of the oscillator. Accordingly, the frequency signal ultimately generated by the heterodyning proximation detector is used by control circuitry to create a signal which, in turn, controls a blower or regulating valve. The blower is then connected to at least one of the air cells or sections that comprise the mattress. Another embodiment of the apparatus contemplates an array of air cells each with a heterodyning proximation detector and a blower or regulating valve that is responsive to the individual reactance signatures emitted by particular segments of the body.
One embodiment includes a force-responsive distance sensing apparatus. The force-responsive distance sensing apparatus comprises a force transmitting member and a force sensing element, which might be a force-sensitive resistor, piezoelectric crystal, or the like, coupled with the force transmitting member. In operation, the force-responsive distance sensing apparatus is placed relative to the mattress so that it is responsive in real-time to the compressive forces that are continuously generated by the patient when the patient is on the mattress. When a patient lying on the mattress has compressed it to the point of bottoming, the force transmitting member is subjected to the maximum amount of loading that is exerted by the patient on the mattress, whereas an uncompressed, fully inflated mattress signifies minimum or no loading on the force transmitting member. In turn, a force sensing element that is coupled to the force transmitting member detects a range of height distance in real-time as a variable range of compression exerted thereon by the force transmitting member. However, compression of the force transmitting member is not necessarily linearly scaled between the maximum and minimum distances of the patient relative to frame; e.g., compressive forces from the force transmitting member might not be generated until the mattress thickness is compressed to some predetermined ratio of the original thickness.
Ultimately, a resulting signal from the force sensing element that is related to the compressive forces exerted on the element of the force transmitting member is sent to a controller and compared to a preset calibrating signal. The signal is then converted into a control signal which is sent to a blower or regulating valve. The controller might also be set to work with a microprocessor to store and compare various voltage values.
One embodiment includes a light-responsive distance sensing apparatus. The light-responsive distance sensing apparatus comprises a deformable container, inflatable chamber, or the like, having a sealed inner surface that is constructed of light diffusing material. A light emitter and a light detector are attached to the air cell at different locations. In operation, as a patient is set atop the air mattress, the initial shape of the air cell becomes deformed due to the compressive forces exerted by the patient thereon. Thus, any deformation of the container's inner surface between the light emitter and light detector would scatter light so that, ultimately, less light would be received and detected by the light detector than what light was initially emitted when the air cell was not subject to compressive forces. The resulting output signal from the light detector is sent to a controller and compared to a calibrated reference signal. The controller may then emit a control signal that indicates a significant disparity in the air supply within that air cell or mattress section to a blower or regulating valve to increase air supply.
One particular embodiment provides a therapeutic mattress for controlled support of a patient, the mattress comprising at least one inflatable chamber having a first translucent portion for the introduction thereto of light energy and a second translucent portion for the passage therethrough of light energy; a source of light energy adapted to introduce light energy through the first translucent portion into the interior of the inflatable chamber; and a receiver of light energy adapted to receive light energy through the second translucent portion from the interior of the inflatable chamber, the receiver being adapted to generate a signal indicative of the quantity of light so received. The first and second translucent portions are preferably disposed on opposing sides of the inflatable chamber. The inflatable chamber also has one or more pouches to secure the source and/or the receiver to the chamber. Preferably, the pouch also has a releasable closing to facilitate insertion and removal of the source and/or receiver. The pouch optionally also has an opaque portion to conceal the source and/or receiver secured within the pouch and a reflective portion to facilitate the transfer of light energy through the chamber. Cushioning material, such as foam, plastic, or cloth batting, is optionally disposed within the inflatable chamber to provide extra support cushioning to the patient. The chamber optionally also includes an air permeable portion to facilitate a gradual flow of air out of the chamber, and a water permeable portion to draw moisture away from the patient.
Another embodiment provides a therapeutic mattress for controlled support of a patient, the mattress comprising a plurality of inflatable chambers each having a light-scattering inner surface; a first of the inflatable chambers having a first light emitter and a first light detector; a second of the inflatable chambers having a second light emitter and a second light detector; and first and second pouches adjacent opposite sides of each of the first and second inflatable chambers. The first light emitter is disposed within the first pouch of the first chamber and is adapted to introduce light energy, preferably infrared light, into the interior of the first chamber. The first light detector is disposed within the second pouch of the first chamber and is adapted to receive light energy from the interior of the first chamber and generate a signal indicative of the quantity of light energy received. The second light emitter is disposed within the first pouch of the second chamber and is adapted to introduce light energy into the interior of the second chamber. The second light detector is disposed within the second pouch of the second chamber and is adapted to receive light energy from the interior of the second chamber and generate a signal indicative of the quantity of light energy received. Furthermore, the mattress is provided with a source of pressurized fluid in communication with the first and second inflatable chambers, the source being adapted to control inflation of the first chamber according to the signal generated by the first light detector, the source being further adapted to control inflation of the second chamber according to the signal generated by the second light detector. Inflation of the first and second inflatable chambers is controlled to minimize interface pressures between the therapeutic mattress and a patient lying on the mattress while simultaneously maintaining sufficient air pressure to prevent the inflatable chambers form bottoming out.
Other embodiments may include other distance sensing mechanisms either alone or in combination with the heterodyning proximation detector, force-responsive distance sensing apparatus or the light-responsive distance sensing apparatus, adapted to assist in controlling and monitoring the air supply of the mattress.
The invention may take the form of a method for regulating inflation within a mattress assembly or overlay. Such a method can be used to better accommodate a wide range of patient body sizes. The preferred method includes the following steps:
1. deflating the mattress and measuring and storing the height distance from a heterodyning proximation detector to a patient while the mattress is deflated;
2. initiating inflation of the mattress as the patient nears the heterodyning proximation detector;
3. placing the patient on the mattress and continuing to increase the air supply of the mattress until fully inflated.
4. measuring and storing the output signal or signals from the heterodyning proximation detector, force-responsive distance sensing apparatus, light-responsive distance sensing apparatus, or any combination of these while the mattress is fully inflated with a patient on top of the mattress;
5. calibrating the optimal height distance for that particular patient using the stored signals from the deflated and fully inflated positions;
6. monitoring and controlling air supply to the mattress based on the determined optimal height distance using the heterodyning proximation detector, force-responsive distance sensing apparatus, light-responsive distance sensing apparatus, or any combination of these.
Among those benefits and improvements that have been disclosed, other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings. The drawings constitute part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective, partially cut away, view of the present invention, an apparatus for sensing patient distance, and all of its components.
FIG. 2 is a perspective view showing one possible arrangement of a force-responsive distance sensing apparatus have a force sensing element set within a force transmitting member, shown here as a cushion. A heterodyning proximation detector is also set within the force transmitting member and is working in cooperation with the force-responsive distance sensing apparatus.
FIG. 3 is a schematic illustration of one method for regulating the inflation of the air mattress with the apparatus shown in FIG. 1 .
FIG. 4 is a perspective view showing one arrangement of a light-responsive distance sensing apparatus through the use of light emission and detection.
FIGS. 5 and 6 are cross sectional and side views, respectively, of an alternative arrangement of a self-inflating air cell apparatus where light is emitted through a translucent outer surface of the air cell.
FIG. 7 shows the deformation of an air cell's initial shape in response to compressive forces exerted by a patient when positioned on the mattress. FIG. 7 a. shows an air cell deformation toward one side of the air cell. FIG. 7 b. shows an air cell deformation toward the center of the air cell.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As required, preferred embodiments of the present invention are described herein; however, the disclosed embodiments are merely exemplary of the invention that may be embodied in various forms. The figures are not necessarily to scale; some features may be exaggerated to show details of particular components. Specific structural and functional details disclosed herein are therefore not to be interpreted as limiting, but as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention.
Referring to the drawings, at least one embodiment of the apparatus and one method of the present invention may be appreciated for sensing patient distance. FIG. 1 shows the preferred embodiment of an apparatus for sensing patient distance 5 where a force-responsive distance sensing apparatus 205 having a force sensing element 70 coupled to a force transmitting member 65 is functionally cooperating with a heterodyning proximation detector apparatus 105 , and a light-responsive distance sensing apparatus 30 to regulate the air pressure within an air mattress 15 accordingly. FIG. 2 illustrates one embodiment of a force-responsive distance sensing apparatus 205 comprising a force sensing element 70 horizontally positioned within a force transmitting member 65 . FIG. 3 illustrates a preferred method for regulating the air flow of an air mattress 15 using data obtained from a heterodyning proximation detector apparatus 105 . FIG. 4 features one embodiment of a light-responsive distance sensing apparatus 30 comprising a light emitter 125 and a light detector 135 positioned at the opposing ends of a deformable inflatable chamber 150 . FIGS. 5 and 6 illustrates an alternative embodiment of a light-responsive distance sensing apparatus 30 incorporating a pliable covering 175 to cover and secure the light emitter 125 and the light detector 135 to the chamber 150 . FIG. 7 shows various exemplary deformation configurations to which a light-responsive distance sensing apparatus 30 might be subjected. With reference to each of these illustrated embodiments, however, it should be understood by those ordinarily skilled in the art that various other apparatus and methods could be incorporated without departing from the scope of the present invention.
Referring to FIG. 1, there is shown a patient 10 positioned partially atop an apparatus for sensing patient distance 5 above a patient support surface. As shown, an apparatus for sensing distance 5 of the present invention includes an air mattress 15 which defines a patient support surface, and is preferably supported by a conventional bed frame 25 . Frame 25 typically comprises more than one articulatable section, and is preferably mounted on castors for ease of movement in the hospital environment. To rotate or elevate the patient thereon, frame 25 may include hydraulic lifting mechanisms for raising and lowering portions of the frame 25 , including the articulatable sections of the frame 25 . Frame 25 may further be constructed of radiolucent materials, such as LEXAN, that are ideally suited for taking x-rays. A preferred air mattress 15 includes a series of air cells 31 which define an upper surface 20 and a lower surface 21 of the air mattress 15 . In its preferred embodiment, patient 10 primary support and cushioning is provided by a series of air cells 31 , however, the present invention is operable with an air mattress 15 comprising a single air cell 31 . The upper and lower surfaces 20 , 21 may be constructed of water permeable material which acts to draw moisture away from the patient 10 and, thus, assist in maintaining a sanitary environment. For therapeutic purposes, air cells 30 , 31 can be constructed using an air permeable material to facilitate a gradual flow of air through the upper and lower surfaces 20 , 21 of each air cell 30 , 31 , and thereby provide patient 10 with an air mattress 15 having a preferred therapeutic air pressure. In accordance with the present invention, each air cell 30 , 31 receives inflation pressure from at least one blower 40 that is connected thereto by a fluid conduit, not shown, or the like.
FIG. 1 illustrates a preferred embodiment of the present invention featuring a heterodyning proximation detector apparatus 105 ; a force-responsive distance sensing apparatus 205 ; and a light-responsive distance sensing apparatus 30 . As shown, the force-responsive distance sensing apparatus 205 includes a force transmitting member 65 and force sensing element 70 contained within at least one air cell 31 . A force transmitting member 65 is preferably constructed of a complaint cushioning material such as, but not limited to, foam, plastic or cloth batting. As will be appreciated, the force transmitting member 65 provides the present invention with a two-fold effect. First, the force transmitting member 65 defines an element of the force-responsive distance sensing apparatus 205 for detecting changes in the height of the upper surface 20 relative to the lower surface 21 as a patient is positioned atop the air mattress 15 . More particularly, changes in the patient 10 distance relative to the lower surface 21 are detected in real-time via a force sensing element 70 which measures a variable range of compressive forces exerted by the force transmitting member 65 in response to the compressive forces of a patient 10 resting thereon. Second, the thickness of the force transmitting member 65 provides an air mattress 15 with extra support cushioning in the event air mattress's 15 inflation pressure is reduced below that required to prevent the patient from bottoming-out, thus reducing the risk for patient injury.
FIG. 2 illustrates the preferred spatial relationship between the force sensing element 70 and the force transmitting member 65 of the force-responsive distance sensing apparatus 205 . As shown, the force sensing resistor 70 , which might be a force-sensitive resistor, piezoelectric crystal, or the like, is coupled to the force transmitting member 65 along a horizontal plane 85 ; however, situating such sensors on other spatial planes is contemplated as well. As will be understood be one skilled in the art, the force transmitting member 65 can be formed using a multiplicity of segmented members, which may differ in size and shape, to allow cooperative ease of movement in tandem with the air mattress 15 . Moreover, at least one force sensing element 70 , which transfers the signal through the control wire 71 , may be coupled to at least one segmented force transmitting member 65 or throughout a non-segmented force transmitting member 65 to provide an array of sensors suited for detecting compressive forces from various parts of the body. The force sensing element 70 may also be placed and coupled to the either the upper or lower surface of the force transmitting member 65 , within the force transmitting member 65 , or generally wherever the height of the patient above the frame 25 is desired to be known. Further illustrated in FIG. 2 is an embodiment of the force transmitting member 65 configured as a trapezoidal prism. It should be understood that other configurations can be used without departing from the scope of the invention. Other chosen configurations, however, should facilitate patient comfort, support and stability.
As can be appreciated from FIG. 1, compression of the force transmitting member 65 generates a resulting voltage across the force sensing element 70 which is representative of the compression exerted on the force sensing element 70 by the force transmitting member 65 . Following compression of the force transmitting member 65 , the resulting voltage is delivered to a controller 75 where the received voltage is compared to a preset calibrating signal. Deviations in the voltage signal as compared to the preset calibrating signal are then directed across a buffer amplifier 80 which modifies the voltage signal into a speed control voltage. The speed control voltage is then directed to a blower 40 or fluid regulating valve thereby either increasing or decreasing the rate of inflation air into the air mattress 15 . Controller 75 can also be configured to communicate with a microprocessor 60 which stores and compares various voltage values, and is operable to regulate blower 40 or fluid regulating valve in response to changes in patient height distance.
As shown schematically in FIG. 1, a heterodyning proximation detector apparatus 5 includes an antenna 36 connected to a tank circuit and oscillator mock-up 45 which is in communication with detector 50 . In its preferred embodiment, tank circuit and oscillator mock-up 45 comprises a capacitor and variable inductor operatively connected to a frequency oscillator. Frequency signals received by detector 50 are sent through a low pass filter 55 which operates to filter out high frequency signals, and emit only low frequency signals for conversion by a frequency-to-voltage converter 56 . The frequency-to-voltage converter 56 transforms the low frequency signals into a speed control voltage which activates a blower 40 or fluid regulating valve to provide inflation pressure to the air mattress 15 . Detector 50 may also be configured with a microprocessor 60 for storing and comparing various voltage values to provide blower 40 speed control.
In use, the heterodyning proximation detector apparatus 5 detects interactions between the electrical field pattern of the antenna 36 and the patient's 10 electrical signature which is characteristic of that patient's 10 dielectric constant. More particularly, the tank circuit and oscillator mock-up 45 operates to induce an electrical field within the antenna 36 which is responsive to a patient's 10 electrical signature characterized by the particular dielectric constant of that patient. Upon interaction with antenna's 36 induced electrical field, a resulting change in the natural frequency of the oscillator is detected. The altered frequency is sent to detector 50 which functions to compare the altered frequency to a preset reference frequency. Detected alterations in frequency signals are then transmitted through a low pass filter, and the resulting difference frequency is sent to a frequency-to-voltage converter 56 and/or servo control circuit which, in turn, communicates a generated speed control voltage to a blower 40 or fluid regulating valve.
The generated heterodyning proximation detector frequency is compared to a frequency generated by a calibrating tank circuit and oscillator for any deviations between the two frequencies via a product detector 50 . A deviation in frequency represents any change in the patient's relative position from the heterodyning detector apparatus 105 as compared to the calibrating, optimal therapeutic air pressure for the air mattress 15 . The deviation frequency from the product detector 50 is sent through a low pass filter 55 to allow only low frequency signals to pass as preparation for entering through a frequency-to-voltage converter 56 .
The preferred method for regulating the inflation of an air mattress 15 of the present invention is shown in FIG. 3 . Initially, air mattress 15 is set to a deflated position 90 . While in a deflated position 90 , a patient is furthest away from the antenna 36 and air mattress 15 . Referring to FIG. 3, the antenna 36 and air mattress 15 are collectively depicted as the heterodyning proximation detector apparatus 105 ; thus, data representing the distance where the patient is furthest away from the heterodyning proximation detector apparatus 105 is recorded at the deflated position 90 . As the patient approaches the antenna 36 , the heterodyning proximation detector apparatus 105 detects the patient and signals blower 40 to begin delivering inflation pressure to the air mattress 15 . This step enables a sufficient amount of inflation pressure to be delivered into the air mattress 15 so as to inflate the air mattress 15 and prevent the possibility of patient bottoming-out as the patient is positioned atop the air mattress 15 . The air mattress 15 continues to inflate to a fully inflated position 95 so long as the patient remains positioned atop the upper surface 20 of the air mattress 15 . After the air mattress 15 reaches a fully inflated position 95 , data representing the patient's closest distance away from the heterodyning proximation detector apparatus 105 is recorded. The patient's optimal height distance 100 is then calibrated using the stored distances from the deflated and fully inflated positions 90 , 95 which are based upon the individual's reactance as detected by the heterodyning proximation detector apparatus 105 . The air supply is continuously monitored and controlled 110 by the heterodyning proximation detector apparatus 105 to maintain the optimal height distance 100 . As the patient's distance from the heterodyning proximation detector apparatus 105 increases or decreases, the air supply to the air mattress 15 is accordingly increased 115 or decreased 120 by control means specifically contemplated by this invention or the like. Additionally, other methods would provide a force-responsive distance sensing apparatus 205 , a light-responsive distance sensing apparatus 30 or any other sensing means to cooperate and be included within the heterodyning proximation detector apparatus 105 to assist in controlling and monitoring the air supply of the air mattress 15 .
FIG. 4 illustrates one embodiment of the light-responsive distance sensing apparatus 30 of the present invention. The light-responsive distance sensing apparatus 30 comprises at least one inflatable chamber 150 forming an outer chamber surface 195 and a sealed inner chamber surface 200 . In a preferred embodiment, the inner chamber surface 200 is constructed of light diffusing materials, such as polyurethane, that are ideally suited to diffuse light within the inflatable chamber 150 . Such inflatable chambers 150 may be arranged singularly, perpendicular to one another, in parallel or in any other preferred configuration that defines an inflatable air mattress 15 for providing primary cushioning and support. It is preferred that the inflatable chambers 150 be constructed of a flexible and pliable material that is receptive to a wide range of compressive forces, especially those forces generated by a patient positioned atop the upper surface 20 of the air mattress 15 . Though other geometric shapes may be contemplated for the inflatable chamber 150 , FIG. 4 depicts the chamber 150 as having a preferred cylindrical shape. As shown, the chamber 150 is constructed having a light emitter 125 releasably or permanently attached to the light emitter end 130 of the chamber 150 using fastening means, such as adhesives, tape, VELCRO, or any other fastening method known to one skilled in the art. A light detector 135 is attached to the light detector end 140 of the chamber 150 using the various fastening methods known in the art. The light emitter 125 and light detector 135 can be an infrared light emitting diode (IRLED) and a photo-transistor, respectively. However, it should be understood to someone skilled in the art that various other light emitters and detectors can be chosen without departing from the scope of the invention.
In use, the chamber 150 of the light-responsive distance sensing apparatus 30 is inflated to an initial preset shape 165 , and the light emitter 125 and light detector 135 are activated to detect any deviation from the chamber's preset shape. As illustrated in FIG. 4, a chamber deformation 160 between the light emitter 125 and the light detector 135 is caused by compressive forces of the patient 10 when positioned on the upper surface 20 of the air mattress 15 . As shown, chamber deformation 160 causes the inner chamber surface 200 to scatter the emitted light, and, thus, results in less emitted light being received and detected by the light detector 135 . The resulting voltage output from the light detector 135 is transmitted through signal line 100 to a controller 170 which compares the light detector 135 voltage output to a preset calibrating voltage. Any deviation away from the preset calibrating voltage represents a material disparity in air supply within the monitored chamber 150 . As shown in the embodiment of FIG. 4, a microprocessor 60 may be configured along with the controller 170 to store and compare the various voltage values. Where a material disparity in air supply is detected, the controller 170 and/or microprocessor 60 respond by delivering a voltage signal that activates a blower 40 or a regulating valve, not shown, to adjust the air supply accordingly.
FIGS. 5 and 6 refer to an alternative embodiment of the light-responsive distance sensing apparatus 30 constructed with a pliable covering 175 . In this embodiment, the light emitter 125 and light detector 135 are situated outside of the outer chamber surface 195 at the light emitter end 130 and the light detector end 140 , respectively. Other embodiments of the light-responsive distance sensing apparatus 30 position the light emitter 125 and light detector 135 within the chamber 150 , embedded along the chamber's surface or any variation thereof. A pliable covering 175 having an inner surface 185 and an outer surface 180 is mated to the outer chamber surface 195 either along the entirety of the chamber 150 or substantially near the light emitter 125 or the light detector 135 . As shown in FIG. 6, the pliable covering's inner surface 185 is mated to the outer chamber surface 195 forming a pouch 145 for receiving the light emitter 125 or the light detector 135 therein. In effect, the pouch 145 seals and secures the light emitter 125 and the light detector 135 to the chamber 150 by restricting relative movement therein; and the pouch 145 , with its pliable covering, aesthetically conceals the light emitter 125 and the light detector 135 . Additionally; the pouch 145 may be provided with releasable closings to facilitate either insertion or removal of the light emitter 125 or the light detector 135 into or out of the pouch 145 during maintenance or cleaning. FIGS. 5 and 6 show a chamber's surface which partially forms a pouch 190 as constructed of either transparent or translucent material to accommodate as well as modify the projection of light from the light emitter 125 to the light detector 135 through the chamber 150 . To further facilitate the transmission of light through the chamber 150 , the inner surface 185 of the pliable covering which partially forms the pouch 145 may be constructed of opaque or reflective material.
FIG. 7 shows in detail the chamber's deformation 160 in response to compressive forces exerted by the patient 10 when the patient 10 is resting on the upper surface 20 of the air mattress 15 . FIG. 7 a. shows a possible chamber deformation 160 towards the light emitter end 130 . FIG. 7 b. shows a possible chamber deformation 160 centered between the light emitter end 130 and the light detector end 140 of the chamber 150 . Accordingly, one advantage of the present invention is that a deformation is detectable along the entire length of the light-responsive distance sensing apparatus 30 , and, thus, precludes the need for a vast and costly array of sensors along the length of the chamber 150 . As shown in FIGS. 4 and 5, the light emitter 125 and light detector 135 are preferably situated at the opposing ends of the cylindrical chamber 150 . Positioning the chamber 150 transversely across the frame 25 thus enables the caregiver to obtain patient x-rays along the length of the air mattress 15 without any x-ray interference from the light emitter 125 and light detector 135 .
While the description given herein reflects the best mode known to the inventor, those who are reasonably skilled in the art will quickly recognize that there are many omissions, additions, substitutions, modifications and alternate embodiments may be made of the teachings herein. Recognizing that those of reasonable skill in the art will easily see such alternate embodiments, they have in most cases not been described herein in order to preserve clarity. | 4y
|
This application is a continuation-in-part of application Ser. No. 07/547,163 filed on Jul. 3, 1990.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical display device which can exhibit a display pattern not only by daylight but also an internal light source in the nighttime. More particularly, it relates to an optical display device in which a display pattern is visible in the daytime but an internal instrument is not visible and which device can exhibit the display pattern in a visible manner by uniform light having any desired color in the nighttime.
DESCRIPTION OF THE PRIOR ART
In general, in the display device such as an emblem or the like mounted on a body of an automotive vehicle, the display pattern is visible in the daytime. There are some display devices in which even internal instruments may be observed in the daytime and the display patterns are displayed by the internal light source within the internal instruments in the nighttime. However, in almost all the display devices, the light emitted from the display devices would be non-uniform. In some of the conventional devices, it is possible to make uniform the emitted light but their structures are complicated, and the size of the devices are large. Thus, the conventional devices are still unsatisfactory.
The present applicants have proposed a variety of improvements in addition to the technique shown in U.S. Pat. No. 5,057,974. The former application filed prior to the filing of the present applicant discloses a prior art technique which is most relevant to the present invention. The former application will be described.
FIG. 5 is a vertical cross-sectional view of the device, and FIG. 6 is a plan view of the device. The optical display device C is constructed as follows.
Reference numeral 2 denotes a printed circuit board, and reference numeral 3 denotes light sources such as light emitting diodes (LEDs) mounted on the printed circuit board 2. Reference numeral 4 denotes a light reflective plate such as a reflective sheet or a reflective layer coated plate mounted on a top surface of the printed circuit board 2 except for portions of the printed circuit board on which the light sources 3 are mounted. Coating material having a high light transmissive characteristic is applied to the light reflective plate 4. Reference numeral 5 denotes a light transmissive member made of transparent material such as acrylic resin, having a high transmissive characteristic, through which the light from the light sources 3 passes. The light transmissive member is slightly spaced upwardly away from the printed circuit board 2. A plurality of cavities 6 into which the light sources 3 are inserted are formed at positions corresponding to the light source mounted positions. Reference numeral 7 denotes a light transmissive box-like member formed of transparent material such as acrylic resin having a desired color. The box-like member is provided so as to cover a front face and side surfaces of the light transmissive member 5 and side surfaces of the printed circuit board. Light non-transmissive members 9 made of coated layers or plated films are applied to a top surface of the box-like member 7 except for portions on which a desired pattern 8 such as a letter or a figure is marked. In the thus constructed conventional optical display device C, when the light sources 3 are turned on by supplying current to the printed circuit board 2, the light from the light sources 3 is introduced into the light transmissive member 5 and is advanced through the member 5. A part of the light is reflected by the light reflective plate 4 as reflective light and is caused to pass through the light transmissive member 5. The light which has reached the upper portion of the light transmissive member 5 passes through the box-like member 7 and passes through the display portion 8 which forms the pattern. The light is emitted to the outside from the display portion 8 to thereby display the pattern such as a letter or a figure. By forming the transparent box-like member 7 and the transmissive member 5 of acrylic resin colored in a desired color, it is possible to select the emission light color of the pattern as desired with a decorative effect. However, the display device suffers from the following defects:
(1) When the light from the light sources 3 passes through the transmissive member 5, since the light is reflected by the reflective plate located at the bottom, the light reflectivity is low, and it is impossible to make the thickness of the transmissive member 5 less than a predetermined level. As a result, it is impossible to reduce the overall thickness of the light display device C as a whole.
(2) Since the light from the light sources 3 is emitted directly from the display portion 8 or the light reflected light from the reflective plate 4 is emitted from the display portion 8, the light of the display portion 8 is not uniform and would flicker, which is undesirable in an outer appearance.
(3) There is a fear that sunshine would be introduced into the interior of the transmissive member 5 in the daytime and the interior of the instruments such as light sources 3 and printed circuit board 2 would be visible from the outside.
(4) In order to color the light emission display, the colored acrylic plate or the like is used. The light absorption amount through the plate is large. Not only would the amount of emission light from the display portion be reduced, but also the number of colors and the kind of colors would be restricted. As a result, it is impossible to obtain a desired bright display.
SUMMARY OF THE INVENTION
In view of the above-noted defects, a primary object of the invention is to provide an optical display device which is simple in structure and which provides a decreased thickness of the display portion while assuring a uniform and bright light display. The internal instruments of the device are not visible from the outside in the daytime, and it is possible to use any desired color for display.
In order to achieve this and other objects, according to the present invention, there is provided an optical display device comprising: a printed circuit board; light sources mounted on the printed circuit board; a light transmissive member having at a bottom a light reflective surface for reflecting light upwardly, cavities into which the light sources are inserted being formed in the light transmissive member, the light transmissive member being made of light transmissive material; a light dispersing plate provided on an upper surface side of the light transmissive member for dispersing light from the light sources; a color sheet provided on an upper surface side of the light dispersing plate for keeping the interior of the optical display device invisible from the outside and for selecting a desired color for the light emitted from the device; a half mirror provided on an upper surface side of the color sheet for serving as a silver metallic mirror surface in the daytime and for passing the light from the inside in the night time; and a light display member made of light transmissive material marked displaying pattern thereon and provided on an upper surface side of the half mirror for displaying a predetermined pattern such as a predetermined letter or figure and for covering the peripheral portions of the printed circuit board, light transmissive member, light dispersing plate and half mirror. A light dispersing function is imparted to an upper surface of said light transmissive member to thereby dispense with said light dispersing plate.
With such an arrangement, the light from the light sources such as LEDs is introduced directly into the light transmissive member or after the light is reflected at the reflective surface of the bottom of the light transmissive member with a high reflectivity, the light is introduced into the light transmissive member. The light is advanced toward the upper surface side of the light transmissive member. The light which has reached the upper surface of the light transmissive member is diffused by the dispersing film to become a uniform light (gentle and stable light). Also, it is possible to color the light emitted through the half mirror and the display portion to the outside to exhibit a predetermined pattern of sign, letters and figures. Also, since the half mirror plate is provided immediately below the display portion, it is possible to reflect sunshine by the surface of the half mirror in the daytime to highlight the pattern in a mirror surface of silver metal.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings:
FIG. 1 is a vertical cross-sectional view showing an optical display device in accordance with a first embodiment of the invention;
FIG. 2 is a cross-sectional view taken along the line II--II of FIG. 1;
FIG. 3 is a vertical cross-sectional view showing an optical display device in accordance with a second embodiment of the invention;
FIG. 4 is a plan view of the device shown in FIG. 3;
FIG. 5 is a vertical cross-sectional view showing a conventional optical display device; and
FIG. 6 is a plan view showing the device shown in FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will now be described with reference to the accompanying drawings.
In the embodiment shown, the same references are used to denote the same members or components as those in FIGS. 5 and 6.
An optical display device A includes a printed circuit board 2, light sources 3 provided on a top face of the printed circuit board 2, a light transmissive member 5A located above the printed circuit board 2 at a slight interval and made of acrylic resin or the like having a high light transmissive characteristic with cavities 6 being formed at positions corresponding to the front faces of the light sources 3, a light dispersing plate 12 formed intimately on the top surface of the light transmissive member 5A, a color sheet 11 having a light transmissive characteristic and formed intimately on the top surface of the light dispersing plate 12, a "half mirror" (through which part of light passes) provided intimately on the top surface of the color sheet 11, a light reflective surface 4A applied to the lower surface of the light transmissive member 5A, and a box-like member 7 arranged so as to cover the front face and side surfaces of the light transmissive member 5A and side surfaces of the printed circuit board 2 and made of acrylic resin or the like having a high light transmissive characteristic. A non-transparent coating film or a plate film 9 is applied to the surface of the box-like member 7 except for the light display portion 8 defining a desired pattern.
The light dispersing plate 12 may be a plate or film made of semitransparent resin made by applying fine corrugations sandblasted on one surface of a thin plate or a film made of transparent material through which the light from the light sources .3 passes so that the light is irregularly reflected and dispersed, or otherwise a milky white plate or film made of material having a high light transmissive characteristic by diffusing white fine pigment powders into the interior of the may be used.
The color sheet 11 is a transparent thin film colored in a single color or a plurality of colors. The color sheet 11 is arranged corresponding to the display pattern of the optical display device A. The light reflective surface 4A is made by forming lines (or dots) on the rear surface of the transmissive member 5A by a screen print with ink having a high light reflectivity as shown in U.S. Pat. No. 5,057,974. The lines are distributed so that the line density becomes higher as the distance from the light sources 3 is longer. Namely, the lines are distributed so that the line density per a unit area is increased by changing a width of the lines or spaces between the lines so that the light from the light sources 3 is reflected toward the color sheet 11 as reflective light having a uniform distribution. Incidentally, the light dispersing plate 12 is not limited to that shown and, it is possible to substitute a formation of a number of fine corrugations on the upper surface of the light transmissive member 5A.
The thus constructed optical display device A displays the display pattern by reflecting sunshine on the half mirror 10 to exhibit the sign or figure in a silver metallic color in the daytime. In the nighttime, the current is supplied to lighting circuits of the light sources to light the light sources 3. The light from the light sources 3 is advanced from the end faces of the cavities of the transmissive member 5A through the transmissive member 5A. On the other hand, a part of the light is effectively reflected by the reflective surface 4A and is advanced toward the upper surface of the transmissive member 5A. The light which has reached the upper surface of the transmissive member 5A becomes light uniform over the entire surface by the action of the light dispersing plate 12. If the display portion 8 of the boxy member 7 is composed of a letter and a sign, and the letter and the sign are displayed in colors, it is possible to make the display more remarkable by forming the color sheet in the desired colors.
A second embodiment of the invention will not be described with reference to FIGS. 3 and 4.
Reference numeral 17 denotes LEDs mounted in a peripheral portion of the optical display device, and reference numeral 14 denotes a transparent member made of transparent material such as acrylic resin or glass with an inverted U-shape in cross section. In the same manner as the first embodiment, the light dispersing plate 22, the color sheet 21 and the half mirror 20 are intimately formed on the upper surface of the transmissive member 14. These components are covered by a box-like member 13 made of material having a high light transmissive characteristic such as acrylic resin located on the upper surface of the half mirror 20. The upper surface of the box-like member 13 is covered by non-transmissive coatings 19 or the like except for the pattern display portions 13B. In the transmissive member 14, except for the light sources 17, the light passing through the light transmissive member 14 is not leaked from the light transmissive member 14, and the reflective surfaces 15 and 16 are formed for introducing the light into the light display portions 13B. The reflective surfaces 15 and 16 have the lines or dots in the same manner as in the first embodiment but their details will be omitted.
In the daytime, the thus constructed optical display device B highlights the light display portions 13B with a high brightness in a silver metallic color by reflecting the sunshine n the half mirror. Also, the color sheet 21 is arranged so that the interior of the optical display device B is not observed from the outside.
On the other hand, when the light sources 17 such as LEDS is turned on in the nighttime, the light from the light sources 17 is advanced through the light transmissive member 14 while reflecting between the reflective surfaces 15 and 16 and the pattern to be displayed is exhibited from the light display portions 13B to the outside, so that the pattern can be read.
It is apparent that the invention is not limited to those embodiments shown but the person skilled in the art may modify the above described embodiments. For example, in the first and second embodiment, the color sheet 11, 21 is intimately formed on the top surface of the light dispersing plate 12, 22. However, it is possible to provide the light dispersing film 12, 22 on the top surface of the color sheet 11, 21.
The optical display device according to the present invention is simple in structure in comparison with the prior art device According to the invention, it is possible to reduce a thickness of the transmissive member and hence the thickness of the overall device. Since the half mirror plate is used, it is possible to keep the internal instruments of the display device invisible from the outside | 4y
|
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/521,071, filed on Aug. 8, 2011, the contents of which are herein incorporated by reference in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to the cooling of photovoltaic (PV) cells, and more particularly, to systems and methods for circulating a coolant for this purpose.
BACKGROUND OF THE INVENTION
[0003] Various systems and methods are known for cooling PV cells during operation. In some instances—for example in systems using water or glycol or other liquids as a coolant—the coolant will warm up as it traverses the panels of PV cells, therefore providing greater cooling near the entrance into the panel assembly, and less cooling near the exit of the panel assembly.
SUMMARY OF THE INVENTION
[0004] In view of the foregoing, it is an object of the present invention to provide improved systems and methods for cooling PV cells. According to an embodiment of the present invention, a cooling system for PV cells includes an evaporator configured to thermally contact the PV cells and transfer heat generated thereby to coolant in the evaporator, a condenser for receiving vaporized coolant from the evaporator and condensing the coolant to a liquid state, tubing connecting the evaporator, and the condenser in a circuit, a compressor arranged in the circuit for pumping coolant therethrough in a coolant flow direction, an active charge control apparatus arranged in the circuit between, in the coolant flow direction, the evaporator and the condenser, and a liquid flow control apparatus arranged in the circuit between, in the coolant flow direction, the condenser and the evaporator. The active charge control apparatus and the liquid flow apparatus cooperate to maintain the evaporator completely wetted by coolant and prevent coolant in the liquid state from leaving the evaporator.
[0005] According to a method aspect, a method for cooling PV cells to increase their efficiency, and for capturing the waste heat from the PV cells, includes placing an evaporator in thermal contact with the PV cells and circulating coolant through the evaporator to remove waste heat therefrom. Circulating coolant through the evaporator includes maintaining the evaporator in a wetted state with substantially no coolant superheating.
[0006] These and other objects, aspects and advantages of the present invention will be better appreciated in view of the drawings and following detailed description of preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a schematic diagram of a photovoltaic (PV) cell cooling system, according to an embodiment of the present invention, including an active charge control (ACC) apparatus, a liquid flow control (LFC) apparatus, and an evaporator;
[0008] FIG. 2 is a sectional side view of the ACC apparatus of FIG. 1 ;
[0009] FIG. 3 is a sectional side view of the LFC apparatus of FIG. 1 ;
[0010] FIG. 4 is a sectional side view of an alternate to the evaporator of FIG. 1 , according to another embodiment of the present invention;
[0011] FIG. 5 is a partially sectioned bottom view of another alternate to the evaporator of FIG. 1 , according to a further embodiment of the present invention;
[0012] FIG. 6 is a sectional view taken along line C-C of FIG. 5 ;
[0013] FIG. 7 is a partially sectioned bottom view of an additional alternate to the evaporator of FIG. 1 , according to an additional embodiment of the present invention;
[0014] FIG. 8 is a sectional view taken along line A-A of FIG. 5 ;
[0015] FIG. 9 is a partially sectioned bottom view of a further alternate to the evaporator of FIG. 1 , according to a further embodiment of the present invention;
[0016] FIG. 10 is a sectional view taken along line B-B of FIG. 5 ;
[0017] FIG. 11 is a partially sectioned side view of an alternate to the LFC apparatus of FIG. 1 , including a cylinder 103 ; and
[0018] FIG. 12 is an end view of the cylinder 103 of FIG. 11 , showing an inlet thereinto.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0019] Referring to FIG. 1 , according to an embodiment of the present invention, a PV cell cooling system 10 includes a compressor 11 that pumps refrigerant vapor from outlet 12 to a condenser 13 (flow direction of coolant represented by unlabeled arrows), where the hot refrigerant is cooled by the condenser 13 , thereby delivering heat energy into the fluid 14 in tank 28 . The refrigerant, being cooled by the fluid in tank 28 , condenses to a liquid state within Condenser 13 , and exits the condenser at outlet 15 . Conduits connect the system 10 components into a complete circuit. The refrigerant is delivered to a liquid flow control (LFC) apparatus 17 via conduit 16 . The refrigerant leaving the LFC apparatus is delivered to the inlet 19 of the evaporator 20 by way of conduit 18 . The liquid refrigerant then contacts an evaporator wall 21 as it moves upward through an evaporator space 22 . As the refrigerant evaporates in space 22 , it absorbs heat from the wall 21 that is in physical and thermal contact with PV support member 27 , and thereby cools the PV cells 26 , which are bonded to, and in thermal contact with, support member 27 . The refrigerant moving up through the evaporator space 22 is forced by an active charge control (ACC) apparatus 24 , working in conjunction with LFC apparatus 17 , to finish evaporating and be in vapor form only as it leaves the evaporator space 22 and proceeds via conduit 23 to the ACC apparatus 24 . This is accomplished by the LFC 17 holding a fixed amount of sub-cooling in the condenser 13 while the ACC apparatus allows only vapor to leave the ACC apparatus, and more preferably only vapor that is not superheated.
[0020] Referring to FIG. 2 , the ACC apparatus 24 receives refrigerant vapor at entrance 81 . The refrigerant proceeds past venturi 85 which entrains liquid refrigerant into evaporator tube 82 . When the vapor/liquid exits tube 82 and impinges on deflector disc 86 , the liquid falls back into the liquid pool at liquid level 84 , while the lighter vapor flows past the deflector disc to leave the ACC apparatus 24 at outlet 87 . Thus the ACC apparatus 24 effectively separates the vaporized refrigerant from the liquid refrigerant, and only saturated vapor (not superheated) leaves the ACC apparatus 24 . The temperature of the contents of the ACC tank 88 is determined by the amount of suction pressure at the compressor inlet. Therefore if superheating of the refrigerant starts to occur in the evaporator 20 , the superheated vapor going through the evaporator tube 82 will be warmer than the liquid reserve in the ACC apparatus 24 , and will evaporate refrigerant from the reserve of liquid in ACC apparatus 24 , and place more refrigerant into active circulation through the whole refrigerant circuit. This additional refrigerant will further “flood” or “wet” the evaporator 20 until all superheating is eliminated. Conversely, if too much refrigerant is in circulation, some amount of liquid will pass through and out of evaporator space 22 , but when any liquid reaches the ACC apparatus 24 , it simply falls back into the reserve pool to eliminate the excess of refrigerant in active circulation. Thus the ACC apparatus ensures that the space 22 in the evaporator 20 is constantly “flooded” or “wetted,” and therefore superheating does not occur in the evaporator 20 .
[0021] The ACC apparatus 24 and LFC apparatus 17 operate together to ensure the entire evaporator space 22 has liquid refrigerant present throughout the evaporator 20 , from entrance 19 to the outlet 23 , and therefore heat is uniformly absorbed from wall 21 of the evaporator 20 , with the result that the cooling of the PV support member 27 , and in turn the cooling of the PV cells 26 , is uniform throughout the panel of PV cells. The refrigerant passes from the ACC apparatus 24 and on to the compressor 11 to repeat the cycle again.
[0022] Referring to FIG. 3 , extensive testing has shown that a refrigerant circuit is more efficient if subcooling in the condenser is held to a low value, preferably in the range of 1 to 8 degrees Fahrenheit, with the optimum amount of subcooling being about 4 degrees Fahrenheit. The LFC apparatus 17 (a subcool control valve (SCV), in the FIG. 3 embodiment) is designed to achieve that purpose when used in concert with ACC apparatus 24 . In the SCV 17 , liquid refrigerant from the condenser 13 flows in at inlet tube 61 , and on and upward between outer tube 62 and outlet tube 63 , and onward to main orifice 65 and side orifice 66 in orifice plug 68 . The liquid is metered at the orifices 65 and 66 , and after metering and expanding, leaves the valve via outlet tube 63 . Dome 67 and diaphragm 66 form a sealed cavity 72 which contains a controlling liquid refrigerant 70 . The controlled fluid, represented by the flow arrows, makes physical and thermal contact with diaphragm 66 , which in turn requires the fluid 70 to assume approximately the same temperature and pressure as controlled fluid flowing to the orifices.
[0023] If the incoming controlled fluid is overly subcooled, the controlling fluid 70 will also become more subcooled which reduces the pressure on top of the diaphragm 66 , causing the diaphragm to flex upward, thereby opening the main orifice, and increasing the flow of the controlled fluid from the condenser 13 and reducing the amount of subcooling. Conversely, if the subcooling becomes too little, the pressure above the diaphragm will decrease and increase the amount of subcooling, all with the result that a predetermined amount of subcooling is maintained in the condenser. The thickness and flexibility of the diaphragm 66 are the primary factors that determine the amount of subcooling that results. The side orifice 73 provides a minimum flow and prevents instability and a possible unintentional shutdown of the system. Note that the diaphragm stop 71 serves to prevent overstressing the diaphragm under various unusual conditions. The LFC apparatus of FIG. 3 has an additional feature and advantage, in that a “built in” heat exchanger is formed by outer tube 62 and outlet tube 63 , wherein the metered, expanded, and chilled refrigerant leaving through outlet tube 63 makes thermal contact with the incoming and un-metered liquid inside outer tube 62 via the wall of outlet tube 63 , to thereby provide inverse thermal feedback to the incoming liquid, for stabilizing the LFC apparatus.
[0024] Advantageously, the present method uses a refrigerant in connection with PV cell cooling. As used herein, a refrigerant is a specific type of coolant which evaporates as it traverses through an evaporator. Thus, while a “coolant” could be any fluid capable transferring heat away from a heat source, a “refrigerant” is more specifically a coolant that will undergo a phase change while doing so. In other words, as the terms are used herein, all refrigerants are coolants, but all coolants are not necessarily refrigerants. By keeping the evaporator wetted with refrigerant at its vaporization point, an even temperature profile will be experienced by the PV cells being cooled. With this in mind, water and glycol are not preferred coolants for many PV cell applications as they will remain subcooled liquids under expected operational conditions.
[0025] As will be appreciated from the foregoing, the refrigerant circuit which drives the refrigerant through the evaporator is designed to continuously supply the required amount of refrigerant to the evaporator that will result in the “wetting” or “flooding” of the entire evaporator. When an evaporator is flooded, there is minimal difference in temperature of the evaporator from the entrance end to the exit end of the evaporator. Flooding the evaporator eliminates any superheating of the refrigerant within the evaporator. Eliminating superheating results in a more uniform cooling of the PV panel. Overheating of even one PV module in multiple modules connected in series can result in limiting the output power of the series of modules, and could result in damage to the overheated module. The uniform cooling provided by the present invention prevents such results. Eliminating superheating also results in a higher “suction pressure” and a cooler, more dense refrigerant vapor at the compressor entrance. These two factors result in more refrigerant pumped per stroke of the compressor, and improvement of efficiency of the refrigerant circuit.
[0026] The heat removed from the PV panel(s) may typically be delivered to a condenser for useful heating of water, or to the condenser of an air handler for the heating of air. The condenser may be used in other heating applications. This arrangement allows for the more effective recapture of what would otherwise be waste heat generated by the PV panels. Thus, the PV cell cooling system is not only able to enhance efficiency of the PV cells—thereby reducing electricity that needs to be supplied by other (potentially less “green”) sources, it can also simultaneously recapture more waste heat for other applications that would otherwise require another (again, potentially less “green”) heat source.
[0027] The above described embodiment is presented for exemplary and illustrative purposes; the present invention is not necessarily limited thereto. For example, referring to FIG. 4 , the structure therein replaces the structure of 19 , 20 , 21 , 22 , 26 , and 27 in FIG. 1 , with like reference numerals (followed by an “A”) referring to analogous elements. Support member 27 A serves multiple purposes. For example, it forms one wall 21 A of the evaporator chamber 22 A, and secondly it serves as the support member 27 A for the PV cells 26 A, thereby eliminating the need for a separate wall member 21 , and reducing the complexity, weight, and cost of the assembly, while improving the thermal conductivity between the evaporating refrigerant and the PV cells 26 A. Thus, as the refrigerant circuit absorbs unwanted heat from the PV cells, it delivers it as useful heat to the condenser in tank 28 , or to any condenser for delivering useful heat.
[0028] In other examples, FIGS. 5-10 show various alternative structures that may be used for PV cooling, as alternatives to the simplified evaporators 20 , 20 A as shown in the refrigerant circuit of FIGS. 1 and 1A .
[0029] Referring to FIGS. 5 and 6 , a cooled panel A includes serpentine tubing 32 attached to tubing support member 30 by thermally conductive bonding material 34 . The tubing support member 30 is in physical and thermal contact with PV cells 31 . The refrigerant evaporates as it flows through the tubing 32 from inlet 36 through passage 35 to outlet 37 , and tubing support member 30 is cooled, which in turn cools PV cells 31 . Tubing support member 30 is made such that it supports the PV cells, and the support member 27 in FIG. 1 is eliminated.
[0030] Referring to FIGS. 7 and 8 , a cooled panel B includes a corrugated member 42 joined to panel support member 40 by seam welds 43 thereby forming fluid passages 44 such that a refrigerant flowing through the passages from entrance 45 to exit 46 extracts heat from member 40 and in turn from PV cells 41 . Support member 40 also serves as one wall of the cooled panel B.
[0031] Referring to FIGS. 9 and 10 , a cooled panel C uses staggered seam-welds 53 to attach corrugated member 52 to panel support member 50 thereby forming a serpentine pathway 54 where the coolant enters at inlet 55 and after traversing the pathway exits the panel at outlet 56 , thereby cooling PV cells 51 . Support member 50 also serves as one wall of the cooled panel C.
[0032] In a further alternative, referring to FIGS. 11 and 12 , a different LFC apparatus—LFC apparatus 17 A—is used. The LFC apparatus 17 A is used to hold a fixed amount of subcooling in the condenser 13 , thereby cooperating with the ACC 24 , but that amount of subcooling is normally zero, because a small trickle of uncondensed vapor is required to arrive at the LFC 17 A to operate the float 107 . The body of the LFC 17 A in FIG. 7 is a cylinder 103 which is enclosed with end caps 111 , thus providing a closed chamber for float 107 . Liquid refrigerant enters the chamber at entrance tube 113 , and inlet 112 . Cylinder 103 fills with liquid to a height determined by the amount of vapor refrigerant arriving with the liquid. The float 107 is attached to metering segment 116 by float attachment 110 and attaching rod 109 , thereby making the metering segment 116 swivel on swivel pin 102 . The metering segment 116 being otherwise generally circular, is flat at segment 116 . When little or no vapor arrives at valve 117 , the cylinder 103 fills with liquid, indicating that liquid is backing up in the condenser 113 . As cylinder 103 fills with liquid, float 107 rises.
[0033] Raising the float 107 presents the flat segment 116 to the valve orifice which is centered in valve plug 105 , which in effect opens the LFC apparatus 17 A to release liquid refrigerant from condenser 13 . When all liquid is released from condenser 13 , vapor arrives in cylinder 103 and the float 107 is forced downward by the vapor rising to the top of cylinder 103 , which closes the valve to require more complete condensing of the refrigerant within the condenser. Equilibrium is reached when just a small trickle of bubbles (vapor) arrives from the condenser, and just enough of the flat on the metering segment 116 is presented to the outlet orifice of LFC apparatus 17 A to maintain zero subcooling in condenser 13 . After the refrigerant is metered and expanded in metering plug 105 , it proceeds through outlet tube 101 and 106 which is formed to make thermal contact with cylinder 103 using a silver braze 114 , thus LFC apparatus 17 A. The metered and expanded refrigerant exits the LFC apparatus 17 at outlet 115 .
[0034] The foregoing is not intended to be an exhaustive list of alternatives. Rather, those skilled in the art will appreciate that these and other modification, as well as adaptations to particular circumstances, will fall within the scope of the invention as herein shown and described and of the claims appended hereto. | 4y
|
This is a continuation-in-part of application Ser. No. 08/900,795, filed on Jul. 25, 1997.
FIELD OF THE INVENTION
Cosmetic compositions containing resveratrol, a natural estrogen derived from plants, and methods of conditioning skin by applying such compositions to the skin.
BACKGROUND OF THE INVENTION
The human skin consists of two major layers, the bottom thicker layer, dermis and the top thinner layer the epidermis. Dermis is the layer which provides the strength, elasticity and the thickness to the skin. With aging, the thickness of the dermal layer is reduced and this is believed to be partially responsible for the formation of wrinkles in aging skin. The top layer of human skin or the epidermis which provides the resilience and the barrier properties of the skin, is composed of many different cell types. Keratinocytes are the major cell type of the epidermis (75-80% of the total number of cells in the human epidermis). Within the epidermis the keratinocytes reside in four distinct stages of differentiation. Epidermal differentiation is important for providing the essential function of the skin, namely to provide a protective barrier against the outside environment and to prevent loss of water from the body. Formation of the cornified envelope is the final stage of keratinocyte differentiation. The enzyme responsible for the formation of cornified envelopes, transglutaminase is a marker of epidermal differentiation. Agents which increase the thickness of the dermal layer and increase the differentiation of keratinocytes in the epidermal layer should therefore be ideal compounds for providing skin conditioning and anti-aging benefits.
Estrogens and synthetic compounds which act like estrogens are known to increase the thickness of the dermal layer and reduce wrinkle formation in the aging skin. Changes in the skin such as skin dryness, loss of skin elasticity and plumpness occurring after menopause are attributed to the lack of estrogen production. Estrogen therapy prevents or slows down many of the changes associated with aging skin (Creidi et al., Effect of a conjugated oestrogen cream (Premarin®) on aging facial skin, Maturitas, 19, p.211-23, 1994). A synthetic estrogen, diethyl stilbestrol, has the following structure:
This structure is very different from the structure of natural estrogen, estradiol:
In recent years, phytoestrogens (i.e., natural compounds which have estrogen-like activity and which are found in plants) have been increasingly used for therapeutic purposes. Some of the uses described are as hypocholesterolemic and antiatherogenic agents, treatment of cardiovascular diseases especially in postmenopausal women, treatment for osteoporosis in the elderly and as an anticancer agent especially against breast cancer, endometrial and cervical cancer in women (Knight et al., Phytoestrogens—a short review, Maturitas, 22: 167-75, 1995).
The consumer demand for “natural” based products has been growing in recent years. The consumers perceive chemical synthesis as environmentally unsafe. A chemically synthesized ingredient may contain harsh chemicals. Natural products are perceived as pure and mild and superior to chemically synthesized products. However, delivering a cosmetic benefit from plant sources is not trivial. In order to derive a real benefit from a “natural” source a specific active in the plant has to be identified which truly delivers a cosmetic benefit.
One known phytoestrogen is photoanethole:
Photoanethole has not been described for topical or cosmetic use.
The present invention is based at least in part on the discoveries that resveratrol is a phytoestrogen, that it inhibits keratinocyte proliferation, increases keratinocyte differentiation, inhibits melanin production by the skin cells, and alleviates irritation or sting potentially associated with the use of alpha-hydroxy acids.
Resveratrol is a compound found in a variety of plants. Isolation and characterization of resveratrol have been described from a variety of plants such as the roots of Japanese knotweed (Powell et al., Phytochemistry 35, p.335, 1994), from wine and grapes (Goldberg et al; J. Agric. Food Chem., 43, p.1820, 1995 and Cellotti et al., “Resveratrol content of some wines obtained from dried Valpolicella grapes: Recioto and Amarone., J chromatogr A (Netherlands) 730: 47-52,1996), and from peanut plant cultures (Kindl et al., U.S. Pat. No. 5,391,724). Red grapes and red wine contain high amounts of resveratrol and this compound is claimed as one of the reasons for cardiovascular health in wine drinkers. In addition, resveratrol has been shown to be a potent cancer chemopreventive agent and an anti-inflammatory agent. Resveratrol has also been reported to induce differentiation of human promyelocytic leukemia cells (Jang et al., Cancer chemopreventive activity of resveratrol, a natural product derived from grapes, Science 275: 218-220, 1997). Jang et al describe resveratrol's use as an anticancer agent against carcinogen-treated mouse skin cells in culture.
Cosmetic compositions containing grape extract have been described. See for instance abstract of Japanese patent application 06336421 (“JP '421”), disclosing the use of 0.5% grape extract in cosmetic compositions. Scafildi et al. (U.S. Pat. No. 5,683,683) and Zabotto et al. (U.S. Pat. No. 5,439,672) disclose cosmetic compositions containing grape seed oil. Griat et al. (U.S. Pat. No. 5,171,577) disclose cosmetic foams containing cosmetic pips. None of these disclosures, except JP '421, mentions any amount of the grape to be used. JP '421 teaches the presence of 0.5% of grape extract. According to Agricultural Research Service of the United States Department of Agriculture, resveratrol concentration in whole berries is about 15 ppm. Then, the resveratrol concentration in 0.5% grape seed extract is 0.33 micromolar or 0.0000075 wt. %.
The art discussed above does not describe the use of resveratrol for skin care or cosmetic use, does not teach that resveratrol is a phytoestrogen, or that it inhibits keratinocyte proliferation, or that it promotes differentiation of keratinocytes, or that it affects melanin production by the skin cells, or that it controls skin irritation caused by alpha-hydroxy acids.
SUMMARY OF THE INVENTION
The present invention includes skin care composition comprising resveratrol in an amount of from 0.00002 to 10 wt. % and a cosmetically acceptable vehicle.
The present invention also includes a method of improving or preventing the condition of wrinkled, lined, dry, flaky, aged or photodamaged skin and improving skin thickness, elasticity, flexibility, radiance, glow and plumpness, which method includes applying to the skin the inventive composition. Compositions of the invention are intended for topical application to mammalian skin which is already dry, flaky, lined, wrinkled, aged, photodamaged, or the inventive compositions may be applied prophylactically to normal healthy skin to prevent or reduce the deteriorative changes. Inventive compositions may also be used for treatment of skin hyperproliferation disorders, such as psoriasis or winter xerosis.
The present invention also includes cosmetic methods of delivering estrogenic activity to the skin, inhibiting keratinocyte proliferation in human skin and increasing keratinocyte differentiation. The present invention also includes a cosmetic method of lightening the skin color. The invention further includes a cosmetic method of controlling skin irritation, sting or inflammation which may be caused by alpha-hydroxy acids. In this respect, the invention also includes cosmetic composition containing resveratrol in combination with an alpha-hydroxy acid.
DETAILED DESCRIPTION OF THE INVENTION
Except in the examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts of material or conditions of reaction, physical properties of materials and/or use are to be understood as modified by the word “about.” All amounts are by weight of the composition, unless otherwise specified.
Resveratrol (also known as 5-parahydroxystyryl resorcinol, or 3,4′5-stilbenetriol) is an essential ingredient of the inventive composition. Resveratrol has the following structure:
Resveratrol may be obtained commercially from Sigma.
In general, the amount of resveratrol in the inventive compositions is in the range of from 0.00002 to 10% by weight composition. Preferably in order to lower cost and maximize the effect the amount of resveratrol is in the range of from 0.001% to 5% and most preferably is in the range of from 0.1% to 5%.
The composition according to the invention also comprises a cosmetically acceptable vehicle to act as a diluant, dispersant or carrier for resveratrol in the composition, so as to facilitate its distribution when the composition is applied to the skin.
Vehicles other than or in addition to water can include liquid or solid emollients, solvents, humectants, thickeners and powders. An especially preferred nonaqueous carrier is a polydimethyl siloxane and/or a polydimethyl phenyl siloxane. Silicones of this invention may be those with viscosities ranging anywhere from about 10 to 10,000,000 mm 2 /s(centistokes) at 25° C. Especially desirable are mixtures of low and high viscosity silicones. These silicones are available from the General Electric Company under trademarks Vicasil, SE and SF and from the Dow Corning Company under the 200 and 550 Series. Amounts of silicone which can be utilized in the compositions of this invention range anywhere from 5% to 95%, preferably from 25% to 90% by weight of the composition.
The cosmetically acceptable vehicle will usually form from 5% to 99.9%, preferably from 25% to 80% by weight of the composition, and can, in the absence of other cosmetic adjuncts, form the balance of the composition. Preferably, the vehicle is at least 80 wt. % water, by weight of the vehicle. Preferably, water comprises at least 50 wt. % of the inventive composition, most preferably from 60 to 80 wt. %, by weight of the composition.
In one embodiment of the invention, the inventive compositions also include an alpha-hydroxy acid.
Hydroxyacids enhance proliferation and increase ceramide biosynthesis in keratinocytes, increase epidermal thickness, and increase desquamation of normal skin resulting in smoother, younger looking skin.
The hydroxy acid can be chosen from alpha-hydroxy acids, beta-hydroxyacids (e.g. salicylic acid), other hydroxycarboxylic acids (e.g., dihydroxycarboxylic acid, hydroxy-dicarboxylic, hydroxytricarboxylic) and mixtures thereof or combination of their stereoisomers (DL, D or L).
Most preferred inventive compositions containing resveratrol anti-irritant include glycolic acid and/or lactic acid because these ingredients have been found to have potential to cause irritation yet they were found to be particularly efficacious at delivering cosmetic benefits.
Preferably the hydroxy acid is chosen from alpha-hydroxy acids having the general structure (1)
where M is H or a saturated or an unsaturated, straight or branched hydrocarbon chain containing from 1 to 27 carbon atoms.
Even more preferably the hydroxy acid is chosen from lactic acid, 2-hydroxyoctanoic acid, hydroxylauric acid, glycolic acid, and mixtures thereof. When stereo isomers exist, L-isomer is most preferred.
A particular advantage of the inventive compositions is that higher amounts of hydroxy acids may be employed without causing skin irritation. Preferably the amount of the hydroxy acid component present in the composition according to the invention is from 0.01 to 20%, more preferably from 2 to 12% and most preferably from 4 to 12% by weight.
It is to be understood that depending on the pH of the composition, the hydroxy acid may be present as a salt, e.g. ammonium or potassium or sodium salt.
Although the inventive compositions may have any pH in the general range of 2.5 to 10, the inventive compositions are particularly useful when they are at an acidic pH (especially if they contain a hydroxy acid), preferably 3-5 and most preferably at a pH of 3-4, because such compositions are particularly irritating.
Optional Skin Benefit Materials and Cosmetic Adjuncts
An oil or oily material may be present, together with an emulsifier to provide either a water-in-oil emulsion or an oil-in-water emulsion, depending largely on the average hydrophilic-lipophilic balance (HLB) of the emulsifier employed.
The inventive compositions preferably include sunscreens. Sunscreens include those materials commonly employed to block ultraviolet light. Illustrative compounds are the derivatives of PABA, cinnamate and salicylate. For example, octyl methoxycinnamate and 2-hydroxy-4-methoxy benzophenone (also known as oxybenzone) can be used. Octyl methoxycinnamate and 2-hydroxy-4-methoxy benzophenone are commercially available under the trademarks, Parsol MCX and Benzophenone-3, respectively. The exact amount of sunscreen employed in the emulsions can vary depending upon the degree of protection desired from the sun's UV radiation.
Emollients are often incorporated into cosmetic compositions of the present invention. Levels of such emollients may range from 0.5% to 50%, preferably between 5% and 30% by weight of the total composition. Emollients may be classified under such general chemical categories as esters, fatty acids and alcohols, polyols and hydrocarbons.
Esters may be mono- or di-esters. Acceptable examples of fatty di-esters include dibutyl adipate, diethyl sebacate, diisopropyl dimerate, and dioctyl succinate. Acceptable branched chain fatty esters include 2-ethyl-hexyl myristate, isopropyl stearate and isostearyl palmitate. Acceptable tribasic acid esters include triisopropyl trilinoleate and trilauryl citrate. Acceptable straight chain fatty esters include lauryl palmitate, myristyl lactate, and stearyl oleate. Preferred esters include coco-caprylate/caprate (a blend of coco-caprylate and coco-caprate), propylene glycol myristyl ether acetate, diisopropyl adipate and cetyl octanoate.
Suitable fatty alcohols and acids include those compounds having from 10 to 20 carbon atoms. Especially preferred are such compounds such as cetyl, myristyl, palmitic and stearyl alcohols and acids.
Among the polyols which may serve as emollients are linear and branched chain alkyl polyhydroxyl compounds. For example, propylene glycol, sorbitol and glycerin are preferred. Also useful may be polymeric polyols such as poly-propylene glycol and polyethylene glycol. Butylene and propylene glycol are also especially preferred as penetration enhancers.
Exemplary hydrocarbons which may serve as emollients are those having hydrocarbon chains anywhere from 12 to 30 carbon atoms. Specific examples include mineral oil, petroleum jelly, squalene and isoparaffins.
Another category of functional ingredients within the cosmetic compositions of the present invention are thickeners. A thickener will usually be present in amounts anywhere from 0.1 to 20% by weight, preferably from about 0.5% to 10% by weight of the composition. Exemplary thickeners are cross-linked polyacrylate materials available under the trademark Carbopol from the B. F. Goodrich Company. Gums may be employed such as xanthan, carrageenan, gelatin, karaya, pectin and locust beans gum. Under certain circumstances the thickening function may be accomplished by a material also serving as a silicone or emollient. For instance, silicone gums in excess of 10 centistokes and esters such as glycerol stearate have dual functionality.
Powders may be incorporated into the cosmetic composition of the invention. These powders include chalk, talc, kaolin, starch, smectite clays, chemically modified magnesium aluminum silicate, organically modified montmorillonite clay, hydrated aluminum silicate, fumed silica, aluminum starch octenyl succinate and mixtures thereof.
Other adjunct minor components may also be incorporated into the cosmetic compositions. These ingredients may include coloring agents, opacifiers and perfumes. Amounts of these other adjunct minor components may range anywhere from 0.001% up to 20% by weight of the composition.
Use of the Composition
The composition according to the invention is intended primarily as a product for topical application to human skin, especially as an agent for conditioning, moisturizing and smoothening the skin, and preventing or reducing the appearance of lined, wrinkled or aged skin.
In use, a small quantity of the composition, for example from 1 to 100 ml, is applied to exposed areas of the skin, from a suitable container or applicator and, if necessary, it is then spread over and/or rubbed into the skin using the hand or fingers or a suitable device.
Product Form and Packaging
The topical skin treatment composition of the invention can be formulated as a lotion, a cream or a gel. The composition can be packaged in a suitable container to suit its viscosity and intended use by the consumer. For example, a lotion or cream can be packaged in a bottle or a roll-ball applicator, or a propellant-driven aerosol device or a container fitted with a pump suitable for finger operation. When the composition is a cream, it can simply be stored in a non-deformable bottle or squeeze container, such as a tube or a lidded jar. The composition may also be included in capsules such as those described in U.S. Pat. No. 5,063,507, incorporated by reference herein. The invention accordingly also provides a closed container containing a cosmetically acceptable composition as herein defined.
The following specific examples further illustrate the invention, but the invention is not limited thereto. In all examples, resveratrol was obtained from Sigma. Student t-test was used to calculate all p-values.
EXAMPLE 1
This example illustrates that resveratrol is a phytoestrogen.
The following test was employed to determine whether resveratrol has an estrogen-like activity:
The ZR75 cell line is a ductal breast carcinoma cell line, originally isolated from malignant mammary epithelium of a sixty-three year old Caucasian female (Engel et al., Human breast carcinoma cells in continuous culture: A review., Cancer Res., 38: 4327-4339, 1978). This cell line contains receptors for estrogen, progesterone and other steroid hormones, but responds through an increase in proliferation only to estrogen. The cell line contains high affinity estrogen-specific receptors. Therefore, this cell line is used for testing estrogen-like activity (Markiewicz et al., In vitro bioassays of non-steroidal phytoestrogens, J. Steroid Biochem. Molec. Biol., 45: 399-405, 1993)
Methodology Used for Determining the Rate of DNA Synthesis in Cells
The incorporation of 3 H-thymidine by cultured cells was used as an assay of cell proliferation (both for ZR75 cells and for keratinocytes). Thymidine is one of four deoxynucleosides which are the monomeric units of DNA. Prior to cell division of a somatic cell, the complete genome of the cell undergoing cell division is replicated. This involves large scale DNA synthesis by the cell and enables both daughter cells to receive identical copies of the genetic material. When 3 H-thymidine is included in the culture media of cells which are synthesizing DNA in preparation for cell division then the labeled thymidine is incorporated into the newly synthesized DNA. The extent of incorporation of 3 H-thymidine into a population of cells is proportional to the rate of DNA synthesis by this population of cells and therefore an indication of their cellular proliferation.
ZR75 cells (from American Type Culture Collection, Rockville, Md.) were grown in RPMI1640 media (from Gibco Life Technologies) with 10% fetal bovine serum (FBS) , 100 units penicillin per ml and 100 units of streptomycin per ml. All incubations were performed at 37° C. in 5% CO 2 . The media did not contain Phenol Red (a weak estrogen mimetic). The cells were seeded at a density of one million per 75 cm2 flask. For the experiment, the cells were seeded in 24 well plates at 100,000 cells per ml per well.
After growing for 24 hours, the media was removed, the cells were washed with PBS (phosphate buffered saline, 0.01 M sodium phosphate, 0.138 M sodium chloride, 0.0027 M potassium chloride, pH 7.4) and 1 ml of RPMI 1640 without serum (but with streptomycin and penicillin) was added. Stock solutions of resveratrol in dimethyl sulfoxide (DMSO) and estradiol in water were prepared. Various concentrations of resveratrol and estradiol, as indicated in Table 1, were then dosed directly into each well. After another 24 hours, one μCi of [methyl-3H] thymidine was added to each well. The media was removed after 24 hours. The cells were washed once in PBS, the PBS was removed completely and the cells were left on ice to incubate with 1 ml per well of 10% TCA (trichloroacetic acid) for 30 minutes. The plates were washed 3 times with 5% TCA to remove all traces of thymidine which wasn't incorporated into the cells. 500 μl of 0.1M sodium hydroxide was added to each well and the plates were incubated at room temperature for at least 30 minutes. 250 μl of each sample was transferred to scintillation vials and after adding 5 mL of counting fluid, the vials were counted for 5 minutes each on a setting for tritium. Data from quadruplicate wells were calculated as % thymidine incorporation into DNA compared to that of control wells which did not receive any resveratrol or estradiol. Values were expressed as mean of quadruplicate wells +/− standard deviation.
The results that were obtained are summarized in Table 1
TABLE 1
EXPT 1
DNA
EXPT 2
synthesis.
DNA
Compound
(% of
EXPT 1
synthesis
EXPT 2
(μM)
Control)
p value
Control)
p value
Control
100 ± 20.4
—
100 ± 1.9
—
(water)
Estradiol
220 ± 11
0.00059
133.4 ± 29
0.062
(1 nM)
10 nM
210 ± 9.7
0.00079
152 ± 17.7
0.0011
100 nM
205 ± 15.6
0.0016
156 ± 11.7
0.00008
1000 nM
190 ± 24.5
0.0068
142 ± 18.3
0.0039
Control
100 ± 7.0
—
100 ± .08
—
(DMSO)
Resveratrol
69.7 ± 10.0
56.8 ± 4.2
(0.5 μM)
1 μM
58.8 ± 9.0
60.5 ± 3.6
5 μM
158.8 ± 4.1
0.000008
10 μM
207.8 ± 32.5
0.0026
163 ± 13.7
0.00029
15 μM
119 ± 2.5
0.00009
20 μM
134.8 ± 21.4
0.612
68 ± 3.9
40 μM
60.8 ± 26.4
50 μM
4.1 ± 1.4
The control 3 H thymidine incorporation value for experiment 1 was 71513 cpm and the control for experiment 2 was 114958 cpm.
The results in Table 1 demonstrate that estradiol, a known estrogen, stimulated proliferation of ZR 75 cells, as expected. Resveratrol increased proliferation of ZR 75 cells at a concentration from 5 to 20 μM.
EXAMPLE 2
This example demonstrates that resveratrol inhibits proliferation of keratinocytes.
1. Normal human keratinocytes isolated from neonatal foreskins by trypsin treatment were grown in Dulbecco's modified Eagle's medium (DME)/5% fetal calf serum in the presence of mitomycin C treated 3T3 mouse fibroblasts for establishing dividing keratinocyte colonies. Keratinocytes were grown under the above condition until their third passage.
2. For the experiments, third passage keratinocytes were plated into a serum-free keratinocyte growth medium (KGM; obtained from Clonetics, San Diego, Calif.) containing 0.09 mM calcium. About 30,000 cells were plated into each well of 6 well cell culture plates and grown for 5 days, until the cells reach about 40% confluence.
3. Medium was changed to fresh medium (KBM; obtained from Clonetics) and resveratrol at various concentrations as indicated in Table 2 was added to the medium from a DMSO (Dimethylsulfoxide) stock solution. The final DMSO concentration in the cultures was 0.1%. Control cultures received no resveratrol but were dosed with 0.1% DMSO. Each concentration was tested in three separate wells. After four hours, 1 μCi of 3 H-thymidine (Amersham Corp., Sp activity 40 Ci/mmol) was added to 1 ml of medium in each well. The cells were incubated for 2 hours. The amount of 3 H-thymidine associated with the cellular DNA of keratinocytes was assessed as described below.
4. The medium was aspirated, and the wells washed with 1 ml PBS. The DNA and proteins of the cells in the plate were then precipitated by adding 1 ml of ice-cold 10% TCA. The plates were left on ice for 30 minutes to complete the precipitation process. TCA was then aspirated and each well was then washed 4 times with 5% TCA. The cells in the wells were dissolved in 0.5 ml of 1.0N sodium hydroxide. 200 μl was then transferred to a scintillation vial for assessing thymidine incorporation and 25 μl was used for a protein assay using BCA protein assay reagent as described below. 5 ml of a scintillation fluid (Scintiverse) was added to the rest of the solution in the vial, and the vials were counted in a scintillation counter to determine the amount of radioactivity in each vial.
BCA (Bicinchoninic Acid)—Protein Assay
25 μl of cell suspension were placed in a 96 well plate. Standards of BSA (bovine serum albumin) in 0.1N Sodium Hydroxide were also pipetted in triplicate in the same 96 well plate. Pierce BCA protein assay reagent was added (200 μl/well) and plate was incubated for 2 hours at room temperature. Absorbance was read at a wavelength of 570 nm on a Dynatech MR7000 plate reader.
The DNA synthesis rate was then calculated as cpm 3 H-thymidine incorporated into total cellular DNA/μg of cell protein for each individual well. Mean and standard deviation for each group were also calculated. These numbers were also expressed as percent of control wells. Each data point is expressed as mean of triplicate wells±standard deviation.
The results that were obtained are summarized in Table 2. p values of less than 0.5 were considered to indicate statistical significance.
TABLE 2
DNA synthesis
Resveratrol
(cpm/μg
(μM)
protein)
% inhibition
P value
Experiment 1
0
29.52 ± 4.44
0
—
50
0.62 ± 0.09
98
0.012
Experiment 2
0
17.17 ± 1.21
0
—
0.78
11.57 ± 1.7
33
0.053
1.56
8.89 ± 1.12
48
0.016
3.12
5.11 ± 0.27
70
0.0074
6.25
2.45 ± 0.56
86
0.0053
12.5
1.07 ± 0.11
94
0.003
25
0.58 ± 0.05
97
0.0029
50
0.44 ± 0.12
97
0.0028
As can be seen from the results in Table 2, concentrations as low as 1.56 μM resveratrol decreased DNA synthesis of keratinocytes significantly. 1.56 μM resveratrol reduced keratinocyte proliferation by as much as 50%. In both experiments, 50 μM resveratrol inhibited DNA synthesis completely.
EXAMPLE 3
Example 2 was repeated at various additional concentrations of resveratrol. The results that were obtained are summarized in Table 3.
TABLE 3
EFFECT OF RESVERATROL AT LOW CONCENTRATIONS
ON THYMIDINE UPTAKE IN KEPATINOCYTES
DNA
Statistically
synthesis
Significant
Resveratrol
(cpm/μg
%
(at p less
concentration
protein
inhibition
P value
than 0.5)
0.0 μM
63.4 ± 5.2
—
—
—
0.1 μM
60.4 ± 4.1
5
0.502
NO
0.2 μM
56.3 ± 3.0
12
0.079
NO
0.3 μM
58.8 ± 0.4
7
0.254
NO
0.4 μM
54.2 ± 1.2
14
0.051
NO
0.6 μM
59.3 ± 5.5
6
0.310
NO
0.8 μM
44.4 ± 2.6
30
0.00013
YES
1.0 μM
37.7 ± 4.0
40
<0.0001
YES
2.0 μM
25.7 ± 2.4
59
<0.0001
YES
It can be seen from the results in Table 3 that resveratrol was not effective at reducing keratinocyte proliferation at concentrations lower than 0.8 μm (or 0.000018 wt. %), including a very low concentration of 0.33 μm which would be the maximum concentration present in 0.5% grape extract disclosed by JP 6336421.
EXAMPLE 4
This example demonstrates that resveratrol induces differentiation of keratinocytes:
Methodology for Transglutaminase Measurement
During the process of terminal differentiation in the epidermis, a 15 nm thick layer of protein, known as the cornified envelope (CE) is formed on the inner surface of the cell periphery. The CE is composed of numerous distinct proteins which have been cross-linked together by the formation of N-((-glutamyl) lysine isodipeptide bonds catalyzed by the action of at least two different transglutaminases expressed in the epidermis. Transglutaminase (TG-1) is expressed in abundance in the differentiated layers of the epidermis, especially the granular layer, but is absent in the undifferentiated basal epidermis. Thus, TG-1 is a useful marker of epidermal keratinocyte differentiation with high TG-1 levels indicating a more differentiated state. An ELISA based TG-1 assay, using a TG-1 antibody, was used to assess the state of differentiation of the cultured keratinocytes in the examples that follow.
The level of TG-1 was measured as follows. Keratinocytes were obtained as described in Example 2. For the experiment, about 30,000 cells were plated into each well of 6 well plates and grown for five days, until the cells reach about 20-30% confluence. 2 ml/well of fresh KGM were added daily with 2 μl of 2-50 mM resveratrol in DMSO for 3 days. Control wells also received 2 μl of DMSO. After 3 days of treatment, cells were washed twice with PBS and placed in freezer for 2 hours. Cells were then thawed for 2 hours. DNA content of the cells were quantitated by using the DNA binding flurophore, bis-benzimidazole (Hoechst 33258) and measuring the specific fluorescence of the DNA-bound flurophore at 450 nm (excitation at 360 nm).
TG-1 levels of the cells in the wells were determined using the TG-1 specific monoclonal antibody (BC1) (first antibody) (obtained from Amersham Life Sciences) and using a peroxidase labeled rabbit antimouse IgG fragment (second antibody). The plates were blocked by 5% nonfat milk in TBS (Tris buffered saline, 0.01 M Tris, 0.150 M sodium chloride, pH 8.0) for one hour followed by 2 hour incubation with the first antibody (1:4,000 fold dilution) in 1% milk/TBS at room temperature. After rinsing the plates three times with 1% milk/TBS containing 0.05% Tween 20, the plates were incubated with 1:4000 dilution of the second antibody at room temperature for two hours. The plates were rinsed three times with 1% milk/TBS/Tween and three times with TBS. Color was developed by incubation with o-phenylene diamine and hydrogen peroxide. The absorbance was read at 492 nm on a Ultrospec 3000 spectrophotometer (Pharmacia Biotech) and TG-1 levels were calculated as Abs/DNA fluorescence. The mean±standard deviation of at least 3 separate wells were used for calculation and statistical analysis of the data. Values were expressed as absorbance for TG-1 per arbitrary unit of DNA fluorescence of triplicate wells±standard deviation. Results were also expressed as % of control.
The results that were obtained are summarized in Table 4.
TABLE 4
Resver-
atrol
TG-1 levels/μg
(μM)
DNA
% of control
p value
EXPERIMENT 1
0
μM
6.74 ± 0.79
—
—
10
μM
8.49 ± 1.77
126
0.1195
25
μM
10.92 ± 2.29
162
0.0008
50
μM
22.2 ± 1.50
329
0.0001
EXPERIMENT 2
0
μM
1.91 ± 0.03
—
—
2
μM
3.42 ± 0.42
179
<0.0001
5
μM
3.51 ± 0.41
184
<0.0001
10
μM
3.61 ± 0.17
189
<0.0001
25
μM
4.69 ± 0.21
246
<0.0001
50
μM
4.65 ± 0.46
243
<0.0001
10 μM resveratrol was not significantly different from control in Experiment 1 due to normal experimental variations in biological systems, but all other concentrations significantly increased transglutaminase expression of keratinocytes, thus proving that resveratrol increases keratinocyte differentiation. In Experiment 2 all concentrations of resveratrol of 2 μM and higher significantly increased keratinocyte differentiation.
EXAMPLE 5
This example demonstrates that resveratrol inhibits melanin production by skin cells, and thus is a suitable skin lightening active.
B16 F1 cells were purchased from ATCC (Rockville, Md.) Subconfluent B16 cells were seeded in 96 well microtiter plates at a density of 5000 cells/well and cultured overnight in DMEM (Life Technologies, NY) containing 10% Fetal Bovine Serum, 1% penicillin/streptomycin without phenol red) at 37° C. under 5% CO2. After 24 hours, the media was replaced with fresh media containing the treatments. Cells were incubated for 72 hours at which time melanin was visible in the control treatment. Next, the melanin containing media from each well was transferred to a clean 96 well plate and quantified by reading the absorbance at 530 nm using a microplate Spectrophotometer.
In order to ensure that melanin inhibition was not simply due to cell killing, cell viability was assessed by neutral red dye uptake. After the removal of media, 200 μL of pre-warmed medium containing 25 μg/ml neutral red dye was added to each well and incubated for 3 hours. Cells were washed 2× with PBS. The dye was extracted by adding 100 L of 50 H2O: 49 ethanol: 1 acetic acid and then gently shaken at room temperature for 20 minutes. The dye was quantified by reading the absorbance at 530 nm. Only viable cells are expected to take up the dye and the absorbance is directly proportional to the number of viable cells surviving the treatment.
For each treatment, the average of four replicate readings was calculated and expressed as percent of the average for the untreated control. Statistical significance was determined using the student's t-test (reported only for the treatments that showed greater than 50% viability).
The results that were obtained are summarized in Table 5. The lower the % melanin value (with a viability value of >50%), the better the skin lightening potential.
TABLE 5
Sample
% Melanin
% Viability
Control
100
100
Resveratrol
80*
94.6
10 μM
Resveratrol
4.0*
86.8
25 μM
Resveratrol
3.9*
69.2
50 μM
Resveratrol
6.6
1.8
100 μM
It can be seen from the results in Table 5 that resveratrol inhibited melanin production by skin cells at all concentrations tested, where viability was greater than 50%.
EXAMPLE 6
This example demonstrates that resveratrol alleviates skin inflammation that may be caused by alpha-hydroxy acids.
Resveratrol is a known cyclo-oxygenase inhibitor. Inhibition of cyclooxygenase reduces the conversion of arachidonic acid to pro-inflammatory substances such as prostaglandins, including PGE2. While inhibition of cyclooxygenase would be expected to reduce inflammation, not all cyclooxygenase inhibitors reduce irritation potentially associated with a cosmetic ingredient such as alpha hydroxy acids.
EXAMPLE 6A
Irritation Test Method
Four Exposure Patch Test: The objective was to compare the level of irritation produced by various test materials after repeated patch applications. The test materials were held in contact with the skin under occlusive conditions. The outer upper arm of the panelist was designated as thea rea of application. Bandage type dressing (Scanpor tape) was used to hold the patches (25 mm Hill Top Chamber fitted with 18 mm diameter disc of Webril padding) into place. Both upper arms of the panelist were used. Patches were applied in a balanced random order.
Patches were applied at 9:00 o'clock Monday morning and removed at 9:00 o'clock Tuesday morning (24 hour exposure). A new set of patches was applied at 3:00 o'clock Tuesday afternoon and removed Wednesday morning at 9:00 o'clock (18 hour exposure). A third set of patches was applied at 3:00 o'clock Wednesday afternoon and removed Thursday morning at 9:00 o'clock (18 hour exposure). A final set of patches was applied at 3:00 o'clock Thursday afternoon and removed Friday morning at 9:00 o'clock (18 hour exposure).
Each time the patches were removed, the sites were rinsed with warm water and patted dry. The test sites were then marked with a surgical skin marking pen to ensure location for grading and subsequent patch applications. Test sites were evaluated at 3:00 p.m. on Tuesday, Wednesday, Thursday, and Friday of the study, prior to re-patching.
Skin irritation such as moderate redness, dryness, and/or itching of the test site is expected. Swelling of the test sites was possible. If any test site had moderate redness or any swelling at any evaluation, that particular test site was not repatched.
The test sites on each arm were visually ranked by two trained examiners under consistent lighting. The test sites were ranked in order of severity. The examiner ranking responses at the first evaluation period continued ranking the sites each day throughout the study.
In ranking the reactions, the site with the most severe response was given the lowest score. The site with the second most severe response was given the second lowest score, etc. There was no forced ranking. If two or more sites had no response or the same response (no difference between sites), an average of the ranks was assigned. If a site had been discontinued, due to degree of irritation, the site retained the rank it received at the time dosing was discontinued.
Statistical Analysis
The ranking results from the patch treatments were statistically compared by nonparametric statistical methods. The test materials containing the anti-irritants were compared to the corresponding control containing only hydroxy acid, using Friedman's Rank Sum at each evaluation point with the panelist acting as a block (i.e., each panelist was tested with each test treatment). A p-value of less than 0.10 was considered to indicate statistical significance.
Compositions containing ingredients as indicated in Table 6A, were tested using the Irritation Test Method. Twenty (20) subjects were tested. The results that were obtained are summarized in Table 6A. The higher the sum of ranks, the less is the irritation.
BASE FORMULA
FULL CHEMICAL NAME OR
TRADE NAME AND %
CFTA NAME
ACTIVE
WT. %
water, DI
46.54
disodium EDTA
Sequesterene Na2
0.05
magnesium aluminum
Veegum Ultra
0.6
silicate
methyl paraben
Methyl Paraben
0.15
simethicone
DC Antifoam Emulsion
0.01
butylene glycol 1,3
Butylene Glycol 1,3
3.0
hydroxyethylcellulose
Natrosol 250 HHR
0.5
glycerine, USP
Glycerine USP
2.0
xanthan gum
Keltrol 1000
0.2
triethanolamine
Triethanolamine 99 (%)
1.2
stearic acid
Pristerene 4911
3.0
propyl paraben NF
Propylparaben NF
0.1
glyceryl hydrostearate
Naturechem GMHS
1.5
stearyl alcohol
Lanette 18 DEO
1.5
isostearyl palmitate
Protachem ISP
6.0
C12-15 alcohols octanoate
Hetester FAO
3.0
dimethicone
Silicone Fluid 200
1.0
(50 cts)
cholesterol NF
Cholesterol NF
0.5
sorbitan stearate
Sorbitan Stearate
1.0
butylated hydroxytoluene
Embanox BHT
0.05
tocopheryl acetate
Vitamin E Acetate
0.1
PEG-100 stearate
MYRJ 59
2.0
sodium stearoyl lactylate
Pationic SSL
0.5
retinyl palmitate
Vit. A Palmitate 84%
0.06
hydroxy caprylic acid
Hydroxy caprylic acid
0.1
water, DI
q.s. to
99.80
alpha-bisabolol
Alpha-bisabolol
0.2
pH
7-8
TABLE 6A
SUM OF
SUM OF RANKS
RANKS
COMPOSITION
INGREDIENTS
(Day 1)
(Day 4)
1
Base Formula
65.5
79.5
2
Base Formula +
63
72
8% Glycolic acid
3
Composition #2 +
85 a
66
0.1% resveratrol
a: significantly less irritating than composition 2.
It can be seen from the results in Table 6A that resveratrol (Composition 3) significantly reduced the irritation induced by composition #2 (containing 8% glycolic acid) on Day 1, after the initial exposure to composition #2.
Comparative Example 6B
Compositions containing ingredients as indicated in Table 6B, were tested using the Irritation Test Method described in Example 6A. Twenty-two (22) subjects were tested. The results that were obtained are summarized in Table 6B. The higher the sum of ranks, the less is the irritation.
TABLE 6B
SUM OF
SUM OF RANKS
RANKS
COMPOSITION
INGREDIENTS
(Day 1)
(Day 4)
1
Base Formula
81
90.5
2
Base Fomnula +
75
73.5
8% Glycolic acid
4
Composition #2 +
71.5
65.5
5% Ibuprofen
It can be seen from the results in Table 6B, that ibuprofen, a known anti-inflammatory ingredient (composition #4) did not reduce the irritation of the Formula which contains 8% glycolic acid (composition #2).
Comparative Example 6C
Compositions containing ingredients as indicated in Table 6C, were tested using the Irritation Test Method, as described in Example 6A. Nineteen (19) subjects were tested. The results that were obtained are summarized in Table 6C. The higher the sum of ranks ranks, the less is the irritation.
TABLE 6C
SUM OF
SUM OF RANKS
RANKS
COMPOSITION
INGREDIENTS
(Day 1)
(Day 4)
2
Base Formula + 8%
70
62
Glycolic acid
5
Composition #2 +
53.5
52.5
1% Indomethacin
It can be seen from the results in Table 6C, that indomethacin, a known cyclo-oxygenase inhibitor and anti-inflammatory ingredient (composition #5) did not reduce the irritation of the Formula which contains 8% glycolic acid (composition #2).
Examples 7-12 illustrate skin care compositions according to the present invention. The compositions can be processed in conventional manner. They are suitable for cosmetic use. In particular, the compositions are suitable for application to wrinkled, lined, rough, dry, flaky, aged and/or UV-damaged skin to improve the appearance and the feel thereof as well as for application to healthy skin to prevent or retard deterioration thereof. The composition are also particularly suitable to lighten the skin and/or to reduce the irritation, sting, or inflammation that may be associated with the use of alpha-hydroxy acids.
EXAMPLE 7
This example illustrates a high internal phase water-in-oil
emulsion incorporating the inventive composition.
% w/w
RESVERATROL
0.5
1,3-dimethyl-2-imidazolidinone
0.2
Brij 92*
5
Bentone 38
0.5
MgSO 4 7H 2 O
0.3
Butylated hydroxy toluene
0.01
Perfume
qs
Water
to 100
*Brij 92 is polyoxyethylene (2) oleyl ether
EXAMPLE 8
This example illustrates an oil-in-water cream incorporating
the inventive composition.
% w/w
RESVERATROL
2
Glycolic Acid
8
Mineral oil
4
1,3-dimethyl-2-imidazolidinone
1
Brij 56*
4
Alfol 16RD*
4
Triethanolamine
0.75
Butane-1,3-diol
3
Xanthan gum
0.3
Perfume
qs
Butylated hydroxy toluene
0.01
Water
to 100
*Brij 56 is cetyl alcohol POE (10)
Alfol 16RD is cetyl alcohol
EXAMPLE 9
This example illustrates an alcoholic lotion incorporating
the composition according to the invention.
% w.w
RESVERATROL
5
1,3-dimethyl-2-imidazolidinone
0.1
Ethanol
40
Perfume
qs
Butylated hydroxy toluene
0.01
Water
to 100
EXAMPLE 10
This example illustrates another alcoholic lotion containing
the inventive composition.
% w/w
RESVERATROL
10
1,3-dimethyl-2-imidazolidinone
0.01
Ethanol
40
Antioxidant
0.1
Perfume
qs
Water
to 100
EXAMPLE 11
This example illustrates a suncare cream incorporating the
composition of the invention:
% w/w
RESVERATROL
2
1,3-dimethyl-2 imidazolidinone
0.2
Silicone oil 200 cts
7.5
Glycerylmonostearate
3
Cetosteryl alcohol
1.6
polyoxyethylene-(20)-cetyl
1.4
alcohol
Xanthan gum
0.5
Parsol 1789
1.5
Octyl methoxycinnate (PARSOL MCX)
7
Perfume
qs
Color
qs
Water
to 100
EXAMPLE 12
This example illustrates a non-aqueous skin care composition
incorporating the inventive combination.
% w/w
RESVERATROL
5
1,3-dimethyl-2-imidazolidinone
1
Silicone gum SE-30 1
10
Silicone fluid 345 2
20
Silicone fluid 344 3
50.26
Squalene
10
Linoleic acid
0.01
Cholesterol
0.03
2-hydroxy-n-octanoic acid
0.7
Vitamin E linoleate
0.5
Herbal oil
0.5
Ethanol
2
1 A dimethyl silicone polymer having a molecular weight of least 50,000 and a viscosity of at least 10,000 centistokes at 25° C., available from GEC
2 Dimethyl siloxane cyclic pentamer, available from Dow Corning Corp.
3 Dimethyl siloxane tetramer, available from Dow Corning Corp.
It should be understood that the specific forms of the invention herein illustrated and described are intended to be representative only. Changes, including but not limited to those suggested in this specification, may be made in the illustrated embodiments without departing from the clear teachings of the disclosure. Accordingly, reference should be made to the following appended claims in determining the full scope of the invention. | 4y
|
RELATED APPLICATION
This application is a continuation-in-part of U.S. Ser. No. 322,152, filed Mar. 10, 1989, now abandoned.
TECHNICAL FIELD
The present invention relates generally to the detection of cancer and, more specifically, to a mixed mercury-nickel (Hg-Ni) composition for use in screening patients for the presence of cancer.
BACKGROUND OF THE INVENTION
An increasing interest in cancer diagnosis has led to an attempt to find reagents useful in the diagnosis of cancer by their reaction with components of urine to produce a colored precipitate. Since a variety of metabolites are excreted in human urine, it has been suggested that the amount of specific metabolites in a patient's urine will vary depending upon the disease state of the patient. It has been found that the distribution of nuclear magnetic resonance (NMR) signals of the urine of cancer patients are quite different from those of the urine of noncancer patients. Specifically, NMR signals in the range of 3.00 ppm to 3.09 ppm are commonly observed in the urine of cancer patients.
As disclosed in Korean Patent No. 21558, the specific NMR signals observed in the urine of cancer patients are related to the presence of phenolic metabolites, such as tyrosine. Korean Patent No. 21558 also discloses a reagent (i.e., Millon's reagent) for use as a cancer diagnosis agent which identifies the presence of tyrosine in urine by the formation of a colored precipitate.
However, the use of Millon's reagent in the urine test is highly disadvantageous because of the instability of the precipitate formed in the reaction. The reason for this instability is that the mercury ions in Millon's reagent have a high complex-forming capacity but a relatively low ionization tendency in comparison with other metal ions. Thus, it is easily interfered with by inorganic salts and aromatic organocompounds that are coexisting in the urine sample.
Accordingly, there is a need in the art for reagents which react with the specific components present in the urine of cancer patients, and which do not exhibit the disadvantages, such as instability of the colored precipitate, associated with Millon's reagent.
SUMMARY OF THE INVENTION
The present invention discloses a method for detecting cancer in humans by contacting a sample of human urine with a mixed Hg-Ni composition which reacts with the urine to form a colored precipitate to indicate the presence of cancer. The present invention also discloses a composition for use in the above method. The composition comprises mercury, nickel, nitric acid and distilled water, wherein the nickel is present at a concentration ranging from about 0.1 to about 0.3 parts by weight to 1 part by weight mercury, wherein the nitric acid is about 9 M and is present in an amount ranging from about 2 ml to about 5 ml of nitric acid to 1 gram mercury, and wherein distilled water is present in an amount substantially equal to the volume of nitric acid. The composition may also be admixed with a material to form a gel.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a mixed mercury-nickel (Hg-Ni) composition which can be used in screening for the presence of cancer through a color reaction by identifying the phenolic metabolites which exist in greater quantities in cancer patients than in persons without cancer.
Millon's reagent is a nitric acid solution of mercury. In order to compensate for the disadvantageous properties of mercury, tyrosine was reacted with other metallic ions in place of the mercury ions, based on the fact that the reaction between Millon's reagent and tyrosine is primarily due to the formation of a complex with said mercury ions. As a result, it was confirmed that tyrosine also reacts with nitric acid solutions of either cadmium (Cd), zinc (Zn), copper (Cu) or nickle (Ni) to form a red complex compound.
However, when the nitric acid solutions of these metals are applied to the urine samples of cancer patients in place of Millon's reagent, no reaction is observed. It is postulated that the reasons for this are that: (1) the complex-forming capacity of these metal ions is relatively low when compared to that of the mercury ion, and (2) the content of aromatic amines present in the urine of the cancer patients is so small that it does not reach the concentration level capable of initiating the reaction with these alternative metal ions.
These metals have a low complex-forming capacity, and a high ionization tendency. Accordingly, it is proposed that these metals may function as either a substitute for mercury in the mercury complexes or as a cross-linking agent between the complexes to stabilize the complexes. On the basis if this, Millon's reagent was combined with each of the above-mentioned metals and it was found that the combination of Millon's reagent with nickel gave a more stable precipitate than that of Millon's reagent alone. That is, when Millon's reagent is used alone, the complex obtained is unstable and dissolved easily, depending on the condition of the sample, and therefore, the reading of the results is difficult.
However, the mixed Hg-Ni composition of the present invention does not produce such an undesired phenomenon and the reading of the reaction results is simplified because the color of the reaction precipitate is stable and persists for a longer period of time.
The mixed Hg-Ni composition of the present invention includes mercury, nickel, nitric acid, and distilled water. Preferably, the amount of nickel needed for maintaining the stable color of the precipitate during the reading period is 0.1 to 0.3 parts by weight of nickel per one part by weight of mercury. If the mixing ratio between mercury and nickel contains too much mercury, the precipitate obtained is unstable. If the ratio is higher in nickel, the amount of the precipitate is reduced bringing about a poor diagnostic effect. Therefore, it is necessary to maintain a suitable mixing ratio.
The nitric acid included in the mixed Hg-Ni composition is preferably 9 molar and used at a ratio of 2 to 5 ml of nitric acid per gram of mercury. Distilled water is used in a substantially similar amount by volume to the nitric acid. However, if distilled water is used in excess, the amount of the precipitate is reduced, while too small an amount of distilled water will result in an unstable precipitate.
When 0.04 ml of the mixed Hg-Ni composition is added to 1 ml of a urine sample, a red precipitate is observed in the urine of cancer patients, while a white precipitate is observed in the urine of normally healthy persons.
In addition, the mixed Hg-Ni composition of the present invention can be applied to a screening test which is used to conveniently and rapidly detect for the presence of tyrosine amines in a large number of urine specimens. If the mixed Hg-Ni composition is mixed with agar to form a jelly phase, it becomes a suitable formulation for treatment, storage and transport. The jelly phase may be prepared by adding 3 to 5 g of agar in 100 ml of distilled water and heating to form a solution. The agar used therein should be better than the lower limit of the Korean Pharmacopoeia standard in purity. The mixed Hg-Ni composition is then added to the agar solution. Preferably, the mixed Hg-Ni composition is combined with the agar solution in a ratio of 1:10 by volume. After mixing, the resulting mixture is divided into test tubes of 1 cm diameter and filled to approximately 2 cm in height, followed by cooling at room temperature.
After about 5 ml of the urine specimen is added to each tube in which the jelly phase was formed, it remains standing for about five minutes in order to produce the precipitate between the layers of the mixture and the urine specimen.
If the precipitates are white or red, these can be read to be negative or positive, respectively. The advantage of the jelly phase is to reduce the hazardous conditions posed by the solution form of the mixed Hg-Ni composition. Thus, hazard to the experimenter may be decreased by having the nitric acid in a jelly phase rather than solution. On the other hand, the reactive sensitivity of the jelly is apt to decline somewhat compared to that of the solution.
The following examples are offered by way of illustration and not by way of limitation.
EXAMPLE 1
10 ml of a solution of 50 g of metallic mercury dissolved in 50 ml of 9 M nitric acid is mixed with 20 ml of a solution of 5 g of metallic nickel dissolved in 50 ml of nitric acid, and the resulting solution is then diluted with the addition of 30 ml of distilled water.
EXAMPLE 2
Using a glass stirrer, 5 g of agar is dissolved in 10 ml of distilled water in a 300 ml beaker with heat prior to sufficiently mixing with 10ml of the reagent solution prepared in Example 1 The mixed solution is poured into a glass tube of 1 cm diameter and is filled to 2 cm high, and is then solidified by cooling at room temperature.
EXAMPLE 3
The mixed Hg-Ni compositions prepared in Examples 1 and 2 above were tested in the following assay:
Three ml of a subject's urine is taken up prior to adding 0.15 ml of the mixed Hg-Ni composition solution prepared in Example A red-colored precipitate formed therefrom is judged as being positive and the white-colored precipitate formed is judged as being negative.
Alternatively, when the jelly phase test method is employed, 5 ml of the subject's urine is added to the mixed Hg-Ni composition jelly prepared in Example 2. After waiting five minutes, a red or a white band of precipitate is formed at the boundary between the jelly and urine phases and is judged as being positive or negative, respectively.
Urine samples obtained from 34 patients who were judged as suffering from cancer by a histological assay and urine samples from 35 non-cancer patients were tested in the manner described above. The test results for all 69 patients are given in Table 1.
The test confirmed the presence of cancer which was previously detected under histological examination. Thus, the clinical value of the mixed Hg-Ni composition of the present invention is that it can be utilized to aid in the diagnosis of cancer. In this way, large populations can be screened for the potential presence of cancer, prior to employing close examination.
It is emphasized that cancer should be detected early so that treatment can be initiated at an early stage to obtain better success rates. Accordingly, the screening method for the diagnosis of cancer using the mixed Hg-Ni composition of the present invention is useful for early detection of cancer.
TABLE 1______________________________________The results of mixed Hg-Ni salt solution and jellied formin cancer and non-cancer patients Results jellyNo. age sex diagnosis type solution form______________________________________ 1 43 F breast ca Malignant + + 2 49 M laryngeal ca Malignant + + 3 50 M stomach Malignant + + 4 63 F lung squam ca Malignant + + 5 47 M lectal ca Malignant + + 6 57 M transi, cell ca Malignant + + 7 63 M hepatocell ca Malignant + - 8 69 M stomach ca Malignant + + 9 69 F esophageal ca Malignant + +10 51 M stomach ca Malignant + +11 53 F rectal ca Malignant + +12 46 M lung ca Malignant + -13 45 M laryngeal ca Malignant + +14 60 M GB ca Malignant + +15 64 M stomach ca Malignant - -16 17 F ALL Malignant + +17 64 F bronchogenic ca Malignant - -18 59 M hepatocell ca Malignant + +19 48 M stomach ca Malignant + +20 49 M periampul ca Malignant + +21 36 F cervical ca Malignant + -22 62 M stinacg ca Malignant + +23 63 M bronchogenic ca Malignant + +24 13 M ALL Malignant + +25 67 M colon ca Malignant + +26 79 M bronchogenic ca Malignant + +27 70 F lung ca Malignant + +28 80 F stomach ca Malignant - -29 32 M stomach ca Malignant + +30 57 M stomach ca Malignant + +31 50 F mullerian ca Malignant + +32 64 M stomach ca Malignant + +33 70 M stomach ca Malignant - -34 35 F Inv. ductal ca Malignant - -35 72 M leiomyosarcoma Benign - -36 61 M pneumonia Normal - -37 48 F GB stone Normal - -38 36 M DM Normal - -39 44 M pyelonephritis Normal - -40 30 M TB, RA, sjogren Normal + +41 18 M enchondroma Benign - -42 21 M pleurisy TD Normal - -43 29 F pregnancy Normal - -44 53 F hashimoto Normal - -45 39 F uelomyoma Benign + -46 54 F unknown, CYTO Normal - -47 42 M pleurisy, TB Normal - -48 64 M appendicitis Normal - -49 53 F insert. obstuct Normal - -50 16 F bronchial cleft Normal - -51 6 F lipomatosis Normal - -52 65 M CHR gastritis Normal - -53 61 F CHR bronchitis Normal - -54 64 F renal cyst Normal + +55 26 F nonsp colitis Normal - -56 37 F placenta previa Normal - -57 36 F leimyoma Benign - -58 55 M pleural TB Normal - -59 70 M CHR PN Normal - -60 43 F adenomyosis Normal - -61 37 M bronchiectasis Normal - -62 26 M anal fistula Normal - -63 74 M hemoptysis Normal - -64 38 F hydroureter Normal - -65 55 M gastritis Normal - -66 67 F GB stone Normal - -67 24 M pleura TB Normal - -68 28 F L/N TB Normal - -69 62 F acute cytosis Normal - -______________________________________
The detection sensitivity, detection specificity, false positive rate, false negative rate, positive predictive value and negative predictive valve are summarized in Table 2 utilizing the following calculations: ##EQU1##
TABLE 2______________________________________ Solution Jelly Form______________________________________Detection sensitivity 78.4% 76.5%Detection specificity 91.4% 94.3%False positive rate 8.6% 5.7%False negative rate 21.6% 23.5%Positive predictive value 90.6% 92.9%Negative predictive value 86.5% 80.5%______________________________________
From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and the scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims. | 4y
|
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0001] This invention was made with U.S. Government support under contract No. 06C2908 awarded by the Department of Defense. The U.S. Government has certain rights in this invention.
FIELD
[0002] The present invention relates to radio frequency and microwave connectors, and more particularly to grounding methods for printed wiring board edge-launch connectors.
BACKGROUND
[0003] Printed wiring boards (PWBs) are used extensively to produce electronic circuits. PWBs are typically formed as sandwiches of one or more layers of dielectric material and one or more layers of conductive material, in which the conductive material may be formed, by etching, into patterns including lines, known as traces, which form connections in a circuit. Holes with conductive walls, known as vias, may be formed in the dielectric layers to provide electrical connections between conductive layers.
[0004] A circuit on a PWB may include connectors, and components such as resistors, capacitors, or transistors, which may be installed on the PWB by applying solder paste to the outer conductive layer at the locations where the components are to be installed, placing the components on the PWB, and heating the assembly in a solder reflow oven which melts the solder, soldering the components in place. Alternately, conductive epoxy may be used instead of solder.
[0005] Coaxial connectors known as board edge-launch connectors may be installed at the edge of a PWB to provide connections to other parts of a system. For example, a PWB with an array of connectors along one edge may be installed in a system by sliding it into a chassis so that the connectors on the PWB connect simultaneously to an array of corresponding mating connectors in the chassis. Such an arrangement, in which there is no opportunity for a human operator or technician to align and connect the connectors individually and where the technician may not be able to see the connectors, is known as a blind-mate application.
[0006] Coaxial connectors individually soldered to a PWB may be unsuitable for use in a blind-mate application because the process for soldering such connectors to a PWB may not produce sufficiently precise alignment to allow each connector to connect reliably with the corresponding connector in an array, such as in the chassis-based system described above. In such a case it may be helpful to use a single rigid part known as a connector frame to hold all of the connectors, and to maintain their alignment relative to each other and to a PWB. It may also be convenient to have the connector frame secured to the bottom surface of the PWB, providing a ground connection between the connector frame and a ground conductor on the bottom surface of the PWB.
[0007] When a connector frame is used with coaxial connectors, it may be necessary to provide ground connections also between the outer conductors of the connectors and ground conductors on the top surface of the PWB. Moreover, when the connectors will be carrying high-frequency signals, such as radio frequency (RF) or microwave signals, it may be necessary to have a continuous connection from the connector frame to one or more ground conductors on the top surface of the PWB, forming a transmission line, so that the characteristic impedance of the signal path will be uniform and to prevent reflection or radiation of the signal.
[0008] A connection between the connector frame and the top-layer ground conductors may be formed by bonding wires to the connector frame and to top-layer ground conductors near the edge of the PWB. A bond wire, however, generally follows a curved path through air between the bond pads it connects. This causes the corresponding part of the signal path to have a different, and generally high, characteristic impedance, and if the wire bonds are applied under manual control, the wire path and the characteristic impedance may suffer from poor repeatability. Moreover, wire-bonding machines may be designed to work with relatively small parts, and a PWB with a connector frame may be too large to fit into such a machine.
[0009] Another means of forming a ground connection between the connector frame and a top-layer ground involves applying a globule of conductive epoxy manually to a ground conductor near the edge of the PWB and to a nearby surface of the connector frame, so that the epoxy bridges the gap between the connector frame and the top-surface ground conductor on the PWB. This method is unsatisfactory, primarily because of the conflicting requirements of (i) applying a sufficient quantity of epoxy to ensure that the gap is bridged by the epoxy and that contact is made reliably with both the connector frame and the PWB, and (ii) applying a sufficiently small quantity of epoxy that it will not flow to other nearby conductors, thereby forming unwanted short circuits. These difficulties may be compounded by variations in gap width resulting from fabrication tolerances, and from the poor repeatability of a manual process.
[0010] Thus, there is a need for a system for providing connections between a conductive connector frame and one or more conductive areas on the top surface of a PWB.
SUMMARY
[0011] Embodiments of the present invention provide a repeatable ground connection between a connector frame and conductors on the surface of a PWB. One aspect of embodiments of the present invention allows a signal path to maintain a uniform characteristic impedance between coaxial connectors and PWB transmission lines, by providing continuous ground paths from a connector frame to ground conductors on the PWB. Exemplary embodiments of the invention accomplish this by providing contact surfaces on the connector frame and on the PWB, and conductive tabs which may be soldered or adhered to both the connector frame and the PWB, to provide conductive ground paths from one to the other.
[0012] In one embodiment, a system for forming a plurality of electrical connections to one or more conductive areas on a PWB comprises a connector frame attachable to a PWB, wherein the connector frame has at least one surface portion adjacent each of the conductive areas of the PWB, and each of the surface portions is electrically connectible to a conductive tab, to connect the surface portion of the connector frame to one of the conductive areas of the PWB. In one embodiment the system comprises flat tabs for connecting one or more of the surface portions of the connector frame to one or more of the conductive areas of the PWB.
[0013] In one embodiment, a method of forming a plurality of ground connections between conductive areas on a PWB and a connector frame for holding coaxial connectors includes providing the connector frame with at least one surface portion adjacent each of the conductive areas on the PWB; securing one or more conductive tabs to one or more of the surface portions; and securing one or more of the conductive tabs to one or more of the conductive areas.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] These and other features and advantages of the present invention will become appreciated as the same become better understood with reference to the specification, claims and appended drawings, wherein:
[0015] FIG. 1 is a fragmentary front perspective view of a portion of a grounding system provided according to an embodiment of the invention;
[0016] FIG. 2 is a rear perspective view of the grounding system of FIG. 1 ;
[0017] FIG. 3 is a rear perspective view of the grounding system of FIG. 1 according to another embodiment of the invention;
[0018] FIG. 4A is a fragmentary top plan view of a portion of the embodiment of FIG. 2 , showing an offset cutting plane used to generate FIG. 4B ;
[0019] FIG. 4B is a cross-sectional view of the embodiment of FIG. 2 taken along the offset cutting plane shown in FIG. 4A ;
[0020] FIG. 5A is a top view of the top conductive layer of a PWB according to an embodiment of the invention; and
[0021] FIG. 5B is a top view of the middle conductive layer of a PWB according to an embodiment of the invention.
DETAILED DESCRIPTION
[0022] The detailed description set forth below in connection with the appended drawings is intended as a description of the presently preferred embodiments of an identification system provided in accordance with the present invention and is not intended to represent the only forms in which the present invention may be constructed or utilized. The description sets forth the features of the present invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and structures may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention. As denoted elsewhere herein, like element numbers are intended to indicate like elements or features.
[0023] As used herein, the term “PWB” means any combination of one or more insulating, dielectric, or semiconductor layers with one or more complete or partial conducting layers, and includes without limitation polymer on metal, ceramic substrates, GaAs and GaN chips, and combinations in which the dielectric material is glass reinforced epoxy, a Teflon-based material, or alumina, and in which the conducting material contains copper or copper and other metals.
[0024] Referring to FIG. 1 and FIG. 2 , in the embodiment shown a connector frame 10 includes a plate portion 11 forming a PWB shelf 12 for supporting a PWB 14 , and also includes a wall portion 13 extending along one edge of the PWB 14 . The PWB 14 is secured to the PWB shelf 12 . Threaded holes 16 in the wall portion 13 accept coaxial connectors 17 with threaded bodies. In one embodiment, the threaded holes 16 may be through holes 0.035 inches in diameter, counterbored with a diameter of 0.148 inches to a depth of 0.167 inches, and the counterbored portion may be threaded with a 0.164-64 UNS-2B thread, to a minimum depth of 0.138 inches. The connector frame 10 may be fabricated from a single piece of metal or assembled from several pieces, and it may be formed of conductive materials other than metal, or of a combination of conductive and insulating materials.
[0025] In the embodiment shown in FIG. 2 , a relief cut 21 on each side of each threaded hole 16 forms a tab shelf 22 at the same height as the top surface of the top layer ground conductor 25 . On either side of each connector 17 , a ground tab 23 is secured to both the tab shelf 22 and to an adjacent area on the top layer ground conductor 25 using solder or conductive epoxy (element 26 of FIG. 4 ). Except where it may cross a relatively small gap 27 between the PWB 14 and the connector frame 10 , the ground tab 23 does not produce an air gap between the signal conductor and ground conductors. As a result this system provides a signal path with a more uniform and more repeatable characteristic impedance than a pair of bond wires.
[0026] For clarity of illustration, FIG. 2 shows the system with ground tabs 23 installed at one of the coaxial connectors 17 and not yet installed at another, so that the tab shelves 22 are visible at the latter location.
[0027] The invention is described herein in relation to an array of coaxial RF connectors 17 , but the invention is not limited to this application, and may be used in other types of connector assemblies, such as triaxial connectors or coaxial connectors intended for use at other frequencies.
[0028] In one embodiment, the center conductors 18 of the coaxial connectors 17 extend just above the top surface of the top layer signal trace 30 on the PWB 14 . The distance between the PWB shelf 12 and the centerline of any of the threaded holes 16 may preferably be chosen such that when the PWB 14 is installed on the PWB shelf 12 , the clearance between the top layer signal trace 30 on the PWB 14 and the center conductor 18 of the connector 17 is sufficiently large to allow the connector 17 to be installed in the threaded hole 16 , and also sufficiently small to allow a reliable connection between the center conductor 18 and the corresponding top layer signal trace 30 to be formed. For example, it may be preferable to have the clearance be sufficiently small that during a soldering or gluing operation molten solder or conductive epoxy (element 26 of FIG. 4 ) will bridge the gap between the center conductor 18 and the corresponding top layer signal trace 30 . In an exemplary embodiment the thickness of the conductive epoxy film (element 15 of FIG. 4 ) between the PWB shelf 12 and the PWB 14 may be 0.005 inches, the thickness of the PWB 14 may be 0.036 inches, the diameter of the coaxial connector center conductor 18 may be 0.012 inches, and the distance between the center line of the threaded hole 16 and the PWB shelf 12 may be 0.049 inches, resulting in a nominal clearance between the center conductor 18 and the top layer signal trace 30 of 0.002 inches.
[0029] The relief cuts 21 may be formed by any suitable method, in one embodiment as part of the process of machining the connector frame 10 using a milling machine under computer numerical control, also known as a CNC machine. In this case each of the relief cuts 21 may be formed using an end mill; the same end mill may also be used to machine other surfaces of the connector frame 10 . The width of the relief cut 21 in this case may be greater than or equal to the diameter of the end mill used for this operation. In embodiments of the present invention, the connector frame 10 may be made of a material having a coefficient of thermal expansion similar to that of the PWB 14 , such as an aluminum-silicon alloy containing 72% aluminum and 28% silicon.
[0030] The PWB 14 may be fabricated from conductive layers made of copper and dielectric layers made of a Teflon-based material such as CLTE sold by Arlon-MED of Rancho Cucamonga, Calif., which may have a glass weave imbedded in it. In another embodiment, similar material sold by Rogers Corporation, of Chandler, Ariz., may be used. The glass weave may control the coefficient of thermal expansion of the dielectric layers so that it is similar to that of the copper conductive layers.
[0031] In exemplary embodiments, after the PWB 14 has been secured to the connector frame 10 , connectors 17 with threaded bodies are installed in the connector frame 10 by threading them into the threaded holes 16 and tightening them to the torque specified by the manufacturer of the connectors 17 . The connectors 17 may in certain embodiments be SMPM connectors, with part number 18S103-500L5, sold by Rosenberger of North America, LLC, of Lancaster, Pa. In other embodiments they may be GPPO connectors, with part number B003-L33-02, sold by Corning Gilbert Incorporated of Glendale, Ariz. Similar or equivalent connectors may be available from other vendors including W. L. Gore & Associates, Incorporated, of Newark, Del., and DDi Corporation of Anaheim, Calif.
[0032] In one embodiment, the ground tabs 23 are oblong with a width of 0.025 inches, a length of 0.125 inches, and rounded ends with radii of curvature equal to half of the width. The relief cuts 21 may be slightly wider than the ground tabs 23 to permit the latter to fit into place easily. In such an embodiment the relief cuts 21 may have a width of 0.032 inches.
[0033] In another embodiment, shown in FIG. 3 , U-shaped ground tabs 23 ′ may be used in place of pairs of oblong ground tabs 23 of the kind illustrated in FIG. 2 . The two arms of each U-shaped ground tab 23 ′ may have widths of 0.025 inches, rounded ends with radii of curvature of 0.0125 inches, and a gap of 0.055 inches between the arms of the U. Each U-shaped ground tab 23 ′ may have an overall width of 0.105 inches and an overall length, measured in the direction parallel to the arms of the U, of 0.1531 inches.
[0034] The ground tabs 23 may, in an exemplary embodiment, be fabricated from a sheet of brass, 0.005 inches thick. In another embodiment, a sheet of another metal may be used. A metal having a coefficient of thermal expansion similar to that of the top conductive layer of the PWB 14 may minimize stresses that otherwise could result from differential thermal expansion or contraction with changes in temperature. It may be preferable to plate the ground tabs 23 with another metal or metals to provide a better bond during installation and to prevent galvanic corrosion. An etching process may be used to fabricate the ground tabs 23 . An etch-resistive film, in the shape that is to remain after etching, may be formed on both sides of a sheet of brass. After the formation of this film the sheet of brass may be etched from both sides. After etching, the sheet may contain a number of ground tabs 23 , each still connected to a supporting strip of the sheet by a narrow support finger of metal. In an exemplary embodiment, this etched sheet may then be plated with a layer of nickel 0.0001 to 0.0002 inches thick, and subsequently plated with a layer of gold 0.00001 to 0.00002 inches thick. Shearing the support fingers in such an embodiment releases the ground tabs 23 from the supporting strip, completing the process of fabricating the ground tabs 23 . In another embodiment, the ground tabs 23 may be punched from a sheet of metal, which may first have been plated with one or more other metals.
[0035] Referring to FIG. 4 , in one embodiment, the PWB 14 may be secured to the PWB shelf 12 using a conductive epoxy film 15 such as Ablestik ABLEFILM 561, a glass supported, modified epoxy adhesive film sold by Henkel Corporation, of Rocky Hill, Conn. The conductive epoxy film 15 may be applied to the PWB shelf 12 , the PWB 14 placed on the conductive epoxy film 15 , and the subassembly heated in an oven to cure the conductive epoxy film 15 . After the PWB 14 is secured to the connector frame 10 , a dab of conductive epoxy 26 may be applied to each tab shelf 22 , and to a point, on the top layer ground conductor 25 , adjacent to each tab shelf 22 . A ground tab 23 may then be placed across the gap 27 so that one end of the ground tab 23 is over the tab shelf 22 and the other end is over the top layer ground conductor 25 . In this embodiment the conductive epoxy 26 , both between the ground tab 23 and the tab shelf 22 , and between the ground tab 23 and the top layer ground conductor 25 , is sandwiched between closely spaced parallel surfaces, and prevented by its adhesion to these surfaces from flowing to other parts of the structure, where it could otherwise cause unwanted short circuits. The conductive epoxy 26 may be one that remains compliant after curing, to reduce the risk that differential thermal expansion of the parts joined by the conductive epoxy 26 may cause the conductive epoxy 26 to fracture. In one embodiment, the conductive epoxy 26 may be Ablestick 8175, which is sold by Henkel Corporation. In another embodiment, dabs of solder paste may be used in place of conductive epoxy 26 , and the subassembly may be subsequently heated in a reflow oven to form solder joints at the locations of the solder paste. The dabs of conductive epoxy 26 or of solder paste may, in an exemplary embodiment, be applied under computer control by a dispensing machine. In another embodiment the dabs may be applied manually.
[0036] The ground tabs 23 may be sufficiently small and of sufficiently low mass for handling with a pick-and-place machine and in one embodiment may be placed on the PWB 14 using such a machine. In another embodiment the tabs may be installed manually. In yet another embodiment a comb-shaped strip of sheet of metal may include multiple ground tabs and may be installed on the PWB 14 and the tab shelves 22 in one manual operation.
[0037] It may be possible to install the ground tabs 23 on the PWB 14 at the same time, and using the same equipment, as other components, improving the efficiency of the assembly process. For example, solder paste may be applied to the tab shelves 22 and to various points on the top surface conductors of the PWB 14 . The components may then be placed on the PWB 14 and the ground tabs 23 on the PWB 14 and on the tab shelves 22 in a subsequent step, and all of the solder joints formed simultaneously in a subsequent solder reflow step.
[0038] FIG. 5 shows an exemplary arrangement of the top and middle conductive layers for an embodiment in which the PWB 14 has three conductive layers. A transition from coaxial transmission line to a transmission line geometry known as “coplanar-over-ground” is formed at the edge of the PWB 14 . As used herein the term “coplanar over ground” delineates a geometry of conductors used for a microwave transmission line including a top layer signal trace 30 , a top layer ground conductor 25 , or a pair of such conductors, extending to both sides of the top layer signal trace 30 , and a bottom layer ground 32 ( FIG. 4 ). A second transition to another transmission line configuration may be formed near the first transition.
[0039] Referring to FIG. 5 , the second transition may for example be from coplanar-over-ground to stripline. In this case, the signal path may be routed from the top layer signal trace 30 to the middle layer signal trace 34 using a signal via 28 . The signal via 28 may be back-drilled through the bottom layer with a drill bit having a diameter slightly larger than the diameter of the signal via 28 , to a depth extending almost to the middle conductive layer, to remove the conductive material from the lower half of the signal via 28 , where it would otherwise contact, or be unacceptably close to, the bottom layer ground 32 and the PWB shelf 12 ( FIG. 4 ). A signal via pad 35 , an annular region of conductor, may surround, or partially surround, the signal via 28 . A cage of ground vias 29 may be used for mode suppression as illustrated in the exemplary embodiment of FIG. 5 to reduce loss in the structure. In an embodiment in which U-shaped ground tabs 23 ′ are employed ( FIG. 3 ), the top layer ground conductor 25 on the PWB 14 extends past the edge of the U-shaped ground tab 23 ′ at all edges of the U-shaped ground tab 23 ′ except at the edge of the PWB 14 . This ensures that the gap between the signal path and the nearest ground on the PWB 14 is determined everywhere by the edge of the top layer ground conductor 25 , and not by the placement of the U-shaped ground tab 23 ′ on the PWB 14 . In one embodiment the bottom layer ground 32 , shown in FIG. 4 , may be a solid conductive sheet except for holes at the locations of vias.
[0040] Adjustments to the dimensions of the conductors on the PWB 14 may be made to provide as uniform as possible a characteristic impedance along the signal path, and to minimize reflections and radiation along the path. These adjustments may be made using electromagnetic field simulation software such as Ansoft HFSS, sold by Ansys Incorporated, of Canonsburg, Pa. Using such software, a designer, in implementing the present invention, may define two ports in the system, one at the coaxial connector 17 , and one at a point on the PWB 14 . In an embodiment having a second transition from coplanar-over-ground to stripline, for example, the second port may be on the stripline transmission line. The designer may then use the simulation software to calculate the four complex S-parameters for this two port system, where the magnitudes of S 11 and S 22 indicate the return loss and the magnitudes of S 12 and S 21 indicate the insertion loss. If the insertion loss is larger than expected it may indicate that the signal path will radiate electromagnetic power, which may be undesirable. The designer may use the simulation software to display the impedance corresponding to S 11 or to S 22 on a Smith chart, on which the desired characteristic impedance is the center point, the upper half corresponds to impedances which are more inductive than the desired characteristic impedance, and the lower half corresponds to impedances which are more capacitive than the desired characteristic impedance.
[0041] The designer may then, in a process known as tuning, adjust conductor dimensions until the design meets its requirements for return loss and insertion loss, over the frequency range of interest. To eliminate excess capacitance, the designer may for example reduce the width of the top layer signal trace 30 , increase the gaps between the top layer signal trace 30 and the regions of the top layer ground conductor 25 on both sides of the signal trace, decrease the diameter of the signal via 28 , decrease the diameter of the signal via pad 35 , enlarge the cage of ground vias 29 , or increase the gap between the signal via pad 35 and the adjacent top layer ground conductor 25 . When enlarging the cage of ground vias 29 , the designer may need to observe the insertion loss, which may become unacceptable if the ground vias 29 are moved too far from the transitions. To eliminate excess inductance, the designer may adjust, for example, any of these same parameters in the opposite direction. In a subsequent step, the designer may if necessary further reduce the capacitance of the structure by narrowing the middle layer signal trace 34 along a portion of its length, forming an inductive section 36 , and then adjust the length and width of the inductive section 36 to further improve the return loss and the insertion loss of the signal path. Alternatively, the designer may, instead of narrowing, widen a portion of the middle layer signal trace 34 , thereby forming a capacitive section, and adjust the length and width of the capacitive section for improved performance.
[0042] When a system design employing the present invention has been adjusted for good performance over one range of frequencies, and it is desired to use the system over a different range of frequencies, it may be necessary to repeat the tuning process for the new frequency range.
[0043] The grounding system of the present invention is described above, and illustrated in FIG. 5 , in the context of a signal path having a first transition from coaxial transmission line to coplanar-over-ground, and a second transition from coplanar-over-ground to stripline. The invention, however, is not limited to such a pair of transitions. It may be used, for example, in a signal path without a second transition, or one in which the second transition is to microstrip transmission line. A transition from coplanar-over-ground to microstrip may be accomplished, for example, by flaring away the top layer ground, i.e., gradually increasing both the width of the top layer signal trace 30 , and the gaps between the top layer signal trace 30 and the ground conductor regions on both sides of the signal trace 30 , so as to keep the characteristic impedance constant, until the top layer ground conductor 25 is on both sides sufficiently distant from the signal trace 30 to have a negligible effect.
[0044] The method for connector grounding of the present invention is not limited to PWBs with three conductive layers, also known as three-layer boards, but may be employed with single-layer boards, two-layer boards, four layer boards, or PWBs with an arbitrary number of conductive layers. In each case the ground tab or tabs 23 may be installed so as to connect the connector frame 10 to a top layer ground conductor 25 . The connection of the connector frame 10 to ground conductors in other layers may be accomplished by one of, or a combination of: tabs connecting the connector frame 10 to a top layer ground conductor 25 , vias from a top layer ground conductor 25 to ground conductors in other layers, vias from the bottom layer ground 32 to ground conductors in other layers, vias connecting ground conductors in intermediate layers, and direct contact, or adhesion using a conductive epoxy film 15 , between the PWB shelf 12 and bottom layer ground 32 .
[0045] Although limited embodiments of a grounding system for an array of blind-mate coaxial connectors have been specifically described and illustrated herein, many modifications and variations will be apparent to those skilled in the art. Accordingly, it is to be understood that the grounding system constructed according to principles of this invention may be embodied other than as specifically described herein. The invention is also defined in the following claims. | 4y
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of surfboards. More specifically, the invention comprises a surfboard with vents that transfer air from the deck to the bottom, where a portion of the air becomes entrained in the water flow and creates an air-film beneath the board.
2. Description of the Related Art
Surfboards were invented by ancient Polynesians. They were originally carved from straight sections of tree trunk and were typically 3-4 meters (10-15 feet) in length and weighed as much as 70 kg (150 pounds). The sport of surfing expanded greatly in the years following World War II. The expansion of the sport was propelled in part by the availability of new materials for constructing surfboards. The widespread availability of fiberglass was a significant factor.
Modern surfboards are typically made by bonding a high-strength “skin” material to a low density/low strength “core” material. The core material is often polyurethane or polystyrene foam, but may also be natural materials such as balsa wood. The skin is made by covering the core with a material such as woven fiberglass cloth. The woven cloth is bonded to itself and the core using polyester or epoxy resin.
FIG. 1 shows a plan and elevation view for a representative surfboard. Those skilled in the art will now that a virtually endless variety of surfboards are now in common use. Thus, the board shown in FIG. 1 is properly viewed as one example among many possibilities. However, all surfboards share some common characteristics and these have been labeled in FIG. 1 in order to benefit the reader's understanding.
The top of the surfboard is known as deck 12 . The forward portion is known as nose 14 , while the aft portion is known as tail 16 . The board's lateral boundaries are generally referred to as “rails” (left rail 18 and right 20 ). The board's downward facing surface is known as bottom 24 .
FIG. 1 is not labeled as “prior art” because the surfboard depicted includes the present invention (vents 26 ). Its other features are common to prior art boards, however, and thus it is still useful for discussing the background of the invention. It is common for modern surfboards to include one or more skegs 22 . These prevent lateral slipping and aid in turning the board. Other features may be included, such as an attachment point for a “leash” that is used to link the board to one of the surfer's ankles.
The board shown in FIG. 1 is known for being fairly agile, meaning that it can be quickly turned. It has a fairly broad beam and a relatively short length (in comparison to traditional “long boards”). When a rider is riding the board such as shown in FIG. 1 , only the aft portion will engage the water. How much of the board is in contact with the water depends on many factors. However, it is common for at least a substantial portion of the board's forward region to be free of the water.
The surface friction generated by the interaction of the board's bottom with the water is a significant factor in determining the speed the surfer is able to achieve. Surfboards are commonly smoothed and waxed in order to minimize the friction between the board's bottom and the water. However, smoothing and waxing will only increase the board's speed to a certain extent. It is desirable to further increase the board's speed by further reducing friction. The present invention provides such an enhancement.
BRIEF SUMMARY OF THE INVENTION
The present invention comprises one or more an air vents that pass from the deck of a surfboard through to its bottom. The vent may have a wide variety of shapes. The trailing boundary of the vent's lower portion is preferably inclined forward toward the surfboard's nose. The inclination serves to prevent water flowing upward. Instead, air is entrained by the water flowing across the vent's bottom exit and pulled downward. A portion of the entrained air flows rearward out of the bottom exit along the surfboard's bottom. This entrained air forms an air film between the board's bottom and the surrounding water, thereby reducing friction.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a plan and elevation view depicting a common type of surfboard with the addition of the present invention.
FIG. 2 is a detailed section view, showing a vent made according to the present invention.
FIG. 3 is a detailed elevation view, showing the operation of the present invention.
FIG. 4 is a detailed elevation view, showing how the orientation of the present invention is significant to its operation.
FIG. 5 depicts four different orientations for the present invention.
FIG. 6 is a detailed perspective view, showing one method of manufacturing the present invention.
FIG. 7 is a detailed perspective view, showing one method of manufacturing the present invention.
FIG. 8 is a detailed perspective view, showing one method of manufacturing the present invention.
FIG. 9 is a plan view, showing three different embodiments of the present invention.
FIG. 10 is a detailed elevation view, showing an alternate embodiment for the present invention.
REFERENCE NUMERALS IN THE DRAWINGS
REFERENCE NUMERALS IN THE DRAWINGS
10
surfboard
12
deck
14
nose
16
tail
18
left rail
20
right rail
22
skeg
24
bottom
26
vent
28
central axis
30
core
32
deck skin
34
bottom skin
36
wall skin
38
air/water boundary
40
entrained air
42
air film
44
water flow
46
lifted flow
48
cavity
50
pipe
52
resin fillet
54
bottom exit
56
top exit
58
leading boundary
60
trailing boundary
DETAILED DESCRIPTION OF THE INVENTION
The present invention involves one or more vents passing through a surfboard from top to bottom. The vents are used to create an air film beneath the trailing portion of the board as it moves through the water. A broad air film is preferably created. In order to create such a film, an array of two or more vents are included in a suitable pattern. The top view of FIG. 1 shows such an array. Six vents 26 are provided in this embodiment.
FIG. 2 depicts a sectional elevation view of one of the vents 26 shown in FIG. 1 . Vent 26 passes vertically through the surfboard. The board in this example includes a typical construction used for modern surfboards. Core 30 defines the overall shape of the board. Deck skin 32 is made by laying one or more layers of woven cloth (fiberglass, KEVLAR, or other more exotic materials such as carbon fiber) over the upper surface of the core and bonding it using a liquid resin material that transitions to a strong solid. Examples of the resin include polyester and epoxy.
The reinforcing cloth and bonding resin surround and bond to core 30 on all sides. Bottom skin 34 is the portion of the bonded reinforcing cloth that lies over the bottom of the board. In this example, vent 26 is simply an inclined cylindrical cavity having central axis 28 . The cylindrical cavity intersects the deck at top exit 56 . It intersects the bottom at bottom exit 54 .
It is undesirable to expose any portion of the core material since it has little toughness or abrasion resistance. Thus, it is preferable to provide wall skin 36 around the perimeter of vent 26 . Wall skin 36 may be formed using a variety of techniques. It is preferable for wall skin 36 to be bonded to deck skin 32 and bottom skin 34 .
The reader will observe that the nose of the surfboard lies off to the right of the cross section, and the tail lies off to the left. Vent 26 is therefore inclined so that its upper portion lies close to the nose and its lower portion lies closer to the tail. This geometry is significant to the operation of the vent.
FIG. 3 shows the same geometry as the surfboard is moved rapidly through the water. The bottom exit region of vent 26 includes leading boundary 58 and trailing boundary 60 . Water flow 44 slides rapidly along bottom 24 in the direction indicated by the arrow. As the water moves aft past leading boundary 58 , air/water boundary 38 moves up into vent 26 . This phenomenon is well known in the field of fluid mechanics and is commonly referrer to as “hydraulic jump.”
As the moving water approaches trailing boundary 60 , however, a different phenomenon occurs. The inclined surface of trailing boundary 60 causes some air to be entrained and pulled beneath the board (entrained air 40 ). Once this entrained air is aft of the vent, it cannot easily escape to the surface and must instead travel along the bottom of the board. Air film 42 is thereby created. As is well known to those skilled in the art, the creation of such an air film substantially reduces the sliding friction between the bottom of the surfboard and the water.
The vent shown in FIG. 3 is a simple cylindrical bore drilled through the surfboard (having a diameter “D”). This simple shape produces the desired effect. It is readily apparent that other shapes could produce the desired effect as well. The important element is the inclination of trailing boundary 60 . The inclination of leading boundary 58 is relatively unimportant. This portion may simply be vertical, or may even be inclined in the opposite direction as trailing boundary 60 .
FIG. 4 provides air extreme illustration of the importance of properly inclining trailing boundary 60 . In the example of FIG. 4 , trailing boundary 60 is inclined so that its lower portion is closest to the nose and its upper portion is closest to the tail. Water flow 44 slides along the bottom of the board as for the example of FIG. 3 , but no air is entrained. Instead, lifted flow 46 is “scooped” up through vent 26 and propelled onto deck 12 . This configuration obviously does not produce the desired effect. It is important to realize that the example of FIG. 4 is not an embodiment of the present invention. It is not really prior art, however, since the inventor is not aware of a board having this precise configuration (though some prior art boards have incorporated scoops intended to spray water upwards). FIG. 4 merely serves to illustrate—by way of an extreme example—how the inclination of trailing boundary 60 is important to the operation of the present invention.
FIG. 5 shows several examples of vents formed by creating a simple cylindrical cavity having a central axis 28 . In FIG. 5(A) , central axis 28 is perfectly perpendicular to deck 12 . In FIG. 5(B) , central axis 28 is tilted forward with respect to deck 12 . The angle between the central axis and the deck in this example is 60 degrees. FIG. 5(C) shows an example where the angle is 45 degrees, and FIG. 5(D) shows an example where the angle of tilt is 30 degrees. The example of FIG. 5(A) entrains some air but is not very effective. The other examples work better, with the preferred embodiment being about 45 to 60 degrees.
Although the invention is not limited to any particular construction technique, the reader may wish to know some information regarding the construction of suitable vents in a typical surfboard. FIGS. 6-8 provide illustrations of one suitable process.
FIG. 6 shows a small section of core 30 used to create a surfboard. Only the section immediately surrounding the location of a vent is shown. Cavity 48 is made through core 30 . The cavity may be drilled by passing a drill bit along central axis 28 . Alternatively, the cavity may be cast into the core material at the time the core material itself is cast.
As stated previously, it is preferable to provide a wall skin in the cavity. In FIG. 7 , pipe 50 has been added to the cavity by gluing it in position. The pipe may be a PVC extrusion, a fiberglass composite, or even a piece of metal tube. Once the pipe is in position, deck skin 32 and bottom skin 34 are added. The deck and bottom skins are preferably bonded to the pipe. Resin fillet 52 may be formed when the resin is used to soak and bond the woven reinforcing cloth used to make the deck and bottom skins.
In the assembly as shown, a portion of pipe 50 sticks up beyond the deck and a second portion (not shown) protrudes down below the bottom. The protruding portions are cut off and the boundaries are sanded smooth. FIG. 8 shows the result. Pipe 50 is sanded smooth with deck skin 32 and bottom skin 34 . The resulting vent 26 is thereby bounded within a “wall skin” (the pipe). Additional adhesive and/or filler material may be used to dress the joints.
In order to create the desired air film beneath the aft portion of the surfboard, it may be necessary to provide two or more vents in a pattern. FIG. 9 provides a plan view for three different embodiments. The upper surfboard 10 has a single large vent 26 . The middle board has an array of three staggered vents 26 . The bottom board has a linear array of four vents 26 . The invention is by no means limited to any particular number or configuration of vents. Some embodiments may have ten or more vents in various locations.
In the preceding examples a simple cylindrical cavity is used for the vent. This is a very easy shape to create, since it involves simply drilling a hole through the board at a desired angle. It may be desirable in some instances, however, to employ a more complex shape for the vent. FIG. 10 shows an additional embodiment in which vent 26 has a non-uniform cross section as it proceeds from top to bottom. The reader will observe that leading boundary 58 is simply a vertical wall. Trailing boundary 60 is suitably inclined, but only in proximity to the portion of the vent that actually contacts the water.
This embodiment pulls in the entrained air and creates air film 42 . However, it uses a complex blended shape for the vent. In studying this shape, the reader will note that the inclination of the trailing boundary is the feature that makes the device produce the desired result. The shape of the other portions of the vent are not critical, as long as they permit enough air to pass.
The preceding description contains significant detail regarding the novel aspects of the present invention. It is should not be construed, however, as limiting the scope of the invention but rather as providing illustrations of the preferred embodiments of the invention. Thus, the scope of the invention should be fixed by the claims presented, rather than by the examples given. | 4y
|
RELATED APPLICATIONS
[0001] The present application is a continuation-in-part of and claims priority to Provisional Application U.S. Ser. No. 60/005,882, filed Oct. 26, 1995, the entire disclosure of which is incorporated herein by reference.
FIELD OF INVENTION
[0002] The present invention provides for new use for creatine compounds (creatine analogues and compounds which modulate one or more of the structural or functional components of the creatine kinase/creatine phosphate system) as therapeutic agents. More particularly, the present invention provides a method of treating or preventing certain metabolic disorders of human and animal metabolism relating to aberrant body weight regulation as manifested in obesity and it's related disorders.
BACKGROUND OF THE INVENTION
[0003] There are several metabolic diseases of human and animal metabolism, eg., obesity and severe weight loss that relate to energy imbalance—where caloric intake versus energy expenditure—is imbalanced. Obesity, which can be defined as a body weight more than 20% in excess of the ideal body weight, is a major health problem in Western affluent societies. It is associated with an increased risk for cardiovascular disease, hypertension, diabetes, hyperlipidaemia and an increased mortality rate. Obesity is the result of a positive energy balance, as a consequence of an increased ratio of caloric intake to energy expenditure. The molecular factors regulating food intake and body weight balance are incompletely understood. Five single-gene mutations resulting in obesity have been described in mice, implicating genetic factors in the etiology of obesity. (Friedman, j. m., and Leibel, r. l. Cell 69: 217-220 (1990)). In the ob mouse a single gene mutation, obese, results in profound obesity, which is accompanied by diabetes (Friedman, J. M., et. al. Genomics 11: 1054-1062 (1991)). Cross-circulation experiments have suggested that the ob mice are deficient of a blood-borne factor regulating nutrient intake and energy metabolism (Coleman, D. L. Diabetologia 14: 141-148 (1978)). Using positional cloning technologies, the mouse ob gene, and subsequently its human homologue, have been recently cloned (Zhang, Y., et. al., Nature 372: 425-432 (1994)). Daily intraperitoneal injections of either mouse or human recombinant OB protein reduced the body weight of obese mice ob/ob by 30% after 2 weeks of injection. The protein reduced food intake and increased energy expenditure in the ob/ob mice (Halaas et. al., Science 269: 543-546 (1995)).
[0004] Cachexia on the other hand is characterized by severe weight loss and imbalanced energy expenditure, examples being patients with cancer or HIV infections.
[0005] The creatine kinase/creatine phosphate system is an energy generating system operative predominantly in the brain, muscle, heart, retina, adipose tissue and the kidney (Walliman et. al., Biochem. J. 281: 21-40 (1992)). The components of the system include the enzyme creatine kinase (CK), the substrates creatine (Cr), creatine phosphate (CrP), ATP,ADP, and the creatine trasporter. The enzyme catalyses reversibly the transfer of a phosphoryl group from CrP to ADP to generate ATP which is the main source of energy in the cell. This system represents the most efficient way to generate energy upon rapid demand. The creatine kinase isoenzymes are found to be localized at sites where rapid rate of ATP replenishment is needed such as around ion channels and ATPase pumps. Some of the functions associated with this system include efficient regeneration of energy in the form of ATP in cells with fluctuating and high energy demand, energy transport to different parts of the cell, phosphoryl transfer activity, ion transport regulation, and involvement in signal transduction pathways.
[0006] The substrate Cr is a compound which is naturally occurring and is found in mammalian brain, skeletal muscle, retina, adipose tissue and the heart. It's phosphorylated form CrP is also found in the same organs and is the product of the CK reaction. Both compounds can be easily synthesized and are believed to be non toxic to man. A series of creatine analogues have also been synthesized and used as probes to study the active site of the enzyme. Kaddurah-Daouk et al. (WO 92/08456 published May 29, 1992 and WO 90/09192, published Aug. 23, 1990; U.S. Pat. Nos. 5,321,030; and 5,324,731) described methods for inhibiting growth, transformation, or metastasis of mammalian cells using related compounds. Examples of such compounds include cyclocreatine, homocyclocreatine and beta guanidino propionic acid. These same inventors have also demonstrated the efficacy of such compounds for combating viral infections (U.S. Pat. No. 5,321,030). Elgebaly in U.S. Pat. No. 5,091,404 discloses the use of cyclocreatine for restoring functionality in muscle tissue. Cohn in PCT publication No WO94/16687 describes a method for inhibiting the growth of several tumors using creatine and related compounds.
[0007] It is an object of the present invention to provide methods for treatment of metabolic diseases that relate to deregulated body weight by administering to an afflicted individual an amount of a compound or compounds which modulate one or more of the structural or functional components of the creatine kinase/creatine phosphate system sufficient to prevent, reduce or ameliorate the symptoms of the disease. These compounds are collectively referred to as “creatine compounds.”
SUMMARY OF THE INVENTION
[0008] The present invention provides a method of treating or preventing a metabolic disorder which relates to an imbalance in the regulation of body weight. Examples would be obesity and its related disorders (such as cardiovascular disease, hypertension, diabetes, hyperlipidaemia, osteoporosis and osteoarthritis) and severe weight loss. It consists of administering to a patient susceptible to or experiencing said disorder a creatine compound (creatine analogues and compounds which modulate one or more of the structural or functional components of the creatine kinase/creatine phosphate system) as therapeutic in the form of a pharmacologically acceptable salt as the pharmaceutical agent effective to treat or prevent the disease or condition.
[0009] Obesity is the result of a positive energy balance, as a consequence of an increased ratio of caloric intake to energy expenditure while severe weight loss is a result of a negative energy balance. The creatine kinase system is known to be involved in energy metabolism and it's substrates creatine phosphate, and ATP are among the highest energy compounds in the cell. It is now possible to modify this system and come up with compounds that can change energy balance and subsequently treat, prevent or ameliorate the diseases mentioned. One can increase energy state or decrease it by using substrates or inhibitors for the enzyme creatine kinase, or modulators of the enzyme system (compounds which modify any of its components) such as the creatine transporter.
[0010] The present invention also provides compositions containing creatine compounds in combination with a pharmaceutically acceptable carrier. Also, they could be used in combination with effective amounts of standard chemotherapeutic agents which act on regulating body weight and others to prophylactically and/or therapeutically treat a subject with a disease related to body weight control.
[0011] Packaged drugs for treating subjects having energy imbalance resulting in weight loss or gain are also the subject of the present invention. The packaged drugs include a container holding the creatine compound, in combination with a pharmaceutically acceptable carrier, along with instructions for administering the same for the purpose of preventing, ameliorating, arresting or eliminating a disease related to glucose level regulation.
[0012] By treatment is meant the amelioration or total avoidance of the metabolic disorder as described herein. By prevention is meant the avoidance of a currently recognized disease state, as described herein, in a patient evidencing some or all of the metabolic disorders described above.
[0013] For all of these purposes, any convenient route of systemic administration is employed, e.g., orally, parenterally, intranasally or intrarectally. The above compositions may be administered in a sustained release formulation. By sustained release is meant a formulation in which the drug becomes biologically available to the patient at a measured rate over a prolonged period. Such compositions are well known in the art.
DETAILED DESCRIPTION OF THE INVENTION
[0014] The method of the present invention generally comprises administering to an individual afflicted with a disease or susceptible to a disease involving body weight regulation, an amount of a compound or compounds which modulate one or more of the structural or functional components of the creatine kinase/phosphocreatine system sufficient to prevent, reduce or ameliorate symptoms of the disease. Components of the system which can be modulated include the enzyme creatine kinase, the substrates creatine creatine phosphate, ADP, ATP, and the transporter of creatine. As used herein, the term “modulate” means to change, affect or interfere with the functioning of the components in the creatine kinase/creatine phosphate enzyme system.
[0015] The creatine kinase/creatine phosphate system is an energy generating system operative predominantly in the brain, muscle, heart, retina, adipose tissue and the kidney (Walliman et. al., Biochem. J. 281: 21-40 (1992)). The components of the system include the enzyme creatine kinase (CK), the substrates creatine (Cr), creatine phosphate (CrP), ATP,ADP, and the creatine trasporter. The enzyme catalyses reversibly the transfer of a phosphoryl group from CrP to ADP to generate ATP which is the main source of energy in the cell. This system represents the most efficient way to generate energy upon rapid demand. The creatine kinase isoenzymes are found to be localized at sites where rapid rate of ATP replenishment is needed such as around ion channels and ATPase pumps. Some of the functions associated with this system include efficient regeneration of energy in the form of ATP in cells with fluctuating and high energy demand, energy transport to different parts of the cell, phosphoryl transfer activity, ion transport regulation, and involvement in signal transduction pathways.
[0016] Brown and white adipose tissue both contain creatine kinase and the substrates creatine and creatine phosphate, with activity of the enzyme 50 times higher in brown tissue (Bertlet et al., Biochim Biophys. Acta 437:166-174 (1976)). Brown fat tissue is responsible for energy expenditure and heat generation through the process of non-shivering thermogenesis. It was suggested that creatine may be involved in co-promoting mitochondrial respiration for thermogenesis.
[0017] The substrate Cr is a compound which is naturally occurring and is found in mammalian brain, skeletal muscle, retina and the heart. It's phosphorylated form CrP is also found in the same organs and is the product of the CK reaction. Both compounds can be easily synthesized and are believed to be non toxic to man. A series of creatine analogues have also been synthesized and used as probes to study the active site of the enzyme. Kaddurah-Daouk et al. (WO 92/08456 published May 29, 1992 and WO 90/09192, published Aug. 23, 1990; U.S. Pat. Nos. 5,321,030; and 5,324,731) described methods for inhibiting growth, transformation, or metastasis of mammalian cells using related compounds. Examples of such compounds include cyclocreatine, homocyclocreatine and beta guanidino propionic acid. These same inventors have also demonstrated the efficacy of such compounds for combating viral infections (U.S. Pat. No. 5,321,030). Elgebaly in U.S. Pat. No. 5,091,404 discloses the use of cyclocreatine for restoring functionality in muscle tissue. Cohn in PCT publication No. WO94/16687 describes a method for inhibiting the growth of several tumors using creatine and related compounds.
[0018] The term “creatine compound” will be used herein to include creatine, and compounds which are structurally similar to it and analogues of creatine and creatine phosphate. The term “creatine compound” also includes compounds which “mimic” the activity of creatine, creatine phosphate, or creatine analogues i.e., compounds which modulate the creatine kinase system. The term “mimics” is intended to include compounds which may not be structurally similar to creatine but mimic the therapeutic activity of the creatine analogues or structurally similar compounds. The term creatine compounds will also include inhibitors of creatine kinase, ie. compounds which inhibit the activity of the enzyme creatine kinase, molecules that inhibit the creatine transporter or molecules that inhibit the binding of the enzyme to other structural proteins or enzymes or lipids. The term “modulators” of the creatine kinase system” are compounds which modulate the activity of the enzyme, or the activity of the transporter of creatine, or the ability of the enzyme to associate with other cellular components. These could be substrates for the enzyme and they would have the ability to build in their phosphorylated state intracellularly. These types of molecules are also included in our term creatine compounds. The term creatine “analogue” is intended to include compounds which are structurally similar to creatine, compounds which are art-recognized as being analogues of creatine, and/or compounds which share the same function as creatine.
[0019] Creatine (α also known as N-(aminoiminomethyl)-N-methyl glycine; methylglycosamine or N-methyl-guanidino acetic acid is a well-known substance. (see the Merck Index, Eleventh Edition No. 2570 , 1989). Creatine is phosphorylated chemically or enzymatically to creatine kinase to generate creatine phosphate, which is also well known (see The Merck Index, No.7315). Both creatine and creatine phosphate (phosphocreatine) can be extracted from animals or tissue or synthesized chemically. Both are commercially available.
[0020] Cyclocreatine is an essentially planer cyclic analogue of creatine. Although cyclocreatine is structurally similar to creatine, the two compounds are distinguishable both kinetically and thermodynamically. Cyclocreatine is phosphorylated efficiently by the enzyme creatine kinase in the forward reaction, both in vitro and in vivo. Rowley, G. L., J.AM. Chem.Soc. 93:5542-5551 (1971); McLaughlin, A. C. et. al. J. Biol. Chem. 247, 4382-4388 (1972). It represents a class of substrate analogues of creatine kinase and which are believed to be active.
[0021] Examples of substances (creatine analogues) known or believed to modify the creatine kinase/creatine phosphate system are listed in Tables 1 and 2.
TABLE 1 CREATIVE ANALOGS
[0022] [0022] TABLE 2 CREATINE PHOSPHATE ANALOGS
[0023] Most of these compounds have been previously synthesized for other purposes (Rowley et al., J.Am.Chem.Soc., 93: 5542-5551, (1971); Mclaughlin et. al., J.Biol.Chem., 247: 4382-4388 (1972) Nguyen, A. C. K., “Synthesis and enzyme studies using creatine analogues”, Thesis, Dept of Pharmaceutical Chemistry, Univ. Calif, San Francisco, 1983; Lowe et al., J. Biol. Chem., 225:3944-3951(1980); Roberts et. al., J. Biol. Chem., 260:13502-13508 (1995) Roberts et. Al., Arch. biochem. Biophy., 220:563-571, 1983, and Griffiths et. Al., J.Biol. Chem., 251: 2049-2054 (1976). The contents of all of the forementioned references are expressly incorporated by reference. Further to the forementioned references, Kaddurah-Daouk et. al., (WO 92/08456; WO 90/09192; U.S. Pat. No. 5,324,731; U.S. Pat. No. 5,321,030) also provide citations for the synthesis of a plurality of creatine analogues. The contents of all the aforementioned references and patents are incorporated herein by reference.
[0024] It will be possible to modify the substances described below to produce analogues which have enhanced characteristics, such as greater specificity for the enzyme, enhanced solubility or stability, enhanced cellular uptake, or better biding activity. Salts of products may be exchanged to other salts using standard protocols.
[0025] Bisubstrate analogues of creatine kinase and non hydrolyizable substrate analogues of creatine phosphate (non transferable moieties which mimic the N phosphoryl group of creatine phosphate) can be designed readily and would be examples of creatine kinase modulators. Creatine phosphate compounds can be synthesized chemically or enzymatically. The chemical synthesis is well known. Annesley, T. M., Walker, J. B., Biochem.Biophys.Res. Commun., 74: 185-190 (1977); Cramer, F., Scheiffele, E., VOLLMAR, A., Chem.Ber., 95:1670-1682 (1962).
[0026] Creatine compounds which are particularly useful in this invention include those encompassed by the following general formula:
[0027] and pharmaceutically acceptable salts thereof, wherein:
[0028] a) Y is selected from the group consisting of: —CO 2 H—NHOH, —NO 2 , —SO 3 H, —C(═O)NHSO 2 J and —P(═O)(OH)(OJ), wherein J is selected from the group consisting of: hydrogen, C 1 -C 6 straight chain alkyl, C 3 -C 6 branched alkyl, C 2 -C 6 alkenyl, C 3 -C 6 branched alkenyl, and aryl;
[0029] b) A is selected from the group consisting of: C, CH, C 1 -C 5 alkyl, C 2 -C 5 alkenyl, C 2 -C 5 alkynyl, and C 1 -C 5 alkoyl chain, each having 0-2 substituents which are selected independently from the group consisting of:
[0030] 1) K, where K is selected from the group consisting of: C 1 -C 6 straight alkyl, C 2 -C 6 straight alkenyl, C 1 -C 6 straight alkoyl, C 3 -C 6 branched alkyl, C 3 -C 6 branched alkenyl, and C 4 -C 6 branched alkoyl, K having 0-2 substituents independently selected from the group consisting of rromo, chloro, epoxy and acetoxy;
[0031] 2) an aryl group selected from the group consisting of: a 1-2 ring carbocycle and a 1-2 ring heterocycle, wherein the aryl group contains 0-2 substituents independently selected from the group consisting of: —CH 2 L and —COCH 2 L where L is independently selected from the group consisting of: bromo, chloro, epoxy and acetoxy; and
[0032] 3) —NH—M, wherein M is selected from the group consisting of: hydrogen, C 1 -C 4 alkyl, C 2 -C 4 alkenyl, C 1 -C 4 alkoyl, C 3 -C 4 branched alkyl, C 3 -C 4 branched alkenyl, and C 4 branched alkoyl;
[0033] c) X is selected from the group consisting of NR 1 , CHR 1 , CR 1 , O and S, wherein R 1 is selected from the group consisting of:
[0034] 1) hydrogen;
[0035] 2) K where K is selected from the group consisting of: C 1 -C 6 straight alkyl, C 2 -C 6 straight alkenyl, C 1 -C 6 straight alkoyl, C 3 -C 6 branched alkyl, C 3 -C 6 branched alkenyl, and C 4 -C 6 branched alkoyl, K having O-2 substituents independently selected from the group consisting of: bromo, chloro, epoxy and acetoxy;
[0036] 3) an aryl group selected from the group consisting of a 1-2 ring carbocycle and a 1-2 ring heterocycle, wherein the aryl group contains 0-2 substituents independently selected from the group consisting of: —CH 2 L and —COCH 2 L where L is independently selected from the group consisting of: bromo, chloro, epoxy and acetoxy;
[0037] 4) a C 5 -C 9 a-amino-w-methyl-w-adenosylcarboxylic acid attached via the w-methyl carbon;
[0038] 5) 2 C 5 -C 9 a-arnino-w-aza-w-methyl-w-adenosylcarboxylic acid attached via the w-methyl carbon; and
[0039] 6) a C 5 -C 9 a-amino-w-thia-w-methyl-w-adenosylcarboxylic acid attached via the w-methyl carbon;
[0040] d) Z 1 and Z 2 are chosen independently from the group consisting of: ═O, —NHR 2 , —CH 2 R 2 , —NR 2 OH; wherein Z 1 and Z 2 may not both be ═O and wherein R 2 is selected from the group consisting of:
[0041] 1) hydrogen;
[0042] 2) K, where K is selected from the group consisting of: C 1 -C 6 straight alkyl; C 2 -C 6 straight alkenyl, C 1 -C 6 straight alkoyl, C 3 -C 6 branched alkyl, C 3 -C 6 branched alkenyl, and C 4 -C 6 branched alkoyl, K having 0-2 substituents independently selected from the group consisting of: bromo, chloro, epoxy and acetoxy;
[0043] 3) an aryl group selected from the group consisting of a 1-2 ring carbocycle and a 1-2 ring heterocycle, wherein the aryl group contains 0-2 substituents independently selected from the group consisting of: —CH 2 L and —COCH 2 L where L is independently selected from the group consisting of: bromo, chloro, epoxy and acetoxy;
[0044] 4) 2 C 4 -C 8 a-amino-carboxylic acid attached via the w-carbon;
[0045] 5) B, wherein B is selected from the group consisting of: —CO 2 H—NHOH, —SO 3 H, —NO 2 , OP(═O)(OH)(OJ) and —P(═O)(OH)(OJ), wherein J is selected from the group consisting of: hydrogen, C 1 -C 6 straight alkyl, C 3 -C 6 branched alkyl, C 2 -C 6 alkenyl, C 3 -C 6 branched alkenyl, and aryl, wherein B is optionally connected to the nitrogen via a linker selected from the group consisting of: C 1 -C 2 alkyl, C 2 alkenyl, and C 1 -C 2 alkoyl;
[0046] 6) —D—E, wherein D is selected from the group consisting of: C 1 -C 3 straight alkyl, C 3 branched alkyl, C 2 -C 3 straight alkenyl, C 3 branched alkenyl, C 1 -C 3 straight alkoyl, aryl and aroyl; and E is selected from the group consisting of: —(PO 3 ) n NMP, where n is 0-2 and NMP is ribonucleotide monophosphate connected via the 5′-phosphate, 3′-phosphate or the aromatic ring of the base; —[P(═O)(OCH 3 )(O)] m —Q, where m is 0-3 and Q is a ribonucleoside connected via the ribose or the aromatic ring of the base; —[P(═O)(OH)(CH 2 )] m —Q, where m is 0-3 and Q is a ribonucleoside connected via the ribose or the aromatic ring of the base; and an aryl group containing 0-3 substituents chosen independently from the group consisting of: Cl, Br, epoxy, acetoxy, —OG, —C(═O)G, and —CO 2 G, where G is independently selected from the group consisting of: C 1 -C 6 straight alky, C 2 -C 6 straight alkenyl, C 1 -C 6 straight alkoyl, C 3 -C 6 branched alkyl C 3 -C 6 branched alkenyl, C 4 -C 6 branched alkoyl, wherein E may be attached to any point to D, and if D is alkyl or alkenyl, D may be connected at either or both ends by an amide linkage; and
[0047] 7) —E, wherein E is selected from the group consisting of —(PO 3 ) n NMP, where n is 0-2 and NMP is a ribonucleotide monophosphate connected via the 5 ′-phosphate, 3′-phosphate or the aromatic ring of the base; —[P(═O)(OCH 3 )(O)] m —Q, where m is 0-3 and Q is a ribonucleoside connected via the ribose or the aromatic ring of the base; —[P(═O)(OH)(CH 2 )] m —Q, where m is 0-3 and Q is a ribonucleoside connected via the ribose or the aromatic ring of the base; and an aryl group containing 0-3 substituents chose independently from the group consisting of: Cl, Br, epoxy, acetoxy, —OG, —C(═O)G, and —CO 2 G, where G is independently selected from the group consisting of: C 1 -C 6 straight alkyl, C 2 -C 6 straight alkenyl, C 1 -C 6 straight alkoyl, C 3 -C 6 branched alkyl, C 3 -C 6 branched alkenyl, C 4 -C 6 branched alkoyl; and if E is aryl, E may be connected by an amide linkage;
[0048] e) if R 1 and at least one R 2 group are present, R 1 may be connected by a single or double bond to an R 2 group to form a cycle of 5 to 7 members;
[0049] f) if two R 2 groups are present, they may be connected by a single or a double bond to form a cycle of 4 to 7 members; and
[0050] g) if R 1 is present and Z 1 or Z 2 is selected from the group consisting of —NHR 2 , —CH 2 R 2 and —NR 2 OH, then R 1 may be connected by a single or double bond to the carbon or nitrogen of either Z 1 or Z 2 to form a cycle of 4 to 7 members.
[0051] Currently preferred compounds include cyclocreatine, creatine phosphate and those included in Tables 1 and 2 hereinabove.
[0052] The modes of administration for these compounds includes but is not limited to, oral, transdermal, or parenteral (eg., subcutaneous, intramuscular, intravenous, bolus or continuous infusion). The actual amount of drug needed will depend on factors such as the size, age and severity of disease in afflicted individual. Creatine has been given to athletes in the range of 2-8 gms/day to improve muscle function. Creatine phosphate was administered to patients with congestive heart failure also in the range of several gm/day and was very well tolerated. In experimental animal models of cancer or viral infections, were creatine compounds were shown to be active, amounts of 1 gm/kg/day were needed intraveniously or intraperitoneially. For this invention the creatine compound will be administered at dosages and for periods of time effective to reduce, ameliorate or eliminate the symptoms of the disease. Dose regimens may be adjusted for purposes of improving the therapeutic or prophylactic response of the compound. For example, several divided doses may be administered daily, one dose, or cyclic administration of the compounds to achieve the required therapeutic result.
[0053] The creatine compounds can be formulated according to the selected route of administration. The addition of gelatin, flavoring agents, or coating material can be used for oral applications. For solutions or emulsions in general, carriers may include aqueous or alcoholic/aqueous solutions, emulsions or suspensions, including saline and buffered media. Parenteral vehicles can include sodium chloride, potassium chloride among others. In addition intravenous vehicles can include fluid and nutrient replenishers, electrolyte replenishers among others.
[0054] Preservatives and other additives can also be present. For example, antimicrobial, antioxidant, chelating agents, and inert gases can be added (see, generally, Remington's Pharmaceutical Sciences, 16th Edition, Mack, 1980).
[0055] Equivalents
[0056] Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentati many equivalents to the specific embodiments of the invention described herein. Such equivalents a intended to be encompassed by the following claims. | 4y
|
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the priority benefit of French patent application number 12/52996, filed on Apr. 2, 2012, which is hereby incorporated by reference to the maximum extent allowable by law.
BACKGROUND
[0002] 1. Technical Field
[0003] The present disclosure relates to an energy harvesting device and to a method of forming such a device. In particular, the present disclosure relates to a device that converts thermal energy into electrical energy.
[0004] 2. Discussion of the Related Art
[0005] It has been proposed to use a bimetal plate, which changes shape under varying temperature conditions, in combination with a layer of piezoelectric material, to convert thermal energy into electrical energy.
[0006] FIG. 1 substantially reproduces FIG. 2 of U.S. patent application 2011/083714. As illustrated, a curved bimetal plate 100 comprises a support layer 102 , which changes shape in response to temperature variations. Plate 100 is shown having a first shape in the form of an arch, and for example changes shape to the form of an inverted arch when its temperature changes. A layer 104 of piezoelectric material is superposed over the support layer 102 . A piezoelectric material is one that has the property of generating a voltage difference between its main surfaces that varies depending on the stress applied to it. During a shape change of the curved metal plate 100 , a stress S occurs in the piezoelectric layer 104 , represented by arrows in FIG. 1 , resulting in variations in the voltage signals V − and V + present on the top and bottom surfaces of the piezoelectric layer 104 . The curved metal plate 100 is, for example, positioned in a cavity between hot and cold walls, such that its middle section contacts with the hot and cold walls when the curved plate 100 assumes its respective shapes. This results in a periodic shape change of the metal plate 100 , leading to the generation of a periodic voltage signal from which electrical energy can be extracted.
[0007] There is a need in the art for a simple and low cost energy harvester that operates based on the above principles and that can provide an efficient conversion of thermal to electrical energy in a range of different environments.
SUMMARY
[0008] It is an aim of embodiments to at least partially address one or more needs in the prior art.
[0009] According to one aspect, there is provided an energy harvester comprising: first and second sheets; and a plurality of walls, each wall being sandwiched between the first and second sheets and surrounding a cavity, wherein each cavity houses at least one curved plate adapted to change from a first shape to a second shape when its temperature reaches a first threshold and to return to the first shape when its temperature falls to a second threshold lower than said first threshold.
[0010] According to one embodiment, each of said cavities houses a single curved plate. According to another embodiment, each of said cavities houses a plurality of curved plates interconnected by fingers to form a matrix.
[0011] According to another embodiment, between said first and second sheets, there is a space separating a first of said walls from a second of said walls.
[0012] According to another embodiment, the energy harvester further comprises, within each of said cavities, a printed layer of piezoelectric material adapted to be deformed by said curved plate.
[0013] According to another embodiment, said piezoelectric layer is printed onto an inner surface of each cavity on a surface of said first sheet.
[0014] According to another embodiment, said piezoelectric layer is printed on a surface of each curved plate.
[0015] According to another embodiment, said inner walls are arranged in at least one column and in at least one row.
[0016] According to another embodiment, each of said curved plates comprises a layer of a first metal superposed by a layer of a second metal, the first and second metals having different coefficients of expansion.
[0017] According to another embodiment, each of said curved plates is formed of a shape-memory material.
[0018] According to a further aspect, there is provided a method of manufacturing an energy harvester comprising: forming a plurality of walls on a first sheet of material, each wall defining an opening which it surrounds; placing at least one curved plate into each of said openings, each curved plate being adapted to change from a first shape to a second shape when its temperature reaches a first threshold and to return to the first shape when its temperature falls to a second threshold lower than said first threshold; and sandwiching each of said walls between said first sheet and a second sheet of material.
[0019] According to one embodiment, the method comprises placing a matrix of curved plates into each of said openings.
[0020] According to another embodiment, the method further comprises printing a layer of piezoelectric material on either: each of said curved plates; or each of a plurality of zones on the surface of said first sheet, each opening being aligned over one of said zones.
[0021] According to another embodiment, the method further comprises printing, on said first sheet, interconnecting tracks comprising a plurality of electrodes adapted to make contact with each of said piezoelectric layers.
[0022] According to another embodiment, the material forming each of said first and second sheets is a plastic or insulated metal having a thickness of between 0.5 mm and 5 mm.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The foregoing and other purposes, features, aspects and advantages will become apparent from the following detailed description of embodiments, given by way of illustration and not limitation with reference to the accompanying drawings, in which:
[0024] FIG. 1 (described above) illustrates a curved metal plate in order to demonstrate a technique for thermal energy harvesting;
[0025] FIG. 2 is a cross-section view illustrating part of a thermal energy harvester according to an example embodiment;
[0026] FIG. 3 is a cross-section, taken in a horizontal plane, of the energy harvester of FIG. 2 according to an example embodiment;
[0027] FIGS. 4A to 4E are perspective views of an energy harvester at various stages during its manufacture according to an example embodiment;
[0028] FIG. 5 is a cross-section view illustrating part of a thermal energy harvester according to an alternative embodiment; and
[0029] FIG. 6 is a perspective view illustrating a matrix of curved plates according to an example embodiment.
[0030] It should be noted that the structures illustrated in the various figures are not drawn to scale, the thicknesses of certain layers in particular being shown to be disproportionately large to aid representation.
[0031] Furthermore, throughout the following description, relative orientations such as “top surface”, “bottom surface”, “upper” and “lower” are assumed to apply when the corresponding structure is orientated as shown in the drawings.
DETAILED DESCRIPTION
[0032] FIG. 2 is a cross-section view illustrating a portion of an energy harvester 200 according to an example embodiment. Two curved plates labelled 202 are positioned in corresponding cavities 206 , 208 of the energy harvester 200 . For example, each of these plates 202 corresponds to the curved bimetal plate 100 of FIG. 1 described above, except that it does not comprise the layer 104 of piezoelectric material superposed over the support layer 102 . Instead, a top wall of each cavity 206 , 208 is formed by a corresponding layer of piezoelectric material 210 .
[0033] The curved plates 202 are, for example, bimetal plates, formed of a layer of a first metal superposed by a layer of a second metal, the first and second metals having different coefficients of expansion. For example, the metal of each layer is one of TiN, aluminium, copper, tungsten, FeNi and an alloy of any of these metals. Alternatively, one or both layers could be formed of non-metals.
[0034] For example, the width and length of the curved plates are in the range of 1 μm to 10 mm. A method of forming curved plates having relatively small dimensions is for example discussed in more detail in co-pending patent application entitled “Curved plate and method of forming the same” filed on the same day as the present patent application and having the same inventors (law firm reference S1022.71770US00) which is hereby incorporated by reference in its entirety.
[0035] In some embodiments, the curved plates 202 are formed such that their change of shape in response to temperature variations is progressive, for example between the two shapes of the plates 202 illustrated in cavities 206 and 208 of FIG. 2 .
[0036] In alternative embodiments, the curved plates 202 are bi-stable, such that they flip rapidly from one shape to another when heated to a first temperature threshold, and back to their original shape when cooled to a second temperature threshold, lower than the first temperature threshold. For example, the curved plates 202 may comprise, as one of its layers, a shape-memory material, for example a nickel and titanium alloy. Such a material for example comprises two crystal phases, and is capable of having two stable shapes. Alternatively, the curved plate 202 may have an inward force applied to its ends by one or more springs, resulting in such a bi-stable effect.
[0037] The structure of the energy harvester 200 for example comprises an upper sheet of material 214 and a lower sheet of material 216 . For example, the upper and lower sheets 214 , 216 are each formed of a plastic sheet or of an insulated metal sheet. The sheets 214 , 216 are for example flexible and each have a thickness of between 0.5 mm and 5 mm, depending on the size of the energy harvester 200 and the desired extent of flexibility.
[0038] On the left-hand side of the structure shown in FIG. 2 , a peripheral wall 218 , for example formed of gum, silicon, silicon dioxide, or porous-silicon, separates the sheets 214 and 216 . The peripheral wall 218 for example extends around the whole device close to the edges of the sheets 214 and 216 , as will be described in more detail below. For example, the separation between the inner surfaces of the upper and lower sheets 214 , 216 is in the range of 0.5 mm to 20 mm.
[0039] The piezoelectric layers 210 of each cavity 206 , 208 are positioned at regular intervals on the inner surface of the upper sheet 214 . An inner wall 220 , also for example formed of gum, silicon, silicon dioxide, or porous-silicon for example surrounds each cavity 206 , 208 , and contacts the respective piezoelectric layers 210 above, and contacts the top surface of the lower sheet 216 below.
[0040] The peripheral wall 218 , and the inner wall 220 corresponding to the left-hand cavity 206 in FIG. 2 , are separated by a distance d 1 , for example of between 1 and 20 mm. The inner walls 220 corresponding to neighbouring cavities 206 , 208 in FIG. 2 are separated by a distance d 2 also of, for example, between 1 and 20 mm.
[0041] As represented by dashed lines extending from the right-hand edge of the structure of FIG. 2 , the structure may continue beyond what is illustrated in FIG. 2 , with one or more further cavities containing further curved plates 202 .
[0042] FIG. 3 illustrates an example of a cross-section view of the energy harvester 200 , in a horizontal plane represented by a dashed line A-A in FIG. 2 , passing through the peripheral wall 218 and inner walls 220 .
[0043] In the example of FIG. 3 , the energy harvester 200 comprises 21 curved plates 202 , each housed in a corresponding cavity, and arranged in 3 rows and 7 columns. Of course, in alternative embodiments, the energy harvester could comprise any number of curved plates. In some embodiments, hundreds, thousands or even millions of curved plates may be provided, each housed in a corresponding cavity or grouped into cavities. In particular, in some embodiments, each cavity houses a single curved plate. In alternative embodiments described in more detail with reference to FIG. 6 , each cavity houses a plurality of curved plates formed in a matrix.
[0044] An advantage of housing the curved plates in cavities, each cavity being surrounded by an inner wall 220 , is that the structure may be relatively flexible. Furthermore, an advantage of arranging the inner walls 220 in rows and columns is that this adds to the flexibility of the structure. In alternative embodiments, rather than being arranged in rows and columns, the inner walls 220 could be arranged in different patterns.
[0045] In plan view, the energy harvester 200 is for example rectangular in shape, and the peripheral wall 218 thus extends in a rectangle around the edge of the device. Furthermore, each of the inner walls 220 also for example extends around the corresponding cavity in the form of a rectangle, the rectangle being square in the example of FIG. 3 .
[0046] Such a rectangular shape of the inner walls 220 is well adapted to rectangular plates 202 . In alternative embodiments, the curved plates 202 and inner walls 220 could have other shapes, for example circular or hexagonal.
[0047] A method of forming an energy harvester similar to that of FIGS. 2 and 3 will now be described with reference to FIGS. 4A to 4E .
[0048] FIGS. 4A to 4E are perspective views of an energy harvester 400 at various stages of manufacture, in this example comprising 35 plates 202 arranged in seven columns and five rows.
[0049] With reference to FIG. 4A , in a first step, a grid of conductive tracks is printed or otherwise deposited on the surface of the upper sheet 214 of the structure of FIG. 2 . The top surface of the sheet 214 shown in FIG. 4A corresponds to the bottom surface of the sheet 214 orientation as shown in FIG. 2 .
[0050] In the example of FIG. 4A , the grid of conducting tracks comprises seven tracks 402 to 414 formed in columns. Each of the tracks 402 to 414 comprises five regularly spaced electrodes 416 , in this example formed as “U” shaped tracks. Thus there are a total of 35 electrodes. The respective ends of the tracks 402 to 414 are coupled together by respective tracks 418 and 420 running perpendicular to the column tracks 402 to 414 . The track 420 is for example coupled to a connection terminal 422 close to an edge of the sheet 214 .
[0051] For example, the conductive tracks could be formed of copper or another suitable conducting material, and printed using PCB (printed circuit board) techniques, which are well known in the art.
[0052] FIG. 4B illustrates the upper sheet 214 after a subsequent step in which a piezoelectric layer 210 has been formed over each electrode 416 . For example, the piezoelectric material is formed of PZT (lead zirconate titanate), ZnO or a compound based on lead and zirconium. The piezoelectric layers 210 could be coated, deposited or printed. For example techniques for printing such a material are discussed in more detail in the publication entitled “Processing of Functional Fine Scale Ceramic Structures by Ink-Jet Printing”, M. Mougenot et al., the contents of which is hereby incorporated by reference to the extent permitted by the law.
[0053] In some cases, the printing or depositing of the piezoelectric layers 210 may be followed by a baking step, for example at a temperature of 200° C. or less.
[0054] FIG. 4C illustrates the structure after a subsequent step in which a further grid of conducting tracks is formed over the surface of upper sheet 214 , this further grid being very similar to the grid discussed above with reference to FIG. 4A . In particular, the further grid of conducting tracks comprises electrodes 424 , one of which is formed over each piezoelectric layer 210 . To prevent electrical contact between the conductive tracks of each of the superposed grids, an insulating layer is for example deposited in some areas prior to forming the further grid. The further grid of conducting tracks is coupled to a further terminal 426 near an edge of the upper sheet 214 .
[0055] The further grid of conducting tracks comprising the electrodes 424 is for example printed or coated, for example using well known techniques, such as those used to print RFID (Radio Frequency Identification) antennas.
[0056] FIG. 4D illustrates yet a further step in which the peripheral wall 218 and inner walls 220 are formed over the surface of the upper sheet 214 , and a curved plate 202 is positioned within each inner wall 220 . In particular, the step of placing each of the inner walls on the surface of the upper sheet 214 for example defines a corresponding opening 428 surrounded by the inner wall, and into which the plates 202 are placed.
[0057] In some embodiments, the curved plates 202 are individual elements. Alternatively, they could form a matrix, being interconnected by one or more fingers. Such fingers could be embedded in the inner walls 220 .
[0058] FIG. 4E illustrates a final step of the method in which the lower sheet 216 is glued to the structure opposite the upper sheet 214 to form the finished energy harvester 400 . In some embodiments, this final gluing step may be performed in a partial vacuum such that the cavities defined by each inner wall 220 are at a partial vacuum, and likewise the spacing between the inner walls 220 in the area between the sheets 214 , 216 is also for example at a partial vacuum. Such a feature improves the insulation between the upper and lower sheets 214 , 216 .
[0059] The terminals 422 and 426 (not illustrated in FIG. 4E ) are for example coupled to energy recuperation circuitry 430 , which recuperates the electrical energy resulting from the voltage changes across the surfaces of the piezoelectric layers 210 . This electrical energy is for example used to charge a battery and/or supply a load (not illustrated in the figures).
[0060] As represented in FIG. 4E , due in part to the form of the inner walls 220 , the resulting energy harvester 200 is for example relatively flexible, for example being able to be bent around pipes or placed in contact with other uneven surfaces. Such flexibility improves the thermal contact between the energy harvester 400 and a heat source, and thus leads to a higher thermal gradient across the energy harvester. This in turn leads to greater energy recuperation. Indeed, the warmer the lower sheet 216 , the faster the curved plates 202 will be heated and change shape, thereby increasing the mechanical power generated by the curved plates and thus the electrical power generated by the piezoelectric layers 210 .
[0061] The surface area of the device 200 could be anything from a few square millimetres to several square metres. For example, in some embodiments the device 200 has a surface area of at least 0.1 square metres.
[0062] In an alternative embodiment, the upper sheet 214 and/or lower sheet 216 could comprise features contributing to the final structure. For example, the inner walls 220 and/or peripheral wall 218 could at least partially be formed of a protrusion from the surface of the lower sheet 216 .
[0063] FIG. 5 is a cross-section view illustrating a portion of an energy harvester 500 according to an alternative embodiment. The energy harvester 500 is very similar to the energy harvester 200 of FIG. 2 , and like features have been labeled with like reference numerals and will not be described again in detail.
[0064] In energy harvester 500 , the piezoelectric layers 210 are removed, the inner walls 220 extending to the underside of the upper sheet 214 . Instead, each of the curved metal plates 202 comprises a piezoelectric layer 502 , which is for example similar to the layer 104 of FIG. 1 . Furthermore, an electrode 504 is for example deposited or coated over the piezoelectric layer. In one example, the electrical signals generated by such a piezoelectric layer 502 are recuperated by electrodes (not illustrated in FIG. 5 ), similar to electrodes 416 , 424 described above, printed on the inner surfaces of the upper and lower sheets 214 , 216 . As illustrated, a connecting wire 506 for example couples the electrode 504 to such an electrode formed on the underside of the upper sheet 214 , and a connecting wire 508 for example couples the metal layers of curved plate 202 to an electrode formed on the top side of the lower sheet 216 .
[0065] FIG. 6 is a perspective view illustrating a portion of the structure of FIG. 3 in more detail according to an example in which each of the cavities defined by the inner walls 220 houses a matrix 600 of curved plates 202 . In the example of FIG. 6 , the matrix 600 comprises eight plates arranged in two columns and four rows, although in alternative embodiments the matrix could comprise any number of curved plates, such as hundreds or thousands of plates arranged in an appropriate number of columns and rows.
[0066] As illustrated in FIG. 6 , each of the curved plates 202 is for example attached by a single finger 602 to a common interconnecting rail 604 . In this way, despite being interconnected, each of the plates 202 may flip from one bi-stable state to another independently of the other plates.
[0067] The interconnecting fingers 602 and rail 604 are, for example, all formed of the same layered structure as the curved plates 202 . The matrix 600 is, for example, formed by the method described in relation to FIGS. 5 and 6 of the co-pending application indicated above entitled “Curved plate and method of forming the same”.
[0068] While a number of specific embodiments of a method and device have been described herein, it will be apparent to those skilled in the art that there are various modifications and alterations that could be provided.
[0069] For example, it will be apparent to those skilled in the art that while a few examples of arrangements of curved plates within an energy harvester have been described, other arrangements of the plates would be possible.
[0070] Furthermore, while rectangular curved plates have been described, in alternative embodiments, the plates could have other forms, such as circular or hexagonal. Furthermore, the “U” shaped form of the electrodes 416 , 424 is merely one example, many other forms being possible.
[0071] The various features described in relation with the embodiments described herein could be combined, in alternative embodiments, in any combination.
[0072] Having thus described at least one illustrative embodiment of the invention, various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description is by way of example only and is not intended as limiting. The invention is limited only as defined in the following claims and the equivalents thereto. | 4y
|
This is a divisional of co-pending U.S. application Ser. No. 07/414,810 filed on Sep. 29, 1989, now U.S. Pat. No. 4,982,999.
The adaptive braking system default activated proportioning valve of the present invention is utilized in an adaptive braking system, and particularly for activation upon a failure in the adaptive braking system.
BACKGROUND OF THE INVENTION
Many adaptive braking systems have been proposed for and utilized on vehicles. Some adaptive braking systems include one or more proportioning valves which function in conjunction with the adaptive braking system. Some adaptive braking systems eliminate the need for a proportioning valve. However, should the adaptive braking system fail for any number or variety of reasons, it is highly desirable to have a proportioning valve operating within the braking system so that the rear wheels of the vehicle are prevented from premature lockup during braking of the vehicle, and in the manner in which proportioning valves have been used for many years on vehicles. The present invention provides a solution to the above problem by providing a proportioning valve which is normally inoperative during normal braking and anti-skid braking. However, should the adaptive braking system experience a failure, the proportioning valve is activated and proportions fluid pressure communicated to the rear wheels of the vehicle.
SUMMARY OF THE INVENTION
The present invention comprises an adaptive braking system for a vehicle, the system including proportioning valve means for proportioning fluid pressure communicated between fluid pressure producing means and at least one wheel brake of the vehicle, the proportioning valve means normally deactivated so that fluid pressure is transmitted therethrough without being proportioned by the proportioning valve means, the proportioning valve means being operatively connected with control means of the system, the control means responsive to a failure in the adaptive braking system so as to activate the proportioning valve means such that fluid pressure communicated to said wheel brake is proportioned during said failure.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is described in detail below with reference to the drawings which illustrate embodiments in which:
FIG. 1 is a schematic representation of a typical adaptive braking system having the present invention therein;
FIG. 2 is a section view of a first embodiment of the default activated proportioning valve of the present invention; and
FIG. 3 is a second embodiment of the default activated proportioning valve of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic illustration of a typical adaptive braking system 10. System 10 includes a pressure producing mechanism such as a master cylinder or full power hydraulic booster 12 which includes a pair of chambers 14 and 16 that communicate with hydraulic circuits of the system. Chamber 14 communicates with brake line 24 which transmits fluid pressure to brake lines 26 and 28. Brake lines 26 and 28 are connected with electrovalve means 30 which may comprise any one of or a number of valves which effect any of the typical isolate, build and decay functions of an adaptive braking system. Brake line 28 communicates with one of the front wheels 29 and also with a bypass line 31 which enables fluid to return to chamber 14 during release of the brakes. Line 24 also communicates with brake line 36, electrovalve means 40, brake line 38, and the other front wheel 39. Line 38 and electrovalve means 40 also communicate with the return line 41 which provides the same function as line 31 during release braking. Adaptive braking system 10 is a schematic representation of a typical pump-back system wherein a pump 61 provides, during adaptive braking, fluid pressure via section 62 and 64 for the electrovalves 30, 40, and 50. Chamber 16 of device 12 communicates through brake line 44 with brake line 46, electrovalve means 50, brake line 48 and the rear wheels 49, 59. Electrovalve means 50 provides for the isolation, build and decay functions in the same manner that electrovalves 30 and 40 operate for their respective circuits. Each of the electrovalves 30, 40, and 50 includes a respective return or decay line 37, 47, 57 which communicates with a respective pumping section. Sumps 63 and 65 communicate with brake lines 37, 47, and 57. An accumulator 66 provides pressure as needed in the two front wheel brake circuits. The wheels 29, 39, 49, and 59 include speed sensors 60 which communicate with a control means or ECU 70 via lines 64. Control means 70 provides communication via lines 72 with the respective electrovalve means 30, 40, and 50. Control means 70 communicates via line 75 with proportioning valve means 80. Proportioning valve means 80 is disposed within brake line 44 so that it communicates directly with chamber 16 of pressure producing device 12. It should be clearly understood that the adaptive braking system 10 illustrated herein could be any one of a multitude of adaptive braking systems, which include any type of pressure producing devices, electromagnetic valves, check valves, speed sensors, and so on. The present invention may be utilized in literally any type of adaptive braking system, and may be positioned in the brake line which communicates directly with a chamber of the pressure producing device or may be positioned in brake line 48 so that it communicates directly with at least one of the wheels of the vehicle. The exact positioning of the proportioning valve means can be determined according to the various parameters and requirements of the adaptive braking system.
Proportioning valve means 80 is a normally deactivated proportioning valve which does not affect fluid communication being transmitted from chamber 16 of device 12 to the respective brake line circuit and wheel brake(s). Adaptive braking system 10 provides for the appropriate control of braking pressure to the rear wheels 49, 59 in case of an impending or incipient skidding condition. Therefore, as long as the adaptive braking system is able to operate as needed, the presence of an operative proportioning valve in the system is not required. However, the adaptive braking system may experience a failure in whole or part for any number of reasons, including electrical circuit failure, ECU failure, and so on. Upon the occurrence of a failure in the adaptive braking system, whether this occurs during normal braking or adaptive braking system operation, or when no braking is being effected at all, a default signal will be sent by the ECU via line 75 to proportioning valve means 80 to effect activation of the proportioning valve means. Thus, fluid pressure transmitted from device 12 to at least one of the wheels of the vehicle, and in most cases both of the rear wheels, will be proportioned in the same manner as normally occurs in vehicles that do not have adaptive braking systems. This will prevent a premature lockup or sliding of the wheels during braking as the front of the vehicle moves downwardly and the rear end of the vehicle rises during which there is less traction between the rear wheels and road surface.
FIG. 2 illustrates a first embodiment of a proportioning valve in accordance with the present invention. Proportioning valve 80A comprises a body 81 which transmits fluid pressure via line 43 and opening 82 to opening 83 and line 44. A differential area piston 84 biased by spring 85 would normally operate in response to the fluid pressure to effect proportioning thereof. However, a bypass line 86 permits fluid to bypass around differential area piston 84 and be communicated directly to opening 83 and line 44. Thus, piston 84 does not experience a fully operational pressure differential thereacross and remains inoperative. Bypass 86 includes a chamber 87 and channel 88 which receives valving means 89. Valving means 89 includes a valve seat 93 positioned adjacent valve head 90 of valve shaft 91. Valve shaft 91 extends into and is a part of a solenoid means 92, shaft 91 being biased by spring means 97. An appropriate sealing mechanism 94 is disposed about shaft 91. Shaft 91 includes a recessed area 95 disposed in channel 88. A resettable detent mechanism 100 includes a spring 102 biased head 103 which may be received within recessed area 95. A reset member 104 is disposed exteriorly so that it may be accessed and moved radially outwardly such that head 103 is moved out of engagement with recess 95.
When adaptive braking system 10 experiences a failure which would prevent operation of part or all thereof, control means 70 sends a signal via connection 75 to solenoid 92 which is activated thereby. Solenoid 92 causes shaft 91 to be retracted against spring 97 a distance sufficient to align recess 95 with head 103. Head 103 is biased by spring 102 and enters into recess 95 as soon as the two are aligned. This will retain shaft 91 in a retracted position without the solenoid having to be continually energized. Retraction of shaft 91 moves valve head 90 into engagement with seat 93 so that bypass 86 is closed. The closing of bypass 86 now causes fluid pressure received at opening 82 to be communicated only around the head 84a of differential piston 84 and to opening 83 and brake line 44. Piston 84 will experience a pressure differential thereacross and move laterally in order to proportion braking fluid pressure appropriately. When the adaptive braking system has been repaired so that it will operate appropriately, the resettable detent mechanism may be reset by pulling reset member 104 radially outwardly to retract head 103 and allow the spring biased shaft 91 and valve head 90 to move downwardly so that valve seat 93 is opened and bypass 86 is reopened. This will place proportioning valve means 80A in an inoperative mode.
FIG. 3 illustrates a second embodiment of the proportioning valve of the present invention. Proportioning valve means 80B comprises a body 110 which includes an opening 112 that communicates with brake line 43, and an opening 113 which communicates with brake line 44. The differential area piston 114 is biased by a spring 115 and includes an extension member 116. Body 110 includes a threaded end cap 111 which carries a fusible link 120. Fusible link 120 communicates operatively with the ECU via connection 75. Extension 116 abuts the fusible link so that piston 114 is held to the left such that head portion 118 does not engage seal 119. This places piston 114 in an inoperative position so that fluid may flow freely between openings 112 and 113. Should the adaptive braking system experience a failure, a signal is sent via connection 75 to fusible link 120 which will, over a short period of time, dissipate. Fusible link 120 need not dissipate immediately, but it is preferable that it dissipate over a short period of time so that intermittent or short term interruptions in the ECU electrical system will not cause the fusible link to dissipate prematurely. When fusible link 120 has dissipated, piston 114 may move laterally in response to a pressure differential thereacross and effect the proportioning of fluid pressure.
Vehicles which include adaptive braking systems typically operate to maintain brake balance under various road conditions. Upon failure of the adaptive braking system to operate regularly, brake balance can be jeopardized and the vehicle can become unstable if the rear wheels should lock before the front wheels. The present invention provides a solution to this problem by activating proportioning valve means which will decrease pressure to the rear wheels during the period that the adaptive braking system is inoperative. This will reduce the likelihood of the rear wheels locking. | 4y
|
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of U.S. patent application Ser. No. 14/668,817, entitled “Fall Protection Guardrail,” filed on Mar. 25, 2015, which claims the benefit of U.S. Provisional Patent Application Ser. No. 61/970,227, entitled “Fall Protection Guardrail,” filed Mar. 25, 2014, which applications are incorporated in their entirety here by this reference.
TECHNICAL FIELD
The present invention relates to a guardrail support used during construction and, more particularly, to a novel guardrail support for use in the erection of a fall protection barrier at multi-story construction sites using wood framing.
BACKGROUND
Modern construction techniques applicable to multi-story apartment and commercial building construction require that safety barriers or guardrails be erected around the perimeter of all uncompleted floors to protect workers against accidental falls. In the United States, safety regulations require construction worker fall protection for any walking or working surface that is six feet (1.8 meters) or more above a lower level. Guardrail systems are a common means of fall protection. Safety regulations often require that guardrail systems have at least two rails, a top rail with a top edge that is typically 39-45 inches (1.0-1.2 meters) above the walking/working level, and a midrail that is midway between the walking/working level and the top rail.
The general practice to erect such fall protection safety barriers, particularly in wood-framed buildings, is to use long “2×4” boards (commonly referred to as “two-by-fours”). Such boards are nailed together in varying patterns in order to provide the desired guard railings. After such railings have served their purpose, they are knocked down, the longer boards typically reserved for future guard railings. The shorter boards are not always reusable. Furthermore, the longer lengths of lumber frequently become damaged due to the application thereto of repeated impact blows, different nail placements, and when tearing out nails upon disassembly. Although such makeshift guard railings may meet safety requirements, they require more than one person and a fair amount of time to construct and often result in the destruction of the materials used when they are disassembled after completion of work at a construction site. Obviously, the additional labor and cost of materials used will add to the expense of the job. Many such railings also fail to pass the rigidity requirements of safety inspectors.
As a result, various designs have been proposed to aid in erecting temporary fall protection barriers that meet strict safety guidelines. To a large extent, however, most of the proposed designs are impractical, expensive, and too complicated. Guardrail systems that are too complicated will not be used efficiently and/or properly by workmen at a construction site, thereby posing a safety risk.
Therefore, a need exists for a simple and reusable guardrail system that is effective in preventing accidental falls, meets safety guidelines, and can be assembled and disassembled efficiently.
SUMMARY
A fall protection guardrail support and assembly for erecting a fall protection barrier for workmen at construction sites, particularly in wood-framed buildings, is disclosed herein. Some of the advantages of the guardrail support disclosed herein are that it is quick and easy to install and assemble and disassemble. The components are reusable, and the lumber used for the rails suffers less damage on disassembly than in most current systems, thus allowing its reuse in most situations.
In accordance with a first aspect of the present invention, a guardrail support for a temporary safety barrier is provided wherein the guardrail support comprises a support bracket adapted with a positioning stop to position a support bracket against a vertical wall framing member and further adapted to attach to the vertical framing member, wherein the support bracket also extends laterally from the wall framing member to an integral pole support that is vertically oriented, and a pole that is adapted to fit into the pole support, the pole having an upper rail support adapted to hold a plurality of rails at a height required for a top rail, and a lower rail support adapted to hold a plurality of rails at a height required for a midrail. The rails are preferably comprised of 2×4 lumber, as it is inexpensive and readily available. The pole support and pole may have holes that match up when the latter is inserted into the former, such holes adapted to accommodate a safety pin or a screw, bolt, or other suitable device to prevent the pole from being accidentally removed from the pole support. The upper and lower rail supports of the pole may be equipped with a rail retention device, to prevent the rails from being accidentally removed from the rail supports, which may comprise a safety pin through a set of holes in the rail support and pole wherein the safety pin is located atop the rails or through a hole in the rails, a hinged top cover for the bracket that closes the bracket opening, or a screw through a support bracket into both rails, as shown in FIGS. 9 and 11 , or any other suitable retention device to prevent accidental removal of the rails.
In accordance with another aspect of the invention, additional brackets may be attached to the support pole, adapted and positioned so that they can support a scaffolding, which may have fall protection afforded by the above-described rails. In such an embodiment, the support bracket and pole would have to be adapted to handle the additional weight from scaffolding. In an alternate embodiment, two or more support brackets could be used with a single support pole that has a longer insertion member. The framing member to which the support bracket(s) is attached should be capable of handling the scaffolding load, both vertically and in other load directions. Additional attachment points could be adapted for other uses.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 depicts a perspective view of a support bracket of the present invention;
FIG. 2 depicts a perspective view of a support bracket of the present invention;
FIG. 3 depicts a perspective view of the present invention in use on a framing member;
FIG. 4 depicts an exploded view of the present invention and a framed wall in a horizontal position;
FIG. 5 depicts a perspective view of the present invention installed on a framed wall in a horizontal position;
FIG. 6 depicts a perspective view of the present invention installed on a framed wall in a vertical position;
FIG. 7 depicts a close-up perspective view of an embodiment of the rail support of the present invention;
FIG. 8 depicts a close-up perspective view of an embodiment of the rail support of the present invention;
FIG. 9 depicts a cross section view taken through line 9 - 9 of the embodiment of the present invention shown in FIG. 8 .
FIG. 10 depicts an exploded view of another embodiment of the present invention.
FIG. 11 depicts the embodiment shown in FIG. 10 in use.
FIGS. 12A and 12B show variations of the bottom bracket.
DETAILED DESCRIPTION OF THE INVENTION
The detailed description set forth below in connection with the appended drawings is intended as a description of presently-preferred embodiments of the invention and is not intended to represent the only forms in which the present invention may be constructed or utilized. The description sets forth the functions and the sequence of steps for constructing and operating the invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and sequences may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention.
The fall protection guardrail described herein includes a novel support bracket 2 that attaches to framing 4 and holds a pole 6 that has a top end 5 and a bottom end 7 . As shown in a preferred embodiment depicted in FIGS. 1 and 2 , the support bracket 2 may comprise two components, an attachment member 8 and a pole support 10 .
The attachment member 8 may be constructed of an attachment face 12 , with a first surface 14 and a second surface 16 , and four sides. The attachment face 12 may be rectangular and substantially planar, and its surface may define at least one attachment hole 56 . On one or more sides of the attachment face 12 , reinforcing members 18 a - d are coupled with the attachment face 12 . The reinforcing members 18 a - d may be planar rectangles such as flat bar stock, typically arranged perpendicular to the attachment face 12 . The reinforcing members 18 may also be other shapes (not shown) such as an L-shape (angle iron), square or rectangular tubing, channel bar, I-beam, T-bar, or any other suitable shape, and may be arranged in any suitable configuration on the attachment face 12 . In a preferred embodiment the attachment face 12 is approximately 10 inches (25.4 cm)×6 inches (15.24 cm), although other dimensions may be used.
In a preferred embodiment, the attachment member 8 may be comprised of a single sheet of steel, with cut out corners, wherein the sides are folded up on the first side of the attachment face 12 to form the reinforcing members 18 a - d , and their corners are fastened together, typically by welding, but any suitable attachment method may be used. The resulting open “box” may have three sides 18 a - c or four sides 18 a - d . Alternatively, the reinforcing members 18 a - d can comprise separate bar stock or other shapes described above, welded or otherwise coupled with the attachment face 12 , again with three or four sides. In either case, the attachment member may comprise a top reinforcing member 18 a , a bottom reinforcing member 18 c opposite and parallel to the top reinforcing member 18 a , and a side reinforcing member adjacent 18 b , perpendicular, and attached to the top and bottom reinforcing members 18 a , 18 c to form the open box configuration, wherein the side reinforcing member 18 b is opposite the pole support 10 . In some embodiments, the pole support 10 may make up the fourth reinforcing member to complete the open box configuration. In other embodiments, a second side reinforcing member 18 d may be attached to the attachment member 8 opposite the first side reinforcing member 18 b and adjacent and perpendicular to the top and bottom reinforcing members 18 a , 18 c . The pole support 10 may be attached to the second side reinforcing member 18 d.
In a preferred embodiment, the pole support 10 may be constructed of square tubing, although other shapes of tubing may be used so long as the tubing comprises at least one wall 11 defining a first cavity 13 . As used herein, the term “square tubing” shall include any rectangular tubing with equal or unequal side dimensions. Square tubing may be advantageous to keep the pole 6 in a certain orientation without use of a pin, and also has greater bending strength than round tubing for a given thickness when the moment is in line with the sides of the tubing. Square tubing may also be easier to attach to the square sides of the attachment member 8 “box.” Square tubing also has an advantage if a safety pin is used, described below. Nevertheless, other shapes of tubing may be used for the pole support 10 . However, non-cylindrical shaped tubing is preferred to prevent unwanted rotation of the pole 6 within the pole support 10 . In a preferred embodiment, the pole support 10 is comprised of square tubing defining a first cavity 13 having a first cavity dimension of approximately 1.25 inches (3.175 cm) by 1.25 inches and an outer pole support dimension of approximately 1.5 inches (3.81 cm) by 1.5 inches, although other dimensioned tubing may be used.
The attachment member 8 may then be coupled with the pole support 10 . The pole support 10 may be coupled with the attachment member 8 by welding or other suitable methods. In a preferred embodiment, the attachment member 8 is a three-sided “box,” and the pole support 10 is a piece of square tubing with a side dimension that is the same width as the reinforcing members 18 a - c , wherein the square tubing may be welded or otherwise coupled with the attachment member 8 so that the square tubing becomes the fourth side of the “box” and acts as a reinforcing member 18 d.
As shown in FIGS. 1 and 2 , in a preferred embodiment the attachment member 8 is a rectangle with unequal sides, where one of the long sides is coupled with the pole support 10 . Although the pole support 10 is shown as being the same length as the long side of the attachment member 8 , the pole support 10 could be longer or shorter.
As shown in FIGS. 1 and 2 , in a preferred embodiment a positioning member 20 is attached to the second surface 16 of the attachment face 12 . The purpose of the positioning member 20 is to act as a stop to accurately position a first portion of the second surface 16 of the attachment face 12 of the attachment member 8 that is distal to the pole support 10 against a building framing member 4 , as shown in FIG. 3 . Preferably, the first portion of the second surface 16 of the attachment face 12 touching the framing member 4 (referred to as the “attachment surface” 22 ) is approximately equal to the width of the framing member 4 , although it may be wider or narrower. For example, for a building made with 2×4 framing members 4 (which are nominally 1.5 inches×3.5 inches (3.81 cm×8.89 cm)), the attachment surface 22 would be 3.5 inches wide. For a building with framing members 4 that are larger, the attachment surface 22 could be sized to match, or be kept at the same 3.5 inch size, or made larger or smaller. Although the positioning member 20 is shown as a piece of angle iron in FIGS. 1-3 , it may be any suitable structure that makes the attachment surface 22 the appropriate dimension, whether it be one or more “ears” cut into the attachment face 12 and bent up to act as a stop, or some other type of bar stock, round stock, or any suitable shaped protrusion. The attachment surface 22 may be equipped with attachment holes 56 to accommodate fasteners 42 , described below.
In some embodiments, the attachment face 12 may have attachment holes 56 on both sides of the positioning member 20 . This allows the attachment member 8 to be attached to a framing member with the first surface 14 facing the framing members 4 . This may be suitable when framing members 4 are made with large 2×6 or 2×8 beams, and the like. Stronger screws or fastening devices may be used to secure the attachment member 8 in this manner.
As shown in FIG. 3 , a pole 6 may be adapted to fit into the pole support 10 and equipped with a pole stop 24 in between the top end 5 and the bottom end 7 , but preferably near its bottom end 7 . Thus, the bottom end 7 defines a pole support insert 9 . The pole stop 24 insures that the pole support insert 9 is suitably inserted into the pole support 10 , but insures the pole 6 cannot slip further into the pole support 10 than necessary. The pole stop 24 may be constructed of bar stock or square tubing that is the same dimension as the pole support 10 , and welded or suitably fastened to the pole 6 at the desired location. In a preferred embodiment, the pole 6 is comprised of square tubing that has an inner dimension of approximately 1.0 inches (2.54 cm) by 1 inch, and an outer dimension of approximately 1.25 inches (3.175 cm) by 1.25 inch.
As shown in FIG. 3 , both the pole support 10 and the pole 6 may be equipped with corresponding pole locking pin holes 26 , 27 , through which a pole locking pin 28 may be inserted to prevent the pole 6 from accidentally falling or lifting out of the pole support 10 . The pin holes 26 , 27 may be spaced apart in regular increments, such as two inch increments so that the proper height of the pole 6 can be selected, for example to accommodate 10-inch, 12-inch, 14-inch floor joists, and the like. The pole locking pin 28 may be a standard spring and ball detent pin, such as those sold under the Kwik-Lok® brand, with or without a release button, or any other suitable locking pin, including but not limited to heavy duty cotter pins, pintle pins, industrial safety and snap pins, or other suitable retaining pins. The pole locking pin 28 may be attached to either the pole 6 , the support bracket 2 or the pole support 10 by a wire cable or other suitable retaining device, so that that a pole locking pin 28 is always within reach.
As shown in FIG. 4 , in a preferred embodiment the upper portion of the pole 6 is comprised of a lower rail support 30 and an upper rail support 32 . The rail supports 30 , 32 may be constructed of bar stock welded into the desired configuration. In a preferred embodiment, the rail support is comprised of an L-shaped piece of bar stock that is coupled with the pole 6 near the top end and a diagonal element 38 coupled with the L-shaped piece of bar stock. The L-shaped piece of bar stock comprises a horizontal element 34 and vertical element 36 connected at a corner 35 . The diagonal element 38 is coupled to the corner 35 of the “L” and also coupled with the pole 6 at a position distal to the pole's 6 top end to act as a support for the “L.” In particular, the diagonal element 38 has a first end 37 and a second end 39 opposite the first end 37 , the first end 37 of the diagonal element 38 coupled to the corner 35 of the L-shaped piece of bar stock and the second end 39 of the diagonal element 38 attached to the pole 6 at a position below the horizontal element 34 to act as a support for the L-shaped piece of bar stock.
The rail supports 30 , 32 may be constructed in any configuration or manner to provide sufficient support for the rails 44 . The rails 44 are elongated structures, each rail having a length L, a width W, and a thickness T, wherein the length L is greater than the width W, and the width W is greater than or equal to the thickness T.
In a preferred embodiment, the vertical element 36 of the “L” of the rail support is at least as tall as the width W of the rail 44 . The vertical element 36 of the “L” of the upper rail support 32 would typically terminate at or near the same height as the pole 6 . For example, when using 2×4 lumber as rails 44 , the vertical element 36 of the “L” of the rail support would be at least 3.5″ tall. In a preferred embodiment, the horizontal element 34 of the “L” of the rail support may have a length that is approximately twice the thickness T of the rail 44 to accommodate two rails 44 , as shown in FIGS. 6-9 . For example, when using 2×4 lumber as rails 44 , the horizontal element 34 of the “L” of the rail support would be at least 3.0 inches (7.62 cm) wide on the interior, to accommodate two rails 44 , each having a thickness T of 1.5 inches with a bit of excess space to allow some play.
As shown in FIG. 4 , a framed wall 40 is typically constructed on the ground or other horizontal surface. When the wall framing is complete but still lying horizontally, the attachment surface 22 of the support bracket 2 may be placed against a framing member 4 , and attached to the framing member 4 by screws, nails, or other fasteners 42 driven through the attachment holes 56 into the framing member 4 . As shown in FIGS. 1 and 2 , the topmost reinforcing member may also have one or more attachment holes 56 , and a fastener 42 may be driven through the hole(s) and into the top plate 42 of the wall framing 40 . The fasteners 42 should be of sufficient strength to hold the support bracket 2 to the framing member 4 when the guardrail system is assembled and under the specified minimum load. In a typical configuration, the support bracket 2 is fastened to the framed wall 40 such that the pole support 10 is located on the outside of the wall.
At some point, preferably before the framed wall 40 is raised to the vertical position, the pole 6 is placed into the pole support 10 . A pole locking pin 28 may be inserted into the pole locking pin holes 26 , 27 as shown in FIG. 5 . Then the wall is raised to the vertical position and secured to other framing, and the guardrail supports are already in position. Once the floor (not shown) is attached to the top of the framed wall 40 , the rails 44 can be placed into the rail supports 30 , 32 .
In a preferred embodiment, the vertical element 36 of the “L” of each rail support would be taller than the width W of the rail 44 to accommodate a rail locking pin 46 to function as the retention device. As shown in FIG. 6 , in such a configuration, the pole 6 and the vertical element 36 of the “L” of the rail support would define corresponding rail locking pin holes 48 , which are typically located slightly higher than the largest dimension of the rail. After the rails 44 are placed into the rail supports 30 , 32 , the rail locking pins 46 are inserted into the rail locking pin holes 48 , 49 to retain the rails 44 in the rail supports 30 , 32 , as shown in FIG. 6 .
In alternative embodiments, the rails 44 may be retained in the rail supports 30 , 32 by other structures that serve as the retention device. In FIGS. 7-9 , one such alternative embodiment is shown, which comprises a vertical element 36 of the “L” of the rail support that is the same height or slightly shorter than the larger dimension of the rail, and a retention clamp 50 as the retention device, which may be an “L” shaped element coupled with the pole 6 by a hinge 52 or other suitable attachment method or apparatus. The vertical element 36 of the “L” of the rail support and the retention clamp 50 may have corresponding retention holes 54 , 55 and a nail, screw, or other fastener 42 may be driven through the retention holes 54 , 55 and into one or both rails 44 to secure the rails 44 in the rail support, as shown in FIGS. 7-9 . Alternatively, the retention clamp 50 may be omitted and a fastener 42 may be driven through a retention hole in the vertical element 36 of the “L” of the rail support, or through a retention hole in the pole 6 , or both, into one or both of the rails 44 .
In yet another embodiment, the retention device may be a retention lip 31 that is at the top of the vertical element 36 and extends towards the pole 6 . The retention lip 31 could be any structure that extends towards pole 6 , such as a bent portion of the vertical element 36 , a separate welded element, or any suitable structure. As shown in FIG. 11 , to secure a pair of rails in this embodiment, a first rail 44 is placed against the vertical element 36 , beneath the retention lip 31 , and a second rail 44 is placed between the first rail 44 and the pole 6 , and at least one fastener 42 is driven through both the first and second rails 44 , which lock them together. Then the retention lip 31 , which is of sufficient length to engage the top of the first rail 44 , prevents these locked-together rails 44 from lifting out of the rail support 30 , 32 . To prevent the rails 44 from moving laterally within the rail support 30 , 32 , one or more fasteners 42 with a protruding head could be driven through the rails 44 on one side or both sides of the vertical element 36 or the pole 6 , wherein the protruding head would engage the vertical element 36 or the pole 6 to prevent significant lateral movement of the rails 44 . Alternatively, the pole 6 and/or the vertical element 36 could have one or more holes 55 through which a single fastener 42 could be driven into the rails 44 to prevent both lateral and vertical movement of the rails. This latter embodiment could be used with or without the retention lip 31 .
In some embodiments, the support bracket 2 could be used to support a pole 6 that holds scaffolding 47 . The support bracket 2 and pole 6 would have to be sized to accommodate the additional load of the scaffolding 47 and the worker(s) using the scaffolding 47 , as well as the live loads from those worker(s). A longer support bracket 2 may be used to spread the load over a greater length of the framing member 4 . Alternatively, several smaller support brackets 2 may be used to support a single pole 6 . In some embodiments, the pole support 10 may be positioned farther away from the building than the guardrail supports described above, to accommodate the width of the scaffolding walking surface. The pole 6 may be long enough to insert into the entire length of such extended support bracket(s) 2 , although a shorter or longer length could be used. In a preferred embodiment, the scaffolding may be supported by scaffolding supports, a similar structure as the rail supports 30 , 32 attached to the pole 6 , but wider and shallower to accommodate the scaffolding walking surface, which may typically be 12 to 18 inches (30.5 to 45.74 cm) wide. The scaffolding surface may be secured in a similar manner as the rails 44 of the above described guardrail system, with locking pins. Alternatively, the scaffolding walking surfaces could be mounted on the scaffolding supports in a similar manner as existing scaffolding systems, with the scaffolding supports adapted to such mounting. The end of a scaffolding walking surface may be supported by a scaffolding end support, which can be on two separate poles 6 close together, each with an end support, or a single pole 6 with two end supports. The scaffolding support may be further adapted to attach to the building. A guardrail system as described above could be integrated into the pole 6 , with the pole 6 having rail supports 30 , 32 extending above the scaffolding walking surface. Such guardrail system would typically be used to prevent falls from the scaffolding, and thus would be positioned on the outside of the scaffolding.
Alternatively, the scaffolding support pole could be a separate structure from the rail support pole. A scaffolding support pole could be placed into a support bracket, which bracket may have additional structure to attach to horizontal framing members to provide additional support. The scaffolding support pole may be substantially vertical and relatively close to the building, then have a cantilevered scaffolding support bracket incorporated into it that extends away from the building to hold the scaffolding walking surface. At the outer edge of the cantilevered scaffolding support bracket, another support bracket could be incorporated to hold a pole to support a guardrail system as described above.
In the preferred embodiment, a support bracket 2 and pole 6 may be used with our without a scaffolding frame 60 . Without the scaffolding frame 60 , the guardrail system works as described above. With the scaffolding frame 60 , the scaffolding frame 60 would be attached to the support bracket 2 and the pole 6 would be attached to the scaffolding frame 60 so that the support bracket 2 supports the pole 6 via the scaffolding frame 60 .
As shown in FIG. 10 , in the preferred embodiment, the scaffolding frame 60 comprises a vertical support bar 62 having a lower end 64 and an upper end 66 opposite the lower end 64 , a horizontal support 70 bar having a proximal end 72 and a distal end 74 opposite the proximal end 72 , and a diagonal support bar 80 having a first end 82 and a second end 84 opposite the first end 82 . The proximal end 72 of the horizontal support bar 70 is attached to the upper end 66 of the vertical support bar 62 . The first end 82 of the diagonal support bar 80 is attached to the distal end 74 of the horizontal support bar 70 , and the lower end 64 of the vertical support bar 62 is attached to the diagonal support bar 80 near the second end 84 . Therefore, the vertical support bar 62 , the horizontal support bar 70 , and the diagonal support bar 80 generally define a triangular configuration.
In the preferred embodiment, the proximal end 72 of the horizontal support bar 70 extends past the vertical support bar 62 , thereby terminating at a free terminal end 76 . Attached to the horizontal support bar 70 in between the vertical support bar 62 and the free terminal end 76 of the horizontal support bar 70 may be another pole support insert 90 . The pole support insert 90 extends downwardly and perpendicularly from the horizontal support bar 70 and parallel to the vertical support bar 62 . The pole support insert 90 of the scaffolding frame 60 is substantially similar to the pole support insert 9 of the pole 6 so that either of the two can be inserted into the pole support 10 of the support bracket 2 .
In the preferred embodiment, the second end 84 of the diagonal support bar 80 extends past the lower end 64 of the vertical support bar 62 . The second end 84 of the diagonal support bar 80 may comprise a bottom bracket 100 . In the preferred embodiment, the bottom bracket 100 comprises a first arm 102 and a second arm 104 opposite and parallel to the first arm 102 , the first and second arms 102 , 104 attached to the second end 84 of the diagonal support bar 80 with the first and second arms 102 , 104 defining a gap therebetween. The distance between the first and second arms 102 , 104 is sufficiently wide to receive the stud of the framing. Each of the first and second arms 102 , 104 may define attachment holes 106 permitting the first and second arms 102 , 104 to be fastened to a stud inserted therebetween.
In some embodiments, the first arm 102 and the second arm 104 each may comprise flanged endings 110 , 112 as shown in FIG. 12A . The flanged endings 110 , 112 may be substantially perpendicular to their respective first and second arms 102 , 104 and extend in opposite directions relative to each other. The flanged ends 110 , 112 may be sufficiently parallel to each other so as to be able to rest flush against a flat surface. The flanged ends 110 , 112 may also define attachment holes 114 . This configuration allows the second end 84 of the diagonal support bar 80 to attach to an appropriately sized stud if the stud fits in between the first and second arms 102 , 104 , or to attach to a particularly wide frame portion by fastening the flanged ends 110 , 112 flush against the frame. In an alternative embodiment, the bottom bracket 100 may have angled flanges 110 , 112 as shown in FIGS. 10-11 , adapted to fit corner framing members. In addition, as those in the art will appreciate, various pieces could be attached to the bottom bracket 100 shown in either FIG. 10 or FIG. 11 , to accommodate a variety of angles and shapes to fasten to various framing members. In some embodiments, as shown in FIG. 12B , the bottom bracket 100 may be a T-bar having a flat base 117 and a perpendicular brace 115 . The perpendicular brace 115 may have holes 114 . The flat base 117 may be pressed flat against the front of the frame with the perpendicular brace 115 against the side of the frame. The perpendicular brace 115 can be fastened to the frame with a screw or some other fastener. In another embodiment, the perpendicular brace 115 can be located in another position along the face of the flat base 117 to be adapted to fit a particular side of a framing member. For example, the perpendicular brace 115 could located on the edge of the face of the flat base 117 .
For corner scaffolding, the length of the horizontal support bar 70 may have to be longer to accommodate the scaffolding 47 because the scaffolding frame 60 for a corner is at a 45 degree angle to the scaffolding frames 60 that are mounted 90 degrees relative to the walls of the building.
A second pole support 120 may be attached to the distal end 74 of the horizontal support bar 70 and/or the first end 82 of the diagonal support bar 80 , perpendicular to the horizontal support bar 70 . The second pole support 120 defines a second cavity 122 having a second cavity dimension. Thus, with the scaffolding frame 60 installed on the first pole support 10 of the support bracket 2 , the pole 6 can be installed on the second pole support 120 of the scaffolding frame 60 .
As shown in FIG. 11 , in the preferred embodiment, in which the pole 6 can be interchangeably inserted into the first pole support 10 (or corner bracket 130 ) or the second pole support 120 , the pole support insert 9 of the pole 6 located below the pole stop 24 may comprise a stepped taper 17 to decrease an outer dimension of the pole support insert 9 in a stepwise manner moving towards the bottom end 7 of the pole 6 , thereby defining a larger region 19 of the pole support insert 9 having a first dimension above the step 17 and a smaller region 21 of the pole support insert 9 having a second dimension below the step 17 . The first dimension of the pole support insert 9 may be greater than the second dimension of the pole support insert 9 of the pole 6 . The first cavity 13 dimension is substantially the same as the second dimension of the pole support insert 9 , but smaller than the first dimension of the pole support insert 9 such that the larger region 19 of the pole support insert 9 cannot enter into the first cavity 13 of the first pole support 10 or the third cavity 142 of corner bracket 130 .
The second cavity 122 dimension is substantially the same as the first dimension of the pole support insert 9 , and larger than the second dimension of the pole support insert 9 such that the larger region 19 of the pole support insert 9 and the smaller region 21 of the pole support insert 9 can pass through the second cavity 122 until the second pole support 120 abuts against the pole stop 24 .
The reason for the varying dimensions is to accommodate the required heights for rail heights. For example, fall protection guardrails typically have a top rail at 42 inches above the flooring and a mid-rail 21 inches above the flooring, whether that flooring is for a building or scaffolding. If a first pole support 10 (or corner bracket 130 discussed below) is mounted on a framing member below the floor joist or rim board, the pole 6 has to be long enough to accommodate that distance so that the rails 44 are at the required height above the floor. Thus, the smaller region 21 of the pole support insert 9 fits into the first cavity 13 of the first pole support 10 or the third cavity 142 of corner bracket 130 (discussed below), and stops when the larger region 19 of the pole support insert 9 abuts against the top of the first or third cavities 13 , 142 . In contrast, when the pole 6 is used for scaffolding, the horizontal support 70 defines the floor of the scaffolding 47 , so there is no need to compensate for floor joist height. Thus the larger region 19 of the pole support insert 9 passes through the second cavity 122 until the top of the second pole support 120 abuts against the pole stop 24 , which puts the rail supports 30 , 32 at the proper heights for the scaffolding 47 .
The guardrail system may further comprise a corner bracket 130 that can be substituted for the support bracket 2 when the guardrail is being installed at a corner of the framing 4 . In the preferred embodiment, the corner bracket 130 may comprise a third pole support 132 and an angled attachment 134 member having a first plate 136 operatively connected to a second plate 138 at substantially a right angle. The third pole support 132 may be connected to the angled attachment member 134 where the first plate 136 meets the second plate 138 . The first and second plates 136 , 138 each comprise a plurality of attachment holes 140 to fasten the corner bracket 130 to a corner of the framing, wherein the third pole support 132 comprises a third cavity 142 having a third cavity dimension that is substantially equal to the first cavity dimension of the first pole support 10 .
Therefore, in use, a support bracket 2 (or a corner bracket 130 if at a corner of the framing) may be fastened to a lower floor framing 4 lying horizontally on a ground, the lower floor framing 4 comprising a plurality of studs and a top plate. A pole support insert 9 or 90 may be inserted into the first pole support 10 , wherein the pole support insert 9 or 90 is operatively connected to a pole 6 such that when the pole support insert 9 or 90 is inserted into the first pole support 10 , a top end 5 of the pole 6 is at a desired height to create a guardrail that meets or exceeds government standards for temporary guardrail systems, wherein the pole 6 comprises at least one rail support 30 , 32 . The pole support insert 9 or 90 may be secured in the first pole support 10 . The lower floor framing 9 can then be erected placing the rail support 30 , 32 at the proper position. Rails 49 may be installed into the at least one rail support 30 , 32 , whereby the guardrail is properly positioned on an upper floor area to protect construction workers working on the upper floor from falling. In addition, a support bracket 2 or a corner bracket 130 could be installed at any point in the construction process, and guardrails and/or scaffolding placed as needed.
In some embodiments, in which a scaffolding is desired, the pole support insert 90 of a scaffolding frame 60 may be inserted into the first pole support 10 , the scaffolding frame comprising a second pole support 120 . The pole 6 is then inserted into the second pole support 120 to operatively connect to the pole support insert 90 .
The foregoing description of the preferred embodiment of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention not be limited by this detailed description, but by the claims and the equivalents to the claims appended hereto. | 4y
|
PRIORITY CLAIM
[0001] The present application claims priority benefit under 35 U.S.C. §120 to, and is a continuation to U.S. patent application Ser. No. 13/563,541, filed Jul. 31, 2012, entitled “Optical Sensor Including Disposable and Reusable Elements,” which is a continuation of U.S. patent application Ser. No. 11/606,455, filed Nov. 29, 2006, entitled “Optical Sensor Including Disposable and Reusable Elements,” which claims priority benefit under 35 U.S.C. §119(e) from U.S. Provisional Application No. 60/740,541, filed Nov. 29, 2005, entitled “Optical Sensor Including Disposable and Reusable Elements.” The present application incorporates the foregoing disclosures herein by reference.
REFERENCE TO RELATED APPLICATIONS
[0002] This application also relates to U.S. Pat. No. 6,920,345, filed on Jan. 24, 2003 and issued on Jul. 19, 2005, entitled “Optical Sensor Including Disposable And Reusable Elements.” The present application also incorporates the foregoing disclosure herein by reference.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Disclosure
[0004] The present disclosure relates to noninvasive optical sensors capable of detecting light attenuated by body tissue. More specifically, the disclosure relates to the combination of reusable and disposable components of such sensors.
[0005] 2. Description of the Related Art
[0006] Early detection of low blood oxygen is important in a wide range of applications, including patient monitoring, the fitness industry, home care and the like. Noninvasive oximetry was developed to study and to measure, among other things, the oxygen status of blood. Pulse oximetry—a noninvasive, widely accepted form of oximetry—relies on a sensor attached externally to a patient to output signals indicative of various physiological parameters, such as a patient's blood oxygen saturation.
[0007] A pulse oximeter sensor generally includes one or more energy emission devices, such as specific wavelength emitting LEDs, and one or more energy detection devices. The sensor is generally attached to a measurement site such as a patient's finger, ear, ankle, or the like, using an attachment mechanism such as a disposable tape, reusable housing, a plastic or hook-and-loop fastening strap, or the like. The attachment mechanism positions the emitters and detector proximal to the measurement site such that the emitters project energy into the blood vessels and capillaries of the measurement site, which in turn attenuate the energy. The detector then detects that attenuated energy. The detector communicates at least one signal indicative of the detected attenuated energy to a signal processing device such as an oximeter. The oximeter generally calculates, among other things, one or more physiological parameters of the measurement site.
[0008] Noninvasive oximetry sensors can be disposable, reusable, or some combination thereof. Reusable sensors offer advantages of superior cost savings. However, reusable sensors are often available in a limited number of sizes even though patient measurement sites, such as fingers or toes, can have a much larger size distribution. Therefore, sometimes reusable sensors do not readily conform to each patient's measurement site. Disposable sensors on the other hand offer superior conformance to the measurement area. However, disposable sensors are generally more costly due to limited use of the relatively expensive sensor components which could otherwise last for repeated uses.
[0009] Faced with the drawbacks of reusable and disposable sensors, manufacturers began designing a number of middle-ground sensors. For example, some manufacturers offer a reusable detector portion that couples to a disposable emitter portion. After a single use, the disposable emitter portion is detached from the reusable detector portion and discarded. While this design reuses some of the expensive electronic components, obviously others are still discarded.
[0010] Another example of a middle-ground sensor includes a reusable “Y” type sensor, where a reusable emitter portion connects to one branch of the “Y” while a reusable detector portion connects to the other branch. A disposable tape positions the two branches on a measurement site. In this design, the electronics are reusable; however, the multiple wires tend to be somewhat difficult to properly attach, especially with a moving patient.
[0011] Other examples of middle-ground sensors include a disposable tape sandwich where a reusable flexible circuit housing an emitter portion and a detector portion, are “sandwiched” between adhesive layers. Separation of such disposable tape sandwiches can be cumbersome. In yet another example of a middle-ground sensor, the Assignee of the present application disclosed a reusable flexible circuit that is snapped into a disposable tape. In an embodiment of that disclosure, small pegs on the flexible circuit snap into mechanically mating elements on the disposable tape. Grooves allow some longitudinal travel between the reusable portion and the disposable portion, thereby allowing for some self adjustment between components to account for differences in radial attachment requirements.
SUMMARY OF THE DISCLOSURE
[0012] However, even with the advances discussed in the foregoing, there continues to be a need for a commercially viable, straightforward, middle-ground solution that offers reusability of expensive electronic components while maintaining some of the advantages of disposable attachment.
[0013] Accordingly, one aspect of an embodiment of the present disclosure is to provide a sensor having reusable and disposable components. In an embodiment, the sensor advantageously includes a disposable component structured to provide a locking feature capable of reducing a chance that the disposable and reusable components can separate when attached or otherwise in close proximity to the body. In an embodiment, a locking mechanism takes advantage of longitudinal displacement and engages when the reusable and disposable portions of the sensor are curved around the measurement site (such as a finger). Separation of the reusable portion from the disposable portion is then advantageously complicated until the sensor is removed from the patient and the displacement is reversed.
[0014] A further aspect of an embodiment of this disclosure is that the tip of the reusable sensor component slides angularly into the front housing component on the disposable portion before sitting flat in a slot or guide. The slot or guide includes a rubber stop that in an embodiment advantageously provides a fluid-tight or at least fluid resistant contact.
[0015] In a further embodiment, a memory device or information element is provided as part of the disposable housing. An electrical contact is made between the memory device and the reusable components to, for example, ensure quality control in the disposable housing, provide information to the patient monitor about the type of sensor, type of patient, type of attachment mechanism or attachment position, information about operating characteristics of the sensor, product manufacture or sale history, distributor history, amount of use, combinations of the same or the like.
[0016] For purposes of summarizing the disclosure, certain aspects, advantages and novel features of the disclosure have been described herein. Of course, it is to be understood that not necessarily all such aspects, advantages or features will be embodied in any particular embodiment of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The following drawings and the associated descriptions are provided to illustrate embodiments of the present disclosure and do not limit the scope of the claims.
[0018] FIG. 1 illustrates an exemplary block diagram of an oximeter system including a sensor and a monitoring instrument, according to embodiments of the disclosure.
[0019] FIG. 2 illustrates a perspective view of the sensor of FIG. 1 , where reusable and disposable components of the sensor are separated according to an embodiment of the disclosure.
[0020] FIGS. 3A-3B illustrate perspective views of the sensor of FIG. 2 , where the components are connected in an assembly/disassembly position, according to an embodiment of the disclosure.
[0021] FIG. 4 illustrates a perspective side view of the sensor of FIG. 2 , where the components are in an attached position, according to an embodiment of the disclosure.
[0022] FIG. 5A-5B illustrate top and bottom perspective views of a detector casing or housing of the reusable component, according to an embodiment of the disclosure.
[0023] FIG. 6A-6B illustrate top and bottom perspective views of an emitter casing or housing of the reusable component, according to an embodiment of the disclosure.
[0024] FIG. 7 illustrates a perspective view of a front holding clip of the disposable component, the clip being capable of mechanically mating with the detector casing of FIG. 5 , according to an embodiment of the disclosure.
[0025] FIG. 8 illustrates a perspective view of the assembly/disassembly clip of the disposable component, the clip being capable of mechanically mating with the emitter casing of FIG. 6 , according to an embodiment of the disclosure.
[0026] FIG. 9 illustrates a top planar view of the disposable component including the front holding clip and the assembly/disassembly clip of FIGS. 7-8 , according to an embodiment of the disclosure.
[0027] FIG. 10A illustrates an exploded view of the disposable component, according to an embodiment of the disclosure.
[0028] FIG. 10B illustrates an exploded view of the reusable component, according to an embodiment of the disclosure.
[0029] FIG. 11 illustrates top planar and side views of component placement of conventional sensors.
[0030] FIG. 12 illustrates top planar and side views of component placement according to an embodiment of the disclosure.
[0031] FIG. 13 illustrates a top down planar view of a disposable sensor, according to an embodiment of the disclosure.
DETAILED DESCRIPTION
[0032] An embodiment of the present disclosure is a sensor with a reusable component and a disposable component. The reusable component generally includes reusable expensive electronic components of a sensor, including, for example, the emitters and detector. In an embodiment, the emitters and the detector are located in respective casings connected by a short flexible circuit. In an embodiment, a disposable component includes mechanically matable portions adapted to mechanically mate with the casings of the reusable component. In an embodiment, the casings of the reusable component mate with the disposable component in a manner that provides an assembly/disassembly state, and an attached state. During the assembly/disassembly state, a caregiver can readily and straightforwardly assemble the sensor by aligning the casings on the reusable component and the mechanical housings of the disposable component and snapping them together. In an embodiment, the alignment is generally vertical in nature and the snapping occurs by lightly pressing on the components while on a flat surface or supported from underneath by, for example, the hand of the assembler. Each detector housing generally vertically accepts the casings; however, one of the casings, such as, for example, the forward housing or clip accepts the casing in such a way as to keep the forward casing generally immobile.
[0033] Disassembly is equally as straightforward, as the caregiver may advantageously lift on the reusable component wire, and the rearward casing extracts from the mechanically mated housing of the disposable element. Continual lifting then similarly extracts the forward casing from the mechanically mated housing of the disposable element. In an embodiment, the flexible circuit between the forward and rearward casing may be reinforced in order to withstand multiple disassembly stresses or forces occurring from the lifting of the reusable wire. In an embodiment, pressing the disposable portion onto a flat surface while lifting the reusable portion aids in the disassembly process.
[0034] The disposable portion includes structures designed to attach the sensor to a measurement site. In an embodiment, the disposable portion comprises a flexible tape having an adhesive side capable of removably adhering to the measurement site. In an embodiment where the disposable portion wraps around a measurement site, the act of bending the flexible circuit advantageously causes the assembly/disassembly clip to recess into the mechanically mated portion of the disposable housing, thereby reducing the likelihood of disassembly during application to a measurement site. In an embodiment, the sensor components are locked together through the longitudinal displacement of the clip with respect to the disposable housing. In such an embodiment, a stop diminishes the capacity of the clip to move vertically, thereby locking it into place. In this embodiment, removing the adhesive from the measurement site and straightening the sensor components unlocks the reusable and disposable components.
[0035] In an embodiment, assembly also necessarily electrically connects electronic components of the disposable portion with those of the reusable portion. In an embodiment, then disposable portion includes an information element or memory device, such as, for example, a resistor, a single wire addressable memory device, such as those EPROMs or EEPROMs commercially available from Dallas Semiconductor, other memory or processing devices, combinations of the same, or the like. The information element may include data accessibly by an attached patient monitor to accomplish quality control, monitor configuration, sensor use monitoring, combinations of the same, or the like.
[0036] Still other advantages of embodiments of the present disclosure include proportionally positioning of the mechanically mating housings to provide for optical alignment between the emitters and detector. Moreover, in embodiments including the disposable tape, the tape may advantageously be scored to assist the caregiver in proper alignment with the body tissue at the measurement site.
[0037] To facilitate a complete understanding of the disclosure, the remainder of the detailed description describes the disclosure with reference to the drawings. Corresponding parts refer to corresponding elements and the leading digit indicates the figure in which that element first appears.
[0038] General Design
[0039] FIG. 1 presents an exemplary block diagram of the components generally found in an oximeter sensor, according to an embodiment of the invention. For example, FIG. 1 shows as oximeter system 100 including sensor 102 , cable 170 , and monitor 172 . The sensor 102 includes one or more emitters 174 for irradiating body tissue with light, and one or more detectors 176 capable of detecting the light after attenuation by the tissue. The sensor 102 also includes an information element 136 such as an EPROM. The sensor 102 also includes a plurality of conductors communicating signals; including emitter drive signal conductors 180 , detector composite signal conductors 182 , and EPROM conductors 184 . According to an embodiment, the sensor conductors 180 , 182 , 184 communicate their signals to and from the monitor 172 through cable 170 .
[0040] Although disclosed with reference to the cable 170 , a skilled artisan will recognize from the disclosure herein that the communication to and from the sensor 106 may advantageously include a wide variety of cables, cable designs, public or private communication networks or computing systems, wired or wireless communications, combinations of the same, or the like.
[0041] The information element 136 may comprise an EPROM, an EEPROM, combinations of the same, or the like. In general, the information element 136 may include a read-only device or a read and write device. The information element may advantageously also comprise a resistor, an active network, or any combination of the foregoing. The remainder of the present disclosure will refer to such possibilities as simply an information element for ease of disclosure.
[0042] The information element 136 may advantageously store some or all of a wide variety of data and information, including, for example, information on the type or operation of the sensor 104 , type of patient or body tissue, buyer or manufacturer information, sensor characteristics including the number of wavelengths capable of being emitted, emitter specifications, emitter drive requirements, demodulation data, calculation mode data, calibration data, software such as scripts, executable code, or the like, sensor electronic elements, sensor life data indicating whether some or all sensor components have expired and should be replaced, encryption information, or monitor or algorithm upgrade instructions or data. The information element 136 may advantageously configure or activate the monitor, monitor algorithms, monitor functionality, or the like based on some or all of the foregoing information. For example, without authorized data accessibly on the information element 136 , quality control functions may inhibit functionality of the monitor. Likewise, particular data may activate certain functions while keeping others inactive. For example, the data may indicate a number of emitter wavelengths available, which in turn may dictate the number and/or type of physiological parameters that can be monitored or calculated.
[0043] FIG. 1 also shows the monitor 172 comprising one or more processing boards 186 communicating with one or more host instruments 188 . According to an embodiment, the board 186 comprises processing circuitry arranged on one or more printed circuit boards capable of being installed in specialized monitoring equipment or distributed as an OEM component for a wide variety of patient monitoring equipment. As shown in FIG. 1 , the board 186 includes a front end signal conditioner 190 , a sensor controller 194 , a digital signal processor or microcontroller 192 , and a memory reader 1102 . In an embodiment, the processor 192 instructs the sensor controller 194 to output one or more drive signals capable of causing the emitters 174 to activate. The front end 190 receives detector output indicating of light from the emitters 174 attenuated by body tissue of the measurement site. The front end 190 conditions the signal and outputs the signal and/or signal data to the processor 192 . The processor 192 executes calculations adapted to determine values and/or indications or physiological parameters, trends of the parameters, alarms based on the parameters or the trends or combinations of trends and/or parameters, or the like. In addition, the reader 1102 is capable of retrieving information stored on information element 136 . The reader 1102 or the processor 192 may advantageously decrypt such information to the extent desired.
[0044] In an embodiment, the host instrument 188 , communicates with the processor 192 to receive signals indicative of the physiological parameter information calculated by the processor 192 . The host instrument preferably includes one or more display devices 196 capable of providing indicia representative of the calculated physiological parameters of the tissue at the measurement site. Such display devices 196 may be controlled by a monitor controller 198 that accepts signals from processor 192 . In an embodiment, monitor controller 198 may also accept signals from user interface 1100 . Such signals may be indicative of various display options for configuring the output to display 196 . In an embodiment, the host instrument 188 may advantageously be capable of displaying one or more of a pulse rate, plethysmograph data, perfusion quality, signal or measurement quality, values of blood constituents in body tissue, including for example, SpCO, functional or fractional SpO.sub.2, or the like. In other embodiments, the host instrument 188 is capable of displaying values for one or more of SpMet, HbO.sub.2, Hb, HbCO, HbMet, Hct, blood glucose, bilirubin, or the like. In still additional embodiments, the host instrument 188 is capable of displaying trending data for one or more of the foregoing measured or determined data. Moreover an artisan will realize from the disclosure herein many display options for the data are available.
[0045] In an embodiment, the host instrument 188 includes audio or visual alarms that alert caregivers that one or more physiological parameters are falling below predetermined safe thresholds, and may include indications of the confidence a caregiver should have in the displayed data. In further embodiment, the host instrument 188 may advantageously include circuitry capable of determining the expiration or overuse of components of the sensor 102 , including for example, reusable elements, disposable elements, or combinations of the same.
[0046] Although disclosed with reference to particular embodiment, an artisan will recognize from the disclosure herein many variations of the instrument 172 . For example, in a broad sense, the instrument 172 accepts data from the sensor 102 , determines values for one or more parameters, trends, alarms or the like, and outputs them to an interface such as a display.
[0047] Sensor Configuration
[0048] FIG. 2 illustrates an embodiment of sensor 102 , having reusable component 204 and disposable component 206 . The components are shown detached. FIG. 3 shows a very similar perspective drawing, but with reusable component 204 and disposable component 206 in their attached, in their assembled state. Returning to FIG. 2 , the reusable component 204 comprises an emitter casing 208 , a detector casing 210 , and a flexible circuit 212 . The emitter casing 208 comprises one or more emission devices operable to emit light at multiple wavelengths, such as red and infrared. Detector casing 210 houses one or more detectors, such as a photodiode detector. In an embodiment, a flexible circuit connects the emitter casing 208 and detector casing 210 . In a preferred embodiment, the flexible circuit is housed in a protective cover and extends beyond the emitter casing 208 . An artisan will understand from the disclosure herein that the emitter and detector electrical components may advantageously be housed in the casings disclosed or simply reversed from the foregoing disclosure. In an embodiment, the flexible circuit 212 and/or cabling extends significantly beyond the casings to advantageously remove any cable attachment mechanisms from the proximity of the tissue site.
[0049] FIG. 2 also shows the disposable component 206 including a base 214 , an assembly/disassembly clip 216 and a front holding clip 218 , the clips each adapted to accept the emitter casing 208 and detector casing 210 , respectively. In the preferred embodiment, front holding clip 218 includes a front stop 220 . Front stop 220 is advantageous for a number of reasons. It helps reduce the likelihood that the reusable component 102 , and in particular detector casing 210 , will slide forward in the front holding clip 218 during assembly or use. In addition, in an embodiment where the stop 220 comprises rubber or other liquid resistant material, the stop 220 provides a liquid resistant connection between the detector casing 210 and front holding clip 218 , reducing the likelihood of sensor contamination and electrical shorts. Rubber or a similar material may be used in an embodiment to compose such a front stop 220 .
[0050] FIG. 3A shows detector casing 210 clipped or snapped into front holding clip 218 with a tip of the casing slid below a portion of the front stop 220 . This allows the front stop 220 to reduce not only horizontal movement of the detector casing 210 , but also helps reduce vertical release of the detector casing unless pulled from, for example, the cable. FIG. 3 also shows the front stop 220 with a generally rounded shape providing a relatively soft material with few, if any, sharp edges. Such an embodiment advantageously reduces damage to a patient or the sensor if the patient tries to scratch body tissue using the edges of the assembled sensor, or if the sensor is dropped, banged against something while worn, or the like. This is particularly useful when used with burn victims or other patients whose skin may damage easily.
[0051] FIG. 3B highlights the ease of assembly. The disposable portion 206 is set on a surface or held in the one hand. The caregiver then aligns a front tip of casing 210 and guides it into front holding clip 218 . This is more a vertical alignment with the front tip snapping below stop 220 . The casing 210 including rounded wings 531 ( FIG. 5 ) that mechanically associate with rounded side walls 739 ( FIG. 7 ). These mechanical structures allow the tip of casing 210 to slide below stop 220 , and snap down into place. Once casing 210 is in place, casing 208 aligns vertically and simply slides down, with tabs 262 ( FIG. 6 ) located sliding into slots 222 ( FIG. 8 ) on either side of assembly/disassembly clip 216 . In an embodiment, the flexible circuit portion 212 between the casings 208 and 210 may bulge slightly.
[0052] FIG. 3B shows the emitter casing 208 after it has been slid onto assembly/disassembly clip 216 . With the reusable sensor component 204 and the disposable sensor component 206 in a generally flat position, the emitter casing 208 remains vertically mobile in slots 222 of assembly/disassembly clip 216 . When the sensor 102 is wrapped around a measurement site 426 , such as a finger, as shown in FIG. 4 , emitter casing 208 slides forward in assembly/disassembly clip 216 due to the tension from flexible circuit 212 and detector casing 210 being substantially immobile in front holding clip 218 . Tabs 262 ( FIG. 6 ) slide away from slots 222 ( FIG. 8 ) and under holding elements 224 ( FIG. 8 ). Holding elements 224 prevent emitter casing 208 from moving vertically or further forward by restricting tabs 262 . As stated before, the tension from flexible circuit 212 when it is wrapped around a measurement site 426 prevents the emitter casing 208 from moving horizontally backwards. The immobility of casing 210 , combined with the tabs 262 sliding out of alignment with slots 222 , effectively secure the reusable sensor component 204 with respect to disposable component 206 , with the emitters appropriately position with respect to the detector. Thus, realignment through release of tension, i.e., removing the sensor from an attachment site and straightening it out, ensure straightforward disassembly of the sensor components. Although shown using tabs 262 and slots 222 , a skilled artisan will recognize from the disclosure herein a wide variety of mechanical mechanisms that ensure reliable attachability when the sensor is applied to the tissue site and straightforward assembly/disassembly when the sensor is removed. For example, one or more detents that snap closed beyond a catch and are released through pinching could be used to secure the reusable portion 104 to the disposable portion 106 .
[0053] As alluded to previously, FIG. 4 depicts sensor 102 as would be seen when in use on a measurement site 426 . In this case, the measurement site is a finger, but other sites such as a toe, ear, wrist or ankle may also work. Disposable component 206 and reusable component 204 are attached, and reusable component 204 is in the assembled and attached position. Longitudinal tension on the flexible circuit 212 from the differing radius between the tape and the circuit has pulled the emitter casing 208 forward, placing tabs 262 under holding elements 224 . FIG. 4 shows that, in an embodiment, emitter casing 208 is rearward with respect to assembly/disassembly clip 216 when in the unattached position ( FIG. 3B ), but the front of emitter casing 208 is forward and in an embodiment, generally flush with assembly/disassembly clip 216 when in the attached position ( FIG. 4 ).
[0054] FIGS. 5A-5B show close up top and bottom perspective views of an embodiment of the detector casing 210 . Electrical contact acceptors 528 are shown as insets on the sides of detector casing 210 . In an embodiment, electrical contact acceptors 528 are located on either side of the detector casing 210 and include conductive material that would be connected to a wire in flexible circuit 212 . Buttons 530 found on either side of the detector casing 210 are, in the preferred embodiment, generally hemispherical protrusions adapted to sit in depressions 738 found on front holding clip 218 (see FIG. 7 ).
[0055] FIG. 7 shows a close up perspective view of an embodiment of the front holding clip 218 , again to show detail less easily seen in smaller figures. While most of the front sensor clip 218 may be made of plastic or some other rigid material, the preferred embodiment has front stop 220 made of rubber as has been discussed. Opening 732 is also shown here and may be a hole through front holding clip 218 or may just be of a generally transparent material that will allow light from the LEDs to enter the tissue at the measurement site and allow light energy to be read by the photodiode. Having window 732 be transparent material will allow the sensor to obtain readings while keeping the LEDs and photodiode from becoming contaminated. Other optical filters or the like could also be housed in window 732 .
[0056] Located inside front stop 220 are conducting prongs 734 . Conducting prongs 734 are adapted to fit into electrical contact acceptors 528 . In an embodiment, the conducting prongs 734 close the circuit with the information element 136 . When the detector casing 210 clips into front holding clip 218 , the conducting prongs 734 slide into electrical contact with acceptors 528 . The completed circuit allows the sensor 102 , and in turn an oximeter, to communicate with information element 136 . Depressions 738 are located on the interior of front holding clip 218 . They are preferably generally hemispherical depressions similar in size to buttons 530 , so as to accept buttons 530 , and hold detector casing 210 in a substantially immobile position relative to front holding clip 218 . Thus, a straightforward snap-in snap-out friction fit is accomplished using buttons 520 and depressions 738 .
[0057] FIGS. 6A-6B show close up top and bottom perspective views of emitter casing 208 . Rear pegs 660 are located on either side of emitter casing 208 . When tabs 262 slide down slots 222 of assembly/disassembly clip 216 , rear alignment pegs 660 slide down behind assembly/disassembly clip 216 . Rear pegs 660 provide further restriction from forward movement, and structural support integrity, once emitter casing 208 has slid into a locking position by hitting rear stops 840 in assembly/disassembly clip 216 (See FIG. 8 ).
[0058] FIG. 8 illustrates a close-up perspective view of a assembly/disassembly clip 216 according to the preferred embodiment. As discussed emitter casing 208 , slides down into assembly/disassembly clip 216 with tabs 262 passing through slots 222 and rear pegs 660 passing behind assembly/disassembly clip 216 . As emitter casing 208 slides forward due to pull from application to a user, tabs 262 generally restrict over-forward movement or any vertical movement by abutting holding elements 224 . Rear pegs 660 also generally abut rear stops 840 . Assembly/disassembly clip 216 also has a window 842 that is substantially similar to window 732 on the front holding clip 218 .
[0059] FIG. 9 shows a top down view of the disposable sensor element. As shown in FIG. 9 , the assembly/disassembly clip 216 and the slots 222 that allow vertical entry of the tabs 262 and the emitter casing 208 . Moreover, FIG. 9 shows windows 842 and 732 in assembly/disassembly clip 216 and front holding clip 218 , respectively. FIG. 9 also shows windows 944 and 946 . Windows 944 , 946 are included in the base 214 . Like the openings 732 , 842 , windows 944 , 946 may either be holes through base 214 , or they may be of a material allowing free light transmission. Windows 944 , 946 generally align with openings 732 and 842 to provide optical access to the measurement site for the emitters and detectors of the sensor. FIG. 9 also shows the contact prongs 734 on the insides of front holding clip 218 . The contact prongs 734 connect the reusable sensor component 204 to information element 136 , which may be variously utilized such as for storing information relating to the sensor's manufacturer or the like.
[0060] Manufacture
[0061] FIG. 10A illustrates an exploded view of an embodiment of disposable sensor component 206 . As shown in FIG. 10A , disposable sensor component 206 comprises a plurality of layers. For example, disposable sensor component 206 includes a base tape 1038 . This base tape 1038 is preferably transparent polyethylene approximately 0.001 inches thick. Such material can be purchased from various sources, such as Product Number 3044 from Avery Dennison Medical of 7100 Lindsey Dr., Mentor, Ohio, 44060. As with all dimension recitations herein, an artisan will recognize from the disclosure herein that the dimensions of a particular layer may advantageously be redesigned according to various design desires or needs, and layers may be added or combined without departing from the scope of the present disclosure.
[0062] A second layer comprises a tape or web layer 1040 . This layer is preferably white polypropylene also approximately 0.001 inches thick. One potential source for this material is Scapa North America, 540 North Oak Street, Inglewood, Calif., 90302, specifically product number P-341. Tape layer 1040 also has windows 1054 that allow light energy emanating from the sensor emitters to pass through this layer to the measurement site 426 and also allows the light to pass through to the detector. The windows 1054 may be holes, transparent material, optical filters, or the like. In the preferred embodiment, base tape 1038 does not have windows 1054 . Base tape 1038 is preferably generally clear as discussed above. This allows light to pass through the tape from the sensor, while also generally reducing contamination of the sensor components. Disposable component 206 also includes clip 218 and assembly/disassembly clip 216 . In an embodiment, information element 136 resides in a depression or slot within clip 218 , preferably affixed in place by adhesives and/or mechanical structure. In an embodiment, a polyester film layer 1042 sandwiches the clips 216 , 218 in place. In an embodiment the polyester film layer 1042 is generally clear and approximately 0.003 inches thick. Polyester film layer 1042 also includes slots 1044 to allow the vertical elements of assembly/disassembly clip 216 and front holding clip 218 to protrude therefrom and to allow polyester film layer 1042 to sit relatively flatly against the bases of assembly/disassembly clip 216 and front holding clip 218 . Front stop 220 may be connected to the vertical elements of front holding clip 218 with polyester film layer 1042 therebetween.
[0063] The disposable portion 204 also includes light-blocking layer 1046 , preferably made of metalized polypropylene approximately 0.002 inches thick. This is a commercially available product available, for example, as Bioflex™ RX48P. Light-blocking layer 1046 has cut-outs 1048 adapted to accept assembly/disassembly clip 216 and front holding clip 218 . Light-blocking layer 1046 increases the likelihood of accurate readings by preventing the penetration to the measurement site of any ambient light energy (light blocking) and the acquisition of nonattenuated light from the emitters (light piping). Above light blocking layer 1046 is an opaque branding layer 1047 also having cut-outs 1048 . This branding layer may advantageously comprise manufacturer's logos, instructions or other markings. Disposable sensor component 206 also comprises face tape 1050 . This face tape 1050 is preferably a clear film approximately 0.003 inches thick and may be obtained commercially through companies such as 3M (product number 1527ENP), located in St. Paul, Minn., 55144. Face tape 1050 has cut-outs 1052 adapted to accept assembly/disassembly clip 216 and front holding clip 218 .
[0064] Additional Advantages
[0065] FIG. 11 illustrates a disposable sensor highlighting issues relating to sensor positioning. Generally, when applying the sensor of FIG. 11 , a caregivers will split the center portion between the emitter and detector around, for example, a finger or toe. This may not be ideal, because as shown, it places the emitter 174 and detector 176 in a position where the optical alignment may be slightly or significantly off.
[0066] FIG. 12 illustrates an embodiment of the disposable component 206 including scoring line 1258 . Scoring line 1258 is particularly advantageous, because it aids in quick and proper placement of the sensor on a measurement site 426 . Scoring line 1258 lines up with the tip of a fingernail or toenail in at least some embodiments using those body parts as the measurement site. FIG. 12 also illustrates the disposable component 206 where the distance between the windows 944 , 946 is purposefully off center. For example, in an embodiment, the clips 216 and 218 will position the sensor components off center by an approximate 40%-60% split. A scoring line 1258 preferably marks this split, having about 40% of the distance from window 946 to window 944 as the distance between window 946 and the scoring line 1258 . This leaves the remaining approximately 60% of the distance between the two windows 944 , 946 as the distance between scoring line 1258 and window 944 .
[0067] Scoring line 1258 preferably lines up with the tip of the nail. The approximately 40% distance sits atop a measurement site 426 , such as the figure shown in a generally flat configuration. The remaining approximately 60% of the distance, that from the scoring line 1258 to window 944 , curves around the tip of the measurement site 426 and rests on the underside of the measurement site. This allows windows 944 , 946 —and thus in turn detector 176 and emitter 174 —to optically align across measurement site 426 . Scoring line 1258 aids in providing a quick and yet typically more precise guide in placing a sensor on a measurement site 426 than previously disclosed sensors. While disclosed with reference to a 40%-60% split, the off center positioning may advantageously comprise a range from an about 35%—about 65% split to an about 45%—about 55% split. In a more preferred embodiment, window 944 to scoring line 1258 would comprise a distance of between about 37.5% and about 42.5% of the total distance between window 944 and 946 . In the most preferred embodiment, the distance between window 944 and scoring line 1258 would be approximately 40% of the total distance between window 944 and window 946 , as is illustrated in FIG. 12 . With a general 40%-60% split in this manner, the emitter and detector should generally align for optimal emission and detection of energy through the measurement site.
[0068] FIG. 13 illustrates a disposable sensor containing many of the features discussed in this disclosure. Based on the disclosure herein, one of ordinary skill in the art may advantageously fix the components discussed herein to form a disposable sensor without moving beyond the scope of the present disclosure.
[0069] Although the sensor disclosed herein with reference to preferred embodiments, the disclosure is not intended to be limited thereby. Rather, a skilled artisan will recognize from the disclosure herein a wide number of alternatives for the sensor. For example, the emitter and detector locations may be in the opposite housings from what was discussed here. It is also possible that the assembly/disassembly clip and sensor clip would be reversed in relation to the casings into which they clip. Additionally, other combinations, omissions, substitutions and modifications will be apparent to the skilled artisan in view of the disclosure herein. Accordingly, the present disclosure is not intended to be limited by the reaction of the preferred embodiments, but is to be defined by reference to the appended claims.
[0070] Additionally, all publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference. | 4y
|
TECHNICAL FIELD
[0001] The present invention pertains to auxiliary power supply systems, and more particularly to auxiliary power supply systems having a plurality of energy storage devices where at least one of the energy storage devices stores inertial energy.
BACKGROUND OF THE INVENTION
[0002] There are numerous applications that exist for auxiliary power sources that can operate in the event that conventional utility power has been interrupted. For example, computer systems need to be isolated from short-term drop-outs and switching noise that commonly occur on utility power lines. Homeowners require backup systems to power furnaces or air conditioners. Office buildings also require backup power to maintain various systems in the event of a utility power outage. Hospitals are yet another example where auxiliary power is critical to maintaining life support equipment.
[0003] One type of auxiliary power source includes large multi-cell DC batteries that typically have a limited backup time measured in units of hours depending on the size of the connected load. Another type of auxiliary power source utilizes electromechanical systems that include an engine connected to an electrical generator. These electromechanical devices require fuel to keep the engine rotating resulting in a system that produces harmful exhaust gases. These systems may also generate a significant amount of noise undesirable for many situations. The amount of time that any of these systems may operate without being recharged or refueled is relatively limited.
[0004] What is needed is an auxiliary power supply that can supply power for an extended period of time without the detriment of both noise and air pollutants, and the expense of costly fuels. The embodiments of the subject invention obviate the aforementioned difficulties by providing a highly efficient auxiliary power supply that operates from the kinetic energy stored in an inertial energy storage device.
BRIEF SUMMARY
[0005] A flywheel is a heavy rotating disk used as a repository for angular momentum. Flywheels can be used by small motors to store up energy over a long period of time and then release it over a shorter period of time, temporarily magnifying its power output for that brief period. The kinetic energy stored in a rotating flywheel is represented by the equation
[0000] E= ½ Iω 2
[0000] where I is the moment of inertia of the mass about the center of rotation and ω (omega) is the angular velocity in radian units. A flywheel is more effective when its inertia is larger, as when its mass is located farther from the center of rotation either due to a more massive rim or due to a larger diameter. The similarity of the above formula will be noted to that of the kinetic energy formula E=½mv 2 , where linear velocity v is comparable to the rotational velocity and the mass is comparable to the rotational inertia.
[0006] In accordance with the embodiments of the invention an auxiliary power supply system supplies electrical power to an associated load and includes a power monitoring device that can regulate the transmission of electrical power to the associated load. An associated external power supply, such as power supplied from conventional power lines, is also communicated to deliver power to the associated load through the power monitoring device. The auxiliary power supply system may also include first and second energy storage devices communicated to the power monitoring device, wherein the power monitoring device cycles between supplying auxiliary power from the first energy storage device and the second energy storage device.
[0007] In one embodiment of the subject invention the first energy storage device may store electrical energy and may comprise a battery having one or more cells. Additionally, the second energy storage device may store a different type of energy from that of the first energy storage device, which may be inertial energy.
[0008] One aspect of the embodiments of the subject invention may include a generator, which may be connected between the second energy storage device and the power monitoring device. The generator may be a motor generator operable to function in one mode as an electrical generator and in another mode as an electrical motor.
[0009] Another aspect of the embodiments of the subject invention may include a transmission operatively connected between the second energy storage device and the power monitoring device, wherein the transmission may include a gearbox having one or more planetary gears.
[0010] In yet another aspect of the embodiments of the subject invention may the second energy storage device may include a frame, an inertial energy storage portion having a fixed mass M operatively connected to the frame and an output shaft rotatably connected with respect to the frame, the output shaft being coupled to the inertial energy storage portion, which may include one or more flywheels having a plurality of disks rollingly connected with respect to each of the flywheels.
[0011] In one embodiment the flywheels may have an offset center of gravity with respect to an axis of rotation caused by the placement and/or movement of the disks within the flywheels respectively.
[0012] One aspect of the auxiliary power supply system according to the embodiments of the subject includes a power monitoring device that may cycle between supplying auxiliary power from the first energy storage device and the second energy storage device when the second energy storage device falls below a threshold level of inertial energy and more particularly below a threshold rotational speed.
[0013] Still another aspect of the auxiliary power supply system according to the embodiments of the subject includes a first energy storage device that is operable to recharge the second energy storage device.
[0014] According to the embodiments of the subject invention an inertial energy storage device may include a frame, an output shaft rotatably connected with respect to the frame, an inertial energy storage portion having a fixed mass M coupled to the output shaft, wherein the inertial energy storage portion includes, at least a first flywheel fixedly connected with respect to the output shaft and a plurality of disks rollingly connected with respect to the at least a first flywheel.
[0015] One aspect of the inertial energy storage device according to the embodiments of the subject invention includes at least a first flywheel having one or more slots fashioned on an interior of the at least a first flywheel that respectively receive the disks.
[0016] Another aspect of the inertial energy storage device according to the embodiments of the subject invention includes at least a first flywheel that comprises at least a first pair of flywheels, where each of the plurality of disks includes an axle fixedly connected to the disks respectively, wherein the axles are rollingly connected with respect to the at least a first pair of flywheels.
[0017] Yet another aspect of the inertial energy storage device according to the embodiments of the subject invention includes a plurality of brake members fixedly connected with respect to at least a first flywheel for arresting motion of the rollingly connected disks.
[0018] Still another aspect of the inertial energy storage device according to the embodiments of the subject invention includes the plurality of flywheels that is phase shifted with respect to the remaining flywheels.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic representation of a power supply system for supplying power to a load according to the embodiments of the invention.
[0020] FIG. 2 is a perspective view of an inertial energy storage device according to the embodiments of the invention.
[0021] FIG. 3 is an end view of the flywheel of the inertial energy storage device according to the embodiments of the invention.
[0022] FIG. 4 is a perspective view of a disk according to the embodiments of the invention.
[0023] FIG. 5 is a side view of a flywheel according to the embodiments of the invention.
[0024] FIG. 6 is a side view of a flywheel according to the embodiments of the invention.
[0025] FIG. 6 a is a side view of a flywheel according to the embodiments of the invention.
[0026] FIG. 7 is a schematic representation of a power monitoring device for controlling the supply of power to a load according to the embodiments of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Referring now to the drawings wherein the showings are for purposes of illustrating embodiments of the invention only and not for purposes of limiting the same, FIG. 1 shows an auxiliary power supply system 1 for supplying electrical power as depicted within the dashed lines. The power supply system 1 may comprise a series of subsystems 2 interconnected to function in the presently described manner. The subsystems 2 may include a first energy storage device 4 , which may be an inertial energy storage device 4 ′. By inertial energy storage device it is meant a repository that stores energy in the form of a moving mass. The inertial energy storage device 4 ′ may be interconnected to an electrical generator 8 through a transmission 6 , which in one embodiment may be a planetary gear box 6 ′. The inertial energy storage device 4 ′ may alternatively be connected to the electrical generator 8 via other torque-speed converting means including but not limited to torque converters and fixed ratio gear boxes. However, any means may be used to connect the inertial energy storage device 4 ′, the transmission 6 and the generator 8 as is appropriate for use with the embodiments of the subject invention. Power may be drawn from the inertial energy storage device 4 ′ as during a power outage and directed to the electrical generator 8 . The generator 8 will produce electrical power for supplying energy to a second energy storage device 13 and/or a designated load depicted generally at 15 . The second energy storage device 13 may comprise one or more electrical energy storage cells as may be found in a battery 13 ′, of which the battery 13 ′ may also be connected to the load 15 .
[0028] In this manner, electrical power may be supplied by the power supply system 1 to a load 15 from the battery 13 ′ and/or the generator 8 . In other words, power supplied to the load 15 may be drawn from either of the first or second energy storage devices. The battery 13 ′ may be connected in parallel to a primary power source 18 . Such power sources 18 are readily known in the art and may include electrical energy supplied from a utility power company through conventional transmission lines. In the event that primary power has been interrupted, a power monitoring device 22 may be incorporated to switch power sources thus maintaining a continuous supply of power to the load 15 . In one embodiment, the power monitoring device 22 may engage the battery 13 ′ and/or the generator 5 in regulating the flow of energy between the devices and the associated load 15 . In particular, the power monitoring device 22 may monitor the amount of energy remaining in each source and selectively engage the battery 13 ′ and/or the generator 5 to regulate the flow of energy from the power supply system 1 . Accordingly, the power supply system 1 may draw power from one energy storage device and charge the other energy storage device, while supplying power to the load 15 , as will be discussed in detail in a subsequent paragraph.
[0029] With reference now to FIG. 2 , the inertial energy storage device 4 ′ may include a series of flywheels 20 mounted within a flywheel housing 21 , where each flywheel 20 has a characteristic mass M. The flywheels 20 may be fixedly connected to a shaft 23 extending through a center of the flywheel 20 . One shaft 23 may connect all of the flywheels 20 together into a single rotating unit. Accordingly, the single rotating unit will have a mass equal to the sum of the masses of the individual components, i.e. the flywheels 20 and shaft 23 . The shaft 23 may subsequently be rotatably connected with respect to the flywheel housing 21 via bearings 25 . In one embodiment, the bearings 25 may be magnetic bearings 25 ′, which incorporate non-contacting technology. The shaft 23 may be received within the magnetic bearings 25 ′ and may rotate therein without substantial frictional losses thereby helping to preserve the inertial energy stored in the mass of the flywheels 20 for conversion by the generator 8 as will be described further in a subsequent paragraph. While the aforementioned embodiment discusses the use of bearings 25 and in particular magnetic bearings 25 ′, it is to be construed that any means may be chosen to rotatably connect the shaft 23 to the flywheel housing 21 that significantly limits the loss of inertial energy stored in the flywheels 20 . In addition to the use of magnetic bearings 25 ′, the housing 21 may be evacuated of air and/or other gases to limit losses due to windage. A person of ordinary skill in the art will understand the resistance caused by an object moving through ambient conditions, and more specifically the density of air at a particular elevation level. Accordingly, the housing 21 may be hermetically sealed substantially preventing air from entering the vacuum of the housing 21 .
[0030] With continued reference to FIG. 2 and now to FIGS. 3 and 4 , the flywheels 20 may be laterally spaced along the length of the shaft 23 in pairs or sets 30 each containing two flywheels 20 . Each set 30 may function as supports for a plurality of disks 50 rotatably connected between the pair of flywheels 20 . The disks 50 may each be fixedly mounted to an axle 52 that spans the distance between the pair of flywheels 20 . As such, the length of the axles 52 may correspond to the spacing of the flywheels 20 . Any length may be selected with sound engineering judgment as is appropriate for use with the embodiment of the subject invention. It will be readily seen that the disks 50 add to the mass of the inertial energy storage device 4 ′ thereby increasing the amount of inertia that can be stored in the power supply system 1 . In this manner, each pair of flywheels 20 may include a set of disks 50 connected therebetween. In one embodiment, the inertial energy storage device 4 ′ may include eight (8) flywheels thus comprising four (4) pairs or sets of flywheels 20 . To facilitate rotation of the disks 50 between the sets of flywheels 20 , the flywheels 20 may be fashioned having one or more races 60 onto which the respective ends 53 of the axles 52 may roll as will be discussed in detail below. In this manner, the disks 50 are connected to rotate with respect to the flywheels 20 and the shaft 23 . The disks 50 may be fashioned having guide ends 55 that align the axles 52 onto their respective races 60 . In one embodiment, the guide ends 55 may be tapered to keep the disk from moving laterally with respect to the flywheels 20 .
[0031] With continued reference to FIGS. 3 and 4 and now to FIGS. 5 and 6 , a flywheel 20 may be constructed having a plurality of slots 62 fashioned on an interior of the flywheel 20 . The slots 62 may have a generally elliptical shape, having a major and a minor axis, with curved surfaces that may function to receive an axle 52 . In this manner, the curved surfaces of the slots 62 may form races 60 on which a disk 50 may rotate. In one embodiment, the flywheels 20 each include seven (7) slots 62 spaced equidistantly around the interior of the flywheel 20 and seven (7) corresponding disks 50 . While the current embodiment describes the flywheels 20 having seven (7) slots 62 , any number of slots 62 and any angular orientation of the slots 62 may be included as are appropriate for use with the embodiments of the subject invention. As the flywheels 20 rotate with the shaft 23 , the disks 50 may translate or roll along the races 60 as the flywheels 20 rotate. In other words, upon reaching a specific point in the cycle of the rotating flywheel 20 , a disk 50 will be pulled downward by gravity thus initiating the rotation of that particular disk 50 . In this manner, gravity causes the disks 50 to move downward in an arcuate trajectory as guided by the configuration of the slots 62 . For example, FIG. 6 depicts point masses M 1 -M 7 in each of the respective slots 62 representing each of the disks 50 . It is to be understood that the point masses represent each of the disks respectively and are used in the examples for illustrative purposes. A disk 50 , represented by point mass M 1 , is positioned at one end of the corresponding slot 62 . It will be readily seen that as the flywheel 20 is rotating in the direction R 1 , work is being done against gravity by the flywheel 20 . The disk 50 in this position is stationary with respect to the flywheel 20 . As the flywheel 20 continues to rotate, the slot 62 crosses a horizontal plane. This position is depicted by point mass M 2 , representing another disk 50 . As such, gravity pulling the disk 50 downward, initiates the movement of the disk 50 along the arcuate trajectory A as guided by the slot 62 . The disk 50 continues along this trajectory, exemplified by point mass M 3 , until it reaches the distal end of the slot 62 , shown by point mass M 4 . Once the disk 50 reaches this position momentum continues to rotate the disk 50 seated in the vertex of the slot 62 until the angle of the slot 62 once again allows gravity to pull the disk 50 downward further rotating the disk 50 in the direction R 2 . It is noted here that the races 60 and the guides 55 of the axle 52 may be fashioned having smooth surfaces so as to minimize frictional losses between the axle 52 and the flywheel 20 . In one embodiment, the surface finish of the slots 62 and the guides of the axles 52 may be substantially 15. However, any surface finish may be used that minimizes frictional losses as chosen with sound engineering judgment. Thus, as the flywheel 20 rotates, in the direction R 1 , each of the successive disks 50 will be drawn upward by the flywheel 20 through approximately one quadrant of the cycle and downward by gravity through the remainder of the cycle. It will be appreciated by a person of ordinary skill in the art that rotation of the flywheels 20 will produce a centrifugal force that drives the disks 50 radially outward. If the radially outward force is sufficiently large enough, the disks 50 will be prevented from rolling along their respective races 60 . As such, a rotational speed of the flywheels 20 may be chosen such that the centrifugal force against the disks 50 is small enough to allow the disks 50 to roll through their respective slots 62 . In one embodiment, the designated rotational speed of the flywheels may be less than 30 RPMs. More specifically, the designated rotational speed may be between 20 and 30 RPMs and more particularly may be substantially 25 RPMs.
[0032] With reference to FIGS. 4 through 6 a , as mentioned above, disk 50 upon reaching the distal end of the slot 62 , as exemplified by point mass M 4 , may spin in place until the flywheel 20 rotates further to the point where the disk 50 once again is drawn by gravity along the slot 62 . A friction reducing device such as a bearing 67 may be placed proximate to the end 65 of the slot 62 so as to receive the guide 55 of the disk 50 . In this manner, as the disk 50 is rotating in the position at the end 65 of the slot 62 the bearing 67 may receive the guide 55 thereby allowing the disk 50 to spin with reduced friction. It is to be construed that each end 65 of each of the slots 62 on all of the flywheels 20 may include bearings 67 positioned in the aforementioned manner. However, any configuration bearings 67 with respect to the ends 65 of the slots 62 may be chosen with sound engineering judgment. The bearings 67 may be roller bearings having multiple bearing members or contacting surfaces for receiving the respective guides 55 of the disks 50 . Alternatively, the bearings 67 may be magnetic bearings or any other type or configuration of friction reducing device as is appropriate for use with the embodiments of the subject invention. FIG. 6 a depicts the bearings 67 fastened onto a side of the flywheel 20 having a retainer 68 . Two bearings 67 may be included per flywheel 20 ; one on each side for each of the respective slots 62 . It is noted that the depicted configuration of bearing 67 is for illustrative purposes and as such other configurations, placement and installation of the bearings 67 may be utilized without departing from the intended scope of coverage for the embodiments of the subject invention.
[0033] With continued reference to FIG. 5 , the flywheels 20 may include brakes 70 which arrest the rotating motion of the disks 50 . In one embodiment, the brakes 70 may be respectively affixed proximate to the end of the slots 62 at the rim 24 of the flywheel 20 . The brake 70 may comprise a friction pad 70 ′ that engages the axle 52 . As mentioned above, at various points in the cycle, the disks 50 will be rolling along each respective race 60 as the flywheels 20 rotate. When the disk 50 reaches the end of the slot 62 at the rim 24 of the flywheel, it contacts the brake 70 bringing the rotating disk 50 to a stop thereby translating the inertial energy of the rotating disk 50 to the flywheel 20 . The disk 50 will remain stationary through that portion of the cycle until it reaches an angle that once again allows the disk 50 to begin rotating along the slots 62 in a manner as previously described. Thus, it will be readily seen that each successive rotating disk 50 will transfer its inertia at prescribed intervals correlating to the configuration of the slots 62 . In one embodiment, a disk 50 may contact each respective brake 70 at approximately every 51.4 degrees throughout the revolution of one set of flywheels 20 . Each set of flywheels 20 may be substantially identical to the others. However, each set of flywheels 20 may be shifted in their angular orientation around the shaft 23 . In one embodiment, the sets of flywheels 20 may be phase shifted approximately 12.8 degrees with respect to each other thus enabling at least one disk 50 to contact its respective brake 70 every 12.8 degrees continuously throughout each revolution of the shaft 23 . While the present embodiment describes the power supply system 1 having four sets of flywheels and seven disks per set of flywheels, it is to be construed that any number of the flywheels and any number of disks may be used in the inertial energy storage device 4 ′ as chosen with sound engineering judgment. In this manner, all of the disks 50 may be substantially equidistantly spaced around the circumference of the shaft 23 . However, any radial position or spacing of the disks 50 around the circumference of the shaft 23 may be chosen as is appropriate for use with the embodiments of the subject invention.
[0034] As the flywheels 20 rotate, output power is available from the shaft 23 proportionate to the speed of rotation of the shaft 23 and the mass of the flywheels 20 of the inertial energy storage device 4 ′. As previously mentioned, the inertial energy storage device 4 ′ may be connected, via shaft 23 , to a transmission 6 thereby conveying the inertial energy stored in the flywheels 20 to a generator 8 for converting the inertial energy into electrical energy. In one embodiment, the transmission 6 may function to convert the output speed, and consequently the torque as well, of the shaft 23 to a speed suitable for driving the rotor of the generator 8 , which may range from 1500 to 2500 RPMs. In this manner, the transmission 6 may comprise a gear reducer having one or more sets of planetary gears, not shown. However any gear reducing means for converting the speed and torque of the inertial energy storage device may be chosen with sound engineering judgment.
[0035] With continued reference to FIGS. 1 and 2 , the output of the transmission 6 or planetary gear box 6 ′ may be coupled to the generator 8 . In one embodiment, the generator 8 may be a reversible motor-generator 8 ′, which functions as a motor or a generator depending on the particular mode of operation as will be discussed in detail in the following paragraphs. The motor-generator 8 may be an AC or DC generating device having a rotor and a stator, neither shown, that work in conjunction with each other to produce either an electrical power output or mechanical power output having parameters of angular velocity and torque. The motor-generator device has two principal components: a field winding and an armature winding. A field, or excitation, winding is a coil or group of coils through which an electrical current is passed. The excitation current sets up a magnetic field in the vicinity of the coil and includes what is commonly referred to as “lines of magnetic flux”. An armature winding is a coil, separate from the excitation coil, which cuts through the lines of magnetic flux created by the field winding and excitation current. This cutting action results in an induced electromotive force (EMF) on the armature winding according to well-established principles of electromagnetic theory. When an electrical load is connected to the armature winding, an electrical current will be made to flow because of the induced EMF. Thus an output voltage and current are generated by the generator 8 when mechanical input is applied to the rotor. As such, the rotor is the rotating part of the motor-generator 8 ′ that may be coupled to the output of transmission 6 . As the rotor turns within the magnetic fields of the stator, current flow will be induced in the windings of the rotor for use by the power supply system 1 . In the opposite mode of operation, current may be supplied to the armature winding thus producing a torque that drives the rotor. In that the operation of motors and generators are well known in the art, no further explanation will be offered at this time.
[0036] With reference again to FIGS. 1 and 7 , the power supply system 1 may include a power monitoring device 22 as previously mentioned, which may incorporate a switchgear 34 for switching and controlling power through the power supply system 1 . The switchgear 34 may be an automatic type switchgear that transfers power to the load 15 between an external power source 18 and the power supply system 1 . One example of an external power source 18 may be power delivered over standard transmission lines from a local power company. When power from the external power source 18 is interrupted, the power monitoring device 22 may sense the interruption and switch power to the load 15 from the external power source 18 to the power supply system 1 . In this manner, the power supply system 1 may be alternate or auxiliary source of power ready for immediate use in the event of a power outage. Thus, the power monitoring device 22 may sense and automatically transfer the connection of power to the load 15 between an external power source 18 and the power supply system 1 .
[0037] With reference to FIG. 7 , in one embodiment, the switchgear 34 may comprise one or more components including a power switching device 36 to shift the load circuits to and from the power supply system 1 and a transfer controller 39 to monitor the status of the external power source 18 and the power supply system 1 . The power switching device 36 may utilize a “circuit breaker” or a “contactor” type switch to transfer the loads between the external power source 18 and power supply system 1 . In one embodiment, solid state circuitry may be incorporated, such as that found in Silicon Controller Rectifiers (SCR). However any type and/or configuration of devices may be used to transfer power between the power supplies. As the load 15 may require a specific type electrical power, for example DC power as opposed to AC power, the power from the generator 8 may need conditioned or rectified. For example, the load 15 may require 24 VDC power whereas output from the generator 8 may provide AC power. Accordingly, the power supply system 1 may include power converters 38 for conditioning the power. Additionally, the magnitude and frequency of the power may also need converted. Power converters 38 may include transformers, rectifiers, variable frequency devices and/or other solid state circuitry, e.g. DC to DC power converters, that functions to condition the power as needed.
[0038] With continued reference to FIG. 7 , the transfer controller 39 may provide logic based circuitry that tells the power switching device 36 under what conditions the power connection is to be switched between the sources of electrical power. Logic-based processors such as microprocessors may be used to perform logic functions based on feedback signals generated by sensors within the power supply system 1 . In one embodiment, power supply system 1 may utilize torque and/or speed sensors that monitor the speed of the shaft 23 . Additionally, the power supply system 1 may incorporate current and/or voltage sensors that detect power levels in the external power source 18 , the load 15 and the output from the generator 8 and the battery 13 ′. It is to be construed that any type, quantity and configuration of sensors may be chosen with sound engineering judgment for use with the embodiments of the subject invention. In this manner, the transfer controller 39 may provide supervisory circuits to constantly monitor the condition of the power sources and thus provide the intelligence necessary for the switchgear 34 to adjust the power output accordingly.
[0039] With reference again to FIG. 1 , the second energy storage device 13 may be a multi-cell battery 13 ′. The battery 13 ′ may have sufficient storage capacity to supply power for a given period of time up to a maximum load. Power for the load 15 may be supplemented by inertial energy converted from the inertial energy storage device 4 ′. Each of these two energy storage devices 4 ′, 13 ′ may function in conjunction to provide an auxiliary source of power to the load 15 as regulated by the power monitoring device 22 , which will be discussed further in a subsequent paragraph. In one embodiment, the power supply system 1 may be configured to supply power at a rate of up to 30 kW to a prescribed load.
[0040] With reference once again to FIG. 1 , the operation of the power supply system 1 will now be described. The power supply system 1 may be connected to a load 15 , such as that found in residential or commercial buildings. Well known electrically operated devices may be connected to draw power from the power supply system 1 including for example copiers, lights, compressors, heating units and the like. External source power 18 may also be connected to the load 15 and may function as a primary source of electrical power for use by the load devices. In one embodiment, the external power source 18 may be connected to the load 15 through the power monitoring device 22 in a manner consistent with the above described embodiments of the subject invention. When the power flow from the external power source 18 is interrupted, the power monitoring device 22 may sense the drop in voltage and/or current and automatically switch the connection of the power to the load 15 from the external power source 18 to the power supply system 1 .
[0041] In one embodiment, when supply power for the electrically operated devices, i.e. load 15 , is switched to the power supply system 1 , the load 15 may be directly connected to battery 13 ′ through a power converter 38 or any power conditioning circuit as may be required. For example, power from the battery 13 ′ may be drawn as DC electrical power and converted to 115 VAC power by a transformer and other circuitry for use by the load 15 . While power is being supplied to the load 15 via battery 13 ′, electrical power may be supplemented by the inertial energy storage device 4 ′ as converted by the generator 8 and supplied to the load 15 in a parallel circuit as controlled by the power monitoring device 22 . Therefore power from each of the first and second energy storage devices 4 ′, 13 ′ may be electrically communicated to the power monitoring device 22 . In this manner, electrical power from the power supply system 1 may be supplied from two dissimilar sources of stored energy, namely an electrical energy source and a kinetic energy source. It will be realized by a person of ordinary skill in the art that as kinetic energy from the flywheels 20 is drawn from the inertial energy storage device 4 ′ the rotational speed of the shaft 23 and the flywheels 20 will decrease thereby reducing the inertial energy stored therein. The power monitoring device 22 may sense the decrease in rotational speed and automatically shi ft the supply of power to the load 15 from both the battery 13 ′ and the inertial energy storage device 4 ′ to power supplied from only the battery 13 ′. Thus, the load 15 will temporarily be supplied by electrical power from a single source of stored energy. In conjunction, the power monitoring device 22 may shift operating modes of the motor-generator 8 ′ from converting the inertial energy stored in the flywheels 20 to supplying energy from the battery 13 ′ to speed up the flywheels 20 . In this mode of operation, power from the battery 13 ′ may supply power not only to the load 15 but also to the motor-generator 8 ′ thus recharging the inertial energy storage device 4 ′. When the inertial energy storage device 4 ′ reaches its designated rotational speed, the power monitoring device 22 may once again shift operating modes of the motor-generator 8 ′ thereby supplying power to the load 15 from both sources of stored energy 4 ′ 13 ′. The frequency at which the power monitoring device 22 shifts between operating modes may depend on a threshold rotational speed of the shaft 23 of the inertial energy storage device 4 ′. In one embodiment, the threshold speed of shaft 23 may be within a range equal to the designated rotational speed less 5 RPMs. In other words, the threshold speed may be between 20 and 25 RPMs. More particularly, the threshold speed may be substantially 23 RPMs. The threshold speed represents a minimum value that the inertial energy storage device 4 ′ may rotate while operating the motor-generator 8 ′ in generator mode. Accordingly, the frequency of switching between modes of operation may depend on the load 15 . A larger load may draw energy from the power supply system 1 at a faster rate. The converse also holds true.
[0042] In summary, the power supply system 1 may control the supply of power to the load 15 from between two sources of stored energy 4 ′ 13 ′. The power monitoring device 22 may shift between modes of operation where both sources of stored energy, i.e. the battery 13 ′ and inertial energy storage device 4 ′, supply power to the load 15 to one source of stored energy, i.e. the battery 13 ′, supplies power to the load 15 , As the inertial energy storage device 4 ′ drops to a minimum threshold energy level, the power monitoring device 22 triggers the operating modes of the motor-generator 8 ′. When the motor-generator 8 ′ is shifted into motor mode, power supplied to the motor-generator 8 ′ from the battery 13 ′ will produce an output torque transferred through transmission 6 to the inertial energy storage device 4 ′ until the shaft 23 is rotating again the designate operating speed. When the motor-generator 8 ′ is shifted into generator mode, power from the inertial energy storage device 4 ′ is supplemented with power from the battery 13 ′ to meet the demands of the load 15 . Thus, an efficient power supply system 1 is provided that can supply electrical power for an extended length of time during a power outage.
[0043] It will be appreciated by persons of ordinary skill in the art that the power supply system 1 contains a finite amount of stored energy. Once the subject power outage has ended, the power supply system 1 may be configured to draw power from the external power source 18 to recharge the battery 13 ′ and/or the inertial energy storage device 4 ′ for use at a future time. In this manner, the power supply system 1 maintains a constant state of readiness to supply power in the event of a power outage.
[0044] The invention has been described herein with reference to the preferred embodiment. Obviously, modifications and alterations will occur to others upon a reading and understanding of this specification. It is intended to include all such modifications and alternations in so far as they come within the scope of the appended claims or the equivalence thereof. | 4y
|
[0001] This application is a continuation of application Ser. No. 10/731,068, filed on Dec. 8, 2003, which is a continuation of application Ser. No. 09/903,831, filed on Jul. 11, 2001, entitled “Bypass Grafting Method”, which application is a continuation of abandoned application Ser. No. 09/111,062 filed Jul. 7, 1998, which is a continuation of application Ser. No. 09/090,598 filed Jun. 4, 1998, now U.S. Pat. No. 5,934,286, which is a continuation of application Ser. No. 09/073,336, filed May 5, 1998, now U.S. Pat. No. 5 , 979 , 455 , which is a continuation of application Ser. No. 08/702,742, filed Aug. 23, 1996, now U.S. Pat. No. 5,749,375, which is a continuation of application Ser. No. 08/391,960, filed Feb. 21, 1995, now U.S. Pat. No. 5,571,167, which is a continuation of application Ser. No. 08/138,912, filed Oct. 18, 1993, now U.S. Pat. No. 5,456,712, which is a division of application Ser. No. 08 / 056 , 371 , filed on May 3, 1993, now U.S. Pat. No. 5,304,220, which is a continuation-in-part of application Ser. No. 07/725,597, filed on Jul. 3, 1991, now U.S. Pat. No. 5,211,683.
FIELD OF THE INVENTION
[0002] The present invention relates generally to a system and apparatus for improving blood flow in the body of a patient and more particularly to an extravascular bypass grafting technique that utilizes a graft and delivery system in an intravascular approach.
BACKGROUND OF THE INVENTION
[0003] Treatment of vascular disease in which the lumen of a blood vessel is significantly narrowed or occluded by atherosclerosis includes surgical and endovascular methods. Conventional surgical methods include obtaining access to a blood vessel via one or more surgical incisions and either removing the blockage by performing an endarterectomy or bypassing the blockage by placing a bypass graft which has a generally cylindrical shape. Endovascular methods include obtaining access to a blood vessel with a catheter and improving blood flow therein by performing an athrectomy, atherolysis, or balloon and laser angloplasty with or without endovascular stent placement. In general, the preferred treatment of severe stenosis or occlusion of a long vessel segment has been surgical bypass grafting.
[0004] Although conventional surgical bypass grafting is an accepted procedure. It presents substantial morbidity and mortality risks. Also, not all patients are acceptable candidates for the above surgical procedure due to advanced age and preexisting medical conditions. Moreover, conventional surgical bypass grafting is an invasive procedure which may require extended hospitalization due to postoperative recovery. In addition, the above surgical procedure may involve substantial financial costs to patients, hospitals and society in general. Further, incisions made during the above surgical procedure may cause significant cosmetically unattractive scarring which is undesirable to many patients.
SUMMARY OF THE INVENTION
[0005] One embodiment of the present invention involves a method of implanting a graft prosthesis in the body of a patient to bypass a segment of a blood vessel. The method includes the steps of (1) making an incision in the body, (2) positioning a graft so that one end of the graft is located substantially adjacent the blood vessel at a site upstream of the segment and a second end of the graft is located substantially adjacent the blood vessel at a site downstream of the segment wherein the positioning step includes the step of placing the graft into the body through the incision, and further wherein the positioning step is performed while the upstream site is covered by a substantially intact portion of the epidermis of the body, (3) isolating a region of the area within the blood vessel substantially adjacent the upstream site from fluid communication with the rest of the area within the blood vessel, wherein the upstream isolating step is performed while the upstream site is covered by the substantially intact portion of the epidermis of the body (4) making an arteriotomy in a sidewall of the blood vessel substantially adjacent the upstream site to create a communicating aperture between the upstream isolated region and an area outside of the blood vessel, wherein the upstream arteriotomy making step is performed while the upstream site is covered by the substantially intact portion of the epidermis of the body (5) forming an anastomosis between the end portion of the graft and the blood vessel substantially adjacent the second location, wherein the anastomosis forming step is performed while the second location is covered by the substantially intact portion of the epidermis of the body, and further wherein the anastomosis forming step includes the step of suturing the end portion of the graft to the blood vessel, (6) isolating a region of the area within the blood vessel substantially adjacent the downstream site from fluid communication with the rest of the area in the blood vessel, (7) making an arteriotomy in the sidewall of the blood vessel substantially adjacent the downstream site to create a communicating aperture between the downstream isolated region and the area outside of the blood vessel, and (8) forming an anastomosis between the second end of the graft and the blood vessel substantially adjacent the downstream site.
[0006] Another embodiment of the present invention involves a method for implanting an end portion of a graft within the body of a patient during a bypass grafting procedure. The method includes the steps of (1) making an incision in the body at a first location, (2) isolating a region of the area within a blood vessel of the body substantially adjacent a second location from fluid communication with the rest of the area within the blood vessel, wherein the first location is remote from the second location, and further wherein the isolating step is performed while the second location is covered by a substantially intact portion of the epidermis of the body, (3) making an arteriotomy in the sidewall of the blood vessel substantially adjacent the second location to create a communicating aperture between the isolated region and the outside of the blood vessel, wherein the arteriotomy making step is performed while the second location is covered by the substantially intact portion of the epidermis of the body, (4) advancing the end portion of the graft through the incision to the second location, wherein the advancing step is performed while the second location is covered by the substantially intact portion of the epidermis of the body, and (5) forming an anastomosis between the end portion of the graft and the blood vessel substantially adjacent the second location, wherein the anastomosis forming step is performed while the second location is covered by the substantially intact portion of the epidermis of the body, and further wherein the anastomosis forming step includes the step of suturing the end portion of the graft to the blood vessel.
[0007] Still another embodiment of the present invention involves a graft which is securable to a sidewall of a blood vessel having an arteriotomy defined therein. The graft includes a body portion, and a flanged end portion attached to the body portion, the flanged end portion being positionable substantially adjacent a portion of the sidewall of the blood vessel which substantially surrounds the arteriotomy.
[0008] Yet another embodiment of the present invention involves a graft and stent assembly which is securable to a sidewall of a blood vessel having an arteriotomy defined therein. The graft and stent assembly includes a graft having an end portion which is positionable within the blood vessel and substantially adjacent a portion of the sidewall of the blood vessel which substantially surrounds the arteriotomy. The graft and stent assembly further includes a stent positionable within the blood vessel and in contact with the end portion of the graft so as to secure the end portion of the graft between the sidewall of the blood vessel and the stent.
[0009] One object of the present invention is to provide an improved method for implanting a graft prosthesis in the body of a patient.
[0010] Another object of the present invention is to provide an improved method for implanting an end portion of a graft within the body of a patient.
[0011] Still another object of the present invention is to provide a method of implanting a graft prosthesis in the body of a patient which is less invasive relative to conventional surgical bypass grafting procedures.
[0012] Yet another object of the present invention is to provide a method of implanting a graft prosthesis in the body of a patient which obviates at least one surgical incision (e.g. the abdominal surgical incision) as compared to conventional surgical bypass grafting procedures.
[0013] Still another object of the present invention is to provide a method of implanting a graft prosthesis in the body of a patient which has low morbidity and mortality risk to patients.
[0014] Yet another object of the present invention is to provide a method of implanting a graft prosthesis in the body of a patient which can be performed on patients whom are elderly or have poor preexisting medical conditions.
[0015] Still another object of the present invention is to provide a method of implanting a graft prosthesis in the body of a patient which requires relatively less financial costs to patients, hospitals and society in general as compared to conventional surgical bypass grafting techniques.
[0016] Yet another object of the present invention is to provide an improved graft prosthesis.
[0017] Still another object of the present invention is to provide an improved graft and stent assembly.
[0018] Another object of the present invention is to provide a graft which can be conveniently secured to a blood vessel.
[0019] Yet another object of the present invention is to provide a graft and stent assembly which allows the graft to be conveniently secured to a blood vessel.
[0020] Yet still another object of the present invention is to provide a graft which is easy to implant in the body of a patient.
[0021] Still another object of the present invention is to provide a graft and stent assembly which is easy to implant in the body of a patient.
[0022] Another object of the present invention is to provide a graft which functions well after it is implanted in the body of a patient.
[0023] Yet another object of the present invention is to provide a graft and stent assembly which functions well after it is implanted in the body of a patient.
[0024] Other objects and benefits of the present invention can be discerned from the following description and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a fragmentary front elevational view of a human body showing a blood vessel which includes the aorta, the right common iliac artery, the right common femoral artery and the left common femoral artery wherein a segment of the blood vessel is occluded. FIG. 1 also shows a portion of each inguinal ligament of the human body.
[0026] FIG. 2 is an enlarged fragmentary view of the human body and blood vessel of FIG. 1 .
[0027] FIG. 3 shows the human body and blood vessel of FIG. 2 with a balloon-tip catheter positioned within the blood vessel wherein the balloon is inflated in accordance with the preferred method of the present invention.
[0028] FIG. 4 is a view similar to FIG. 3 but showing a second balloon-tip catheter positioned within the blood vessel wherein the second balloon is inflated in accordance with the preferred method of the present invention.
[0029] FIG. 5 is a view similar to FIG. 4 but showing the blood vessel in phantom except for a portion thereof that is exposed through a gaping surgical incision. Also shown exposed through the surgical incision in FIG. 5 is a portion of the right inguinal ligament.
[0030] FIG. 6 is a view similar to FIG. 5 but showing another portion of the blood vessel. Including the aorta, exposed for clarity of description. Moreover, in FIG. 6 , a laparoscope (depicted schematically) is shown inserted through the surgical incision in accordance with the preferred method of the present invention.
[0031] FIG. 7 is a view similar to FIG. 6 but showing a needle positioned within the laparoscope in accordance with the preferred method of the present invention.
[0032] FIG. 8 is a view similar to FIG. 7 but showing the needle removed from the laparoscope and replaced with a scissors device in accordance with the preferred method of the present invention.
[0033] FIG. 9A is an elevational view of a graft prosthesis used in carrying out the preferred method of the present invention.
[0034] FIG. 9B is a fragmentary sectional view taken along the line 9 B- 9 B of FIG. 9A as viewed in the direction of the arrows.
[0035] FIG. 9C is a fragmentary perspective view of the graft prosthesis of FIG. 9A showing its outwardly extending flanged end portion.
[0036] FIG. 9D is another fragmentary perspective view of the graft prosthesis of FIG. 9A showing its outwardly extending flanged end portion.
[0037] FIG. 9E is a view similar to FIG. 9C but showing a plurality of springs, in phantom, integrally positioned within the outwardly extending flanged end portion, in addition to a portion of the sidewalls of the graft prosthesis of FIG. 9A .
[0038] FIG. 9F is an elevational view of one of the plurality of springs of FIG. 9E .
[0039] FIG. 9G is an elevational view of another of the plurality of springs of FIG. 9E .
[0040] FIG. 9H is an elevational view of yet another of the plurality of springs of FIG. 9E .
[0041] FIG. 9I is an elevational view of still another of the plurality of springs of FIG. 9E .
[0042] FIG. 10A is an elevational view of the graft prosthesis of FIG. 9A wherein the graft prosthesis is in a rolled configuration.
[0043] FIG. 10B is a cross-sectional view taken along the line 10 B- 10 B of FIG. 10A as viewed in the direction of the arrows.
[0044] FIG. 11A is an elevational view of the laparoscope of FIG. 6 . Moreover, FIG. 11A shows the graft prosthesis of FIG. 10A , positioned within the laparoscope in accordance with the method of the present invention. FIG. 11A , further shows a plunger, used in carrying out the preferred method of the present invention, partially positioned within the laparoscope in accordance with the preferred method of the present invention.
[0045] FIG. 11B is a cross-sectional view taken along the line 11 B- 11 B of FIG. 11A as viewed in the direction of the arrows.
[0046] FIG. 12 is a view similar to FIG. 8 but showing the scissors device removed from the laparoscope and replaced with the graft prosthesis and plunger of FIG. 11A in accordance with the preferred method of the present invention.
[0047] FIG. 13 IS a view similar to FIG. 12 but showing the graft prosthesis being advanced out the distal end of the laparoscope in accordance with the preferred method of the present invention.
[0048] FIG. 14 is a view similar to FIG. 13 but showing the graft prosthesis being further advanced out the distal end of the laparoscope in accordance with the preferred method of the present invention.
[0049] FIG. 15 is a view similar to FIG. 14 but showing the graft prosthesis being yet further advanced out the distal end of the laparoscope in accordance with the preferred method of the present invention.
[0050] FIG. 16 is a view similar to FIG. 15 but showing the laparoscope removed from the surgical incision and showing the graft prosthesis after it had reverted back to its pre-rolled configuration in accordance with the preferred method of the present invention.
[0051] FIG. 17 is a view similar to FIG. 16 but showing a third balloon-tip catheter having a balloon thereon and further having an expandable stent, in its unexpanded state, positioned over the balloon, advanced to a position within the blood vessel in accordance with the preferred method of the present invention.
[0052] FIG. 18 is a view similar to FIG. 17 but showing the balloon of the third balloon-tip catheter inflated so as to expand the stent in to its expanded configuration in accordance with the preferred method of the present invention.
[0053] FIG. 19A is a view similar to FIG. 18 but showing the third balloon-tip catheter removed from the blood vessel and showing the stent expanded to form an anastomosis between one end of the graft prosthesis and the blood vessel in accordance with the preferred method of the present invention.
[0054] FIG. 19B is an enlarged schematic side elevational view showing a number of sutures tied to the sidewall of the blood vessel so as to secure the end portion of the graft and the stent thereto as a possible additional procedure in order to further ensure the integrity of the anastomosis of FIG. 19A .
[0055] FIG. 19C IS a cross-sectional view taken along the line 19 C- 19 C of FIG. 19B as viewed in the direction of the arrows.
[0056] FIG. 19D is a view similar to FIG. 19A but showing a laparoscope (depicted schematically) inserted through an incision in the epidermis of the body and into the peritoneal cavity, and further showing a grasper holding a curved needle with an end of a suture attached thereto wherein the distal end of the grasper is positioned at the upstream site.
[0057] FIG. 19E is an enlarged schematic side elevational view showing a number of sutures tied to the sidewall of the blood vessel so as to secure the end portion of the graft thereto (without the use of the stent), wherein the end portion of the graft is positioned within the upstream isolated region, as an alternative procedure in forming an anastomosis between the end portion of the 15 graft and the blood vessel.
[0058] FIG. 19F is a cross-sectional view taken along the line 19 F- 19 F of FIG. 19E as viewed in the direction of the arrows.
[0059] FIG. 19G is an enlarged schematic side elevational view showing a number of sutures tied to the sidewall of the blood vessel so as to secure the end portion of the graft thereto (without the use of the stent), wherein the end portion of the graft is positioned outside of the upstream isolated region, as another alternative procedure in forming an anastomosis between the end portion of the graft and the blood vessel.
[0060] FIG. 19H is a cross-sectional view taken along the line 19 H- 19 H of FIG. 19G as viewed in the direction of the arrows.
[0061] FIG. 20A is an enlarged side elevational view showing the anastomosis of FIG. 19A .
[0062] FIG. 20B is a cross-sectional view taken along the line 20 B- 20 B of FIG. 20A as viewed in the direction of the arrows.
[0063] FIG. 20C is a cross-sectional view taken along the line 20 C- 20 C of FIG. 20A as viewed in the direction of the arrows.
[0064] FIG. 21 is a view similar to FIG. 19A but showing a pair of clamps positioned on the blood vessel in accordance with the preferred method of the present invention.
[0065] FIG. 22 is a view similar to FIG. 21 but showing an arteriotomy formed in the sidewall of the blood vessel in accordance with the preferred method of the present invention.
[0066] FIG. 23 is a view similar to FIG. 22 but showing an anastomosis formed between the other end, the graft prosthesis and the blood vessel in accordance with the preferred method of the present invention.
[0067] FIG. 24 is a view similar to FIG. 23 but showing the first balloon-tip catheter and the second balloon-tip catheter removed from the blood vessel in accordance with the preferred method of the present invention.
[0068] FIGS. 25-33 are views showing performance of a bypass grafting procedure in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0069] For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments and methods illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated devices and methods, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
[0070] Referring now to the drawings, FIG. 1 shows a portion of a human body, generally designated by the reference numeral 10 , with an artery, the common iliac artery 12 , having an occluded segment, generally designated by the reference numeral 14 . Human body 10 is further shown having other arteries, in particular, aorta 16 , right common femoral artery 18 , left common femoral artery 1530 and renal arteries 20 . In addition, human body 10 includes a right inguinal ligament 19 and a left inguinal ligament 29 . Human body 10 also includes an epidermis 13 (see e.g. FIG. 6 ). The preferred method disclosed herein describes the implantation of a graft to couple aorta 16 to right common femoral artery 18 thereby bypassing occluded segment 14 . FIG. 2 shows an enlarged view of aorta 16 , right common iliac artery 12 , occluded segment 14 , right common femoral artery 18 , left common femoral artery 30 , renal arteries 20 and right inguinal ligament 19 . In FIGS. 1 and 2 , a blood vessel is shown, generally designated by the reference numeral 11 , which includes aorta 16 , right common iliac artery 12 , right common femoral artery 18 and left common femoral artery 30 . Blood vessel 11 , when not occluded, conveys blood from a point C within aorta 16 to a point D within right common femoral artery 18 (see FIGS. 1-2 ). However, due to the presence of occluded segment 14 , blood is substantially totally precluded from being conveyed from point C within aorta 16 to point D within right common femoral artery 18 via the direct route of right common iliac artery 12 . While the inventive method will hereinafter be described with regard to a substantially totally occluded segment of a blood vessel of a patient, it will be understood to one skilled in the art that the inventive method is equally effective for bypass of a partially occluded segment of a blood vessel. In addition, the inventive method is also useful for bypass of an aneurysmal segment of a blood vessel.
[0071] Referring now to FIGS. 3-24 , successive steps according to the preferred method of the present invention are depicted of the implantation of a graft prosthesis of the present invention to couple aorta 16 to right common femoral artery 18 thereby bypassing occluded segment 14 of blood vessel 11 .
[0072] One step of the preferred method of the present invention comprises isolating a region of the area within the blood vessel 11 , located near a site 21 1 s (see FIG. 4 ) upstream of occluded segment 14 , from fluid communication with the rest of the area within the blood vessel. There also exists a site 31 which is located downstream of occluded segment 14 (see FIG. 4 ). Upstream site 21 is located substantially adjacent the blood vessel 11 and designates a working area where the distal end of medical instruments and various medical devices may be positioned during the process of securing one end of a graft to the blood vessel. Upstream site 21 is located near blood vessel 11 so as to allow such distal end of medical instruments and medical devices to be appropriately manipulated at upstream site 21 to thereby successfully secure the one end of the graft to the blood vessel Downstream site 31 is located substantially adjacent the blood vessel 11 and also designates a working area where the distal end of medical instruments, physician's hands and various medical devices may be positioned during the process of securing a second end of the graft to the blood vessel. Downstream site 31 is also located near blood vessel 11 so as to allow such distal end of medical instruments. physician's hands and medical devices to be appropriately manipulated at downstream site 31 to thereby successfully secure the second end of the graft to the blood vessel.
[0073] Referring now to FIG. 3 , a balloon-tip catheter 22 having a balloon 24 thereon is percutaneously inserted into blood vessel 11 via the right or left axillary artery (not shown). This step may be accomplished using standard catherization techniques. The distal end of catheter 22 is then advanced into aorta 16 until balloon 24 is positioned distal to renal arteries 20 as shown in FIG. 3 . Balloon 24 is then inflated to and maintained at a size such that fluid communication is substantially terminated in aorta 16 between the portion of blood vessel 11 proximal to balloon 24 and the portion of blood vessel 11 distal to balloon 24 . Since conventional balloon-tip catheters may not have a balloon thereon that possess the characteristics necessary to terminate fluid communication in the aorta as described above, modification may be readily made to an existing design of a conventional balloon-tip catheter to achieve the above desired results. One such modification would include providing a balloon on the catheter with is inflatable to an outer diameter which is larger than the inner diameter of the aorta. Another such modification would include providing a coarse textured outer surface to the balloon of the catheter. The above modification would provide increased frictional resistance between the inflated balloon and the sidewall of the blood vessel when force is applied to the balloon in the axial direction thereof. A balloon-tip catheter having a conventional design is available through Medi-tech, Incorporated of Watertown, Massachusetts, as Order No.17-207 (Description: OBW/4018/2/100).
[0074] Referring now to FIG. 4 , a balloon-tip catheter 26 having a balloon 28 thereon and an open lumen defined therein is percutaneously inserted into blood vessel 11 via the left common femoral artery 30 . This step may be accomplished using standard catherization techniques. The distal end of the catheter 26 is then advanced into aorta 16 until balloon 28 is positioned proximal to the aortic bifurcation. Balloon 28 is then inflated to and maintained at a size such that fluid communication is substantially terminated in aorta 16 between the portion of blood vessel 11 proximal to balloon 28 and the portion of blood vessel 11 distal to balloon 28 . Since conventional balloon-tip catheters may not have a balloon thereon that possess the characteristics necessary to terminate fluid communication in the aorta as described above, modification similar to that 10 described with respect to catheter 22 may need to be made to catheter 26 . In addition, further modification may need to be made to catheter 26 since a conventional balloon-tip catheter may not have an open central lumen defined therein which possesses a diameter large enough for the advancement therethrough of a compressed stent mounted on a balloon of another balloon-tip catheter as will be required by the preferred method of the present invention (see FIG. 17 ). Such further modification would be to create an open central lumen in catheter 26 that possesses a diameter larger than the outer diameter of the compressed stent which is mounted on the balloon of the balloon-tip catheter as referred to above. Due to the increased size requirements of catheter 26 as 20 alluded to above, a surgical cut-down may need to be performed in order to expose left common femoral artery 30 . Such exposure would facilitate both placement of catheter 26 into blood vessel 11 and repair of such blood vessel following subsequent removal of such catheter therefrom.
[0075] Temporary occlusion of the blood flow in the inferior mesenteric artery 2 s (not shown) by laparoscopic procedures may need to be performed in order to prevent the flow of blood from the inferior mesenteric artery into aorta 16 due to placement of inflated balloons 24 and 28 as discussed above.
[0076] The region bound by balloon 24 of catheter 22 and balloon 28 of catheter 26 and the sidewall of blood vessel 11 contained therebetween defines a region 40 of the area within blood vessel 11 , located near site 21 upstream of occluded segment 14 , which is substantially isolated from fluid communication with the j rest of the area within blood vessel 11 .
[0077] Alternatively, the step of isolating the region of the area within blood vessel 11 , located near upstream site 21 , from fluid communication with the rest of the area with the rest of the area within the blood vessel may be accomplished by laparoscopically placing a first clamp around the blood vessel 11 at the location where balloon 24 of the balloon-tip catheter 22 was described as having been inflated and also laparoscopically placing a second clamp around the blood vessel 11 at the location where balloon 28 of the balloon-tip catheter 26 was described as having been inflated.
[0078] Another step according to the method of the present invention comprises making an arteriotomy in the sidewall of blood vessel 11 , near upstream site 21 , to create a communicating aperture between upstream isolated region 40 and the outside of blood vessel 11 .
[0079] Referring now to FIG. 5 , right common femoral artery 18 and right inguinal ligament 19 are exposed via a surgical incision 17 . Such exposure is accomplished using standard surgical techniques.
[0080] Insufflation of the peritoneal cavity is then performed using standard techniques associated with laparoscopy. A laparoscope 37 (see FIG. 6 ), having an open central lumen (i.e a working channel) defined therein, is then inserted into human body 10 through the opening between right common femoral artery 18 and right inguinal ligament 19 . Laparoscope 37 may additionally include a fiber optic illumination device and a telescope for viewing. A tilt table may be used with the patient (i.e. human body 10 ) positioned thereon in order to maneuver the patient's abdominal contents away from the laparoscope insertion site and the area near upstream site 21 . Laparoscope 37 is then advanced toward upstream site 21 until its distal end is positioned there at as shown in FIG. 6 . One or more additional laparoscopes and associated laparoscopic operating instruments may be employed using standard laparoscopic techniques to assist in the above positioning via direct visualization, tissue retraction and tissue dissection. One laparoscope which may be used in carrying out the preferred method of the present invention is available through Karl Stop Endoscopy-America Incorporated of Culver City, Calif., as Catalog No 26075A. Modification may be readily made to laparoscope 37 , such as rounding the distal edge thereof, in order to reduce the possibility of tissue trauna as a result of advancement of laparoscope 37 within human body 10 . A book which discloses various standard laparoscopic techniques and standard associated laparoscopic operating instruments is entitled “Laparoscopy for Surgeons,” authored by Barry 15 A. Salky, M.D., published by Igaku-Shoin Medical Publishers, Inc. of New York, N.Y., U.S.A. (1990), and the pertinent part of the disclosure of which is herein incorporated by reference.
[0081] Referring now to FIG. 7 , a puncture needle 39 is advanced through the open central lumen of laparoscope 37 until its distal end exits the laparoscope. Thereafter, needle 39 is manipulated to penetrate through the sidewall of blood vessel 11 to the inside thereof, thus creating a puncture in the blood vessel. Needle 39 is then withdrawn and a scissors device 41 is advanced through the open central lumen of laparoscope 37 until its distal end exits the laparoscope (see FIG. 8 ). The scissors device is then manipulated to enlarge the puncture in the sidewall of the blood vessel. Scissors device 41 is then withdrawn from laparoscope 37 . One puncture needle which may be used in carrying out the preferred method of the present invention is available through Karl Stop Endoscopy-America. Incorporated of Culver City, Calif., as Catalog No. 261 78R. Additionally, one scissors device which may be used in carrying out the method of the present invention is available through Karl Storz Endoscopy-America, Incorporated of Culver City, Calif., as Catalog No. 25 178PS.
[0082] It should be noted that if upstream isolated region 40 was not substantially isolated from fluid communication with the rest of the area within the blood vessel, the act of making an arteriotomy in the sidewall of blood vessel 11 near upstream site 21 would cause significant blood leakage out of blood vessel 11 and such blood leakage may be fatal to the patient.
[0083] According to another step of the method of the present invention, a graft prosthesis is positioned so that one end of the graft is located substantially adjacent blood vessel 11 at downstream site 21 and the other end of the graft prosthesis is located substantially adjacent blood vessel 11 at downstream site 31 . The above positioning step includes the step of advancing the graft prosthesis within the human body 10 with a medical instrument.
[0084] One type of graft prosthesis which may be used is a graft, generally designated by the reference numeral 60 and shown in FIGS. 9A-9E . Graft 60 includes a body portion 61 having a length slightly larger than the distance between upstream site 21 and downstream site 3 1 . Graft 60 has an outwardly extending flanged end portion 62 as shown in FIGS. 9A, 9C , 9 D and 9 E. End portion 62 is resiliently maintained outwardly extending by four springs 64 A- 64 D as shown in FIGS. 9 B and 9 E- 91 . In their relaxed state, springs 64 A- 64 D maintain end portion 62 within a plane PI as shown in FIG. 9A . It should be noted that a number of springs other than four may be used, if desired, to maintain end portion 62 outwardly extending as previously shown and described. Graft 60 further includes a second end portion 63 having a design similar to that of a conventional prosthetic graft as shown in FIG. 9A . Graft 60 is preferably made of synthetic fibers. By way of example, graft 60 can be made from the material sold under the trademark Dacron by E.I. du Pont de Nemours & Co., Inc. of Wilmington, Del. Body portion 61 and end portion 62 are integrally formed together with springs 644 - 640 maintained integrally within the end portion 62 and a portion of the sidewalls of body portion 51 as shown in FIGS. 98 and 9 E. Graft 60 maintains its shape as shown in FIGS. 9A-9E absent application of external forces thereto and also graft 60 will revert back to such shape upon termination of such external forces thereto.
[0085] Graft 60 is positioned within the open central lumen defined in laparoscope 37 . In order to achieve the above, graft 60 is preferably rolled into a substantially cylindrical shape as shown in FIGS. 10A and 10B . End portion 62 of graft 60 is manipulated to lie substantially parallel to body portion 61 of graft 60 while graft 60 is in its rolled configuration as shown in FIG. 10A . The outer diameter of graft 60 , in its rolled configuration, from point W to point Y is larger than the outer diameter of the rolled graft from point Y to point Z as shown in FIG. 10A . The above is due to the angular construction of end portion 62 as shown in FIG. 9A . The outer diameter of the rolled graft from point W to point Y is slightly smaller than the inner diameter of laparoscope 37 . As a result, in its rolled configuration, graft 60 can be positioned within the open central lumen of laparoscope 37 . Moreover, graft 60 can be maintained in its roiled configuration while positioned in the central lumen of laparoscope 37 due to the inner diameter thereof. Graft 60 is then inserted into the proximal end of the central lumen of laparoscope 37 and advanced until its full length is entirely therein. A plunger 82 is insertable into the central lumen of laparoscope 37 as shown in FIGS. 11A and 11B . Plunger 82 has a length sufficient to span the length of laparoscope 37 . Plunger 82 enables an operator to selectively position graft 60 within body 10 . FIGS. 11A and 12 show graft 60 positioned in the distal portion of the central lumen of laparoscope 37 after being advanced by plunger 82 . Laparoscope 37 with graft 60 contained therein is then advanced and manipulated such that the distal end of the laparoscope is advanced through the communicating aperture near upstream site 21 and into isolated region 40 . While the plunger is held stationary, laparoscope 37 is then withdrawn axially over plunger 82 and graft 60 in the direction of arrow 84 as sequentially shown in FIGS. 13-15 This allows graft 60 in its rolled configuration to be delivered out the distal end of laparoscope 37 . FIG. 15 shows end portion 62 of graft 60 positioned within upstream isolated region 40 and end portion 63 of graft 60 positioned at downstream site 31 . Since graft 60 is no longer held in its rolled configuration by the inner diameter of the open central lumen of laparoscope 37 , graft 60 becomes unrolled and reverts to its prerolled configuration as shown in FIG. 16 . Injection of a saline solution into graft 60 , via end portion 63 , may be performed to facilitate the reverting of graft 60 to its prerolled configuration. Alternatively, an additional laparoscope may be used to manipulate graft 60 to its prerolled configuration. Alternatively, a balloon-tip catheter may be advanced into graft 60 via end portion 63 and the graft converted to its prerolled configuration by inflation and deflation of the balloon along various segments of the graft.
[0086] Also shown in FIG. 16 , end portion 62 of graft 60 is positioned within upstream isolated region 40 near upstream site 21 and end portion 63 of graft 60 is positioned at downstream site 31 while body portion 61 of graft 60 is positioned outside of blood vessel 11 . Note that end portion 62 has also reverted back to its prerolled configuration so that such end portion is outwardly extending relative to body portion 61 of graft 60 .
[0087] Another step according to the preferred method of the present invention includes forming an anastomosis between end portion 62 of graft 60 and blood vessel 11 near upstream site 21 .
[0088] A balloon-tip catheter 86 having a balloon 88 thereon and further having an expandable stent 90 in its unexpanded configuration, positioned over balloon 38 is advanced through the open central lumen of catheter 26 until its distal end is located within upstream isolated region 40 near upstream site 21 (see FIG. 17 ). Catheter 86 is further advanced until balloon 88 is positioned substantially adjacent end portion 62 of graft 50 as shown in FIG. 17 . Balloon 88 is then inflated to expand stent 90 to its expanded configuration such that end portion 62 is secured between stent 90 and the sidewall of blood vessel 11 near upstream site 21 as shown in FIG. 18 . Balloon 88 is then deflated and catheter 86 is then removed from body 10 via the central lumen of catheter 26 . FIG. 19A shows body 10 after catheter 86 is removed therefrom. Moreover, FIGS. 20A-20C show end portion 62 of graft 60 being forced into the sidewall of blood vessel 11 by stent 90 (in its expanded configuration) such that graft 60 is secured to blood vessel 11 near upstream site 21 at its end portion 62 .
[0089] One stent which may be used, with a minor degree of modification, in carrying out the preferred method of the present invention is disclosed in U.S. Pat. No. 4,776,337 issued to Palmaz on Oct. 11, 1988, the pertinent part of the disclosure of which is herein incorporated by reference. Such modification would be to provide stent 90 with an outer diameter (in its fully expanded configuration) that is larger than the inner diameter of blood vessel 11 near upstream site 21 .
[0090] Note that stent 90 includes a plurality of intersecting bars 71 which span the ortifice of graft 60 near end portion 62 as shown in FIG. 208 . Intersecting bars 71 which span the above ortifice do not substantially hinder blood flow through the graft orifice as demonstrated by the technical article entitled “lntravascular Stents to Prevent Occlusion and Restenosis After Transluminal Angioplastyl′ which was published in the Mar. 19, 1987 edition of the periodical “The New England Journal of Medicine,” the pertinent part of the disclosure of which is herein incorporated by reference.
[0091] Further modification may be readily made to stent 90 whereby stent 90 would have an opening defined in its sidewall which is of similar dimensions to the orifice of graft 60 near end portion 62 . Such opening would have no intersecting bars traversing thereover. The above modification would allow stent 90 to be positioned within blood vessel 11 near upstream site 21 wherein the above opening would be substantially superimposed over the orifice of graft 60 near end portion 62 . This would allow blood to flow through the connection between blood vessel 11 and graft 60 near upstream site 21 in an unimpeded manner.
[0092] As a possible additional procedure in order to further ensure the integrity of the anastomosis between end portion 62 of graft 60 and blood vessel 11 near upstream site 21 , a number of sutures 100 may be tied to the sidewall of blood vessel 11 so as to further secure end portion 62 and stent 90 to the sidewall of blood vessel 11 as schematically shown in FIGS. 19B and 19C . This is accomplished by inserting a laparoscope 102 (which is similar to laparoscope 37 ) having an open central lumen into human body 10 until its distal end is near upstream site 21 . Thereafter, a grasper 104 is advanced through the central lumen of laparoscope 102 . The grasper 104 has in its grasp a curved needle 106 having an end of suture 100 attached thereto as shown in FIG. 19D . By manipulating the distal end of grasper 104 , the needle 106 and the end of suture 100 are passed through the sidewall of blood vessel 11 and end portion 62 of graft 60 and into blood vessel 11 . With continued manipulation, the needle 106 and the end of suture 100 are then brought back out of blood vessel 11 . The suture 100 is then tied by standard laparoscopic techniques. One article that refers to standard laparoscopic techniques for tying sutures is entitled ‘Laparoscopic Choledocholithotomy which was published in Volume 1, Number 2, 1991 edition of the “Journal of Laparoendoscopic Surgery,” (Mary Ann Liebert, Inc. Publishers) pages 79-32, and another article that refers to standard laparoscopic techniques for tying sutures is entitled “Improvement in Endoscopic Hernioplasty: Transcutaneous Aquadissection of the Musculofascial Defect and Preperitoneal Endoscopic Patch Repair”, which was published in Volume 1, Number 2. 1991 edition of the “Journal of Laparoendoscopic Surgery” (Mary Ann Liebert, Inc. Publishers), pages 83-90, the pertinent part of both of the above articles of which is herein incorporated by reference. A number of other sutures 100 are then tied to the sidewall of blood vessel 11 and end portion 62 of graft 60 in a manner similar to that hereinbefore described so as to further secure end portion 62 to the sidewall of blood vessel 11 as schematically shown in FIGS. 19B and 19C . One or more additional laparoscopes and associated laparoscopic operating instruments may be employed using standard laparoscopic techniques to assist in the above suturing procedure. Of course, sutures 100 may be sewn in a conventional running fashion so as to secure end portion 62 to the sidewall of blood vessel 11 . Also, end portion 62 may be sutured to the sidewall of blood vessel 11 prior to the placement of stent 90 within blood vessel 11 .
[0093] Alternatively, the step of forming an anastomosis between end portion 62 of graft 60 and blood vessel 11 near upstream site 21 may be accomplished by suturing alone (i.e. without the use of stent 90 ). In particular, once end portion 62 of graft 60 is positioned within upstream isolated region 40 near upstream site 21 as shown in FIG. 16 . end portion 62 is sutured to the sidewall of blood vessel 11 as schematically shown in FIGS. 19E and 19F . Note that in this alternative step, end portion 62 is sutured to an interior portion of blood vessel 11 as schematically shown in FIGS. 19E and 19F . Also note that end portion 62 is sutured to the sidewall of blood vessel 11 so as to be positioned substantially adjacent a portion of the sidewall of blood vessel 11 which substantially surrounds the arteriotomy. This is accomplished by tying a number of sutures 110 to the sidewall of blood vessel 11 and end portion 62 of graft 60 so as to secure end portion 62 to the sidewall of blood vessel 11 as schematically shown in FIGS. 19E and 19F . The sutures 110 shown in FIGS. 19E and 19F are applied in the same manner as the sutures 100 shown in FIGS. 198, 19C and 19 D were applied as described above. Of course, sutures 110 may be sewn in a conventional running fashion so as to secure end portion 62 to the sidewall of blood vessel 11 .
[0094] As a further alternative, the end portion 62 of graft 60 need not be positioned in upstream isolated region 40 but rather end portion 62 may be positioned adjacent the sidewall of blood vessel 11 so that the communicating aperture (i.e. the arteriotomy) in the sidewall of blood vessel 11 near upstream is site 21 is aligned with the central passage of graft 60 . At this position, end portion 62 is sutured to the sidewall of blood vessel as schematically shown in FIGS. 19G and 19 H. Note that in this further alternative step, end portion 62 is sutured to an exterior portion of blood vessel 11 as schematically shown in FIGS. 19G and 19H . Also note that end portion 62 is sutured to the sidewall of blood vessel 11 so as to be positioned substantially adjacent a portion of the sidewall of blood vessel 11 which substantially surrounds the arteriotomy. This is accomplished by tying a number of sutures 120 to the sidewall of blood vessel 11 and end portion 62 of graft 60 so as to secure end portion 62 to the sidewall of blood vessel 11 as schematically shown in FIGS. 19G and 19H . The sutures 120 shown in FIGS. 19G and 19H are applied in the same manner as the sutures 100 shown in FIGS. 19B 19 C and 19 D were applied as described above. Of course, sutures 120 may be sewn in a conventional running fashion so as to secure end portion 62 to the sidewall of blood vessel 11 .
[0095] The remainder of the preferred method of the present invention is performed using standard surgical techniques. A book which discloses various standard surgical techniques is entitled “Color Atlas of Vascular Surgery,” authored by John S. P. Lumley, published by Wolfe Medical Publications Ltd. of Baltimore. Md. (1986), printed by W.S. Cowell, Ltd. of Ipswich, United Kingdom, and the pertinent part of the disclosure of which is herein incorporated by reference. More specifically, another step according to the preferred method of the present invention comprises isolating a region 50 of the area within blood vessel 11 , located near site 31 downstream of occluded segment 14 , from fluid communication with the rest of the area within the blood vessel. Referring now to FIG. 21 , a pair of surgical clamps 53 and 55 are positioned on blood vessel 11 , one being placed upstream of isolated region 50 and the other being placed downstream of isolated region 50 .
[0096] Another step according to the method of the present invention comprises making an arteriotomy in the sidewall of blood vessel 11 , near downstream site 31 , to create a communicating aperture between downstream isolated region 50 and the outside of the blood vessel 11 . End portion 63 of graft 60 is retracted by surgical forceps (not shown) to expose blood vessel 11 near downstream site 31 (see FIG. 22 ). A scalpel puncture is then made in blood vessel 11 near downstream site 31 and thereafter the puncture is extended to the appropriate length with a pair of surgical scissors. FIG. 22 shows the communicating aperture defined in the sidewall of blood vessel 11 , near downstream site 31 .
[0097] Another step according to the preferred method of the present invention comprises forming an anastomosis between end portion 63 of graft 60 and blood vessel 11 near downstream site 31 . Graft 60 is then cut to an appropriate length and thereafter end portion 63 is cut an appropriate shape for attachment to blood vessel 11 . End portion 62 of graft 60 is then surgically stitched with suture 65 to blood vessel 11 near downstream site 31 as shown in FIG. 23 .
[0098] Clamps 53 and 55 are then removed from blood vessel 11 , and moreover balloons 24 and 28 are then deflated and thereafter catheters 22 and 26 are removed from body 10 as shown in FIG. 24 . This allows blood to flow to former upstream isolated region 40 . Once blood flow reaches former upstream isolated region 40 , a flow of blood will enter graft 60 and flow therethrough to former downstream isolated region 50 thereby bypassing occluded segment 14 . Consequently, proper blood flow will now exist in body 10 from point C within aorta 16 to point D within right common femoral artery 18 as a result of performing the above described method of bypass of occluded segment 14 .
[0099] While the invention has been described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments and methods have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.
[0100] For instance, it is possible that left common femoral artery 30 and left inguinal ligament 29 could be exposed via a surgical incision similar to that of incision 17 as hereinbefore described. Thereafter, a Y-shaped graft could be utilized instead of graft 60 as hereinbefore disclosed. The Y-shaped graft could be advanced in a rolled configuration through laparoscope 37 and delivered to a position substantially adjacent blood vessel 11 similar in manner to that hereinbefore described. An additional laparoscope could be inserted into human body 10 through the opening defined between left common femoral artery 30 and left inguinal ligament 29 in a manner substantially similar to that hereinbefore described with respect to the insertion of laparoscope 37 into human body 10 . The additional laparoscope could be advanced toward the left limb of the Y-shaped graft and thereafter used to grasp such limb and pull it toward left common femoral artery 30 and subsequently out of the surgical incision near the left common femoral artery. The end portion of the left limb of the Y-shaped graft could be cut to an appropriate length and shape, and thereafter, an anastomosis could be made between such end portion and left common femoral artery 30 similar in manner to that hereinbefore described with regard to right common femoral artery 18 and end portion 63 of graft 60 .
[0101] Moreover, for example, in an alternative embodiment of the present invention, it is possible that a graft 200 may be utilized which would be similar to graft 60 hereinbefore described, however, both end portions of such graft 200 could be similar in structure to end portion 62 of graft 60 (see FIGS. 29-33 ). In other words, each graft end could posses an end portion that is resiliently maintained outwardly extending relative to the body portion of the graft 200 . A catheter 202 could be placed into blood vessel 11 at right femoral artery 18 and advanced toward occluded segment 14 (see FIG. 25 ). Prior to arriving at occluded segment 14 , the distal end of the catheter 202 could be manipulated and guided out of blood vessel 11 through a puncture site 204 laparoscopically created in the blood vessel in a manner similar to that hereinbefore described (see FIG. 26 ). The catheter 202 could then be advanced substantially adjacent blood vessel 11 over and past occluded segment 14 (see FIG. 27 ). One or more additional laparascopes could assist in the above advancement (see also FIG. 27 ) The distal end of the catheter 202 could then be manipulated and guided to reenter blood vessel 11 at a site upstream of occluded segment 14 through a puncture site 206 laparoscopically created in blood vessel 11 in a manner similar to that hereinbefore described (see FIG. 28 ). The graft 200 having a resiliently outwardly extending end portion at each end thereof could then be advanced in a rolled configuration through the catheter 202 and delivered to a position substantially adjacent blood vessel 11 similar in manner to that hereinbefore described with respect to graft 60 and laparoscope 37 (see FIGS. 29, 30 , 31 ). The graft 200 could have a predetermined length equal to a length slightly larger s than the distance between the puncture site 206 located upstream of occluded segment 14 and the puncture site 204 located downstream of occluded segment 14 . As a result, the distal end portion of the graft 200 could be positioned within blood vessel 11 at a location upstream of occluded segment 14 and the proximal end portion of the graft 200 could be positioned within blood vessel 11 at a location downstream of occluded segment 14 while the body portion of the graft 200 could be positioned substanially adjacent and outside o blood vessel 11 (see FIG. 29 , 30 , 31 ). Of course, an area within the blood vessel near each end portion of the graft 200 could be isolated from fluid communication with the rest of the area within the blood vessel in a manner substanially similar to that herein before described with respect to upstream isolated region 40 . After being advance out of the distal end of the catheter 202 , the graft 200 (including each outwardly extending end portion) could revert back to its prerolled configuration as herein before describe with respect to graft 60 (see FIG. 32 ). Thereafter, a stent 208 could be placed, in an expanded configuration, adjacent each of the end portions of the graft 200 within blood vessel 11 in order to secure such end portions of the graft 200 to blood vessel 11 as hereinbefore describe with respect to stent 90 and end portion 62 of graft 60 (see FIG. 33 ). | 4y
|
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an apparatus of fabricating a liquid crystal display, and more particularly to a unified strip/cleaning apparatus wherein a strip device is unified with a cleaning device.
[0003] 2. Description of the Related Art
[0004] Generally, since a liquid crystal display (LCD) has the advantages of small size, thin thickness and low power consumption, it has been used for a notebook personal computer, office automation equipment and audio/video equipment, etc. Particularly, an active matrix LCD using thin film transistors (TFT's) as switching devices is suitable for displaying a dynamic image.
[0005] An active matrix LCD displays a picture corresponding to a video signal such as a television signal on a picture element or pixel matrix having pixels arranged at each intersection between gate lines and data lines. Each pixel includes a liquid crystal cell controlling a transmitted light amount in accordance with a voltage level of a data signal from the data line. The TFT is installed at each intersection between the gate lines and the data lines to switch the data signal to be transmitted to the liquid crystal cell in response to a scanning signal from the gate line.
[0006] [0006]FIG. 1 shows a TFT formed on a substrate 18 . A process of fabricating the TFT will be described below. First, a gate electrode 20 and a gate line is deposited on the substrate 18 with a metal such as Al, Mo, Cr or their alloy, etc. and thereafter is patterned by the photolithography. A gate insulating film 22 made from an organic material such as SiN X or SiO X , etc. is deposited on the substrate 18 provided with the gate electrode 20 . Then, a semiconductor layer 24 made from an amorphous silicon (a-Si) layer and an ohmic contact layer 26 made from an a-Si doped with n+ ions are continuously deposited on the gate insulating film 22 . A source electrode 28 and a drain electrode 30 made from a metal such as Mo or Cr, etc. are formed on the ohmic contact layer 26 . The source electrode 28 is patterned integrally with the data line. The ohmic contact layer 26 exposed through an opening between the source electrode 28 and the drain electrode 30 is eliminated by dry etching or wet etching. A protective film 32 made from SiN X or SiO X is entirely deposited on the substrate 18 to cover the TFT. Subsequently, a contact hole is formed in the protective film 32 . A pixel electrode 34 made from an indium tin oxide (ITO) is coated so as to be connected, via the contact hole, to the drain electrode 30 . Such a TFT fabricating process includes a photoresist pattern formation step, an etching step and a photoresist pattern strip step, etc. upon the patterning of the electrode layers 20 , 28 and 30 or upon the formation of the contact hole.
[0007] [0007]FIG. 2 shows a conventional strip and cleaning apparatus. Referring to FIG. 2, the conventional strip and cleaning apparatus includes a loader 40 for loading a cassette (not shown) received with a substrate, a strip line for removing a photo-resistor (PR) of the substrate transported from the cassette, a cleaning line for cleaning the stripped substrate, a dry module 54 for drying the substrate cleaned by means of the cleaning line, and a unloader 56 for loading the substrate dried by means of the dry module 54 into the cassette that is arranged in an inline type. The loader 40 carries the substrate received in the cassette (not shown) into a first strip module 42 using a conveyor or a robot. The substrate from the loader 40 in which the PR formed on the TFT is removed by a pipe shower at the first strip module, is conveyed into a second strip module 44 . A stripper made from a mixture of H 3 PO 4 , CH 3 COOH and HNO 3 is used to remove the PR on the substrate. The second strip module 44 removes residual PR film that has not been removed at the first strip module 42 using a brush. The substrate having the PR film removed by physical cleaning is carried into a third strip module 46 . The third strip module 46 injects the stripper at a high pressure by a cavitation jet (CJ) system to remove the residual PR film on the substrate that has not been removed at the first and second strip modules 42 and 44 . The substrate stripped at the third strip module 46 is carried into an isopropyl alcohol (IPA) injecting module 48 . The IPA injecting module 48 removes minute alien substances and cleans the stripper using an IPA liquid. If the stripper and de-ionized water are mixed at a specific composition ratio, OH is produced to corrode aluminum (Al) formed on the surfaces of the source, drain and gate electrodes. Thus, the stripper is diluted with the IPA liquid so as to prevent the corrosion of aluminum. The substrate cleaned with the IPA liquid by means of the IPA injecting module 48 is carried into a first cleaning module 50 . The first cleaning module 50 cleans the substrate by a pipe shower using de-ionized water and thereafter carries it into a second cleaning module 52 . The second cleaning module 52 injects de-ionized water at a high pressure by the CJ system to clean the substrate. The substrate cleaned at the second cleaning module 52 is carried into a dry module 54 . The dry module 54 rotates the substrate using a centrifugal force of 1800 to 2200 rpm to remove the de-ionized water. The substrate dried at the dry module is received into the cassette on the unloader 56 .
[0008] Such conventional strip/cleaning equipment requires a wide installation space of 10840×1800 mm.
SUMMARY OF THE INVENTION
[0009] Accordingly, it is an object of the present invention to provide a unified strip/cleaning apparatus wherein a strip line is integrated with a cleaning line to minimize the installation space.
[0010] In order to achieve these and other objects of the invention, a unified strip/cleaning apparatus according to an embodiment of the present invention includes a strip line for removing resin on a substrate; and a cleaning line provided under the strip line to clean and dry the substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] These and other objects of the invention will be apparent from the following detailed description of the embodiments of the present invention with reference to the accompanying drawings, in which:
[0012] [0012]FIG. 1 is a section view showing the structure of a conventional thin film transistor;
[0013] [0013]FIG. 2 is a block diagram showing the configuration of a conventional strip and cleaning apparatus; and
[0014] [0014]FIG. 3 is a block diagram showing the configuration of a unified strip/cleaning apparatus according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0015] Referring to FIG. 3, there is shown a unified strip/cleaning apparatus according to an embodiment of the present invention in which a strip line and a cleaning line are stacked in a two-layer configuration. The present strip/cleaning apparatus includes a loader 60 for loading a cassette (not shown) received with a substrate, a strip line for removing a photo-resistor (PR) of the substrate transported from the cassette, a cleaning line for cleaning the stripped substrate, a dry module 74 for drying the substrate cleaned by means of the cleaning line, and a unloader 76 for loading the substrate dried by means of the dry module 54 into the cassette. The loader 60 is mounted with a desired number of cassettes, each of which is received with a plurality of substrates. The loader 60 plays the role of carrying the substrates received in the cassette (not shown) into a first strip module 62 using a conveyor or a robot. The substrate carried from the loader 60 into the first strip module 62 where the PR formed on the TFT is removed by a pipe shower is then conveyed into a second strip module 64 . Then, the substrate having the PR film further removed by the physical cleaning process is carried into a third strip module 66 . The third strip module 66 injects a stripper at a high pressure by a cavitation jet (CJ) system to remove residual PR film on the substrate that has not been previously removed at the first and second strip modules 62 and 64 . The substrate stripped at the third strip module 66 is carried into an isopropyl alcohol (IPA) injecting module 68 . The IPA injecting module 68 removes minute alien substances and cleans the stripper using an IPA liquid. The substrate cleaned with the IPA liquid by means of the IPA injecting module 68 is conveyed, via an elevator 69 , into a first cleaning module 70 . The first cleaning module 70 cleans the substrate by a pipe shower using de-ionized water and thereafter carries it into a second cleaning module 72 . The second cleaning module 72 injects de-ionized water at a high pressure utilizing the CJ system to clean the substrate. The substrate cleaned at the second cleaning module 72 is carried into a dry module 74 . The substrate cleaned at the second cleaning module 72 is carried into a dry module 74 . The substrate conveyed into the dry module 74 is rotated by a centrifugal force of 1800 to 2200 rpm to remove the de-ionized water. The substrate dried at the dry module 74 is received into the cassette on the unloader 76 .
[0016] As described above, the unified strip/cleaning apparatus according to the present invention is stacked to have a two-layer structure, so that the installation space can be minimized. Accordingly, the present unified strip/cleaning apparatus occupies a space of 5270×1800 mm that is equal to one-half of the space utilized in the prior art.
[0017] Although the present invention has been explained by the embodiments shown in the drawings described above, it should be understood to the ordinary skilled person in the art that the invention is not limited to the embodiments, but rather that various changes or modifications thereof are possible without departing from the spirit of the invention. | 4y
|
CROSS-REFERENCE TO RELATED APPLICATION
The present application is related to and claims priority from prior provisional application Ser. No. 61/686,315, filed Apr. 3, 2012 which application is incorporated herein by reference.
COPYRIGHT NOTICE
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 37 CFR 1.71(d).
BACKGROUND OF THE INVENTION
The following includes information that may be useful in understanding the present invention(s). It is not an admission that any of the information provided herein is prior art, or material, to the presently described or claimed inventions, or that any publication or document that is specifically or implicitly referenced is prior art.
1. Field of the Invention
The present invention relates generally to the field of USB holding devices and more specifically relates to a holding assembly for a USB flash/thumb drive.
2. Description of the Related Art
Today, USB flash drives are a popular and portable data storage device. A USB drive may be used in place of other storage mediums such as floppy disks, CDs, DVDs, zip drive disks, etc, and may conveniently fit in one's pocket. In most cases, the USB drive is a plug and play device that includes Flash memory for storing data and a USB connector for connecting to a host device. While these devices work well, they are limited in the operations that they can perform. These devices are only configured for storing and transporting stored data (similar to other portable storage mediums) and therefore they do not include processing components, batteries for powering the processing components, or a user interface that enable users to communicate with the processing components.
Due to growing use of flash drives and thumb drives in today's technology-fueled era, it is important that USB drives are conveniently accessible throughout the day. Often times, people forget to take their USB drive with them because it is not yet considered an essential item (such as a wallet, cell phone, keys). As such, people may often discover that a USB drive would be extremely handy in unanticipated situations. However, because it is quite easy to forget a USB drive since they are small, lightweight, and inexpensive, it is not uncommon to be without a USB drive when such an unanticipated situation arises.
Various attempts have been made to solve the above-mentioned problems such as those found in U.S. Pat. and Pub. Nos. 2012/0239836 to Babak Enayati; U.S. Pat. No. 8,316,492 to Launce R. Barber; U.S. Pat. No. 7,500,858 to Brandon Emerson et al; U.S. Pat. No. 7,630,204 to Itzhak Pomerantz; U.S. Pat. No. 7,544,073 to David Nguyen et al; and U.S. Pat. No. D522,519 to Bennett S. Rubin et al. This prior art is representative of flash drive grips having an attachment mechanism to a key ring. None of the above inventions and patents, taken either singly or in combination, is seen to describe the invention as claimed.
Ideally, a flash grip system should provide a retro-installable holding assembly for a USB flash/thumb drive which may comprise a grip having an article-fastening clip attached thereto so that the flash drive may be easily attached to a belt loop, purse strap, key chain, brief case, etc., for convenient accessibility. Thus, a need exists for a reliable flash grip system and to avoid the above-mentioned problems.
BRIEF SUMMARY OF THE INVENTION
In view of the foregoing disadvantages inherent in the known USB flash drive holding grip art, the present invention provides a novel flash grip system comprising a flash grip assembly which may include a rectangular gripping strip, a pair of USB drive attachers, and a clip fastener for clipping the rectangular gripping strip holding a USB drive to a separate article or object.
The general purpose of the present invention, which will be described subsequently in greater detail, is to provide a “FLASH GRIP” with carabiner snap hook key ring which allows a flash drive to be easily attached to a belt loop, purse strap, brief case, etc., for convenient accessibility. As an added feature, the sides may be trimmed for a “custom fit” to various sized USB thumb drives.
Flash grip systems are disclosed herein in a preferred embodiment comprising a flash grip assembly, which may comprise a rectangular strip with dimensions of approximately 1½″ width by 4″ height manufactured of a pliable material comprising a foam sheet or other suitable pliable material. The foam sheet may provide a cushiony, ergonomic surface. Further, the rectangular strip has a first-end, a mid-point, and a second-end. The flash grip assembly further comprises a first-attacher preferably comprising a first-adhesive, a second-attacher preferably comprising a second-adhesive, a first-eyelet and a second-eyelet, an article-fastener comprising a carabineer clip, and an article-fastener-securer comprising a loop.
Relationally, the first-end of the rectangular strip is connected to the mid-point, and the mid-point of the rectangular strip is connected to the second-end. The first-end comprises the first-attacher, and the second-end comprises the second-attacher. The first-eyelet and the second-eyelet each may comprise a through-hole. The first-eyelet and the second-eyelet may each comprise a ring about a perimeter of the through-holes for providing a buffer between the article-fastener-securer and the pliable (foam) material of the rectangular strip. Further, the first-eyelet is located between the first-end and the mid-point of the rectangular strip, and the second-eyelet is located between the second-end and the mid-point of the rectangular strip. The rectangular strip is foldable in half about the mid-point such that the first-eyelet and the second-eyelet line up evenly.
The article-fastener-securer may comprise a loop, which may pass through the first-eyelet and the second-eyelet when the rectangular strip is folded in half. The loop is interconnected to the article-fastener. The article-fastener is fastenable to a clippable-article, such as a keychain, a strap of a carrying bag, a brief case, a backpack, a belt loop, or the like.
In the preferred embodiment, the rectangular strip may or may not comprise at least one decoration. The decoration may comprise an adornment (such as a design, insignia, jewel, picture, etc). In use, the flash grip system decorates to personalize the USB flash drive, thereby protecting the USB flash drive from abrasive damage, and improves portability of the USB flash drive via the article-fastener of the flash grip assembly. As such the present invention is convenient to ‘take along’ and its design causes it to be remembered.
A method of use for a flash grip system is also disclosed herein and may comprise the steps of: removing an adhesive sheet from a first-attacher of a first-end of a rectangular strip; placing a USB flash drive on an adhesive surface of the first adhesive; removing the adhesive sheet from a second adhesive of a second-end of the rectangular strip; folding the rectangular strip in half along a mid-point and pressing firmly the second-end of the rectangular strip on the USB flash drive; and attaching the flash grip system to a clippable article via the article-fastener. The method of use may further comprise the optional step of customizing the size of the rectangular strip to best fit the USB flash drive.
The present invention holds significant improvements and serves as a flash grip system. For purposes of summarizing the invention, certain aspects, advantages, and novel features of the invention have been described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any one particular embodiment of the invention. Thus, the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. The features of the invention which are believed to be novel are particularly pointed out and distinctly claimed in the concluding portion of the specification. These and other features, aspects, and advantages of the present invention will become better understood with reference to the following drawings and detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The figures which accompany the written portion of this specification illustrate embodiments and method(s) of use for the present invention, flash grip systems, constructed and operative according to the teachings of the present invention discussed herein.
FIG. 1 shows a perspective view illustrating a user sitting at a desk using a computer showing a flash grip system in an ‘in-use’ condition holding a USB flash drive according to an embodiment of the present invention.
FIG. 2A is a perspective view of a top portion of the flash grip system comprising a rectangular strip having a carabineer clip according to an embodiment of the present invention of FIG. 1 .
FIG. 2B is a perspective view a bottom portion of the flash grip system comprising a pair of adhesive-based fasteners for attaching the rectangular strip to the USB flash drive according to an embodiment of the present invention of FIG. 1 .
FIGS. 3A-3D are perspective views showing how the flash grip system may conveniently be applied to the USB flash drive according to an embodiment of the present invention of FIG. 1 .
FIG. 4A is a perspective view illustrating the flash grip system used to attach the USB flash drive to a keychain according to an embodiment of the present invention of FIG. 1 .
FIG. 4B is a perspective view illustrating the flash grip system used to attach the USB flash drive to a belt loop of a pair of pants according to an embodiment of the present invention of FIG. 1 .
FIG. 4C is a perspective view illustrating the flash grip system used to attach the USB flash drive to a strap of a handbag according to an embodiment of the present invention of FIG. 1 .
FIG. 5 is a flowchart illustrating a method of use of the flash grip system according to an embodiment of the present invention of FIGS. 1-4C .
The various embodiments of the present invention will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements.
DETAILED DESCRIPTION
As discussed above, embodiments of the present invention relate to a flash grip system and more particularly to a retro-installable holding assembly for a USB flash/thumb drive which may comprise a grip having an article-fastening clip attached thereto so that the flash drive may be easily attached to a belt loop, purse strap, key chain, brief case, etc., for convenient accessibility.
Generally speaking, the flash grip system may comprise a “FLASH GRIP” with carabineer snap hook key ring which allows a flash drive to be easily attached to a belt loop, purse strap, brief case, etc., for convenient accessibility. As an added feature, the sides may be trimmed for a “custom fit” to various sized USB thumb drives.
Referring now to the drawings by numerals of reference there is shown in FIG. 1 , flash grip system 100 during ‘in-use’ condition 150 according to an embodiment of the present invention.
As shown, flash grip system 100 may comprise flash grip assembly 102 . Flash grip assembly 102 may comprise rectangular strip 200 having first-end 202 , mid-point 204 , and second-end 206 , first-attacher 225 , second-attacher 230 , first-eyelet 215 , second-eyelet 220 , article-fastener 120 , and article-fastener-securer 125 . Flash grip system 100 may be used to hold USB flash drive 110 such that USB flash drive 110 is fastenable to a clippable-article via article-fastener 120 of flash grip assembly 102 . By way of example as illustration in FIG. 1 , flash grip systems 100 during ‘in-use’ condition 150 may be used by user 140 to attach USB flash drive 110 to keychain 105 also holding keys 115 . As shown, USB flash drive 110 may be inserted into a USB port on a computer, such as laptop 130 , while USB flash drive 110 is still attached to keychain 105 . In such a manner, user 140 has improved accessibility to USB flash drive 110 as it is conveniently available in keychain 105 .
Referring now to FIG. 2A showing a perspective view of a top portion of flash grip systems 100 comprising rectangular strip 200 having carabineer clip 260 attached thereto according to an embodiment of the present invention of FIG. 1 . As discussed, rectangular strip 200 comprises first-end 202 , mid-point 204 , and second-end 206 . As shown in FIG. 2A , first-end 202 of rectangular strip 200 is connected to mid-point 204 and mid-point 204 is connected to second-end 206 of rectangular strip 200 .
In continuing to refer to FIG. 2A , flash grip systems 100 may further comprise first-eyelet 215 and second-eyelet 220 . First-eyelet 215 and second-eyelet 220 may each comprise a through-hole. Further, first-eyelet 215 and second-eyelet 220 may each comprise a ring around a perimeter of the through-holes thereby providing a buffer between article-fastener-securer 125 and rectangular strip 200 .
First-eyelet 215 is located between first-end 202 and mid-point 204 of rectangular strip 200 , and second-eyelet 220 is located between second-end 206 and mid-point 204 of rectangular strip 200 . Preferably, first-eyelet 215 and second-eyelet 220 are orientated on rectangular strip 200 such that when rectangular strip 200 is folded in half about mid-point 204 , the through-holes of first-eyelet 215 and second-eyelet 220 line up evenly, thereby enabling article-fastener-securer 125 to pass there-through. In one embodiment as shown in FIGS. 2A and 2B , article-fastener-securer 125 may comprise a loop. The loop of may pass through first-eyelet 215 and second-eyelet 220 when rectangular strip 200 is folded in half. Further, article-fastener-securer 125 is interconnected to article-fastener 120 , and article-fastener 120 is fastenable to a clippable-article.
In a preferred embodiment, rectangular strip 200 may comprise dimensions of approximately 1½ inch width by 4 inches height. However, it should be appreciated that rectangular strip 200 may comprise smaller or larger dimensions to fit USB flash drive 110 of varying sizes. Rectangular strip 200 may be formed of a pliable material. In one embodiment, rectangular strip 200 may comprise a foam sheet. The foam sheet may provide a lightweight, cushiony, ergonomic surface for holding flash grip system 100 . However, it should be noted that rectangular strip 200 may also be formed of leather, felt, vinyl, plastic, or a lightweight metal material.
In still referring to FIG. 2A , rectangular strip 200 may comprise decorative indicia 210 . In one embodiment, decorative indicia 210 may comprise indicia such as a picture, an insignia, or the like. In other embodiments, decorative indicia 210 may comprise an adornment, such as a jewel, gem, or other artistic construction such that the present invention is more likely to be remembered for ‘taking it along’ when travelling. It should be appreciated that flash grip systems 100 decorates to personalize USB flash drive 110 , protects USB flash drive 110 from abrasive damage, and improves portability of USB flash drive 110 via article-fastener 120 of flash grip assembly 102 .
Referring now to FIG. 2B showing a perspective view of a bottom portion (inside in relation to the USB when attached thereto) of rectangular strip 200 according to an embodiment of the present invention of FIG. 1 . As shown, first-end 202 of rectangular strip 200 comprises first-attacher 225 and second-end 206 of rectangular strip 200 comprises second-attacher 230 . As may best be seen in FIG. 2B , first-attacher 225 may be fixedly attached to first-end 202 of rectangular strip 200 via first-attacher fastener 227 and second-attacher 230 may be fixedly attached to second-end 206 of rectangular strip 200 via second-attacher fastener 232 . In one embodiment, first-attacher fastener 227 and second-attacher fastener 232 may each comprise hook-and-loop fasteners. In alternative embodiments, first-attacher fastener 227 and second-attacher fastener 232 may comprise a bonding substance (high-grade glue, adhesive, or the like).
In continuing to refer to FIG. 2B , article-fastener 120 of flash grip assembly 102 may comprise carabineer clip 260 . Carabineer clip 260 may comprise a metal loop with a sprung gate used to quickly and reversibly connect components. This type of clip is useful for easily connecting and disconnecting clippable-articles to article-fastener 120 . In other embodiments, article-fastener 120 may comprise a ring fastener, connectors, or the like.
Referring now to FIGS. 3A-3D illustrating perspective views showing how the flash grip system 100 may conveniently be applied to USB flash drive 110 according to an embodiment of the present invention. As shown in FIG. 3A , user 140 may first peel off a top layer of first-attacher 225 of rectangular strip 200 revealing adhesive surface 305 . As shown in FIG. 3B , user 140 may next place USB flash drive 110 in a middle area of adhesive surface 305 of first-attacher 225 . It should be noted that USB flash drive 110 should be positioned such that the input port is facing outward from first-end 202 of rectangular strip 200 . Next, as shown in FIG. 3C , user 140 may peel off a top layer of second-attacher 230 revealing adhesive surface 305 . User 140 may then fold rectangular strip 200 constructed if a pliable material in half about mid-point 204 such that adhesive surface 305 of second-attacher 230 comes into contact with USB flash drive 110 . Next, as shown in FIG. 3D , user 140 may apply a downward force onto second-end 206 of rectangular strip 200 , thereby adhering adhesive surface 305 of first-attacher 225 and second-attacher 230 to USB flash drive 110 .
Referring now to FIG. 4A showing a perspective view illustrating flash grip systems 100 used to attach USB flash drive 110 to keychain 105 according to an embodiment of the present invention of FIG. 1 . As shown, flash grip assembly 102 comprising rectangular strip 200 having decorative indicia 210 and retains USB flash drive 110 during ‘in-use’ condition 450 via first-attacher 225 and second-attacher 230 . As shown, article-fastener 120 comprising carabineer clip 260 may attach to keychain 105 having a plurality of keys 115 . In such a manner, USB flash drive 110 is taken whenever user 140 takes keychain 105 which likely has essential keys 115 .
Referring now to FIG. 4B showing a perspective view illustrating flash grip systems 100 used to attach USB flash drive 110 to belt loop 412 of pants 410 worn by user 140 according to an embodiment of the present invention. As shown, clippable-article may comprise belt loop 412 . In such a manner, article-fastener 120 comprising carabineer clip 260 may be removably fastenable to belt loop 412 of pants 410 . As such, user 140 may comfortably and conveniently carry USB flash drive 110 attached to belt loop 412 for easy accessibility to USB flash drive 110 throughout the day.
Referring now to FIG. 4C showing a perspective view illustrating flash grip systems 100 used to attach USB flash drive 110 to strap 422 of handbag 420 according to an embodiment of the present invention of FIG. 1 . As shown, clippable-article may comprise strap 422 of handbag 420 . It should be appreciated that strap 422 may also be a brief-case, luggage, backpack, carrying bag, or the like. In such a manner, article-fastener 120 comprising carabineer clip 260 may be removably fastenable to strap 422 of handbag 420 for convenient access to USB flash drive 110 throughout the day. A kit may comprise the present invention with an assortment of decorative indicia 210 .
Referring now to FIG. 5 , showing flowchart 550 illustrating method of use 500 according to an embodiment of the present invention of FIGS. 1-4C . Method of use 500 for flash grip systems 100 may comprise the steps of: step one 501 , removing an adhesive sheet from first-attacher 225 of first-end 202 of a rectangular strip 200 ; step two 502 , placing USB flash drive 110 on adhesive surface 305 of first-attacher 225 ; step three 503 , removing an adhesive sheet from second-attacher 230 of second-end 206 of rectangular strip 200 ; step four 504 , folding rectangular strip 200 in half along mid-point 204 and pressing firmly second-end 206 of rectangular strip 200 on USB flash drive 110 ; and step five 505 attaching flash grip assembly 102 to a clippable article via article-fastener 120 .
In continuing to refer to FIG. 5 , method of use 500 may further comprise the optional step of customizing the size of rectangular strip 200 . This may be accomplished by cutting the sides of rectangular strip 200 such that rectangular strip 200 does not overlay on USB flash drive 110 .
It should be noted that the steps described in the method of use can be carried out in many different orders according to user preference. Upon reading this specification, it should be appreciated that, under appropriate circumstances, considering such issues as design preference, user preferences, marketing preferences, cost, structural requirements, available materials, technological advances, etc., other methods of use arrangements such as, for example, different orders within above-mentioned list, elimination or addition of certain steps, including or excluding certain maintenance steps, etc., may be sufficient.
The embodiments of the invention described herein are exemplary and numerous modifications, variations and rearrangements can be readily envisioned to achieve substantially equivalent results, all of which are intended to be embraced within the spirit and scope of the invention. Further, the purpose of the foregoing abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientist, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. | 4y
|
FIELD OF THE INVENTION
This invention relates to a chemical process and apparatus for producing inorganic fullerene-like nanoparticles.
LIST OF REFERENCES
The following references are considered to be pertinent for the purpose of understanding the background of the present invention:
1. L. Rapoport, Yu. Bilik, Y. Feldman, M. Homyonfer, S. Cohen and R. Tenne, Nature, 1997, 387, 791; 2. C. Schffenhauer, R. Popovitz-Biro, and R. Tenne, J. Mater. Chem. 2002, 12, 1587-1591 3. Jun. Chen, Suo-Long Li, Zhan-Liang Tao and Feng Gao, Chem. Commun. 2003, 980-981; 4. WO 97/44278; 5. Y. Feldman, V. Lyalkhovitskaya and R. Tenne, J. Am. Chem. Soc. 1998, 120, 4176; 6. A. Zak, Y. Feldman, V. Alperovich, R. Rosentsveig and R. Tenne, J. Am. Chem. Soc. 2000, 122, 11108; 7. Y. Feldman, A. Zak, R. Popovitz-Biro, R. Tenne, Solid State Sci. 2000, 2, 663; 8. WO 01/66462; 9. WO 02/34959; 10. Xiao-Lin Li, Jian-Ping Ge and Ya-Dong Li, Chem. Eur. J. 2004, 10, 6163-6171; and 11. T. Tsirlina and V. Lyaldiovitskaya, S. Fiechter, and R. Tenne, J. Mater. Res. 2000, 15, 2636-2646.
BACKGROUND OF THE INVENTION
Carbon nanoparticles having a layered configuration are known as fullerene nanoparticles. Generally, there are three main types of fullerene-related carbon particles: fullerenes (C 60 , C 70 , etc.); nested-fullerene nanoparticles (in the form of onions), and nanotubes. Analogous fullerene-like nanoparticles can be obtained from a number of inorganic materials with layered structure, and are known as inorganic fullerene-like materials.
Inorganic fullerene-like (abbreviated hereinafter “IF”) nanoparticles and nanotubes are attractive due to their unique crystallographic morphology and their interesting physical properties.
Layered transition-metal dichalcogenides MS 2 (such as WS 2 and MoS 2 ) are of great interest as they act as host lattices by reacting with a variety of guest atoms or molecules to yield intercalation compounds, in which the guest is inserted between the host layers. Accordingly, IF transition metal dichalcogenides may be used for instance, for hydrogen storage.
Furthermore, disulfides of molybdenum and tungsten belong to a class of solid lubricants useful in vacuum, space and other applications where liquids are impractical to use. IF nanoparticles can be used as additives to various kinds of oils and greases to enhance their tribological behavior 1 . Furthermore, different coatings with impregnated IF nanoparticles were shown to exhibit self-lubricating behavior.
IF nanoparticles may also be used for other possible applications such as battery cathodes, catalysis, nanoelectronic and magnetic information storage.
The first closed-cage fullerene-like nanoparticles and nanotubes of WS 2 were obtained via sulfidization of thin films of the respective trioxides in 1992, followed by MoS 2 and the respective diselenides.
Numerous IF nanostructures have been synthesized using different metodologies. The first report related to IF-MS 2 (IF-NbS 2 ) structures obtained by the reaction of the metal chloride (NbCl 5 ) and H 2 S 2 . Later on, Jun Chen et al. 3 used a low-temperature gas reaction to synthesize TiS 2 nanotubes. The reaction involved heating TiCl 4 , H 2 , and H 2 S inside a horizontal furnace at a relatively low temperature of 450° C. and in the absence of oxygen and water.
Another method and apparatus for preparing inorganic fullerene-like nanoparticles of a metal, e.g. transition metal chalcogenide having a desired size and shape in high yields and macroscopic quantities, is described in WO 97/44278 4 . This method utilizes (a) dispersing solid particles of at least one non-volatile metal oxide material having the preselected size and shape; and (b) heating the solid particles of the non-volatile metal material in a reducing gaseous atmosphere containing at least one chalcogen material for a time and a temperature sufficient to allow the metal material precursor and the chalcogen material to react and form at least one layer of metal chalcogenide, the at least one layer of metal chalcogenide encaging the surface of the solid particles to form the fullerene-like particles.
The synthesis of IF-WS 2 involves a solid-gas reaction, where the nanocrystalline tungsten oxide, serving as a precursor, reacts with H 2 S gas at elevated temperatures 5 . In a different procedure, IF-MoS 2 nanoparticles are prepared in the gas phase, upon in-situ reduction and condensation of the MoO 3 vapor and subsequent sulfidization by H 2 S 6 .
The availability of fullerene-like MoS 2 and WS 2 nanoparticles in large amounts paved the way for a systematic investigation of their properties. Both IF-WS 2 and IF-MoS 2 nanoparticles were found to provide beneficial tribological behavior under harsh conditions 1 , suggesting extensive number of tribological applications for these nanoparticles, eliciting substantial industrial interest.
Mass production of IF-WS 2 was enabled by the construction of first a falling bed and subsequently fluidized bed reactors 7 .
Reactors for mass production of IF-WS 2 and IF-MoS 2 are described in WO 01/66462 and WO 02/34959, respectively 8,9 .
The reported IF-WS 2 and IF-MoS 2 5-7 were synthesized from their corresponding oxide crystallite that served as a template for the growth of the sulfide nanoparticles. The growth of the sulfide layers in each particle starts on the top surface of the partially reduced oxide nanoparticle terminating in its core. This diffusion-controlled reaction is rather slow, lasting a few hours. The final nanoparticles consist of dozens of sulfide layers and a hollow core occupying 5-10% of the total volume of the nanoparticles.
In another research, large-scale MoS 2 and WS 2 IF nanostructures (onion-like nanoparticles and nanotubes) and three-dimensional nanoflowers were selectively prepared through an atmospheric pressure chemical vapor deposition process from metal chlorides (e.g. MoCl 5 and WCl 6 ) and sulfur 10 . In this technique, selectivity was achieved by varying the reaction temperature, with 750° C. favoring the nanotubes and 850° C. the fullerene-like nanoparticles.
In a further research, tungsten diselenide closed-cage nanoparticles were synthesized by the reaction of prevaporized Se with WO 3 powder in a reducing atmosphere 11 . The selenium vapor was brought to the main reaction chamber by a carrier gas. The growth mechanism of the IF-WSe 2 nanoparticles was outside-in. This growth mode is analogous to the previously reported growth of IF-WS 2 using the reaction between WO 3 nanoparticles and H 2 S gas 5 .
SUMMARY OF THE INVENTION
There is a need in the art to facilitate production of inorganic fullerene-like particles by providing a novel process and apparatus with improved capability to control the shape and size of the structure being produced. Also, there is a need in the art to produce nanoparticles having spherical shape, thus having improved properties, such as tribological, optical, etc.
It was found by the inventors that the known mechanisms for the synthesis of IF-WS 2 from metal trioxide powder and the synthesis of IF-MoS 2 from the evaporated metal trioxide, are not suitable for other metals such as titanium. For instance, the titanium dioxide can not be easily sulfidized even at the relatively high temperature of up to 1450° C. Also, although the sulfidization of tungsten or molybdenum dioxide results in respective disulfide, the desired morphology of the particle is not obtained.
Furthermore, the inventors have found a more rapid way for making the synthesis of IF nanoparticles that yields a desired spherical shape and a relatively narrow size distribution of produced nanoparticles. The IF nanoparticles synthesized by the technique of the present invention have smaller hollow core (substantially not exceeding 5-10 nm) and they contain many more layers (typically, 50-120 layers) as compared to those synthesized from the metal oxides, which have a relatively large hollow core (more than 20 nm) and fewer number of layers (20-40). Therefore, the presently synthesized IF nanoparticles are expected to reveal improved tribological behavior, which is confirmed by preliminary measurements.
Thus, the present invention provides a process for producing inorganic fullerene-like (IF) nanoparticles having well defined size and shape, from commercially available reactants and in a rather fast reaction. The large number of molecular layers, i.e. 50-120 in the present synthesis is advantageous for tribological applications where the lifetime of the Nan particle is determined by the gradual deformation and peeling-off of the outer layers of the nanoparticle.
The process of the present invention occurs in the gas phase, and is suitable for mass production of inorganic fullerene-like nanoparticles of metal chalcogenides. The process is based on a reaction between a metal precursor, e.g. metal halide, metal oxyhalide, metal carbonyl or organo-metallic compound (hereinafter termed “metal containing precursor” or “metal precursor”) and a reacting agent, e.g. chalcogen material, both in the gas phase. The use of metal carbonyls, for example, has the advantage that its decomposition in the reactor leads to the release of CO which is a strongly reducing agent and allows to overcome the sensitivity of this reaction to oxidizing atmosphere.
Thus according to a first aspect thereof, the present invention provides a process for producing inorganic fullerene-like (IF) metal chalcogenide nanoparticles, the process comprising:
(a) feeding a metal precursor selected from metal halide, metal carbonyl, organo-metallic compound and metal oxyhalide vapor into a reaction chamber towards a reaction zone to interact with a flow of at least one chalcogen material in gas phase, the temperature conditions in said reaction zone being such as to enable the formation of the inorganic fullerene-like (IF) metal chalcogenide nanoparticles.
According to a preferred embodiment, the process comprises:
(b) controllably varying the flow of said metal precursor into said reaction chamber to control the amount, shape and size of the so-produced IF fullerene-like metal chalcogenide nanoparticles in solid form.
Preferably, the vapor of the metal precursor is fed into the reaction chamber to flow towards the reaction zone along a vertical path, e.g. along an upward/downward direction that is opposite with respect to that of the chalcogen material that is being fed in a downward/upward direction.
The nanoparticles produced by the process of the invention are characterized by narrow size distribution and large number of molecular layers.
The invention also provides IF metal chalcogenide nanoparticles having a plurality of molecular layers and characterized in that the number of said molecular layers exceeds 40, preferably exceeds 50 and at times exceeds 60 and even 70 layers. According to one embodiment of the invention there is provided a product comprising a plurality of IF metal chalcogenide nanoparticles, a substantial portion of which having a number of molecular layers exceeding 40, preferably exceeds 50 and at times exceeds 60 and even 70 layers. The substantial portion is typically more than 40% out of the nanoparticles, preferably more than 50%, 60%, 70%, 80% and at times even more than 90% out of the total number of the IF nanoparticles.
Furthermore, the IF fullerene-like metal chalcogenide nanoparticles produced by the process of the present invention optionally have no hollow core or a very small hollow core (not exceeding 5-10 nm).
The term “very small hollow core” as used herein means that the nanoparticles produced by the process of the present invention have a hollow core which is not exceeding 5 nm or occupying no more than 0-5% of the total volume of the nanoparticles.
The term “nanoparticles” as used herein refers to multi-layered, spherical, or close to spherical particle having a diameter in the range from about 10 nm to about 300 nm, preferably from about 30 nm to about 200 nm. The nanoparticles of the invention may typically have 50-120 concentric molecular layers.
The nanoparticles obtained by the process of the present invention have a spherical or close to spherical shape and optionally have no hollow core. The provision of a very small hollow core or even absence of such core may be explained by the mechanism of growth of the nanoparticles, namely from the central portion (nucleai of product) towards the peripheral portion, rather than the opposite direction carried out in the known processes.
Preferably, the term “mental” as used herein refers to In, Ga, Sn or a transition metal.
A transition metal includes all the metals in the periodic table from titanium to copper, from zirconium to silver and from hafnium to gold. Preferably, the transition metals are selected from Mo, W, V, Zr, Hf, Pt, Pd, Re, Nb, Ta, Ti, Cr and Ru.
A chalcogen used in the invention is S, Se or Te, and the chalcogen material is selected from a chalcogen, a compound containing a chalcogen, a mixture of chalcogens, a mixture of compounds containing a chalcogen, and a mixture of a chalcogen and a compound containing a chalcogen.
The chalcogen material is preferably a chalcogen compound containing hydrogen, more preferably H 2 S, H 2 Se and/or H 2 Te. Alternatively, instead of H 2 X (X=S, Se, Te) it is possible to use elemental chalcogen under the flow of hydrogen with H 2 X being formed in-situ during the reaction time. The chalcogen material may optionally be mixed with a reducing agent such as hydrogen and/or Co.
In a preferred embodiment of the invention, an inert carrier gas is used to drive a flow of the chalcogen material and a flow of the vaporized metal precursor into the reaction chamber. Non limiting examples of inert gases that may be used in the process of the present invention are N 2 , He, Ne, Ar, Kr and Xe.
The term “precursor” as used herein means any suitable starting material or materials. The precursor in the process of the present invention may be any metal containing compound that can be vaporized without or with its decomposition. Suitable metal containing precursors that may be used in the process of the present invention are, for example, metal halides, metal carbonyls, organo-metallic compounds and metal oxyhalides. More specific examples of metal containing precursors that may be used in the process of the present invention are TiCl 4 , WCl 6 , WCl 5 , WCl 4 , WBr 5 , WO 2 Cl 2 , WOCl 4 , MoCl 5 , Mo(CO) 5 and W(CO) 6 , Ga(CH 3 ) 3 , W(CH 2 CH 3 ) 5 , In(CH 3 ) 3 and the like.
A list of metal precursor compounds that can be used in the process of the present invention is given in Table 1 below.
TABLE 1
Examples of metal precursors
Name
Formula
mp, ° C.
bp, ° C.
Chromium carbonyl
Cr(CO) 6
130 (dec)
subl
Chromium (III) iodide
CrI 3
500 (dec)
Chromium (IV) chloride
600 (dec)
Chromium (IV) fluoride
CrF 4
277
Chromium (V) fluoride
CrF 5
34
117
Chromium (VI) fluoride
CrF 6
100 (dec)
Cromyl chloride
CrO 2 Cl 2
−96.5
117
Trimethylgallium
Ga(CH 3 ) 3
−15.8
55.7
Hafnium bromide
HfBr 4
424 (tp)
323 (sp)
Hafnium chloride
HfCl 4
432 (tp)
317 (sp)
Hafnium iodide
HfI 4
449 (tp)
394 (sp)
Trimethylindium
In(CH 3 ) 3
88
133.8
Molybdenum carbonyl
Mo(CO) 6
150 (dec)
subl
Molybdenum (V) chloride
MoCl 5
194
268
Molybdenum (V) fluoride
MoF 5
67
213
Molybdenum (V)
MoOCl 3
297
subl
oxytrichloride
Molybdenum (VI) fluoride
MoF 6
17.5
34
Molybdenum (VI)
MoOF 4
98
oxytetrafluoride
Molybdenum (VI)
MoOCl 4
101
oxytetrachloride
Molybdenum (VI)
MoO 2 Cl 2
175
dioxydichloride
Niobium (IV) chloride
NbCl 4
Niobium (IV) fluoride
NbF 4
350 (dec)
Niobium (IV) iodide
NbI 4
503
Niobium (V) bromide
NbBr 5
254
360
Niobium (V) chloride
NbCl 5
204.7
254
Niobium (V) fluoride
NbF 5
80
229
Niobium (V) iodide
NbI 5
200 (dec)
Niobium (V) oxybromide
NbOBr 3
320 (dec)
subl
Niobium (V) oxychloride
NbOCl 3
subl
Niobium (V) dioxyfluoride
NbO 2 F
Palladium (II) bromide
PdBr 2
250 (dec)
Palladium (II) iodide
PdI 2
360 (dec)
Platinum (II) bromide
PtBr 2
250 (dec)
Platinum (II) chloride
PtCl 2
581 (dec)
Platinum (II) iodide
PtI 2
325 (dec)
Platinum (III) bromide
PtBr 3
200 (dec)
Platinum (III) chloride
PtCl 3
435 (dec)
Platinum (IV) bromide
PtBr 4
180 (dec)
Platinum (IV) chloride
PtCl 4
327 (dec)
Platinum (IV) fluoride
PtF 4
600
Platinum (IV) iodide
PtI 4
130 (dec)
Platinum (VI) fluoride
PtF 6
61.3
69.1
Rhenium carbonyl
Re 2 (CO) 10
170 (dec)
Rhenium (III) bromide
ReBr 3
500 (subl)
Rhenium (III) chloride
ReCl 3
500 (dec)
Rhenium (III) iodide
ReI 3
(dec)
Rhenium (IV) chloride
ReCl 4
300 (dec)
Rhenium (IV) fluoride
ReF 4
300 (subl)
Rhenium (V) bromide
ReBr 5
110 (dec)
Rhenium (V) chloride
ReCl 5
220
Rhenium (V) fluoride
ReF 5
48
220
Rhenium (VI) chloride
ReCl 6
29
Rhenium (VI) fluoride
ReF 6
18.5
33.7
Rhenium (VI)
ReOCl 4
29.3
223
oxytetrachloride
Rhenium (VI)
ReOF 4
108
171
oxytetrafluoride
Rhenium (VII) fluoride
ReF 7
48.3
73.7
Rhenium (VII) trioxycloride
ReO 3 Cl
4.5
128
Rhenium (VII)
ReO 3 F
147
164
trioxyfluoride
Rhenium (VII)
ReO 2 F 3
90
185
dioxytrifluoride
Rhenium (VII)
ReOF 5
43.8
73
oxypentafluoride
Ruthenium dodecacarbonyl
Ru 3 (CO) 12
150 (dec)
Ruthenium (III) bromide
RuBr 3
400 (dec)
Ruthenium (III) chloride
RuCl 3
500 (dec)
Ruthenium (III) fluoride
RuF 3
600 (dec)
Ruthenium (III) iodide
RuI 3
Ruthenium (IV) fluoride
RuF 4
86.5
227
Ruthenium (V) fluoride
RuF 5
54
Tantalum (V) bromide
TaBr 5
265
349
Tantalum (V) chloride
TaCl 5
216
239.35
Tantalum (V) fluoride
TaF 5
95.1
229.2
Tantalum (V) iodide
TaI 5
496
543
Titanium (III) bromide
TiBr 3
Titanium (III) chloride
TiCl 3
425 (dec)
Titanium (IV) bromide
TiBr 4
39
230
Titanium (IV) chloride
TiCl 4
−25
136.45
Titanium (IV) fluoride
TiF 4
284
subl
Titanium (IV) iodide
TiI 4
150
377
Tungsten carbonyl
W(CO) 6
170 (dec)
subl
Tungsten (II) bromide
WBr 2
400 (dec)
Tungsten (II) chloride
WCl 2
500 (dec)
Tungsten (II) iodide
WI 2
Tungsten (III) bromide
WBr 3
80 (dec)
Tungsten (III) chloride
WCl 3
550 (dec)
Tungsten (V) bromide
WBr 5
286
333
Tungsten (V) chloride
WCl 5
242
286
Tungsten (V) fluoride
WF 5
80 (dec)
Tungsten (V) oxytribromide
WOBr 3
Tungsten (V) oxytrichloride
WOCl 3
Tungsten (VI) bromide
WBr 6
309
Tungsten (VI) chloride
WCl 6
275
246.75
Tungsten (VI)
WO 2 Br 2
dioxydibromide
Tungsten (VI)
WO 2 Cl 2
265
dioxydichloride
Tungsten (VI)
WO 2 I 2
dioxydiiodide
Tungsten (VI) fluoride
WF 6
2.3
17
Tungsten (VI)
WOBr 4
277
327
oxytetrabromide
Tungsten (VI)
WOCl 4
211
227.55
oxytetrachloride
Tungsten (VI)
WOF 4
106
186
oxytetrafluoride
Vanadium carbonyl
V(CO) 6
60 (dec)
subl
Vanadium (IV) chloride
VCl 4
−25.7
148
Vanadium (IV) fluoride
VF 4
325 (dec)
subl
Vanadium (V) fluoride
VF 5
19.5
48.3
Vanadyl bromide
VOBr
480 (dec)
Vanadyl chloride
VOCl
700 (dec)
Vanadyl dibromide
VOBr 2
180 (dec)
Vanadyl dichloride
VOCl 2
380 (dec)
Vanadyl difluoride
VOF 2
Vanadyl tribromide
VOBr 3
180 (dec)
Vanadyl trichloride
VOCl 3
−79
127
Vanadyl trifluoride
VOF 3
300
480
Zirconium chloride
ZrCl 4
437 (tp)
331 (sp)
Zirconium fluoride
ZrF 4
932 (tp)
912 (sp)
Zirconium iodide
ZrI 4
499 (tp)
431 (sp)
Abbreviations:
(dec)—decomposes
(sp)—sublimation point
(subl)—sublimes
(tp)—triple point
According to a preferred embodiment of the invention, the process further comprises at least one, preferably both of the following steps:
(c) terminating the feeding of the metal precursor vapor into the reaction chamber by stopping heating of the metal precursor;
(d) cooling the reaction zone and collecting the obtained fullerene-like metal chalcogenide nanoparticles.
In another preferred embodiment, the process may comprise driving a flow of an inert gas into the reaction zone after step (c) and before step (d).
In a further preferred embodiment, the process may farther comprise annealing to allow the precursor to react completely.
As indicated above, the temperature profile (conditions) used in the reaction zone is preferably such so as to enable the formation of the nanoparticles such that the nuclei of the nanoparticles have essentially no or very small hollow core. This results, among others, from the fact that formation of the nanoparticles is thorough a mechanism involving growth of the nanoparticles from the central portion (nuclei of product) towards the peripheral portion.
Preferably, the temperature within the reaction zone is in the range of 500° C. to 900° C., depending on the particular material being synthesized by the process (see examples below). The gradient of the temperature within the reactor provides lowering of the temperature towards the filter.
In the process of the present invention, the amount, morphology and size of the nanoparticles are controlled by the flow of the metal precursor vapor. This flow may be controlled by adjusting the rate of the flow of an inert gas driving the vapor into the reaction chamber; and/or adjusting the temperature used for heating the metal precursor to obtain a vapor thereof.
The heating temperature of the metal precursor is preferably very close to its boiling point. More specifically, it is in the range of between 50 degree below the boiling point and up to the boiling point of said metal precursor.
The process described above allows the preparation of nanoscale inorganic fullerene-like (IF) metal chalcogenides having spherical shape optionally with a very small or no hollow core. The metal chalcogenides are preferably selected from TiS 2 , TiSe 2 , TiTe 2 , WS 2 , WSe 2 , WTe 2 , MoS 2 , MoSe 2 , MoTe 2 , SnS 2 , SnSe 2 , SnTe 2 , RuS 2 , RuSe 2 , RuTe 2 , GaS, GaSe, GaTe, In 2 S 3 , In 2 Se 3 , In 2 Te 3 , InS, InSe, Hf 2 S, HfS 2 , ZrS 2 , VS 2 , ReS 2 and NbS 2 .
According to one preferred embodiment of the invention, novel TiS 2 nanoparticles with fullerene-like structure having quite a perfectly spherical shape and consisting of up to 120 concentric molecular layers, were obtained by the reaction of TiCl 4 and H 2 S, using a vertical reactor. The obtained IF-TiS 2 exhibited excellent tribological behavior resulting probably from their close to a spherical shape which promotes rolling friction.
An apparatus of the present invention includes a reaction chamber, and a separate evaporation chamber, which is operated and whose connection to the reaction chamber is controllably operated to control the shape, size and amount of the product being produced. The control of the output parameters of the process (the shape, size and amount of the nanoparticles) is significantly improved by utilizing a vertical configuration of the reaction chamber. Thus, the present invention provides according to a further aspect thereof, an apparatus for preparing IF nanostructures, the apparatus comprising: a reaction chamber having inlets for inputting reacting gases and an outlet; a separate evaporation chamber for separately preparing a precursor vapor; and a control unit configured and operable for controlling the precursor vapor flow into the reaction chamber.
Preferably, the reaction chamber is a vertical chamber with the gas inlet accommodated so as to provide the reacting gases flow in opposite directions towards a reaction zone where they meet and react with each other. Preferably, the control unit comprises a bypass arrangement associated with the evaporation chamber. This bypass is configured and operable to provide a flow of clean inert gas instead of one enriched with vaporized precursor at certain moments of the reaction as described for instance, in Example 1 below. This improvement is of importance for the synthetic procedure preventing the flow of the highly reactive precursor during the heating up and cooling down steps of the synthesis.
According to yet another broad aspect of the invention, there is provided an apparatus for preparing IF nanostructures, the apparatus comprising: (i) a reaction chamber configured to be vertically oriented during the apparatus operation, and having gas inlets located at top and bottom sides of the chamber so as to direct a precursor vapor and the other reacting gas in opposite directions towards a reaction zone where the gases meet and react with each other; (ii) a separate evaporation chamber configured and operable for separately preparing the precursor vapor and feeding it to the respective inlet of the reaction chamber; and (c) a control unit configured and operable for controlling the precursor vapor flow into the reaction chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
In order to understand the invention and to see how it may be carried out in practice, preferred embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:
FIG. 1 exemplifies a preferred configuration of an apparatus of the present invention utilizing a vertical reaction chamber associated with a separate evaporation chamber.
FIG. 2 is a schematic illustration of an apparatus utilizing a horizontal reaction chamber.
FIG. 3 is the TEM image of IF-TiS 2 nanoparticle, produced in a horizontal reactor.
FIG. 4 is the TEM image of a typical IF-TiS 2 nanoparticle, produced in a vertical reactor. The interlayer distance is 5.8 Å and the diameter of the nanoparticle is larger than 70 nm.
Insert shows the Fast Fourier Transform (FFT) of the shown nanoparticle.
FIG. 5A is the HRTEM image of a part of an IF-TiS 2 nanoparticle produced in a vertical reactor with an overlay of the simulated TiS 2 pattern (view down [110], simulation with thickness 20 nm and defocus of −20 nm).
FIG. 5B shows the measurement of the interlayer distance by HRTEM.
FIG. 6 shows the typical IF-WS 2 obtained from WO 2 Cl 2 and H 2 S in a horizontal reactor.
FIG. 7A is the magnified TEM image of a group of IF-WS 2 nanoparticles received in a reaction of WCL 4 and H 2 S in a vertical reactor.
FIG. 7B is the TEM image of individual closed-caged IF-WS 2 nanoparticle received in a reaction of WCL 4 and H 2 S in a vertical reactor.
FIG. 8 shows the WS 2 nanoparticle obtained from WCl 5 precursor in a vertical reactor.
FIG. 9 is a TEM image of a small WS 2 nanoparticles obtained from WCl 6 in a vertical reactor
FIG. 10A is a TEM image of a group of MoS 2 nanoparticles obtained from MoCl 5 in a vertical reactor.
FIG. 10B is a TEM image of small (20 nm) IF-MoS 2 obtained from MoCl 5 in a vertical reactor.
FIG. 11A shows IF-WS 2 synthesized from WO 3 by methods known in the art.
FIG. 11B shows IF-TiS 2 synthesized from TiCl 4 . Each nanoparticle has a diameter ca. 60 nm.
Note the difference between FIGS. 11A and 11B in topology, number of layers and the absence of a hollow core in IF-TiS 2 .
DETAILED DESCRIPTION OF THE INVENTION
The principles of the process of the present invention will be explained hereinbelow with reference to the preparation of closed-cage IF nanoparticles of TiS 2 . However, it should be understood that the discussion is not limited to that specific material but it applies to IF metal chalcogenides in general.
IF nanoparticles of TiS 2 were synthesized through the reaction of TiCl 4 and H 2 S. The obtained nanoparticles have no or very small hollow core and they consist of 80-100 molecular sheets with quite a perfect spherical shape. The IF nanoparticles were prepared by two reactor assemblies: a horizontal reactor and a vertical reactor.
Reference is made to FIG. 1 exemplifying a preferred configuration of an apparatus, generally designated 10 , of the present invention suitable to be used for synthesis of IF-nanoparticles with expected superior tribological behavior. The apparatus 10 includes a vertical reaction chamber 12 for mounting into an oven 15 , a separate evaporation chamber 14 , and a control unit 16 . An outlet 17 of the evaporation chamber 14 is connectable to an inlet IN 1 of the reaction chamber 12 via a connecting gas-flow pipe (not shown here).
In the present example, the oven 15 is designed as a two-zone oven, operable to control the temperature profile in the reaction chamber. The reaction chamber 12 has independent inlets IN 1 and IN 2 at opposite ends of the chamber 12 for inputting two reaction gases (agents), respectively, e.g., TiCl 4 and H 2 S, and a gas outlet GO. Flows of these reaction agents in opposite directions towards a reaction zone in the reaction chamber are assisted by inert gas, N 2 , and a mixture of TiCl 4 and H 2 S gases is formed in the reacting zone. The control unit 16 includes, inter alia, a mass flow controller 16 A (e.g., TYLAN model FC260 commercially available from Tylan General, USA) operable for controlling the flow-rate of H 2 S, and a suitable flow controller 16 B for controlling the flow of additional gas to dilute the H 2 S by mixing it with a stream of inert gas or inert gas mixed with a reducing agent. Further provided in the apparatus 10 is a filter 18 appropriately configured and accommodated to collect the product (nanoparticles). The filter 18 is preferably spatially separated from the inner walls of the reaction chamber 12 .
The precursor (TiCl 4 ) vapors were prepared in advance in the separate evaporation chamber 14 . The latter includes a gas-washing bottle 14 A, a temperature source (not shown here) appropriately accommodated adjacent to the bottle 14 A and operable to controllably heat the TiCl 4 liquid while in the bottle 14 A. Valve arrangements 14 B and 14 C are provided to present a bypass for the nitrogen flow. This bypass provides a flow of clean nitrogen instead of one enriched with TiCl 4 at certain moments of reaction. This improves the synthetic procedure since it prevents the flow of the highly reactive TiCl 4 precursor during the heating up and cooling down steps of the synthesis. To this end, each valve is shiftable (either by an operator or automatically) between its position I (used for flushing the apparatus with pure nitrogen gas) and its position II (used for stopping the flush of the pure nitrogen gas) during the reaction. The precursor (TiCl 4 ) vapor was carried from the evaporation chamber 14 to the reaction chamber 12 by an auxiliary gas flow. The carrier gas is inert gas, which can be mixed with a reducing agent (H 2 or/and CO).
The control unit 16 is configured for controlling the gas flows and the temperature sources' operation. The preheating temperature was found to be a very significant factor, determining the amount of precursor supplied to the reaction chamber 12 . The flow-rate of nitrogen through the bottle 14 A affects the stream of the titanium tetrachloride precursor as well.
This two-chamber design apparatus with the vertical configuration of the reaction chamber considerably improves the size and shape control of the synthesized nanoparticles. The nucleation and growth mechanism established with the vertical reaction chamber ( FIG. 1 ) provide nanoparticles with quite a perfect spherical shape; small or no hollow core and many layers, which are ideally suited for alleviating friction and wear, as well as other different applications such as ultra strong nanocomposites, very selective and reactive catalysts, photovoltaic solar cells, etc.
Using similar reactions, the nucleation and growth mechanism is likely to provide many other kinds of IF nanoparticles with expected superior tribological behavior.
FIG. 2 shows another example of an apparatus, generally at 100 . The apparatus 100 includes a horizontal reaction chamber 112 associated with a single-zone oven 115 , and a separate evaporation chamber 14 configured as described above. The reaction chamber 112 has an inlet arrangement IN (for inputting reaction agents TiCl 4 and H 2 S) and an outlet arrangement OA. A control unit 16 is used for controlling the operation of the oven 115 to thereby control the temperature profile in the reaction chamber 112 . The flow-rate of H 2 S, as well as that of N 2 , is appropriately controlled as described above. The TiCl 4 vapors were obtained by preheating the liquid TiCl 4 in a gas-washing bottle (evaporation chamber). The TiCl 4 vapor is carried from the evaporation chamber 14 to the reaction chamber 112 by an auxiliary N 2 gas flow. The resulting product (TiS 2 powder) is collected for analysis on the surface of the reaction chamber.
EXAMPLES
Example 1
Preparation of IF-TiS 2 Nanoparticles in the Vertical Reactor Based Apparatus of FIG. 1
In order to maintain a water and oxygen free atmosphere, the reaction chamber 12 was permanently maintained at 500° C. and a flow of N 2 gas (20 ml/min) until shortly before the run starts, when it is withdrawn from the oven 15 . At this point, the reaction chamber 12 was opened and cleaned. At the beginning of the process, the reaction chamber 12 was closed hermetically from outside the oven, and the reaction gases, except for precursor (titanium tetrachloride), were supplied to the inlets flushing the system for 10-15 min. The slight overpressure (ca. 1.1 bars) was maintained at a constant value by the gas trap in the exit GO of the gases from the reaction chamber 12 . This procedure eliminates most of the residual atmospheric gases, like water vapor and oxygen from the reaction chamber. This step is very important for the synthesis, since both the final product (TiS 2 ) and especially the precursor (TiCl 4 ) are very sensitive to moisture. Subsequently, the reactor was inserted into the oven 15 .
Independent inlets IN 1 and IN 2 for both reaction gases i.e. TiCl 4 and H 2 S were used, with the mixture of the reagents being formed in the reaction chamber itself. The flow-rate of H 2 S (3-20 cc/min) was controlled by means of a TYLAN model FC260 mass flow-controller 16 A. The H 2 S was diluted by mixing this gas with a stream of N 2 gas (10-200 cc/min in this reaction) using another flow-controller 16 B. The TiCl 4 vapors were obtained by preheating the liquid TiCl 4 in the gas-washing bottle 14 A of the evaporation chamber 14 . The TiCl 4 vapor was carried to the reaction chamber 12 by an auxiliary N 2 gas flow. The temperature of the TiCl 4 source was kept usually between 100 and 130° C., which is close to its boiling point of 136.5° C. As indicated above, the preheating temperature is a significant factor, determining the amount of precursor supplied to the reaction zone. The flow-rate of nitrogen through the bottle 14 A (10-100 cc/min) affects the stream of the titanium tetrachloride precursor as well. A small overpressure (1.1 bar) was maintained by using a gas trap filled with NaOH (5%) solution in the gas outlet of the reactor.
The temperature in the reaction chamber zone, where the two gases (TiCl 4 and H 2 S) mix and react, and near the filter 18 was usually varied between 650-750° C. This temperature was chosen based on the properties of the Ti-S system.
Several experiments have been run at higher temperatures (up to 800° C.) in the reaction chamber.
The reaction started with the flow of TiCl 4 vapor for 30-60 min and was interrupted by terminating the preheating of the TiCl 4 precursor and using the bypass system, which provides continuous N 2 flow for flushing the system. A short annealing period (10-15 min) followed, allowing the last portions of the supplied titanium tetrachloride precursor to react completely. Afterwards, the reactor was moved down for cooling. The main portion of the synthesized material was collected on the filter. In addition, small portions of the product powder were found sticking to the surfaces of the quartz reactor.
Example 2
Preparation of Fullerene-Like Nanostructures of TiS 2 in a Horizontal Reactor Based Apparatus of FIG. 2 .
The reaction chamber 112 was cleaned in a similar manner as described in Example 1 above in order to maintain a water and oxygen free atmosphere. Subsequently, the reaction chamber was inserted into the oven 115 .
The temperature in the horizontal reaction chamber 112 was controlled by means of a single-zone oven 115 . The TiCl 4 vapor was prepared in the separate evaporation chamber ( 14 in FIG. 1 ) and supplied to the reaction chamber 112 in the similar way as was done in the above-described Example 1. The temperature of the reaction chamber 112 , where the two gases (TiCl 4 and H 2 S) mix and react, was varied in the range of 650-750° C. The resulting TiS 2 powder was collected for analysis on the surface of the reactor boat. However, the product collection was impeded as the product was swept by the carrier gas to the trap.
Example 3
Preparation of Fullerene-Like Nanostructures of WS 2 in a Horizontal Reactor Based Apparatus of FIG. 2 .
The reaction chamber 112 was cleaned in a similar manner as described in Example 1 above in order to maintain a water and oxygen free atmosphere.
Subsequently, the reaction chamber was inserted into the oven 115 .
The temperature in the horizontal reaction chamber 112 was controlled by means of a single-zone oven 115 . The chosen precursor WO 2 Cl 2 was heated up to 270-290° C. in the separate evaporation chamber ( 14 in FIG. 1 ) and its vapor was supplied to the reaction chamber 112 in the similar way as was done in the above-described Example 1. The temperature of the reaction chamber 112 , where the two gases (metal-containing precursor and H 2 S) mix and react, was varied in the range of 700-850° C. A small overpressure (1.1 bar) was maintained by using a gas trap filled with NaOH (5%) solution in the gas outlet of the reaction chamber.
The resulting WS 2 powder was collected for analysis on the surface of the reactor boat. However, the product collection was impeded as the product was swept by the carrier gas to the trap. The resulting nanoparticles are shown in FIG. 6 . As can be noted, the IF-WS 2 obtained in the present example are not so perfect and have hollow core. This can be explained by the inhomegenity of the reaction parameters in the chosen horizontal reactor.
In other experiments the forming gas, containing 1-10% of H 2 in N 2 , was used instead of clean nitrogen for either caring the metal-containing precursor or diluting the H 2 S.
Furthermore, similar series of experiments were carried out using horizontal reactors starting with WBr 5 (boils at 333° C., preheated at 290-330° C.). Different combinations of carrier gas (clear nitrogen or hydrogen-enriched nitrogen) were used. The resulting material consisted from IF-nanoparticles together with byproducts (platelets amorphous materials), as revealed by TEM analysis. Different nanoparticles both hollow-core and non-hollow core were observed.
Example 4
Preparation of IF-WS 2 Nanoparticles in the Vertical Reactor Based Apparatus of FIG. 1
At the beginning of the process, the reaction chamber 12 was closed hermetically from outside the oven, and the reaction gases, except for precursor (WBr 5 ), were supplied to the inlets flushing the system for 10-15 min. The slight overpressure (ca. 1.1 bars) was maintained at a constant value by the gas trap in the exit GO of the gases from the reaction chamber 12 . Subsequently, the reactor was inserted into the oven 15 .
Independent inlets IN 1 and IN 2 for both reaction gases i.e. WBr 5 and H 2 S were used, with the mixture of the reagents being formed in the reaction chamber itself. The H 2 S (3-20 cc/min) was mixed with a stream of N 2 gas (10-200 cc/min in this reaction). The WBr 5 vapors were obtained by preheating the WBr 5 precursor in the gas-washing bottle 14 A of the evaporation chamber 14 and were carried to the reaction chamber 12 by an auxiliary N 2 gas flow. The temperature of the WBr 5 source was kept usually between 290 and 330° C., which is close to its boiling point of 333° C. A small overpressure (1.1 bar) was maintained by using a gas trap filled with NaOH (5%) solution in the gas outlet of the reaction chamber.
The temperature in the reaction chamber zone, where the two gases (WBr 5 and H 2 S) mix and react, and near the filter 18 was usually varied between 700-850° C.
The main portion of the synthesized material was collected on the filter. In addition, small portions of the product powder were found sticking to the surfaces of the quartz reaction chamber.
Example 5
Preparation of IF-MoS 2 Nanoparticles in the Vertical Reactor Based Apparatus of FIG. 1
At the beginning of the process, the reaction chamber 12 was closed hermetically from outside the oven, and the reaction gases, except for precursor (Mo(CO) 5 ), were supplied to the inlets flushing the system for 10-15 min. Subsequently, the reaction chamber was inserted into the oven 15 .
Independent inlets IN 1 and IN 2 for both reaction gases i.e. Mo(CO) 5 and H 2 S were used, with the mixture of the reagents being formed in the reaction chamber itself. The H 2 S (3-20 cc/min) was mixed with a stream of N 2 gas (10-200 cc/min in this reaction). The Mo(CO) 5 vapors were obtained by preheating the liquid Mo(CO) 5 in the gas-washing bottle 14 A of the evaporation chamber 14 and was carried to the reaction chamber 12 by an auxiliary N 2 gas flow. The temperature of the Mo(CO) 5 source was kept usually between 160 and 200° C., which is over its melting point of 150° C.
The temperature in the reaction chamber zone, where the two gases (Mo(CO) 5 and H 2 S) mix and react, and near the filter 18 was usually varied between 650-850° C.
The main portion of the synthesized material was collected on the filter. In addition, small portions of the product powder were found sticking to the surfaces of the quartz reactor.
Example 6
Preparation of IF-WS 2 Nanoparticles in the Vertical Reactor Based Apparatus of FIG. 1
At the beginning of the process, the reaction chamber 12 was closed hermetically from outside the oven, and the reaction gases, except for precursor (WCl 4 ), were supplied to the inlets flushing the system for 10-15 min. The slight overpressure (ca. 1.1 bars) was maintained at a constant value by the gas trap in the exit GO of the gases from the reaction chamber 12 . Subsequently, the reactor was inserted into the oven 15 .
Independent inlets IN 1 and IN 2 for both reaction gases i.e. WCl 4 and H 2 S were used, with the mixture of the reagents being formed in the reaction chamber itself. The H 2 S (3-20 cc/min) was mixed with a stream of N 2 gas (10-200 cc/min in this reaction). The WCl 4 vapors were obtained by preheating the precursor in the gas-washing bottle 14 A of the evaporation chamber 14 and were carried to the reaction chamber 12 by an auxiliary N 2 gas flow. The temperature of the WCl 4 source was kept usually between 200 and 400° C. in order to provide the necessary amount of precursor supplied to the reaction. A small overpressure (1.1 bar) was maintained by using a gas trap filled with NaOH (5%) solution in the gas outlet of the reaction chamber.
The temperature in the reaction chamber zone, where the two gases (WCl 4 and H 2 S) mix and react, and near the filter 18 was usually varied between 700-850° C.
The main portion of the synthesized material was collected on the filter. In addition, small portions of the product powder were found sticking to the surfaces of the quartz reaction chamber.
Example 7
Preparation of IF-WS 2 Nanoparticles in the Vertical Reactor Based Apparatus of FIG. 1
At the beginning of the process, the reaction chamber 12 was closed hermetically from outside the oven, and the reaction gases, except for precursor (WCl 5 ), were supplied to the inlets flushing the system for 10-15 min. The slight overpressure (ca. 1.1 bars) was maintained at a constant value by the gas trap in the exit GO of the gases from the reaction chamber 12 . Subsequently, the reactor was inserted into the oven 15 .
Independent inlets IN 1 and IN 2 for both reaction gases i.e. WCl 5 and H 2 S were used, with the mixture of the reagents being formed in the reaction chamber itself. The H 2 S (3-20 cc/min) was mixed with a stream of N 2 gas (10-200 cc/min in this reaction). The WCl 5 vapors were obtained by preheating the WCl 5 precursor in the gas-washing bottle 14 A of the evaporation chamber 14 and were carried to the reaction chamber 12 by an auxiliary N 2 gas flow. The temperature of the WCl 5 source was kept usually between 250 and 285° C. A small overpressure (1.1 bar) was maintained by using a gas trap filled with NaOH (5%) solution in the gas outlet of the reaction chamber.
The temperature in the reaction chamber zone, where the two gases (WCl 5 and H 2 S) mix and react, and near the filter 18 was usually varied between 700-850° C.
Since the formal valence of tungsten in the precursor (WCl 5 ) differs from the one in the expected product (WS 2 ), additional reduction of metal was required. The excess of H 2 S in the reaction atmosphere acts as the reduction agent, however in part of the experiments additional flow of H 2 was used for this purpose. The additional flow of hydrogen (1-10% of hydrogen within nitrogen instead of pure N 2 ) was supplied either together with precursor or mixed with H 2 S.
The main portion of the synthesized material was collected on the filter. In addition, small portions of the product powder were found sticking to the surfaces of the quartz reaction chamber.
Example 8
Preparation of IF-WS 2 Nanoparticles in the Vertical Reactor Based Apparatus of FIG. 1
At the beginning of the process, the reaction chamber 12 was closed hermetically from outside the oven, and the reaction gases, except for precursor (WCl 6 ), were supplied to the inlets flushing the system for 10-15 min. The slight overpressure (ca. 1.1 bars) was maintained at a constant value by the gas trap in the exit GO of the gases from the reaction chamber 12 . Subsequently, the reactor was inserted into the oven 15 .
Independent inlets IN 1 and IN 2 for both reaction gases i.e. WCl 6 and H 2 S were used, with the mixture of the reagents being formed in the reaction chamber itself. The H 2 S (3-20 cc/min) was mixed with a stream of N 2 gas (10-200 cc/in in this reaction). The WCl 6 vapors were obtained by preheating the WCl 6 precursor in the gas-washing bottle 14 A of the evaporation chamber 14 and were carried to the reaction chamber 12 by an auxiliary N 2 gas flow. The temperature of the WCl 6 source was kept usually between 275 and 345° C. A small overpressure (1.1 bar) was maintained by using a gas trap filled with NaOH (5%) solution in the gas outlet of the reaction chamber.
The temperature in the reaction chamber zone, where the two gases (WCl 6 and H 2 S) mix and react, and near the filter 18 was usually varied between 700-850° C.
Since the formal valence of tungsten in the precursor (WCl 6 ) differs from the one in the expected product (WS 2 ), additional reduction of metal was required. The excess of H 2 S in the reaction atmosphere acts as the reduction agent, however in part of the experiments additional flow of H 2 was used for this purpose. The additional flow of hydrogen (1-10% of hydrogen within nitrogen instead of pure N 2 ) was supplied either together with precursor or mixed with a H 2 S.
The main portion of the synthesized material was collected on the filter. In addition, small portions of the product powder were found sticking to the surfaces of the quartz reaction chamber.
Example 9
Preparation of IF-MoS 2 Nanoparticles in the Vertical Reactor Based Apparatus of FIG. 1
At the beginning of the process, the reaction chamber 12 was closed hermetically from outside the oven, and the reaction gases, except for precursor (MoCl 5 ), were supplied to the inlets flushing the system for 10-15 min. The slight overpressure (ca. 1.1 bars) was maintained at a constant value by the gas trap in the exit GO of the gases from the reaction chamber 12 . Subsequently, the reactor was inserted into the oven 15 .
Independent inlets IN 1 and IN 2 for both reaction gases i.e. MoCl 5 and H 2 S were used, with the mixture of the reagents being formed in the reaction chamber itself. The H 2 S (3-20 cc/min) was mixed with a stream of N 2 gas (10-200 cc/min in this reaction). The MoCl 5 vapors were obtained by preheating the precursor in the gas-washing bottle 14 A of the evaporation chamber 14 and were carried to the reaction chamber 12 by an auxiliary N 2 gas flow. The temperature of the MoCl 5 source was kept usually between 200 and 265° C. A small overpressure (1.1 bar) was maintained by using a gas trap filled with NaOH (5%) solution in the gas outlet of the reaction chamber.
The temperature in the reaction chamber zone, where the two gases (MoCl 5 and H 2 S) mix and react, and near the filter 18 was usually varied between 700-850° C.
Since the formal valence of tungsten in the precursor (MoCl 5 ) differs from the one in the expected product (WS 2 ), additional reduction of metal was required. The excess of H 2 S in the reaction atmosphere acts as the reduction agent, however in part of the experiments additional flow of H 2 was used for this purpose. The additional flow of hydrogen (1-10% of hydrogen within nitrogen instead of pure N 2 ) was supplied either together with precursor or mixed with a H 2 S.
The main portion of the synthesized material was collected on the filter. In addition, small portions of the product powder were found sticking to the surfaces of the quartz reaction chamber.
Analysis of the Synthesized Materials
The products were analyzed mainly by means of various electron microscopy techniques. The following microscopes were used: environmental scanning electron microscope (Philips FEI-XL30 E-SEM); transmission electron microscope (Philips CM120 TEM), equipped with EDS detector (EDAX-Phoenix Microanalyzer); high resolution transmission electron microscope (HRTEM) with field emission gun (FEI Technai F30), equipped with a parallel electron energy loss spectrometer (Gatan imaging filter-GIF (Gatan)). Simulation of the HRTEM micrographs of TiS 2 was obtained using the MacTempas image-simulation software. Complementary analyses were carried out by powder X-ray diffraction (XRD).
TEM examination of the powder obtained in the horizontal set-up (Example 2) revealed the presence of closed cage nanostuctures in the product ( FIG. 3 ). The typically observed particle-size was about 100 nm, with nanoparticles ranging in size between 50 and 150 nm. The wide size distribution is a reflection of the inhomogenity of the reaction conditions in this set-up. The yield of the closed-cage nanoparticles in those experiments was up to 30%, depending on the reaction conditions. The remaining material, as revealed by SEM and TEM, was made of TiS 2 platelets, a few tens of nanometers to 0.5 micron in size, each.
The product of the vertical set-up (Example 1) was found to contain an appreciably larger fraction of the IF-TiS 2 phase with yields approaching 80%. Furthermore, the size distribution of the synthesized nanoparticles was found to be appreciably narrower in the vertical set-up, as compared to the horizontal reactor. The product of the vertical reactor ended up also to be more spherical ( FIG. 4 ). Tilting the sample in different viewing angles did not reveal any significant changes in the shape of the observed nanoparticles. These findings emphasize the advantage of using the vertical set-up for the synthesis of the IF-nanophase materials. Varying the synthesis time did not seem to have an appreciable influence on the size distribution of the IF-TiS 2 nanoparticles.
The resulting IF-nanoparticles were found to consist of a large number of concentric layers displaying relatively smooth curvature. For instance, the nanoparticle shown in FIG. 4 consists of approximately 80 concentric and spherical layers. These layers were continuous with no visible holes or edge dislocations observed. The hollow core, which was observed in the IF-WS 2 (MOS 2 ) nanoparticles, did not exist in the present nanoparticles. A careful examination of the synthesized nanoparticles did not reveal a spiral growth mode of the molecular layers of the material. Instead, a quasi-epitaxial, layer by layer growth mode could be deciphered. The observed layers are complete and are separated one from the others.
In several cases the cores of the observed TiS 2 nanoparticles were found to be made of a number of tiny spherical IF centers, which are stacked together. As a rule, such nanoparticles were preferably found in the experiments with definitely higher flow rate of TiCl 4 precursor (preheating at 130-140° C.). For instance several such centers are visible in the TEM image of the nanoparticle shown in FIG. 3 . The borders between those nuclei can be clearly distinguished in the core of the nanoparticle, while the peripheral layers envelope the divided core into a single spherical moiety.
HRTEM image of a part of a closed TiS 2 fullerene-like nanoparticle is shown in FIG. 5A together with its simulated image. A satisfactory agreement between the real and simulated images is indicative of the correct assignment of the nanoparticle's structure. It should be nonetheless noted, that the simulation refers to the bulk (lT) material, which is flat, awhile the IF-TiS 2 nanoparticles are curved and their structure is not fully commensurate, because the number of atoms is different in each of the concentric nested layers.
The interlayer distance obtained from either Fourier analysis (insert of FIG. 4 ), or a direct measurement ( FIG. 5B ) was found to be 0.58 nm. This value represents an expansion of about 1.8% in comparison to the layer to layer separation in bulk lT-TiS 2 (0.57 nm). The interlayer distance did not seem to vary along the entire volume of the nanoparticle. This result is in a good agreement with XRD experiments, in which the synthesized material was identified as lT-TiS 2 . It nevertheless stands in a sharp contrast with the synthesized IF-WS 2 and MoS 2 nanoparticles, synthesized by reacting H 2 S with the respective oxides, were often large gaps are observed between the molecular sheets. These gaps can be associated with strain-induced brisk changes in the topology of the layers from evenly folded to faceted structure. This topology was found to be typical for nanoparticles which are produced by the reaction of H 2 S with the respective oxide, which starts on the surface of the nanoparticle and progresses inwards consuming the oxide core.
At high temperature experiments (800° C.), nanoparticles having distorted shape were observed. Also, the overall yield of the IF-TiS 2 at high temperatures was low (app. 10%), the main portion being TiS 2 platelets.
A number of other precursors were tested for their aptitude to obtain fullerene-like materials in similar way. The resulting nanoparticles of both MoS 2 and WS 2 ( FIGS. 6-10 ) were obtained from variety of starting materials. Most of the newly-obtained nanoparticles were found to differ from their analogs, obtained by reduction-sulfidization of oxide templates. More specifically, the nanoparticles obtained from the vapors of metal-containing precursors were more spherical, with little amount of defects. Moreover, they had a small hollow core, if any, like it was found in the case of TiS 2 .
Tribological Experiments
A ball on flat tester 1 was used for the present tribological experiments. A load of 50 grams was used in these experiments. The friction coefficient was measured in the end of the 20 cycles run, were steady tribological regime prevailed.
To test the efficacy of the IF-TiS 2 particles produced by the process of the present invention, as a solid lubricant a series of tribological experiments were conducted. It was found that the addition of a small amount (1%) of the IF-TiS 2 powder decreases significantly (10 times) the friction coefficient of the pure oil-from 0.29 to 0.03. A similar test with 1% bulk powder (lT-TiS 2 ) added to the oil, leads to a friction coefficient of 0.07, i.e. twice that of the IF-phase. It must be emphasized here that the portion used for the tribological tests contained no more than 50% IF-TiS 2 , the rest being platelets of lT-TiS 2 . The collected data suggests that the shape of the IF-TiS 2 of the invention might play a major role in lowering the friction coefficient. The quite perfectly spherical nanoparticles with sizes ranging in the 30-70 nm and up to 100 molecular layers thick obtained with the vertical set-up could provide effective rolling friction and sliding. It is emphasized the important role played by the spherical shape of the nanoparticles in providing rolling friction with a reduced friction coefficient and wear. These nanoparticles are also stable and compliant.
Comparison Between IF Nanoparticles Obtained in the Process of the Present Invention and Known IF Nanoparticles:
The IF-TiS 2 nanoparticles obtained by the process of the present invention in a vertical reactor, typically consist of about hundred layers and are formed fast, over a period of a few minutes or less, only. They are spherical in shape, and their lattice parameter (c) is constant along the radial axis of the nanoparticle, which suggests that they suffer from relatively minor strain. Table 2 together with FIG. 11 make a concise comparison between the morphology and some of the properties of the IF-TiS 2 nanoparticles obtained by the process of the present invention and IF-WS 2 nanoparticles obtained by processes known in the art.
The following Table 2 compares the representative characteristics of fullerene-like WS 2 obtained by the known reaction of H 2 S gas with tungsten oxide nanoparticles, and TiS 2 nanoparticles obtained from titanium chloride vapor according to the present invention.
TABLE 2
Comparison between representative characteristics of IF-WS 2
obtained by the known reaction and IF-TiS 2 nanoparticles obtained
by the process of the present invention.
IF-TiS 2
IF-WS 2
Typical size
60-100 nm
60-200 nm
Number of layers
50-120
20-30
Core
No core or very
Empty hollow core
small core observed
Overall shape of the
Substantially
Partially faceted,
nanoparticle
spherical
not spherical
Estimated growth
Minutes
Hours
duration
Growth mechanism
Nucleation and
Synergetic
growth
sulfidization and
reduction; diffusion
controlled
In contrast to the earlier synthesized IF-WS 2 (MoS 2 ) 5-7 , the closed-cage nanoparticles of titanium disulfide produced by the process of the present invention have a very small hollow core or do not possess such core. The interlayer distance (0.58 nm) is preserved along the entire volume of the nanoparticle. The present results are indicative of the fact that the titanium disulfide layers start to grow from a small nuclei, obeying thereby the ubiquitous nucleation and growth mechanism. The present synthesis of IF-TiS 2 may be envisaged as a homogeneous nucleation of the fullerene-like structures from embryonic clusters formed in the vapor phase, in contrast to the heterogeneous nucleation of IF-WS 2 (MoS 2 ) on the surfaces of the respective oxide templates.
The vapor of TiCl 4 crosses the flux of H 2 S, coming out from an oppositely placed tube at relatively high temperature (650-750° C.), which provides a high reaction rate. Since the TiS 2 clusters formed in the gas phase are non-volatile, they condense into small nuclei. It is well established that shrinking the size of the graphene (or other layered material—like TiS 2 ) sheet makes the planar structure unstable resulting in folding and formation of a closed-cage structure. Once such closed-cage nuclei of TiS 2 are formed in the vapor phase of the reactor further TiCl 4 adsorb on its surface and react with the H 2 S gas. This reaction occurs in a highly controlled-quasi-epitaxial fashion, i.e. with a single growth front leading to a layer by layer growth mode. This growth mode entails minimal geometrical constraints, and hence the nanoparticles are appreciably more spherical than the previously reported IF nanoparticles. The spherical morphologies with relatively smooth curvature exhibited by these nanoparticles suggest that the bending of the molecular sheets results in continuously distributed dislocations or defects, in contrast to the more facetted structures, observed in the previously synthesized IF-WS 2 , where the defects are localized in grain boundaries. The rather large number of layers observed in the IF-TiS 2 nanoparticles undergoing van der Waals interactions may compensate for the bending and dislocation energies and add to the stability of such spherical nanoparticles.
The small crystallites, formed during the initial stages of the gas-phase reaction collide in the vapor phase. When the kinetic energy of the collision is not sufficiently large to separate the colliding nanoparticles, they aggregate forming multi-nuclei cores. These aggregated nanoparticles serve as a template, which are subsequently enfolded by additional TiS 2 layers on their surface. A fullerene-like nanoparticle with multi-core is thus obtained (see FIG. 3 ). The fairly narrow size distribution of the IF-TiS 2 nanoparticles in the vertical set-up is particularly notable. Presently, two possible explanations for this effect can be invoked. Once the nanoparticles reach a critical size, which coincides with their thermodynamic stability, their growth rate slows down appreciably, while the smaller nuclei continue to grow fast until they reach a similar size. A further possible reason for the narrow size distribution is that the larger nanoparticles can not float in the vapor and they fall on the filter, where they are rapidly buried under the next layer of nanoparticles, and their growth slows down.
The constancy of the distance between the layers (c) in the radial direction, and their quite perfectly spherical shape indicate that the present IF nanoparticles suffer little strain, only. This phenomenon is the result of the nucleation and growth mechanism accomplished in the present invention, and it has a favorable impact on the tribological behavior of such nanoparticles.
Other IF metal chalcogenides, e.g. IF-WS 2 and MoS 2 nanoparticles, synthesized by a similar process as the above-exemplified one for TiS 2 , provide similar spherical nanoparticles consisting of many layers ( FIG. 6-10 ). It appears that the nanoparticles obtained from the vapors of metal-containing precursor follow the same growth mechanism (nucleation and growth). This topology favors rolling and sliding of the nanoparticles, providing improved tribological behavior for the IF solid lubricant. Since IF-WS 2 and MoS 2 are the materials of choice for such applications, the improved control of the nanoparticles morphology, as presented in the present invention for IF-TiS 2 , leads to a superior tribological behavior of these solid lubricants, too. | 4y
|
RELATED APPLICATIONS
This application is a continuation of U.S. application Ser. No. 10/431,863, filed on May 7, 2003, now U.S. Pat. No. 6,877,187 which is a continuation of U.S. application Ser. No. 09/810,868, filed on Mar. 16, 2001, now U.S. Pat. No. 6,598,264, and incorporates by reference those applications in their entireties and claims priority thereto.
TECHNICAL FIELD
This invention relates to block and tackle window balance devices for single and double hung windows and, more particularly, to a block and tackle window balance device that provides an increased range of travel within a window frame.
BACKGROUND INFORMATION
Hung window assemblies generally include a window frame, a lower window sash, an upper window sash, a pair of window jambs, two sets of jamb pockets, and at least one window balance device for offsetting the weight of a window sash throughout a range of travel within the window frame. Block and tackle window balance devices use a combination of a spring and pulleys located within a channel to balance the weight of the window sash at any position within the jamb pockets.
In some block and tackle window balance devices, the channel containing both the spring and pulleys is attached to the window sash, and a cord, which connects the pulleys together, is attached to a jamb mounting hook that is connected to a side jamb. A disadvantage of this type of device is that the travel distance of the window sash is limited by some of the pulleys located within the rigid channel interfering with the jamb mounting hook that attaches the window balance to the window jamb.
SUMMARY OF THE INVENTION
In general, in one aspect, the invention relates to a block and tackle window balance device for use with single and double hung windows that affords increased window opening travel distance. In one embodiment, the block and tackle window balance device includes a channel, a spring with a first end and a second end, a translatable pulley block unit, a fixed pulley block unit, a cord, a top guide, and a bottom guide with a bottom guide roller. The top and bottom guides are connected to opposite ends of the channel. The spring, the translatable pulley block unit, and the fixed pulley block unit are all located within the channel. The first end of the spring and the fixed pulley block unit are fixed at opposite ends of the channel. The second end of the spring is connected to the translatable pulley block unit. The translatable and fixed pulley block units are connected by the cord. The cord is threaded around both the translatable and fixed pulley block units and extends around the bottom guide roller located within the bottom guide.
In another embodiment, the block and tackle window balance device includes a top guide including a top angled portion and a bottom portion. The bottom portion of the top guide is connected to one end of the channel. In still another embodiment, the top angled portion of the top guide is sized to receive a member from a window sash.
In yet another embodiment, the block and tackle window device includes a bottom guide that extends beyond the rigid channel. In still yet another embodiment, the bottom guide of the device further includes a channel to receive a portion of a window sash.
In general, in one aspect, the invention relates to a method of providing increased travel of a window sash slidably mounted in a window frame. The method includes three steps. A first step is to provide a window assembly that includes a window frame with jambs with jamb pockets, an upper window sash, a lower window sash, and at least one block and tackle window balance device having a channel and a bottom roller for dispensing a cord. The channel has a first end and a second end. The bottom roller is mounted proximate to the second end of the channel with a first distance between the first end of the channel and the bottom roller. A second step is to remove the block and tackle window balance device from the window assembly. A final step is to provide and to install an increased travel window balance device. The increased window balance device has a channel with a first end and a second end and a bottom guide roller for dispensing a cord. The bottom guide roller is mounted proximate to the second end of the channel and a second distance is defined as the length between the first end of the channel and the bottom guide roller. The second distance of the increased window balance device is greater than the first distance of the removed block and tackle window balance device.
The foregoing and other objects, aspects, features, and advantages of the invention will more apparent from the following description and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, like reference characters generally refer to the same parts throughout the different views. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.
FIG. 1 is a perspective view of a double hung window.
FIG. 2A is a perspective view of a prior art block and tackle window balance.
FIG. 2B is another perspective view of the prior art block and tackle window balance of FIG. 2A with one of two side walls of the U-shaped channel removed.
FIG. 3 is a perspective rear view of the prior art block and tackle window balance.
FIG. 4A is a perspective view of an embodiment of a block and tackle window balance of the invention.
FIG. 4B is perspective view of the block and tackle window balance of FIG. 4A with one of two side walls of the U-shaped channel removed.
FIG. 5 is a perspective view of an embodiment of a block and tackle window balance of the invention mounted within a window jamb.
FIG. 6 is an enlarged front view of a top guide of the block and tackle window balance of FIG. 4A attached to a cam.
FIG. 7A is a front view showing a closed position of a window assembly with prior art block and tackle window balances.
FIG. 7B is a front view showing an open position of the window assembly with prior art block and tackle window balances.
FIG. 8A is a front view showing a closed position of a window assembly with an embodiment of a block and tackle window balances of the invention.
FIG. 8B is a front view showing an open position of a window assembly with block and tackle window balances of the invention.
DETAILED DESCRIPTION
Referring to FIG. 1 , shown is a double hung window assembly 100 in which a block and tackle window balance constructed in accordance with the teachings of the present invention can be used. The double hung window assembly 100 includes a window frame 102 , a lower window sash 104 , an upper window sash 106 , and a pair of window jambs 107 . Within each window jamb 107 , jamb pockets 108 are defined. The lower window sash 104 and upper window sash 106 slide vertically within the jamb pockets 108 . Generally, window balances are attached to the lower and upper window sashes 104 , 106 to balance the weight of the window sashes at any vertical position within the jamb pockets 108 .
FIGS. 2A , 2 B, and 3 show perspective views of a prior art block and tackle window balance 200 . FIG. 2A shows the prior art block and tackle window balance 200 in full, whereas FIG. 2B shows the prior art block and tackle window balance 200 with one side wall of a rigid U-shaped channel 205 cut away so that components within the window balance 200 are more visible. FIG. 3 shows a rear view of the window balance 200 .
The block and tackle window balance 200 includes a spring 220 , a translatable pulley unit 230 , a fixed pulley unit 235 , a roller 239 , and a cord 240 all housed with the rigid U-shaped channel 205 . Attached to the two ends of the rigid U-shaped channel 205 with fasteners 212 , 216 are a top guide 210 and a bottom guide 215 that are used to connect the window balance 200 to either the upper or lower window sashes 104 , 106 and to help guide the vertical motion of the window balance 200 within the jamb pockets 108 . The top guide 210 includes an upper portion 202 and a lower portion 203 . The upper portion 202 of the top guide 210 is angled and is sized to be received by a member attached to a window sash, such as a cam. The bottom guide 215 includes a back portion 213 , best seen in FIG. 3 , that encases a portion of the rigid channel 205 . Within the back portion 213 of the bottom guide 215 is a channel 214 sized to receive a portion of a window sash.
The rigid U-shaped channel 205 has a back wall 206 and two side walls 207 , 208 that in combination form the U-shape. The rigid U-shaped channel 205 serves as an external frame to which the components of the window balance 200 can be secured. The rigid U-shaped channel 205 also keeps components located within the rigid U-shaped channel 205 free of debris and particulate matter. The spring 220 , the translatable pulley unit 230 , the fixed pulley unit 235 , and the roller 239 are located inside the rigid U-shaped channel 205 . Both of the translatable pulley unit 230 and the fixed pulley unit 235 include one or more pulleys rotatable around respective axles.
Components within the rigid U-shaped channel 205 work in combination to create a force to counterbalance the weight of the attached sash at any vertical position within the window frame 102 . These components are attached to each other such that a first end 219 of the spring 220 is connected to the translatable pulley unit 230 , and the translatable pulley unit 230 is connected to the fixed pulley unit 235 and the roller 239 via the cord 240 . A pulley in the fixed pulley unit 235 and the roller 239 may be contained in a frame 236 . To secure the components within the rigid U-shaped channel 205 , the second end 221 of the spring 220 and the frame 236 are fixed to opposite ends of the rigid U-shaped channel 205 via respective fasteners 218 , 243 . The frame 236 is also used to secure a pulley axle 237 and a roller axle 238 , around which the pulley in the fixed pulley unit 235 and the roller 239 respectively rotate. A first distance “AA” 275 is defined by a length extending between the upper portion 202 of the top guide 210 and the roller axle 238 . The spring 220 and the translatable pulley unit 230 are connected together by hooking the first end 219 of the spring 220 through an upper slot opening 229 in a frame 225 . The frame 225 houses the translatable pulley unit 230 and a pulley axle 232 around which a pulley in the translatable pulley unit 230 rotates. The cord 240 , which can be a rope, string, or cable, has a first end 241 and a second end 242 . The first end 241 of the cord 240 is secured to the frame 225 and the second end 242 , which is a free cord end, is threaded through the translatable pulley unit 230 , the fixed pulley unit 235 , and the roller 239 , thereby connecting all three components together. After the cord 240 connects the three components together, a jamb mounting attachment 245 is secured to the second end 242 of the cord 240 . When the prior art window balance 200 is located in the jamb pocket 108 , the jamb mounting attachment 245 engages an opening 430 ( FIG. 5 ) within one of the jamb pockets 108 , securing the window balance 200 to the window jamb 107 .
The spring 220 provides the force required to balance the sashes. The spring 220 is extended when the second end 242 of the cord 240 with the jamb mounting attachment 245 is pulled, causing the frame 225 to move within the rigid U-shaped channel 205 towards the frame 236 , which is fixed. As the frame 225 moves towards the frame 236 , the spring 220 is extended.
FIGS. 4A and 4B show an embodiment of a block and tackle window balance 300 in accordance with the teachings of the present invention. The window balances 300 act to counterbalance the weight of the window sashes 104 , 106 at any vertical position within the window frame 102 . FIG. 4A show one perspective view of the window balance 300 and FIG. 4B shows another perspective view of the same balance, but with a side wall of the rigid U-shaped channel 305 removed. The window balance 300 includes the rigid U-shaped channel 305 , a top guide 310 , a bottom guide 315 , a spring 320 , a translatable pulley unit 330 , a fixed pulley unit 335 , a bottom guide roller 350 , and a cord 340 . The top guide 310 and the bottom guide 315 are fixed to the rigid U-shaped channel 305 by fasteners 312 , 316 . The top guide 310 is used to help connect the block and tackle window balance 300 to the window sash 104 , 106 and to help guide the movement of the block and tackle window balance 300 within the jamb pocket 108 . The top guide 310 may include a top angled portion 302 and a bottom portion 303 as shown in FIGS. 4A and 4B . The bottom guide 315 is also used for connection and guidance purposes, but the bottom guide 315 further serves as a frame for housing the bottom guide roller 350 . The bottom guide 315 extends beyond the rigid U-shaped channel 305 and, therefore, the bottom guide roller 350 is located outside of the rigid U-shaped channel 305 . A back portion 313 of the bottom guide 315 may include a channel 314 for receiving a portion of the window sash, as depicted in FIG. 5 . Some windows have a groove running along a bottom rail of the sash. On conventional balances, the bottom guide can drop into this groove so a manufacturer needs to use a shorter balance to avoid dropping into the groove. This effectively reduces the amount of travel, because shorter balances have to be used. The bottom guide 315 of the present invention is configured so the contact point of the bottom guide 315 to the sash is higher on the balance 300 so the groove is avoided and a longer balance with a greater spring force can be used. This can afford increased force for balancing the sash at any vertical position, as well as increased amount of travel resulting from the longer balance.
The spring 320 , the translatable pulley unit 330 , and the fixed pulley unit 335 are located within the rigid U-shaped channel 305 . In the embodiment shown in FIGS. 4A and 4B , the translatable pulley unit 330 includes two pulleys 326 , 327 that are rotatable about a single pulley axle 328 , however, in other embodiments, the translatable pulley unit 330 may contain one or more pulleys rotatable about the pulley axle 328 . Similarly, the fixed pulley unit 335 , as shown in FIGS. 4A and 4B , includes two pulleys 331 , 332 that rotate about a single pulley axle 333 ; however, in other embodiments, the fixed pulley unit 335 may contain one or more pulleys that rotate about the pulley axle 333 . A first end 319 of the spring 320 is fixed with respect to the rigid U-shaped channel 305 via a fastener 318 . In the disclosed embodiment, the fastener is a rivet; however the fastener could also be a support member welded between the two side walls of the rigid U-shaped channel 305 , a hook secured to or formed in the rigid U-shaped channel 305 , or any other device which secures the first end 319 of the spring 320 to the rigid U-shaped channel 305 . The second end 321 of the spring 320 is attached to a frame 325 , which houses the translatable pulley unit 330 . To connect the spring 320 to the frame 325 , the second end 321 of the spring 320 hooks through an opening 329 in the frame 325 . The cord 340 has a first end 341 and a second end 342 . The first end 341 of the cord 340 is attached to the frame 325 through a frame opening 322 . The second end 342 is attached to a jamb mounting hook 345 . The cord 340 is threaded through the translatable pulley unit 330 , the fixed pulley unit 335 , and around the bottom guide roller 350 , connecting the three components together. The cord 340 in the disclosed embodiment is a string, however it may also be a rope, or a cable. Both the fixed pulley unit 335 and the bottom guide roller 350 are fixed with respect to the rigid U-shaped channel 305 . The fixed pulley unit 335 is housed within a frame 336 and rotates around the pulley axle 333 . The frame 336 is secured within the rigid U-shaped channel 305 with a fastener 337 . In an alternative embodiment, the frame 336 is not required, the fixed pulley unit 335 rotates around an axle supported between side walls of the rigid U-shaped channel 305 . In yet another alternative embodiment, the fixed pulley unit 335 can be integral with the bottom guide 315 and as a result, fasteners 337 and 316 can be eliminated because tension of the spring 320 will keep the bottom guide 315 engaged with or connected to the rigid U-shaped channel 305 . The bottom guide roller 350 is located within the bottom guide 315 and rotates around a bottom guide axle 352 . A second distance “BB” 375 is defined as the length extending between the top angled portion 302 of the top guide 310 and the bottom guide axle 352 . It should be noted that the second distance “BB” 375 is greater than the first distance “AA” 275 of the window balance 200 .
To use the block and tackle window balance 300 within the window assembly, the balance is connected to both the widow jamb 107 and to either the lower window sash 104 or the upper window sash 106 . Substantially vertical front portions 301 , 311 of the top guide 310 and the bottom guide 315 , respectively, help guide movement of the balance 300 when installed in the jamb pocket 108 . Referring to FIG. 5 , the block and tackle window balance 300 is attached to the window jamb 107 via the jamb mounting hook 345 . The jamb mounting hook 345 is secured within an opening 430 within the jamb pocket 108 . The window balance 300 is then connected to a window sash by inserting a portion of the window sash into the channel 314 (formed from walls having an angled portion 317 ) of the bottom guide 315 and connecting a cam 405 mounted on the top of the window sash 400 to the top angled portion 302 of the top guide 310 , as shown in FIG. 6 .
The spring 320 of the window balance 300 creates the force required to counterbalance the weight of the window sash. However, because the bottom guide roller 350 is located in the bottom guide 315 , instead of within the rigid U-shaped channel 305 as in prior art balances, window sashes with the block and tackle window balances 300 as disclosed in this application provide greater travel distance. FIG. 7A is an illustration of a window assembly 500 with two prior art window balances 200 attached to a lower window sash 504 . In FIG. 7A , the lower window sash 504 is in a closed position. FIG. 7B shows the window assembly 500 , but with the lower window sash 504 in a fully open position. The standard travel distance of a window sash attached to the prior art window balance 200 is labeled “CC” 520 in FIG. 7B . The window sash 504 , as shown in FIGS. 7A and 7B , is prevented from achieving a greater travel distance by the roller 239 , located within the rigid U-shaped channel 205 , hitting the jamb mounting hook 245 .
FIGS. 8A and 8B show a schematic of the window assembly 600 with block and tackle balances 300 of the present invention. FIG. 8A shows the window assembly 600 in the closed position, while FIG. 8B shows the window assembly 600 in the fully open position. Because the bottom guide roller 350 is mounted within the bottom guide 315 instead of within the rigid U-shaped channel 305 , the window sash 604 can travel a greater distance before the bottom guide roller 350 hits the jamb mounting hook 345 , resulting in a greater travel distance, labeled “DD” 530 in FIG. 8B . It should be noted that the distance “DD” 530 is greater than the distance “CC” 520 . The greater travel distance is an important feature, because it allows for an increased window clearance that will help persons who are using the window assembly as an emergency exit.
Variations, modifications, and other implementations of what is described herein will occur to those of ordinary skill in the art without departing from the spirit and the scope of the invention as claimed. Accordingly, the invention is to be defined not by the preceding illustrative description but instead by the spirit and scope of the following claims. | 4y
|
BACKGROUND OF THE INVENTION
This invention relates to hot melt tanks for dispensing a molten thermoplastic. In one aspect it relates to hot melt tanks which comprise a hopper and a pump connected to the hopper for dispensing the thermoplastic. In a specific aspect, the invention relates to a pump assembly which is designed to be rapidly disengaged and removed from the hopper for repair or replacement with a new assembly.
Hot melt tanks are used in a number of commercially important applications which include the application of hot melt polymer adhesives for bonding furniture parts, diaper backings, and automotive parts, to name a new. Most, if not all, hot melt tanks comprise an electrically heated hopper and a pump connected to the hopper outlet. Thermoplastic pellets are introduced into the top of the hopper wherein they are heated to a temperature above the melting point of the thermoplastic. The molten thermoplastic settles to the bottom of the hopper which has an outlet flow passage feeding into the pump. The pump draws the molten polymer from the hopper and discharges the polymer into a flow line connected to a dispensing means. Hot melt tanks have been described in U.S. Pat. No. 5,061,170.
The article of manufacture whereon the adhesive is applied may be generically referred to as the substrate. In some applications the dispensing means may comprise a flexible hose connected to the pump at one end and at the opposite end connected to a dispensing gun. The operator may manually move the gun to the bonding points on the substrate for applying the adhesive. In other applications the pump may discharge into a flow line connected to stationary spray nozzles which are directed onto a moving conveyor line. The substrate will be placed on the conveyer line and will pass under the spray nozzles. The nozzles may be oriented to discharge the adhesive onto the substrate in a desired pattern and/or be equipped with valving for selectively turning nozzles on or off to achieve the desired pattern. This is important for substrates having an irregular shape. The operation of the hot melt tank comprising the hopper and the pump is the same, whether the adhesive is applied to the substrate using dispensing means comprising a movable spray gun or stationary spray nozzles.
The operation of the pump of the hot melt tank requires peripheral devices including an electric motor which is often coupled to the pump through a gear box for speed reduction. In addition the pump usually discharges into a manifold which houses a filter and a pressure relief valve for safety. The manifold has an outlet line which discharges the molten polymer to the dispensing means. Positive displacement gear pumps of the type described in U.S. Pat. Nos. 5,061,170 and 5,236,641 have been used in hot melt tanks.
A problem in hot melt tanks of the prior art is encountered when the pump or any of the peripheral devices must be removed for repair or replacement. In this case the production line must be shut down and the faulty component removed. This is often a time consuming task due to the spatial and/or mechanical interrelationship of the components of the hot melt tank. For example, a common problem is that the pump has become plugged and needs cleaning or repair. In this instance it is generally not possible to remove the pump without also removing one or more of the peripheral components as well. The pump and peripheral components are generally mounted on a frame secured to the floor by bolts or other connectors. Thus, for replacing the pump it is usually necessary to disassemble component-by-component from the frame, and reverse the procedure by reassembling the assembly with a new or repaired component. The production down-time for this procedure may be on the order of six hours or more. This is the case even if a new pump is available for replacing the faulty pump since most of the down-time is associated with the removal and replacement of parts. The economic implications of this time consuming procedure are obvious.
In summary, hot melt tanks comprise a heated hopper for providing a source of molten thermoplastic often used as adhesives. The tank further comprises a pump and peripheral devices for delivering the thermoplastic to a dispensing means for applying the thermoplastic to a substrate. In prior art tanks, the procedure for replacing the pump and/or peripheral devices is complicated by the mechanical interrelationship of the tank components and results in lengthy production down-time.
SUMMARY OF THE INVENTION
The present invention provides a hot melt tank having a novel pump assembly which may be rapidly connected and disconnected to the hopper of the tank. In the event the pump or peripheral device becomes plugged or damaged, the assembly may be removed as a unit and replaced with a new assembly unit. The use of the present pump assembly reduces production down-time to a matter of minutes.
The hot melt tank of the present invention comprises a main frame with the hopper secured thereto and a pump assembly removably secured to the hopper. The pump assembly comprises a subframe having secured thereto a manifold, a gear pump, and an electric motor coupled to the pump through a gear box. The pump assembly may be attached and detached from the hopper as a unit for minimizing production down-time.
The manifold of the assembly has a mating surface which slidingly engages with a mating surface on the underside of the hopper. The manifold mating surface has a polymer inlet which registers with the hopper outlet for conducting the molten polymer to the pump of the assembly. The pump discharges the molten polymer into a flow line which conducts the polymer to a dispensing means. The dispensing means may be either a moveable dispensing gun on a flexible hose, or alternatively, stationary spray nozzles adapted to discharge onto a substrate on a moving conveyor.
The pump assembly further in a preferred embodiment includes wheels which are fixed to either side of the assembly and adapted to roll along a track formed on the main frame of the hot melt tank. The installation and/or removal of the pump assembly comprises three positions. A first position wherein the assembly is completely disengaged from the hopper and is supported on the track (e.g. by the wheels of the assembly). From the first position, the assembly is moved as a unit to the second position which is located under the hopper. In the second position the assembly is slidingly engaged with the hopper with the manifold inlet and hopper outlet in vertical alignment but slightly spaced apart in the vertical direction. The third position which is the fully engaged operational position, is achieved by moving the assembly upward as a unit whereby the spaced apart flow passages of the second position are compressed together and a fluid seal is established therebetween. Alignment means are provided whereby the polymer flow passages of the hopper and pump assembly precisely register at the interface of the hopper and the assembly. The movement of the assembly from the second to the third position is accomplished using a wedge mechanism which imparts an upward force on the assembly whereby the assembly is moved rectilinearly (i.e. it does not tilt to one side or the other or rotate) and vertically as a unit off the track and secured to the hopper for operation. For removing the pump assembly, the procedure is reversed so that the assembly moves from the third, to the second, and finally to the first position.
For removing a plugged or damaged pump assembly, a shut-off valve is provided to temporarily discontinue the flow of polymer from the hopper to the pump assembly. The plugged assembly may be rapidly removed as a unit and a replacement assembly moved into place following the steps above. The shut-off valve is then opened and production resumed within a matter of minutes. The removed assembly may then be repaired off-line for later use. The use of the present pump assembly significantly reduces the downtime associated with pump and/or pump peripheral device failure and, therefore, improves the economics of hot melt tanks.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation of the pump assembly in the operating position (described as third position) with frame portions cut away to illustrate details.
FIG. 2 is a side view similar to FIG. 1, illustrating the pump assembly in the fully disengaged position (described as first position) disconnected from the hopper.
FIG. 3 is a sectional side view taken along the 3--3 of FIG. 4 of the hopper and pump assembly.
FIG. 4 is a rear partially sectional view taken along line 4--4 of FIG. 1 of the hopper and pump assembly.
FIG. 5 is a partial sectional view taken along line 5--5 of FIG. 3 illustrating the rectilinear and vertical movement of one pump assembly from the second to the third positions.
FIG. 6 is a schematic taken along line 6--6 of FIG. 5 illustrating the kinematics of the wedge mechanism for lifting the pump assembly from the second to the third position.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The components of the hot melt tank and the flow of polymer therethrough are first described, followed by a detailed description of the steps and apparatus for installing or removing the pump assembly as a unit from the hot melt tank.
Hot Melt Tank and Polymer Flow
Referring to FIG. 1, hot melt tank 10 comprises main frame 11, hopper 12, and pump assembly 13. Frame 11 will normally be secured to concrete flooring or the like for safety. Hopper 12 is secured to the frame using bolts as at 14. In the operating position, pump assembly 13 is detachably secured to hopper 12 as will be described.
FIGS. 1, 3, and 4 illustrate the pump assembly in the fully operational position (third position). As seen in the Figures, hopper 12 comprises a top portion having an inlet or lid 16 wherein solid thermoplastic pellets are introduced. The hopper comprises heating elements (not shown) which heat the hot melt thermoplastic to the molten state whereby a source of molten thermoplastic fills the bottom of the hopper in reservoir 17. Hopper 12 further comprises base plate 15 in fluid communication with reservoir 17 through passages 18 and 19. Base plate 15 has outlet passage 21 in communication with passage 19 across rod-type valve 22. As seen in FIGS. 3 and 4, rod valve 22 comprises elongate rod 23 having port 24 which registers with passages 19 and 21 with the valve in the open position. The rod is rotated 90 degrees using handle 26 to close the valve by blocking the space between passages 19 and 21. The valve is shown in the open position in FIG. 3 and in the closed position in FIG. 4. Valve 22 is provided to temporarily shut off the flow of polymer to pump assembly 13 while the assembly is being replaced as described below. Base plate 15 may be secured to hopper 12 by bolts 20 passing through flange 25. Note that in FIG. 4, the system is constructed to accommodate two pump assemblies 13, one illustrated in the first position, and the second (not shown) adapted to be inserted in space 107. Rod 23 is provided with two openings 24 (shown in the closed position), one for each pump assembly.
As best seen in FIGS. 1 and 3, pump assembly 13 comprises manifold 31, pump 32 for delivering hot melt to the manifold, electric motor 33 drivingly coupled to the pump through gear box (speed reducer) 34, shaft coupling 35, and shaft 28. As will be described below, the pump assembly 13 is mounted as a unit on a subframe, which permits the pump assembly unit to be moved relative to the main frame 11 and hopper 12.
Pump 32 comprises body 37 which is secured to manifold 31 by bolts (not shown). Motor 33 and gear box 34 may be secured to the assembly by bolting (not shown) through subframe 29 which is secured to pump 32 and manifold 31 using bolts.
Pump 32 is preferably a positive displacement pump such as a gear pump. Pump 32 has an internal cavity wherein gear 36 is rotatably disposed. Gear 36 defines inlet cavity 39 fed by inlet passage 39 and outlet cavity 41 discharging to outlet passage 51. As gear 36 rotates, polymer material in cavity 39 is entrapped in the teeth of the gear and is transferred and pressurized into cavity 41. The gear pump actually comprises a pair of counter-rotating gears which entrap the polymer between the meshed teeth of the gears. In the view of FIG. 3, the second gear is hidden by gear 36. Pump 32 is also provided with fluid seals 42 and 43 and shaft bearing 44. The preferred pump 32 is a positive displacement gear pump of the type disclosed in U.S. Pat. No. 5,236,641, the disclosure of which is incorporated herein by reference. This pump has a throughput directly proportional to pump speed. Motor 33 may be provided with electronic controls 38 to control the pump speed.
As may be seen in FIGS. 3 and 4, manifold has formed thereon a mating surface 45, which engages with mating surface 46 of base 15. Manifold 31 has formed therein inlet polymer flow passage 48 which registers with hopper outlet 21 at one end and with pump inlet 49 at the other end for conducting molten polymer from the outlet passage to pump inlet cavity 39. By means described below, the manifold is maintained in compressive contact relationship with plate 15 so that the compression between the mating surfaces 45 and 46 is sufficient to establish a fluid seal around the intersection of passages 21 and 48. O-ring 47 is provided to further establish the seal. Manifold 31 further comprises flow passage 52 which registers with pump outlet passage 51 for receiving pressurized polymer from pump outlet cavity 41. Molten polymer entering passage 51 flows through filter 56, into passages 57, through intersecting outlet passage 58 and into discharge line 59. Line 59 is connected to an external dispensing means such as a dispensing gun or dispensing nozzles. Molten polymer thus flows from reservoir 17, through passages 18 and 19, through valve port 24, through passages 21, 48, and 49, into pump cavity 39, across gear 36, into cavity 41, through passages 51 and 52, through filter 56, through passages 57 and 58, and finally into outlet line 59.
Filter 56 is a tubular filter wherein the polymer flows through the inner core of the filter and radially outward through the permeable filter walls. The filter is provided with O-rings 61 and 62 for sealing the filter ends so that the polymer must flow through the filter core. Filter 56 may be a cartridge-type filter which may be removed by unscrewing cartridge cap 63 and pulling the filter out of the manifold. Manifold 31 also has formed therein second outlet flow passage 64 which may be used as an alternative to outlet passage 58. The outlet passage not in use will be capped using a bolt 66 or other means. Manifold 31 and base 15 have formed therein by-pass lines 67a and 67b, provided with a check valve 68 for returning flow to reservoir 17. The check valve 68 may be spring loaded to maintain a minimum pressure on the by-pass line 67. Alternatively, a separate by-pass valve may be provided in line 67. The manifold may also be provided with a pressure relief valve 69 for safety.
The components of the pump assembly, base plate, and hopper should be constructed of high quality steel to resist corrosion and to withstand the high temperature operation.
Pump Assembly Subframe: Tracks and Wedge Mechanism
The subframe comprises two main parts for providing two functions: (1) tracks for supporting assembly 13; and (2) a wedge mechanism for engaging the assembly 13 to hopper 12.
Tracks:
Referring to FIGS. 1 and 4, pump assembly subframe comprises side plates 71 and 72 secured to opposite sides of the manifold 31 by bolts 73 and spacers 74. On the bottom of plates 71 and 72 are rotatably mounted wheels 76a and 76b. Main frame 11 has secured thereto parallel, horizontal track members 77a and 77b whereon the wheels (76a and 76b) guidingly roll. The tracks 77a and 77b have a portion positioned directly below the hopper 12 and extend a sufficient distance to permit the assembly 13 to be moved to a fully retracted position (see FIG. 2). Assembly 13 may thus be manually moved as a unit by pushing or pulling the unit whereby wheels 76a and 77b roll along tracks 77a and 77b, respectively, between the first and second positions. In the first position, the assembly is in a fully retracted position (FIG. 2), permitting its removal from the tracks. In the second position (FIG. 1), the assembly 13 is directly below hopper 12.
As indicated above, and as described in more detail below, the pump assembly is selectively movable to three positions:
First Position:
In this position, the pump assembly 13 is completely detached from hopper 12 and outlet line 59 and is positioned on tracks 77a and 77b with the weight of the assembly being supported on wheels 76a and 76b. This position is illustrated in FIG. 2.
Second Position:
In this intermediate position, pump assembly 13 is located under hopper 12 with hopper outlet 21 and manifold inlet in vertical alignment but slightly spaced apart in the vertical direction. The assembly is moved from first to second position by rolling the assembly along tracks 77a and 77b as has been described. The positioning of the assembly 13 relative to the manifold 31 for aligning hopper 12, flow passage 21, and manifold passage 48 is achieved using plate 78 mounted on the top side of pump 32 (see FIG. 3) which contacts the side of base plate 15 as at 79 with the assembly 13 in the aligned position. The second position is illustrated in FIG. 5 by the dashed lines where it is seen that wheels 76a and 76b are in contact with tracks 77a and 77b, respectively.
Third Position:
This position is the operating position of the pump assembly 13 (see FIG. 1). The third position is achieved by lifting the pump assembly from the second position whereby hopper mating surface 46 and manifold mating surface 45 are compressed together thereby establishing a fluid seal at the junction of passages 21 and 48. As described below, a wedge mechanism is used to lift the pump assembly 13 rectilinearly (i.e. it does not tilt one way or another as it moved nor does it rotate from the second to the third position. The third position is illustrated in FIG. 5 by the solid lines. FIGS. 1, 3, and 4 also illustrate the third position. As mentioned above, the positioning of the pump assembly 13 relative to hopper 12 in the rolling direction is achieved using stopper 78. For aligning flow passages 21 and 48, the precise positioning of the assembly as it is lifted and secured to the hopper may be accomplished using dowel pin 81 mounted on surface 45 and complementary shaped hole formed in surface 46.
From the foregoing it is seen that installing the pump assembly involves the steps of rolling the assembly along tracks 77a and 77b from the first position to the second position, then lifting the assembly using the wedge mechanism described below from the second position to the third position 3 whereby the assembly is secured to the hopper for operation. Removing the pump assembly involves a reversal of these steps.
Wedge Mechanism:
The movement of pump assembly 13 from the second position to the operating third position is achieved by the wedge mechanism. The mechanism which is used to move the assembly 13 upwardly, as the name suggests, operates on the kinematical principles which govern the motion of sliding wedges.
Referring to FIGS. 4 and 5, manifold 31 has machined on either side angular grooves 83 and 84 defining downward facing wedges 86 and 87, respectively. Wedges 86 and 87 are parallel and have downward facing surfaces 88 and 89, respectively. For slidingly engaging with wedges 86 and 87, hopper base 15 has secured to the underside thereof upward facing stationary wedge 93 and upward facing movable wedge 94. Wedge 93 may be attached to base 15 using bolts 91. As best seen in FIG. 5, wedge 94 is movable laterally within housing 99 in the horizontal direction as illustrated by arrow A. The housing 99 may be secured to base 15 using bolts 92. The wedge is movable between the limits illustrated by solid line 96 and the retracted position illustrated by dashed line 97 so that as the wedge moves from 97 to 96 the distance between wedges 93 and 94 decreases. With the wedge 94 in the retracted position there is sufficient clearance between wedges 93 and 94 for the pump assembly 13 to be rolled therebetween as has been described in relation to the first and second positions. As the pump assembly 13 is moved into the second position, manifold wedge 86 slidingly engages with stationary wedge 93 and the other manifold wedge 87 slidingly engages with movable wedge 94 (in the retracted position). The second position is achieved when the rolling motion is terminated by stopper 78 contacting the side of base plate 15 at 79 whereby assembly 13 is aligned with base 15 in the rolling direction by the stopper and in the direction perpendicular thereto by the engagement wedges 86 and 87 with wedges 93 and 94, respectively.
Referring now to FIG. 5, the second position is illustrated by the dashed lines, whereas the third position is illustrated by the solid lines. For lifting the assembly movable wedge 94 is driven from 97 to 96 toward stationary wedge 93 and slidingly contact wedge surface 89 of wedge 87. The wedge angle C is preferably between 30 to 60 degrees and most preferably about 45 degrees. The wedged relation of wedge 94 and surface 89 induces an upward force upon surface 89 and the unitary pump assembly 13 as a whole. The contact of wedge 94 with surface 89 also induces a sideways force away from wedge 94 which forces wedge surface 88 into sliding contact with stationary wedge 93. The wedged contact imparts an upward force on surface 88 which acts to lift the opposite side of the pump assembly. Thus wedges 93 and 94 simultaneously impart an upward force on surfaces 88 and 89, respectively, as movable wedge 94 is driven towards stationary wedge 93. The upward forces are sufficient to lift the pump assembly, and wedge 94 is driven inward a distance which compresses hopper surface 46 and manifold surface 45 with a compressive force sufficient to establish a fluid seal around passages 21 and 48. Note that with the manifold 31 in the second position, the inlet 48 is vertically aligned with passage 21.
Importantly, because of the kinematic and symmetrical configuration of engaging wedges 86 and 93 in relation to engaging wedges 87 and 94, the upward forces acting on surfaces 88 and 89 are very nearly equal whereby the assembly moves rectilinearly (i.e. it does not tilt to one side or the other) as it moves vertically upward from position 2 to position 3. As the assembly 13 and base 15 are brought together, polymer flow passage 21 is joined to passage 48 in compressive engagement. O-ring 47 is provided to further establish the sealing at the junction of the passages.
The lowering of pump assembly 13 from the third to the second position, as in removing the assembly, is accomplished by retracting wedge 94 outward from position 96 to 97 away from stationary wedge 93 whereby gravity lowers the assembly. The assembly is lowered rectilinearly with wedges 93 and 86 in sliding engagement and wedges 94 and 87 in sliding engagement. The assembly is lowered until wheels 76a and 76b contact tracts 77a and 77b. The motion of wedge 94 is controlled by the locking mechanism described below wherein wedge 94 is moved in a continuous motion so that prior to contacting the tracks, the assembly is supported on wedges 93 and 94 as it is lowered.
From the above it is seen that in both the upward and downward motions, wedge 94 moves horizontally as indicated by arrow A and assembly 13 moves rectilinearly and vertically as indicated by arrow B. As wedge 94 is driven towards the stationary wedge 93 the assembly is raised, whereas a wedge motion away from the stationary wedge lowers the assembly. The rectilinear and vertical motion of assembly 13 as wedge 94 is moved horizontally are kinematically required by the sliding wedge design.
As best seen in FIG. 6, wedge 94 is driven from position 2 to position 3 (to the left as illustrated in FIG. 5) by a locking mechanism 100 (for simplicity of description, FIG. 6 illustrates the wedges without the manifold 31 disposed therebetween) which comprises housing 99, movable wedge 94 in sliding contact with movable locking wedge 101 along wedge surface 104, and locking bolt 102 having threads 95 threaded into end 103 of wedge 101. In both FIGS. 5 and 6, position 2 is illustrated by the dashed lines and position 3 illustrated by the solid lines. For moving wedge 94 from position 2 to position 3, locking bolt 102 is turned drawing wedge 101 to the right as viewed in FIG. 6. Due to the kinematical wedged relation at 104 between members 94 and 101, the motion of wedge 101 towards bolt 102 drives wedge 94 outward towards stationary wedge 93. Wedge 94 is provided with slots 105 which movably engage pins 106 which are fixed to housing 99. Slots 105 and pins 106 movably secure wedges 94 and 101 to the housing. Thus in the locking mechanism 100, locking wedge 101 moves in the direction E whereas wedge 94 moves perpendicular thereto in the direction A. The distance between wedges 94 and 93 may be selectively increased or decreased within the limits of slot 106. A wedge angle, labeled D in FIG. 6, of between 5 to 15 degrees is preferred with about 10 degrees is most preferred.
From the foregoing it can be appreciated that pump assembly 13 may be moved from position 2 to position 3 by the steps of turning locking bolt 102 whereby locking wedge 101 moves toward the bolt and whereby the wedged relation of members 101 and 94 kinematically requires that wedge 94 move outward towards wedge 93, thereby decreasing the distance between the wedges. The motion of wedge 94 toward wedge 93, and the slidingly wedged relation of wedges 94 and 87 as well as the slidingly wedges relation of wedges 93 and 86 requires kinematically that assembly 13 move recti-linearly and vertically upward. Thus the sliding motion of wedges 94 and 86 and that of wedges 93 and 86 occurs simultaneously at the same rate. Wedge 94 is moved towards wedge 93 to sufficiently compress hopper surface 46 and manifold surface 45 together to establish a fluid seal therebetween and to secure pump assembly 13 in the operating position.
In the downward motion from the third to the second position, bolt 102 is turned so that wedge 101 moves away from the bolt. Half of the weight of the pump assembly is supported by wedge 94 acting through wedge 87 with the remaining half supported on wedge 93 acting through wedge 86. The weight imparts an outward force on wedge 94 which drives wedge 94 away from stationary wedge 93. The motion of wedge 94 away from wedge 93, and the slidingly wedged relation of wedges 94 and 87, as well as 93 and 86, kinematically requires that the pump assembly move rectilinearly and vertically downward. It should be noted that the motion of wedges 101 and 94 is continuous as bolt 102 is turned. Therefore, as assembly 13 is raised or lowered between positions 2 and 3, the weight of the assembly is supported by the contact of wedges 86 and 87 on wedges 93 and 94, respectively.
As best seen in FIG. 4, main frame 11 may be adapted to accommodate more than a singly pump assembly by providing additional means of the type described above, whereby each pump assembly operates independently of other assemblies. FIG. 5 illustrates a frame for receiving two independent pump assemblies with only one assembly installed. A second assembly may be installed as at 107 which is equipped with independent wedge means for lifting the assembly from positions 2 to 3 as has been described. The movable wedge 94 may share a common housing 99 as illustrated in FIG. 4 wedge for 107 space being labeled 108. Wedges 94 and 108 are operated independently by turning their respective locking bolts.
While a pump assembly having a single polymer inlet and a single polymer outlet have been described, it is also possible to have an assembly having a single inlet and multiple outlets. The assembly may comprise a single inlet which splits to feed separate pumps in parallel which in turn feed each outlet independently. Alternatively, the assembly may comprise a single pump with a discharge which splits to feed multiple outlets in parallel.
The apparatus of the present invention is illustrated in FIG. 4 with separate hoppers 12. In practice one hopper may be used to feed one or more pump assemblies.
Operation
In operation, the pump assembly 13, as an integrated unit, is placed on track 77a and 77b (position 1) and moved to position 2 along the track. The manifold grooves 83 and 84 mate with wedges 93 and 94 and serve as lateral guides for positioning the manifold inlet 48 in alignment with plate passage 21. Upon reaching stop 78, the manifold inlet 48 is in longitudinal alignment (i.e. direction of manifold movement) with passage 21. Note that the other mating openings such as passage 67a and passage 67b are also in alignment with the pump assembly in the second position. The flexible hose 59 may be connected to the manifold 31 with the assembly 13 in position 1 or position 2. With the assembly 13 in position 2, the wedge mechanism is operated moving the assembly 13 to position 3. The hopper feed valve is opened placing the system in the operating position.
In replacing or repairing a defective part of the assembly, the procedure is reversed: the hopper valve is closed, the wedge mechanism is operated to move assembly 13 vertically downward to position 2, and the assembly 13 is then removed along the tracks to position 1, exposing the parts for repair or replacement. Note that check valve 68 prevents the flow from hopper 12 into the filter chamber.
Any of the hot melt adhesives may be used in the apparatus of the present invention. These include EVA's (e.g. 20-40 wt % VA). These polymers generally have lower viscosities than those used in meltblown webs. Conventional hot melt adhesives useable include those disclosed in U.S. Pat. Nos. 4,497,941, 4,325,853, and 4,315,842, the disclosures of which are incorporated herein by reference. The preferred hot melt adhesives include SIS and SBS block copolymer based adhesives. These adhesives contain block copolymer, tackifier, and oil in various ratios. The above melt adhesives are by way of illustration only; other hot melt adhesives may also be used.
Most hot melt adhesives are applied at temperatures ranging from about 270° F. to about 340° F., well within the operating temperatures of the apparatus of the present invention. In order to maintain the proper temperature through the assembly 13, electric heaters may be provided in manifold 31, in which case flexible electric lines would be connected to the heaters by conventional means. | 4y
|
INTRODUCTION
This application is a continuation-in-part of application Ser. No. 07/911,206 entitled Automatic Fluid Flow Control Device filed Jul. 9, 1992, now U.S. Pat. No. 5,230,366.
FIELD OF THE INVENTION
The present invention relates to fluid flow control devices, particularly automatic fluid flow control devices.
BACKGROUND
Fluid flow control assemblies of the prior art generally comprise two or more components. The components, as many as six or more, are pieced together in series. The assemblies require many joints, usually threaded, and usually have relatively long lengths. These are major drawbacks of the prior art assemblies because the more threaded joints a device has, the longer it takes to install the device and the higher the risks of leaks occurring in the device. In addition, the longer the length of a device, the more installation room it requires.
Another problem with prior art assemblies is that a plumbing system incorporating a prior art assembly is not easily subjected to excessive flow to flush the system without clogging the various components. Certain components of the assembly impede flow through the assembly and, therefore, would impede a high pressure flow therethrough for flushing. Furthermore, the impeding components of the prior art assemblies are not easily removable. Indeed, some prior art assemblies must be taken off-line to remove or replace such components.
SUMMARY OF THE INVENTION
The present invention relates to a plumbing system which incorporates a plurality of automatic fluid flow control devices each having a unitary body which contains at least one flow member (such as a strainer or a flow control cartridge or both). The automatic fluid flow control devices may be installed in a plumbing system. Preferably, the flow member (e.g. strainer or flow control cartridge or both) is removed prior to installation. Once everything is connected in the plumbing system, it may then be provided with excessive flow to flush out the system and then the flow member(s) may be replaced or installed. In this manner the system can be flushed without clogging the flow member(s) prior to placing the system in regular operation.
The automatic fluid flow control device includes, among other things, a ball valve for controlling gross fluid flow through the device, a strainer member for straining fluids upon entering the device, and a pressure compensating flow control valve which provides for constant fluid flow through and out of the device. The flow control valve is pre-set and, therefore, the flow through the device is tamper resistant. These components are provided in a compact assembly which allows easy access to each of the components for cleaning and/or replacing and which embodies the device of the present invention.
The novel design and construction of an automatic fluid flow control device according to the present invention provides a singular body which minimizes both (1) the number of threaded joints (thereby minimizing the time it takes to install the device and the risks of leaks in the device) and (2) the size of the device (thereby minimizing the space needed for installation).
Accordingly, a principal object of this invention is to provide an improved automatic fluid flow control system and an improved automatic fluid flow control device.
It is also an object of this invention to provide a plumbing system comprising a plurality of improved automatic fluid flow control devices.
It is another object of this invention to provide an automatic fluid flow control device in which the flow setting is tamper resistant because the flow control valve is pre-set.
It is a further object of the present invention to provide an automatic fluid flow control device in which the flow control valve is a pressure compensating valve.
An additional object of the present invention is to provide an automatic fluid flow control device in which any flow member is easily accessible and replaceable without taking the device off line.
It is still another object of the present invention to provide an automatic fluid flow control device in which any flow member can be removed and left out before or during installation.
The present invention relates to a fluid flow control system having an automatic fluid flow control device which provides a constant fluid flow even though a variety of supplied pressures occur. The configuration of the body of the device provides for a compact size and easy access to various components of the device including a fluid strainer and a flow control cartridge which may be removed and/or replaced without taking the device off-line. With the strainers and flow control cartridges removed from the devices in the system, excessive fluid flow may be provided to the system to flush it. Once flushing is completed, the strainers and flow control cartridges may be replaced or installed. The device also includes access ports which provide for testing the pressure and/or temperature in the device at various locations.
The structure of a valve according to the present invention is such that when fluid flows into the device, it first encounters a positionable ball valve. The ball valve, depending on its position, either prevents the fluid from entering the rest of the device or allows the fluid to flow into the rest of the device. If the fluid flows into the rest of the device, it then encounters a fluid strainer member.
The fluid strainer member strains and filters the fluid for preventing contaminants from entering the rest of the device and/or exiting from the device. The fluid strainer member is easily accessible and may be easily removed to allow for cleaning, replacement, and/or flushing. Once the fluid passes through the strainer, it encounters an automatic flow control valve.
The automatic flow control valve provides for a constant fluid flow rate despite a varying differential pressure. A variety of flow control cartridges may be used in the flow control valve depending on the flow rate desired. Suitable automatic flow control cartridges are available from Griswold Controls, Irvine, California, which may be of the type disclosed in U.S. Pat. No. 3,752,183. The automatic flow control valve is positioned in the device of the present invention such that it is easily accessible and may be removed to allow a high pressure flush of the device and/or replaced with a different flow control valve without taking the device off-line. Once the fluid passes through the flow control valve, it exits the device at a selected flow as determined by the cartridge used.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is an elevational view of the front of an assembled preferred embodiment of an automatic fluid flow control device of the present invention.
FIG. 1B is an elevational view of the left side of the device of FIG. 1A.
FIG. 2 is an exploded view of the device of FIG. 1A showing the components of the device and their spacial relationship.
FIG. 3 is a cross-sectional view illustrating the internal configuration of the device of FIG. 1A.
FIG. 4 is a diagrammatic view of a system comprising a plurality of the devices of FIG. 1A.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention relates to a method of plumbing a facility and the resultant plumbing system, and the valve involved. The plumbing system comprises a plurality of automatic flow control devices (described in detail below) which contain a flow member to provide strained fluid flow at a selected flow rate regardless of the supplied fluid flow pressure. The flow member comprises a strainer or an automatic flow control cartridge or both. The devices enable easy access to and removal and installation of any flow member of the device. Removal of the flow member(s) enables an excessive fluid flow to be supplied to the system to flush the system without clogging these components.
A description of the automatic flow control devices will be helpful. Turning to the drawings, FIGS. 1A, 1B, 2, and 3 show a preferred embodiment of the flow control device of the present invention in the form of an automatic fluid flow control device 10. As best shown in FIGS. 2 and 3, the device 10 comprises four main components: a valve body 12, a positionable ball valve assembly 14, a removable strainer assembly 16, and a removable flow control valve assembly 18.
As best shown in FIG. 2, the valve body 12 includes six orifices: an inlet orifice 20, an outlet orifice 22, a flow control valve orifice 24, a test valve orifice 26, a strainer orifice 28, and a ball valve fitting orifice 30. The valve body 12 also includes: a top side 32, a bottom side 34, a front side 36, a back side 38 (FIG. 1B), a left side 40, and a right side 42.
Furthermore, as shown in FIG. 3, the valve body 12 comprises several internal channels for directing fluid flow through the device 10. These channels include: a ball valve channel 14a; a ball valve-strainer connecting channel 15; a strainer channel 16a; a strainer-flow control valve connecting channel 17; a flow control valve channel 18a; and an outlet channel 19. When the device 10 is assembled, as in FIG. 3, the ball valve channel 14a comprises the location of the ball valve assembly 14, the strainer channel 16a comprises the location of the strainer assembly 16, and the flow control valve channel 18a comprises the location of the flow control valve assembly 18. The channels 14a, 15, 16a, 17, 18a, and 19, together form a fanciful backwards "Z" configuration with channels 19 and 18a comprising a top arm of the Z, channel 17 comprising a body of the Z, and channels 16a, 15, and 14a comprising a bottom arm of the Z.
A general description of the positioning and operation of the device 10 will be helpful to understanding the detailed description of the device 10 given below. The device 10 is connected between two pipes or lines with the ball valve fitting orifice 20 attached to a pipe or line which is to be regulated and the outlet orifice 22 is attached to on outlet pipe. Turning to FIG. 3, the general operation of the device 10 involves the following seven steps:
(1) A fluid flow of varying pressures enters the device 10 through the inlet orifice 20 at the left side 40.
(2) The fluid flow encounters the ball valve assembly 14 which, depending upon its position, either allows the fluid to enter or prevents the fluid from entering the device 10.
(3) If the fluid enters the device 10, it then passes through the connecting channel 15 to the strainer assembly 16.
(4) The fluid flow passes through the strainer assembly 16 which strains debris out of the fluid flow so it neither passes through nor out of the rest of the device 10 particularly the removable flow control valve assembly 18.
(5) The strained fluid then passes through the connecting channel 17 to the flow control valve assembly 18.
(6) The flow control valve assembly 18 automatically regulates the fluid flow such that the fluid exits the valve assembly 18 at a constant, pre-selected, rate.
(7) The strained and regulated fluid flow then passes through the outlet channel 19 and the outlet orifice 22, and exits the device 10.
Thus, the device 10 provides automatically controlled fluid flow from fluid supplied at varying pressures in a very compact and simple apparatus.
Turning to the Figures, the device 10, and particularly the configuration of the valve body 12, in more detail, the inlet orifice 20 and the outlet orifice 22, located on the left 40 and right 42 sides of the valve body 12 respectively, comprise openings in the valve body 12 and respectively define a ball valve channel 14a and an outlet channel 19 which are aligned on a common axis and oppositely faced. The flow control valve orifice 24 comprises an opening on the top side 32 of the valve body 12 and defines a flow control valve channel 18a which is acutely angled upward from the common axis toward the inlet orifice 20. The test valve orifice 26 comprises an opening on the top side 32 of the valve body 12 which is upwardly angled from the common axis at approximately a ninety degree angle and is located between the flow control valve orifice 24 and the outlet orifice 22.
The strainer orifice 28 comprises an opening on the bottom side 34 of the valve body 12 and defines a strainer channel 16a which is acutely angled downward from the common axis toward the outlet orifice 22. The ball valve fitting orifice 30 comprises an opening on the front side 36 of the valve body 12 which is outwardly angled from the common axis at approximately a ninety degree angle and is located on the ball valve channel 14a between the inlet orifice 20 and the connector channel 15.
As shown in FIGS. 2 and 3, the ball valve assembly 14 comprises a conventional isolation ball valve arrangement assembled in the ball valve channel 14a of the valve body 12 near the inlet orifice 20. Two packing washers 44a and 44b are placed in the ball valve channel 14a of the valve body 12 through the inlet orifice 20 with a ball valve 46 movably seated between them. The ball valve 46 is movable from an open position to a closed position and vice versa by a handle 70 to be described later. An inlet fitting 50 holds the packing washers 44a and 44b and the ball valve 46 in place in the channel 14a of the valve body 12. The inlet orifice 20 of the valve body 12 has inner threads 52 and inlet fitting 50 has matching outer threads 54 for attaching the inlet fitting 50 to the valve body 12. The inlet fitting 50 also has inner threads 56 for attaching the device 10 to an inlet pipe (not shown). The inlet fitting may be any one of a variety of sizes to connect to a variety of sizes of inlet pipes. The packing washers 44a and 44b and a ring 48 provide tight seals between: (1) the valve body 12 and the ball valve 46; (2) the ball valve 46 and the inlet fitting 50; and (3) the inlet fitting 50 and the valve body 12.
In addition, a shaft 58 engages the ball valve 46 through the ball valve fitting orifice 30. A washer 60 and a fitting 62 hold the shaft 58 in place. The ball valve fitting orifice 30 has inner threads 64 and fitting 62 has matching outer threads 66 for attaching the fitting 62 to the valve body 12. Furthermore, a screw 68 attaches a handle 70 to the shaft 58 thereby providing means for manipulating the position of the shaft 58 thereby manipulating the position of the ball valve 46. The shaft 58 has inner threads 72 and the screw 68 has matching outer threads 74 for attaching the screw 68 (and the handle 70) to the shaft 58.
Also shown in FIGS. 2 and 3, the strainer assembly 16 comprises a strainer 76 which is placed in the strainer channel 16a of the valve body 12 through the strainer orifice 28 and is held in place in the strainer channel 16a by a threaded cap 80. The strainer orifice 28 has inner threads 82 and the threaded cap 80 has matching outer threads 84 for attaching the threaded cap 80 to the valve body 12 thereby holding the strainer 76 in the valve body 12. A washer 78 is disposed between the valve body 12 and the threaded cap 80 and provides a seal between the threaded cap 80 and the valve body 12. The threaded cap 80 includes a test port 86 and a strainer fitting 88 for providing access to fluid in the valve body 12 without disassembling the device 10. The test port 86 includes inner threads 90 and the strainer fitting 88 includes matching outer threads 92 for attaching the strainer fitting 88 to the threaded cap 80.
The strainer fitting 88 provides the device 10 with blow down capability for flushing out debris accumulated in the strainer 76. By closing the ball valve assembly 14 thereby preventing fluid flow through the inlet 20 and removing the strainer fitting 88 from the test port 86, a reverse fluid flow through the device is created which forces any debris collected in the strainer 76 out the test port 86. A small ball valve (not shown) may be used in place of the strainer fitting 88 to facilitate back flushing the strainer 76 in this manner.
FIGS. 2 and 3 show that the fluid flow control assembly 18 comprises a flow control cartridge 94 which is placed in the flow control valve channel 18a of the valve body 12 through the flow control valve orifice 24 and is held in place by a spring 96 and a cap 98. A washer 100 and a ring 102 are, respectively, placed between the flow control cartridge 94 and the valve body 12 and between the spring 96 and the cap 98. The washer 100 and ring 102 provide seals between the components of the flow control assembly 18.
The flow control assembly 18 is located in the flow control valve channel 18a of the valve body 12 in such a way that the flow control assembly 18 is easily accessible and the flow control cartridge 94 of the flow control assembly 18 may be easily removed and/or replaced without taking the fluid flow control device 10 off-line. Thus, the fluid flow exiting the flow control device 10 can be altered without taking the device 10 off-line.
In addition, the strainer 76 and the flow control cartridge 94 can be removed thereby enabling the device 10 to be subjected to an excessive flow for the purposes of flushing out the device 10 without clogging the strainer 76 or the cartridge 94. After the device 10 is sufficiently flushed, the strainer 76 can be replaced and the flow control cartridge 94 can be replaced with either the same or a different flow control cartridge 94.
Flow through the assembly 18 is generally tamper resistant due to the fact that the flow control cartridge 94 is generally contained with in the assembly 18 and the cartridge 94 is pre-set and is preferably pressure compensating to allow a certain flow.
The flow control valve orifice 24 includes inner threads 104 and the cap 98 has matching outer threads 106 for attaching the cap 98 to the valve body 12 thereby holding the flow control cartridge 94 in place by holding the spring 96 against it. The cap 98 includes a test port 108 and a first test valve fitting 110 for providing access to fluid in the valve body 12 without disassembling the device 10. The test port 108 includes inner threads 112 and the first test valve fitting 110 includes matching outer threads 114 for attaching the first test valve fitting 110 to the cap 98.
Shown further in FIGS. 2 and 3, the test valve orifice 26 includes inner threads 116 and a second test valve 118 which has matching outer threads 120 for attaching the second test valve 118 to the valve body 12. As mentioned above, the test valve orifice 26 provides a port through which fluid interior to the valve body 12 and beyond the flow control assembly 18 may be tested. The second test valve 118 provides such access without dismantling the entire device 10.
Also shown in FIGS. 2 and 3, the outlet orifice 22 includes an outlet fitting 122 which is held in place by a coupling 124. The outlet orifice 22 has outer threads 126 and the coupling 124 has matching inner threads 128 for attaching the coupling 124 to the valve body 12 thereby holding the outlet fitting 122 in the valve body 12. A washer 130 is situated between the valve body 12 and the outlet fitting 12 and provides a seal. The coupling 124 can be a union or a compression fitting to allow, with the outlet fitting 122, ease of installation of the device 10 and connection to different sized pipes (not threaded), or a threaded outlet fitting could be used.
A plurality of flow control assemblies 18 can be used together in a plumbing system (FIG. 4) comprising an arrangement of pipes and valves, such as supply line 200, line 202 and individual branch lines 204-206 with valves 18 (supplying, for example, radiators in a building). For example, separate assemblies 18 can be used to regulate flow to different rooms or to different floors of a facilities' plumbing system. FIG. 4 shows an example of such a system. As described above, this system has the benefit of enabling easy flushing through excessive flow because the strainers 76 and flow control cartridges 94 can be easily removed from the flow control devices 10.
While an embodiment of the present invention has been shown and described, various modifications may be made without departing from the scope of the present invention, and all such modifications and equivalents are intended to be covered. | 4y
|
BACKGROUND OF THE INVENTION
This Nonprovisional application claims priority under 35 U.S.C. § 119(a) on Patent Application No(s). 092122853 filed in Taiwan on Aug. 20, 2003, the entire contents of which are hereby incorporated by reference.
1. Field of Invention
The invention relates to a manufacturing method of transistors and, in particular, to a manufacturing method of carbon nanotube transistors.
2. Related Art
In the trend of miniaturization, the manufacturing processes of the integrated circuit (IC) based upon silicon wafers are facing bottleneck problems in optics and physics and pressures from research investments. People have started trying various kinds of nanotransistors made from nanomolecules, so that hundreds of times more transistors than the prior art can be put into a same area. A nanometer is one-billionth meter. In the development of all sorts of nanotransistors, the technique that uses carbon nanotubes as the basic building blocks is the fastest. It is expected to be the best material for nano-grade computer products in the next generation.
The carbon nanotube was discovered by Japan NEC researcher in 1991 when he was studying carbon family chemicals. It is a cylindrical carbon material with a diameter between 1 and 30 nanometers. The carbon nanotube is known to be the thinnest tube discovered in Nature. It is thermally conductive, electrically conductive, robust, chemically stable, and soft. It is mainly comprised of one or several layers of unsaturated graphene layer. These little tubes are actually elliptical micro molecules. They are formed under high temperatures in the water vapor generated by carbon arc and laser. The central portion of the carbon nanotube graphene layer completely consists of six-cite rings. Both ends of the turning points have five- or seven-cite rings. Each carbon atom has the SP2 structure. Basically, the structure and chemical properties of the graphene layer on the carbon nanotube are similar to carbon sixty (C60). The carbon nanotubes can be semiconductors or conductors. Because of this special property, the carbon nanotube plays an important role in electronic circuits.
A necessary condition for using carbon nanotubes in future circuits is that they can be used to make transistors. The semiconductor carbon nanotube can be used as the gate in a field effect transistor (FET). Imposing a voltage can increase its conductivity to be 106 times that of the silicon semiconductor. The operating frequency can reach 1012 Hz, which is 1000 times the frequency that can reached by current CMOS. IBM has successfully used individual single wall or multi wall carbon nanotube as the channel of FET's to obtain carbon nanotube transistors for test. The single wall carbon nanotubes (SWNT's) consist of a single shell of carbon atoms. The so-called CNT is a macro carbon molecule with many properties. There are single wall CNT (SWCNT) and multiple wall CNT (MWCNT). There are three kinds of carbon nanotube preparation methods. The first is called the plasma discharging method; the second is called the laser ablation method; and the third is called the metal catalyst thermal chemical vapor deposition method, in which the carbon nanotubes are formed by using iron, cobalt, and nickel metal particles to thermally decompose acetylene or methane in a high-temperature furnace.
Using the reactions in the third type carbon nanotube production method, the disclosed manufacturing method of carbon nanotube FET's does not require the use of highly pollutant alkaline metals. The processes involved are very simple and compatible with existing IC processes.
SUMMARY OF THE INVENTION
An objective of the invention is to provide a manufacturing method of carbon nanotube transistors to solve the foregoing problems and difficulties in the prior art.
Another objective of the invention is to provide a manufacturing method of carbon nanotube transistors to simplify the conventional production processes. With currently available equipment, the production and research costs can be greatly reduced.
We disclose a general embodiment to demonstrate the invention can achieve the above objectives. The detailed steps include: forming an insulating layer on a substrate; forming a first oxide layer on the insulating layer using a solution with cobalt ion catalyst by spin-on-glass (SOG); forming a second oxide layer on the first oxide layer using a solution without the catalyst; forming a blind hole on the second oxide layer using photolithographic and etching processes, the blind hole exposing the first oxide layer, the sidewall of the second oxide layer, and the insulating layer; forming a single wall carbon nanotube (SWNT) connecting the first oxide layer separated by the blind hole and parallel to the substrate; and forming a source and a drain connecting to both ends of the SWNT, respectively.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will become more fully understood from the detailed description given hereinbelow illustration only, and thus are not limitative of the present invention, and wherein:
FIGS. 1A through 1F show cross-sectional views of the production steps in the first embodiment of the invention;
FIGS. 2A through 2F show cross-sectional views of the production steps in the second embodiment of the invention;
FIGS. 3A through 3E show cross-sectional views of the production steps in the third embodiment of the invention; and
FIGS. 4A through 4I show cross-sectional views of the production steps in the fourth embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1A through 1F show the production steps of the carbon nanotube transistors according to a first embodiment of the invention.
As shown in FIG. 1A, an insulating layer 101 is formed on a substrate 100 . The insulating layer 101 can be made of SiO 2 or Si X N Y using the chemical vapor deposition (CVD) method.
With reference to FIG. 1B, a first oxide layer 102 containing a catalyst is formed on the insulating layer 101 . First, a coating solution is prepared. The coating solution is applied on the insulating layer 101 by the SOG method. Finally, the coating solution layer (not shown) on the insulating layer is dried in two steps. The coating solution consists of at least a solution containing TEOS, pure alcohol and catalyst ions. One can also add an ammonia solution (NH 4 OH+alcohol). The catalyst ion can be cobalt, nickel, or iron ion. The two-step drying includes drying at the temperature of 100˜120° C. for one hour and then drying at the temperature of 350˜500° C. for another hour.
As shown in FIG. 1C, a second oxide layer without the catalyst is formed on the first oxide layer 102 . First, a coating solution is prepared and applied on the first oxide layer 102 by the SOG method. Afterwards, the coating solution layer (not shown) is dried. The coating solution consists at least a TEOS solution.
As shown in FIG. 1D, after exposure and developing using a mask, a blind hole 104 is formed by dry or wet etching. The blind hole 104 exposes part of the insulating layer 101 , the sidewall 105 of the first oxide layer 102 , and the sidewall 106 of the second oxide layer 103 .
As shown in FIG. 1E, a carbon nanotube 107 is formed. Both ends of the carbon nanotube 107 are connected to the sidewall 105 of the first oxide layer 102 . The alcohol (C 2 H 5 OH) inside the first oxide layer 102 is the reactant for the carbon nanotube 107 . It reacts with the catalyst inside the first oxide layer 102 under the temperature of 850° C. The reason it does not form the carbon nanotube between the sidewall 106 of the second oxide layer is that there is no reactant and catalyst in the second oxide layer 103 . Thus, the carbon nanotube 107 can be fixed between the sidewall 105 of the first oxide layer 102 .
As shown in FIG. 1F, a source 108 a and a drain 108 b are connected to both ends of the carbon nanotube 107 , respectively. The source 108 a and the drain 108 b can be formed using electron-beam (E-beam) photolithography along with a lift-off means.
Please refer to FIGS. 2A through 2F for the production steps in a second embodiment of the invention.
As shown in FIG. 2A, a first insulating layer 201 is formed on a substrate 200 . The insulating layer 201 can be made of SiO 2 or Si X N Y using the chemical vapor deposition (CVD) method.
With reference to FIG. 2B, a source 208 a and a drain 208 b are formed on the first insulating layer 201 . The detailed steps include using metal sputtering to form a metal layer (not shown) on the first insulating layer 201 and using photolithography and etching to form the source 208 a and the drain 208 b . They are separated by a gap 204 . The metal can be titanium.
As shown in FIG. 2C, a first oxide layer 202 with a catalyst and a second oxide layer 203 with no catalyst are formed on the substrate 200 that has the source 208 a , the drain 208 b , and the first insulating layer 201 . To form the first oxide layer, one first prepares a coating solution and applies the coating solution on the source 208 a and the drain 208 b by the SOG method, filling the gap 204 . Afterwards, the coating solution layer (not shown) covering the source 208 a , the drain 208 b , and the gap 204 is dried. The coating solution for the first oxide layer 202 consists of at least a solution containing TEOS, pure alcohol and catalyst ions. One can also add an ammonia solution (NH 4 OH+alcohol). The catalyst ion can be cobalt, nickel, or iron ion. To form the second oxide layer 203 , one first prepares a coating solution and applies the coating solution on the first oxide layer 202 by the SOG method. Afterwards, the coating solution (not shown) on the first oxide layer is dried. The coating solution here consists of at least a TEOS solution.
As shown in FIG. 2D, after exposure and developing using a mask, a blind hole 209 is formed by dry or wet etching. The blind hole 209 exposes part of the insulating layer 201 , the sidewall 205 of the first oxide layer 202 , the sidewall 206 of the second oxide layer 203 , and the sidewall 210 of the source 208 a and the drain 208 b.
As shown in FIG. 2E, a carbon nanotube 207 is formed. Both ends of the carbon nanotube 207 are connected to the sidewall 205 of the first oxide layer 202 . The alcohol (C 2 H 5 OH) inside the first oxide layer 202 is the reactant for the carbon nanotube 207 . It reacts with the catalyst inside the first oxide layer 202 under the temperature of 850° C. The reason it does not form the carbon nanotube between the sidewall 206 of the second oxide layer is that there is no reactant and catalyst in the second oxide layer 203 . Thus, the carbon nanotube 207 can be fixed between the sidewall 205 of the first oxide layer 202 .
As shown in FIG. 2F, a second insulating layer 211 is formed on the second oxide layer 203 that contains the blind hole 209 . The forming method can be the CVD method. Once the second insulating layer 211 fills the blind hole 209 , it pushes down the carbon nanotube 207 in the blind hole 209 . The carbon nanotube 207 thus has a concave shape and touches the sidewall 210 of the source 208 a , the drain 208 b and part of the first insulating layer 201 . Therefore, the carbon nanotube 207 connects the source 208 a and the drain 208 b . The second insulating layer consists of SiO 2 or Si x N y .
Please refer to FIGS. 3A through 3F for the production steps in a third embodiment of the invention.
As shown in FIG. 3A, a first insulating layer 301 is formed on a substrate 300 . The insulating layer 301 can be made of SiO 2 or Si X N Y using the chemical vapor deposition (CVD) method.
With reference to FIG. 3B, a source 308 a and a drain 308 b are formed on the first insulating layer 301 . The detailed steps include using metal sputtering to form a metal layer (not shown) on the first insulating layer 301 and using photolithography and etching to form the source 308 a and the drain 308 b . They are separated by a gap 304 . The metal can be titanium.
As shown in FIG. 3C, a first oxide layer 302 with a catalyst and a second oxide layer 303 with no catalyst are formed on the substrate 300 that has the source 308 a , the drain 308 b , and the first insulating layer 301 . To form the first oxide layer, one first prepares a coating solution and applies the coating solution on the source 308 a and the drain 308 b by the SOG method, filling the gap 304 . Afterwards, the coating solution layer (not shown) covering the source 308 a , the drain 308 b , and the gap 304 is dried. The coating solution for the first oxide layer 302 consists of at least a solution containing TEOS, pure alcohol and catalyst ions. One can also add an ammonia solution (NH 4 OH+alcohol). The catalyst ion can be cobalt, nickel, or iron ion. To form the second oxide layer 303 , one first prepares a coating solution and applies the coating solution on the first oxide layer 302 by the SOG method. Afterwards, the coating solution (not shown) on the first oxide layer is dried. The coating solution here consists of at least a TEOS solution.
As shown in FIG. 3D, after exposure and developing using a mask, a blind hole 309 is formed by dry or wet etching. The blind hole 309 exposes part of the insulating layer 301 , the sidewall 305 of the first oxide layer 302 , the sidewall 306 of the second oxide layer 303 , and some surface and the sidewall 312 of the source 308 a and the drain 308 b . The sidewall 312 of the source 308 a and the drain 308 b protrudes from the sidewall 305 of the first oxide layer 302 and the sidewall 306 of the second oxide layer 303 .
As shown in FIG. 3E, a carbon nanotube 307 is formed. Both ends of the carbon nanotube 307 are connected to the sidewall 305 of the first oxide layer 302 . The alcohol (C 2 H 5 OH) inside the first oxide layer 302 is the reactant for the carbon nanotube 307 . It reacts with the catalyst inside the first oxide layer 302 under the temperature of 850° C. The reason it does not form the carbon nanotube between the sidewall 306 of the second oxide layer is that there is no reactant and catalyst in the second oxide layer 303 . Thus, the carbon nanotube 307 can be fixed between the sidewall 305 of the first oxide layer 302 . Both end of the carbon nanotube 307 are connected to the surfaces of the source 308 a and the drain 308 b.
Please refer to FIGS. 4A through 4I for the production steps in a fourth embodiment of the invention.
As shown in FIG. 4A, a first insulating layer 401 is formed on a substrate 400 . The insulating layer 401 can be made of SiO 2 or Si X N Y using the chemical vapor deposition (CVD) method.
As shown in FIG. 4B, a first oxide layer 402 with a catalyst is formed on the first insulating layer 401 . First, one prepares a coating solution and applies it on the first insulating layer 401 by the SOG method. Afterwards, the coating solution layer (not shown) on the first insulting layer 401 is dried in two steps. The coating solution consists at least a solution containing TEOS, pure alcohol and catalyst ions. One can further add an ammonia solution (NH 4 OH+alcohol). The catalyst ion can be one of the cobalt, nickel, and iron ions. The two-step drying includes drying under the temperature of 100˜120° C. for one hour and then under the temperature of 350˜500° C. for another hour.
As shown in FIG. 4C, a second oxide layer 403 with no catalyst is formed on the first oxide layer 402 . To form the second oxide layer 403 , one first prepares a coating solution and applies it on the first oxide layer 402 by the SOG method. Afterwards, the coating solution layer (not shown) on the first oxide layer 402 is dried. The coating solution here consists at a TEOS solution.
As shown in FIG. 4D, after exposure and developing using a mask, a blind hole 404 is formed by dry or wet etching. The blind hole 404 exposes part of the insulating layer 401 , the sidewall 405 of the first oxide layer 402 , and the sidewall 406 of the second oxide layer 403 .
As shown in FIG. 4E, a carbon nanotube 407 is formed. Both ends of the carbon nanotube 407 are connected to the sidewall 405 of the first oxide layer 402 . The alcohol (C 2 H 5 OH) inside the first oxide layer 302 is the reactant for the carbon nanotube 307 . It reacts with the catalyst inside the first oxide layer 302 under the temperature of 850° C. The reason it does not form the carbon nanotube between the sidewall 306 of the second oxide layer is that there is no reactant and catalyst in the second oxide layer 403 . Thus, the carbon nanotube 407 can be fixed between the sidewall 405 of the first oxide layer 402 .
As shown in FIG. 4F, a second insulating layer 411 is formed on the second oxide layer 403 that contains the blind hole 404 . The second insulating layer 411 deposited in the blind hole 404 covers the carbon nanotube 407 and pushes it down for the carbon nanotube 407 to touch the first insulating layer 401 .
As shown in FIG. 4G, a photoresist pattern 413 is formed by photolithography to fill the blind hole 404 and to cover part of the second insulating layer 411 at the blind hole 411 . The photoresist pattern 413 does not cover the second insulating layer 411 outside the blind hole.
As shown in FIG. 4H, the area uncovered by the photoresist pattern 413 is removed by wet etching. The removed part includes the first oxide layer 402 and the second oxide layer 403 that are not covered by the photoresist pattern 413 . After the photoresist pattern 413 is removed, one is left with the carbon nanotube 407 on the first insulating layer and the protruding part 412 covering the carbon nanotube 407 and above the second insulating layer 411 . The protruding part 412 of the second insulating layer exposes both ends 407 a , 407 b of the carbon nanotube 407 .
As shown in FIG. 4I, a source 408 a and a drain 408 b are connected to the two ends 407 a , 407 b of the carbon nanotube 407 . The forming steps include first depositing a metal layer (not shown) on the first insulating layer 401 that contains the second insulating layer 414 , and then using photolithography and etching processes to form the source 408 a and the drain 408 b from the metal layer.
Certain variations would be apparent to those skilled in the art, which variations are considered within the spirit and scope of the claimed invention. | 4y
|
FIELD OF THE INVENTION
This invention relates generally to melt distribution arrangements for injection moulding apparatus. More particularly, this invention relates to cross over nozzle arrangements for multi-level stack moulds.
BACKGROUND OF THE INVENTION
In injection moulding apparatus utilizing a stack mould design, a melt transfer system is required which transfers melt across mould levels yet which is separable to enable mould separation. The separable component of the melt transfer system is referred to as a “cross over nozzle”.
In order to be effective, a cross over nozzle is provided with some means for blocking melt flow upon separation. Prior art systems include a valve gate design such as described in U.S. Pat. No. 4,212,626, a hot probe design such as described in U.S. Pat. No. 4,891,001 and a valveless melt transfer system such as described in U.S. Pat. No. 5,458,843. Each such system has particular benefits for certain types of application. Each however typically drools or leaks in one way or another.
The valve gate design utilizes a pair of nozzles which are pressed up one against the other when the mould is closed with respective nozzle orifices in registry. Each nozzle orifice has a pin which can be advanced to block its respective orifice or retracted to unblock the orifice and permit melt flow. A disadvantage with this arrangement is that a positive driving force is required for the pin, which can be mechanical, pneumatic or hydraulic. The driving mechanisms typically require a considerable amount of space and accordingly such an arrangement may not be useable in some applications due to space constraints. There is also typically some stringing at the gate with such an arrangement. As the two pins open and close in a hot resin environment, hot resin may be trapped between the two pins causing a string to form when the mould is opened.
The hot probe design basically utilizes a heated nozzle tip to selectively allow the resin to solidify and block the nozzle or melt to free the nozzle. As it lacks a valve pin it has a tendency to drool heavily yet has the advantage of being compact and accordingly suited to an arrangement where space is limited.
The valveless melt transfer design includes an expansive chamber which captures melt during mould opening. This is an effective system which requires minimal shut height yet still causes some angel hair stringing.
It is an object of the present invention to provide a cross over nozzle arrangement with virtually no drool which can operate in a small volume similar to that of a valveless melt transfer system to enable its use on three and four-level stack mould systems.
SUMMARY OF THE INVENTION
According to the present invention, a cross over nozzle is provided of two parts which, when joined, define a housing having a passage extending therethrough, a tapered valve seat extending about the passage and a valve member having a tapered valve head disposed in the passage for engaging the valve seat. The two parts are axially separable at an interface extending through the valve seat/valve head. In order to open the valve, both valve parts are first joined and then moved together as one member in the same direction relative to the housing axially away from the valve seat. Similarly, the valve members are jointly moved into engagement with the valve seat before the cross over nozzle is separated. Accordingly, unlike the valve gate design, the valve interface between the two parts of the valve head isn't exposed to molten resin and therefore molten resin isn't trapped therebetween to cause a string upon opening.
More particularly, a cross over nozzle is provided which has a nozzle housing with the melt passage extending therethrough, a valve axis extending along the passage and a tapered valve seat in the passage extending about the valve axis. The nozzle housing has a first housing part and a second housing part separable along the valve axis through the valve seat at a housing interface. A first valve seat part is carried by the first housing part and a second valve seat part is carried by the second housing part. A valve member having a tapered valve head is disposed in the passage and axially movable relative to the nozzle housing between a closed configuration wherein the valve head engages the valve seat to block melt flow along the passage and an open configuration wherein the valve head is displaced from the valve seat to allow melt flow along the passage about the valve head. The valve head has a first valve head part and a second valve head part which meet at a valve interface corresponding to the nozzle interface and at which the valve member is separable along the axis into first and second valve parts for respectively sealing the first and second nozzle parts in the closed configuration. A valve opening actuator acting between the valve member and the nozzle housing is provided for causing simultaneous movement of the first and second valve parts relative to the nozzle housing toward the open configuration when said first and second nozzle housing parts and first and second valve parts are joined. A first valve closing actuator is provided which acts between the first valve part and the first housing part to bias the first valve part toward its closed configuration. A second valve closing actuator is provided which acts between the second valve part and the second housing part to bias the second valve part towards its closed configuration.
According to one embodiment, the valve opening actuator may be a fluid pressure responsive first piston in a bore associated with a first housing part. A first valve stem may extend between and operably connect the first piston and the first valve head part. The first piston may also act as the first valve closing actuator. A fluid pressure responsive second piston and a second bore associated with a second housing part may act as the second valve closing actuator. A second valve stem may extend between and operably connect the second piston and the second valve head part.
According to an alternate embodiment, the first housing part may have a base part and an outer part which are telescopically connected for relative axial movement along the nozzle axis. A biasing means may act between the base part and the outer part to urge the outer part away from the base part. The first valve seat part may be carried by the outer part. A first valve stem may extend between and rigidly secure the first valve head part and the base part. The first valve head part may engage the seat to limit movement of the outer part away from the inner part. The valve opening actuator may cause movement of the second housing part toward the first housing part and act against the biasing means to urge the outer part of the first housing part toward the base part in turn causing relative movement of the valve head and valve seat to move the valve member into the open configuration. The biasing means between the base part and the outer part of the first housing part may also act as the first valve closing actuator. A second valve stem may extend between and operably connect the second valve head part with the second closing actuator.
The biasing means in the alternate embodiment described in the preceding paragraph may be at least one of a resilient biasing means and fluid pressure. The second valve closing actuator may be at least one of a resilient biasing means and a fluid pressure responsive piston in a bore associated with the second housing part.
The first valve stem may be provided with a hollow interior which defines a portion of the melt passage and the first valve stem may sealingly engage the first housing part.
At least a portion of the second valve stem may also sealingly engage the second housing part and the melt passage may extend along an interior of the second valve stem. Accordingly in the open configuration melt may flow along the interior of the first and second valve stems and about the valve member between the valve member and the valve seat.
The melt passage may extend axially along the interior of the first and second valve stems and diverge toward the first and second valve head parts to exit the valve stem through at least one opening adjacent each of the first and second valve head parts.
The biasing means may act against a face of the mould and the outer part of the first valve head part and first valve stem may be removable from the face without mould disassembly. Furthermore the second housing part may have an inner section and an outer section with the second valve seat part being carried by the outer section. The outer section and the inner section may be separably axially joined to provide for removal of the outer section, the second valve head part and the second valve stem without mould disassembly.
DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the present invention are described below with reference to the accompanying drawings in which:
FIG. 1 is an axial sectional view of a cross over nozzle according to the present invention in its closed and joined configuration;
FIG. 2 is an axial sectional view corresponding to FIG. 1 but showing the cross over nozzle in its open configuration;
FIG. 3 is an axial sectional view of the cross over nozzle of FIG. 1 in a closed and separated configuration;
FIG. 4 is an axial sectional view of an alternate embodiment of a cross over nozzle according to the present invention in a closed and joined configuration;
FIG. 5 is an axial sectional view of the cross over nozzle of FIG. 4 in a joined and open configuration;
FIG. 6 is an axial sectional view of the cross over nozzle of FIG. 4 in a closed and separated configuration;
FIG. 7 is a partially cut-away perspective view of another embodiment of a cross over nozzle according to the present invention in a joined and open configuration;
FIG. 8 is a view corresponding to FIG. 7 but illustrating the cross over nozzle in a closed and separated configuration; and
FIG. 9 is an axial sectional view illustrating an alternative mounting arrangement for the FIGS. 7 and 8 embodiment.
DESCRIPTION OF PREFERRED EMBODIMENTS
A first embodiment of a valved cross over nozzle according to the present invention is generally indicated by reference 10 in FIGS. 1 through 3 .
A melt passage 30 extends through the nozzle housing 20 . A valve axis 40 extends along the melt passage 30 and a tapered valve seat 50 extends about the valve axis 40 .
The cross over nozzle 10 has a nozzle housing 20 with a first housing part 22 (to the left as illustrated) and a second housing part 24 (to the right as illustrated).
The first housing part 22 and the second housing part are separable along the valve axis 40 through the valve seat 50 at a housing interface 26 . FIG. 3 illustrates the nozzle housing 20 in a separated configuration. A first valve seat part 52 is carried by the first housing part 22 and a second valve seat part 54 is carried by the second housing part 24 .
A valve member 60 having a tapered valve head 62 is disposed in the passage 30 and is axially movable relative to the nozzle housing 20 between a closed configuration as illustrated in FIG. 1 and an open configuration as illustrated in FIG. 2 . In the closed configuration the valve head 62 engages the valve seat 50 to block melt flow along the passage 30 . In the open configuration the valve head 62 is displaced from the valve seat 50 to allow melt flow along the passage 30 about the valve head 62 .
The valve head 62 has a first valve head part 64 and a second valve head part 66 . The first valve head part 64 and second valve head part 66 meet at a valve interface 68 which corresponds to and is aligned with the nozzle interface 26 . The valve member 60 is separable at the valve interface 68 along the valve axis 40 into first and second valve parts 70 and 72 respectively. The first valve part 70 and its associated first valve head part 64 act to seal the first nozzle part 22 . The second valve part 72 and its associated second valve head part 66 act to seal the second nozzle part 24 .
A valve opening actuator in the form of a fluid pressure responsive first piston 80 in a bore 82 is operably connected to the first valve head part 64 by a valve stem 74 in the FIGS. 1 through 3 embodiment. Alternate valve opening actuator assemblies may be utilized as for example discussed below with respect to the FIGS. 4 through 6 embodiment.
The first piston 80 is axially slidable in its bore 82 in response to fluid pressure applied through either of two fluid ports 84 and 86 respectively. The introduction of fluid (air or hydraulic fluid typically) will cause the first piston 80 to move to the right as illustrated and in turn move the valve stem 74 and first valve head part 64 to the right. The first valve head part in turn presses against the second valve head part 66 and as a result the whole valve head 60 is unseated from the valve seat 50 to move the valve member 40 into its open configuration as illustrated in FIG. 2 . As the first valve head part 64 and second valve head part 66 are in contact during the valve member 60 being in its open configuration, molten resin isn't provided with an opportunity to flow between the two parts 64 and 66 respectively.
Once an injection cycle is complete and it is necessary to separate the mould, the valve member 60 is advanced to the left as illustrated into the closed configuration of FIG. 1 . This may be achieved by initially using a second valve closing actuator in the form of a fluid pressure responsive second piston 90 slidably mounted in a second bore 92 associated with the second nozzle part 24 . The second piston 90 is operably connected to the second valve head part 66 by a second valve stem 76 . In lieu of a fluid pressure responsive piston, a resilient biasing means such as a stack of Belleville™ washers may be used as the second valve closing actuator. Other actuator arrangements may occur to persons skilled in such structures.
Once the valve member 60 has been moved to the closed configuration a first closing actuator is used to maintain the first valve head part 64 against the first valve seat part 62 . The first closing actuator may also be the piston 80 , but with fluid pressure applied through the port 86 rather than the port 84 to urge the piston 80 and in turn the first valve stem 74 and first valve head part 64 to the left as illustrated. At this point the nozzle housing 20 and the valve member 60 can be parted at the nozzle interface 26 and the valve interface 68 as illustrated in FIG. 3 . As no molten resin has been trapped between the first valve head part 64 and the second valve head part 66 , the separation will be clean as compared to that of a valve gate design.
In order to align the first valve head part 64 with the second valve head part 66 when the nozzle housing 20 is joined, cooperating locating means may be provided. Suitable locating means may for example be a projection 94 on the first valve head part 64 which is received by and nests in a corresponding recess 96 on the second valve head part 96 . Obviously other arrangements are possible such as using a plurality of projections 94 and recesses 96 and reversing the projection 94 and recess 96 as between the first valve head part 64 and the second valve head part 66 .
To reduce shock on opening and closing, the second housing part 24 may be made up of an inner part 27 and a cover 28 which are telescopically connected albeit for a relatively small amount of movement relative to each other along the valve axis 40 . A cushioning means 29 such as the stack of Belleville™ washers illustrated acts to bias the cover 28 to the left as illustrated away from the inner part 27 . Accordingly the initial shock of joining of the first housing part 22 and second housing part 26 is absorbed by the cover 28 yielding slightly to the right as illustrated against the force of the cushioning means 29 . Obviously the amount of telescopic movement between the inner part 27 and cover 28 mustn't exceed the stroke of the second closing actuator to avoid having the cushioning means 29 unseat the second valve head part 66 from the second valve head part 54 .
An alternate embodiment of a valved cross over nozzle according to the present invention is illustrated and generally indicated by reference 100 in FIGS. 4 through 6 . The differences between the FIGS. 4 through 6 embodiment and the FIGS. 1 through 3 embodiment reside in the first housing part and accordingly common reference numerals for the second housing part 24 , its components and the associated second valve part 60 and its components are used throughout and the foregoing description applies. The basic operational principles are common to both embodiments, namely a two part cross over nozzle is provided with a tapered valve head which engages a tapered valve seat in a nozzle passage, the nozzle is separable through the valve head and seat into two independently sealable valve head and seat parts and the valve head parts are joined and moved in unison between an open and a closed configuration.
In the FIGS. 4 through 6 embodiment a first housing part 122 includes a base part 123 and an outer part 125 which are telescopically connected for relative movement along (i.e. parallel to) the valve axis 40 . A biasing means such as either the stack of Belleville™ washers 127 or pressurized fluid introduced through a fluid port 129 act between the base part 123 and the outer part 125 to urge the outer part 125 away from the base part 123 (i.e. to the right as illustrated).
A first valve stem 170 extends between and rigidly secures a first valve head part 164 to the base part 123 . The first valve head part 164 in turn engages a first valve seat part 152 to limit movement of the outer part 125 away from the inner part 123 . Other stop means could be provided but using the first valve head part 164 in combination with the first valve stem 170 ensures sealing engagement between the first valve head part 164 and the first valve seat part 152 at the limit of travel of the outer part 125 away from the base part 123 .
In the FIGS. 4 through 6 embodiment, the valve opening actuator is in effect the mould closing structure (which is not illustrated) that moves the mould levels and in turn the two halves of the cross over nozzle toward one another. As can be seen by comparing FIGS. 4 and 5 , as the second housing part 23 presses up against the first housing part 122 , the outer part 125 , which carries the first valve seat part 152 is moved (to the left as illustrated) axially toward the base part 123 . As the first valve head part 164 remains in its position by virtue of its rigid securement to the base part 123 through the first valve stem 170 , the first valve seat part 152 moves away from the first valve head part 164 to move the valve member toward its open configuration. As the first valve head part 164 and the second valve head part 66 are joined at a valve interface 168 before and during valve opening and closing, and moved simultaneously in the same direction, no molten resin is trapped therebetween.
During mould separation the first housing part 122 and second housing part are moved away from each other the biasing means acting between the base part 123 and outer part 125 acts as a first valve closing actuator by causing relative movement of the first valve seat part 152 and first valve head part 164 back into engagement. The second valve closing actuator (i.e. the piston 90 in the bore 92 ) are simultaneously employed to maintain joinder of the first valve head part 164 and the second valve head part 66 .
As the first valve head part 164 and the second valve head part are sealed respectively against the first valve seat part 152 and second valve seat part 54 before separation to block the flow of molten resin, a clean separation can be effected.
An advantage of the FIGS. 4 through 6 embodiment is that it can be set up using resilient biasing means in lieu of fluid pressure responsive biasing means for all of the opening and closing actuation to achieve a totally automatic self energized closing and opening sequence without the need for a pneumatic or hydraulic hook-up or synchronization of a pneumatic or hydraulic actuator with mould opening and closing sequences.
In FIGS. 7 and 8 , another embodiment of a cross over nozzle according to the present invention is generally indicated by reference 200 . The cross over nozzle 200 is similar to the cross over nozzle 100 in FIGS. 4 through 6 in that it is actuatable by machine movement without requiring a separate hydraulic actuating system. It differs principally in melt directing and placement. Similar reference numerals are applied to analogous components.
According to the FIGS. 7 and 8 embodiment, the first valve stem 170 is a hollow member which sealingly engages the outer part 125 of the first housing part 122 . Rather than having the melt passage 30 defined between the first valve stem 170 and the first housing part 122 , the melt passage 30 extends axially along the hollow interior of the first valve stem 170 . Melt exits the first valve stem 170 through one or more openings 210 adjacent the first valve head part 164 . Valve head operation is much the same as for the other embodiments in that the valve head has a first valve head part 164 and a second valve head part 66 each of which interfaces respectively with the first valve seat part 152 and the second valve seat part 54 separable along the housing interface 26 .
The second valve stem 76 may be configured in a similar manner with a second valve stem 76 being hollow and sealingly engaging the second housing part 24 . The melt passage 30 extends axially along the hollow interior of the second valve stem 76 . Melt enters the interior through one or more openings 212 located adjacent the second valve head part 66 .
There are two significant advantages to the FIGS. 7 and 8 embodiment. A first is that it is “front mounted” in that the assembly can be removed from the face of a mould rather than requiring mould disassembly. This is achieved in the first part by securing screws 225 which extend through the biasing means which in this case are coil springs 227 for securement to a mould face (not shown). This is achieved in the second housing part 24 by forming the second housing part in two sections namely an outer section 226 and an inner section 228 which are threadedly or otherwise axially connected at 230 and providing a bore 232 in the outer section 228 large enough to enable passage over the second valve head part 66 .
Alternatively the entire unit including the outer section 226 and the base part 123 may be removable from a mould face 250 as illustrated in FIG. 9 . This is achieved by providing a clamping ring 252 which engages an outer end 254 of the outer section 226 . The clamping ring 252 is threadedly secured to the mould face 250 by screws 256 . Preferably the screws 256 and clamping ring 250 will be configured to melt flush with the balance of the mould face 250 .
The cross over nozzle 200 is provided with a coil spring 290 as the second valve closing actuator. The coil spring 290 acts between the second housing part 24 and the second valve stem 76 . The second valve stem 76 sealingly engages the second housing part 24 beyond both ends of the coil spring 290 . Other actuating means may be utilized such as a stack of Belleville™ washers. Flats 240 may be provided on the outer part 228 to facilitate gripping with a wrench.
The above description is intended in an illustrative rather than a restrictive sense. Variations to the specific structure described may be apparent to persons skilled in the art without departing from the spirit and scope of the present invention which is defined by the claims set out below. | 4y
|
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit under 35 USC 119(e) of U.S. Application No. 61/091,913 filed Aug. 26, 2008, the entirety of which is incorporated by reference herein.
BACKGROUND
Field
The present invention relates to a device for the torque limitation in a machine for processing means of payment.
In the following means of payment shall mean bank notes, checks, vouchers, coupons and coins. Processing means of payment shall mean the automatic processing of means of payment for example with bank note processing machines, coin processing machines etc, which are operated by operators in order to, in particular, check, count and account the means of payment.
With the automatic processing of means of payment, for example, certain quantities of means of payment are handed in by depositors to an authority effecting the automatic processing, e.g. a bank, in order to be accounted, so that the total value of the means of payment can be credited e.g. to a bank account of the depositor.
Here it can occur that the operator or the depositor comes in contact with moving parts of the machine effecting the automatic processing, the result of which can be a risk of injury for the operator.
Likewise, a damage of the machine effecting the automatic processing of the means of payment can occur. It can occur, for example, that foreign objects are between the bank notes inputted by the operator, which are thicker and harder than the bank notes and during the processing, e.g. singling of the bank notes, would lead to a damage of the machine effecting the automatic processing of the means of payment.
Further damage of the machine effecting the automatic processing of the means of payment can occur, when components of the machine inserted by the operator into the machine, e.g. cassettes for receiving means of payment, are not properly inserted into the machine.
All the cases described by way of example have in common, that too high torques can cause injuries of the operator or damage of the machine effecting the automatic processing of the means of payment, in particular of a drive of the machine.
SUMMARY
Therefore, it is the object of the present invention to provide a device for the torque limitation in a machine for processing means of payment, which has an especially simple structure and permits a reliable limitation of torques.
This object is achieved according to the invention by the features of the independent claim.
The invention starts out from a device for the torque limitation in a machine for processing means of payment, the device for the torque limitation having two elements transmitting a torque, the two elements having magnets which are disposed in the two elements with an angular distribution of the same kind, the magnets connecting the two elements to each other in a non-positive fashion, and the connection of the two elements being disrupted, when a maximum of transmittable torque is exceeded.
The advantage of the invention in particular is that with the help of the two elements a safety coupling especially simple to realize can be realized, which has an exactly defined maximum transmittable torque. Moreover, the device works wear-free with magnetic forces.
In an advantageous development it is provided, that the two elements of the device have depressions and elevations, which are disposed on the adjacent surfaces of the two elements with an angular distribution of the same kind, in particular with cylindrical depressions and spherical elevations.
The advantageous development has the advantage, that the maximum torque transmittable by the device can be easily increased, without there having to be made especially high demands on the magnetic forces of the magnets used in the elements.
DESCRIPTION OF THE DRAWINGS
Further advantages of the present invention appear from the dependent claims as well as the following description of an embodiment with reference to Figures.
FIG. 1 shows an embodiment of a device for the torque limitation in a machine for processing means of payment on transmitting a torque, and
FIGS. 2 and 3 show substantial component parts of the device shown in FIG. 1 .
FIG. 4 shows a schematic view of a machine for processing payment means.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
In FIG. 1 is shown an embodiment of a device for the torque limitation in a machine for processing means of payment on transmitting a torque. In the shown embodiment a torque of a drive or a motor 16 is transmitted with the help of a shaft 10 , 20 consisting of two parts to a toothed wheel 21 which e.g. with the help of a toothed belt drives parts of the machine for processing means of payment. For example, as shown in FIG. 4 , the device for torque limitation may used in a machine 100 for processing means of payment in combination with a singler 101 or a mechanism 201 disposed in a cassette 200 for receiving means of payment, e.g. for receiving bank notes BN in a singler 101 , and transporting the bank notes on path 202 and stacking the bank notes BN in the cassette 200 . Between the two shaft parts 10 , 20 there are disposed two elements 12 , 22 for limiting the transmitted torque, which form a safety coupling. The two elements 12 , 22 can be formed in a disk-shaped fashion. Each of the two elements 12 , 22 is firmly connected with one end of the two shaft parts 10 , 20 . For monitoring a rotational speed that has to be observed when operating the shaft 10 , 20 , a clocking disk 11 can be provided, which is firmly connected with the shaft. With the help of a not shown forked light barrier, which is disposed in the rotating area of the clocking disk 11 the rotational speed of the shaft can be determined by evaluating the output signal of the forked light barrier.
FIGS. 2 and 3 show the shaft 10 , 20 consisting of two parts in a separated state. Here the surfaces of the element 12 , 22 forming the safety coupling, that adjoin each other when transmitting a torque, become visible. The first element 12 mounted at the first shaft part 10 has magnets 13 . Additionally, the first element 12 can have depressions 14 , which can be formed e.g. cylindrical. Moreover, the first shaft part 10 can have a tapered extension 15 , which protrudes beyond the surface of the first element 12 . The second element 22 mounted at the second shaft part 20 has magnets 23 . Additionally, the second element 22 can have elevations 24 , which can be formed e.g. as spheres. Moreover, the second shaft part 20 can have a bush-shaped bore 25 .
When first and second shaft part 10 , 20 , as shown in FIG. 1 , are brought together, the extension 15 of the first shaft part 10 moves into engagement with the bush 25 of the second shaft part 20 . The magnets 13 of the first element 12 and the magnets 23 of the second element 22 attract each other and connect the first element 12 and the second element 22 with each other in a non-positive fashion, so that their surfaces adjoin each other. It is obvious, that the pole direction of the magnets 13 and 23 must be chosen such that the magnets 13 of the first element 12 and the magnets 23 of the second element 22 attract each other. For example, the magnets 13 of the first element 12 are inserted such that they have a north pole at the surface of the first element 12 , whereas the magnets 23 of the second element 22 are inserted such that they have a south pole at the surface of the second element 22 . In the shown example with four magnets per element, then first and second element are connected with each other after a quarter turn at the latest. But it is also possible, that in both elements for example a north pole follows a south pole. In the shown example with four magnets per element, then first and second element are connected with each other after a half turn at the latest.
By choosing number, type and size of the magnets 13 , 23 and the size, i.e. the diameter, of the elements 12 , 22 of the device for the torque limitation, or the distance between the magnets 13 , 23 and the axial center of the shaft 10 , 20 , there can be determined the maximum transmittable torque. If, for example, a diameter of 20 millimeters is chosen for the elements 12 , 22 and if four permanent magnets of the REFeB type with a degree of magnetization N52 and 5 millimeters diameter at a length of 6 millimeters are chosen and disposed concentric to the axis of the shaft 10 , 20 , a maximum torque of 0.18 Nm can be transmitted.
When bringing together the first and second element 12 , 22 , moreover, the possibly additionally provided elevations 24 of the second element 22 , which e.g. are formed as spheres, move into engagement with the possibly additionally provided, for example, cylindrical depressions 14 of the first element 12 . In this way first and second element 12 , 22 can be positively connected, when viewed in the direction of rotation. With that the torque transmittable by the device for the torque limitation can be increased. The effect of the elevations 24 and depressions 14 , which increases the maximum transmittable torque, substantially depends on their dimensions, in particular on the height and depth of the elevations 24 and depressions 14 , respectively, and their form. Instead of providing the elevations and depressions each on one of the elements, elevations and depressions can be alternately provided on the two elements.
When the torque transmitted by the shaft 10 , 20 exceeds the maximum permissible value, e.g. because the singler for bank notes is blocked by foreign objects, the retention forces of the magnets 13 , 23 are exceeded and the device for the torque limitation effects a disruption of the shaft 10 , 20 between first and second element 12 , 22 . When, optionally, the above-described depressions 14 and elevations 24 are provided, the transmittable torque is increased respectively, so that for achieving the desired torque lower magnetic forces are sufficient.
When the cause, that effects the exceeding of the maximum torque, is eliminated, first and second shaft part 10 , 20 are re-connected with each other with the help of first and second element 12 , 22 as described above, so that a torque can be transmitted until the maximum permissible torque. Here the elements 12 , 22 and thus the shaft parts 10 , 20 are put together again and held together by the magnetic forces of the magnets 13 , 23 used.
In particular when the described depressions 14 and elevations 24 in the surfaces of the elements 12 , 22 are used, it can be provided, that one of the elements 12 , 22 is mounted movable in axial direction on the respective shaft part 10 , 20 . This permits that in the case the maximum transmittable torque is exceeded the movably mounted element 12 , 22 can evade. The permissible axial movability here can approximately correspond to the height of the elevations 24 .
In the described embodiment first and second element 12 , 22 of the device for the torque limitation each have four magnets 13 , 23 . It is obvious, that more or less than four magnets per element 12 , 22 can be used. Here it is required, that the magnets 13 of the first element 12 and the magnets 23 of the second element 22 have an angular distribution of the same kind. The same applies for the optionally provided four elevations 24 or depressions 14 per element 22 or 12 .
As shown, elements 12 , 22 are formed in a disk-shaped fashion, but it is obvious, that the elements 12 , 22 can also have a different form, in order to in particular accommodate the magnets 13 , 23 .
From the Figures and the description of the action principle of the device for the torque limitation it obviously appears, that the device for the torque limitation is suitable to effect a torque limitation in both directions of rotation.
Likewise, from the Figures and their description results that the two shaft parts 10 , 20 are separable. For example, the second shaft part 20 can be component part of a cassette, the first shaft part 10 can be disposed in the machine for processing means of payment. Thus the cassette and with that the second shaft part 20 can be easily flanged to the machine for processing means of payment and thus to the first shaft part 10 , to permit the driving of the elements located in the cassette. | 4y
|
BACKGROUND OF THE INVENTION
The invention relates generally to hydraulic systems utilizing charge pumps and more particularly to an improved hydraulic system having a jet pump to augment the charge pump.
In the past, in hydraulic systems having a main pump and a charge pump, the charge pump was always sized so as to be large enough to supply the demands of the main pump under all conditions. Even with proper sizing of the charge and main pumps for all normal conditions, it has been found that at new elevated operating temperatures and low charge pump speeds that a properly sized charge pump is inadequate to keep up with the leakage through the system and a costly, larger charge pump is required to provide adequate fluid to the main pump to prevent destructive cavitation therein.
SUMMARY OF THE INVENTION
The present invention provides a charge pump augmenting device which eliminates the necessity of having a larger charge pump than necessary to meet the normal requirements of the main pump.
In accordance with the present invention there is provided, a venturi-containing jet pump powered by fluid flow from the main pump adding fluid to the inlet of the main pump. The fluid flow is controlled by a control valve connected to the outlet of the jet pump to maintain a predetermined pressure thereat and a reservoir connected check valve allows fluid from the reservoir to be drawn into the jet pump.
The above and additional advantages of the present invention will become apparent to those skilled in the art from a consideration of the following detailed description of the preferred embodiment when taken in conjunction with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
The drawing shows schematically and partially in section the hydraulic system incorporating the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawing, therein is shown a reservoir 10 having immersed therein a charge pump 12 having an inlet line 14 and an outlet charge line 16.
The outlet charge line 16 is connected to a transmission line 18 for a vehicle transmission (not shown) and a clutch line 20 for a clutch control and lubricating system (not shown). The outlet charge line 16 is further connected to a conventional pressure control valve 22 which normally blocks the flow of fluid therethrough from the outlet charge line 16 to a main pump inlet line 24. The main pump inlet line 24 is connected by a conventional overload relief valve 26 which normally blocks the flow of fluid therethrough, to a reservoir connected reservoir line 28.
The main pump inlet line 24 is further connected to the inlet of a main pump 30. The main pump 30 has an outlet connected to a motor supply line 32 for various fluid motors (not shown). The exhaust of fluid from the fluid motor is through a motor return line 34 which is connected to a filter 36 and thence to a motor return line 38 which has therein a restrictor 40 and thence to the reservoir line 28.
To augment the fluid in the outlet charge line 16, there is provided an augmenting line 42 connected thereto at one end and connected at the other end to a jet pump generally designated by the numeral 44. The jet pump 44 consists of a venturi 46 which is made up of a venturi nozzle 48, a venturi throat 50, and a venturi chamber 52. The venturi nozzle 48 is connected by a pilot line 54 to a control valve 56. The control valve 56 has provided therein a bore 58 which connects to the pilot line 54 at one end and to a relief line 60 at the other end. A jet pump inlet line 62 intersects the bore 58 between the pilot line 54 and the relief line 60. A piston 64 is positioned in the bore having a head portion 66 proximate the pilot line 54. The head portion 66 is connected by a throat portion 68 to a tail portion 70 of the piston 64. The tail portion 70 abuts a spring 72 and compresses it against the relief line 60 connected end of the bore 58.
The jet pump inlet line 62 is connected to the motor supply line 32 at one end and terminates in a nozzle 74 at the other end. The nozzle 74 is positioned in the venturi throat 50.
A check valve 76 is immersed in the reservoir 10 and includes a ball 78 and a spring 80. The check valve 76 is connected to the venturi chamber 52 and prevents the flow of fluid from the venturi chamber 52 into the reservoir 10.
In normal operation, the charge pump 12 draws fluid from the reservoir 10 and supplies the outlet charge line 16 with fluid pressurized to an intermediate level. A portion of the charge pump 12 output is used for the transmission and clutch while the remainder opens the pressure control valve 22 so as to permit the flow at the intermediate pressure level to the main pump 30 and thence at a high pressure to the fluid motors.
The pressurization of the outlet charge line 16 causes pressurization of the venturi nozzle 48. The pressure acting on the control valve 56 which is connected to the venturi nozzle 48 will cause the piston 64 to act against and compress the spring 72. With compression of the spring 72, the piston throat portion 68 will be moved out of the position permitting flow from the main pump 30 to the nozzle 74. With the piston head portion 66 blocking the jet pump inlet line 62, there will be no flow out of the nozzle 74 and thus the pressure in the venturi throat 50 and the venturi chamber 52 will be at the intermediate pressure level preventing the opening of the check valve 76.
During operation, and as the temperature increases while the charge pump 12 speed decreases, the pressure in the outlet charge line 16 will decrease due to increased leakage. As the pressure in the outlet charge line 16 decreases, the pressure in the venturi nozzle 48 decreases to a predetermined level allowing the control valve 56 to permit the flow of fluid from the main pump 30 to the nozzle 74. The flow out of the nozzle 74 and into the venturi throat 50 will cause the well-known venturi effect which will reduce the pressure in the venturi chamber 52. A reduction of the pressure in the venturi chamber 52 below the holding force of the spring 80 will cause the check valve 78 to open and allow fluid to be drawn from the reservoir 12 into the venturi chamber 52. The fresh fluid is added to the fluid from the main pump in the venturi throat 50 and is supplied through the augmenting line 42 to the outlet charge line 16. When the pressure in the venturi nozzle 48 again reaches the predetermined level, the control valve 56 will be moved to block the jet pump inlet line 62 and stop the drawing of fluid through the check valve 76. Therefore, there is provided a charge pump augmenting device for automatically augmenting the flow of fluid in the charge line 16 when the charge pump 12 is of inadequate capacity at low speeds and high temperatures to supply the main pump 30.
While the invention has been described in conjunction with a specific embodiment, it is to be understood that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations which fall within the spirit and scope of the appended claims. | 4y
|
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of, and claims a benefit of priority under 35 U.S.C. 120 of the filing date of U.S. patent application Ser. No. 11/524,831 entitled “SYSTEM AND METHOD FOR CLASSIFYING OBJECTS” filed on Sep. 21, 2006, which in turn claims the benefit of priority under 35 U.S.C. §119 to U.S. Provisional Patent Application No. 60/719,058, filed Sep. 21, 2005, entitled “SYSTEM AND METHOD FOR CLASSIFYING OBJECTS,” the entire contents of which are incorporated herein by reference for all purposes.
FIELD OF THE INVENTION
[0002] The present invention relates generally to managing and controlling data storage resources. More specifically, the present invention relates to systems, methods and apparatuses for filtering and classifying objects in file systems or file based data storage media utilizing metadata and/or content of the files and other objects stored in the file systems or file-based data storage media.
BACKGROUND OF THE INVENTION
[0003] Today's computers require memory to hold or store both the steps or instructions of programs and the data that those programs take as input or produce as output. This memory is conventionally divided into two types, primary storage and secondary storage. Primary storage is that which is immediately accessible by the computer or microprocessor, and is typically though not exclusively used as temporary storage. It is, in effect, the short term memory of the computer.
[0004] Similarly, secondary storage can be seen as the long-term computer memory. This form of memory maintains information that must be kept for a long time, and may be orders of magnitude larger and slower. Secondary memory is typically provided by devices such as magnetic disk drives, optical drives, and so forth. These devices present to the computer's operating system a low-level interface in which individual storage subunits may be individually addressed. These subunits are often generalized by the computer's operating system into “blocks,” and such devices are often referred to as “block storage devices.”
[0005] Block storage devices are not typically accessed directly by users or (most) programs. Rather, programs or other components of the operating system organize block storage in an abstract fashion and make this higher-level interface available to other software components. The most common higher-level abstraction thus provided is a “filesystem.” In a filesystem, the storage resource is organized into directories, files, and other objects. Associated with each file, directory, or other object is typically a name, some explicit/static metadata such as its owner, size, and so on, its contents or data, and an arbitrary and open set of implicit or “dynamic” metadata such as the file's content type, checksum, and so on. Directories are containers that provide a mapping from directory-unique names to other directories and files. Files are containers for arbitrary data. Because directories may contain other directories, the filesystem client (human user, software application, etc.) perceives the storage to be organized into a quasi-hierarchical structure or “tree” of directories and files. This structure may be navigated by providing the unique names necessary to identify a directory inside another directory at each traversed level of the structure; hence, the organizational structure of names is sometimes said to constitute a “filesystem namespace.”
[0006] Filesystems support a finite set of operations (such as create, open, read, write, close, delete, etc.) on each of the abstract objects which the filesystem contains. For each of these operations, the filesystem takes a particular action in accordance with the operation in question and the data provided in the operation. The sequence of these operations over time affects changes to the filesystem structure, data, and metadata in a predictable way. The set of filesystem abstractions, operations, and predictable results for particular actions is said to constitute “semantics” for the filesystem. While particular filesystems differ slightly in their precise semantics, in general filesystems implement as a subset of their full semantics a common semantics. This approximately equivalent common semantics can be regarded as the “conventional” or “traditional” filesystem semantics.
[0007] Storage resources accessed by some computer, its software or users need not be “directly” attached to that computer. Various mechanisms exist for allowing software or users on one computing device to access over a network and use storage assets that are actually located on another remote computer or device. There are many types of remote storage access facilities, but they may without loss of generality be regarded to fall into one of two classes: block-level and file-level. File-level remote storage access mechanisms extend the filesystem interface and namespace across the network, enabling clients to access and utilize the files and directories as if they were local. Such systems are therefore typically called “network file systems.” Note that the term “network file system” is used herein generally to refer to all such systems—there is a network file system called Network File System or NFS, originally developed at Sun Microsystems and now in the public domain. When discussing the general class of such systems herein, the lower-case term, e.g., “networked file systems” will be used. When discussing the specific Sun-developed networked file system, the fully capitalized version of the term or its acronym, e.g., “Network File System or NFS” will be used.
[0008] Networked file systems enable machines to access the filesystems that reside on other machines. Architecturally, this leads to the following distinctions: in the context of a given filesystem, one machine plays the role of a filesystem “origin server” (alternatively, “fileserver” or “server”) and another plays the role of a filesystem client. The two are connected via a data transmission network. The client and server communicate over this network using standardized network protocols; the high-level protocols which extend the filesystem namespace and abstractions across the network are referred to as “network filesystem protocols.” Exemplary filesystem protocols include the Common Internet File System (CIFS), the aforementioned NFS, Novell's Netware filesharing system, Apple's Appleshare, the Andrew File System (AFS), and the Coda Filesystem (Coda). CIFS and NFS are by far the most prevalent. These network filesystem protocols share an approximately equivalent semantics and set of abstractions, but differ in their details and are noninteroperable. Thus, to use a filesystem from a fileserver, a client must “speak the same language,” i.e., have software that implements the same protocol that the fileserver uses.
[0009] A fileserver indicates which portions of its filesystems are available to remote clients by defining “exports” or “shares.” To access a particular remote fileserver's filesystems, a client must then make those exports or shares of interest available by including them by reference as part of their own filesystem namespace. This process is referred to as “mounting” or “mapping (to)” a remote export or share. By mounting or mapping, a client establishes a tightly coupled relationship with the particular file server. The overall architecture can be characterized as a “two-tier” client-server system, since the client communicates directly with the server which “has” the resources of interest to the client.
[0010] In addition to organizing and maintaining the relationships between filesystem clients and file servers, additional challenges exist in managing access to and utilization of filesystems. While most organizations have and enforce stringent document workflow and retention policies for their paper files, similar policies—while desired and mandated—are rarely enforced for electronic files. As a non-limiting example, many corporations have a policy that prohibits the usage of corporate storage capacity on fileservers for the storage of certain personal files and content types, for instance, digital music in MP3 format, personal digital images, and so on. This “policy” usually takes the form of a memo, email, entry in a company policy manual, etc. The administrators in charge of enforcing this policy face significant challenges. Conventional filesystems do not provide mechanisms for configuring a filesystem to only allow particular content types or otherwise make decisions about what should be stored, where, and how. These conventional filesystems are static, and the set of semantics for access and other administrative controls are rather limited. Thus any such policy enforcement that happens is done retroactively and in an ad-hoc manner via manual or mostly-manual processes. The net result is that network file storage fills up with old, duplicated, and garbage files that often violate corporate and administrative utilization policies.
[0011] In today's increasingly litigious environment and in the presence of new rules and regulations such as the Health Insurance Portability and Accountability Act of 1996 (HIPAA) and the Sarbanes-Oxley Act of 2002, the lack of management, including the inability to enforce policies consistently and effectively, represents a serious risk that corporations and businesses alike must rush to address. Unfortunately, as a direct result of the general lack of innovation and improvement in filesystem architecture over the last 30 years, viable solutions that could provide practical and effective policy management to enterprises do not seem to exist.
[0012] Perhaps a general comparison between typical databases systems and typical filesystems could provide an insight as to the lack of innovation and improvement in filesystem architecture. For databases, storage is usually organized into tables arranged in a flat space (i.e., tables may not be contained in other tables) which contain records with generally fixed form. Such database systems often provide a notion of “triggers” and “stored procedures.” Triggers define a set of conditions; when the database is manipulated in a way that matches some condition, the stored procedure associated with that trigger is executed, potentially modifying the transaction or operation. This mechanism is used primarily in two ways in database applications: to ensure data correctness and integrity and to automate certain administrative and application-specific tasks. The analogous facility is not available in filesystems because filesystems are quasi-hierarchical collections of directories and files. As such, triggers cannot be generally or easily defined with associated stored procedures that can be automatically activated and enacted synchronous with a filesystem activity in any extant filesystem.
[0013] In general, implementation of triggers and stored procedures in filesystems is significantly more complex than in databases systems because of less regular structure of filesystems, their less formally well-defined semantics, and because file data is itself arbitrarily semi-structured and loosely typed. Implementation of programmable procedures which respond to an arbitrary filesystem operation by modifying the operation is challenging when the correct (i.e., traditional, expected, etc.) semantics of filesystems must be preserved. There are existing systems that will generate “events” when operations occur on the filesystem; these events can then be used to activate arbitrary actions post-facto. However, the actions cannot themselves modify the file operation, since the event which activates them is not generated until the triggering operation completes.
[0014] Currently, the “intelligence” that a conventional filesystem exhibits with respect to access control is typically restricted to a static set of rules defining file owners, permissions, and access control lists. To the extent even this relatively low level of “intelligence” exists, it is usually statically defined as a part of the filesystem implementation and may not be extended.
[0015] In a typical enterprise, the files and directories stored in the enterprise filesystems represent unstructured or semi-structured business intelligence, which comprises the work product and intellectual property produced by its knowledge workers. The work product may include business-critical assets and may range from Excel spreadsheets representing (collectively) the financial health and state of the enterprise to domain-specific artifacts such as Word documents representing memos to customers. However, in contrast to the data stored in “mission critical” information systems such as logistics systems, inventory systems, order processing systems, customer service systems, and other “glass house” applications, the unstructured and semi-structured information stored in the enterprise filesystems is largely “unmanaged.” It is perhaps backed up but little or no effort is made to understand what the information is, what its relevance or importance to the business might be, or even whether it is appropriately secured.
[0016] As examples, assuming that a user ‘Idunno’ has stored unauthorized and illegal copies of MP3 music files in a “home directory” on some file server that belong to a corporation ‘Big Corp’ where Idunno works. In doing so, Idunno has perhaps violated a corporate policy of Big Corp stating that no MP3 files are to be stored on the network. However, the system managers may have no knowledge to this violation, nor any automated means of remedying the situation. Even in the event that the system managers are able to episodically inventory the filesystems for such violators, they are often loathe to automatically take appropriate actions (e.g., deleting) on such offending files. The reason is that, more often than not, while they have the responsibility for enforcing such policies, they do not have the authority to do so. To remedy this, the end-user (i.e., the file owner—in this example, Idunno) or some other responsible party must be brought “into the loop.” Other examples of file management policies might include: documents relating to patients' individual medical conditions within a healthcare provider business might be stored in such a way that perhaps would violate the privacy constraints of HIPAA; or financial documents within the finance operation of a Fortune 2000 company might be stored in such a way that perhaps would violate both regulatory requirements under the Sarbanes-Oxley Act of 2002 and internal corporate governance considerations.
[0017] The pressing need to monitor filesystems and to report activities related to the filesystems presents a challenge of unprecedented scope and scale on many fronts. Filesystem activity produces changes to the state of a filesystem. This activity can affect changes to the structure, the stored metadata, and the stored data of the directories and files. Generally speaking, this activity is not logged in any way; rather, the filesystem itself holds its current state. Some filesystems—called “journaling” filesystems—maintain transient logs of changes for a short duration as a means of implementing the filesystem itself; however, these logs are not typically organized in any way conducive to monitoring and reporting on the state of the filesystem and its activity and are not made available to external programs for that purpose. Further, these logs are frequently purged and therefore provide a poor basis for reporting of historical and trend data.
[0018] One significant and open problem is that of collection, redaction, and analysis of high-level data about what a filesystem is being used for, what is stored in it, by whom and for what purpose. Solutions today involve software programs or users explicitly walking through the filesystem structure, gathering the data required, and then analyzing it and/or acting on it, etc. Collection of filesystem data proactively as operations occur is generally not done as it is generally not supported by the filesystem itself. Furthermore, the accuracy of such collected data is usually questionable, as it reflects not an instantaneous state of the filesystem at any given moment, but, rather, an approximate state of the filesystem over the duration of the run. Without collecting and maintaining the appropriate statistics as file operations occur, it is impossible for the data, at the end of the run, to represent a correct and accurate picture of the contents of the filesystem at that time.
[0019] The problem of data collection and reporting is further compounded in the network filesystem environment. Because each server—indeed, each filesystem on each server—is a separate entity, it is therefore necessary to perform each data collection independently on each server. If reporting or monitoring is to be done across the network filesystem environment, significant challenges exist; namely, because of the parallel and discrete nature of the collection runs, it becomes difficult or impossible to sensibly merge the collected data into a consistent snapshot of the state of the filesystem at some time.
[0020] It is further the case that collection and storage of all such data as it occurs could be untenably burdensome; such logs would “grow” quickly and consume additional storage capacity at an undesirable rate. A need exists for a system and method that would allow ongoing statistics to be gathered and maintained while simultaneously constraining the total amount of storage capacity that must be dedicated to such a purpose. Embodiments of the present invention address this need and more.
SUMMARY OF THE INVENTION
[0021] One aspect of the invention is directed to a classification engine having the ability to both collect data as it occurs and dynamically redact or “historicize” it, allowing ongoing statistics to be gathered and maintained while simultaneously constraining the total amount of storage capacity that must be dedicated to such a purpose. In one embodiment, the classification engine is operable to extract various types of information from an object (e.g., a document, a file, a unit of data, etc.). In one embodiment, the classification engine is operable to tag various types of information (e.g., system information, security information, content information, etc.) extracted from or otherwise obtained on the object.
[0022] One embodiment of the invention provides a system and method for exposing or opening up the classification engine across a network through an interface. Through the interface, the functionality of the classification engine can be made available as a set of services (e.g., extraction, tagging, classification, etc.) to a plurality of clients in a distributed computing environment. One embodiment of the interface allows clients in a networking environment to plug in and use the functionality of the classification engine at their leisure.
[0023] According to embodiments of the invention, the interface can be implemented in various ways. For example, it can be a Web interface including but not limited to XML over HTTP, XML RPC, SOAP, any form of remote procedural call interface, an Applications Programming Interface (API), etc. The API can be configured to operate synchronously or asynchronously.
[0024] In one embodiment, the functionality of the classification engine is implemented in a pipeline software construct or framework which provides for optimal configurability and extensibility. In one embodiment, the classification pipeline can be implemented as a piece of software which allows new functionality (e.g., disambiguity, content-based hashing, etc.) to be added or otherwise readily adapted. The classification pipeline software framework can also provide clients with the ability to customize a list of services and configure how these services should perform and/or upon what information these services should perform.
[0025] In some embodiments of the invention, actions (e.g., executing a business policy, harvesting metadata, generating a report, etc.) may be taken based upon the classification of object(s) or based upon metadata associated with the object(s). Such actions may generate additional metadata about the object(s) which can be recursively sent back to the classification pipeline. For example, in extracting system metadata for an object, various types of attributes of the object can be analyzed and classification applied. Conditions on these attributes (e.g., how many instances are there, etc.) may be obtained by or submitted to a policy engine which may generalize the attributes based on the conditions and recursively send them back into the classification engine again. If reporting or monitoring is to be done across a particular network environment, the classification pipeline can be configured to collaborate with other software in the network environment to provide a consistent snapshot of the state of that particular network environment based on data collected at the time.
[0026] Embodiments of the classification pipeline disclosed herein can provide many advantages. One advantage is that the classification pipeline can provide comprehensive insight on the collected data. More specifically, embodiments of the invention can provide a classified object with multi-dimensional context, including the context of filesystem metadata, the context of security information, the context of directory information about who people are in an organization, the context of entities (e.g., content, keywords, regular expressions, etc.) extracted from or otherwise obtained on an object (e.g., a document, a file, etc.), and so on.
[0027] Another advantage relates to configurability. Embodiments of the classification pipeline disclosed herein can be readily configured by a plurality of clients across a network. Each client can choose what functionality of the classification pipeline to apply and how.
[0028] Yet another advantage the invention is directed to adaptability, which can translate into cost savings in implementation. The classification pipeline software construct disclosed herein allows a new functionality (i.e., a piece of software) to be inserted into the classification pipeline as a service, a layer, a stack, a stage, or a metadata space. As such, embodiments of the classification pipeline can be readily modified or otherwise updated to adapt to changes (e.g., changes in classification requirements due to a new business policy, a new privacy regulation and/or a new discovery rule, etc.).
[0029] Another advantage of the invention is directed to extensibility. Embodiments of the classification pipeline disclosed herein can be presented as services across a network environment, allowing a multitude of clients to subscribe to or acquire multiple classification services. As discussed above, each client can customize or otherwise configure its classification pipeline across the network environment to set classification requirements, create a new vocabulary for desired information, insert a new functionality, etc.
[0030] Other objects and advantages of the present invention will become apparent to one skilled in the art upon reading and understanding the detailed description of the preferred embodiment(s) described herein with reference to the following drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] A more complete understanding of the present invention and the advantages thereof may be acquired by referring to the following description, taken in conjunction with the accompanying drawings in which like reference numbers indicate like features.
[0032] FIG. 1 depicts a block diagram illustrating a synchronous integration flow of a classification pipeline according to one embodiment of the present invention.
[0033] FIG. 2 depicts a block diagram illustrating an asynchronous integration flow of a classification pipeline according to one embodiment of the present invention.
[0034] FIG. 3 depicts a classification pipeline according to one embodiment of the invention.
[0035] FIG. 3A depicts another exemplary embodiment of a classification pipeline.
[0036] FIG. 4 depicts an exemplary configuration of a classification pipeline according to one embodiment of the invention.
[0037] FIG. 5 depicts an exemplary system implementing one embodiment of the invention.
[0038] FIG. 6 depicts one embodiment of an exemplary architecture for the implementation of a system for processing objects through classification pipelines.
DETAILED DESCRIPTION
[0039] The present invention and various features and advantageous details thereof will now be described with reference to the exemplary, and therefore non-limiting, embodiments that are illustrated in the accompanying drawings. Descriptions of known programming techniques, computer software, hardware, network communications, operating platforms and protocols may be omitted so as not to unnecessarily obscure the invention in detail. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only and not by way of limitation. Various substitutions, modifications, additions and/or rearrangements within the spirit and/or scope of the underlying inventive concept will become apparent to those skilled in the art from this disclosure.
[0040] Before describing embodiments of the invention in detail, it might be helpful to clarify a few terms used in this disclosure. A “file classification” can have one or more file attributes and can be associated with one or more volumes. A volume is a mountable share where objects (e.g., subject files) reside on a server. A file attribute is an entity, an instance of a file classification or file system metadata. The term “file system metadata” or its acronym “FSMD” encompasses file system attributes that embodiments of the invention maintain about files. An exemplary list of file system attributes implementing embodiments of the invention can be found in the User's Guide, StoredIQ Appliance 4.0, July 2006 edition, pp. 106-125, attached as appendix A to the present application. FSMD may comprise metadata such as access and creation times, file size, etc. A content-based entity is an instance of data, type of entity, location of entity, or data match. Examples of entities can be found in the aforementioned User's Guide.
[0041] Attention is now directed to systems, methods and apparatuses for a classification pipeline configured to provide a set of tagging and extraction services. The classification pipeline disclosed herein may be embodied in computer-executable program instructions residing on computer-readable media. In one embodiment, a system implementing the classification pipeline disclosed herein is programmed with computer-executable program instructions for extracting and/or analyzing the data of files or other objects in the filesystem (collectively referred to as objects) or metadata pertaining to these objects, in order that the objects may be classified and/or certain actions taken based on the classification of the object. Actions (e.g., executing a business policy, harvesting metadata, generating a report, etc.) may be taken based upon the classification of the object or based upon metadata associated with the objects.
[0042] In embodiments of the invention, the tagging and extraction services provided by the classification pipeline are made available to one or more clients (i.e., machines running client software) through an interface. In the present disclosure, this interface is interchangeably referred to as the “classification pipeline interface” or simply “the interface”. The interface may be implemented in various ways. For example, it may be implemented as an application web interface or an Applications Programming Interface (API). It may be implemented as a single synchronous interface or a set of asynchronous interfaces. One example of a synchronous interface for a classification pipeline is described below with reference to FIG. 1 . One example of a set of asynchronous interfaces for a classification pipeline is described below with reference to FIG. 2 . In both examples, the classification pipeline configuration can be controlled through the interface, which is implemented as an API exposed as a series of XML request and replies over TCP.
[0043] A synchronous interface implementing embodiments of the invention may comprise two components: the Classify Object Request and the Classify Object Response. The Classify Object Request is designed to pass a set of parameters to the classification pipeline for a single file. The metadata for the specified file is extracted and passed back to the requesting application on the Classify Object Response. The interface of this type may be referred to as an “Object_Classify_Request interface”.
[0044] In one embodiment, the Classify Object Request can pass at least two types of parameters: required and optional. Required parameters may include File Name (i.e., the name of the file to be classified) and Volume (i.e., the volume where the file is located.) The File Name parameter could be fully qualified relative to the context provided by the Volume parameter. In one embodiment, the Volume parameter refers to a volume defined within an appliance that is hosting the pipeline (e.g., a StoredIQ appliance), in which case, a volume must first be defined on that appliance (e.g., using the StoredIQ user interface) before it can be given as a parameter. Various volume types (e.g., CIFS, NFS, Netware, Centera, Exchange, etc.) may be implemented in embodiments of the invention. Examples of volume configuration options can be found in the aforementioned User's Guide, StoredIQ Appliance 4.0, July 2006 edition, pp. 36-39.
[0045] Optional parameters for the Classify Object Request may include:
Pipeline Profile Name—Refers to the name of a pipeline profile that is defined on the appliance hosting the classification pipeline. The pipeline profile determines what sets of metadata the client application will receive from the classification pipeline. Using the StoredIQ appliance as an example, the pipeline profile is set up in the System Configuration tab of the StoredIQ user interface. If no pipeline profile name is passed, the default is to provide all sets of metadata. Other configurations are possible. Object System Metadata—This parameter includes data such as file size, access times, and modified times. The data will vary depending upon the underlying object system (e.g., CIFS, NFS, Netware, etc.). Embodiments of the classification pipeline are configured to extract all types of metadata. In cases where user(s) inherently have object system metadata “in hand” (e.g., as a function of learning or acquiring the name of the file to be classified), the classification pipeline is operable to allow the user(s) to pass the user-acquired data into the pipeline. External Metadata—This parameter provides a mechanism for client applications to pass in metadata that is not created by the pipeline per se, but can be referenced within the object classification rules engine to assist in the classification processing.
[0049] There are many different types of metadata, including metadata about electronic documents created by client applications. Document metadata describes document attributes such as the title, author, content, location, and date of creation. Since it is often possible to view a history of every change ever made to an electronic document during its lifetime, acquiring this type of information can help in “historicizing” and/or classifying the document. Document metadata can include edits and comments made by the author and other users to a document as well as hidden information about the document. Exemplary document metadata may include one or more of the following: text changes, comments, document versions, document revisions, template information, file properties and summary information, author's name, author's initials, author's email address, company or organization's name, name of the computer on which it is created, name of the hard disk, volume, or network server on which the document is saved, routing information, names of previous authors, hyperlinks, macros, hidden text, and non-visible portions of embedded Object Linking and Embedding (OLE) objects, etc.
[0050] FIG. 1 depicts a block diagram illustrating a synchronous integration flow of a classification pipeline according to one embodiment of the present invention. API 120 can be used by any type of software application to interface with the classification pipeline. For example, Application 100 may wish to receive information pertaining to a certain object or to a certain location on a particular filesystem. More details on the term “object” will be described below with reference to FIGS. 3-5 . To obtain this information on the object, Application 100 may send a <Classify Object Request> 102 (“request 102 ”) to Classification Pipeline 110 with information pertaining to the object on which Application 100 wishes to receive information. The information pertaining to the object sent via request 102 may include information such as the volume on which the object is located or the name of the object.
[0051] To facilitate the sending of request 102 (and possibly of response 104 to request 102 ), request 102 may be formulated according to API 120 or any suitable API that Classification Pipeline 110 is operable to implement. Classification pipeline 110 may then obtain or extract metadata on or about the object, and/or classify the object according to a set of classification parameters. In one embodiment, the metadata extracted or obtained on the object may be dependent on a level of service specified in conjunction with Classification Pipeline 110 . In response to request 102 , Classification Pipeline 110 may send a <Classify Object Response> 104 (“response 104 ”). Response 104 may contain information pertaining to the object on which information was requested in request 102 . This information on the object may be metadata pertaining to the object (e.g., Pipeline Metadata) or data contained by the object, or a classification of the object, or tagged entities that were found within the content of the object. In one embodiment, metadata in response 104 may be formulated as an XML string.
[0052] The interaction with Classification Pipeline 110 depicted in FIG. 1 may occur in a synchronous manner. In other words, Application 100 may send request 102 to Classification Pipeline 110 , which in turn will respond with response 104 to the same Application 100 when metadata has been obtained on the object, or the object has been classified. In some cases, however, it may be desirable to have separate, asynchronous interactions, such that a request pertaining to an object may be sent by one application and the metadata or classification information about that object may be sent to, or obtained by, another distinct application, portion of application or location.
[0053] Asynchronous interfaces allow an asynchronous ingest and an asynchronous publish subscribe interface to the pipeline's output. They may be configured with one or more of the following abilities: get and set volume definitions, get and set file classification definitions, get and set new entity types, and get and set pipeline profile configurations.
[0054] FIG. 2 depicts a block diagram illustrating an asynchronous integration flow of a classification pipeline according to one embodiment of the present invention. In this example, Application 200 may send a <Classify Object Request> 202 (“request 202 ”) to Classification Pipeline 110 with information pertaining to the object on which Application 200 wishes to receive information. The information pertaining to the object sent via request 202 may include information such as the volume on which the object is located or the name of the object. Request 202 may also contain information on the location to which a response to request 202 is to be delivered, such as to what application the response should be delivered, what portion of an application the response should be delivered, or if the response should be stored etc. To facilitate the sending of request 202 , request 202 may be formulated according to API 120 or any suitable API that Classification Pipeline 110 is operable to implement.
[0055] In response to this initial request 202 , Classification Pipeline 110 may send a <Classify Object Response> 204 (“response 204 ”) indicating that request 202 has been received by Classification Pipeline 110 and that information will be delivered to the requested application/location. Classification Pipeline 110 may then operate to obtain or extract metadata on or about the object, or to classify the object according to a set of classification parameters. In one embodiment, the metadata extracted or obtained on the object may be dependent on a level of service specified in conjunction with Classification Pipeline 110 .
[0056] Once this information has been obtained, Classification Pipeline 110 may send a <Classified Object Assertion> 206 (“response 206 ”). Response 206 may contain information pertaining to the object on which information was requested in request 202 , and may be sent to the location, application or portion of application specified in request 202 . Although response 206 is depicted in FIG. 2 as being sent to Application 200 , this is for the convenience of depiction and for the purpose of illustration only. Response 206 may be delivered to another application (not shown), a location (not shown), or a certain procedure or portion of Application 202 . This information on the object may be metadata pertaining to the object or data contained by the object, or a classification of the object. In one embodiment, metadata in response 206 may be formulated as an XML string.
[0057] Upon receiving response 206 , Application 200 (or a portion of Application 202 ) may send a <Classified Object Acknowledgement> 208 (“response 208 ”) acknowledging that the information pertaining to the object has been received.
[0058] Moving to FIG. 3 , one embodiment of a classification pipeline is depicted. Classification Pipeline 300 may comprise a plurality of layers through which metadata can be obtained and/or processed for submission to Object Classification Rules Engine 326 . The term “layers” is representative of the various ways in which the functionality of Classification Pipeline 300 may be implemented (e.g., services, stages, etc.). In one embodiment, the functionality of Classification Pipeline 300 can be divided into three levels (Object System Metadata Processing 301 , Content-based Metadata Processing 303 , and Entity Processing 305 ).
[0059] Object System Metadata Processing 301 may comprise layers 302 , 304 , and 306 for extracting system-level metadata which pertains to the keeper of the object (e.g., the system on which the object resides, the surrounding systems, the type of filesystem on which the object resides, the security settings pertaining to the object, other filesystem information such as user directories, etc.). Current filesystems generally provide ample amounts of system metadata. Object System Metadata Extraction 302 may operate to extract raw system metadata pertaining to the location and type of filesystem on which an object resides. This can be done by using the volume parameter passed in on the <Object Classification Request>. Each volume has a system type. Object System Metadata Extraction 302 may operate to map available attributes based on the system type. The type of volume is extensible (i.e., new system types can be readily added). Object System Metadata Extraction 302 may operate to collaborate, from within the pipeline and based on detailed information extracted thus far, with other software facilities within a network (e.g., an enterprise policy engine in an enterprise network) to aggregate, enrich, and/or augment the extracted metadata (e.g., the enterprise policy engine may recursively feed analyzed attributes back into Object System Metadata Extraction 302 ).
[0060] Security Extraction 304 may operate to extract an object's security settings such as access permissions. Like system metadata, the security settings are a type of metadata that exist on objects which can be extracted, tagged, and classified via Classification Pipeline 300 . The extracted security information can be useful for forensic and/or reporting purposes. For example, one might desire to know, while an object is being tagged, how many times the object had been accessed, when and perhaps by whom. In this way, access behavior may be analyzed based on the extracted security information and the historic value(s) associated therewith.
[0061] User Directory Extraction 306 may operate to extract system metadata pertaining to user directories associated with the object. User Directory Extraction 306 can enrich the extracted system metadata with directory information (e.g., the active directory where an object currently resides on a user computer).
[0062] Additional system-level processing is possible to extract from the keeper of an object other types of metadata germane to the structure (e.g., file type) of the object (e.g., “Sender” may be germane to “Email”, “Author” may be germane to “Document”, etc.). The keeper of the object refers to the system(s) on which the object resides. As an example, a client can simply plug in, insert or otherwise add new metadata extraction algorithm(s) or processing layer(s) to Classification Pipeline 300 .
[0063] Content-based Metadata Processing 303 may comprise layers 308 , 310 , 312 , 314 , 316 and 318 for obtaining metadata on an object based upon the content of the object (e.g., free form text of an email or document, etc.). For example, Duplicate Hash Computation 308 may operate to perform a binary hash to detect possible duplicate objects which can then be removed (also called “deduplication”). In one embodiment, another layer (not shown) can be added to perform a text-based hash on the content of the object to see if it has changed semantically. This can be done before extractions 314 , 316 , 318 .
[0064] Content Typing 310 may operate to determine the type of object by its content and not by its extension. As an example, a file named “work.doc” may be an .mp3 file in disguise. Determining the type of a document based on what's in it can help to ensure the accuracy of its classification.
[0065] Text Conversion 312 may operate to process and prepare the text of the object for content-based extraction operations (e.g., Keyword Extraction 314 , Raw Entity Extraction 316 , Text Pattern Extraction 318 , etc.). Other content-based metadata extraction operations are also possible. In one embodiment, another layer or module (not shown) can be added to remove any ambiguity (also called “the disambiguity” layer”) in the content of the object. As one skilled in the art can appreciate, removing ambiguity (e.g., run-on sentences, improper punctuation, extra spaces, tables, dashes or hyphens in words and sentences, etc.) from the content can improve performance. The aforementioned text-based hashing can be performed on the converted text as well.
[0066] The converted text next is broken down into speech units (e.g., names, cities, nouns, verbs, etc.) and goes through a battery of extraction processes (e.g., Keyword Extraction 314 , Raw Entity Extraction 316 , Text Pattern Extraction 318 , etc.). These layers of extraction operate to look for keywords, semantic entities, word units, expressions, text patterns, etc. and extract them from the text based on some predetermined parameters (e.g., a client desiring to locate documents discussing patient privacy might specify a list of relevant keywords such as “patient” and “privacy” based on which Keyword Extraction 314 is operable to go through the text and tag documents that contain those keywords). In some embodiments, third party text processing software development kits such as ThingFinder® by Inxight Software, Inc. of Sunnyvale, Calif. can be used to supplement this functionality. Inxight ThingFinder® can automatically identify, tags, and indexes about 35 types of named entities in a document, such as persons, organizations, dates, places, and addresses.
[0067] Entity Processing 305 may comprise layers 320 , 322 , and 324 for processing the object and/or metadata previously obtained from the object. In particular, the object and metadata previously obtained may be combined or analyzed to produce further metadata on the object. In embodiments of the invention, Filtering/Scoping 320 may operate to tag metadata according to predetermined scope(s)/filtering rule(s), which are user-definable. This can be useful in classifying objects in compliance with privacy policies and/or rules. With this functionality, objects may be included (scoping) and/or excluded (filtering) from one or more classes.
[0068] Proximity Analysis 322 may operate to tag or select an entity (metadata) based on its proximity or affinity to another entity or entities. For example, to distinguish from all dates a user may specify for Proximity Analysis 322 to find dates in proximity to a particular word or entity. As another example, to find names of people who work in hospitals, a user might first create an entity called “Hospital Names” and distinguish from all names only those that are in proximity to Hospital Names using Proximity Analysis 322 . These are examples of proximity-based entities.
[0069] At this point, everything about an object is tagged and there could be a plurality of entities (extracted as well as created by the layers in the classification pipeline) of various types. User Level Entity Assertion 324 may operate to normalize these entities and interface with Object Classification Rules Engine 326 for submitting objects and their associated data. In this respect, User Level Entity Assertion 324 can be seen as interfacing between the tagging functionality and the classification functionality of Classification Pipeline 300 . That is, an object may move up or through Classification Pipeline 300 as metadata concerning the object continues to be collected, enriched, and augmented. Once it reaches the last node, in this case, Proximity Analysis 322 , the tagging aspect of the pipeline is done and User Level Entity Assertion 324 can assert all the data in its aggregate into Object Classification Rules Engine 326 .
[0070] In one embodiment, Object Classification Rules Engine 326 is operable to classify objects according to a set of rules which define classes for objects based upon various data, metadata or various combinations associated therewith. Each object is classified based on its associated data according to these rules. These classification rules are user-definable and can be expressed in the form of conditions. In one embodiment, a condition has an attribute in terms of a value or value plus instances. In this way, if an object has an entity associated therewith that satisfies a condition, Object Classification Rules Engine 326 may classify that object to be a member of a class having that condition. Once the class membership is asserted, its class can be expressed in terms of another class (i.e., the class becomes the object's another attribute). This complex class membership can be interpreted subsequently during class processing.
[0071] It will be apparent to those of skill in the art that the stages or layers 302 - 326 depicted with respect to Classification Pipeline 300 are exemplary only, and that Classification Pipeline 300 may include more or fewer stages depending on the functionality of Classification Pipeline 300 desired. As an example, FIG. 3A depicts an embodiment of Classification Pipeline 330 comprising layers 332 , 334 , 336 , 338 , 340 , 344 , and 346 for operating on metadata spaces listed in Table 1 below. In one embodiment, layers 332 , 334 , 336 , 338 , 340 , 344 , and 346 are implemented as a set of tagging and extraction services available through a Web interface or an API interface.
[0000]
TABLE 1
Metadata Spaces
Description
Object System
Includes all core metadata acquired from the
underlying system where an object resides
and includes attributes such as size,
creation date, and modified date.
Security
Contains all security information from an
object.
User Directory
User and group mappings from the current
directory of an object.
Content
Contains a SHA-160 bit hash of the object
Signature
being processed.
Content-based
Contains a series of attributes representing
Typing
the type of object derived from an analysis
of the object's content.
Content Entities
Includes all entities that are located via
text and natural language processing of the
object's content. The scope of the entities
to be extracted is based on the entities
located within the active file
classification(s) for the volume specified
on the pipeline object classification
request. Examples of entities can be found
in the attached Appendix B, entitled
“Understanding standard entities.”
Object
Indicates that the pipeline client wants
Classification
specified objects to be classified against
the file classification rules defined for
the provided volume.
[0072] In one embodiment, clients (e.g., application 100 ) of the classification pipeline (e.g., Classification Pipeline 110 ) can subscribe to specific metadata spaces listed above by defining a pipeline profile. If no pipeline profile is provided (e.g., request 102 contains no pipeline profile), the classification pipe may be configured to provide all sets of metadata.
[0073] In embodiments of the invention, any of the above-described layers and options of the classification pipeline can be turned on and off by metadata subscription. As an example, a client may choose to subscribe to a particular profile of the pipeline and configure it accordingly. As another example, a client may choose to tag an object but not classify it.
[0074] In some cases, a client may desire to have some dimensions of classification that is germane to a particular application domain, but not necessarily part of the classification pipeline. For example, a class may require its members to contain the name “Steve”, be bigger than one megabyte in file size, be created over one year ago, mention a software product called “Classification Pipeline,” and references the city of Austin. In one embodiment, a user can pass the classification requirements in from the application domain to the classification engine (e.g., Object Classification Rules Engine 326 ) and the classification pipeline (e.g., Classification Pipeline 300 ) can synthesize the user-defined classification requirements with all the tag attributes (e.g., name, size, date, text pattern, keyword, etc.) and feed them into the classification engine to assert classification accordingly. In this way, classification can be done based on dynamically inserted requirements from external applications.
[0075] FIG. 4 depicts an exemplary configuration of one embodiment of the classification pipeline, illustrating by example how embodiments of the classification pipeline disclosed herein may be utilized in conjunction with external applications or data. Pipeline configuration can be controlled via an application web interface, or through an API exposed as a series of XML request and replies over TCP. The example shown in FIG. 4 exemplifies pipeline configuration via the API and adopts the following terminology:
[0000] Object-Class—consists of one or more conditions, all of which can be combined by an “AND” and “OR” Boolean operations or instance requirement counts.
Condition—consists of a single Object-Attribute and value/occurrence based expression whose scope is constrained by the Object-Attribute properties. For the purpose of inclusion within an Object-Class, a condition on an Object-Attribute has the following dimensions.
Object-Attribute—consists of file system metadata, content based data, and user-defined (i.e., custom) attributes. Each Object-Attribute can have the following properties:
Base Type (e.g., String, Integer, Date, Occurrence) Sparse or Dense Indicator Single or Multiple Instance Data Values or Partial Data values (is, contains, begins with, ends with, regular expression values)
Object-Attribute Tagging/Extraction Implementations—can be Core or Custom:
[0000]
Core Object-Attributes—default object-attributes provided by the classification pipeline.
Custom Object-Attributes—object-attributes created by applications (including the classification pipeline) users, available for viewing and updating. Custom Object-Attributes can have the following types:
Keyword—Custom Object-Attributes Regular Expression-based—Custom Object-Attributes
[0085] There are four types of pipeline configuration objects that control the behavior of the classification pipeline: Volumes, Pipeline-Profile, Object-Attributes, and Object-Classes. In the example shown in FIG. 4 , pipeline configuration objects 400 (Volume 410 , Object-Classes 420 , Object-Attributes 430 , and Pipeline Profile 440 ) control the behavior of Classification Pipeline 300 .
[0000] Volume—A volume is an aggregation of data needed to address a repository of objects somewhere on the network. A volume can include the name of the server, the name of the share, the protocol to be used in communicating with the server, authentication credentials (if applicable to the protocol), a starting directory from which subsequent file requests are relative, and an include directory regular expression. The latter two items can allow for specification of subsections of share when it is desirable to logically break up a network share.
Pipeline-Profile—A pipeline-profile comprises a series of options that control which sets of metadata are extracted from an object as it passes through the pipeline. Following the example shown in FIG. 3A , these options may include the following:
Enable/disable content signature calculation; Enable/disable system metadata extraction; Enable/disable content based object file-type calculation; Enable/disable classification engine; Enable/disable directory resolution; Enable/disable extraction of security information; Enable/disable the extraction of content Object-Attributes; and Maximum number of content Object-Attributes to extract per type per object.
Object-Attribute—depending upon implementation, Object-Attributes can fall into two categories: core or custom. Core Object-Attributes are provided with the classification pipeline and are immutable. The definition of custom Object-Attributes is controlled by the user. “Person” and “Address” are examples of core Object-Attributes. One embodiment of the invention supports two custom Object-Attribute types, keyword and regular expression. Users can create and modify custom Object-Attributes of these types. Since Object-Attributes are the vocabulary upon which Object-Classes are built, the ability to add custom Object-Attributes allows a user to extend this vocabulary.
Object-Attributes have the following properties:
Name—name of the Object-Attribute; Custom—(Boolean) determines whether Object-Attribute is of type custom; Base-type—integer, date, string, occurrence; Dense—(Boolean) determines whether the Object-Attribute is dense or sparse (i.e., is it always present); and Multi-instance—(Boolean) determines whether multiple instances are possible.
[0099] The latter four determine what conditions can be applied to a particular Object-Attribute.
[0000] Object-Class—An Object-Class is a collection of conditions expressed across Object-Attributes. Each condition within an Object-Class enumerates value/instance-based expressions across a single Object-Attribute. An Object-Class may be associated with one or more volumes and there can be multiple Object-Classes associated with a given Volume. One example of an Object-Class is defined as a path containing a sub-string “home” AND the presence of a social security number (SSN) and is associated with all volumes. In this case, the conditions are:
Object-Attribute—path
Condition—contains “home”
Object-Attribute—SSN
Condition—at least one time.
[0104] Referring to FIG. 4 , Classification Pipeline 300 may receive Volume 410 specifying a location on a filesystem, a filename or object name, or a profile of an object which may indicate which objects to process through Classification Pipeline 300 or which may indicate services within Classification Pipeline 300 are desired. Utilizing some of this information, Classification Pipeline 300 may extract metadata and classification information on the object and pass this metadata or classification to another application.
[0105] As described above, Classification Pipeline 300 may be utilized in conjunction with configuration data 400 to tailor classification pipeline. Pipeline Profile 440 received by Classification Pipeline 300 may indicate desired layers or services of Classification Pipeline 300 (e.g., extract security information but no hash computation) or may indicate how Classification Pipeline 300 is to be set up. Other configuration data may include various volumes of filesystems, particular servers, protocols or various access information associated with objects on which Classification Pipeline 300 is to operate. Objects classes may be defined by rules which define classes to which objects may belong. These object classes may be associated with certain volumes or filesystem types such that when files from a particular filesystem or filesystem type are processed by Classification Pipeline 300 , Classification Pipeline 300 may determine if these objects are of that class.
[0106] Components of the classification pipeline disclosed herein can be controlled programmatically through an XML over TCP interface. For example, a plurality of methods can be provided to GetAll, Get, Create, Update, and Delete for each of the pipeline configuration objects 400 described above. An exemplary breakdown of methods, parameters, parameter descriptions, types, and return values is attached to this disclosure as Appendix C. Other implementations are also possible.
[0107] Embodiments of the classification pipeline disclosed herein may be utilized as part of a broader system. One embodiment of such a system 500 is depicted in FIG. 5 . Classification Pipeline 300 may interface with a set of applications 510 (e.g., StoredIQ Walkers, StoredIQ Event Sinks, etc.) designed to provide objects and object data to an ingest queue 520 where objects to be processed by Classification Pipeline 300 are organized. Ingest queue 520 may be operable to implement an API 515 such that information on objects may be provided to ingest queue 520 . For example, if applications 510 which may be provided in conjunction with Classification Pipeline 300 only cover a certain set of filesystems, the “external” API 515 may allow objects in a filesystem outside the set of filesystems to be classified by Classification Pipeline 300 by passing information on the object, or the object itself, to ingest queue 520 . This information on an object or the object may be passed in by a third party application or any other application that wishes to utilize the capabilities of Classification Pipeline 300 .
[0108] From ingest queue 520 objects are then processed by Classification Pipeline 300 . The processing of these objects may lead to one or more pipeline events 530 . These pipeline events may be the fact that an object has been classified a certain way, that certain metadata of an object comports with certain criteria, etc. Based on the pipeline events generated, metadata or other object data may be stored to a repository 540 and/or utilized to implement policies 550 and/or inform applications (e.g., a Web application external to Classification Pipeline 300 ) through API 535 . Policies may be actions to be taken and may for example be based upon the classification of an object. These policies may be either predefined or user defined, such that system 500 may take user-defined actions based upon a pipeline event. These pipeline events or other results of processing by Classification Pipeline 300 may also be reported using API 535 as discussed above, such that client applications may receive requested information on objects that have been processed by Classification Pipeline 300 .
[0109] FIG. 6 depicts one embodiment of an exemplary architecture for the implementation of a system 600 for processing objects using a cluster of classification pipelines disclosed herein. Filesystems (e.g., CIFS 662 , NFS 664 , Netware 666 in a network Filesystem environment 660 ) may be accessed by various applications (e.g., Filesystem Walkers 611 , Real Time Event Sinks 613 ) to obtain objects as well as information on objects in these filesystems and events pertaining to these systems. These applications may place these events and information into a pipeline queue (e.g., Ingest Queue 620 ) which is managed by a queue manager (e.g., Ingest Queue Manager 628 ). Additionally, an external interface (e.g., API 605 ) may allow external applications (e.g., Applications 601 ) to provide information on objects in external filesystems to the pipeline queue.
[0110] From this queue (e.g., Ingest Queue 620 ), the queue manager (e.g., Ingest Queue Manager 628 ) may distribute objects to computer nodes (e.g., nodes 682 , 684 , 686 ), each which is operable to implement one or more instances of a classification pipeline (e.g., Classification Pipeline 300 ), or a subset thereof. Thus, each of the objects in the queue may be processed by an instance of a classification pipeline implemented on a node. The processing of these objects by the instances of the classification pipeline on the various nodes results in the generation of various pipeline events (e.g., Pipeline Events 630 ). The pipeline events may result in the various actions taken by volume subscribers (e.g., Volume Subscribers 690 ) based upon the volume with which the object that caused a pipeline event to be generated is associated. Thus, if a pipeline event was generated based upon an object in a certain volume, the pipeline event, object metadata or other information associated with the object may be stored in a repository or storage location (e.g., Repository 640 ). Additionally, the pipeline event, object metadata or other information associated with the object may implement some predefined policies (e.g., Policies 640 ) and/or be reported to external applications through an external interface (e.g., API 625 ), as described above.
[0111] It will be apparent from the above descriptions that many other architectural arrangements may be implemented and utilized in conjunction with embodiments of the classification pipeline disclosed herein.
[0112] Although the present invention has been described in detail herein with reference to the illustrative embodiments, it should be understood that the description is by way of example only and not to be construed in a limiting sense. It is to be further understood, therefore, that numerous changes in the details of the embodiments of this invention and additional embodiments of this invention will be apparent to, and may be made by, persons of ordinary skill in the art having reference to this description. Accordingly, the scope of the invention should be determined by the following claims and their legal equivalents. | 4y
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an improvement in the intermediate transfer body of a transfer type recording apparatus such as transfer type electrophotographic copying machine.
2. Description of the Prior Art
FIG. 1 shows the intermediate transfer body 1 of a transfer type recording apparatus. Typical conventional intermediate transfer body used hitherto includes a substrate made of a metal such as a stainless steel or a resin, e.g. polyimide, polyester or the like and an intermediate transfer layer made of a material such as fluoro-carbon rubber, e.g. TEFLON manufactured by Du Pont, silicone rubber or the like formed on the substrate.
Besides the intermediate transfer body 1 having the form of an endless belt, the copying machine has a drive roller 2 for driving the intermediate transfer body 1, a heat source 3 incorporated in the drive roller 2, a tension roller 4 for imparting a tension to the intermediate transfer body 1, a pressure roller 5 for pressing the surface of the intermediate transfer body 1 against the surface of a photosensitive drum 6 as a toner image retaining member, a charging device 7, a projection device for projecting light 8, a developing device 9, a charge eliminating device 10, a cleaning device 11, a pressure conveyor roller 12 for pressing a recording paper 13 onto the surface of the intermediate transfer body 1 and feed the same in cooperation with the heated drive roller 2, and a conveyor roller 14 for conveying the recording paper 13.
In operation, the photosensitive drum 6 is rotated in the direction of the arrow so that the surface thereof is electrostatically charged uniformly. An electrostatic latent image formed on the charged surface as the light 8 is projected onto the charged surface. The latent image is then developed by the developing device 9. When the developed toner image 15 reaches the position of the pressure roller 5, it is transferred to the surface of the intermediate transfer body 1 and the transferred toner image 15' is further transferred to the recording paper 13 as the same is brought to the position of the pressure conveyor roller 12 as a result of movement of the intermediate transfer body 1 in the direction of the arrow.
The transferred image is then fixed on the recording paper 13 by the heat from the drive roller 2 to become a fixed toner image 15". In the above case, it is possible to heat the pressure conveyor roller 12 and the drive roller 2 as heating roller.
In this recording apparatus, the following disadvantages (1) to (4) are brought about by the use of the intermediate transfer body 1 having a metallic substrate.
(1) Since the metallic substrate exhibits a high rigidity, the intermediate transfer body 1 exhibits only a small adherence to the photosensitive drum 6 and the recording paper 13. As a result, the efficiency of the transfer of the image, particularly the image transfer from the photosensitive drum 6, is lowered seriously. To obviate this problem, it has been necessary to increase the contact pressure of the pressure roller 5.
(2) Due to the high thermal conductivity of the metallic substrate, the heat is transmitted to other portion than the pressure conveyor roller 12 so that the thermal efficiency of the heat source 3 is lowered and the temperature in the apparatus is raised undesirably.
(3) The fluoro-carbon rubber, silicone rubber or the like material constituting the surface of the intermediate transfer body exhibits only a small strength of bonding to the substrate.
(4) It is difficult to obtain the intermediate transfer body in the form of an endless belt.
It is possible to obtain higher bonding strength by using a high molecule resin such as polyimide, polyester or the like as the material of the substrate of intermediate transfer body 1 than that exhibited when the substrate is made of a metal. However, the thermosetting resin such as polyimide can provide only a small productivity because, in such a case, the intermediate transfer body is formed by a batch type method employing a mould. In addition, the intermediate transfer body made of a thermosetting resin exhibits a small adherence to the photosensitive drum 6 and to the recording paper 13. On the other hand, the intermediate transfer body having a substrate made of a thermoplastic resin such as polyester can be produced at a higher productivity than that having substrate made of a metal or even that having a substrate made of a thermosetting resin. In addition, it is easy to produce an intermediate transfer body in the form of an endless belt and, in addition, a superior adherence to the photosensitive drum 6 and the recording paper 13 is attained. Unfortunately, however, the intermediate transfer body having a substrate made of a thermoplastic resin exhibits inferior physical properties at high temperature in the fixing of the toner image.
SUMMARY OF THE INVENTION
Accordingly, an object of the invention is to provide an intermediate transfer body capable of overcoming the above-described problems of the prior art.
To this end, according to the invention, there is provided an intermediate transfer body comprising a substrate having a thermoplastic resin layer and a thermosetting resin layer.
The above and other objects, features and advantages of the invention will become clear from the following description of the preferred embodiment taken in conjunction with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustration of a transfer type recording apparatus;
FIG. 2 is a sectional view of an intermediate transfer body in the form of an endless belt, in accordance with an embodiment of the invention; and
FIG. 3 is a sectional view of an intermediate transfer body in accordance with another embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 2 and 3, a symbol P represents a layer of a thermoplastic resin, S represents a layer of a thermosetting resin and G represents an intermediate transfer layer made of a fluoro-carbon rubber, silicone rubber or the like material and constituting a surface layer independent from the resin layers P and S. As shown in FIG. 2, according to the invention, the thermosetting resin layer S constituting the surface of the substrate may be used as the intermediate transfer layer or, alternatively, the thermoplastic resin layer P and the thermosetting resin layer S shown in FIG. 2 may be replaced with each other to permit the use of the thermoplastic resin layer P as the intermediate transfer layer. It is also possible to sandwich the thermoplastic layer P between two thermosetting resin layers S and to use one of the thermosetting resin layers S as the intermediate transfer layer. According to the invention, however, it is preferred to use an intermediate transfer layer G independently of the thermoplastic resin layer P and the thermosetting resin layer S as shown in FIG. 3, because the use of the intermediate transfer layer G independent from the resin layers S and P permits the selection of the kinds of resin layers P and S without taking into account the transfer efficiency. The free selection of the kinds of resins advantageously affords the improvement in the productivity, heat resistance and durability.
The positions of the thermoplastic resin layer P and thermosetting resin layer S may be replaced with each other or the thermoplastic resin layer P may be sandwiched between two thermosetting resin layers S also in the embodiment shown in FIG. 3 as explained in the case of the embodiment shown in FIG. 2. FIG. 3 shows that the intermediate transfer body of the invention can be used not only in the form of an endless belt but also in the form of a planar form.
According to the invention, it is possible to use, as the material of the thermoplastic resin layer P constituting the substrate, various resins such as polyester, polyethylene, polypropylene, polystyrene, polyamide, polyacetal, polycarbonate, polysulfone, polyarylsulfone, polyurea, fluoro-carbon resin and so forth solely or in the form of a blend or copolymer. On the other hand, the thermosetting resin layer S may be formed of a phenol resin, urea resin, melamine resin, xylene resin, diallylphthalate resin, epoxy resin, polyimide, polyimideamide, polydiphenylether, and polybenzimidazole solely or as a compound.
The thermoplastic resin layer is formed as a sheet by a known method in which the material is molten and extracted from a slit, while the thermosetting resin layer is formed by applying the resin liquid onto the surface of the thermoplastic resin and then drying and baking the liquid, thereby to form a sheet consisting of the thermoplastic resin layer P and the thermosetting resin layer S. The intermediate transfer body shown in FIG. 2 is formed by connecting opposite ends of the above-mentioned sheet into the form of an endless belt. The intermediate transfer layer G may be formed by applying an emulsion of fluoro-carbon rubber or silicone rubber on the surface of the thermoplastic resin layer P or the thermosetting resin layer S of the sheet and then drying and baking the emulsion, thereby to form the intermediate transfer body as shown in FIG. 3.
The application of the thermosetting resin liquid and the fluoro-carbon rubber emulsion or the like can be made by any known method such as dipping, spraying, doctor blade method, bar coat method, slide hopper method and so forth.
The intermediate transfer body of the invention has a construction as explained above. The thermoplastic resin layer P as the substrate improves the productivity of the intermediate transfer body in the form of a sheet or endless belt and, in addition, improves the adherence to the photosensitive drum 6 or the recording paper 13 as shown in FIG. 1. On the other hand, the thermosetting resin layer S improves the heat resistance and durability of the intermediate transfer body. It is thus possible to obtain an intermediate transfer body having superior performance and capable of eliminating the problem inherent in the conventional intermediate transfer body having a substrate made of a metal or the high molecule resin.
The invention will now be fully described hereinunder through specific examples.
EXAMPLE 1
A polyethylene terephthalate sheet of 50μ thick was formed by discharging the material in molten state, drawing and then heat treating the same. An epoxy resin liquid consisting of 75 weight parts of EPIKOTE 828 (produced by Shell Petrochemical Industry) and 25 weight parts of DDM was applied on one surface of the polyethylene terephthalate sheet by means of a doctor blade. The sheet applied with the epoxy resin liquid was subjected to drying and baking conducted for 1 hour at 100° C. and for 5 hours at 125° C., respectively, to form an epoxy resin layer of 25μ thick on the polyethylene terephthalate layer. Meanwhile, a dope was prepared by mixing 100 weight parts of a silicone rubber of self-bonding and addition polymerization type (KE1800 produced by Shinetsu Kagaku K.K., containing suitable amount of filler) and 100 weight parts of toluene, and permitting the mixture to foam sufficiently. The dope was applied to the surface of the epoxy resin layer on the sheet by a doctor blade and, after drying, a baking was conducted for 30 minutes at 150° C. to form a silicone rubber layer of 50μ thick to obtain a laminated sheet having three layers of a total thickness of 150μ. The silicone rubber layer was peeled off over a width of 20 mm along one end of the sheet to reveal the epoxy resin layer to which applied thinly was an adhesive (PRIMER KE41 of Shinetsu Kagaku K.K.). The terephthalate resin layer on the other end of the sheet was then superposed to the epoxy resin layer applied with the adhesive and was left for 24 hours under application of a pressure to obtain an intermediate transfer body in the form of an endless belt.
The intermediate transfer body thus obtained was put into an actual use as the intermediate transfer body 1 shown in FIG. 1 to transfer and fix the toner image on successive 5000 sheets of recording paper 13. Copy images of high contrast and resolution and devoid of any defect were obtained to the final sheet. It was thus confirmed that the intermediate transfer body 1 can carry the toner image in quite a stable manner.
EXAMPLE 2
A U-sheet polyacrylate resin (manufactured by Taihei Chemical Co., Ltd.) was extracted from a circular slit to form an endless belt of 50μ thick. A mixture liquid was prepared by mixing 100 weight parts of a polyimide resin (TORAYNEECE #2000 produced by Toray) and 30 g of solvent of above-mentioned polyimide resin consisting mainly of N-methyl-2 pyrrolidone and containing N,N-dimethylacetamide. The mixture liquid was applied to the belt surface by spraying. The belt was then subjected to a drying conducted for 2 hours at 150° C. and then to a baking conducted for 4 hours at 180° C. to form a polyimide resin layer of 30μ thick to become a laminated sheet having two layers. The surface of the polyimide resin layer of this sheet was beforehand treated with a primer (PRIMER T produced by Shinetsu Kagaku K.K.). A liquid was prepared from 100 weight parts of silicone rubber (KE1300, room temperature vulcanization curing type, produced by Shinetsu Kagaku K.K.), 150 weight parts of toluene and 100 weight parts of kerosene. The liquid was then applied by spraying to the polyimide resin layer surface. The sheet was then subjected to a drying heat treatment conducted for 2 hours at 150° C. to form an intermediate transfer body having an intermediate transfer layer of silicone rubber.
The intermediate transfer body thus produced was put into an actual use as the intermediate transfer body 1 shown in FIG. 1 to make copies on successive 10000 sheets of recording paper 13. Copy images of high contrast and resolution and devoid of any defect were obtained as in the case of Example 1. In consequence, it was confirmed that the intermediate transfer body 1 of this example can carry the toner image in quite a stable manner. | 4y
|
BACKGROUND OF THE INVENTION
In olefin polymerizations, the polymer melt flow is controlled by varying the hydrogen/propylene ratios in the reactor. At present, changes in polymer melt flow are accomplished by changing the hydrogen concentrations in the reactor. Traditionally, melt flow transitions from low melt flow to high melt flow were accomplished by, quickly adding hydrogen into the reactor. Similarly, to achieve a melt flow transition from high melt flow to low melt flow, extensive venting of the reactor has been traditionally required to reduce the hydrogen concentration of the material contained in the reactor. This venting of the reactor to obtain hydrogen concentrations at the desired level can take many hours and cause expensive production delays. For example, using conventional melt flow transition techniques and propylene as the polyolefin in the polymerization reaction, to reduce melt flow from high to low, venting of the reactor can require up to 40 hours at a vent rate of 6000 lbs/hr propylene to reduce melt flow from 50 to 3.
Transition from a higher melt flow to a lower one is dependent upon reactor residence time, reactor design, and the magnitude of the change in the melt flow value. The time to effect a high melt flow to low melt transition by venting can vary from minutes to many hours depending upon the three above-noted parameters. To overcome this extremely costly method which has a tendency to cause production delays, a novel process for adjusting polymer melt flow from high to low has been developed. Practice of this novel invention results in a high melt flow to low melt flow transition time which takes less than about 50% and even as little as about 10% to about 1% of the conventional transition time previously required for conventional venting.
SUMMARY OF THE INVENTION
A process for polymerizing a member of the group consisting of an alpha olefin or mixtures thereof, consisting of the steps of:
polymerizing an alpha olefin in a polymerization reactor using a polymerization catalyst, a cocatalyst, and an amount of hydrogen adjusted for molecular weight control as measured by melt flow;
rapidly changing the melt flow of the polymerized alpha olefin from high to low melt flow by reacting a portion of the unreacted hydrogen in the reactor with a quantity of the alpha olefin present therein by interaction with a hydrogenation catalyst; and
removing the hydrogenation catalyst from the reactor through continuous exchange of the reactor contents.
DESCRIPTION OF THE INVENTION
The novel process can use an alpha olefin such as propylene, butene, hexene, octene, ethylene, polyethylene or other linear or branched alpha olefins. The polymerization of the alpha olefin can preferably occur at a temperature in the range between 20° C. and 160° C., although for certain alpha olefins, a temperature range between 40° C. and 120° C. can be used. Low temperature polymerization between 60° C. and 90° C., can also be performed and the novel advantage of the present invention can be obtained.
In the inventive process, the polymerization catalyst can be an unsupported catalyst for olefin polymerization. This unsupported catalyst can contain titanium, chromium, vanadium, zirconium, cobalt or a mixture thereof. Titanium halide is an unsupported catalyst usable within the scope of the present invention.
Alternatively, it is possible to carry out the present invention using a supported catalyst such as a polymerization catalyst on a support of a magnesium halide. Magnesium chloride is a preferred magnesium halide support. The support for a polymerization catalyst useful within the scope of the present invention can be either a titanium halide, a silica, a magnesia, an alumina, a mixed metal oxide, a non-chemically reactive organic polymer or a non-chemically reactive inorganic polymer. The preferred titanium halide support is titanium chloride. Other supported catalysts usable within the present invention include chromium, vanadium, zirconium and cobalt containing supported catalyst. Supported catalysts which are mixtures of titanium, chromium, vanadium, zirconium and cobalt supported catalysts are also usable within the scope of the present invention.
The cocatalyst usable within the scope of the inventive process can be either a metal alkyl, a metal alkyl alkoxide, a metal alkyl halide, a metal alkyl hydride or mixtures thereof.
A selectivity control agent can be used in the inventive process. Aromatic esters, amines, hindered amines, esters, phosphites, phosphates, aromatic diesters, alkoxy silanes, aryloxy silanes, silanes, hindered phenols and mixtures thereof may be useful as the selectivity control agent in the inventive process.
The present invention provides a novel process for polymerizing alpha olefins by eliminating the costly traditional method of changing melt flow of the reactor contents during polymerization from high to low by venting. The present inventive process reduces the hydrogen concentrations in the reactor contents containing alpha olefins to a level wherein the reactor contents have the desired melt flow index in less time than is currently required by conventional procedures. This novel method involves reacting the hydrogen with an alpha olefin, such as propylene in the reactor using a novel catalyst system.
The novel polymerization or copolymerization of the alpha olefin preferably occurs in the range of 20° C. to 160° C., for the polymerization or copolymerization of higher olefins, such as poly-4-methyl-1 pentene and hexene, and decene. It is also possible to polymerize or copolymerize alpha olefins in the novel process using temperatures in the range of 40° C.-120° C., when olefins such as 1-butene are used. Use of this more narrow temperature range with olefins like 1-butene in the novel process provide a product with certain desirable isotacticities. In this process it is possible to polymerize or copolymerize an alpha olefin such a propylene in the range of 60° C.-90° C. and obtain the desired results. In another embodiment of the present invention, the reactor can be heated to temperatures in the range of about 25° C. to about 100° C. which facilitates polymerization.
Given the above parameters, polymerization or copolymerization of the alpha olefin can be carried out by known alpha olefin polymerization processes.
The reactor usable in the present invention can be either a liquid phase reactor a gas phase reactor, a solvent slurry reactor or a or a solution polymerization reactor. These kind of reactors have been described in U.S. Pat. Nos. 3,652,527, 3,912,701, 3,922,322, 3,428,619, 3,110,707 and 3,658,780 and reference to these types of reactors is incorporated herewith.
During polymerization or copolymerization, such as by the above described process, it has been discovered that the catalytic reduction of the hydrogen to carry out the transition from high to low melt flow can be performed by direct injection of one of the several hydrogenation catalysts into the polymerization or copolymerization reactor. Hydrogenation catalysts useful for olefin hydrogenation, including nickel, platinum, palladium catalysts are preferred for use in this inventive process. A more extensive list of hydrogenation catalysts usable within the present invention follows.
It is preferred to minimize the deleterious effects that the hydrogenation catalyst will have on the polymerization catalyst activity and on polymer quality when the novel process using direct injection of the hydrogenation catalyst approach is carried out. The hydrogenation catalyst can be in a carrier of hydrocarbon solvent, such as toluene, prior to direct injection of the catalyst into the reactor.
Alternatively, it has been discovered that catalytic reduction of the hydrogen can be carried out outside the polymerization reactor by circulating the reactor contents or part of the reactor contents through a fixed, external catalytic bed containing a hydrogenation catalyst, such as the nickel hydrogenation catalyst. An advantage of the external fixed bed system is that it is not necessary to deactivate or remove the hydrogenation catalyst from the fixed bed following the catalytic reduction of the hydrogen concentration, thus potentially saving even more money and steps in polymerization or copolymerization reactions.
In the novel process, the hydrogen concentration of the reactor contents can be adjusted to be in the range of about 0.01 mole percent to about 20 mole percent to provide a melt flow of polymerized product between about 0.01 and 2,000 dg/min. The novel process can be used to adjust the hydrogen concentration of the reactor contents such that the melt flow of polymerized product is between about 0.1 to about 1,000 dg/min and in some cases between about 0.1 to about 700 dg/min.
The hydrogenation catalysts useful to obtain the fast reduction in transition time from high melt flow to low melt flow can be a transition metal catalyst useful for the hydrogenation of alpha olefins (such as benzenetricabonylchromium, dibenzenechromium, dihydridochlorotris(triphenylphosphine iridium (III), hydridodichlorotirs(triphenylphosphine)iridium (III) and dicarbonylcyclopentadienylcobalt). When a transition metal catalyst is used as the hydrogenation catalyst, a preferred catalyst of this type is a supported nickel catalyst. Supported platinum catalyst and supported palladium catalyst can also be used within the scope of this invention. It is preferred to use transition metal catalysts supported on either alumina, silica, carbon or carborundum.
The most preferred nickel catalyst usable within the scope of the present invention is bis-1,5-cyclooctadiene nickel. Nickel octanoate is another preferred nickel catalyst usable within the scope of the present invention.
When the hydrogenation catalyst is directly added to the reactor, the preferred amount of hydrogenation catalyst, in parts per million can extend from about 0.01 to about 3,000 parts per million down to 0.01 to 100 parts per million. Between 1 to about 20 parts per million of hydrogenation catalyst has been found useful within the scope of the present invention depending on which hydrogenation catalyst is used in the polymerization. In the most preferred embodiment of the present invention, using the bis-1,5-cyclooctadiene nickel between about 5 to about 15 parts per million of the nickel catalyst can be added to the reactor to provide the desired results.
Other hydrogenation catalysts that may be effective within the scope of the present invention, include other nickel hydrogenation catalysts, nickel in graphite, such as graphimet Ni-10; palladium in graphite such as graphimet Pd-1; benzenetricarbonylchromium, C 6 H 6 Cr (CO) 3 ; dibenzenechromium, (C 6 H 6 ) 2 Cr; dicarbonylcyclopentadienylcobalt, (C 5 H 5 )Co(CO) 2 ; dihydridochlorotris(triphenylphosphine) iridium (III), Ir(H 2 )Cl[P(C 6 H 5 ) 3 ] 3 ; hydridodichlorotris(triphenylphosphine)iridium (III), Ir(H)Cl 2 [P(C 6 H . . . ; bis(1,5-cyclooctadiene)nickel, (CH 8 H 12 ) 2 Ni; bis(cyclopentadienyl)nickel, dry, Ni(C 5 H 5 ) 2 ; tetrakis(diethylphenylphosphonite)nickel, [C 6 H 5 P(OC 2 H 5 ) 2 ] 4 Ni; tetrakis(methyldiphenylphosphine)nickel, [(C 6 H 5 ) 2 PCH 3 ] 4 Ni; tetrakis(triethylphosphine)nickel, [(C 2 H 5 ) 3 P] 4 Ni; tetrakis(triphenylphosphine)nickel, [(C 6 H 5 ) 3 P] 4 Ni; tetrakis(trifluorophosphine)nickel, (PF 3 ) 4 Ni; tetrakis(triphenylphosphine)palladium, Pd[(C 6 H 5 ) 3 P] 4 ; bis(triphenylphosphine)platinum(II) chloride, PtCl 2 [(C 6 H 5 ) 3 P] 2 ; dichloro(cycloocta-1,5-diene)platinum(II), Pt(C 8 H 12 )Cl 2 ; tetrakis(triphenylphosphine)platinum, Pt[(C 6 H 5 ) 3 P] 4 chloro(norbornadiene)rhodium(I) dimer, [RhCl(C 7 H 8 )] 2 ; dihydridotetrakis(triphenylphosphine)ruthenium(II), [(C 6 H 5 ) 3 P] 4 RuH 3 ; potassium hexachlororuthenate(IV), K 2 RuCl 6 ; and tris(triphenylphosphine)ruthenium(II) chloride, [(C 6 H 5 ) 3 P] 3 RuCl 2 .
A nickel catalyst is the preferred catalyst within the scope of the present invention since it is both insensitive to the presence of tri-ethyl aluminum (TEA), PEEB and Si(OR) x (R') 4-x wherein 0<x≦4, but capable of being poisoned by reagents containing reactive chloride. Sensitivity to active chloride or water can serve to limit the life of such a hydrogenation catalyst in the reactor, especially when the catalyst contains a transition metal olefin polymerization catalyst containing titanium, chromium, vanadium, zirconium or cobalt. Poisoning of the hydrogenation catalyst can permit continuation of the polymerization reaction at the desired lower polymer melt flow without further loss of hydrogen (H 2 ). Additionally, hydrogenation catalysts such as nickel octanoate can be used in the novel process since they are easily poisoned by compounds such as, di-ethyl aluminum chloride (DEAC), and thereby provide a reaction wherein the hydrogen consumption can be controlled. Hydrogenation catalysts which are supported transition metal catalysts, supported on a component consisting of alumina, silica, clay, carbon, layered clay, are also effective.
In the above described direct injection process, it has been found that removal of the hydrogenation catalyst from the reactor or deactivation of the hydrogenation catalyst once the hydrogen concentration is reduced to the desired level is very helpful to achieve good polymerization and copolymerization results. Another process for deactivating hydrogenation catalysts involves poisoning the hydrogenation catalyst in the reactor by adding a reactive chlorine containing compound, such as DEAC, (diethyl aluminum chloride), silicon tetrachloride, ethyl aluminum dichloride, chlorine gas or combination thereof to the reactor to stop any unwanted consumption of hydrogen after the desired level of hydrogen concentration is achieved. In a continuous polymerization or copolymerization process, the depletion or removal of the hydrogenation catalyst can be achieved by gradually exchanging the reactor contents.
The present invention can be carried out in a variety of reactors such as gas phase reactors, liquid phase reactors, solvent slurry reactors or solution reactors, to achieve the novel rapid transition time of polymer product from high melt flow to low melt flow is less than 50% of the conventional transition time for reducing melt flow of product. It has been found that the novel process can reduce high to low melt flow transition time as much as 1% to 10% of the transition time traditionally required.
EXAMPLE 1
To a one (1) gallon polymerization reactor, 2700 cc of liquid propylene was added. The liquid propylene was initially maintained at ambient temperature, 20°-24° C. in the reactor. The reactor was then heated to about 60° C. and hydrogen gas was directly injected into the reactor. Hydrogen was injected into the reactor in an amount to establish an initial liquid phase concentration of hydrogen in the reactor at about 0.15% mol. About 0.14 mmole of diphenyl dimethoxy silane, 0.56 mmole of triethylaluminum and 0.008 mmole titanium equivalent of a polymerization catalyst were added to the reactor. The temperature in the reactor was then allowed to increase to 67° C.
For 20-30 minutes, additional hydrogen was directly added to the reactor until a liquid phase concentration of hydrogen, of around 0.5% mol was obtained. A nickel containing solution was added to the reactor, to a level of 4 ppm Ni (basis--total weight of reactor contents). The nickel solution contained nickel octanoate, cyclohexane and triethyl aluminum (TEA), (TEA stabilized the solution). Immediately following the addition of the nickel solution a temperature exotherm occurred, between about 2° and 4° C. indicating a significant increase in energy being evolved from the reactor. Gas chromatographic analysis of the nonpolymerized liquid contents indicated that an immediate reduction in hydrogen concentration occurred.
After 25 minutes, the hydrogen concentrations were reduced, essentially to zero. A substantial increase in molecular weight of the product formed after the initial injection of the nickel solution (containing nickel hydrogenation catalyst) was confined by gel permeation chromatography. The final yield was about 1.08 million grams polypropylene per gram titanium, indicating no significant loss in catalyst performance.
EXAMPLE 2
The novel control of hydrogen during melt flow transition in an alpha olefin polymerization reaction was tested in a continuous gas phase reactor. During normal operation, the reactor was continuously fed with propylene, a Ti supported Shell Shac® catalyst (Shell high activity catalyst) with an aluminum alkyl as cocatalyst, a selectivity control agent (SCA) and hydrogen to maintain a desired but high polymer melt flow.
The experiment started by first establishing a base line for hydrogen consumption during the reaction. This base line was established by stopping the catalyst/cocatalyst, SCA and hydrogen flows and blocking the reactor vent. The hydrogen concentration in the reactor was monitored by Gas Chromatography (GC). The GC analysis showed that the hydrogen concentration was reduced from 2.8% mole to 2.1% mole after 1.5 hours. This change in rate suggests that under normal polymerization, hydrogen is being consumed or lost at a rate of 0.008%/min.
EXAMPLE 3
The process described in Example 2 was repeated, however, instead of stopping the catalyst and cocatalyst feed as well as the hydrogen feed, the polymerization reaction was maintained as a continuous flow. A steady state of hydrogen concentration was maintained by continuously feeding hydrogen into the reactor. When a steady reactor operation was achieved, the hydrogen feed and the reactor vent were shut down and the "initial" hydrogen concentration was recorded as shown in Table 1. This was followed with an injection of the hydrogenation catalyst (bis 1,5-cyclooctadiene Ni(O) stabilized with aluminum alkyl). The catalyst was injected into the reactor in a single shot to achieve a calculated value of 5 ppm Ni (basis--the polymer weight in the reactor bed). During this process the polymer production was maintained at a constant rate by continuously feeding propylene catalyst, cocatalyst and the selectivity control agent into the reactor. The changes in the hydrogen concentrations were monitored by GC. The experimental data is summarized in Table 1.
EXAMPLE 4
The process described in Example 2 was repeated with the injection of same the hydrogenation catalyst but at a 10 ppm Ni concentration (basis--the polymer weight in the reactor bed). This data is summarized in Table 2.
EXAMPLE 5
The process described in Example 3 was repeated with the injection of the same hydrogenation catalyst but at 15 ppm Ni concentration (basis--the polymer weight in the reactor bed). This data is summarized in Table 3.
The data summarized in Table 4 shows that the injection of the hydrogenation catalyst had no deleterious effect on the polymerization catalyst performance. The lower than theoretical levels of Ni in the polymer appears to be due to the normal polymer bed exchange that occurs during the polymerization reaction.
TABLE 1______________________________________Hydrogen Control(Injection of 5 ppm (Ni) Catalyst)1 Time 2 Bed 3 InletMins Temp °C. Temp °C. 4 Mol H.sub.2 % 5 Mol C.sub.3 H.sub.8 %______________________________________0 65.0 61.0 5.270 1.0145 65.8 60.5 5.080 1.02610 64.0 59.5 4.500 1.02615 63.5 59.5 4.280 1.50720 65.5 60.2 4.140 1.50725 65.3 60.3 3.850 1.73230 65.0 60.1 3.850 1.86135 65.1 60.0 3.700 1.86140 65.7 60.0 3.700 1.95545 65.2 59.5 3.550 2.01950 64.5 59.5 3.460 2.01955 64.0 59.5 3.460 2.09660 65.1 59.0 3.360 2.09670 65.0 59.7 3.040 2.13780 64.5 60.1 3.000 2.11590 65.5 60.0 2.930 2.119100 64.0 60.0 2.850 2.180110 64.8 60.0 2.790 2.204120 65.0 60.3 2.790 2.175______________________________________
TABLE 2______________________________________Hydrogen Control(Injection of 10 ppm (Ni) Catalyst)1 Time 2 Bed 3 InletMins Temp °C. Temp °C. 4 Mol H.sub.2 % 5 Mol C.sub.3 H.sub.8 %______________________________________0 65.6 60.5 4.890 0.9955 66.5 58.5 4.890 0.99510 64.8 59.3 4.890 0.97115 65.0 59.5 4.890 0.97120 65.3 59.3 4.190 1.50025 64.8 59.5 3.410 2.05030 65.0 60.0 3.410 2.05035 65.6 59.7 3.030 2.42040 65.2 59.3 3.030 2.42045 64.9 59.8 2.760 2.60050 65.1 59.9 2.570 2.69055 65.5 59.6 2.570 2.69060 65.4 59.5 2.370 2.79070 64.9 59.8 2.370 2.79080 65.6 58.8 2.160 2.86090 64.6 60.2 1.970 2.840100 65.6 59.8 1.970 2.890110 64.9 60.3 1.920 2.860120 65.5 59.5 1.850 2.910______________________________________
TABLE 3______________________________________Hydrogen Control(Injection of 15 ppm (Ni) Catalyst)1 Time 2 Bed 3 InletMins Temp °C. Temp °C. 4 Mol H.sub.2 % 5 Mol C.sub.3 H.sub.8 %______________________________________0 65.0 60.5 3.340 1.0605 65.2 58.9 3.270 1.05310 64.8 58.0 1.960 2.18715 64.2 58.0 1.960 2.18720 63.5 58.0 1.430 2.66825 63.0 58.2 1.430 2.66830 64.8 60.5 1.100 2.96235 65.1 60.6 1.100 2.96240 65.0 60.8 0.881 2.96945 66.0 60.8 0.686 2.96450 65.1 60.0 0.686 2.96455 65.0 60.0 0.605 3.05560 64.9 59.8 0.605 3.05570 64.9 60.1 0.469 3.14680 65.2 60.0 0.444 3.17390 64.9 60.0 0.398 3.168100 64.9 60.0 0.369 3.175110 65.0 60.2 0.344 3.125120 65.3 60.4 0.283 3.007______________________________________
TABLE 4______________________________________Hydrogen Control(Product Analysis) Ni Catalyst Total Ni Injection.sup.(1) Total In PolymerRun # (ppm) Ti (ppm) XS.sup.(2) Ash (ppm) (ppm)______________________________________1 5 2.7 5.1 150 2.02 10 2.4 4.6 210 2.13 15 2.7 4.25 290 4.9______________________________________ .sup.(1) Basis reactor polymer bed weight. .sup.(2) % wt xylene solubles. | 4y
|
BACKGROUND OF THE INVENTION
This invention concerns an anti-theft lock for attachment to a steering wheel of an automobile, particularly one using a remote controller of an electronic alarm set for locking and unlocking this lock, without using a key.
Nowadays many kinds of anti-theft locks are used in automobiles, but they are generally unlocked by a key, therefore, they are liable to be pried open by smart thieves.
SUMMARY OF THE INVENTION
A main object of this invention is to offer a kind of automobile mobile steering lock using a remote controller instead of a key in locking and unlocking the lock.
A main feature of the present invention is a motor disposed in an inner half housing, the motor having a semiround activating block fixed at top of a shaft, and a block is fitted in a flat recess of a deadbolt, with the motor being connected to an electronic alarm set so that the motor can be turned on or off by a remote controller of the electronic alarm set to rotate the activating block 180 degrees to push up or pull down the deadbolt for locking or unlocking this lock.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is an exploded perspective view of an automobile steering lock in the present invention.
FIG. 2 is a perspective view of the automobile steering lock in the present invention.
FIG. 3 is a cross-sectional view of the automobile steering lock in the present invention, showing it in a closed or locked condition.
FIG. 4 is a cross-sectional view of the automobile steering lock in the present invention, showing it in an open or unlocked condition.
FIG. 5 is a perspective view of the automobile steering lock in the present invention, showing it applied on the steering wheel of an automobile.
DETAILED DESCRIPTION OF THE INVENTION
An automobile steering lock in the present invention, as shown in FIG. 1, comprises an inner half housing 1, an outer half housing 2, a stop member 3, an elongate rod 4, a head bolt 5, a motor 6, an electronic alarm set 7 and a cap 8 as main components combined together.
The inner half housing 1 has a block portion 16, a length-wise passageway 10 in an upper section of the block portion 16, a stop edge 100 of a small size, a chamber 11 formed in a rear end of the passageway 10, a motor hole 12 in parallel to the passageway 10 in the lower section of the block portion 16, a cover annular edge formed in an outer end of the motor hole 12 for a cover 63 to fit therein, a vertical deadbolt hole 13 provided in the lower section and communicating with the passageway 10 and the motor hole 12, an outer annular edge 130 in the deadbolt hole 13 for a cover 55 to fit therein, two vertical bolt holes 14, 14 are provided in the bottom of a rear end of the block portion 16 for a pair of bolts, to fit upwardly therethrough, and a curved semiround portion 15 formed to abut at a right angle on the block portion 16 and able to fit around an outer surface of a portion of the steering wheel of an automobile.
The outer half housing 2 has a curved semiround portion 20, a vertical wall 21 extending up from a center section of the semi-round portion 20, a locking rod 22 extending horizontally inward from an upper end of the vertical wall 21 and having a plurality of straight transverse grooves 23 in a bottom surface, an annular groove 24 in the end of the locking rod 22, and each of the grooves 23 having a sloped face 231 and a vertical face 230 adjacent each other. The curved semiround portion 15 and 20 fit around outer and inner surfaces of a portion of the steering wheel of an automobile so that the two half housings 1 and 2 may surround the portion of the steering wheel in locking engagement therewith.
The stop member 3 is shaped as a rectangular ring, having an aperture 31 in one side and a large center hole for engaging annular groove 24.
The elongate rod 4 has two bolt holes 42, 42 in the front end for the bolts 14, 14 to fit upwardly therethrough so as to fit through the bolt holes 14, 14 in the inner half housing 1 to combine the rod 4 with the half semiround housing 1, a recess 40 in a front end face for disposing a spring 41 therein, a cord hole 43 in the front bottom, a chamber 44 with an upper opening in a rear portion, and a cord hole 440 in a front wall of the chamber 44.
The deadbolt 5 is to be disposed in the vertical deadbolt hole 13 of the block portion 16 of the inner half housing 1, and has a sloped face 50 and a vertical face 51 at its upper end formed to selectively engage any of grooves 23, a flat recess 52 cut in an intermediate portion, a spring recess 53 in a bottom to receive a spring 54 therein, and a cover 55 fitting and welded in the opening edge 130 of the deadbolt hole 13 to stop and bias the spring 54.
The motor 6 is disposed in the motor hole 12 of the inner half housing 1, and has a shaft 60 extending to the front, a semi-round activating block 61 fixed at the front of the shaft 60, a power cord 62 coming out of the end of the motor 6, and a cover 63 fitting and welded in the opening edge 120 of the motor hole 12 of the inner half housing 1.
The electronic alarm set 7 is disposed in the chamber 44 of the elongate rod 4, and has a power cord 70 connected with the power cord 62 of the motor 6 for giving out high decibel sounds in case the steering wheel is rotated or the body of the automobile is touched by a would-be thief after this lock is installed. The alarm set 7 is controlled by a remote controller.
The cap 8 is provided to close the upper opening of the chamber 44 to protect the electronic alarm set 7 after the set 7 is disposed therein.
In assembling, referring to FIGS. 1 and 2, firstly, the locking rod portion 22 of the outer half housing 2 is fitted the passageway 10 of the inner half housing 1, with the stop member 3 engaged in the annular groove 24 of the locking rod 22 to secure it in position and preventing it from completely separating from the block portion 16. Then the deadbolt 5 is inserted in the deadbolt hole 13 of the inner half housing 1, with the vertical face 51 engaging the vertical face 230 of one of the grooves 23 of the locking rod 22, the spring 53 is disposed in the recess 52, and with the cover 55 is fitted in the opening edge 130 of the deadbolt hole 13 and welded thereon. Next, the electronic alarm set 7 is disposed in the chamber 44 of the elongate rod 4, with its power cord 70 extending out of the hole 440 of the chamber 44 and out of the cord hole 43 in the front bottom of the elongate rod 4 and connected with the power cord 60 of the motor 6. After that, the cover 8 is used to close up the chamber 44, the spring 41 is disposed in the recess 40, and the front end of the elongate rod 4 is inserted in the chamber 11 of the inner half housing 1. The two bolts 14, 14 are threadedly engaged through the bolt holes 42, 42 and 14, 14, thus finishing the assemblage.
If this lock is to be applied on the steering wheel of an automobile, referring to FIGS. 3, 4 and 5, firstly, the semiround portion 15 of the inner half housing 1 is fitted around the outer surface of an upper portion of the steering wheel, letting the elongate rod 4 extend to the corner between the gauge panel and the wind shield of the automobile, with the spring 54 pushing the deadbolt 5 upward to always engage one of the grooves 23 of the locking rod 22 of the outer half housing 2 in case of the deadbolt 5 being disposed in a locked condition. When the vertical face 51 of the deadbolt 5 engages a vertical face 230 of one of the grooves 23, the outer half housing 2 cannot be pulled outward but can be pulled inward because the sloped face 50 of the deadbolt 5 permits it to slide along the sloped face 231 of grooves owing to resilience of the spring 54, thus permitting the semiround portion 20 of the outer half housing 2 to closely surround the steering wheel, and the end of the locking rod 22 pressing the spring 41, with the elongate rod 4 having its end sticking to the corner of the gauge panel and the windshield, thus preventing the steering wheel from being rotated. In addition, a remote controller is operated to turn on the electronic alarm set 7, which is ready to give out a high decibel alarm if the lock being moved by rotating the steering wheel or by contacting the body of the automobile.
If this steering lock is to be disengaged from the steering wheel, referring to FIGS. 3 and 4, the remote controller is operated to cut off the electronic alarm set 7, and the motor 6 is started through the power cord 70, rotating the shaft 60 and the semiround block 61 for 180° degrees to push down the deadbolt 5 so that the vertical face 51 may separate from the vertical face 230 of the groove 23, letting the spring 41 resiliently push the locking rod 22 outward for such a distance as to enable the outer half housing 2 to be released from the steering wheel. Then the stop member 3 will prevent the locking rod 2 from being completely pulled out of the block portion 16 of the inner half portion.
As can be understood from the above description, this automobile steering lock has the following advantages.
1. Locking and unlocking this lock is operated by means of the remote controller, this is very convenient and handy.
2. The deadbolt moves steadily in engagement and disengagement from any one of the grooves of the locking rod, thus assuring that the locking or unlocking action is stable and accurate.
3. The remote controller makes the locking or unlocking action accurate and convenient, thus preventing the automobile from being stolen, and also providing an alarm. | 4y
|
This is a continuation of application Ser. No. 730,573, filed May 6, 1986, which was abandoned upon the filing hereof.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metal core for a steering wheel, to be used for automobiles, and more specifically to a steering wheel core in which a plurality of metal pipe core elements in circular arc form are connected by connecting metal core elements of a prescribed number whereby a ring core is formed, and spoke cores are connected at respective radially outer ends to the connecting core elements of the ring core and at respective radially inner ends to a boss plate.
2. Description of the Prior Art
In such a steering wheel metal core of the prior art, a part of a ring core is formed a by pipe so as to make the metal core lighter in weight, a plurality of pipe core elements in circular arc form are connected by connecting core elements of a prescribed number, and thereby a ring core is formed. In this case, connection of the pipe core elements with the connecting core elements has been performed in a process in which the pipe core elements are arranged outside the connecting core elements and end circumferential surface of each pipe core element is welded to each connecting core element.
However, simultaneous welding of the whole circumference at ends of the pipe core elements is difficult because the welding may be obstructed by other portions. Consequently, the whole circumference is divided into three or the like during the welding. For example, when the ring core is composed of the three pipe core elements, the connecting core elements also become three in number and each pipe core element is welded at both ends. That is, the six portions must be welded by dividing in three respectively and therefore the process number becomes large for the connection.
Since welding is utilized in order to connect the pipe core elements to the connecting core elements, both core elements cannot be connected to each other if both are made of different materials, for example, if the connecting core elements are made of iron and the pipe core elements are made of aluminium to make the core metal lighter in weight.
SUMMARY OF THE INVENTION
An object of the invention is to provide a metal core for a steering wheel in which caulking (i.e. squeeze-forming, such as crimping) is utilized in order to connect the pipe core elements with the connecting core elements. The number of process required for manufacturing the ring core is not large, and the pipe core elements and the connecting core elements can be connected to each other even if both of the types of core elements are made of different materials.
The above object can be attained by the invention in that each recess is formed in a connecting core element at a connecting portion radially outside of which a respective pipe core element is to be arranged. That pipe core element is arranged outside the connecting portion of the respective connecting core element and caulked (i.e. squeeze-formed) into the recess of the connecting portion, and as a plurality of the pipe core elements in circular arc form are connected in a like manner, a ring core is formed.
Further in a steering wheel metal core according to the invention, when a pipe core element is caulked (i.e. squeeze-formed) into the recess portion in a respective pipe core element, the end of the pipe core element may be narrowed smoothly in a tapered or curved surface manner towards the outer circumferential surface of the recess so as to form the ring core. In such constitution of the ring core, when a coating layer of soft plastic material is formed on outer circumference of the ring core by means of injection molding after formation of the steering wheel metal core, the molding material flows smoothly over all of the outer circumference of the ring core, thereby generation of an uneven luster or a weld mark on the outer surface of the coating layer can be reduced.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a plan view of a steering wheel metal core of a first embodiment of the invention;
FIG. 2 is a sectional view taken in line II--II of FIG. 1;
FIG. 3 is a partial sectional view of a steering wheel metal core of a second embodiment; and
FIG. 4 is a partial sectional view of a steering wheel metal core of a third embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In a first embodiment as shown in FIG. 1 and FIG. 2, a steering wheel metal core 1 comprises a boss plate 6 of iron, three flat spoke cores 5 of iron welded at their radially inner ends with the boss plate 6, and a ring core 2 welded with radially outer ends of the spoke cores 5.
The ring core 2 is composed of three pipe core elements (i.e. ring core elements) 3 in circular arc form and three solid connecting core elements 4 to connect the pipe core elements 3 into ring form. The radially outer end of each spoke core 5 is welded with each connecting core element 4. Each pipe core element 3 is made of aluminium in consideration of lightening in weight, and each connecting core element 4 is made of iron in consideration of welding with the respective spoke core 5.
Each connecting core element 4 is formed as an arcuate member, provided on its opposite arms 4b, 4b near both ends thereof with radially outwardly opening recesses (i.e. indentations) 4a of annular groove form, two per end. The ends of each pipe core element 3 are arranged radially outside the portions of the respective connecting core elements where the recesses 4a are provided and caulked (i.e. squeeze formed) into the portions including the recesses, through the mouths of the recesses, thereby fixedly connecting the pipe core elements 3 to the respective connecting core elements 4.
Each connecting core element 4 has the four recesses 4a having sides 4c which diverge outwardly to respective mouths 4d and therefore use of the three connecting core elements 4 requires squeeze-forming actions to be performed at twelve sites. In order to manufacture the ring core 2, the pipe core elements 3 are arranged radially outside the portions of the respective connecting core elements where the recesses 4a, thereby assembling the pipe core elements and the connecting core elements 4 into ring form. The connecting core elements are then caulked (i.e. squeeze-formed) to a corresponding jig, in one caulking operation. Thus, the number of process steps needed for manufacturing the ring core 2 may be reduced and the cost is lowered.
Since caulking (i.e. squeeze-forming) is utilized to connect the pipe core elements 3 with the connecting core elements 4, both types of core elements can be fixedly connected to each other even if they are made of different materials.
After the ring core 2 is manufactured as above described, the ring core 2, the boss plate 6 and the spoke cores 5 are set into a prescribed jig in a conventional manner, and each spoke core 5 is welded at its respective ends with the boss plate 6 and the connecting core element 4 of the ring core 2, thus further completing manufacture the steering wheel metal core 1.
Although each connecting core element 4 in the first embodiment is formed near both ends with recesses 4a of annular groove form at two portions per end, the recesses 4a may be formed at one portion per each end as long as the pipe core elements 3 can be securely connected by squeeze-forming, to the respective connecting core elements.
Referring to the second embodiment shown in FIG. 3, each connecting core element 14 may be formed on outer circumference near both of its ends with recesses 14a being not in annular form but sunk at prescribed portions. Each pipe core element 13 may then be arranged outside the sunk portions on respective connecting core elements and caulked (i.e. squeeze-formed) therewith so as to form a ring core 12.
Further, referring to the third embodiment shown in FIG. 4, when a pipe core element 23 is to be caulked (i.e. squeeze-formed) at both ends, it may be narrowed smoothly in a tapered or curved surface manner to the outer circumferential surface of a respective recess 24a of a respective connecting core element 24 so as to form a ring core 22. In such a type of construction, if a coating layer of soft plastic material is formed by injection molding on outer circumference of the ring core 22 after forming the steering wheel metal core, the molding material flows smoothly towards the outer circumference of the ring core 22 so that the generation of an uneven luster or a weld mark on the outer surface of the coating layer can be reduced.
In addition, although a circular cross-section is shown in the drawings for the pipe core elements 3, 13, 23 and the connecting core elements 4, 14, 24 of the first through third embodiments, it may be square or trigonometric other than circular.
Although the connecting core elements 4, 14, 24 disclosed in the first through third embodiments preferably is solid, it may be hollow as long as the welding with the spoke core can be performed satisfactorily. | 4y
|
RELATED APPLICATIONS
This is a Continuation of patent application Ser. No. 08/164,879, filed Dec. 9, 1993, now U.S. Pat. No. 6,251,952, which is a Continuation-in-part of patent application Ser. No. 07/645,175, filed Jan. 24, 1991, now abandoned.
BACKGROUND OF THE INVENTION
This invention relates to methods, apparatus and substances for moisturizing the eye and particularly to moisturizing the eye with natural tears, i.e., by inducing natural tear production rather than introducing artificial tears.
Many people suffer from what is commonly known as “dry eye”. The condition arises from lack of sufficient tear production and results in a variety of symptoms such as burning, itching and undue sensitivity to smoke. The condition is more common in older adults inasmuch as a gradual lessening of tear production is a natural concomitant of the aging process. However, younger persons also suffer dry eye as a pathological disorder and the problem is particularly acute with the wearers of contact lenses. In this case, tear production may be entirely adequate for normal purposes but insufficient to provide adequate wetting and lubrication to permit wearing such lenses in comfort.
As any wearer of contact lenses knows, the low humidity of the average home or office in winter, windy days, and other ambient climatological conditions greatly aggravate the situation and often times precludes wearing contact lenses. With prolonged wear under drying conditions, the eye sometimes generates mucous which coats the lenses to the point that they can become opaque. If this occurs while the wearer is reading, say, a research paper before a learned society or making a presentation at a business meeting, it can be embarrassing; while driving, dangerous.
With more than discomfort involved, it is important that the eyes be quickly, easily, and effectively moisturized and there is a need to do this without embarrassment in public places and social situations.
THE PRIOR ART
At the present time numerous eye moisturizing products are available ranging from simple artificial tears to lens clearing and lubricating solutions and additives calculated to “get the red out”.
While these products vary widely in effectiveness, cost and the claims made for them, they have one thing in common: insofar as is known, all are liquids intended for macroscopic introduction into the eye in the form of drops and are packaged either in plastic squeeze-bottle droplet dispensers or glass containers having caps fitted with an eye dropper. They are intended to be administered by tilting back one's head, putting the dropper nozzle over and in proximity to the eye (being careful to observe the label warning not to touch the tip lest the contents of the dispenser become contaminated), and allow a drop or two to fall into one eye at a time.
Another method of administration of liquid drops involves pulling down the lower eyelid to form a pocket and placing the drops into the pocket.
With practice, some users become so proficient with one or the other technique that they can get a high percentage of the drops dispensed to fall into the eye. Near misses can be dealt with if tissues are handy and, if not, the drops roll harmlessly down the cheeks, the only occasional casualty being smeared mascara unless of course one is foolish enough to attempt the administration while driving!
From the foregoing it will be noted that a well-equipped wearer of contact lenses should carry: a lens case (to store the lenses in the event that dryness forces their removal); a pair of corrective spectacles to substitute for the “contacts”; a bottle of eye drops; and a supply of tissues.
Those persons who do not wear or aspire to wear contact lens but have dry eye suffer only slightly fewer vexations, viz., they are not burdened with the contact wearers paraphernalia.
With the foregoing state of the art in view, it is the object of this invention to overcome or at least mitigate the problems of the prior art as outlined above.
A further object is the provision of methods and means for moisturizing the eye without introducing moisturizing liquid into the eye.
Another object is to provide methods and means for inducing “dry eyes” to generate natural tear in situ. A still further object is to provide means for moisturizing the eye which can be employed discretely and without attracting notice in public places.
BRIEF DESCRIPTION OF THE INVENTION
To the fulfillment of these and other objects, the invention contemplates a method for moisturizing the eye by the microscopic introduction into the eye in gaseous or vapor form, a substance causing the generation of tears by the lachrymatory glands.
The substance is a lachrymatory agent vaporizable at room temperature diluted to a concentration which causes tearing of the eye without untoward smarting or irritation.
The invention further contemplates a device for moisturizing the eye comprising a container having an opening and a closure member normally closing the opening. Means are provided for opening the closure member and a lachrymatory agent as described above is disposed in the container.
A kit comprising an amount of lachrymatory agent and means for dispensing an effective amount of said lachrymatory agent to cause tears.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation, partly in section on the vertical center line, of a device for moisturizing the eye embodying the invention.
FIG. 2 is an elevational view taken on line 2 — 2 of FIG. 1, looking in the direction of the arrows.
FIG. 3 is a top plan view of FIGS. 1 and 2.
FIG. 4 is an elevational view of the structure in FIG. 1 with parts in an alternate position.
FIGS. 5, 6 and 7 are views similar to FIG. 4 showing modified embodiments of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
It has been determined that the smarting and tearing effect associated with peeling onions is caused by propanethial-s-oxide (‘PSO”) and related compounds naturally occurring in onions. (See “PROPANETHIAL-S-OXIDE”, Chemical Abstracts Registry #3215729-2). The compounds are quite volatile, vaporizing at room temperature. These compounds, the most significant of which is propanethial-s-oxide, and other compounds having similar chemical and physical properties, viz., lachrymatory activity and volatility, can be diluted and utilized to stimulate tearing to combat pathogenic and benign dry eye conditions.
The method of moisturizing the eye contemplated by the invention consists of the fundamental step of introducing into the eye, in vapor, gaseous or otherwise microscopic form, a lachrymatory compound(s) naturally occurring in onions. For the purposes of this specification the term microscopic is defined to encompass misting, vaporous or gaseous methods of introducing lachrymatory agents into the eye. The lachrymatory compounds may be appropriately diluted to a concentration that is suitable to the individual using it. The concentration must be determined empirically as the strength of the compounds in onions varies widely with the variety of onion used, growing conditions, etc. The desideratum is a concentration which produces sufficient tearing without undue burning or smarting of the eye.
The preferred composition comprises an amount of PSO and related compounds to produce tears after a short exposure time. The purity of the compounds will have a direct effect on the production of tears. It is preferred to use pure PSO and related compounds, although the PSO and related compounds maybe diluted to promote the volatility of the PSO. Common pharmaceuticals adjuvants may also be added to the compositions to produce the desired composition. Said common pharmaceutical adjuvants can be found in Remingtons Pharmaceutical Sciences, fifth edition, by Mack Publishing Company, which publication is herein specifically incorporated by reference. The desired composition may be any that is known to those skilled in the art and can be based on, for example, an aerosol composition employing a propellant, or a volatile composition using volatility enhancers, such as, for instance, ethyl alcohol.
A device for introducing the lachrymatory agent will now be described with reference to the drawings and, first, to FIGS. 1 to 4 showing a container 10 having an opening 12 at its upper end. A cap assembly 14 includes a mounting band 16 tightly encircling opening 12 and a captive closure member 18 secured to the band by a hinge 20 consisting of a strip of flexible plastic or other material.
Closure member 18 is of the type often referred to as a “snap-cap” and is closed by means of downward finger pressure applied on its top surface, preferably at a point diametrically opposite hinge 20 . In this condition, the cap closes opening 12 .
A radially projecting tab 22 on cap 18 facilitates opening the container which is accomplished by upward pressure on the tab. Thus opening can be accomplished with a single finger, usually the thumb, by pushing tab 22 upwardly; when in the open position, shown in FIG. 4, the cap is held captive by hinge 20 .
Container 10 has a generally ovate cross-section as appears in FIG. 3, lending itself to a comfortable fit in the user's palm and permitting easy removal and replacement of the cap.
Container 10 is filled to the desired level with the lachrymatory agent; preferably the agent is absorbed in a matrix of suitable absorbent material such as cotton shown at 24 in FIG. 1 . Whether or not a matrix is used, it is preferred that a wick 26 be disposed in the container extending from a point at or near its bottom 28 and extending to opening 12 , terminating flush with the face of the opening.
To moisturize the eye, the user simply positions the opening of the container close to his eye, opening the cap before or after doing so. (There is no need to tilt the head back.) The vapor from the container enters the eye and almost immediately stimulates tear production by the lachrymatory glands. After a few moments, i.e., when the desired effect is obtained, the process is repeated with the other eye. Then the cap is replaced and the container restored to purse or pocket.
An alternative form of the moisturizer is shown in FIG. 5 wherein the cap assembly 14 ′ is modified as compared to FIGS. 1-4 by the substitution of a spring hinge 20 ′ for hinge 20 .
Spring hinge 20 ′ resiliently biases cap 18 toward its open position and a latch is provided diametrically opposite the hinge. When engaged, the latch maintains the cap in closed position against the bias effect of the spring. A latch release button 32 , when pressed, causes the cap to snap open; it is closed by applying downward pressure on the top surface of the cap in the same manner as the previously described embodiment. The use of the FIG. 5 moisturizer is entirely analogous to and will be readily apparent from the above-described use of the device in FIGS. 1-4.
FIGS. 6 and 7 show further embodiments of the invention each including a preferably soft plastic cup-shaped member 34 and 34 ′, respectively, mounted on a container 10 . Members 34 , 34 ′ are configured and dimensioned to fit over the eye and are, in use, selectively placed in flow communication with the interior of the container so as to guide and confine vapor issuing there from to the ocular region.
The FIG. 6 embodiment is a non-aerosol, pump-type dispenser which ejects a measured quantity of the contents of the container 10 each time the member 34 is depressed as by finger pressure on the flat 35 provided thereon for the purpose.
FIG. 7 illustrates an aerosol-type unit in which the contents of container 10 are under pressure and a metered quantity ejected into member 341 when a valve actuation button 36 is pressed. It will be understood that the construction and operation of the pump and aerosol dispensing devices per se are well known. However the substance issuing from the device is not an aerosol or spray but a vapor.
The use of the devices shown in FIGS. 6 and 7 is completely analogous to that of the FIG. 1-4 embodiment of the invention already described except, of course, that the cup-shaped member 34 , 34 ′ is placed over the eye before dispensing the lachymatory vapor.
The use of a kit comprising means for dispensing lachrymatory agent and the lachrymatory agent itself is also within the scope of this invention. A preferred kit would use an apparatus for dispensing said lachrymatory agent as described above containing a lasting supply of lachrymatory agent. Such kit would be packaged in a shrink wrapped package or a hard plastic protection pack. The packaging material used in the kit can be any material known to those skilled in the art. Such materials can include cardboard, plastic and any combination of the two, for example.
From the foregoing description of exemplary embodiments, it will be seen that the objects of the invention are achieved, enabling moisturization of the eyes discretely and effectively, using a single hand, without tilting the head or possibility of misapplication of liquid drops. The scope of this invention is intended to include all such modifications that would be obvious to one of ordinary skill in the art. | 4y
|
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a divisional of application Ser. No. 09/148,182, now U.S. Pat. No. 6,242,369 filed on Sep. 4, 1998. This parent application is herein entirely incorporated by reference.
FIELD OF THE INVENTION
This invention relates to metallized, particularly aluminized, fabrics which are coated with specific polyurethane finishes. Such specific polyurethanes must be cross-linked and present in latex form. Upon impregnation within metal-coated fabrics, these particular polyurethanes provide vastly improved washfastness properties to the fabrics and thus ensure the retention of substantially all the metal coating within and on the target fabric.
DISCUSSION OF THE PRIOR ART
Metallized fabrics have recently been utilized in order to provide effective heat insulation for garments, particularly apparel for use outdoors and in cold-weather climates. Other uses for such fabrics have included incorporation within radar-detectable objects, such as in U.S. Pat. No. 4,390,588, to Ebneth et al.; water-repellent automobile covers, as in U.S. Pat. No. 5,271,998, to Duckett et al.; strength-enhanced fibrous materials, as in U.S. Pat. No. 3,660,138, to Gorrell. Washfastness is a very important characteristic which needs to be exhibited by metallized fabrics, particularly those which are intended to be incorporated within garments. Generally, such metal coatings, in particular aluminum, easily washes out of and from fabric substrates upon standard laundering procedures. Past attempts have been made to reduce the loss of metal from such fabrics. These include U.S. Pat. No. 5,744,405, to Okumura et al., which requires a siloxane over coat adhered to the metal-coated fabric through a plasma pre-treatment; and U.K. Patent 800,093, to Kunsch, which discloses the pre-treatment of fabric with cross-linked polyurethanes and the like, prior to depositing metal on the treated fabric surface. The Kunsch pre-treatment basically acts as an adhesive for the metal to remain bonded to the fabric substrate. These methods have proven to be either costly (with the high expense of plasma pre-treatments and particular siloxanes), or ineffective (with the mere utilization of an adhesive to bind the metal to the fabric leaving an appreciable amount of metal susceptible to removal through inadvertent contact and friction with certain surfaces as well as corrosion through atmospheric and aqueous oxidation). As such, there is no teaching or fair suggestion within the prior art which pertains to the improvement in metal-coated fabric washfastness provided by cross-linked polyurethane/acrylic polymer which is impregnated within the target fabric after deposition of the metal composition.
DESCRIPTION OF THE INVENTION
It is thus an object of the invention to provide improved washfastness for metallized fabrics. A further object of the invention is to manufacture a polyurethane-coated, aluminized fabric with better washfastness than comparable aluminized fabric. Another object of the invention is to provide a metallized fabric for incorporation within garments for the outdoor and cold-weather climate apparel industries which provides effective and appreciable levels of heat insulation throughout the wearable lives of such garments. Yet another object of this invention is to provide a fabric for use in any type of heat insulation covering or fabric and not necessarily within apparel. Still a further object of the invention is to provide a method for producing such a metallized, washfast, heat insulation fabric.
Accordingly, this invention encompasses a fabric comprising a metal coating wherein said metal coating comprises discrete metal particles which are encapsulated within a cross-linked polyurethane latex. Nowhere within the prior art has such a specific encapsulated metal coating for fabrics been utilized to impede corrosion of the metal particles adhered to the fabric surface thereby substantially eliminating the removal of such metal particles from the fabric substrate due to atmospheric conditions and/or harsh laundering conditions.
Any fabric can be utilized in this invention as the important requirement is that the polyurethane latex thoroughly coat the metal particulate coating of the fabric in such a way as to substantially prevent contact between the metal and atmospheric oxygen or harsh oxidizing (and thus corrosive) chemicals present within laundry applications. Polyester is most preferred; however, any natural fibers, such as cotton, ramie, and the like; any synthetic fibers, such as polyamides, lycra, and the like; and any blends thereof of any natural and/or synthetic fibers may be utilized within the inventive fabric. Furthermore, woven fabrics are preferred; however, knitted and non-woven forms may also be utilized as well as combinations of any types of these forms. The important limitation of this invention is the presence of the polyurethane latex over the metal coating of the target fabric to provide a barrier to corrosive elements and thus ultimately provide a long-lasting fabric for the retention of heat.
Any metal generally utilized within a coating for fabrics may be utilized within this invention, also. The most common metal for this purpose, aluminum, is most preferred, basically because of its low cost in combination with its superior performance (particularly in provided heat retention for clothing in cold climates). Other metals which may be utilized include copper, silver, nickel, zinc, titanium, vanadium, and the like.
The preferred polyurethane component is a waterborne aliphatic or aromatic polymer which also lends a soft hand to the target fabric. As such, the preferred polyurethane is a dispersion comprising a polyurethane having an elongation of at least 150% and conversely a tensile strength at most 7,000 psi. Particular examples of such dispersions include those within the Witcobond® polyurethane series, from Witco, such as W-232, W-234, W-160, W-213, W-236, W-252, W-290H, W-293, W-320, and W-506; most preferred is W-293. Acrylic polyurethane dispersions may also be utilized provided they exhibit the same required degree of elongation and tensile strength as for the purely polyurethane dispersions.
Any cross-linking agent compatible with polyurethanes may be utilized within this invention, particularly those which have low amounts of free formaldehyde. Preferred as cross-linking agents are Cytec™ M3 and Aerotex™ PFK, both available from BFGoodrich. Any catalyst, which is generally necessary to initiate and effectuate cross-linking of a polyurethane dispersion, which is compatible with both a polyurethane and a polyurethane cross-linking agent maybe utilized within this invention. Preferred as a cross-linking catalyst is Cytec™ MX, available from BFGoodrich.
The cross-linked polyurethane latex of the invention may be present in any amount and concentration within an aqueous solution for use on and within the target fabric. The table below indicates the difference in performance of the cross-linked polyurethane latex in reference to its concentration and dry solids addition rate on the fabric surface. Preferably, the concentration of the polyurethane is from 5 to 100% by weight of the utilized aqueous solution; more preferably from 10 to about 75% by weight; and most preferably from 25 to about 50% by weight. The coating addition rate (measured as the percent of dry solids addition on the weight of the fabric) of the cross-linked polyurethane dispersion is preferably from 3 to 50% owf; more preferably from about 6 to about 40% owf; and most preferably from about 15 to about 30% owf.
As noted below, the basic procedure followed in applying this cross-linked polyurethane dispersion entails first providing a metal-coated fabric. Next, the latex is formed by combining the polyurethane with the cross-linking agent and optionally a catalyst to effectuate such cross-linking of the polyurethane. The resultant latex is then diluted with water to the desired concentration which will provide the most beneficial washfastness of the metal coating after treatment. The metal-coated fabric is then saturated with the resultant aqueous solution of the polyurethane latex with the excess being removed. Such saturation and removal of the latex may be performed in any standard manner, including dipping, padding, immersion, and the like for initial contacting of the dispersion; and wringing, drying, padding, and the like for the removal of the excess. The treated fabric is then dried and cured for a period of time, preferably at a temperature sufficient to effectuate a complete covering of the metal particles previously adhered to the target fabric surface. For example only, a temperature between about 300 and 450° F.; preferably between 310 and 400° F.; more preferably from 325 and 385° F.; and most preferably between 350 and 370° F. are workable. Times of from 2 to 30 minutes are preferred for this drying and curing step with a time between about 2 and 10 minutes most preferred.
Any other standard textile additives, such as dyes, sizing compounds, and softening agents may also be incorporated within or introduced onto the surface of the finished wrinkled apparel fabric substrate. Particularly desired as optional finishes to the inventive fabrics are soil release agents which improve the wettability and washability of the fabric. Preferred soil release agents include those which provide hydrophilicity to the surface of polyester. With such a modified surface, again, the fabric imparts improved comfort to a wearer by wicking moisture. The preferred soil release agents contemplated within this invention may be found in U.S. Pat. Nos. 3,377,249; 3,540,835; 3,563,795; 3,574,620; 3,598,641; 3,620,826; 3,632,420; 3,649,165; 3,650,801; 3,652,212; 3,660,010; 3,676,052; 3,690,942; 3,897,206; 3,981,807; 3,625,754; 4,014,857; 4,073,993; 4,090,844; 4,131,550; 4,164,392; 4,168,954; 4,207,071; 4,290,765; 4,068,035; 4,427,557; and 4,937,277. These patents are accordingly incorporated herein by reference.
This metal-coated fabric may be incorporated into a garment due to the advantages of its first retaining a substantial amount of metal particles within and on the target fabric after a long duration of wear and standard laundering; and second, retaining a substantial amount of heat due to the presence of a large amount of heat-retaining metal particles within and on the target fabric. Further uses for such a fabric include, without limitation: tents, awnings, blankets, crowd covers, jackets, scarves, and the like.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The following example is indicative of the preferred embodiment of this invention:
EXAMPLE
A 100% polyester, 4×1 sateen woven fabric (115/34 warp-drawn warp yarn and 150/50 textured fill yarn, having a fabric weight of 3.5 ounces per square yard) was evaporation-coated with 0.24% (wt.) of aluminum produced by Diversified Fabrics Inc. A latex mixture of 100 grams Witcobond® W-293 (polyurethane dispersion available from Witco), 1 gram of Cytec™ M3 (cross-linking agent available from BFGoodrich), and 1 gram of Cytec™ MX (catalyst available from BFGoodrich) were then blended together in a beaker. This mixture was then diluted with water to varying concentrations as set forth in the table below. Different swatches of the aluminum-coated fabric were then saturated with these various polyurethane latex mixtures and squeezed between two wringers in order to remove excess latex. In such a procedure the polyurethane latex actually encapsulates the individual or cohered aluminum particles. Each swatch was then dried and cured at 3600° F. for about 5 minutes. Each treated swatch was then washed according to AATCC Test Method 130-1995, “Soil Release: Oily Stain Release Method” and measured for aluminum retention after different numbers of washes. The washfastness of the latex encapsulate remaining aluminum was calculated through the utilization of a % ash test according to AATCC Test Method 78-1989, “Ash Content of Bleached Cellulosic Textiles.” The results were tabulated as follows:
TABLE
Washfastness (% Al remaining
Latex Conc.
Coating Addition Rate
after X washes)
(wt %)
(% Dry Solids owf)
X = 3
X = 10
X = 20
0
0
2.3
4.5
4.5
2.5
1.7
22.7
11.4
6.8
5.0
3.3
31.8
27.3
27.3
10.0
6.0
65.9
43.2
40.9
15.0
8.3
68.2
59.1
45.5
25.0
15.0
88.6
75.0
75.0
50.0
26.7
90.9
86.4
86.4
75.0
36.0
86.4
77.3
72.7
100
49.0
86.4
84.1
84.1
As is clearly evident, the washfastness of the aluminum improved dramatically first upon utilization of the cross-linked polyurethane encapsulate, and second, upon utilization of greater concentrations of the latex up to a 50% by weight concentration of the cross-linked latex in aqueous solution.
There are, of course, many alternative embodiments and modifications of the present invention which are intended to be included within the spirit and scope of the following claims. | 4y
|
FIELD OF THE INVENTION
[0001] The present invention relates to an industrial robot transmission system for the transmission of movement to a robot part, and an industrial robot comprising such a system. The invention also relates to a method for preventing the deterioration of a lubricant due to absorption of moisture, inside an industrial robot used in surroundings with high humidity, and further to a method for absorbing moisture inside a gearbox containing a lubricant in an industrial robot.
BACKGROUND OF THE INVENTION
[0002] Outdoor applications are a relatively new field of use for industrial robots. During outdoor use of robots under humid conditions, it has been found that the lubricant used in e.g. the gearbox of the robot, after some time displays a moisture content that is higher than normal, due to the moisture from the surroundings penetrating into the gearbox. This is a disadvantage since it could lead to less good lubrication, increased wear on machine parts that need lubrication, a shorter life time and consequently higher costs. In order to avoid this, the lubricant has to be checked and changed at shorter intervals which also will increase costs. Alternatively, the lubricant that is used must be a lubricant that is capable of standing higher moisture in the surroundings without negative effects on its lubricating function and capabilities. Another conceivable alternative would be to make the gearbox much tighter, if possible. All of these alternatives involve increased costs.
[0003] There is also a problem created by increased moisture content in the gearbox, when the moisture is not absorbed by the lubricant, but is present as free water, dissolved or emulsified by the lubricant, which is equally or more detrimental to the function of the lubricant.
[0004] Industrial robots may also be used in other environments where the humidity is high, for example in foundry or wash-down environments such as in food industry. A similar problem with increased moisture content in lubricants may also occur in such applications.
[0005] Problems with lubricants absorbing moisture also may occur due to temperature variations which result in a temperature difference between the surroundings and the interior of the gearbox, and this will in turn result in pressure difference between the surroundings and the interior of the gearbox, which may lead to an increase of moisture in the gearbox when humid air is sucked into the gearbox due to lower internal pressure. For example, this may be the case when a robot is operated in two or three shifts, and the day temperature may be considerably higher than the night temperature. These temperature variations in combination with a humid surrounding are a particularly challenging problem.
SUMMARY OF THE INVENTION
[0006] One object of the present invention is to provide a solution to problems related to too high moisture contents in lubricants used in industrial robots, and thereby increase the possibility of using industrial robots in environments with high humidity. The object is also to make this possible in a simple and inexpensive way.
[0007] These objects are achieved by the features defined in the present teachings.
[0008] According to a first aspect of the present invention, is defined an industrial robot transmission system for the transmission of movement to robot parts, comprising at least one motor and at least one gearbox containing a lubricant, characterized in that the gearbox is provided with an integrated moisture absorbing device comprising a moisture absorbing material adapted to absorb moisture contained in the gearbox. By providing the gearbox with an integrated moisture absorbing device, the moisture in the gearbox will be absorbed by the moisture absorbing device instead of being absorbed, dissolved or emulsified by the lubricant, and the moisture absorbing device may also absorb water from the lubricant. This is defined in that the moisture absorbing device comprises a moisture absorbing material with higher affinity to water than the affinity of the lubricant to water.
[0009] It is foreseen that the lubricant may come into contact with the moisture absorbing material, in which case the moisture absorbing material may absorb lubricant instead of water or moisture, and become saturated with lubricant, in which case it will not be able to absorb moisture. This may be prevented by the moisture absorbing device comprising a moisture absorbing material with higher affinity to water than to the lubricant.
[0010] In many applications it will be desirable that the affinity to water of the moisture absorbing material is such that the absorbing material will both absorb moisture in a gaseous phase from within the gearbox and water present as free water, dissolved in, absorbed or emulsified by the lubricant, as well as preventing lubricant from being absorbed by the moisture absorbing material.
[0011] Affinity should be interpreted to include both chemical affinity and physical affinity or a combination thereof.
[0012] By integrating the device in the gearbox is provided a simple and inexpensive means for absorbing moisture and thereby prolonging the time span between lubricant changes, decreasing the risk of damage to parts in the gearbox due to reduced lubricating function of the lubricant which in turn is due to an excessive amount of moisture having been absorbed by the lubricant.
[0013] By the expression integrating is intended a device that can be kept mounted in the gearbox all the time, and including during operation of the gearbox. There will be no need for any separate external devices that have to be connected and disconnected.
[0014] According to one feature, the moisture absorbing device may be removable. Through this, the device may be exchanged whenever desirable, and replaced by a new device.
[0015] The moisture absorbing device may be integrated in the gearbox by being provided as part of a plug located in a hole in a wall of the gearbox. The moisture absorbing device with its absorbing material may be arranged in several ways. For example, it may be provided mainly outside the gearbox and the moisture will be absorbed via a hole in the plug providing a communication from the interior of the gearbox to the moisture absorbing material of the device. In an alternative, the moisture absorbing device may be provided mainly inside the gearbox, being attached to the plug and in which case the moisture absorbing material inside the gearbox may be surrounded by a moisture permeable shell or film or similar, if necessary. According to another alternative, the moisture absorbing material may be contained in the plug.
[0016] According to another embodiment, the gearbox is provided with at least one oilplug hole for the filling or and draining of lubricant in the gearbox, and the moisture absorbing device is integrated in an oilplug designed to be inserted in the oilplug hole. If a regular oilplug hole of the gearbox can be used for a plug with an integrated moisture absorbing device, this provides a very simple and economic solution, since no separate hole for the moisture absorbing device will be necessary.
[0017] It will also be advantageous to have some provision in relation to the moisture absorbing device that will provide an indication of whether the device can still absorb moisture or if it has used up its moisture absorbing capacity, and needs to be replaced. To this end, the moisture absorbing device may comprise a moisture absorbing material having a physical property that is adapted to change depending on the amount of absorbed moisture. Examples of such physical properties may be colour, volume, electrical resistance etc.
[0018] According to another alternative, the moisture absorbing device may comprise a sensor device adapted to emit a signal, reflecting the status of absorbed moisture in the moisture absorbing device, to an indicator device which indicates the status of absorbed moisture.
[0019] As a further alternative, the moisture absorbing device may comprise a sensor device adapted to emit a signal, reflecting the status of absorbed moisture in the moisture absorbing device, to a control system. This control system may be a robot controller, a programmable logic controller (PLC), a remote service, a remote control device or any other type of control system or device regularly used in connection with industrial robots.
[0020] According to another aspect of the invention is defined an industrial robot comprising a transmission system with an integrated moisture absorbing device having the above features.
[0021] According to yet another aspect of the invention is defined a method for preventing the deterioration of a lubricant due to absorption of moisture, inside an industrial robot used in surroundings with high humidity, characterized by integrating a moisture absorbing device comprising a moisture absorbing material in a robot part containing the lubricant. By integrating a moisture absorbing device in a robot part containing a lubricant, the moisture will be absorbed by the moisture absorbing device instead of being absorbed by the lubricant, and moisture already absorbed by the lubricant may be reduced, as already discussed above. Consequently deterioration of the lubricant due to excessive moisture content is prevented, and the life span of the lubricant is prolonged. This may be achieved by choosing a moisture absorbing material with higher affinity to water than the affinity of the lubricant to water.
[0022] It may also be prevented that the moisture absorbing material absorbs lubricant, as also explained above, by choosing a moisture absorbing material with higher affinity to water than to the lubricant.
[0023] According to another feature, the method may be characterized by choosing a moisture absorbing material having a physical property that is adapted to change depending on the amount of absorbed moisture. Examples of such physical properties may be colour, volume, electrical resistance etc.
[0024] According to a further feature, the method may be characterised by integrating the moisture absorbing device in a part of a plug located in a hole in a wall of a gearbox containing lubricant and being part of a transmission system for the transmission of movement to a robot part.
[0025] According to another feature, the method may be defined by integrating the moisture absorbing device in an oilplug of the gearbox. The advantages related to this have been described above.
[0026] Finally, and according to a further aspect of the present invention is defined a method for absorbing moisture inside a gearbox containing a lubricant in an industrial robot, characterized by integrating a moisture absorbing device comprising a moisture absorbing material in the gearbox.
[0027] Other features and advantages of the invention may be apparent from the following detailed description of embodiments.
[0028] It should be mentioned that the expression lubricant is intended to encompass any type of lubricant that may be used in an industrial robot and in particular in a gearbox, for example liquid or solid lubricants of any type.
[0029] It should also be mentioned that by moisture is intended fluid moisture such as water in gaseous or liquid form, including such moisture which may be contained in other gases, liquids or solids.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The invention will now be described in more detail, with reference being made to the enclosed schematic drawings illustrating different aspects and embodiments of the invention, given as examples only, and in which:
[0031] FIG. 1 illustrates schematically an industrial robot;
[0032] FIG. 2 shows parts of an industrial robot comprising a transmission system according to the present invention and including a moisture absorbing device;
[0033] FIG. 3 shows a first embodiment of a moisture absorbing device according to the present invention;
[0034] FIG. 4 shows a second embodiment of a moisture absorbing device according to the present invention;
[0035] FIG. 5 shows a third embodiment of a moisture absorbing device according to the present invention; and
[0036] FIG. 6 shows a fourth embodiment of a moisture absorbing device according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0037] In the drawings, the same elements or corresponding elements in the different embodiments have been given the same reference number.
[0038] In FIG. 1 is schematically illustrated an industrial robot. An industrial robot 1 comprises a control system, a manipulator, and electric motor units configured to attend to the movements of the manipulator. Each motor unit comprises an electric motor, a brake, a gearbox and other gearing as necessary in order to form a transmission system for the transmission of movement to a movable part of the robot.
[0039] The illustrated robot is a conventional six-axis industrial robot 1 . However, it is apparent that the invention is not limited to such a robot, but may be used also in robots with more or less axes, and for other types of kinematic solutions such as parallel kinematic robots or SCARA robots.
[0040] The illustrated robot has a stand 3 that is rotatably mounted on a base 2 , about a first axis of rotation A. In the stand 3 , a first robot arm 4 is rotatably journalled for rotation about a second axis of rotation B. The industrial robot further comprises a second robot arm 5 , which is rotatably journalled in the outer end of the first robot arm, for rotation about a third axis of rotation C. The second robot arm is also rotatable about a fourth axis of rotation D which coincides with the longitudinal axis of the second robot arm 5 . A wrist unit 6 is arranged at the outer end of the second robot arm 5 , and said wrist unit comprises a tilt part 7 which is rotatably journalled in the wrist unit 6 for rotation about a fifth axis of rotation E. A turn disc 8 , on which an end effector or tool may be mounted, is arranged on the tilt part for rotation about a sixth axis of rotation F. The manipulator is connected to a control system 1 a.
[0041] In order to drive the connected parts in rotation about the respective axes A, B, C, D, E, F, a transmission system 9 is provided for each movable robot part, of which some of the motors 10 can be seen in FIG. 1 .
[0042] FIG. 2 illustrates parts of an industrial robot provided with a transmission system 9 according to the present invention. The robot parts are a base 2 and a stand 3 , and in the stand is arranged a gearbox 12 connected to an electric motor 10 . The transmission system comprising the electric motor 10 and the gearbox 12 transmits a rotational movement to a first robot arm 4 about the axis of rotation B, as seen in FIG. 1 . The gearbox is filled with a lubricant, in most cases oil.
[0043] A gearbox 12 is in most cases provided with three holes in the gearbox wall 13 in which so called oilplugs are inserted. There is one oilplug and hole for inspection, there is one oilplug and hole for filling oil or other lubricant into the gearbox, and there is one oilplug and hole for draining oil from the gearbox. These holes may be used for the installation of a moisture absorbing device according to the present invention. Alternatively, a separate hole may be made in the wall of the gearbox for the installation of a moisture absorbing device according to the present invention. All of these possible holes that may be used for a moisture absorbing device have been given the reference number 14 , irrespective of if they are already existing holes or separate holes made for this particular purpose. However, in most cases it is preferable that the hole is located underneath the normal surface of the lubricant.
[0044] In the following examples of embodiments illustrated in FIGS. 3-6 , the interior of the gearbox is designated by 15 and the wall of the gearbox is designated by 14 .
[0045] A first embodiment of a moisture absorbing device 20 is shown in FIG. 3 . A hole 14 is provided in the gearbox wall 13 , and in this hole a plug 22 is inserted, thereby plugging the hole. The plug is designed with a part comprising a moisture absorbing device 20 , which is thus integrated in the gearbox. The part of the plug comprising the moisture absorbing device is located externally of the gearbox. The moisture absorbing device comprises a hollow part 24 in the interior of the plug, which hollow part is located externally of the gearbox when the plug is inserted in the hole 14 . In this hollow part 24 there is arranged a moisture absorbing body 26 of a moisture absorbing material 27 . Since also the part of the plug that extends through the hole 14 is hollow, there is free communication between the interior 15 of the gearbox and the interior of the plug with the moisture absorbing material 27 , and the moisture absorbing material can consequently absorb moisture contained inside the gearbox.
[0046] The moisture absorbing material can absorb moisture from the air in the gearbox, or even liquid moisture (water), and it can absorb moisture contained in the oil in the gearbox. This is made possible by choosing a moisture absorbing material that has a higher affinity to water than the affinity of the oil to water, thus preventing that the oil absorbs the moisture/water. The moisture absorbing material may also be chosen to have a higher affinity to water than to the oil, in order to prevent that the moisture absorbing material absorbs oil instead of moisture/water. It is intended to encompass both materials with chemical affinity and materials with physical affinity. Examples of suitable materials are absorbing polymers, e.g. so called super absorbent polymers such as starch-acrylonitrile copolymers, cross-linked acrylic homo-polymers, cross-linked polyacrylate/polyacrylamide copolymers; molecular sieves such as silica gel, zeolites—microporous aluminosilicates; minerals such as calcium sulphate, calcium chloride, magnesium sulphate; clays such as montmorillonite clay. The moisture absorbing material may also be chemically compatible with the used lubricant, i.e. the lubricant may not be chemically affected by the moisture absorbing material, e.g. due to chemical reactions with the material or catalysed by the material.
[0047] Materials with a combined chemical and physical affinity may also be used, e.g. materials having physical affinity in the form of hollows, and where the hollows also have a chemical affinity, in line with the above discussion regarding affinity. Examples of such materials are zeolites, e.g. molecular sieve 3 A, sodium/potassium aluminosilicate.
[0048] In FIG. 4 is shown a second embodiment of a moisture absorbing device 30 . This device resembles the device according to the first embodiment in that it comprises a hollow part 34 in the interior of the plug 32 , which hollow part is located externally of the gearbox when the plug is inserted in the hole 14 . In this hollow part 24 there is arranged a moisture absorbing body 36 of a moisture absorbing material 37 . There is free communication between the interior 15 of the gearbox and the interior of the plug with the moisture absorbing material 37 . In this embodiment the moisture absorbing body 36 is illustrated as smaller than in the first embodiment, and there is a certain amount of free space between the body 36 and the inner wall of the hollow part 34 . This allows for the moisture absorbing material 37 to expand/change volume inside the hollow part 34 , during absorption of moisture. The moisture absorbing material may be any one suitable chosen from the above mentioned examples of materials, or any other suitable expanding material. The expansion of the material may be used as an indicator of how much moisture the device has absorbed. If required, and depending on the material used, the moisture absorbing material may be contained within a moisture/water permeable film or shell 38 , or similar as illustrated in FIG. 4 . This will prevent that the material spreads into the interior of the gearbox. This shell should be of an expandable or elastic material in order to accommodate an expansion of the volume of the moisture absorbing material. It should also be compatible with the used lubricant, in the same way as the moisture absorbing material as described above.
[0049] Examples of possible moisture/water permeable shell materials are polyethylene film, polyester, laminates, etc.
[0050] In FIG. 5 is illustrated a third embodiment of a moisture absorbing device according to the present invention. In this embodiment, the part of the plug 42 that forms the moisture absorbing device 40 is located in the interior 15 of the gearbox. As in the previous embodiments, the device comprises a moisture absorbing body 46 comprising a moisture absorbing material 47 . The moisture absorbing material 47 is contained in a water permeable film or shell 48 , which keeps the moisture absorbing material in place and attached to the plug 42 , while at the same time it does not prevent the material from absorbing moisture. The function corresponds to what has been described above and examples of materials are the same as given above.
[0051] In FIG. 6 is illustrated a fourth embodiment of a moisture absorbing device 50 according to the present invention. This device is integrated in an oilplug 52 , which may be e.g. an inspection oilplug inserted in an inspection hole in the gearbox. The moisture absorbing body 56 with its moisture absorbing material 58 is completely contained within the plug, by means of being placed in a hollow portion 54 provided within the plug, with an opening facing the interior 15 of the gearbox. This plug is primarily designed to be utilizable as a regular oilplug.
[0052] It may be desirable to be able to obtain information about the status of the moisture absorbing material in an easily accessible manner. It has already been described in connection with FIG. 4 how the moisture absorbing material can be of a kind that changes volume depending on the degree of moisture absorption. Alternatively, the absorbing material may be chosen to have other physical properties that are adapted to change depending on the amount of absorbed moisture. Another example is a moisture absorbing material of a kind that changes colour depending on the amount of absorbed moisture. This change of volume or colour can for example be visually checked in order to determine if the device has absorbed so much moisture that it is now time to replace it with a new device. The visual check can be made by removing the plug with the moisture absorbing device. In FIG. 1 is illustrated another alternative. The external wall of the hollow part 24 of the plug 22 is provided with a transparent portion 21 through which the absorbing material 27 can be visually inspected. Another example of a possible changing physical property is electrical resistance.
[0053] According to another alternative, illustrated in FIG. 5 , the moisture absorbing device may comprise a sensor device 45 adapted to emit a signal, reflecting the status of absorbed moisture in the moisture absorbing device, to an indicator device which indicates the status of absorbed moisture. The indicator device may for example be a lamp or a device giving a sound signal. Alternatively, the sensor device may emit a signal to a control system 1 a. This control system may be a robot controller, a remote service, a remote control device or any other type of control system or device regularly used in connection with industrial robots. The signal may be emitted via any suitable means, wireless or not. Examples of possible sensors are sensors using electrical resistance to measure moisture level.
[0054] Naturally, the different types of status indicators, volume change, colour change, sensors emitting signals to different systems, may be applied in any one of the described embodiments of the moisture absorbing device.
[0055] In all of the illustrated embodiments, the plug with the moisture absorbing device may be removable in order to be able to replace the moisture absorbing device/plug with a new one, whenever desired or necessary.
[0056] The present invention is not limited to the disclosed examples, but may be modified in many ways that would be apparent to the skilled person, within the scope of the appended claims. | 4y
|
BACKGROUND OF THE INVENTION
The invention relates to a variable-length connecting element for transmitting traction or pressure forces from and to assemblies connected to the free ends of the connecting element by means of fastening elements. The connecting element of this kind is preferably of rod-shaped design.
It is known practice to manufacture rod-shaped and variable-length connecting elements, hereinafter referred to as link rods, from a metal rod, the free ends of which are, for example, provided with threads having opposite directions. Fastening elements having, for example, an eye surrounding a bolt or an axle, can be screwed onto these threads.
Link rods are used, for example, for actuating switching and control elements for air routing in internal-combustion engines, e.g. in intake systems. The link rod connects a lever arm connected to a stepping motor with a shaft located in the intake manifold of the vehicle for controlling the timing angle of the valve flaps fastened to the shaft. The position of the stepping motor adjusts the timing angle of the flaps as required. The flaps determine the degree of swirl of the air and thus affect the emission characteristics and fuel consumption of the engine. The flaps must be adjusted to a certain position during assembly. This positioning is achieved by way of the adjustable link rod.
It must be possible to set the link rod to different lengths, in order to be able to balance out tolerance fluctuations between the components, compensate for play occurring between the components and be able to use these as universally manufacturable components with different engine geometries. In the simplest version, the length is adjusted by turning the metal rod, thus axially displacing the fastening elements mounted on the threads at the ends. Lock nuts can additionally be provided on the threads. Accordingly, rotary movement is required for fixing and alignment. In confined engine compartments, it may be difficult to gain access, with the result that this rotary movement cannot be performed without problems. In addition, it is usually only necessary to adjust the position of one fastening element. However, the rotary movement acts on both of the opposite threads provided on the ends, meaning that the end not requiring adjustment is also displaced. In this way, undesirable forces act on the assemblies connected by the link rod. This is particularly critical in relation to the sensitive stepping motor. Moreover, it is difficult, or even impossible in confined spaces, to obtain definitively reliable assembly, i.e. to achieve the necessary torque for fixing. The metal rod is usually designed as a metal casting of high weight. This contradicts the targeted reduction of weight in the automotive sector. Finally, the fixing of the fastening elements on the rod is a complex and time-consuming process.
SUMMARY OF THE INVENTION
The invention is based on the technical problem of designing a connecting element of the kind defined in the generic part of claim 1 that is lighter and can be assembled more accurately.
According to the invention, this technical problem is solved in that the connecting element is essentially of two-part design, having a receiving element and a plug-in element that can be inserted into the receiving element in a manner at least permitting longitudinal displacement and that can be fixed in the receiving element in a desired position relative to the receiving element.
As a result of the design according to the invention, the link rod with the two fastening devices can be fastened to the connecting elements and pushed together or pulled apart until the desired axial length is obtained. A fixing element locks the plug-in element in this position in the receiving element. In the preferred configuration, the fixing element is designed as an easily manufactured metal slide. As an alternative, it can also be designed as a metal ring with teeth on the flanks.
The receiving element and the plug-in element are preferably manufactured in the form of plastic injection mouldings, this not only resulting in a reduction in weight, but also offering resistance to aggressive media.
The plug-in element is customarily guided and mounted in the receiving element without play and in a manner allowing longitudinal displacement. In this context, snap-in devices formed between the receiving element and the plug-in element can prevent the components from unintentionally falling apart. When supplied, the elements are snapped together, but not adjusted, and are far easier to assemble than the rods known from the prior art. This advantage becomes particularly apparent in view of the higher degree of automation of mass production.
In the case of components that are critical in terms of movement, it is also desirable to prevent rotation of the receiving element relative to the plug-in element. It is thus sensible for the plug-in element to be guided in the receiving element in non-rotating fashion. This can be achieved, for example, by designing the receiving element with a non-round inner contour, into which the complementary, non-round outer contour of the plug-in element can be inserted in sliding fashion. An elliptical inner contour of the receiving element and an elliptical outer contour of the plug-in element are used with preference. If rotation of the two elements relative to each other is wanted, they can be provided with a round inner contour of the receiving element and a round outer contour of the plug-in element, so that the plug-in element can rotate in the receiving element.
In the preferred configuration, fixing of the plug-in element in the receiving element is achieved by using a fixing clip, which can be inserted in the desired position between the plug-in element and the receiving element. The fixing clip is slid into a receiving opening provided on the side of the receiving element for fixing in the desired position. Assembly and setting of the length can thus be performed with one hand without requiring tools. The fixing clip establishes both a non-positive and a positive connection between the plug-in element and the receiving element, as the fixing clip is provided with cutting edges that cut into the plastic during insertion. Seen in the cross-sectional view, the fixing clip is preferably designed as a U-shaped metal clip with two longitudinal limbs, running in the longitudinal direction and aligned parallel to each other, and a transverse limb connecting the longitudinal limbs.
Accordingly, the invention also relates to a fixing clip for fixing, and preventing relative movement between, a plug-in element manufactured from a plastic material and a receiving element manufactured from a plastic material into which it can be inserted, said fixing clip being capable of insertion between the elements in the desired position between the receiving element and the plug-in element in order to guarantee at least a positive connection. The link rod and/or the fixing of the relative positions of the receiving and plug-in elements by a fixing clip can, of course, also be used for other elements, such as for connecting the door knob with the door-opening mechanism. Also, the connecting element need not necessarily be of rod-shaped design. Using the fixing clip, it is also possible, for example, for several plug-in elements to be inserted in a receiving element of star-shaped design for accommodating several plug-in elements, or in an essentially Y-shaped receiving element. Accordingly, the essential aspect is the relative fixing of one plastic part in another by the fixing clip.
In order to guarantee particularly firm fixing of the fixing clip between the receiving element and the plug-in element, a preferred configuration of the fixing clip is provided with blade-like edges (cutting edges) which cut into the receiving element and/or the plug-in element during insertion between the plug-in element and the receiving element, in order to establish a positive connection between the receiving element and the plug-in element. It has proven particularly expedient to produce these cutting edges by bending the outer edges of the longitudinal limbs outwards.
In another advantageous configuration, the fixing clip is provided with means for fixing in the receiving element in various installation positions. In the simplest version, these means have at least one snap-in lug, provided on the receiving element, which can be integrally moulded on the receiving element, and at least one recess, provided on the fixing clip, which this snap-in lug engages. It is particularly advantageous if a recess for the snap-in lug is provided both in the pre-assembly position and in the position for fixing in the final condition. In the pre-assembly position, the snap-in lug engaging the recess prevents the fixing clip from unintentionally falling out of the receiving element. In the final, assembled position, the snap-in lug locks the fixing clip in the desired position.
The snap-in lug can be integrally moulded on the elements.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
An example of the invention is illustrated in the drawings and described in detail below on the basis of the figures. The figures show the following:
FIG. 1 A front view of the assembled link rod,
FIG. 2 A perspective view of the plug-in element,
FIG. 3 A perspective view of the receiving element,
FIG. 4 A front view of the procedure of fixing the plug-in element in the receiving element by means of the fixing clip,
FIG. 5 A perspective view of the fixing clip, and
FIG. 6 A view of the fixing clip from below.
DETAILED DESCRIPTION OF THE INVENTION
As can be seen from FIG. 1, the present connecting element of rod-shaped design essentially consists of receiving element 2 , in which plug-in element 4 is locked in the desired position by fixing clip 6 . Fixing clip 6 prevents relative movement between receiving element 2 and plug-in element 4 .
Receiving element 2 and plug-in element 4 are both plastic injection mouldings and the free end of each is provided with an integrally moulded ball socket 20 and 40 for fastening to assemblies. In the present configuration, ball sockets 20 and 40 are integrally injection-moulded on receiving element 2 and plug-in element 4 . The fastening elements designed as ball sockets for an eye-type bearing can also be screwed onto the link rod or connected to it by snap-fitting connections. In addition, the fastening elements need not be ball sockets, it being equally possible to use eye-like connections for surrounding axles or shafts.
The exact structure of the plug-in element can be seen particularly well in FIG. 2, which shows a perspective view of this component. Immediately following on from ball socket 40 comes the integrally moulded, rod-shaped web 41 , which becomes wider towards the outside before merging into plug-in area 42 . Plug-in area 42 extends up to the front end of plug-in element 4 . Roughly in the middle of plug-in area 42 , which is of hollow design on the inside, a snap-in tab 43 is provided, which extends in the longitudinal direction of plug-in element 4 . A snap-in lug 44 is integrally moulded on the front end of snap-in tab 43 . Snap-in tab 43 is of resilient design and, when assembled, engages opening 23 of receiving element 2 , which is described further below. In this way, receiving element 2 and plug-in element 4 are captively joined, but longitudinally adjustable relative to each other, so that the link rod can be set to any desired length. The hollow design of plug-in area 42 of plug-in element 4 means that this component is particularly suitable for injection moulding and displays very good cooling properties of the plastic.
FIG. 3 shows a perspective view of receiving element 2 without plug-in element 4 inserted. Immediately following on from ball socket 20 in the longitudinal direction comes a rod-shaped web 21 , which, roughly in the middle, merges into the wider receiving area 22 , the inside of which is of hollow design. Receiving area 22 is designed to be roughly twice as wide as web 21 . The previously described rectangular opening 23 , into which snap-in lug 44 of plug-in element 4 can be inserted in longitudinally sliding fashion, is oriented to run in the longitudinal direction of receiving area 22 . Snap-in lug 44 prevents plug-in element 4 from unintentionally falling out of receiving element 2 , as its undercut runs up against the front, short edge of opening 23 when plug-in element 4 is pulled out of receiving element 2 .
At the front end of receiving element 2 , receiving area 22 again becomes wider to form a second receiving area 24 , running at right angles to the longitudinal direction of receiving area 22 , for fixing clip 6 .
Finger-like snap-in tabs 25 and 26 are integrally moulded on the end of receiving area 24 shown at the top in the figure. These snap-in tabs 25 and 26 engage openings, to be described further below, in both sides of fixing clip 6 , thus making it possible to captively fix fixing clip 6 in various positions in receiving element 2 . Snap-in tabs 25 and 26 are integrally moulded on receiving area 24 for the fixing clip, of resilient design and provided, on the end at the front in installed position, with a snap-in lug displaying an undercut and pointing towards the inside of receiving element 4 .
A web 27 , likewise running in the longitudinal direction, is integrally moulded in receiving area 22 . When plug-in element 4 is inserted into receiving element 2 , this web 27 , which is designed with a rectangular cross-section, engages the front opening of plug-in area 42 . The inner contour of plug-in area 42 essentially corresponds to the outer contour of web 27 . The rectangular design of web 27 ensures that plug-in element 4 is guided in non-rotating and longitudinally sliding fashion in receiving element 2 and establishes the frictional connection between the elements.
In order to increase the longitudinal stiffness, receiving element 2 is provided, in the area of web 27 , with a further transverse web 28 , which runs in the longitudinal direction of receiving element 2 .
FIG. 4 shows plug-in element 4 inserted in receiving element 2 with fitted fixing clip 6 in the pre-assembly position. The link rod is delivered in this position. The connecting element is not yet fixed in its desired position in terms of length.
In this position, snap-in tabs 25 and 26 of receiving area 24 for fixing clip 6 engage recesses provided on the front end of the longitudinal limbs or fixing clip 6 , so that fixing clip 6 is fixed relative to receiving element 2 and fixing clip 6 is prevented from unintentionally falling out.
As soon as the connecting element has been set to the required length, fixing clip 6 is pressed into receiving area 24 for fixing clip 6 . This can be done with one hand and requires little space for access. When in the desired position, the fixing clip is inserted completely into receiving area 24 , as illustrated in FIG. 1 . During insertion, edges provided on the longitudinal limbs of fixing clip 6 cut into the plastic of receiving element 2 and plug-in element 4 . Once in the desired position, the longitudinal limbs of fixing clip 6 reach around the outside of plug-in area 42 . Fixing clip 6 thus establishes a positive and non-positive connection between both receiving element 2 and plug-in element 4 , meaning that the creep of the plastic is compensated for. Once fixing clip 6 is completely inserted, the elements are inseparably connected to each other.
FIG. 5 shows an enlarged, perspective view of fixing clip 6 . Fixing clip 6 consists of an essentially U-shaped, bent metal part with two essentially parallel longitudinal limbs 60 and 61 , which are integrally connected by transverse limb 62 . The longitudinal edges of longitudinal limbs 60 and 61 are provided with cutting edges 63 to 70 , which are of wing-like design and likewise integrally moulded on the longitudinal limbs. Cutting edges 63 to 70 are designed as tab-like extensions that are bent into the desired position. They have an arc-shaped curvature. Cutting edges 63 , 65 , 67 and 69 are bent further inwards in relative terms. These cutting edges cut into plug-in area 42 of plug-in element 4 when in the installed position, whereas cutting edges 64 , 66 , 68 and 70 , which are bent further outwards, cut into the inside of receiving area 24 for the fixing clip in the installed position. Accordingly, cutting edges 64 , 66 , 68 and 70 project further from longitudinal limbs 60 and 61 of fixing clip 6 . The different radii of curvature of cuttings edges 63 to 70 of fixing clip 6 can be seen particularly well in FIG. 6, which shows a face-end view of fixing clip 6 as per FIG. 5 from below. Compared to the others, cutting edges 63 , 65 , 67 and 69 are offset towards the front on longitudinal limbs 60 , 61 in relation to transverse limb 62 and are designed to be longer than the other cutting edges, in order to achieve a particularly firm connection to plug-in element 4 .
Depending on the arrangement, cutting edges 63 to 70 can be designed to be of different lengths and bent with different radii.
Longitudinal limbs 60 and 61 of the fixing clip are provided with rectangular recesses 71 to 74 , the longitudinal dimension of which lies transverse to longitudinal limbs 60 and 61 . In assembled condition, snap-in tabs 25 and 26 of receiving element 2 engage these recesses 71 to 74 , in order to fix fixing clip 6 in the pre-assembly position by means of openings 71 and 73 , which are located at the front in relation to transverse limb 62 , and in the desired final assembly position by means of rear openings 72 and 74 . Fixing in front openings 71 and 73 captively retains fixing clip 6 in receiving element 2 in the pre-assembly position, as illustrated in FIG. 4 .
Provided on the outside of longitudinal limbs 60 and 61 are elongated fixing ribs 75 to 78 , which project from longitudinal limbs 60 and 61 and ensure a play-free fit of longitudinal limbs 60 and 61 within receiving area 24 in the final assembly position. These fixing ribs 75 to 78 are formed by cutting around three sides of a rectangular area which is then pressed together with the side connected to fixing clip 6 , thus forming an area that projects from the plane of longitudinal limbs 60 and 61 in essentially triangular fashion.
List of Reference Numbers
2 receiving element
4 plug-in element
6 fixing clip
20 ball socket
21 web
22 receiving area
23 opening
24 receiving area for the fixing clip
25 snap-in tab
26 snap-in tab
27 web
28 transverse web
40 ball socket
41 web
42 plug-in area
43 snap-in tab
44 snap-in lug
60 longitudinal limb
61 longitudinal limb
62 transverse limb
63 - 70 cutting edge
71 - 74 opening
75 - 78 fixing rib | 4y
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a continuous process for the manufacture of a nitrogen-rich gas stream by the partial oxidation of a hydrocarbonaceous feed with air. More specifically, the present invention pertains to the production of a misture of inert gases substantially comprising N 2 , A and CO 2 .
2. Description of the Prior Art
Hydrocarbonaceous feedstocks, e.g. petroleum oil, have been reacted previously with a free oxygen-containing gas in the presence of steam to produce gaseous mixtures principally comprising H 2 and CO. For example, see coassigned U.S. Pat. No. 3,097,081 -- Du Bois Eastman et al. The free oxygen-containing gas is usually substantially pure oxygen, e.g. 95 mole % O 2 or more, in order to reduce the amount of nitrogen in the product gas.
SUMMARY
The subject process relates to the production of a continuous stream of nitrogen-rich gases by the partial oxidation of a hydrocarbonaceous feed with air. A stream of inert gas substantially comprising nitrogen, argon and carbon dioxide may be produced. The product gas contains substantially no gaseous nitrogen oxide compounds, no particulate carbon, and no free oxygen gas. In the process, a hydrocarbonaceous feedstock containing substantially no metals nor noncombustible materials is reacted with air by partial oxidation. The atomic ratio of free oxygen in said air to carbon in said hydrocarbonaceous fuel is in the range of about 1.7 to stoichiometric, or preferably 0.2 less than stoichiometric. The weight ratio of air to hydrocarbonaceous fuel may be in the range of about 7 to 22. The reaction takes place in a free-flow, unpacked, refractory-lined gas generator, free from catalyst, at a temperature in the range of about 1300° to 3000° F. and a pressure in the range of about 1 to 250 atmospheres. Optionally, by further processing, including drying and conventional gas purification techniques, various mixtures of inert gases comprising nitrogen, carbon dioxide and argon may be obtained.
DESCRIPTION OF THE INVENTION
In the subject continuous process a hydrocarbonaceous feed is reacted by partial oxidation with air under conditions producing a nitrogen-rich gas stream containing up to about 80 to 90 mole % (dry basis) of elemental nitrogen gas, and higher. Since the atmosphere in the reaction zone is slightly reducing, the nitrogen-rich gas produced contains substantially no oxides of nitrogen, i.e. less than 10 parts per million (ppm) of the oxides of nitrogen (NO x where x is a number in the range of 1/2 to 21/2). Further, there is substantially no free oxygen nor particulate carbon in the effluent gas from the generator.
The nitrogen-rich product gas may be used to blanket or pressurize vessels containing materials that become hazardous or corrosive in the presence of air, or it may be used to pressurize an oil well for secondary recovery of oil. Since the inert gas produced will contain substantially no NO x , the gas is noncorrosive to the steel casings used in oil wells or to steel vessels. Further, if the inert product gas is used for oil well injection, it may be injected hot without condensing the steam. Thus, the volume of gas available for injecting is increased and the oil in the formation may be heated up at the same time.
The generator for carrying out the partial oxidation reaction in the subject process preferably consists of a compact, unpacked, free-flow, noncatalytic, refractorylines steel pressure vessel of the type described in coassigned U.S. Pat. No. 2,809,104 issued to D. M. Strasser et al, which patent is incorporated herewith by reference. The nitrogen-rich effluent gas stream from the gas generator may have the following composition in mole % (wet basis): N 2 53 to 74; CO 2 4 to 13; A 0.65 to 0.95; H 2 nil to 20; CO nil to 15; H 2 O 8 to 19; COS nil to 0.05; H 2 S nil to 0.3; NO x less than 10 ppm; and particulate carbon less than 100 ppm.
Optionally, by conventional gas drying and purification techniques, inert gas mixtures of different compositions may be derived from the effluent stream from the gas generator comprising N 2 , A and CO 2 . For example, inert gas compositions (1) and (2) below in mole % may be obtained: (1) N 2 84 to 92, CO 2 7 to 15, and A 0.9 to 1.1; and (2) N 2 98.8 to 98.9, and A 1.1 to 1.2.
A wide variety of hydrocarbonaceous fuels containing substantially no metals nor noncombustible materials are suitable as feedstocks for the partial oxidation process, either alone or in combination with each other. The hydrocarbonaceous feed may be gaseous, liquid or solid. The hydrocarbonaceous feeds include fossil fuels such as: various liquid hydrocarbon fuels including petroleum distillates, liquefied petroleum gas, naphtha, kerosine, gasoline, gas oil, fuel oil, coal oil, shale oil, tar sand oil, aromatic hydrocarbons such as benzene, toluene, xylene fractions, coal tar, furfural extract of coker gas oil, and mixtures thereof. Suitable liquid hydrocarbon fuel feeds as used herein are by definition liquid hydrocarbonaceous fuel feeds that have a gravity in degrees API in the range of about -20 to 100.
Included also by definition as a hydrocarbonaceous fuel are liquid oxygenated hydrocarbonaceous materials, i.e. liquid hydrocarbon materials containing combined oxygen, including alcohols, ketones, aldehydes, organic acids, esters, ethers, oxygenated fuel oil and mixtures thereof. Further, a liquid oxygenated hydrocarbonaceous material may be in admixture with one of said liquid petroleum materials.
Included also are pumpable slurries of solid hydrocarbonaceous fuels, e.g. particulate carbon and other ash-free carbon-containing solids in a liquid hydrocarbon fuel and mixtures thereof. By definition, gaseous hydrocarbonaceous fuels include natural gas, methane, ethane, propane, butane, pentane, water gas, coke-oven gas, refinery gas, acetylene tail gas, ethylene off-gas, and mixtures thereof. Both gaseous and liquid fuels may be mixed and used simultaneously and may include paraffinic, olefinic, naphthenic and aromatic compounds.
In conventional partial oxidation procedures, it is normal to produce from ordinary hydrocarbonaceous fuel feeds about 0.2 to 20 weight percent of free carbon soot (on the basis of carbon in the hydrocarbonaceous fuel feed). The free carbon soot is produced in the reaction zone of the gas generator, for example, by cracking hydrocarbonaceous fuel feeds. Carbon soot will prevent damage to the refractory lining in the generator by constituents which are present as ash components in some residual oils. In conventional synthesis gas generation processes with heavy crude or fuel oil feeds, it is preferable to leave about 1 to 3 weight percent of the carbon in the feed as free carbon soot in the product gas. With lighter distillate oils, progressively lower carbon soot yields are maintained. However, since the hydrocarbonaceous fuel feeds in the subject process are specified as being free from metals and ash-free, e.g. no noncombustible solids, carbon soot is not required in the reaction zone to protect the refractory lining and substantially all of the particulate carbon produced may be converted into carbon oxides.
Particulate carbon and the oxides of nitrogen may be eliminated from the subject process gas stream primarily by regulating the oxygen to carbon ratio (O/C, atoms of oxygen in oxidant per atom of carbon in hydrocarbonaceous feed) in the range of about 1.7 to stoichiometric and preferably 0.2 less than stoichiometric, wherein by definition the term "stoichiometric" means the stoichiometric number of atoms of oxygen theoretically required to completely react with each mole of hydrocarbonaceous feedstock to produce carbon dioxide and water.
Thus, the (O/C, atom/atom) ratio may be in the range of about 1.7 to 4.0 and preferably 2.0 to 3.8 for gaseous hydrocarbonaceous fuels; and in the range of about 1.7 to 3.0 and preferably 2.0 to 2.8 for liquid hydrocarbonaceous fuels. When the O/C atomic ratio reaches stoichiometric, the moles of H 2 and CO in the product gas theoretically drop to zero. The weight ratio of air to hydrocarbonaceous fuel may be in the range of about 7 to 22. In the above relationship, the O/C ratio is to be based upon the total of free oxygen atoms in the oxidant stream plus combined oxygen atoms in the hydrocarbonaceous fuel feed molecules.
In order to operate the subject generator over the entire O/C range, i.e. about 1.7 to 4.0, additional cooling may have to be provided in some cases to keep the reaction temperature from exceeding 3000° F. In the subject process, the nitrogen in the air reactant is sufficient to act as the temperature moderator and will prevent the reaction zone temperature from exceeding 3000° F. when the O/C atomic ratio is 3 and below for a gaseous hydrocarbonaceous fuel, or when the O/C atomic ratio is 2 and below for a liquid hydrocarbonaceous fuel. In such instance, for example, no supplemental H 2 O other than that normally found in the reactant streams need be introduced into the reaction zone as a temperature moderator since the nitrogen in the air is an adequate temperature moderator.
However, when the O/C atomic ratios exceed these specified ranges, then some form of additional cooling may be used. Thus, in the subject process, the reaction temperature may be maintained at a maximum of 3000° F. when the hydrocarbonaceous fuel is in the gaseous phase and the O/C atomic ratio is above 3.0 to 4.0 or when said hydrocarbonaceous fuel is in the liquid phase and the O/C atomic ratio is above 2.0 to 3.0 by recycling a cooled portion of the effluent inert gas stream to the reaction zone. For example, sufficient effluent gas from the reaction zone may be cooled to a temperature in the range of about 80 to 300° F. by external heat exchange and then recycled to the gas generator to maintain the reaction zone at a maximum temperature of 3000° F. Alternatively, cooling of the gas in the reaction zone may be effected by installing water-cooled coils in the gas generator, or by simultaneously introducing a small amount of supplemental H 2 O from an external source into the reaction zone along with said reactants in the amount of about 0.05 to 1.0 and preferably less than 0.15 parts by weight of H 2 O per part by weight of fuel.
The hot effluent gas stream from the reaction zone of the synthesis gas generator may be cooled to a temperature in the range of about 80° to 900° F. by indirect heat exchange in a waste heat boiler. This nitrogen-rich gas stream may be used as an inert gas mixture or may be dried and purified by conventional procedures to separate any or all of the unwanted constituents.
Thus, by conventional means substantially all of the H 2 O may be removed from the process gas stream. For example, the clean process gas stream may be cooled to a temperature below the dew point of water by conventional means to condense out and separate H 2 O. Next, the feed stream may be substantially dehydrated by contact with a desiccant such as alumina.
In other embodiments, by conventional gas purification methods including, for example, cryogenic cooling and solvent absorption, H 2 , CO and acid gas (CO 2 , H 2 S and COS) may be removed; or alternately, only the sulfur-containing gases (if present) and not the CO 2 may be separated from the effluent gas from the gas generator. For example, the dry process gas stream may be cooled to a temperature near the triple point in the range of about -70° to -50° F. to condense out and separate a liquid stream comprising from about 0 to 70 volume percent of the CO 2 , H 2 S and COS originally present (depending upon the pressure and the amount present in the raw gas). Further purification of the process gas stream may be effected by any suitable conventional system employing physical absorption with a liquid solvent, e.g. cold methanol, N-methyl-pyrrolidone. A simplified system in which removal of the remaining H 2 S, COS, CO 2 and H 2 O may be accomplished by physical absorption in cold methanol will be described below.
In a conventional liquid-gas absorption column, e.g. tray-type, at a temperature in the range of about -20° to -70° F. and a pressure in the range of about 25 to 150 atmospheres, about 10 to 20 standard cubic feed (SCF) of the partially purified process gas stream are contacted by each pound of cold methanol. Preferably, the pressure in the absorption column is the same as the pressure in the gas generator less ordinary drop in the lines and equipment. The solvent rate is inversely proportional to the pressure and to the solubility. Solubility is a function of temperature and the compositions of the solvent and of the gas mixture. Acid gases are highly soluble in methanol at high pressures and low temperatures. Then, when the pressure is reduced, these gases may be readily stripped from the solvent without the costly steam requirement of conventional chemical-absorption methods.
The difference in solubility between CO 2 and the gaseous sulfur compounds in methanol and in most polar solvents makes it possible to selectively remove H 2 S and COS before CO 2 removal. Further, the H 2 S and COS may be concentrated into a fraction suitable for feeding a conventional Claus unit where elemental sulfur is produced.
The process gas stream leaving the gas purification zone may have the following composition in mole %: N 2 61 to 99; A 0.75 to 1.21; H 2 nil to 23; CO nil to 17; and CH 4 nil to 1.3; CO 2 nil to 2000 ppm; H 2 S nil to 10 ppm; and COS nil to 10 ppm. This gas stream may be used as an inert blanket gas in a carburizing process or reforming furnace.
The liquid solvent absorbent leaving the gas purification zone charged with acid gas may be regenerated by suitable conventional techniques, including flashing, stripping, boiling and combinations thereof, to produce a CO 2 -rich gas stream and a separate stream of sulfur-containing gases. This H 2 S-rich gas stream may be introduced into a conventional Claus unit for the production of byproduct sulfur.
Optionally, the process gas stream leaving the acid gas absorption zone may be purified to remove the other noninert impurities. A CO-rich gas stream and a separate H 2 -rich gas stream substantially comprising 98 to 99 mole % hydrogen may be obtained thereby. Any suitable conventional system employing physical absorption with a liquid solvent may be employed for obtaining the CO-rich gas stream from the effluent gas stream leaving the acid gas absorption column. The CO-rich gas stream comprises 98 mole % CO and 2 mole % CO 2 . For example, the effluent gas stream from the acid gas scrubber may be contacted in a conventional packed or tray-type column with a countercurrent stream of cuprous acetate dissolved in aqua-ammonia solution.
In another embodiment, the effluent gas from the generator may be burned in a second stage with a controlled amount of air and optionally with a combustion catalyst to convert all of the H 2 and CO into H 2 O and CO 2 without producing soot, NO x or free oxygen in the process gas stream. The H 2 O and optionally CO 2 , H 2 S and COS may be then removed from the process gas stream in the gas purification zone in the manner previously described.
The following example is offered as a better understanding of the present invention, but the invention is not to be construed as unnecessarily limited thereto.
EXAMPLE I
The process fuel oil in this example has a gravity of 17.7° API, a gross heating value of 18,650 BTU/pound, and the following analysis in weight percent: C 86.5; H 11.2; O 0.0; N 0.5; S 1.8; ash nil; and metals nil. 357 pounds per hour of said process fuel oil at a temperature of about 60° F. are charged into the reaction zone of a free-flow, unpacked, noncatalytic, refractorylined gas generator by way of the annulus passage of a conventional annulus-type burner. Simultaneously, 39,559 standard cubic feet per hour of dry air at a temperature of about 63° F. are passed into the reaction zone by way of the center passage of said burner so as to atomize said fuel oil feed at the tip of the burner. The resulting mixture of oil and air is reacted at an autogenous temperature of about 2700° F. and at a pressure of 21 atmospheres.
44,289 standard cubic feet per hour of an inert effluent gas stream are discharged from the reaction zone having the following analysis in mole % (dry basis): N 2 69.8; CO 2 5.8; A 0.9; H 2 7.2; CO 16.2; CH 4 nil; H 2 S 0.2; COS 0.01; and NO x less than 0.5 ppm. This inert gas stream may be used for oil formation flooding or as a blanketing gas when small amounts of CO and H 2 are not objectionable.
Optionally, all of the H 2 , CO, CH 4 , H 2 S, COS and H 2 O may be removed by conventional gas purification techniques to produce an inert gas mixture comprising in mole %: N 2 91.2; CO 2 7.6; and A 1.2. This inert gas stream may be used as a pressurizing gas or as a blanketing gas.
The process of the invention has been described generally and by example with reference to an oil feedstock of particular composition for purposes of clarity and illustration only. It will be apparent to those skilled in the art from the foregoing that various modifications of the process and the materials disclosed herein can be made without departure from the spirit of the invention. | 4y
|
BACKGROUND
[0001] This application claims the priority of Korean Patent Application No. 10-2003-0029130 filed on May 7, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
[0002] 1. Field
[0003] This disclosure teaches techniques related to an RF transceiver apparatus including a receiver unit with a low noise amplifier (LNA) and a filter, and a transmitter unit with a power amplifier and a filter, and a UWB signal transceiving method. More particularly, the teachings relate to techniques for overcoming interference which may be produced in a frequency band overlapped with a frequency band of radio communications currently used in an RF transceiver apparatus using ultra wide band (UWB) technology.
[0004] 2. Description of the Related Art
[0005] [0005]FIG. 1 is a schematic diagram showing a related art radio frequency (RF) transceiver apparatus. As shown in FIG. 1, when the RF system is in receive mode, a switch is connected to an input terminal of a low noise amplifier (LNA). RF signals input to an antenna connected to the LNA are transmitted to a filter via the LNA. The RF signals are transmitted further to a down converter via the filter when a carrier is used with the system. In case if no carrier is used, the RF signals are transmitted directly to a demodulator.
[0006] When the RF system is in transmit mode, the switch is connected to an output terminal of a power amplifier. When a carrier is used, the signals after passing through an up converter and a filter are amplified in the power amplifier. They are then transmitted, as electrical energy, into space through the antenna. When a carrier is not used, modulated signals are amplified in the power amplifier after passing through the filter. They are then transmitted through the antenna.
[0007] Increasingly, wireless communication system available for use in a number of wireless local area network (WLAN) and wireless personal area network (WPAN) require data transmission rates as high as those used in wired communication system. Such a need is met only if a UWB (ultra wide band) is used. UWB has a data rate that is the highest among currently used WLAN or WPAN wireless communication systems. Since a bandwidth of at most 200 to 300 MHz is generally employed in such a related art RF transceiver apparatus, it is not so difficult to construct the LNA, the power amplifier and the filter. Further, since a specific predetermined narrow band is used, the band rarely interferes with the other systems.
[0008] However, several problems are encountered if an UWB system having a bandwidth of several hundred MHz or GHz is used. An acute problem in using the UWB is that the UWB uses predetermined frequency bands that are already used by other commercial wireless communication systems. There is a strong possibility that a malfunction in the UWB system may be produced in a specific frequency band overlaps with that used by the other radio communication systems, because signal power thereof is low and receiver sensitivity is also accordingly low. Further, since the LNA, the power amplifier, the filter, and the like, which are used in a UWB system, should cover the broad bandwidth, they cannot exhibit good performance throughout the entire frequency band of interest. As a result, some problems such as signal distortion may occur in some frequencies.
[0009] Therefore, there is a need for an apparatus that can cause a UWB system not to interfere with, or not to be interfered by, wireless communication systems operating adjacent to the UWB system.
SUMMARY
[0010] To overcome some of the disadvantages discussed above, there is provided a UWB receiver comprising at least one communication module with a limited working band whose on/off state can be controlled. The UWB receiver is adapted to detect power intensity of a received radio signal in the limited working band based on an on/off state of said at least one communication module. The UWB receiver is adapted to control the on/off state of the at least one communication module based on a result of the detection.
[0011] In a specific enhancement, the detected power intensity corresponds to a band that comprises a frequency at which interferences is expected.
[0012] In another specific enhancement, the receiver has a baseband controller adapted to control the on/off states of said at least one communication module, to detect the power intensity of the radio receive signals, and to control the on/off state of said at least one communication module.
[0013] More specifically, an MAC is provided for storing information on the detected band and transmit the stored information on the band to other UWB receivers.
[0014] More specifically, the information on the band is transmitted through a management frame.
[0015] More specifically, the band is stored in a physical layer header.
[0016] In another specific enhancement the at least one communication module comprises a band stop filter.
[0017] In another specific enhancement, the at least one communication module comprises a small signal amplifier.
[0018] Another aspect of the disclosed teachings is a UWB transmitter, comprising at least one communication module with limited working bands whose on/off states can be controlled. The UWB transmitter controls the on/off states of the at least one communication module to filter out a radio transmission signal in a corresponding band.
[0019] Yet another aspect of the disclosed teachings is a UWB transceiver, comprising at least one communication module. The UWB transceiver is adapted to detect power intensity of a radio receive signal by bands according to on/off states of the at least one communication module with a predetermined limited working bands. It is further adapted to control the on/off states of the at least one communication module based on the detection result, to filter out a radio receive/transmission signal in a corresponding band.
[0020] Yet another aspect of the disclosed teachings is a method of receiving UWB signals, comprising detecting power intensity of a radio receive signal according to on/off states of at least one communication module with a limited working band. The on/off state of the at least one communication is controlled in accordance with the detection result. The radio receive signal in the band are filtered out.
[0021] Yet another aspect of the disclosed teachings is a method of transmitting UWB signals, comprising: controlling on/off state of at least one communication module and filtering out a radio transmission signal in a band.
[0022] Specifically controlling the on/off state of at least one communication module further includes setting on/off state of the communication module and making an agreement on the determination result with at least one other communicating UWB receiver.
[0023] More specifically the making an agreement on the determination result includes storing information on the determination result and transmitting the stored information to the other UWB receiver.
[0024] Still another aspect of the disclosed teachings is a method of transceiving UWB signals, comprising detecting power intensity of a radio receive signal according to on/off states of at least one communication module with limited working band. The on/off states of the at least one communication module is controlled in accordance with the detection result. A radio receive/transmission signal in a band is filtered out.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The above features and advantages of the disclosed teachings will become apparent from the following description of example implementations given in conjunction with the accompanying drawings, in which:
[0026] [0026]FIG. 1 is a schematic diagram showing the configuration of a conventional RF transceiver apparatus;
[0027] [0027]FIG. 2 is a block diagram illustrating a non-limiting exemplary configuration of a UWB transceiver apparatus including a filter unit having a plurality of filters by frequency bands;
[0028] [0028]FIG. 3 is a schematic diagram showing a structure of a baseband controller embodying some aspects of the disclosed teachings;
[0029] [0029]FIG. 4 is a block diagram illustrating a non-limiting exemplary configuration of a UWB transceiver apparatus including a LNA unit with a plurality of LNAs and a power amplifier unit with a plurality of power amplifiers by frequency bands;
[0030] [0030]FIG. 5 is a flowchart illustrating a non-limiting exemplary technique for dynamically determining a frequency band to be unused in the UWB transceiver apparatus with a plurality of filters by frequency bands;
[0031] [0031]FIG. 6 is a flowchart illustrating a non-limiting exemplary technique for dynamically determining a frequency band to be unused in the UWB transceiver apparatus including a plurality of LNAs and plurality of power amplifiers by frequency bands; and
[0032] [0032]FIG. 7 is a flowchart illustrating a non-limiting exemplary technique of determining a frequency band to be unused and transceiving the signals between UWB systems where the plurality of filters, LNAs and power amplifiers are all used.
DETAILED DESCRIPTION
[0033] Hereinafter, example implementations of the disclosed teachings are described in detail with reference to accompanying drawings.
[0034] [0034]FIG. 2 is a block diagram that shows a non-limiting example of a configuration of a UWB transceiver apparatus. It includes a filter unit having a plurality of filters, each of which is capable of filtering a specific frequency band according to the disclosed teachings. Referring to FIG. 2, the UWB transceiver has a wideband LNA 220 covering all frequency bands of a UWB system, a wideband power amplifier 270 , a filter unit 230 including a plurality of filters, a demodulator 240 , a modulator 280 , a baseband controller 250 , and a medium access control (MAC) 260 .
[0035] Each of the components of the apparatus will now be described in detail. The LNA is a typical small signal amplifier. An example of a small signal amplifier is an RF device that is needed for converting a signal. Such a signal, while interpretable, has increased noise and weakened intensity as the signal passes through a number of paths in the air. The small signal amplifier is an amplifier that receives not only gain but also the noise component. In this example, a wideband LNA covering all the frequency bands of the UWB system is used.
[0036] Each of the filters constituting the filter unit is a band stop filter for selectively filtering out only a specific frequency band used in existing RF systems. Each of the band stop filters is required to filter out a specific frequency spectrum when a signal is input to the UWB receiver. Because specific frequency bands are filtered out, the UWB system does not interfere with existing wireless communication systems.
[0037] Further, it is likely that new frequency bands that may overlap with the existing frequencies may appear due to the advent of new communication devices. The band stop filter is required to dynamically cope with interference due to such newly overlapped band. For example, the filters may be arranged according to ranges of the frequency band used in the existing wireless communication systems in such a manner that a first band stop filter is used in the global positioning system (GPS) band and a second band stop filter is used in the 5 GHz wireless LAN band, etc.
[0038] A switch that can be turned on or off is attached in a parallel connection format to each filter. In this configuration, if the switch is in an ON state, the signal input is transmitted only along the shorted switch without passing through the filter with predetermined impedance. Thus, the band stop filter is in an OFF state. On the other hand, if the switch is in an OFF state, the input signal is transmitted through the filter with predetermined impedance. Thus, the band stop filter is in an ON state.
[0039] The baseband controller 250 serves to control the overall operation of processing transmission and reception of UWB pulse signals through the transceiver. As shown in FIG. 3, the baseband controller 250 comprises a power measurement unit 251 , an on-off control unit 252 and a power control unit 253 . The functions of the components will be later described in detail with reference to FIG. 3.
[0040] The MAC 260 is present in the upper layer of the physical layer and serves to manage data communication according to the UWB communication. The MAC 260 receives binary signals through the baseband controller or transfers the binary signals to be transmitted to the baseband controller. Further, the demodulator 240 serves to demodulate a data sequence of UWB pulse signals received through the antenna into original signals. The modulator 280 modulates binary data of the original signals into UWB pulse signals. The power amplifier 270 amplifies the intensity of the UWB pulse signals input from the modulator 280 via the filter so that they are suitable for UWB channel transmission.
[0041] In the receiving side of the apparatus, the order between the filter and LNA may be changed and all the filters may be located in front or to the rear of the LNA. In case of a heterodyne system or direct conversion system where the carrier is used, the signals may be moved to the baseband of the original signals. These signals are then demodulated if the signals pass through the down converter. On the other hand, in case of a baseband system or UWB system where the carrier is not used, the signals may be directly demodulated without passing through the down converter.
[0042] In the transmitting side of the apparatus, the order between the filter and power amplifier may be changed, and all the filters may be located in front of or to the rear of the power amplifier. In case of a heterodyne system or direct conversion system where a carrier is used, the modulated baseband signals are up-converted into the band around the carrier frequency. Here, the up-converted RF signals have a band that is to be sent to a specific band space. In a system where a carrier is not used, the modulated signals are directly sent to the filter without performing the up-conversion process.
[0043] [0043]FIG. 3 is a schematic diagram showing an exemplary structure of the baseband controller 250 embodying some aspects of the disclosed teachings. The power measurement unit 251 of the baseband controller 250 measures the power intensity of the RF signal entering the band space as each of the filters is turned on or off, thereby turning on or off each of the corresponding LNAs. As a result of the measurement, if there is power variation greater than a predetermined value, the power measurement unit 251 determines that another wireless communication system is using the band.
[0044] The on-off control unit 252 serves to filter out signals in the band that are not to be used. This is done by controlling the turning on or off each of the filters. More specifically, the on-off control unit 252 can dynamically turn on or off the switch by turning on the band stop filter corresponding to a band, which is determined to be used by the other wireless communication system in the power measurement unit 251 , and turning off other band stop filters. Further, the on-off control unit 252 serves to filter out signals in the band that are not to be used, by controlling the operation of turning on or off each of the LNAs. More specifically, the on-off control unit 252 can dynamically turn on or off the switch by turning off the LNA corresponding to a band that has been determined to be used by the other wireless communication systems in the power measurement unit 251 , and turning on the other LNAs.
[0045] Further, the power control unit 253 controls the intensity of the transmission power of the UWB pulse signals according to the signal to noise ratio (SNR) of the received signals. Since the respective components of the baseband controller 250 so constructed operate independently from one another, additional components may be added thereto depending on the data transmission method or only some of the components shown in FIG. 3 may be included therein. For example, the baseband controller 250 may be comprised of only the power measurement unit 251 and the on-off control unit 252 . If there is an additional need to control the intensity of the transmission power, the power control unit 253 may be further added to the baseband controller 250 .
[0046] [0046]FIG. 4 is a block diagram illustrating an exemplary configuration of the UWB transceiver apparatus including the LNA unit with a plurality of LNAs and the power amplifier unit with a plurality of power amplifiers arranged according to the frequency bands. Only the parts different from the UWB transceiver apparatus shown in FIG. 2 are explained in detail herein.
[0047] Referring to FIG. 4, the exemplary UWB transceiver apparatus comprises the LNA unit 420 with a plurality of LNAs, the power amplifier unit 470 with a plurality of power amplifiers, the wideband filter 430 covering all the bands of the UWB system, the demodulator 240 , the modulator 280 , the baseband controller 250 , and the MAC 260 . The LNA unit 420 includes a plurality of LNAs and a LNA combiner 421 for collecting the outputs from the plurality of LNAs and then sending the outputs to a single port. The power amplifier unit 470 includes a plurality of power amplifiers and a power amplifier combiner 471 for collecting the outputs from the plurality of power amplifiers and then sending the outputs to a single port. Further, the wideband filter 430 covers all the bands used in the UWB system.
[0048] When the UWB receiver receives signals, it is designed such that the LNA and power amplifier are not used for a specific frequency band spectrum. Thus, since a band that will not be used upon transmission and reception due to its overlapping with other communication systems is not subjected to an amplification process through the relevant LNA and power amplifier, the UWB system cannot interfere with the existing wireless communication systems and can dynamically cope with interference due to the existing overlapped bands as well as overlapped bands that are likely to appear due to the advent of new communication devices in the future. For example, the filters may be arranged according to the ranges of frequency bands used in the existing wireless communication systems in such a manner that a first LNA and power amplifier are used in the global positioning system (GPS) band and a second LNA and power amplifier are used in the 5 GHz wireless LAN band, for example.
[0049] An exemplary implementation that combines the structures of FIGS. 2 and 4 are combined with each other can also be created. In such a combined structure, the transceiver system comprising the filter unit with a plurality of filters, the LNA unit with a plurality of LNAs, and the power amplifier unit with a plurality of power amplifiers are combined. Here, if only interference occurring due to a band overlapping with existing wireless communication systems becomes a problem, the problem can be solved only through the embodiment shown in FIG. 2 or FIG. 4, respectively.
[0050] The LNA, the power amplifier, the filter and the like used in the UWB system is required to cover the wideband. Therefore, good performance cannot be uniformly obtained throughout the entire frequency band even though a wideband LNA, filter and power amplifier are used. Further, another problem such as the distortion of signals may be produced in a certain frequency band. On the other hand, if the LNA, filter and power amplifier are provided in each of the frequency bands as described in the exemplary implementations embodying the disclosed teachings, problems such as the distortion of signals will not occur.
[0051] [0051]FIG. 5 is a flowchart illustrating a technique for dynamically determining a frequency band that is not to be used in the UWB transceiver apparatus using a plurality of filters. The steps in the flowchart of FIG. 5 are performed at a regular interval of time or when the UWB transceiver apparatus is turned on. First, all the filters shown in FIG. 2 are turned off (S 510 ). Then, one of the filters is turned on and the remaining filters remain turned off. Next, the next filter is turned on and the other filters remain turned off. This process is performed for all the filters (S 520 ).
[0052] Through the above processes, it is possible to determine as to which bands the interferences occur. For example, where the second filter can cover the 5 GHz wireless LAN band that is currently used by another apparatus, the first to n-th filters are sequentially turned on one by one at a regular interval of time or when the UWB transceiver apparatus is turned on. Then, the total intensity of the RF signals coming into the band space will be significantly lowered when the second filter is turned on. Therefore, the UWB system can perceive the presence of the 5 GHz wireless LAN band through the above process.
[0053] Generally speaking, if the power of the RF signals entering the band space is significantly reduced when a specific band stop filter is turned on (S 530 ), it is determined that the filter for use in the band is turned on (S 540 ). Otherwise, it is determined that the relevant filter is turned off (S 550 ). Subsequently, it is checked whether the relevant filter is the last n-th filter (S 560 ). If so, the process goes to next step S 570 . Otherwise, the process returns to step S 520 . According to the determined result, the UWB transceiver apparatus turns on only the relevant filters for use in a band from which interference is expected and turns off the other filters (S 570 ). Thus, the UWB board will not be damaged even though higher power is input through the interference band.
[0054] Further, information on the relevant band so determined is transmitted to a communicating UWB transceiver apparatus (S 580 ). The two UWB transceiver apparatuses make a mutual agreement that they will not use the relevant band (S 590 ). A method of making an agreement between the two UWB transceiver apparatuses that they will not use a specific band for mutual communication may include a method of producing a management frame in the MAC and transceiving the frame between the apparatuses. Alternately, this information can be included in a physical layer header and communicated to each other during the wireless data transmission/reception. In such a case, a new frame may be produced, or “reserved bits” of the existing frame may be used.
[0055] [0055]FIG. 6 is a flowchart illustrating an exemplary technique for dynamically determining a frequency band that is not to be used in the UWB transceiver apparatus including a plurality of LNAs and a plurality of power amplifiers. The steps in the flowchart of FIG. 6 are performed at a regular interval of time or when the UWB transceiver apparatus is turned on. First, all the filters shown in FIG. 4 are turned on (S 610 ). Then, one of the filters is turned off and the remaining filters remain turned on. Next, the next filter is turned off and the other filters are turned on. This process is performed for all the filters (S 620 ). Through the above processes, it is possible to determine as to which bands the interferences occur.
[0056] As such, if the power of the RF signals entering the band space is significantly reduced when a specific LNA is turned off (S 630 ), it is determined that the LNA for use in the band is turned off (S 640 ). Otherwise, it is determined that the relevant filter and power amplifier are turned on (S 650 ). Subsequently, it is checked whether the relevant LNA is the last n-th LNA (S 660 ). If so, the process goes to step S 670 . Otherwise, the process returns to step S 620 . According to the determined result, the UWB transceiver apparatus turns off only the relevant LNA for use in the interference band and turns on the other LNAs (S 670 ). Further, information on the relevant band so determined is transmitted to a communicating UWB transceiver apparatus (S 680 ), and then, the two UWB transceiver apparatuses make a mutual agreement that they will not use the relevant band (S 690 ).
[0057] [0057]FIG. 7 is a flowchart illustrating a process of determining a frequency band not to be used and transceiving signals between the UWB systems where a plurality of filters, LNAs and power amplifiers are all used. First, the filter unit, the LNA unit and the power amplifier unit are set on the basis of the agreement process as described in the embodiment shown in FIG. 5 or FIG. 6 (S 710 ). Then, the modulator of the first UWB transceiver apparatus receives binary signals to be transmitted from the baseband controller (S 720 ). Next, the received binary signals are modulated into UWB pulse signals through the modulator (S 730 ).
[0058] Where a carrier is used, the signals should first pass through a down converter and be then subject to the modulation process. Otherwise, the signals are directly transmitted to the modulator. The modulated signals pass through the filter unit on the transmitting side of the UWB system, in which the signals in the band to be unused are filtered out or stopped (S 740 ). Thereafter, only the signals in the band to be used are amplified through the power amplifier unit (S 750 ), and the UWB pulse signals are then transmitted through the antenna (S 760 ).
[0059] The transmitted signals are propagated through the UWB channel in the air and are received through the antenna of the second UWB transceiver apparatus (S 770 ). Then, the received signals are amplified by passing through the LNA unit (S 780 ), and the signals in the band not to be used are filtered out or stopped through the filter unit on the receiving side of the UWB system (S 790 ). Only the filtered pulse signals are demodulated into binary signals (S 795 ). Where a carrier is used, the pulse signals should pass through the filter unit and then be transmitted to the down converter. Where a carrier is not used, the pulse signals are directly sent to the demodulator. The binary signals having passed through the demodulator are transmitted to the baseband controller (S 799 ).
[0060] Although the disclosed teachings have been described in connection with the disclosed embodiments thereof, it is not limited to these embodiments thereof. Therefore, it is apparent to those skilled in the art that various changes and modifications can be made thereto without departing from the scope and spirit of the present invention defined by the appended claims. | 4y
|
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of a U.S. Provisional Application Ser. No. 60/590,632 filed Jul. 23, 2004.
FIELD OF THE INVENTION
[0002] The present invention relates to thermoelectric devices which utilize a thermal gradient to generate electrical power. More particularly, the present invention relates to an expeditious method of fabricating a CoSb 3 -based thermoelectric (TE) device by using a spark plasma sintering (SPS) process to attach a high-temperature electrode to a buffer layer and to attach the buffer layer to p-type and n-type legs of the device.
BACKGROUND OF THE INVENTION
[0003] With the recent discovery of high-efficiency thermoelectric (TE) materials, potential applications of TE technology have attracted worldwide interest. TE devices can be used for cooling and power generation purposes in a variety of applications and have the potential for high reliability, long life and environmentally safe operation. While most of the work in thermoelectric technology has focused on the development of new materials, of equal importance is investigation of the fabrication issues regarding incorporation of the newly-developed materials into TE devices.
[0004] Filled skutterudites are prospective high-efficiency materials for TE power generation by TE devices having a hot side temperature (T H ) of between 450 degrees C. and 600 degrees C. For simplicity and proof of concept, binary n-type and p-type CoSb 3 skutterudites are used to fabricate the n-type and p-type legs of thermoelectric devices. Copper is used as the electrode material at the cold side of the device.
[0005] Because of the relatively high T H at the hot side of the device, selection of the high-temperature electrode material is important. First, the high-temperature electrode material should neither react with CoSb 3 nor diffuse into the CoSb 3 at the T H . Second, the high-temperature electrode material should have high electrical and thermal conductivity values. Third, the material should have a thermal expansion coefficient which is comparable to that of CoSb 3 to prevent breakage or cracking. Finally, the material should not be oxidized easily.
[0006] Due to its high electrical conductivity (18.1 10 6 Ω −1 m −1 ) and thermal conductivity (138 W/mK), molybdenum (Mo) is a good candidate for the high temperature electrode material. In addition, its room temperature thermal expansion coefficient is close to that of CoSb 3 . The room temperature thermal expansion coefficients for both n-type and p-type CoSb 3 are about 8.0×10 −6 K −1 . Furthermore, Mo does not oxidize easily. However, because it has a high melting point (2623 degrees C.), Mo is difficult to be directly joined to CoSb 3 , which has a melting point of 876 degrees C.
[0007] Therefore, utilization of a titanium buffer layer between the molybdenum high-temperature electrode and the CoSb 3 n-type and p-type legs is needed in the fabrication of a thermoelectric device since titanium has relatively large electrical and thermal conductivities, a thermal expansion coefficient which is comparable to that of CoSb 3 , is oxidation-resistant and has a melting point which is much lower than that of molybdenum.
SUMMARY OF THE INVENTION
[0008] The present invention is generally directed to a novel method of fabricating a thermoelectric device having a high efficiency and durability. The method includes attaching a high-temperature electrode layer, typically molybdenum, to a buffer layer, typically titanium, using spark plasma sintering (SPS); forming adjacent composite binary skutterudite CoSb 3 n-type and p-type layers using SPS; attaching the buffer layer to the composite n-type and p-type layers using SPS; attaching a low-temperature electrode layer to the composite n-type and p-type layers; and cutting between the composite n-type and p-type layers to form separate n-type and p-type legs which connect the high-temperature electrode layer to the low-temperature electrode layer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The invention will now be described, by way of example, with reference to the accompanying drawings, in which:
[0010] FIG. 1 is a cross-section of a high-temperature electrode subjected to an ultrasonic pretreatment process according to the method of the present invention;
[0011] FIG. 2 is a cross-section of an electrode/buffer layer fabricated according to the method of the present invention;
[0012] FIG. 3 is a schematic illustrating formation of composite n-type and p-type layers using a spark plasma sintering (SPS) technique according to the present invention;
[0013] FIG. 4 is a schematic illustrating attachment of an electrode/buffer layer to composite n-type and p-type layers using SPS according to the present invention;
[0014] FIG. 5 is a perspective view of a thermoelectric device fabricated according to the invention, prior to cutting between the composite n-type and p-type layers;
[0015] FIG. 6 is a perspective view of a thermoelectric device illustrating cutting between the composite n-type and p-type layers to form the connecting n-type and p-type legs in fabrication of the device according to the present invention;
[0016] FIG. 7 is a flow diagram which illustrates sequential process steps carried out according to the method of the present invention;
[0017] FIG. 8 shows scanning electron micrograph (SEM) images (top panels) and elemental composition intensities (bottom panels) obtained by electron probe microanalysis (EPMA) of the CoSb 3 , Ti and Mo composite and the CoSb 3 and Ti interface of a thermoelectric device fabricated according to the method of the present invention;
[0018] FIG. 9 shows SEM images (top panel) and elemental composition intensities obtained by EPMA (bottom panels) of the CoSb 3 and Ti interface after 1000 hours of thermal fatigue testing at 500 degrees C.; and
[0019] FIG. 10 is a graph which illustrates voltage drop as a function of position across the CoSb 3 and the electrode interface before and after thermal fatigue testing.
DETAILED DESCRIPTION OF THE INVENTION
[0020] The present invention contemplates a novel method of fabricating a thermoelectric device having a high efficiency and durability. According to the method, spark plasma sintering (SPS) is used to attach a typically molybdenum high-temperature electrode layer to a typically titanium buffer layer to form an electrode/buffer layer. SPS is then used to form adjacent composite binary skutterudite CoSb 3 n-type and p-type layers and to attach the electrode/buffer layer to the n-type and p-type composite layers. A low-temperature electrode layer is attached to the composite n-type and p-type layers, typically using a conventional soldering method. Finally, the composite n-type and p-type layers are cut to form separate n-type and p-type legs which connect the high-temperature electrode layer to the low-temperature electrode layer in the finished thermoelectric device. The use of SPS as a rapid sintering technique facilitates the rapid fabrication of n-type and p-type legs in the thermoelectric device.
[0021] Sequential process steps carried out according to the thermoelectric device fabrication method of the present invention are shown schematically in FIGS. 1-6 and as a flow diagram in FIG. 7 . As a first step according to the method, as shown in FIG. 1 and indicated in step 1 of FIG. 7 , a high-temperature electrode foil 12 , which is preferably a molybdenum foil having a thickness of typically about 0.5˜1.5 mm, is pretreated ultrasonically for typically about 5˜10 minutes with SiC or diamond sand 13 having a particle size of typically about 0.5˜5 μm. This pre-treatment step imparts roughness to the surface 12 a of the high-temperature electrode foil 12 .
[0022] As indicated in step 2 of FIG. 7 , buffer layer material is then placed on the pre-treated surface 12 a of the high-temperature electrode foil 12 . The buffer layer material is preferably a titanium powder (99.9% pure, 200˜400 mesh) or a titanium foil (99.9% pure) which is laid on the pretreated surface 12 a of the high-temperature electrode foil 12 . As indicated in step 3 and shown in FIG. 2 , the buffer layer 14 is attached to the pretreated surface 12 a of the high-temperature electrode foil 12 to define an electrode/buffer layer 11 . This step may be carried out using SPS under vacuum or an inert gas atmosphere for about 5˜30 minutes, with about 20˜60 MPa pressure, and at a temperature of about 950˜1000 degrees C.
[0023] A SPS (spark plasma sintering) apparatus 24 , which may be conventional, is shown schematically in FIG. 3 . The SPS apparatus 24 includes an upper punch 28 and a lower punch 30 to which are attached thermocouples 26 . A DC pulse generator 36 is electrically connected to the upper punch 28 and lower punch 30 .
[0024] As shown in FIG. 3 and indicated in step 4 of FIG. 7 , powders of p-type and n-type CoSb 3 are loaded as alternative p-type layers 16 and n-type layers 18 between the upper punch 28 and the lower punch 30 of the SPS apparatus 24 . The desired cross-sectional thicknesses of the p-type and n-type legs in the fabricated thermoelectric device determine the quantity of p-type and n-type powders loaded in the SPS apparatus 24 . In step 5 , the p-type layers 16 and n-type layers 18 are then sintered as a composite layer at a temperature of between typically about 560 degrees C. and 590 degrees C. with a pressure 32 of typically about 20 to 80 MPa.
[0025] In step 6 , the surface of the buffer layer 14 is next pre-treated ultrasonically with 0.5˜5 μm diamond sand 13 , as further shown in FIG. 2 , for typically about 5˜10 minutes to impart surface roughness to the buffer layer 14 . As indicated in step 7 and shown in FIG. 4 , the electrode/buffer layer 11 , which includes the high-temperature electrode foil 12 and the buffer layer 14 previously sintered together in step 3 , is next loaded with the composite p-type layers 16 and n-type layers 18 in the SPS apparatus 24 . The pretreated surface of the buffer layer 14 is placed into contact with the composite p-type layers 16 and n-type layers 18 . As indicated in step 8 , the electrode/buffer layer 11 and composite layers are then subjected to spark plasma sintering at a temperature of between typically about 560˜590 degrees C. with typically about 20˜80 MPa pressure for about 5˜60 minutes. The relatively low melting point of the titanium buffer layer 14 facilitates attachment of the high-temperature electrode foil 12 to the composite p-type layers 16 and n-type layers 18 .
[0026] As indicated in step 9 and shown in FIG. 5 , a low-temperature electrode 20 is next attached to the ends of the composite p-type layers 16 and n-type layers 18 which are opposite the electrode/buffer layer 11 . Preferably, the low-temperature electrode 20 is copper. The low-temperature electrode 20 may be formed using conventional soldering techniques known to those skilled in the art.
[0027] As indicated in step 10 and shown in FIG. 6 , fabrication of the thermoelectric device 10 may be completed by cutting a central saw line 22 through the high-temperature electrode 12 and buffer layer 14 and to the low-temperature electrode 20 to define a central p-type leg 16 a and n -type leg 18 a . This may be carried out using a conventional wire saw. In similar fashion, peripheral saw lines 23 may be cut through the low-temperature electrode 20 and to the buffer layer 14 to define a peripheral p-type leg 16 b and a peripheral n-type leg 18 b . Accordingly, responsive to a thermal gradient established between the high-temperature electrode 12 and the low-temperature electrode 20 , the central p-type leg 16 a , the peripheral p-type leg 16 b , the central n-type leg 18 a and the peripheral n-type leg 18 b conduct the flow of electrons from the high-temperature electrode 12 to the low-temperature electrode 20 in the finished thermoelectric device 10 . The relatively large electrical conductivity of the titanium buffer layer 14 facilitates electrical conductance between the high-temperature electrode 12 and the low-temperature electrode 20 .
[0028] FIG. 8 shows scanning electron microscopy (SEM) images (top panels) and elemental composition intensities obtained by electron probe microanalysis (EPMA, bottom panels) of the CoSb 3 , Ti and Mo composite and the CoSb 3 and Ti interface of a thermoelectric device fabricated according to the method of the present invention. The yield strength of the prepared sample is 65 MPa. The interfaces are crack-free and show no signs of significant inter-diffusion. As shown in FIG. 9 , after a 1000-hour thermal fatigue test carried out at 500 degrees C., the interfaces remain unchanged and the yield strength drops slightly to 63 MPa.
[0029] FIG. 10 shows the measured voltage drop as a function of position across the interfaces at room temperature using a 10 mA electrical current, before and after the thermal fatigue test. The contact resistances at the interfaces remain approximately unchanged after thermal fatigue testing.
[0030] While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications can be made in the invention and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the invention. | 4y
|
This is a continuation-in-part of U.S. patent application Ser. No. 07/407,603, filed Sep. 15, 1989, now abandoned.
TECHNICAL FIELD
This invention relates to improved wrappers and shrouds for use in packaging, shipping and storing shingles. In particular, the invention is directed toward use of heat deflecting wrappers and shrouds designed for use with bundles of self-sealing shingles wherein the temperature within the bundle of shingles is maintained at a substantially lower temperature than that temperature previously achieved with prior wrappers or shrouds.
BACKGROUND OF THE INVENTION
Shingles intended for use in such applications as roofing and siding building materials have developed so that most commonly available shingle products now have a self-sealing adhesive layer or strip located upon a major surface of each shingle product. The adhesive or sealant which is placed upon the shingle during the manufacturing process is temperature sensitive and the sealant will activate when a specified threshold temperature is met. The threshold or activation temperature for the sealant can be selected to closely correlate with the expected ambient temperature of the specific geographical area in which the shingles are expected to be used. Usually the activation temperature will be selected to be from 20°-60° F. higher than the expected ambient temperature. When the shingles are applied during building construction the shingle will heat up as a result of solar heat absorption and activate the adhesive. The weight of the shingles will then seal the shingles together.
Problems have been encountered in packaging such self-sealing shingles in that the shingles are often left outdoors at a construction site, or a shingle manufacturer's or retailer's storage yard. These shingles will often be exposed to solar heat ambient temperatures which may activate the sealant causing the shingles to adhere to each other. Solar heat, if not deflected from the shingles, will be absorbed by the shingle products causing the bundle of shingles to reach a temperature substantially higher than ambient. If the temperature within the bundle reaches the tab sealant activation level, the sealant will become tacky and the shingles, stacked upon each other, will adhere to one another. Thus problems are created when the shingles are stored outdoors prior to use in construction.
There are specific packaging efforts which have been directed at solving this problem of self-sealing adhesion during shingle storage. For instance, U.S. Pat. No. 3,138,251 offers a solution to the problem through the use of a light cardboard-type wrapper which is folded over the bottom, sides and ends of the bundle of shingles. The wrapper ends are folded upon themselves and mated with the uppermost shingle in the bundle to cover a substantial portion of the head and butt portions of the shingles and create a gap between the folded ends. As the shingles are stacked, the adhesive strips are in approximate alignment adjacent the area of the gap thereby separating the adhesive portions of each shingle from the other shingles resting upon it. This type of packaging, however, has proven to be costly and time consuming in its application.
A more commonly accepted method for wrapping shingle bundles is to cover the bundles with a paper wrapper. This type of wrapper, while offering brief insulating properties from exposure to solar heat, often fails to maintain the interior temperature of a bundle of shingles at a sufficiently low temperature to avoid activating the self-sealing adhesive. A release paper or film is commonly placed over the sealant strips when the shingles are stacked in a bundle. Even though a release paper is used, under certain storage conditions the shingles will still adhere to each other in the bundle.
Another problem with high temperatures due to solar heating under storage conditions is staining of the lighter colors of shingles, particularly the white shingles. It may be that the hot temperatures cause some of the oils to seep out from the base asphalt of the shingle. Prevention of extremely hot temperatures from solar loading will help alleviate this staining problem.
Recent attempts to enhance the packaging of shingle bundles have focused on the use of polyethylene films as packaging material. It is known that white polyethylene film and clear polyethylene film have been used. However, these films have shown no success in reducing the interior heat of the shingle bundle. In fact, tests have shown that both white and clear wrappers actually increase the interior heat of a bundle when compared to a paper wrapper.
Therefore, it is an object of this invention to facilitate ease of packaging of shingle bundles and pallet loads of shingle bundles.
It is a further object of this invention to package shingle bundles and pallet loads of shingle bundles in such a manner that the adhesive portions of the self-sealing shingles are maintained at a temperature which will be low enough so as not to cause the individual shingles to adhere to one another, even when exposed to solar heat.
SUMMARY OF THE INVENTION
The present invention provides a dual element wrapper or shroud consisting of a heat reflective outer layer and a heat absorptive inner layer for use in wrapping bundles of shingles or for use as a shroud for pallets containing many bundles of shingles or other roofing products. The wrapper and shroud are designed to deflect sufficient heat from the packaged shingles to reduce the temperature build-up in a bundle of shingles to prevent or minimize the temperature activated shingle sealant from causing the shingles to adhere to one another. The shingle wrapper and shroud are composed of an outer layer designed to reflect a substantial portion of the incoming heat and an inner layer which absorbs the remaining heat and causes it to scatter. The wrapper is effective in reducing the temperature build-up on the interior surface of a bundle of shingles because the two-layer combination prevents the penetration of a sufficient amount of infrared light rays to overheat the package.
According to this invention, there is provided a bundle of shingles wrapped in a dual element wrapper comprised of an outer layer of heat reflective material and an inner layer of heat absorptive material.
In a specific embodiment of the invention, the outer layer has an opacity of at least 30 percent and the inner layer has an opacity of at least 75 percent.
In another specific embodiment of the invention, the inner and outer layers are comprised of heat shrinkable plastic film. Preferably the film is a coextruded film. Most preferably the film is a coextruded polethylene film, with the inner and outer layers being coextruded to nearly equal thicknesses.
In another embodiment of the invention, the outer layer is white in color and the inner layer is silver in color.
In another embodiment of the invention, the inner and outer layers yield an overall opacity of at least 90 percent.
According to this invention, there is also provided a pallet load of bundles of shingles covered by a shroud, where the shroud is comprised of an outer layer of heat reflective material and an inner layer of heat absorptive material.
In a specific embodiment of the invention, the shroud outer layer has an opacity of at least 30 percent and the shroud inner layer has an opacity of at least 75 percent.
In another specific embodiment of the invention, the shroud inner and outer layers are comprised of a plastic film. Most preferably the film is a coextruded polethylene film, with the shroud outer layer being about three mils thick and the shroud inner layer being about one mil thick.
In an additional embodiment of the invention, the shroud outer layer is white in color and the shroud inner layer is silver in color.
In another embodiment of the invention, the shroud inner and outer layers yield an overall opacity of at least 90 percent.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph showing the temperature over time of a top shingle in a bundle and comparing the invention with a known paper wrapper and a known polyethylene wrapper.
FIG. 2 is a close-up of FIG. 1 for the time interval from 11 to 15 hours.
FIG. 3 is a graph showing the temperature over time for mid-bundle and comparing the invention with a known paper wrapper and a known polyethylene wrapper.
FIG. 4 is a close-up of FIG. 3 for the time interval from 12 to 16 hours.
FIG. 5 is a partially cut away perspective view of a bundle of shingles having a wrapper of the present invention.
FIG. 6 is a partially cut away view of a pallet load of bundles of shingles covered with a shroud of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The invention will be described in terms of packaging for shingles. As used herein, "shingles" includes any granule-covered roofing membranes, whether in the form of individual shingle pieces, or in the form of a rolled granule-covered roofing sheet.
The wrapper and shroud of the present invention are comprised of two elements: a reflective outer layer and an absorptive inner layer. The outer layer is usually of a light color designed to enhance its reflective qualities. It is preferable that the outer layer be capable of reflecting at least 50% of the radiant heat contacting it. It is believed that the use of a light color enables the outer layer to reflect visible light and long infrared waves. The second or inner layer, composed of a highly absorptive material, receives the remaining heat, usually composed mainly of short infrared waves which are not as powerful as the long infrared waves. The second layer absorbs a portion of the short infrared waves and causes them to scatter, thereby reducing the rate of heat transfer into the shingles.
In the preferred embodiment of the present invention, the wrapper or shroud is a film composed of a dual-layer film such as polyethylene. In the case of a shingle wrapper, the film is preferably heat-shrinkable. In addition to polyethylene, it is envisioned that the invention can be achieved with other forms of plastic film and with paper having a specific coating of absorptive material. For example, PVC, polyolefin, ethylene vinyl acetate and blends of these materials could be used. The invention can also be practiced using a lamination of two layers: one reflective and one absorptive.
The films of the present invention are preferably composed of a light colored outer layer, usually white, and an absorptive inner layer having a gray or silver color. There is nothing intended to be limiting by the selection of these colors as it is envisioned that any appropriate combination of reflective and absorptive colors will achieve the invention. Also, it is to be understood that the use of the term "silver" includes like colors, including gray.
In the preferred embodiment, the film of the present invention is composed of coextruded polyethylene film having a white outer layer and a silver inner layer. Each layer is 1 mil in thickness. It is clear that film products of alternative thicknesses may be successfully used. The inner and outer layers need not necessarily be of equal thickness. In the preferred embodiment of the shroud, an outer white layer is 3 mils thick and an inner silver layer is 1 mil thick.
The opacity of the white outer layer, a measure of reflectance as measured in accordance with the D1003-61 ASTM test for opacity, should be at least 30%, preferably, at least 45% and, most preferably, around 70%. Increased opacity of the white layer can be produced by doping the film during manufacture with additional pigment, such as titanium dioxide.
The opacity of the silver layer, a measure of absorption, as measured in accordance with the D1003-61 ASTM test for opacity, should be at least 75% and, preferably, around 90%. The silver color is achieved by the addition of aluminum powder pigment to the polyethylene resin. The preferred combination will result in an overall opacity measurement of 90%-93%. However, opacity measurements above 70% may be effective. Measuring the overall opacity of a dual layer coextruded film is readily determined by the ASTM test. The opacity of a single layer of a dual layer film must be determined by assessing the pigment loading of the material in that layer during the manufacturing process.
Referring to the Figures, it can be seen that the present invention has been found to be more effective in reducing temperature build-up in a bundle of shingles than the commonly used paper wrapper and the current polyethylene wrappers. The data shown in FIGS. 1-4 reflects tests conducted in direct sunlight in Phoenix, Ariz. The ambient temperature reached highs of about 105° F. It can be seen that the dual element wrapper of the present invention achieved substantially greater success in maintaining lower temperatures within the bundle of shingles than the paper and single layer polyethylene wrappers.
Referring to FIG. 5, bundle of shingles 10 is shown as being covered with wrapper 12, which is a dual element wrapper comprised of a coextruded outer layer 14 of white polyethylene and inner layer 16 of silver polyethylene. Each shingle has a row of tab sealant applications 18 suitable for sealing the tabs of the shingles on the roof.
Referring to FIG. 6, pallet load 20 consists of pallet 22 of bundles of shingles covered by shroud 24, which is a coextruded outer layer 26 of white polyethylene and inner layer 28 of silver polyethylene. It is to be understood that as used herein, the term "pallet load of bundles of shingles" refers to any stack, pile or assembly of bundles of shingles, whether or not they are actually placed on a pallet.
The preferred embodiment of the present invention has been described for illustrative reasons and is not intended to be limiting upon the scope and content of the following claims. | 4y
|
TECHNICAL FIELD
The invention relates generally to the field of casters for movably supporting objects and, in particular, casters that can be locked to prevent the caster wheel from rotating about its running axis (wheel braking) and/or from turning about its swivel axis.
BACKGROUND ART
A swivel lock for a caster helps to maintain directional control (tracking) of an object that it supports, such as a cart, while the object is being moved. A wheel brake keeps the supported object from rolling unintentionally. Total locking of the caster (wheel brake and swivel lock) is the most stable condition, preventing all rolling and swiveling movement. Examples of both are disclosed in U.S. Pat. No. 4,035,864; U.S. Pat. No. 4,835,815; U.S. Pat. No. 4,205,413; U.S. Pat. No. 3,571,842; U.S. Pat. No. 4,349,937; and U.S. Pat. No. 6,725,501, to name a few.
SUMMARY DISCLOSURE OF THE INVENTION
The present invention is directed to a unique and improved caster having directional and total locking capabilities. From one perspective, the invention is directed to a lockable caster comprising a mounting member adapted to be connected to a load to be supported by the caster; a yoke, comprising two depending legs interconnected by an upper bight portion, pivotally connected to the mounting member for relative pivotal movement about a swivel axis; a wheel mounted between the legs of the yoke for rotation about a running axis; and a locking structure between the legs of the yoke adjacent the bight portion and fixed relative to the mounting member. The locking structure comprises recesses spaced so as to at least partially surround the swivel axis. A total lock mechanism is carried by the yoke and comprises a movable brake member adapted to engage the wheel to lock it against rotation, and a movable total lock tooth configured to engage any of a plurality of the recesses to lock the yoke against pivotal movement about the swivel axis in any of a plurality of total lock positions. A directional lock mechanism is carried by the yoke and comprises a movable directional lock tooth adapted to engage at least one of the recesses to lock the yoke against pivotal movement about the swivel axis in at least one directional lock (tracking) position while allowing the wheel to rotate. The number of directional lock positions is fewer than the number of total lock positions.
In a preferred arrangement, all of the recesses may be coplanar, and all may lie along a circle centered on the swivel axis. For example, the locking structure may comprise a lower ball retainer of a pivot bearing assembly, and the recesses may be located at the periphery of the lower ball retainer. The directional lock tooth preferably is wider than the total lock tooth; at least one of the recesses is a directional lock recess having a width sized to accommodate the directional lock tooth; and the other recesses are equal-width total lock recesses that are equally spaced on either side of the directional lock recess(es) and are sized to accommodate the total lock tooth but not the directional lock tooth. The number of recesses engageable by the directional lock tooth preferably is fewer than the number of recesses engageable by the total lock tooth. Further, the total lock tooth preferably comprises at least two tines spaced such that each tine can engage a total lock recess, the overall width of the plurality of tines being equal to the width of the directional lock tooth so that the total lock tooth can also engage a directional lock recess. Preferably there are two diametrically opposed directional lock recesses.
The total lock mechanism preferably comprises a total lock lever pivoted intermediate its ends to the yoke, with the brake member and the total lock tooth at opposite ends of the total lock lever. The directional lock mechanism preferably comprises a directional lock lever pivoted intermediate its ends to the yoke, with the directional lock tooth at one end of the directional lock lever. The total lock lever and the directional lock lever preferably are arranged side-by-side, with both pivoted to the yoke about a common pivot axis. The brake member preferably is canted toward the medial plane of the wheel so as to be engageable with the outer circumference of the wheel.
Each of the lock mechanisms preferably is spring-biased away from a locked state and comprises an expanding over-center toggle mechanism pivoted to the yoke for moving the lock mechanism against the spring bias into a locked state. Each toggle mechanism preferably comprises a four-bar linkage, one link of the toggle mechanism being pivoted to its respective lock lever remote from its toothed end and having an extension forming an operating pedal for moving the lock mechanism into a locked state. The operating pedals of the toggle mechanisms preferably are arranged side-by-side, with a common release pedal pivoted to the yoke above the operating pedals and linked to each toggle mechanism for releasing either or both of the lock mechanisms from a locked state.
From another perspective, the invention is directed to a lockable caster comprising a mounting member adapted to be connected to a load to be supported by the caster; a yoke, comprising two depending legs interconnected by an upper bight portion, pivotally connected to the mounting member for relative pivotal movement about a swivel axis; a wheel mounted between the legs of the yoke for rotation about a running axis; and a locking structure between the legs of the yoke adjacent the bight portion and fixed relative to the mounting member. The locking structure preferably comprises coplanar recesses spaced along a circle centered on the swivel axis, at least one of the recesses being a directional lock recess, and a greater number of other recesses being total lock recesses, which are configured differently from the directional lock recess. A total lock mechanism carried by the yoke comprises a movable brake member configured to engage the wheel to lock it against rotation, and a movable total lock tooth configured to engage any of the total lock recesses and any of the directional lock recesses to lock the yoke against pivotal movement about the swivel axis in any of a plurality of total lock positions. A directional lock mechanism is carried by the yoke and comprises a movable directional lock tooth configured to engage only the directional lock recesses to lock the yoke against pivotal movement about the swivel axis in at least one directional lock (tracking) position while allowing the wheel to rotate.
In a preferred arrangement, the total lock tooth is at one end of a total lock lever, and the directional lock tooth is at one end of a directional lock lever. The two lock levers preferably are arranged side-by-side with their toothed ends adjacent each other.
Further features, aspects and advantages of the invention will become apparent from the following detailed description of preferred embodiments, including the best mode for carrying out the invention, when considered together with the accompanying figures of drawing.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a perspective view of one example of a locking caster according to the invention.
FIG. 2 is a front elevational view of the caster of FIG. 1 .
FIG. 3 is a left side elevational view of the caster of FIG. 1 .
FIG. 4 is an exploded view of the caster of FIG. 1 , showing details of the lock mechanisms.
FIG. 5 is a partially exploded perspective view of the caster of FIG. 1 , with some parts removed, showing how the lock mechanisms interface with the lock recesses.
FIG. 6 is a partially exploded perspective view of the lock mechanisms of the caster of FIG. 1 , from an opposite viewpoint.
FIG. 7 is a cross-sectional view taken along line 7 - 7 in FIG. 2 , with most of the yoke removed, showing the relationship among the total lock mechanism, the lock recesses and the wheel.
FIG. 8 is a bottom plan view of the caster of FIG. 1 , with the wheel removed, showing the relationship of the lock mechanisms to the lock recesses.
DETAILED DESCRIPTION
Referring to FIGS. 1-3 , a locking caster 2 according to the invention comprises a mounting member in the form of a plate 4 having four elongated holes 6 through which bolts, screws or other suitable fasteners can be installed to attach the caster to a load to be movably supported. A yoke 8 is connected to the plate 4 for relative pivotal movement about a swivel axis 10 by means of a pivot bearing assembly 12 and a rivet 14 or other suitable fastener. The yoke has depending legs 16 between which a ground-engaging wheel 18 is mounted for rotation about a running axis 20 by means of an axle 22 , which extends through aligned holes in the legs 16 and through bearings in the wheel, secured by a locknut 24 . The legs 16 are interconnected by an upper bight portion 26 . Also visible in these figures are a total lock operating pedal 28 , a directional lock operating pedal 30 , and a common release pedal 32 , all of which are parts of the lock mechanisms described below.
Referring to FIGS. 4-8 , two side-by-side lock mechanisms 40 , 60 are carried by the yoke 8 and are selectively engageable with various recesses R formed by and between teeth 15 on the lower ball retainer 13 of pivot bearing assembly 12 . Lower ball retainer 13 is fixed relative to plate 4 . Teeth 15 and recesses R thus form a locking structure that is fixed (stationary) in relation to plate 4 . One of the lock mechanisms is a total lock mechanism 40 , which comprises a total lock lever 42 pivoted intermediate its ends to the yoke 8 about a pivot rod 34 , which is secured to the legs 16 through holes 36 . Lever 42 preferably is made of spring steel and has a projecting central tab 44 , which is flanked by curved shoulders 46 . Resilient tab 44 and shoulders 46 embrace pivot rod 34 , with the tip of tab 44 trapped against the underside of bight portion 26 (see FIG. 7 ) to bias total lock lever 42 toward an unlocked position (counterclockwise as seen in FIG. 7 ). Although shown passing beneath pivot rod 34 , for easier assembly tab 44 alternatively could be configured to pass above rod 34 and still perform its biasing function.
The front (lower) end of lock lever 42 has a brake member 50 that is canted toward the medial plane 38 of the wheel 18 so as to overlie the center of the wheel tread. Brake member 50 has braking elements on its underside in the form of ribs 52 that grip the wheel tread when in a locked condition. Other types of braking elements or surfaces may be employed, depending at least in part on the type of wheel tread used. The opposite (rear) end of total lock lever 42 has a total lock tooth structure 54 in the form of two tines 56 shaped and arranged along an arc that conforms to the arc along which teeth 15 of lower ball retainer 13 are arranged.
The other lock mechanism is a directional lock mechanism 60 , which comprises a directional lock lever 62 that is similar in many respects to total lock lever 42 . Directional lock lever 62 also preferably is made of spring steel, is pivoted intermediate its ends to the yoke 8 about pivot rod 34 , and has a projecting central tab 65 , which is flanked by curved shoulders 66 . Resilient tab 65 and shoulders 66 embrace pivot rod 34 , with the tip of tab 65 trapped against the underside of bight portion 26 to bias directional lock lever 62 toward an unlocked position (counterclockwise with reference to FIG. 7 ). Although shown passing beneath pivot rod 34 , for easier assembly tab 65 alternatively could be configured to pass above rod 34 and still perform its biasing function. The rear end of directional lock lever 62 has a directional lock tooth structure in the form of a single tooth 64 shaped and arranged along an arc that conforms to the arc along which teeth 15 of lower ball retainer 13 are arranged.
Referring to FIG. 8 , the swivel locking relationship that involves recesses R on lower ball retainer 13 , directional lock tooth 64 and total lock tooth 54 (tines 56 ) will now be explained. The recesses R on lower ball retainer 13 are of two different sizes, all formed by teeth 15 : fourteen narrow, equal-width total lock recesses 72 , and two wider, equal-width and diametrically opposed directional lock recesses 74 . All are arranged in a circle centered on swivel axis 10 . Total lock recesses 72 are equally spaced on either side of each of the directional lock recesses 74 . The angular offsets of adjacent teeth 15 are as follows:
teeth 15 that form total lock recesses 72: 20 degrees; teeth 15 that form directional lock recesses 74: 40 degrees.
Thus, the space between alternate teeth 15 that form the total lock recesses 72 is equal to the width of each directional lock recess.
Directional lock tooth 64 is sized to fit into (engage) only a directional lock recess 74 ; it is too wide to engage any total lock recess 72 . The tines 56 of total lock tooth 54 are sized and spaced to fit into (engage) any adjacent pair of total lock recesses 72 ; or one tine 56 can engage a single total lock recess 72 adjacent a directional lock recess 74 , with the other tine residing in that directional lock recess 74 . The pair of tines 56 together have an overall width that is equal to the width of the directional lock tooth 64 ; therefore, the total lock tooth 54 can also fit into (engage) either of the directional lock recesses 74 . Accordingly, total locking can be effected in any of eighteen swivel positions, equally spaced by 20 degrees. On the other hand, directional locking in a tracking position can be effected in only two swivel positions (with the directional lock tooth 64 engaging a directional lock recesses 74 ); and because those positions are diametrically opposed, the plane of rotation of the wheel 18 when so locked is the same regardless of which directional lock recess 74 is engaged.
Upward (locking) movement of the rear toothed end of each of the lock levers 42 , 62 to engage recesses R is effected through separate but similar expanding toggle mechanisms, each comprising a four-bar, over-center linkage. Depressing common release pedal 32 (labeled “OFF”) unlocks either or both of the lock mechanisms, i.e., lowers the toothed end(s) of the lock lever(s) out of engagement with recesses R. Both toggle mechanisms are pivotally linked to the legs 16 of the yoke by a common pivot rod 86 , about which common release pedal 32 also pivots. Each toggle mechanism includes its respective lock lever 42 , 62 , which is pivotally linked by an individual pivot pin 82 held in a pair of upturned ears 84 at the front (lower) end of the lock lever. Each toggle mechanism further includes the rear extension 88 of its respective lock operating pedal 28 , 30 , and a cam link 90 individually linked to its respective pedal extension by a pivot pin 92 and nestled in a recess 33 in common release pedal 32 . The upper end of cam link 90 is pivoted to the legs 16 by common pivot rod 86 . Thus, the four “bars” of each linkage are: the yoke 8 (leg(s) 16 ); the lock lever ( 42 , 62 ) from pivot rod 34 to pivot pin 82 ; the rear extension 88 of the lock operating pedal ( 28 , 30 ) from pivot pin 82 to pivot pin 92 ; and the cam link 90 from pivot pin 92 to pivot rod 86 .
The sectional view of FIG. 7 shows in broken lines the locked positions of the components of one of the lock mechanisms. When the lock operating pedal ( 28 , 30 ) is depressed, the rear extension 88 of the lock operating pedal and the cam link 90 expand the distance between pivot rod 86 and pivot pin 82 , forcing the front end of the lock lever ( 42 , 62 ) downwardly so that the lock lever pivots about pivot rod 34 , raising the opposite (rear) end of the lock lever toward the lower ball retainer 13 and its recesses R. The lock operating pedal rear extension 88 and the cam link 90 are dimensioned such that an over-center latching effect is achieved, whereby the lock operating pedal ( 28 , 30 ) snaps downwardly near the end of its travel and remains there. At the same time, a front extension 94 on cam link 90 raises common release pedal 32 . When the common release pedal 32 is in this position and is depressed, it forces the cam link 90 to rotate downwardly, raising the front end of the lock lever ( 42 , 62 ), lowering the opposite (rear) end away from the lower ball retainer 13 and its recesses R, and raising the lock operating pedal ( 28 , 30 ).
When the total lock operating pedal 28 is depressed, if the tines 56 of resilient total lock lever 42 are not aligned with any of the recesses 72 , 74 , slight pivoting of the yoke and wheel (less than 20 degrees) about the swivel axis 10 will allow them to snap into engagement with one or more nearby recesses to effect total locking. When the directional lock operating pedal 30 is depressed, if the tooth 64 of the resilient directional lock lever 62 is not aligned with a directional lock recess 74 , pivoting of the yoke and wheel by less than 180 degrees about the swivel axis 10 will allow tooth 64 to snap into engagement with one of the directional lock recesses 74 to effect directional locking. Of course, if the yoke and wheel are pivoted in a direction that moves the tooth 64 toward the nearer directional lock recess 74 , locking will be accomplished by swiveling the yoke and wheel less than 90 degrees.
The above-described arrangement of recesses R on stationary lower ball retainer 13 is exemplary only, and it is envisioned that the invention may encompass many variants. For example, it may be desirable to be able to lock the wheel directionally in one of two (or even more) planes of rotation (tracking positions), in which case an additional pair of diametrically opposed directional lock recesses 74 may be formed on lower ball retainer 13 , e.g., displaced 90 degrees from the first pair. Alternatively, instead of forming the directional lock recesses in diametrically opposed pairs, individual directional lock recesses 74 may be formed at positions on lower ball retainer 13 that are not diametrically opposed to one another. Further, a different number of total lock recesses 72 may be formed on lower ball retainer 13 , depending on the size of the caster and/or the requirements of the particular caster application, the sizes of the recesses and the lock teeth being adjusted accordingly. In a further variant, the recesses may be formed on a stationary plate fixed below and coaxial with lower ball retainer 13 , instead of on the lower ball retainer. In almost any variant, the recesses themselves may be formed as depressions or holes rather than being defined by the square shoulders of teeth such as those on lower ball retainer 13 . Of course, in that case, the lock teeth 54 , 64 would have to be configured appropriately to engage such recesses.
It is also possible, within the scope of the invention, to deviate from the exclusively coplanar arrangement of recesses R described above. For example, two sets of recesses in spaced parallel planes may be employed: one set (e.g., the total lock recesses) formed at the periphery of stationary lower ball retainer 13 , and the other set (the directional lock recess(es)) formed along a circle on a stationary plate fixed below and coaxial with lower ball retainer 13 , or along a smaller circle on lower ball retainer 13 . With such arrangements, the directional lock lever would be differently configured so as to reach the differently placed directional lock recess(es) and clear the total lock recesses. The locations of the different sets of recesses could be reversed, in which case the total lock lever would be differently configured for reach and clearance. Those skilled in the art will recognize that further variations are within the scope of the invention, which is defined by the appended claims.
As to material selection, it is preferred that most of the parts of the caster of the invention be made of steel (e.g., stainless) for strength and durability. Possible exceptions are the pedals 28 , 30 , 32 and the cam links 90 , which preferably are molded of a stiff and durable plastic, such as HDPE. The wheel and its bearings may be made of any materials suitable for the particular application. Of course, material selection for any of the parts of the caster will be governed at least in part by particular load, environmental and regulatory requirements of the application.
INDUSTRIAL APPLICABILITY
It will be readily apparent that selectively lockable casters embodying the invention can be employed to movably support a wide variety of objects and structures used in many fields, such as food service carts, equipment carts, utility carts, dollies, and patient beds, to name just a few. | 4y
|
BACKGROUND OF THE INVENTION
The invention relates to the technical field of satchels and rucksacks (backpacks) that may be intended for school, sporting or hiking use.
School satchels are often designed to be worn on the back by the pupil and the shoulder straps press on the shoulders. This type of satchel has the advantage of freeing the pupil's hands and, above all, ensures a better balanced load. The load can be relatively heavy, of the order of 10 to 20 kg, depending on the number of files and books carried. There is therefore a need to improve, as much as possible, carrying comfort.
Hiking rucksacks that can be used for any purpose and for leisure use in particular may, in some cases, be heavily loaded with products and various clothing, thus making it necessary to improve carrying comfort.
In view of the problems mentioned above, there have been proposals to make the shoulder straps of satchels, backpacks or similar bags with built-in inflatable means, thus making it possible to create pockets of air to improve and make the carrying of such articles more comfortable. Many patents have been filed in this area, e.g. FR 1028577, AT 675838, FR 2406402, FR 2697143.
In these embodiments, the inflatable element was introduced directly into the shoulder strap with an external means of control used to ensure inflation or deflation.
Proposals have also been made, in numerous patents, to incorporate in the rear surface or the bottom of the satchel one or more inflatable chambers with pumps or external bulb inflators with this assembly offering improved carrying comfort.
Various investigations that have been carried out demonstrate that the need to lighten and/or make the carrying of packs or satchels more comfortable are very real and meet genuine medical concerns to protect the pupil or wearer, especially their vertebral column.
Although the concept of inflating certain parts or components of the pack and/or satchel offer undeniable benefits, in practice certain drawbacks or inadequacies in the protection of the means of inflation or deflation have been observed. If the latter is an inflator bulb as described in Patent FR 2700675 or a bellows, it generally remains visible from outside the pack or satchel. It can be operated by persons other than the wearer with all the resulting risks of damage, puncture and other risks of the same type.
In addition, once the pack or satchel is worn by the user, none of the known techniques makes it possible to vary, if required, the degree of inflation in order to adapt it to the carried load and therefore to adjust inflation as required.
SUMMARY OF THE INVENTION
The object sought after by the invention was to devise an inflation/deflation device for shoulder straps associated with a pack, satchel or similar that would, on the one hand, be protected as such, be operable chiefly by the user and adjustable during use as required.
These objects and others will become apparent from the following description.
According to a first aspect, the device for inflating/deflating the shoulder straps of a means of the satchel, pack or similar type intended to be worn on the back by a person, the shoulder strap or straps comprising an inflatable integral cushion controlled by an external means of inflating the shoulder strap, is distinctive in that the inflation/deflation device is incorporated in a one-piece part constituting the means of guiding and adjusting the length of the strap attached to the pack, satchel or similar, said one-piece part forming a pad being shaped and devised to ensure positioning of the means of inflating/deflating the shoulder straps, its protection, its connection to one of the ends of the shoulder strap whilst allowing the injection of inflating air into the cushion incorporated in the shoulder strap.
These aspects and others will become apparent from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
The object of the present invention is described, merely by way of example, in the accompanying drawings in which:
FIG. 1 is a perspective view before assembly of the inflation/deflation device according to the invention intended to be incorporated in the closing loop of a pack, satchel or similar shoulder strap.
FIG. 2 is a longitudinal section of the device according to the invention after assembly and its integration into the closing loop.
FIG. 3 is a plan view according to FIG. 2 .
FIG. 4 is a view according to FIG. 3 but in section showing the means of operating the inflation/deflation device.
FIG. 5 is a transverse sectional view along line A—A in FIG. 4 .
FIG. 6 is a longitudinal section of the device showing the shoulder strap inflation phase.
FIG. 7 is a view similar to FIG. 6 but during the shoulder strap deflation phase.
FIG. 8 is a view of the application of the device according to the invention to a satchel.
DESCRIPTION OF THE INVENTION
In order that the present invention may more readily be understood, the following description is given, merely by way of example, reference being made to the accompanying drawings.
The device for inflating/deflating the shoulder straps is referred to in its entirety as ( 1 ) and has applications for packs, satchels ( 2 ) and, generally speaking, any article that can be worn on the back by a user and which demands the use of shoulder straps that press onto the user's shoulders.
The shoulder straps are made in a known manner of fabric or any other material and are attached at one end ( 3 a ) to the rear wall ( 2 a ) or shell of the satchel by any known appropriate means and to a quick-release fastener at the other end ( 3 b ) allowing connection to a strap ( 4 ) joined to the lower part ( 2 b ) of the satchel.
According to the invention, the inflation/deflation device ( 1 ) is incorporated in a one-piece part ( 5 ) herein referred to as a pad constituting the means of guiding and adjusting the length of the strap, said part itself being connected to the shoulder strap by making the means of inflation member ( 6 ) communicate with an inflatable cushion ( 7 ) incorporated in the shoulder strap. A device of this type is provided on each shoulder strap of the satchel. The inflation member is formed of a resilient material that can be deformed as illustrated in FIG. 6 .
The one-piece part ( 5 ) forming a shaped pad is made of any appropriate material and is devised to fulfil four functions, namely:
protecting the inflation/deflation device,
positioning it,
connection to one of the ends ( 3 b ) of said shoulder strap ( 3 ), allowing the injection of inflating air,
connection to the length-adjustment strap ( 4 ) in order to adjust the carrying position of the satchel for the user.
The pad of the one-piece part ( 5 ) is shaped in any appropriate manner with a flat cross section and may have a well styled, attractive appearance.
The pad of the one-piece part ( 5 ) is advantageously made in two parts with a base ( 5 a ) and a cover ( 5 b ), the latter being separately mounted and fixed by bonding or other means. The stretched-shape base has, in its central part ( 5 a 1 ), a cavity ( 5 a 2 ) making it possible to position the inflation means ( 6 ) which must be connected to cushion ( 7 ). The base has an opening ( 5 a 3 ) in its thickness located in the above-mentioned central part and accommodating a shaft ( 8 ) integrally made during the manufacture of the pad and making it possible to guide and deflect the adjustment strap ( 4 ) that is physically connected to the pack or satchel. Said base ( 5 a ) also comprises, at one of its ends, a tunnel shape ( 5 a 4 ) making it possible to guide and attach the end ( 3 b ) of the shoulder strap by any appropriate means. This tunnel shape ( 5 a 4 ) is shaped to permit and provide room for the connecting tube ( 9 ) between the inflation means ( 6 ) and cushion ( 7 ) incorporated in the shoulder strap. Said inflation member includes a bulb shape ( 6 a ) intended to be centred in the central part of the cavity of the pad, said bulb extending as a pipe ( 6 b ) capable of penetrating into said part forming a tunnel ( 5 a 4 ) on the one hand, and permitting, on the other hand, connection to the cushion by means of an appropriate connecting tube ( 9 ). The pipe part ( 6 b ) is capable of fitting into a recess that matches its shape made in the thickness of the pad, this recess being arranged advantageously in the median axial plane of the pad. Said pipe ( 6 b ) is therefore maintained securely in position.
Communication between the pipe ( 6 b ) and bulb ( 6 a ) is via a reduced-diameter channel ( 6 c ) that delimits on the bottom of the pipe a seat shape of which the function will be specified below. Vertically above the area where the pipe and reduced-diameter channel are connected, there is provision for an additional protruding bump ( 6 d ) capable of receiving, during certain phases, a ball ( 10 ) of small cross-sectional area. This ball is pushed into the pipe by a spiral spring ( 11 ) that is suitably guided into the latter, said ball blocking off the connecting channel ( 6 c ) between the bulb and the pipe when the inflation/deflation means is not in use. Spring ( 11 ) is secured in said pipe by a retention lip ( 6 e ) formed on the outside of the pipe.
Cover ( 5 b ) which is separately mounted on the pad is devised with two circular openings ( 5 b 1 - 5 b 2 ) of appropriate size to surround and protect, on the one hand, the bulb part 6 a of the inflation means and, on the other hand, the bump part 6 d of the air pipe, leaving the protruding projecting parts of the bulb and of the bump visible.
Cushion ( 7 ) which is linked to inflation means ( 6 ) is long and is inserted inside the actual shoulder strap. In a known manner, this cushion may comprise various chambers that communicate with each other making it possible to split up the inflation zone into segments. The connecting tube between the cushion and the inflation device is made in any appropriate manner.
The operation of the device will now be described. Each shoulder strap of the satchel or pack is devised with such a device. The end of the shoulder strap is attached, as stated previously, on the pad by any appropriate known means and the cushion is made to communicate with the inflation device via the intermediate tube. The lower strap attached to the pack or satchel has been inserted into the lower part of the pad into the opening so that the entire assembly is securely held.
When not in use, the shoulder straps are not inflated. When the user has correctly put the satchel or pack onto their back, the shoulder straps are located over the individual's chest. Using the right or left hand, the user simply needs to press the bulb as shown in FIG. 6 in order to ensure inflation. The pressure exerted on the bulb makes it possible to expel the air and push the ball in opposition to the spring in the connecting pipe, the air then being forced into the cushion located inside the shoulder strap. The user repeats this operation several times in order to obtain the desired inflation pressure. After inflation, the inflation bulb is no longer used and the ball, under the effect of the spring's decompression force, returns to its original position, thus blocking off the seating of the bottom of the pipe.
To ensure the deflation function shown in FIG. 7, the user simply has to press on the bump 6 d of the pipe, this pressure causes displacement of the ball in the pipe and frees the reduced-diameter channel between the bulb and the pipe. The air can escape into the bulb and into the outside atmosphere through an opening in the bulb. The cushion is gradually deflated until all the air is evacuated.
The device according to the invention is very simple to produce and operate. According to the invention, the inflation/deflation device is entirely integrated into the support pad which also provides connection to the lower strap. The entire device is produced so that its various components cannot be tampered with because only the bulb and the deflation means can be accessed.
The pad may also be of any appropriate shape and profile. The area where the lower strap is connected and deflected may be arranged differently, for instance, at the end of the pad opposite the area where the shoulder strap is attached.
As well as its functional aspect, the inflation device therefore helps give the pad its special attractive appearance.
The user can, depending on the load, adjust, in each shoulder strap, the inflation pressure, thus obtaining optimum comfort at their discretion.
The integral cushion in the shoulder strap is of any appropriate shape and design. | 4y
|
BACKGROUND OF THE INVENTION
The present invention relates to a ratio control of a continuously variable transmission of an automobile, and more particularly to a traction control by appropriately setting a reduction ratio upon the vehicle starting from a standstill on a road with a low friction coefficient.
Japanese patent application First (unexamined) Publication No. 64-36532 discloses a continuously variable transmission provided with a manual selector switch. According to this continuously variable transmission, if he/she recognizes that a road has a low friction coefficient, the driver places this switch to a predetermined position, causing the transmission to establish a predetermined reduction ratio smaller than the maximum reduction ratio.
An object of the present invention is to improve a ratio control of a continuously variable transmission such that the transmission automatically selects an appropriate reduction ratio for a road condition.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided an automotive vehicle, comprising:
an engine;
a continuously variable transmission having an input member drivingly connected to said engine and an output member;
a driving wheel drivingly connected to said output member;
means for detecting a revolution speed of said input member and for generating an input revolution speed indicative signal indicative of said revolution speed of said input member detected; and
means for detecting a revolution speed of said output member for generating a driving wheel revolution speed indicative signal indicative of said revolution speed of said output member detected;
wherein a driving wheel acceleration of said driving wheel is determined on said driving wheel revolution speed indicative signal, and said continuously variable transmission upshifts when said driving wheel acceleration becomes equal to or greater than a predetermined acceleration value.
According to another aspect of the present invention, there is provided a method of a traction control of an automotive vehicle having an engine, a continuously variable transmission and a driving wheel, the continuously variable transmission including an input member drivingly connected to the engine and an output member drivingly connected to the driving wheel, the method comprising the steps of:
detecting a revolution speed of the input member and generating an input revolution speed indicative signal indicative of said revolution speed of said input member detected;
detecting a revolution speed of the output member and generating a driving wheel revolution speed indicative signal indicative of said resolution speed of the output member detected;
determining a driving wheel acceleration of the driving wheel based on said driving wheel revolution speed indicative signal; and
causing the continuously variable transmission to upshift when said driving wheel acceleration becomes equal to or greater than a predetermined acceleration value.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of a motor vehicle with an engine followed by a hydrokinetic torque transmitting unit with a lock-up clutch and an automatic transmission;
FIGS. 2A and 2B, when combined, illustrate an electro-hydraulic circuit for the automatic transmission;
FIG. 3 is a block diagram of a control unit for the electro-hydraulic circuit;
FIG. 4 is a flow diagram for explaining the operation of a first embodiment;
FIG. 5 is a diagram illustrating a function of α o (alpha zero) versus TVO;
FIG. 6 is a diagram illustrating T·Nt versus VSP for different TVO; and
FIG. 7 is a flow diagram for explaining operation of a second embodiment.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIGS. 1, 2A, 2B, and 3, reference is made to Yamamuro et al U.S. Pat. No. 4,735,113 issued on Apr. 5, 1988 which is hereby incorporated by reference in its entirety. Specifically, reference is made to FIG. 2, 1A, 1B, and 3 of this known patent since they correspond to FIGS. 1, 2A, 2B, and 3 of this application. This U.S. Patent corresponds to EP-A 0180209 published on May 7, 1986, which EP publication is hereby incorporated by reference in its entirety. In understanding FIGS. 1, 2A, 2B, and 3, reference is also made to copending U.S. patent application Ser. No. 07/563,309 (now U.S. Pat. No. 5,067,372 issued on Nov. 26, 1991) filed on Aug. 7, 1990, which application is hereby incorporated by reference in its entirety. This copending U.S. patent application corresponds to German patent application Ser. No. P 4025455.0 filed on Aug. 10, 1990, now DE 40 25 455 A1 published on Mar. 14, 1991.
Referring to FIG. 1, there is shown a portion of an automotive vehicle. The vehicle includes an engine 10 with a throttle which opens in degrees as an accelerator pedal or a gas pedal is depressed, a hydrokinetic torque transmitting unit in the form of a fluid coupling 12, a forward/reverse drive change-over mechanism 15, a driver pulley 16, a follower pulley 26, a V-belt 24, and a differential 56. The fluid coupling 12 includes a pump impeller 12c coupled with the engine 10 at its output shaft 10a, and a turbine runner 12b coupled with a turbine shaft 13 which is in turn coupled with the forward/reverse drive change-over mechanism 15. The fluid coupling 12 includes a lock-up mechanism, namely, a lock-up clutch, which is hydraulically actuable.
Referring to FIGS. 2A and 2B, a lock-up control valve 122, an electromagnetically operated valve 118 including a solenoid 224, a throttle valve 114, and a shift command valve 108 are shown. The lock-up control valve 122 has a lock-up position as illustrated by an upper half thereof viewing in FIG. 2A and a lock-up release position as illustrated by a lower half thereof viewing in FIG. 2A. It assumes one of the two positions under the control of the electromagnetically operated valve 118. The throttle valve 114 generates a throttle pressure which is supplied selectively to a forward clutch 40 for a forward drive or a reverse brake 50 for a reverse drive. The magnitude of the throttle pressure is adjustable or variable by the electromagnetically operated valve 118. The electromagnetically operated valve 118 is connected to the lock-up control valve 122 or the throttle valve 114, selectively, under the control of the shift command valve 108. The shift command valve 108 has a spool 182 longitudinally movable by a shift motor in the form of a stepper motor 110. The spool 182 is movable within a normal stroke range between a minimum reduction ratio position and also movable beyond the maximum reduction ratio position into an overstroke range next adjacent to the normal stroke range. The spool 182 is formed with two axially spaced lands 182a and 182b which function to connect the electromagnetically operated valve 118 to the lock-up control valve 122 to subject the lock-up control valve 122 to a hydraulic pressure signal generated by the electromagnetically operated valve 118 during movement of the spool 182 within the normal stroke range and to disconnect the electromagnetically operated valve 118 from the lock-up control valve 122 during movement of the spool within the overstroke range. During movement of the spool 182 within the normal stroke range, the lands 182a and 182b on the spool 182 function to disconnect the electromagnetically operated valve 118 from the throttle valve 114, while during movement of the spool 182 within the overstroke range, the lands 182a and 182b on the spool 182 function to connect the electromagnetically operated valve 118 to the throttle valve 114. A constant pressure regulator valve 116 generates a constant hydraulic pressure. This constant hydraulic pressure is allowed to act via a signal pressure port 240b on the lock-up control valve 122 when the electromagnetically operated valve 118 is disconnected from the lock-up control valve 122 during movement of the spool 182 within the overstroke range to keep the lock-up control valve 122 at the lock-up release position, causing the lock-up mechanism of the fluid coupling 12 to assume the lock-up release state. Upon or immediately after a driver's demand for moving the vehicle from a standstill, the spool 182 of the shift command valve 108 moves from the overstroke range to the maximum reduction ratio position of the normal stroke range to connect the electromagnetically operated valve 118 to the lock-up control valve 122. Subsequently, the lock-up control valve 122 is allowed to shift between the lock-up release position and the lock-up position under the control of the electromagnetically operated valve 118. The electromagnetically operated valve 118 holds the lock-up control valve 122 in the lock-up release position until the vehicle speed exceeds a lock-up vehicle speed value, and subsequently shifts the lock-up control valve 122 to the lock-up position when the vehicle speed exceeds the lock-up vehicle speed value.
Briefly explaining the manner of a ratio shift control, a shift control valve 106 regulates the supply of hydraulic fluid to and discharge thereof from a driver pulley cylinder chamber 20 of the driver pulley 16 in response to movement of the spool 82. The pressure of the hydraulic fluid within the follower pulley cylinder chamber 32 of the follower pulley 26 is not affected by the shift control valve 106 and is kept as high as a line pressure generated by a line pressure regulator valve 102. The line pressure is used in pressure regulation effected by the shift control valve 106. The shift control valve 106 includes a spool 174 which is actuated via a shift operation mechanism 112 by the stepper motor 110. The output of the shift control valve 106 is supplied to a driver pulley cylinder chamber 20. The pressure level within the driver pulley cylinder chamber 20 is zero to establish the maximum reduction ratio in the transmission. Increasing the pressure within the driver pulley cylinder chamber 20 causes an upshift from the maximum reduction ratio, resulting in a drop in engine revolution speed. The stepper motor 110 is controlled by the control unit 300.
As shown in FIG. 3, the control unit 300 receives signals from an engine revolution speed sensor 301, a vehicle speed sensor 302, a throttle opening degree sensor 303, and a turbine revolution speed sensor 305. It also receives signals from a shift position switch 304, an engine coolant temperature sensor 306, a brake sensor 307 and a change over detection switch 298. The engine revolution speed sensor 301 detects a revolution speed of the engine 10 and generates an engine revolution speed indicative signal indicative of the engine revolution speed detected. The vehicle speed sensor 302 detects a revolution speed of an output shaft 28 and generates a vehicle speed indicative signal indicative of the revolution speed detected. The throttle opening degree sensor 303 detects an opening degree of the engine throttle, as a variable representative of the engine load, and generates a throttle opening degree indicative signal indicative of the throttle opening degree detected. The turbine revolution speed sensor 305 detects a revolution speed of the turbine shaft 13 and generates an input revolution speed indicative signal indicative of the turbine revolution speed detected. These signals are fed to the control unit 300 along with the other sensor and switch outputs.
Referring to FIG. 6, the principle of operation of this embodiment is explained. In FIG. 6, a family of fully drawn curves illustrates a mapping data, g(TVO,VSP), which is to be retrieved based on a throttle opening degree TVO and a vehicle speed VSO. In FIG. 6, a broken straight line MAX is drawn to interconnect operation points at which the maximum reduction ratio is maintained, while a broken straight line MIN is drawn to interconnect operation points at which the minimum reduction ratio is maintained. According to this control strategy, the maximum reduction ratio is maintained to allow a swift increase in the engine revolution speed at low vehicle speeds to produce a driving force large enough to move the vehicle from a standstill. This control strategy will suffice unless a traction is lost. According to this embodiment, in order to make it easy for the vehicle to start from a standstill on a road with a low friction coefficient, an increase in target input revolution speed T·Nt given from the mapping data of FIG. 6 is leveled off at a predetermined value T·No upon detection of an occurrence of a predetermined degree of wheel slip. In accordance with this modified control strategy, the transmission initiates an upshift from the maximum reduction ratio at an earlier stage than would ordinarily occur upon detection of the predetermined degree of wheel slip. The setting is such that the above-mentioned predetermined value T·No is lower than an input revolution speed value which is usually used upon starting of the vehicle from a standstill. The larger the throttle opening degree, the larger the above-mentioned degree of wheel slip is. This relationship is illustrated in FIG. 5.
Referring to FIG. 4, the flow diagram of this operation is explained. This flow diagram shows a sub-routine of a main routine.
In FIG. 4, at a step 502, a stored vehicle speed data VSP is stored as VOLD. At the subsequent step 504, reading operations of outputs of the vehicle speed sensor 302 and throttle opening sensor 303 are performed to store the results as VSP and TVO. Thus, the vehicle speed data VSP is updated. At the next step 506, a wheel acceleration α(alpha) is calculated by subtracting VOLD from VSP. Then, at a step 508, a table look-up operation of the mapping data as illustrated in FIG. 5 based on TVO to give a predetermined acceleration value α o . At a step 510, a table look-up operation of the mapping data as illustrated in FIG. 6 is performed based on TVO and VSP to give a target input revolution speed T·Nt. There is an interrogation at a step 512 whether or not the acceleration α is greater than or equal to the predetermined acceleration value α o . If this results in a negative, a reduction ratio control is carried out (see block 520) using the data given at the step 510. If this inquiry results in affirmative, there is another interrogation at a decision step 514 whether or not T·Nt is greater than or equal to the predetermined value T·No. If this results in negative, the control proceeds to the block 520 where the data T·Nt stored at the step 510 is used unmodified. If the interrogation at the step 514 results in affirmative, T·No is stored as T·Nt at a step 516 and this modified data is used in the reduction ratio control at the block 520.
In the flow diagram, it is to be understood that the vehicle speed sensor 302 detects revolution speed of the transmission output member and thus the data α is indicative of a wheel acceleration of the driving wheel of the vehicle.
In the flow diagram shown in FIG. 4, the predetermined acceleration value α is set as a function of the TVO. Alternatively, this may be set as a function of VSP or a combination of VSP and TVO.
FIG. 7 is a flow diagram of a second embodiment. In this embodiment, the data T·Nt stored at the step 510 is modified to a smaller value which is a function of TVO and VSO. Thus, the flow diagram shown in FIG. 7 is different from that shown in FIG. 4 only in the provision of a step 518 in the place of two steps 514 and 516 of FIG. 4. | 4y
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus for making insulation. In another aspect this invention relates to a method and apparatus for making V-groove insulation. In yet another respect this invention relates to a method and apparatus for making tank pipe wrap.
2. Description of the Related Art
The increasing cost of energy has made it even more imperative that commercial and industrial applications be properly insulated to increase energy efficiency. Such applications include high temperature processes in which insulation is used to prevent energy loss to ambient surroundings. Such applications also include low temperature processes in which insulation is utilized to prevent energy gain to the system from ambient surroundings. Generally, insulation is applied to the exterior of piping, ductwork, tanks, reactors and other areas in which insulation is desired. Although a wide variety of insulation may be applied in a variety of methods, depending upon the desired insulating effect required for a given application, the two most common types of insulation are spray-on insulation and preformed insulation.
Spray-on insulation, is as the name implies, insulation that is sprayed on to the area to be insulated. However, spray-on insulation is recognized to have several disadvantages. Unless care is taken during the application, spray-on insulation may not be evenly applied to the area to be insulated, or if adequately applied, may not evenly adhere or bond to the area being insulated. Improper application, or improper bonding will create "hot" or "cold" spots. Since spray-on insulation hardens, sets-up, or cures after application, such spray-on insulation does not allow for ready access to the insulated member, thus hampering inspection and/or repairs. Spray-on insulation is also known to trap liquids, which if the liquids are salt-bearing or corrosive, may result in the eventual deterioration of the insulation and/or the insulated member. The application of spray-on insulation material is also very sensitive to local environmental conditions. Successful application must generally be performed within rigid wind, temperature and humidity parameters. Another complaint about spray-on insulation is that it is messy in application, and is often considered aesthetically unappealing.
Disadvantages associated with preformed insulation include high cost to individually form or mold a given insulation section to its intended application around the insulated member. For a given length and diameter pipe, duct or tank, a specific dimension insulation section must be formed, and this process is often expensive in terms of time and energy. Preformed insulation sections are also expensive from the standpoint of both shipment and storage, because the items generally have a hollow cavity inside which requires a great deal of space to ship or store, than would, for example, flat boards. Due to the vast array of sizes of pipe, it is generally required that a manufacturer or supplier have many various sizes on hand. Further, preformed sections are not easily adapted to applications other than the shape for which it was made, and often poorly fit even their original intended application due to manufacturing tolerances.
As a result of these and other disadvantages, other contemporary insulation systems have evolved which utilize either V-groove insulation or tank/pipe wrap insulation.
V-groove insulation is a flat section of insulation which has been notched or grooved to accommodate a given diameter circular pipe or duct. FIG. 5(a) shows a pipe 400 partially wrapped with V-groove insulation 440, having a multiplicity of V-grooves 450. V-groove insulation is generally necessary for small diameter pipes and tanks (i.e. less than about 36 inches) because of the extreme bending that the insulation is subjected to. In addition to fitting around cylindrical shapes, V-groove insulation can be made to fit around other shapes such as square, hexagon, octagon, rectangular as well as other shapes.
Tank wrap, known in the industry as lamilla, comprises pliable sheets of insulation that are wrapped around the pipe, tank or other item to be insulated. FIG. 5(b) shows a pipe 400 partially wrapped with tank wrap 410. Tank wrap generally has utility with larger diameter tanks and pipes (i.e. greater than about 36 inches). With smaller diameters, V-grooves are generally required to help the insulation material bend properly.
V-groove insulation and tank wrap is wrapped around a pipe, tank or other item to be insulated and held in place by a fastener such as an appropriately sized band or jacket. When access to the insulated item is required, the band or jacket is released and the V-groove insulation or tank wrap may be easily and quickly removed. Because V-groove insulation and tank wrap are simply boards that are then wrapped around the item to be insulated, they can be stored or shipped with efficient use of storage or shipping space. The boards of V-groove insulation or tank wrap may be easily fabricated to a multiplicity of sizes by merely cutting the board to the proper desired length. Thus, the boards are easily and quickly adapted to other sizes.
However, tank wrap is generally made from fibrous sections such as mineral wool or fiberglass in which the fibers are generally oriented in the lengthwise direction. FIG. 6(a) is a depiction of such sections that have been abutted end-to-end to be used as tank wrap. As shown, tank wrap 410 has fibers 430 generally oriented lengthwise in the tank wrap. However, such tank wrap suffers from a lack of compressive strength and is prone to collapsing radially inward toward the pipe, thus reducing insulating ability of the tank wrap. If the fibers were oriented radially from the pipe, the tank wrap would have greater compressive strength. FIG. 6(b) shows tank wrap 410 having fibers 420 that will be oriented generally radially from the pipe once it is wrapped around a pipe.
U.S. Pat. No. 4,838,968 issued Jul. 13, 1989 to Nelson, et al, and U.S. Pat. No. 4,954,202 which is a Continuation-in-Part of U.S. Pat. No. 4,838,968 and which issued Sept. 4, 1990 to Price, et al, both disclose a method and apparatus for making V-groove insulation.
However, neither U.S. Pat. No. 4,838,968 nor U.S. Pat. No. 4,954,202 disclose or suggest an apparatus or method for making tank wrap. Further, the V-groove apparatus of the above patents are limited to cutting isosceles V-grooves, are limited in that they require two saws to make V-grooves, and the carriage below the saw blades, limits the size of blade than can be utilized, thus limiting the thickness of board than can be processed.
Therefore, a need exists for an apparatus and method for making tank wrap, and for making V-groove insulation without the prior art limitations.
SUMMARY OF THE INVENTION
According to one embodiment of this invention there is provided a method of fabricating tank wrap of desired thickness having fibers oriented generally in the thickness direction from lengths of insulation material having fibers oriented generally in the length direction. The method comprises several sequential steps. The first step is positioning the lengths of insulation material lengthwise along a first movable track conveyor, such that the fibers are oriented generally parallel to the direction of conveyance as the lengths progress downstream in a longitudinal direction along the conveyor. Second step is severing the insulation material completely across the length, at intervals equal to the desired thickness of the tank wrap to be fabricated. Next the cut lengths of insulation material are reoriented by positioning them lengthwise across a second movable track conveyor such that the fibers are now oriented generally perpendicular to the direction of conveyance, and in an abutting relationship. Finally, a continuous length of backing material is affixed to the abutted severed lengths to form a continuous length of tank wrap having fibers generally oriented in the thickness direction.
According to another embodiment of the present invention there is provided an apparatus for fabricating tank wrap of desired thickness having fibers oriented generally in the thickness direction from lengths of insulation material having fibers oriented generally in the length direction, said apparatus comprising: a frame; a first conveyor system comprising an endless loop belt disposed along the frame and adapted to travel in a longitudinal direction; a feeding means situated at an upstream end of the conveyor system, and adapted to position the lengths of insulation material lengthwise along the belt, such that the fibers are oriented generally parallel to the direction of travel; a cutting means situated downstream of the feeding means and adapted to completely sever the insulation material across the length, at intervals equal to the desired thickness of the tank wrap to be fabricated; a second conveyor system comprising a second endless belt disposed along the frame and adapted to travel in the longitudinal direction and transport the severed lengths away from the cutting means, and off of the second conveyor system; a third conveyor system comprising a third conveyor system comprising a third belt disposed along the frame and adapted to travel in the longitudinal direction, which is positioned downstream and below the second conveyor system to catch the severed lengths as they convey off of the second conveyor system; a reorienting means situated at an upstream end of the third conveyor system and adapted to reorient the severed lengths lengthwise across the third belt such that the fibers of the severed lengths are now oriented generally perpendicular to the direction of travel; an abutting means located downstream of the reorienting means and adapted to place the severed lengths in an abutted relationship while maintaining the conveyor system to catch the severed lengths as they convey off of the second conveyor system; and a backing means situated downstream of the abutting means and adapted to affix backing to the abutted severed lengths to form a continuous sheet of tank wrap.
According to yet another embodiment of the present invention there is provided a V-groove cutting apparatus comprising: a base comprising a generally parallel pair of rods; saw mounts comprising a generally parallel pair of rods each independently slidably and rotatably disposed on and oriented generally perpendicular to the base rods; a pair of saws, each slidably mounted on one of the saw mounts; a saw mount movement means for each saw mount affixed to each base rod for slidably moving each saw mount independently along the base; a saw movement means for each saw affixed to each saw mount rod for slidably moving each saw along the saw mount rods; and a saw mount rotation means for each saw mount affixed to the saw mounts for rotating the saw mounts to set the saw cutting angle.
BRIEF DESCRIPTION OF THE DRAWINGS
In order to more fully understand the drawings used in the detailed description of the present invention, a brief description of each drawing is presented.
FIG. 1 shows a side view of the V-grooving apparatus of the present invention.
FIG. 2 is an overhead view of the V-grooving apparatus of the present invention.
FIG. 3 is a side view of the cutting station of the present invention.
FIG. 4 is an overhead view of the cutting station of the present invention.
FIG. 5 shows (a) V-groove insulation wrapped around a pipe, and (b) tank wrap wrapped around a pipe.
FIG. 6 shows (a) tank wrap with fibers oriented in the lengthwise direction, and (b) tank wrap with fibers oriented in the thickness direction.
FIG. 7 shows a side view of the tank wrap apparatus of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a side view and FIG. 2 shows an overhead view of the apparatus of the present invention in which sections of insulation are transformed into lengths of V-groove insulation.
Referring now to both FIGS. 1 and 2 it can be seen that the apparatus generally comprises a series of stations, each disposed along, above or proximate to a conveyor system. The conveyor system, shown generally as conveyor 20, conveyor 70 and conveyor 200, conveys the insulation sections 12 along a linear path in the direction represented by direction arrow 6, from the feeding station shown generally at 10, to the butt joint adhesive station 15, to the backing station shown generally at 30, to the cutting station shown generally at 500.
Conveyor 20 is designed to convey the insulation sections 12 in a linear path from the feeding station 10 to the cutting station 500. Conveyor 70 is designed to convey the insulation sections 12 in a linear path from the cutting station 500 for further processing downstream. Conveyor 200 is an optional conveyor for further downstream processing. Conveyor 20, conveyor 70 and conveyor 200 are all conventional conveyor systems that utilize a motor driven endless loop disposed on a series of rollers supported by a frame. Conveyor 20 comprises endless loop conveyor belt 21 that is driven by motor 23. Drive belt 25 connects the motor pulley 22 with the conveyor drive pulley 27. The conveyor belt 21 is disposed on a series of rollers 29 (not all shown), and the entire conveyor 20 is supported by a frame, shown by legs 24. In a similar fashion, conveyor 70 comprises endless loop conveyor belt 71 that is driven by motor 73. Drive belt 75 connects the motor pulley 72 with the conveyor drive pulley 77. The conveyor belt 71 is disposed on a series of rollers 79 (not all shown), and the entire conveyor 70 is supported by a frame, shown by legs 74. Conveyor 200 is similar to conveyor 20 and conveyor 70.
The feeding station 10 is generally required to place the insulation sections 12 in an end-to-end abutting relationship on conveyor belt 21 of conveyor 20 where the insulation sections are then joined together with an adhesive in the end-to-end abutted relationship to form a long continuous sheet. Many different feeding systems are available that can accomplish the above task. The feeding system shown in feeding station 10 of the FIGS. 1 and 2 comprises a billet auto loader 5 and a magazine feed 8. The feed magazine 8 is placed in load position 11 and the billet auto loader 5 feeds the insulation sections 12 onto conveyor belt 21. Once all of the insulation sections 12 of feed magazine 8 in load position 11 have been fed onto conveyor belt 21, that feed magazine 8 can be reloaded or replaced with another loaded feed magazine 8 and the feeding may be continued. As the insulation sections 12 are placed onto conveyor belt 21, they are joined together in an end-to-end abutting relationship with an adhesive at butt joint adhesive station 15, an adhesive is applied to at least one of the ends of insulation to be abutted together and the two insulation sections 12 are then pressed together by billet auto loader 5 to form a continuous sheet.
Once the insulation sections 12 are abutted together to form a continuous sheet, they are then conveyed along conveyor 20 to the backing station 30, where backing 33 is applied. Backing may generally be applied by any method. Common methods of applying backing, include the application of self-sticking backing to the insulation section 12, or application of backing after applying an adhesive to either the backing, the insulation section 12, or both. In the embodiment shown, self sticking backing is utilized. The backing is generally applied to insulation sections 12 from a spool 35 that is situated over conveyor 20. The adhesive may be applied by sprayer, or with a contactor such as a brush or roller. The backing is applied over the abutted insulation sections 12 so as to form a continuous integral sheet.
Any suitable backing material that can withstand the rigors of the manufacturing process and the rigors of insulation applications may be utilized. Suitable backing material is generally comprised of a flexible mylar or kevlar composition such as for example Hypolon ®TGH-100 laminate made by Alpha Associates, Inc. of Woodbridge, N.J. or a foil scrim (FSK) or all service jacket (ASJ) manufactured by LAMTEX Corp. of Flanders, N.J.
Ideally, the backing material should be exactly juxtaposed on the insulation sections -2 in order to avoid expensive and time consuming trimming operations. Unfortunately, there are many factors which may effect this exact juxtaposition. For example, inherent irregularities associated with different factory winding processes may effect how the backing is unwound off of the roll. Some backing materials may arrive from the factor staggered or unevenly would on the roll. Due to these and other problems, an alignment apparatus (not shown) is generally required to ensure even distribution and alignment of the backing on the insulation sections 12. Such alignment systems are well known to those of skill in the art, and would include for example, an electric eye guide such as model no. 57044H/H1116 electric eye and control component that is available from Hydralign, Inc.
Once the backing is applied, the insulation sections 12 are then conveyed to the cutting station 500 where the desired cuts are made to the abutted insulation sections 12.
The cutting station 500 is shown in FIGS. 1 and 2 and in more detail in FIGS. 3 and 4 (note that the blade angle varies between FIGS. 3 and 4), and generally comprises a pair of circular saws 520a and 520b which are mounted respectively on saw mounts 510a and 510b which allow the circular saws 520a and 520b to traverse beneath the insulation sections 12 in a direction generally perpendicular to the machine direction. The saw mounts 510a and 510b generally each comprise a precise lead screw and ground cylinder shaft. Saw position motors 570a and 570b move circular saws 520a and 520b, along saw mounts 510a and 510b, respectively. Each saw position motor 570a and 570b generally comprises a stepper or servo motor and optionally a brake to precisely move the circular saws 520a and 520b along saw mounts 510a and 510b. Each saw blade 521a and 521b is powered by a saw motor 523a and 532b. Saw motors 523a and 523b are generally electric motors that have a horsepower suitable for the operation. In most insulation cutting applications low horsepowers in the range of about 3 to about 25 horsepower are utilized, with the saws running at low r.p.m. in the range of about 8,000 to 12,000 r.p.m.
The blade cutting angle for blades 521a and 521b are each controlled by angle pivot motors 572a and 572b. The angle pivot motors 572a and 572b pivot the saw mounts 510a and 510b, along with the circular saws 520a and 520b. By rotating saw mounts 510a and 510b, the angle pivot motors 572a and 572b can cause the blades 521a and 521b to rotate in a full range of motion, allowing for virtually any angle to be cut. The angle pivot motors 572a and 572b generally comprise a servo or stepper motor, brake assembly and gear reducer.
The saw mounts 510a and 510b are mounted generally perpendicular across a generally parallel pair of mount supports 550a and 550b. The mount supports 550a and 550b each generally comprise two precise lead screws and a ground cylindrical shaft. Mount support 550b comprises lead screws 560a and 560b, to which one end of saw mounts 510a and 510b is mounted and moves along. The lead screws 560a and 560b are oppositely threaded to allow saw mounts 560a and 560b to move together or apart. The other ends of saw mounts 510a and 510b are likewise connected to lead screws 561a and 561b on mount support 550a. Lead screws 561a and 561b are likewise threaded to allow for saw mounts 510a and 510b to move together or apart. Saw mount position motors 530a and 532a both simultaneously move saw mount 510a along mount supports 550b and 550a. Saw mount position motors 530a and 532a operate in a master/slave relationship and move saw mount 510a in such a manner so as not to bind it. Saw mount position motors 530a and 532a both comprise a stepper or servo motor and a brake to precisely position the saw mount 510a along mount supports 550b and 550a.
In a similar fashion, saw mount position motors 530b and 532b position saw mount 510b along mount supports 550b and 550a. Saw mount position motors 530b and 532b also both comprise stepper or servo motors and a brake to accurately position the saw mount 510b along mount supports 550b and 550a. Saw mount position motors 530b and 532b also operate in a master/slave relationship to prevent binding of saw mount 510b.
Support guides 503 support the insulation 12 as it passes through the cutting station 500.
The apparatus of the present invention is preferably controlled by a computer, represented generally by control cabinet 40. Such a computer would control the conveyor motors 25 and 75, the billet auto loader 5, the backing station 30, all of the motors in cutting station 500, and vacuum system 60, and any other item to allow for automatic running of the apparatus.
In an actual operation for cutting V-grooves in insulation sections 12, the angle pivot motors 572a and 572b are used to set blades 521a and 521b at the proper desired angle. The blades 521a and 521b are positioned apart from each other at the proper distance by using saw mount position motors 530a and 530b and saw mount position motors 532a and 532b.
Since the angles on each cutting blade can be set independently of each other, the V-groove apparatus of the present invention is not limited to cutting an isosceles V-groove. Triangle shapes such as right angle, scalene, and obtuse may be cut. For example, one blade angle may be set at the vertical, while the other blade may be set at the desired angle. The resulting V-groove will not be an isosceles V-groove.
Furthermore, since circular saw 520a and 520b may be rotated through 360°, it is possible for one saw to cut a V-groove without aid of the other saw. This of course allows operation of the machine in the event that one circular saw suffers a mechanical failure. The lack of a carriage underneath allows for larger diameter blades to be substituted for blades 521a and 521b, to allow for cutting of thicker pieces of board.
The apparatus of the present invention may also comprise a planning station (not shown). It is desired that insulation sections 12 each have approximately the same thickness. While it is possible to order insulation sections 12 of a given thickness it is also understood that there is some variation in manufacturing tolerances. Thus it may be necessary to have a planning station appropriately located along the apparatus of the present system. Such a planning system generally comprises a band saw assembly disposed laterally across the conveyor 20, preferably located upstream of the backing station, so as not to remove the backing. The planning system should be adjustable so as to accommodate various thicknesses of insulation sections 12.
The heavy pieces of scrap material created by the sawing operation will drop below to a scrap conveyor 90 which is shown in FIG. 1. The lighter particles such as dust, are removed via an exhaust system shown generally at 60. Exhaust fan 65 has a rubberized blade to help break up the larger particles that are removed through exhaust opening 66 by the exhaust fan 65. A duct 67 transports the exhausted particles to a cyclone 63 which drops larger particles out below and sends the lighter particles to bag houses 61 where they are trapped on bag filters.
Once the insulation sections 12 have been properly cut at cutting station 500 they are then conveyed by conveyor 70 on conveyor belt 71 for further processing.
FIG. 7 shows another embodiment of this invention in which tank wrap having fibers generally oriented in the width direction, are manufactured from insulation sheets having fibers generally oriented in the lengthwise direction. With the exception of the backing station 30, this embodiment will utilize the apparatus as above described plus a reorienting station 80, a backing station 150, and a non-optional conveyor 200.
Reorienting station 80 allows the cut pieces 12a, having fibers oriented generally in the machine direction, to be guided off of conveyor belt 71 of conveyor 70 by reorienting guide 85 and land on conveyor 200 reoriented such that the fibers are now oriented generally perpendicular to the machine direction. The reoriented pieces 12b are then joined together in an end-to-end abutting relationship at butt joint adhesive station 88. To abut pieces 12b together, the conveyor system is stopped, and an engaging means 81 is used to press pieces 12b together so that the adhesive will adhere the pieces 12b together. The engaging means 81 may be any suitable linear actuator. In the embodiment shown, engaging means 81 is a piston. Once reoriented pieces 12b are joined together, the conveyor is restarted and backing 153 is then applied at backing station 150.
Conveyor 200 comprises endless loop conveyor belt 201 that is driven by motor 203. Drive belt 205 connects motor pulley 202 with conveyor drive pulley 207. The conveyor belt 201 is disposed on a series of rollers 209 (not all shown), and the entire conveyor 200 is supported by a frame, shown by legs 204. Conveyor 200 is located immediately downstream from conveyor 70 and is positioned lower than conveyor 70, utilizing adjustable legs 204.
In an actual operation to make tank wrap, cutting station 500 is operated to cut the insulation sections 12 into pieces 12a. This may be accomplished using both saws 520a and 520b with blades 521a and 521b in the vertical position. Alternatively the cutting station 500 could be operated with only one saw 520a or 520b in operation with the respective saw blade in the vertical position while the other saw is rotated out of the way.
The present invention is not limited to cutting any specific type of material, and generally any type of rigid insulation material may be processed. Examples of suitable insulation materials that may be processed by the present invention include those comprised of wood, perlite, fiberglass, mineral wool, and calcium silicate. While the present invention has been illustrated as processing insulation materials, it is not to be so limited. In fact, the present invention could have application in furniture manufacture and other type of manufacturing operations which require complex cutting geometries.
The apparatus of the present invention is also versatile enough to cut shapes other than V-grooves. For example, the blade may be rotated through a material during the cutting process to form a circular or elipital shape.
While prior art machines are generally limited to processing materials of density of no more than about 12 lb/cf, the present invention is not so limited. Higher density material may be cut by controlling the feeding and cutting speeds.
The description given herein is intended to illustrate the preferred embodiments of the present invention. It is possible for one of ordinary skill in the art to make various changes to the details of the present invention, including changes in the size, shape and materials, as well as in the details of the illustrated construction without departing from the spirit of this invention. Therefore, it is intended that all such variations be included within the scope of the present invention as claimed. | 4y
|
CROSS REFERENCE TO A RELATED APPLICATION
This application is a continuation application of co-pending application Ser. No. 12/531,988, filed Jan. 19, 2010; which is a National Stage Application of International Application Number PCT/EP2008/002277, filed Mar. 20, 2008; which claims priority to German Patent Application No. 102007016534.1, filed Apr. 5, 2007; all of which are incorporated herein by reference in their entirety.
The Sequence Listing for this application is labeled “January2010-ST25.txt”, which was created on Oct. 6, 2009, and is 19 KB. The entire contents is incorporated herein by reference in its entirety.
FIELD OF THE INVENTION
The present invention relates to novel expression cassettes and expression vectors, comprising three nucleic acid sequences for araA, araB and araD, each coding for a polypeptide of an L-arabinose metabolic pathway, in particular, a bacterial L-arabinose metabolic pathway. The invention particularly relates to expression cassettes and expression vectors, comprising codon-optimised nucleic acid sequences for araA, araB and araD. The invention further relates to host cells, in particular modified yeast strains containing the expression cassettes or expression vectors and expressing the polypeptides for the L-arabinose metabolic pathway, in particular, for the bacterial L-arabinose metabolic pathway. When using these modified host cells, arabinose is more effectively fermented by these cells, in particular into ethanol. The present invention is therefore relevant, inter alia, in connection with the production of biochemicals from biomass, such as bioethanol for example.
BACKGROUND OF THE INVENTION
The beer, wine and baking yeast Saccharomyces cerevisiae has already been used for centuries for the production of bread, wine and beer owing to its characteristic of fermenting sugar to ethanol and carbon dioxide. In biotechnology, S. cerevisiae is used particularly in ethanol production for industrial purposes, in addition to the production of heterologous proteins. Ethanol is used in numerous branches of industry as an initial substrate for syntheses. Ethanol is gaining increasing importance as an alternative fuel, due to the increasingly scarce presence of oil, the rising oil prices and continuously increasing need for petrol worldwide.
In order to produce bioethanol inexpensively and efficiently, the use of lignocellulose-containing biomass, such as for example straw, waste from the timber industry and agriculture and the organic component of everyday household waste, presents itself as an initial substrate. Firstly, said biomass is very convenient and secondly is present in large quantities. The three major components of lignocellulose are lignin, cellulose and hemicellulose. Hemicellulose, which is the second most frequently occurring polymer after cellulose, is a highly branched heteropolymer. It consists of pentoses (L-arabinose, D-xylose), uronic acids (4-O-methyl-D-glucuronic acid, D-galacturonic acid) and hexoses (D-mannose, D-galactose, L-rhamnose, D-glucose) (see FIG. 1 ). Although, hemicellulose can be hydrolized more easily than cellulose, but it contains the pentoses L-arabinose and D-xylose, which can normally not be converted by the yeast S. cerevisae.
In order to be able to use pentoses for fermentations, these must firstly enter the cell through the plasma membrane. Although S. cerevisiae is not able to metabolize D-xylose, it can uptake D-xylose into the cell. However, S. cerevisiae does not have a specific transporter. The transport takes place by means of the numerous hexosetransporters. The affinity of the transporters to D-xylose is, however, distinctly lower than to D-glucose (Kotter and Ciriacy, 1993). In yeasts which are able to metabolize D-xylose, such as for example P. stipitis, C. shehatae or P. tannophilus (Du Preez et al., 1986), there are both unspecific low-affinity transporters, which transport D-glucose, and also specific high-affinity proton symporters only for D-xylose (Hahn-Hagerdal et al., 2001).
In earlier experiments, some yeasts were found, such as for example Candida tropicalis, Pachysolen tannophilus, Pichia stipitis, Candida shehatae , which by nature ferment L-arabinose or can at least assimilate it. However, these yeast lack entirely the capability of fermenting L-arabinose to ethanol, or they only have a very low ethanol yield (Dien et al., 1996).
Conversion of L-arabinose
In order for the pentose L-arabinose to be metabolised by S. cerevisiae , it must enter into the cell via transport proteins and be converted to the metabolite D-xylulose-5-phosphate in three enzymatic steps. These three enzymatic steps may be made available to the yeast by heterologously expressed genes. D-xylulose-5-phosphate functions as an intermediate of the pentose phosphate pathway and can be decomposed further to yield ethanol under anaerobic conditions in the cell (see FIG. 2 ).
Becker and Boles (2003) describe the engineering and the selection of a laboratory strain of S. cerevisiae which is able to use L-arabinose for growth and for fermenting it to ethanol. This was possible due to the over-expression of a bacterial L-arabinose metabolic pathway, consisting of Bacillus subtilis AraA and Escherichia coli AraB and AraD and simultaneous over-expression of yeast galactose permease transporting L-arabinose in the yeast strain. Molecular analysis of the selected strain showed that the predetermining precondition for a use of L-arabinose is a lower activity of L-ribulokinase. However, inter alia, a very slow growth is reported from this yeast strain (see FIG. 2 ).
So far, it was only possible to express the native genes of bacterial arabinose metabolic pathways that are essential for metabolising arabinose in S. cerevisiae on single plasmids or to integrate them individually in the yeast genome, respectively (Karhumaa et al, 2006). This means that each yeast transformant with a functional arabinose metabolic pathway contained at least three plasmids or the genes integrated into the rDNA locus (Becker and Boles, 2003; Karhumaa et al, 2006).
The presence of the genes on different plasmids is associated with a number of disadvantages. On the one hand, plasmids that are present simultaneously represent additional stress for the yeast cells (“Plasmid stress”, Review of E. coli by Bailey (1993)). On the other hand, the plasmids used have strong homologies in their sequences, which can lead to loss of information within the plasmids due to homologous recombination (Wiedemann, 2005). However, the main disadvantages associated with the use of plasmids lie in the fact that they remain unstable in the strains without selection pressure and that they are not suitable for industrial use.
Moreover, it would be ideal for industrial applications if the microorganism used were able to metabolise all of the sugars present in the medium. Since the yeasts currently used industrially are not capable of metabolising the arabinose in the medium, it would be highly advantageous to provide the strains with this additional capability in a stable manner.
The object of the present invention is therefore to provide means that overcome the disadvantages known from the prior art of introducing genes of a bacterial L-arabinose metabolic pathway into host cells individually, and which in particular may be usable for industrial yeast strains.
BRIEF SUMMARY
The object is solved according to the invention by the provision of nucleic acid molecules comprising three nucleic acid sequences, each of which codes for a polypeptide of an L-arabinose metabolic pathway, in particular a bacterial L-arabinose metabolic pathway.
A nucleic acid molecule according to the invention is a recombinant nucleic acid molecule. Furthermore, nucleic acid molecules according to the invention comprise dsDNA, ssDNA, PNA, CNA, RNA or mRNA, or combinations thereof.
DETAILED DESCRIPTION OF THE INVENTION
The “L-arabinose metabolic pathway” or “bacterial L-arabinose metabolic pathway”, such as it occurs in E. coli , is shown in FIG. 2 . This metabolic pathway contains 3 enzymes: L-arabinose isomerase, L-ribulokinase and L-ribulose-5-P-4-epimerase. The genes that code for these enzymes are called araA, araB and araD. L-arabinose isomerase converts L-arabinose to L-ribulose, which is further metabolised to L-ribulose-5-phosphate by the L-ribulokinase. Finally, the L-ribulose-5-P-4-epimerase converts L-ribulose-5-phosphate to D-xylulose-5-phosphate. The intermediate metabolite D-xylulose-5-phosphate is formed by the heterologously expressed genes of the L-arabinose metabolic pathway, particularly the bacterial L-arabinose metabolic pathway, in the yeast cell. D-xylulose-5-phosphate functions as an intermediate of the pentose phosphate pathway and can be further decomposed to ethanol under anaerobic conditions in a yeast cell. Enzymes of the xylose metabolic pathway are also found in fungi, and these and other enzymes isolated from eukaryotes can also be used as enzymes for the L-arabinose metabolic pathway.
The three nucleic acid sequences of the nucleic acid molecules according to the invention, each of which codes for a polypeptide of an L-arabinose metabolic pathway, are preferably araA (L-arabinose isomerase), araB (L-ribulokinase) and araD (L-ribulose-5-P-4-epimerase).
The nucleic acid molecules according to the invention preferably comprise nucleic acid sequences that are identical with the naturally occurring nucleic acid sequence or that have been codon-optimised for use in a host cell.
Each amino acid is encoded by one codon. However, there are several different codons that code for an individual amino acid. The genetic code is, thus, degenerated. The preferred codon selection for a corresponding amino acid varies from one organism to another. For example, problems may arise in heterologously expressed genes if the host organism or host cell has a very different codon usage. The gene can only be expressed very slowly, if at all. Differing codon usage may even be observed in genes of different metabolic pathways within the same organism. The glycolysis genes from S. cerevisiae are known to be expressed strongly. They have a highly restrictive codon usage. Adapting the codon usage of the bacterial genes of the arabinose metabolic pathway to the codon usage of the glycolysis genes from S. cerevisiae leads to improved arabinose metabolism in yeast.
For codon optimisation, the inventors did not rely on the usual platforms of synthetic gene designers for heterologous expression (such as Synthetic Gene Designer as described in Wu et al. 2006), instead they adapted the codon optimisation specifically to the codon usage of the glycolysis genes in the yeast. The glycolysis genes in the yeast have a highly restrictive codon usage, which is aligned with the frequency of the corresponding tRNA. The glycolysis genes use mainly codons for which there are high concentrations of the corresponding tRNAs, which in turn results in greater translation efficiency and gene expression (Bennetzen and Hall, 1982, Hoekema et al., 1987). In contrast, the usual synthetic gene designers are geared more to the average codon usage of all the genes in an organism, not just those that are highly expressed, and they also take into account other factors, such as stability. Accordingly, codon optimisation with the aid of such an electronic platform, such as the one described in Wu et al. 2006, results in a nucleic acid sequence that is entirely different from the one disclosed in this patent specification.
According to the invention, at least two of the three nucleic acid sequences, and preferably all three nucleic acid sequences, have been codon optimised for use in a host cell.
The nucleic acid sequence for araB (L-ribulokinase) and the nucleic acid sequence for araD (L-ribulose-5-P-4-epimerase) are preferably derived from E. coli . Thereby, the nucleic acid sequence for araB preferably comprises a nucleic acid sequence with SEQ ID NO: 1 and the nucleic acid sequence for araD preferably comprises a nucleic acid sequence with SEQ ID NO: 2.
The nucleic acid sequence with SEQ ID NO: 1 is the gene sequence of the open reading frame (ORF) of araB mut from E. coli in a codon-optimised form.
The nucleic acid sequence with SEQ ID NO: 2 is the gene sequence of the open reading frame (ORF) of araD from E. coli in a codon-optimised form.
The nucleic acid sequence for araA (L-arabinose isomerase) is preferably derived from Bacillus licheniformis or Clostridium acetobutylicum.
These L-arabinose isomerases are advantageous for the growth of yeast transformants on an arabinose medium. Example 1 shows (see also FIG. 4 ) that, compared with the isomerase from B. subtilis , particularly the expression of the L-arabinose isomerase from C. acetobutylicum and B. licheniformis significantly improved the growth of yeast transformants on arabinose medium.
Thereby, the nucleic acid sequence for araA preferably comprises a nucleic acid sequence with SEQ ID NO: 3, 4 or 5.
The nucleic acid sequence with SEQ ID NO: 3 is the gene sequence of the open reading frame (ORF) of araA from Bacillus licheniformis in a codon-optimised form.
The nucleic acid sequence with SEQ ID NO: 4 is the gene sequence of the open reading frame (ORF) of araA from Bacillus licheniformis.
The nucleic acid sequence with SEQ ID NO: 5 is the gene sequence of the open reading frame (ORF) of araA from Clostridium acetobutylicum.
Accordingly, the nucleic acid sequences with SEQ ID NOs: 4 and 5 are naturally occurring nucleic acid sequences.
In a particularly preferred embodiment, a nucleic acid molecule according to the invention comprises the nucleic acid sequence with SEQ ID NO: 1, the nucleic acid sequence with SEQ ID NO: 2 and the nucleic acid sequence with SEQ ID NO: 3, 4 or 5. Most preferable is a nucleic acid molecule according to the invention that comprises the nucleic acid sequence with SEQ ID NO: 1, the nucleic acid sequence with SEQ ID NO: 2, and the nucleic acid sequence with SEQ ID NO: 3.
Yeast transformants that have the two codon-optimised genes of the kinase (araB, SEQ ID NO: 1) and the epimerase (araD, SEQ ID NO: 2), and yeast transformants in which all three genes have been codon-optimised (araB: SEQ ID NO: 1, araD: SEQ ID NO: 2 and araA: SEQ ID NO: 3), show a considerable growth advantage in a medium containing arabinose compared to yeast transformants that have only one codon-optimised gene. The strains show a considerably shorter lag phase and grow to their maximum optical density considerably faster (see example 2). The combination of three codon-optimised genes enables recombinant S. cerevisiae cells to convert L-arabinose considerably more efficiently.
The object is further solved according to the invention by the provision of expression cassettes comprising a nucleic acid molecule according to the invention.
Furthermore, the expression cassettes according to the invention preferably comprise promoter and terminator sequences.
Promoter sequences are preferably selected from HXT7, truncated HXT7, PFK1, FBA1, PGK1, ADH1 and TDH3.
Terminator sequences are preferably selected from CYC1, FBA1, PGK1, PFK1, ADH1 and TDH3.
Thereby, it is preferable that different pairs of promoter and terminator sequences control each of the three nucleic acid sequences. This is necessary to avoid possible homologous recombination between the promoter and/or terminator regions/sequences.
According to the invention, the pairs of promoter and terminator sequences are preferably selected from an HXT7 or truncated HXT7 promoter and CYC1 terminator, a PFK1 promoter and FBA1 terminator, and an FBA1 promoter and PGK1 terminator.
Particularly preferred is a nucleic acid sequence for araA controlled by the HXT7 or truncated HXT7 promoter and the CYC1 terminator.
Particularly preferred is a nucleic acid sequence for araB controlled by the PFK1 promoter and the FBA1 terminator.
Particularly preferred is a nucleic acid sequence for araD controlled by the FBA1 promoter and the PGK1 terminator.
For further details, see also example 3.
The expression cassettes according to the invention preferably comprise 5′ and/or 3′ recognition sequences as well.
Recognition sequences of the enzymes PacI and AscI are preferred.
The object is further solved according to the invention by provision of expression vectors, comprising a nucleic acid molecule or an expression cassette according to the invention.
The expression vectors according to the invention preferably comprise a selection marker as well.
The selection marker is preferably selected from a leucine marker, an uracil marker or a dominant antibiotic marker. A preferred dominant antibiotic marker is selected from geneticin, hygromycin and nourseothricin.
An expression vector according to the invention is preferably selected from the group p425H7synthAra, pRS303X, p3RS305X or p3RS306X.
For further details, see also example 3.
For industrial applications, it would be ideal if the microorganism used were capable of metabolising all of the sugars present in the medium. Since the yeasts that are currently used are not capable of metabolising the arabinose in the medium, it would be highly advantageous to provide the strains with this additional capability in stable manner. In order to achieve this, an expression vector with genes of an arabinose metabolic pathway is highly beneficial. This expression vector can then be genomically integrated in a stable manner and can allow for the metabolisation of arabinose in industrial strains.
This invention succeeded (see also Examples) in constructing a vector that codes for an expression cassette with three genes of an arabinose metabolic pathway, particularly a bacterial metabolic pathway. In this way, it is possible to circumvent the problems that may arise when several plasmids are present in the same cell at the same time (“Plasmid stress”, Review of E. coli by Bailey (1993)). Furthermore, stable genomic integration of the arabinose metabolic pathway genes is enabled. The problems associated with constructing an expression cassette of the arabinose metabolic pathway genes and integrating it in a manner that is genomically stable have already been shown by Becker (2003) and Wiedemann (2005).
By selecting promoters and terminators in combination with using the improved L-arabinose isomerase and the codon-optimised versions of the genes involved, the construction of this functional expression cassette according to the invention was achieved.
The expression cassette constructed with the three genes according to the invention represents an excellent starting point for a direct genomic integration as well as enables subcloning into the integrative plasmids of the series pRS303X, pRS305X and pRS306X (Taxis and Knop, 2006).
Furthermore, a plurality of experimental obstacles and difficulties had to be overcome in the process of cloning the three genes with the different promoters and terminators, and these are reported in greater detail in the examples and figures.
Finding an L-arabinose isomerase that functions better, such as is more efficient, in yeast. Cloning the isomerase proved to be difficult and time-consuming. The vector according to the invention is the first vector described that contains all the essential genes for converting arabinose in yeast. The vector contains all the genes in functional form and enables the recombinant yeast a good arabinose growth. Functionality as well as very good arabinose growth were by no means expected.
The object is further solved according to the invention by providing host cells that contain a nucleic acid molecule according to the invention, an expression cassette according to the invention, or an expression vector according to the invention.
In a particularly preferred embodiment, a nucleic acid molecule according to the invention, an expression cassette according to the invention or an expression vector according to the invention is integrated in stable manner in the genome of the host cell.
For industrial applications, it would be ideal if the microorganism used were capable of metabolising all of the sugars present in the medium. Since the yeasts that are currently used are not capable of metabolising the arabinose in the medium, it would be highly advantageous to provide the strains with this additional capability in stable manner. In order to achieve this, a nucleic acid molecule according to the invention, an expression cassette according to the invention or an expression vector according to the invention can be genomically integrated in stable manner and can allow for the metabolisation of arabinose in industrial strains. Using the nucleic acid molecules according to the invention ensures a very efficient arabinose conversion in industrial strains. Previously, the practice of introducing the genes of the bacterial L-arabinose metabolic pathway individually was associated with the difficulty that the genes were not present in an optimal ratio to each other. The transformations were time-consuming and the resulting arabinose metabolism was often not as efficient as desired. Moreover, the properties provided were often not stable. In contrast, the expression cassette according to the invention or the expression vector according to the invention, respectively, enable the bacterial L-arabinose metabolic pathway to be introduced quickly and functionally. With the selection of the promoters, it was possible to combine the genes together on one nucleic acid molecule, one expression cassette or one expression vector. The integration of the nucleic acid molecule according to the invention, the expression cassette according to the invention or the expression vector according to the invention, respectively, further guarantees an efficient arabinose conversion.
A host cell according to the invention is preferably a fungus cell, and more preferably a yeast cell, such as Saccharomyces species, Kluyveromyces sp., Hansenula sp., Pichia sp. or Yarrowia sp.
In particular, a host cell according to the invention is selected from BWY1, CEN.PK113-7D, Red Star Ethanol Red and Fermiol.
The object is further solved according to the invention by providing methods for producing bioethanol. One method according to the invention comprises the expression of a nucleic acid molecule according to the invention, an expression cassette according to the invention, or an expression vector according to the invention in a host cell.
Thereby, the method is preferably carried out in a host cell according to the invention.
The object is further solved according to the invention by the use of a nucleic acid molecule according to the invention, an expression cassette according to the invention, an expression vector according to the invention, or a host cell according to the invention to produce bioethanol.
The object is further solved according to the invention by the use of nucleic acid molecule according to the invention, an expression cassette according to the invention, an expression vector according to the invention, or a host cell according to the invention for recombinant fermentation of pentose-containing biomaterial.
For the methods and uses, see the examples and figures. The results of fermentation recorded in example 2 show that especially the codon-optimised genes of araA, araB and araD enable the yeast transformants to metabolise arabinose more efficiently. The result of this is faster conversion of the sugar and a significantly higher ethanol yield.
The object is further solved according to the invention by providing a polypeptide selected from the group of
a. a polypeptide which is at least 70%, preferably at least 80% identical to the amino acid sequence that is coded by SEQ ID NO: 3, 4 or 5, and has an in vitro and/or in vivo pentose isomerase function,
b. a naturally occurring variant of a polypeptide including the amino acid sequence that is coded by SEQ ID NO: 3, 4 or 5, which has an in vitro and/or in vivo pentose isomerase function,
c. a polypeptide which is identical to the amino acid sequence that is coded by SEQ ID NO: 3, 4 or 5, and has an in vitro and/or in vivo pentose isomerase function, and
d. a fragment of the polypeptide from a., b. or c., comprising a fragment of at least 100, 200 or 300 continuous amino acids of the amino acid sequence that is coded by SEQ ID NO: 3, 4 or 5.
Such a polypeptide is preferably selected from the group of
a. a polypeptide which is at least 70%, preferably at least 80% identical to the amino acid sequence according to SEQ ID NO: 6 or 7, and has an in vitro and/or in vivo pentose isomerase function,
b. a naturally occurring variant of a polypeptide comprising the amino acid sequence according to SEQ ID NO: 6 or 7, which has an in vitro and/or in vivo pentose isomerase function,
c. a polypeptide which is identical to the amino acid sequence according to SEQ ID NO: 6 or 7, and has an in vitro and/or in vivo pentose isomerase function, and
d. a fragment of the polypeptide from a., b. or c., comprising a fragment of at least 100, 200 or 300 continuous amino acids according to SEQ ID NO: 6 or 7.
A polypeptide according to the invention preferably comprises a polypeptide which is at least 90%, preferably 95% identical to the amino acid sequence that is coded by SEQ ID NO: 3, 4 or 5, and has an in vitro and/or in vivo pentose isomerase function.
Such a polypeptide according to the invention preferably comprises a polypeptide which is at least 90%, preferably 95% identical to the amino acid sequence according to SEQ ID NO: 6 or 7, and has an in vitro and/or in vivo pentose isomerase function.
The amino acid sequence with SEQ ID NO. 6 is the amino acid sequence of Bacillus licheniformis L-arabinose isomerase (araA). This amino acid sequence is preferably coded by the nucleic acid sequences with SEQ ID NOs. 3 or 4.
The amino acid sequence with SEQ ID NO. 7 is the amino acid sequence of Clostridium acetobutylicum L-arabinose isomerase (araA). This amino acid sequence is preferably coded by the nucleic acid sequence with SEQ ID NO. 5.
The pentose is arabinose, in particular L-arabinose.
The polypeptide according to the invention preferably originates from a bacterium, more preferably from Bacillus licheniformis or Clostridium acetobutylicum.
These L-arabinose isomerases are advantageous for the growth of yeast transformants on arabinose medium. A number of different experiments indicated that the L-arabinose isomerase from B. subtilis that was used previously represents a limiting step in the decomposition of arabinose in yeast (Becker and Boles, 2003; Wiedemann, 2003; Karhumaa et al, 2006; Sedlak and Ho, 2001). Example 1 shows (see also FIG. 4 ) that the growth of yeast transformants on arabinose medium is significantly improved particularly by the expression of L-arabinose isomerase from C. acetobutylicum and from B. licheniformis , in comparison to the isomerase from B. subtilis.
The object is further solved according to the invention by providing an isolated nucleic acid molecule that codes for a polypeptide according to the invention.
Additionally, the object is further solved according to the invention by providing a host cell that contains such an isolated nucleic acid molecule.
For preferred embodiments of the isolated nucleic acid molecule and of the host cells, reference is made to the embodiments described above.
The polypeptide according to the invention, the isolated nucleic acid molecule according to the invention and the host cell according to the invention are preferably used in the production of bioethanol and for recombinant fermentation of pentose-containing biomaterial.
A further aspect of the present invention are host cells that contain one or more modifications, such as nucleic acid molecules.
An additional modification of such kind is a host cell that overexpresses a TAL1 (transaldolase) gene, such as is described by the inventors in EP 1 499 708 B1, for example.
A further such additional modification is a host cell that contains a nucleic acid coding for a specific L-arabinose transporter gene (araT), particularly such as a specific L-arabinose transporter gene from the genome of P. stipitis , such as is described by the inventors in German Patent Application DE 10 1006 060 381.8, filed on Dec. 20, 2006.
Further biomass with significant amounts of arabinose (source of the data: U.S. Department of Energy:
Type of biomass
L-arabinose [%]
Switchgrass
3.66
Large bothriochloa
3.55
Tall fescue
3.19
Robinia
3
Corn stover
2.69
Wheat straw
2.35
Sugar can bagasse
2.06
Chinese lespedeza
1.75
Sorghum bicolor
1.65
The nucleic acids, expression cassettes, expression vectors and host cells according to the invention are also of great importance for their utilization.
Possible uses of the nucleic acids, expression cassettes, expression vectors and host cells according to the invention include both the production of bioethanol and the manufacture of high-quality precursor products for further chemical synthesis.
The following list originates from the study “Top Value Added Chemicals From Biomass”. Here, 30 chemicals were categorized as being particularly valuable, which can be produced from biomass.
Number of
C atoms
Top 30 Candidates
1
hydrogen, carbon monoxide
2
3
glycerol, 3-hydroxypropionic acid, lactic acid, malonic acid,
propionic acid, serine
4
acetoin, asparaginic acid, fumaric acid, 3-
hydroxybutyrolactone, malic acid, succinic acid, threonine
5
arabitol, furfural, glutamic acid, itaconic acid, levulinic acid,
proline, xylitol, xylonic acid
6
aconitic acid, citrate, 2,5-furandicarboxylic acid, glucaric acid,
lysine, levoglucosan, sorbitol
It is important to have the nucleic acids, expression cassettes, expression vectors and host cells according to the invention available as soon as these chemicals are produced from lignocellulose by biokonversion (e.g. fermentations with yeasts).
The present invention will be explained in greater detail in the following figures, sequences and examples, without limitation thereto. The references cited are fully incorporated herein by reference thereto. In the sequences and figures are shown:
BRIEF DESCRIPTION OF THE SEQUENCES
SEQ ID NO: 1 shows the gene sequence of the open reading frame (ORF) of araB mut from E. coli in a codon-optimised form.
SEQ ID NO: 2 shows the gene sequence of the open reading frame (ORF) of araD from E. coli in a codon-optimised form.
SEQ ID NO: 3 shows the gene sequence of the open reading frame (ORF) of araA from B. licheniformis in a codon-optimised form.
SEQ ID NO: 4 shows the gene sequence of the open reading frame (ORF) of araA from B. licheniformis.
SEQ ID NO: 5 shows the gene sequence of the open reading frame (ORF) of araA from C. acetobutylicum.
SEQ ID NO. 6 shows the amino acid sequence of the Bacillus licheniformis L-arabinose isomerase (araA). This amino acid sequence is preferably coded by the nucleic acid sequences with SEQ ID NOs. 3 or 4.
SEQ ID NO. 7 shows the amino acid sequence of the Clostridium acetobutylicum L-arabinose isomerase (araA). This amino acid sequence is preferably coded by the nucleic acid sequence with SEQ ID NO. 5.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 Composition of the biomass.
Biomass consists of cellulose, hemicellulose and lignin. The second most frequently occurring hemicellulose is a highly branched polymer consisting of pentoses, uronic acids and hexoses. The hemicellulose consists in a large proportion of the pentoses xylose and arabinose.
FIG. 2 Scheme of the metabolism of L-arabinose in recombinant S. cerevisiae by integration of a bacterial L-arabinose metabolic pathway.
FIGS. 3A-3B Vectors used and their construction.
The initial plasmid for construction of the vector p425H7synthAra ( FIG. 3 A) was the plasmid p425HXT7-6HIS ( FIG. 3 B). The open reading frames of the codon-optimised genes of araA from B. licheniformis and araB mut and araD from E. coli were amplified and cloned into the plasmid p425HXT7-6HIS after various promoters and terminators. The primers were selected in such manner that the resulting expression cassette was flanked by the restriction sites of enzymes PacI and AscI. Thereby, the plasmid p425H7synthAra was produced, which has a leucine marker.
FIG. 4 Growth on arabinose using various L-arabinose isomerase genes.
Growth curves of recombinant S. cerevisiae strains containing the bacterial L-arabinose metabolism with various L-arabinose isomerases. Growth tests were conducted in 5 ml SM medium with 2% arabinose under aerobic conditions. The L-arabinose isomerases of C. acetobutylicum, B. licheniformis, P. pentosaceus, L. plantarum and L. mesenteroides were tested. The L-arabinose isomerase from B. subtilis and the empty vector p423HXT7-6HIS were used as controls.
FIG. 5 Growth on arabinose using codon-optimised arabinose metabolic pathway genes.
Growth curves of recombinant S. cerevisiae strains containing the bacterial L-arabinose metabolism with different combinations of codon-optimised genes and the genes with original sequences. Growth tests were conducted in 5 ml SM medium with 2% arabinose under aerobic conditions. Each of the combinations that contained one of the codon optimised genes respectively, and the combination containing all three codon-optimised genes were tested. In addition, the combination in which the codon-optimised genes of kinase and epimerase were present was also tested. A recombinant yeast strain with the four genes having the original sequences was used as a control.
FIG. 6A-6B Ethanol formation using codon-optimised arabinose metabolic pathway genes.
The figure shows the results of HPLC analyses of the media supernatants from two fermentations. ( 6 A) One fermentation was carried out with strain BWY1, which possesses plasmids p423H7synthIso, p424H7synthKin, p425H7synthEpi and pHL125 re (3xsynth). ( 6 B) In the other fermentation, strain BWY1 was tested, containing plasmids p423H7araABs re , p424H7araB re , p425H7araD re and pHL125 re (3xre). The fermentations were carried out in SFM medium with 3% L-arabinose. The strains were grown to a high optical density in the fermenter.
Then, the fermentation was changed to anaerobic conditions (after 48 hours). The plots show arabinose consumption and ethanol production.
FIG. 7 Growth on arabinose using the constructed expression plasmid p425H7-synthAra.
Growth curves of recombinant S. cerevisiae strains containing bacterial L-arabinose metabolism in the form of the vector p425H7-synthAra. Growth tests were conducted in 5 ml SC medium with 2% arabinose under aerobic conditions. A recombinant yeast strain with the plasmids p423H7araABs re , p424H7araB re , p425H7araD re and pHL125 re , which had been tested in 5 ml SM medium with 2% arabinose, was used as the control.
EXAMPLE
Methods
1. Strains and Media
Bacteria
E. coli SURE (Stratagene) E. coli DH5α (Stratagene) Bacillus licheniformis (DSMZ) Clostridium acetobutylicum (DSMZ) Leuconostoc mesenteroides (DSMZ) Pediococcus pentosaceus (DSMZ) Lactobacillus plantarum (DSMZ)
Full medium LB 1% Trypton, 0.5% yeast extract, 0.5% NaCl, pH 7.5 (see Maniatis, 1982). 40 μg/ml ampicillin was added to the medium after autoclaving for selection based on plasmid-coded antibiotic resistance. Solid culture media also contained 2% agar. Culturing was performed at 37° C.
Yeast
Strain BWY1:
BWY1 is based on the strain JBY25 (MATa leu2-3,112 ura3-52 trp1-289 his3-Δ1MAL2-8c SUC2+ unknown mutations for better growth on arabinose); the strain JBY25 was selected further and possesses additional mutations for improved growth on L-arabinose under reduced oxygen conditions (Wiedemann, 2005)
Synthetic Complete Selective Medium SC:
0.67% yeast nitrogen base w/o amino acids, pH 6.3, amino acid/nucleobase solution, carbon source at the concentration indicated in each case
Synthetic Minimal Selective Medium SM:
0.16% yeast nitrogen base w/o amino acid and ammonium sulphate, 0.5% ammonium sulphate, 20 mM potassium dihydrogen phosphate, pH 6.3, carbon source at the concentration indicated in each case
Synthetic Fermentation Medium (Mineral Medium) SFM:
(Verduyn et al., 1992), pH 5.5 Salts: (NH 4 ) 2 SO 4 , 5 g/l; KH 2 PO 4 , 3 g/l; MgSO 4 *7H 2 O, 0.5 g/l Trace elements: EDTA, 15 mg/l, ZnSO 4 *4.5 mg/l; MnCl 2 *4H 2 O, 0.1 mg/l; CoCl 2 *6H 2 O, 0.3 mg/l; CuSO 4 , 0.192 mg/l; Na 2 MoO 4 *2H 2 O, 0.4 mg/l; CaCl 2 *2H 2 O, 4.5 mg/l; FeSO 4 *7H 2 O, 3 mg/l; H 3 BO 3 , 1 mg/l; KI, 0.1 mg/l Vitamins: Biotin, 0.05 mg/l; p-aminobenzoic acid, 0.2 mg/l; nicotinic acid, 1 mg/l; Calcium pantothenate, 1 mg/l; pyridoxin-HCL, 1 mg/l; thiamin-HCL, 1 mg/l; M inositol, 25 mg/1
Concentration of amino acids and nucleobases in the synthetic complete medium (based on Zimmermann, 1975): Adenine (0.08 mM), arginine (0.22 mM), histidine (0.25 mM), isoleucine (0.44 mM), leucine (0.44 mM), lysine (0.35 mM), methionine (0.26 mM), phenylalanine (0.29 mM), tryptophan (0.19 mM), threonine (0.48 mM), tyrosine (0.34 mM), uracil (0.44 mM), valine (0.49 mM). L-arabinose and D-glucose were used as the carbon source.
Solid full and selective media also contained 1.8% agar. The yeast cells were cultured at 30° C. The synthetic mineral medium used for the fermentations contained salts, trace metals and vitamins in the concentrations listed above and L-arabinose as the carbon source. Stock solutions of the trace metals and of the vitamins were prepared. Both solutions were sterile filtered. Both were stored at 4° C. The pH value are critically important to the preparation of the trace metal solution. The various trace elements had to be completely dissolved in water one after the other in the order given above. After each addition, the pH value had to be adjusted to 6.0 with KOH before the next trace element could be added. Finally, the pH value was adjusted to 4.0 with HCl. 200 μl antifoaming agent (Antifoam2004, Sigma) was added to the medium to prevent foaming. Since the tests were carried out under anaerobic conditions, 2.5 ml/l of a Tween80-Ergosterol solution had to be added to the medium after autoclaving. This consists of 16.8 g Tween80 and 0.4 g Ergosterol, which was filled to 50 ml with ethanol and dissolved therein. The solution was sterile filtered. The salts and the antifoaming agent were autoclaved together with the complete fermenter. The arabinose was autoclaved separately from the rest of the medium. After the medium cooled down, the trace elements and vitamins were added to it.
2. Plasmids
Plasmid Source/Reference Description p423HXT7-6HIS Becker and Boles, 2003 2μ expression plasmid for overexpression of various genes (=p423H7) and for fusing the E. coli L-arabinose isomerase with an His 6 epitope; HIS3 selection marker gene, shortened HXT7 promoter and CYC1 terminator (Hamacher et al., 2002) p424HXT7-6HIS Becker and Boles, 2003 2μ expression plasmid for overexpression of various genes (=p424H7) and for fusing the mutated and the wild type E. coli L- ribulokinase with an His 6 epitope; TRP1 selection marker gene, shortened HXT7 promoter and CYC1 terminator (Hamacher et al., 2002) p425HXT7-6HIS Becker and Boles, 2003 2μ expression plasmid for overexpression of various genes; (=p425H7) LEU2 selection marker gene, shortened HXT7 promoter and CYC1 terminator (Hamacher et al., 2002) p426HXT7-6HIS Hamacher et al., 2002 2μ expression plasmid for overexpression of genes (=p426H7) producing an His 6 epitope; URA3 selection marker gene, shortened HXT7 promotor and CYC1 terminator p423H7araABs re Becker and Boles, 2003 B. subtilis araA in p423HXT7-His, re-isolated from JBY25- 4M p424H7araB Becker and Boles, 2003 E. coli araB in p423HXT7-His p424H7araB re Becker and Boles, 2003 E. coli araB in p423HXT7-His; re-isolated from JBY25- 4M, mutation in araB, which enables arabinose growth p425H7araD re Becker and Boles, 2003 E. coli araD in p425HXT7-His; re-isolated from JBY25- 4M p423H7-synthIso B. licheniformis araA codon-optimised in p423HXT7-His p424H7-synthKin E. coli araB codon-optimised in p424HXT7-His, with mutation in araB p425H7-synthEpi E. coli araD codon-optimised in p425HXT7-His p425H7-synthAra 2μ plasmid with codon-optimised genes araA, araB mut and araD; araA under control of the FBA1 promoter and PGK1 terminator, araB mut under control of the PFK1 promoter and FBA1 terminator, and araD under control of the shortened HXT7 promoter and the CYC1 terminator, LEU2 selection marker gene pHL125 re Liang and Gaber, 1996 2μ plasmid with the GAL2 gene expressed after the ADH1 promoter, URA3 selection marker gene; re-isolated from JBY25-4M
3. Transformation:
Transformation of E. coli
The E. coli cells were transformed by the electroporation method described by Dower et al. (1988) and Wirth (1993) using an Easyject prima device (EQUIBO).
Transformation of S. cerevisiae
S. cerevisiae strains were transformed with plasmid DNA or DNA fragments using the lithium acetate method of Gietz and Woods (1994).
4. Preparation of DNA
Isolation of Plasmid DNA from E. coli
Plasmid DNA was isolated from E. coli with the alkaline lysis procedure developed by Birnboim and Doly (1979), modified according to Maniatis et al. (1982), or alternatively with the “QIAprep Spin Miniprep Kit” manufactured by Qiagen.
Highly pure plasmid DNA for sequencing was prepared with the “Plasmid Mini Kit” manufactured by Qiagen according to the manufacturer's instructions.
Isolation of Plasmid DNA from S. cerevisiae
The cells of a stationary yeast culture (5 ml) were harvested by centrifuging, washed and resuspended in 400 μl P1 buffer (Plasmid Mini Kit, Qiagen). After the addition of 400 μl P2 buffer and ⅔ volume glass beads (Ø0.45 mm, cell disruption was performed by shaking for 5 minutes on a Vibrax (Vibrax-VXR manufactured by Janke & Kunkel or IKA). The residue was filled with ½ volume P3 buffer, mixed and incubated on ice for 10 min. After centrifuging for 10 minutes at 13000 rpm, the plasmid DNA was precipitated at room temperature by adding 0.75 ml isopropanol to the residue. The DNA was pelletized by centrifuging at 13000 rpm for 30 min. and washed with 70% ethanol, dried and resuspended in 20 μl water. 1 μl of the DNA was used for the transformation in E. coli.
Determination of DNA Concentration
The DNA concentration was measured by spectrophotometry in a wavelength range of 240-300 nm. If the purity of the DNA, as determined by the quotient E 260nm /E 280nm , is 1.8, extinction E 260nm =1.0 corresponds to a DNA concentration of 50 μg dsDNA/ml (Maniatis et al., 1982).
DNA Amplification Using PCR
Use of the Phusion™ High Fidelity System
The polymerase chain reaction was carried out in a total volume of 50 μl with the “Phusion™ High Fidelity PCR System” manufactured by the company Finnzymes in accordance with the manufacturer's instructions. Each stock solution consisted of 1-10 ng DNA or 1-2 yeast colonies as a synthesis model, 0.2 mM dNTP-Mix, 1× buffer 2 (contains 1.5 mM MgCl 2 ), 1 U polymerase, and 100 pmol of each of the corresponding oligonucleotide primers. The PCR reaction was carried out in a thermocycler manufactured by the company Techne and the following PCR conditions were selected according to requirements:
1. 1x
30 sec, 98° C.
Denaturation of DNA
2. 30x
10 sec, 98° C.
Denaturation of DNA
30 sec, 56-62° C.
Annealing/binding of oligonucleotides to the
DNA
0.5-1 min, 72° C.
DNA synthesis/elongation
3. 1x
7 min, 72° C.
DNA synthesis/elongation
The polymerase was added after the first denaturation step (“hot start PCR”). The number of synthesis steps, the annealing temperature and the elongation time were adapted to the specific melting temperatures of the oligonucleotides used and the size of the expected product. The PCR products were tested with agarose gel electrophoresis and then cleaned up.
DNA Purification of PCR Products
The PCR products were purified with the “QIAquick PCR Purification Kit” manufactured by Qiagen in accordance with the instructions of the manufacturer.
Gel Electrophoretic Separation of DNA Fragments
DNA fragments having a size of 0.15-20 kb were separated in 0.5-1% agarose gels with 0.5 μg/ml ethidium bromide. 1×TAE buffer (40 mM Tris, 40 mM acetic acid, 2 mM EDTA) was used as the gel and running buffer (Maniatis et al., 1982). A lambda phage DNA digested with the restriction endonucleases EcoRI and HindIII was used as the size standard. Before loading, 1/10 volume blue marker (1×TAE buffer, 10% glycerin, 0.004% bromophenol blue) was added to the DNA samples, which were rendered visible after separation by irradiation with UV light (254 nm).
Isolation of DNA Fragments from Agarose Gels
The desired DNA fragment was cut out of the TAE agarose gel under long-wave UV light (366 nm) and isolated with the “QIAquick Gel Extraction Kit” manufactured by Qiagen in accordance with the manufacturer's instructions.
5. Enzymatic Modification of DNA
DNA Restriction
Sequence-specific cleaving of the DNA with restriction endonucleases was conducted for 1 hour with 2-5 U enzyme per μg DNA under the incubation conditions recommended by the manufacturer.
Example 1
Screen for Better L-arabinose Isomerases
A) Performance of the Screen
Several experiments indicated that the L-arabinose isomerase from B. subtilis represents a limiting step in the breakdown of arabinose in yeast (Becker and Boles, 2003; Wiedemann, 2003; Karhumaa et al, 2006; Sedlak and Ho, 2001). In order to improve the arabinose metabolic path, five L-arabinose isomerases from different organisms were tested.
For this, genomic DNA was isolated from the organisms C. acetobutylicum, B. licheniformis, P. pentosaceus, L. plantarum and L. mesenteroides (see “Isolation of plasmid DNA from S. cerevisiae ”). The cells were cultivated, harvested and absorbed in the buffer. Cell disruption was effected using glass beads. Then, the DNA was precipitated, washed, and used for the PCR. The open reading frame (ORF) of araA from the organisms listed was amplified with primers, which also had homologous areas to the HXT7 promoter and CYC1 terminator. The PCR products obtained were transformed in yeast together with the EcoRI/BamHI linearised vector p423HXT7-6His and cloned by in vivo recombination into the plasmid between the HXT7 promoter and CYC1 terminator. The sequence of the plasmids obtained was verified by restriction analysis. The functionality of the new isomerases and their effect on the arabinose metabolism also needed to be studied.
For this purpose, recombinant yeast strains were produced, containing one of the new isomerases and the rest of the bacterial arabinose metabolic pathway genes (p424H7araB re , p425H7araD re and pHL125 re ).
B) Growth Behaviour
Growth of the strains was tested under aerobic conditions in a medium containing arabinose. The recombinant yeast strain containing the isomerase from B. subtilis was used as the control. A yeast strain with the empty vector p423HXT7-6HIS was constructed as the negative control.
The strains with the various isomerase plasmids were cultured in SM medium with 2% arabinose and inoculated with a OD 600nm =0.2 in 5 ml SM medium with 2% arabinose. This was incubated in test tubes on a shaking flask under aerobic conditions at 30° C. Samples were taken regularly to determine optical density.
The results are shown in FIG. 4 . It was shown that, compared with the isomerase from B. subtilis , particularly the expression of L-arabinose isomerase from C. acetobutylicum and from B. licheniformis significantly improved the growth of yeast transformants on arabinose medium.
Example 2
Codon-Optimisation of Genes for Arabinose Decomposition in Yeast
A) Codon-Optimisation of Genes According to the Codon Usage of the Glycolysis Genes from S. cerevisiae
The preferred codon usage of the glycolysis genes from S. cerevisiae was calculated and is listed in table 1. The ORF of genes araA and araB mut from E. coli were codon-optimised as well as the ORF of the gene araA from B. licheniformis . This means, the sequences of the open reading frames were adapted to the preferred codon usage listed below. The protein sequence of the enzymes remained unchanged. The genes were synthesised at the facilities of an independent company delivered in dried form in company owned house vectors.
More detailed information about gene synthesis is available.
TABLE 1 Preferred codon usage of glycolysis genes from S. cerevisiae . Amino acid preferred codon Ala GCT Arg AGA Asn AAC Asp GAC, (GAT) Cys TGT Gln CAA Glu GAA Gly GGT His CAC Ile ATT, (ATC) Leu TTG Lys AAG Met ATG Phe TTC Pro CCA Ser TCT, (TCC) Thr ACC, (ACT) Trp TGG Tyr TAC Val GTT, (GTC) Stop TAA
B) Introduction of Codon-Optimised Genes into the BWY1 Strain
In order to transform the three codon-optimised genes into the BWY1 strain and test them, the genes had to be subcloned in yeast vectors. For this purpose, the codon-optimised araA ORF, the araB mut ORF and the araD ORF were amplified with primers, so that homologous overhangs to the shortened HXT7 promoter and the CYC1 terminator were created. The 2μ expression plasmids p423HXT7-6HIS, p424HXT7-6HIS, p425HXT7-6HIS were linearised with restriction endonucleases in the range between the HXT7 promoter and the CYC1 terminator. The PCR product from araA was transformed in yeast with the linearised p423HXT7-6HIS and cloned to the plasmid p423H7-synthIso by in vivo recombination. The same procedure was followed with the PCR product araB mut and the linearised vector p424HXT7-6HIS. This produced the plasmid p424H7synthKin. Plasmid p425H7-synthIso was produced by in vivo recombination of PCR product araD and the linearised vector p425HXT7-6HIS in yeast. The plasmids were isolated from the yeast and amplified in E. coli . After the plasmids were isolated from E. coli , the plasmids were examined by restriction analysis. One of each of the plasmids with the codon-optimised genes was transformed into the yeast strain BWY1 together with the three original, re-isolated plasmids, to test for functionality and for further analysis, so that all of the recombinant strains produced contained a complete arabinose metabolic pathway. In addition, the combination p424H7synthKin and p42457synthEpi was tested with the original, re-isolated plasmids as well as a batch in which the yeast transformant possessed all three new plasmids. The transformation with the four plasmids in each case took place at the same time. The transformants were plated on SM medium with 2% glucose. After two days, the colonies obtained were streaked out onto SM medium with 2% arabinose. A yeast strain that contained the four original, re-isolated plasmids was used as a positive control.
C) Growth Behaviour
The growth of the strain BWY1 with the various plasmid combinations of codon-optimised genes and original genes was examined in growth tests on arabinose-containing medium under aerobic conditions.
The strains with the various plasmid combinations were cultured in SM medium with 2% L-arabinose and inoculated with an OD 600nm =0.2 in 5 ml SM medium with 2% L-arabinose. Incubation took place in test tubes under aerobic conditions at 30° C. Samples were taken regularly to determine optical density.
The results of the aerobic growth curve are shown in FIG. 5 . It can be seen clearly that recombinant yeast strains that possess only one of the optimised genes show little or no growth advantages compared to the strain with the four original plasmids in a medium containing arabinose. However, yeast transformants with the two optimised genes of kinase and epimerase and yeast transformants with three optimised genes showed a clear growth advantage in a medium containing arabinose. The strains manifested a significantly shorter lag phase and grew to their maximum optical density considerably more quickly.
This shows that the combination of the three codon-optimised genes enables recombinant S. cerevisiae cells to convert L-arabinose significantly more efficiently.
D) Ethanol Production
FIGS. 6 (A) and (B) shows the results of HPLC analyses of two fermentations. One recombinant yeast strain contains plasmids p423H7synthIso, p424H7synthKin, p425H7synthEpi and pHL125 re , the other contains plasmids p423H7araABs re , p424H7araB re , p425H7araD re and pHL125 re . The fermentations were conducted in SFM medium with 3% L-arabinose. FIG. 6 (A) shows the arabinose consumption and the dry weight of both strains. FIG. 6 (B) illustrates the ethanol production of the two strains.
The strains were cultivated in the fermenter aerobically until they reached a dry weight of approx. 2.8 g/l. When sufficient cell mass was present, the fermentations were switched to anaerobic conditions. The figure shows the plots of arabinose metabolism and ethanol production. The byproducts produced, arabitol, acetate and glycerin, have not been listed because they were produced in comparable quantities by both strains.
As the plots show, ethanol production begins immediately after the switch to anaerobic conditions for both strains (the switch to anaerobic conditions is shown in FIGS. 6 (A) and (B) by an arrow). The ethanol that was already present in the medium at the start of the fermentation was not produced by the yeasts, it originated from the Tween80/Ergosterol solution. Under the aerobic conditions that prevailed in the beginning, ethanol was decomposed by yeast by respiration.
After about 80 hours, the strain that has the arabinose metabolic pathway genes in codon-optimised form demonstrates significantly improved arabinose metabolism and increased ethanol production. The arabinose present in the medium has been completely consumed after just 150 hours. In contrast, even after 180 hours there is still arabinose in the medium with the strain with the original, reisolated plasmids.
The fermentation results show that the codon-optimised genes enable the yeast transformants to metabolise arabinose more efficiently. The result of this is that the sugar is metabolised faster and a significantly higher ethanol yield is obtained.
Example 3
Construction of an Expression Cassette with Three Genes for the Arabinose Metabolic Pathway
The vector with the expression cassette with three genes for the arabinose metabolic pathway was constructed both to circument the problems that can arise when several plasmids are present in the same cell at the same time (“Plasmid stress”, Review of E. coli by Bailey (1993)), and to enable stable genomic integration of the arabinose metabolic pathway genes. The issues associated with constructing an expression cassette of the arabinose metabolic pathway genes and integrating it individually in a manner that is genomically stable have already been shown by Becker (2003) and Wiedemann (2005). The expression cassette with the three genes that has now been constructed represents an excellent starting point for direct genomic integration and enables subcloning into the integrative plasmids of the series pRS303X, pRS305X und pRS306X (Taxis und Knop, 2006).
A) Construction of the Expression Cassette
The starting point for constructing the expression cassette was the plasmid p425H7-synthEpi, in which the codon-optimised form of epimerase was expressed from E. coli behind the shortened HXT7 promoter and in front of the CYC1 terminator. In order to prevent possible homologous recombination between identical promoter or terminator regions, the codon-optimised araB mut -ORF must be expressed from E. coli between the PFK1 promoter and the FBA1 terminator, the codon-optimised araA-ORF from B. licheniformis between the FBA1 promoter and the PGK1 terminator. The plasmid p425H7-synthEpi was opened before the HXT7 promoter with restriction endonuclease SacI, streaked on an agarose gel, and eluted from the gel. The araB mut ORF was amplified by PCR. The PFK1 promoter and FBA1 terminator were amplified from genomic DNA of S. cerevisiae , the primers having been selected so that a 500 bp long sequence of the promoter and a 300 bp long sequence of the terminator were synthesised and homologous overhangs to the plasmid p425H7-synthEpi and to the araB mut ORF were produced at the same time. The primer that amplified the PFK1 promoter with the homologous regions to p425H7-synthEpi also contained a sequence for a PacI restriction site. The three PCR products were transformed in yeast together with the linearised vector and cloned into the plasmid via in vivo recombination. Restriction analysis was used to verify that the p425H7synthEpisynthKin plasmid produced had been successfully reconstructed. The functionality of the vector was tested. To do this, yeast transformants that contained the plasmids p425H7synthEpisynthKin and p423H7araABs re were prepared. The transformants were tested for arabinose growth. The strain was capable of growing on a medium containing arabinose. A yeast strain containing the vectors p424H7synthEpi and p423HXT7-6HIS was used as the negative control. This strain was not able to grow on the medium.
In the next step, the codon-optimised form of the isomerase from B. licheniformis was integrated into the vector. For this, plasmid p425H7synthEpisynthKin was linearised with NgoMVI after the CYC1 terminator, streaked onto an agarose gel and eluted from the gel. A 500 bp long sequence of the FBA1 promoter was amplified from genomic DNA of S. cerevisiae , and the primers were selected so that homologous overhangs to plasmid p425H7synthEpisynthKin in the CYC1 terminator and to the ORF of the codon-optimised araA were produced. A 300 bp long sequence of the PGK1 terminator was also amplified from genomic DNA of S. cerevisiae , in which a primer had overhangs to the ORF of the codon-optimised araA and the other primer included homologous overhangs to plasmid p425H7synthEpisynthKin and an AscI restriction site.
Restriction analysis was again used to verify the successful construction of the plasmid p425H7synthAra, and its functionality was tested. The test for functionality was performed for arabinose growth. Yeast transformants that contained the plasmid p425H7synthAra demonstrated growth on a medium containing arabinose. Growth curves in 5 ml SC medium with 2% arabinose were recorded. FIG. 7 shows that the transformants with vector p425H7synthAra demonstrate growth comparable to a strain with the four original, re-isolated plasmids.
B) Role of Promoters and Terminators
In order to avoid possible homologous recombination between the promoter and terminator regions, the three genes were cloned behind different promoters and terminators. In this context, the selection of the promoters was particularly important. It had been found in previous research (Becker and Boles, 2003) that the gene dose of the three genes relative to each other was critically important. In addition, all genes were to be strongly expressed. For these reasons, the decision was made to use the shortened HXT7 promoter, which is expressed strongly and constitutively, and the promoters PFK1 and FBA1, which are both known to promote strong expression of genes.
C) Examples of Vectors for the Expression Cassette
The starter plasmid for the construction of p425H7synthAra was the plasmid p425H7synthEpi, which is based on the plasmid p425HXT7-6HIS. The vector is a 2μ expression plasmid that possesses a leucine marker.
The three arabinose metabolic pathway genes were cloned into a vector one after the other under the control of various promoters and terminators. The expression cassette is flanked by the recognition sequences of the enzymes PacI and AscI.
Other possible expression vectors are come from the series pRS303X, p3RS305X and p3RS306X. These are integrative vectors that have a dominant antibiotic marker. More information about these vectors is provided in Taxis and Knop (2006).
REFERENCES
Becker, J. (2003)
Konstruktion und Charakterisierung eines L-Arabinose fermentierenden Saccharomyces cerevisiae Hefestammes.
Thesis, Heinrich-Heine-Universität Düsseldorf
Becker, J. und Boles, E. (2003)
A modified Saccharomyces cerevisiae strain that consumes L-arabinose and produces ethanol.
Appl. Environ. Microbiol. 69:4144-4150
Bailey, J. E. (1993)
Host-vector interactions in Escherichia coli.
Adv. Biochem Eng. 48.29-52
Bennetzen, J. L. und Hall, B. D. (1982)
Codon selection in yeast.
J Biol Chem. 257(6):3026-2031.
Birnboim, H. C. und J. Doly (1979)
A rapid alkaline extraction procedure for screening recombinant plasmid DNA.
Nucl. Acids Res. 7: 1513-1523
Dower, W. J., Miller, J. F. und Ragsdale, C. W. (1988)
High efficiency transformation of E. coli by high voltage electroporation.
Nucl. Acids Res. 16: 6127-6145
Gietz, R. D. und Woods, R. A. (1994)
High efficiency transformation in yeast.
In: Molecular Genetics of Yeast: Practical Approaches, J. A. Johnston (Ed.).
Oxford University Press pp. 121-134
Hamacher, T., Becker, J., Gárdonyi, M., Hahn-Hägerdal, B. und Boles., E. (2002)
Characterization of the xylose-transporting properties of yeast hexose transportes and their influence on xylose utilization.
Microbiology 148:2783-2788.
Hoekema A, Kastelein R A, Vasser M, de Boer H A. (1987)
Codon replacement in the PGK1 gene of Saccharomyces cerevisiae : experimental approach to study the role of biased codon usage in gene expression.
Mol Cell Biol. 7(8):2914-2924.
Karhumaa, K., Wiedemann, B., Hahn-Hägerdal, B., Boles, E. and Gorwa-Grauslund, M F. (2006)
Co-utilisation of L-arabinose and D-xylose by laboratory and industrial Saccharomyces cerevisiae strains.
Microbial Cell Factories 5(1):18
Maniatis T, Fritsch, E. F und Sambrook, J. (1982)
Molecular cloning. A laboratory manual.
Cold Spring Harbor Laboratory, New York.
Sedlak, M. und Ho, N. W. Y. (2001)
Expression of E. coli araBAD operon encoding enzymes for metabolizing L-arabinose in Saccharomyces cerevisiae.
Enz. Microbiol. 28:16-24
Taxis, C. und Knop, M. (2006)
System of centromeric, episomal, and integrative vectors based on drug resistance markers for Saccharomyces cerevisiae.
Bio Techniques 40, No. 1
Verduyn, C., Postma, E., Scheffers, W. A. und Van Dijken, J. P. (1992)
Effect of benzoic acid on metabolic fluxes in yeasts: a continuous-culture study on the regulation of respiration and alcoholic fermentation.
Yeast 8 (7), 501-17
Wiedemann, B. (2005)
Molekulargenetische und physiologische Charakterisierung eines rekombinanten Pentose-vergärenden Hefestammes. Diplomarbeit. Johann Wolfgang Goethe-Universität, Frankfurt am Main.
Wirth; R. (1993)
Elektroporation: Eine alternative Methode zur Transformation von Bakterien mit Plasmid-DNA. Forum Mikrobiologie 11 (507-515).
Wu G, Bashir-Bello N, Freeland S J. (2006)
The Synthetic Gene Designer: a flexible web platform to explore sequence manipulation for heterologous expression.
Protein Expr Purif. 47(2):441-445.
Zimmermann, F. K. (1975)
Procedures used in the induction of mitotic recombination and mutation in the yeast Saccharomyces cerevisiae.
Mutation Res. 31:71-81 | 4y
|
BACKGROUND OF THE INVENTION
[0001] The present invention is related to compression caps, and more particularly to compression caps used in plumbing connections.
[0002] Compression caps are well known for connecting a section of pipe or tubing to a fitting. The current method is a metal band that is positioned and crimped onto the end of a pipe or tube to secure the tube to a fitting. The cap is crimped using a specially designed tool. These caps may be used in a wide variety of plumbing applications including recreational vehicles, modular homes, marine crafts and beverage dispensing machines.
[0003] The proper positioning of the compression caps on the pipe ends is important. Accordingly, the present caps are designed to enhance the likelihood that the cap will be properly positioned. One such cap is sold by Stadler-Viega of Bedford, Mass. under the Pureflow trademark. As illustrated in FIGS. 1 and 2 , this cap 100 includes a shoulder 110 at one end 120 to provide a positive stop for the pipe 130 within the cap. The cap also defines a “witness window” 115 to permit visual observation and confirmation that the pipe is properly positioned within the cap end against the flange 110 . The flange 110 assists in properly positioning the cap on the tube end.
[0004] Unfortunately, there are difficulties in the installation of conventional compression caps. After a cap is placed on the end of the pipe, it must be physically held in place until the fitting is inserted into the pipe and the cap is compressed, which requires two hands. If this is not done, the cap may fall off the tube. This problem is exacerbated when the installation of a cap is attempted in a tight space, because the user may only be able to reach the pipe and the cap with one hand.
SUMMARY OF THE INVENTION
[0005] The aforementioned problems are overcome by the present invention wherein a compression cap is provided with an inward deformation that provides a friction fit or an interference fit between the cap and the outer surface of the pipe.
[0006] In the disclosed embodiment, the inward deformation is a plurality of longitudinal ribs evenly spaced about the circumference of the cap. As the cap is placed on the pipe, the ribs engage the outer surface of the pipe creating friction and thereby preventing the cap from falling off the pipe prematurely.
[0007] The present invention provides a number of advantages over conventional compression caps. First, users of the present invention are no longer required to hold the cap in position on the pipe, or to keep the pipe in an upright position prior to placing the pipe onto the fitting. Second, the inward deformation aids in preventing the cap from slipping, moving, or being pushed out of position before the crimp is performed. Third, the number of caps lost inside walls or compartments where pipes are located will be reduced, because caps will be less likely to fall off the pipe after they are placed there. Fourth, installation of caps in tight spaces is much easier with the present invention, because the same hand can be used to place the cap on the pipe, then insert the fitting, and then crimp the cap. Fifth, the inward deformation contributes to a stronger connection between the pipe and the fitting or other object inside the pipe.
[0008] These and other objects, advantages, and features of the invention will be readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view of a prior art cap in combination with a pipe and a fitting.
[0010] FIG. 2 is a perspective view of the prior art cap.
[0011] FIG. 3 is a perspective view of the cap of the present invention in combination with a pipe and a fitting.
[0012] FIG. 4 is a perspective view of the cap.
[0013] FIG. 5 is a sectional view taken along line 3 - 3 in FIG. 4 .
[0014] FIG. 6 is a sectional view taken along line 6 - 6 in FIG. 3 .
[0015] FIG. 7 is a perspective exploded view of FIG. 3 .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] A compression cap in accordance with the preferred embodiment is shown in FIG. 3 and generally designated 10 . The cap 10 is preferably a metal band that is capable of slidably fitting over a pipe or tube 12 . The cap 10 preferably includes a plurality of spaced apart ribs 14 , a positive stop flange 16 , and a witness window 18 . In operation, the cap 10 is placed over the end of a pipe 12 , and a fitting 22 is inserted into the cap 10 at the same end of the pipe 12 . The cap 10 is then crimped with a crimping tool (not shown) to compress the cap 10 about the pipe 12 and the fitting 22 , securing the fitting 22 inside the pipe 12 .
[0017] I. Structure
[0018] Shown in FIGS. 6 and 7 , the pipe 12 is well known and generally comprised of, but not limited to, plastic, such as PVC or PEX (cross linked polyethylene). The pipe includes an outer surface 19 , and an end 23 that will receive the cap 10 . Depending on the desired application, the pipe may be a rigid or flexible, and may have a variety of standard sizes. The fitting 22 is also well known and is available in standard sizes. They are generally comprised of a metal, such as brass, or plastic, and include at least one insert 21 having a diameter slightly smaller than the inner diameter of the pipe 12 such that it can be inserted into the end 23 of the pipe 12 . The T-shaped fitting 22 shown is intended to be exemplary of just one type of such pipe fittings.
[0019] As shown in FIG. 4 , the cap 10 is generally a metal band having a circumference of any desired size so that it fits over a desired pipe or tube. The metal band 10 includes a first end 24 , a second end 26 , and a side wall 28 extending between the first end 24 and second end 26 . The width of the side wall between the first and second ends 24 and 26 may vary with the desired application. The side wall 28 also includes an inner surface 32 , an outer surface 34 . In the preferred embodiment, a lip 38 extends radially outward from the second end 26 . The lip 38 includes a radius 40 that forms a smooth transition with the side wall 28 .
[0020] The side wall 28 also includes a plurality of inward deformations. As shown in FIGS. 4 and 5 , in the preferred embodiment, the inward deformations are a plurality of ribs 14 . The ribs 14 preferably extend across the substantial width of the side wall 28 , forming an indentation 42 in the outer surface 34 and a corresponding protrusion 44 on the inner surface 32 . The depth of the protrusion 44 may vary depending on the desired interference between the ribs 14 and the pipe 12 . In a preferred embodiment, three ribs 14 are spaced evenly about the sidewall 28 . However, any number of ribs 14 may be used, and the ribs 14 may have a different orientation, such as running circumferentially about the cap 10 . Alternatively, the inward deformations may be a number of dimples, or a differently shaped inward deformation that creates a friction fit between the cap 10 and the pipe 12 .
[0021] In the preferred embodiment, a positive stop flange 16 extends radially inward from the first end 24 of the cap 10 . The flange 16 preferably extends around the entire circumference of the cap 10 , having an inner surface 50 , and an outer surface 52 . The depth of the flange 16 is approximately the same, but not greater than, the thickness of the pipe 12 , so that the fitting 22 may still be inserted through the cap 10 and into the end of the pipe 12 . In another embodiment, the side wall 28 includes a hole 48 , or witness window. The hole 48 is proximate to the first end 24 of the cap 10 , allowing a user to view the pipe 12 through the window 48 when the cap 10 is placed on the pipe 12 .
[0022] II. Operation
[0023] In operation, the second end 26 of the cap 10 is positioned proximate to the end 23 of the pipe 12 . A user will then slide the cap 10 onto the end 23 of the pipe 12 . As the cap 10 slides onto the pipe 12 , the lip 38 on the second end 26 of the cap 10 serves to guide the pipe 12 into the cap 10 , and then the ribs 14 engage the outer surface 19 of the pipe 12 , creating a friction fit between the ribs 14 and the pipe 12 for crimping. The pipe 12 is slid onto the cap 10 until the end 23 of the pipe 12 contacts the inner surface 50 of the flange 16 , and the pipe 12 is visible through the window 48 . The flange 16 prevents the cap 10 from sliding farther onto the pipe 12 , and the friction fit created by the ribs 14 prevents the cap from sliding off the pipe 12 without a force being applied by the user. Once the cap 10 is in place, the insert 21 of the fitting 22 is inserted into the end 23 of the pipe 12 , and the cap 10 is crimped with a crimping tool to compress the cap 10 onto the pipe 12 , and compress the pipe 12 onto the fitting 22 .
[0024] The above description is that of a preferred embodiment of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular. | 4y
|
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is generally related to processes for sulfur recovery and more specifically to processes for removing sulfur compounds, including hydrogen sulfide and sulfur dioxide, from process streams.
2. Description of the Related Art
Processing of hydrocarbon-containing fuels such as gasoline and diesel fuel results in gases containing sulfur compounds, including hydrogen sulfide (H 2 S), and hydrocarbon compounds, including ammonia (NH 3 ). Governmental regulations limit plant emissions of sulfur-bearing gases. Refineries commonly include sulfur reduction units to decrease emissions of sulfur compounds.
The use of a Claus reaction to recover sulfur from process off-gases is widely known in the field. Sulfur dioxide (SO 2 ) and hydrogen sulfide react to produce elemental sulfur (S 2 ) and steam (H 2 O). The reaction formula is:
2H 2 S+SO 2 →1.5S 2 +2H 2 O
The reaction can occur with or without a catalyst. As long as two moles of hydrogen sulfide are available for each mole of sulfur dioxide in appropriate concentrations with appropriate heat and pressure, elemental sulfur and water will result.
A typical prior art arrangement of a Claus process with a SCOT tail gas process is outlined in FIG. 5 . The prior art generally teaches high temperature reaction of air, through air line 16 , off-gas streams containing hydrogen sulfide, through hydrogen sulfide line 18 , and off-gas streams containing ammonia, through ammonia line 12 , in a thermal reactor 14 to oxidize a portion of the hydrogen sulfide in the process streams to create sulfur dioxide and to react the sulfur dioxide with hydrogen sulfide into elemental sulfur and water, thus eliminating a substantial portion of the hydrogen sulfide and sulfur dioxide in the streams. The quantity of air to the thermal reactor is controlled to provide a stoichiometric balance of hydrogen sulfide and sulfur dioxide in the process stream. A balanced stoichiometric ratio is difficult to maintain due to variations in composition of process streams.
Commonly, the process stream containing significant hydrogen sulfide is divided prior to introduction to the reactor chamber, with approximately 30-70% of the feed directed to the front end 22 of the thermal reactor chamber 14 through line 18 and the remaining 30-70% directed to the back end 20 of the reactor chamber 14 through line 18 a . The mixture of air and off-stream gases is thermally reacted near the front end 22 of the reactor chamber 14 and moves to the back end 20 of the reactor chamber 14 where the second hydrogen sulfide stream is received.
It is desirable to maintain a temperature at or near 1,316° C. (2,400° F.) in the thermal reactor 14 to crack process gas hydrocarbon compounds such as ammonia. Providing a determined quantity of hydrogen sulfide at the front end 22 of the reactor chamber 14 assists in maintaining desired temperature in the thermal reactor 14 . An excess of hydrogen sulfide tends to lower the temperature in the reactor chamber 14 due to increased mass flow. In prior art thermal reactors, the temperature at the back end 20 of the reactor 14 may be less than the desired temperature because of added off-gases containing hydrogen sulfide.
After the thermal reactor 14 the resulting gas stream is processed through a series of Claus reactors 46 , 60 and 72 , condensers 34 , 50 , 64 and 76 and reheaters 42 , 54 and 68 . The Claus reactors 46 , 60 and 72 typically have aluminum oxide or bauxite catalyst beds. The Claus reaction produces elemental sulfur, which is recovered as liquid sulfur and water vapor. Traditional Claus systems remove greater than 95% of the sulfur from the process stream. Tail gas processes are used to remove remaining quantities of sulfur compounds to obtain an overall recovery of up to 99.9%.
Various processes are taught for treating tail gas to remove the remaining hydrogen sulfide and sulfur dioxide. The Shell Claus Off-gas Treating process, often referred to as the SCOT process, reacts hydrogen with remaining sulfur dioxide to generate hydrogen sulfide which is in turn absorbed in an amine compound. A typical SCOT process includes a pre-heater 82 for heating the tail gas, a hydrogenation reactor 84 , a quench tower 86 to remove water from the tail gas, an amine tower 88 for reaction of the amine solution with the tail gas, a regenerator 96 to strip the hydrogen sulfide for transmission back to the Claus reactor, and an incinerator 92 for burning off treated tail gas. The SCOT process is effective in further reducing sulfur dioxide emissions. However, the SCOT involves substantial capital and operating expense. The hydrogenation reactor 84 , required to react hydrogen with hydrogen sulfide and sulfur dioxide, is expensive because of high initial capital cost and operating costs.
U.S. Pat. No. 5,021,232 issued to Hise et al. on Jun. 4, 1991 discloses a process for the cleanup of sulfur-containing constituents in a gaseous stream such as a tail gas from a sulfur recovery unit. A Claus reaction is used to convert sulfur-containing compounds to elemental sulfur in the presence of a stoichiometric excess of hydrogen sulfide. The elemental sulfur is separated from the tail gas and the sulfurous compounds remaining in the tail gas are separated by crystallization for recycle through the Claus process. Carbon dioxide is the crystallization material. Sulfur-containing compounds are at least partially excluded from a solid (frozen) phase of the carbon dioxide for recycling through the Claus process.
U.S. Pat. No. 5,741,469 issued to Bhore et al. on Apr. 21, 1998 discloses a process that may be used to treat Claus plant tail-gas utilizing solid oxides to remove sulfur oxides from gas streams.
U.S. Pat. App. No. US 2003/0082096, invented by Lynn and published on May 1, 2003 discloses treating sulfur dioxide-rich gas by combusting it with a substoichiometric amount of oxygen to produce a combustion gas with water vapor and sulfur vapor. The combustion gas is cooled to form water containing suspended solid sulfur and polythionic acids.
U.S. Pat. No. 6,610,264 issued to Buchanan et al. on Aug. 26, 2003 discloses a process and system for removing sulfur from tail-gas emitted from a Claus sulfur recovery process. The tail-gas is first oxidized so as to convert sulfur therein to sulfur oxides. Oxidized tail-gas is directed into an absorber where a solid absorbent absorbs substantially all the sulfur oxides thereon. After allowing sufficient time for a desired amount of sulfur oxides to be absorbed, absorption is ceased. Next, the solid absorbent containing the absorbed sulfur oxides is contacted with a reducing gas so as to release an off-gas containing hydrogen sulfide and sulfur dioxide. Upon releasing sulfur from the solid absorbent, the solid absorbent is regenerated and redirected into the absorber. Sulfur in the off-gas emitted by regeneratio is concentrated to an extent sufficient for use within a Claus sulfur recovery process for conversion to elemental sulfur.
SUMMARY OF THE INVENTION
Objects of the present invention include providing a process for treating process off-gases that:
effectively removes sulfur compounds from the gases; handles variations and operational fluctuations in the process stream composition without upset; eliminates the need for a hydrogenation reactor and the hydrogen supply required for such a reactor; and reduces or eliminates the need for amine towers.
Other objects of the present invention will become evident throughout the reading of this document.
The present invention comprises a method of treating an off-gas stream from a refining process to remove sulfur compounds, including hydrogen sulfide. In the present invention, a portion of the off-gas stream containing hydrogen sulfide is injected at the front end of the thermal reactor and in at least one other location downstream of the thermal reactor. A ratio of hydrogen sulfide to sulfur dioxide at the outlet of the thermal reactor is less than the stoichiometric requirement. The ratio is adjusted downstream of the thermal reactor so that a ratio of hydrogen sulfide to sulfur dioxide is maintained substantially in excess of the stoichiometric requirement for a Claus reaction through the Claus reactors. Substantially complete reaction of all sulfur dioxide, whether initially present in process gas or generated in the thermal reactor, occurs concurrently with transmission of the process gas through the Claus reactors, such that the tail gas contains virtually no sulfur dioxide.
The tail gas, containing hydrogen sulfide but virtually no sulfur dioxide, is treated by a process including removal of water, heating the tail gas, introducing sulfur dioxide into the tail gas in a stoichiometricly balanced quantity, processing the tail gas in a Claus reactor, recovering elemental sulfur and sub-cooling the remaining tail gas to the sulfur dewpoint.
In an alternative embodiment, the tail gas may be treated by a sub-dewpoint reactor intermediate the tail gas Claus reactor and the sub-cooler.
In a second alternative embodiment, the tail gas is treated as in a SCOT tail gas treatment process. However, the elimination of sulfur dioxide from the tail gas eliminates the need for a prior art hydrogenation unit.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram of the preferred embodiment of the process of the present invention.
FIG. 2 is a diagram of an alternative embodiment of the process of the present invention.
FIG. 3 is a diagram of an alternative embodiment of the process of the present invention incorporating a sub-dewpoint reactor.
FIG. 4 is a diagram an alternative embodiment of the present invention depicting a modified SCOT tail gas treatment process.
FIG. 5 is a diagram of a prior art process treating system with a SCOT tail gas treatment process.
DESCRIPTION OF THE INVENTION
Referring to FIG. 1 , the preferred embodiment of the process treatment process of the present invention is depicted. An off-gas line 18 containing hydrogen sulfide as a primary sulfur-containing compound, referred to herein as hydrogen sulfide off-gas line 18 , and an off-gas line 12 containing ammonia, referred to herein as the ammonia off-gas line 12 , each include by-products from a primary hydrocarbon process. Off-gas lines 12 and 18 each typically also contain various quantities of water, oxygen, nitrogen, carbon dioxide, sulfur dioxide, carbon monoxide and small amounts of other hydrocarbon compounds. Compositions vary depending on the process, variation of the input stream and variations in the application of the process.
Hydrogen sulfide off-gas line 18 and ammonia off-gas line 12 are each connected to thermal reactor 14 for transmittal of respective process gases to thermal reactor 14 . Air is supplied to thermal reactor 14 through air line 16 for reaction with process gases from hydrogen sulfide off-gas line 18 and ammonia off-gas line 12 .
Relative quantities of air, hydrogen sulfide off-gas line 18 gases and ammonia off-gas line 12 gases introduced into reactor chamber 14 are determined to create an excess of sulfur dioxide over the stoichiometric amount of sulfur dioxide and hydrogen sulfide required pursuant to the Claus equation. Accordingly, an excess of sulfur dioxide will be result at the outlet of reactor 14 .
The preferred temperature within thermal reactor 14 is at least 1,316° C. (2,400° F.) in order to oxidize or reduce various other constituents of hydrogen sulfide off-gas line 18 gases and ammonia off-gas line 12 gases.
In the preferred embodiment of the present invention, all hydrogen sulfide containing gas introduced into thermal reactor 14 through hydrogen sulfide off-gas line 18 is introduced at the front end 22 of thermal reactor 14 . Hydrogen sulfide is not fed into the thermal reactor 14 after the initial introduction through first hydrogen sulfide line 18 . This allows the temperature of reactor chamber 14 to remain near 1,316° C. (2,400° F.) in a greater area of the reactor chamber 14 and extends exposure time of the process gas to such temperature. Accordingly, increased oxidation or reduction of contaminants results at consistent flow rates of process gases.
After exiting reactor chamber 14 , the thermally-reacted process gas is fed by gas line 26 through a waste heat boiler 30 to cool the process gas and recover thermal energy from the process gas. Process gas is then fed to first condenser 34 where the process gas is cooled to allow condensation and collection of elemental sulfur.
A second quantity of hydrogen sulfide line 18 gas is transmitted by hydrogen sulfide gas line 18 and injected into thermally-reacted gas line 26 downstream of first condenser 34 at mixer 38 . The amount of hydrogen sulfide added is sufficient to create an excess of the amount hydrogen sulfide required for a stoichiometric balance with sulfur dioxide in the process gas line 26 .
As the Claus reaction is exothermic, reaction of hydrogen sulfide and sulfur dioxide is readily accomplished at a wide range of temperatures and pressures. Addition of excess hydrogen sulfide at mixer 38 accordingly enhances effective Claus reaction downstream of mixer 38 and enhances sulfur dioxide removal from the gas stream.
Through control devices known in the art, the quantity of hydrogen sulfide containing process gas delivered to mixer 38 through line 24 may be adjusted. Control of flow may be accomplished by valve 36 or by a control mechanism incorporated into mixer 38 . The quantity of hydrogen sulfide line 18 gas injected into thermally-reacted gas line 26 at mixer 38 may be controlled by controller 52 .
A sulfur dioxide analyzer 78 determines the quantity of sulfur dioxide in tail gas line 80 upstream of quench tower 84 . Such determination is input to controller 52 . If input of additional hydrogen sulfide line 18 gas is required at mixer 38 , controller 52 adjusts the amount of hydrogen sulfide line 18 gas input to mixer 38 . Analyzer 78 and controller 52 are commercially practiced control devices.
Process gas is subsequently transmitted to reheater 42 where the process gas is heated. Process gas is then transmitted by line 26 to a first Claus reactor 46 where a catalyst, such as aluminum oxide (Al 2 O 3 ) or bauxite, is utilized to catalyze reaction of hydrogen sulfide and sulfur dioxide in the process gas. Condensers such as second condenser 50 , reheaters such as first reheater 42 and reactors such as first Claus reactor 46 are known in the art.
Claus reactor 46 is operated to achieve an outlet temperature greater than 315° C. (600° F.). The hydrogen sulfide off-gas of line 18 contains quantities of carbonyl sulfide (COS) and carbon disulfide (CS 2 ). Operating Claus reactor 46 at such temperature allows such compounds to be cracked during the reaction process.
Process gas is then transmitted by line 26 through second condenser 50 .
A third quantity of hydrogen sulfide line 18 gas is transmitted by hydrogen sulfide gas line 18 and injected into process gas line 26 downstream of second condenser 50 at mixer 48 . Control of flow may be accomplished by valve 46 or by a control mechanism incorporated into mixer 48 . Process gas is then transmitted by line 26 through second reheater 54 and second Claus reactor 60 .
Process gas is then transmitted by line 26 through third condenser 64 , third reheater 68 , third reactor 72 and fourth condenser 76 . Preferably a ratio of 50 lbmol of hydrogen sulfide to 1 lbmol of carbon dioxide is provided at the inlet to third reactor 72 (25:1 ratio on a stoichiometric basis.
Condensers such as condensers 50 and 64 , reheaters such as reheaters 42 and 68 , and reactors such as reactors 60 and 72 are known in the art.
The excess hydrogen sulfide feed at mixer 38 and mixer 48 introduces sufficient quantities of hydrogen sulfide through hydrogen sulfide line 18 that contact of substantially all sulfur dioxide remaining in the process gases may be made within process line 26 , thereby achieving substantial elimination of sulfur dioxide at the outlet of condenser 76 . The quantity of sulfur dioxide in the tail gas line 80 at the outlet of condenser 76 is reduced below a level that would cause corrosion or sulfur formation in the quench tower. A desired concentration is substantially below one hundred (100) parts per million.
OPERATION EXAMPLE
In an illustrative material balance calculation, a quantity of hydrogen sulfide line 18 gas, a quantity of ammonia line 12 gas and a quantity of air line 12 gas are reacted in reactor 14 creating a process line 26 gas having a concentration of sulfur dioxide of 41.9 pound moles (“lbmols”) of sulfur dioxide and of 27.5 lbmols of hydrogen sulfide at the outlet of condenser 34 . This is a 0.66:1 ratio of hydrogen sulfide to sulfur dioxide on a lbmol basis and a 0.33:1 ratio on a stoichiometric basis (as 2 lbmols of hydrogen sulfide are required to each lbmol of sulfur dioxide).
A second quantity of hydrogen sulfide line 18 gas is injected at mixer 38 to provide a concentration of hydrogen sulfide of 21.7 lbmols and a concentration of sulfur dioxide of 9.4 lbmols at the outlet of condenser 50 , a 2.31:1 ratio of hydrogen sulfide to sulfur dioxide on a lbmol basis and a 1.16:1 ratio on a stoichiometric basis.
A third quantity of hydrogen sulfide line 18 gas is subsequently injected at mixer 48 to provide a concentration of hydrogen sulfide of 14.4 lbmols and a concentration of sulfur dioxide of 0.34 lbmols at the outlet of condenser 64 , a 48:1 ratio on a lbmol basis and a 24:1 ratio on a stoichiometric basis. In a preferred embodiment, the ratio of hydrogen sulfide to sulfur dioxide downstream of reactor 60 us at least 20:1 on a lbmol basis. This is the ratio of hydrogen sulfide to sulfur dioxide at the inlet to reactor 72 . As further reaction occurs and sulfur is condensed at reactor 72 , a concentration of hydrogen sulfide of 13.7 lbmols and a concentration of sulfur dioxide of 0.003 lbmols results at the outlet of condenser 76 , a ratio of 4,566:1 on a lbmol basis and a ratio of 2,283:1 on a stoichiometric basis. In a preferred embodiment, the ratio of hydrogen sulfide to sulfur dioxide downstream of reactor 72 is at least 200:1 on a lbmol basis.
In such calculation, the total lbmols of all constituents of process gas at the outlet of condenser 76 is 872.6 lbmols (including 435.6 lbmols of nitrogen and 360.3 lbmols of water vapor), providing a calculated sulfur dioxide concentration of 3.4 parts per million on a lbmol basis.
In operation, sulfur dioxide levels are monitored sulfur dioxide analyzer 78 determines the quantity of sulfur dioxide in tail gas line 80 upstream of quench tower 84 . Controller 52 adjusts quantities of hydrogen sulfide off-gas line 18 input to process line 26 at mixer 38 and at mixer 48 to obtain the desired concentration of sulfur dioxide at the analyzer measurement location. Such control may be exercised using defined constraints or through user input.
Liquid sulfur condensation utilizing Claus reactors may be accomplished using fewer or greater than the three series of reactors and condensers identified in FIG. 1 .
Referring to FIG. 2 , an alternative embodiment of the gas treatment process is shown. An additional mixer 58 is installed downstream of condenser 64 to provide an additional input source of hydrogen sulfide line 18 gas at such location. Introduction of a relatively small quantity of additional hydrogen sulfide at such location greatly impacts the ratio of hydrogen sulfide to sulfur dioxide at such location to react remaining sulfur dioxide and reduce the quantity of sulfur dioxide at the outlet of condenser 76 . A fourth hydrogen sulfide line 18 gas input location is provided at mixer 58 downstream of third condenser 64 . Control of flow may be accomplished by valve 24 or by a control mechanism incorporated into mixer 58 . A hydrogen sulfide/sulfur dioxide analyzer 28 is provided downstream of first condenser 34 . Analyzer 28 is connected to controller 52 . provides additional data regarding the composition of process line 26 gas at condenser 34 . Mixer 58 provides additional operational flexibility in adjusting hydrogen sulfide input.
Additional analyzers (not shown) may be utilized as desired. Placement of analyzers may be adjusted to provide information at locations deemed relevant. Mixers may be placed at alternate locations.
In a second alternative embodiment of the process gas treatment process, mixer 48 may eliminated. Adjustments to the amount hydrogen sulfide line 18 gas input to process gas line 26 are made at mixer 38 .
In a third alternative embodiment of the process gas treatment process, a separate source of hydrogen sulfide may be utilized to introduce a hydrogen sulfide feed to mixer 38 in lieu of feeding a portion of the hydrogen sulfide off-gas line 18 process gas to mixer 38 . Such alternative embodiment would be useful in instances wherein the hydrogen sulfide off-gas line 18 process gas contains significant quantities of other contaminants.
In a fourth alternative embodiment of the process gas treatment process, mixer 38 is placed downstream of thermal reactor 14 and upstream of condenser 34 to increase dwell time of excess hydrogen sulfide in the process gas stream.
Tail Gas Treatment—Sulfur Dioxide Addition
The process gases remaining after removal of elemental sulfur, which are now referred to as the “tail gas,” are transmitted from condenser 76 by tail gas line 80 to a quench tower 84 to remove water vapor from the tail gas. Quench towers, such as quench tower 84 , are known in the art and are commonly used for removal of water vapor from the tail gas. Water is known to inhibit Claus reactions, so it is advantageous to remove water vapor from the tail gas prior to a Claus reaction to be subsequently initiated.
The tail gas is then heated at heater 104 to achieve a temperature in the range of 149 to 260° C. (300 to 500° F.). A quantity of sulfur dioxide is added to the tail gas from sulfur dioxide line 106 at valve 110 such that a stoichiometric ratio of sulfur dioxide and hydrogen sulfide is obtained to achieve a Claus reaction. The amount of sulfur dioxide to be added is determined by an analyzer 118 upstream of valve 110 . Analyzer 118 monitors the quantity of hydrogen sulfide in the tail gas line 80 and through valve control devices known in the art adjusts the quantity of sulfur dioxide added to tail gas line 80 .
Addition of sulfur dioxide to the tail gas creates an additional Claus reaction with the hydrogen sulfide remaining in the tail gas.
The tail gas is then transmitted to a Claus reactor 114 having a catalyst bed of aluminum oxide or bauxite and subsequently to a condenser 120 .
Remaining tail gas is then transmitted to a subcooler 128 where the tail gas is further cooled preferably to a temperature of 66° C. (150° F.). At subcooler 128 , the Claus reaction continues and sulfur continues to condense.
Liquid sulfur is continuously collected at a sulfur trap 70 at condenser 120 and a sulfur trap 70 at subcooler 128 .
Tail gas remaining at the output of subcooler 128 contains less than 150 parts per million of hydrogen sulfide and sulfur dioxide and may be burned to atmosphere at burner 132 .
Referring to FIG. 3 , an alternative embodiment of the tail gas treatment process provides a subdewpoint reactor system 124 for treatment of tail gas remaining after condenser 120 . The subdewpoint reactor system 124 includes at least one pair of subdewpoint reactors, reactor 124 a and 124 b . Tail gas is transmitted to subdewpoint catalyst bed 124 a . Catalyst bed 124 a is a catalyst bed utilizing aluminum oxide (Al 2 O 3 ) or bauxite as a catalyst for a Claus reaction. Catalyst bed 124 a operates effectively when the temperature of the tail gas is around 260° F. Catalyst bed 124 a and the condensing process are known in the art. As is known in the art, catalyst bed 124 a is porous and subject to saturation as sulfur condenses from tail gas onto catalyst bed 124 a . Upon saturation of the catalyst bed 124 a , flow of tail gas is redirected to subdewpoint catalyst bed 124 b . Catalyst bed 124 b is like catalyst bed 124 a and likewise is subject to condensation of sulfur and saturation.
Upon redirection of tail gas to catalyst bed 124 b , the sulfur may be cleaned from catalyst bed 124 a . In like manner, upon saturation of catalyst bed 124 b with sulfur, tail gas may be redirected to catalyst bed 124 a and catalyst bed 124 b may be cleaned. Such process of cleaning catalyst beds is known and practiced in the art.
In the alternative embodiment of FIG. 3 , tail gas remaining after subdewpoint reactor system 124 is transmitted to subcooler 128 where the tail gas is further cooled preferably to a temperature of 66° C. (150° F.). Tail gas remaining at the output of subcooler 128 may be burned to atmosphere at burner 132 .
Modified SCOT Process.
Referring to FIG. 4 , an alternative embodiment of the tail gas process comprises a modification to the Shell Claus Off-gas Treatment Process. In such alternative embodiment, the process gases remaining after condenser 76 , which are now referred to as the “tail gas,” are transmitted from condenser 76 by tail gas line 80 to a quench tower 84 to eliminate water vapor from the tail gas. Quench towers, such as quench tower 84 , are known in the art and are commonly used for removal of water vapor from the tail gas.
The tail gas from quench tower 84 is transmitted to an amine tower 88 . In amine tower 88 , hydrogen sulfide is absorbed by an amine solution contacting the tail gas. The remaining tail gas contains sufficiently reduced quantities of sulfur dioxide that the remaining tail gas may be burned to the atmosphere at burner 92 .
The amine and hydrogen sulfide solution from amine tower 88 is transmitted to an amine regenerator 96 . At amine regenerator 96 , hydrogen sulfide is stripped from the amine. Hydrogen sulfide from the amine regenerator is transmitted by hydrogen sulfide feed line 18 to thermal reactor 14 .
Amine towers, such as amine tower 88 , and amine regenerators, such as amine regenerator 92 , are commonly practiced in the art.
It is noted that the tail gas treatment of the present invention eliminates the expensive hydrogenation step of the prior art SCOT tail gas treatment process as the quantity of sulfur dioxide in the tail gas line 80 at the outlet of condenser 76 is reduced below a level that would cause corrosion or sulfur formation in the quench tower. This embodiment allows practice of the process of the present invention in plants having existing SCOT tail gas treatment facilities in place, but at reduced operation costs.
The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction may be made within the scope of the appended claims without departing from the spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents. | 4y
|
FIELD OF INVENTION
[0001] This invention relates to plug-in hybrid propulsion systems for cars, trucks, and buses where the energy storage element of the hybrid drive train may be charged with externally supplied electricity as well as energy from the engine or regenerative braking.
[0002] In particular, the invention relates to plug-in hybrids that can provide services to the electrical utility when the vehicle is connected to the utility grid.
RELATED ART
[0003] Existing products commonly found in the marketplace include conventional hybrid vehicles such as the Toyota Prius, Honda Insight, and Ford Escape Hybrid. More closely related to the present invention are prototype Daimler Chrysler Sprinter plug-in hybrid vans.
[0004] The main problem with existing conventional hybrids is that the full potential of conventional hybrid propulsion is not realized due to limited all-electric travel range. This problem is addressed by increasing the energy storage capacity of the vehicle to allow for greater all-electric range. The energy storage system may be charged from an external supply to offset and reduce fuel consumption. This type of propulsion system is known as a plug-in hybrid.
[0005] The main problems with existing plug-in hybrid vehicles are the cost of batteries and limited battery life. While conventional hybrid propulsion sized for a car uses energy storage with a capacity of about 1 kWh, plug-in hybrid cars require energy storage exceeding 5 kWh. The plug-in hybrid battery system must be deeply cycled in order to obtain useful all-electric range within a reasonable physical weight and volume. Deep cycling reduces battery life. The plug-in hybrid battery is much larger and proportionately more expensive than the battery in a conventional hybrid vehicle. Therefore, the cost penalty associated with a plug-in hybrid is more severe than for a conventional hybrid.
[0006] An additional problem with batteries used for hybrid vehicles is that maximizing available energy storage requires constraining such environmental conditions of the batteries as temperature. Conditioning of the environment of the battery is required to attain tolerable durability.
[0007] Some electric power grids in the U.S. are operated not by utilities but by separate regional entities called Independent System Operators. For example, the California Independent System Operator (CAISO) controls the grid for the entire State of California. An ISO purchases a variety of ancillary services that are used to regulate power flows, voltage stability and frequency on the grid. These include:
[0008] peak power
[0009] baseload power
[0010] spinning reserves
[0011] regulation services
[0012] backup power
[0013] renewable energy time shifting
[0014] Regulation service is necessary because the electric load on the grid is constantly changing as people turn on or off appliances, motors and machinery. This constantly changing load leads to small voltage imbalances at various locations on the grid. Changing load can also cause small changes in generator speed leading to frequency variations above and below 60 Hz. Since motors, clocks, computers and most other devices require constant electric frequency to operate accurately, utilities maintain a 60 Hz frequency within specified tolerances. Deviations from the 60 Hz frequency are called Area Control Error (ACE).
[0015] Regulation service is provided today by small, frequent adjustments to the output of each power plant. Computer models use frequency measurements throughout the grid to determine which power plants should generate more and which should generate less in order to minimize ACE at all points on the grid. Often one power plant will be providing Regulation Up service at the same time that another is providing Regulation Down service.
[0016] In California, regulation service is provided partly by the electric utilities (self-provided regulation) and partly by merchant power plants that are paid for their services by the ISO. A power plant cannot operate at its maximum output level if it is committed to offering Regulation Up service. That is because it must be prepared to make further upward adjustments in generation to boost voltage if called upon. In California, regulation service providers must be capable of changing their output within 10 minutes of being asked to do so and must be able to stay online at the required output level for at least two hours.
BRIEF SUMMARY OF THE INVENTION
[0017] The invention is a hybrid electric vehicle powertrain comprising an internal combustion engine; a first electric motor-generator connected to the engine and used to start the engine or supply electricity to the second motor-generator; a second electric motor generator that supplies traction power to the vehicle wheels, a first electrical energy storage device, a second electrical energy storage device, a power electronics system, a control system, and a charging system.
[0018] The first electrical energy storage device is a battery that delivers or absorbs electrical energy when the vehicle is operated as a hybrid or when the vehicle is operated using stored electrical energy only.
[0019] The second electrical energy storage device is a flywheel, a capacitor or ultracapacitor or supercapacitor, or a battery that absorbs or delivers current only as necessary to protect the first energy storage device from current above the damage threshold for the first energy storage device.
[0020] A power electronics system, responsive to the control system, transfers electrical energy from each electrical energy storage device or electric motor-generator to each other electrical energy storage device or electric motor-generator.
[0021] The control system has means to determine and control the energy flow path through the power electronics. The charging system uses externally supplied electricity to recharge either or both the first energy storage device and the second energy storage device.
[0022] The system comprises (contains at least) either a fuel powered engine or a fuel cell, a battery, a fast energy storage system, power converters, controllers, drive motors, an electrical distribution system, and a drive train.
[0023] One of three devices can be used for fast energy storage. (1) A flywheel apparatus comprises a rotor, a motor-generator, bearings, a housing, a power converter and controller, and ancillary subsystems. (2) A small battery optimized for high cycle life. (3) A super-capacitor bank comprises a number of electrostatic energy storage components.
[0024] In broad terms, a preferred embodiment of the apparatus comprises a battery pack, a fast energy storage device, an engine, a transmission, power electronics, and controls. A preferred embodiment of the method comprises use of the fast energy storage device to perform short, frequent, high intensity charge and discharge functions to preserve the battery to provide average power for driving in electric-only mode.
[0025] The power electronics package comprises a number of power conversion devices to manage the flow of power between the various subsystems. One conversion device is used for grid interface. Associated with the grid interface power electronics are a controller to manage the two-way flow of power between the vehicle and the grid which may include a device for communicating with a utility, independent system operator, aggregator of services, or other relevant entity.
[0026] The grid interface system may comprise some or all of the following elements:
[0027] GPS-based vehicle location sensing device
[0028] Two way data communications
[0029] Charge/discharge control unit
[0030] “Plug” or hookup device capable of bi-directional power flows
[0031] External (garage-installed) charger for bi-directional power flows
[0032] Charger(s) at workplace parking lots and garages
[0033] A purpose of the invention is to provide a plug-in hybrid drive-train system that will yield at least a 150,000 mile durability for a passenger car in ordinary use.
[0034] A second purpose of the invention is to combine the battery and a separate fast energy storage element of a plug-in hybrid to provide services to the electric distribution grid when the vehicle is connected to the grid where Vehicle to Grid (V2G) systems allow the electric power grid to benefit from many small power sources connected to it at random and dispersed locations. Regulation services have the best potential to use the capabilities of a vehicle-based energy storage system to add value to the grid but other ancillary services may be comparably beneficial. Ancillary services provided by a dispersed fleet of vehicles may be cheaper and more effective than regulation services provided by power plants today. A large population of V2G vehicles would be able to perform frequency stabilization by sourcing or sinking energy pulses thereby mitigating the need for frequent adjustment of power plant output. With respect to V2G applications, the main problem with existing conventional hybrids is that providing ancillary services to the electrical distribution system is likely to entail a sufficient number and depth of charge-discharge cycles to degrade the performance of the battery and reduce battery life. This problem is exacerbated when cycling involves high current operation at a low state of charge.
[0035] A third purpose of the invention is to provide distributed storage for non-firm sources of electricity such as wind. Wind patterns in some parts of the world (the American Midwest and West Texas for example) are such that there is more wind at night than in the daytime. A large population of V2G vehicles would be able to absorb non-dispatchable, off-peak wind generation to charge their batteries during off-peak hours when energy is inexpensive.
[0036] One advantage of the invention is a reduced number of charge discharge cycles of the battery with correspondingly increased battery life. This is accomplished by using a fast energy storage system that has a cycle life exceeding battery cycle life by at least 10× and sizing the fast energy storage system to source or sink brief, frequent pulses and provide most or all of the V2G ancillary services.
[0037] A second advantage of the invention is that fast energy storage reduces the life-cycle cost of a battery. Without fast energy storage, the battery will experience a large number of shallow cycles and occasional high current pulses when the battery is at a low state of charge. The invention reduces the number of shallow charge cycles that the battery would experience by as much as 90%-100% and protects the battery from high current pulses. In particular, the fast energy storage system protects the battery from the deleterious effects of high rate discharge while at a low state of charge. By doing so, the invention extends life of the battery so that replacement is not required for the life of the vehicle.
[0038] A third advantage of the invention is reduced total weight of the energy storage system. The combined weight of the battery and fast energy storage device are less than the weight of a battery sized to handle frequent cycling and high current pulses.
[0039] A fourth advantage of the invention is improved durability of the energy storage system.
[0040] A fifth advantage of the invention is that fuel economy with respect to conventional vehicles is improved. The invention enables as much as 2× improvement in fuel efficiency and an improvement in fuel economy that, depending on the driving cycle, may be as much as 5× for the typical driver. Current hybrids provide a 30-50% improvement in fuel economy.
[0041] The invention requires integration of electrochemical, electrostatic, and electro-kinetic storage technology. The apparatus and its function have application as a distributed energy system.
[0042] Further aspects of the invention will become apparent from consideration of the drawings and the ensuing description of preferred embodiments of the invention. A person skilled in the art will realize that other embodiments of the invention are possible and that the details of the invention can be modified in a number of respects, all without departing from the inventive concept. Thus, the following drawings and description are to be regarded as illustrative in nature and not restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] The features of the invention will be better understood by reference to the accompanying drawings that illustrate presently preferred embodiments of the invention. In the drawings:
[0044] FIG. 1 is a drawing of the plug-in hybrid system.
[0045] FIG. 2 is a drawing of a plug-in hybrid system with clutches.
[0046] FIG. 3 is a drawing of a plug-in parallel hybrid system.
[0047] FIG. 4 is a drawing of a plug-in series hybrid system.
[0048] FIG. 5 is a drawing of a plug-in series hybrid system with four-wheel drive.
[0049] FIG. 6 is a drawing of a plug-in series hybrid system with a fuel cell.
[0050] FIG. 7 is a drawing of an electronic switch assembly.
[0051] FIG. 8 is a schematic drawing of the power converter and controller and attached devices for a system using three motor/generators and a capacitor fast energy storage system.
[0052] FIG. 9 is a schematic drawing of the power converter and controller and attached devices for a system using three motor/generators and a flywheel fast energy storage system.
[0053] The following reference numerals are used to indicate the parts and environment of the invention on the drawings:
1 Engine 2 First motor/generator 3 Second motor/generator 4 Transmission 5 Clutch 6 Power converter and controller 7 Battery 8 Fast energy storage (flywheel, high cycle battery, or capacitor) 9 Differential 10 Axle 11 Wheel 12 Plug/disconnect 13 Stationary V2G interface 14 Grid 15 Driveshaft 16 Fuel Cell 17 switch module 18 DC bus 19 DC bus common 20 DC bus capacitor 21 inductor 22 transformer 23 AC link 24 charger input/output 25 DC supply 26 flywheel fast energy storage 27 gate drive 28 controller 29 diode 30 insulated gate bipolar transistor (IGBT) 31 rear motor/generator (MGR)
DETAILED DESCRIPTION OF THE INVENTION
[0085] Referring to FIG. 1 , a preferred embodiment of apparatus is disclosed. The invention comprises an engine 1 connected to a transmission 4 . The engine 1 may be connected through a clutch or may be connected through fixed gears or shafting. A first motor/generator 2 is connected to the shaft either on the engine 1 or the transmission 4 side of the engine/transmission interface. The transmission 4 transfers power from the engine 1 and first motor/generator 2 through the transmission 4 to the driveshaft 15 , differential 9 , and then the axle 10 and the wheels 11 . A second motor/generator 3 is connected to the transmission 4 at a point in the transmission 4 closer to the output. The drivetrain may use zero, one, two, or three clutches to selectively disengage the engine 1 or an individual motor/generator 2 , 3 .
[0086] The drivetrain comprises the driveshaft 15 and differential 9 , which both may be part of the transmission 4 or separate from it, and the axle 10 or split shaft.
[0087] The motor/generators 2 , 3 may be mounted in-line with the drive train or may be connected to the drivetrain through gears, belts or chains, or hydraulics.
[0088] The battery 7 preferentially uses lithium chemistry but may also use NiMH, NiCAD, or Pb:acid. The fast energy storage device 8 may comprise a flywheel, a capacitor, or a high power battery. Preferentially, the flywheel uses a high-speed rotor housed in an evacuated chamber and integral electronics to drive the flywheel. Alternatively, the flywheel may be of any type that incorporates a rotor and built in motor/generator so that energy may be stored and retrieved electrically. The capacitor may be of any type including super capacitors, ultra capacitors and electrolytic capacitors. The fast energy storage device 8 may have an energy storage capacity that is considerably smaller than the capacity of the battery 7 .
[0089] In the preferred embodiment, the engine 1 is a small piston engine 1 fueled with gasoline. Alternatively, the engine 1 may be an internal combustion engine 1 fueled with gasoline, ethanol, flex-fuel, diesel fuel, bio-diesel, natural gas, propane, or hydrogen.
[0090] A fast energy storage device 8 and a battery 7 are connected to a power converter and controller 6 . The power converter and controller 6 directs the flow of energy between the flywheel or capacitor 8 , the battery 7 , the first motor/generator 2 and the second motor/generator 3 . All the elements that store or use electricity ( 2 , 3 , 7 , and 8 ) may either source or sink electricity. The power converter and controller 6 may comprise a single assembly or subassemblies. The subassemblies may be collocated within a single module or they may be housed as separate modules. They may be located together or dispersed throughout the vehicle.
[0091] The interface between the vehicle and the grid may comprise a plug and receptacle 12 where AC power to the vehicle is converted to DC power on-board. The AC supply may by 110V, 220V, 480V single or three phase or other commercially supplied AC electricity. Alternatively, a stationary V2G interface 13 that has bi-directional power handling capability may provide V2G service. The stationary V2G interface 13 may communicate with a utility in order to dispatch the V2G resource or to allow isolation by the utility. The stationary V2G interface 13 may connect to the vehicle through a DC or AC link and a plug/receptacle 12 .
[0092] Operation of the invention involves driving in a number of different modes of operation.
[0093] In the first driving mode, the engine 1 supplies motive power to the wheels 11 and the first motor/generator 2 and the second motor/generator 3 are free to rotate but are not energized.
[0094] In the second driving mode of operation, the engine 1 is turned off and all motive power is provided using either the first motor/generator 2 or the second motor/generator 3 or both. This mode is referred to as EV mode. In this mode, electrical energy is supplied by either the fast energy storage device 8 and the battery 7 in a combination determined by the power converter and controller 6 .
[0095] In the third driving mode of operation, motive power is provided by both the engine 1 and either the first motor/generator 2 , the second motor/generator 3 or both motor/generators. In this mode, electrical energy is supplied by either the fast energy storage device 8 and/or the battery 7 in a combination determined by the power converter and controller 6 .
[0096] In the fourth driving mode of operation, the vehicle is decelerating or descending on a grade and energy is recovered regeneratively. In this mode of operation, retarding torque is applied to the transmission 4 by either the first motor/generator 2 , the second motor/generator 3 or both motor/generators. In this mode of operation, one or both motor/generators functions as generators and convert recovered kinetic energy of the vehicle into electricity. The electricity is delivered to either the fast energy storage device 8 or the battery 7 . The flow of electricity to the energy storage devices is directed by the power converter and controller 6 . In this mode of operation, the engine 1 may be rotating or not rotating.
[0097] In the fifth driving mode of operation, the engine 1 drives the first motor/generator 2 so that it produces electricity to charge the battery 7 or the fast energy storage device 8 or both in a combination determined by the power converter and controller 6 . In this mode, the vehicle may be either stopped or moving.
[0098] Performing V2G services involves a number of different V2G modes of operation.
[0099] In the first V2G mode of operation, the grid sources energy through the stationary V2G interface 13 to the plug/receptacle 12 and subsequently the power converter and controller 6 . The controller 6 uses this energy to charge either the fast energy storage device 8 or the battery 7 or both.
[0100] In the second V2G mode of operation, energy from the fast energy storage device 8 is extracted by the power converter and controller 6 and supplied to the grid 14 via the plug/receptacle 12 and the stationary V2G interface 13 .
[0101] In the third V2G mode of operation, energy from battery 7 is extracted by the power converter and controller 6 and supplied to the grid 14 via the plug/receptacle 12 and the stationary V2G interface 13 .
[0102] In the fourth V2G mode of operation, energy from engine 1 is converted to electricity by either or both of the motor generators 2 and 3 and is then extracted by the power converter and controller 6 and supplied to the grid 14 via the plug/receptacle 12 and the stationary V2G interface 13 . Any of the modes of V2G operation may be commanded automatically by software residing in the vehicle or may be commanded by an outside entity such as a utility, an independent system operator, an aggregator of services, or any other end user.
[0103] The fast energy storage device 8 is tolerant of frequent cycling and high power operation while the battery 7 is not. In all modes of operation, the power converter and controller 6 typically directs the flow of energy such that the number of charge and discharge events experienced by the battery 7 is minimized. Additionally, the fast energy storage device 8 is operated to minimize the magnitude and extent of high power operation of the battery 7 . By protecting the battery 7 from excessive cycling and excessive high power operation, several benefits accrue. The durability of the combined energy storage system is improved compared to using a battery 7 without a fast energy storage device 8 . The battery 7 may be operated over a deeper depth of discharge than would otherwise be possible without the protection of the fast energy storage device 8 . Thus a given all-electric range of travel can be attained with a much smaller battery 7 than would be possible without the protection of a fast energy storage device 8 .
[0104] Many other modes are possible where the functions of the five defined modes are used in combination.
[0105] Many variations of the invention will occur to those skilled in the art.
[0106] Referring to FIG. 2 , the first variation uses one or more clutches 5 to selectively disengage the engine 1 , the first motor/generator 2 or the second motor/generator 3 .
[0107] Referring to FIG. 3 , a second variation is the parallel configuration in which only one motor/generator (the first motor/generator 2 ) is used. The transmission 4 may be an automatic or manual transmission that may include zero, one, or two clutches 5 .
[0108] In either the first variation or the second variation, the transmission 4 may support two-wheel drive as shown. Alternatively, the transmission 4 may be capable of full time or part time four-wheel drive.
[0109] Referring to FIG. 4 , the third variation eliminates the transmission 4 entirely. In this case, the first motor/generator 2 is connected directly to the engine 1 . The first motor/generator 2 functions primarily as a generator but may also function as a motor that could be used to start the engine 1 . The second motor/generator 3 powers the wheels 11 directly or indirectly. The second motor/generator 3 is connected to the differential 9 , the driveshaft, or the wheels 11 directly. The second motor/generator 3 may be connected through fixed gearing or other compact and limited drivetrain components or subassemblies. All motive power is transmitted from a point of point of generation or storage to the drive motor electrically. This configuration is a series plug-in hybrid or a series hybrid.
[0110] Referring to FIG. 5 , a fourth variation uses multiple drive motors instead of a single second motor/generator 3 .
[0111] Referring to FIG. 6 , a fifth variation uses the series hybrid configuration from above and uses a fuel cell to generate electricity. The fuel cell replaces the engine 1 and the first motor/generator 2 . In this variation, a fast energy storage device 8 and a battery 7 are connected to a power converter and controller 6 . The power converter and controller 6 directs the flow of power between the fast energy storage device 8 , the battery 7 , and the second motor/generator 3 . All the elements that store or use electricity ( 3 , 7 , and 8 ) may either source or sink electricity. In this variation the fast energy storage device 8 protects the battery 7 from severe or frequent charge and discharge events. Additionally, in this configuration, the fast energy storage device 8 protects the fuel cell 16 by providing immediate power for acceleration where the fuel cell has poor throttle response and could be damaged by such an event.
[0112] FIGS. 7, 8 and 9 disclose the details of the power converter and controller 6 . FIG. 7 shows nomenclature for a switch 17 comprising a diode 29 and a solid-state switching device 30 . Preferentially, the solid-state switching device 30 is an insulated gate bipolar transistor (IGBT) although other switching devices may be used. The switch 29 is commanded to open or close through signals from the controller to the gate drive 27 .
[0113] FIGS. 8 and 9 indicate the controller 28 that issues commands to each switch 29 in the system. For clarity, only a few representative connections are shown. In practice, all switches 29 receive input from the controller 28 . Additionally, the controller 28 may receive information from each switch 29 including temperature, state (open or closed), and fault condition (clear, warning, fault).
[0114] Each switch 29 is switched open or closed in response to a command from the controller 28 . Switching is conducted to energize or disable components or subsystems, for commutation, chopping, or to synthesize an AC waveform. The power ratings of the attached devices vary. The corresponding power ratings of the associated switches 15 may also vary in order to allow minimization of the overall size, weight and cost of the power converter and controller 6 .
[0115] The power converter and controller 6 has a DC bus with one bus bar 18 at elevated potential and a second bus 19 at a common potential. An H-bridge leg comprises two switches 29 connected in series where the pair of switches 29 connect the two bus bars of the DC bus 18 , 19 and the point between the switches connects to one phase leg of the connected AC device.
[0116] A DC bus capacitor 20 serves several purposes individually or simultaneously. Mainly, the bus capacitor 20 provides dynamic energy storage necessary for the motor drive and buck-boost functions conducted by the inverter legs. A single DC bus capacitor 20 serves all of the phase legs in the power converter and controller 6 .
[0117] The power converter and controller 6 sources or sinks power from the motor/generators, 2 , 3 , 31 flywheel fast energy storage 26 , and the charging port 24 in AC format. The H-bridge legs of the power converter and controller can operate as a rectifier, an active rectifier, a motor drive, or an AC inverter in order to interface with these devices.
[0118] The H-bridge legs may also function as a chopper, or perform any other power processing accomplished by switching, such as those used for DC-DC conversion. These configurations are used for the interface to the battery 7 and the fast energy storage capacitor 8 .
[0119] Inductance is required for buck-boost functions and as part of the motor drive circuitry. Motors have non-negligible inductance that may be sufficient for this purpose. For devices with low inherent inductance such as batteries 7 or energy storage capacitors 8 , an inductor 21 may be incorporated in the circuit.
[0120] For motors MG 1 2 , MG 2 3 , MGR 31 , and the motor/generator in the flywheel 26 , portions of the power converter and controller 6 function as a bi-directional motor drive. Three-phase drive is typical but other numbers of phases may be used as well. FIGS. 3 and 4 show 3-phase drive configurations. To produce torque, a number of control strategies may be implemented including pulse width modulation (PWM), space vector control, and simple commutation.
[0121] Buck/boost converters perform DC to DC voltage conversion by using high frequency switching to cause dynamic response in an inductance. A capacitor 20 smooths out transients associated with the switching frequency of the converter. An inductor 21 or inherent inductance, a capacitor 20 , and a switch 15 are required to perform either a buck or boost function. FIGS. 8 and 9 show buck/boost circuits for the battery 7 . FIG. 8 shows a buck/boost circuit for the fast energy capacitor 8 . In these examples, the use of two switches 17 for each buck/boost stage allows the inductor 21 and the capacitor 20 to be used for either buck or boost operation without reconfiguration.
[0122] Buck/boost converters are used for DC-DC conversion for higher power attached devices. An AC link 23 and transformers 22 are used for AC voltage conversion to the charger port 24 . An internal AC link 23 is used to allow transformation to a lower voltage so that a separate inverter subassembly can provide lower voltage output (12V, 42V) at the DC supply ports 25 .
[0123] The charger port 24 is shown as a single-phase system but a 3-phase system may be used as well. When the vehicle is at rest and connected to a utility grid, the charger circuitry may deliver energy to the DC bus 18 , 19 and from there to any of the attached devices. During V2G operation, energy from the battery 7 , fast energy system 8 , 26 or engine 1 via MG 1 2 may be delivered to the grid.
[0124] The DC output ports 25 are energized by a small active rectifier that operates at a voltage that is different from the voltage of the principal DC bus 18 , 19 . This active rectifier uses switches 17 of the type used throughout the power converter and controller 6 and communicate with the controller 28 . The configuration shown in FIGS. 8 and 9 can source low power DC at two voltages, preferentially 12V and 42V.
[0125] All such variations are intended to be within the scope and spirit of the invention. | 4y
|
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to the Internet and related devices and, more particularly, to an Internet web server that provides web documents, or a physical device, that relate to the interactive provision of instructional information particularly in medical and other emergency situations.
[0003] 2. Description of Related Art
[0004] In any emergency operation, such as in the rescue of an unconscious victim, it is of paramount importance for the individuals involved to take the proper actions as soon as possible. Normally, if proper rescue operations are applied to a victim, the chance of survival or recovery of the victim are much improved. In order to carry out many rescue operations effectively, the rescuer must follow the steps set forth in any of the standard medical rescue manuals. The proper procedure is generally based upon the particular condition of the victim.
[0005] Standard rescue procedures are well developed in the medical field and are beyond the scope of this disclosure, except so far as may be necessary to explain the nature and applications of the present concepts. Studies have shown that even amongst professional rescue operators such as paramedic, firemen and nurses, relatively few people can remember the proper rescue sequence or procedure precisely. This is further complicated because the “standard” procedures frequently change as they are refined and new methodologies are introduced.
[0006] Even more importantly, a paramedic, fireman, nurse or other emergency medical technician is generally not available in the critical initial moments of an emergency. Rather, lay rescuers, i.e., ordinary individuals, generally discover emergencies, and these people are responsible for both initiating the proper procedures and determining whether additional assistance from professionals is necessary.
[0007] In general, the standard procedures have become more complex, and more procedures have been created for a growing number of emergencies. As procedures become more and more complex, potential rescuers have more and more difficulty in obtaining familiarity with them and memorizing them.
[0008] Moreover, the ability of a rescuer to recall and employ the proper emergency procedure is further hampered by the chaotic circumstances typically surrounding an emergency situation.
[0009] The prior art has seen varied approaches to the handling of emergency instructions or to the use of audible instructions. The prior art systems have included use of instruction booklets having indices in which the particular emergency has to be located; then pages flipped to locate the emergency; and read step by step while trying to perform the emergency with one hand and constantly going back to reread the instructions. The prior art also has included sophisticated computer instructions that are activated by a particular code on a telephone to give a caller instructions as to how to fill out a bank deposit, how to call a particular bit of information regarding insurance policies or the like.
[0010] Attempts have been made to provide devices to assist in providing emergency information to ensure that a rescuer performs the rescue operation properly. However, most of these have been devices dedicated to just one type of emergency—cardiopulmonary resuscitation (CPR). One of such devices is shown in U.S. Pat. No. 4,451,158 to Selwyn et al. Selwyn's device is in the form of a timer with various coded pattern displays at predetermined time intervals to indicate various stages in the rescue operation. The main drawback of the device is that confusion may still arise for the rescuer to memorize which procedural step is related to which code.
[0011] Another device, such as that shown in U.S. Pat. No. 4,588,383 to Parker et al., provides voice instructions solely for the rescuer to carry out the CPR rescue operation. Other portable CPR-prompting devices have been disclosed in U.S. Pat. No. 4,588,383 to Parker et al., U.S. Pat. No. 4,583,524 to Hutchins and U.S. Pat. No. 5,088,037 to Battaglia.
[0012] An emergency audible instruction apparatus for a fire extinguisher is disclosed in U.S. Pat. No. 4,303,395 to Bower. Such a device provides audible instructions which instruct a user in handling a fire emergency. The device is activated automatically when the fire extinguisher is removed from its base. Bower suggests that a device embodiment storing multiple instructions may be included with a dial selector for selecting a particular emergency. However, unlike the CPR-prompting devices, the Bower device is not portable and suggests purely mechanical means for providing a portable solution.
[0013] A generalized manual key operated message generator is described in U.S. Pat. No. 3,845,250 to O'Brien. However, this device is not portable nor adapted for emergency use. To retrieve a message, the user presses a series of keys to assemble a complete message upon prerecorded parts.
[0014] U.S. Pat. No. 5,086,391 describes a medical alert system for domestic use comprising two major components, a device worn about the neck and a home computer. The device worn about the neck and the home computer reciprocally communicate with one another to provide the wearer of the device, as well as an attendant of the device, both instructions for care and a method to call for emergency help. The home computer contains an audio synthesizer and a voice amplification device to communicate verbally to the individual. The device may be used to summon an ambulance from a remote location if the injured person is unable to reach a telephone.
[0015] As can be seen, most of the known devices are bulky in size, not portable to be located conveniently beside the victim at the rescue site, provide very limited information and are complex to operate.
[0016] Other prior devices have been developed in the past and include the Emergency Information Apparatus and Methods of U.S. Pat. No. 5,521,812 and the Instructional CD Player for providing emergency information of U.S. Pat. No. 5,668,954, the disclosures of each of which are fully incorporated herein by this reference.
SUMMARY OF THE INVENTION
[0017] A principal object of the present invention is to provide an Internet web server and method for an interactive virtual implementation and provision of instructional information in medical and other emergency situations. Another object is to provide a new form of a portable device which can be conveniently located beside a victim or near an emergency site to assist the rescuer to carry out the rescue operation. Either implementation provides step by step instructions sequentially in response to the condition of the victim.
[0018] A particularly important aspect of the present invention, whether implemented via an Internet web server, or a physical device, is the provision of a plurality of step indicators to assist the user in determining progress with respect to completion of the instructional program. Preferably, a separate indicator such as a light, is provided for each step in the program, and as steps are completed, the corresponding indicator light is either extinguished or illuminated in a manner to provide the user with an indication that the step has been completed. During a crisis, such as a medical emergency, the persons involved can be nervous, the situation can be chaotic, there can be uncertainty as to the steps to be taken. Therefore, it is important to have something to indicate the status of the beginning and ending of the procedure as well as each step of the procedure. Such step indicators provide this important feature. Alternatively, a display of numbers (e.g., 1 through 8 ) can be provided with the display stepping through the numbers as steps are completed.
[0019] These objects and features are provided in the emergency information concepts of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] These and other advantages of the present invention are best understood with reference to the drawings in which:
[0021] FIG. 1 is a partial elevation of an emergency information apparatus of the prior art.
[0022] FIG. 2 is a block diagram of a network data distribution system,
[0023] FIG. 3 shows an Internet browser window,
[0024] FIG. 4 shows an exemplary web page that includes a virtual representation of an information apparatus,
[0025] FIG. 5 is a flow chart that describes a method of providing instructional programs over the Internet in connection with a virtual information apparatus, and
[0026] FIG. 6 is a block diagram of a hardware implementation device according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] Referring first to FIG. 1 , there is shown a partial elevation of an emergency information apparatus of the type disclosed in U.S. Pat. No. 5,521,812 and No. 5,668,954. The external portion of the apparatus is comprised primarily of a casing 100 . The casing 100 is preferably of a rigid material, such as hard plastic, PVC, or the like. In addition, the casing and the items disposed in and within the casing 100 are, together, water resistant, such that water will not seep into the internal portion of the apparatus and induce electrical shorts or corrosion. This is beneficial so that the apparatus may be used, for example, in the rain, or during fire emergencies when water is being used to dowse the fire. The bottom of the casing 100 (not shown) preferably includes shock absorbing pads, such as rubber pads embedded within the casing 100 and exposed at the outer edge of the casing 100 to reduce shock and vibration when the apparatus is set down.
[0028] On the left side of the apparatus there is a hinged compartment 180 . The compartment 180 is in a closed and locked position, as shown. The compartment 180 may be opened through a release (not shown), which may be on the side or top of the apparatus as known in the art. The compartment 180 is adapted for receiving a program medium such as a compact disc (CD) (not shown). When open, the compartment 180 may receive a CD, and when closed, the compartment 180 holds the CD within the apparatus.
[0029] While a CD is one form of the program medium, other media are generally suitable. These media preferably are of a standard form and storage format, such as Data Play CD, micro cassette, floppy disk, DAT, flash memory or ROMs on a PCMCIA card.
[0030] As shown in FIG. 1 , there are provided five rows of three program selectors 110 . The program selectors 110 are used for selecting and thereby starting the playback of programs stored therein. The number of program selectors 110 is not critical, although several should be provided so that several emergencies may be addressed. To further control playback, there are also provided several playback selectors 160 , including a pause key 160 H, a reverse key 160 R, a forward key 160 F and a continued play key 160 P. The program selectors 110 and the playback selectors 160 are preferably push buttons. The program selectors 110 and playback selectors 160 preferably are backlit.
[0031] A nearly limitless number of programs may be used with the apparatus. To accommodate this flexibility, the program selectors 110 are preferably labeled with numbers 1 - 15 , and these numbers correspond to stored programs. Programs may include instructions relating to AIDS/HIV, bloody nose, bumps and bruises, burns, choking, CPR, dental injuries, drowning, earthquakes, electric shock, external bleeding, eye injuries, fires, fractures and dislocations, frostbite and hypothermia, heart attack, heat emergencies, insect stings and bites, internal injuries, muscle cramps, poisoning, rescue breathing, seizures and shock, stroke, spinal injuries, sprains and strains, and emergency action principles.
[0032] With each start program, there can be provided a removable overlay 115 . The overlay 115 is adapted to be placed over and around the program selectors 110 . The overlay 115 labels the program selectors 110 in accordance with the stored programs. Thus, by scanning the overlay 115 , the user can determine which program selector 110 to press to begin a playback of a desired program. The overlay 115 is preferably a think piece of plastic, with the labels being resistant to erasure from typical use of the apparatus. The apparatus further includes a speaker 120 for playing back the audio portion of the programs stored.
[0033] Once a program selector 110 has been pressed and the selected program has begun to play, the number of the program as associated with the program selector 110 and the name of the program is displayed on a display 160 . In FIG. 1 , it is shown that the program number 5 related to “bleeding” has begun playback. The programs may be in multilingual audio. Preferably there is a language selector 185 in the casing.
Virtual Implementation of Information Apparatus
[0034] Turning now to FIG. 2 , there is shown a network data distribution system in which a preferred embodiment of the invention is implemented. The data distribution system includes a local device 600 , a data access network 620 , and a web server 650 . The local device 600 , the data access network 620 and the monitoring server 630 comprise the network data distribution system.
[0035] The local device 600 preferably comprises a client computer which is configured to access the web server 650 via the local access network 120 . The client computer may be, for example, a PC running a Microsoft Windows operating system. The local device 600 preferably includes an output device, such as display 601 , and an input device, such as keyboard 602 and/or pointing device 603 (e.g., mouse, track ball, light pen, or data glove). The local device 600 also includes a docking station 611 that allows a data access device, such as a PDA to interface with the local device 600 and exchange data.
[0036] Furthermore, the local device 100 may be any device that provides some measure of individual user interactivity with a source of web pages. For example, the local device could be an Internet appliance, network computer (NC, or an appropriately Internet-enabled device such as a PDA, mobile phone, etc.
[0037] The data access network 620 provides lower layer network support for the local device 100 to interact with the web server 650 . The data access network 620 preferably comprises a common or private bidirectional telecommunications network (e.g., a public switched telephone network (PSTN), a cable-based telecommunication network, a LAN, a WAN, a wireless network), coupled with or overlayed by a TCP/IP network (e.g., the Internet or an intranet).
[0038] The web server 650 may be of the type known in the art and has the ability to serve web pages to the local device 600 , as requested in the manner known in the art. It should be appreciated that the web server 650 is generic for any source of web pages available to the local device 100 . Thus, for example, the web server 650 could be accessible from the Internet, or it could be a part of an intranet and represents any number of web servers.
[0039] A browser application, such as Microsoft Internet Explorer or Netscape Navigator is preferably installed on the local device 600 . When the local device 100 is connected to the web server 650 through the data access network 620 , the user of the local device browses the web server 650 from the local device 600 using the browser application. The browser application itself need not be stored on the local device 600 .
[0040] Referring now to FIG. 3 , there is shown a browser window 700 generated by a browser application, here Microsoft Internet Explorer. The browser window 700 is familiar to those skilled in the art, so the particulars are not described further herein. Further information regarding the use of most browser applications and their technical specifications is abundantly available.
[0041] Several aspects of the browser window 700 are identified for further reference below. These aspects include a display pane 710 , an address bar 720 and a title bar 730 . The display pane 710 is a region of the browser window 700 wherein the browser application causes web pages received by the browser application to be displayed. The address bar 720 is another region of the browser window 700 and the browser application displays URLs in the address bay 720 corresponding to the web page currently displayed in the display pane 710 . The user can also enter a URL into the address bar 720 , and the browser application will attempt to load the web page or other object to which the entered URL points. The primary feature of the title bar 730 is that it displays the title of the browser application.
[0042] The web server 650 preferably includes a memory that includes one or more web pages that are associated with a virtual representation of the emergency information apparatus described above. The web server 650 downloads the web pages to the local device 600 so that a representation of the emergency information apparatus is displayed on the display device 601 within the browser display pane 710 .
[0043] FIG. 4 shows an embodiment of a web page that includes a representation of a virtual emergency information apparatus 800 . The virtual information apparatus 800 is preferably configured to simulate the operation of the physical apparatus described above with respect to FIG. 1 . According, the web page includes several hypertext program keys 810 , wherein each program key 810 is associated with a program that is stored in the web server 650 . By clicking on any of the program keys 810 , a user of the local device 600 causes the web server to load and initiate a program associated with the particular key 810 . In a preferred embodiment, each program is associated with a set of instructions relating to an emergency medical scenario, although the programs could vary.
[0044] The virtual information apparatus 800 also includes one or more operational keys 812 that allow a user using the local device 600 to perform functions relating to the program, such as start, stop, pause, etc. In addition, the apparatus 800 includes step indicator 814 that provide a representation of the status with respect to the number of completed steps in the program, and which are described in more detail later.
[0045] With reference to FIG. 4 , the virtual information apparatus also includes a representation of one or more acknowledgement keys 816 that allow a user of the local device 600 to acknowledge the completion of steps associated with a program.
[0046] FIG. 5 shows a flow chart that describes process in web pages associated with the virtual emergency information apparatus are downloaded to the local device 600 . The process begins when a user accesses the web server 650 using the local device 600 (step 910 ). In step 920 , the web server 650 downloads one or more web pages to the local device 600 . The web pages preferably include one or more introductory pages that allow a user to select a particular instructional template for the virtual information apparatus 800 from a list of options (step 930 ). For example, the user could select an instructional template associated with the provision of emergency services or provision of some category of emergency services. The templates could also be associated with other subject matter.
[0047] In any event, in step 940 , after the user selects the instructional template, the web server downloads a web page in which is displayed a representation of the information apparatus 800 configured in accordance with the selected instructional template. For example, FIG. 8 shows the web page associated with the information apparatus 800 being configured to implement emergency medical instructions. The program keys 810 each include a label that indicates the particular instructional set that will be implemented when the respective key 810 is selected.
[0048] In step 950 , the instruction program is initiated. The web server 650 preferably issues instructions that causes the local device 600 to play the particular program in the manner described above with respect to the physical emergency information apparatus. The user can pause, stop, play or interact with the program using the acknowledgement keys 812 and the operational keys 810 .
[0049] Each program preferably comprises plural audio instruction messages that relate to steps in a procedure. In one embodiment, the procedure relates to instructional steps for dealing with an emergency medical situation. However, the procedure could also relate to instructional steps for any other type of situations for which instructional steps are appropriate. The program further comprises playback control information for directing playback of the audio step message in a predefined pattern and in accordance with operation of the operational keys 810 and acknowledgement keys 812 .
[0050] In a preferred embodiment, the acknowledgement keys 812 are used interactively in response to the audio instructional steps. The user preferably selects an appropriate acknowledgement key 812 to acknowledge an audio instruction. Preferably, the program includes predetermined stop points where the program either pauses for a predetermined time or repeats an instruction until the user acknowledges completion of a step using one or more of the acknowledgement keys 812 . The apparatus is preferably configured to respond to voice acknowledgements. The apparatus could be equipped with voice activation software that recognizes and responds to the voice of a user.
[0051] For example, in an emergency medical instruction program, the audio instruction may instruct the user to check a person's breathing. The program could repeat the instruction or pause playing of the next instruction until the user acknowledges that this step has been completed. Once an acknowledgment has been received, the program would then continue.
[0052] The step indicators 814 preferably assist the user in determining progress with respect to completion of the instructional program. Preferably, a separate indicator, such as a light, is provided for each step in the program. Any given program (e.g., category of medical emergency, such as bleeding, burns, seizure, etc.). For example, a “bleeding” program may involve four steps, a “seizure” program eight steps, and the like. When one of the programs is selected, all of the lights can be illuminated, such as illuminated green, so that the operator can readily see that there are four, five, six or more steps as the case may be. As the steps are completed, the corresponding indicator light is either extinguished or illuminated, or illuminated in a different color, to provide the user an indication that the step has been completed. The indicator could also blink or flash during the pendency of a particular step. The step indicators 814 thus provide the user with a visual status and summary relating to the progress of the particular program that is being played.
[0053] In a preferred embodiment, the docking station 611 can be used to transfer one or more programs and virtual representations of the information apparatus to a PDA, such as a Palm Pilot. The PDA may then be used to implement the instructional program. For example, the user could dock the PDA to the docking station 611 and then download a virtual information apparatus into the memory of the PDA. Thereafter, the functionally provided in the web page representation of the virtual information apparatus would be available directly on the PDA, preferably via a touch screen on the PDA. Preferably, audio files in the form of voice instructions are downloaded to the PDA as part of the instructional program and virtual information apparatus. The PDA is also configured to accept voice instructions from the user from a microphone positioned on the PDA. Alternatively, the programs can be stored or embedded in the computer (e.g., in the hard drive) or PDA memory and be accessible via an emergency icon.
Physical Device
[0054] The virtual apparatus of the present invention as shown in FIG. 4 also can be implemented in a physical device of the nature earlier described in connection with FIG. 1 , but further includes the step indicators 814 in the physical device operating in the same manner as described above and for the same purposes. Thus, the concepts of the present invention can be implemented in the form of a virtual device through a network data distribution system and the Internet, or via other communications systems, and can as well be implemented in a physical device like that shown in FIG. 4 .
[0055] This device typically is battery powered and includes a speaker 820 ( FIG. 4 ) for providing audible instructions and includes an internal system as shown in FIG. 6 with a microcontroller interconnected with the keypad 810 and the step indicators 812 to appropriately cause illumination or extinguishing of the lights (e.g., LED's). The programs preferably are stored in a flash memory, and the other components of the system shown in FIG. 6 provide the audio information.
[0056] As noted earlier, the steps can be indicated via a display of numbers which are stepped through as program steps are completed, for either or both of the virtual system or portable device.
[0057] While embodiments of the present invention have been shown and described, various modifications may be made without departing from the scope of the present invention, and all such modifications and equivalents are intended to be covered. | 4y
|
FILED OF THE INVENTION
The present invention relates to methods and apparatus for cutting or machining parts and more particularly to removing flash from plastic parts automatically with computer numerical control (CNC) tools.
BACKGROUND OF THE INVENTION
Many plastic processes such as injection molding, blow molding, compression molding and reaction injection molding among others produce parts which may have flash (extraneous material) that must be removed after the part is molded. Removing this flash by hand is a difficult and physically demanding task. The repetitive nature of the task can lead to repetitive motion injuries such as carpel tunnel syndrome.
Efforts to automate this task using CNC machine tools have encountered several difficulties. The flash must be trimmed to blend with the surrounding part surfaces; however, it is the nature of many plastic parts that the part size and shape may vary from part to part. Therefore it is not possible to create a CNC program to properly trim the part with the precision often required.
An attempted solution to this problem was the development of a "floating head" which was intended to allow the machining head to float and be guided by a bearing on the tool which rolled on the part guiding the trim operation. This approach has certain limitations. The size of the mechanism prevents its use on many parts and makes it difficult to mount on many CNC machines, especially 5 axis heads intended to machine three dimensional parts. Also, it may be necessary to perform both conventional machining, which requires a rigid head, and de-flashing, which requires a floating head on the same part.
SUMMARY OF THE INVENTION
The present invention solves the problem set forth above by providing a unique worktable on which a workpiece (e.g. plastic part) is positioned for cutting, trimming, etc. CNC machine tools usually operate in one of two modes: (a) the head of the machine tool remains in a fixed position while the workpiece is manipulated about it; or (b) the workpiece remains in a fixed position on a stationary table and the head of the machine tool is moved about the workpiece in a preprogrammed manner.
The present invention utilizes the second mode of operation. However, as discussed above, plastic parts are often inconsistent in exact size and shape. Therefore, when the cutting tool (e.g. a router bit) moves about the part in a preprogrammed pattern, which is based upon the ideal or nominal part size, it may perform inexact cutting on parts fixed to the table that are inexact in shape.
The present invention overcomes the problems associated with removing flash from varying shaped parts by allowing the part to move somewhat under the influence of the cutting tool, which always traverses a fixed pattern. The cutting tool is equipped with a ball bearing guide that allows the tool to follow along the plastic part so that the tool can trim the flash even with the surface of the part. However, to accommodate variations in the part size, the part is allowed to move when the tool encounters a shape that varies from its preprogrammed pattern. This is in contrast to prior approaches in which the cutting tool moves from its preprogrammed pattern to accommodate variations in part shapes.
To permit the plastic part to move, the present invention utilizes a novel table on which the workpiece (part) is fixed. The working surface of the table is allowed to "float" in relation to bottom of the table, which is fixed in relation to the ground and thus in relation to the CNC machine. The unique table of the present invention consists of two flat metal plates, one located on top of the other. Compressed air is forced through a hole in the bottom plate which creates a cushion of air allowing the top surface to slide on the bottom surface with very little friction. A set of guides is attached to the bottom surface to position the top "floating" surface. Each guide includes a long pivot arm that is pivotally mounted to the edge of the bottom surface. The top edge of the pivot arm contacts, but is not connected to the edge of the top surface. The other end of the pivot arm is pivotally connected to a combination compression spring and shock absorber.
A guide with pivot arm is located on all four edges of the table so that when all four shock absorber/compression spring units are fully extended, the top floating surface is centered on the bottom surface. A fixture to hold the plastic part is mounted to the top surface. A router bit equipped with a ball bearing guide is used for trimming. The ball bearing guide moves along the plastic part allowing the router bit to trim the flash even with the surface of the part.
To trim a part using a CNC machine tool, the router with ball bearing guide is programmed to contact the plastic part and to push to some degree the plastic part, fixture and table from its center position. The guides with pivot arms keep the top table from rotational motion but allow it to translate. The spring in the spring/shock absorber unit pushes the table, fixture and part against the router bit and ball bearing guide. The shock absorber dampens transient mechanical motion allowing a smooth cutting action. The spring keeps the part against the router bit and ball bearing guide even if there are variations in the part.
Other features and advantages of the present invention will become apparent to those having ordinary skill in the art to which the present invention pertains from the following detailed description taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of the present invention utilized in a CNC system.
FIG. 2 is a detailed view of the cutting tool utilized in the present invention in position relative to a plastic part from which flash is trimmed.
FIGS. 3A-3C illustrate the relative positions of operative parts of the present position during an example operation.
FIG. 4 is a detailed view of the table guide of the present invention.
DETAILED DESCRIPTION
The method and apparatus of the present invention are best suited in a system shown generally in FIG. 1, which includes a computer numerical control (CNC) controller 10, a cutting or milling machine 12 with cutting tool 14 for performing work operations on a workpiece 16. Workpiece 16 is held stationary on working surface 32 of table 22 by fixture 20. As is conventional, CNC controller 10 is programmed to control cutting machine 12 to move cutting tool 14 through a prescribed path or pattern. In the present invention, the cutting tool 14, as best shown in FIG. 2, includes a router bit 24 equipped with a ball bearing guide 26. In operation, ball bearing guide 26 moves along the surface of plastic part 16. Moving in accordance with its preprogrammed pattern, ball bearing guide 26 will apply some transverse force against plastic part 16. This allows the router bit 24 to trim the flash 28 even with surface 30 of part 16.
In the present invention, plastic part 16, fixture 20 and working surface 32 of table 22 are capable of transverse movement in response to force from cutting tool 14, specifically ball bearing guide 26. FIG. 3 illustrates table 22 of the present invention which permits transverse movement of the plastic part. Table 22 includes a movable ("floating") upper surface 32 and a lower fixed surface 34. Surfaces 32 and 34 are preferably metal plates. Compressed air from a source, illustrated generally as 36 in FIG. 3A, is delivered through an appropriate conduit 38 with nozzle 39 and through a hole 40 in lower surface or plate 34 to create a cushion of air between plates 32 and 34. This permits plate 32 to slide on plate 34 with very little friction. Alternative forms of slidable support for plate 32 include low friction ball bearings or roller bars.
In a preferred embodiment, table 22 includes four guides 42 located on the perimeter of upper plate 32, preferably each being centrally located on each of the four sides of plate 32. FIG. 3 illustrates left and right guides 42L and 42R respectively and a portion of front guide 42F. Rear guide 42R (not shown) is located adjacent plate 32 on the side opposite to front guide 42F.
Referring to FIGS. 3 and 4, each guide 42 includes a pivot arm 44 that is centrally and pivotally mounted to bottom plate 34 via central support 46. Central support 46 is attached to bottom plate 34 by screws or bolts 48 (FIG. 3) and includes a pivot rod 50 (FIG. 4). Pivot rod 50 extends through an opening in pivot arm 44 along its length and pivotally supports arm 44. Pivot arm 44 includes an upper end 54 with head 56 for contact with an outside edge of movable upper plate 32. Lower end 58 of pivot arm 44 is pivotally connected to an actuator 60. Lower end 58 comprises a clevis 58 (FIG. 3) that straddles pivot block 62 of actuator 60. A second lower pivot rod 64 is connected between the two legs of clevis 58 and extends through pivot block 62 to provide pivotal support for arm 44.
Actuator 60 is connected to the bottom of lower plate 34 through angle mount 52, which is secured to plate 34 by screws or bolts. Connected to angle mount 52 is clevis 66 from which actuator 60 is suspended. Actuator 60 is a combination compression spring and shock absorber. The compression spring portion, illustrated as 68 as in FIG. 4 resiliently urges piston rod 70 out of actuator 60. As will be readily appreciated, this force will cause pivot arm 44 to pivot about rod 50 of center support 46 and urge head 56 against an edge of movable upper plate 32. The four actuators 60 are mounted such that when their respective piston rods 70 are fully extended, they bias movable upper plate 32 into a central position on fixed lower plate 34. This operative position is shown in FIG. 3A.
During a deflashing operation, the router bit 24 with ball bearing guide 26 moves along and pushes against plastic part 16. This in turn causes the fixture 20 and movable upper plate 32 to also be pushed off of center with lower fixed plate 34. The spring 68 of actuator 60 through the respective pivot arm 44 oppositely positioned from router bit 24 will oppose but not completely negate the pushing force of the ball bearing guide. In this manner the action of a respective spring maintains the part against the ball bearing guide of the router bit even if there are variations from normal in the part size and shape. Each of four actuators 60 and respective pivot arms 44 on each of the four sides of movable upper plate 32 permit limited translational movement while preventing rotational movement.
FIGS. 3A, 3B and 3C illustrate the relative positions of upper plate 32 and actuators 60 during an example operation. Figure 3A illustrates the initial position with piston rods 70 fully extended and upper plate 32 centered on lower plate 34. FIG. 3B illustrates an operating position in which the router bit and ball bearing guide is traversing a side of the plastic part toward guide 42R and thus pushing the part and plate 32 in the direction of guide 42L. In such position, piston rod 70 associated with guide 42L will be partially retracted. FIG. 3C illustrates an operating position similar to FIG. 3B but wherein the ball bearing guide contacts a further outwardly extending surface of the part (e.g. a surface extending beyond the expected norm toward guide 42R), thus causing the part and plate 32 to move further in the direction of guide 42L. In such position, piston rod 70 associated with guide 42L is fully retracted and pivot arm 44 prevents any further movement of plate 32 in the direction of guide 42L. In the operative examples of FIGS. 3B and 3C, guide 42R will remain in the same position as illustrated in FIG. 3A, i.e. with piston rod 70 fully extended. The shock absorber function of each actuator 60 is to dampen spring oscillations and provide for a smooth trimming operation.
From the foregoing detailed description, it will be evident that there are a number of changes, adaptations and modifications of the present invention which come within the province of those persons having ordinary skill in the art to which the aforementioned invention pertains. However, it is intended that all such variations not departing from the spirit of the invention be considered as within the scope thereof as limited solely by the appended claims. | 4y
|
BACKGROUND OF THE INVENTION
As used in the present invention description, the term insert refers to those advertising or informational newspaper inserts which are added to a daily or Sunday newspaper.
As is known in the industry, such inserts are commonly preprinted in a separate printing run days or weeks ahead of the normal daily newspaper. Since the daily newspaper itself leaves the printing presses in a folded condition, it then becomes necessary to place the advertising inserts inside the folded newspapers.
Such melding of the advertising insert with the folded newspaper must be accomplished rapidly due to the exigencies of daily newspaper delivery.
Accordingly, specialized insert machines have been developed in the art to accomplish the above. Typically, in a mechanized operation, the advertising inserts are loaded into a hopper of an insert machine which automatically places the inserts into the appropriate position in the printed daily newspaper.
It has been known in the industry for a number of years to utilize sectioned carts to transport the advertising inserts to the hopper of an insert machine. For example, the use of carts having four different insert carrying sections have been used in the art, such carts in past years typically being made of wood.
Loading carts of this variety have become known as insert carts, and such are the subject of the present invention.
The four-sectioned structure of the wooden insert carts has been utilized to accomplish a more rapid loading of the advertising inserts into the hopper of an insert machine. Of course, such wooden carts had rolling casters mounted therebelow for transport of the advertising inserts from one place in the printing plant to the desired hopper location.
In more recent years, the insert carts have been fashioned of metal and ways have been developed to facilitate the more rapid loading and unloading of such insert carts.
An example of a prior art metal insert cart is shown in U.S. Pat. No. 4,302,025 to Waddell et al. As shown in FIG. 1 of the U.S. Pat. No. 4,302,025 to Waddell, metal insert carts of today's usage continue to utilize the four-sectioned structure known in the older prior art wooden insert cart designs.
The Waddell '025 structure also incorporated a rod 62 and pad 54 braking structure, shown in FIG. 2 of the patent, which operates as follows: an exterior handle 84 is moved from a horizontal position by the operator to the vertical position shown in FIG. 2. Such movement of the handle 84 serves to force rod 62 and attached lower pad 54 downward into a braking position whereby the loaded insert cart can be rotated about a fixed point on casters 16 so that a workman can easily unload the four sections of the cart and appropriately place the advertising inserts into the hopper of an insert machine.
It has been realized in the safety engineering arts that structures such as those of the Waddell patent may pose a serious cart operator safety hazard in practical use.
For example, the braking handle 84 of the Waddell system may be operated by one hand only of the cart using operator, leaving the other hand free to be potentially caught under the section shown as 88 in FIG. 2 of the '025 patent. Such potential for operator injury has been generally recognized by national safety engineering groups and the U.S. Occupational Safety and Health Administration (OSHA) in promulgating standards which recommend that a manually actuated machine be designed such that both hands of a workman are required in the activation step to eliminate the possibility for crushing or severing injury to a free hand which may be placed in the work area.
Other potentially dangerous aspects of configurations such as that of Waddell have been noted by those of skill in the art. For example, in the brake-on position of Waddell, the relatively sharp handle 84 is in a vertical position which may cause injury to a workman falling or slipping in the area of the insert cart. Further, as the handle 84 is turned up or down by the workman, it passes through region 74 and tends to very rapidly accelerate or snap into the up or down position. Such rapid handle acceleration also poses a risk of injury to the using workman.
In an age of profuse product liability litigation, it is of course recognized that the elimination of safety hazards wherever possible is of tantamount importance in the arts. Such is especially true where, as here, the working tool is intended for use by unskilled or semi-skilled personnel.
OBJECTS OF THE INVENTION
Accordingly, it is an object of the present invention to provide an insert cart having a brake to allow rotation of the cart to facilitate the rapid unloading of the cart as required in the newspaper industry.
It is a further object of the invention to provide a more positive braking function and added reliability and durability for an insert cart than has heretofore been utilized in the arts.
It is also an important object of the present invention to provide an insert cart having features incorporated into the combination structure and the cart braking assembly which result in maximizing worker safety and which minimize the potential for worker injury in using the device.
Further objects and advantages of the present invention will become apparent as the following description proceeds, and the features of novelty characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.
BRIEF SUMMARY OF THE INVENTION
The invention utilizes an upper brake operating handle which normally requires the use of both hands by an operating workman. An elongated rod extends downwardly from the handle to serve as a floor-contacting brake mechanism. A pin and slot camming arrangement is positioned in an area of the device where it does not pose a threat of injury to work personnel.
The pin referred to is securely affixed to the elongated braking rod in a manner to provide for a more positive braking action and less possibility of pin breakage.
The camming slot referred to is part of a subassembly which has an upper plate thereon serving to confine all potentially hazardous areas of the device from the cart operator.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an enlarged side elevational view of the upper portion of the insert cart and braking assembly of the invention.
FIG. 2 is a reduced side elevational view of the lower portion of the insert cart showing the clamping rod 10 in the brake-off position.
FIG. 3 is an elevational view of the clamping rod subassembly showing the pivot pin and spring collar attached thereto.
FIG. 4 is a top plan view of the overall device.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings in which like numerals refer to like component parts, FIG. 1 shows in side elevational view the important operational components of the insert cart and braking assembly of the present invention.
A one piece clamping rod 10 has a cross-handle welded to the top thereof as indicated at 11a and 11b. Clamping rod 10 extends downwardly through a clamping cam subassembly 20 and, at its lower end shown in FIG. 2, rod 10 extends through an opening 61 in the insert cart base 60. As shown, the rod 10 at its lower portion is not in contact with floor 5 thus being in the brake-off position.
In the basic operation of the device, upper portions 11a and 11b are grasped by the operator and turned counterclockwise. Rod 10 is driven downward by the action of floating compression spring 50 on the spring collar 53 and the lower portion of rod 10 thus contacts floor 5 where the insert cart is braked from further translational movement. It is to be understood that in the brake-on position, the cart can pivot about the point created by rod 10 and ground 5 by way of conventional roller casters 62.
As shown in FIG. 3, the clamping rod 10 has two components rigidly attached thereto. The first attached component is a pivot pin 15 which passes through clamping rod 10 and is attached rigidly to it by means of set screws indicated at 16. The second component rigidly attached to the clamping rod 10 is a spring collar 53 mounted by means of pin 54. The purpose and function of both components will be more fully described hereinbelow.
Referring again to FIG. 1, it can be understood that, as handles 11a and 11b are grasped and turned counterclockwise, pivot pin 15 follows the downwardly angled path formed by slot 30 which has been formed in the clamping cam assembly 20. It is to be understood that a groove 32 and lip 33 construction is formed on the upper portion of slot 30 so that, once the pin 15 slides over lip 33, the compression spring 50 strongly urges collar 53 and therefore the attached rod 10 downwardly into a braking position with floor 5.
Pin 15 thus follows the path of slot 30 until it contacts a lower vertical wall 31 of the slot 30 where the pin 15 and its attached rod 10 are stopped from further movement.
It is to be understood that slot 30 extends for a distance of approximately ninety degrees around the circumference of clamping cam 20. It is contemplated that, in practice of the invention, the slope of slot 30 would be in the range of 25-55 degrees as measured from a horizontal plane.
It should also be understood that a second slot 35 would be formed on the other side of clamping cam 20. This second slot is indicated by dashed lines in FIG. 1 and would be identical to slot 30 and receive the second end of pivot pin 15, sbown in FIG. 3, thus providing a more positive and durable clamping cam action.
In viewing FIG. 1, it can be seen that the clamping cam subassembly 20 has three sections or zones as a part thereof. A middle zone 22 has the slots 30 and 35 formed therein, said slots serving to guide the ends of pin 15 along the desired path and thereby permit compression spring 50 to force rod 10 into its downward or brake-on position. A lower reduced area zone 23 of the clamping cam subassembly 20 serves as a guide for rod 10 during its upward and downward operating motions. Zone 23 by its reduced area also serves as an abutting surface for spring 50.
An upper zone 21 serves as a mounting section for the clamping cam cover plate 36. In practice of the invention, cover plate 36 is welded to upper zone 21.
The clamping cam cover plate 36 is of importance to the overall invention since it serves in part to isolate the camming area from the operator of the cart, thus serving to reduce the likelihood of injury.
Cover plate 36 has an aperture 38 in a central portion thereof to allow passage and upward and downward motion of rod 10. Cover plate 36 also has four apertures 37 at its corners whereby the cover plate and the entire clamping cam subassembly 20 may be bolted or otherwise fixedly attached to the upper ends of four vertical sectional dividers 40, said dividers 40 serving to provide four compartments for loading of newspaper inserts into the cart. Two of the vertical dividers 40 are shown schematically in FIG. 1 and the location of all four vertical dividers is shown in the top plan view of FIG. 4. The four apertures 37 are also shown in the plan view of FIG. 4.
As can be seen in the views of FIGS. 1 and 4, the vertical dividers 40 in combination with the bolted clamping cam cover plate 36 serve to completely isolate the clamping cam subassembly 20 and the moving pin 15 therein.
Such isolation of the camming assembly results in a system which is much less likely to result in injury to a person utilizing the cart for the simple reason that the operator's hands, hair or loose clothing cannot be caught in the camming mechanism.
To recapitulate the operation of the insert cart of the present invention, a cart loaded with newspaper inserts would be pushed to the desired work area with the clamping rod 10 in the brake-off position shown in FIGS. 1 and 2 i.e. pin 15 is resting in the groove 32 formed in slot 30 and also in slot 35. Upon reaching the desired point, handles 11a and 11b are grasped by the workman and turned counterclockwise thus slipping the pivot pin 15 ends over lips 33. Spring 50, which is always under compression, then acts to force rod 10 downward into its floor 5 contacting brake-on position.
As rod 10 is forced downward, ends of pin 15 move downwardly along slots 30 and 35 until said pin ends contact the lower slot walls as indicated at numeral 31, thus stopping the downward motion of rod 10.
In the brake-on position, with rod 10 in contact with floor 5, the cart is braked from translational movement (for example, a rubber tip may be used on the end of rod 10) while still allowing cart rotational movement via casters 62 as desired by the person unloading the insert cart.
From the foregoing, it can be realized by those of skill in the art that a reliable and durable, positive acting combined insert cart and brake assembly has been set forth by the applicant herein. The overall system also incorporates important safety features which greatly reduce the possibilities of injury and resultant products liability suits for users and manufactures of the device.
While there has been illustrated and described what is at present considered to be a preferred embodiment of the present invention, it will be appreciated that numerous changes and modifications are likely to occur to those skilled in the art, and it is intended in the appended claims to cover all those changes and modifications which fall within the true spirit and scope of the present invention. | 4y
|
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
This invention was made with Government support under Agreement No. N66001-97-1-8908 awarded by DARPA. The Government has certain rights in the invention.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to MOS devices and their fabrication. More particularly, this invention relates to MOS devices that employ metal gate electrodes over ultra-thin gate dielectrics, and to a process for passivating the semiconductor-dielectric interface of such devices by diffusing atomic hydrogen through the metal gate electrode.
2. Description of the Prior Art
With the continued scaling of MOSFET (metal-oxide-semiconductor field effect transistors) gate lengths to the tens of nanometers regime, metal gate electrodes have been studied extensively as a substitute for conventional polysilicon gates to eliminate polysilicon gate depletion and to reduce gate resistance. Preferred materials for metal gate electrodes have been those with a midgap workfunction, i.e., a Fermi level midway between the valence and conduction bands of the semiconductor material (e.g., silicon), in order to implement CMOS with slightly doped and undoped channels. For devices with gate lengths well below 0.1 micrometer, a gate material with a midgap workfunction is desirable to permit the use of lightly-doped channels in fully depleted, ultra-thin CMOS-SOI (metal-oxide-semiconductor, silicon-on-insulator) devices. This approach minimizes threshold voltage variations that may occur from device to device as a result of fluctuations in local dopant concentration and film thickness, and increases the carrier mobility from reduced impurity scattering and normal electric fields. Tungsten is one of the most promising candidates for metal gate CMOS technology because of its low resistivity and near ideal midgap workfunction. In addition, the refractivity of tungsten permits process integration in the very early stages of the standard CMOS technology. For deposition on ultra-thin dielectrics, chemical vapor deposition (CVD) has been successfully employed as the method for producing thin, low-resistivity tungsten gate electrodes. Although there have been studies on the performance of tungsten gate MOSFET's, the CVD tungsten gate MOS interface has not been examined in great detail.
For all high performance MOS devices, the passivation of the semiconductor-dielectric interface is important. In the art it is known that, for a MOS capacitor comprising a silicon substrate, silicon dioxide dielectric film and an aluminum electrode, heating the MOS structure to a temperature of about 350° C. to about 500° C. in either a nitrogen or hydrogen environment is able to reduce the Si/SiO 2 interface state (trap) density (D ito ) to very low levels, e.g., less than 5×10 10 /cm 2 -eV. The effectiveness of aluminum in this process has been attributed to atomic hydrogen produced by the reaction of aluminum with water vapor adsorbed at the Al-SiO 2 interface. In theory, atomic hydrogen passivates the Si/SiO 2 interface by tying up dangling bonds. In contrast, interface states in polysilicon gate MOS devices can be passivated with forming gas anneal (FGA) treatments using 5 to 10% hydrogen and 90 to 95% nitrogen at temperatures of about 400° C. to about 550° C. However, it has been observed that standard FGA treatments provide very little passivation of a Si/SiO 2 interface (e.g., an interface state density below 5×10 11 /cm 2 -eV) when applied to MOS capacitors with 100 nm thick CVD tungsten gate electrodes. One possible explanation is where a high temperature (e.g., about 500° C. or more) hydrogen-free CVD process has been used, which may effectively eliminate any internal source of hydrogen. Another possibility might lie in the low solubility and diffusivity of hydrogen gas in tungsten, such that a tungsten electrode prevents molecular hydrogen within the surrounding atmosphere from reaching the Si/SiO 2 interface during annealing. In any event, the inability to passivate the semiconductor-dielectric interface through a tungsten layer is a potential barrier to the practical use of MOS devices (including capacitors and FET's) with thick tungsten gate electrodes.
From the above, it can be seen that it would be desirable if a process were available to reduce the semiconductor-dielectric (Si/SiO 2 ) interface state density of a MOS device with a thick tungsten gate electrode, particularly if such a process were capable of reducing the interface state density to very low levels (for example, below 5×10 10 /cm 2 -eV).
BRIEF SUMMARY OF THE INVENTION
The present invention provides a process for passivating the semiconductor-dielectric interface of a MOS structure to reduce the interface state density to a very low level. More particularly, the invention is directed to MOS structures that employ a metal layer, and particularly a tungsten layer, that in the past has prevented passivation of an underlying semiconductor-dielectric interface to an extent sufficient to yield an interface state density of less than 5×10 10 /cm 2 -eV.
The invention generally entails fabricating a MOS device by forming a layer of a suitable dielectric material (such as silicon dioxide) on a silicon-containing semiconductor substrate, such that a semiconductor-dielectric interface is formed between the substrate and the dielectric layer. A metal layer that is pervious to atomic hydrogen is then formed on the dielectric layer to yield a MOS structure. The MOS structure is then exposed to atomic hydrogen in a manner that diffuses the atomic hydrogen through the metal layer and into the interface. The invention encompasses several approaches for introducing atomic hydrogen into the semiconductor-dielectric interface. According to one technique, an aluminum layer is formed on the metal layer in the presence of hydrogen to form a metal stack in which atomic hydrogen is stored between the metal and aluminum layers. The MOS structure is then annealed at a temperature sufficient to cause the atomic hydrogen to diffuse through the metal layer and into the interface. In a second technique, atomic hydrogen is diffused through the metal layer and into the interface by subjecting the metal layer to hydrogen plasma. Another technique is to implant atomic hydrogen into the metal layer, and then anneal the MOS structure at a temperature sufficient to cause the atomic hydrogen to diffuse through the metal layer and into the interface.
According to the invention, sufficient atomic hydrogen is diffused into the semiconductor-dielectric interface to passivate the interface, preferably yielding an interface state density of less than 5×10 10 /cm 2 -eV. The process of this invention is particularly beneficial to MOSFET devices that employ metal gates, and particularly tungsten gates, over an ultra-thin gate dielectric, e.g., silicon dioxide at thicknesses of 5 nm or less. Of particular significance to the invention are tungsten layers that are deposited to thicknesses of greater than 20 nm. The present invention determined that such tungsten gates are substantially impervious to molecular hydrogen, thereby preventing the passivation of an underlying semiconductor-dielectric interface by methods employed by the prior art, yet pervious to atomic hydrogen so as to allow passivation in accordance with the techniques of this invention. Consequently, the present invention makes possible MOSFET's with short gate lengths (e.g., on the order of 0.01 micrometer or less) and which make use of tungsten as the gate electrode material, such that the electrode has a midgap workfunction to permit the use of lightly-doped channels in fully depleted, ultra-thin CMOS-SOI devices.
Other objects and advantages of this invention will be better appreciated from the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 schematically represents a MOSFET device of a type that can be formed in accordance with the present invention.
FIGS. 2 and 3 are plots that graphically compare C-V data collected from MOS devices passivated in accordance with, respectively, the prior art and in accordance with a first embodiment of this invention.
FIG. 4 is a plot of C-V data collected from MOS devices passivated by hydrogen implantation in accordance with a second embodiment of this invention.
FIGS. 5 and 6 are plots of C-V data collected from MOS devices passivated by hydrogen plasma in accordance with a third embodiment of this invention.
FIG. 7 is a plot of C-V data collected from MOS devices with very thin tungsten layers and passivated in accordance with the prior art.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 represents a MOSFET device 10 that includes a semiconductor substrate 12 , a pair of wells 14 that serve as the source and drain of the device 10 , a gate dielectric 16 overlying a channel 20 between the source and drain wells 14 , and a gate electrode 18 overlying the gate dielectric 16 . While the device 10 represented in FIG. 1 will be used to illustrate and explain the present invention, those skilled in the art will appreciate that the invention is applicable to various other MOS devices having structures that differ from that represented in FIG. 1 .
In accordance with conventional practice, the substrate 12 may be formed of various semiconductor materials, though silicon is preferred and the focus of the present invention. Examples of other suitable semiconductor materials include Ge and SiGe alloys, and semiconductor materials such as InGaAs with deposited oxide layers. Silicon dioxide is a preferred material for the gate dielectric 16 , though it is foreseeable that other dielectric materials could be used, such as high-k dielectrics including Y 2 O 3 , La 2 O 3 , Al 2 O 3 , ZnO 2 , HfO 2 , and mixtures thereof. The substrate 12 and source and drain wells 14 are appropriately doped to be n or p-type as necessary for the particular device 10 , and in accordance with known practices. Finally, the gate electrode 18 is formed by a metal layer. Though not necessary for practicing this invention, in a preferred embodiment the MOSFET device 10 is a fully-depleted, ultra-thin CMOS-SOI device, and scaled to have a gate length of less than 0.1 micrometer, more preferably about ten nanometers or less. Furthermore, the metal of the gate electrode 18 preferably has a midgap workfunction to permit the use of an undoped or lightly-doped channel 20 , e.g., a doping concentration of not more than about 10 17 cm −2 . For this purpose, a preferred material for the gate electrode 18 is tungsten, though other suitable gate electrode materials include tungsten and cobalt silicides and tantalum nitride. However, the present invention is generally applicable to gate electrodes formed of essentially any metal that renders the electrode 18 impermeable to molecular hydrogen. Finally, the gate dielectric 16 is preferably ultra-thin, which as used herein refers to thicknesses of about 5 nm or less for a silicon dioxide gate dielectric, and thicknesses of about 20 nm or less for other gate dielectric materials. While the teachings of the invention are particularly well suited for the device 10 as it has been described above, those skilled in the art will appreciate that the teachings of this invention are applicable to other MOS devices formed with other materials.
The present invention is directed to passivating the interface between the semiconductor substrate 12 (at the channel 20 ) and the gate dielectric 16 , whereby the semiconductor-dielectric interface state (trap) density (D ito ) is reduced to a very low level, preferably less than 5×10 10 /cm 2 -eV. In the past, passivation of an Si/SiO 2 interface beneath an aluminum gate electrode has been performed by forming gas annealing (FGA) treatments, typically using a mixture of about 5 to 10% hydrogen and about 90 to 95% nitrogen and annealing temperatures of about 250° C. to about 450° C. It is believed that atomic hydrogen is produced during FGA by the reaction of aluminum with water vapor adsorbed at the Al-SiO 2 interface. However, similar FGA treatments of MOS devices with tungsten electrodes of comparable thickness have not resulted in suitable passivation of the Si/SiO 2 interface.
In an investigation leading to this invention, tungsten gate MOS capacitors were processed using FGA treatments to evaluate the ability of FGA to passivate a semiconductor-dielectric interface beneath a tungsten layer. Tungsten was deposited by chemical vapor deposition (CVD) performed at a process temperature of about 680° C. and using W(CO) 6 as the source material, preferably in accordance with the process disclosed in U.S. Pat. No. 5,789,312 to Buchanan et al., which is incorporated herein by reference. Tungsten was deposited to a thickness of about 100 nm directly on a thermally-grown silicon dioxide layer formed on N-type silicon test wafers (resistivities of about 1 to 2 ohm-cm). The silicon dioxide layers were 4 or 20 nm in thickness, the former being termed “ultra-thin” as used herein. For this investigation, the MOS structure was either defined by conventional photolithography, or defined with a hard etch mask formed by shadow-evaporated aluminum, in which a layer of aluminum remained on the upper surface of the tungsten layer to form an aluminum-tungsten electrode stack. Following fabrication, FGA (5-10% H 2 /90-95% N 2 ) was performed on each specimen at a temperature of about 350° C. for a duration of about thirty minutes.
A combination of quasi-static (45 mV/sec) and high frequency (10 KHz) capacitance-voltage (C-V) curves were then obtained through measurements to extract the interface state density using the well-known high-low method, disclosed in M. Kuhn, Solid-State Electronics, Volume 13, pp. 873 (1970). The results for both sets of specimens are represented in FIGS. 2 and 3, which evidence that the passivation of the MOS structures was completely different. In FIG. 3, those specimens with the aluminum-tungsten stack can be seen to be very well passivated, exhibiting interface state densities (D ito ) in the low 10 10 /cm 2 -eV range. In contrast, FIG. 2 evidences that interface state densities of the MOS structures without the aluminum layer were only somewhat passivated after the same FGA treatment, exhibiting interface state densities in the mid-10 11 /cm 2 -eV range, i.e., very near the interface state density exhibited in the as-deposited condition. The latter results evidenced that a tungsten layer having a thickness of about 100 nm is substantially impervious to molecular hydrogen. Subsequent FGA's performed on the same specimens in the same atmosphere at higher temperatures (such as about 550° C.) were not effective in reducing the interface state density. Instead, an increase in interface state density was actually observed. Further attempts to passivate specimens without an aluminum layer by annealing in atmospheres containing nitrogen, oxygen and water vapor, both together and separately, also failed to substantially passivate their Si/SiO 2 interfaces.
FGA treatments were then performed on additional specimens formed to have an aluminum-tungsten electrode stack by annealing in an inert ambient, such as nitrogen. These treatments were carried out at a temperature of about 350° C. for a duration of about thirty minutes, with the result that excellent passivation was again achieved (e.g., interface state densities of about 3×10 11 /cm 2 -eV). These results strongly suggested that passivating elements were already present in the aluminumtungsten electrode stack, and that these elements are able to diffuse through a 100 nm-thick layer of tungsten and into an underlying Si/SiO 2 interface. Since aluminum is known to be a source of atomic hydrogen by reacting with a monolayer of water vapor adsorbed on surfaces of a MOS structure, it was concluded that the passivating element in each of the specimens equipped with an aluminum-tungsten electrode stack was atomic hydrogen. It was further concluded that atomic hydrogen was somehow stored between the aluminum and tungsten layers of the stack, and that the MOS structure was annealed at a temperature sufficient to cause the atomic hydrogen to diffuse through the tungsten layer and into the Si/SiO 2 interface. Suitable temperatures for this purpose are believed to be in the range of about 250° C. to about 400° C., though lower and higher temperatures might also yield acceptable results.
On the premise that atomic hydrogen was the passivating element, two additional tests were devised to evaluate MOS structures with tungsten electrodes, but with atomic hydrogen being made available through other sources, namely, implanted hydrogen and hydrogen plasma. In a first of these additional investigations, three samples with tungsten gate capacitors were provided with atomic hydrogen by ion implantation. The capacitors were MOS structures identical to those defined by conventional photolithography in the previous investigation (i.e., 100 nm CVD tungsten without an aluminum overlayer). Two different implant energies were selected to set the implant ranges: 10 KeV with range in tungsten of 535A and straggle of 300A, and 5 KeV with range in tungsten of 300A and straggle of 156A. Implant range and straggle were determined using implantation simulation software available under the name TRIM from International Business Machines. In addition, two different doses (1×10 13 /cm 2 and 1×10 14 /cm 2 ) were used for the 5 KeV samples. The quasi-static and high frequency C-V characteristics for each sample measured as-implanted were severely stretched out for all samples, i.e., characterized by the lack of a sharp and deep drop in the capacitance value, indicative of a very high interface state density. The heavier-dose, deep-implant specimen particularly exhibited a very high interface state density, likely due to implant damage. Following a post metal anneal (PMA) performed at about 350° C.in nitrogen for about 30 minutes, the interface state densities of the specimens were reduced, as evidenced in FIG. 4 . The interface state density (D ito ) of the sample implanted at 5 KeV with a dose level of 1×10 14 /cm 2 , was lowered to about 1×10 11 /cm 2 -eV.
This experiment clearly demonstrated that atomic hydrogen can act as the passivating species. It was theorized that interface state density could be further lowered if the implant energy and dose were optimized. Ideally, implant energy and dose should be chosen so as not to implant atomic hydrogen directly into the dielectric layer and the surrounding semiconductor substrate. On this basis, it is believed that suitable atomic hydrogen dose levels are in the range of about 2×10 12 /cm 2 to about 2×10 14 /cm 2 . A suitable temperature range for the anneal following implant is believed to be about 300° C. to about 550° C., though lower and higher temperatures might also yield acceptable results.
In the second test, atomic hydrogen was generated by a treatment with hydrogen plasma. Samples were again tungsten electrode MOS capacitors identical to those of the implantation investigation, i.e., 100 nm CVD tungsten defined by conventional photolithography and without an aluminum layer. The plasma was created using a single frequency microwave cavity in accordance with Cartier et al., Appl. Phys. Lett., Volume 63, No. 11, pp. 1510 (1993), and brought directly to the samples in a vacuum chamber. In a first procedure, it was shown that a room temperature hydrogen plasma treatment plus a post anneal at 350° C. was not sufficient to introduce atomic hydrogen into the Si/SiO 2 interface of the MOS capacitors. In another procedure, a hydrogen plasma treatment was conducted with samples maintained at about 350° C., whereby the efficiency of hydrogen introduction to the Si/SiO 2 interface was greatly improved, as evidenced by the interface state density being reduced to about 3.5×10 10 /cm 2 -eV. However, further post anneals at higher temperatures, such as 400° C., was found to deteriorate the passivation, as indicated in FIG. 5 . Further plasma treatments were then performed at plasma anneal temperatures of 300° C. and 350° C., and hydrogen flow pressures of 100 and 200 mTorr. C-V data represented in FIG. 6 indicates that the quality of passivation was very sensitive to lower treatment temperatures (300° C.) and lower flow pressures (100 mTorr). The best passivation was produced with hydrogen plasma treatments conducted with a hydrogen flow pressure of about 200 mTorr and a temperature of about 350° C.for a duration of about 10 minutes. However, it is believed that suitable results could be obtained with plasma treatment temperatures between 250° C. and 400° C., and with a hydrogen flow pressure of about 10 mTorr to about 1000 mTorr.
In a final investigation, the ability of molecular hydrogen to diffuse through very thin layers of tungsten was evaluated. This investigation was pursued to determine whether the role of tungsten in preventing passivation performed under conventional FGA conditions is simply as a diffusion barrier to molecular hydrogen. For the investigation, MOS capacitors were prepared identically to those prepared for the previously described investigations, with the exception that the tungsten electrodes had thicknesses of 20 nm. The samples then received either a 30 minute or a 150 minute FGA treatment at about 350° C. The C-V data for two specimens are plotted in FIG. 7, which clearly shows that the Si/SiO 2 interfaces of both samples were passivated, with those samples receiving the longer FGA treatment receiving the better passivation. The interface state density measured on the sample annealed for 150 minutes was reduced to about 9.5×10 10 /cm 2 -eV. In contrast to those earlier samples with a thick (100 nm) tungsten electrode, the improvements in passivation exhibited by these MOS devices when subjected to long and low temperature FGA treatments suggested that the diffusion of molecular hydrogen through a tungsten layer is possible if the tungsten layer is sufficiently thin (e.g., about 20 nm or less).
In summary, the present invention demonstrated that a relatively thick (above 20 nm, e.g., about 100 nm) tungsten electrode prevents passivation of an underlying Si/SiO 2 interface by conventional FGA treatments, because the electrode is impermeable to molecular hydrogen (though relatively thinner (20 nm) tungsten electrodes may allow passivation by conventional FGA). However, passivation is achieved with thick tungsten electrodes if hydrogen is available in atomic form, such as by implantation into the tungsten electrode or from a source of atomic hydrogen such as hydrogen plasma or the aluminum layer of an aluminum-tungsten electrode stack. It is believed that further optimization can be achieved through enhancements to the annealing process and a fuller understanding of the reaction kinetics relating to the complex interplay between the diffusivity of different species of hydrogen and surface reaction rates. Nevertheless, the present invention evidences that passivation of a Si/SiO 2 interface of a MOS device through a tungsten electrode can be achieved.
It is believed that the above investigations suggest that passivation of other semiconductor-dielectric interfaces may be possible through other metal electrodes that are impermeable to molecular hydrogen. Furthermore, while a particular MOS device 10 is represented in FIG. 1, those skilled in the art will appreciate that the invention is applicable to various other MOS devices, including advanced MOS devices with sidewalls that might prevent hydrogen gas diffusion into the semiconductor-dielectric interface. Accordingly, while the invention has been described in terms of a preferred embodiment, it is apparent that other forms could be adopted by one skilled in the art. Therefore, the scope of the invention is to be limited only by the following claims. | 4y
|
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of copending International Application No. PCT/EP2003/014968 filed Dec. 30, 2003 which designates the United States, and claims priority to German application no. 102 61 751.1 filed Dec. 30, 2002 and German application no. 103 10 672.3 filed Mar. 12, 2003.
TECHNICAL FIELD
[0002] The invention concerns a method and device for adjustment of a fuel/air ratio for an internal combustion engine.
BACKGROUND
[0003] A catalyst arranged in the exhaust system of an internal combustion engine is ordinarily used to clean the exhaust of an internal combustion engine. This converts harmful components, like hydrocarbons CH, carbon monoxide CO and oxides of nitrogen NO x essentially to nontoxic gases. It is critical to the so-called degree of conversion of the catalyst that the oxygen content of the exhaust lie within optimal values. For a so-called three-way catalyst these optimal values lie in a narrow range around the value corresponding to a fuel/air mixture of λ=1. In order to be able to maintain this narrow range, it is customary to regulate the fuel/air ratio for an internal combustion engine by means of oxygen sensors arranged in the exhaust system of an internal combustion engine.
[0004] A method for lambda control for internal combustion engine with a downstream catalyst is known from Unexamined Patent Application DE 40 24 212 A1 in which the oxygen fractions of the exhaust of the internal combustion engine are recorded by oxygen sensors upstream and downstream of the catalyst. In stipulated operating ranges a control signal with controllable amplitude is generated by coupling in an outside signal with controllable amplitude. With increasing catalyst aging the amplitude is reduced. The functional state of the catalyst in the exhaust system of the internal combustion engine can be determined with the method by means of lambda regulation and the time for replacement of an aged catalyst determined.
[0005] A method for adjustment of the fuel/air ratio for an internal combustion engine with a downstream catalyst is known from Unexamined Patent Application DE 43 37 793 A1 in which the oxygen fractions in the exhaust of the internal combustion engine are determined by oxygen sensors upstream and downstream of the catalyst. Both sensors influence regulation of the fuel/air ratio. It is initially determined with an amplitude evaluation whether the catalyst has already reached a certain degree of aging. This actual control quantity is issued by the sensor upstream of the catalyst. A switch is then made to frequency evaluation or frequency regulation in which the catalyst yields the actual control quantity downstream of the catalyst. Such evaluations are sensitive per se, but have a relatively strong influence on the operating behavior of the internal combustion engine. This is avoided by only switching to frequency evaluation when the catalyst has already reached a certain state of aging. With increasing operating time the oxygen storage capability of the catalyst declines. The control frequency therefore increases with increasing catalyst aging so that lambda regulation is adjusted to the state of aging of the catalyst. As soon as the determined control frequency downstream of the catalyst is higher than the frequency threshold, aging of the catalyst can be reliably recognized and the catalyst replaced.
SUMMARY
[0006] The object of the invention is to improve the method for adjusting the fuel/air ratio for an internal combustion engine with a downstream catalyst according to the prior art and permit greater dynamics, as well as to devise an apparatus for execution of the method.
[0007] This object can be solved by a method for adjustment of a fuel/air ratio for an internal combustion engine with an associated catalyst, comprising the steps of determining an exhaust composition in an exhaust system of the internal combustion engine by means of sensors, generating a control signal to influence the fuel/air ratio as a function of output signals of at least one of the sensors, and making by means of a characteristic curve of the control signal a switch back and forth between an operating state with oxygen excess and an operating state with oxygen deficiency of the catalyst, wherein a shape of the characteristic curve is adjusted as a function of an oxygen and/or NO x addition and/or desorption capability of the catalyst.
[0008] A course of a transition from operating state to another and/or a course of the characteristic curve within an operating state can be adjusted as a function of oxygen and/or NO x addition and/or desorption capability of the catalyst. The characteristic curve of the control signal can be adjusted as a function of a catalyst temperature. The characteristic curve of the control signal can also be adjusted as a function of the degree of aging of the catalyst. Adjustment of the characteristic curve of the control signal may occur as a function of the operating parameters of an internal combustion engine. The characteristic curve of the control signal can be adjusted unsymmetrically to a stipulated lambda value over a time range that includes at least several periods of the control signal. The characteristic curve of the control signal may be a sawtooth. The subsequent operating states can be adjusted with different residence time of the control signal. The subsequent operating states can be adjusted with different amplitude of the control signal. The characteristic curve of the control signal may be nonlinear at least in a region. The characteristic curve of the control signal may become leaner or richer degressively. The characteristic of the control signal may initially become leaner around a stipulated amount or richer and then is degressively guided in the direction λ=1.00. The characteristic curve of the control signal can be a rectangular curve with different amplitudes and/or residence times in the adjusted operating states. During fuel cutoff in the overrun or idle of the internal combustion engine, the internal combustion engine may be operated more in the rich operating state than in the lean operating state. In a catalyst the control signal may be adjusted so that increased incorporation of oxygen and/or NO x in the catalyst occurs temporarily. In a catalyst after a stipulated operating time the control signal can be adjusted so that a phase with increased lean operation follows a phase with at least two periods with mostly rich operation. Before reaching an operating temperature of the catalyst the characteristic of the control signal may deviate from the characteristic after surpassing the operating temperature. In a catalyst at almost operating temperature, the characteristic curve of the control signal may have a sawtooth trend before reaching a stipulated operating temperature. The catalyst state and/or a state of the sensor upstream and/or downstream of the catalyst can be determined from the control signal.
[0009] The object can also be achieved by a device for adjustment of a fuel/air ratio for an internal combustion engine with an associated catalyst, comprising exhaust composition sensors, a control unit for generating a control signal to influence the fuel/air ratio as a function of output signals of at least one of the sensors, said control signal comprising a characteristic curve for switching back and forth between an operating state with oxygen excess and an operating state with oxygen deficiency of the catalyst, and means for adjusting a form of a characteristic curve as a function of oxygen and/or NO x addition and/or desorption in the catalyst.
[0010] A sensor can be arranged in the exhaust system of the internal combustion engine upstream and downstream of the catalyst. The sensor upstream of catalyst may be a broadband lambda probe with a constant characteristic. The sensor upstream of the catalyst can also be a two-point lambda probe with a transfer characteristic. The sensor downstream of the catalyst may be a two-point lambda probe with a transfer characteristic. The sensor downstream of the catalyst may also be a broadband lambda probe with a constant characteristic. The catalyst can be a three-way catalyst. The catalyst may have a noble metal content of less than 60 g/ft 3 , especially less than 40 g/ft 3 , preferably less than 30 g/ft 3 , optimally less than 20 g/ft 3 , ideally less than 10 g/ft 3 . The catalyst can be an NO x storage catalyst. The catalyst may have a noble metal content of less than 80 g/ft 3 , especially less than 60 g/ft 3 . The internal combustion engine can be a directly injected internal combustion engine capable of layered charging.
[0011] One advantage of the method is that the time trend of the reference value of lambda value of the exhaust upstream of a catalyst connected after the engine is automatically adjusted to the operating states of the catalyst in which conversion is otherwise not optimum. This leads to better utilization of the catalyst and to increased reliability in maintaining emission values.
[0012] Another advantage of the invention is that because of the improved dynamics of the exhaust system in a vehicle in which the device according to the invention was implemented the driving dynamics are approved.
[0013] In addition, the catalyst during its lifetime is brought to favorable operating ranges and operated with high efficiency so that in comparison with ordinarily regulated catalysts noble metals of the catalyst can be saved and/or the catalyst itself reduced in size. This saves cost and resources.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The invention is further explained by means of drawings, in which the figures show:
[0015] FIG. 1 shows a schematic view of a preferred device for execution of the method according to the invention,
[0016] FIG. 2 shows a characteristic curve of a control signal according to the prior art for a three-way catalyst with new catalyst ( 2 a ) and with aged catalyst ( 2 b ),
[0017] FIG. 3 shows a first preferred characteristic curve of a control signal according to the invention with a rectangular trend and different transfer height,
[0018] FIG. 4 shows a second preferred characteristic curve of a control signal according to the invention with a sawtooth trend,
[0019] FIG. 5 shows a third preferred characteristic curve of a control signal according to the invention with a degressive trend,
[0020] FIG. 6 shows a fourth preferred characteristic curve of a control signal according to the invention with also a degressive trend,
[0021] FIG. 7 shows a fifth preferred characteristic curve of a control signal according to the invention with a rectangular trend and progressive runout,
[0022] FIG. 8 shows a sixth preferred characteristic curve of a control signal according to the invention with a rectangular trend and a sawtooth runout.
DETAILED DESCRIPTION
[0023] The invention is particularly suited for catalysts in which the air fraction fed to the internal combustion engine of a fuel/air mixture is adjusted by means of a control signal that is periodically set between a minimal value and a maximal value of the air fraction and switched back and forth between a rich operating state with oxygen deficiency and a lean operating state with oxygen excess.
[0024] The invention is particularly favorable for a three-way catalyst in which oxygen and/or NO x are periodically introduced as oxidizers for the catalyst and desorbed and in which a control signal of a lambda control deviates essentially periodically around the lambda value λ=1. In the lean operating state the oxygen supply in the exhaust is sufficient to oxidize its HC and CO fractions, whereas in the rich operating state NO x fractions in the exhaust as oxidizers oxidize the HC and CO fractions present. A common control strategy for a three-way catalyst proposes a lambda regulation in which a λ probe is exposed to a control signal with constant frequency. In the lean operating state when λ>1 oxygen is introduced to the catalyst 2 ; in the rich operating state with λ<1 this oxygen is consumed for oxidation processes.
[0025] However, it is also possible to use the invention NO x storage catalyst that can be operated at higher lambda values in a three-way catalyst. Aged storage catalysts can also be operated at lower lambda values around λ=1.
[0026] FIG. 1 schematically depicts a preferred device for execution of the method according to the invention. A catalyst 2 is connected in the exhaust 3 after the internal combustion engine 1 . The internal combustion engine 1 is supplied in the usual manner with a fuel/air mixture via means not further shown; air supply preferably occurs via an intake line 7 . In the exhaust line 3 upstream of catalyst 2 a sensor 4 is arranged, which detects the composition of the exhaust. The sensor 4 is preferably an oxygen sensor that detects the oxygen content in the exhaust. The sensor 4 is preferably a broadband lambda probe with a constant control characteristic. Downstream of catalyst 2 another sensor is arranged in the exhaust line 8 that can detect the composition of the exhaust purified in catalyst 2 . Preferably, an oxygen sensor is also used here, with particular preference a two-point lambda probe with a transfer characteristic. The invention also includes devices with more than one downstream catalyst 2 .
[0027] In principle, ordinary lambda probes are suitable with sensors 4 , 5 , like broadband lambda probes, two-point lambda probes or NO x sensor with lambda probe function. As an alternative, a two-point lambda probe can also be used upstream of catalyst 2 and/or a broadband lambda probe downstream of catalyst 2 has sensors 4 , 5 . It is also conceivable to determine the lambda value upstream of catalyst 2 from other types of measured quantities, like injected amount of fuel and drawn in amount of air.
[0028] The oxygen storage capability of catalyst 2 varies over the lifetime of the catalyst 2 . The characteristic of a lambda probe, especially a broadband lambda probe can also vary. This can be compensated by adjusting the frequency of the control signal to the state of aging. Expediently, sensor 4 is exposed to a control signal upstream of catalyst 2 . Sensor 5 downstream of catalyst 2 reports to sensor 4 upstream as soon as breakthrough of rich exhaust or lean exhaust is observed behind catalyst 2 . As long as lean exhaust is available up to sensor 5 downstream of catalyst 2 oxygen breakthrough is recognized via the internal combustion engine 1 . A switch is made to the rich operating state of catalyst 2 until breakthrough of the rich component is observed. A switch is then made back to the lean operating state and the sequence is repeated.
[0029] With increasing age the oxygen storage capability of catalyst 2 diminishes, breakthroughs occur more quickly and the control frequency rises. The lambda control is therefore adapted to the state of aging of catalyst. Such regulation is also referred to as natural frequency regulation.
[0030] The sensors 4 , 5 are connected to a control device 6 that receives their signals and sends them to evaluation. This control device 6 is expediently a component of an ordinary engine control device used for operation of the internal combustion engine 1 . In this control device 6 or via this device operating parameters of the internal combustion engine 1 or a vehicle driven by the internal combustion engine 1 are available. These operating parameters are preferably entered as maps in a corresponding storage medium. Such operating parameters include exhaust temperature upstream of catalyst 2 and/or in catalyst 2 , exhaust temperature downstream of the catalyst, oxygen storage capability of the catalyst 2 , exhaust flow rate, speed of the internal combustion engine 1 , exhaust recirculation rate, position of a camshaft disk, charge movement flap, ignition time and/or charge pressure and the like. Information concerning the operating parameters can be linked to the sensor signals and control therefore conducted as a function of the operating parameters. This is indicated by arrows on control device 6 . Individual operating parameters or different operating parameters can be used in combination with each other.
[0031] Two characteristic curves of an ordinary control signal according to the prior art for a fresh three-way catalyst ( FIG. 2 a ) and an aged three-way catalyst ( 2 b ) are shown in FIG. 2 . The frequency of the control signal of fresh catalyst 2 is distinctly smaller than that of the aged catalyst 2 . However, otherwise the characteristic curve of the control signal is unchanged, since the characteristic curve shape and especially the amplitude are retained.
[0032] Means are provided according to the invention in order to adjust a characteristic curve of the control signal to an actual catalyst state so that a characteristic curve shape of the characteristic curve is adjustable as a function of addition and/or desorption of an oxidizer in catalyst 2 . Such a characteristic curve shape can involve a transition from one operating state to another and/or a trend of the characteristic curve within an operating state of catalyst 2 . The oxidizer can be oxygen or NO x .
[0033] In this case the frequency of the control signal is not followed simply as described in the prior art according to the state of aging of catalyst 2 , but the characteristic curve shape of the characteristic curve is varied by varying the amplitude and/or characteristic curve, especially a flank steepness, switching point and/or trend in an operating state. This adjustment occurs within a control cycle and can vary with increasing operating time of catalyst 2 . The aging behavior of catalyst 2 can be different in rich and lean operating states so that consideration of the different behavior in the two operating states permits more efficient utilization of catalyst 2 via a corresponding adjustment of the control signal as a function of the catalyst state.
[0034] Depending on the state of aging of catalyst 2 the amplitude of the characteristic curve for a rich and lean operating state of the catalyst can be adjusted. This is shown in FIG. 3 . An abrupt control signal with variable amplitude is shown there. In addition, the frequency can also be modulated. By varying the amplitude the system can be accelerated. If the sensor 5 downstream of catalyst 2 establishes a strongly depleted exhaust, it can rapidly be adjusted by stronger enrichment. During over-enrichment it can again be rapidly depleted. The system can therefore reach equilibrium more quickly. The amplitudes for the transition from the rich operating state to the lean operating state and from the lean operating state to the rich operating state can be different.
[0035] Such a control strategy is advantageous for catalysts that have already been used for some time but are still useable over a longer time. Here it is favorable to operate over several control periods more strongly in the rich region, followed by a phase with mostly lean fractions and then again richer fractions and to repeat this. Because of this, increased oxygen storage in the catalyst 2 can be temporarily reached up to the limit of the regeneration capability of catalyst 2 .
[0036] A trend according to FIG. 3 can also be very advantageous between internal combustion engine 1 operated with thrust operated with fuel cutoff in the overrun. In this state, for example on a gradient, no fuel is temporarily fed to the internal combustion engine 1 and the internal combustion engine 1 operates on idle. The exhaust quickly becomes lean. It is favorable here to adjust the control signal so that the internal combustion engine is initially exposed to a fuel/air mixture that over several periods on a time average causes more rich fractions in the exhaust, which is recognizable by the larger amplitudes in the rich operating state. The internal combustion engine 1 is then operated in the lean range. This permits improved dynamics of the system and better driving dynamics of a vehicle operated in this way.
[0037] Over a time region that includes at least several periods of the control signal it can therefore be advantageous to adjust the amplitudes of the characteristic curve of the control signal unsymmetrically to a stipulated lambda value.
[0038] According to a favorable modification of the invention the characteristic curve of the control signal can be sawtooth. This is shown in FIG. 4 . The transitions between a lean operating state to a rich operating state therefore do not occur abruptly, as in the previous example, but the transitions occur more smoothly with a finite slope of the flanks. This trend of the control signal is suitable for catalyst 2 that has not reached or has still not reached the optimum temperature range, especially in the phase with average temperature between a cold start and the sought operating temperature. It was found that the catalyst 2 can reach its optimal temperature range for normal operation more quickly by means of the sawtooth trend of the control signal. The flanks of the control signal can then have different slopes in terms of amount as well as different amplitudes.
[0039] It can prescribed that the characteristic curve of the control signal is a rectangular curve or a different characteristic curve with different amplitude and/or residence time in the corresponding operating states so that the percentage of rich operating states and lean operating states can be adjusted as a function of needs to the actual state of catalyst 2 .
[0040] It is also possible that adjust consecutive operating states with different duration depending on how dependent the addition process and/or desorption processes of the oxidizer in catalyst 2 are on the operating parameters of the internal combustion engine and/or the lifetime of catalyst 2 .
[0041] A control characteristic curve is shown in FIG. 5 that is nonlinear and has a degressive trend. A transition from one operating state to another occurs quickly with a relatively steep flank, whereupon the characteristic curve is slightly rising to a maximum or minimum value. The control signal can also have a progressive trend.
[0042] A control characteristic curve is shown in FIG. 6 that is nonlinear and has a progressive trend. A transition from one operating state occurs initially quickly, but then with a relatively flat flank.
[0043] FIGS. 7 and 8 show examples of control signals, in which different curve forms are superimposed. The transitions between the operating states are abrupt but in the operating state the lean and/or fat fractions in the exhaust still increase nonlinearly or linearly. There are also additional overlaps and combinations of curve forms of the control signal that occur in succession that can be adjusted as a function of need.
[0044] With increasing age the deep storage of oxygen and/or NO x in catalyst 2 deteriorates so that the desired catalytic processes can no longer occur efficiently. The behavior of the catalyst 2 in lean operating states can be different than in rich operating states. Variation in modulation of the characteristic curve of the control signal therefore permits adjustment to these boundary conditions with a simultaneous increase in efficiency of the catalytic processes. This is advantageous to maintain emission limits.
[0045] It is particularly expedient to conduct the adjustment of the characteristic curve of the control signal as a function of operating parameters in internal combustion engine 1 . This can occur via maps of operating parameters, as already described in FIG. 1 . It is therefore considered that the behavior of catalyst 2 is strongly influenced by the operating parameters of the internal combustion engine 1 . The rate of conversion changes sharply with exhaust temperature. The catalyst 2 is exposed to pollutants with a high exhaust flow rate so that in the extreme case the purification efficiency of catalyst 2 can decline. If exhaust recirculation is varied, the richness of the fuel/air mixture changes. If the amount of recycled exhaust rises, the NO x content in the exhaust drops. The ignition point influences the system in similar fashion to exhaust recirculation. By influencing the combustion trend the pollutant and oxygen concentration change at the same lambda value. With low crude emissions or a shift to more readily convertible pollutants (for example more CO, less CH 4 ) the requirements on accuracy of lambda control diminish. Such influences of the operating parameters can be considered by corresponding adjustment of the characteristic curve of the control signal so that maintenance of the emission standard is ensured over broad operating ranges of the internal combustion engine 1 .
[0046] In addition to ensuring the emission standard, in an advantageous embodiment of the invention the catalyst state and/or state of the sensor 4 , 5 , especially sensor 5 downstream from catalyst 2 can be determined from a change in the characteristic curve of the control signal.
[0047] In addition to increased reliability in maintain in emission values, the invention also permits a reduction in noble metal content of catalyst 2 . The catalyst 2 is mostly operated in regions in which conversion is improved. Because of this the catalyst volume can be correspondingly reduced and/or the noble metal compound of the catalyst can be reduced in order to achieve the same efficiency as in an ordinary control. It is possible to reduce the noble metal content and/or the catalyst volume during use of the method according to the invention without surpassing the pollutant emissions forming without use of the method by at least 10%, especially by at least 20%. In particular, the catalyst 2 in the case of an NO x storage catalyst has a noble metal content of less 80 g/ft 3 , especially less than 60 g/ft 3 . In a three-way catalyst a noble metal content of less than 60 g/ft 3 , especially less than 40 g/ft 3 , preferably less than 30 g/ft 3 , optimally less than 20 g/ft 3 , ideally less than 10 g/ft 3 is provided. | 4y
|
This is a continuation of application Ser. No. 608,367, filed May 9, 1984, now abandoned.
1. Field of the Invention
The present invention relates to a universal case for packaging and storing software and associated literature, in particular discs, cartridges and related documentation, and for serving as an easel for the documentation.
2. Description of the Prior Art
U.S. Pat. No. 4,356,918 of Kahle et al discloses a storage container for flexible magnetic discs in which a cover section is rotatable with respect to a base section. The cover section includes a pouch for holding the disc and serves as an easel for the same when the cover is rotated in excess of 270°. The pouch also has a pivotal front wall for increasing the volume thereof to facilitate insertion and removal of the disc.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a universal case for packaging and storing software and associated literature.
Another object of the invention is to provide a case which functions as an easel for the documentation associated with the hardware.
Another object of the invention is to provide a software package which will receive different sizes of cartridges.
Another object of the invention is to provide a case which has a transparent section for receiving a printed sheet therebehind which may serve as a label. Changes of labeling amounts to merely using a different printed sheet.
Another object of the invention is to provide a case which may be opened by a potential purchaser for inspection of the materials therein, while at the same time preventing pilferage of the software.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects, features and advantages of the invention, its organization, construction and operation will be best understood from the following detailed description, taken in conjunction with the accompanying drawings, on which:
FIG. 1 is a pictorial representation of a case constructed in accordance with the present invention;
FIG. 2 is a sectional view of the case generally along the line II--II of FIG. 1;
FIG. 3 is a sectional view of the case taken substantially along the line III--III of FIG. 2 and also including the cover which is only partially illustrated in FIG. 2;
FIG. 4 is a perspective view of the latch portion of the case;
FIG. 5 is a fragmentary section of a portion of the case, also showing the latch, and also illustrating the transparency of the cover;
FIG. 6 is a fragmentary view of the latch portion just prior to latching;
FIG. 7 is a fragmentary sectional view taken substantially along the line VII--VII of FIG. 2 showing also the cover and the latched condition of the cover and base;
FIG. 8 is a fragmentary sectional view as would be seen substantially along the line III--III of FIG. 2 with the cover open to a detent position for access to the software and documentation;
FIG. 9 is a sectional view of the case as would be seen with the base inverted and the cover fully open, as viewed in the direction generally indicated by the parting line IX--IX of FIG. 2 for use as an easel;
FIG. 10 is a perspective view of the case being used as an easel supporting documentation;
FIG. 11 is a fragmentary sectional view taken substantially along the line XI--XI of FIG. 2 showing a first anti-pilferage feature;
FIG. 12 is an open development of the label illustrating a second anti-pilferage feature;
FIG. 13 is a sectional view, similar to that of FIG. 8, showing the structure of FIG. 12 as its positioned prior to use by a purchaser and further showing an adaptor for supporting a different size of cartridge;
FIG. 14 is a fragmentary top view of the adaptor structure of FIG. 13;
FIG. 15 is a sectional view taken along the line XV--XV in FIG. 14; and
FIG. 16 is a three-dimensional overview of the case constructed in accordance with the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1-3, the software case is generally illustrated at 10 as comprising a base 12 and a cover 14.
The cover 14 comprises a top wall 16, an end wall 18, a bottom wall 20, and an offset extended pair of walls 22, 22a. The cover 14 further comprises a pair of sidewalls 24 and 26. The sidewall 24 comprises an oblique edge 28 and the sidewall 26 comprises an oblique edge 30. The oblique edges, as will be appreciated from FIGS. 9 and 10, serve to support and guide the bottom of the documentation for engagement behind the walls 22 and 22a.
The sidewalls 24 and 26 further include sections which extend towards the free end of the cover and joined with a transverse ridge 98 which is received, along with the sidewalls within the cavity formed by the base 12.
The base 12 comprises a bottom wall 34, a pair of sidewalls 36 and 38, and a front wall 40 which is slightly recessed at a wall section 42. The sidewall 36 comprises an integral hinge pin 44 which is received in an aperture 46 of the sidewall 24 of the cover, and a sidewall 38 likewise includes an integral hinge pin 48 which is received in an aperture 50 in the sidewall 26 of the cover.
As best seen in FIG. 3, the sidewall 26 comprises a pair of detent apertures 52 and 54 which receive a detent pin 56 which is also integral with the sidewall 38. In the position illustrated in FIG. 3, the cover is closed and the pin 56 is received in the aperture 54. With the cover open to a first position, as best seen in FIG. 8, the pin 56 is received in the aperture 52. A similar set of apertures 58 and 60 and a similar detent pin 62 are provided at the opposite side of the case, as best seen in FIG. 9.
Referring specifically to FIG. 2, and as partially illustrated in other smaller figures, a plurality of tabs 64, 66 and 68 project from the bottom wall 34 and, together with the sidewall 36 and the front wall 40, define a position for locating and holding a cartridge. Similar structure including a plurality of tabs 70, 72 and 74 are illustrated on the right side of the drawing for holding a cartridge 76 (shown in phantom) therebetween in conjunction with the sidewall 38 and the front wall 40. Inasmuch as some cartridges, such as the cartridge for the IBM™ PC JR., incorporate transverse rib on the bottom side, a pair of similar, oppositely-directed ribs 78, 80 and 82, 84 are provided for supporting a cartridge on each side of its own rib.
In a central area of the bottom wall 34 a plurality of differently shaped tabs 86, 88, 90 and 92 extend from the bottom wall for locating different sizes and shapes of cartridges of other manufacturers, as illustrated in phantom at 94 and 96.
A flexible magnetic disc 170 (shown in phantom) is received and stored in a pocket generally defined by the walls 16, 20, 22 and 30 and by a divider 32 which is connected to the wall section 22 and extends toward, but short of the wall 16 thereby forming a gap 35 (FIGS. 3, 8, 9 and 13). The purpose for the gap 35, as will be evident from the discussion of the label, is to permit the label to lie against the inner surfaces of the walls 16, 18 and 20. As can be seen, therefore, the divider 32 divides an elongate pocket into a pair of pockets, one of which is sized to receive a flexible magnetic disc 170.
Referring now to the right side of FIG. 3, the cover 16 extends beyond the ridge 98 so that its inner surface may engage an upper edge 100 of the front wall 40 when the cover is latched to the base.
Referring to FIGS. 4-7, a latch 102 is illustrated in the area of the front wall section 42 as comprising a resilient member 104 which includes a ramp 106 and a downwardly facing surface 108. As the cover is closed, the ramp 106 engages the distal end of the cover causing the member 104 to yield and be received in a slot 112 which is partially defined by an upwardly facing surface 110. Upon latching, the surface 110 is engaged with the surface 108.
Referring to FIGS. 9 and 10, the case is illustrated as the cover and base would be positioned with respect to one another for use as an easel. As shown, the cover 14 has been rotated in excess of 270° from its closed condition so that the upper surface of the cover rests against the edge 34a of the bottom wall 34. In this position, the cover acts as a support for the documentation which is guided by the edges 28 and 30, as mentioned above so as to rest on the free ends of the sidewalls 36 and 38 and be prevented from sliding off by the sections 22 and 22a as shown in FIG. 10.
The case of the present invention is provided with two anti-pilfering features as briefly mentioned above. The first of these features is illustrated in FIGS. 2 and 11. FIG. 2 shows a plurality of bosses 116, 118 and 120 each defining a slot therein. As illustrated for the cartridge 76, a generally L-shaped hold-down device 122 may be provided. The device 122 comprises a first leg 124 which has a flat distal end surface 124a extending approximately 0.250" while the remainder of the surface in the unstressed state, has a small upward rise of, for example, 0.025" so that the device may be flexed against the cartridge upon insertion of the leg 126 into the slot of the boss 120. The leg 126 is provided with a plurality of barbs 128 so as to prevent removal of the device 122 without breaking the device. This feature therefore discourages pilfering, yet permits the case to be opened by a perspective purchaser.
A second anti-pilfer feature is illustrated in FIGS. 12 and 13. This feature prevents pilfering of the flexible magnetic disc 170 prior to purchase. As best seen in FIG. 12, initially, upon packaging, the label 130 provides the anti-pilfering feature for the flexible magnetic disc 170. As shown, the label 130 comprises a first portion 132 which is hinged at 142 to a second portion 146. The opposite end of the portion 142 comprises two folds defining the section 150 and a section 152 which are to lie against the inner surfaces of the end wall 18 and the wall 20 of the cover 14. The portion 146, actually the undersurface of that portion as shown in FIG. 12, is to be imprinted as the label and lie against the transparent top wall 16. The undersurface of the portion 132 may or may not be printed.
As illustrated, the portion 132 has been slit at 134a, 134b to form a flap 134, and has been further slit at 138, 140. In order to secure the magnetic disc 170, and as illustrated in FIG. 12, two corners thereof are inserted into the slits 138, 140 and the flap 134 is then folded over and secured with an adhesive tape 136. The portion 132 is then folded at the hinge 142 to the position illustrated in phantom at 144 and the edge is sealed with an adhesive tape 148 to the folded portion 150.
An aperture 154 is provided for accommodating the latch.
After packaging as described above the entire packet is placed in the cover, as shown in FIG. 13, and hooked behind a plurality of projections 172 (see FIG. 7).
In order to remove the magnetic disc, after purchase, the user will separate the two portions 132, 146 at the hinge 142, which may be provided as preparations to facilitate opening. Afterward, the disc may be stored in the aforementioned pocket defined by the divider 32, the sidewall 26 and the walls 16, 18, 20, 22 and 22a.
Referring to FIGS. 13-15, the case may also accommodate a further cartridge of different size and shape. Here, a bridge 156 serves in conjunction with the tabs 90 and 92 and the front wall section 42 to support and locate a cartridge 154 (shown in phantom in FIG. 13). The bridge 156 comprises an elongate member 156 having a pair of depending members 164 (only one shown) which are received in the slots defined by the bosses 116 and 120. The upper surface of the member 158 comprises a pair of projections 162. With this mounting of a cartridge, an anti-pilferage hold down device of the type shown in FIG. 11 could be employed in conjunction with the boss 118.
Although I have described my invention by reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. I therefore intend to include within the patent warranted hereon all such changes and modifications as may reasonably and properly be included within the scope of my contribution to the art. | 4y
|
PRIORITY
[0001] The present application is a continuation of application Ser. No. 13,107,568, filed on May 13, 2011, which claims priority to provisional patent application entitled, “LOW-E HOUSEWRAP,” filed on May 21, 2010, and assigned U.S. Application Ser. No. 61/346,916. The contents of these applications are incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to building structure materials, and more specifically to an infiltration barrier used in building construction to improve energy efficiency and to protect against air infiltration and moisture build-up in buildings.
[0004] 2. Description of Related Art
[0005] In order to improve the energy efficiency of new and existing buildings, it has been common practice in building new structures, and in residing old structures, to cover the exterior wall sheathing with an infiltration barrier, for example, prior to installation of a covering material such as siding. One such infiltration barrier is a high density polyethylene fiber sheeting. While infiltration barriers cut down on drafts and thereby convective heat loss, they provide little other contribution to the energy efficiency of the structure.
[0006] In addition to addressing energy efficiencies of new and existing buildings, moisture concerns can be one of the worst enemies of home or building construction. Water or moisture or humid air infiltration if allowed to penetrate behind siding or brick can saturate the wood of a building structure, thereby creating an environment that encourages mildew or rot. A weather resistant barrier has for many years been applied to the wood studs of buildings and homes in order to resist the moisture or water generated by weather. Such material is typically flexible and in a film or sheet form. Typically, this weather resistant barrier or “house wrap” is applied to the wooden stud frame before the application of a final siding or veneer (e.g. brick, metal, painted wood). Many such “wrap” products are commercially available such as, for example: Dupont Tyvek®, Typar®. Housewrap (www.typarhousewrap.com), and Barricade®. building wrap (www.ludlowcp.com).
[0007] In 2010 the International Energy Conservation Code (IECC) and International Residential Code (IRC) increased the thermal performance requirements for residential walls. Both of these standards seek to improve thermal performance and reduce energy needs per dwelling. As of January 2010 the U-value requirement for geographical area or zones 5-8 is 0.057; the reciprocal R-value for wall systems is R-20. The U-factor is the inverse, or reciprocal, of the total R-Value, i.e.: U-factor=1/Total R-Value. The R-Value is the thermal resistance to heat flow. A larger R-Value means that the material has greater thermal resistance and more insulating ability as compared to a smaller R-Value. Such R-Values can be added together. For instance, for homogeneous assemblies, the total R-Value of an insulation assembly is the sum of the R-Value of each layer of insulation. These layers may include sheathing and finishes, the insulation itself, air films and weatherproofing elements.
[0008] In order to meet the new building requirements, builders have employed additional building techniques such as altering construction of framed openings. For example, typically, builders have constructed walls on 2×4 framing. However, due to the revised requirements, builders are altering building designs by constructing walls on 2×6 framing and inserting, for example, R-20 mass insulation within the respective wall cavity in order to meet the energy/code regulations mandated within the building industry. These techniques, however, increase construction costs because of the added and more expensive construction materials. In addition, the increased size of framing also produces a loss in living space. Nevertheless, many builders have simply accepted the added cost and loss of living space created by the newly implemented thermal code changes.
[0009] Accordingly, a need exists for providing a protective wrap that improves energy efficiency and protection against air infiltration and moisture build-up in buildings while satisfying newly implemented industry-wide energy/code regulations. There is also a need for employing a protective wrap which meets or exceeds the newly implemented code requirements on existing framing structures or openings and/or without increasing the wall profile of a building.
SUMMARY OF THE INVENTION
[0010] The present invention provides a low-emittance housewrap material which may be implemented on traditional 2×4 framing having R-15 mass insulation material within existing or newly constructed framing cavities. The material of the present invention also meets requirements for serving as a water resistive barrier as defined by The International Code Council's (ICC) codes and standards used to construct residential and commercial buildings, including homes and schools (e.g., ICC AC38). Thus, by not increasing the wall profile in the attempt to meet new industry standards, the builder does not have to perform additional techniques or provide additional expenses for constructing framed openings.
[0011] Still other aspects, features and advantages of the present invention are readily apparent from the following detailed description, simply by illustrating a number of exemplary embodiments and implementations, including the best mode contemplated for carrying out the present invention. The present invention also is capable of other and different embodiments, and its several details can be modified in various respects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The present invention will be understood more fully from the detailed description given below and from the accompanying drawings of various embodiments of the invention, which, however, should not be taken to limit the invention to the specific embodiments, but are for explanation and understanding only.
[0013] FIG. 1 provides a top view of a low-emittance housewrap material according to an exemplary disclosed embodiment;
[0014] FIG. 2 provides a cross-sectional view of a low-emittance housewrap material according to an exemplary disclosed embodiment;
[0015] FIG. 3 provides a cut-away perspective view of a low-emittance housewrap material according to an exemplary disclosed embodiment;
[0016] FIG. 4 provides a top view of a low-emittance housewrap materials during an assembly method according to an exemplary disclosed embodiment;
[0017] FIG. 5 provides a perspective view of the low-emittance housewrap materials during the assembly method of FIG. 4 ;
[0018] FIG. 6 provides a top view of a low-emittance housewrap materials during a continued assembly method according to an exemplary disclosed embodiment;
[0019] FIG. 7 provides a perspective view of the low-emittance housewrap materials during the assembly method of FIG. 6 ;
[0020] FIG. 8 provides a top view of low-emittance housewrap materials after assembly according to an exemplary disclosed embodiment;
[0021] FIG. 9 provides a bottom view of low-emittance housewrap materials prior to assembly according to an exemplary disclosed embodiment;
[0022] FIG. 10 provides a top view of low-emittance housewrap materials during an assembly method according to an exemplary disclosed embodiment;
[0023] FIG. 11 provides a bottom view of low-emittance housewrap materials after assembly according to an exemplary disclosed embodiment;
[0024] FIG. 12 provides an exemplary exterior wall according to an exemplary disclosed embodiment; and
[0025] FIG. 13 provides a low-emittance housewrap material application to the exemplary wall structure of FIG. 12 according to an exemplary disclosed embodiment.
DETAILED DESCRIPTION
[0026] A low-emittance housewrap is described. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments. It is apparent to one skilled in the art, however, that the present invention can be practiced without these specific details or with an equivalent arrangement.
[0027] Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, FIG. 1 illustrates a top view of low-emittance housewrap materials according to one disclosed embodiment of the present invention. By way of example, two pieces of the low-emittance housewrap materials 10 , 12 are shown. Each of the two pieces of low-emittance housewrap materials 10 , 12 may comprise flap portions 14 , 16 , respectively, at one end thereof. At another end the low-emittance housewrap material may include an adhesive strip 18 such as that provided on low-emittance housewrap material 10 . In a preferred embodiment, the top surface 20 , 22 of the low-emittance housewrap materials 10 , 12 , respectively, is a reflective material such as a layer of reinforced foil material.
[0028] Turning to FIG. 2 , a cross-section of the low-emittance housewrap material 12 is shown. The low-emittance housewrap material 12 may comprise an assembly of product component parts including, for example, a reflective foil material 34 , foil reinforcement 26 , and a foam material 28 . In one embodiment, the reflective material may comprise a facing of approximately 99.4% polished aluminum. It is noted that the reflective material may comprise a facing having any suitable amount of aluminum, for example, greater than about 90%, preferably between about 90% and about 99.9%, even more preferably between about 99.0% and about 99.9%. The reflective foil material 34 may be nonreinforced on one side. On the other side, the reflective foil material 34 may comprise a foil reinforcement 26 including, for example, a scrim foil reinforcing 30 (e.g., see FIG. 3 ). Scrim is a term known in the art to consist of crossed lines of plastics material which serve to strengthen the overall product and to prevent stretching damage to the layers. The reflective foil material 34 and foil reinforcement 26 may be applied over and bonded to the foam material 28 . The scrim foil reinforcing 30 is sufficient to provide a tensile strength of approximately 23 pounds per inch width in a machine direction and 25 pounds per inch width in a cross machine direction on a low-emittance housewrap material test specimen cut approximately 1″ wide by 9″ long in standard ambient lab conditions. The foam material 28 serves as a polyolefin thermal break such as one comprising a closed cell polyethylene foam. In a preferred embodiment, the nominal thickness of the polyolefin thermal break is approximately ¼″ (0.25″). It is noted that the nominal thickness of the polyolefin thermal break may be any suitable thickness, for example, greater than about ⅛″ (0.125″) and less than about ⅜″ (0.375″). Thicknesses above about ¼″ are within the scope of the present invention. It is noted that a thickness greater than about ¼″ may require use of 2×6 framing instead of the more traditional 2×4 framing. The low-emittance housewrap 12 may also incorporate a self adhered drainage plane 24 feature as further described below.
[0029] Thus, the invention includes a layer of polyethylene foam which serves as a support for the other added component layers. Polyethylene foam or equivalent polypropylene foam may be utilized, both being in the chemical family designated as polyolefins. A thin layer of aluminum foil is bonded indirectly to one or both sides of said foam layer. Thin polyethylene layers are placed between the aluminum foil and the foamed layer. The thin polyethylene is bonded to the aluminum foil layer to greatly improve its resistance to tearing. This strengthening feature means that the end product has a much wider use than has been known in the art. A layer of strengthening scrim may be added to further enhance the product integrity. In practice of the invention, the various layers adjoin one another after being flame or heat roller laminated together.
[0030] In certain embodiments and in practice of the invention, both sides of the foam layer may be covered with layers as described above. The end product may thus appear identical on either side with the aluminum foil layers being externally located. Thus, use and installation is simplified since the product may be used with either side facing out since both external faces are identical. The resulting bonded layers are easily rolled, transported and installed without requiring special tools or environmental precautions which must be taken with many other prior art insulations.
[0031] Turning to FIG. 3 , the low-emittance housewrap 12 comprises perforations 32 sufficiently spaced to ensure that the low-emittance housewrap material does not act as a vapor barrier. In one preferred embodiment, the perforations in the low-emittance housewrap are generated from perforation system consisting of 1/16″ punchers placed in four holes per 1.25 square inch sequence on a collar mechanism. The collar mechanism is mounted to a drive roll assembly for perforation of the low-emittance housewrap wherein a 1.25 square inch perforation pattern is achieved on the finished product. A perforation pattern of 1.25 square inch allows low-emittance housewrap 12 to meet the criteria for perms, water vapor transmission and water resistance while maintaining an effective emissivity rating. This is unique and contrary to industry standards wherein in many applications, micro perforations are generated in housewraps using needles for vapor penetration. However, in such convention applications, the micro perforations are susceptible to resealing when exposed to higher temperatures. This affect may trap moisture and induce undesirable results such as mold and rot. In contrast, the present perforation pattern of the prescribed invention eliminates the possibility resealing when exposed to higher temperatures. Spaced in approximately 1.25″ square perforations, the low-emittance housewrap material achieves a preferred permeance and water vapor transmission of approximately 7 perm or 40 g/day/m 2 . As such, the present low-emittance housewrap material performs within the optimal permeance and water vapor transmission range of about 5 to about 20 perm.
[0032] The present low-emittance housewrap material meets the Standard Specification for Reflective Insulation, C 1224-03, Section 6, 6.1, which states that “Low emittance materials shall have a surface with an emittance of 0.10 or less, in accordance with test Method C 1371.” Specifically, the present low-emittance housewrap material achieves an emittance of 0.10 or less, more specifically within a range of about 0.03 to about 0.05, in accordance with test Method C 1371.
[0033] Accordingly, the product low-emittance housewrap material of the present invention is constructed to include the following approximate performance characteristics:
[0000]
Test Description
Test Results
Perm Test
7 perms
ASTM E-96
Water
As Received 23 hrs
Resistance
Pass
ASTM D-779
Weathered 23 hrs
Pass
Ultraviolet light
No Cracking
Accelerated Aging
No Cracking
Tensile Strength
23 lbs/inch
(machine direction)
25 lbs/inch
(cross direction)
U-value
.056 vinyl
Wall (zone 5-7)
2010 IECC
U-value
.051 brick
Wall (zone 5-7)
2010 IECC
U-value
.063 Stone
Wall (zone 5-7)
2010 IECC
[0034] Although the use of 1/16″ punchers at a rate of four holes per 1.25 square inch is described above and represents one of many preferred embodiments of the present invention, other size punchers may be used and other rates of holes per given area are within the scope of the present invention. For example, the diameter of the puncher may be varied to any suitable size and the rate may be modified to achieve the particular permeance and emittance standards required by a particular building code, specification or other requirement.
[0035] The system U-values described in The Evaluation of Thermal Resistance of a Building Envelope Assembly demonstrates the performance of wood framed walls (2×4 construction 16″ on center). The U-value calculations are based on methods outlined by the ASHRAE Handbook of Fundamentals. The U-value performance of these systems achieve a U-value between 0.051 (brick), 0.056 (vinyl) and 0.063 (stone) satisfying or exceeding requirements for zones 1-7 established by 2010 IECC Code Table 402.1.3 or equivalent UA alternative values established by other code bodies.
[0036] Flap portion 16 is illustrated in FIG. 3 . This overlapping flange serves as a self adhered drainage plane 24 . During assembly of one or more low-emittance housewrap sections, the flap portion 16 may be assembled to cover an edge of an abutting portion of another low-E housewrap material section in order to seal the edge. For example, turning to FIGS. 4 and 5 , a first section 10 of low-emittance housewrap material is positioned near a second section 12 of low-emittance housewrap material. The flap portion 16 of the second section 12 of low-emittance housewrap material may be disposed over an edge portion 38 of the first section 10 of low-emittance housewrap material. In one embodiment, the aforementioned edge portion 38 may include an adhesive strip 18 for retaining the flap portion 16 thereon. The adhesive strip 18 may be employed on the top surface 20 such as on the reflective foil material 34 . While the adhesive strip 18 has been described and shown in the drawings for illustrative purposes, any means may be employed which is suitable for retaining the flap portion 14 over the edge portion 38 in order to provide a water resistive barrier between the abutting sections of low-emittance housewrap materials.
[0037] Turning to FIGS. 6 and 7 , a protective film is removed to expose the adhesive strip 18 in preparation for securing the flap portion 16 over the edge portion 38 . The flap portion 16 is contacted to the adhesive strip 18 and secured over the edge portion as illustrated in FIG. 8 . This assembly serves to provide a water resistive barrier between two abutting sections of low-emittance housewrap materials of the present invention to effectively seal their respective edges and allow water runoff from one low-emittance housewrap material section to another low-emittance housewrap material section.
[0038] A bottom view vantage point of abutting low-emittance housewrap materials is illustrated in FIGS. 9-10 . Again, the first section 10 of low-emittance housewrap material is positioned near the second section 12 of low-emittance housewrap material. The flap portion 16 of the second section 12 of low-emittance housewrap material is disposed over an edge portion 38 of the first section 10 of low-emittance housewrap material. Edge portion 38 may include an adhesive strip 18 for retaining the flap portion 16 thereon. As a sufficient force is applied, for example, to flap portion 16 to contact the adhesive strip 18 , the flap portion 16 is held in retention over the edge portion 38 as shown, for example, in FIG. 11 . It is clear from FIG. 11 that, in a final assembly arrangement, a foam edge portion 56 of a first low-emittance housewrap material 10 abuts a foam edge portion 58 of a second low-emittance housewrap 12 . Accordingly, the assembled sections serve to provide a water resistive barrier between two abutting sections of low-emittance housewrap materials of the present invention.
[0039] In order to improve the energy efficiency of new and existing building structures, application of the herein described low-emittance housewrap serves to cover the exterior wall sheathing with an infiltration barrier, for example, prior to installation of a covering material or exterior finish such as siding, brick, stone, masonry, stucco and concrete veneers, for examples. The herein described low-emittance housewrap also serves to protect against air infiltration and damaging moisture build-up. Air infiltration may occur in typical construction through, among other places, sheathing seams and cracks around windows and doors. Moisture build-up can occur externally in the wall cavity from, for example, leaking exterior finishes or coverings, and cracks around windows and doors. The low-emittance housewrap of the present invention does not trap the water, but rather allows it to flow downward so as to exit the wall system.
[0040] Installation procedures of the presently described low-emittance housewrap include those as described, for example, in the technical manual for ESP Low-E® Housewrap utilized on exterior walls and under a primary barrier. The technical manual for ESP Low-E® Housewrap is submitted herewith and is hereby fully incorporated herein by reference. Turning to FIG. 12 , an exemplary exterior wall assembly 40 is constructed and prepared for receiving the low-emittance housewrap material of the present invention. In the illustrated example, a window opening 42 is shown. In a preferred embodiment, the low-emittance housewrap is employed after the walls have been construction and all sheathing and flashing details have been installed. The low-emittance housewrap material is preferably applied before doors and windows have been set inside framed openings and prior to the installation of the primary wall covering.
[0041] Turning to FIG. 13 , a first low-emittance housewrap material is applied to the wall assembly 40 . The reflective side of the low-emittance housewrap material is installed facing outwardly. In one preferred embodiment, a roll of low-emittance housewrap material is unrolled horizontally starting at the corner of a preferred exterior wall 40 . The flange side or flap portion (e.g., 14 , 16 of FIG. 1 ) of the roll is installed facing downwardly. The low-emittance housewrap material is secured to the exterior wall with fasteners 48 such as staples or cap nails (or any other suitable fasteners) at preferably every 8-12″. When applying another horizontal run of low-emittance housewrap material 44 , the foam ends of each applied section of rolled low-E housewrap material abut together such that the flange 52 of the additionally applied low-emittance housewrap material 44 is allowed to overlap the outside edge 50 of the adjacent low-emittance housewrap material 46 . This installation ensures that any intruding water is encouraged by the drainage plane (e.g., 24 of FIG. 2 ) to flow downwardly.
[0042] In a preferred embodiment, the flange 52 is installed to overlap the abutting foam edge by approximately 2″. The low-emittance housewrap material is installed to extend over all of the sill plates by a minimum of approximately 1″. The vertical and horizontal seam areas are sealed with suitable low-emittance foil tape. The low-emittance housewrap material may be trimmed around each framed opening with additional appropriate detailing applied as per window/door manufacturer and/or code standards.
[0043] Once installed, an appropriate exterior covering may be applied/installed over the low-emittance housewrap. Such covering may include, but not limited to, siding, brick, stone, masonry, stucco and concrete veneers. The utilization of the herein described low-emittance housewrap provides, inter alia, a protective wrap that not only improves energy efficiency in accordance with newly implemented industry-wide energy/code regulations, but enhances drainage of damaging moisture build-up while protecting against air infiltration.
[0044] Moreover, other implementations of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. Various aspects and/or components of the described embodiments may be used singly or in any combination. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims. | 4y
|
This application is a continuation of application Ser. No. 08/199,474, filed on Feb. 22, 1994, now abandoned.
FIELD OF THE INVENTION
This invention relates generally to the application of wood trim in residential and commercial building construction and particularly to a barbed nail for joining the wood trim to associated wallboard and metal studs.
BACKGROUND OF THE INVENTION
In residential as well as commercial construction there is a great deal of what is termed finish carpentry. Skilled labor is required to perform this type of work and it is very time consuming and therefore very expensive. In view of this, every effort is made to cut corners and to reduce the cost of finish work.
One particular type of finish work that requires a substantial amount of labor and material expense concerns the application of finish carpentry, for example wood trim. The various trim members used in finishing the interior of a building include the casings around doors and windows, baseboard, crown molding, wainscoting, and chair rails. The wood trim serves an aesthetic purpose as well as a functional purpose. It provides a finished look to a room; and it also seals the gaps between the doors, windows, or floors and the adjacent wall.
In residential construction, wood trim is attached to the associated wallboard and wood studs. Wood studs are generally used to form the support base for the wallboard. The use of wood studs allows the wood trim to be quickly and efficiently attached to the wallboard and wood stud by use of a power or pneumatic gun. One disadvantage of using the wood stud support is that in today's construction market an equal length wood stud can cost twice the amount of the metal stud. Another disadvantage of using wood studs is the environmental concern that a continuing lumber demand will promote the deforestation of the country. In addition, wood members are subject to termite infestation which requires chemical treatment of the wood or the surrounding soil. Therefore, there is an economical as well as an environmental incentive to use metal studs in place of wood studs.
Currently, in most commercial construction, metal studs are used because of their inherent strength and non-combustible qualities. The wood trim is attached to the wallboard and a metal stud with screws. Although the application of the wallboard to the metal stud with screws is efficient, the application of wood trim is time consuming. One method of applying the wood trim requires a hole to be first driven through the wood trim, followed by the insertion of a finish head screw through the wood trim, wallboard and metal stud using an electric screw gun, requiring time and expense. The end result is a wood trim having large and rough screw holes which later require an application of wood filler and sanding for a finished job. Another method used to apply wood trim requires gluing the trim to the predetermined location and then shooting smooth shank nails into the wood trim, wallboard, and metal stud with a pneumatic gun. This method is a two-step process requiring expensive labor time. A third method requires shooting a nail into the three layers at a 45° angle. This method does not provide the holding power preferred as in the previous methods. To benefit from the advantages of metal studs, it is necessary to minimize the labor expenditure of applying the finishing touches such as wood trim.
SUMMARY OF THE INVENTION
The present invention addresses the aforementioned problems by providing a method that significantly reduces labor time and cost. In addition, the invention provides a method to reduce material cost by using metal studs rather than the more costly wood studs. Finally, the invention provides a means to attach the wood trim to the wallboard and metal stud to securely hold the members in place, wherein minimal finishing and repair is required to the applied wood trim.
The invention is a method to attach wood trim to the base wallboard and metal stud with a finish nail having a plurality of barbs along its shank. The finish nail has the capability of driving into the three layers of wood trim, wallboard and the metal stud by means of a power or pneumatic finish nail gun in approximately one-tenth the current labor time. The barbed finish nail provides a sufficient holding strength so that the nail is not pulled back out of the metal channel. The barbed finish nail further results in a final appearance that requires minimal touch up repair.
Other objects, advantages and applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein:
FIG. 1 is a view illustrating the prior art showing screws driven through wood trim, wallboard, and a metal stud;
FIG. 2 is a perspective view of a typical metal stud wall assembly utilizing the present invention;
FIG. 3 is a sectional view taken along lines 3--3 of FIG. 2 showing the barbed finish nail; and
FIG. 4 is a sectional view of the barbed finish nail taken along lines 4--4 of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 illustrates the current method of attaching wood trim 10 onto wallboard 12 and a metal stud 14. Generally, wall construction comprises laterally spacing metal C-shaped studs 14 which have upper and lower ends retained in rigid channel shaped upper and lower tracks (not shown). These tracks may be formed of metal and removably mounted on the ceiling and floor with the open sides of the channel tracks in confronting relationship to receive the respective ends of the metal studs 14. The metal studs 14 are cut to appropriate length and manipulated into the desired position extending between the ceiling and the floor to form a frame. A wallboard panel 12 is positioned against the framing and adjusted to cause the panel edges to fall in approximate centers of the vertical studs 14. The wallboard panel 12 is then mechanically secured to the upper ceiling and lower floor tracks and vertical studs 14 with suitable Teflon® coated drywall screws 16. When using sheet metal studs 14, the procedure of securing the wallboard 12 is accomplished usually with an electric powered screw driver and self-drilling, self-tapping screws. Wood trim 10 can then be attached in a time-consuming process of first driving a hole through the wood trim and then securing the wood trim 10 to wallboard 12 and metal stud 14. The screw 18 causes an unsightly gouge 20 that requires additional time-consuming filling and sanding.
In residential construction, wood framing generally consisting of 2"×4" wood members (not shown) replace the metal studs 14. Wood studs allow the carpenter to shoot nails with a pneumatic gun when attaching the wood trim onto the wallboard and the wood studs. The method of attaching the three layers by means of nails using a nail gun is highly efficient and minimizes labor costs. But in order to save material cost, a suitable method and means to apply wood trim and wallboard to a frame of metal studs is necessary.
FIGS. 2-4 disclose a means to apply wood trim 10 and wallboard 12 to a metal stud 14. A wallboard panel 12 is generally made of a high gypsum material. The wallboard 12 has a layer of paper 22 applied to both faces to provide a painting surface. The wallboard 12 is positioned against the metal stud 14 framing and adjusted so that the panel edges fall on the vertical studs 14. The panel 12 is then secured to the upper and lower track (not shown) and vertical studs 14 with suitable Teflon® coated drywall screws 16. This procedure can be accomplished with an electric powered screw driver using self-drilling, self-tapping screws. The wood trim 10 is aligned at the predetermined location after the necessary cutting and fitting has been completed. A barbed finish nail 24 is driven through the wood trim 10, wallboard 12 and metal stud 14 with a pneumatic finish nail gun. This method to apply the wood trim provides a securely held trim that can be applied in a fraction of the time required by the prior art. In addition, the resultant hole 26 in the wood trim 10 is significantly smaller than the gouge 20 left by finish head screws 18 used in the prior art. The labor to fill and sand hole 26 is proportionally reduced to the labor required in the prior art.
Nail 24 generally has the same dimensions and sizes as existing finish nails, but is distinguished from the current finish nail in that the nail 24 has a plurality of flexible barbs 28 running along the shank 30. Existing finish nails are not adequate to secure a material to metal because the finish nails are of such a proportion having a small head and a smooth shank, that the shank is easily moved out of the metal channel to cause dislocation of the wood trim 10 and wallboard 12 from the metal channel 14. On the other hand, it is advantageous to use a nail 24 of the same dimensions and size of a finish nail, because the nails can fit into existing pneumatic nail guns; and the head of a finish nail 24 is such that, when shot into the material, the head is small enough not to form a large gouge 20 that needs extensive resurfacing and sanding.
Nail 24 may be made with standard metallic material such as hardened aluminum or galvanized steel. Referring to FIG. 3, the nail may have a low profile rectangular, square or round flat-topped head 32. Nail 24 has a solid, continuous, one piece shank 30 extending from the head 32 and having a cross-sectional area smaller than the cross-sectional area of the head 32. The shank 30 may have a circular cross-sectional area, but the preferred nail 24 has a flat sided shank 30, resulting in a square or rectangular cross-section, as shown in FIG. 4. A tip 34 is located at a distal end from the head 32 and forms a sharp point for piercing the solid material. Barbs 28 are located preferably parallel to each other along opposing sides of the shank 30. The barbs may also be staggered along the opposing sides of shank 30, or located along one side of shank 30. In the preferred embodiment, the barbs 28 are located approximately three-fourths of the way up the shank 30 from tip 34. It is particularly important to have barbs 28 near the tip 34 to anchor against the metal stud 14. The barbs 28 have flexible pointed surfaces that retract toward the shank 30 in the direction of the head 32 to create an essentially smooth surface 43, axially along the shank 30 as the nail 24 is penetrating the solid material of the wood trim 10, wallboard 12 and stud 14. The smooth surface 43 allows the nail to penetrate the wood trim 10 through the hole formed by tip 34 without damage to the wood material. The barbs 28 are resilient enough to expand outwardly after the barbs 28 have been driven through the metal stud 14 and catch against the inner surface 36 of the metal stud 14 so that the nail 24 cannot be easily withdrawn from the stud 14.
The preferred means to form barbs 28 is to cut a smooth shank finish nail angularly along shaft 30. As seen in FIG. 3, the flexible pointed surfaces of the barbs 38 have outer 36 and inner 38 slanted portions that join to form the barb tips 42. The barb tips 42 may be either rounded (FIG. 4), straight, pointed or other shapes. Each outer and inner slanted portions 36, 38 are separated from another slanted portion 36, 38 along the axial length of the shank 30 by a straight surface portion 44. Straight surface portion 44 should have a length slightly greater than the thickness of the sheet material for metal stud 14, so that stud 14 is disposed along straight surface portion 44 between adjacent barbs 28, but does not allow oscillation of the nail 24.
As nail 24 is driven into the solid layers, the barbs 28 flex toward the straight surface portion 44 of the shank 30 so that inner slanted portion 38 lays approximately adjacent to straight surface portion 44. Barbs 28 that extend beyond metal stud 14 expand so that a pair of parallel barb tips 42 abut inner surface 36 of the metal stud 14. For a particular application, a nail 24 should be used having a length greater than the thickness of the three solid materials so that at least one pair of parallel barbs 28 extend beyond the metal sheet material.
This combination of a new method for installing wood trim onto construction wallboard with the use of a barbed finish nail 24 provides a finished product that is one tenth of the labor cost and one-half of current material cost. In addition, the low profile head 32 of the barbed finish nail 24 requires less finishing work of patching and sanding the wood trim 10 once applied.
While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law. | 4y
|
FIELD OF THE INVENTION
This invention relates to an apparatus for cross-cutting trees and more particularly to an improved felling head for felling trees.
BACKGROUND OF INVENTION
The valuable part of a tree is the butt area where the felling cut is made and there has been increasing concern over the damage being done to this area by severing devices now in use, particularly shears. To overcome this, numerous proposals have been made adapting chain saws to felling heads in place of the shear blades and a large number of the same are in operation. The main drawback, however, of chain saws is their fragility.
Numerous proposals have also been made adapting circular saw blades and cutting disks for cutting trees and severing standing trees. In the majority of the known devices, the circular saw blade is mounted on a central axle and, in some cases, are rotated at high speeds, i.e. rim speeds in the range of 10,000 to 20,000 f.p.m. Some feel these speeds are necessary to give a high quality cut and perhaps more importantly to build up a reservoir of energy which can be applied to produce a rapid cut. Varying degrees of success have been achieved by the devices now known.
One problem with the majority of the known circular saw devices is that they are bulky. One reason for this is that the rotary cutter running on a central axis must have a diameter at least twice that of the tree to be cut plus space required for the hub and axle. It has been found that a minimum size for the saw is about 21/2 times the diameter of the largest tree to be cut. This ratio also holds true for two cutters abreast when each cuts half of the tree.
Another reason contributing to the bulkiness of circular saws is that, in many cases, they require protection particularly where slim disks are used to minimize the kerf loss. Also, in many instances, the saw blade is retractably mounted in a housing which increases the bulk of the device and requires additional apparatus to effect a reciprocating stroke at least equivalent to the largest diameter of tree to be cut.
Some disks are not protected as they do not retract and while they are less bulky they must be heavy enough to withstand impact loads imposed thereon in addition to those produced by cutting. Also, they run at high rim speeds and thus store a great deal of energy. This permits a very fast cut but the energy release can also produce damaging and dangerous stresses in the disk and its teeth when the disk engages the tree to be cut or, even more seriously, engages stones or bed-rock.
One known device (see Canadian Pat. No. 1,140,029 issued Jan. 25, 1983 to A. Larose) employs two saws in stacked relation to each other with enough space between the saws to support and drive them with a chipping element being disposed between the blades to clear the kerf. The saw is driven at a high speed and not protected and therefore subject to damage. Such arrangement, however, is somewhat more compact in diameter than other known devices because the saws are supported and driven by means between the saw blades thus leaving the upper and lower faces clear, resulting in that the saw diameter need only be somewhat larger than the largest tree to be cut. The penalty in this solution is in the width of the kerf which must be large enough to permit passage of the two saws and the supporting and driving mechanism between them. The kerf is so wide that the wood loss to sawdust is roughly the same as that damaged by shears. This wood can not be used for pulp as it is sheared wood and left behind in the forest. This solution, by some, is felt to be a retrogressive step in the art.
In summary, the known devices for cross-cutting trees, particularly the felling cut, are fragile in relation to the environment where they must work, some of them being dangerously so because of their fly-wheel characteristics. Most of them are excessively bulky, and the centrally driven double saw blade that is not, produces an unacceptable kerf loss.
SUMMARY OF INVENTION
The general purpose of the present invention is to provide a tree felling head having a circular cross-cutting saw and which overcomes the disadvantages of presently known devices. This is accomplished by utilizing a cutting disk, i.e. a circular saw blade, supported and driven at or near the other rim. The arrangement is compact as the saw disk (or blade) need only be slightly larger than the largest tree to be cut. The single blade is almost fully supported by the rim thereof and the cutting forces act directly along the rim. It can therefore be thin enough to produce small kerf widths similar to those of conventional chain saws and at the same time be sturdy enough to support cut trees.
The disk-saw can be operated over a wide range of speeds through the choice of a suitable bearing and drive arrangement. In the present proposal the preferred embodiment is a low speed arrangement which avoids the damage and danger potential of high speed disks. The required power is applied through a high-torque, low speed motor of sufficient power to effect the severing and to overcome, in most cases, pinching forces exerted by leaning trees.
Teeth are bolted to the disk thus permitting a wide variety of tooth patterns for different conditions and easy replacement of damaged or dull teeth.
The feed speed is controllable for best application of the cutting power and controlling the quality of the cut.
The pinion may be cut back at the root of the teeth to provide some self-cleaning.
Air also can be used in two ways with the present apparatus. It can be jetted onto the driving and bearing surfaces to keep them clean and it can be introduced into the bearing cavity where, in conjunction with self-lubricating bearing material, will permit much higher rotational speeds if desired.
BRIEF DESCRIPTION OF DRAWINGS
The invention is illustrated by way of example with reference to the accompanying drawings wherein:
FIG. 1 is a plan view of the severing device shown attached to the base of a felling head illustrated in part by broken line;
FIG. 2 is a partial, enlarged, detailed plan view of the disk-saw showing the drive arrangement and the replaceable teeth;
FIG. 3 is a sectional view of the disk-saw taken essentially along line 3--3 of FIG. 1 showing the drive and bearing arrangements and the pinion self-cleaning modifications;
FIG. 4 is a plan view similar to FIG. 2 but illustrating an alternative drive arrangement employing some chain drive technology;
FIG. 5 is a sectional view of the bearing and drive taken along line 5--5 of FIG. 4;
FIG. 6 is a sectional view of the bearing and drive showing a ball bearing alternative to the metal bearings of FIG. 3 and FIG. 5;
FIG. 7 is a partial plan view of a modified gear tooth and cutting tooth arrangement;
FIG. 8 is a right hand elevational view of FIG. 7; and
FIG. 9 is a view similar to FIG. 8 but with the cutting tooth rotated to a different position and
FIG. 10 is a diagrammatic side elevational view of a tree felling head.
DESCRIPTION OF PREFERRED EMBODIMENT
Referring to FIG. 1, there is illustrated, partly in broken line, the outline of the base portion 10 of a felling head having a rim drive severing device mounted thereon and provided in accordance with the present invention. The base portion of the felling head is of the type disclosed in Canadian Pat. No. 1,103,130 issued June 16, 1981 to my company, Logging Development Corporation, or Canadian Pat. No. 1,065,742 issued Nov. 6, 1979. The felling head includes grapple arms 10A and 10B at least one of which is pivotally mounted and together provide a grapple jaw for grasping a standing tree. The grapple is mounted on a frame and the severing device is mounted on such frame below the grapple. The grapple arms are moved by a means designated 10C. It will, however, be obvious to anyone skilled in the art that the principles disclosed herein can be applied to any felling head and to other cross-cutting devices as well as those employed for cross-cutting on tree processors.
The severing device has a frame 13 (also referred to as an arm) pivotally attached to the base of the felling head by a pin 11 and is controllably moved by a hydraulic cylinder unit 12 connected thereto. A rotary cutting device 14 (i.e. a circular disk) is mounted on the outer end of frame 13 (in a manner to be described hereinafter) and is driven by a motor 15 through pinion gear 16 which mates with gear teeth 17 adjacent the outer periphery of the rotary disk 14. Cutting teeth 18 (or abrading elements) are mounted (preferably detachably) on the outer end of gear teeth 17. The rotary cutter 14 is supported adjacent the outer periphery thereof by suitable bearings in a part circular portion 13A on the outer end of arm 13. The part circular portion 13A is U-shaped in cross-section providing a curved channel that receives a portion of the saw disk around a portion of the periphery of the cutting disk. Actuation of the cylinder 12 pivots the arm 13 about the pin 11 and moves the rotary cutter 14 toward and away from a sharp edged arcuate anvil 29 on the frame of the felling head. A tree to be severed is placed between the rotary cutter and the arcuate anvil 29 and the arm is controllably moved at an appropriate speed toward the anvil so as to cut the tree.
FIG. 2 illustrates in greater detail the drive motor 15 and gear or pinion 16 driven thereby, meshing with gear teeth 17 on the rotary cutter. The cutting or abrading elements 18 are shown detachably attached to the tips of the two adjacent gear teeth 17 by threaded studs 19. The gear teeth 17 are preferably of the Face gear type and the pinion 16 is preferably a Spur gear suitably proportioned to mesh with the Face gear teeth.
FIG. 3 is a sectional view at the point of gear contact illustrating bearing support elements 20A and 20B for supporting and guiding the rotary cutter and sealing elements 21 located on opposite sides of each of the bearing to retain lubricant and exclude contamination. The bearing 20B on the upper surface of the circular cutter 14 engages the flat side face of the cutter and it will be noted on the lower surface of the bearing 20A projects into a groove 20C in the lower side face of the cutter. The bearings 20A and 20B are mounted in the curved channel of the arm portion 13A which is U-shaped in cross-section and extends essentially along the full length of the part circular housing. The bearings are curved so as to be part circular with a radius of curvature about the center point of the circular cutting disk. Also in this embodiment, it will be noted gear teeth of pinion gear 16 are cut back as indicated at 16B, the purpose of which is to have a self-cleaning effect as the pinion gears mesh with the gear teeth 17.
In FIGS. 4 and 5 there is illustrated an optional drive arrangement wherein roller assemblies 23 replace the Face gear teeth 17 and sprocket 24 with special gear teeth replaces the Spur gear 16. The rollers 23 are retained in position by a retaining ring 25 held in place by cutting elements 26 attached to the circular disk 14 by cap screw elements 27. It will be noted the cutting elements 26 illustrated are different from the cutting elements 18 in that two cutting projections 26A are provided rather than a single cutting element shown in FIG. 1. In most instances, the two adjacent cutting teeth 26A would be offset in opposite directions relative to the plane of the disk, and offset sufficiently to provide a kerf wider than the thickness of the disk as is normal with any cutting blade.
FIG. 5 is a sectional view taken along line 5--5 of FIG. 4 illustrating the point of contact of the drive from which it can be seen the cutting projections 26A of the teeth are offset and positioned around the outer periphery of the ring 25 which retains rollers 23 on projections or on studs secured to the disk 14.
FIG. 6 is a cross-sectional view taken essentially along line A--A of FIG. 1, but illustrating a modified bearing arrangement to support the rotary disk 14. In FIG. 6 there is illustrated a circulating ball bearing assembly 28 which will permit much higher rotational speeds of the cutter 14 than possible with metal bearings designated 20A and 20B in FIGS. 3 and 5. While the circulating ball bearing assembly 28 is illustrated only on a lower surface, it could optionally be used on the upper surface or both.
In the rotary cutter illustrated in the foregoing embodiments, the cutting teeth are secured to two adjacent gear teeth on the outer periphery of the disk which mesh with the pinion gear. Referring to FIGS. 7 to 9 inclusive, there is illustrated a single cutting tooth 30 mounted individually on each of the gear teeth 17 on the cutting member 14. The cutting tooth member 30 consists of a stem 31 projecting into a hole or recess 17A in gear tooth 17 and retained in position by a pin 32. On the outer end of stem 31 is a member 33 appropriately shaped with cutting edges for cutting wood. The shaft 31 is preferably circular, fitting into a cylindrical hole 17A in the tooth 17 and the material and/or size of pin 32 is appropriately chosen so as to be a shear pin in the event cutting member 33 encounters unusual or impact forces during cutting, for example, striking a stone rather than cutting through wood. The cutting part 33 of members 30 are oppositely directed on adjacent gear teeth on the ring cutting member so as to cut a kerf of sufficient width to clear the circular plate 14. FIG. 8 illustrates one tooth facing in one direction and in dotted line the next adjacent tooth is illustrated facing the opposite direction.
In this embodiment, as illustrated in FIG. 9, the cutting portion 33 may be positioned differently so as to provide the appropriate cutting action dictated by the requirements at the time. In order to do this in place of shear pin 32, a set screw or set screws may be utilized to retain the shaft 31 at an appropriate position. It will, of course, be understood the stem may be pre-drilled for the appropriate angle required or pre-drilled at different positions permitting setting the teeth at different predetermined angles. | 4y
|
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of pending U.S. application Ser. No. 09/552,564 filed on Apr. 19, 2000, and U.S. Ser. No. 10/890,199, filed on Jul. 14, 2004.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of communication networks, and, more specifically, to the networking of devices within a building via combined wired and non-wired communication.
BACKGROUND OF THE INVENTION
[0003] There is a growing need for networking within the home. This need is driven by two major factors, the increasing use of multiple data devices and the emergence of broadband services in the home.
[0004] Lately there has been an expansion in the number of homes in the USA with multiple personal computers. In addition, connectivity and networking capabilities have been added to appliances, such as refrigerators and microwave ovens. Furthermore, there is a trend toward enabling data connectivity among various multimedia (audio and video) appliances such as TV's, VCR's, receivers, and speakers. The term “data unit” as used herein denotes any device capable of generating and/or receiving data. The networking of data units enables the sharing of files and applications as well as the sharing of common peripheral devices, along with other benefits.
[0005] Another driving force behind the need for home connectivity products is the growth in the number of on-line households. As high-speed connections to information and broadband entertainment sources soar, there is a growing need to share and distribute this access among appliances within the house. These broadband services are supplied mainly by three types of service providers:
1. Telco's, via xDSL connections (currently ADSL, to be followed by VDSL). 2. CATV. Currently via Cable-Modem, to be followed by digital Set-Top-Box. 3. Wireless connections, such as Satellite, LMDS, WLL, and others.
[0009] Communication within a home can be classified into two types: wired and non-wired. These are covered below:
[0000] Wired Communication
[0010] Wired communication requires using at least two distinct electrical conductors. The wiring can be new wiring installed and dedicated for data communication within the home, such as installing structured wiring such as Category 5 type, used in Ethernet IEEE802 networks. However, the installation of a new wiring structure within a home is labor-intensive, complex, and expensive. Alternatively, existing home wiring, which was previously installed for a specific purpose, can be used for data communication without substantially affecting or degrading the original service. Existing wiring includes telephone wiring, power line wiring, and cable TV wiring. These are reviewed below.
[0011] For all wired configurations, the present invention relies upon electrically-conducting lines which may be pre-existing within a building, which have at least two distinct electrical conductors, and which are capable of transporting data communication signals. Furthermore, the present invention relies upon suitable outlets, to which the electrically-conducting lines are coupled, and which are capable of connecting to external devices.
[0000] Telephone Wiring
[0012] In-home telephone service usually employs two or four wires, and is accessed via telephone outlets into which the telephone sets are connected.
[0013] FIG. 1 shows the wiring configuration of a prior-art telephone system 10 for a residence or other building, wired with a telephone line 5 . Residence telephone line 5 consists of single wire pair which connects to a junction-box 16 , which in turn connects to a Public Switched Telephone Network (PSTN) 18 via a cable 17 , terminating in a public switch 19 , which establishes and enables telephony from one telephone to another. The term “analog telephony” as used herein denotes traditional analog low-frequency audio voice signals typically under 3 KHz, sometimes referred to as “POTS” (“Plain Old Telephone Service”), whereas the term “telephony” in general denotes any kind of telephone service, including digital service such as Integrated Services Digital Network (ISDN). The term “high-frequency” as used herein denotes any frequency substantially above such analog telephony audio frequencies, such as that used for data. ISDN typically uses frequencies not exceeding 100 KHz (typically the energy is concentrated around 40 Khz). The term “telephone line” as used herein denotes electrically-conducting lines which are intended primarily for the carrying and distribution of analog telephony, and includes, but is not limited to, such electrically-conducting lines which may be pre-existing within a building and which may currently provide analog telephony service. The term “telephone device” as used herein denotes, without limitation, any apparatus for telephony (including both analog telephony and ISDN), as well as any device using telephony signals, such as fax, voice-modem, and so forth.
[0014] Junction box 16 is used to separate the in-home circuitry from the PSTN and is used as a test facility for troubleshooting as well as for wiring new in the home. A plurality of telephones 13 a and 13 b connects to telephone lines 5 via a plurality of telephone outlets 11 a, 11 b, 11 c, and 11 d. Each outlet has a connector (often referred to as a “jack”), denoted in FIG. 1 as 12 a, 12 b, 12 c, and 12 d, respectively. In North-America, RJ-11 is commonly used. Each outlet may be connected to a telephone unit via a connector (often referred to as a “plug”), denoted in FIG. 1 (for the two telephone units 13 a and 13 b illustrated) as 14 a and 14 b, respectively. It is also important to note that lines 5 a, 5 b, 5 c, 5 d, and 5 e are electrically the same paired conductors.
[0015] While network 10 exhibits serial or daisy-chained topology wherein the wiring is serialized from an outlet the next one only, other topologies such as star, tree or any arbitrary topology may also exist. However, the telephone wiring system within a residence is always composed of wired media: two or four copper wires, and several outlets which provides direct access for connecting to these wires.
[0016] There is a requirement for simultaneously using the existing telephone infrastructure for both telephone and data networking. In this way, the task of establishing a new local area network in a home or other building is simplified, because there would be no additional wires to install. U.S. Pat. No. 4,766,402 to Crane (hereinafter referred to as “Crane”) teaches a way to form LAN over two-wire telephone lines, but without the telephone service.
[0017] As an another example, relevant prior-art in this field is disclosed in U.S. Pat. No. 5,896,443 to Dichter (hereinafter referred to as “Dichter”). Dichter suggests a method and apparatus for applying frequency domain/division multiplexing (FDM) technique for residential telephone wiring, enabling simultaneously carrying telephone and data communication signals. The bandwidth enabled by the wiring is split into a low-frequency band capable of carrying an analog telephony signal and a high-frequency band capable of carrying data communication signals. In such mechanism, the telephone service is not affected, while data communication capability is provided over existing telephone wiring within a home.
[0018] The concept of frequency domain/division multiplexing (FDM) is well-known in the art, and provides means of splitting the bandwidth carried by a wire into a low-frequency band capable of carrying an analog telephony signal and a high-frequency band capable of carrying data communication or other signals. Such a mechanism is described, for example, in U.S. Pat. No. 4,785,448 to Reichert et al. (hereinafter referred to as “Reichert”). Also widely used are xDSL systems, primarily Asymmetric Digital Subscriber Loop (ADSL) systems.
[0019] The Dichter network is illustrated in FIG. 2 , which shows a network 20 serving both telephones and providing a local area network of data units. Data Terminal Equipment (DTE) units 24 a, 24 b, and 24 c are connected to the local area network via Data Communication Equipment (DCE) units 23 a, 23 b, and 23 c, respectively. Examples of Data Communication Equipment include modems, line drivers, line receivers, and transceivers (the term “transceiver” herein denotes a combined transmitter and receiver). DCE units 23 a, 23 b, and 23 c are respectively connected to high pass filters (HPF) 22 a, 22 b, and 22 c. The HPF's allow the DCE units access to the high-frequency band carried by telephone-line 5 . In a first embodiment (not shown in FIG. 2 ), telephones 13 a, 13 b, and 13 c are directly connected to telephone line 5 via connectors 14 a, 14 b, and 14 c, respectively. However, in order to avoid interference to the data network caused by the telephones, in a second embodiment (shown in FIG. 2 ) low pass filters (LPF's) 21 a, 21 b, and 21 c are added to telephones 13 a, 13 b, and 13 c from telephone line 5 . Furthermore, a low pass filter is also connected to Junction Box 16 , in order to filter noises induced from or to the PSTN wiring 17 . It is important to note that lines 5 a, 5 b, 5 c, 5 d, and 5 e are electrically the same paired conductors.
[0020] Additional prior-art patents in this field can be found under US Class 379/093.08, which relates to carrying data over telephone wiring without any modifications made to the telephone wiring (e.g. wires and outlets). U.S. Pat. No. 5,841,360 and U.S. patent applications Ser. Nos. 09/123,486 and 09/357,379 to the present inventor are the first to suggest modifying the telephone wiring, by means of splitting the wiring into distinct segments, each of which connects two telephone outlets. In this way, the network is modified from ‘bus’ topology into multiple ‘point-to-point’ segments, enabling superior communication characteristics.
[0021] Part of such a network 30 is shown in FIG. 3 , describing outlets 31 a and 31 b, substituting outlets 11 of FIGS. 1 and 2 . The telephone wiring 5 is split into distinct segments 5 a, 5 b and 5 c. Low-Pass Filter (LPF) and High-Pass Filters (HPF) are coupled to each wire segment end, in order to split between the telephony and the data signals. As shown in FIG. 3 , LPF's 21 b and 21 c are attached to each end of wiring segment 5 b. The LPF's are designed to allow passing of the telephony signals, and are connected together thus offering a continuous path for the telephony signals. Access to the telephony signals is made via connectors 12 a and 12 b in the outlets, into which telephone devices 13 a and 13 b are connected via connectors 14 a and 14 b respectively. Thus, the telephony service is fully retained. The data signals, carried in the high part of the spectrum, are accessed via HPF's 26 a and 22 b, coupled to each end of the telephone wire segment 5 b. HPF's 22 a and 26 b are connected to the ends of the wire segments 5 a and 5 c respectively. Each HPF is connected to a modem 23 and 27 , which transmit and receive data signals over the telephone wiring. Modems 23 a, 27 a, 23 b, and 27 b are connected to HPF's 22 a, 26 a, 22 b and 26 b respectively. Data units 24 a and 24 b are connected to the outlets 31 a and 31 b respectively, via a connector (not shown in the Figure) in the outlet. The data units are coupled via DTE interface in the outlet. Outlets 31 a and 31 b comprise DTE interfaces 29 a and 29 b respectively. The three data streams in each outlet, two from each modem and one from the DTE, are handled by an adapter 28 a and an adapter 28 b, which serve outlets 31 a and 31 b, respectively. While FIG. 3 describes an embodiment wherein all the components for the relevant functions are housed within the outlet, other embodiments are also possible, wherein only some of the components for these functions are contained within the outlet.
[0000] Power Lines
[0022] It is possible to transmit data over wiring used for distribution of electrical power within the home, which is normally at a frequency of 50 or 60 Hz. Access to the power is available via power outlets distributed around the house. Such wiring consists of two wires (phase and neutral) or three wires (phase, neutral, and ground).
[0023] FDM techniques, as well as others, are used for enabling data communication over power lines. Many prior-art patents in this field can be found in US Class 340/310.
[0000] Cable Television Lines
[0024] It is also possible to transmit data over wiring used for the distribution of television signals within the home. Such wiring usually is coaxial cable.
[0025] Both power line and cable television wiring systems resemble the telephone line structure described in FIG. 1 . The wiring system is based on conductors, usually located in the walls, and access to these wires is obtained via dedicated outlets, each housing a connector connected directly to the wires. Common to all these systems, is the fact that the wiring was installed for a dedicated purpose (telephone, power, or cable TV signal distribution). Wherever one of these existing wiring systems is used for carrying data, it is desirable that the original service (telephony, power, or television signal distribution) be unaffected. Dedicated modems are used for carrying data over the media concurrently with the original service.
[0026] When using existing wiring, specific wired modems are normally required for communicating over the electrically-conducting lines, and access to the electrically-conducting lines is provided via the relevant outlets. Using electrically-conducting lines as the communication media allows for high bandwidth, and provides robust and cost-effective communication. In addition, communication over large distances is possible, which in most cases enables coverage of the whole house, thereby guaranteeing communication from any outlet to another within the house.
[0027] Such networks, however, require data units to be connected to the outlets, usually by means of a cable from the data unit to a suitable nearby outlet. This makes the connection complex and hard-to-use, requires the data unit to be in proximity to an appropriate outlet, and impairs mobility for some data units within the house.
[0000] Non-Wired Communication
[0028] Non-wired solutions for in-home data networking use waves propagated without an electrically-conducting medium. Three main techniques are commonly used:
1. Radio Frequency (RF). Transmission of data between data units can be accomplished with radio frequency electromagnetic signals. As an example, IEEE802.11 can be used. 2. Light. Transmission of data between data units can be accomplished with light in the visible or non-visible spectrum. Currently, the most popular is infrared (IR) based communication. Most such systems require ‘line-of-sight’ placement of the communicating data units. 3. Sound. Transmission of data between data units can be accomplished with sound waves, either in the audio spectrum (20-20,000 Hz), or inaudible spectrum (ultrasonic, above 20,000 Hz; or infrasonic, below 20 Hz).
[0032] It is noted that although light and radio waves are both electromagnetic phenomena, they occupy different parts of the electromagnetic spectrum and have significantly different characteristics for purposes of the present invention. Thus, light and radio waves are herein treated as distinct physical phenomena.
[0033] An example of a non-wired data network 40 is shown in FIG. 4 . Two data units 41 a and 41 b are shown, into which non-wired transceivers 42 a and 42 b are respectively coupled. The non-wired transceivers 42 a and 42 b communicate over a space 43 without any electrically-conducting medium. If RF transmission is used, the transceivers are RF transceivers, and the communication over space 43 is based on the propagation of radio frequency electromagnetic waves. Similarly, in the case of light-based communication, transceivers 42 a and 42 b utilize light emitters (e.g. LEDs) and light detectors (e.g. photoelectric cell), and the communication over space 43 relies on the propagation of light. Likewise, in the case of sound-based communication over space 43 , the transceivers use microphones and speakers, and the communication relies on the propagation of sound waves through the air in the space 43 .
[0034] Since these solutions do not require any physical connection such as cable, they provide both ease-of-use and mobility. However, such non-wired solutions are effective over short distances only. Furthermore, most of the non-wired solutions cannot easily pass through walls and other such obstructions, owing to the attenuation to the signals. Hence, such techniques are suitable for communication within a single room, but are not suitable for communication between the rooms of a home or other building.
[0035] There is thus a widely recognized need for, and it would be highly advantageous to have, a means for implementing a data networking in-home between data units, wherein such data units can be networked within a home or other building, while providing mobility and ease of use. This goal is met by the present invention.
SUMMARY OF THE INVENTION
[0036] The present invention discloses a data communication network within a building having wired and non-wired segments. The wired segments are based on electrically-conducting lines installed within the building. In addition to supporting data communication, these electrically-conducting lines concurrently distribute a primary service other than the transport of data communication signals, such as telephone service, electrical power service, or cable television service, and may be pre-existing wires originally-installed to distribute the primary service. Dedicated outlets are used to enable direct access to the wiring. The present invention uses means for utilizing the electrically-conducting lines concurrently for both the transport of data communication signals and the primary service, without any interference between these two uses. The non-wired segments employ communication without electrically-conducting media, via waves propagated through open space, such as by light or radio waves, or by acoustic waves in air.
[0037] The wired and non-wired segments are combined by means of circuitry in one or more outlets. The coupling device is a module containing one port for coupling to the wired network using a specific wired modem. Another port of the device couples to the non-wired segment, using a non-wired modem. An adapter handles the data flow between the wired segment and the non-wired segment, and has provision for protocol conversion, if required.
[0038] The module coupling both segments, or any of the components of the module, can be fully integrated into the outlet, partially integrated into the outlet, or externally coupled to it.
[0039] Therefore, according to the present invention there is provided a local area network within a building for transporting data among a plurality of data units, the local area network including at least one wired segment and at least one non-wired segment, wherein the at least one wired segment includes: (a) at least one electrically-conducting line within the building, the electrically-conducting line having at least two conductors and operative to transport data communication signals; (b) at least two outlets, each operative for coupling to the electrically-conducting line; and (c) at least one wired modem coupled to the electrically-conducting line, operative to communicate over the electrically-conducting line; (d) and wherein the at least one non-wired segment is operative to communicating data without electrically-conducting media and includes at least one non-wired modem, wherein at least one of the outlets couples a wired segment to a non-wired segment, and wherein the at least one electrically-conducting line is furthermore operative for concurrently distributing a service other than the transport of data communication signals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0040] The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein:
[0041] FIG. 1 shows a common prior art telephone line-wiring configuration for. a residence or other building.
[0042] FIG. 2 shows a first prior art local area network based on telephone line wiring for a residence or other building.
[0043] FIG. 3 shows a second prior art local area network based on telephone line wiring for a residence or other building.
[0044] FIG. 4 shows a prior art non-wired communication network.
[0045] FIG. 5 shows modules according to the present invention.
[0046] FIG. 6 shows a local area network according to the present invention, wherein telephone wiring used for the wired segment and radio-frequency communication for the non-wired segment.
[0047] FIG. 7 shows a second embodiment of a local area network based on telephone lines as the wired segment and radio frequency communication for the non-wired segment.
[0048] FIG. 8 shows a kit for upgrading existing electrically-conducting lines to support a network according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0049] The principles and operation of a network according to the present invention may be understood with reference to the drawings and the accompanying description. The drawings and descriptions are conceptual only. In actual practice, a single component can implement one or more functions; alternatively, each function can be implemented by a plurality of components and circuits. In the drawings and descriptions, identical reference numerals indicate those components that are common to different embodiments or configurations.
[0050] The invention is based on a wired/non-wired network adapter module (hereinafter referred to as “module”). A functional description of such a module 50 is shown in FIG. 5 . The module comprises a physical port 54 for connecting to the wired network. The communication with the wired network is carried by wired transceiver 51 . Wired transceiver port 54 and transceiver 51 are dependent upon the type of wired network. Interfacing a telephone line-based network requires a telephone line transceiver, while connecting to a power line network requires a power line dedicated modem. Additionally, the connection to the wired network may require specific means in order to meet regulatory and safety requirements, as well as specific means for ensuring that the basic service (e.g. telephony service, power distribution) is not substantially degraded or affected.
[0051] The non-wired segment interfaces via a port 55 . Port 55 communicates without an electrically conducting medium. Communication with this non-wired segment is handled by a non-wired modem/transceiver 53 . The term “non-wired modem” herein denotes any device capable of data communication without requiring an electrically conducting medium. The data to and from the wired segment and the data to and from the non-wired segment are handled by a protocol adapter 52 . Protocol adapter 52 may serve as a transparent unit, acting as a repeater/regenerator, dealing with the physical layer only of the OSI model. However, higher layers can also be handled by the protocol adapter 52 . In such a case, the protocol adapter will function as a bridge, router, gateway or any other adaptation mechanism as required.
[0052] Other facilities of module 50 may contain logic, control, processing, storage, power-supply and other components not shown in FIG. 5 . The communication supported by module 50 can be simplex (unidirectional, either from the wired towards the non-wired segment or vice-versa), half-duplex, or full duplex. A module 50 a connects a telephone line network segment to an RF network segment. Module 50 a employs a telephone line modem 51 a as the wired network interface, a radio-frequency modem 53 a as an interface to the non-wired network segment, and a protocol adapter 52 a. A module 50 b is an embodiment of the present invention, in which the telephone line transceiver can be implemented by a high-pass filter (HPF) 22 a and data terminal equipment (DCE) 23 a, as also used by Dichter as discussed previously.
[0053] FIG. 6 shows an embodiment of a network 60 according to the present invention that includes wired and non-wired segments. The wired segment is based on telephone wiring 5 within a building as described in FIG. 1 . While outlets 11 b and 11 c are unchanged, outlets 11 a and 11 d are replaced by outlets 61 d and 61 a, respectively, containing modules 50 d and 50 e respectively. Basic telephone service is retained by employing low-pass filters (LPF) 21 d and 21 a in outlets 61 d and 61 a respectively. The LPF's are coupled to telephone connectors 12 d and 12 a respectively, enabling connection of telephone devices. This is illustrated by a telephone 13 a connected by connector 14 a to connector 12 a in outlet 61 a. A Dichter-type data communication network is established by connecting data terminal equipment (DTE) via a modem and HPF, as illustrated by DTE 24 b connected to DCE 23 b, which is coupled to HPF 22 b, which is in turn directly coupled to telephone wiring 5 via connector 12 b in outlet 11 b.
[0054] The non-wired part of network 60 is based on radio frequency transmission, utilizing a pair of RF transceivers 53 ( FIG. 5 ). As shown in FIG. 6 , DTE's 24 d and 24 a are coupled to RF transceivers 53 c and 53 b, respectively. In turn, each such RF transceiver communicates with RF transceivers 53 d and 53 a, respectively, which are integrated within outlets 61 d and 61 a, respectively.
[0055] Integrating the wired and non-wired segments of the network is accomplished by modules 50 d and 50 e, each of which is illustrated by module 50 c in FIG. 5 . Modules 50 d and 50 e are integrated within outlets 61 d and 61 a, respectively. Each such module interfaces the wired segment of the network by a telephone modem. Each such modem contains a high-pass filter 22 and DCE 23 , as described previously for a Dichter-type network. Interfacing to the non-wired segment of network 60 is performed via an RF transceiver, wherein modules 50 d and 50 e comprises RF transceivers 53 d and 53 e respectively. Protocols and data conversion between both segments are performed by adapter 52 ( FIG. 5 ), wherein adapters 52 d and 52 e are integrated within modules 50 d and 50 e respectively.
[0056] Network 60 allows DTE's 24 d, 24 b and 24 a to communicate among themselves. While DTE 24 b is connected to the network via a wired connection, DTE's 24 d and 24 a can communicate in a non-wired manner. While FIG. 6 illustrates a single DTE connected by wires and two DTE's connected without wires, it is obvious that any number of DTEs of each type can be connected. Furthermore, while in network 60 each outlet supports a single wired or non-wired DTE connection, other implementations can also be supported. For example, an outlet can provide one or more wired connections simultaneously with one or more non-wired connections.
[0057] While FIG. 6 illustrates the case where module 50 is integrated in an outlet 61 , embodiments of the present invention also include those wherein the module is external to the outlet. Similarly, selective parts of a module may be integrated within an outlet while other parts are external. In all cases, of course, appropriate electrical and mechanical connection between the module and the outlet are required.
[0058] A network outlet is physically similar in size, shape, and overall appearance to a standard outlet, so that a network outlet can be substituted for a standard outlet in the building wall. No changes are required in the overall telephone line layout or configuration.
[0059] Network 60 provides clear advantages over hitherto proposed networks. For example, DTEs (e.g. PC's) located in different rooms can interconnect without the need to use any wires. A radio-frequency transceiver in each DTE communicates with the nearest outlet, and the outlets communicate between rooms over the telephone wiring media.
[0060] The invention can equally well be applied to the prior art wired network illustrated in FIG. 3 . FIG. 7 shows part of a network 70 . Outlet 31 a represents a prior-art network outlet. In order to interface to the non-wired network segments, an outlet 71 according to the present invention must be used. With the exception of RF transceiver 53 a within outlet 71 , which communicates with RF transceiver 53 b connected to a DTE 24 a, outlet 71 is similar to outlet 31 a. In this embodiment, the module includes two telephone line modems 23 b and 27 b, a three-port adapter 72 (for the two wired ports and the single non-wired port), and RF transceiver 53 a. The advantages offered by the prior-art topology apply also for this configuration.
[0061] While the present invention has been described above for the case where the wired media is based on a telephone line system and includes telephone wires and telephone outlets, the present invention can equally well be applied to other wired systems such as those based on power and cable television signal distribution. In the case of an electrical power distribution system, the electrical wires and outlets employed for power distribution in the house are used. Similarly, cable television wiring and outlets can also be used. In all cases, it may be necessary to retain the basic service for which the wiring systems were installed: telephony service, electrical power distribution, or television signals. This is usually achieved by adding the appropriate circuitry to separate the data communication network from the basic service, as well as to avoid interference of any kind between the two roles currently employing the same wiring. For example, the LPF's 21 a, 21 b, 21 c, and 21 d; and HPF's 22 a, 22 b, 26 a, and 26 b ( FIG. 7 ) serve the role of separating the telephony service from the data communication network and vice-versa.
[0062] While the present invention has been described above for the case wherein the non-wired communication is accomplished by radio-frequency transmission, the present invention can be equally applied to other types of non-wired communication, such as:
1. Non-wired communication accomplished by other forms of electromagnetic transmission. Electromagnetic waves in various parts of the electromagnetic spectrum can be used for communication. For example, low-frequency electromagnetic radiation can be used to transmit audio-frequency signals over short distances without a carrier. Radio-frequency transmission is a special case of this general electromagnetic transmission. As noted previously, light is also a special case of electromagnetic radiation, but is herein treated separately because of the characteristics of light are distinctly different from those of electromagnetic transmission in other usable parts of the electromagnetic spectrum. 2. Non-wired communication accomplished by light. Either visible or non-visible light wavelength can be used for such transmission. As previously noted, currently, the most popular is infrared (IR) based communication. Most such systems require substantially ‘line-of-sight’ access. 3. Non-wired communication accomplished by sound. Either audible sound (20-20,000 Hz band), or inaudible sound (ultrasonic, above 20,000 Hz; or infrasonic, below 20 Hz).
[0066] In addition to the described data communication function, the network according to the present invention can also be used for control (e.g. home automation), sensing, audio, or video applications, and the communication can also utilize analog signals (herein denoted by the term “analog communication”). For example, a video signal can be transmitted in analog form via the network.
[0000] Upgrade Kit
[0067] The present invention also contemplates a kit for upgrading existing electrically conducting lines to support a network as described above. FIG. 8 illustrates an embodiment of such a kit containing an outlet 132 and an outlet 134 and installation instructions 136 . Outlet 132 has connection 144 for coupling to a wired segment and mounting points such as a flange 146 for installing in the building walls. Outlet 132 also has a jack 138 and a jack 140 for connecting to external devices via cables, and a transducer 142 for connecting to external data units via a non-wired segment. Within outlet 132 is a module according to the present invention, as previously described and illustrated in FIG. 5 . In one embodiment, transducer 142 is a radio frequency transceiver. In another embodiment, transducer 142 is a combined light-emitting diode and photocell receiver. In still another embodiment, transducer 142 is a combined speaker and microphone. Likewise, in one embodiment, jack 138 is a telephone jack. In another embodiment, jack 138 is an electrical power socket. In still another embodiment, jack 138 is a cable television jack. In one embodiment, jack 140 is a data jack. The embodiment of the kit illustrated in FIG. 8 has two outlets, outlet 132 and outlet 134 , which are illustrated as substantially identical. However, in another embodiment, the kit contains only outlet 132 . In still another embodiment, outlet 134 does not contain a transducer. Other variations are also possible in different embodiments.
[0068] It will also be appreciated that the outlet and the adapter module may be provided as separate components for use in upgrading existing wiring of a building to support a local area network having at least one wired segment and at least one non-wired segment. They may likewise find independent use for further expanding a hybrid network that has previously been upgraded according to the invention. Such an outlet is provided with a first coupler for coupling the outlet to the at least one non-wired segment, and a second coupler for coupling the outlet to the existing wiring via an adapter module. The adapter module may be either fully or partially integrated within the outlet.
[0069] A method for upgrading existing electrically conducting lines within a building to support a network according to the present invention involves:
(a) providing a wired modem; (b) providing a non-wired modem; (c) providing an adapter for handling the data communications between a wired segment and a non-wired segment; and (d) providing an outlet, and (e) equipping the outlet with the wired modem, the non-wired modem, and the adapter.
[0075] While the invention has been described with respect to a limited number of embodiments, it will be appreciated that many variations, modifications and other applications of the invention may be made. | 4y
|
BACKGROUND OF THE INVENTION
[0001] This invention relates generally to electrical switchgear and more particularly, to electrical and electronic instruments for monitoring the performance of electrical switchgear.
[0002] In an industrial power distribution system, power generated by a power generation company may be supplied to an industrial or commercial facility wherein the power is distributed around the industrial or commercial facility to various equipment such as, for example, motors, welding machinery, computers, heaters, lighting, and other electrical equipment. At least some known, power distribution systems include switchgear which facilitates dividing the power into branch circuits which supply power to various portions of the industrial facility. Circuit breakers are provided in each branch circuit to facilitate protecting equipment within the branch circuit. Additionally, circuit breakers in each branch circuit can facilitate minimizing equipment failures since specific loads may be energized or deenergized without affecting other loads, thus creating increased efficiencies, and reduced operating and manufacturing costs. A similar selecting tripping situation applies within electric utility system transmission and distribution substations, although the switching operations used may be more complex.
[0003] At least some known circuit breakers utilize electronic circuitry to monitor a level of current passing through the branch circuits, and to trip the breaker when the current exceeds a pre-defined value. Electronic circuit breakers are adjustable depending on the particular application, and may include a protection module that is coupled to one or more current sensors. The protection module continuously monitors digitized current values using curves which define permissible time frames in which both low-level and high-level overcurrent conditions may exist. For example, if an overcurrent condition has been maintained for longer than its permissible time frame, the breaker is tripped. Accurate current readings may be affected by the measuring instruments themselves. More specifically and for example, current transformer (CT) saturation may cause errors even when low-burden static relays are used.
[0004] At least some known circuit breakers use protection modules to monitor and control other types of faults, such as over or under voltage conditions and phase loss or imbalances. Such protection modules also require instrument sensors to translate raw electrical signals into conditioned signals which are usable by breaker protection modules. Accuracy in the measurement of the electrical parameters is important to ensure power design limits are not being exceeded while still maintaining equipment in service during transient conditions. To facilitate improved accuracy, high quality and stable components may be used in the construction of protective instrumentation. However, such components increase production costs. Another technique used is to compensate for known or estimated errors in the measurement ability of an instrument system. Once errors are quantified a countervailing circuit is introduced to balance the errors out of the system. However, this technique is often difficult to maintain and may lead to greater errors or less predictable errors being introduced into the system.
BRIEF DESCRIPTION OF THE INVENTION
[0005] In one aspect, a method for operating an electrical apparatus is provided. The method includes mounting an instrument transformer proximate a load current carrying conductor, wherein the instrument transformer includes a current transformer for supplying an analog input signal proportional to a load current, the current transformer is coupled to a relay front-end module that includes a current-to-voltage converter circuit and is configured to couple to a remote protection module, converting the analog input signal to a digital input signal, transmitting the digital input signal to the remote protection module; and activating contacts to operate the electrical apparatus based on the digital input signals.
[0006] In another aspect, an instrument transformer is provided. The instrument transformer includes a current transformer for supplying an analog input signal proportional to a load current, the current transformer is coupled to a relay front-end module, the relay front-end module including a current-to-voltage converter circuit and the relay front-end module is configured to couple to a remote protection module.
[0007] In still another aspect, an electrical apparatus for connecting a load to an electrical power source is provided. The electrical apparatus includes separable contacts selectively connecting the load to the power source when closed and disconnecting the load from the power source when open and an instrument transformer including a current transformer for supplying an input signal proportional to a load current, the current transformer coupled to a relay front-end module, the relay front-end module including a current-to-voltage converter circuit, the relay front-end module configured to couple to a remote protection module.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] [0008]FIG. 1 is a schematic illustration of a known current transformer arrangement.
[0009] [0009]FIG. 2 is a schematic illustration of an exemplary embodiment of the present invention.
[0010] [0010]FIG. 3 is a schematic illustration of an alternative embodiment of the present invention.
[0011] [0011]FIG. 4 illustrates a block diagram of an instrument transformer of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0012] [0012]FIG. 1 is a schematic illustration of a known instrument transformer 10 arrangement. Busbar 12 is a primary conductor in an alternating current (AC) switchgear panel (not shown) and is conducted through a toroidal core 13 of a current transformer 14 such that busbar 12 and a plurality of electrical windings 15 within current transformer 14 are magnetically coupled Electrical terminations 16 and 18 couple current transformer 14 to copper conductors 20 and 22 respectively to transmit a signal generated by current transformer 14 to a measuring device (not shown).
[0013] In operation, an alternating current flowing in busbar 12 induces a proportional current signal in windings 15 of current transformer 14 . The current signal is transmitted via terminations 16 and 18 to conductors 17 and 19 which transmit the current signal to a measuring device.
[0014] [0014]FIG. 2 is a schematic illustration of an instrument transformer arrangement 20 . A switchgear busbar 22 is a primary conductor conducted through and magnetically coupled to a current transformer 24 . Electrical terminations 26 and 28 couple current transformer 24 to a retrofit relay front end module 30 . In the exemplary embodiment, relay front end module 30 is mechanically supported by as well as electrically coupled to, current transformer 24 by terminations 26 and 28 . In another embodiment, an auxiliary attachment is used to couple relay front end module 30 to current transformer 24 . The details of the relay front end module 30 are discussed below. The output of relay front end module 30 is transmitted through conduit 32 to a relay protection module (shown in FIG. 4). In an alternative embodiment, front end module 30 may be coupled to other switchgear electrical or electronic devices such as, for example, a limit switch, timer, transfer switch, panel control or display.
[0015] [0015]FIG. 3 is a schematic illustration of an alternative embodiment of an instrument transformer arrangement 40 . Instrument transformer 40 is similar to instrument transformer 20 (shown in FIG. 2) and components in instrument transformer 40 that are identical to components of instrument transformer 20 are identified in FIG. 3 using the same reference numerals used in FIG. 2. Accordingly, instrument transformer 40 includes switchgear busbar 22 which is a primary conductor conducted through and magnetically coupled to a current transformer 24 . Relay front end module 30 is integrally formed with current transformer 24 . The details of the relay front end module 30 are discussed below. The output of relay front end module 30 is transmitted through conduit 32 to a relay protection module (shown in FIG. 4). In an alternative embodiment, front end module 30 may be integrally formed and coupled to other switchgear electrical or electronic devices such as, for example, a limit switch, timer, transfer switch, panel control or display.
[0016] [0016]FIG. 4 illustrates a block diagram of an instrument transformer 50 that may be used within instrument transformer arrangements 20 or 40 (shown in FIGS. 2 and 3 respectively). Instrument transformer 50 includes a current transformer (CT) 52 , a relay front end module 54 , a protection module 56 , a user interface module 58 and a fiber optic power supply module 60 . In one embodiment, current transformer 52 , is a known CT that is retrofitted to receive relay front end module 54 . Terminals 62 and 64 couple relay front end module 54 to current transformer 52 . Current transformer 52 includes a toroidal shaped secondary winding 66 , through which a primary winding 68 is conducted. In the exemplary embodiment, primary winding 68 is a switchgear busbar or cable. A raw current signal from current transformer 52 is conducted to step down transformer 70 which reduces an amplitude of the raw current signal to a level suitable for processing within relay front end module 54 .
[0017] An instrument level signal is conducted via conduit 72 to a current to voltage converter 74 , wherein the current signal is converted to a proportional voltage signal. The voltage signal is conducted via conduit 76 to an analog to digital (A/D) converter 78 wherein the signal is digitized and transmitted via a conduit 80 to a fiber optic interface 82 . Fiber optic interface 82 communicates via fiber optic bus 84 with protection module 56 . This communication is bi-directional, such that signal data is transmitted to protection module 56 , while limit value and setup data may be transmitted to fiber optic interface 82 .
[0018] Protection module 56 communicates data to user interface module 58 via conduit 86 and receives commands and limit values from user interface module 58 . In one embodiment, user interface module 58 is a thin screen module mounted to a user accessible portion of a switchgear panel exterior. In another embodiment, user interface module 58 is mounted remotely, for example, in a central control room for remote monitoring of a status of instrument transformer 50 . User interface module 58 includes a user input portion (not shown), for example, a key pad, touch screen, and communications port or any combination thereof. The communications port may be coupled to a personal computer or another data processing device. User interface module 58 also includes a display for indicating a status of the instrument transformer including, but not limited to, operational status, fault status, self diagnostic results and additional programmable status indications. In one embodiment, bus 86 facilitates communication with a plurality of protection modules 56 and one or more user interface modules 58 .
[0019] The flexibility of a fiber optic data highway communications path allows many systems to be monitored and controlled from a central location or any number of remote locations. Communications conduits 84 and 86 are not limited to a fiber optic architecture but, may be any of a wide array of standard communications bus architectures including, but not limited to Ethernet, RS-485, or other applicable bus architectures. Communications conduits 84 and 86 may use any of a number of applicable communications protocols including, but not limited to profibus, profibus DP, TCP/IP, or any other applicable communications protocol. Fiber optic power supply module 60 , in one embodiment, is located in the switchgear panel proximate user interface module 58 . Fiber optic power supply module 60 supplies power via conduit 88 to relay front end module fiber optic components through fiber optic power supply 90 and conduit 92 .
[0020] The exemplary embodiment has heretofore been described as an instrument transformer with a current transformer as the sensor. Other similar instrument transformers based on other sensors may be incorporated in the same manner. For example, voltage, frequency, temperature, infrared spectrum energy, vibration, flow, interlocks and safety devices can be modularized in similar fashion and incorporated into the monitoring and protection system described herein. In operation, coupling a relay front end module 30 directly to a current transformer 24 reduces the amount of copper connecting wire required to manufacture switchgear. Instead, most of the signal carrying conduit is fiber optic.
[0021] The electromagnetic environment within electrical switchgear in the area of the busbars is characterized by high electrical and magnetic field strength and often by the presence of high levels of electrical “noise,” that is, unwanted signals which interfere with instrumentation and measurement. These conditions may severely affect electrical equipment and communications. For this reason, instrument transformer signals in switchgear are at relatively high electrical levels, such as 5 Amperes for current transformer signals and 120 Volts for voltage transformer signals. In addition, electrical shielding is provided between the high voltage compartments and the instrumentation and relaying compartments by means of grounded steel enclosures. Fiber optic communications signals are not affected by this relatively low-frequency electromagnetic environment, and thus are an ideal communications medium for electrical switchgear. Fiber optics are commonly used in the industry for triggering high-voltage thyristors, and for communications with high voltage equipment. This invention describes a new application of fiber optics to electrical switchgear. The electrical module ( 54 in FIG. 4) should be shielded from electromagnetic interference with means such as a grounded steel container. Alternatively, it may be designed using electronic devices which do not require such shielding.
[0022] The invention described here is not limited in terms of its application to instrument transformer circuits. The entire wiring harness assembly of electrical switchgear may be replaced by fiber-optic cables. Each device, such as panel controls and displays, metering, instrumentation and relaying, and all other devices, such as limit switches, timers, transfer switches, and so forth may be connected by a fiber optic network much smaller in size and lower in cost than the copper wire assemblies in present use.
[0023] The above described instrument transformer configuration for switchgear is cost-effective and reliable. The instrument transformer includes a sensor coupled to a relay front end module. The sensor includes a current transformer but, may be any number of electrical or process sensors depending on a user's requirements. The relay front end module includes signal conversion and conditioning components and a communications module to receive data and commands and pass data on to a protection module over a fiber optic or other suitable conduit. Mounting the relay front end module to the sensor and using a fiber optic communications bus instead of copper panel wire will reduce a high cost construction component and labor intensive manufacturing step. As a result, a reliable and durable instrument assembly is provided for a switchgear.
[0024] While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims. | 4y
|
BACKGROUND OF THE INVENTION
This invention relates generally to contact lenses and more particularly to the fabrication of contact lenses.
Defects in human vision have for years been corrected by placing lenses, commonly referred to as glasses, of a prscribed design in front of the eye. Recently, as an alternative to glasses, contact lenses were developed. Contact lenses are thin lenses, typically made of a plastic material, fitted over the cornea to correct vision defects. A process for fabricating contact lenses involves filling a plastic casting mold with contact lens material in liquid monomer form. The liquid is then polymerized into a solid. The casting mold is precision manufactured such that the contact lens formed in the mold is of a prescribed edge dimension and the concave surface is of a prescribed finished optical design and quality. Once the convex surface of the lens is cut and polished to the prescribed optical quality, the lens can beremoved from the casting mold and is in a completely finished state.
while the above process has enabled contact lenses to be produced in mass quantities with high optical quality, the effective yield (i.e., the number of good lenses per total number of molded lenses) is low. This low yield is primarily due to the fact that removal of a lens from the plastic casting mold has been difficult. Such removal involves either floating the lens off of the casting mold in a liquid bath or deforming the casting mold such as by squeezing the mold with pliers for example. The liquid bath is an inefficient process only cost justified for large batches of lenses. Moreover, it is only effective for lenses made with liquid permiable material. On the other hand, deforming of the casting mold is a manual process, usable on only one mold at a time, requiring a high degree of skill to prevent braking of the lens as the mold is deformed.
SUMMARY OF THE INVENTION
This invention is directed to fabrication of contact lenses whereby the yield of lenses removed from plastic casting molds is significantly increased. According to a preferred embodiment of this invention. in fabricating contact lenses where a lens is initially formed in a plastic casting mold. the mold is compressed to a degree sufficient to initiate permanent deformation of the mold material. in progressive steps. incrementally decreasing in diameter from a starting diameter substantially larger than the diameter of the molded lens. until the lens self-detaches from the mold. The compression process may be carried out in a fluidbath for the purpose of dampening the compressive action. Further, the lens and casting mold may be preheated to facilitate the initiation of deformation, and the release of the lens from the mold.
The invention, and its objects and advantages. will become more apparent in the detailed description of the preferred embodiment presented below.
BRIEF DESCRIPTION OF THE DRAWINGS
In the detailed description of the preferred embodiment of the invention presented below, reference is made to the accompanying drawings, in which:
FIG. 1 is a view, in cross-section, of a plastic contact lens casting mold filled with lens material;
FIG. 2 is a view, in cross-section, of the casting mold with the contact lens cup cut away and the convex surface of the lens in its finished state;
FIG. 3 is a side elevational view of an apparatus for removing the contact lens from the plastic casting mold according to this invention;
FIG. 4 is a top plan view of the apparatus of FIG. 3 for removing the contact lens from the plastic casting mold; and
FIGS. 5 through 8 are views, in cross-section, taken at progressive stages during the operation of the apparatus of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the accompanying drawings, FIG. 1 shows a plastic casting mold, designated generally by the numeral 10, in which a contact lens is formed. The mold 10, fabricated from nylon for example, includes a body portion 12 having an integrally formed cup 14 adapted to contain lens material. The base 16 of the cup is finished so as to have a surface finish to yield a complimentary surface finish of a predetermined optical quality, for example according to a particular lens prescription. Moreover the diameter of the cup 14 at its base is selected to be substantially equal to the desired diameter of the lens to be formed (e.g., 6-13 mm).
during fabrication of a contact lens, the cup 14 of the casting mold 10 is filled with a monomer of the material 18 from which the lens is to be formed. The material 18 is polymerized such as by irradiation with light of the particular wave lengths to induce such polymerization. Thereafter the cup 14 is cut off and the lens material 18 is polished to the desired optical quality. This results in a contact lens 20 finished on its convex surface 20a (see FIG. 2). Since the concave surface of the lens is formed to the desired optical quality finish during the molding process, lens fabrication is completed just by removing the lens from the body portion 12 of the casting mold 10.
Removal of the contact lenses from respective casting molds successfully without damage to the lenses is accomplished according to this invention as follows. The body portion 12 of the casting mold, with the attached contact lens is positioned in a die 22 of a compression apparatus 24 (see FIG. 3). The apparatus 24 may be of the pneumatic or hydraulic cylinder type. Of course other apparatus developing compressive force, such as spring or lever based mechanisms, are suitable for use with this invention. The die 22 holds the body portion 12 such that it is substantially coaxially located with respect to the longitudinal axis of the piston rod 26 of the compression cylinder of the apparatus 24. A series of plungers 28a-28f, preferably made of brass, are mounted on a turret assembly 30. The turret assembly 30 is rotatable (either manually or by an automatically indexing mechanical mechanism) about an axis 30a to selectively locate a particular plunger between the end 26a of the piston rod 26 and the die 22. On activation of the compression cylinder by a control mechanism 32, the selected plunger is forced into engagement with the casting mold body portion 12 on the opposite side from the attached contact lens 20.
The control mechanism 32, which may include a programmable microprocessor for example, controls the amount of force, and the time duration and speed of its application by the compression cylinder through the plunger on the body portion of the casting mold in the die. The parameters of force application are selected, dependent in part on mold and lens composition and configuration so as to be sufficient to cause the beginning of plastic flow of the body portion material for permanent deformation of the body portion 12 of the casting mold (see FIG. 5). The permanent deformation of the body portion 12 is progressively continued, in descrete steps, utilizing successive plungers 28b-28f rotated into position by the turret 30. The plungers are arranged such that their respective diameters are of incrementally decreasing size so that, as can be seen in FIGS. 6-8, the lens 20 progressively detaches from the body portion 12 on each successive deformation until the lens finally self-detaches from the body portion.
As an illustrative example, the apparatus 24 may include an air cylinder of a diameter of approximately 10 cm utilizing air at a pressure of between 5-80 psi. Depending upon the material of the casting mold, the resultant force to be applied to the body portion 12 of the casting mold is in the range of between approximately 100-1400 pounds for a time of approximately between 2-10 sec. With a contact lens diameter of approximately between 4-16 mm, the diameter of the plunger 28 starts at approximately 1.2 cm and decreases in 0.15 cm increments down to 0.35 cm. Of course other arrangements for the apparatus 24 for carrying out the progressive permanent deformation are suitable for use with this invention. For example, the plungers may be successively manually located in position on the end of the piston rod of a compression cylinder to be engaged sequentially with the casting mold. Alternatively, the plungers may be in an in-line arrangement to be moved in a stepped manner for sequential activation, and progressive compressive application, on a single stroke of the compression cylinder.
The above process can be carried out in a fluid bath if so desired. This has the advantage of dampening the compressive action to further prevent damage to the contact lens 20 as it separates from the body portion 12 of the casting mold 10. It has also been found that preheating the body portion prior to subjecting it to the progressive compressive steps also facilitates lens removal. While the reasons for this are not yet completely understood, it is felt that such preheating encourages the onset of plastic flow necessary for the start of permanent deformation of the casting mold body portion. As an illustrative example, baking of the casting mold for 1/2 hour at 230° has resulted in an increase in the yield of contact lenses successfully removed by the process according to this invention.
The invention has been described in detail with particular reference to a preferred embodiment thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. | 4y
|
FIELD OF THE INVENTION
[0001] The present invention relates to improvements in water efficient greenhouses for efficient growth of agricultural produces and more particularly to a renewable energy desalination greenhouse which can utilize seawater or brackish water to perform a desalination process which, using renewable energy, grows crops in a shorter time period while using only a small fraction of the water which would otherwise be utilized in open field production. The present invention is also shown to be amenable to automated and continuous agricultural production.
BACKGROUND OF THE INVENTION
[0002] In arid areas of the world a conventional greenhouse has a number of disadvantages. Increased sun light can cause a greenhouse to overheat. The answer to overheating has been to open the greenhouse to a cross breeze and increase evaporation for cooling. However, in desert areas this simply translates into a prohibitively greater water usage than would be experienced with the greenhouse in cooler climates. A conventional greenhouse project in the desert would normally require a commitment of several multiples of the amount of water than would be necessary in a cooler climate. Conventional greenhouses contemplate fresh water to be applied to plants in an amount to not only provide a nourishment medium for the plants, but also to humidify the internal space within the greenhouse. However, the internal space within the greenhouse must not over heat, and the main mechanism to prevent overheating is to create a cross draft of outside air to cool. However, this cooling evaporates and dehumidifies the interior growing space of the greenhouse.
[0003] The desert environment is well known to have very little fresh water available, or perhaps only sea water, brine from groundwater desalination plants or brackish water available. Such desert environment is also known to have high solar availability, but suffers from excess temperatures associated with the intense solar exposure. The shortcomings of the conventional or more advanced solar still design, where water in an enclosure with a sun facing inclined transparent cover condenses desalinated water on the inside of the cover for collection. Its heat input may be increased by mirrors in order to increase yield of desalinated water per square meter of cover per day, however the original simple solar still and its many variations suffer from the following shortcomings: (1) when the solar still is dedicated for desalination only the cost of the structure becomes very expensive and so does the desalination process and output; (2) as the moisture in the tightly closed cavity of the still increases upon solar heating the evaporation is reduced and the still becomes less efficient; (3) Some of the desalinated water that condenses on the lower side of the transparent cover is preferentially evaporated relative to the salty water in the basin because of its lower density and therefore less salty water is evaporated; (4) there is a problem of obtaining an efficient condenser for the solar still and reliance on the air temperature outside the still to condense the water is not efficient, and the transparent cover becomes hot itself and the temperature drop between the evaporating moisture and the cover is not significant enough to allow substantial condensation; and (5) the above factors result in a still that is expensive with a low output of 2-5 liters per square meter per day. It is therefore desirable to invent a solar desalination device that is less expensive and is more productive per unit of space per day.
SUMMARY OF THE INVENTION
[0004] The desalination greenhouse is a solar still that doubles as a greenhouse. The desalinated water produced could be used for any purpose such as drinking, boiler water and chemical industry due to its high purity or for agriculture and any combination of the above as it is inexpensively produced. The structure is essentially a greenhouse with an additional inexpensive extra cover and with a side benefit of desalination. The capital cost is therefore appropriated primarily for the greenhouse crop product, and the capital cost of desalination is significantly reduced. The desalination greenhouse of the invention also provides a number of flexible operation controls to produce crops rapidly in a desert environment using brackish water. Both winter and summer operations can be optimized and the desalination greenhouse helps to compensate for changing exterior process operating conditions. Even more surprisingly the desalination greenhouse can produce a source of potable water given an input of only brackish or sea water.
[0005] The desalination greenhouse can be optimized for superior crop production and minimization of diseases. It minimizes heating and cooling requirements due to its superior insulation and absorption of heat in summer and its release in winter without obstructing natural light transmission. It uses renewable energy to desalinate water through condensation of sun and wind heated air that is forced through the cavity between the two structures to evaporate a very thin layer of water, and then to a black cover heated zone, to evaporative cooler wet pads. Condensation occurs on the inner surfaces of the outer and inner sections of the desalination greenhouse. Condensation of the inner greenhouse humid air may be achieved through a heat exchanger carrying the cooled water piped from the through of the evaporative cooling pads. The roof of the inner section of the desalination greenhouse is wetted evenly with sea or brackish water for evaporation which also cools the structure of the inner section of the desalination greenhouse. 1.0 to 10.0 mm v to u shaped grooves in the hard cover roof material of the inner section of the desalination greenhouse, preferably made of polycarbonate, guide the water downward and spread it evenly over the surface, providing the right depth for effective evaporation and cooling of the inner greenhouse. The inner greenhouse frame structure elements may be extended to support the outer greenhouse poly cover. The double shell greenhouse as described provides an efficient and cost effective means of heat utilization to desalinate sea or brackish water for irrigation and other uses, reduce heat input into the inner greenhouse, and minimize the crop requirement by over 95% by cutting the production cycle substantially and recovering the evapo-transpiration water.
[0006] The space over the water being desalinated is never saturated due to continuous air movement. The thickness of the salty water being evaporated is maintained very thin, within one centimeter, in order to chill the water to lower temperatures through evaporation and removal of moisture by the air. The even distribution of the salt water and its thin layer covering the roof and sides of the production greenhouse, made possible by the channel design (grooves) provides the production greenhouse with a cold surface that makes the environment more conducive to optimal plant growth and enhances condensation on the ceiling and sides of the production greenhouse. The outer shell greenhouse is a canopy to trap the moisture evaporating from the roof of the production greenhouse and enhances condensation on the ceiling and inside wall of the outer shell greenhouse.
[0007] An 1008 square meter floor greenhouse, for example, (36×28 and 4 meter high at the gutter and 8 meter high at the center) with one meter space between the inner and outer shell, has a total surface are of roof and sides of 2800 square meters allowing for doors and other vents. This area shall produce about 10 liters per square meter per day, or 28,000 liters per day. A seawater desalination greenhouse of a single shell (1), which relied on cold deep seawater as a condenser, produced between 3 and 6 liters per square meter per day depending on whether the environment is tropical or oasis. When the crop produced in the present desalination greenhouse invention is barley for animal forage production, the cycle per crop averages ten days from seed to harvest (2). The desalination greenhouse will produce 1500 tons of forage annually and consumes 4500 cubic meters of desalinated water per year for irrigation.
[0008] The desalination greenhouse of the current invention produces over 10,000 cubic meters of desalinated water, enough for forage irrigation and drinking water for 1000 people, each using 15 liters per day. The desalination greenhouse of the current invention could contribute to solving problems of many regions of the world that require desalinated water for human consumption, industry and irrigation of crops. The high value of the desalinated water makes it valuable for boiler and chemical process water which is expensive to produce and requires substantial energy due to its high level of purity.
[0009] The air cycle steps of the desalination greenhouse may be represented as follows: Ambient air>disinfection>filter>blower>distribution>roof humidification>heating>pad humidification>condensation>ambient air. The water cycle steps in the desalination greenhouse may be represented and summarized as follows: a) Salty water. Salty water spread over roof of production greenhouse>evaporation and cooling on roof>evaporation and cooling on evaporation pads or water shower>heat exchanger condenser>Collection and recycle with bleed and blend with fresh salty water; b) Desalinated water. Condensed water on inside and walls of outer shell+Condensed water on inside and walls of production greenhouse+condensed water on heat exchanger carrying cold water from evaporation pads
[0010] All condensate is collected in their own gutter like channels separate from salty water channels.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The invention, its configuration, construction, and operation will be best further described in the following detailed description, taken in conjunction with the accompanying drawings in which:
[0012] FIG. 1 is a perspective skeletal view of the desalination greenhouse of the present invention showing a nesting of the structures to create a separation space between an inner section and an outer section;
[0013] FIG. 2 is diagram of the structures within the desalination greenhouse which inlet air experiences during the expected operation;
[0014] FIG. 3 is a section taken along line 3 - 3 of FIG. 1 to illustrate the conversion of brackish water to potable water by condensation onto the inside surfaces of an outer section of the desalination greenhouse;
[0015] FIG. 4 is perspective of a panel having channels (grooves) in the plate surface which have a triangular cross-sectional shape to produce triangular channels, the plate used for roof and outer sides of the inner and outer shells of the desalination greenhouse;
[0016] FIG. 5 is cross sectional view of a plate which may or may not be the same overall size of the plate of FIG. 4 , and illustrating a cross sectional profile having abbreviated height projections which define wide shallow channels;
[0017] FIG. 6 is cross sectional view of a plate which may or may not be the same overall size of the plate of FIG. 3 , and illustrating a cross sectional profile having height projections which have a separation of about the same distance as their height;
[0018] FIG. 7 is a schematic of the components of a vortex system which is utilizable for cooling at one end and heating at the other in conjunction with the desalination greenhouse;
[0019] FIG. 8 is an expanded sectional view of the portion of the desalination greenhouse and illustrating separated vertical walls, and a fresh water reservoir feeding a system which includes heat exchange, storage, irrigation system storage and metered fertilizer; and
[0020] FIG. 9 is a perspective skeletal view of a stackable production bin which may be preferably used on a conveyor.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] Referring to FIG. 1 a perspective skeletal view of one type of embodiment of a desalination greenhouse 21 which is shown as a long rectangular building, but need not be of the shape shown. The desalination greenhouse 21 is shown in a transparent view and includes an outer shell 23 for containment of water vapor, desalination, and light transmission; and inner shell 25 which is in effect an inner greenhouse, and is for crop production, evaporative cooling and condensation of moisture.
[0022] The outer shell 23 shown is of simple construction and includes a series of vertical walls 31 which include side walls and end walls and topped by a roof 33 which includes a pair of sloped roof walls. Likewise, inner shell 25 shown is of simple construction and includes a series of vertical walls 37 which include side walls and end walls and topped by a roof 39 which includes a pair of sloped roof walls. Roofs 33 , 39 of both greenhouses are preferably similar to each other (although shown in FIG. 1 as being parallel), they need not be. Both the roofs 33 , 39 have roof walls shaped with a slant angle more than 15 and less than 60 degrees to facilitate condensate gravitationally sliding downward. Outer shell 23 has an inner chamber 41 while inner shell 25 has an inner chamber 43 . Inner chamber 41 contains the inner shell 25 and is smaller, with the annular space between the outer shell and inner shell being referred to as a cavity and including a roof cavity 45 between the roofs 33 and 39 and a side cavity 47 between the vertical walls 31 and vertical walls 37 .
[0023] Any number and type of protruding supports 51 may be anchored to the structural body of either of the outer shell 23 or inner shell 25 and for the purpose of anchoring the desalination greenhouse 21 , securing the outer shell 23 or inner shell 25 to each other, or for anchoring the outer shell 23 to the ground, with FIG. 1 being a skeletal view to show the nested relationship of the outer shell 23 and inner shell 25 . Differing construction materials and methods of support, such as positive air pressure and the like, can be used to construct the desalination greenhouse 21 . Supports 51 may include any frame member, as well as any member from which external or internal support may be facilitated by any other structure or object. Also, the desalination greenhouse 21 has been recited in terms of an outer shell 23 and an inner shell 25 such that roof and side cavities 45 and 47 can be available to promote condensation in the outer shell. It is understood that, especially for desalination greenhouse 21 which are much longer than they are wide, that the ends can be similarly situated to have a side cavities along with some portal access such as a door bridge to extend between them, but that in a long desalination greenhouse 21 most of the action will occur between side cavities 47 of the major long sides of the desalination greenhouse 21 , as well as the roof cavities 45 .
[0024] FIG. 1 illustrates a crude schematic possible location for a pair of air inlet air moving devices such as fans 53 shown, but not necessarily forced to be located nearer the roof 33 , which force outside air into the roof and side cavities 45 and 47 . A pair of exhaust or outlet air moving devices, such as fans 55 are shown, but not necessarily forced to be located, in the middle of an end vertical wall structure 57 , and connect inner shell 25 inner chamber 43 to the outside atmosphere. Vertical wall structure 57 may include a door 59 . The further details of an entry door 59 will be omitted, but suffice it to say that door 59 may be located in a connective portal which engages both the outer shell 23 and inner shell 25 to disrupt any breach or interruption of the roof and side cavities 45 and 47 . In this way, a single door 59 can be operated to give access to the inner chamber 41 .
[0025] Conversely, a separate door may be provided for each of the outer shell 23 and inner shell 25 , with the space between the two doors remaining an active part of the roof and side cavities 45 and 47 . This may not be as preferred as the opening of either of two such separate doors would disrupt the action and flow going on in the roof and side cavities 45 and 47 . When access to the inner chamber 41 is had over a long time, such as the introduction or removal of soil and plant materials, the roof and side cavities 45 and 47 would be significantly disrupted. In yet a further alternative, the end wall 57 may be designed not to contain a side cavity 45 and to be built as a wall and support structure common to both the outer shell 23 and inner shell 25 . In this case, the user is giving up the desalination action at the end wall 57 . However, as can be seen in FIG. 1 , and in the end wall 57 and roof portion of end wall 57 supports four fans 53 , 57 and a door 59 which combine to occupy a significant percentage of the end wall 57 . It may thus be desirable for simplicity of construction for doors 59 and fans 53 , 57 to be located in an isolated cluster which will enable the use of a single wall to thus eliminate the need for double sealing, and accommodating other insulatory structures to enable the action to be described in the roof and side cavities 45 and 47 around such access accommodating and insulatory structures.
[0026] With the basics of an overall structure of an example desalination greenhouse 21 having been seen in FIG. 1 , and without the need to make duplicative burdensome specifically located structures to illustrate the operation of the desalination greenhouse 21 , a diagrammatic representation of the overall flow is shown in FIG. 2 . Referring to FIG. 2 , a block diagram illustrates the general flow of air through the desalination greenhouse 21 . From the outside atmosphere 61 , air may be drawn in through forced air fans 53 . Where the desalination greenhouse 21 is much larger than the simple design of FIG. 1 , the inside of air fans 53 may be fitted with a distribution duct to insure that the incoming forced air from the atmosphere is spread as evenly as possible through the roof cavity 45 , even to the most distant portion of the desalination greenhouse 21 . It is understood that even though the general structure of the desalination greenhouse 21 is oblong, that if a desalination greenhouse 21 was wider than long, there may be several forced air fans 53 operating with generally parallel hot air distribution lines (not shown). In the case of a single, extraordinary long desalination greenhouse 21 , a large forced air fan 53 might be used with a significant sized ambient air distribution pipe or duct (not shown).
[0027] The forced air fans 53 introduce ambient air into the roof and side cavities 45 and 47 throughout the desalination greenhouse 21 . The hot air will be utilized to evaporate and possibly cool any saline or brackish water which may be introduced onto the surface of the outside of the inner shell 25 . The air circulating in the roof and side cavities 45 and 47 whose humidification may be increased after contact with moisture from the outside of the inner shell 25 may deposit some fresh water droplets via condensation on the inside of the outer shell 23 . The air circulating in the roof and side cavities 45 and 47 whose humidification may be increased after contact with moisture from the outside of the inner shell 25 may then proceed into the inside of the inner shell 25 through an optional cooling pad 63 . Cooling pad 63 may be a matrixed structure which entrains some liquid to facilitate an increased contact between air circulating in the roof and side cavities 45 and 47 and liquid water which may be present in the cooling pad 63 through a variety of mechanisms.
[0028] The cooling pad 63 can be a passive fibrous flow device to enable a passing gas to make a greater degree of contact with a wetted area. Cooling pad 63 can include a recycle branch to collect and recirculate liquid which typically passes through it from top to bottom. Cooling pad 63 may also be connected to external heating sources or cooling sources (not shown in FIG. 2 ) which provide thermal transfer through a conduit such as a heating coil or cooling coil. Cooling pad 63 also, regardless of whether or not connected to external heating or cooling sources, can act as a stabilizing passive heating or cooling mass to protect plants within the inner shell 25 from momentary changes such as between full sun and cloud cover, as well as between day and night. Physically, the cooling pad 63 may likely be located within the inner shell 25 and likely beginning at the boundary between the inner shell 25 and the roof and side cavities 45 and 47 and continuing into the inner shell 25 for a sufficient distance (typically horizontal distance) to provide adequate contact between the air flow entering the inner shell 25 and any wetted surfaces within the cooling pad 63 .
[0029] Air which emerges from the cooling pad 63 enters the inner shell 25 which it is available to humidify and provide gentle and stable appropriate temperature air for any growing plant matter located within the inner shell 25 . The air from the cooling pad 63 may be arranged for maximum circulation within the inner shell 25 , including other circulating fans, such as ceiling fans and blowers, located within the inner shell 25 . From inner shell 25 , the air passes to and through exhaust fan 55 and back to the atmosphere 61 . It may be preferable for inlet fan 53 to operate at a higher pressure rate than exhaust fan 55 so that the air within the outer shell 23 and inner shell 25 may be somewhat slightly pressurized.
[0030] Referring to FIG. 3 , a schematic view taken along line 3 - 3 of FIG. 1 shows some operational details of desalination greenhouse 21 . The previously seen inlet fan 53 is seen as blowing air into a conduit or duct 65 which continues to extend along a significant length of the rectangular elongate shape of the desalination greenhouse 21 . Duct 65 may be a wide plastic pipe and may be configured to be heated by the sun. The relationship of the roof 33 and roof 39 separated by the roof cavity, and the relationship of the vertical walls 31 and vertical walls 37 , separated by the wall cavity 47 is better illustrated. Above a top portion of the roof 39 , a brine distribution header pipe 71 is seen as having ability to distribute, drip, spray or otherwise convey in any manner, brine 73 in an even as distribution as possible to coat and move slowly across the roof 39 and thence walls 37 of the inner shell 25 . As will be shown, the materials of construction of both the inner shell 25 and outer shell 23 are so as to promote an enhanced holding time for brine 73 so that it will have an opportunity to evaporate from the exterior of the inner shell 25 and condense on the inside of the outer shell 23 .
[0031] Not shown in FIG. 1 were details of construction of the desalination greenhouse 21 as the details of other structures would have been obscured. The materials of construction for the inner and outer shells 25 and 23 of the desalination greenhouse 21 may include a plurality of uprights 77 and cross bars 79 to support panels (not yet shown) which may be replaced if damaged or broken. Uprights 77 and cross bars 79 may be made from galvanized steel, aluminum or other suitable material. In the perspective of FIG. 3 , some of the uprights 77 are shown as segments between the cross bars 70 which are shown as expansions located along the uprights 77 . It is also noted that the walls 31 and 39 need not be vertical, but may be sloped or curved. Any sloping and curving of the walls 31 and 39 may be configured to combine with the shape of the roofs 31 and 39 to produce an advantageous gravity and slope controlled flow.
[0032] Explained, the exterior of inner shell 25 will have an even flow of brackish water or brine 73 over its exterior surface. Any energy input into the inner shell 25 will cause water to be vaporized. Vaporized water may condense on the inside of the outer shell 23 and run down the inside of the roof 33 and down the inside of wall 31 . At the base of the walls 37 and 31 , the clean condensed water from the inside of wall 31 would otherwise mix with the brackish water, or brine 73 flowing down from the outside of wall 37 . The prevention of mixing of these two streams by segregating and conserving the pure condensed water provides a source of desalinated water. A barrier 81 separates the flow at the base of the walls 31 and 37 into a brackish water reservoir 83 and a fresh water reservoir 85 . Brackish water reservoir 83 may have a lower drainage tap 87 and a fresh water reservoir 85 may have a drainage tap 89 . Taps 87 and 89 will assist in harvesting and or recycling the brackish water 73 or the condensed water as needed.
[0033] Referring to FIG. 4 , a panel 91 is shown which has a series of channels or grooves 93 seen in parallel across the upper surface of the panel 91 . When the panel 91 is arranged so that the grooves 93 extend horizontally, the grooves act to entrain some of the brackish water 73 and hold onto it while giving it an opportunity to evaporate. At minimum, the grooves 93 increase the effective vertical height of the walls 37 and optionally the flow path length along the roof 39 . At best, the grooves 93 could be angled unevenly to form little “shelves” each of which could provide a significant residence time for brackish water 73 on its way to brackish water reservoir 83 . In some cases the grooves 93 could even have a negative load flanking to form a horizontal drainage channel with or without interruptions in a horizontal to even further increase the mean flow path. In other words, if every other groove were “nicked” at its end, and if the upper angle were less than horizontal, brackish water 73 could be caused to follow a serpentine path down the panel 91 . Other variations are possible.
[0034] The panel 91 may be made of conventional greenhouse building material products such as plastic, polycarbonate, or any other material which is at least partially clear. The grooves 93 may be formed by molding or by matching or by other technique. An outer covering may be of lighter materials such as polyethylene for economics and for easy removal when cleaning of the roof 33 is needed. Air and water within the desalination greenhouse 21 may be uv-disinfected at any, and at many points in the system for to enable the use of an organic crop label for plants grown. Referring to FIG. 5 , and as a further variation on panel 91 of FIG. 4 , an end view of a panel 101 is shown as having a series of spaced apart and low profile protrusions 103 . Likewise, Referring to FIG. 6 , and as a further variation on panel 91 of FIG. 4 , an end view of a panel 111 is shown as having a series of spaced apart and high profile protrusions 133 to form a series of rectangular channels approximately as wide as the protrusions are tall.
[0035] The use of a vortex system could be employed with the desalination greenhouse 21 . Referring to FIG. 7 , a schematic block diagram of such a system is shown. A vortex system 151 includes equipment to make a process flow of air. A vortex diverter system 151 is used for heating on one end and cooling on the other and which may be controlled to increase or decrease as required. A compressor 153 pressurizes air into an air storage tank 155 at about 100 PSI. The pressurized air exits from the tank 155 and passes through an air filter 157 and a moisture trap 159 before it inters a vortex device 161 . The vortex device 161 splits the air into cold stream exiting from one end of the vortex device 161 and hot exiting from the other end of the vortex device 161 . The hot air output of the vortex device 161 may be introduced into the duct 65 either upstream or downstream of the inlet fans 53 where it will ultimately enter the roof and side cavities 45 and 47 . The cold air output of the vortex device 161 may be passed through a coil or other heat exchange structure inside a water pipe (not shown) carrying the cold water to the inner shell 25 of the desalination heat exchanger 21 . In the summer when more cold air from the output of the vortex device 161 is needed to condense more water, the cold portion of the air is increased which will decrease the warm output of the vortex device 161 . In winter the arrangement is reversed as more hot air from the vortex device 161 is needed for introduction of heated air duct 65 either upstream or downstream of the inlet fans 53 . Mechanical controls on each end of the vortex device 161 outlets facilitate adjustment of heat and cold flow. In instances when the air filter 155 , and heat and residence time in the vortex system 151 do not disinfect enough, the air passing into black, heat absorbing conduit or duct 65 can provide some additional sterilization.
[0036] In general, the use of a vortex system could be employed with the desalination greenhouse 21 . The cool air under positive pressure from the air blower 153 will eventually enters inner shell 25 through evaporation or cooling pads 63 . Cooling pads 63 may be switched off by either being taken out of the path of flow or simply allowed to run dry, to remove its ability to cool inner shell 25 of desalination greenhouse 21 using cooled air from roof and side cavities 45 and 47 . Conversely, cooling pads 63 may be switched on or into or out of the path of flow and with the brine distribution header pipe 71 used wetting roof 39 and side walls 37 of inner shell 25 of desalination greenhouse 21 with roof and side cavities 45 and 47 switched off or isolated from flow, in humid climates so that heating the air reduces its relative humidity and makes it effective in cooling inner section 24 of desalination greenhouse 21 . Cool air then passes from roof and side cavities 45 and 47 into inner shell 25 of desalination greenhouse 21 to cool the growing crop, to enable the growing crop to transpire, supply oxygen and remove carbon dioxide and other gases. Air becomes warmer and more humid as it passed from one end of to the other of inner shell 25 of desalination greenhouse 21 due to the incident light and heat and transpiration of the crop in inner shell 25 of desalination greenhouse 21 . Air may exit inner shell 25 of desalination greenhouse 21 through a heat exchanger (not shown in FIG. 7 ) through which cold water is circulated. The air loses its moisture to heat exchange and exits to ambient environment or fed to the inlet of the inlet fan 53 feeding roof and side cavities 45 and 47 . An advantage of circulating air is to reduce dust and germ, insects, seed and other undesirable foreign matter into desalination greenhouse 12 . Ultra-violet disinfectant 80 helps classify a crop as organic as no chemical disinfectants or herbicides are used.
[0037] Referring to FIG. 8 , a portion of a possible flow scheme utilizable in conjunction with the desalination greenhouse 21 is shown. A section including the inner shell 25 , outer shell 23 and barrier 81 is shown with a connection to drainage tap 89 . Drainage trap 89 can be connected into a heat exchanger 171 which can be used dehumidify the humid warm air exiting inner shell 25 before being discharged to atmosphere. An air inlet 175 is shown and which may optionally be connected either upstream or downstream of the exit fan 55 seen in FIG. 1 . An air outlet 177 would typically be vented directly to atmosphere 61 . A number of shutoff and bypass valves, storage tanks and piping (not shown) may be used to shutoff, bypass water flow to any of the devices when not in use and store water.
[0038] Heat exchanger 171 exit condensate is preferably collected through exit line 179 and is piped to an insulated underground cold water storage tank 181 . A portion of the desalinated water is transferred by pipe 183 to an insulated underground irrigation tank 185 tank used as an irrigation reservoir. Well balanced fertilizers that include macro and micro nutrients required by the crops may be contained in a fertilizer tank 187 are dosed into the irrigation tank and are topped as the crop uses the fertilizers through a dosing line 189 . One possible method of hydrating the plants may involve cold irrigation water is fed to the crop through piping that connects to soaker hoses laid in parallel under the crop. Excess irrigation water may be drained to the irrigation system tank 185 which is topped with fertilizers and desalinated water as needed.
[0039] Referring to FIG. 9 , a stack of two growing trays, including growing tray 201 and growing tray 203 are shown in stacked relationship to emphasize the efficiency which can be achieved in conjunction with the desalination greenhouse 21 . The growing trays 201 , 203 contain the sprouted seeds to grow the crop. The growing trays have edges 205 which may overlap so as to contain irrigation water within the trays 201 , 203 . Trays 201 , 203 may each have a drainage hole 207 and several openings 209 to admit light to promote growth even though the trays 201 , 203 may be in stacked position. One set of dimensions that may work well for a given growing tray 201 may include a width of about 100 centimeters, a depth of about 120 centimeters, and a depth of about 40 centimeters.
[0040] The growing trays 201 , 203 may also extend along the same direction as a soaker hose 211 . Soaker hoses 211 may extend along the length of the desalination greenhouse 21 and may be fed with cold water from fertilizer added irrigation system 185 seen in FIG. 8 . Several soakers hoses 211 may connect to a header for pressure equalization. Soaker hoses 211 may also deliver a desalinated water rich in nutrients in the form sprayed fog. Irrigation frequency is scheduled to provide the crop with adequate irrigation water, without excess, during, for example, a 10-14 day growth cycle, for forage production. Using the growing trays 201 , 203 shown and soaker hose 211 shown, the root mat for plants grown will be removed with the crop during harvest.
[0041] In terms of overall process operations, the water for feeding crops is typically the desalinated water which originates at the inside surface of the outer shell 23 of the desalination greenhouse 21 resulting from evaporating of sprayed brackish water 73 using relatively hot air within roof and side cavities 45 and 47 and producing, condensation of inside of roof 33 and sides 31 of desalination greenhouse 21 resulting from evaporation of sprayed brackish water 73 onto the roof 39 and walls 37 of the inner shell 23 of the desalination greenhouse 21 and possibly from cooling pads 63 when operating and evapo-transpiration of the crop. Condensate from vertical walls 31 of the outer shell 23 are collected in a fresh water reservoir 85 which is preferably separated from a brackish water reservoir 83 such as by a barrier 81 as was shown in FIG. 8 . Desalinated water may be collected in an insulated underground storage tank 181 and utilized both for crop watering and as a source of fresh water.
[0042] In terms of process, and in further detail as to operation, air forced by inlet fans 53 are distributed evenly throughout the roof and side cavities 45 and 47 . When this air is heated, it evaporates sea or brackish water 73 on the exterior surface of the inner shell 25 . Downward flow of brackish water 73 is delayed by grooves 93 , 103 or 113 of panel 91 , 101 , 111 which make up the roof 39 and side outer surfaces of vertical walls 37 , except for doors 59 and vents associated with the inlet and exit fans 53 and 55 . Transparent roof 33 of outer shell 23 of the desalination greenhouse 21 preferably passes maximum light and heat to roof and side cavities 45 and 47 . Roof 39 and vertical sides 37 of inner shell 25 of desalination greenhouse 21 is wetted with a thin sheet of brackish water 73 , of about two centimeters or less thick, fed from a source of sea or brackish water 73 from brine distribution header pipe 71 by a low pressure pump and spread evenly as guided by grooves 93 , 103 or 113 of panel 91 , 101 , 111 . Cool air from to roof and side cavities 45 and 47 produced by hot air giving up its heat to vaporize water, especially where brackish water 73 is heated in a black lining sun exposed section of the outer section of the desalination greenhouse 21 . As inlet air is heated its relative humidity drops. It then passes through the cooling pads 63 where it may pick up more moisture and cools the inner shell 25 of desalination greenhouse 21 . Brackish water 73 on the roof 39 of inner shell of desalination greenhouse 21 is cooled through evaporation and transmits this cooling effect through panel 91 , 101 , 113 to the inner shell 23 of desalination greenhouse 21 to aid in the cooling of the crop environment and condensation of moisture on the inside of the outer section 23 of the desalination greenhouse 21 . Cool air is blown into inner chamber 43 through the cooling pads 61 .
[0043] When roof 39 of the inner shell 25 is not wetted, as in winter when crop water requirement and cooling are not required, hot air passes through water soaked cooling pads 61 to pick up moisture to produce cool air within inner chamber 43 and to produce cold water where a coil is provided in the cooling pad 61 . Cool air will then exit evaporative cooling pads 61 into the inner chamber 43 of the inner section 25 of the desalination greenhouse 21 to cool growing crops and then exit through exhaust fans 55 which operate at lower pressure than forced air fans 53 to maintain positive pressure in both the inner chamber 43 and the roof and side cavities 45 and 47 . In the alternative, exhaust fans 55 can be minimized or eliminated with certain designs, particularly a passive exit where overall pressure and air flow in the desalination greenhouse 21 is maintained high.
[0044] The forage crop production system in the desalination greenhouse 21 is and can be a 24/7 production system. A quantity of the seeds, depending on the size of the growing tray 201 , may be soaked in disinfected water for 24 hours, then drained and covered to germinate in a pail or other container. The seeds may be irrigated with mist nutrient twice a day. Within 3-4 days the germinated seed may be spread in a growing box such as growing tray 201 and placed on a conveyer belt or rollers. The growing trays 201 may be stacked 4-6 high to utilize the inner chamber 43 of the desalination greenhouse 21 effectively. The growing trays 201 may have openings 207 on the sides for light, ventilation and irrigation. The growing trays 201 may be irrigated with a mist of nutrient rich desalinated water. A conveyor built/roller (not shown) can be operated daily to move ⅛ to 1/10 the distance per day so that a crop has an automated harvest indication each day after it has been on this type of moving belt for 8 to 10 days.
[0045] The crop, including the roots, may be tipped from the growing tray 201 and into a tub grinder which may cut or otherwise process the crop and feeds it into a wagon or conveyance to be transported fresh to its needed consumption point, such as to a grazing animals for feeding. A typical desalination greenhouse if 1000 square meters area, producing 4 tons of barley forage per day. It will use 50 cubic meters of sea or brackish water per day compared to 10,000 cubic meters per day in field production of sweet water. The energy requirement is 96 KWH per day for the fans. Conventional Reverse Osmosis desalination alone will require 200-400 KWH per day.
[0046] Controls of the desalination greenhouse 21 , not shown, may be used to control the equipment set forth and other equipment. Equipment controlled includes ventilation, evaporative cooling, spraying and use of both fresh and brackish water, irrigation, vortex device 161 operation, warning systems, pumps and other functions. The advantages of desalination greenhouse 21 are to desalinate brackish water 73 for potable and agricultural use and insulation property of two preferably transparent bodies, as the bulk of the internal and external shells 25 and 23 , with air in between within roof and side cavities 45 and 47 which enables a level of control and combine to save major running expenses compared to conventional greenhouse operation. The brine distribution header pipe 71 sprinkling system within the roof and side cavities 45 and 47 creates a sheet of water on the roof 39 and vertical walls 37 of inner shell 25 of desalination greenhouse 21 further insulating it without obstructing light transmission and while cooling inner chamber 43 of desalination greenhouse 21 . The superior properties of water to absorb heat to the extent of 540+ calories per cubic centimeter (cc) when evaporating is an effective cooling mechanism in summer while the outer shell 23 of desalination greenhouse 21 insulates it from cold and snow in winter. Such arrangement exemplified in the desalination greenhouse 21 saves energy and is environmentally friendly.
[0047] Another advantage of desalination greenhouse 21 is the use of the crop growing structure of inner shell 25 of desalination greenhouse 21 as a support structure for the cover of inner shell 25 of desalination greenhouse 21 . Cooling of crop roots using soaker hoses 211 is another advantage of desalination greenhouse 21 for the crop shoots to be enabled to tolerate higher temperatures in their potentially high temperature growing environment. An additional advantage of desalination greenhouse 21 is the ability for sterilization of the air through heat and ultraviolet treatment which enables desalination greenhouse 21 to grow organic crops and reduce insecticide use. A further advantage of desalination greenhouse 21 is use of natural lighting while providing a general thermal insulated inner section 25 of desalination greenhouse 21 .
[0048] Another advantage of desalination greenhouse 21 is the heating of air for use for effective evaporative cooling where it would otherwise be ineffective in humid areas. A further advantage of the desalination greenhouse 21 is the flexibility and efficiency of using many features independently, especially heating and cooling which contributes to an overall cost reduction. A further advantage of the desalination greenhouse 21 is the use of renewable energy for some or all of its operations. The aforementioned advantages makes the desalination greenhouse 21 simple to operate and competitive especially in developing countries where fuel is expensive and potable water may not be available.
[0049] While the present invention has been described in terms of a desalination greenhouse 21 and components which can be used with control to affect (1) fresh water production, (2) quick crop growing times, (3) combination summer and winter operating configurations, the construction and process operation of a desalination greenhouse within the teaching above can be used to make a wide variety of alternate variations thereof.
[0050] Although the invention has been derived with reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. Therefore, included within the patent warranted herein are all such changes and modifications as may reasonably and properly be included within the scope of this contribution to the art. | 4y
|
BACKGROUND
The invention relates to a process and a device for melting glass starting with vitrifiable materials, a device more commonly called a melting furnace, continuously to feed melted glass to forming equipment for flat glass such as rolling or float equipment, or for hollow or cut glass like numerous forming machines, or for insulation glass (glass wool, rock wool), or for glass for reinforcement fibers or even special glass for television screens or others.
The invention can be applied to all types of melting furnaces having production capacities for melted glass that can range, for example, from batches of 10 tons/day up to 1,000 tons/day and more.
This type of furnace usually consists, as is known, of a series of compartments emptying into one another and each having specific functions and dimensions. The furnace must indeed be able to melt vitrifiable materials and guarantee the chemical and thermal homogeneity of the glass once it is melted.
Furnaces can be placed in two broad categories according to the heating method used to melt the vitrifiable materials in the melting compartment:
on the one hand, there are electric melting furnaces, called "cold vault," where melting is performed by electrodes that are immersed in the depth of the melted glass, which is known, for example, from patent EP-B-0-304 371.
On the other hand, there are draft furnaces, also called regenerative furnaces, known notably from U.S. Pat. No. 4,599,100. In this case, the heating power is provided by two rows of burners generally operating with a fuel/air mixture, and in alternation; the combustion gases then alternately reheat one or the other of the two regenerators placed opposite one another on both sides of the melting compartment and connected to the latter. The combustion gases are thermally exhausted by stacks of refractories that comprise these regenerators, refractories that then return the heat thus stored to the melting compartment. This method of heating is efficient and widely used, although it is not without certain inherent drawbacks. Thus the energy cost of fuel/air burners is relatively high. Besides, the operating system of burners that are "activated" alternately with cycles on the order of 15 to 60 minutes is not the most simple to control rigorously and can cause a discontinuity in continuous manufacturing and the equilibrium of the temperatures is affected. Their use further leads to introducing, into the melting compartment, a significant amount of air, thus of nitrogen, from which there is an increased risk of seeing form a certain amount of polluting gases of the NO x type that must then be treated.
Further, the large amount of special and costly refractories necessary for manufacturing regenerators significant raises the price of construction of the furnace.
The object of the invention is thus to mitigate the drawbacks connected with the use of draft furnaces by proposing a new type of draft heating that greatly reduces the energy cost and the material cost for construction of the furnace, that simplifies its operating method, while guaranteeing that melted glass of at least as high a quality is obtained.
The invention also has the object of reducing the wear of the refractories comprising the walls of the furnace and thus of increasing the lifetime of the furnace.
The object of the invention is a furnace for melting vitrifiable materials, a furnace comprising a melting (or melting/refining) compartment for glass equipped, in the upstream part, with at least one opening intended to be fed with vitrifiable materials with the help of charging devices placed opposite said opening. In the downstream part, said melting compartment comprises at least one exit opening for melted glass emptying into one or more successive downstream compartments intended to convey melted glass toward the forming zone. According to the invention, the melting of vitrifiable materials is performed, in the melting compartment, essentially by at least one fuel oil and/or gas burner, the combustive material being formed mainly of essentially pure oxygen, at least 50% of the combustive material necessary for the desired combustion being supplied separately by at least one oxygen lance. Essentially pure means, according to the invention, at least 80% and preferably at least 90% oxygen. Separately means separate arrival points for the fuel oil and/or gas on the one hand and for the oxygen on the other hand. Fueled intended for use with the operation of the burners are those typically used for glass melting furnaces including fuel oil and gas.
In the framework of the invention, the terms "upstream" and "downstream" refer to the overall direction of flow of the melted glass through the furnace. Melting compartment means the melting compartment and the melting/refining compartment.
To choose, according to the invention, a method of heating combining burners and oxygen lances supplying at least 50% of the oxygen separately indeed offers a whole series of advantages compared to more conventional burners operating notably with an air-type combustive material, or even compared to oxygen burners supplied with a stoichiometric amount of oxygen.
This method of heating with oxygen makes it possible to eliminate, first of all, the traditional operation by "inversion" for draft furnaces: the oxygen burners can maintain a constant operating regime over time, which makes the use of the furnace simpler, this continuous operation is more regular and makes it possible to have much more fine adjustments than with operation by inversion. Especially the presence of regenerators made of stacks of costly refractories, susceptible to wear, can be completely eliminated. The oxygen burners thus are able to heat the vault of the melting compartment and the so-called "heating chamber" volume between said vault and the plane of melted glass, continuously and without having to use regenerators.
The atmosphere that prevails above the plane of the glass in the melting compartment is much more stable and controlled, which can prove to be significant for the production of so-called special glasses.
Further, the thermal efficiency of this type of burner is notably higher than that of conventional burners operating with an air-type combustive material, because of the absence of nitrogen, which considerably decreases the volume of fumes generated. Thus considerable reductions in energy cost are obtained overall, and this type of burner makes it possible also to envision considerable increases in the specific draw of the furnace.
The fact that the burners chosen according to the invention introduce a very small amount, almost none, of air into the melting/refining compartment very greatly reduces the possibilities for forming NO K type polluting gases, making it all the more less costly to treat the combustion gases exhausted from the compartment.
Further, always with respect to conventional burners, the oxygen burners make it possible to introduce, into the melting compartment, a much smaller volume of gas and, similarly, the volume of gas resulting from the combustion is likewise greatly reduced as already mentioned. This means that it can be envisioned to reduce the volume of the so-called "heating chamber" mentioned above, notably, for example, by slightly lowering the vault of the melting compartment which, here again, tends to reduce simultaneously the energy cost and the construction cost of the furnace itself.
Everything, thus, in using oxygen burners operating without inversion contributes to achieving a more reliable furnace, less costly in its design and one that makes it possible to have energy savings that can go up to well beyond 15% with respect to a conventional draft furnace of similar dimensions.
However, when essentially pure oxygen is used as a combustive material in fuel oil and/or gas burners with so-called stoichiometric amounts, the flame temperature obtained at the plane of the exit of the burners is higher than the flame temperature using air as the combustive material. A rapid deterioration of the refractories comprising the walls of the furnace, notably around the tip of the burners, can thus result.
An object of the invention is thus a process for melting vitrifiable materials in a melting compartment, continuously to feed melted glass to glass forming equipment in which the melting of vitrifiable materials is performed essentially by the combustion of a fuel oil and/or gas mixture with essentially pure oxygen, the supply of fuel oil and/or gas to the melting compartment being performed at least at one point that has a deficiency of oxygen with respect to stoichiometric amounts, at least 50% of the oxygen corresponding to the total combustion being supplied separately at least at one different arrival point.
This supply of at least 50% of the oxygen necessary for total combustion by at least one different arrival point and preferably by several different arrival points further yields a greater flexibility for regulating the temperatures in the melting compartment, the zones(s) of the compartment where the oxygen is supplied generally corresponding to the point at which it is desired to control the temperature level.
Further, the feed of the burners with a deficiency of oxygen, according to the invention, and the supply of oxygen, in combination, by wisely distributed oxygen lances, notably makes it possible to have a controlled flame temperature called "low temperature, low NO x flame." Further, the fact of inserting oxygen between the flame and the walls of the furnace assures an oxidizing atmosphere at the walls. The flame is also at a distance from the walls and thus the phenomenon of exudation and attack on the refractories in their vitreous phase is decreased.
The combination of oxygen burners fed with a deficiency of oxygen and oxygen lances results in a better distribution of the flame over the mixture and the glass bath. This better distribution of the flame makes it possible to lower the vault temperatures and to increase the temperatures of the bottom. Finally, this makes it possible likewise to envision increases in the specific draw of furnaces of 10 to 30%.
As indicated above, the supply of oxygen by burners on the one hand and by oxygen lances on the other hand, is made thus with 0 to 50% only by burners and the rest, to 100% of the oxygen necessary for combustion, by oxygen lances.
Preferably, the oxygen supply is made with at least 80% separately by the oxygen lances.
Finally, all or essentially all the oxygen can be advantageously supplied separately. Thus any incident at the tip of the injector (burner) in the case of fouling or run-out, in particular in the case of special glasses, is avoided. All or essentially all the oxygen is meant to mean 100 to about 95% of the oxygen.
According to one of the characteristics of the invention, the flame of a burner is fed by successive feeds of oxygen to the flame and at certain locations in the furnace to have the desired flame temperature.
However, the very favorable assessment described above would be compromised if, contrary to the invention, the entry of air into the melting compartment, coming from downstream compartments, were not avoided. In the opposite case, indeed, the risk is run of recreating a certain amount of NO x type polluting gases in the melting compartment and the saving realized in terms of energy in this compartment is decreased considerably. The arrival of air can be prevented with the help of sealing means for the gases of the melting/refining compartment with respect to the rest of the furnace. The or these means of sealing thus "insulate" the atmosphere prevailing above the glass melted in the melting compartment from the atmosphere of the successive downstream compartment(s) that are adjacent to it. These "downstream" compartments are intended to condition the glass, i.e., are essentially intended to progressively cool it until it reaches its forming temperature, to perfect its chemical and thermal homogeneity and to eliminate foreign bodies of the unmelted type or particles of refractory material. Now this thermal conditioning can be performed in one or the other of these so-called downstream compartments by using, as is known, alternatively or in combination, reheating means, for example conventional fuel-air burners, and cooling means that introduce the air in a large amount at ambient temperature into these compartments. Thus it is necessary to prevent these types of gases from "returning" toward the melting/refining compartment so they do not disturb its very controlled atmosphere.
Of course if the downstream compartment(s) are designed so that, for example, they use cooling means without the introduction of air, and have an atmosphere not composed of air, these sealing means are no longer indispensable.
According to an embodiment of the device according to the invention, the burners or injectors are distributed in rows by being alternated with oxygen lances in the upstream and/or downstream wall, and or the lateral walls parallel to the glass bath, with a number and an inclination of +5 to -15 degrees, depending on the structure and dimensions of the furnace, and on the position with respect to the glass bath. The burners and oxygen lances empty into the melting/refining compartment through superstructure walls whose sections can be very reduced and do not alter the thermal insulation of the unit. The burners can be independent or gathered in groups of burners whose heating power is regulated independently from one group to the next. The groups are placed essentially perpendicular to the axis of the furnace on the lateral walls and essentially parallel to the furnace on the upstream and downstream front walls, with the possibility each time of being oriented from 0 to 20 degrees with respect to these axes and to the horizontal plane. The heating can be modulated and regulated in an optimal way in the entire melting/refining compartment and can achieve all the desired temperature profiles, according to the types of melted glass and fabrication. Other arrangements of burners and oxygen lances are of course possible.
There can be provided, in the melting/refining compartment, mechanical means of the babbling type to accelerate the convection or auxiliary heating means of the type where electrodes are- immersed in the glass to adjust or correct the temperature profile.
The fact of having eliminated the recuperator or the regenerators reduces the number of openings, frees the entrance and the space around the furnace, which makes it possible better to insulate it and facilitates its maintenance.
To recover, to the maximum, the heat energy from the fumes coming from the combustion of the burners in the melting compartment, preferably the exhaust openings are placed behind the openings for feeding the vitrifiable materials, the fumes following a path from the center of the furnace toward the walls (making a screen between the flame and the walls) to return from downstream toward the upstream to enter above the charging zone where the vitrifiable materials are floating on top, which can thus advantageously be preheated.
Several positions can be adopted for the feed opening(s) for vitrifiable materials. The latter can be made, on the one hand, in the one or two lateral walls, on the other hand, in the front wall of the melting compartment.
An advantageous solution can be two symmetrical openings opposite one another in the lateral walls.
It is possible to provide the auxiliary exhaust openings for the fumes either in the upstream front wall or in the lateral walls of the melting/refining heating chamber.
These fumes, once they exit the heating chamber of the furnace, are still relatively hot, it can be provided to convey them into heat recovery devices or devices for preheating vitrifiable materials before they are charged. They can still be used to preheat oxygen.
Another advantage of the invention using the combination of gas and/or fuel oil burners (or injectors), fed with a deficiency of oxygen, this deficiency being able to be total, and oxygen lances, is a more flexible regulation of the flame and notably a regulation of its position with respect to the glass mixture, the flame being drawn toward the location where the oxygen is supplied.
This advantage, notably, makes it possible to design variants of the device according to the invention in the arrangement of burners and oxygen lances.
Separate supply of oxygen generally means, according to the invention, a supply of oxygen at one or more points that are at least 5 cm and preferably at least 10 cm away from the point at which the fuel oil and/or gas is supplied, i.e., from the tip of the burner. The oxygen can advantageously be supplied at two points around each burner, and preferably at a level lower than the level at which the fuel oil and/or gas is supplied.
Thus the invention envisions likewise a unit that can be used in the heating system combining burner and oxygen lances according to the invention. This unit comprises a refractory block equipped with a passage for emplacing a burner, this passage being flared notably in the form of a truncated cone toward the face intended to be oriented toward the interior of the furnace, and two passages placed at equal distances and at more than 5 cm and preferably at more than 10 cm from the axis of the burner passage, these two passages intended for the emplacement of two oxygen lances being further located at a level lower than the level of the burner. The unit can be equipped with a burner and with two oxygen lances.
This arrangement of oxygen lances with respect to the burner makes it possible regulate the flame very well while notably avoiding excessive heating of the refractory where the burner tip is located.
Other characteristics and advantages of the invention come out of the following description with the help of the figures that represent:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1, a view in a lengthwise section of a furnace according to the invention,
FIG. 2, a plan view of this furnace,
FIG. 3, a possible way of operating a furnace according to the invention,
FIG. 4 and 5, a unit comprising a refractory block and a burner/oxygen lance combination according to the invention.
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1 and 2 diagrammatically represent melting/refining compartment 1 of the melting furnace according to the invention. This compartment is delimited by a bottom 2, a vault 3, upstream walls 4, downstream walls 5, and lateral walls 6-7. The level of the melted glass is indicated in FIG. 1 by horizontal line X. The glass runs toward the downstream compartment by narrow passage 18.
This furnace comprises two main zones:
melting zone 8 where vitrifiable materials 9 are charged, floating on top of the melting glass,
zone 10 for melting/refining, this zone is delimited by a lower vault 3, which makes it possible notably to increase the refractory.
In this embodiment, a method of lateral charging of the vitrifiable mixture is provided in zone 8. Of course, other embodiments according to the invention can use a front method of charging.
The feed opening represented in FIGS. 1 and 2 consists of two symmetrical openings 11 and 12 that connect the melting compartment to two attachments 19, 20 in which the charging with vitrifiable material is performed, on both sides in this example.
Openings 13, 14 for exhausting the combustion fumes are provided behind feed openings 11, 12. The fumes are thus forced to follow an exhaust path from the center of the furnace, going along the walls and the vault, and hanging over the yet unmelted vitrifiable materials, which improves the energy yield of the furnace.
The fumes can then be used to feed any heat recovery device, or in a preheating system for vitrifiable materials. Auxiliary openings 16 for exhausting the fumes can also be provided in the front and lateral walls.
In all the walls: front, lateral, downstream, small openings are made to introduce injectors 15 or burners represented in the figures by a solid arrow, oxygen lances 17 represented by a dashed arrow. The burners and oxygen lances are placed above the plane of the glass to form groups, or individually to mark a hot point and to achieve an optimal distribution of the thermal exchange between the flames and the glass bath; each group of burners or independent burner can be regulated by heat power independently, which makes it possible to obtain the desired temperature profile at any point and at any moment. Further, the oxygen lances are placed at various locations on the walls to accompany the flame and to make it so that, along the distance covered by the flames, there is no over-oxygenation resulting in too hot a flame or, in contrast, a lack of oxygen, which results in a reduced flame. Indeed, in the two cases, a premature wear of the refractories of the furnace can occur.
The use of burners and oxygen lances functioning continuously assures a thermal yield clearly higher than that of conventional burners by using an amount of combustive material that is reduced with respect to the air, which results in a volume of fumes that is reduced by about 80%. The design of the melting/refining heating chamber can be reduced in volume without counterindication for the operation of the furnace, resulting in a savings in construction material for the furnace. Likewise, the burners and oxygen lances do not introduce any air, thus no nitrogen, into the furnace, which prevents the formation of NO x -type polluting gases. The separate oxygen feed for the burners prevents a deterioration of the refractories, notably at the tip of the burners.
To guarantee the advantages of all the oxygen it is necessary to eliminate any introduction of air into the melting/refining compartment. It is necessary that all the openings between the heating chamber and the exterior be closed (expansion joint, draft holes, etc.).
Further, the exit(s) for the glass from the melting/refining compartment toward the forming compartments are made so that there are no recirculation belts for the melted glass between the melting/refining zones and the feed zones for the working compartments, nor any atmospheric exchange. To do this, known feeding and sealing means are used: feed by throat and channel, feed by channel with hanging or immersed barrier, feed by channel with suspended screen and barrier. Such feed or sealing means is shown schematically at 18' in FIGS. 1 and 2.
The heating system according to the invention makes the use of the furnace more reliable with less costly fabrication. It achieves a constancy of the atmosphere in the melting compartment that, with adequate refractories, makes it possible to increase the lifetime of the furnace. Indeed, the temperature variations are one of the causes of wear of the refractories. Further, atmospheric pollution is greatly decreased.
Thus, for example, the heating system according to the invention makes it possible to lower the temperature of the vault of the furnace by about 50 to 80° C., and to increase its bottom temperature by about 10 to 20° C. with respect to known systems for a given melting temperature. Further, the temperature at the tip of an oxygen burner is decreased by about 60° C. thanks to the separate oxygen feed.
FIG. 3 represents diagrammatically the operation of a heating system according to the invention for an end-fired furnace.
A burner 21 fed with fuel oil and/or gas, but essentially without oxygen is placed in upstream wall 22 of furnace 23. Part of the oxygen necessary for combustion is supplied by two oxygen lances 24 placed around burner 21 in the upstream wall. The amount of oxygen supplied by these two lances corresponds to about 20 to 40% of the oxygen necessary for combustion.
Other oxygen lances 25 are placed in the walls of the furnace. Four pairs of lances 25 are represented here. Each of these pairs supplies about 15 to 20% of the necessary oxygen. Thus the oxygen is supplied accompanying flame 26 along its path so as to have a flame that is neither too hot nor too cold.
When it is desired to increase the draw of the furnace, other burners 27 can be placed between pairs of oxygen lances 25 and likewise the oxygen supply can be increased by these lances and/or other additional lances. The melted glass is removed by exit 42 toward the downstream compartment.
FIGS. 4 and 5 represent a unit 28 that is advantageously used for heating according to the invention combining a burner and oxygen lances. This unit comprises a refractory block 29 provided with a central passage 30 ending flared in the form of a truncated cone 31 whose axis 32 is slanted by about 15 degrees toward the bottom with respect to the horizontal.
This passage 30, flared toward face 41 and intended to be oriented toward the interior of the furnace, elongates opening 33 provided in a composite plate 34 for installing burner 35 (not represented in FIG. 5) with the help of a cylindrical sleeve 36.
Two other passages 37 placed symmetrically, under the axis of the burner, and outside truncated cone 31, are provided for installing, with the help of cylindrical sleeves 38, two oxygen lances (not represented). The axes of these two passages 37 are located at a distance greater than 10 cm from axis 39 of the tip of burner 35. Attachment means 40 are provided to attach composite plate 34 to refractory block 39.
This heating unit makes it possible notably to have a very good regulation of the flame temperature, neither too hot nor too cold. It prevents, in particular, soiling of the tip of the burner, and also a rapid deterioration of the refractory near the tip of the burner. | 4y
|
BACKGROUND OF THE INVENTION
Eccentrics are used to convert rotary motion into reciprocating linear motion, or vice versa. The amplitude of reciprocation, or throw, may be fixed or variable. In variable throw eccentrics, the adjustment is commonly accomplished by stopping the operation of the device and adjusting the relationship of the parts of the device.
In many applications, it would be desirable to be able to adjust the throw while the eccentric is in motion. In the particular application of metering seed or fertilizer in agricultural seeding implements such as air-seeders, with a suitable metering device a continuously variable throw eccentric drive would allow the rate of application to be varied during operation. In the emerging field of precision farming such desired rates change while passing over various parts of a field. Global positioning systems are used to transmit the precise field location to a computer which can then send the appropriate signal to the metering drive to adjust the rate of application. The metering drives presently used to respond to these signals are expensive and cumbersome.
Similar uses can be seen for metering in other applications such as feed mills, pharmaceutical manufacturing, mines, etc. As well, such a variable throw eccentric could be well utilized in driving shakers, vibrators and the like.
Starting torque requirements could be reduced by an eccentric device which was adjustable in operation. A short throw provides more torque which could be an advantage in start-up, with the throw being gradually increased. The eccentric drive motor could be started with the eccentric in neutral, or zero throw. As the throw is increased, the shaker would gradually attain the desired action. Such a device would act essentially like a clutch. Starting torque requirements often dictate the use of a motor with more power than that required for continuous operation. An example of a conventional variable throw eccentric is described in U.S. Pat. No. 4,249,424.
Conventional eccentric devices are costly and prone to mechanical difficulty.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an eccentric where the amplitude of reciprocation, or throw, is continuously variable, during operation, from zero to a maximum.
The invention accomplishes these objects comprising substantially a sleeve, said sleeve having a first end and a second end, rotatably mounted on a frame; a control shaft, said control shaft having an inner end and a projecting end, fitted inside said sleeve such that the projecting end of the control shaft projects from the second end of the sleeve and such that said control shaft may move freely within the sleeve along the axis of said sleeve from a withdrawn position, where the said projection is minimized, to a projected position where the said projection is maximized; hinge point support means fixedly attached to the sleeve and supporting a first hinge point at some distance from the axis of the sleeve; a throw arm, with a hinge end and a pivot end, the hinge end being hingably attached at the first hinge point such that the said arm may move freely in a plane generally defined by the first hinge point and the axis of the sleeve; a pivot attachment point at the pivot end of the throw arm; a linkage member, having a shaft end and an arm end, the shaft end being hingably attached to a shaft hinge point on the control shaft near the projecting end of the control shaft and the arm end being hingably attached to an arm hinge point at a mid-point of the throw arm, which hingable attachments are such that the pivot attachment point at the pivot end of the throw arm is in alignment with the axis of the sleeve when the control shaft is in the withdrawn position and moves away from said axis when the control shaft is moved towards the projected position; means to move the control shaft from the withdrawn position to the projected position; and a crank arm, pivotally mounted to the pivot point at the pivot end of the throw arm.
The provision of an eccentric wherein the amplitude of reciprocation is continuously adjustable during operation from zero to a maximum, may also be accomplished where the invention comprises a fixed throw eccentric reciprocally driving a member which is mounted at a pivot point at one end; a by crank arm, having a driving end pivotally connected to the driven device at one end, and a driven end engaged in a channel on the reciprocating member; an actuator attached to the crank arm moves the driven end of the crank arm along the channel, from the pivot point, where the amplitude of reciprocation is zero, to points on the channel removed from said pivot point, thereby achieving various amplitudes of reciprocation.
As the crank pivot point moves away from the axis of rotation, the amplitude of reciprocation will increase from zero to a maximum. This movement is simply and economically accomplished by the invention. The present invention also has the advantage of providing a free eccentric point for driving shaker cranks and so forth.
It is contemplated that the invention will be useful both for converting rotary motion to reciprocating linear motion, and vice versa.
It is also contemplated that in some applications it may not be desired to adjust the amplitude of reciprocation to zero, in which case the eccentric point could be moved from a point removed from the axis of rotation or pivot point, to a different position removed from the axis or pivot point.
BRIEF DESCRIPTION OF THE DRAWINGS
While the invention is claimed in the concluding portions hereof, preferred embodiments are provided in the accompanying detailed description which may be best understood in conjunction with the accompanying diagrams where like parts in each of the several diagrams are labeled with like numbers, and where:
FIG. 1 is a plane view of the preferred embodiment;
FIG. 2 is a cross sectional view of the preferred embodiment;
FIG. 3 is a plane view of the preferred embodiment showing the control shaft in the projected position and
FIG. 3A is an end view showing the degree of eccentricity being a maximum;
FIG. 4 is a plane view of the preferred embodiment showing the control shaft in the withdrawn position and
FIG. 4A is an end view showing the degree of eccentricity being zero;
FIG. 5 is a plane view of an embodiment utilizing a shaft mounted linear electric actuator to adjust the throw arm and thereby the amplitude of reciprocation;
FIG. 6 is a plane view of an embodiment utilizing a shaft mounted rotary electric actuator to directly adjust the amplitude of reciprocation; and,
FIG. 7 is a plane view of an embodiment utilizing a shaft mounted linear electric actuator to directly adjust the amplitude of reciprocation.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows an embodiment of the invention. The invention is an eccentric wherein the amplitude of reciprocation is continuously adjustable during operation from zero to a maximum, comprising a sleeve 3 having a first end 1 and a second end 2 and an axis 10, said sleeve rotatably mounted on a frame 6; a control shaft 7 having an inner end 8 and a projecting end 9, said control shaft 7 fitted inside the sleeve 3 such that the projecting end 9 of the control shaft projects from the second end 2 of the sleeve and such that the control shaft 7 may move freely within the sleeve 3 along the axis 10 of the sleeve from a withdrawn position Y, where the said projection is minimized, to a projected position X where the said projection is maximized; hinge point support means fixedly attached to the sleeve 3 and supporting a first hinge point 14 at some distance from the axis 10 of the sleeve; a throw arm 15 with a hinge end 16 and a pivot end 17, the hinge end 16 being hingably attached at the first hinge point 14 such that the throw arm 15 may move freely in a plane defined by the first hinge point 14 and the axis 10 of the sleeve; a pivot attachment point at the pivot end 17 of the throw arm; a linkage member 19 having a shaft end 20 and an arm end 21, the shaft end 20 being hingably attached to a shaft hinge point 22 on the control shaft near the projecting end 9 of the control shaft, and the arm end 21 being hingably attached to an arm hinge point 23 at a mid-point of the throw arm 15, which hingable attachments are such that the pivot attachment point 18 at the pivot end 17 of the throw arm is in alignment with the axis of the sleeve 3 when the control shaft 7 is in the withdrawn position Y and moves away from the axis of the sleeve 3 when the control shaft 7 is moved towards the projected position X; control shaft movement means to move the control shaft 7 from the withdrawn position Y to the projected position X; and a crank arm 32, pivotally mounted to the pivot point 18 at the pivot end 17 of the throw arm. As illustrated in FIGS. 3 and 3A the linkage member 19 comprises two linkage plates 19a, 19b. Shaft hinge point 22 is provided by a shaft pin 40 through corresponding holes in the linkage plates 19a, 19b and shaft 7. Arm hinge point 23 is provided by an arm pin 41 through corresponding holes in the linkage plates 19a, 19b and throw arm 15.
In the embodiment shown in FIGS. 1 and 2, the sleeve 3 is substantially cylindrical and is rotatably mounted inside a cylindrical housing 4 via sleeve bearings 5, said cylindrical housing 4 being fixed to the frame 6. The drive sprocket 33 is fixedly attached to the sleeve 3.
The hinge point support means in this embodiment consists of a hinge point support collar 13 fixedly attached to the sleeve 3 and supporting a first hinge point 14 at some distance from the axis 10 of the sleeve 3. The pivot attachment point at the pivot end 17 of the throw arm is a ball and socket attachment point 18.
The hingable attachments of the linkage member 19 to the control shaft 7 and the throw arm 15 are such that the ball and socket attachment point 18 at the pivot end 17 of the throw arm 15 is in line with the axis 10 of the sleeve when the control shaft 7 is in the withdrawn position Y and moves away from said axis 10 when the control shaft 7 is moved towards the projected position X.
The embodiment further includes a shaft bearing 24 fixed to the inner end 8 of the control shaft and mounted is in pillow block 25 such that the control shaft 7 rotates freely; a control arm 26 attached to pillow block 25 at pillow block attachment point 27 and to fulcrum 28 at control arm pivot point 29; actuator 30 attached to control arm 26 at actuator attachment point 31.
Is in operation, the sleeve 3 is rotated by external means acting on sprocket 33. This rotation is transmitted through linkage member 19 to the control shaft 7, causing said control shaft 7 to rotate with the sleeve 3, on shaft bearing 24. When the control shaft 7 is in the withdrawn position Y, ball and socket attachment point 18 is in line with the axis 10 of the sleeve 3 and crank arm 32 is at rest. As actuator 30 acts on control arm 26 moving control shaft 7 towards the projected position X, ball and socket attachment point 18 is moved away from the axis 10 of the sleeve 3, and crank arm 32 reciprocates, reaching a maximum amplitude of reciprocation when the control shaft 7 reaches the projected position X. Actuator 30 may be stopped at any point is in the range when the desired amplitude of reciprocation has been attained, and then activated is in either direction to increase or decrease said amplitude.
FIG. 3 shows this preferred embodiment with the control shaft 7 is in the projected position X.
FIG. 4 shows this preferred embodiment with the control shaft 7 is in the withdrawn position Y, a distance D from the projected position X.
FIG. 5 shows the embodiment wherein a linear actuator 34 acts on the throw arm 15 to move the ball and socket attachment point 18 from a point 35 coincidental with the axis 37 of the shaft 35 to a point 38 removed from the axis 37, thereby providing reciprocation.
FIG. 7 shows another embodiment of the invention wherein a linear actuator 34 is fixed to a rotatably mounted shaft 35. Ball and socket attachment point 18 is attached to said actuator 34 such that said ball and socket attachment point 18 may be moved from a point 36 coincidental with the axis 37 of the shaft 35 to a point 38 removed from the axis 37, thereby providing reciprocation.
FIG. 6 shows the embodiment of FIG. 7 wherein a rotary actuator 39 replaces the linear actuator 34.
Is in the embodiments shown is in FIGS. 5, 6 and 7, power and control are passed to the actuators mounted on the rotating shaft 35 by wires 40 through slip rings 41.
The control shaft movement means could be an electrical or hydraulic actuator. It will, however, also be understood that other methods of actuation could also be used and are contemplated within the scope of the invention.
The foregoing is considered as illustrative only of the principals of the invention. Further, since numerous changes and modifications will readily occur to those skilled is in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all such suitable changes or modifications is in structure or operation which may be resorted to are intended to fall within the scope of the claimed invention. | 4y
|
BACKGROUND OF THE INVENTION
The present invention relates to a method to interrupt a media flow through a tubular pipe and a device for utilizing the method.
It is previously known to use various types of valve means to reduce or interrupt a media flow through a tubular pipe. However, these valve means can only be attached to the pipe when the pipe is installed, or, when the pipe is not being utilized for transport of a media flow, unless the type of medium and flow and pressure conditions permit leakage during the time when a portion of the pipe is removed and replaced by a valve means, attached to the pipe as replacement for the removed portion. Such a method can only be utilized in cases involving relatively low pressure and flow speeds, and when the type of medium and the environment permits use of a method involving leakage. Furthermore, such a method of installation is obviously extremely difficult to perform.
OBJECT OF THE INVENTION
The object of the present invention is to disclose a method, and a device for utilizing the method, whereby it is possible to reduce or interrupt a continuous media flow through a pipe, regardless of the type, pressure and speed of flow for the medium. The interruption is also achieved in a minimum of time, effectively, completely without leakage, and the point of interruption can be chosen at random and without preventing the pipe from being used for the intended purpose, i.e. in cases where it is desirable to achieve a temporary interruption of the flow. It is easily realized, that the method and the device according to the present invention thus provides for an extremely large demand, e.g. to accomplish interruption of a media flow such as oil and/or gas leaking from pipe lines connected to maritime oil rings. It is thus possible to prevent damage caused by leakage, and also to extinguish fires at oil or gas wells most effectively, by interrupting the oil and/or gas flow from the well. As an example of further fields of use, the possibility to block a pipe can be mentioned, e.g. used for transport of hot water to radiators arranged within a specific area, e.g. an apartment, and thereafter to connect a flow depending metering means between a point before, respectively after, the point of interruption. It is thus possible to include various types of metering means in existing plumbing installations, e.g. for metering of hot water or heating comsumption, without interrupting the operation of the system.
The method according to the present invention is mainly characterized by the features disclosed in the following main claim, and the device for utilizing the method is mainly characterized by the features disclosed in the subclaims relating to the device according to the present invention.
In order to simplify the understanding the the invention, a number of embodiments for utilizing the method according to the present invention are described below by way of example, the embodiments being shown in connection with a first pipe, surrounded by a second pipe, intended to illustrate the type of tubular pipes generally used for transport of oil and/or gas from maritime wells, connected with an oil rig by means of double pipes, said first and surrounded pipe being the transport pipe for an oil and/or a gas flow. However, it should be emphasized, that the method and the device according to the invention can also be utilized in connection with a single pipe, without a surrounding second pipe.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows, partly in section, divided at a sectional line I--I in FIG. 2, a side view of a device according to the present invention arranged on a vertically extending pipe.
FIG. 2 shows a plan view of the device according to FIG. 1.
FIG. 3 is a cross-sectional view of the device disclosed in FIG. 2, said device being shown in a first and partially flow reducing position.
FIG. 4 is a fragment of the device shown in FIG. 3 in a corresponding cross-section, said device being arranged to totally interrupt the area of the inside pipe and thus also a media flow therethrough.
FIG. 5 is a principal cross-sectional view of a slightly modified embodiment of a device according to the present invention, arranged to partially interrupt a media flow through the inside and surrounded pipe.
FIG. 6 is a principal cross-sectional view corresponding to FIG. 5, the cross-sectional area of the inside pipe, and thus also the media flow, being totally interrupted.
FIG. 7 is a further principal cross-sectional view of a further modified embodiment, arranged to partially interrupt a media flow.
FIG. 8 is a cross-sectional view corresponding to FIG. 7, the device being arranged to completely interrupt the cross-sectional area of the pipe, and thus also the media flow through the pipe.
FIG. 9 is a longitudinal extending section of the embodiment as shown in FIG. 7.
FIG. 10 is a longitudinal extending section of the embodiment as shown in FIG. 8.
FIG. 11 is a partial cross-sectional view of a further modified embodiment of a device according to the present invention, shown immediately before the operation when a substantial reduction of the cross-sectional area of the pipe is achieved.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
With reference to the figures, reference numerals 1 and 2 indicate two housing parts, which can be joined to each other by means of a screw or a bolt connection or similar, thus arranged to sealingly embrace a pipe 3, which in the shown embodiment surrounds a second pipe 4. The second pipe 4 is a transport pipe for the media flow to be interrupted. In order to simplify the drawing figures of the device, the housing parts 1, 2 have been indicated with similar cross-sectional lines, and certain dividing lines are not shown. However, said dividing line is shown in FIGS. 1 and 2, showing flanges to be connected, and the dividing line extends through the housing 1, 2 along the dividing line for said flanges. The housing 1, 2, extends in direction from the pipe 3, 4, and includes two parallel and preferably cylindrical holes 5, 5', which serve as guiding cylinders for two piston means 6, 6', arranged movably in said holes or cylinders 5, 5'. The distance between said holes 5, 5' is so arranged, that the adjacent peripheral portions area arranged at a distance from each other smaller than the inside diameter of the inner pipe 4. The open portions of the holes 5, 5' directed from the pipes 3, 4, are in the shown embodiments arranged closed by means of a lid 7, also being divided along the aforementioned dividing line. Between the piston means 6, 6' and the lid 7, at least one explosive charge 8 is arranged, and an activating means 9 for said charge 8 is indicated extending through the lid 7. Said activating means 9 can obviously be of mechanical, electrical or any other previously known type, depending on the method of initiation for the charge that is desired.
In a basically perpendicular relationship to the holes 5, 5' extending through the housing 1, 2 a tubular cylindrical part 10 extends from the pipes 3, 4, the length axis of said tubular part 10 being arranged corresponding to the center axis of the pipes 3, 4. Said tubular part 10 embraces and acts as a guide for a further piston means 11. A further explosive charge 12 is arranged between the end portion of said piston means 11 directed from the pipes 3, 4 and a lid 13, which seals the open end portion of the tubular part 10. Activating means 14 are also indicated at said lid 13, intended to facilitate initiation of the explosive charge 12.
With reference to the embodiment shown in FIGS. 1-4, FIGS. 1-2 show the device arranged embracing the outside pipe 3, the attachment being made by joining one housing part 1 and the tubular part 10 with the other housing part 2 by means of screws, bolts or similar. As shown in FIG. 2, all piston means 6, 6', 11 are arranged in a position adjacent to the respective lids 7, 13. The end portions of the two parallel piston means 6, 6' directed towards the pipes 3, 4 are arranged to be concave, or in any other suitable manner, in order to improve the material removing action of the piston means 6, 6' when contacting the pipes 3, 4. By influencing a first activating means 9, the explosive charge is initiated, or alternatively the explosive charges 8, which are arranged at the end portions of the piston means 6, 6' directed from the pipes 3, 4. The piston means 6, 6' are thus propelled with high speed in direction towards the pipes 3, 4, and when the front portion passes the pipes 3, 4, two opposed edge portions from the pipes 3, 4 are removed. The piston means 6, 6' are further arranged with a through hole 15, 15', said holes being arranged with the center axis to basically coincide with the center axis of the piston means 11 arranged in the tubular part 10, when the first mentioned piston means 6, 6' have completed their movement.
Thereafter, the second activating means 14 is influenced, and the explosive charge 12 arranged in the tubular part 10 is initiated, whereby the piston means 11 arranged in the tubular part 10 is brought to move with high speed in direction towards the pipes 3, 4, said piston means 6, 6', thus also through the pipes 3, 4, the through flow area thus being partially reduced, as shown in FIG. 3. According to this embodiment, the parallel piston means 6, 6' are joined to each other at the portions directed from the pipe 3, 4, said joint partly acting as a means for maintaining the axis of the through holes 15, 15' in the piston means 6, 6' in a predetermined relationship to the axis of the perpendicular piston means 11, but also maintaining a simultaneous movement of the parallel piston means 6, 6'.
With reference to FIG. 3, it is also shown that the crosswisely directed piston means 11 has a pointed part directed towards the pipes 3, 4, being followed by a cylindrical part, surrounded by a tubular means of a flexible and compressible material 16, said means 16 being arranged between the pointed part of the piston means 11 and a tubular member 17, in the embodiment joined to the piston means 11 by means of a screw thread.
When the piston means 6, 6', 11 have been brought to take up an internally, and also in relation to the tubular pipes 3, 4, locked position, the tubular member 10 can be removed, as shown in FIG. 4, whereafter the tubular member 17 by means of a tool can be rotated in relation to the crosswisely extending piston means 11, first moving the tubular member 17 in direction towards the pointed portion of the piston means 11. The elastic means 16 surrounding the piston means 11 is thus compressed, thereby completely closing the remaining cross-sectional area of the inside pipe 4, thus also completely interrupting the media flow through said tubular pipe 4.
When desired, it is also possible to completely regain original flow capacity through the inner tubular pipe 4. In this case, the crosswisely extending piston means 11 is removed by first bringing the elastic means 16 to the original shape, by unscrewing the tubular means 17 in direction from the forward and pointed portion of the piston means, whereafter the piston means 11 is completely removed, the parallel piston means 6, 6' simultaneously being brought to take up an alternate angular position by a rotary movement, the holes 15, 15' in the piston means 6, 6' thus being prevented from communication with the inside pipe 4. The reduction in the cross-sectional area of the inside pipe 4 which is caused, is of such a small significance, that the reduction in flow capacity is negligible.
It should be emphasized, that the method also gives extremely good attachment properties against the tubular pipes 3, 4. When the parallel piston means 6, 6' are initiated, an extremely good grip with the pipe 3, 4 is obtained, and when the crosswisely directed piston means 11 is activated, such attachment properties are obtained, that the device obviously will remain in position, regardless of existing flow speed and pressure. The device is also extremely suitable for use with pipes containing oil or gas, since there is no risk for fire when attached, in view of the fact that no oxygen is available.
The embodiment shown in FIGS. 1-4 is based on the use of an elastic compressible means 16 in connection with a threaded tubular member 17 in order to obtain total interruption in the inside tubular pipe 4. An alternative embodiment is shown in FIGS. 5-6, the piston means 11 being arranged with a portion having a smaller diameter, formed by means of two conical surfaces 18, also as previously using an elastic and compressible tubular means 16 as a sealing member. According to this embodiment, the tubular means 16 is arranged with stop means, which prevent the tubular means 16 from being moved past a predetermined position. During a continued movement of the piston means 11, the elastic tubular means 16 is pressed out in the inner tubular pipe 4, thereby achieving a total sealing action.
A further alternative embodiment is shown in FIGS. 7-10, the crosswisely extending piston means 11 being arranged with two sealing piston means 19, 19', the facing surfaces by means of a channel 20, arranged in the crosswisely extending piston means 11, arranged to communicate with a medium under pressure, such as a hydraulic or pneumatic medium. Alternatively, said channel 20 can be arranged to communicate with the area behind the end portion of the crosswisely extending piston 11 directed from the pipes 3, 4, the combustion gases in said area creating a pressure forcing the sealing piston means 19, 19' to take up contact with the internal peripherial portion of the inside pipe 4. As can be easily understood, this embodiment also facilitates for a return movement, when desired, of the sealing piston means 19, 19' to a position surrounded by the crosswisely extending piston 11, e.g. by connection of the channel 20 to a vacuum source. The sealing piston means 19, 19' can also be returned by rotating the crosswisely extending piston 11, thereby first applying a pressure to one of the sealing piston means 19 from the medium in the pipe 4, whereafter a further rotary movement is carried out, approximately 180°, thereby also returning the second piston means 19'.
The above described embodiments are used as examples of various methods to accomplish total interruption when the crosswisely extending piston 11 has completed its movement, but it is easily understood, that a number of possibilities exist for accomplishing said interruption, and further examples are therefore not regarded as necessary.
FIG. 11 indicates an alternative method to arrange the parallel piston means 6, 6', thereby completely removing the need for guidance and a corresponding movement. According to this embodiment, the parallel piston means 6, 6' consist of relatively thin wall tubular members 21, 21', arranged with a relatively strong forward cutting wall 22, 22', arranged to remove two opposed wall portions of the tubular pipes 3, 4. Furthermore, a bottom part 23, 23' is shown, arranged to act as a surface against which combustion gases from the explosive charges can act, even though said bottom portions 23, 23' can be excluded in many cases. The crosswisely extending piston means 11 is arranged to penetrate the thin walls 21, 21' when the charge 12 is initiated, which means that the holes 15, 15' are completely eliminated and thereby also corresponding guiding means for the piston means 6, 6'. This embodiment facilitates also in a simpler way rotation of the piston means 6, 6', if the original cross-sectional area of the pipe 4 should be reinstated, after removal of the piston means 11.
All of the embodiments described above with reference to the accompanying drawings concern devices intended for two pipes 3, 4, the inner pipe 4 being the pipe used for transport of a medium. This has been made with regard to the fact, that the method, and devices for utilizing the method, are extremely suitable for interrupting an oil or gas flow from a damaged pipe from a well under water, since the device can be attached by means of both automatic and manual devices, in view of the fact that the device consists of two mutually joinable parts.
Even though no embodiment with one pipe only has been shown, which is a simpler case, the device can obviously also be utilized for such pipes. This fact can easily be illustrated by considering the outside pipe 3 as the outside peripheral portion of a single pipe, the single pipe, and by this example, it is easily understood, that the method, as well as described embodiments for utilizing the method, without modification can also be used for this purpose.
Particularly in connection with single pipes only, means can be arranged which partly compress the wall portions between the parallel piston means 6, 6' in direction towards each other, in which case said compression can be relatively small. This would make it possible for corresponding outside portions of the crosswisely extending piston means 11 to directly create complete sealing action and interruption of the media flow, preferably in connection with a smaller portion of the compressed tubular walls being formed, or removed, to a shape corresponding to the shape of the cross-wisely extending piston means 11.
The method according to the present invention is thus in no way restricted to the shown and described embodiments, since obviously a large number of modifications are possible within the scope of the inventive thought and the following claims. | 4y
|
CROSS-REFERENCE TO RELATED APPLICATION
This application is a divisional of U.S. application Ser. No. 08/761,273 filed Dec. 6, 1996 which claims priority from provisional application number 60/009,065 filed on Dec. 8, 1995.
FIELD OF THE INVENTION
The present invention relates generally to apparatus and methods for in situ construction of subsurface containment barriers for containing hazardous waste materials buried under the earth, and more particularly to a method of constructing a vault to encapsulate such hazardous materials so that contaminants are not released into the air or surrounding or underlying strata. The present invention further relates to a means for monitoring the continued integrity of the vault over many years and to a means for repairing any breaches which might occur over time.
BACKGROUND OF THE INVENTION
In the early days of the nuclear age, contaminated debris and undocumented low level radioactive waste were buried in shallow trenches. Other waste materials were placed in underground storage tanks. These burial areas are now considered to pose a unacceptable risk to the environment. Excavation and removal of these wastes is potentially dangerous and very expensive. The concern is that excavation of such sites could release airborne radioactive contaminants which would pose a substantial harm to personnel and nearby residents. There have been a number of solutions proposed for containing these sites. Some of these solutions include slant drilled jet grouting, soil freezing, soil dehydration, tunneling, and chemical grout permeation. Others have taught vertical drilling and hydraulic fracturing as a means of forming a bottom barrier.
U.S. Pat. Nos. 4,230,368 and 4,491,369 to Cleary and others have disclosed the concept of displacing soil blocks containing the contaminants. This is accomplished by making a narrow vertical trench around the perimeter of the soil and forming a horizontal fracture under the site through injection of a fluid under pressure. The horizontal fracture intersects the vertical perimeter trench. A seal is created along the surface areas of the vertical perimeter trench as continued injection of pressurized fluid into the horizontal fracture causes the block of soil within the perimeter to be lifted upwards.
The injected fluid may also become a sealant to produce a barrier surrounding the block like a basement. U.S. Pat. No. 4,230,368 to Cleary discloses that the density of the fluid is a factor in reducing the pressure needed to displace the block but does not contemplate use of fluid densities greater than those achievable with locally excavated soil materials in a clay slurry. This is by definition, less dense than soil. Gel strength of the fluid is mentioned as the primary means of sealing the perimeter opening. Such methods produce both the initial fracture and upward displacement by increasing hydrostatic pressure on the bottom of the block.
The problem with this approach is that hydrostatic pressure will cause fractures to propagate along the plane of least principal stresses. It is not possible to verify the final location and limits of such fractures in a radioactive waste site. The thickness and continuity of such fractures can not be verified. Because of the potential for uncontrolled fracturing into and beyond the contaminated material this method has not been used to produce any type of containment structure in radioactive waste sites.
The inventor's previous invention, U.S. Pat. No. 5,542,782, which is hereby incorporated by reference, describes a means of cutting vertical and horizontal barriers with high pressure jets of grout slurry and teaches the benefits of constructing such barriers from grout materials which are of a density equal to or greater than that of the overburden. This reference also teaches that the thickness of a horizontal grout barrier may be increased by introduction of a grout slurry which is sufficiently dense so as to result in net upward forces on the soil which heave the land surface upward, however few details of the method or apparatus to accomplish this are described.
SUMMARY OF THE INVENTION
The present invention is directed to improved methods and apparatus for constructing a thick horizontal barrier through buoyant block displacement. The present invention provides a new means for cutting the soil with a cable saw and details a practical apparatus for introducing a block displacement fluid to multiple cuts under a large multi-acre site. The subject invention also provides an improved means of cutting a thin horizontal barrier with high pressure jetting apparatus, which is more practical for application of chemical grouts and has an improved means of joining adjacent cuts to previous ones and recovering from equipment breakage.
The present invention uses a combination of trenching, horizontal directional drilling, diamond wire quarry saw methods, or high pressure jetting to cut a thin gap under and around a block of soil containing the contamination. As this "cut" is formed, it is filled with a high-density, low-viscosity fluid grout. This thin channel of this dense fluid extends back to the surface and so exerts a hydrostatic head against the soil. This proprietary fluid is so heavy that the soil and rock will literally float on a thin layer of the fluid. This keeps the cut open and prevents the weight of the soil block from squeezing the fluid out from under it. After the block has been completely cut loose from the earth, additional dense fluid is pumped and poured into the cut. This additional fluid exerts a buoyant force on the block and causes it to rise out of the earth. The dense fluid is designed to slowly harden over a period of weeks to form an impermeable barrier. Use of the head of the dense grout fluid instead of attempting to pressurize the fluid to support the block is a subtle but important innovation. It eliminates the difficulties of sealing the vertical perimeter trench and also prevents uncontrolled fracturing of the grout into the waste burial area. If any of the grout fluid should find a crack in the active waste area it will do no more than fill it. It can not spurt up to the surface and form fountains of contaminated liquid, as it could do if it were under pressure. While the grout under the block is liquid an impermeable barrier sheet, such as HDPE (high density polyethylene extrusion), may be pulled under the floating block.
After the "moat-like" barrier around the soil block has hardened, a gravity-anchored, air-tight cap structure is built on top of it. The HDPE liner under the block may be fusion bonded to the HDPE liner in the cap to achieve a very high degree of containment integrity. Passive soil gas pressure sensors under the cap and similar sensors in the ground outside the cap monitor the air pressure changes inside the structure as a function of normal atmospheric pressure changes due to weather. This data allows passive monitoring of the integrity of not only the horizontal barrier but also the entire containment structure. Moisture, sound, and chemical tracer levels may be passively monitored as leak and leak location indicators. Repair of damage is also possible by flooding the structure with liquid grout.
A wire saw may also be used with molten paraffin grout to form a thin barrier roughly the thickness of the steel cable. This method maintains a circulating supply of molten paraffin in the pulling pipes which is ejected through holes in the pipe adjacent to the area being cut. The steel cable carries this molten paraffin into the cut and back to the surface. The paraffin is modified with additives that cause it to permeate into tight soils and form a barrier significantly thicker an the cut. Rapid cooling of the grout as the cut proceeds prevent excessive subsidence. An unlimited number of replacement jetting tubes or wire saw cables may be pulled into cutting position by the steel cables or the heated "pulling pipes" which are in the original directionally drilled holes. These may remelt a path through the previous cut.
Improvements on the inventor's previously disclosed method of forming a barrier by high pressure jetting from a long arcuate conduit are also described. The new method forms a very thin cut using chemical grout, such as molten paraffin or molten low density polyethylene, circulated through an catenary arcuate tube at high pressure and rate while the tube itself is reciprocated through directionally drilled holes to the advancing cut. Holes or hardened ports in the forward facing surface of the tube eject the heated liquid into the soil at high kinetic energy causing the soil to be eroded and substantially replaced by the molten paraffin. The tube is also able to perform abrasive cutting. An unlimited number of replacement jetting tubes or wire saw cables may be pulled into cutting position by the heated "pulling pipes" which are in the original directionally drilled holes.
Another improvement over prior art is the use of the above mentioned molten paraffin applied with conventional jet grouting apparatus. The preferred molten paraffin has a melting point between 120° and 180° F. and is modified by the addition of a surfactant which allows the molten paraffin to soak into soils which are already water wet or damp, as well as dry soils which have a very low permeability to water. The paraffin may also be replaced by or blended with a low density polyethylene homopolymer.
Previous inventions have addressed forming impermeable caps, vertical barriers and horizontal barriers but the present invention provides a totally integrated solution which results in total isolation of a waste site from the environment in a manner which is continually and passively verifiable. A subsurface "block" or volume of the earth defined by the ground level on its top and by a bottom comprised of a box-shaped or basin-shaped three dimensional mathematical "surface" which surrounds and underlies the block and rises upward to the ground level at the perimeter, forming a complete and continuous basin and top, fully enclosing the volume of earth in an air-tight, and water vapor-tight vault formed in situ around the block.
A liquid grout with viscosity comparable to motor oil, but which is of greater density than the subterranean "block" such that the block will float in the liquid grout, which will subsequently harden into an impermeable barrier material, and where the hardening of this grout is delayed for an extended period of 6 to 60 days while continuing to transmit hydrostatic pressure effectively. The length of set delay and the density and impermeability of this grout is significantly beyond the performance of the previous art.
Directionally drilled holes which traverse the lower surface of the block in roughly parallel paths and which rise to the ground level and level off to a near horizontal attitude at each end. Such holes being formed in a manner which leaves a tubular steel member or "pipe," and one or more non-crossed steel cables, or two pipes and at least two non-crossed cables in each of the holes extending from ground level at one end of the block to ground level at the opposite end of the block. A mechanical earth cutting means consisting of a flexible length of abrasive tensile member such as a steel cable or chain, The catenary section of which is cooled, cleaned and lubricated by a flow of grout from one or more ports in the adjacent pipes which are moved at intervals in synchronous with the net advance of the cutting means, and which itself is joined end to end and reciprocated or circulated in a continuous substantially horizontal loop between the two adjacent holes by a power driven apparatus that maintains tension on the cutting means against the face of the cut. Prior art has not utilized an abrasive cable saw in curving directionally drilled holes and has not anticipated coolant lines advancing through the holes with the cut.
The initial cutting means and periodic replacement cutting means are pulled into the holes by means of the cables initially attached to the pulling pipes. Pipes which have one or more perforations and are used to convey pressurized grout to the arc of the cable saw cut being formed. Movement of such discharge point being accomplished by moving the pipe through the ground or by moving a smaller inner pipe discharging between straddle packers positioned over one or more holes nearest the arc of the cut.
A perimeter excavated trench filled with the dense grout covers each opening into the directionally drilled holes such that the grout may flow by gravity into those into the annulus between the pulling pipe and the hole and into any narrow cut between them formed by the cutting means. Grout may also flow out to relieve pressure. Flow from the grout filled trenches through the annulus to the cut area may be stimulated by a differential elevation of grout in the trench or the grout may flow from the pressurized grout pipe, which traverses the hole and discharges grout at any desired location along the length of the hole. Excess grout will flow up the annulus to the trench or will contribute to increasing the thickness of the barrier.
The cut through the soil along the lower surface of the block, is filled with a layer of the grout such that the overburden weight is supported by the buoyant force of the grout, and such that the thickness of the cut can be increased by adding additional grout to the excavations. The elevation increase of the block may be controlled by changing the elevation of grout in the trench or by changing the grout density. Restraining means such as steel cables or chains, attached between anchorages on the block and anchorages outside the perimeter trench which act to keep the block floating in the center of the excavation from which the block has been lifted, and to limit the elevation increase of any given section of the block.
While the block is floating free on the layer of dense grout, an impermeable sheet, such as high density polyethylene extrusion (HDPE) heat-fusion-seamed together as is known in the art, is attached by chains or other flexible linkage to two or more of the pulling pipes such that the impermeable sheet may be pulled through the layer of liquid grout under the floating block by pulling the pipes from the opposite end until the sheet extends out of the grout filled perimeter trench on all sides. The sheet is preferably heat-fusion-seamed so as to be wide and long enough to underlie the entire block and the outside berm of the perimeter trench. The outermost portions of the sheet are permitted to pucker into undulating folds to compensate for differences in length of the paths under the block. Sites too large to move in one piece may be laid in the grout as unsealed strips with substantial overlap between strips. Separate strips of this material may be equipped with an slidable mechanical interlock, as is known in the art for vertical sheets such as the GSE Gundwall® Interlock, or Curtain Wall® made by GSE of Houston, Tex., such that one sheet may be slidably attached to adjacent sheets allowing one sheet to be pulled into place and sealed to its neighbor. A sealing compound may later be injected into this joint from the ends.
An air-tight above ground cap, is then constructed and sealed to the hardened surface of the perimeter trench of, and also preferably to the impermeable sheet. This completes an air-tight containment vault over, under and around the block. The top cap may have a layer of impermeable HDPE sheet which is heat-fusion-seam bonded to the bottom liner rising from the perimeter trench so as to form an air-tight seal between the two sheets. The cap is equipped with: air pressure, humidity, sound, and chemical sensors mounted both in the soil under the cap and on its exterior surface such that differential measurements may be performed and recorded on a continual basis in order to evaluate the degree of isolation between the environment inside the structure and the external environment. A standard data logger device records the data from the sensors may be periodically downloaded to a computer which graphically displays the relationship between internal conditions vs external conditions, as a function of time, temperature and rainfall conditions.
A catenary cutting means similar to the cable saw but operating by a reciprocating stroke implemented with standard construction equipment such as trackhoes may also be used to make the cuts between the directionally drilled holes. The apparatus consists of a flexible hollow tube of substantially uniform diameter extending from the surface down through the directionally drilled holes, joined in a catenary arc, through which high pressure fluid is circulated in a continuous loop, and from which at least a portion of this fluid exits the forward face of the tube through one or more holes or "jets", such that the fluid jet helps erode and wet the soil in the path of the device and allows the fluid to displace substantially all of the soil. The orientation of such fluid jets being cyclically altered to increase the thickness and uniformity of the cut by reciprocating rotation of both ends of the tube an equal increment on each pulling stroke, or by other means substantially in unison such that all soil in the path of the tube can be impacted by one or more fixed jets. The surface of the catenary tube is abrasive and mechanically cuts the soil in its path as well as eroding it with fluid jets. An additional abrasive cable may be pulled into the cut by means of the color-coded, non-crossing cables on the pulling pipe. This cable can bypass the tube and perform an abrasive cutting job and then be withdrawn from either end. The entire cutting tube could also be circulated out of the ground and temporarily replaced by an abrasive cable or chain. If the tube is damaged it can also be replaced in the same manner. This is a major improvement over jet cutting methods which have no recourse when they strike a hard object or if the jets plug. If the jetting tube has substantial enlargements along its length or at the slurry discharge points then it can not be circulated out of the hole if a problem should develop. This ability to recover from a structural failure, jet plugging, or a hard obstruction is critical to commercial use of the process.
The grout material may be either a slow setting dense material capable of buoyantly supporting the overburden or may be a fast set or thermoplastic set material which sets before a large unsupported span exists. A low water, cementitious, latex polymer modified grout with iron oxide additives and a long term set retarder is preferred for buoyant barriers. A molten grouting material made from paraffin wax or polyethylene homopolymer and surfactant admixtures which enable it to mix with damp or wet soils and permeate farther into water impermeable soils is preferred for the non-buoyant process. Circulation of molten grout through the pulling pipes and the catenary tube can keep the material from setting during a work delay or even overnight. Paraffin supply lines from relatively hot and relatively cool but molten paraffin may be blended by a valve to rapidly adjust the temperature of the material with changing ground conditions. Blends of paraffin and polyethylene may also be used. A cap liner made of a similar polyethylene or paraffin mixture may be used in the top cap and heat fusion bonded to the bottom barrier to create a completely air tight seal of similar material. This cap material may be sprayed onto the surface of the cap as a liquid material and cured in place or it may be a prefabricated sheet.
The above mentioned grouts have desirable properties for block encapsulation of buried low level radioactive waste. The molten wax and surfactant blends offer superior permeation into non-homogenous trash as well as good bonding and encapsulation of organic sludges. They offer a desirable matrix to stabilize the waste while it remains in the ground and also prevent airborne dust release during future retrieval. Since they are fully combustible they add no volume to the final waste matrix of a vitrification melter process.
BRIEF DESCRIPTION OF THE DRAWINGS
Other aspects and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:
FIG. 1 is a perspective view of a buried tank farm containing toxic waste illustrating directionally drilled holes being placed under the site and a quarry wire saw machine cutting between adjacent holes.
FIG. 2 is an illustration of the formation of an impermeable containment barrier under the tank farm shown in FIG. 1.
FIG. 3 is an illustration of a completed containment barrier under the tank farm shown in FIG. 1.
FIGS. 4A and 4B illustrate several of the steps performed in forming an impermeable containment barrier under a waste site.
FIGS. 5A and 5B illustrate the use of cables to keep a floating block containing the waste material centered in the excavation.
FIG. 6 is an elevation view of the completed containment vault illustrating the system for monitoring containment integrity.
FIGS. 7A and 7B illustrate the formation of barrier panels using an abrasive cable saw which cuts through the earth while molten grout is being supplied by pulling pipes to the cut region.
FIG. 8 is a illustration of an alternate method of forming a containment barrier under a buried tank.
FIGS. 9A-F illustrate the steps in constructing a containment vault around a waste site.
FIG. 10 is a perspective view of the waste site shown in FIGS. 9A-F being undercut and lifted.
FIG. 11 is a perspective view of a small test block being undercut by pull cables.
FIGS. 12A-C illustrate the step of placing an impermeable liner sheet in the grout barrier under the block of soil containing the waste material.
FIG. 13 is a perspective view of the containment site illustrating the step of pulling a large one-piece sheet of impermeable material under the block of soil containing the waste material which is free floating in the dense grout fluid.
FIG. 14 is a perspective view of the containment site illustrating the step of interlocking adjacent impermeable liner sheets.
FIGS. 15A and B are a plan and cross-sectional view, respectively, illustrating a catenary cutting step used in one embodiment of the invention to cut and form an impermeable containment barrier.
FIG. 16 is a perspective view of the a completed containment vault with a sealed cap structure.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, a shallow perimeter trench 7 is first excavated around the entire surface perimeter of the block to be isolated. A subsurface "block" or volume of the earth is defined by the ground level on its top and by a bottom comprised of a box-shaped or basin-shaped three dimensional mathematical "surface" which surrounds and underlies the block and rises upward to the ground level at the perimeter, forming a complete and continuous basin, fully enclosing the volume of earth.
A directional drilling machine 1 then drills rows of pilot holes under the site, which define the basin's elongated shape. A pulling pipe with two or more non-crossed cables strapped to it is connected to the drill pipe and pulled through the pilot holes. After this operation each pilot hole contains a pulling pipe and two or more color coded steel cables. Next, a diamond-wire saw machine 2 moves an abrasive cable 3, formed by joined adjacent cables, through the pilot holes cutting a pathway between adjacent pilot holes. The abrasive cable 3 cuts the soil and assists the flow of the grout which carries soil particles to the surface. Pulling pipes 3, 5, and 8 remain in the pilot holes after the paths are cut.
A grout plant 4 pumps grout through one or both of a pair of adjacent pulling pipes to the arc of the cut and also fills the trench 7 with a high density fluid grout. A grout panel 9 is formed as a pulling means, such as a dozer 10, advances the wire saw 2. The level of the grout in the trench 7 and its density applies a hydrostatic force to the bottom of the block.
FIG. 2 shows the pulling pipes 11 are in place defining a basin. Each pulling pipe 11 has one or more accompanying steel cables which are joined at the cutting end and threaded through a wire saw machine 13 at the other end. The wire saw machine 13 is pulled by a dozer 12. A grout plant 15 supplies pressurized grout to the surface perimeter trench 16 and to one or more of the pulling pipes 11 through the flexible hose 14. The grout exits the pulling pipes 11 through ports 18. The grout cools and lubricates the cable saw 19, and carries cuttings back to the surface perimeter trench 16. The cut 17 is filled with the dense liquid grout, which supports the weight of the overburden soil.
Referring to FIG. 3, as the grout plant 21, continues to fill the perimeter trench to an elevation 22, below the elevation of an outer berm 24, the thickness of the cut increases due to buoyancy as the block rises out of the ground. Existing fractures and fissures inside the block will fill with grout but will not extend even in planes of weakness because the hydrostatic forces on the block are balanced. Fissures in the earth outside the block will also be filled with the grout.
FIG. 4 shows a directional drilling machine 28 placing a drill pipe in the ground defining the lower surface of the vault. Long "pulling pipes" are prepared with several steel cables running parallel along the length of the pipe and secured to the pipe by a temporary fastener such as steel bands on the ends and masking tape in the midpoint. The cables have color coded ends and do not cross one another. These pulling pipes are attached to the drill pipe in the holes and pulled into position 31 by a dozer 29, which pulls on the original drill pipe. One of the cables from each adjacent pipe 32 is joined together and threaded through a wire saw machine 35. The cable may be used to draw a more specialized diamond-wire saw cable 33 into the cut. Circulation of this cable and tension applied by the wire saw machine carves a catenary cut through the earth as a supply of grout is pumped down the pulling pipe and exit ports 34 in the vicinity of the cut to cool, lubricate and carry away cuttings. This pipe may be pulled along through the ground as the location of the cut advances. The grout buoyantly increases the thickness of the cut such that a chain or other type of mechanical proving instrument may be pulled through one or more sections of the cut under the now floating block to verify that the barrier is continuous. Additional lengths of pipe are added to the end of the pipe as it is pulled under the block, so that a pipe always remains in position. A roll of a synthetic impermeable sheet, e.g., a high density polyethylene extrusion sheet 27 is then pulled through the liquid grout under the floating block. This may be interlocking sheets pulled in separately, as further explained below, or one large continuous sheet with numerous wrinkles.
FIG. 5B shows a block 38 floating on a layer of grout may not be of uniform density and due to its size may behave somewhat elastically. Steel cables or chains, 36 and 37, may be secured to anchor posts in the block and surrounding it to limit the total upward movement of the block as well as provide a centering effect 41, as the block reaches full elevation. Grout from the plant 42 may fill the trench 40 at one end of the block but due to viscosity and friction effects may not initially fill the trench at the other end 39, thus causing one end of the block to lift first. However, after a period of time the fluid levels will equalize and the block will level.
A cap structure is sealed to the hardened grout wall 43 with a resilient material 44 (such as an elastomer or wax) to create an air-tight vault, as shown in FIG. 6. Additionally, the impermeable polyethylene sheet 53, is fusion bonded to a similar polyethylene sheet 45, in the cap structure. This top sheet is covered with layers of sand, concrete 46, clay 47, and topsoil, as is known in the art. The clay and sand are doped with bitter tasting additives to discourage plants, animals and insects from burrowing into it. Air pressure, humidity, temperature, sound and chemical sensors 48, 49, 50, and 51 are buried in the clean perimeter soil inside the vault and also outside the vault. These sensors allow passive measurement of the vault's integrity over time. A port may also be provided to introduce tracer gas into the containment structure.
In an alternate embodiment, the device shown in FIGS. 1 and 2 is modified to include a circulating loop of molten paraffin grout, as shown in FIG. 7A. The molten paraffin grout 55 is circulated by a pump 56 to one of the pulling pipes 57 to a connecting pipe 63 or hose, back through the other pulling pipe and through a hose back to the tanker truck. Holes or jets 59 in the pulling pipe spray the grout into the cutting area to cool and lubricate the cut and to carry away cuttings back to the surface along the annulus outside the pulling pipes. The cutting cable 60 is pulled through the cut by the wire saw 61. The wire saw and the pulling pipes are all attached to a sled which is periodically pulled forward by a dozer. The paraffin grout displaces the soil and hardens a few meters behind the cut of the wire saw, before the length of the cut is wide enough to allow subsidence of the overburden. The paraffin grout is capable of soaking several inches into soils before it hardens and thus the final barrier may be several inches thick. Paraffin supply lines from relatively hot and relatively cool but molten paraffin may be blended by a simple valve to rapidly adjust the temperature of the material with changing ground conditions.
Once the panels are complete the perimeter trench may be excavated by conventional means and filled with molten grout. If the paraffin grout is made sufficiently dense, by addition of iron oxide powder, to provide buoyant force on the block then a perimeter trench may be maintained with molten grout to produce a thick barrier as in FIG. 3. The pulling pipes 66 and cable assembly have a length 65, which is enough to allow one complete pass under the block with the end still exposed.
In another alternate embodiment according to the present invention, a directional drilling machines 67 place a pipe down into the earth encircling the perimeter of a contaminated soil site below the tank, and then back to the surface, as shown in FIG. 8. Using a cutting means similar to the one shown in FIG. 7, a layer of high density fluid grout from a grout plant 70 is placed in a plane 72 below the tank 71. A perimeter trench is then excavated 68 around the tanks to partial depth and is filled with high density fluid grout. The remaining depth is excavated with a clamshell or trackhoe excavator 69 releasing the block of ground containing the tank which floats upward as the grout flows into the plane under the tank.
FIGS. 9A-F show a cross-sectional view of a long narrow burial site 73 being undercut and lifted by the method according to the present invention wherein a single pair of pilot holes 74 is employed. First, a wire saw 75 cuts between directionally drilled holes with a dense fluid to form a horizontal cut under a burial trench, as shown in FIG. 9A. Second, a vertical perimeter trench 76 is excavated, as shown in FIG. 9B. Next, the perimeter trench 76 is filled with dense grout 77, as shown in FIG. 9C. The soil block 78 then becomes buoyant and displaces upward to its final position 79, with higher external soil berms in place, as shown in FIGS. 9D and 9E. Lastly, the airtight cap structure 81 is bonded to the below ground barrier, as shown in FIG. 9F.
In FIG. 10, a long waste site, similar to the one shown in FIG. 9, is being undercut and lifted. An excavator 83 digs a perimeter trench to fill depth. A pair of holes are drilled and cased, intersecting one end of the trench and a wire saw cable is looped around the entire block. This could also be done with another trench, but would require more grout. The trench is then filled with a dense liquid grout. A wire saw machine 82 makes a cut 84, which is filled by the grout from the trench, which buoyantly supports the weight of the block. As the cut progresses, the block buoyantly lifts upward to its full floating position.
In FIG. 11, a small test block is being undercut by the direct pull cable method. The dozer 89 pulls the cable 88 through the soil while the trench 87 is filled with the dense fluid grout supplied by the grout plant 90.
FIGS. 12A-C show the steps of sealing the block with a synthetic impermeable layer. This is accomplished as follows. While the block of soil is floating free on a thick layer of dense grout, a dozer 93 pulls on pulling pipes 92, which in turn pull an impermeable liner sheet 91 completely under the block, as shown in FIG. 12A. The impermeable liner sheet 94 is pulled under the block until it extends over berms on the perimeter, as shown in FIG. 12B. An impermeable top sheet 95 is fusion bonded 96 to the bottom sheet all around the perimeter of the block producing an airtight containment vault, as shown in FIG. 12C.
In one embodiment, one large sheet 99 is pulled under the free floating block by one or more dozers 98, as shown in FIG. 13. In this embodiment, the pulling pipes 100 are elastically attached 103 to the sheet at intervals. The edges of the sheet are allowed to pucker 102 to compensate for the differences in lengths.
In another embodiment, multiple interlocking sheets of the impermeable liner material 105 are pulled under the free floating block by pulling pipes 108, as shown in FIG. 14. The interlock 106 joins the sheets while allowing relative movement as the sheets are pulled through the liquid grout 104.
FIGS. 15A-B show another alternate embodiment of the basic method. This embodiment illustrates a catenary cutting method using a uniform tubular abrasive member 110 and a circulating pressurized fluid 55 directed at the cut as the tubular member is reciprocated around the arc of the cut by the motion of two hydraulic excavator trackhoes. The ends of the tubular member are rotated to allow a single fixed jet to sweep through at least 45° of arc so that it may strike substantially all of the soil in the path of the tubular member, as shown in FIG. 15B. In this embodiment, the tubular member is a flexible high pressure tube of substantially uniform diameter extending from the surface down through the pilot holes and joined in a catenary arc. The high pressure fluid is circulated in a continuous loop and at least a portion of the fluid exits the forward face of the tube through one or more holes or jets such that the fluid jet helps erode and wet the soil in the path of the device and allows the fluid to displace substantially all of the soil. The orientation of such fluid jets being cyclically altered to increase the thickness and uniformity of the cut by reciprocating rotation of both ends of the tube an equal increment on each pulling stroke, or by other means substantially in unison such that all soil in the path of the tube can be impacted by one or more fixed jets.
A completed containment structure with the final cap in place is shown in FIG. 16.
Further details of the present invention are described below.
A directional drilling machine 1, such as those used by Eastman Cherrington Co, Houston, Tex., or direct push type machines such as those made by Charles Machine Works, which is known in the art, is used to drill a series of roughly parallel (in plan view) pilot holes 8, under the site. The pilot holes may typically be spaced from 20 to 100 feet apart and do not have to be parallel or equidistant. They need only define the geometry of the barrier to be constructed. The holes typically enter the ground within the trench at an angle, descend to the desired depth, level off and run substantially horizontal, and then rise back to the trench at the opposite end of the block. Steering and verification of the position of such holes is well known in the art. Several such pilot holes would be drilled at intervals across the width of the site at various depths to trace an elongated basin-shaped surface which is substantially below the contaminated rock/soil layer but rises nearly to the surface on the sides and each end, where it intersects the perimeter trench. This perimeter trench may be excavated with a backhoe in conventional manner.
During drilling of these pilot holes any drilling fluid which returns to the surface may be used to verify that the holes are located in uncontaminated soil. If contamination is found, the hole may be plugged and a deeper pilot hole installed. Portions of the hole in unconsolidated soils may optionally be cased with a thin plastic sleeve 5.
After drilling is complete, a pair of saw cables 6, (or jetting tubes, 110) and a "pulling pipe" 7, may be introduced into each pilot hole as the drill pipe 8, is extracted. These two cables (or tubes) are affixed to both ends of the steel pipe. This arrangement helps prevent the cables from crossing each other and provides a means of running replacement cables or injecting grout. The pipes extend up through the trench and over a soil berm to a horizontal position on each end. The steel pipes are preferably 23/8 inch oil well tubing with threaded connections as is known in the art. The steel pipe may have one or more small holes drilled in it at intervals. The pipe may optionally be used to convey dense fluid or super dense grout to points along the pilot hole. A smaller pipe with a straddle packer may be moved within the pulling pipe to direct liquid flow to any desired point along the pipe. Preferably the fluid may also be directed to any point by moving the pipe through the ground such that the holes are at the desired position. The pipe may also be used to draw additional wire saw cable into place if a cable breaks in service. The pipes may also be used to pull larger or more powerful wire saw cables or cutting devices or proving bars through the cut after the initial cut is made.
A diamond-wire saw quarry saw such as the Pellegrini TDD 100 G, Verona, Italy, made for the extraction of granite blocks, is set up at one end of the directionally drilled pilot holes. These machines have been in use for many years. The diamond-wire saw is essentially a steel cable with abrasive materials bonded to it at intervals. The wire saw machine is a large power driven cable sheave which maintains tension on the cable and pulls a continuous loop of cable through the cut like a band saw. The diamond-wire saw steel cable from the first hole is joined in a loop back through the second hole to the wire saw machine and joined into a continuous cable. The method of joining steel cables may include a reweaving process which is known in the trade. The cable machine causes the cable to move in a continuous loop through the holes and places tension on the cable to cut a pathway between the first two pilot holes. Diamond abrasive sections of the cable do the cutting in rock, and also cut soil. In applications where rock is not anticipated, the cable abrasives may be optimized for fast soil cutting. A standard aircraft grade steel cable may also be used without abrasives to cut through soft soils. In this specification, the words cable saw, cable, diamond-wire saw, diamond-wire saw quarry saw, and wire saw are used interchangeable to refer to a mechanical cutting means. The cutting fluid may optionally contain a clay dispersing additive such as sodium lignosulphonate or salt, to keep the clay from sticking to the cable. A high pressure fluid jet or mechanical brushes may be set up to continuously clean the cable as it comes out of the ground.
The shallow perimeter trench at each end of the pilot holes is filled with a special cutting fluid or grout which has a density greater than the average density of the waste site soil and a low viscosity. Cutting fluid is circulated through the cut to remove cuttings, cool and lubricate the cable. The cutting fluid is preferably sufficiently dense to support the overburden and prevent the cut from subsiding and also to provide significant net lifting force as well. This fluid may be made from a gelled water combined with a powdered iron oxide to increase its density, or it may be a dense iron oxide modified cement grout with set retarder. The fluid may be introduced into the pilot holes by pumping it down the pulling pipes in the pilot holes to the area of the cut. At this point the fluid exits the pulling pipe through small holes and flows back to the surface, applying a hydrostatic head to the area of the cut. As the wire saw cable moves, it circulates this fluid from the entry side of the cut to the exit side and back to the surface trench. The wire saw cable also carries this fluid into the cut where it picks up cuttings and then returns to the surface trench with the returning cable. The used fluid may be picked up from the exit area of the trench and re-conditioned before placing it back into the trench. The fluid's density and the hydrostatic head from the surface trenches provide a balancing force which prevents the overburden soils from collapsing into the cut which the wire saw makes. The fluid is designed to flow into permeable soils and rock to a very limited degree, while forming a filter cake which the hydrostatic force may act against and support the overburden. The principal is similar to that of a deep horizontal oil well drilled through unconsolidated sands.
If the soil and rock is very abrasive, the cable may be changed several times during a single cut. Broken cables may be replaced by pulling a new set of cables through that pair of holes with the steel pulling pipe which is left in the hole. After the first wire saw cut is complete, the next cut may begin. Each cut has its own cables so if multiple wire saw machines are available many cuts could be completed at the same time. The cable will tend to cut through most rocks and debris in soil. Hard rocks in softer soils may get pushed up or pushed down by the cable. In either case the dense fluid will fill whatever gap is created. For large scale applications a larger diameter cable could be used to make longer and wider cuts.
After the initial cuts have been formed in a given area additional grout may be added to the trench and injected through the pipes. The level of the grout fluid in the trench is gradually increased, which causes more grout fluid to flow into the cut and buoyantly lift the overburden soil as the thickness of the cut slowly and uniformly increases. The concept is like floating a ship out of dry dock. Addition of grout continues until the soil block has risen about 3 feet. See FIG. 2A. At this point the barrier thickness is also about 3 feet. The steel pipes which lie in the tracks of the pilot holes can now be utilized to pull a chain type proving bar or a High Density Polyethylene Extrusion (HDPE) liner under the floating block. See FIG. 5. A large sheet of HDPE could be fabricated by field fusion bonding techniques and pulled under the entire site in one motion. A reinforcing mesh of composite fiber could also be installed in this manner to increase the strength of cement based grout. Post tension cables or nondestructive testing devices could also be installed in the same manner.
Earthen berms may be built up around the outer perimeter of the trench to allow higher grout levels to increase the lift of the block or to allow lift of a site with surface structures, or heavy objects. Anchored cables may be used to provide a force to keep the block floating in the geometric center of the liquid perimeter. See FIG. 6.
Grout Properties And Composition
The proprietary grout will remain fluid for several weeks and then harden into a rock with physical and chemical properties similar to ceramic tile. Properties of this fluid are tailored for the site and are sufficiently "filter cake-forming", that the fluid does not leak into the soil or rock excessively. Permeability of the preferred grout has been demonstrated to be approximately 10 -8 cm/sec. Compressive strength after 6 months is greater than 5000 psi. This grout has near zero shrinkage on set and is highly impermeable. It is suitable for both wet and desert dry conditions. As a liquid the grout has a marsh funnel viscosity less than 120 seconds and typically less than 70 seconds. The grout is inorganic and resistant to nitrate salt migration. A nonhardening version of the grout is also available for use as a cutting fluid in the wire saw operations. When mixed with the hardening version of the grout this dense cutting fluid will also harden.
The special super dense grout is preferably composed of a type K other zero expansion cement to minimize the potential for stress cracking, mixed with water to an initial density of 12 to 20 pounds per gallon. A high density additive, such as barite, brass or copper powder, uranium ore, or steel shot, but preferably iron oxide powder (hematite) such as is known in the art of oil well cementing and drilling fluids, is added to increase the final density to 20 to 30 pounds per gallon. A viscosity reducing admixture such as condensed polynaphthalene sulfonate, but preferably a salt-tolerant high range water reducer such as Halliburton CFR-3, available from Halliburton Services, in Houston, Tex. is added at a concentration of 0.5 to 2 percent. A set retarding admixture, based on lignosufonates, borates or gluconic acids, which are known in the art, but preferably an organic phosphonic acid such as Amino Tri Methylene Phosphonic Acid, which is made by Monsanto Chemical as a anti-scale additive. Other preferred additives include Fumed Silica, epoxy resins, and butadiene styrene latex emulsion. The above grout formulation, properly proportioned, will form a nonsettling slurry which will remain liquid for several weeks and have a viscosity comparable to butter milk. After several weeks the slurry will harden. After curing for several months it will develop a high compressive strength.
An example of such a slurry is as follows: 90 to 110 parts water (by weight), 150 parts type K cement, 300 to 400 parts powdered hematite (iron oxide), 20 to 40 parts fumed silica, 25 to 35 parts Latex emulsion, 30 to 60 parts CFR-3, and 0.2 to 0.8 parts organic phosphonic acid. This grout has a very low water content and produces a final product which can withstand very dry environments.
An alternative slurry may be used if the site characteristics require a flexible barrier material. This slurry would be similar to the above slurry but the cement content would be reduced to 50 parts cement and the water replaced with a 6 to 8 percent prehydrated bentonite slurry modified with 1 percent sodium lignosufonate in place of the other set retarder. This formula will form a dense clay-like grout which will have plasticity similar to native clay.
Another alternative grout may be made by adding powdered hematite or a cement grout slurry containing hematite to an epoxy resin grout. The preferred epoxy would be CARBRAY 100, distributed by Carter Technologies, Sugar land, Tex. This epoxy has a very low viscosity and can be diluted with water or bentonite slurry. The material, cures to a rubbery product which is stable in a variety of moist environments. This epoxy may also be mixed with dry bentonite and powdered hematite to form a lower cost, but still flexible, product.
Another useful grout material is molten paraffin or molten low density polyethylene. These materials will melt at temperatures below the boiling point of water and thus can be applied in field operations with relative ease of cleanup. They can both be modified with surfactants to make them wet the soil better, even when the soil is already wet.
Air-tight Barometric Cap, For All Methods
After the below ground portions of the barrier vault are completed by either method, an above ground cap would be constructed and later covered with soil. This cap is of conventional concrete, clay, and HDPE construction but is designed to be air-tight and would be equipped with passive air pressure sensors on its inner and outer surface. These sensors allow air pressure differentials between the vault and the surroundings to be monitored and recorded. Dry soils are relatively permeable to air pressure. A breach in the vault will allow external air pressure to slowly equalize in the vault. This cap is equipped with pressure sensors which monitor external atmospheric pressure, external soil gas pressure, and internal soil gas pressure under the cap. By comparing these three pressures over time the integrity of the barrier may be verified. Manually operated vent pipes would allow periodic venting of any pressure which accumulates in the structure due to gas generation by the contents. Trace gasses may be introduced to aid in crack detection, location and repair. See FIG. 7. Introducing a small amount of Freon or other suitable tracer gasses into the containment structure should allow any subsurface cracks to be detected by soil gas probes placed around the perimeter. Injecting an odor producing chemical would allow regular monitoring by trained dogs. Dogs can be trained to dig at the source of the leak.
Moisture levels and sound levels inside versus outside the barrier may also be used to monitor leakage. The moisture levels inside the barrier should not change when the exterior levels change. The interior moisture levels may be reduced by circulating dry air through the interior of the structure. Passive sound sensors inside the containment structure can detect stress cracking of the rock-like barrier material as it occurs. Four buried acoustic transducers outside the structure alternately sweeping frequencies from 20 to 60,000 cycles per second would allow several acoustic sensors inside and outside the structure to pick up information that could indicate both the location and magnitude of a crack. The attenuation of different frequencies can indicate the size of a crack.
The preferred method of construction varies greatly according to the size and environmental conditions. An example of such construction for a 300 foot by 300 foot cap in Idaho is as follows. The hardened surface of the perimeter trench is smoothed and a resilient rubbery material such as Carbray 100 epoxy, or silicone caulk is layered on to its surface. A layer of permeable sand is placed within the boundary of the perimeter trench to a depth of 1 foot on the edges sloping to 3 foot deep in the center. A geo-textile high density polyethylene top liner sheet fabricated by fusion bonding methods is placed over the site extending over the seal material and fusion bonded to the bottom liner extending out of the perimeter trench. A geo-textile is installed on top of the top HDPE liner with post tensioning and reinforcing installed above. A layer of sand with bitter tasting additives like pepper, alum, and borax is spread over the liner and a Low permeability concrete is cast on top of it to further discourage insects, plants, and rodents. A clay and soil cap is constructed above using these same additives to bury the concrete cap well below the frost line.
In the event of a breach, ports into the finished vault can be used to inject a small amount of tracer gas such as common R-12 Freon or R-134 or similar fluorocarbons, which will diffuse through the entire vault. Leakage of even trace amounts of this gas through the wall can be sensed by an inexpensive portable detector at the perimeter surface and on the top cap, thus indicating the general area of the leak. An odor producing chemical could also be introduced into the vault. Trained dogs can then be used to routinely inspect the cap and perimeter areas. It is well established that dogs can detect concentrations of oderants more reliably, and in smaller concentrations than currently available instruments. Moisture levels could also be used to verify isolation. Hollow pipes, placed into the wall and floor of the vault while in the liquid state may be used to perform radio frequency, electro-resistivity, or acoustic logging in the walls of the vault to locate cracks even if they do not cause a leak. Several acoustic transducers outside the vault sweeping from 20 to 60,000 cycles per second picked up by sensors buried in the interior of the structure could be used to locate cracks. Stress cracks will make sounds as they occur and can be passively detected. The preferred grout material would have a low electrical conductivity to allow resistive logging between the inside and the outside of the containment structure.
Significant damage to the cap of the vault could be repaired by conventional means including epoxy crack injection. Damage to side walls could be repaired by excavating a narrow trench along the wall and casting new concrete in place. Traditional chemical grouting methods could also be used. Damage to the floor of the vault could be repaired by flooding the vault with a water-thin chemical grout such as sodium silicate, polyacrylamide, or epoxy. It should also be possible to construct an entirely new containment barrier under an existing one.
VARIATIONS OF THE METHOD
Bottom First Burial Trench Method
There are a number of burial trenches in Idaho which are approximately 20 feet wide by 15 feet deep by 500 to 1700 feet long. These trenches are typically parallel and about 30 feet apart. They contain randomly dumped undocumented low level waste. The trenches were cut with a dozer down to a basalt rock layer. This basalt rock layer is about 500 feet thick but is located over the Snake River aquifer. The rock is fractured and is not considered to be a long term confining layer.
Directionally drilled holes would be placed along the bottom outboard edges of a trench at the desired depth. This could be well into the basalt rock layer. These pilot holes would curve back to the surface on each end of the burial trench. Diamond wire quarry saw cables, attached to both ends of a pipe, preferably 23/8 inch oil well steel tubing, would be pulled into each hole as the drill pipe is removed.
The cables from one hole to another would be joined at the surface into a continuous length and threaded through the wire saw machine. Two separate, bermed, elevated pits "A" and "B" would be constructed around each of the pilot hole openings on the wire saw machine end of the burial trench. A single trench "C" would be constructed connecting both of the pilot holes on the opposite end of the burial trench. A dense drilling fluid pumped into the "A" pit will flow through the number 1 pilot hole to the "C" trench and back through the number 2 pilot hole to pit "B". The fluid arriving in pit "B" would be reprocessed and placed back in pit "A". Grout could also be pumped through the pipes as described above.
After this continuous flow is established the wire saw machine would feed cable into the number one pilot hole while pulling the cable from the number 2 pilot hole. The cut would begin at the "C" trench and proceed toward the wire saw machine, as the machine moves backward along its tracks. Periodically a new wire saw cable would be spliced into the system. The steel pipes can be used to pull additional cables into position if a cable breaks in service, or to provide a flow of cutting fluid to a specific area. As the cut progresses the entire burial trench will be undercut and supported on a half inch thick layer of the dense cutting fluid.
The properties and stability of this fluid are, of course critical to the process. The fluid must have a density greater than the soil and rock above it and be fluid enough that it flows and transmits hydrostatic pressure effectively through a half inch thick cut. It's fluid loss characteristics must also be tailored to plug small fissures in the permeable rock without plugging the half inch thick cut. Large vertical cracks and fissures are a common feature in the basaltic rock of Idaho. If the wiresaw encounters cracks which cannot be filled, one or more of the pulling pipes will be used to inject a sodium silicate solution into the cut. This material will cause the grout to become viscous very rapidly and plug large openings.
After completion of the bottom cut, sidewall trenches would be excavated by conventional means such as backhoes under a slurry of low viscosity dense grout. These trenches would begin at one end and proceed down both sides at once to construct a trench around the entire perimeter. When the sidewall trench intersects the bottom cut the dense grout will flow into the bottom cut and provide a net positive lifting force on the order of 1 to 5 pounds per square foot. (Not enough to shear the soil and rock but enough to lift it once it is no longer restrained.) As the sidewall cuts proceed down the length of the burial trench the elasticity of the soil and rock will allow the block to lift out of the ground on the free end. Once the entire length of the block is free floating, additional grout could be added to increase the thickness of the grout layer. In very long trenches the soil block may rise to full design elevation before the excavators reach the far end of the site. See FIG. 10.
Side First Burial Trench Method
An alternate method of construction may be used in soil or rock which may be cut more rapidly. This method is expected to be useful in hard soil in which a trench will stand open without support and has little chance of large fractures or voids. In this method the vertical perimeter trench is first excavated to full depth. The wire sawing equipment is then positioned in the trench to cut loose the base of the block on a horizontal plane. This may be accomplished by placing cable pulleys in the trench or by entering the base of one end of the trench with directional drilled holes, through which the cable saw is threaded. The trench will be filled with a super dense grout which is denser than the soil block and which is designed to remain fluid during the duration of the work. As the cut begins, the super dense grout fills the trench and enters the gap cut by the wire saw to provide solids removal, cooling and buoyancy for the block. The cable saw for this work may require diamond abrasives in rock but in soil may use steel cable or steel chain cutting elements. In this method the grout will fill the void behind the cable as it cuts.
As the wire saw undercuts the block, buoyancy of the super dense grout will cause the end of the block which has been undercut to rise slightly as the grout flows into the horizontal cut. Additional grout will be added to the trench to maintain a level sufficient to cause a small but measurable rise in the free end of the block. After the under-cutting process is complete additional grout will be added to the trench to cause the entire block to rise to the desired elevation. (18 to 36 inches typical) Berms may be constructed around the outer perimeter of the trench to allow greater lift height.
In this method the set properties of the super dense grout must be delayed until the cut is complete. This method may not require directional drilling at sites where deep conventional excavation of the perimeter trench is possible. This method forms a rectangular block instead of a gently curved basin structure. Additional sloping excavations on each end could be added to facilitate introduction of a plastic liner material.
Direct Pull Cable Method
A special variation of this method is possible in very soft soil or in a small test site. A trench is excavated dry in a U shape with the ends of the U tapering back to the surface and a cross ditch in the full depth portion such that the waste area is surrounded. A steel cable is laid in the bottom of the trench with ends extending from the bottom of the U and connecting to a pulling means such as a large dozer. The tapering portion of the trench is backfilled to hold the cables in place. The remaining trench is filled with a grout that is more dense than the soil but still fluid. The dozer pulls the cable through the soft soil like a cheese slicer, making a cut which is instantly filled with grout. This action forms a continuous layer of grout under the soil block which thickens as the grout displaces the block upward. Anchor cables keep the soil block centered in the excavation. When the grout hardens it will form a seamless basement structure.
Vertical Cylindrical Block Method
Another alternate method involves forming a directionally drilled hole which enters the ground outside the waste area perimeter, descends to depth and levels off, proceeds around the perimeter of the area to be isolated, (completely encircling it), and then returns to the surface near the point of entry. The wire saw cable is drawn through this circular path as the drill is withdrawn. As the wire saw tightens it cuts under the area to be isolated. A large circular cut is formed under the site. See FIG. 8. The cut is filled with dense fluid as it is cut, as is done in the preferred method. This dense fluid fills the cut and the directionally drilled holes back to the surface to provide hydrostatic support for the block of soil. This dense fluid may be a nonhardening material which could remain in place for many months before the next phase of the project. The fluid would be designed to be slightly heavier or lighter than the grout and would have the ability to seal off small leak pathways or permeable formations.
After the bottom horizontal cut is formed, a perimeter trench is conventionally excavated within the boundaries of the horizontal circular cut and through it. This trench may be rectangular or curved according to the capability of the excavating equipment. This trench may be cut "dry" or excavated under a super dense grout slurry. If excavated dry, the dense fluid will flow out of the horizontal cut and allow the cut to close near the trench. This also provides visual evidence that the horizontal cut has been intersected. If the trench is excavated under a super dense grout slurry the slurry will balance the hydrostatic pressure of the dense fluid in the horizontal cut, or overcome it and flow into the horizontal cut. Optionally both methods be used at the same time on opposite sides of the block. As the slurry filled perimeter trench cuts through the horizontal cut its super dense grout will enter the horizontal cut and cause the block to lift. It may also be desirable to cut to a percentage of full depth with a dry trench, and then complete the intersection with the trench filled with super dense grout.
Forming Barriers With Molten Paraffin
Wiresaw cuts may also be made using a molten paraffin which is pumped into the cut through the pulling pipes in the same manner as with dense grout. Pulling pipes may include circulation loops to keep paraffin from hardening around the pipes. In this method the paraffin hardens only a few feet behind the cutting cable. The liquid area is a thin arc between the pilot holes, typically from 1 to 3 inches thick. This limits the overburden stress on the soil so that the barrier does not get pinched out. These grouts can also be modified with powdered iron oxide to make them more dense than the soil to facilitate a buoyant lift barrier. However it is also possible to use a thermoplastic material like paraffin to construct a thin barrier which relies on rapid hardening to prevent subsidence. Subsidence forces are managed by keeping the one horizontal dimension of the cut sufficiently narrow that the structural strength of the soil overburden is enough to prevent collapse. A two component chemical grout may also be applied in a similar manner with the pulling pipe containing a concentric inner pipe supplying the second component and a nozzle constructed so as to receive flow of both components and mix them together. This could also be done with two separate pipes tethered together or inside a larger pipe. The grout need only be injected on the side of the cut from which the cable moves inward. The movement of the cable through the ground creates a pumping action which causes the greater portion of the grout to follow the movement of the cable around the catenary arc of the cut and back to the surface trench.
Molten paraffin, circulated through a catenary arcuate tube at high pressure and rate while the tube itself is reciprocated through directionally drilled holes to the advancing cut. Typical pressures would be from 2,000 psi to 10,000 psi controlled by a spring loaded pinch valve on the recirculation line which automatically limits the pressure in the line. Circulation rates are sufficient to prevent particles from settling out and to keep temperature uniform. Holes or hardened ports in the forward facing surface of the tube eject the heated liquid into the soil at high kinetic energy causing the soil to be eroded and substantially replaced by the molten paraffin. This allows the tube to advance forward laterally. These ports, or "jets" may be fabricated by brazing a tungsten carbide nozzle flush with the surface of the tube. Portions of the surface of the tube may be covered with an abrasive grit such as tungsten carbide imbedded in an epoxy coating, or by weld deposited hard facing. Rotating both ends of the tube slightly after each pulling stroke allows for a single jet to cut a path wider than the tube. An example of such a rotation sequence would be 0°, +5°, 0°, -5°, 0°, +5°. By rotating the tube in small increments it is possible to sweep the entire soil area in front of the tube with a fixed position jet. In previous tests of soil jetting devices the inventor has noted that the width of the cut formed by a single jet varies significantly with soil type and jetting factors. If the jets do not make a cut at least as thick as the diameter of the tube then the device can not advance except by mechanical abrasion. The ends of the pipe may be automatically rotated by a mechanical "J-Slot" mechanism such as is common in the art of oil well down-hole tools. The mechanism rotates one increment each time the tube is placed in tension and released.
As the tube passes laterally through the ground, the paraffin both permeates into the soil and cools to a solid state. Paraffin which fractures away from the barrier will undergo rapid cooling and will harden and seal off. The injection temperature, and the cooling rate are such that the paraffin hardens before a large enough liquid area of the cut exists to allow subsidence of the overburden to pinch out the barrier. Since fresh molten paraffin is always circulating through the tube, the immediate area of the cut will always remain molten even if reciprocation stops. If the pipe breaks or becomes stuck a new tube may be pulled into position by melting a path through the previous cut. An unlimited number of replacement jetting tubes or wire saw cables may be pulled into cutting position by the heated "pulling pipes" which are in the original directionally drilled holes. An abrasive wire saw cable or chain, may also precede the jetting tube by a few feet to cut through hard objects and reduce the stress on the tube.
Another improvement over prior art is the use of the above mentioned molten paraffin applied with conventional jet grouting apparatus. The preferred molten paraffin has a melting point between 120° and 180° F. and is modified by the addition of a surfactant which allows the molten paraffin to soak into soils which are already water wet or damp, as well as dry soils which have a very low permeability to water. An example of such a surfactant includes Fluoroaliphatic polymeric esters such as Flourad™ FC-430 made by the 3M company of St. Paul, Minn. Another useful surfactant blend can be formed from a blend of 9 parts by weight oleic acid, 6 parts alkanolamine, and 6 parts nonionic surfactant such as nonyl phenol ethoxylate. The surfactant, along with an optional oil soluble dye may be added to a tanker truck of molten paraffin which directly feeds the jet grouting equipment. Optionally a bad tasting or bad smelling substance may be added to increase the resistance to rodent and insect damage. When mixed with the soil by the jet grouting process, it produces a water impermeable product. Hot water is pumped through the system prior to the paraffin to heat the piping and also afterward to clean the system. Molten low density polyethylene Homopolymer such as Marcus 4040 which melts at 181.4° F. may be utilized in a similar manner to the paraffin to increase chemical resistance properties. It may also be modified to enhance its performance in wet soils by the additions of surfactant blends. An example of a nonionic blend is 7 parts by weight ethoxylated alcohol, 0.56 parts potassium hydroxide, and 0.21 parts sodium bisulphite. An ionic blend could be made with equal parts by weight of oleic acid and an amine. If polyethylene is used as the primary grout, the HDPE top liner may be fusion bonded directly to the bottom barrier. This material may also be used as a hot melt glue to bond the paraffin to an HDPE top liner. The low density polyethylene homopolymers may be blended with the paraffin wax at a concentration of from 2 to 10 percent weight percent to improve its wetting properties, impermeability, and chemical resistance.
Molten paraffin may be especially useful for constructing barrier vaults in rock which has large cracks or fissures such as the basalt rock layers which exist in Idaho. As the molten wax enters a fissure and begins to escape from the area where the barrier is to be formed it loses heat and solidifies quickly. This tends to seal off the fissure. This approach should work in both water saturated and vadose zones.
Those skilled in the art who now have the benefit of the present disclosure will appreciate that the present invention may take many forms and embodiments. Some embodiments have been described so as to give an understanding of the invention. It is intended that these embodiments should be illustrative, and not limiting of the present invention. Rather, it is intended that the invention cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims. | 4y
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to providing low frequency communications using ionospheric modification. In particular, the present invention provides a method and apparatus for causing interruptions in the ionospheric electrojet to produce ULF/ELF/VLF signals.
2. Related Art
Low frequency communication systems can use the long propagation paths of low frequency waves (on the order of 1 Hz to 1 kHz) inside the earth-ionospheric wave guide to convey information. For example, ELF wavelengths are comparable to the radius of the earth, and horizontal propagation of ELF waves is equivalent to the propagation of a series of earth-ionosphere eigenmodes which have very low spatial attenuation. ELF waves also feature very low absorption in sea water. A 100Hz wave can typically penetrate 100 meters below the ocean surface. As a result, ELF waves have a practical utility in allowing communication with submerged submarines. ELF waves can also penetrate the earth's surface and be used in geophysical exploration.
The conventional approach to ELF wave excitation, as pursued in the late 1960's and early 1970's, employed large ground based antennas, typically on the order of 10 4 km 2 . The ground based antenna approach suffers several drawbacks, including the large physical area required for the antenna array, the expense of constructing and maintaining a large facility, and relatively low efficiency. For example, one Navy ELF transmitter uses over 2 MW of ground power to produce only 2W of radiated power, resulting in an efficiency of only 10 -6 . Other alternatives which have been proposed include ELF generation by satellite borne antennas and the use of high frequency ground transmitters using the ionosphere as an active medium.
Generating ELF waves by utilizing the ionosphere as an active medium is of particular interest. This technique provides frequency agility and avoids many of the economic drawbacks associated with large and inefficient ground based facilities. Generation of ELF waves by modulating ionospheric currents has been confirmed for both the equatorial and the auroral electrojet in experiments conducted in the USSR (Migulin and Gurevich 1985, Belyaev et al. 1987), the MAX-Planck Tromso facility in Norway (Stubbe et al. 1982, Barr and Stubbe 1984, James et al. 1988), and in the United States (Ferraro et al. 1982, Ferraro 1988, Ferraro et al. 1988).
Electrojet current modulation can be accomplished by using a high power ground transmitter which heats ionospheric electrons locally, to enhance the electron-neutron collision rate. This yields a modified ionospheric region with plasma conductivities (Hall, Pedersen and Parallel) substantially different than the surrounding region which impedes the electroject and induces a local current perturbation. If the heating process is carried out in an intermittent manner with a pulse period in the ELF range, the current perturbation around the heated region will radiate at the ELF frequency in a manner similar to an oscillating dipole. Thus, a "virtual" antenna is created inside the ionosphere. This virtual antenna radiates at the expense of the free energy of the natural electrojet current system.
Most of the experiments performed in this area have used HF frequencies in the range of 2-5 MHz, while the power density at the interaction region varied from between 10 -4 -10 -3 W/m 2 . The most exhaustive studies were performed at the Max-Planck Tromso facility The results here were generally consistent with results produced at other facilities, although the precise values of the detected field amplitudes depend on local conditions, characteristics of the HF facility and other specific factors While proving the underlying fundamental principles were sound, experiments to date indicated that the efficiency of such a system would be limited to about 10 -8 , or less than that of established ground based systems, such as the Navy system mentioned above. As further discussed below, these previous attempts to utilize electrojet antennas failed to match ionospheric plasma response to antenna operation, resulting in such low efficiencies.
SUMMARY OF THE INVENTION
In view of the above limitations of the related art, it is an object of the invention to achieve a higher efficiency system for transmitting low frequency waves using the electrojet.
It is still another object of the invention to match performance of the HF antenna to the ionospheric plasma response and radiated ELF frequency.
It is a still further object of the invention to direct an antenna beam at a region of earth atmosphere thereby causing heating of ionospheric electrons in a corresponding region of earth atmosphere and sweep the antenna beam to another region of earth atmosphere to cause heating of ionospheric electrons in the other region.
It is a further object of the invention to heat ionospheric electrons at a fixed altitude determined by the frequency of the antenna beam.
It is still another object of the invention to direct the heating to an altitude of about 90 km.
It is still another object of the invention to monitor an electric field generated by the antenna beam.
It is a further object of the invention to shape the ionospheric heating region to optimize a vertical component of the monitored electric field.
The above objects of the invention and others are carried out by a method and apparatus for producing ELF waves by ionospheric modulation having a much greater efficiency than previous ionospheric and conventional methods. The present invention is based on the recognition that the efficiency of HF to ELF power conversion can be increased by more than two orders of magnitude if the heater is swept over a 35 degree cone on timescales faster than the plasma cooling rate at the heating altitude. Further efficiencies can be realized by providing localized heating at an altitude between 90-100 km where the dominant modulated current is the Pedersen current. Finally, further improvement is achieved by monitoring the electric field and adjusting the heating region to optimize the coupling of the electric field to the earth-ionosphere waveguide.
BRIEF DESCRIPTION OF THE DRAWINGS
The above objects of the invention are achieved by the embodiments described herein in which:
FIG. 1 shows a typical magnetic field amplitude as a function of frequency measured on the ground at the Max-Planck Tromso "Heater" facility;
FIG. 2 shows the equivalent circuit system to describe modulation current;
FIG. 3 shows ELF power v. frequency for the Tromso facility as determined by Barr & Stubbe, with the ELF power scale multiplied to emphasize the scaling with size L and conductivity Δσ;
FIG. 4 illustrates the ionospheric model used in determining the energy dependent electronneutral collision frequency at a chosen height;
FIG. 5a shows the initial and steady state electron distribution for 75 km & S=10 -3 W/m 2 ;
FIG. 5b and 5c show the initial and steady state electron distribution for S=10 -2 W/m 2 at 90 km & 100 km respectively;
FIGS. 6a-6c show the Hall conductivity modifications for the conditions in FIGS. 5a-5c respectively.
FIGS. 7a-7c show the Pedersen conductivity modifications for the conditions in FIGS. 5a-5c respectively;
FIG. 8 shows Hall conductivity modulation vs. S at 70 km and 100 km;
FIG. 9 shows Pedersen conductivity modulation vs. S for 70 km and 100 km;
FIG. 10a shows ionospheric electron temperatures with all power delivered to an area corresponding to a half beam width of 7.5° ;
FIGS. 10b-10d show the power delivered over a wider area having many spots; R is the enhancement of ELF power over FIG. 10a.
FIG. 11 shows enhancement of ELF power by sweeping over an area with a beaming angle of 37.5°.
FIG. 12 is a schematic showing a system for continuous monitoring of ionospheric electric field and electron density profiles.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The ionosphere is an active, strongly nonlinear plasma medium containing free energy sources in the form of ambient currents and density gradients maintained by the input of the solar energy and the earth's rotation. Tapping these free energy sources is a longtime goal of space plasma physics. The best known non-linear effect caused by the ionospheric plasma is the so-called "Luxemburg Effect" in which an amplitude modulated high power HF wave propagating through the ionosphere causes modulation transfer (cross modulation) to other waves passing through the same ionospheric medium. The ionospheric plasma thus acts as a non-linear frequency transformer.
Manifestations of the frequency transforming properties of the ionosphere have been confirmed in a series of experiments conducted during the past decade in the U.S., the U.S.S.R. and Norway. The majority of the experiments demonstrated downconversion of HF power in the 1.5-10 MHz region to the VLF-ELF-ULF range (i.e., 10 kHz-1 mHz). The most comprehensive experiments were performed with the "heater" facility at Tromso, Norway operated by the Max Planck Institute. A summary of the ground measurements of the magnetic field amplitude vs. frequency are shown in FIG. 1. An analysis of the "Heater" results gave conversion efficiencies that varied from 10 -5 at a frequency of 2 kHz to 10 -8 200 Hz. Due to mechanical resonances of their L, diesel generators, data were not taken in the 20-200 Hz region. As seen from FIG. 1, the field amplitude of the 1-20 Hz waves is comparable to the 200 Hz amplitude. The technique of generating low frequency (Ω) waves from HF waves has been called the "Combination Frequency Signal" (CFS) in the U.S.S.R. literature because the low frequency could be selected by using two carrier HF waves with frequencies, ω 1 , ω 2 such that ω 1 -ω 2 =Ω instead of amplitude modulating the HF carrier. The "Heater" experimenters have called the technique the "Polar Electrojet" (PEJ) antenna.
PEJ antennae have been studied systematically over the last ten years and a quantitative understanding of their physical principles, well validated by experiments, has emerged. The free energy source for their operation is the auroral current system. This system is powered by the flow of the solar wind plasma intercepting the polar magnetic field lines. The resultant emf drives currents along the magnetic field lines of the collisionless magnetospheric plasma (Birkeland currents) which close across the magnetic field lines at an altitude between 70 and 100 km in the collision dominated ionospheric plasma. This DC cross field current is called the auroral electrojet current and is confined around the auroral oval. The auroral oval is a ring around the geomagnetic pole, where the ionospheric conductivity is enhanced by the continuous precipitation of keV electrons. The total power of the electrojet current system is 10 5 MW and its ohmic dissipation results in an increase of the ionospheric temperature by 100 K. The electrojet current I 0 is driven by an ionospheric electric field E 0 which results from mapping along the magnetic field lines of the emf induced by the solar wind. The average observed value of E 0 is about 25 mV/m, although at times it can reach 150 mV/m or be as low as 5-10 mV/m.
The PEJ antenna operates on the following principle. An HF transmitter which is amplitude modulated at a frequency Ω or, equivalently, two HF transmitters with frequencies ω 1 -ω 2 =Ω are incident on the lower ionosphere. Absorption of the HF power by the electrons that carry the electrojet currents results in local heating and modifies the temperature dependent value of the local conductivity. For values of Ω such that Ωτ C <<1, where τ C is the electron cooling time, the conductivity modulation Δσ reflects the shape of the envelope imposed by the heater modulation (for the lower ionosphere τ C ≈0.01-0.2ms). The associated variation of the current density is Δj, given by ΔJ=Δτ·E 0 . This constitutes a primary source of modified current. For low frequencies the total current is divergence free. As a result, a secondary current is set up consistent with the divergence free condition. The total current consists of the current I 1 flowing through the heated volume a current I 2 flowing around the modified volume, and a field aligned current I 3 flowing through the magnetosphere to the conjugate ionosphere. The equivalent circuit shown in FIG. 2 was proposed by Stubbe et al. to describe the radiative loop. It is easy to see that for the ELF range (10Hz-5kHz) the radiating current is essentially due to I 1 and only the R 1 , L 1 part of the circuit is active. For the ULF part (1-10 Hz) I 2 becomes relevant. For our frequency range, the field aligned currents do not respond (L M ≃50H) and the radiating currents are essentially due to the locally modified currents.
Relating the amplitude of the ELF waves on the ground to the extent and characteristics of the modified region in the ionosphere and to the design characteristics of the HF transmitter is a complex problem. Aspects of the problem have been examined by many authors (Kotik and Trakhtengerts 1975, Belustin et al 1977, Tripathi et al 1982, Fejer and Krenzien 1982, Barr and Stubbe 1984a,b). It involves the following series of sequential steps. Based on the transmitter characteristics (power, gain, H.F. frequency and modulation frequency) and the applicable model of the ambient ionosphere, the conductivity modulation is first computed as a function of altitude. This allows for the calculation of the modulated current altitude profile, for any specified ambient ionospheric electric field (assumed or measured). This calculation involves computing the primary current, the polarization currents required to set up quasineutrality, and the induction currents caused by the time dependence of the magnetic field. Finally, from the modulated current profile the excitation and propagation of the ULF/ELF/VLF waves in the earth's ionospheric waveguide can be computed by using either the extended source technique (Tripathi et al, 1982) or with an equivalent ULF/ELF/VLF moment in the ionospheric reciprocity principle (Galejs 1968, 1971; Barr and Stubbe 1984a,b).
Within the experimental and theoretical uncertainties our purpose can be accomplished by starting from the current experimental results in the frequency range of 50-500 Hz and analyzing them under the assumption that the power generated is proportional to the square of the dipole moment
M≡IL (1)
where I is the total modulated current contributing to the ELF field on the ground and L is the linear size of the modulated region. All other factors entering the efficiency calculation can taken from the available experimental data base. The measurements and analysis of the Tromso results (Barr and Stubbe 1984a) can be used as a baseline input. These results are in general agreement to the ones reported from HIPAS (Ferraro et al 1988). The range of 50-500 Hz has been selected in order to avoid effects associated with waveguide resonances which arise for frequencies above 1 kHz.
The experimental results indicate that when the heating transmitter is operated at a power level of 150 MW ERP (effective radiated power), the amplitude of the ELF field measured on the ground is 100 IV/m or 1 pT. This corresponds to about 10-100 mW of radiated ELF power in the 200-500 Hz range (Barr and Stubbe 1984a). The equivalent radiating horizontal dipole at 75-80 km altitude in the ionosphere is IL 1/43-5×10 4 A-m which corresponds to an equivalent ground based electric vertical dipole with IL ≈2-4×10 3 A-m. The polarization is consistent with predominance of Hall current modulation. Computations based on a fluid model indicate that for an assumed ambient ionospheric electric field E 0 =25 mV/m the peak values of the modulated current density are in the range of 10 -8 A/m 2 and are located between 75-80km in altitude. The effective horizontal radiated current moment M can be estimated by height integration as
M=IL=ΔjΔzL.sup.2 =ΔσΔzE.sub.0 L.sup.2 (2)
where Δj is the modulated current density, Δz is the extent of the effective radiating layer in altitude (or the vertical extent of the effective radiating layer) and Δσ is the modulated conductivity. Since, for the high altitude case
I=ΔjΔZL=E.sub.0 ΔτΔZL (3)
This result (equation 2) is also obtained by combining equations 1 and 3.
The value of the ELF field on the ground depends on the value of M and the efficiency at which the field couples to the earth ionosphere waveguide (excitation factor). For the ELF range, the excitation factor varies as 1/Ω. The ELF power on the ground would then be
P.sub.ELF ˜(E.sub.0 ΔZ).sup.2 ε.sup.2 (Ω)Δε.sup.2 L.sup.4, (4)
where ε(Ω) is the waveguide excitation factor. The HF to ELF conversion efficiency η is then given by ##EQU1## where P HF is the average ground based HF power. For the case analyzed by Barr and Stubbe, a square heating pulse was used. The value of P HF was 1 MW and at the ELF generation region L ≈ 10km corresponding to a heater beam width of 7.5°.
For the typical experimental conditions L ≈ 20km (i.e. at a heater beam width of 15° ), Δz ≈ 10km, E 0 ≈ 25mV/m, the value of IL ≈ 3-5 × 10 4 A-m corresponds to a peak value of Δσ≈3-4 × 10 3 sec -1 . This is achieved with an incident HF power density of 2 mW/m 2 at 75-80 km height. Finally it should be noted that the value of IL is independent of frequency and the frequency dependence in the ELF power is attributed to the scaling of the excitation efficiency as suggested by Galejs in 1971.
Since the quantities that can be controlled from the ground are the value and the altitude location of the conductivity modulation, Δσ, and the size L, it is instructive to cast the experimental data as interpreted by Barr and Stubbe (1984a) in the form of FIG. 3. Notice the important scaling valid for each ELF frequency, i.e.
P.sub.ELF M.sup.2 ˜ (Δσ).sup.2 L.sup.4 (6)
For instance, increasing the peak conductivity modulation by a factor of 10 while keeping L ≈20km, increases the radiated power at 500 Hz from 100 mW to about 10W. Similarly, increasing the size L by a factor of 5 while keeping Δσ≈3-4 × 10 3 sec -1 , the radiated power would increase by a factor of (5) 4 ˜ 6 × 10 2 .
A critical input needed for determining the factors that optimize P ELF is the scaling of the conductivity modification Δσ on the HF power density S at the modified height, ##EQU2## where P HF is the ground HF power and L is the spot size at the appropriate height. Of course this neglects absorption at lower heights, a point discussed further herein. Assuming that ##EQU3## we find from (4) - (6) that
P.sub.ELF ˜P.sub.HF.sup.2α L.sup.4(1-α) (9)
For α≈1, we find that P ELF is independent of the antenna gain and scales as
P.sub.ELF ˜P.sup.2.sub.HF (10)
Namely the HF to ELF conversion increases as the square of the HF power. For α>> 1) the ELF conversion efficiency increases enormously by increasing the ground based HF power, P HF , while maintaining the same antenna gain (i.e., L = const.). For α>>1, more efficient conversion requires large spot sizes.
We now evaluate the level of conductivity modulation at various ionospheric heights as a function of the incident HF power density S. The calculation is "local" and neglects transport. From the modulated conductivity, we can evaluate the modulated current for a given ionospheric electric field. Contrary to previous studies (Stubbe and Kopka 1977, Tomko 1981, Chang et al 1981, James 1985) which used fluid equations to compute the variation of the electron temperature T e as a linear approximation, the present approach uses the complete time dependent kinetic equation for the electron energy distribution function f(ε). For an HF electric field of peak amplitude E o and frequency ω o at the chosen height, f(ε) is given by (Gurevich 1978): ##EQU4## where ν(ε) is the energy dependent electron-neutral collision frequency at the chosen height and Ω is the electron cyclotron frequency. v(1/3) can be written as: ##EQU5## where N m is the neutral density at the chosen height, τ m is the momentum transfer cross section and the summation is carried over both O 2 and N 2 species. The ± signs correspond to o (+) and x (-) mode heating correspondingly. The term L(ε) operator that represents the energy loss due to various inelastic processes. It includes excitation of rotational, vibrational and optical levels as well as ionization and attachment for N 2 and O 2 . Detailed expressions of the inelastic contribution were given by Gurevich in 1978. Note that the latter process is not important for the power densities analyzed here. Equation (11) can be solved numerically for f(ε, t) at various altitudes, HF power density values, S, and modulation frequencies, ω. The time dependence of the conductivity is found from ##EQU6## where σp, σh, σz are the Pederson, Hall and parallel conductivities and n is the electron density. As noted previously herein, a kinetic analysis is an absolute requirement for exploring high power densities. The initial f(ε,t=O) was taken as Maxwellian at T e ≈0.025 eV. For the studies reported herein ω o ≈1.8×10 7 rad/sec which corresponds to a heater frequency of 2.8 MHz.
We report below results for daytime ionospheric conditions corresponding to altitudes between 70-100 km. The ionospheric model used is shown in FIG. 4.
The need for a kinetic description at high power and high altitude is obvious from the distribution function shown in FIG. 5. FIGS. 5a-c show the initial and steady state distribution functions for ionospheric heating at 75 km, 90 km and 100 km altitude and at values of S=10 -3 W/m 2 , 10 -2 W/m 2 , 10 -2 W/m 2 correspondingly The time required to reach steady state was in all cases much shorter than 10 -4 sec. This implies that steady state is reached at times much shorter than the relevant modulation frequencies. It is seen that at low altitude and low power density (i.e. 75 km, 10 -3 W/m 2 ) f(ξ) does not deviate much from Maxwellian and the fluid description is a reasonable approximation. This, however, is not true for the other two cases where the high energy tails of the distribution functions become the dominant part.
FIGS. 6-7 show the time dependence of the Hall and Pedersen modulation respectively for the above three cases. At 75 km and 10 -3 W/m 2 the Hall conductivity modulation is about 7 × 10 3 sec -1 which is consistent with the value from the Tromso experiments. The Pederson conductivity modulation is significantly smaller. This is reversed for the 90km and 100km cases at 10 -2 W/m 2 . The Hall conductivity modulation becomes progressively smaller and is negligible at 100 km. Furthermore, the level of the Pederson conductivity modulation is about 3 × 10 4 sec -1 at 90 km and 6 × 10 4 sec -1 at 100 km. It is clear that if the size L, which is controlled by the antenna gain was the same for all three cases and the increase in the power density was entirely due to an increase in P HF by a factor of 10, the radiated P ELF would increase by factors of 20 and 100 for the 90km and 100 km cases respectively over the 75 km case. Since steady state is established for all cases much earlier than the low frequency oscillation period, the values of Δσ are independent of the ELF frequency.
In order to determine the scaling of the conductivity modification with power density and altitude, a survey was performed of the level of steady conductivity modification for altitudes 70 and 100 km and values of S in the range of 10 -4 -1 W/m 2 . The results for the Hall and Pederson conductivities are shown in FIGS. 8 and 9. The boundary altitudes were chosen in a way that they reflect the range of variation of the Pedersen and Hall conductivities with altitude.
For low altitudes (70-75 km) the Hall conductivity provides the dominant contribution. The value of Δσ h increases very weakly with power density (α<1/2) and saturates at a value of S about 10 -3 W/m 2 . Further increasing the power density does not produce any increase in the modulated current density. In accordance with the discussion of Eq.(10) above, optimization of the conversion efficiency requires increases in L under constant S.
For high altitude (> 90 km) heating, modification of the Pederson conductivity dominates. The value Δσ p increases as S 2 (i.e. α=2), up to power density of 10-2 W/m 2 and saturates slowly afterward. There is an obvious premium in increasing P HF , since in this case P ELF P 4 HF , while keeping S=10 -2 W/m 2 .
Finally, the maximum value of Δσ is achieved for high altitude heating.
In order to have uniformity in the results and be close to the benchmark case, the survey shown in FIG. 5 was performed using the same frequency ω o =1.8 × 10 7 for all the three altitudes examined (75, 90, 100km). This frequency corresponds to a critical electron density n c =10 5 #/cm 3 which corresponds to an altitude of 105 km for the model ionosphere used here. The electron densities at 75, 90 and 100 km (FIG. 4) are 3 × 10 2 #/cm 3 , 8 × 10 3 #/cm 3 and 8 × 10 4 #/cm 3 . Since collective effects are not included, the 100 km results are close but within the validity range of the model. Furthermore, as long as the half width of the heater is smaller than 26°, effects of resonance absorption can also be neglected even for the 100 km case. However, we should note that for the high altitude cases (> 90 km) the results are applicable to frequencies higher than the 2.8 MHz by a simple scaling law based on Eqs. (9) and (10). Note that for ω>2.8 MHz and h>90 km, (ω o ±Ω) 2 >>V(ξ). Therefore ##EQU7## Where D (ε) is the quiver energy of the electrons in the high frequency field, with an effective frequency ω eff =ω o ±Ω, defined as ##EQU8## The results can be generalized to any frequency by noting that the solution of Eq. (11) is self-similar with respect to the value of ##EQU9## Thus, for a frequency ω>ω o a power density is higher by a factor (ω±Ω) 2 /(ω o ±Ω 2 than for ω=ω o will be required.
We now combine the results of Barr and Stubbe (1984) as shown in FIG. 2 with the results reported above and use them to determine the HF to ELF conversion efficiency and techniques by which it can be optimized. Based on Hall conductivity modulation of the polar electroject at 70-75 km altitude Barr and Stubbe (1984) estimate a power conversion efficiency of 5-10 mW per MW of HF at 200 Hz. This implies an overall conversion efficiency of about 10 -8 , compared with 10 -6 conversion achieved by the Navy facility. For low altitude heating the results discussed above indicate that increasing the power does not have any significant effect an the ELF power. However, as shown in Eq. (4) for constant power density and therefore constant Δσ, P LEF -L 4 .
This suggests that increasing the heating area increases the efficiency. Equation 5 can be rewritten as: ##EQU10## wherein K incorporates factors beyond control, i.e., E 0 , ΔZ, ε, etc.
Increasing the size of the modulated region requires matching the operation characteristics of the HF heater to the non-linear response of the ionosphere. In order to be specific, we consider the particular case of 200 Hz (Ω=1.2 × 10 3 sec -1 ).
The particular observations were made using an HF frequency f =2.76 MHz, effective radiated power ERP =150 MW, and antenna beam width 2Θ 0 =15°; the estimated ELF power was 6-8 mW, giving an efficiency of η˜10 31 8. The observations were consistent with a modified Hall current density of 10 -8 A/m 2 , which corresponds to a conductivity modification of Δσ 0 =4×10 -7 mhos at an altitude h 0 =78-80 km, and a value of E 0 =25 mV/m. The value of T e corresponding to the modified conductivity was saturated at T e ≈2000K. The power density at 78-80 km was of the order of 2 mW/m 2 . For the ELF/ULF frequency range of interest, the observed ELF power was consistent with a horizontal dipole in the ionosphere with magnetic moment M=3.5×10 4 A-m. As is well known from the work of Galejs, horizontal dipoles are inefficient exciters of the earth ionosphere waveguide at 100-200 Hz, having excitation efficiency ε of the order of 10 -2 compared with that of a comparable ground based electric dipole. Notice that ground based ELF sources are also very inefficient, with typical efficiencies ε of the order of 10 -3 or less for horizontal magnetic dipoles. From Eq. (17), the measured efficiency and the values discussed above, we can rewrite Eq. (17) as ##EQU11## where Δσ=4×10 -7 mhos, L 0 =h 0 tanΘ 0 ≈10 km, P HF ,O =1 MW are the values of the reference case. The on-off heater time rH O is half of the wave period of 200 Hz. Furthermore, we should remember that the Δσ O modification over an L 2 O area was accomplished with an incident power flux S O ≈2 mW/m 2 at h O .
The modulated heating of the ionosphere by an X-mode HF field of frequency ω and peak amplitude E O is given by ##EQU12## where ε is the quiver energy defined as ##EQU13## and ω O is the effective frequency
ω.sub.O =ω-Ω.sub.e (21)
Also Ω e is the electron cyclotron frequency ν en is the electron neutral collision frequency for momentum transfer ν er the rate of inelastic electron neutral collisions resulting in excitation of the rotational levels of N 2 , the term with ν ev is the vibrational loss and T O ≈100 K is the ambient temperature of the neutrals. For the range of electron energies of interest here ##EQU14## where N is the number density of the neutrals. Defining ##EQU15## we can cast Eq. (19) in a dimensionless form as ##EQU16## where F=5.3±3.755 tanh [0.11(y-18)]. The modification of the temperature results in changes in the conductivity of the medium. For the ionosphere, the conductivity tensor σ transverse to the magnetic field is given by ##EQU17## where σ p is the Pedersen conductivity, i.e., the conductivity along the electric field E O . and σ H is the Hall conductivity. In our dimensionless units they are given by ##EQU18## where ω e is the plasma frequency and we have taken Ω e /2π1.35 MHz. From the above equations we note that the values of the dimensionless quantities α and β, Γ and τ are altitude dependent, while the value of K depends only on the incident HF power density. Equations (13)-(28) can and have been solved numerically under several conditions. Important insight is provided by considering some limiting cases.
(i) The regime of interest corresponds to β<<1, i.e., neutral densities N ≈10 14 #/cm 3 , so that for y=1, rP/r H <<1. Furthermore, heating always decreases σ H forcing the Hall current to flow outside the heated volume. The Pedersen conductivity has a different dependence on Y. For values of βy<1, σ P increases with y, producing currents in antiphase with the Hall currents, while for βY>1 it decreases with y and the currents are in phase with the Hall currents. Notice that since the ambient electrojet current flows at an angle
δ=tan.sup.-1 (1/β)
with respect to the ambient E O , it is a Hall current. For βy=1 it flows at a 45° angle with respect to E O . This implies that the induced polarization electric field E P has the same value as E O . Finally for βy>>1 the Pedersen current becomes dominant.
(ii) Inspection of the heating equations, Eqs. (24), shows the presence of a strong barrier for values of y ≈20-30 due to the third term on the right side of Eqs. (24). This term is due to the high value of the inelastic electron-N 2 cross section for vibrational excitation. It implies a heavy energy penalty in achieving temperatures past y ≈ 20.
(iii) Equations (24) shows that for values of <20αy<1 the heating rate is exponential with τ, while the cooling rate, which in this regime is due to rotational energy transfer, has a weaker (τ 2 ) dependence.
Following Barr and Stube we assume that the source height is at 78-80 km, which corresponds to neutral density N≈2×10 14 #/cm 3 . For this value of density α=0.05 and α=0.05. The value of the quiver energy in K is given by ##EQU19##
For f 2.76 MHz, ERP of 150 MW which corresponds to 2 mW/m and T O ≈100 K,.sup.˜ε/T O ≈22. Using Eq. (23), we find that K =30. Finally for an ELF frequency of 200 Hz the dimensionless ELF time is τ ELF =34. FIG. 10(a) shows the waveform of y for a square wave heater operation with period half the period of the ELF wave. It clearly demonstrates the inefficient fashion in which the heater power is utilized. First, more than 95% of the power is utilized to maintain the temperature at its saturated value, while the absorbed energy is transferred to the excitation of N 2 vibrations which, of course, do not contribute to the conductivity modification. Second, we are overheating the plasma. There is little, if any, gain by heating past the value of y=1/β, as is obvious from Eqs. 24a & b. FIG. 10(a), however, also suggests the operating procedure which can lead to improved efficiency, which is discussed next.
Let us consider a facility with the same average power as the Tromso "Heater" facility but equipped with the capability to scan fast over an area up to a cone of 37.5° (FIG. 11). The ratio of this area to that modified by the 7.5° half-beamwidth HF antenna is ##EQU20## If using the same average power as the "Heater" facility we modify the conductivity of the accessible area A at the desired ELF frequency, the efficiency, according to Eq. (18), will increase by a factor ξ 2 which corresponds to 3.3 × 10 3 . It will, however, be reduced by the relative modification of conductivity. The quadratic dependence ξ 2 on the area is a consequence of the fact that a larger area produces a simultaneous increase in total current as well as flux. Techniques by which this can be accomplished are demonstrated below.
We now compute the power enhancement over the standard case that can be accomplished by dividing the area A corresponding to the cone of 37.5° into a number of smaller areas A O corresponding to the half-beamwidth of 7.5°, and sweeping the transmitter so that during the half cycle τ ELF/2 =17 it stays on each spot only A O /A of the time. The expected enhancement of R of the ELF power over that of the standard case is given by the ratio of the efficiencies obtained from Eq. (17) for the two cases. The antenna with beamwidth of 15° irradiates each area A O for the duration τ on with a revisit time τ off and so the total heated area is A=(τ on +τ off )A O . Further, if the antenna gain K is reduced from the value of 30, the heated area is increased by the factor 30/K. Thus, for the same power P HF , we get ##EQU21## where Δσ is the final conductivity modification averaged overall the spots and Δσ=0.72 is the conductivity modification of the standard case (FIG. 10(a)). The heated area can be increased by choosing small τ on and large τ off , whose limits are set by the heating and cooling timescales. The heating timescale is given by Eq. (24), which for y >1 yields y=y(τ=0) exp(τ/τ O ) with τ O =3/2K. To achieve a 20% rise in the temperature in one heating cycle we need τ on ≈0.2 τ O , which is 0.01 for K =30. A value τ on smaller than this will lead to a weak heating. Since the idea of the proposed scheme is to avoid the strong vibrational losses by keeping T e <2000 K, the relevant cooling time is that due to the rotational losses. In the normalized units this has a value ˜1 and so τ off should be <1 to prevent excessive cooling. With these considerations different cases are examined as follows.
We first take the case where the full power (K=30) of the antenna irradiates each area A O over a time τ on =0.02 with a revisit time τ off . The procedure was repeated until τ=17. The enhancements for different values of τ off /τ on , results in an increase of R. This is, however, accompanied by a decrease in Δσ because the distribution of the power into a much larger area limits the heating. This overcomes the advantage of the increase in area, and beyond τ off /τ on =40 the value of R decreases. There is thus a balance between these two effects, and it gives an optimum value of τ off for a given τ on . The peak enhancement for this case was 455, corresponding to τ off τ on =40, and the heating profile of the temperature of a typical spot is shown in FIG. 10(b). The value of Δσ is the average obtained in the last (τ on +τ off ) before the power was turned off at τ=17. With the same K value and different values of τ on , the enhancement R will be optimum at different values of τ off τ on . The reason for the relatively low enhancement compared to the theoretical maximum of 3× 10 3 is the reduction in the conductivity modulation, giving a low value for the (Δσ/Δσ) 2 factor.
TABLE I______________________________________Enhancement of the ELF generation for different antenna gains(K) and τ.sub.off /τ.sub.on ratios. a. The enhancement R for K =30 and awide range of values of τ.sub.off /τ.sub.on. The gain fromincreasing τ.sub.off /τ.sub.onis offset by the accompanying decrease in Δσ, giving thepeakvalue of R - 455. b. For half the full antenna gain (K = 15) thevariation of the enhancement around the peak value(R = 458) is shownτ.sub.off /τ.sub.on Δσ R______________________________________a. K = 30 and τ.sub.on = 0.0220 0.49 20430 0.44 35335 0.41 41740 0.37 45545 0.31 39650 0.21 224b. K = 15 and τ.sub.on = 0.0316 0.42 39917 0.41 42418 0.40 44519 0.38 45820 0.36 45221 0.34 43922 0.31 397______________________________________
FIGS 10(c) and 10(d) indicate the result of a trade-off study in which the antenna gain wa reduced by factors of 2 and 3 so that the area of each spot was 2A O and 3A O , respectively. This of course, results in a reduction of the corresponding value of K. In the case presented in FIG. 10(c), the antenna gain is reduced by a factor of 2 so that K=15 and the area of each spot is 2A O . This case requires a longer τ on to achieve significant heating of a spot and also the total number of spots that can be covered is reduced (Table Ib). Unlike Table Ia, which shows the enhancement for a wide range of τ off τ on , Table Ib shows the sensitive dependence of R on τ off τ on around the case of maximum enhancement. FIG. 3(d) shows the case with K=10 where the maximum enhancement 524 in efficiency was achieved. In this case only 15 spots each with area 3A O were heated. In all the three cases K=10, 15 and 30 shows in FIGS. 10(b), 10(c), and 10(d), enhancements 500 are easily achieved and the waveforms of y in these cases are similar to each other.
Optimum waveguide excitation efficiency occurs when the structure of the ELF fields generated in the ionosphere by the modulated HF heating matches the fields of the least damped eigenmode of the Earth-Ionosphere waveguide. For the frequencies considered here, the relevant mode is the TEM mode which is characterized by the presence of a propagating vertical electric field in the waveguide. By controlling the HF heater frequency and scanning antenna pattern, the coupling efficiency to the TEM mode of the waveguide can be optimized. To achieve this, good models of the ionospheric electric field and electron density profiles are required. The continuous monitoring of these quantitites in real time constitutes a further aspect of the invention. A schematic of how this is accomplished is shown in FIG. 12. An independent fixed HF heater (H1) with large bandwidth is modulated at a fixed VLF frequency in the range of 1-2 khz. The HF frequency is swept over its bandwidth on a few seconds times. The components of the electric and magnetic fields generated at the chosen VLF frequency are continuously monitored by a receiver (R1) and fed into a processor (P1). The data from a continuously operating inosonde (I) are also fed into the processor P1. Inverting the data from R1 and I, the processor P1 produces models of the ambient ionospheric electric field and the electron density profile. These are fed to another processor (P2) which determines the HF frequency and sweep pattern required to obtain optimum overall conversion efficiency. These are relayed to the ELF generating HF heater (H2) for implementation.
While specific embodiments of the invention have been described and illustrated, it will be clear that variations in the details of the embodiments specifically illustrated and described may be made without departing from the true spirit and scope of the invention as defined in the appended claims. | 4y
|
The present application claims priority to provisional patent application entitled, “LOW-E HOUSEWRAP,” filed on May 21, 2010, and assigned U.S. Application Ser. No. 61/346,916.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to building structure materials, and more specifically to an infiltration barrier used in building construction to improve energy efficiency and to protect against air infiltration and moisture build-up in buildings.
2. Description of Related Art
In order to improve the energy efficiency of new and existing buildings, it has been common practice in building new structures, and in residing old structures, to cover the exterior wall sheathing with an infiltration barrier, for example, prior to installation of a covering material such as siding. One such infiltration barrier is a high density polyethylene fiber sheeting. While infiltration barriers cut down on drafts and thereby convective heat loss, they provide little other contribution to the energy efficiency of the structure.
In addition to addressing energy efficiencies of new and existing buildings, moisture concerns can be one of the worst enemies of home or building construction. Water or moisture or humid air infiltration if allowed to penetrate behind siding or brick can saturate the wood of a building structure, thereby creating an environment that encourages mildew or rot. A weather resistant barrier has for many years been applied to the wood studs of buildings and homes in order to resist the moisture or water generated by weather. Such material is typically flexible and in a film or sheet form. Typically, this weather resistant barrier or “house wrap” is applied to the wooden stud frame before the application of a final siding or veneer (e.g. brick, metal, painted wood). Many such “wrap” products are commercially available such as, for example: Dupont Tyvek®, Typar®. Housewrap (www.typarhousewrap.com), and Barricade®, building wrap (www.ludlowcp.com).
In 2010 the International Energy Conservation Code (IECC) and International Residential Code (IRC) increased the thermal performance requirements for residential walls. Both of these standards seek to improve thermal performance and reduce energy needs per dwelling. As of January 2010 the U-value requirement for geographical area or zones 5-8 is 0.057; the reciprocal R-value for wall systems is R-20. The U-factor is the inverse, or reciprocal, of the total R-Value, i.e.: U-factor=1/Total R-Value. The R-Value is the thermal resistance to heat flow. A larger R-Value means that the material has greater thermal resistance and more insulating ability as compared to a smaller R-Value. Such R-Values can be added together. For instance, for homogeneous assemblies, the total R-Value of an insulation assembly is the sum of the R-Value of each layer of insulation. These layers may include sheathing and finishes, the insulation itself, air films and weatherproofing elements.
In order to meet the new building requirements, builders have employed additional building techniques such as altering construction of framed openings. For example, typically, builders have constructed walls on 2×4 framing. However, due to the revised requirements, builders are altering building designs by constructing walls on 2×6 framing and inserting, for example, R-20 mass insulation within the respective wall cavity in order to meet the energy/code regulations mandated within the building industry. These techniques, however, increase construction costs because of the added and more expensive construction materials. In addition, the increased size of framing also produces a loss in living space. Nevertheless, many builders have simply accepted the added cost and loss of living space created by the newly implemented thermal code changes.
Accordingly, a need exists for providing a protective wrap that improves energy efficiency and protection against air infiltration and moisture build-up in buildings while satisfying newly implemented industry-wide energy/code regulations. There is also a need for employing a protective wrap which meets or exceeds the newly implemented code requirements on existing framing structures or openings and/or without increasing the wall profile of a building.
SUMMARY OF THE INVENTION
The present invention provides a low-E housewrap material which may be implemented on traditional 2×4 framing having R-15 mass insulation material within existing or newly constructed framing cavities. The material of the present invention also meets requirements for serving as a water resistive barrier as defined by The International Code Council's (ICC) codes and standards used to construct residential and commercial buildings, including homes and schools (e.g., ICC AC38). Thus, by not increasing the wall profile in the attempt to meet new industry standards, the builder does not have to perform additional techniques or provide additional expenses for constructing framed openings.
Still other aspects, features and advantages of the present invention are readily apparent from the following detailed description, simply by illustrating a number of exemplary embodiments and implementations, including the best mode contemplated for carrying out the present invention. The present invention also is capable of other and different embodiments, and its several details can be modified in various respects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be understood more fully from the detailed description given below and from the accompanying drawings of various embodiments of the invention, which, however, should not be taken to limit the invention to the specific embodiments, but are for explanation and understanding only.
FIG. 1 provides a top view of a low-E housewrap material according to an exemplary disclosed embodiment;
FIG. 2 provides a cross-sectional view of a low-E housewrap material according to an exemplary disclosed embodiment;
FIG. 3 provides a cut-away perspective view of a low-E housewrap material according to an exemplary disclosed embodiment;
FIG. 4 provides a top view of a low-E housewrap materials during an assembly method according to an exemplary disclosed embodiment;
FIG. 5 provides a perspective view of the low-E housewrap materials during the assembly method of FIG. 4 ;
FIG. 6 provides a top view of a low-E housewrap materials during a continued assembly method according to an exemplary disclosed embodiment;
FIG. 7 provides a perspective view of the low-E housewrap materials during the assembly method of FIG. 6 ;
FIG. 8 provides a top view of low-E housewrap materials after assembly according to an exemplary disclosed embodiment;
FIG. 9 provides a bottom view of low-E housewrap materials prior to assembly according to an exemplary disclosed embodiment;
FIG. 10 provides a top view of low-E housewrap materials during an assembly method according to an exemplary disclosed embodiment;
FIG. 11 provides a bottom view of low-E housewrap materials after assembly according to an exemplary disclosed embodiment;
FIG. 12 provides an exemplary exterior wall according to an exemplary disclosed embodiment; and
FIG. 13 provides a low-E housewrap material application to the exemplary wall structure of FIG. 12 . according to an exemplary disclosed embodiment.
DETAILED DESCRIPTION
A low-E housewrap is described. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the exemplary embodiments. It is apparent to one skilled in the art, however, that the present invention can be practiced without these specific details or with an equivalent arrangement.
Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, FIG. 1 illustrates a top view of low-E housewrap materials according to one disclosed embodiment of the present invention. By way of example, two pieces of the low-E housewrap materials 10 , 12 are shown. Each of the two pieces of low-E housewrap materials 10 , 12 may comprise flap portions 14 , 16 , respectively, at one end thereof. At another end the low-E housewrap material may include an adhesive strip 18 such as that provided on low-E housewrap material 10 . In a preferred embodiment, the top surface 20 , 22 of the low-E housewrap materials 10 , 12 , respectively, is a reflective material such as a layer of reinforced foil material.
Turning to FIG. 2 , a cross-section of the low-E housewrap material 12 is shown. The low-E housewrap material 12 may comprise an assembly of product component parts including, for example, a reflective foil material 34 , foil reinforcement 26 , and a foam material 28 . In one embodiment, the reflective material may comprise a facing of approximately 99.4% polished aluminum. It is noted that the reflective material may comprise a facing having any suitable amount of aluminum, for example, greater than about 90%, preferably between about 90% and about 99.9%, even more preferably between about 99.0% and about 99.9%. The reflective foil material 34 may be non reinforced on one side. On the other side, the reflective foil material 34 may comprise a foil reinforcement 26 including, for example, a scrim foil reinforcing 30 (e.g., see FIG. 3 ). Scrim is a term known in the art to consist of crossed lines of plastics material which serve to strengthen the overall product and to prevent stretching damage to the layers. The reflective foil material 34 and foil reinforcement 26 may be applied over and bonded to the foam material 28 . The scrim foil reinforcing 30 is sufficient to provide a tensile strength of approximately 23 pounds per inch width in a machine direction and 25 pounds per inch width in a cross machine direction on a low-E housewrap material test specimen cut approximately 1″ wide by 9″ long in standard ambient lab conditions. The foam material 28 serves as a polyolefin thermal break such as one comprising a closed cell polyethylene foam. In a preferred embodiment, the nominal thickness of the polyolefin thermal break is approximately ¼″ (0.25″). It is noted that the nominal thickness of the polyolefin thermal break may be any suitable thickness, for example, greater than about ⅛″ (0.125″) and less than about ⅜″ (0.375″). Thicknesses above about ¼″ are within the scope of the present invention. It is noted that a thickness greater than about ¼″ may require use of 2×6 framing instead of the more traditional 2×4 framing. The low-E housewrap 12 may also incorporate a self adhered drainage plane 24 feature as further described below.
Thus, the invention includes a layer of polyethylene foam which serves as a support for the other added component layers. Polyethylene foam or equivalent polypropylene foam may be utilized, both being in the chemical family designated as polyolefins. A thin layer of aluminum foil is bonded indirectly to one or both sides of said foam layer. Thin polyethylene layers are placed between the aluminum foil and the foamed layer. The thin polyethylene is bonded to the aluminum foil layer to greatly improve its resistance to tearing. This strengthening feature means that the end product has a much wider use than has been known in the art. A layer of strengthening scrim may be added to further enhance the product integrity. In practice of the invention, the various layers adjoin one another after being flame or heat roller laminated together.
In certain embodiments and in practice of the invention, both sides of the foam layer may be covered with layers as described above. The end product may thus appear identical on either side with the aluminum foil layers being externally located. Thus, use and installation is simplified since the product may be used with either side facing out since both external faces are identical. The resulting bonded layers are easily rolled, transported and installed without requiring special tools or environmental precautions which must be taken with many other prior art insulations.
Turning to FIG. 3 , the low-E housewrap 12 comprises perforations 32 sufficiently spaced to ensure that the low-E housewrap material does not act as a vapor barrier. In one preferred embodiment, the perforations in the low-E housewrap are generated from perforation system consisting of 1/16″ punchers placed in four holes per 1.25 square inch sequence on a collar mechanism. The collar mechanism is mounted to a drive roll assembly for perforation of the low-E housewrap wherein a 1.25 square inch perforation pattern is achieved on the finished product. A perforation pattern of 1.25 square inch allows low-E housewrap 12 to meet the criteria for perms, water vapor transmission and water resistance while maintaining an effective emissivity rating. This is unique and contrary to industry standards wherein in many applications, micro perforations are generated in housewraps using needles for vapor penetration. However, in such convention applications, the micro perforations are susceptible to resealing when exposed to higher temperatures. This affect may trap moisture and induce undesirable results such as mold and rot. In contrast, the present perforation pattern of the prescribed invention eliminates the possibility resealing when exposed to higher temperatures. Spaced in approximately 1.25″ square perforations, the low-E housewrap material achieves a preferred permeance and water vapor transmission of approximately 7 perm or 40 g/day/m 2 . As such, the present low-E housewrap material performs within the optimal permeance and water vapor transmission range of about 5 to about 20 perm.
The present low-E housewrap material meets the Standard Specification for Reflective Insulation, C 1224-03, Section 6, 6.1, which states that “Low emittance materials shall have a surface with an emittance of 0.10 or less, in accordance with test Method C 1371.” Specifically, the present low-E housewrap material achieves an emittance of 0.10 or less, more specifically within a range of about 0.03 to about 0.05, in accordance with test Method C 1371.
Accordingly, the product low-E housewrap material of the present invention is constructed to include the following approximate performance characteristics:
Test Description
Test Results
Perm Test
7 perms
ASTM E-96
Water
As Received 23 hrs
Resistance
Pass
ASTM D-779
Weathered 23 hrs
Pass
Ultraviolet light
No Cracking
Accelerated Aging
No Cracking
Tensile Strength
23 lbs/inch
(machine direction)
25 lbs/inch
(cross direction)
U-value
.056 vinyl
Wall (zone 5-7)
2010 IECC
U-value
.051 brick
Wall (zone 5-7)
2010 IECC
U-value
.063 Stone
Wall (zone 5-7)
2010 IECC
Although the use of 1/16″ punchers at a rate of four holes per 1.25 square inch is described above and represents one of many preferred embodiments of the present invention, other size punchers may be used and other rates of holes per given area are within the scope of the present invention. For example, the diameter of the puncher may be varied to any suitable size and the rate may be modified to achieve the particular permeance and emittance standards required by a particular building code, specification or other requirement.
The system U-values described in The Evaluation of Thermal Resistance of a Building Envelope Assembly demonstrates the performance of wood framed walls (2×4 construction 16″ on center). The U-value calculations are based on methods outlined by the ASHRAE Handbook of Fundamentals. The U-value performance of these systems achieve a U-value between 0.051 (brick), 0.056 (vinyl) and 0.063 (stone) satisfying or exceeding requirements for zones 1-7 established by 2010 IECC Code Table 402.1.3 or equivalent UA alternative values established by other code bodies.
Flap portion 16 is illustrated in FIG. 3 . This overlapping flange serves as a self adhered drainage plane 24 . During assembly of one or more low-E housewrap sections, the flap portion 16 may be assembled to cover an edge of an abutting portion of another low-E housewrap material section in order to seal the edge. For example, turning to FIGS. 4 and 5 , a first section 10 of low-E housewrap material is positioned near a second section 12 of low-E housewrap material. The flap portion 16 of the second section 12 of low-E housewrap material may be disposed over an edge portion 38 of the first section 10 of low-E housewrap material. In one embodiment, the aforementioned edge portion 38 may include an adhesive strip 18 for retaining the flap portion 16 thereon. The adhesive strip 18 may be employed on the top surface 20 such as on the reflective foil material 34 . While the adhesive strip 18 has been described and shown in the drawings for illustrative purposes, any means may be employed which is suitable for retaining the flap portion 14 over the edge portion 38 in order to provide a water resistive barrier between the abutting sections of low-E housewrap materials.
Turning to FIGS. 6 and 7 , a protective film is removed to expose the adhesive strip 18 in preparation for securing the flap portion 16 over the edge portion 38 . The flap portion 16 is contacted to the adhesive strip 18 and secured over the edge portion as illustrated in FIG. 8 . This assembly serves to provide a water resistive barrier between two abutting sections of low-E housewrap materials of the present invention to effectively seal their respective edges and allow water runoff from one low-E housewrap material section to another low-E housewrap material section.
A bottom view vantage point of abutting low-E housewrap materials is illustrated in FIGS. 9-10 . Again, the first section 10 of low-E housewrap material is positioned near the second section 12 of low-E housewrap material. The flap portion 16 of the second section 12 of low-E housewrap material is disposed over an edge portion 38 of the first section 10 of low-E housewrap material. Edge portion 38 may include an adhesive strip 18 for retaining the flap portion 16 thereon. As a sufficient force is applied, for example, to flap portion 16 to contact the adhesive strip 18 , the flap portion 16 is held in retention over the edge portion 38 as shown, for example, in FIG. 11 . It is clear from FIG. 11 that, in a final assembly arrangement, a foam edge portion 56 of a first low-E housewrap material 10 abuts a foam edge portion 58 of a second low-E housewrap 12 . Accordingly, the assembled sections serve to provide a water resistive barrier between two abutting sections of low-E housewrap materials of the present invention.
In order to improve the energy efficiency of new and existing building structures, application of the herein described low-E housewrap serves to cover the exterior wall sheathing with an infiltration barrier, for example, prior to installation of a covering material or exterior finish such as siding, brick, stone, masonry, stucco and concrete veneers, for examples. The herein described low-E housewrap also serves to protect against air infiltration and damaging moisture build-up. Air infiltration may occur in typical construction through, among other places, sheathing seams and cracks around windows and doors. Moisture build-up can occur externally in the wall cavity from, for example, leaking exterior finishes or coverings, and cracks around windows and doors. The low-E housewrap of the present invention does not trap the water, but rather allows it to flow downward so as to exit the wall system.
Installation procedures of the presently described low-E housewrap include those as described, for example, in the technical manual for ESP Low-E® Housewrap utilized on exterior walls and under a primary barrier. The technical manual for ESP Low-E® Housewrap is submitted herewith and is hereby fully incorporated herein by reference. Turning to FIG. 12 , an exemplary exterior wall assembly 40 is constructed and prepared for receiving the low-E housewrap material of the present invention. In the illustrated example, a window opening 42 is shown. In a preferred embodiment, the low-E housewrap is employed after the walls have been construction and all sheathing and flashing details have been installed. The low-E housewrap material is preferably applied before doors and windows have been set inside framed openings and prior to the installation of the primary wall covering.
Turning to FIG. 13 , a first low-E housewrap material is applied to the wall assembly 40 . The reflective side of the low-E housewrap material is installed facing outwardly. In one preferred embodiment, a roll of low-E housewrap material is unrolled horizontally starting at the corner of a preferred exterior wall 40 . The flange side or flap portion (e.g., 14 , 16 of FIG. 1 ) of the roll is installed facing downwardly. The low-E housewrap material is secured to the exterior wall with fasteners 48 such as staples or cap nails (or any other suitable fasteners) at preferably every 8-12″. When applying another horizontal run of low-E housewrap material 44 , the foam ends of each applied section of rolled low-E housewrap material abut together such that the flange 52 of the additionally applied low-E housewrap material 44 is allowed to overlap the outside edge 50 of the adjacent low-E housewrap material 46 . This installation ensures that any intruding water is encouraged by the drainage plane (e.g., 24 of FIG. 2 ) to flow downwardly.
In a preferred embodiment, the flange 52 is installed to overlap the abutting foam edge by approximately 2″. The low-E housewrap material is installed to extend over all of the sill plates by a minimum of approximately 1″. The vertical and horizontal seam areas are sealed with suitable low-E foil tape. The low-E housewrap material may be trimmed around each framed opening with additional appropriate detailing applied as per window/door manufacturer and/or code standards.
Once installed, an appropriate exterior covering may be applied/installed over the low-E housewrap. Such covering may include, but not limited to, siding, brick, stone, masonry, stucco and concrete veneers. The utilization of the herein described low-E housewrap provides, inter alia, a protective wrap that not only improves energy efficiency in accordance with newly implemented industry-wide energy/code regulations, but enhances drainage of damaging moisture build-up while protecting against air infiltration.
Moreover, other implementations of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. Various aspects and/or components of the described embodiments may be used singly or in any combination. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims. | 4y
|
This application is a continuation in part of PCT/US92/08462, filed Oct. 2, 1992, which is a continuation in part of U.S. Ser. No. 07/791,821, filed Nov. 13, 1991, now U.S. Pat. No. 5,169,443.
This invention relates to novel mechanically delaminated kaolin clay pigments especially useful for coating lightweight printed paper. In particular, the invention relates to delaminated kaolin coating pigments which possess a unique combination of desirable properties not possessed by other kaolin pigments.
Kaolin clay pigments are obtained from kaolin crudes. The crudes contain kaolin particles, oversize (grit) and fine and coarse particle size impurities. Some impurities (e.g., fine ferruginous or titaniferous impurities) impart undesirable color to the clay. Other impurities have an undesirable effect on the rheology of the kaolin.
The kaolin portion of kaolin crudes is "polydisperse" in the sense that the particles occur over a range of sizes and shapes. Thus, a kaolin crude will not contain particles of a single size, such as, for example, particles all of which are 2 micrometers. Typically a degritted kaolin crude will contain particles ranging in size from sub-micron or colloidal to particles 20 micrometers or larger.
Kaolins from different ores, or even from different zones in the same deposit, can vary widely in the content of impurities, particle size distribution, and the morphology of the kaolin particles. In general, kaolin particles finer than about 2 micrometers are composed of individual platelets, and particles larger than about 2 micrometers are composed of stacks or booklets of finer particles. Particle sizes of kaolins are conventionally determined by sedimentation using Stokes law to convert settling rates to particle size distribution, and assume a spherical particle shape for the kaolin particles. Hence, the use of the conventional term "equivalent spherical diameter (e.s.d.)" to designate particle size.
Kaolin clay pigments are widely used to coat and to fill paper products and they are also used as functional fillers in paints and plastics. Such pigments are available in a large number grades, the selection of which by the user is determined by price and performance. It was formerly the practice simply to use relatively coarse kaolins to fill papers and to employ finer grades of kaolin to coat paper. In paper the coarser kaolin fillers functioned primarily as pulp extenders. When used to coat paper, the finer kaolin pigments improved opacity and provided a smooth, ink-receptive surface and gloss which improved print quality and aesthetic appearance.
It has long been recognized in the industrial minerals industry that mechanical delamination of kaolin stacks present in the coarse particle size fractions of many kaolin crudes provides kaolin pigments with improved opacification as well as enhanced smoothness in paper coating. See, for example U.S. Pat. No. 3,171,718, Gunnet al.
During mechanical delamination, large kaolin particles are disaggregated into smaller particles having a higher aspect ratio, principally by parting clay crystals along basal cleavages. It has also been recognized that a relative narrowing of the particle size distribution of mechanically delaminated as well as non-delaminated kaolin particles results in pigments providing improved opacity and smoothness to paper along with improved printability. Such pigments are disclosed as being especially advantageous when used in the manufacture of lightweight coated paper for rotogravure printing (see GB 2,058,734). The characteristics of delaminated pigments are particularly beneficial in the coating of ground wood- containing paper basestock, which is typically of substantially lower uncoated sheet brightness and of rougher surface than chemical wood-free basestock.
Delaminated pigments in clay-water slurries and in paper coating color formulations have however, had substantially poorer high shear rheological characteristics (higher viscosity) than undelaminated pigments. Superior rheology in coating color formulations permits the paper coating equipment to run at higher speeds (which directly increases the productivity of existing coating equipment) or permits the formulation of coating colors at higher solids (thus reducing drying time and hence increasing the efficiency of drying equipment). Thus, with the use of conventional delaminated pigments, papermakers must balance the tradeoff between paper opacification (quality) and efficiency of production (productivity).
Coating color viscosity is a key issue with paper coaters facing capacity constraints. A clay-water slurry that has equivalent viscosity to a comparable slurry at only 2-3% higher pigment solids represents an improvement of significant commercial importance.
Generally, paper makers seek to use clay coating pigments capable of forming clay-water slurries at 67-70% solids which have a low shear viscosity below 1000 cp, preferably below 500 cp, when measured by the Brookfield. Viscometer at 20 rpm. High shear viscosity for these slurries should be such that they are no more viscous than a slurry having a Hercules endpoint viscosity at 16×10 5 dyne-cm of 500 rpm, preferably 800 rpm, using the "A" bob. Those skilled in the art are aware that when using the Hercules Viscometer and measuring endpoints of 1100 rpm or higher, viscosity is reported in units of dyne-cm at 1100 rpm. It is conventional to use the abbreviated term "dyne". A "2 dyne" clay slurry is less viscous than a "9 dyne clay" slurry at a given solids level.
Kaolin pigments produced by mechanical delamination are currently commercially made and marketed as delaminated pigments by various producers with processing facilities located in Georgia and South Carolina, using as raw material sources the Cretaceous and Tertiary kaolin deposits of the region. However, none of the commercially available delaminated kaolin pigments have the unique desirable combination of high opacification and the low viscosity characteristic of some underlaminated pigments.
SUMMARY OF THE INVENTION
We bare developed, and the invention provides, kaolin pigments which possess the opacification, smoothness, and printability advantages of delaminated kaolin pigment with narrow particle size distribution and with high and low shear viscosities that provide paper-makers with productivity enhancements. Kaolin pigments according to the invention can be especially useful for high-speed coating of lightweight ground wood paper.
We have also ascertained the characteristics for kaolin crudes which result, on delamination of the crudes, in kaolin pigments having such improvement of combined properties. We have also identified specific kaolin crudes, available for example from Georgia, USA, the Rio Capita area of Para, Brazil and Manaus, Amazonas, Brazil, which are capable of providing delaminated kaolin pigments having both desirable low viscosity not normally associated with delaminated pigments and desirable optical properties of opacification normally associated with coarse particle size delaminated kaolin pigments, and sometimes also desirable optical properties of gloss not normally associated with delaminated pigments.
The present invention provides kaolin pigments comprising delaminated kaolin particles and possessing the following distinguishing combination of properties or characteristics:
Particle Size (weight percent finer than stated equivalent spherical diameter, e.s.d., as measured by Sedigraph)
At least 95% finer than 10 micrometers
37% or less finer than 0.5 micrometers
12% or less finer than 0.2 micrometers
Median particle size: at least 0.70 micrometers ##EQU1## Surface Area of 12.5 m 2 /gm or less (BET method using N 2 as adsorbate)
Viscosity
Brookfield viscosity, measured at 20 rpm [#2 spindle] and 67-68% solids: 175 cp or less and, most preferably, Brookfield viscosity, measured at 20 rpm [#2 spindle] and at 100 rpm [#2 spindle] at 72% solids: 300 cp or less
Hercules viscosity, measured at 1100 rpm [A-bob] and 67-68% solids: dyne endpoint
Opacity and gloss (as measured by black glass)
scatter coefficient at 457 nm: ≧100.0 m 2 /Kg
scatter coefficient at 577 nm: ≧80.0 m 2 /Kg
gloss: preferably at least 75%
Other aspects of the invention comprise aqueous paper coating compositions containing the pigment of the invention with organic binder,and paper webs coated with kaolin pigments of the invention.
The invention further provides a method of making a hydrous kaolin pigment which comprises delaminating degritted minus 325 mesh ( i.e. minus 0.044 mm) kaolin crude having the following characteristics:
(1) Particle Size (e.s.d. as determined by Sedigraph)
(a) % less than 2 microns: 40-65%
% less than 0.2 microns: ≦12%, preferably ≦5% ##EQU2## (2) Surface Area: 12.0 m 2 /gm or less (BET method using N 2 as adsorbate).
(3) Structural Order
(a) Hinckley Index: ≧0.90, indicating a high degree of overall structural order
(b) C-axis crystal coherence - Full-Width-Half-Maximum measure of (001) peaks
FWHM (001) ≦0.26, indicating thick, well-formed, coherent crystal lites--the basic diffracting unit of the crystal structure (Plancon et al, 1988)
(4) Cation Exchange Capacity - measured by Na + adsorption at pH 4.0 on non-dispersed minus 325 mesh crude: ≦0.05 microequivalents/m 2 .
Delaminated kaolin pigments according to the invention have been produced from Rio Capim and Manaus crudes, and those crudes and appropriate crudes from Georgia and elsewhere can be used in the methods according to the invention. The kaolin crude of the above characteristics used as a bulk feed in the method of the invention may be a whole crude or a fractionated crude or a mixture of whole or fractionated crudes or both. It is a feature of this invention to terminate delamination when the predominant proportion of booklets have been parted by mechanically induced shearing along basal (001) cleavages into discrete platelets, but prior to onset of undesired significant attrition of the platelets. The point at which to terminate delamination is generally determined by calculating the rate of change in the particle size distribution at particular particle size control points versus residence time in the delaminator, and ceasing delamination when the rate of change approaches zero, and/or when an increase in the percentage of very fine particles (e.g. less than 0.3 microns) is noted. The said particle size control points could for example be one or more or all of those used above in definition of pigment according to the invention (10, 0.5 and 0.2 micrometers), or particle sizes from a similar range.
DESCRIPTION OF PREFERRED EMBODIMENTS
The following chart summarizes the physical characteristics of seven coarse kaolin crudes, including crudes that meet the criteria and will make products of the invention as well as those that fail to meet the criteria or make products of the invention.
Crudes 1, 4, 5, 6 and 7 are kaolins sampled from various kaolin deposits in central Georgia, USA, and crudes 2 and 3 are kaolin crudes from the Amazon region of Brazil. Crudes 1, 2 and 3 satisfy all of the criteria of required physical characteristics for use in the methods according to the invention; products of the invention have been made from crudes 2 and 3.
In this chart, the viscosity characteristics are proxied by fluidity which denotes maximum solids achieved at optimum dispersion with a Brookfield value of 300 cps. All values reported are for de-gritted, minus 325 mesh crudes with the exception of the structural order characteristics, which are measured on whole crude.
______________________________________CRUDE 1 2 3 4 5 6 7______________________________________Fluidity 77.9 76.6 73.6 68.7 67.4 62.5 64.1(solids@ 300 cps)Surface Area(BET, N.sub.2)SA (m.sup.2 /g) 9.3 8.5 10.8 11.9 16.4 14.6 13.2Particle SizeDistribution5 μm (% finer) 73.3 76.0 72.0 75.5 76.9 78.9 60.92 μm (% finer) 54.2 55.0 51.0 54.2 56.9 61.2 43.21 μm (% finer) 39.5 40.4 32.0 42.4 43.6 48.5 31.80.5 μm (% finer) 16.6 23.3 10.5 25.3 28.1 31.7 20.70.2 μm (% finer) 1.4 10.3 0.0 6.3 8.4 11.1 7.0 ##STR1## 3.26 2.36 4.86 2.14 2.0 1.9 2.1Structural OrderHinckley Index 1.07 1.06 1.05 .62 .68 .55FWHM "001" .25 .25 .22 .29 .25 .30Cation ExchangeCapacity(micro-equivalents/m.sup.2)pH 4 .03 .06 .80 1.00 .09______________________________________
A typical prior commercial delaminated pigment from a Georgia producer will have the following characteristics:
Particle Size
79% finer than 2 micrometers
Distribution (weight % finer than e.s.d.) 63% finer than 1 micrometers
43% finer than 0.5 micrometers
16% finer than 0.2 micrometers ##EQU3##
Median Particle Size: less than 0.65 micrometers
Surface Area 15.0 m 2 /g
Viscosity
Brookfield: 275 cp @20 rpm @68% solids
>300 cp @20 rpm @68-69% solids
Hercules endpoint: 600 rpm @68% solids
Black glass
scatter coefficient at 457 nm: 100 m 2 /Kg
scatter coefficient at 577 run: 75 m 2 /Kg
gloss: 68%
Some commercially available kaolin pigments marketed as delaminated pigments will exhibit better viscosity than is indicated above. These pigments may have dyne-endpoint high shear viscosity at 68% solids. However, these particular pigments will be finer than the products of the invention and the above typical delaminated pigment, as measured by a higher surface area and the higher weight percentage of kaolin particles finer than the 0.5 micrometers and 0.2 micrometers control points while the presence of fine kaolin particles improves the high shear viscosity of delaminated kaolin pigments, the presence of fines concomitantly reduces the scattering efficiency and opacification of the pigments, as quantified by a reduction in the black glass scatter coefficients of the "good" viscosity pigment below those values for products of the invention. For example, the "best" viscosity, commercially available delaminated pigment tested had the following characteristics:
Particle Size (weight % finer than e.s.d.)
98% finer than 5.0 micrometers
81% finer than 2.0 micrometers
67% finer than 1.0 micrometers
50% finer than 0.5 micrometers
21% finer than 0.2 micrometers
Median Particle Size 0.50 micrometers ##EQU4## Surface Area 16.9 m 2 /g Viscosity
Hercules viscosity, measured at 1100 rpm (A bob) and 68% solids: 15.9 dyne
Brookfield viscosity, measured at 20 rpm (#2 Spindle) and 68% solids: 290 cp
Black Glass
Scattering coefficient at 457 run: 67 m 2 /kg
Scattering coefficient at 577 nm: 43 m 2 /kg
gloss 71%
While the good high shear viscosity characteristics of this commercially available pigment, marketed as a delaminated pigment, will be perceived as advantageous, the comparatively low black glass scatter coefficients will be perceived by the papermakers as a reduction in paper and print quality, particularly in lightweight papers.
Products of the invention possessing the characteristics set forth in the accompanying claims have been made by various techniques, all involving the step of mechanically delaminating kaolin crudes or fractions of crudes, e.g. from the Rio Capim river basin, Para State, Brazil. The Rio Capim kaolins are contained within an extensive sedimentary formation containing coarse and fine sands, clays and silts. The near-surface clay bearing members have been preserved from erosion in plateau tops. The clay members appear to be stratigraphically flat-lying, with high brightness kaolin horizons occurring underneath variously superficial laterites, sands, and discolored kaolins not suitable for processing. Underneath this waste material, typically there is an horizon of high brightness, low sand content kaolin which is an acceptable source material for products of the invention. In the northern portions of the Rio Capim kaolin district, in the vicinity of Igarape Cipoteua, the crudes can be described as coarse, with the -325 mesh [U.S. sieve] fraction typically having a cumulative particle size distribution of:
______________________________________Weight percent finer than Range Average______________________________________2.0 micrometers 72-39% 58%1.0 micrometers 55-25% 40%0.5 micrometers 34-8% 20%0.2 micrometers 13-1% 6%______________________________________
Further to the south, in the vicinity of Igarape Cupijo, the -325 mesh fraction of the crude kaolin is typically finer, averaging 75% finer than two micrometers and 60% finer than one micrometer.
Those skilled in the art know that the use of sedimentation to determine particle size of the thin platelets of mechanically delaminated kaolins results in values that do not truly reflect the size of thin flat plates. Inspection of micrographs (SEM) of the degritted -325 mesh crudes used in the practice of this invention indicate that, numerically, most of the discrete kaolin particles consist of crystals having 1 to 2 micrometers face diameter and less than 0.5 micrometers edge thickness. Those skilled in the art refer to particles of this size and crystal form as platelets. Typically the platelets in a suitable crude will have at least one well-formed straight edge, and occasional crystals will have six well-formed edges in a pseudohexagonal crystal habit. The coarseness of kaolin particle population is imparted by the kaolin crystals referred by those skilled to in the art as books and large plates. Books are stacks of kaolinite layers. In well-formed crystals the perfect, regular basal cleavage of kaolinite with straight edges at 60 degree angles are readily apparent. Typically the books in crudes used in practice of the invention can be described as roughly equant, on the order of 15 micrometers by 15 micrometers in size. Occasionally, books will develop the vermiform habit wherein the dimension perpendicular to the basal cleavage will be upwards of 40 micrometers in length, often curving at one end of the crystal. Another crystal habit is known as the plate wherein the face diameter is 10 to 15 micrometers and the thickness (the direction perpendicular to the basal cleavage) is on the order of 0.5 micrometers. Plates typically will have less well-formed edges than books.
In the Rio Capim, the degritted kaolin crudes from the "coarser" northern portion of the area appear to have a greater proportion of books and plates relative to platelets than in the "finer" southern area.
Typically the crude is initially crushed and then blunged in water, preferably containing a clay dispersant, such as, for example, a mixture of soda ash and sodium silicate, or a condensed phosphate salt, e.g., tetrasodium pyrophosphate or sodium polyacrylate. Generally, solids of the blunged clay are in the range of 30% to 65%, usually about 40% by weight. The blunged clay is then degritted by known means such as the use of screens or gravity settling to remove oversize (grit). Suitable for this purpose are 200 or 325 mesh ,U.S. Standard (0.074 and 0.044 mm) screens.
In an embodiment of the invention, the degritted slip of kaolin is then separated into one or more coarse and fine size fractions, the finer fraction being, for example, 70 to 90% by weight finer than 2 micrometers. Continuous centrifuges such as those equipped with nozzle bowls or scrolls can be used or gravity settling can be employed for fractionation. Excellent results were obtained with the crude used in an illustrative example by operating the centrifuge to remove and then isolate a fine size fraction of which about 90% by weight of the particles were finer than 2 micrometers and a coarse fraction which was about 25% by weight finer than 2 micrometers. The coarse size fraction remaining after centrifugation to separate the fines is employed as delaminator feed optionally along with a portion of the fines separated during centrifugation and/or a portion of degritted feed. When a fine fraction is separated in the first classification step, the population of particles of the delaminator feed contains of a higher proportion of large kaolin books and plates than occurs in the population of kaolin particles in the kaolin slip prior to classification. Fines and/or feed are included in delaminated feed primarily to control the particle size distribution of the mechanically delaminated product. See Example 2.
In another embodiment of the invention, the degritted slip is subjected to delamination without an intervening particle size classification. This operation is referred to as "whole fraction delamination". See Example 1 and Example 3.
It is preferred in this invention to terminate the delamination when delamination is essentially complete and attrition of finer than 5 micron platelets begins to occur. The onset of undesired attrition may be controlled by determining the increase in the particle size fraction finer than a particular e.s.d. (e.g., 5.0 and 2.0 micrometers). Duration and intensity of delamination varies, depending on the source of crude, the blend of coarse and fine particle fractions in the delaminator feed, and the desired particle size distribution of the product.
The process of delaminating the clay can be practiced using fine milling media in a batch operation but is advantageously carried out in a continuous manner. Nonlimiting examples of milling media are small ceramic balls, coarse sand, plastic cylinders, beads, or pellets of nylon, styrene-divinyl benzene copolymer, polyethylene or other plastic. The medium acts upon a suspension of the clay in water.
Most preferably, the milling medium is minus 20 plus 50 mesh (US sieve) styrene divinyl benzene copolymer beads. Generally the volume of beads to clay slurry varies between 20-70%, most preferably between 35% and 50%. The clay feed to the process should typically be controlled between 20% to 50% solids; however, optimum processing conditions are often achieved between 35 and 45% solids.
A suitable vessel used for the process contains vertical baffles and typically has a height to diameter ratio greater than 1.0 and optimally 1.5 to 2.0. Such a vessel is equipped with an agitation system containing multiple agitator elements attached to a vertical shaft. The number and spacing of the agitators must be optimized for the specific process conditions in order to impart the necessary combined shear and percussive and frictional energy input necessary to overcome the Van der Waals forces holding individual platelets in a stacked array. Energy input required for delamination will vary due to differences between crudes, process conditions, and equipment; typically requiring 10 to 50 horsepower-hour per ton of clay charged to the delaminators.
In continuous delamination, the clay is fed continuously into a delaminating apparatus and the discharge from the apparatus is advantageously combined with a fractionation of the clay, returning the coarser clay to the apparatus while removing only the finer clay of the desired particle size. The selective takeoff of finer clay, while returning the coarser clay to the vessel in which the delamination is taking place, has the advantage that the overall process yield can be improved and plates greater than 5 micrometers face diameter can be fractured to meet the desired particle size attributes. In this manner, the clay remaining in the apparatus during the continued operation is made up mainly of the coarser clay particles which are undergoing delamination and which are continuously freed from finer clay particles by the selective draw-off and fractionation and return of coarser clay particles.
In this continuous withdrawal of clay suspension, separation of finer clay and return of coarser clay to the apparatus is also advantageously continuous, and can be accomplished by subjecting the withdrawn clay to a centrifugal separation with return of the coarser clay to the apparatus, or by the use of one or more cyclone separators which will separate the finer clay fraction and return the coarser clay to the apparatus.
The slip of delaminated clay is then optionally centrifuged to remove oversize, e.g. particles larger than 2 micrometers, as an underflow and the overflow product is then passed through a high intensity magnetic separator, followed by bleaching, filtration and drying to produce product of the invention. The centrifuged underflow containing oversize may be blended with appropriate levels of delaminated and/or undelaminated clay to achieve blends of desired particle size distribution and further processed in a conventional manner, e.g. magnetic purification and/or bleaching, to produce other advantageous kaolin products.
The fine particle size fraction separated from the coarser kaolin in the first classification step (prior to delamination) may be processed in a conventional manner, e.g., magnetic purification and/or bleaching, to produce No. 1 or No. 2 grade coating clays.
As mentioned, it is within the scope of the invention to delaminate the degritted slip without first fractionating the slip. It is also within the scope of the invention to delaminate with grinding media other than plastic beads, e.g., by sand, zircon or glass beads or by the delamination process known as "superstrusion".
Delaminated kaolin pigments of the invention can be advantageously used as the single pigment in coating color formulations used to coat paper and paper board. However, it is also within the scope of the invention to employ pigments of the invention in blends with other kaolin and non-kaolin pigments, and to use the blends to coat paper and paperboard. Such blends may be produced prior to the preparation of coating color formulations or produced concomitant with the preparation of coating color formulations.
Delaminated pigments are particularly advantageous when used as the single pigment to coat ground wood-containing lightweight paper. A typical ground wood containing lightweight paper basestock, suitable for coating, may have the following characteristics:
Basis weight: 24 lbs/3300 ft 2 or 36 g/m 2
Brightness: 67.5%
Opacity: 76%
In preparing coating color formulations, coating pigments are admixed in a conventional manner with other constituents and binders, materials that bind the coating pigments to the paper basestock surface. Coating color formulations will vary from mill to mill for the same end- use application, and will differ on the basis of the surface characteristics required by different printing methods commonly used. For example:
______________________________________Typical Light Weight Coated Paper - Coating FormulationsOffset Paper Rotogravure Paper______________________________________Europe100 pts pigment 100 pts pigment10 pts Dow 685 4.8 pts Acronal.sup.R 5485 pts PG280 0.5 pts Nopcote.sup.R C-1040.5 pts Nopcote.sup.R C-1040.5 pts Sunrez.sup.R 700CUnited States100 pts pigment 100 pts pigment8 pts PG280 7 pts PG2808 pts CP640 A 4 pts CP620 A0.5 pts Nopcote.sup.R C-104 5 pts Nopcote.sup.R C-1040.5 pts Sunrez.sup.R 700C______________________________________ pts = parts
All particle sizes used in the specification and claims are determined with the SEDIGRAPH 5100 particle size analyzer and are reported as equivalent spherical diameters (e.s.d.) on a weight percentage basis.
Light scattering and gloss were determined by coating the kaolin clay suspensions at 60% solids onto black glass plates at a coat weight of 7.0-14.0 g/m 2 (expressed as dry clay). The reflectance of the coatings, after drying in air, is measured at wavelengths 457 nm and 577 nm by means of an Elrepho reflectometer. The 457 nm wavelength corresponds to the wavelength used in the TAPPI brightness measurement and the 577 nm wavelength to that used to measure opacity. The reflectance values are converted by the use of Kubelka-Munk equations to light scattering values (m 2 /Kg). The light scattering values are a measure of the opacity potential of the clay. The higher values indicate that light, rather than passing through, is reflected and scattered back. The higher the light scattering value, the higher the opacity potential of the clay. The black glass gloss value is a measure of specular gloss at 75 degrees (15 degrees from the plane of the paper), and is widely used as a particle measure of surface quality and shiny appearance (which is conventionally equated with high quality). In many applications, high gloss values are desirable.
In preparing slurries for measurement of high shear (Hercules) and low shear (Brookfield) viscosity, Engelhard Corporation procedure PL-1 was used. Brookfield viscosity was measured using TAPPI procedure T648 om-88 at 20 rpm using the #1 or #2 spindle; in some cases Brookfield viscosity was measured at 100 rpm using the #3 spindle. All slurries were formulated with optimum amount of dispersant, following the PL-3 procedure of Engelhard Corporation. Descriptions of PL-1, PL-3 and Hercules viscosity measurement procedures appear in U.S. Pat. No. 4,738,726.
In the examples which follow, references are made to pigment brightness, which was determined in the conventional manner (TAPPI standard T452 m - 58) using a G. E. Brightness meter.
In Examples 1 & 2 which follow, the kaolin clay crudes were obtained from deposits of the northern portion of the Rio Capim river basin of Para, Brazil. In Example 3, the kaolin crudes were a bulk sample obtained from deposits approximately 75 kilometers due north of Manaus, Amazonas, Brazil.
EXAMPLE 1
Whole Fraction Delaminated Products
This example demonstrates the embodiment of the invention in which a degritted slip of kaolin is subjected to mechanical delamination without first fractionating the slip (whole fraction delamination). The kaolin slip used as feed in the process was a sample of Capim kaolin, described above. The slip was prepared by blunging kaolin crude (pH 4.4) in water containing sodium polyacrylate (C211 brand) and soda ash as a dispersant, resulting in a slurry having a pH of 8.2 The slip was degritted in two stages, the first involving allowing the slip to remain quiescent (settle) for 5 minutes and then passing the nonsettled portion through a 200 mesh screen. The degritted slip at about 39% solids contained about 86% of the starting crude. Particle size of the recovered kaolin was 54% finer than 2 micrometers. Brightness was 81.3%; TiO 2 and Fe 2 O 3 were 1.08% and 0.71%, respectively.
Delamination was carried out in a pilot plant delamination simulator which consists of a stainless steel vessel nominally 10" ID by 15" high. Within the vessel are three vertical baffles approximately 1/2" wide extending the length of the vessel. The agitation system utilizes three ceramic cones mounted in a turban array where two or more cones can be mounted on the vertical shaft. The power for the vessel is provided by a 3/4 HP drill press with variable speed control. In this vessel, approximately 2.5 gallons of clay slip are delaminated per batch utilizing the necessary bead volume ratio of styrene divinyl benzene copolymer to achieve optimum results. In this example, bead volume was 50% and residence time of the slip in the delaminator was 55 minutes. Bead size was minus 20 plus 50 mesh (US sieve), and shape was spherical.
Particle size of the delaminated product was about 70% finer than 2 micrometers. Brightness was 81.9%. TiO 2 and Fe 2 O 3 analyses were 1.08 and 0.72%, respectively, indicating that kaolin was not brightened during delamination. Solids of the delaminator discharge was 19.2%.
In one case the delaminator discharge was then charged to brightness enhancing equipment, described below, resulting in a finished Product A with 70% of the kaolin particles finer than 2 micrometers. In another case, the delaminator discharge was charged to a Sharples centrifuge which divided the slip into Product B, a fine fraction of 80% finer than two micrometers (77.3% yield and 19.2% solids), and a coarse reject fraction.
For both products A and B, the delaminated kaolin was then charged to a conventional high intensity magnetic separator using various throughput rates in order to remove colored paramagnetic impurities and thereby improve brightness. Prior to magnetic treatment the brightness of the feed kaolin was 82.3%; TiO 2 and Fe 2 O 3 were 1.13 and 0.70%, respectively. The pilot plant High Insensity Magnetic Separator is fitted with a 1" ID ×20" high canister containing approximately 100 pads of 430 stainless steel. Space velocity calculations are utilized to simulate equivalent processing conditions for commercial scale HIMS units. Typically, commercial scale units have canisters of 84 or 120 inch diameter ×20 inch high matrix. An important consideration in plant scale-up is the performance of a process under varying capacities. Thus, in order to simulate future scale-up requirements space velocities are varied typically to simulate production capacities of 20 to 40 tons per hour utilizing an 84" HIMS unit. At throughput rates between 20 and 40 tons per hour, products having brightness in the range of 87.7 to 88.4% were produced. Those skilled in the art will recognize that the 5-6 points increase in brightness as a result of magnetic separation treatment was unusually high; typical Georgia kaolins experience an increase in brightness of only 1 to 3 points by treatment in conventional high intensity separators.
Brightness of all magnetically purified products was further significantly increased by floccing the slip of magnetically purified kaolin with 6#/T aluminum sulfate (4.7 pH), treatment with a conventional sodium dithionite bleach reagent, followed by filtration and viscosity measurement. Brightness results for runs at various magnet throughput rates and bleach levels are reported below in table form for the 80% finer than two micrometer product. (The 70% finer than two micrometers product responded similarly)
______________________________________Brightness of Delaminated Beneficiated Kaolin ProductsBleach Magnetic Through-Put tons/hour)#/T 0 t/hr 20 t/hr 30 t/hr 40 t/hr______________________________________ 0 82.3 88.4 87.8 87.8 7 84.2 89.6 89.4 88.810 85.0 89.6 89.4 89.113 84.7 89.6 89.5 89.2______________________________________
The characteristics of the two products A and B of this example:
______________________________________ A B______________________________________Particle Size% finer than 10 micrometers 98 100% finer than 5 micrometers 92 98% finer than 2 micrometers 72 80% finer than 1 micrometers 52 60% finer than 0.5 micrometers 28 32% finer than 0.2 micrometers 7 6Median Particle Size .94 .77 ##STR2## 2.57 2.50Surface Area m.sup.2 /g 10.6 11.5ViscositySolids % 67.0 67.0Brookfield #2@ 20 rpm 97 cp 76 cp@ 100 rpm 77 cp 71 cpHercules @ 1100 rpm 5 dynes 5.2 dynes______________________________________
Example I
Whole Delaminated Products Continued
Products of the invention, A and B, and two commercially available high aspect ratio delaminated kaolin products C and D, made from Georgia, USA and Cornwall, United Kingdom kaolin crudes, respectively, were admixed in a conventional manner with binders, commonly used in Europe for rotogravure paper in the following formulation:
______________________________________Coating Formulation______________________________________Pigment 100Acronal 548 4.8Nopcote C-104 0.5______________________________________
The admixtures, commonly referred to as coating colors, were tested for viscosity in a conventional manner:
______________________________________ Product A B C D______________________________________Solids (%) 59.4 59.2 59.2 55.6pH 9.5 9.6 9.5 9.8Brookfield (cps) 20 rpm 2070 2140 3510 7220100 rpm 672 678 1064 2176Spindle #4 #4 #4 #54400 H.E.P. "E" 20.4 22.4 25.0 19.6______________________________________
Note that commercially available product D has substantially worse rheology as it is measurable in this formulation at 3.5% lower solids than products of the invention A and B and commercially available product C. At the same solids level, products of the invention A and B have superior viscosity to commercially available product C.
The coating color was then applied to a European base sheet suitable for rotogravure printing applications. The following coated sheet and print properties were measured:
______________________________________EUROPEAN LWC ROTOGRAVURECoated Sheet Properties Product A B C D______________________________________Brightness (%) 74.0 74.2 73.6 73.6Opacity (%) 86.3 86.5 85.8 85.5Gloss (%) 49 54 48 43Heliotest (mm)@ 25 Kg/f 22 25 19 18@ 30 Kg/f 48 67 52 42PPS 1.19 1.10 1.28 1.27______________________________________ Properties shown at 5.5 lb/3300 ft.sup.2 Calendar Conditions: 1 nip at 2000 psig and 140° F.
In each of these measures of desirable coated sheet optical properties and printability, the products of the invention A and B are equivalent to or superior to the commercially available products C and D.
Samples of product A, B, C, D as described above were admixed with binders typically used in European LWC formulations;
______________________________________Coating Formulation______________________________________Pigment 100Dow 685 10PG 280 5Nopcote C-104 0.5Sunrez 700C 0.5______________________________________
Viscosity measurements of the four coating colors were then taken in a conventional manner with the following result:
______________________________________EUROPEAN LWC OFFSETCoating Color Properties Product A B C D______________________________________Solids (%) 58.1 58.1 58.0 58.3pH 8.5 8.5 8.5 8.5Brookfield (cp) 20 rpm 840 940 1490 2100100 rpm 320 330 534 760Spindle #4 #4 #4 #44400 H.E.P. "E" 15.0 15.2 24.8 26.0______________________________________
The coating color formulations A, B, C, D were applied to a European base sheet suitable for light weight coated offset applications. Coated sheet and print properties were measured in conventional manner with the following results:
______________________________________EUROPEAN LWC OFFSETCoated Sheet Properties Product A B C D______________________________________Brightness (%) 71.4 71.7 70.9 70.9Opacity (%) 81.6 81.6 80.7 80.6Gloss (%) 55 59 56 49Print Gloss (%) 79 81 79 79o.d. = 1.6Print Through 79 79 79 79Resistance (%)o.d. = 1.6IGT pick (vvp) 35 33 32 33K&N (%) 21 22 20 18PPS 1.13 1.06 1.08 1.16______________________________________ Properties shown are at 5.5 lb/3300 ft.sup.2 Calendar conditions: 4 nips, 2000 psig. 140° F.
Thus, in a European LWC offset application, products of the invention A and B demonstrated better coating color high and low shear viscosities than commercially available products C and D, and have equivalent to slightly superior optical and printability characteristics.
EXAMPLE 2
Delaminated Products From Coarse Particle Size Fractions Of Crude
This example illustrates the production of a mechanically delaminated clay product of the invention from a coarse particle size fraction of crude and a by-product No. 1 grade product.
The crude was blunged in water at 40% solids, resulting in a pH of 4.4. To facilitate subsequent processing the slurry was dispersed by adding soda ash (2 pounds per ton) and N R Brand sodium silicate solution (4 pounds per ton), resulting in a pH of 8.4.
The dispersed slurry was degritted by allowing it to settle for 5 minutes and then passing the nonsedimented portion through a 200 mesh screen (U.S. Standard) to remove grit. The size of the kaolin in the minus 200 mesh (degritted) slip was 54% by weight finer than 2 micrometers. Brightness was 82.6%. Chemical analysis was 0.90 weight % TiO 2 and 0.58% Fe 2 O 3 .
The degritted slip at 32.7% solids was then divided in a Sharples centrifuge into a fine fraction (93% finer than 2 micrometers at 20.,6% solids) and a coarse fraction (22% finer than 2 micrometers).
To the coarse centrifuge underflow fraction (22% finer than 2 micrometers) there was added a portion of the fines (93% finer then 2 micrometers) and a portion of degritted feed (54% finer than 2 micrometers) to produce a delaminator charge have a desired particle size of about 51% minus 2 micrometers. The blend of clays charged to the delaminator had a brightness of 82.8% and analyzed 0.90% TiO 2 and 0.63% Fe 2 O 3 .
The resulting blend of dispersed clays at 42.6% solids was then subjected to mechanical delamination in a pilot plant delamination simulator, described in the previous example, in a batch operation for 11/2 hours using minus 20 plus 50 mesh spherical styrene - divinyl benzene co-polymer beads; bead volume was 35% during delamination. Particle size distribution of the delaminated product was 62% by weight finer than 2 micrometers; TiO 2 and Fe 2 O 3 contents were 0.86% and 0.64%. Brightness was 83.5%.
The slurry discharged from the delaminator, which had a distinctly pink appearance, was then separated in a Sharples centrifuge, recovering a delaminated fractionated product having No. 2 coating clay particle size specification (81% finer than 2 micrometers) and 84.1% brightness. TiO 2 was 1.24%; Fe 2 O 3 was 0.61%. The delaminated product was then purified in a high intensity magnetic separator with a 430 stainless steel wool matrix. As a consequence of magnetic separation, the distinctly pink color disappeared.
Portions of the mechanically delaminated, magnetically purified clay were then bleached with various amounts of sodium dithionite. Optimum bleach dosage was 12 pounds per ton, resulting in a bleached, delaminated product having a brightness of 90.2%. TiO 2 content was 0.78%; Fe 2 O 3 was 0.56%.
The 93% finer than 2 micrometer fraction of undelaminated clay from the initial Sharples classification (prior to delamination) was also magnetically purified, bleached and spray dried to recover a No. 1coating clay.
The delaminated product made in the above described procedure had the following characteristics:
Particle Size:
% finer than 10.0 micrometers >99
% finer than 5.0 micrometers 99
% finer than 2.0 micrometers 81
% finer than 1.0 micrometers 56
% finer than 0.5 micrometers 26
% finer than 0.2 micrometers 3
Median Particle Size: 0.88 micrometers ##EQU5## Surface Area: 9.4 m 2 /g Slurry Viscosity
At 68.5% solids:
Brookfield @20 rpm: 80 cp
@100 rpm: 70 cp
Hercules @1100 rpm: 6.4 dyne-end point
At 71.7% solids:
Brookfield @20 rpm: 170 cp
@100 rpm: 132 cp
Hercules: 245 rpm @16 dynes
Black Glass
Scattering co-efficient at 457 nm: 113 m 2 /Kg
Scattering co-efficient at 577 nm: 81 m 2 /Kg
Gloss 82.5%
It is within the scope of the invention to utilize feed to the delaminator which consists of coarse centrifuge underflow fraction (about 20% finer than 2 micrometers) and a portion of degritted feed (about 55% finer than two micrometers) to produce a delaminator charge of a desired particle size of about 35% minus 2 micrometers. The resulting blend of dispersed clays is then subjected to mechanical delamination under the conditions and in the manner described above. The delaminator discharge has a particle size distribution of about 60% finer than two micrometers. The slurry discharge is then charged to a Sharples centrifuge, recovering a delaminated fractionated product stream with a particle size of about 80% finer than 2 micrometers, which is then purified as described above. The characteristics of the delaminated, fractionated product conform to the specifications of the products of the invention. This embodiment of the invention is not limited to the specific particle size variations set forth above.
Delaminated Product from Coarse Particle Size Fractions of Crude
Delaminated product from the above described procedure was admixed with binders and other constituents in the formulation described below to make paper coating colors which were tested for coating color viscosity and then applied in a conventional manner to appropriate commercially available European and American lightweight paper base stock.
Formulations used are:
______________________________________Coating Color FormulationsAmerican American EuropeanLWC Offset LWC Roto LWC Roto______________________________________Pigment 100 Pigment 100 Pigment 100PG 280 8 PG 280 7 Resyn 5 6833CP 640A 8 CP 620A 4 FinnFix 1.5 5Sunrez 0.5 Nopcote 0.5 Nopcote 0.5700C C-104 C-104Nopcote 0.5C-104______________________________________
The pigments tested included:
Pigment A--Product of the invention as described in this example.
Pigment C--Commercially available mechanically delaminated pigment made from Georgia, USA kaolins.
Pigment D--Commercially available naturally delaminated pigment made from kaolins mined in Cornwall, United Kingdom.
American LWC Roto
Coating color viscosity and coated sheet properties were measured as follows:
______________________________________ Product A Product C______________________________________Solids (%) 57.1 57.0pH 8 8Brookfield (cp) 20 rpm 2640 2800100 rpm 900 9784400 H.E.P. `E` 18.2 23.6______________________________________
______________________________________COATED SHEET PROPERTIES(American LWC Roto) Product A Product C______________________________________Gloss (%) 55 49Brightness (%) 74.2 73.4Opacity (%) 85.2 84.6Heliotest (mm) 84 69______________________________________ Properties shown are at 5.5 lb/3300 ft.sup.2 Calendar conditions: 3 nips, 2000 psig, 140° F.
European LWC Rotogravure
Similarly, coating color viscosity and coated sheet properties for Product A, Product C, Product D were tested in the European LWC rotogravure formulation with the following results:
______________________________________COLOR PROPERTIES(European LWC Roto) A C D______________________________________Solids (%) 57.1 57.0 57.2pH (NaOH) 8 8 8Brookfield (cps) 20 rpm 1,050 1,680 13,150100 rpm 352 536 4,280400 H.E.P. `E` 16.0 22.8 35.6______________________________________
______________________________________COATED SHEET PROPERTIES(European LWC Roto) A C D______________________________________Gloss (%) 53 46 43Brightness (%) 74.8 73.8 74.2Opacity (%) 85.6 84.5 84.5Heliotest (mm) 51 40 52______________________________________ Properties shown are at 5.5 lb/3300 ft.sup.2 Calendar conditions: 2 nips, 1600 psig, 140° F.
In each of the cases above, the product A of the invention provided equivalent to superior to significantly superior optical and printability characteristics compared to commercial delaminated pigments C and D; and the product of the invention had significantly lower high and low viscosity than the commercially available pigments at the same solids level in the same coating color formulation.
An alternative means of quantifying the novel, unexpected viscosity characteristics of the delaminated product of the invention is to determine the coating color solids level at which the product of the invention will report viscosity measurement values equal to the commercially available pigments. This determination was made by measuring the Brookfield and Hercules viscosity of the commercially available Product C at typical color coating solids level 57%.
A product of the invention, Product A, was admixed in a pigment binder system at a significantly higher solids level than 57% solids and viscosity measurements were taken; then the solids level was reduced by one percent increments with the addition of deionized water, with viscosity measurements again taken at each new lower solids level. This process is repeated to establish a range of data relating coating color solids to viscosity and until the viscosity measurements of product A, initially higher than that of product C, are, via dilution of solids content, lower than the viscosity measurement of product C.
In this manner and with the pigments of this example, it was determined that product of the invention A can be dispersed in an American LWC offset formulation and achieve an equivalent Brookfield viscosity value to commercially available product C at 2% higher color solids level and an equivalent Hercules viscosity value at 3% higher coating color solids. These differences are significant and can provide substantial commercial advantages to the paper maker.
EXAMPLE 3
Whole Fraction Delamination
(Manaus, Amazonas,Brazil kaolin crudes)
In this example, processing steps described above in Example 1 for Product A were employed for crudes from deposits of kaolinitic sands located about 75 kilometers north of the city of Manaus, Amazonas state, Brazil.
The slip was prepared by blunging the kaolin crude in water containing Calgon® dispersant, resulting in a slurry with a pH of 7.1. The slip was degritted in two stages, the first involving allowing the slip to remain quiescent for about 5 minutes and then passing the nonsettled portion through a 200 mesh screen (U.S. standard). The degritted slip at about 41% solids contains about 43% of the starting crude. Particle size of the recovered kaolin was 57% finer than 2 micrometers. Brightness was 82.6%; Fe 2 O 3 and TiO 2 were 0.69% and 0.81% respectively.
Delamination was carried out in a pilot plant delamination simulator as described above. Bead volume was 50% and residence time was 45 minutes. The discharge of the delaminator Was charged to a magnetic separator and then flocced and bleached with 6#/ton K-brite® sodium dithionite solution, then filtered, rinsed and dried using conventional procedures.
The delaminated pigment product of this example had the following characteristics:
Particle Size
99% finer than 10 micrometers
Distribution (weight % finer than e.s.d.)
93% finer than 5.0 micrometers
71% finer than 2.0 micrometers
49% finer than 1.0 micrometer
27% finer than 0.5 micrometers
3% finer than 0.2 micrometers
Median particle size: 1.02 micrometers ##EQU6## Surface Area: 9.2 m 2 /g Viscosity, measured at 70.3% solids
Brookfield @20 rpm: 100 cp
@100 rpm: 80 cp
Hercules @1100 rpm: 7.7 dynes
Black Glass
Scatter coefficient at 457 nm: 108 m 2 /Kg
Scatter coefficient at 577 nm: 82 m 2 /Kg
Gloss: not measured
Example 4 Processing Replicates of Novel Whole Fraction Delaminated and Delaminated Produces from Coarse Fractions of Crude
In this example, the crudes used in Example 1 and Example 2 were again processed, in part, in a manner more fully described in Example 1 and Example 2 to make products of the invention.
Whole Fraction Delamination
In this case a degritted slip of kaolin, with physical characteristics as reported below, is subjected to mechanical delamination without first fractioning the slip. The delaminator discharge, with physical characteristics as described below, was charged to a Sharples centrifuge which divided the slip into Product A, a fine fraction of 75% finer than two micrometers, as more fully described below, and a coarse reject fraction. The product slip can then be subjected to brightness enhancement as described in Example 1.
______________________________________Whole Fraction Delaminated Degritted Crude & Delaminator Delaminator Final Charge Discharge Product______________________________________Particle SizeDistribution% less than 5 microns 76.4 91.1 95.8 2 microns 55.0 67.6 74.5 1 micron 40.4 47.4 53.2.5 micron 23.3 25.1 28.8.3 micron 10.3 9.2 11.4.2 micron 4.8 3.6 4.4Surface Area 7.8 7.9 8.9m.sup.2 /gBET - N.sub.2Viscosity72% SolidsBrookfield 90 cps 138 cps 205 cps@ 20 RPMBrookfield 122 cps 168 cps 174 cps@ 100 RPM68% SolidsBrookfield 40 cps 59 cps 64 cps@ 20 RPMBrookfield 71 cps 78 cps 76 cps@ 100 RPMHercules 2.0 dynes@ 1100 RPM 1.9 dynes 2.3 dynes 2.0 dynesHercules 12 dynes 28.8 dynes 26.8 dynes@ 4400 RPM______________________________________
Delaminated Product from Coarse Fraction of Crude
In this example, the degritted kaolin crude slip, with physical characteristics as described below, is separated by a centrifuge, as described in Example 2, into a fine fraction and coarse fraction with particle size distributions as described below. A portion of the fine fraction recovered in the first step is then admixed with the course fraction in order to make a kaolin slip for charge to the delaminator; the portion of fine fraction remaining can be further processed in a conventional manner into a fine fraction No. 1 grade product, if desired. The delaminator charge, with physical characteristics as described below, is charged to the delaminator, as described in Example 2. The delaminator discharge with physical characteristics as described below is then charged to a centrifuge to separate the slip into a delaminated product as described below, and a course reject fraction. The fractionated, delaminated product slip can then be subjected to brightness enhancement, as described in Example 2.
__________________________________________________________________________ Degritted Crude & Fine Centrifuge Fractionated Coarse Delam. Delam. Centrifuge Charge Slip Fraction Charge Discharge Product__________________________________________________________________________Particle Size Distribution% less than 5 microns 76.4 99.4 59.9 73.3 89.5 97.5 2 microns 55.0 88.1 28.3 49.9 63.0 75.3 1 micron 40.4 68.9 19.1 35.3 42.8 52.7.5 micron 23.3 39.9 11.1 21.4 23.2 28.5.3 micron 10.3 16.9 6.0 8.8 9.8 11.1.2 micron 4.8 7.1 2.6 3.1 4.7 3.6Surface Area m.sup.2 /g 7.8 8.3 8.7BET - N.sub.2Viscosity72% SolidsBrookfield @ 20 RPM 90 cps 90 cps 112 cps 158 cpsBrookfield @ 100 RPM 122 cps 129 cps 143 cps 170 cps68% SolidsBrookfield @ 20 RPM 40 cps 41 cps 42 cps 61 cpsBrookfield @ 100 RPM 71 cps 76 cps 66 cps 73 cpsBrookfield @ 1100 RPM 1.9 dynes 2.6 dynes 2.6 dynes 2.5 dynesHercules @ 4400 RPM 12 dynes 15.2 dynes 28.4 dynes 32.0 dynes__________________________________________________________________________ | 4y
|
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation, under 35 U.S.C. §120, of copending international application No. PCT/EP2013/053921, filed Feb. 27, 2013, which designated the United States; this application also claims the priority, under 35 U.S.C. §119, of German patent application No. DE 10 2012 203 010.7, filed Feb. 28, 2012; the prior applications are herewith incorporated by reference in their entirety.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The invention relates to a method for conditioning a power-generating circulatory system of a power plant. By way of example, such a circulatory system should be understood to mean the primary and secondary circuit of a pressurized water reactor, the coolant circuit of a boiling water reactor and the steam circuit of a conventional power plant. Here, the term “conditioning” should be understood to mean a measure by means of which the surfaces of the components of the circulatory system can be protected from corrosion. When surfaces are mentioned, this should be understood to mean, on the one hand, the inner surfaces of e.g. lines, heat exchangers and containers and, on the other hand, surfaces of components such as turbine blades around which a work medium (water, steam) of the circulatory system flows. By way of example, German published patent application DE 2625607 and German patent DD 107962 describe methods in which film-forming amines (FFA) are metered into the secondary circuit or the water/steam circuit of pressurized water reactors during power operation.
[0003] The object of conditioning of the type in question is to generate a thin film on the surfaces which is as contiguous as possible, with the thickness of at most one to two molecule layers. However, conventional methods result in the risk in this context that thicker FFA deposits are formed, which, on the one hand, interfere with the process operation, by virtue, for example, of reducing heat transport in steam generators or other heat exchangers or narrowing flow cross sections. Moreover, there is the risk of parts of the deposits detaching and damaging turbine blades or adversely affecting mechanical filter installations and ion exchangers, so that the latter two have to be replaced.
SUMMARY OF THE INVENTION
[0004] It is accordingly an object of the invention to provide a method of conditioning of a power-generating circulatory system of a power plant which overcome the above-mentioned disadvantages of the heretofore-known devices and methods of this general type.
[0005] With the foregoing and other objects in view there is provided, in accordance with the invention, a method of cleaning and conditioning a circulatory system of a power plant, in particular a water/steam circuit of a nuclear power plant. The method comprises:
[0006] adding an amine as a film-forming agent to a work medium circulating in the circulatory system, for the film-forming agent to form a hydrophobic film on surfaces of the circulatory system;
[0007] monitoring a concentration of the film-forming agent by conducting measurements at a measurement point during a duration of the method; and
[0008] terminating the step of adding the film-forming agent when the concentration of the film-forming agent in the work medium has reached a value between 1 ppm and 2 ppm at the measurement point.
[0009] In other words, the above and other objects are achieved with a method of the type mentioned at the outset, in that preferably during power operation an amine is added to the work medium circulating in the circulatory system, which amine acts as film-forming agent and forms a hydrophobic film on the surfaces of the circulatory system which are in contact with the work medium. Here, the method is carried out in such a way that there is control in respect of the concentration of the film-forming agent or the progress of the film formation at practically any time during the method. This is achieved by virtue of the fact that the concentration of the film-forming agent is monitored at at least one measurement point by measurements during the duration of the method. Here, the film-forming agent is metered in such a way that in the water phase of the water/steam circuit, at least in the steam generator feed water, there is a concentration of 1 to 2 ppm, preferably of 1 to 1.5 ppm. If work is conducted within these boundaries, in particular with at most up to 1.5 ppm of film-forming agent, the formation of thick layers of the film-forming agent can be avoided. It was moreover found that, in many cases, an adequate film is already present on the surfaces when the aforementioned concentration or target concentration has been reached.
[0010] However, a single-layer or substantially mono-molecular film is obtained with greater reliability on the surfaces, substantially covering the latter completely, if the method is continued under the aforementioned premises until the concentration of the film-forming agent at a constant metering rate at a plurality of measurement points distributed over the water/steam circuit remains constant averaged over time at a plurality of measurement points (M1, M2, M3), i.e. if an equilibrium concentration sets in at the measurement points. The mean averaged over time is understood to mean the profile of the trend which emerges if fluctuations due to the measurement technologies have been eliminated by suitable methods of conventional error calculation.
[0011] The measurement points already mentioned above are, in the case of a water/steam circuit, distributed such that at least one measurement point is situated in the one-phase region and at least one measurement point is situated in the two-phase region of the circuit.
[0012] In a preferred variant, the method is carried out in such a way that it can be possible, at practically any time during the method, to control not only the concentration of the film-forming agent or the progress of the film formation, but also the effects of the film-forming agent metering in respect of impurities mobilized thereby. This is achieved by virtue of the fact that the concentration of at least one impurity and the concentration of the film-forming agent are measured during the duration of the method and the concentration of the film-forming agent is modified depending on the concentration of at least one impurity. This ensures that, at any time during the method, predetermined guide values and limits of an impurity, in particular a corrosively acting ionic impurity such as e.g. chloride or sodium ions, are maintained or not exceeded. Moreover, it is possible to effectively prevent an impurity, immobilized at a locally restricted surface region of the water/steam circuit, from quickly being mobilized by metering of the film-forming agent and being distributed in large quantities in the whole circuit.
[0013] As a countermeasure to an increase in the concentration of an impurity, the metering rate of the film-forming agent can be reduced or interrupted, in particular in view of maintaining limits. A further countermeasure consists of reducing the concentration of impurities that have passed into the work medium. This preferably occurs by virtue of the water/steam circuit being purged and, in the process, particulate impurities, inter alia, being removed by blowing down. This measure preferably occurs, for example for reasons of procedural economy, directly following an interruption of the metering of the film-forming agent. It is also feasible that, in order to remove impurities from the water/steam circuit, filters are employed, for example the filter installations of the condensate cleaning system, which is part of the power plant.
[0014] Monoamines with a hydrocarbyl comprising 8 to 22 carbon atoms were found to be particularly effective for both the cleaning effect and for the film formation, with octadecylamine being particularly suitable in this case. Monoamines of the present type are available as waxy substance at room temperature. Conventional emulsions produced therefrom usually contain relatively large amounts of organic emulsifiers, which can have damaging effects in the water/steam circuit. Therefore, the FFA is preferably employed in the pure form in the method according to the invention, namely as an aqueous emulsion without the addition of emulsifiers, which can be obtained by pure mechanical mixing under the application of increased temperature.
[0015] Other features which are considered as characteristic for the invention are set forth in the appended claims.
[0016] Although the invention is illustrated and described herein as embodied in a method for conditioning a power-generating circulatory system of a power plant, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
[0017] The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0018] FIG. 1 shows, in a very schematic view, the water/steam circuit of a pressurized water reactor (PWR);
[0019] FIG. 2 shows a diagram which reproduces the time profile of the concentration of ODA in the steam generator feed water due to ODA metering; and
[0020] FIG. 3 shows a flowchart illustrating a conditioning process.
DETAILED DESCRIPTION OF THE INVENTION
[0021] Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown an exemplary circulatory system, in the form of a water/steam circuit 1 (abbreviated WSC in the following text) of a pressurized water reactor (PWR). The circuit comprises a piping system 2 , a plurality of steam generators 3 , normally a plurality of turbines, for example a high-pressure (HP) turbine 4 and a low-pressure (LP) turbine 5 , a water separator intermediate superheater 17 between the HP and LP turbines, a condenser 6 , a feed water container 7 , a condensate pump 8 arranged between the condenser 6 and the feed water container 7 , a plurality of feed water preheaters 16 and a feed water pump 9 arranged between the feed water container 7 and the steam generator. Moreover, downstream of the condenser 6 , there is a condensate cleaning system 10 , which can comprise mechanical filters and, likewise, ion exchangers. On the primary side, the steam generator 3 is connected to the primary circuit 13 of the nuclear reactor, which comprises the reactor pressure container 14 and a main coolant pump 15 .
[0022] As mentioned above, the cleaning and conditioning method is preferably carried out during power operation. This also comprises phases during the startup and shutdown of the power plant. In the exemplary embodiment described below, the conditioning of the water/steam circuit or the metering of a film-forming amine (abbreviated to FFA in the following), namely octadecylamine (ODA), is carried out just before shutting down the nuclear reactor. The continuous monitoring of concentrations or concentration changes in FFA and impurities (see step II in FIG. 3 ), carried out from the start of the method, is brought about by a plurality of measurement points arranged at different positions within the WSC 1 . Some of these measurement points M1, M2, M3 are depicted in FIG. 1 in an exemplary manner.
[0023] The film-forming agent may be metered in at any expedient location within the circulatory system. Here, the injection point is illustrated in FIG. 1 by way of the arrow just upstream of the condenser 6 .
[0024] As a result of the surfactant-like properties of the ODA (octadecylamine), there is a mobilization of impurities from the start of the FFA metering. Thus, as already mentioned above, limits which may not be exceeded are set for the concentration of these impurities. In the case of ionic impurities, the concentration is measured directly, i.e. in relation to a very specific ion with known wet-chemical or physical-chemical measurement methods. However, the concentration can also be determined indirectly, i.e. by the increase in the electrical conductivity of the work medium caused by the mobilization or the passage of ions into the work medium. The measurement methods used in the process are well known to a person skilled in the art, and so these do not have to be discussed in detail. A further parameter important for carrying out the method in a controlled manner is the FFA or ODA concentration in the work medium—the water present in the WSC.
[0025] Finally, as a result of the ODA metering, corrosion products are also released, i.e. very fine particles of magnetite, which adhere to the surfaces and, as a result of the effect of ODA, go into colloidal solution. Since the majority of corrosion products can be traced back to metal oxides such as magnetite, it is normally sufficient only to carry out measurements in this respect. In the process, e.g. the iron content of the feed water is determined in a known fashion and, as a result of the known stoichiometry of the magnetite, the concentration thereof in the feed water is deduced. Finally, the pH-value is also monitored in order to prevent corrosion of the metallic components of the WSC 1 . It is also feasible for the TOO (total organic carbon) value to be monitored in order to exclude a possible decomposition of the added ODA at the prevalent conditions, i.e. temperatures of over 250°, and hence the formation of decomposition products which could act corrosively.
[0026] The ODA metering or the amount of ODA metered into the WSC 1 per unit time is—on the basis of the measurement data established at the measurement points M1 to M3 regulated such that the concentrations of the type of impurities that have passed into the work medium due to the ODA metering remain below predetermined limits (see step III in FIG. 3 ). Moreover, by monitoring the aforementioned concentration values, it is already possible to identify a trend in a timely fashion such that a countermeasure can be introduced in a timely fashion. By way of example, the metering-in of ODA can be reduced or interrupted. Here, it should be noted that a change in metering only has an effect a couple of hours later due to the volume of water and the length of the piping of the WSC 1 . However, this time delay plays practically no role in a method according to the invention since a change of a critical concentration value is identified by permanent whole control at a plurality of measurement points M1 to M3, long before said value has reached its critical limit.
[0027] In order to have an indication of which ODA amounts are required for a given WSC 1 , it is expedient to estimate what approximate amount of ODA is necessary to generate a mono-molecular hydrophobic film on the surfaces of the WSC. This amount can then still be multiplied by a factor in order to take into account the roughness of the surfaces, which, after all, is significant in the case of sub-microscopic observation, and effects which use up ODA, for example the degree of contamination of the WSC. On the basis of this estimate, it is possible, in the case of a given ODA metering rate, to specify a defined period of time in which an ODA film which completely covers the surfaces, e.g. a mono-molecular ODA film, has been created.
[0028] When a critical concentration of an impurity is reached (step III in FIG. 3 ), an effective measure for reducing the critical concentration lies in interrupting the FFA metering and a subsequent purging or blowing down, during which the impurity is removed from the WSC (step VII in FIG. 3 ). In the process, there is continuous monitoring of whether the installation-specific control parameters or concentrations lie in an admissible range (step VIII in FIG. 3 ). If this is the case, the conditioning is continued by resuming the FFA metering.
[0029] The concentration of ODA in the aqueous phase is regulated by appropriate metering rates in such a way that this value, practically until the end of the method, does not exceed an upper absolute safety limit of 2 ppm, preferably 1.5 ppm. As a result, this prevents too strong a mobilization of impurities, which goes beyond the set limits, or a no longer controllable massive ODA precipitation from occurring. It also ensures that no unwanted massive ODA deposits are formed. In so doing, metering is such that initially there is a low ODA concentration, which only rises to a target concentration of above 1 ppm, at most up to 1.5 ppm or 2 ppm (C Target in FIG. 2 ), toward the end of the process. The addition preferably continues until the ODA concentration with increasing tendency has reached the maximum values of 2 ppm or 1.5 ppm (step VI in FIG. 3 ).
[0030] In order to identify when a complete substantially mono-molecular film is formed on the surfaces, the concentration profile of the ODA concentration is observed at an unchanging ODA metering rate. If the equilibrium concentration of the FFA is reached at a plurality of measurement points, preferably at all measurement points M1 to M3, i.e., if an unchanging or slightly falling FFA concentration is to be observed (step V in FIG. 3 ), the time has been reached to end the ODA metering-in or the conditioning method (step VI in FIG. 3 ; line CP in FIG. 2 ). The unchanging or sinking ODA concentration toward the end of forming the film could be traced back to the fact that the formation of ODA double and multiple layers is favored for kinetic and/or thermodynamic reasons and therefore occurs more quickly than the initial film formation on the metallic surfaces of the WSC 1 .
[0031] The ODA film applied to the surfaces of the WSC can lose or reduce its effectiveness over time, for example by virtue of it in part detaching from surfaces or for instance it being subjected to thermal or chemical decomposition processes. It is therefore expedient to undertake a refresh conditioning at a given time. To this end, permanent monitoring of the work medium for the presence of corrosion products, i.e. products connected with the formation of oxidation layers, for example metal ions originating from the component materials of the WSC, is expedient. As soon as it is possible to identify a (significant) increase of corrosion products (step X in FIG. 3 ), a conditioning of the type described above is put into motion.
[0032] The following summarizes and lists the various steps illustrated in the flowchart of FIG. 3 .
[0033] Step I Start of FFA conditioning
[0034] Step II Process monitoring
FFA concentration (M 1 -M 3 in FIG. 1 ) Control parameters as per installation specification
[0037] Step III Limits of control parameters reached?
[0038] Step IV Target concentration of FFA reached at M 1 ?
[0039] Step V Equilibrium concentration of FFA reached over M 1 -M 3 ?
[0040] Step VI End of FFA conditioning
[0041] Step VII Interrupt metering, purging
[0042] Step VIII Values of the control parameters in an admissible range?
[0043] Step IX Process monitoring of corrosion products
[0044] Step X Increase in the concentration of corrosion products? | 4y
|
REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application Ser. No. 438,161, filed Nov. 1, 1982, for "Process and Apparatus for Surface Diffusing Steel Product in Coil Form and the Products Made by Such Process and Apparatus", now abandoned.
BACKGROUND OF THE INVENTION
U.S. Pat. Nos. 3,620,816 and 4,168,333 describe methods for diffusing elements such as chromium and/or aluminum into the surface of ferrous-based substrates in order to produce an alloyed steel surface. Such methods involve placing the substrate in a molten lead bath containing chromium and/or aluminum for an extended period of time, from one to eighteen hours. The molten lead acts as a transfer agent to transfer the chromium and/or aluminum dissolved in the bath to the substrate and to diffuse the same into its surfaces. Processing times of one hour or more are satisfactory when batch processing is employed; in other words, when the parts are placed in a bath for the requisite time and then removed. Such long periods of time, however, are not satisfactory when it is desired to diffuse chromium and/or aluminum into the surfaces of steel sheet or other products, in coil form, on a continuous basis.
The carbon in the steel while important to giving steel its strength, adversely affects the corrosion resistance of a chromium diffusion layer formed on the surface of the steel. Low carbon steel having a carbon content of between 0.01% and 0.06% by weight is available. Various decarburization heat treatments can reduce the carbon content still further. However, as the chromium diffuses into the surface of such low carbon, decarburized steel, the remaining carbon tends to migrate to the surface. It is believed that when sufficient carbon has diffused into the chromium diffusion alloy layer on the steel, precipitation of chromium carbides will occur during subsequent cooling from the processing temperature, which can result in chromium depletion in regions adjacent to the carbides. This effect is believed to cause the loss in corrosion resistance. Therefore, it is desirable to form the carbon adjacent the surfaces of the ferrous-based material into carbides that are more stable than chromium carbides.
In preparing the bath for performing the diffusing process, chromium is added thereto. Usually chromium is in particulate form and is contained within a cage that is placed in the bath. The cage is normally agitated, causing the chromium particles to dissolve in the molten lead and thereby leave the cage. The chromium is either in elemental form or is an alloy such as ferrochromium. Either form is likely to have debris associated therewith. The debris does not dissolve in the bath and instead travels upwardly in the bath to form a dross on its surface. When sheet steel is drawn through such a bath, it tends to pick up impurities from the dross, Which impurities constitute barriers to diffusion of the chromium. Furthermore, these inorganic particles serve as nucleation sites for the in-situ growth of dendritic structures of alloy crystals that form on the surface. The corrosion resistance of the steel at the sites of the foreign matter is much less. The contamination can be reduced by screening the chromium prior to its being placed in the bath. Additionally, the chromium can be cleaned with chemicals such as solvents and acids.
SUMMARY OF THE INVENTION
It is therefore an important object of the present invention to provide a process, and apparatus for practicing the process, to continuously diffuse elements such as chromium and/or aluminum into the surfaces of steel sheet and other products in coil form.
Another object in connection with the foregoing object is to uncoil the coiled steel, pass it through a molten alloy bath within minutes or even less than one minute, and generate steel product with stainless steel surfaces that are highly corrosion resistant.
Another object is to utilize low-carbon coiled steel, uncoil it, decarburize it and finally form whatever carbon is remaining adjacent the surfaces into carbides more stable than chromium carbides, so as to improve the corrosion resistance of the steel product.
Another object in connection with the foregoing object is to diffuse titanium into the surfaces of the uncoiled steel, ahead of the diffusing chromium.
It is another object of the present invention to utilize coiled steel products, uncoil them, and treat the uncoiled steel in a molten lead bath in such a way that foreign matter in the dross associated with the bath does not attach itself to the steel as it enters and exits the bath.
Another object is to provide sheet steel with a thin chromium alloy layer diffused into each surface.
In summary, there is provided a continuous process of surface diffusion alloying a continuous length of steel product supplied in a coil, comprising uncoiling the steel product, preheating the steel product, providing a molten-alloy bath having therein lead and chromium and titanium, the molten-alloy bath having titanium of a concentration in the range of about 67 ppm to about 367 ppm, lead being the only transfer agent in the bath, moving the steel product continuously through the bath for diffusing the chromium into the surface of the steel product, and cooling the diffused steel product.
The invention consists of certain novel features, a composition of matter and a process and apparatus for making such composition of matter, as hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
For the purpose of facilitating an understanding of the invention, there is illustrated in the accompanying drawings a preferred embodiment thereof, from an inspection of which, when considered in connection with the following description, the invention, its construction and operation, and many of its advantages should be readily understood and appreciated.
FIG. 1 is a somewhat schematic, elevational view of apparatus for continuously diffusing chromium or other element into the surface of sheet steel;
FIG. 2 is a fragmentary view in vertical section on an enlarged scale taken along the line 2--2 of FIG. 1;
FIG. 3 is a fragmentary view in vertical section taken along the line 3--3 of FIG. 2;
FIG. 4 is a view in horizontal section on an enlarged scale taken along the line 4--4 of FIG. 1;
FIG. 5 is a view in horizontal section on an enlarged scale taken along the line 5--5 of FIG. 1;
FIG. 6 is a view in horizontal section on an enlarged scale taken along the line 6--6 of FIG. 1; and
FIG. 7 is a view in horizontal section on an enlarged scale taken along the line 7--7 of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Turning to the drawings and more particularly to FIG. 1 thereof, there is depicted a processing apparatus generally designated by the number 10, which is operative to continually diffuse chromium into the surfaces of sheet steel. The present invention is described in connection with diffusion of chromium to obtain stainless steel surfaces on the sheet steel. However, the principles of the invention are applicable to other steel products in coiled form such as foil (having a thickness of less than 12 mils), plate and wire. While chromium is the preferred diffusing element, and will be so described, additional and/or other diffusing elements can be employed. For example, aluminum can be diffused along with or instead of chromium. The processing apparatus 10 represents a model of a line to produce chromized sheet steel on a continuous basis. It is a model in that the steel to be processed is narrow on the order of about four inches. In actual practice, steel two or three feet in width or more can be processed.
The sheet steel 12 is supplied in coil form, wrapped around a hub 13 mounted for rotation in known manner. A motor (not shown) rotates the hub 13 to unroll the sheet steel. The sheet steel 12 passes a follower arm 14 which operates a switch (not shown) that controls the motor. When the motor is on, sheet steel 12 is withdrawn from the roll to increase the size of the loop as shown by the phantom line, until the follower arm 14 reaches the position indicated in phantom, whereupon the motor is turned off. The sheet steel, being drawn by a subsequent station by a drive mechanism to be described, straightens the loop. In this way, the size of the loop is controlled.
The sheet steel 12 passes a deflector roll 15 to equipment located in a furnace 20 in turn positioned within a pit 21 located beneath the floor 22. An access platform 23 is located above the furnace 20. Removably positioned in the furnace 20 is a cylindrical retort 24 closed at the bottom and having a flange 25 extending around its periphery at the top. The retort 24 contains a predetermined quantity of molten lead 26.
The processing apparatus 10 comprises a drive mechanism 30 which includes a hold-down or pressure roll 33 bearing against a flanged idler roll 35. The sheet steel 12 passes between the rolls 33 and 35, and around the roll 35, and in between it and a brake roll 38. The sheet steel 12 is drawn downwardly through rolls 64 of a sealing mechanism 60, through a rectangular inlet tube 80 into the retort 24. The sheet steel 12 passes into molten lead 26, around the idler roll mechanism 100, up through a rectangular outlet tube 85. The exiting sheet steel 12 passes through another pair of rolls 70 in the sealing mechanism 60 and then up between a drive roll 45 and a flanged idler roll 43. The drive roll 45 is rotated by a motor, in a manner to be described, which pulls the sheet steel 12 from the coil so as to follow the path just described. The sheet steel 12 passes over a deflection roll 16, an output follower arm 17, between tension rolls 18 and onto a hub 19 to form an output coil. The hub 19 is also connected to a motor (not shown) which is energized by a switch (not shown) controlled by the follower arm 17. The phantom line position of the follower arm 17 indicates its position when the motor is energized to remove the loop.
Turning now to FIGS. 3 and 4, further details of the drive mechanism 30 will be described. The drive mechanism 30 includes a generally horizontally oriented frame 31 having at one end an upstanding portion 32. A hold-down or pressure roll 33 is journaled into pillow blocks 34 which are mounted on the upstanding portion 32. A flanged idler roll 35 is journaled into pillow blocks 36 carried by the frame 31. The roll 33 is biased against the roll 35. Adjusting screws 37 positioned in operative relationship with the pillow blocks 34 enable movement of the roll 33. The sheet steel 12 passes between the rolls 33 and 35 each of which has a deformable rubber surface. The adjustment screws 37 are used to control the pressure on the sheet steel 12. The sheet steel 12 remains in contact with the roll 35 for 120° or so. A brake roll 38 is journaled into pillow blocks 39 mounted on the frame 31. The brake roll 38 has a deformable rubber surface biased against the roll 35. The shaft of the roll 38 is connected to a brake 40 which is adjustable to control the friction or braking of the roll 38 as the sheet steel 12 moves therebetween, which in turn controls the tension in that part of the sheet steel 12 between the input and output stages of the drive mechanism 30.
After passing through the retort 24, the sheet steel 12 returns to the drive mechanism 30. The drive mechanism 30 further includes an output roll 43 journaled into pillow blocks 44 carried by the frame 31. A smaller, drive roll 45 is journaled into pillow blocks 46 which are mounted on the frame 31. The rolls 43 and 45 have deformable rubber coatings and the sheet steel 12 passes therebetween. The shaft of the roll 45 is connected to a motor 47 by way of a gear box 48. The drive roll 45 rotates to draw sheet steel 12 from the coiled source thereof, through the retort 24. From there the sheet steel 12 is drawn onto the hub 19 as previously explained.
Turning to FIGS. 2, 3 and 5, the apparatus 10 further comprises a cover plate 50 welded to the flange 25 of the retort 24. The cover plate 50 has a pair of spaced-apart rectangular openings 51 and a pair of spaced-apart round openings 52. Ports 53 in the plate 50 accommodate protective atmosphere flow into the interior of the retort 24. The cover plate 50 also has a pair of spaced-apart exhaust-pipe openings 54 for purposes to be described.
The sealing mechanism 60 includes a rectangular housing 61 formed of sheet metal and having a rectangular inlet slit 62 and rectangular outlet slit 63. Aligned with the inlet slit 62 is a pair of inlet rolls 64 biased against each other and respectively journaled into opposed pillow blocks 65. Located at the ends of the rolls 64 are two side sealing plates 66, each having a pair of concave upper surfaces that fit into grooves 67 in the ends of the rolls 64. End sealing plates 68 have their upper ends bearing against the bottoms of the rolls 64. The sheet steel 12 passes between the rolls 64 and into the retort 24. The plates 66 and 68 in conjunction with the roll 64 constitute a mechanical seal to preclude leakage of the atmosphere in the tube 80. Similarly, the sealing mechanism 60 includes a pair of outlet rolls 70 aligned with the inlet slit 62. The rolls 70 are biased against each other and respectively are journaled into opposed pillow blocks (not shown). Located at the ends of the rolls 70 are two side sealing plates 71, each having a pair of concave upper surfaces that fit into grooves in the ends of the rolls 70. End sealing plates 72 have their upper ends bearing against the bottoms of the rolls 70. The sheet steel 12 passes between the rolls 70 as it exits the retort 24. The plates 71 and 72 in conjunction with the roll 70 constitute a mechanical seal to preclude leakage of the atmosphere in the tube 85.
The rectangular tube 80 has a flared upper end welded to the underside of the cover plate 50 and communicates with one opening 51 in the plate 50 and is aligned with the sealing rolls 64. A pair of inlet pipes 81a is attached to upper points on the tube 80, a pair of inlet pipes 81b is attached to lower points on the tube 80 just above the level of the lead 26, and a pair of inlet pipes 81c is attached to intermediate points. The pipes 81a, b and c enable selected gases to be delivered to the interior of the tube 80. Any one or more of such pipes may be utilized to deliver the gases to a selected point or points in the tube 80. Although not shown, the pipes 81a-c extend through the cover 50 to enable connection to the gas sources. An exhaust pipe 82 is attached to the tube 80 and extends through the cover 50, and enables gases in the tube 85 to be exhausted into the environment. The rectangular tube 85 has a flared upper end welded to the underside of the cover plate 50 and the tube 85 communicates with the other opening 51 in the plate 50 and is aligned with the sealing rolls 70. A pair of inlet pipes 86a is attached to upper points on the tube 85, a pair of inlet pipes 86b is attached to lower points on the tube 85 just above the level of the lead 26, and a pair of pipes 86c is attached to intermediate points. The pipes 86a, b and c enable selected gases to be delivered to the interior of the tube 85. Any one or more of such pipes may be utilized to deliver the gases to a selected point or points in the tube 85. Although now shown, the pipes 86a-c extend through the cover 50 to enable connection to the gas sources. An exhaust pipe 87 is attached to the tube 85 and extends through the cover 50, and enables gases in the tube 85 to be exhausted into the environment. Four cross braces 89 are attached to the tubes 80 and 85.
The sheet steel 12 passes through the tube 80, down into the molten lead bath 26 and after it is processed, is directed back up through the tube 85 and into the sealing mechanism 60.
The insulation plug 90 includes top and bottom plates 91, an annular side wall 92 and insulation material 93. The tubes 80 and 85 pass through the insulation plug 90 and are welded thereto. The insulation plug 90 reduces heat loss from the bath 26.
The idler roll mechanism 100 is depicted in FIGS. 2, 3 and 7. It includes a pair of straps 101 depending from the lowermost cross brace 89. A shaft 102 is journaled into the straps 101 and carries a pair of spaced-apart side plates 103. Loosely journaled into the side plates 103 at spaced-apart points around the periphery thereof is a set of twelve rods 104. The sheet steel 12 exits the inlet tube 80, passes around the idler roll mechanism in contact with a number of the rods 104, and up through the outlet tube 85.
Referring to FIGS. 2 and 7, the apparatus 10 further comprises a chromium container 110 which includes a core 111 to which is secured a pair of spaced upper plates 112 attached to an annular side wall 113 by inner and outer retaining rings 114, thereby defining a compartment 115. Lower plates 116 are also attached to the core 111 at a lower region thereon. The plates 116 are attached to an annular side wall 117 by means of inner and outer retaining rings 114, thereby defining a second compartment 119. A side wall 120 secured to the lower upper plate 112 and the upper lower plate 116 defines, with a spacer 121, a third compartment 122. Particulate chromium, which may be either in elemental form or compound form, is contained in one or more of the compartments 115, 119 and 122. Actually each of the plates 112 and 116 includes a screen of a gauge to prevent the particulate chromium from escaping into the lead bath 26, except to the extent it is in solution with the molten lead. Preferably each such plate also includes a sheet of expanded metal or the like to rigidify the associated screen.
The chromium, whether in elemental or compound form, is likely to be contaminated. The contamination can be reduced to some extent by cleaning the chromium prior to placing it in the chromium container 110. Acids and solvents can be useful for this purpose. Also, screening the chromium is of some value in removing debris. Even with screening and/or cleaning, some contamination of the chromium will remain. In solution, such contaminants migrate upwardly and create a dross floating on the lead. Debris from such dross tends to become attached to the sheet steel as it enters the bath 26.
To prevent that from occurring, debris blocking structure is provided which, in the embodiment depicted is a cylindrical tube 125 extending from the cover 50 downwardly into the molten lead 26, terminating in a downwardly and inwardly directed deflector 126 defining a discharge area 127. The upper end of the tube 125 is connected to a cover plate 128 which in turn is connected to the main cover plate 50. Slots 129 accommodate gas flow between the tube 125 and the retort 24. When debris separates from the chromium, it migrates upwardly through the vertical region defined in the tube 125 and floats on the molten lead contained therein. The contaminants do not float on the surface of the balance of the lead which defines another vertical region. Thus, the contaminants do not come in contact with the sheet steel as it enters the lead in the tube 80.
The chromium container 110 is agitated to hasten the dissolution of the chromium in the molten lead. The dissolved chromium is pumped downwardly against the deflector 126 and out the discharge area 127 into the main body of molten lead. The agitator 130 includes an axial bearing 135 attached to the cover plate 128. A stand-off tube 136 is attached at its lower end to the bearing 135 and has opposed elongated slots 137 in its side wall. A shaft 138 is axially movable in the bearing 135, having its lower end attached to the core 111 and partly located within the stand-off tube 136. The upper end of the shaft 138 is coupled by way of a connector 139 to a pneumatically operated cylinder 140. At the joint between the shaft 138 and the connector 139 is a laterally extending pin that rides in the slots 137 for limiting the stroke of the cylinder 140.
Preferably the cylinder 140 operates more slowly in the upstroke than in the downstroke so as forcefully to discharge the molten lead having the entrained chromium therein.
To minimize heat loss from the molten lead, there is provided an insulator 145 hanging by means of chains 146 attached to lugs 147 and to the plate 128. Although the insulator 145 is shown above the insulation plug 90, it is preferable that the insulator 145 be lowered so that it is at the same height, so that a substantially continuous heat shield across the reactor is defined.
A second chromium container 110, a second tube 125, a second agitator 130, and a second insulator 145 are provided as shown.
Before the sheet steel is processed in the lead bath 26, one or more pretreatment steps are required. It is desirable that as many as possible of these pretreatment steps be performed in the line represented by the apparatus 10. Two such steps preferably performed in the line and specifically within the tube 80 are cleaning and decarburizing the sheet steel. A further important step is preheating the steel gradually.
Referring to this last step first, the sheet steel for processing is at room temperature while the bath 26 is at a temperature of between 1,700° F. and 2,300° F. It would be deleterious to the steel to plunge it directly into the bath 26. The temperature of the interior of the tube 80 follows a gradient from the temperature of the bath at its lower end to approximately 500° just below the sealing rolls 64. The time during which the sheet steel is preheated is controlled by its speed through the apparatus 10. A slower speed means that the sheet steel will be treated more slowly as, of course, will its treatment in the bath 26.
The tube 85 being between the molten lead and the cover 50 constitutes a cooling zone containing an atmosphere administered through any one or more of the pipes 86a, b and c. The atmosphere may be the same as that in the tube 80, at a temperature of say 1,000° F. or lower, to produce rapid cooling.
In order to attain the requisite corrosion resistance, the carbon in the steel must be "tied up" by a strong carbide former like titanium. Accordingly, when the substrate does not itself contain titanium, titanium is codiffused with the chromium in the lead bath. Then, specialized, expensive steel having titanium as part of the alloy is not required. The requisite corrosion resistance was achieved using baths containing 140 ppm titanium and 280 ppm titanium. The minimum titanium level is a function not only of the residual carbon in the steel but also the gradient of the carbon across its thickness. Other factors which affect the quantity of titanium required are the temperature of the bath and the rate at which the steel is cooled after the diffusion process.
The first step is to decarburize the steel to remove a substantial portion of the carbon in the region of its surfaces. The decarburization leaves substantially no carbon at the surface and a carbon content which increases inwardly. In the zone in which the diffusion of chromium is to take place, that is, about 0.2 to 2 mils, a completely carbon free zone is desired. The titanium diffuses into the surfaces of the sheet steel at a rate equal to or exceeding the rate of diffusion of the chromium. The titanium converts the carbon into carbides in the reaction zone.
In an operating form of the invention, the line speed of the sheet steel was adjustable between one inch per minute and 25 inches per minute with a drive torque of 340 inch pounds. The height of the molten lead bath 26 was between 20 inches and 24 inches. The balance of the retort 24 was devoted to preheating the sheet steel. The distance between the bottom of the retort 24 and the insulation plug 90 was 623/4 inches, so that with a 20 inch lead level, the sheet steel was preheated for 423/4 inches while for a 24 inch level the preheat length was 383/4 inches. The center of rotation of the idler roll mechanism 100 was 10 inches off the floor of the retort 24, and its diameter was 6 inches. Thus, if the level of the lead was 20 inches, the sheet steel would be in the bath for 38 inches (10" down+10" up+6) whereas for a 24 inch lead level, the sheet steel was in the bath for 46 inches (14"+14"+6). To be in the bath for two minutes, the line speed would be 19 inches per minute, for a lead level of 20 inches (38"/2 minutes) and 23 inches per minute for a 24 inch level. In order that the sheet steel be in the bath for five minutes, the line speed would be 7.6 inches per minute (38"/5 minutes) or 9.2 inches per minute for a 24 inch lead level.
The sheet steel would be preheated for five minutes if the speed was 8.5 inches per minute using a 20 inch lead level, or 7.5 inches per minute using a 24 inch lead level. It would be preheated for ten minutes if the line speed was 4.3 inches per minute using a 20 inch level or 3.8 inches per minute using a 24 inch lead level.
A decarburizing atmosphere is preferably delivered to the tube 80 at the intermediate points, that is, the pipes 81c, where the temperature is high. Gases, such as hydrogen and chlorine, to remove oxides from the sheet steel may be delivered via the pipes 81a. A small water vapor content may be used to effect surface and bulk decarburization. A protective gas to keep air away may be delivered via the pipes 81b, such protective gas may be 90% argon and 10% hydrogen. Their function is a reducing agent to clean the surface of the sheet steel. The gases are continually exhausted by way of the pipe in order to control pressure in the tube 80. The seal rolls 64 are protected from the hot exhaust gases.
A number of experiments were made in which the continuous processing concept embodied in the apparatus 10 was simulated. In such simulation, the sheet steel was processed by pretreating specimens and then placing them in a molten lead bath rather than continuously moving the sheet steel through the bath. In the following examples, "CQ-2" signifies commercial quality steel, 70 mils in thickness, made by Inland Steel by a hot rolled process; "TBB-2" signifies top and bottom blown sheet steel, 26 mils in thickness, made by Jones & Laughlin by a cold rolled process; "TBB-3" signifies top and bottom blown steel, 86 mils in thickness, made by Jones & Laughlin also by a hot roll process; and "TBB-4" signifies top and bottom blown sheet steel 33 mils in thickness made by Jones & Laughlin by a cold rolled process. The decarburizing step involved placing the sample in an atmosphere of 90% argon by weight and 10% hydrogen, with a dew point of +40° F. The temperature of the atmosphere was 1,550° F. An atmosphere with a higher or lower temperature would perform satisfactorily in such decarburization step. The samples were decarburized for the specified times. Then the samples were left for the specified times in a molten lead bath containing chromium, having the specified temperatures. The specimens made in accordance with the following showed no evidence of rusting in 200 hour salt spray tests:
______________________________________ Time in Bath Decarb. Bath TempSubstrate Time (min.) (min.) (°F.)______________________________________CQ-2 30 5 2000CQ-2 20 5 2000CQ-2 10 5 2000TBB-3 20 5 2000TBB-3 20 5 2000TBB-3 10 5 2000TBB-3 10 5 2000TBB-2 10 5 2000TBB-2 5 5 2000TBB-2 5 5 2000TBB-4 10 5 2000TBB-4 10 5 2000TBB-4 10 5 2100TBB-4 10 5 2100TBB-4 10 5 2100TBB-3 10 5 2000TBB-3 10 5 2000______________________________________
Cyclic oxidation tests were conducted on specimens made in accordance with the foregoing process under various conditions. These tests were run for 96 cycles, with each cycle consisting of a 55 minute exposure at 1,450° F. followed by a 5 minute forced air cool room temperature. The specimens were weighed before and after the test and weight gains per unit area were determined. For the following specimens, the weight gain per unit area was less than 0.63 mg/cm 2 , which is the weight gain per unit area of 409 stainless steel under similar conditions:
______________________________________ Time Decarb. in Bath Weight Time Bath Temp GainSubstrate (min.) (min.) (°F.) (mg/cm.sup.2)______________________________________CQ-2 30 5 2000 0.26CQ-2 20 5 2000 0.28TBB-3 20 5 2000 0.45TBB-3 10 5 2000 0.36TBB-2 10 5 2000 0.59TBB-2 5 5 2000 0.61TBB-4 10 5 2000 0.62TBB-3 10 5 2000 0.34______________________________________
A series of experiments were run in sealed capsules to determine the influence of titanium bath content on the formability of sheet metal samples that were co-alloyed with chromium in a short cycle process. All experiments were carried out in 2-inch diameter steel tubes that were evacuated and sealed. Each tube contained 1500 grams of lead, 10 grams of elemental vacuum grade chromium and commercially pure titanium in amounts varying from 0.1 to 1.0 grams. Four steel samples having dimensions of 1.5"×2"×0.30" and having an 0.125" diameter hole drilled at each end were strung on top and bottom support wires inside the 2" diameter tubes. Twisted wire spacers were placed over the support wires between each sample to provide separations. The substrate that was evaluated was an aluminum killed steel that was decarburized at 1450° F. in an Ar-10 v/o H 2 atmosphere with a dew point of +40° F. to produce a bulk carbon content of 0.005 w/o.
The sealed tubes were placed in a furnace at 2100° F. and were shaken vigorously after attaining a temperature at which all of the lead was molten. The vigorous shaking was continued until the tubes reached 2100° F. and for 10 minutes at that temperature. The tubes were then removed and air cooled. A series of runs were made in which the titanium bath additions were as follows:
______________________________________Ti bath Ti ConcentrationAddition in Lead Bath(grams) (ppm)______________________________________0 00.1 670.25 1670.35 2330.40 2670.45 3000.50 3330.55 3670.75 5001.0 667______________________________________
Surface composition analyses were made on the diffusion alloyed steels using standard energy dispersive spectroscopy microprobe procedures at an accelerating voltage of 25 KV. The surface chromium contents varied from 43.4 to 36.2 w/o while the surface titanium concentration increased to 2.4 w/o for the 667 ppm titanium bath concentration run. Examination of metallographically polished cross-sections that were etched with 5% Nitol showed that the thickness of the diffusion layer increased from 30 microns with no titanium bath addition to 92 microns with a 667 ppm titanium bath concentration. Microhardness measurements made with a diamond pyramid indenter at a load of 15 grams show that the hardness at a depth of about 10 microns from the surface increases with increasing bath titanium content from a value of 150 DPN with no titanium bath addition to a value of 235 DPN with a 667 ppm titanium bath concentration.
Bend tests were run on 0.5 inch wide ×1 inch long samples that were bent 180° around an 0.060 inch thick sheet (2T bend). The tension side of the bend surfaces was examined with a scanning electron microscope at a magnification of 1000×. Specimens that were produced in baths containing up to 267 ppm titanium showed no evidence of surface cracking. The grains on the surface showed slip lines that were approximately parallel to the bend axis. The specimen produced at a bath concentration of 300 ppm titanium showed very fine intergranular cracks that generally ran in a direction parallel to the bend axis. Examination of the cross section of these cracks showed that they do not extend more than 5 microns in from the surface. Salt spray tests performed in accordance with ASTM B117 for 16 hours showed no evidence of rusting in these microcracked areas.
The specimen produced at a bath concentration of 333 ppm titanium showed intergranular cracking that was more extensive than that in the 300 ppm titanium bath concentration run. Salt spray testing as performed above again showed no evidence of rusting in the microcracked areas.
The specimen produced at a bath concentration of 367 ppm titanium showed very extensive microcracking with fissures formed that extend well into the diffusion layer. Salt spray testing showed that rusting occurred at the bottom of the largest of these fissures. The specimens produced at even higher titanium bath concentrations showed more extensive intergranular cracking with more deep fissures formed. Thus it has been determined that to have a usable sheet metal product having good formability and the ability to maintain corrosion resistance in formed areas it is necessary to restrict the titanium bath concentration to a value of less than 367 ppm. This will also result in the formation of a surface alloy having less than 1 w/o Ti as a surface concentration and a cross-sectional microhardness at 10 microns from the surface of less than 200 DPN when these measurements are made by the methods described.
In certain instances, the chromium delivered by the chromium container 110 alone is not sufficient. Three additional chromium containers 150 provide a system for additional delivery of chromium. The containers are rectangular in plan, and are horizontally arranged and vertically spaced apart. The containers are attached to four brackets 151 arranged in a rectangle (two are shown in FIG. 2), the brackets being hung from a pair of cross bars 152. Each of the containers 150 includes a rectangular spacer 153, a pair of rectangular screens 154 and a pair of rectangular retaining rings 155. The space between the screens 154 and the spacer 153 is a compartment 156 within which chromium is placed. Each of the screens 154 consists of a fine wire mesh with a sheet of perforated metal on either side to define a relatively rigid sandwich. In an actual embodiment, each of the containers 150 had dimensions of 9"×15"×1" and contained about 10 pounds of chromium. This addition to the system increased the attainable surface chromium composition on the steel sheet to 24 w/o.
Immediately beneath the stack of three containers 150 is a length of tubing 160 that has a series of spaced perforations (not shown) through which a dry gas (inert or reducing) is passed. The gas exits through the perforations and percolates through the stacked chromium containers 150, providing agitation and increasing the solution of chromium in the molten lead.
To further facilitate chromium diffusion, two gas tubes 170 are mounted on the inlet tube 80 adjacent its exit end. The tubes 170 are located respectively on the sides of the steel sheet 12. These tubes are perforated at the top. Gas delivered to the tubes 170 by means of tubing 171 is discharged through the perforations and bubbles into the tube 80, thereby agitating the molten lead at the surfaces of the steel sheet.
The combination of the tube 170 next to the strip entry tube 80 and the tube 160 beneath the containers 150 causes the surface chromium concentration to increase. In a particular embodiment the concentration increased to 33 w/o.
What has been described therefore is an improved process and apparatus for diffusing chromium into the surfaces of steel products in coil form. In the specific embodiment, sheet steel is the product. However, the same principles are applicable to foil, plate and wire that are supplied in coil form. Also, while titanium is the preferred additive to the bath, other strong carbide formers could be employed. Furthermore, while a particular apparatus has been described as being capable of practicing the process, it is contemplated that substantial changes would be made in equipment that would perform the process on a commercial scale. | 4y
|
Cross-reference to Other Application
This application is a continuation-in-part of our copending application, Ser. No. 297,999, filed Oct. 16, 1972 now U.S. Pat. No. 3,804,935. A further related application is our application, Ser. No. 572,112, filed Apr. 28, 1975, which is a continuation of application Ser. No. 359,687, filed May 14, 1973, now abandoned, which was in turn a division of said application Ser. No. 297,999.
Background of the Invention
This invention relates to a unique process by which a particle board of substantial continuous solid thickness can be manufactured from any of a wide variety of comminuted lignocellulosic materials at a high, economical production rate despite the substantial thickness of the resultant product.
The lumber industry is presently concerned with the severe problem of disposing of vast amounts of bark and other wood wastes accumulating at sawmills in the lumber-producing regions of the world. Although limited amounts of the wastes may be used in paper production or as fuel, there remain huge quantities of bark, sawdust and shavings for which no adequate market presently exists. In the past disposal of such waste material by burning caused sufficient air pollution that the practice has now been prohibited in many areas. More recent types of disposal result in land pollution or land disfiguration, which is equally undesirable. Industries generating other types of lignocellulosic waste materials, such as bagasse from sugar cane processing, or straw, corn stalks, rice hulls, etc. are faced with a similar disposal problem.
A somewhat different but related disposal problem is faced by the railroads which every year are forced to remove and replace vast numbers of railroad ties which, because of decay, have become too weak for further useful service. Not only is the cost of manufacturing new railroad ties substantial, but there is no satisfactory way to dispose of the old creosoted wood ties without causing air or land pollution.
In the past a number of processes for manufacturing resin-bonded particle board products from various lignocellulosic waste materials have been developed in a an attempt to create a demand for sawmill wood wastes and certain other vegetable wastes. Several of these processes are exemplified in Elmendorf et al. U.S. Pat. No. 2,381,269 issued Aug. 7, 1945, Roman U.S. Pat. No. 2,446,304 issued Aug. 3, 1948, goss U.S. Pat. No. 2,581,652 issued Jan. 8, 1952 and Schueler U.S. Pat. No. 3,309,444 issued Mar. 14, 1967. A significant characteristic of most of the previous particle board manufacturing processes is that they form the particle board by the simultaneous application of heat and pressure to the material mixture in a relatively expensive hot platen press. This occupies the press and thus delays production for a period of time necessary to insure sufficient curing of any thermosetting binder used, or sufficient plasticizing of any thermoplastic binder used, the duration of such time period being a function primarily of the thickness of the compressed mixture. The temperature of the press cannot usually be raised significantly to shorten the period of time because unacceptable charring or scorching of the material may then result.
The aforementioned time delay raises a serious problem, because platen presses are such expensive items that they must be maintained at high rate of production continuously in order to enable particle board to be manufactured economically. This requirement has, up to now, forced the particle board industry to limit severely the maximum final thickness of the product to between about 178 and 3/4 inch. Such limited thickness requires only a fraction of an hour for curing or baking in a platen press under normal temperature conditions as opposed, for example, to at least 2 hours for material of 11/2 inch thickness. The present maximum economically practical board thickness of between about 178 and 3/4 of an inch, caused by the shortcomings of present production methods, has unfortunately foreclosed particle board from entering certain very substantial markets where the demand for particle board would certainly multiply many times and would thus help to relieve lumber shortages while contributing to the solution of sawmill wood waste and other lignocellulose waste disposal problems.
Despite the fact that the aforementioned problem of platen press inefficiency and the resultant economic limitation on the thickness of particle board has been clearly recognized by the industry for many years, no adequate measures have been devised for alleviating the problem. Goss, who recognized the problem 25 years ago as evidenced by the disclosure of his above-mentioned patent, attempted to alleviate the delay caused by the use of the heated platen press by removing the particle board mix prematurely from the platen press and finishing the curing process without the application of any pressure whatsoever. Such practice however does not yield as strong a bonded wood product as is obtainable with the simultaneous application of heat and compression. Accordingly there is presently no satisfactory production process available by which particle board of substantial continuous thickness, say one inch or greater, can be economically manufactured from lignocellulosic waste materials. Consequently particle board cannot readily be sold into such substantial markets as those for dimension lumber (e.g. studs, decking, framing lumber, etc.) or railroad ties, all of which require pieces of substantial continuous thickness, without requiring lamination of thin particle board pieces to produce a thick piece which is undesirable both from economic and structural standpoints. Moreover, due to the thickness limitation, particle board cannot economically be produced in pieces thick enough to be used as raw "logs" for sawing into lumber products of thinner dimension such as siding, grape stakes, etc.
Accordingly a great need presently exits for an efficient and economical particle board manufacturing process which utilizes a miximum amount of lignocellulosic waste matter and produces particle board pieces having sufficient continuous thickness and other characteristics to enable such product to be sold competitively into the above-described additional markets from which particle board is presently foreclosed, thereby establishing a requirement for a much greater percentage of lignocellulosic wastes than is presently being utilized and serving as a substitute for lumber in the marketplace so as to help alleviate lumber shortages.
SUMMARY OF THE INVENTION
The present invention is directed to a method for economically making a particle board of substantial thickness and density which eliminates the economic problem of limited thickness of the finished product, presently caused by efficiency limitations of the heated platen press, by eliminating completely the requirement for a platen press while retaining its advantages. The product may be manufactured utilizing virtually any tupe of comminuted lignocellulose material, including but not limited to such types as hardwoods or softwoods, particularly in the form of chips, shavings and sawdust, their barks, bargasse, straw, rice hulls, corn stalks, reeds, vegetable stems, cork and the like, or mixtures thereof. Such versatility with respect to the raw materials utilized is particularly applicable if the resultant product has no particular strength requirement, such as where the product is to be cut for siding, or where the resultant product has not tensile or bending strength requirement but rather only a compressive strength requirement. A requirement for a predetermined tensile or bending strength may dictate the use only of the more woody or fibrous lignocellulose materials. The process by which a highly densified, substantially thicker particle board product is economically produced comprises utilizing a plurality of special molds for holding the lignocellulose material, adhesive binders and other mixed ingredients from which the product is manufactured. Each mold includes a wholly insertable lockable pressure plate which, in combination with the mold, forms an enclosure surrounding the material. The process of the present invention comprises placing the mold in a cold press and applying pressure to the plate so as to substantially densify the mixture and compress the mixture to a predetermined substantial thickness and to a shape conforming with the interior of the mold. While the mold is under such initial compression, fasteners are applied to the mold which function to lock and retain the pressure plate in its compressed position regardless of whether or not the mold thereafter remains in the press. Consequently it is possible to transfer the locked mold as an assembly immediately from the press with no expansion or loss of internal pressure of the mixture, although the initial external pressure imposed by the press has been released. The material may then be bonded together by hardening the adhesive binder within the locked mold by curing, or by heating and subsequent cooling, depending upon the type or types of adhesive binders utilized, for the required period of time during which the internal pressure of the material gradually decreases. After hardening the binder or binders has been completed, the material is then removed by unlocking the pressure plate and dismantling the mold. The molds are built in such predetermined dimensions that the final molded particle board piece may thereafter be applied to its intended use without further processing or, alternatively, the molded piece may thereafter be sawed conveniently into smaller pieces of a size suitable for a particular intended use with only negligible waste of the product because the mold dimensions are preferably such as to provide enough excess only for sawing and sanding.
The steps, after initial momentary compression of the mixture, of locking the pressure plate in a compressed position and removing the mold and locked pressure plate assembly from the press with the compression still retained, permits the material thereafter to be heated in an oven for an extended period of time, to cure and/or plasticize the binder as the case may be, without thereby tying up an expensive platen press. Meanwhile the press, by far the most expensive single piece of equipment utilized in the process, is free to compress additional quantities of the material which may then immediately gbe added to the oven while the initial mixture is being heated. Since large ovens of the type contemplated for accepting multiple molds have a much lower acquisition cost than do a series of platen presses having the same total capacity, the economic disadvantages occasioned previously by the long heating times in palten presses required for thick particle boards is eliminated.
The ability of the foregoing particle board molding process economically to produce much thicker, and yet highly densified, particle board pieces makes possible the development of techniques for gainfully utilizing lignocellulosic waste materials for new products and new markets not heretofore considered feasible. In our copending U.S. application Ser. No. 297,999, filed Oct. 16, 1972, now U.S. Pat. No. 3,804,935 the use by means of the foregoing molding process of wood wastes, certain barks, bagasse, etc. in the manufacture of thick particle board pieces adapted to be cut into dimension lumber (for example, 2 × 4 studs) is disclosed. The same basic molding process can additonally be used to manufacture a wide variety of other products such as roof decking, grape stakes, decorative or protective siding, beams, columns, etc. It is significant that the inclusion of a substantial portion of bark, approximately 30% or more by weight, in the materials mixture provides a significantly higher degree of fire retardation in the resultant product than if solely wood sawdust, shavings and/or chips are used in the product. This can be very advantageous since fire retardation characteristics of any building material are usually critical.
One other extremely valuable application for the molding process is in the recycling of used railroad ties. By comminuting the wood from old rotted ties, mixing it with thermosetting and/or thermoplastic binders and then molding it by the above-described process into thick pieces having the dimensions required for ties, new ties can be readily produced from the old, thereby saving lumber and obviating the disposal of old ties. Since the old materials are already creosoted, there is an additional benefit in that no creosoting of the new ties need be performed. Of course new ties could alternatively be produced utilizing other lignocellulose wastes by the same molding method if desired.
It is therefore a principal objective of the present invention to provide a process by which highly densified particle board pieces of substantial continuous thickness can be produced economically by the application of pressure during the hardening of the adhesive binder without requiring the use of a heated platen press.
The foregoing and other objectives, features and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic flow diagram of an exemplary production process which may be utilized to manufacture a particle board product in accordance with the present invention.
FIG. 2 is a fragmented perspective view of a typical mold which may be utilized in the process of the present invention, with certain portions cut away for clarity.
FIG. 3 is a simplified, partially schematic side view illustrating the initial compression of the particle board material in a press, with portions of the mold cut away for clarity.
FIG. 4 is a simplified, partially schematic side view illustrating an alternative method of compressing the material.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 illustrates schematically the various steps which may be utilized in manufacturing a particle board product from lignocellulose materials in accordance with the process of the present invention. Although in FIG. 1 the lignocellulose waste materials are indicated as being bark, sawdust and shavings of the type which may be collected from sawmills, it should be understood that the process can utilize virtually any lignocellulosic matter as raw input material, including but not limited to all soft woods and hard woods, particularly in the form of sawdust, shavings and chips, their barks and other lignocellulose materials such as bagasse, straw, rice hulls, corn stalks, reeds, vegetable stems, cork, etc. Moreover, each type of lignocellulose material may be used alone or in mixture with one or more other types of lignocellulose material. Where tensile or bending strength of the resultant product is important to its application, such as with framing or dimension lumber, it may be desirable to utilize substantial amounts of only the more woody or fibrous types of lignocellulose materials which are best adapted to provide the required tensile strength, such as for example wood, redwood or cedar bark, bagasse, etc. The process described herein is by no means limited to any particular group of lignocellulose materials, however, since all are considered to be potentially useful in the manufacture of products where no substantial strength requirements need be met such as decorative or protective siding or wall covering.
The lignocellulose materials or mixtures are collected and transported to a manufacturing site and preferably dried by any suitable means to a moisture content of approximately 6% by weight, after which the material is placed in a hammer hog and comminuted into smaller particles of uniform consistency in the usual manner to render the material suitable for particle board manufacture. Following this initial preparation, the comminuted particles are blended with predetermined quantities of an adhesive binder or binders and wax respectively, the latter being used to waterproof the product. A substantial number of thermosetting or thermoplastic binders and waxes suitable for use in particle board production and for use in the present process are well known to the particle board industry and may be used in their usual proportions either alone or in combination with one another. A mixture of thermosetting with a thermoplastic binder is deemed preferable to maximize the adaptability of the product for sawing and sanding by minimizing its tendency to chip. The blending of the comminuted lignocellulose particles with the binder or binders and wax is preferably done with the aid of batch scales and conventional mechanical mixing apparatus.
The next step comprises placing measured quantities of the blended mixture in respective molds of the exemplary type shown in FIG. 2. A typical mold, designated generally as 10, comprises an elongate, channel-shaped member having a pair of flat, parallel upright side walls 12 and 14 connected at the bottom by means of bolts 15 to a base 16 which is joined at right angles with each of the walls 12 and 14. A group of spaced apertures 18 is formed in each of the side walls 12 and 14 respectively, each group running in a straight line above and parallel to the base member with opposite apertures being in transverse alignment with one another. At each end of the mold 10 a vertical row of transversely aligned apertures 20 is also provided in each of the side members 12 and 14. Through these latter apertures 20 a series of transverse bolts 22 are fastened to support respective end plates 24 which seal each end of the channel member. A pressure plate member 26 is provided having a length and width just slightly less than the inside dimensions between the two end plates 24 (only one of which is shown in FIG. 2), and the side walls 12 and 14 respectively. This permits the plate 26 to move freely in a vertical direction between the sides and end plates of the mold, thereby forming a mold enclosure of variable internal height. The interior length of the mold and the interior width between the side members 12 and 14 is dependent entirely upon the dimensions required for the finished product. The interior height of the ultimate mold enclosure, i.e. the interior are bounded by the channel member, the end plates 24 and the underside of the pressure plate 26, should be at least equal to or greater than the minimum thickness required for the finished product. The actual predetermined product thickness is regulated by the ultimate vertical position of the pressure plate 26, which is in turn determined by the location of the two rows of apertures 18. Accordingly, with the thickness of the plate 26 taken into account, the two rows of apertures 18 are spaced a sufficient distance above the upper surface of the base 16 that, when fastener bolts 28 are inserted transversely through the aligned apertures 18 and the pressure plate 26 is installed as shown in FIG. 2 with its upper surface abutting the underside of the bolts 28, the interior space between the plate 26 and the base member will be equal to the particular predetermined thickness desired for the pressed product.
It will be understood that fastening means other than bolts such as 28 might be utilized to lock the plate 26 into position, such as for example spring-loaded cams or lugs which automatically snap over the plate when the plate has been depressed sufficiently into the mold.
In the process of the present invention, the foregoing blended mixture of lignocellulose particles, binder and wax is weighed to a specific measured quantity preparatory to being placed in a respective mold 10 of the type just described. The height of the uncompressed mixture initially placed in the mold will of course be much greater than the final compressed thickness. Such uncompressed mixture should be spread evenly throughout the mold, its quantity being such that a predetermined pressure on the plate 26 is required to compress the mixture to the final predetermined thickness. The predetermined pressure is variable, again depending upon such factors as strength and density requirements for the finished product dictated by the particular intended application. As soon as the mold 10 has been filled with the measured weight of mixture, the pressure plate 26 is inserted into the mold atop the mixture and the mold is conveyed to a press. The press, indicated generally as 30 in FIG. 3, comprises an elongate, cylinder-actuated plunger 32 sized so as to fit loosely between the side and end walls of the mold 10 and designed to distribute a predetermined initial external pressure evenly along the top of the pressure plate 26. The bottom face of the plunger 32 includes a group of transverse notches 36 spaced so as to correspond with the spacing of the apertures 18 in the side walls of the mold 10.
Upon placement of the mold in proper position beneath the press 30, with the apertures 18 vertically aligned with the notches 36, pressure is applied to the plunger 32 which thereby forceably pushes the pressure plate 26 into the mold 10 and compresses the mixture 38. While the external pressure is being applied, the fastener bolts 28 are inserted through the respective apertures 18 over the plate 26, the insertion being made possible by the aligned notches 36. After insertion the bolts are tightened so as to prevent any spreading of the side walls 12 and 14 of the mold which might otherwise occur due to the internal pressure within the compressed material 38. The press 30 is then released, but the internal pressure existing within the mixture 38 is nevertheless maintained by the plate 26, now retained in its compressed position by the fastener bolts 28 as shown in FIG. 2. While the mold is in this condition it is removed from the press 30, preferably by transferring it forward on a conveyor such as 40. This frees the press 30 immediately to accept another mold of the same type, thereby permitting the compression and fastening steps just described to be repeated continuously.
As will be apparent to those skilled in the art, the press 30 may alternatively be of the inverted type wherein the cylinders are positioned beneath the mold and pressure is exerted upwardly against the surface upon which the mold rests. Other structural features of the press may also be variable, depending upon the specific structure of the mold and the type of fastening means employed.
A somewhat different type of press, also capable of accomplishing the foregoing compression step, is shown in FIG. 4. The mold 10 and compression process are the same as before, but in this case the press comprises a series of eccentrically mounted rollers 42, each fixed to a respective shaft 44. Initially the rollers 42 are situated with their eccentric portions facing upwardly to permit the mold 10 to be placed beneath the rollers. Thereafter the rollers 42, which are narrow enough to fit between the side walls 12 and 14 of the mold, are forceably rotated in a counter-clockwise direction as shown in FIG. 4 by torque applied to the respective shafts 44, thereby pushing the plate 26 down and compressing the material 38 as before. The fastener bolts 28 may then be inserted in the spaces between the rollers to retain the pressure plate 26. Other molding techniques employing the foregoing basic principles of initial compression and subsequent pressure retention may also be utilized and may be equally satisfactory.
After their removal from the press 30 the molds 10, with their pressure plates 26 still fastened in compressed position, are transferred to a curing oven. The oven is preferably of elongate configuration with multiple tiers of conveyors moving from an entry port to an exit port of the oven. The speed of the conveyors through the oven is regulated so as to insure a minimum heating period sufficient to properly cure and thereby harden any thermosetting binder used or plasticize any thermoplastic binder used, or do both if a combination of such binders is used, throughout the entire thickness of the material at the particular oven temperature utilized so as to effect ultimate bonding of the mixture throughout. Preferably the combination of oven temperature and time are sufficient to cause any substantial scorching or charring of the mixture. It will be readily understood by those skilled in the art that the maximum temperature and the time of heating may vary depending upon the particular lignocellulose materials utilized and their susceptibility to scorching, the type of binder of binders utlized, and especially the thickness of the mixture.
Upon their exit from the oven the molds are permitted to cool sufficiently to insure that hardening of any thermoplastic binder utilized is complete, the extent of such cooling also being a function of the type of binders utilized and the thickness of the mixture. Thereafter the molds may be dismantled by first loosening the bolts 15 on one side of the mold to relieve the pressure on the fastener bolts 28 and then loosening and extracting the bolts 28. Thereafter the bonded particle board product is removed from the mold and either used as is or, alternatively, sanded and/or cut as desired. Removal of the pressed product from the mold may be facilitated by spraying, smearing or otherwise depositing a suitable releasing agent such as oil or grease on the interior surfaces of the mold prior to filling it with the mixture, to prevent the product from adhering to the interior of the mold. The molds, pressure plates and fastener bolts respectively are returned to stations where they may be reused in the process.
It should be noted that the side walls and end walls 12, 14 and 24 respectively of the typical mold, as well as the base 16 and the pressure plate 26, are provided with a large number of small vent holes 46 which perform a two-fold purpose. First, during the initial compression of the material the vents 46 readily permit the escape of air in the mixture and thereby aid the compaction of the material. Second, during the heating step, the same vents 46 also permit the escape of water vapor. In addition, the mold 10 is preferably constructed of an aluminum alloy which is a good conductor of heat and thereby further aids both the heating and cooling processes.
The invention will now be described further with reference to the following examples showing how different particle board products may be prepared utilizing the foregoing molding method.
EXAMPLE 1
A mixtue of cedar sawmill waste containing sawdust, shaving and bark in the same proportions found at the sawmill site (including roughly at least 30-35% cedar bark by weight) is dried to a moisture content of approximately 6% , after which the cedar waste mixture is placed in a hammer hog and chopped into smaller particles of uniform consistency suitable for particle board manufacture. The comminuted waste material is blended with a thermosetting phenolic resin binder (e.g. Dry Monsanto Resinox Compound 673 or 736), a thermoplastic binder (e.g. Vinsalyn, manufactured by Hercules, Inc. of Wilmington, Delaware) and a wax (e.g. Hercules brand Paracol 800N). The proportions are such tha the resultant mixture comprises approximately 91.75% cedar waste, 3.75% thermosetting binder, 3.75% thermoplastic binder, and .075% wax by weight. The blended mixture is placed in a mold of the type described, preferably having an interior width of 111/2inches and an interior length of 24 feet. The two rows of apertures 18 in the mold are positioned such that, with the pressure plate 26 installed with its upper surface abutting the underside of the bolts 28, the interior space beween the plate 26 and the base member 16 is 11/2plus inches. About 135 pounds of the foregoing blended mixture of cedar waste, binders and wax are spread evenly in the mold. In its uncompressed conditon the mixture fills the mold to a height of approximately 8 inches. The pressure plate 26 is then inserted into the mold atop the mixture and the mold is conveyed to the press where an initial external pressure of about 1,200 psi is applied to depress the plate. The fastener bolts 28 are inserted and tightened, and the external pressure imposed on the plate by the press is then released. The mold is removed from the press as an assembly and transferred to an oven where it is baked for about two hours at a maximum oven temperature of approximately 450° F. to avoid scorching, 425° F. being preferable, after which the mold is removed from the oven and permitted to cool in ambient air until the compressed material is below 200° F., which takes about 1/2 hour. Thereafter the mold is dismantled and the product removed. The product is cut and sanded so as to produce 8 foot length of nominal two-by-fours, two-by-sixes or two-by-twelves as desired, the actual thickness of such pieces being 11/2 inches in accordance with present dimensional lumber standards.
A board prepared in accordance with the foregoing example is exposed directly to a blow torch flame continuously for approximately 30 seconds without igniting. A board prepared in the same manner but without including any cedar bark is ignited immediately when similarly exposed to the blow torch flame.
EXAMPLE 2
The process is the same as that described in Example 1 except that no thermoplastic binder is used and the thermosetting binder constitutes 71/2% by weight of the blended mixture. The resultant product has characteristics comparable to those of the product of Example 1 except that it has a somewhat greater tendency to chip and thus is not as well adapted to be sawed.
EXAMPLE 3
In this example the process is essentially the same as in Example 1 except that no cedar waste is used and instead the lignocellulose materials constitute any one of the following redwood wastes:
a. 100% bark;
b. 90% bark, 10% sawdust;
c. 80% bark, 20% sawdust;
d. 70% bark, 30% sawdust;
e. 60% bark, 40% sawdust;
f. 50% bark, 50% sawdust.
The mixture is molded in pieces of 11/8 inch thickness in molds 71/2 inches wide and 8 feet long, about 28 lbs. of mixture being required per mold. Upon removal from the mold, the product is sawed into eight-foot pieces of bevel siding having a thickness from 1/4 inch on the narrow edge to 3/4 inch on the wide edge, the extra 1/8 inch being consumed in sawing and sanding.
EXAMPLE 4
The process and blended mixture are the same as in Example 3 except that the redwood waste is replaced by a mixture of gum tree and oak shavings, chips and bark in the same proportions as such waste is normally found at the sawmill site. Pieces of bevel siding are cut from the resultant molded product.
EXAMPLE 5
The process and blended mixture are essentially the same as in Example 1 except no cedar waste is used and instead the lignocellulose material is comminuted creosoted wood from used railroad ties. The blended mixture is pressed in molds designed to produce pieces of either 9 or 18 foot lengths having a rectangular cross-section of 7 inches thick by 9 inches wide. About 300 lbs. of undried mixture or 230 lbs. of dried mixture are required per 9 foot mold. If the mixture is undried, substantial water as well as air through the vents 46 during the compression step. Oven time, at 425° F. oven temperature, is approximately 4-5 hours. Oven temperature could be increased above the scorching point in this particular application if needed to accelerate heating, assuming that some surface scorching of the railroad ties would probably not be objectionable. Lignocellulose materials from another than used ties could also be used if desired, either alone or in combination with the creosoted wood. Creosote may be added to any of the foregoing mixtures if needed to insure wood preservation, more creosote obviously being needed if fresh lignocellulose materials are used than if recycled ties are used. The resultant ties will be creosoted throughout, as opposed to lumber ties which are creosoted only adjacent their outer surfaces.
EXAMPLE 6
The process is the same as in Example 1 except that an elongate stiffener material such as wire, fiberglass rods or expanded metal is placed into the mold together with the blended mixture prior to compression so as to produce a stiffener molded product.
The examples, terms and expressions which have been employed in the foregoing abstract and specification are used therein for description and are not intended in any way to limit the scope of the invention nor exclude equivalents of the methods and features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow. | 4y
|
RELATED APPLICATION
This application claims priority from U.S. provisional patent application No. 61/225,264, titled “Method for Extraction of Base Metal Value from Oxide,” filed on Jul. 14, 2009, and which is incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
1. Field of Invention
The present disclosure relates to recovery of base metal values, such as nickel, cobalt, copper and the like, from oxide type materials.
2. Description of Related Art
There are several methods available to those skilled in the art for the extraction of nickel and other base metals from oxide ores, and especially from laterites. These conventional methods generally have several disadvantages that render producing nickel from laterites a difficult task.
The choice of a hydrometallurgical route for nickel laterites is highly dependent on ore characteristics because no conventional process can be generally applied thoroughly. Parameters such as flexibility, high recovery, and savings of energy, reagents and water are not only desired, but are essential to a viable hydrometallurgical plant. There are several leaching options available for nickel laterites, such as the Caron process (roasting/reducing/ammonia-based leaching) or the pressure acid leaching (PAL or HPAL—high pressure acid leaching), but these leaching options are generally associated with high operational and capital costs. There are other options being developed, trying to reduce those costs, such as atmospheric acid leaching in agitated tanks or heap leaching (McDonald and Whittington, 2007; Whittington, McDonald, Johnson and Muir, 2002).
Even though there are commercially available hydrometallurgical options for nickel laterites and plenty of development in the field with good technical background, these options are still costly. High capital and economical costs are related to the number and complexity of unit operations that are currently needed for nickel extraction and their complexity. Researchers have been struggling to find solutions for issues such as high acid consumption, impurities extraction, solid/liquid separation, among others. Hydrometallurgical purification of nickel often deals with high volumes and low concentration of valuable metals, thus considerably increasing overall operational costs.
High acid consumption is one of the main components of operational costs of laterite leaching. Nickel and the other base metals are usually bonded in ferruginous ores, as in limonites, or in saprolite matrixes, both being rich in magnesium. Accordingly, in order to effectively leach those elements, iron and magnesium need to be leached, both iron and magnesium being available in high amounts and thus increasing overall acid consumption. That is the main issue with conventional atmospheric or heap leaching operations, as seen throughout the available literature, for example in patent applications WO/2010/000029, WO/2009/146518, WO/2009/018619, EP1790739 and many others. An excess of acid is needed to achieve high extractions of payable metals. It is known for those skilled in the art that high pressure acid leaching (PAL or HPAL) can deal with the high ferruginous ores, as all iron is hydrolyzed, but magnesium remains an issue.
Document WO 2010000029 (BHP Billiton SSM) teaches a process for the recovery of nickel and cobalt from a nickeliferous oxidic ore by heap leaching and/or atmospheric agitation leaching, the process generally including mixing a sulfur containing reductant selected from reductants that do not include copper into a nickeliferous oxidic ore, leaching the reductant/ore mixture with an acidic leach reagent to produce a pregnant leach solution including nickel, cobalt, iron substantially in a ferrous form and other acid soluble impurities, and recovering the nickel and cobalt from the pregnant leach solution.
WO 2009146518—(VALE S.A.) describes a process of recovering nickel and cobalt and regenerating the main raw materials, the process including granulometric separation, leaching, neutralization, mixed hydroxide precipitate (MHP) production in only one stage and the pressure crystallization of magnesium sulphite. The process proposes a way to recover nickel and cobalt from laterite ores through atmospheric and heap leaching with staged addition of ore—by size separation—and H 2 SO 4 , decreasing the nickel losses, simplifying the neutralization circuit and producing a more purified MHP. The present process route is employed for nickel extraction, including the one from high magnesium containing lateritic ores.
WO 2009 018619 (BHP Billiton SSM) describes an atmospheric leach process in the recovery of nickel and cobalt from lateritic ores, the process including providing limonitic and saprolitic ore fractions of a laterite ore, separately slurrying the limonitic and saprolitic ore fractions to produce a limonitic ore slurry and a saprolitic ore slurry, separating any limonitic type minerals from the saprolitic ore slurry to produce a saprolitic feed slurry, milling or wet grinding the saprolitic feed slurry, leaching the limonitic ore slurry with concentrated sulfuric acid in a primary leach step, introducing the saprolitic feed slurry to the leach process in a secondary leach step by combining the saprolitic feed slurry with the leached limonite slurry following substantial completion of the primary leach step, and releasing sulfuric acid to assist in leaching the saprolite feed slurry, wherein the saprolitic feed slurry is substantially free of all limonitic type minerals before it is introduced to the leach process.
EP 1790739 (Companhia Vale do Rio Doce) teaches a process for extraction of nickel, cobalt, and other metals from laterite ores by heap leaching, and of the product obtained as well, characterized by the fact that it is comprised of crushing, agglomeration, stacking and heap leaching stages, with this last stage being a continuous, countercurrent, heap leaching system with two or more stages, comprised of two phases, one of which is composed of the ore, or solute, and the other is composed of the leaching solution, or solvent, which are supplied at opposite ends of the series of stages and flow in opposite directions. Upon cessation of leaching in the last stage, its solute is removed and a new stage is introduced at the first position, formed by new ore to be leached by the solvent solution, which is introduced from the last stage, percolating or flowing through all the previous stages until it reaches the first stage, being separated if loaded with target metals.
Another issue with acid leaching of oxide base metals ores is neutralization and solid-liquid separation. A neutralizing agent, such as, but not limited to, lime, limestone or magnesia, is needed to increase solution pH and hydrolyze some impurities from solution. This operation produces hydroxides, as ferric hydroxides, that make solid-liquid separation very onerous. Rheology is often a problem too. To avoid that problem, high dilution of the solution is needed, and higher volumes of poorer solution are needed to be purified.
Effluent treatment could also be an issue, as magnesium levels can be prohibitive. There are several methods for removing magnesium from solution, but all come with a high cost. Solid residue is also not very stable and needs large tailings ponds.
One patent application, WO/2009/026694, from Berni et al, attempts to address the above-discussed issues by contacting HCl gas and oxide ore. This patent application uses the fact that iron, aluminum and magnesium chlorides can be selectively decomposed from payable metals, then recovering HCl and producing a much cleaner solution to treat and that is free of iron, magnesium, manganese or aluminum. This technique also produces a stable solid residue and in smaller quantity.
The major hurdle on HCl usage for base metals extraction has normally been focused on the need to use highly corrosion resistant materials and to control hydrogen chloride gas emissions.
Gybson and Rice (1997) showed the advantages of hydrochloric acid usage for nickel laterite extraction. There is substantial literature examining the use of hydrochloric acid and several new processes proposed in recent years based upon novel chemistry only achieved in strong chloride liquors.
SUMMARY
Various aspects of the present invention bring a controlled process that promotes in-situ generation of HCl, reducing corrosion problems, thus reducing capital costs. Ferric or ferrous chloride is agglomerated with the ore and later submitted to selective hydrolysis of the iron chloride. The agglomeration and hydrolysis depend on the iron oxidation stage and generates in-situ HCl that attacks base metals oxides, forming metal chlorides. These chlorides are later solubilized in water, generating an iron and aluminum-free leach effluent. This effluent can then be submitted to any known and more simplified purification technology because there is no longer a need for an iron removal stage.
Aspects of this invention reduce the impact of using direct HCl to leach oxide ores by indirect hydrochlorination using ferric or ferrous chloride. As a result, the use of HCl is limited to a smaller unit operation, reducing overall costs and maintenance.
A method for recovering base metal values from oxide ores is provided according to various aspects of the current invention. According to various aspects, the ore includes a first metal selected from the group consisting of at least one of iron, magnesium and aluminum and a second metal selected from nickel, cobalt and copper. The method may include the steps of reducing ore particle size to suit the latter unit operations, favoring contact of the metal elements, contacting the ore with at least one of ferric or ferrous chloride, hydrated or anhydrous, to produce a mix of ore and iron(II or III) chloride, subjecting the mixture of the ore and ferric or ferrous chloride to enough energy to decompose the chlorides into hydrochloric acid and a iron oxide, preferably hematite, contacting the readily-formed hydrochloric acid with the base metal oxides from the second group described above, forming their respective chlorides, and selectively dissolve the produced base metal chlorides, leaving the metals from the first group as oxides and in the solid state. The method may also include methods of recovering the dissolved base metal from aqueous solution.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustration of a method for extracting base metals from laterite ore, according to various aspects of the present invention;
FIG. 2 is a graph illustrating Gibbs free energy behavior with temperature for indirect hydrochlorination utilizing ferric chloride, according to various aspects of the present invention; and
FIG. 3 is a graph illustrating Gibbs free energy behavior with temperature for indirect hydrochlorination utilizing ferrous chloride, according to various aspects of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Aspects of the present invention relate to a process for recovering base metal values from oxide materials, specifically metals found, e.g., in laterite ores, such as nickel, cobalt and copper.
In accordance with aspects of the present invention, oxide materials such as, for example, laterite ores, are mixed with ferric or ferrous chloride to produce an iron, aluminum and magnesium-free solution that carries base metals chlorides, such as nickel, cobalt and copper, through indirect hydrochlorination, as described by equations (1) to (3) below.
FIG. 1 is an illustration of a method 100 for extracting base metals from laterite ore, according to various aspects of the present invention. As described in more details below with respect to FIG. 1 , the oxide material may be initially crushed or granulated to liberate the oxide base metals prior to mixing with ferric or ferrous chloride, as indicated in step S 101 . The particle reduced oxide material may be mixed with ferric or ferrous chloride and agglomerated with a mineral acid if necessary, as indicated in step S 102 . According to various aspects, the mix of particle-reduced ore and ferric or ferrous chloride is contacted with enough wet air at high temperature to convert base metals into chlorides and iron, and aluminum and magnesium to their respective oxides, as indicated in step S 103 . Gibbs free energy behavior for hydrochlorination with using both ferric chloride and ferrous chloride is illustrated in FIGS. 2 and 3 . To obtain an iron-, aluminum- and magnesium-free solution, water may be added to the converted ore at a pH of between about 8 and 2. The pH can be controlled using a mineral acid such as, for example, hydrochloric acid, in order to avoid the newly formed oxides from leaching.
In accordance with aspects of the present invention, after solid-liquid separation such as illustrated in step S 104 , the solution becomes therefore iron-, aluminum- and magnesium-free. The solubilized base metals can then be purified into sellable products by various methods known by those skilled in the art. The solid portion of the solid liquid separation, after proper washing of residual solution, may be submitted to a high intensity magnetic separation to separate hematite from other oxides. Neutralization may optionally be needed. Hematite may then be contacted with hydrochloric acid to produce ferric chloride and water. In order to produce ferrous chloride, a reducing agent, such as, but no limited to, iron may be added to the system.
In accordance with aspects of the present invention, ore is extracted from the mine to provide beneficiation plant a run-of-mine. The run of mine may then be prepared to be fed into the extraction plant. For that, it is preferable that the size of the ore is reduced to an appropriate size to liberate base metals oxides for proper indirect hydrochlorination and efficient solubilization. In accordance with aspects of the present invention, ore size may be kept between 2 mm and 0.050 mm, and optionally less than 0.5 mm. These sizes can be obtained by different conventional unit operations well known and described in the literature, such as, but not limited to, crushing and grinding. Ore may be separated in two fractions: a first one that is rich in nickel and having about the sizes described above, and another one that is poor in nickel. The fraction of ore that is poor in nickel may be discarded. It should be noted that the above-discussed fractions and sizes are exemplary, and those skilled in the art may provide more or less fractions of varying sizes.
In accordance with aspects of the present invention, after size reduction, the ore is mixed or agglomerated with ferric or ferrous chloride sufficient for total hydrochlorination of payable base metals. Ferric or ferrous chloride can be added in the ratio between, for example, 0.05 and 1.5 times the ore mass, and optionally between 0.1 and 0.5 times the ore mass. Water or a mineral acid may optionally also be added to improve agglomeration. If ferrous chloride is used, an oxidizing agent may also be added to the ore, such as, but not limited to, oxygen, potassium permanganate, ozone or hydrogen peroxide. The oxidizing agent may be added in a similar mass ratio range as ferrous chloride. It should be noted that ferric or ferrous chloride may be obtained by any available source.
In accordance with aspects of the present invention, the oxidizing agent reacts with ferrous chloride, forming hematite and HCl, as shown by the reaction below.
2FeCl 2 +1/2O 2 +2H 2 O→Fe 2 O 3 +4HCl (1)
In accordance with aspects of the present invention, the temperature range needed for this reaction ranges may be between 60° C. and 600° C., optionally between about 100° C. and about 300° C. for kinetics reasons. Residence time may range between 0.5 hour and 12 hours, optionally between 1 hour and 2 hours.
When using ferric chloride, an oxidizing agent may not be necessary. The properly agglomerated ore is taken to a hydrolysis stage, usually but not limited to a kiln, where the ore is submitted to conditions under which ferric and/or ferrous chloride is decomposed, producing stable hematite or other hydrated iron oxide, and HCl. During this step, the agglomerated ore is then submitted to elevated temperature, ranging between 60° C. to 600° C., for between a minimum of about 5 minutes and a maximum of about 24 hours. Sufficient water may need to be added, but enough water may already be present in ore moisture.
The decomposition reaction of the ferric chloride can be described as shown below.
2FeCl 3 +3H 2 O→Fe 2 O 3 +6HCl (2)
The temperature range needed for this second reaction mechanism may ranges between 60° C. and 600° C., and optionally around 150° C. to 350° C. Residence time requirements may be the same as the residence time requirements for ferrous chloride.
Accordingly, it is clear from the reactions expressed by equations (1) and (2) that enough water must be provided to the system in order to ensure proper hydrolysis. Ore-free moisture may thus be controlled to be between 1% and 20% (m/m), and water vapor may also be added to the system in order to provide enough water.
The HCl generated as described above in equations (1) and (2), inside the agglomerated ore, is used to form value base metal chlorides, as shown below for a generic transition metal M that forms an oxide MO:
MO+2HCl→MCl 2 +H 2 O (3)
According to various aspects of the current invention, the newly formed chlorides are soluble in water, but the metal M such as iron, aluminum and magnesium is already in a stable form as an oxide. Accordingly, equation (3) would yield an iron, magnesium and aluminum-free effluent, easily purified by various methods available in the literature and known by those skilled in the art.
According to various aspects of the current invention, after hydrochlorination as described before is terminated, the ore could be stacked in a heap and leached with acidified water, with a pH of at least 7. Any mineral acid may be used such as, for example, sulfuric acid, nitric acid or hydrochloric acid. According to various aspects, the acid content may be increased up 100 g/L, but the pH may be kept between about 1 and about 3. Leaching solution could be recycled, with acid make-up, to increase payable metals concentration. Another possible way of solubilizing the payable metals is through agitated tanks, keeping pH at the same ranges. Residence times may be determined to be between about 5 minutes and about 24 hours, and optionally between 30 minutes and 120 minutes. Also, the solution may be heated to increase solubilization kinetics, and the percentage of solids may be kept between about 5% and about 50%, depending on how concentrated the solution needs to be. Optionally, the percentage of solids may be in the range 15% and 35%. It should be noted that any other form of solubilization known by those skilled in the art may also be employed.
According to various aspects of the current invention, after proper solubilization and solid-liquid separation, any method of downstream purification may be used. According to various aspects, there is no need of an iron removal stage and an aluminum removal stage, or of effluent treatment for magnesium or manganese removal, because these elements were already stabilized as oxides in the furnace.
According to various aspects of the current invention, tailings produced from the solid-liquid separation may be contacted with a high intensity magnetic field, after first been washed to remove residual base metals solution. Neutralization may also be needed, but may not be necessary. The magnetic field separates hematite from other oxides. It should be noted that other separation methods, known from those skilled in the art, can be used instead of a magnetic separator.
According to various aspects of the current invention, in order to produce ferric or ferrous chloride, hematite may be contacted with hydrochloric acid, producing the chosen iron chloride, as described by equations below:
Fe 2 O 3 +6HCl→2FeCl 3 +3H 2 O (4)
Fe 2 O 3 +Fe+6HCl→3FeCl 2 +3H 2 O (5)
It should be noted that any reducing agent may be used to form ferrous chloride, such as, for example, metal iron (Fe). Ferric chloride may also be produced by contacting metal iron with hydrochloric acid in oxidizing conditions. Hydrochloric acid may be produced by reacting a chloride salt, such as sodium chloride, potassium chloride, with an acid, such as sulfuric acid. According to various aspects, potassium chloride may be used as a chloride salt. Reacting potassium chloride with sulfuric acid produces dry hydrochloric acid (e.g., free of water) and potassium sulfate, a useful byproduct.
According to various aspects of the current invention, one of the advantages of this technology is that HCl is used in a controlled form, reducing the need for expensive equipments, Cheaper construction materials and simpler equipments are needed. Gas-solid interaction is not a big concern because HCl is generated within the agglomerated ore, diffusing throughout the material. That way, a simple kiln such as, but not limited to, a rotary kiln, can be employed at the hydrolysis stage, thus reducing capital costs. Downstream equipments are also simpler because no high chloride solution will be produced.
Various aspects of the process according to the current invention provide the advantage of base metal extraction with chlorides while reducing one of its drawbacks which is the need of special engineering and materials of construction.
Further, the following features can also summarize the benefits of various aspects of the present invention: i) increased extraction of value metal, such as copper, nickel and cobalt; ii) better deposit exploitation; iii) reduced acid consumption; iv) better settling properties of pulp; v) reduced consumption of flocculants; vi) no need for saprolite/limonite separation; vii) controlled HCl usage; viii) simple engineering; ix) simple operation; and x) reduced capital costs. The following examples are illustrative of the experimental process according to various aspects of the current invention:
EXAMPLE 1
100 g of a limonite-type ore is mixed with a laterite ore comprising 1.03% Ni, 35.06% Fe, 12% Si, 4.05% Mg, 1.94% Al, 0.64% Mn and 0.065% cobalt, and with 10 g of ferric chloride hexahydrated for 180 minutes and 400° C. Extraction results are in Table 1 below.
TABLE 1
Extraction Results for Example 1
Element Extraction
Al
Co
Fe
Mg
Mn
Ni
0.10%
98.10%
0.50%
0.30%
0.40%
95%
EXAMPLE 2
A laterite charge is subjected to a 90 minute indirect hydrochlorination at 300° C. with wet air injection. The sample contains 2.01% Ni, 0.073% Co, 49.1% Fe, 3.07% Mg and 06% SiO 2 . Extraction results are show in Table 2 below.
TABLE 2
Extraction Results for Example 2.
Element Extraction
Al
Co
Fe
Mg
Mn
Ni
0.08%
94.12%
1.50%
0.21%
0.29%
96.70%
While this invention has been described in conjunction with the exemplary aspects outlined above, various alternatives, modifications, variations, improvements, and/or substantial equivalents, whether known or that are or may be presently unforeseen, may become apparent to those having at least ordinary skill in the art. Accordingly, the exemplary aspects of the invention, as set forth above, are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention. Therefore, the invention is intended to embrace all known or later-developed alternatives, modifications, variations, improvements, and/or substantial equivalents. | 4y
|
BACKGROUND
1. The Field of the Invention
This invention relates to athletic training equipment and, more particularly, to novel systems and methods for use in basketball shooting practice.
2. The Background Art
Basketball is a common sport among youths and adults alike. Most amateur athletes (basketball players) develop and practice their shooting techniques without a coach. Like sandlot baseball, basketball is often played with a minimum of equipment, no officiating, no coaching and a makeshift court. Basketball is often played on a driveway or in a schoolyard. Basketball may be played as a solo practice event or one-on-one between friends. Informal teams may form if enough players are present. Individuals learn how to shoot a basketball by watching friends. Sometimes, questions or comments may be exchanged. However, knowledge and skill are limited. Information exchanged or techniques observed are often erroneous. Thus, any skills developed in reliance on informal play are questionable. Practice of those skills may simply solidify poor techniques.
Some players have a coach accessible. Basketball teams are typically coached at junior and senior high schools. However even there, a coach cannot average more than a few minutes per day in individual instruction with a player. Moreover, a coach has little opportunity to carefully observe an individual. Seldom will a coach see a player take the same shot numerous times in succession. Individual players also practice alone, but spend little practice time being observed by a coach. College and professional teams alone have coaches who can spend time observing and correcting each player.
Players need knowledge of what to do. They need to know proper techniques. They also need some way to know whether they are executing the techniques properly during practice. Finally, players need a reminder with each shot, until the proper technique, properly executed is a habit.
Practicing to aquire a skill is most effective if a proper technique is properly executed numerous times. Among other things, practice strengthens required or useful muscles. Practice also creates control. However, practicing a wrong technique or executing a technique improperly teaches wrong technique. Bad practice may be worse than no practice. Poor practice limits a player's ability to perform or to improve in any sport or activity.
Practice should employ proper technique for each shot. Proper technique should be the only technique practiced. The proper technique should be executed properly every time. The technique should be repeated numerous times. A youth aspiring to play collegiate or professional basketball should shoot approximately 300 shots per day. Those shots should be done with proper technique, properly executed, until the technique is habit, even reflex. Control is a direct result of this repeated, identical, correct, habitual positioning and movement of body members.
Muscles are also developed with practice. Repetitions or "reps" are part of any strength training. Proper strength comes from repeating a motion against some resistance, such as a weight, or the body's weight. Muscles should be properly "loaded." That, is they should encounter the proper resistance forces. If additional loading is added, it must be carefully directed to develop muscles in proper balance. A proper balance of the strengths of cooperating muscles comes from repeating the motions associated with a desired skill.
A proper range of motion comes from each body member traversing its full path of motion associated with the desired skill. Motions by a body member are more likely to be correctly executed if begun from a proper position. However, young players and untrained participants may fail to practice proper techniques such as positioning and motion, moreover, they are unlikely to know what they are. Therefore, such individuals will lack both the positioning of the arms, hands and shoulder complex. They will lack muscular development required to shoot a basketball forcefully and in a proper direction required to make a goal shot.
"Neuromuscular memory" is an expression used to describe the development of habits and muscles with practice. It is the sum of habitual patterns that become part of any player's technique and conditioning after frequent and numerous repetitions of motions. Thus, neuromuscular memory is a combination of balanced muscular strength, range of motion and muscular control. It is developed by numerous, frequent repetitions of the physical positioning and motion associated with a properly executed technique for an athletic skill.
No reliable method is available without professional coaching to provide the necessary practice of proper techniques. The individual without a coach relies only on happenstance to learn and practice proper techniques.
BRIEF SUMMARY AND OBJECTS OF THE INVENTION
In view of the foregoing, it is a primary object of the present invention to teach a basketball player the proper positions and motions of arms, hands and shoulders when shooting a basketball. Another object is to remind the participants constantly and in a consistent fashion of those necessary positions and motions during recreation, individual practice, team practice and games.
Another object is to urge proper positioning and motion with every shot. One object of the invention is to position the "throwing hand" of a basketball player properly before a shot. Another object is to position the hand, associated forearm, and upperarm in proper relationship to one another for executing a shot properly. Another object is to urge a player to lift the upper arm and extend the forearm away from the upperarm. Another object is to urge the player to rotate the forearm with respect to the upperarm to position the hand and forearm above and forward of the respective shoulder. Another object is to position the arm of a player to control subsequent motion and follow-through.
Another object is to provide a safe, simple method and apparatus useful in all types of basketball practice environments. Another object is to provide an apparatus organic to (completely self contained with) the user. Other related objects are to minimize the complexity of the apparatus, to avoid bulky hardware, and to avoid requiring any fixed exercise stations.
When shooting a basketball, arm and hand positions at the beginning of a shot are critical. Initial positions and the physical limitations of body members effectively direct subsequent motions. Young players often shoot a basketball with two hands, or "throw" it with a motion similar to a "shot put." In a shot put, the hand moves from the shoulder and is extended the length of the arm. The hand and shoulder are together when the upperarm and forearm are hinged closed from the elbow. Usually, as the upperarm and forearm open, the shot is released.
By contrast, in basketball, the "throwing hand" should be positioned directly above the shoulder and higher than the head. The upperarm and forearm should not be closed together. Neither the upperarm nor the forearm should cross in front of the face of a shooting player. The hand should swing in a long arc on the forearm, the forearm pivoting about the elbow. Before a shot, the elbow should be displaced and moved forward of the head. That is, the elbow should be positioned above and in front of the shoulder. The upperarm is elevated during most of the motion of the forearm. Unfortunately, many players do not ever learn this positioning correctly. They do not repeat this positioning and motion in practice. They have no way of assessing their own performance of the correct positioning and motions.
A feature of an apparatus consistent with the foregoing objects is a brace having a base securable to an arm of a user or player. A yoke attached to one end of the base extends away from the base. The yoke may be fixedly attached or movably attached to the base. During use, the yoke and base remain in fixed relation to one another.
The yoke orients the forearm of the user with respect to an associated upperarm of the user. The yoke controls both relative closure, relative rotation, and extension of the forearm and the upperarm of the arm used for shooting. The yoke restrains the forearm from closing toward the upperarm beyond a predetermined angle. The yoke also urges the forearm into the proper rotational position with respect to the upperarm. The yoke also orients the shoulder complex to the proper angle.
The base may be configured to be secured to either the forearm or the upperarm (first member) of the arm of a user. As the forearm closes toward the upperarm, the yoke receives the second member (either upperarm or forearm) to which the base is not attached.
The yoke thus urges the second member to stop at a predetermined angle in the plane formed by a centerline through the forearm and a centerline through the upperarm. The yoke also urges a rotation of the plane, by urging rotation of the forearm to a predetermined position with respect to the upper arm.
The base and yoke may be fabricated separately and fastened together. An adjustable link may be interposed between the base and yoke for adjusting their relative positions including relative angles. Alternatively, they may be cast or molded monolithically.
A strap may be used to secure the base to the arm of the user. The strap may be configured with ends which may be selectively separated and attached with a fastener. A hook-and-loop fastener may be used to attach the ends at different positions, orientations and lengths to fit the arm of a user. Buckles, or "D-rings" with straps, neoprene tensioners, ratchet clips, terry bands/straps may also be incorporated.
Advantages of the apparatus include gauging for a user the correct positioning of the shooting hand, with its associated forearm, upperarm and shoulder. Another advantage is repeatability of the practiced positioning and motions of a user. Another advantage resulting from the foregoing is feedback to a user immediately with each shot. Another advantage is the provision of virtually perfect solo practice without a coach.
Another advantage is increased leverage of a basketball against the muscles in the arm and shoulder. A related advantage is creation of a proper length of the stroke of the hand of a user during a shot. Another related advantage is strengthening muscles due to the increased leverage. Another advantage is physiological or psychological "motor memory" occurring. Moreover, another advantage over strength training is that all muscles used in the body during a shot are exercised in proper relationship, being exposed to the proper forces and moving through the proper range of motion, increasing performance and theoretically avoiding muscular/boney damage from improper, repetitive movement.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects and features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawings in which:
FIG. 1 is an isometric view of one presently preferred embodiment of an apparatus in accordance with the invention;
FIG. 2 is a top plan view of the apparatus of FIG. 1;
FIG. 3 is a front end elevation view of the apparatus of FIG. 1;
FIG. 4 is a right side elevation view of the apparatus of FIG. 1;
FIG. 5 is a left side elevation view of the apparatus of FIG. 1;
FIG. 6 is a back end elevation view of the apparatus of FIG. 1;
FIG. 7 is an isometric view of the apparatus of FIG. 1 including ventilation slots and a pad attachable to the base;
FIG. 8 is an isometric View of the apparatus of FIG. 1 provided with a shim and associated attachment layer for changing the size of the effective inside radius of the base;
FIG. 9 is an isometric view of an apparatus having open fingers forming a base;
FIG. 10 is an isometric view of an apparatus having a rectangular yoke angle in lieu of a radiused yoke, the base being provided with a shim;
FIG. 11 is an isometric rear quarter view of an apparatus having an open, adjustable strap;
FIG. 12-14 are partial cutaway elevation views of a flared, beaded, and rolled edge, respectively;
FIG. 15 is an isometric front quarter view of the apparatus of FIG. 11 augmented with a pad for absorbing impacts;
FIG. 16 is a rear quarter isometric view of an alternate embodiment of an apparatus according to the invention and molded in a block format, a format adaptable to use with expanded (foamed) polymer resins;
FIG. 17 is a top plan view of the apparatus of FIG. 16;
FIG. 18 is a right side elevation view of the apparatus of FIG. 16;
FIG. 19 is a front end elevation view of the apparatus of FIG. 16;
FIG. 20 is a left side elevation view of the apparatus of FIG. 16;
FIG. 21 is a bottom plan view of the apparatus of FIG. 16;
FIG. 22 is a rear quarter isometric view of an alternate embodiment of an apparatus according to the invention and molded in a shaped format, a format adaptable to use with expanded (foamed) polymer resins;
FIG. 23 is a side elevation view of the apparatus of FIG. 22 with one embodiment of a strap surrounding the base; and
FIG. 24 is a rear quarter isometric view of an alternate embodiment of an apparatus according to the invention to have a yoke adjustably movable with respect to the base.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in FIGS. 1 through 24, is not intended to limit the scope of the invention, as claimed, but it is merely representative of the presently preferred embodiments of the invention.
The presently preferred embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout.
The apparatus is best understood by reference to FIGS. 1-23 and particularly to FIGS. 1-15. The apparatus 10, also referred to as a brace 10, is made to have a base 12 securable on an arm of a user. A yoke 14 extends away from the base 12 for orienting a forearm of the user with respect to an associated upperarm of the user. A band 16 or other attachment means suitable for wrapping around the arm of a user is attached over or otherwise to the base 12 for securing the base to the arm of the user. The apparatus may include a pad 18 fitting between the base 12 and the arm of the user, and a pad 20 for absorbing impacts of the member (forearm or upper arm) received into the yoke. The pad 20 is preferably a resilient pad having a thickness, stiffness, and energy absorption selected to absorb an impact of the member of the arm of the user.
The base 12 has a toe 22 and a heel 24. A bicep pocket 26 is formed therebetween along the inside surface 54 of the wall 30 of the base 12. Hypothetically, the bicep pocket 26 has a centerplane 27 passing vertically through it, for reference. The base 12 is curved to fit around a portion of a member (upperarm or forearm) of an arm of a user. The base 12 is connected to the yoke 14 (also curved to receive another member of the same arm of a user) by the joint 28, or dihedral joint 28. The length 32, width 34, and depth 35 of the base are selected to provide comfortable bearing area and to prevent sliding or rotation of the base 12 on the arm of the user. The pad 18 may be formed of a suitable material to achieve these effects. For example open-cell polymer foam, such as polyurethane is suitable, as is a combination of closed cell polymer foam lined with a fabric of cotton.
The depth 35 and thickness 36 are selected to achieve structural strength. The resulting contact angle 38 is defined by the width 34, depth 35 and the radius 40 from the centerline 39. A suitable contact angle is from 10 to 180 degrees with the range of 90 to 130 degrees preferred. A 120 degree contact angle 38 is suitable.
The edge 42 may be treated at any or all of its locations to prevent chafing or scraping against the skin of a user. Suitable treatments may include, for example, the addition of a roll 44, bead 45, flare 16 as shown in FIGS. 12-14. A combination of the roll 44, bead 45 and flare 16 may be used at various locations, and sometimes at the same location along the edge 42.
The vents 50 (See FIG. 7) may be formed to pass in a radial direction 51 through the base. The vents 50 may be extended to open (render discontinuous) the edge 42, forming fingers 52. The fingers 52 are preferably stiff, but flexible. The fingers allow an impact against the yoke 14, absorbing the impact by flexing. Because the fingers 52 can bend in the radial direction 51 as well as flex apart in the circumferential direction 49, the force exerted by the edge 42 of the toe 22 on the arm of a user is reduced in the embodiment of FIG. 9.
A band 18, such as a strap 102 may be wrapped or fastened about the outer surface 56 to extend in a circumferential direction 49. The band 18 secures the base to the arm of a user. The band 18 should also limit the separation distance 57 between the fingers 52. For example, the strap 102 of FIG. 11 may be connected or made to have a suitable restraint against excessive opening of the separation distance 57 during flexure of the fingers 52.
The base 12 need not have a bicep pocket 26. The base 12 can be configured to fit over the forearm of a user. In this embodiment, upon closure of the forearm toward the upper arm, the yoke 14 receives the upperarm. Thus, whether the base 12 is placed on the upperarm or forearm, the yoke 14 serves to orient the forearm with respect to the upperarm upon an attempt at closure, movement of the wrist toward the shoulder. The base member is the forearm or upperarm to which the base 12 is attached. The moving member is the remaining member (upperarm or forearm) that is received into the yoke 14.
The yoke 14 increases leverage on the moving member with the height 70 of the wall 68 forming the cradle 66 in the yoke 14. The height 70 is selected to optimize the leverage of the yoke 70 on the moving member while minimizing bulk. Safety and comfort also figure in the selection of the height 70. The yoke 14 and base 12 need not meet at a dihedral joint 28. However, the dihedral joint 28 makes possible a strong, light yoke 14.
The yoke may be made of a flexible material, such as high density polyurethane foam, that will collapse, bend or give. The yoke then will give in a forward longitudinal direction 53A upon impact, but resist a force in a backward longitudinal direction 53B. (See FIGS. 1 and 15.) The yoke may have a width 72, thickness 74, wrap angle 76, radius 78, and depth 82 selected to permit collapse toward the center of curvature 79.
The wrap angle 76 may be from 5 to 180 degrees, depending on coverage of the arm of a user, and the radius 78. In the embodiment of FIG. 10, the radius may be considered that of any arm that would fit into the yoke 14 A wrap angle is preferably from about 70 degrees to about 130 degrees. The pad 20 need not cover the entire wrap angle but may cover approximately the center third of the wrap angle 76. Alternatively, the pad 20 may be positioned and sized to cover only a third of the inside surface 94 of the yoke 14. The extensive, remaining inside surface 94 beside the pad 20 is preferably smooth and slippery to form a guide and to prevent chafing as the arm (moving member) of the user is urged into alignment.
A center of curvature 79 need not be a single point, nor a single line in the radial direction 51. Any point on the yoke 14 may have its own center of curvature 79. The cradle 66 need not be formed as a right circular cylinder. The cradle 66 portion of the yoke 14, between the head 62 and the knee 64, may be formed to meet individual needs or skill levels. for example, the relative height 70, width 72, wrap angle 76 and radius 78 can be selected for a player's size, skill, and comfort.
The base 12 and yoke 14 meet to form a stop angle 80, and a sweep angle 83, defined by a yoke centerline 81 and a base centerline 39. The base centerline 39 corresponds (is aligned with, oriented similarly to) the base member, and the yoke centerline 81 similarly corresponds to the moveable member.
The sweep angle 83 may be thought of as approximately the angle of rotation of the forearm about the upperarm, with respect to the bicep pocket 26 in the base 12. The sweep angle 83 may be from about negative 15 to about positive 45 degrees, depending on a user's physical development.
The sweep angle 83 may also be thought of as the angle made by a yoke centerline 81 with respect to the base 12, and specifically the centerplane 27 of the bicep pocket 26. One embodiment of the apparatus may be made with a sweep angle of zero degrees. The position of the base 12 in the circumferential direction 49 is adjustable around the arm, thus, the sweep angle 83 of zero degrees.
The base 10 is simply rotated to the proper position (typically slightly outboard of the bicep) before being attached on the upper arm. The user may set the base 12 on one upper arm and rotate the associated forearm until the wrist, elbow and shoulder intersect approximately the same vertical plane. Then, the user closes the forearm toward the shoulder until the forearm rests against the inside surface 94 of the cradle 66 of the yoke 14. Then the user secures the base 12 against the upper arm with the strap 102.
As with the base 12, a flare 84, bead 85 (not shown) similar to the bead 45, or roll 86 can be formed at the edge 88 of the yoke 14. (See FIGS. 11-15.) These treatments of the edge 88 promote safety and comfort of the user, while improving strength and stiffness of the yoke 14.
In one presently preferred embodiment, the sides 90A, 90B may be advantageously formed in one preferred embodiment of a material selected to be smooth and slippery. This arrangement reduces chafing or other discomfort, although the sides are not ideally contacted by a user. That is, a user ideally aligns the forearm to be received into the pocket 92. The forearm then comes to rest against the inside surface 94 of the cradle 66 or a pad 20 secured thereto. If a user does not rotate the forearm of the shooting hand into a proper position, the forearm will be urged toward the centerline 81 by the sides 90A, 90B. A pad 20 is used to absorb the impact of closure of the arm of a user against the yoke 14.
The bands 16 as seen in FIGS. 1, 11, 16-21, and 23 may be configured as a strap 102 or straps 102. The band 16 may be closed on itself. The band 16 may form a continuous loop. Such a band 16 would preferably be elastically extendible for positioning around an arm of a user. The strap 102 is preferably a single piece of material such as a durable, strong, inextensible fabric. Nylon webbing is a suitable material and is available in a variety weaves. The strap 102 is preferably open ended as illustrated in FIG. 11. The fasteners 104 attached to the strap 102 are preferably a hook pad 106A and a loop pad 106B forming a hook-and-loop type of fastener 104.
Alternate fasteners 104 are less preferred, but may be made serviceable and adjustable. Examples of such fasteners 104 contemplated include buckles on straps, hook and eye fasteners, laces through eyelets, snaps, zippers, double "D"-rings on straps, multiple straps having hook-and-loop pads (panels) for attaching at one end, ratcheting straps, clips, levers, and buttons.
Connection of the hook pad (panel) 106A to the loop pad (panel) 106B need not form the strap 102 into a cylinder. The two edges 107, 108 need not remain parallel. That is the ends 107A, 108A of edges 107, and 108, respectively, need not align with the two ends 107B, 108B. Since the upper arm (and forearm, in some embodiments of the apparatus) is not of a constant diameter, either edge 107 or 108 will probably traverse a longer path around the arm of a user. Thus, the fastener 104 is preferably one that will enable this important adjustability to accommodate the shape of the arm of a user.
Moreover, a larger width 112 creates a larger load bearing area against the arm of a user. An optional elastic section 110 may be inserted for relieving stress due to impacts of other players against a user. The result of either of these options is lower stress (continuous and impact derived, respectively) on the skin, muscle, tendons, bones and other components of the arm of a user. Thus the width 112 of a preferred strap 102 covers a substantial fraction of the length 32 of the base 12. A short elastic section 110 may be comprised of an elastic material that is relatively stiff. Relatively stiff means here that the size and stiffness is such that only an impact or other load larger than would normally be comfortable for a user will elongate the elastic section 110.
A pad 18 is optional. The pad 18 may be selected for comfort and for holding securely against the skin of an active user. A suitable embodiment may include a pad 18 having a width 122 that almost covers the inside surface 54 of the base 12. However the thickness 124 may be very thin, from a few thousandths of an inch to about an eighth of an inch is preferred. A binding layer 126 may be a separate layer of permanent or removable adhesive, a double-sided adhesive tape, or a solvent film. However, a pad may be removably attached also.
Removable adhesive can be useful for attaching a shim 128. A shim 128 may be a pad 18 sized to decrease the inside radius 40 of the base. Thus, a shim 128 may be used to size a standard brace 10 or apparatus 10 for a smaller user. A brace 10 may also be used for different players from time to time by adding a shim 128.
The pad 20 may be sized to have a width 142 that does not cover the inside surface 94 of the yoke 14. The width 122 is preferably about a half to about a third of the width 72 of the yoke 14. That is, the pad 20 operates by virtue of its selected thickness 144, energy absorption and resilience to cushion impacts from the arm of a user coming to rest in the yoke 14. By contrast, the sides 90A, 90B may benefit the user by being smooth, slippery and exposed to prevent wear or chafing against the skin. A binding layer 146 operates similarly to the binding layer 126 discussed. Also, a pad 20 could be a shim 148 (not shown) sized as the shim 128 to accommodate the size or orientation (stop angle 80 or sweep angle 83) of the member received in the yoke.
Suitable materials for the apparatus 10 include metals, polymeric, and elastomeric materials. Combinations of materials are contemplated also. For example styrene compounds, acrylonitrile butadiene styrene (ABS), polyvinyl chloride (PVC), vinyl, nylon, polyurethane, olefinics such as polyethylene and polypropylene, polycarbonate, natural and synthetic elastomers such as rubber, and metals including aluminum, iron, and steel. Various combinations of these materials can also be used. Also, reinforced resins may form a matrix around fibers of KEVLAR™, polyethylene, graphite, glass, steel or aluminum for improving tensile strength. Likewise, a polymer selected may be expanded, "foamed," to reduce weight, improve safety, increase cross section for stiffness or strength, to soften the material, promote rounded edges, or to reduce cost.
The embodiments of FIGS. 16-23 operate similarly to the embodiments of FIGS. 1-15. However The embodiments of FIGS. 16-23 are more readily adaptable to molding with comparatively soft, foamed polymers. Suitable materials would include styrofoam, low density polyurethane, low density polyethylene and similarly performing materials. The large, block-like shape of the brace 10 FIG. 16 is readily adaptable to use by children in primary schools.
Multiple straps 102 through the base 12 or a single wide strap over the base 12 may be suitable. The slots 48 may be formed in the base, traversing in a circumferential direction 49 around the arm to which a strap 102 is secured. The embodiment of FIG. 23 may rely on a strap 102 that is a closed, elastic loop similar to a sweat band. A primary school child could easily slip the brace on and off. The large size of the brace would render the brace effective, yet very safe. A low density polyurethane such as is commonly used for sleeping pads could exert enough force to be useful. However, such a material could not exert enough force upon impact to cause injury.
FIG. 24 illustrates yet another preferred embodiment of an apparatus having a base 12 pivotably connected to a yoke 14. The yoke 14 may be pivotably attached to the base 12 at the joints 58A, 58B. In one presently preferred embodiment, an adjustable member 60 connects between the base 12 and yoke 14. Brackets 158, 160 may be of the clevis type for holding a threaded eye rod 162 and reverse-threaded eye rod 164 of the adjustable member 60, respectively, connected by a turnbuckle 166. The turnbuckle 166 may be knurled as shown, and can be configured to adjust the orientation of the yoke 14 with respect to the base 12. The stop angle 80 may be set at a desired value. The base 12 and yoke 14 may also be made adjustable in a similar manner to control the sweep angle 83.
Other adjustment mechanisms may include, for example, fixed blocks fastened to restrain the yoke 14 at a desired position; multiple adjustment members, and bendable metal skeletons inside plastic outer covers forming the apparatus 10. In one embodiment, the yoke 14 may be adjusted by warming and softening the plastic material of which the apparatus 10 is formed. The yoke 14 may alternatively be made rigidly attachable at a selected one of a plurality of locations along the base 12.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope. | 4y
|
BACKGROUND OF THE INVENTION
The present invention relates generally to steam traps used in steam distribution systems.
Steam traps, which are essentially automatic valves used to discharge condensate, are widely used in steam distribution systems. In operation, flash steam within the trap chamber of such devices functions to keep the valve closed. As the trap cools, the steam condenses and fluid pressure in the inlet passage forces the valve element off its seat. Condensate then passes through the trap, which eventually causes the valve element to again engage the seat.
Attempts have been made to verify the proper operation of steam traps by measuring temperature of incoming and outgoing fluid. In this regard, external piping connections having thermocouple sensors have been attached in line with the inlet and outlet of the thermocouple housing. By analyzing the time-varying pattern of temperature readings, it can be determined on a real-time basis whether the thermocouple is operating properly. Such external connections, however, add to the overall “footprint” of the piping network and may not be possible in situations where space is limited or is otherwise tight.
SUMMARY OF THE INVENTION
In accordance with one aspect, the present invention provides a steam trap comprising a housing defining a flow passage extending between an inlet and an outlet. A cap fitted to the housing has a stop face. In addition, the housing and the cap define a trap chamber. A movable valve element is located in the trap chamber.
The steam trap further comprises a first temperature sensor having an inlet sensing portion in the flow path between the inlet and the valve element. A second temperature sensor has an outlet sensing portion in the flow path between the valve element and the outlet.
In accordance with some exemplary embodiments, the inlet may have a first internally threaded portion and a first smooth bore portion. Similarly, the outlet may have a second internally threaded portion and a second smooth bore portion. First and second sensing ports respectively intersecting the first smooth bore portion and the second smooth bore portion may also be provided.
Preferably, the first and second sensing ports may each have internally threaded portions for engagement by attachment portions of the first and second temperature sensors, respectively. The sensing portions of the temperature sensors may extend axially from the respective attachment portions. It will often be desirable for the temperature sensors to be thermocouples.
Embodiments are contemplated in which an end of the inlet sensing portion of the first temperature sensor is located past a centerline axis of the inlet. An end of the outlet sensing portion of the second temperature sensor may be located substantially at a centerline axis of the outlet.
In some exemplary embodiments, the housing may comprise a unitary trap body. Alternatively, the housing may comprise a body portion and a separate connector portion, the connector portion defining both the inlet and the outlet.
In accordance with another aspect, the present invention provides a steam trap comprising a housing defining a flow passage extending between an inlet and an outlet. A movable valve element is operative to selectively allow flow between the inlet and the outlet. A first sensing port having a first internally threaded portion is located at the inlet of the housing and extends transverse to a flow direction at the inlet. A second sensing port having a second internally threaded portion is located at the outlet and extends transverse to a flow direction at the outlet.
A further aspect of the present invention provides a steam trap comprising a housing comprising a body portion and a separate connector portion together defining a flow passage extending between an inlet and an outlet each located at the connector portion. A movable valve element is operative to selectively allow flow between the inlet and the outlet. A first temperature sensor has an inlet sensing portion in the flow path between the inlet and the valve element. A second temperature sensor has an outlet sensing portion in the flow path between the valve element and the outlet.
Further aspects and features of the present invention are provided by various combinations and subcombinations of the elements disclosed herein.
BRIEF DESCRIPTION OF THE DRAWINGS
A full and enabling disclosure of the present invention, including the best mode thereof, to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying drawings, in which:
FIG. 1 is a perspective view of a steam trap constructed in accordance with an embodiment of the present invention;
FIG. 2 is cross-sectional view of the steam trap of FIG. 1 ;
FIG. 3 is an elevational view of the inlet of the steam trap of FIG. 1 ;
FIG. 4 is an elevational view of the outlet of the steam trap of FIG. 1 ;
FIG. 5 is a perspective view of an alternative embodiment of a steam trap constructed in accordance with the present invention utilizing a steam trap body portion and a universal connector portion;
FIG. 6 is a cross-section view of the universal connector portion of the steam trap of FIG. 5 ; and
FIG. 7 is a cross-sectional view of the steam trap body portion of the steam trap of FIG. 5 .
Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only and is not intended as limiting the broader aspects of the present invention, such broader aspects being embodied in the exemplary constructions.
FIG. 1 illustrates an embodiment of a novel steam trap 10 constructed in accordance with the present invention. Steam trap 10 has a trap body 12 to which a cap assembly 14 is attached. Referring now also to FIG. 2 , trap body 12 defines an inlet 16 and an outlet 18 through which the condensate flows.
In this embodiment, inlet 16 defines an internally threaded portion 20 upstream of a smooth bore portion 22 . As one skilled in the art will appreciate, threaded portion 20 permits connection to a pipeline via threaded coupling. Similarly, outlet 18 has an internally threaded portion 24 downstream of a smooth bore portion 26 .
Inlet 16 is in fluid communication with an internal inlet passage 28 , whereas outlet 18 is in fluid communication with at least one internal outlet passage 30 . Inlet passage 28 and outlet passage 30 emerge at a seating face 32 located at the end of a spigot 34 . Cap assembly 14 includes a cap 36 having internal threads engaging outer threads on spigot 34 . As can be seen most clearly in FIG. 1 , cap 36 preferably defines a series of flats 38 about its periphery for engagement by a wrench.
Along with seating face 32 , cap 36 defines a trap chamber 40 in which a valve element in the form of a metal disc 42 is located. Disc 42 is movable upwardly and downwardly within chamber 40 , its movement being limited by seating face 32 and an opposed stop face 44 on the interior of cap 36 . Typically, body 12 and cap 36 are made from metal such as stainless steel.
In the illustrated embodiment, cap assembly 14 further includes a ceramic disc 46 juxtaposed to the top surface 48 of cap 36 to reduce heat loss that may otherwise occur through the cap. As shown, cap 36 includes a vertical pin 50 which is received in a central bore defined in ceramic disc 46 . Preferably, the pin and bore are dimensioned to form a tight fit between these two components. As a result, ceramic disc 46 will be maintained securely in proximity to top surface 48 of cap 36 , without rotating. In addition, a cover 52 , which may be stamped from thin metal, is fitted over ceramic disc 46 and secured to pin 50 such as by a small spot weld.
In operation, condensate reaches trap 10 at inlet 16 . The condensate flows through inlet passage 28 , lifting disc 42 off of seating face 32 . The condensate continues through outlet passage 30 and leaves trap 10 through outlet 18 . As steam approaches the trap, the temperature of the condensate increases.
When the hot condensate passes between disc 42 and seating face 32 , a portion of it evaporates and forms flash steam. The resulting expansion causes an increase in volume of the flowing mixture of flash steam and condensate, thus increasing the velocity. This causes a local reduction in pressure between disc 42 and seating face 32 , which pushes disc 42 into engagement with seating face 32 . A steam bubble within chamber 40 retains disc 42 against seating face 32 , thus resisting the pressure in the upstream pipeline. Loss of heat causes the bubble to collapse, resulting in cycling of steam trap 10 .
Proper operation of steam trap will thus cause periodic variations in temperature both upstream and downstream of disc 42 . As noted above, prior efforts to monitor these temperatures has involved attaching external piping connections in line with the inlet and outlet of the trap body. In addition to increasing the overall footprint of piping near the steam trap, such an arrangement places the sensing elements away from the valve disc. Accordingly, the response detected at this location may not always coincide with the internal steam trap temperature.
The present invention, in contrast, provides a construction wherein the temperature sensing elements are located within the installation “footprint” of the steam trap itself, and closer to the movable disc inside. Referring now particularly to FIG. 2 , sensing ports 54 and 56 are associated with inlet 16 and outlet 18 , respectively. In particular, port 54 extends through the wall of body 12 so as to intersect smooth bore portion 22 in a direction transverse to the direction of fluid flow. Similarly, port 56 intersects smooth bore portion 26 in a direction transverse to the direction of fluid flow. In this embodiment, both of ports 54 and 56 are internally threaded.
A suitable temperature sensor is inserted through port 54 such that its sensing element will be in the flow path of the incoming fluid. In this embodiment, for example, a thermocouple sensor 58 is received in port 54 . Sensor 58 includes an attachment portion 60 having external threads which engage the internal threads of port 54 . A sensing portion 62 extends from attachment portion 60 such that its tip will be in the fluid flow path. As can be clearly seen in FIG. 3 , the end of sensing portion 62 is, in this case, situated past (and above) the centerline CL of inlet 16 to be in alignment with the opening to inlet passage 28 . A lead wire 64 extends away from attachment portion 60 for connection to appropriate monitoring equipment.
In similar fashion, a suitable temperature sensor is inserted through port 56 such that its sensing element will be in the flow path of the outgoing fluid. For example, the illustrated embodiment provides a thermocouple sensor 66 which is received in port 56 . Sensor 66 includes an attachment portion 68 having external threads which engage the internal threads of port 56 . A sensing portion 70 extends from attachment portion 68 such that its tip will be in the fluid flow path. As shown in FIG. 4 , the end of sensing portion 70 is situated approximately at the centerline CL of outlet 18 in this case. A lead wire 72 extends away from attachment portion 68 for connection to appropriate monitoring equipment.
FIG. 5 illustrates a steam trap 80 constructed in accordance with an alternative embodiment of the present invention. Steam trap 80 is constructed in two main portions—a steam trap body portion 82 and a universal connector portion 84 —that are fixed together. Connector portion 84 (which may also be referred to as a “connector block”) permits steam traps of different capacities to be utilized with a single connection envelope in a steam distribution system.
Referring now to FIG. 6 , connector portion 84 defines an inlet 86 and an outlet 88 . In this embodiment, inlet 86 defines an internally threaded portion 90 upstream of a smooth bore portion 92 . Similarly, outlet 88 has an internally threaded portion 94 downstream of a smooth bore portion 96 . Inlet 86 and outlet 88 are in fluid communication with inlet passage 98 and outlet passage 100 , respectively.
Sensing ports 102 and 104 are associated with inlet 86 and outlet 88 , respectively. In particular, port 104 extends through the wall of block portion 84 so as to intersect outlet passage 100 in a direction transverse to the direction of fluid flow. Similarly, port 102 intersects smooth bore portion 92 in a direction transverse to the direction of fluid flow. As shown, both of ports 102 and 104 may be internally threaded. Suitable temperature sensors, such as those described above in connection with the previous embodiment, are inserted through ports 102 and 104 such that their sensing tips will be at the appropriate location.
In the illustrated embodiment, connector portion 84 further includes holes 106 and 108 for receipt of suitable fasteners. Bolts 110 and 112 ( FIG. 5 ) may extend through holes 106 and 108 to threadably engage bores 114 and 116 in body portion 82 ( FIG. 7 ). As a result, body portion 82 and connector portion 84 will be securely connected together.
The construction of body portion 82 may be most easily explained with reference to FIG. 7 . As shown, body portion 82 has an attachment flange 118 at which bores 114 and 116 are located. An L-structure 120 defines an inlet passage 122 and at least one outlet passage 124 . As one skilled in the art will appreciate, inlet passage 122 is in fluid communication with inlet passage 98 of block portion 84 . Similarly, outlet passage 124 is in fluid communication with outlet passage 100 .
A cap assembly 126 (similar to cap assembly 14 in its construction) is attached to L-structure 120 . A movable disc 128 is located in the space between L-structure 120 and cap 126 to move in and out of engagement with a seating face. O-rings 130 and 132 , or other suitable seals, may be provided to seal the interface between body portion 82 and connector portion 84 .
It can thus be seen that the present invention provides a novel steam trap having integrated temperature sensors. While preferred embodiments of the invention have been shown and described, modifications and variations may be made thereto by those of skill in the art without departing from the spirit and scope of the present invention. It should also be understood that aspects of those embodiments may be interchangeable in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only and is not intended to be limitative of the invention described herein. | 4y
|
This is a division of application Ser. No. 49,662, filed June 18, 1979, now U.S. Pat. No. 4,247,623, issued Jan. 27, 1981.
FIELD OF THE INVENTION
This invention relates to a multilayer "blank" for multiple beam leads that can be simultaneously bonded to an integrated (IC) chip preferably by automated equipment. In particular, the invention relates to a blank featuring separate positive- and negative-working resist compositions and a method of preparing and bonding the aforementioned beam leads to IC chips.
BACKGROUND OF THE INVENTION
One of the most costly aspects of IC technology is the labor required to bond the IC chip to the rest of the circuit. Originally this was done by wire-bonding, which required the manual soldering of a wire under a microscope, first to the microscopically small chip and then to the rest of the circuit, one bond at a time. This is not a feasible long-term solution, as the number of bonds necessary would soon far exceed the number of laborers available.
One solution to this problem was to use a gang-bonding technique, wherein automatic bonding of a film-carrying frame to the IC chip or component avoids the necessity of wire bonding. As described in the May 16, 1974 issue of Electronics, page 89, such a technique uses a roll of film that carries to a bonding station a plurality of frames each of which has many generally planar microscopic, spider-shaped copper fingers known as leads. At the bonding station the inner portions of the leads are aligned and then simultaneously connected to the bonding sites on the IC chip. The outer portion of the leads is then available for bonding to remaining portions of the IC package.
Conventionally, such leads are themselves premanufactured, preferably by a photoresist etch process. Generally, such etching has been applied to a three-layer blank, comprising a layer of electrically conductive metal such as copper and a layer of photoresist on each side of the metal. At first both resists were positive-working, usually comprising a quinone diazide. The result of such a blank is a lead frame that lacks any means for maintaining the alignment of the etched leads. That is, the blank provided no means for supporting the etched leads because both resists of the blank were used for etching the leads.
Others suggested that a supporting plastic of the 3-layer blank should be formed to support the etched fingers or leads prior to bonding, as described for example in U.S. Pat. Nos. 3,795,043, issued Mar. 5, 1974 and 3,763,404, issued Oct. 2, 1973. The one layer of the blank that becomes the supporting plastic can be a negative-working resist. A typical negative-working composition has been "Riston", a photoresist material available under the noted trademark from DuPont.
One difficulty with such "supported plastic" blanks has been that, under certain exposure conditions, a large amount, e.g., from 10 to 50 weight percent, of the monomer of the negative resist can be left unpolymerized in the exposed areas. This has been found to be undesirable, because such monomer can leach out and have a corrosive influence on the finished product. Even if corrosive leaching is somehow avoided, residual monomer tends to outgas during the two separate steps of bonding the inner lead portions and the outer lead portions. Such outgassing is thought to be detrimental, particularly to the more expensive, high reliability IC components to be fabricated using the lead frames.
Therefore, it is desirable from the standpoint of electronic reliability that the residual monomers be eliminated. On the other hand, such elimination in effect removes a major plasticizer from the negative resist. This results in poor adhesion and brittleness that can completely negate the negative resist's function of supporting the leads prior to, during and after bonding of the IC chip. Thus, what has been needed is a negative resist formulation which, after substantially all residual monomers are removed from exposed areas, still retains sufficient adhesion to the metal and flexibility as will permit the blank to be coiled and uncoiled during the various process steps.
A large number of photoresist compositions are known in the art for generalized use. Many of these compositions are alleged to provide flexibility or improvement in some other respect, e.g., adhesion. Thus, British Pat. No. 1,507,704 discloses a photoresist composition including certain photopolymerizable monomers and a binder. However, there is no recognition by this patent of resist uses peculiar to the formation of beam leads for IC chips.
SUMMARY OF THE INVENTION
In accordance with the present invention, there is advantageously featured a blank containing a resist, capable of providing superior beam leads for automatic bonding of IC chips, and a process for forming such beam leads. The beam leads are maintained in their proper orientation prior to and during bonding by a spacer formed from the resist having superior adhesion to the beam leads.
In a related feature of the invention such a blank has sufficient flexibility to withstand multiple bending and flexing as is characterisic of the processing of such blanks.
The aforesaid features of the invention are achieved by the use of an improved blank having a structure comprising a flexible strip of electrically conductive metal, a layer of positive-working resist adhered to a portion of one surface of the metal strip, and a layer of negative-working resist adhered to a portion of the opposite surface of the metal strip. The improvement is that the negative-working resist comprises (a) a binder mixture of at least (i) a polymer having recurring units with the structure: ##STR1## wherein each R 1 is independently hydrogen or methyl, R 2 is alkyl containing from about 3 to about 5 carbon atoms, R 3 is alkyl containing from 1 to about 2 carbon atoms, and x, y, and z are mole percents and are about
30≦x≦70
30≦y≦60
1≦z≦5;
and (ii) poly(methyl methacrylate) (PMMA) in an amount of from 0 to about 75 weight percent of the mixture; the binder mixture having a glass transition temperature (Tg) between about 50° and about 100° C.; (b) a photopolymerizable monomer selected from the group consisting of triethylene glycol diacrylate, tetraethylene glycol diacrylate; and a mixture of pentaerthyritol tetraacrylate and either 1,6-hexanediol diacrylate or tripropylene glycol diacrylate; and (c) a photoinitiator composition.
Such a blank permits the use of an improved process for the manufacture of frames containing beam leads suitable for bonding to an integrated circuit chip, the process comprising the steps of imagewise exposing and developing a positive-working resist on one side of a flexible, electrically conductive metallic layer to form a protective resist on the beam lead portions of the metallic layer, and a negative-working resist on the opposite side of the metallic layer to form a window-bearing spacer holding the beam leads in a desired orientation, etching through the exposed metallic layer to form the beam leads, inserting a chip into the spacer, and bonding the beam leads to the inserted chip. The improvement comprises exposing and developing the negative-working resist so that essentially all monomer in the exposed areas is fully polymerized prior to bonding of the IC chip, whereby outgassing of the negative-working resist during the bonding step is substantially reduced.
Other features of the invention will become apparent upon reference to the following Description of the Preferred Embodiments when read in light of the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an isometric view of a blank prepared in accordance with the invention, the preferred form being a rolled-up strip or coating;
FIG. 2 is a fragmentary plan view of a single frame portion of the processed strip after the beam leads have been bonded to the IC chip and before it has been tested at a pre-test station, the details of the chip having been omitted for clarity; and
FIG. 3 is a schematic representation of the process and related apparatus used to convert the blank of the invention into lead frames assembled with IC chips.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
It has been discovered that conventional photoresist formulations cannot provide the exacting properties required for automated beam lead frame formation and bonding of IC chips. Specifically, manufacture of conventional electronic equipment such as circuit boards has not necessitated the kind of flexibility and strict dimensional controls that are needed in continuous strip processing of strip-form lead frames. Such continuous strip processing, generally described in the aforesaid U.S. Pat. No. 3,795,043, requires a blank in the form of a continuous strip to be unwound from a reel and fed intermittently through a photopolymerization exposure station, a developing station, and at least one etch bath, prior to the strip being recoiled for use in the subsequent bonding of an integrated circuit chip to the frame. The coiling and uncoiling during and after resist development subjects the strip to repeated flexures, during which the exposed and developed spacer resist for the leads must maintain its dimensional integrity to hold the leads in their proper orientation, i.e., space the leads within the plane of the strip.
Therefore, the invention is directed to a blank and process for the formation of an IC component lead frame which provide the above-noted properties.
The blank of the invention comprises a metallic layer or strip of metal, a layer of positive-working resist adhered to at least a portion of one surface of the metallic layer, and a negative-working resist layer adhered to at least a portion of the opposite surface of the metallic layer.
Any electrically conductive metallic layer can be used in the invention. Preferred are copper, silver and other similar metals, the materials that are favored for use as beam leads in bonding IC chips. Also, any positive-working resist capable of adhering to the selected metallic layer can be used. The choice is not critical and conventional formulations are acceptable.
In accordance with one aspect of the invention, the negative resist layer is formulated to have superior flexibility and adhesion to the metal layer, particularly a layer of copper. Such a resist comprises a binder mixture (a) noted above, a monomer (b) noted above, and a photoinitiator composition.
Useful binders include those that are a mixture of at least polymers (a) (i) and (ii) noted above. Highly preferred examples of polymer (a) (i) include poly(butyl methacrylate-co-methyl methacrylate-co-acrylic acid), the mole percents of the recurring units being selected to provide, with a 25 to 50 weight percent of PMMA, a glass transition temperature of between 50° and 100° C. The currently preferred mole ratios of the terpolymer are (63:34:3) available from Rohm and Haas Co. under the trademark "Acryloid B48N".
Although the mole percents of the terpolymer can be varied as noted above, it has been found that polymers having no acrylic acid (z=0) tend to provide a resist having insufficient adhesion to the metallic beam leads. Therefore, such polymers provide inadequate maintenance of the orientation of the beam leads prior to and during bonding of the chip to the leads.
The currently preferred monomer of the class (b) noted above is tetraethyleneglycol diacrylate. Dimethacrylate monomers are believed to lack the flexibility necessary to the formation of a successful resist spacer for the beam leads.
With respect to the photoinitiator of the negative-working resist, any free-radical generating photoinitiator system can be used which initiates polymerization of the polymerizable monomer and does not subsequently terminate the polymerization. The free-radical generating system preferably has at least one component that has an active radiation absorption band with a molar extinction coefficient of at least about 50 within the range of about 340 to 700 nm, and preferably 340 to 500 nm. "Active radiation absorption band" means a band of radiation which is active to produce the free radicals necessary to initiate polymerization of the ethylenically unsaturated monomer. The free-radical generating photoinitiator system can comprise one or more compounds which directly furnish free radicals when activated by radiation. It can also comprise a plurality of compounds, one of which yields free radicals after having been caused to do so by a sensitizer which is activated by the radiation.
Representative useful examples of such photoinitiators include all those known in the art, for example those described in the aforedescribed British Pat. No. 1,507,704, including benzophenone, acetophenone, ethyl methyl ketone, cyclopentanone, benzil, caprone, benzoyl cyclobutanone, and dioctyl acetone, particularly when used in admixture with substituted benzophenones such as Michler's ketone.
Highly preferred as the photoinitiator is a mixture of a 3-ketocoumarin and an amine such as is described in the commonly owned U.S. Application Ser. No. 184,606 filed on Sept. 5, 1980 now U.S. Pat. No. 4,289,844 by Farid et al entitled "Photopolymerizable Compositions Featuring Novel Co-initiators". Representative amines include ethyl-p-dimethylaminobenzoate; other esters of p-dimethylaminobenzoic acid, e.g., n-butyl-p-dimethylaminobenzoate, phenethyl-p-dimethylaminobenzoate, 2-phthalimidoethyl-p-dimethylaminobenzoate, 2-methacryloylethyl-p-dimethylaminobenzoate, 1,5-pentyl di-(p-dimethylamino)benzoate; 4,4'-bis(dimethylamino)benzophenone; phenethyl and 1,5-pentyl esters of m-dimethylaminobenzoic acid; p-dimethylaminobenzaldehyde; 2-chloro-4-dimethylaminobenzaldehyde; p-dimethylaminoacetophenone; p-dimethylaminobenzyl alcohol; ethyl-(p-dimethylamino)benzoyl acetate; p-N-piperidinoacetophenone; 4-dimethylamino benzoin; N,N-dimethyl-p-toluidine; N,N-diethyl-m-phenetidine; tribenzyl amine; dibenzylphenyl amine; N-methyl-N-phenylbenzyl amine; p-bromo-N,N-dimethylaniline; tridodecyl amine; 4,4',4"-methylidyne(N,N-dimethylaniline) (crystal violet, leuco base); 3-indoleacetic acid; and N-phenylglycine.
The coumarin associated with the amine can be one or more of, e.g., the following:
3-(2-benzofuroyl)-7-diethylaminocoumarin;
3-(2-benzofuroyl)-7-(1-pyrrolidinyl)coumarin;
7-dimethylamino-3-thenoylcoumarin;
3-benzoyl-7-diethylaminocoumarin;
3-(o-methoxybenzoyl)-diethylaminocoumarin;
3-(m-fluorosulfonyl)benzoyl-diethylaminocoumarin;
3-(p-dimethylaminobenzoyl)-diethylaminocoumarin;
3,3'-carbonylbis(5,7-di-n-propoxy coumarin);
3,3'-carbonylbis(7-diethylamino coumarin);
3-benzoyl-7-methoxycoumarin;
3-(2-furoyl)-7-diethylaminocoumarin;
3-(p-dimethylaminobenzoyl)-7-diethylaminocoumarin;
3-(p-diethylaminostyrylcarbonyl)-diethylaminocoumarin;
3-(p-morpholinostyrylcarbonyl)-diethylaminocoumarin;
9-(7-diethylamino-3-coumarinoyl)-1,2,4,5-tetrahydro-3H, 6H, 10H [1] benzopyrano[9, 9a, 1-gh]quinolazine-10-one which has the structure ##STR2## 9-(7-n-propylamino-3-coumarinoyl)-,2,4,5-tetrahydro 3H, 6H, 10H [1] benzopyrano[9, 9a, 1-gh]quinolazine-10-one.
It has been found that the noted coumarin-amine mixed photoinitator renders objectionable outgassing of the remaining resist support less likely during bonding of the IC chip and/or during subsequent processing.
The weight percents of the components of the negative-working resist can be varied widely, based on the total weight of the solvent free composition. E.g., the monomer (b) noted above can be from about 20 to about 40 weight percent, and preferably from 24 to about 30. The photoinitiator composition can be from about 0.05 to about 10 weight percent, and preferably about 0.10 to about 5 weight percent (based on total solids).
Photoinhibitors are often desirable for use with the monomers, and conventionally a photoinhibitor such as hydroquinone is included in the monomers. If additional photoinhibitors are required, useful examples include 3-t-butyl-4-hydroxy-5-methylphenyl sulfide and t-butylpyrocatechol.
Stabilizers can also be added if desired, for example, benzotriazole.
With respect to the positive-working resist, because it is present only during the short time that is necessary to etch the metal to form the leads and provides no support function, as contrasted to the negative-working resist, formulation does not need to be carefully designed as to flexibility or adhesion. Thus, the positive-working resist can comprise, in general, any insoluble, light-sensitive material that becomes soluble in a solvent of choice when exposed, and an optional filler or binder such as a poly(acrylic acid) or a copolymer of ethyl acrylate and methacrylic acid. Particularly useful positive-working light-sensitive materials are cresol-formaldehyde resins condensed with quinone diazides to produce the structures ##STR3## wherein R is the main chain of the cresol-formaldehyde resin and R 1 and R 2 are different and are either N 2 or O. Such structures can be formed, for example, by condensing 6% of the resin with 6-diazo-5,6-dihydro-5-oxo-1-naphthalene sulfonyl chloride. Applicant's U.S. Pat. No. 4,141,733, issued Feb. 27, 1979, provides additional examples, the disclosure of which is hereby expressly incorporated by reference.
Alternatively, quinone diazides can be condensed with phenol- and cresol-formaldehyde novolak resins.
Stabilizers such as glacial acetic acid are often added to such positive-working resists.
The photochemistry by which a typical positive-working resin becomes soluble is believed to proceed as follows: ##STR4##
The dried negative-working resist layer has a thickness sufficient to provide the desired spacer function, preferably from 25 to about 75 microns. The dried positive-working resist is preferably from about 2.5 to about 5.0 microns thick, and the metallic layer from about 25 to about 75 microns thick, although other thicknesses outside these ranges may also be useful in certain applications.
The photoresists of the invention can be applied to the metal layer by a wide variety of techniques, including coating techniques such as spray-coating, whirl-coating, curtain-coating, roll-coating, and the like, all of which are conventional.
Any suitable solvent can be selected for preparing a coating of either resist on the metallic layer. Typical examples include dichloromethane, acetone, benzene, acetates, alcohols, ethers, toluene and the like. The choice will depend of course upon the composition selected for the resist.
Thus, as shown in FIG. 1, the blank 10 of the invention can comprise a metallic layer 12, a positive-working resist 14 and a negative-working resist 16. The negative resist can optionally include a removable cover sheet 18. Such a sheet is particularly useful for formulations of resist 16 that tend to be somewhat tacky or oxygen sensitive. The cover sheet can be either preformed and then laminated to layer 16, or it can be cast in place as a film from a water-soluble polymer. Examples of the former include cellulose esters such as cellulose triacetate, polyamides, polyolefins, vinyl polymers and polyesters. Examples of the latter include poly(vinyl alcohol) such as is obtainable from DuPont under the trade name "Alvinol 5105", or hydroxyalkyl cellulose of from 1-2 carbon atoms in the alkyl portion, as is available for example from Hercules Inc. under the trade name "Natrasol 180L".
The thickness of such cover sheets is not critical, other than that an excessive thickness makes removal more difficult. For example, a thickness of 12 to about 50 microns can be used. A preferred thickness is from about 17 to about 25 microns.
A preferred method of storage of the blank or tape of the invention, after manufacture, is in strip form coiled upon a suitable spool or mandrel 20 into a roll 21, FIG. 1. In such cases, the cover sheet or layer 18 is preferably one which prevents or bars transfer of monomer from layer 16 to layer 14 of the next adjacent section of the strip, at least in those instances in which the monomer is detrimental to the positive-working resist. Highly useful materials having such a barrier property include polyester films.
After the blank strip 10 is processed in the manner described hereinafter, there are formed in the blank, FIG. 2, successive frames 30 each of which comprises edge portion 31 of the metallic layer 12, etched to provide beam leads 36. Each of the leads has an inner portion 32 to be aligned with a selected portion of IC chip 40, and an outer lead portion 37 connected to edge portions 31. Portions 37 eventually are bonded to other electronic components. Sprocket holes 38 may also be formed in layer 12. The leads 36 are held in place prior to and during bonding of chip 40 by means of the exposed and developed negative resist layer 16, now in the general shape of an annular spacer 41 having a window 42. The inner dimensions of the window are sized to permit the insertion of chip 40. No positive resist remains.
Any suitable IC chip 40 can be used. For example, the IC chip 40 can be of a conventional type utilizing planar technology in which the chip is formed of a suitable semiconductor material such as silicon. The integrated circuit is formed by diffusing impurities into the silicon to form regions of opposite conductivity with junctions between the same extending to the planar upper surface of the silicon die. Contact buttons or "bumps", not shown, which make contact with the active regions of the devices of the integrated circuit are evaporated or deposited onto the dye by conventional methods. Beam leads 36 normally extend and are bonded to the contact bumps. As is well known to those skilled in the art, the integrated circuit can contain active and passive devices such as transistors, diodes, resistors and other electronic components to form at least part of an electrical circuit. The transistors can be of the n-p-n or p-n-p type.
As noted above, any tendency of the support resist to outgas during bonding can be harmful to the IC chip. Outgassing is preferably minimized by any or all of the following steps:
(a) the elimination of low-boiling plasticizers;
(b) the use of an amine-biscoumarin mixture as the photoinitiator in place of other initiators; and/or
(c) the use of full photopolymerization exposure. As used herein, "full photopolymerization" means exposure and/or subsequent processing such as will completely polymerize the monomers of the negative-working resist, to prevent outgassing as is described in the "Background".
A variety of processing steps, sequences and accompanying apparatus can be used to produce the bonded frames 30, FIG. 2, from the blank 10 of FIG. 1. For example, hand processing can be used. However, the commercial realities are that automated gang-bonding of all the leads in a single frame is necessary to render the process competitive.
A useful and preferred processing sequence is detailed in FIG. 3. At station A, a roll 21 of the blank is uncoiled and fed by conventional advancing means through exposure units 50 and 52. Unit 50 exposes the positive-working resist 14 through a suitable mask, not shown, which after development will leave resist in the unexposed areas that represent the beam leads 36, fingers 32 and edge portions 31 shown in FIG. 2. Unit 52 exposes the negative-working resist 16 to a mask shaped as the spacer 41 of FIG. 2. Unit 52 either has sufficient intensity during exposure to fully photopolymerize the monomer of resist 16 in the exposed areas, thereby leaving no monomer after development, or alternatively full polymerization is achieved by a subsequent optional oven baking 54 where the negative resist is heated for between about 0.5 minute to about 5 minutes at a temperature of from about 75° C. to about 125° C. The blank 10 is then recoiled at 56, creating new stresses in the fully exposed portions of the negative-working resist due to the lack of monomer. Subsequently strip 56 is moved (56') to developing station B where a wash spray device 58 removes the exposed portions of positive resist 14, and cover sheet 18 if it is water soluble. Wash bath 59 rinses off residual developer. Alternatively, a mechanical stripper (not shown) can be used to remove sheet 18 if it is the laminated type. The strip now bearing the positive resist over the beam leads 36, fingers 32, and edge portions 31 only, of the metal layer, is carried to etch station C and passed through an etch bath 60 to etch the openings in layer 12 shown in FIG. 2. A wash bath 62 removes residual etchant. To develop the negative resist, the strip continues to station D where apparatus 64 sprays a suitable solvent such as 1,1,1-trichloroethane onto the strip to remove the unexposed areas of negative resist 16, leaving at each frame the spacer 41 as shown in FIG. 2. A rinse spray 66, usually water, is also included. This rinse spray can also be selected to remove the positive resist 14 remaining on the opposite side of the metal. The strip is recoiled at 68.
At bonding station E, the strip is uncoiled at 68', and IC chips 40 are mated with windows 42. Bonder 70 bonds the inner portions of the leads to the IC bumps, preferably at a temperature in excess of 400° C. It is this elevated temperature which creates objectionable outgassing and cracking of the spacer 41 if the formulation of resist 16 is not carefully controlled. The bonded strip is recoiled at 72.
To determine which, if any, of the components of the IC chip have not survived the processing and/or are defective, the strip is then uncoiled at 72', station F. To free the leads 36 from edge portions 31, a punch 73 is operated to sever the connections of outer portions 37 of the leads. The unit formed by the leads now connected just to the chip can be transferred to another conveyor path 74. An optional testing device 75 is disposed to check each of the leads by contacting outer portions 37 thereof. Spacer 41 continues to hold the leads in their proper orientation. Frames bearing inoperative IC chips are then removed (not shown) and operative units are carried to station G for final packaging. Other components (not shown) are fed into place at station G and the outer lead portions 37 are bonded and assembled with these components by conventional apparatus. If the chip is to constitute an individual component, it is hermetically sealed in an inert plastic envelope and the outer lead portions 37 are bonded to a circuit board. Alternatively the outer lead portions can be bonded along with the leads of diverse other chips to a thin film circuit to create a hybrid element.
It will be readily appreciated that one or more of the coiling and uncoiling steps can be eliminated to permit immediate application of the next step of the process. However, because steps D, E, and F can each proceed at a rate that is generally different from the other step rates, recoiling and subsequent uncoiling is as a practical matter necessary to some extent. It is this coiling and uncoiling that demands superior flexibility and adhesion of the negative resist spacer 41 to the beam leads. The removal of unpolymerized monomer at station A eliminates the plasticizing effect that would otherwise be present.
As an alternative to the aforedescribed process, exposure station A and developing station B can be used to process just the positive-working resist, in which case a separate exposure station for the negative-working resist would be inserted between station C and D.
As yet another alternative, the leads 36 can be etched free of edge portion 31 during the primary etching, station C. In that case, one or more mounting bridges (not shown) is used to connect spacer 41 to the metal edge portions 31 of frames 30, and the mechanical severance step at punch 73 is used just to sever the bridge.
EXAMPLES
The following examples further illustrate the nature of the invention.
EXAMPLE 1
Each of the following negative-resist formulations of Table I was coated at 75 microns dry thickness onto a 35 micron thick copper foil coated on one side with a 5 micron thick positive-working resist to form a continuous film strip. Recurring units are stated in mole percents. The positive-working resist comprises in each case the following composition:
______________________________________Composition of Positive-Working Resist______________________________________Cresol-formaldehyde resin esterifiedwith 6-diazo-5,6-dihydro-5-oxo-1-naphthalene sulfonyl chloride 70.0 gPoly(ethylacrylate-co-methacrylic acid)(90:10 mole ratio) 26.6% solids inbutyl acetate solution 112.8 gGlacial acetic acid 1.36 gButyl acetate 99.2 g______________________________________
TABLE 1______________________________________Compositions of Negative-Working Resists______________________________________Example 1Poly(methyl methacrylate-co-butylmethacrylate-co-acrylicacid) (34:63:3) availablefrom Rohm and Haas under thetrademark "Acryloid B48N" 2.0 gPoly(methylmethacrylate) availablefrom Rohm & Haas under thetrademark "Acryloid A-11" 2.0 g1,6-Hexanediol diacrylate 1.75 g4,4'-Bis(dimethylamino)benzo-phenone (MK) 0.025 gBenzophenone .15 g3-t-Butyl-4-hydroxy-5-methyl-phenyl sulfide (photoinhibitor) 0.0175 gDichloromethane (DCM) 8.92 gExample 2"Acryloid B48N" 2.0 g"Acryloid A-11" 2.0 gPentaerythritol tetraacrylate 0.75 gTripropylene glycol diacrylate 1.0 gMK 0.025 gBenzophenone 0.15 g3-t-Butyl-4-hydroxy-5-methyl-phenyl sulfide 0.0175 gDCM 8.92 gExample 3"Acryloid B48N" 2.0 g"Acryloid A-11" 2.0 gTetraethylene glycol diacrylate 1.27 g3,3'-carbonylbis(5,7-di-n-propoxycoumarin .036 gEthyl-4-dimethylamino benzoate .036 gt-Butylpyrocatechol (photoinhibitor) .0175 gDichloromethane 8.16 g______________________________________
Two controls were prepared. For Control No. 1, a 100-micron thick layer of Riston "Solder Mask" R Type 74OS photoresist available from DuPont was laminated onto the copper foil in place of the negative-working resists of Examples 1-3. For Control No. 2, a 75-micron thick layer of "Riston I" resist available from DuPont was prepared by laminating together 3 layers of 25 microns each. The active components of the composition of the "Solder Mask" and "Riston I" resists are as follows:
______________________________________ Solder Mask Riston I______________________________________Binder poly(methyl poly(methyl methacrylate) methacrylate)Monomer Pentaerythritol Trimethylol tetraacrylate propane tri- acrylatePhotoinitiator 4-chlorobenzo- Michler's phenone and ketone and Michler's ketone Benzophenone______________________________________
Each sample was processed as follows:
(1) All sample strips were exposed until 13 solid steps were produced with a Kodak T-14 0.15 neutral density step tablet, on a Colight M-218R exposing unit (400 watt mercury lamp). In the case of Example 1, the amount of exposure was 4 minutes, for example.
(2) The strips were then baked in an oven at 90° C. for 1 minute.
(3) Exposed positive resist films were immersion developed for 90 seconds in aqueous-diluted KMPR-809R developer (1:1) available from Eastman Kodak, to completely remove the exposed areas. A final water rinse was used to remove all traces of developer.
(4) The unprotected copper foil (exposed areas) was chemically removed using a FeCl 3 spray etcher at 45° C. (2-minute total etch).
(5) The protective positive resist was then removed in a stripper of KMPR-809R developer and isopropanol.
(6) The exposed negative resist films were then spray developed with 1,1,1-trichloroethane to remove the unexposed areas. A final water rinse was used to remove all traces of developer.
(7) All processed tapes were thermal compression bonded to gold bumped IC chips using a Jade JEMS/LAB bonder. The bonding cycle was for 0.35 seconds at 438° C.
All three of Examples 1 through 3 demonstrated the formation from layer 16 of a spacer 41 that adhered well to the copper and demonstrated little tendency to crack or break when processed through step (7). In contrast, however, Control No. 2 cracked and broke to such an extent by the time step (3) was completed that further testing was impossible. Control No. 1 fared better, but exhibited a pronounced tendency to "pop off" the copper beam leads prior to the final chip bonding step, step (7), thereby demonstrating a lack of adhesion.
COMPARATIVE EXAMPLE
The following negative resist formulation was found to be unacceptable.
C.E. No. 1
The formulation of Example 1 was repeated, except that the composition of the negative resist was as follows:
______________________________________Component Amount______________________________________Poly(methyl methacrylate-co-ethyl acrylate (60:40)available from Rohm and Haasunder the trademark "Acryloid B-82" 1.0 gPolymethylmethacrylateavailable from Rohm and Haas Co.as "Acryloid A-11" 1.0 gPentaerythritol tetramethacrylate 0.6 gPentaerythritol tetraacrylate 0.45 gBenzophenone 0.23 gMichler's Ketone 0.03 g[4,4'-Bis(dimethylamino)benzophenone]Dibutyl phthlate plasticizer 0.21 gDichloromethane 7.8 gNon-ionic fluorochemicalsurfactant in ethyl acetate 50%active solids, available from 3Munder the trade name "FC-431" 0.02 g______________________________________
This resist was coated, exposed, developed and tested as described in Example 1. After the bonding step, step 7, it was found that the negative resist spacer 41 had cracked and separated enough from the copper fingers so as to render the results unacceptable. That is, insufficient dimensional stability was provided for the copper beam leads. It is believed this was due in part to insufficient adhesion of the resist binder to copper, as well as to the lack of flexibility in a binder containing only 40 mole percent of ethyl acrylate. Merely increasing the relative amount of the ethyl acrylate is not believed to be acceptable as this along with the corresponding decrease in methyl methacrylate produces an unacceptable lowering of the binder Tg.
The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. | 4y
|
This application is a continuation-in-part of Ser. No. 08/786,102 filed Jan. 17, 1997 now abandoned, which is a continuation of Ser. No. 08/393,018 filed Apr. 19, 1995 now abandoned.
TECHNICAL FIELD
This invention relates to a waterproofing material suitable for waterproofing ponds, lakes, lagoons or comparable sites whereby water is retained, or wherein waste is deposited and the ground beneath has to be protected against leakage of aqueous or other liquid. The material can also be used in relation to water proofing structures, covering contaminated land to prevent flow of water into such contaminated land and lining trenches which separate contaminated areas from clear areas. The material can also be used as roofing material on flat or sloping roofs.
PRIOR ART
Several materials have been proposed in the past which include a layer of swellable smectite such as montmorillonite and/or saponite incorporated within the material to act as the sealing agent. The montmorillonite has been carried by a support layer or base which has been provided in various ways. A support layer acts as protection but also gives additional strength within the material.
European patent number 59625 (CLEM) describes a waterproofing material which is a laminate comprising a fabric base, particles of montmorillonite adhered to the base and a scrim adhered over the montmorillonite particles to retain them on the base.
In European patent application 246 311 (McGROARTY) a lower sheet comprises a base and montmorillonite and an overlaid sheet comprises a base and montmorillonite. The bases are of solid plastics non-venting and impermeable material so one of the bases forms a non-water transmissive layer between the two layers of montmorillonite, thus giving a very good seal. However, the McGROARTY construction does have several practical difficulties. Firstly, the bases are made from a thick, impervious and essentially solid plastics material, described in the specification as HDPE (high density polyethylene). Secondly, the granules of montmorillonite are adhered not only to the base but also to each other.
Waterproofing materials of this kind are usually supplied in rolls and have to be unrolled and placed to lie in the pond, lagoon or storage space. With the bases made from HDPE the McGROARTY material is less flexible than when using a fabric (non-woven or woven) for the base. This means that the product is much more difficult to handle and the montmorillonite is likely to crack during folding and unfolding. Further, because of the nature of an HDPE plastic sheet the adhering of the montmorillonite to its surface is not easy. Quite large quantities of very strong glue have to be used.
A further waterproofing barrier material is disclosed in GB 2 202 185 (NAUE) in which a layer of montmorillonite is sandwiched between a pair of layers of non-woven textile material and the two layers are united by needling, the needles passing through the layer of montmorillonite and uniting all three layers. Again, because the montmorillonite is not adhered to the layers, as the material is unfolded, folded and manhandled during installation, the montmorillonite can move relative to the two layers leaving voids and/or more permeable thinner areas in the montmorillonite layer.
There is a further disadvantage in that all these earlier materials tend to use particulate montmorillonite which may be from 2-5 mm, usually about 3 mm in size. Although finer material can be poured to fill gaps between the larger granules, such larger size granules tend to make up the bulk of the montmorillonite layer in the waterproofing material. As the waterproofing material is only relatively thin, for example containing only perhaps one or two layers of montmorillonite granules, problems can arise in connection with foreign bodies in the montmorillonite used. In its natural state montmorillonite is found alongside shale and other impurities. Whilst the montmorillonite can be quite highly purified, it is not unusual for a low percentage of shale particles to remain in the final sized and graded montmorillonite. An unfortunate result of the use of relatively large granules of montmorillonite is that granules of impurities can also become incorporated in the material. The chemical nature of shale and some other impurities have the effect that not only are they not montmorillonite (and therefore do not swell upon contact with water), but, when wetted, act to inhibit swelling in adjacent montmorillonite granules. Thus, a single granule of shale in a layer of waterproofing material can form a small area (perhaps 10 mm in diameter) which does not swell upon being contacted with water. Such areas are generally water impermeable, but medium and larger such areas allow water to pass through the sheet. When water pressure is high this flow can cause significant wash out of adjacent montmorillonite leading to failure of the sealing system. Although the percentage of impurities is small, and although the failure rate is small, when a large area is sealed using sheet material incorporating such impurities it needs only a single leak for the whole system to have failed. A pond or lagoon which has a single leak is no pond or lagoon at all!
U.S. Pat. No. 2,277,286 (Bechtner) is primarily concerned with formation of a blanket of dry “in-situ” bentonite which has all the disadvantages noted above, and is also difficult to distribute evenly. However, it also mentions the possible formation of a putty-like mass form 50-60% water and 40-50% clay, which is sufficiently cohesive to adhere to rough or smooth surfaces, such as a wall which is to be sealed against leakage from outside earth.
Particulate montmorillonite has also been mixed with various organic components to form a thick putty (see U.S. Pat. No. 4,534,925). Typical components are polypropene and polybutene. This material has been extruded in the form of rods and sheets, usually being stored between layers of release paper. Such material has been used for sealing ground foundations and similar structures. It has not, however, being extruded so as to become united with a carrier sheet and be capable of use in large rolls for covering large areas. Indeed, the polypropene and polybutene used is intended deliberately to give the extruded material a rubbery or formable consistency enabling it to be moulded by hand around small areas such as chimneys, at joints in concrete panels, or where drains penetrate foundations. These materials are also quite expensive and prohibitively so for use in relation to large area sheets.
U.S. Pat. No. 5,116,413 (Nooren) teaches the mixing of bentonite clay with a hydrophobic substance such as bitumen or vaseline, with addition of only a small amount of water or alcohol, namely 0-4% (see column 4 line 44), to provide a sealing agent which is mouldable and useful for production of watertight bushings. Cellulose compounds or polyacrylates are mentioned as alternative water swellable or swollen high-molecular substances to the bentonite clay.
U.S. Pat. No. 5,132,021 (Alexander) is primarily concerned with use of dry, particulate bentonite clay sandwiched between outer sheets. At column 7, line 26 to 33 it mentions that polar activators such as 75-98% methanol or ethanol and 25-2% water can be “included with (absorbed by)” the clays, the amount of such activator being from 10-40% relative to the dry weight of the clay. Partial hydration of the clay should result from the aforesaid addition. However, there is no teaching at all of the mixing of the two constituents, or kneading same, to provide a substantially homogeneous deformable mass. Without this, a reliable waterproofing layer is not formed. The mere pouring of water onto the “in situ” dry clay will be quite inadequate in most applications, as discussed above.
U.S. Pat. No. 5,237,945 (White et al) teaches the application of a bentonite clay/water paste (preferably about 30% clay) to the top surface of a loose fibrous mat in which powdered clay has been deposited. The paste is subsequently compressed into the mat, which in practice is likely to prove difficult, and certainly will not provide a truly homogenous hydrated layer, nor retain or hydrate the loose particles.
Calcium montmorillonite is sometimes used as a substitute for sodium montmorillonite. In use, calcium bentonite, when initially wetted, will swell and expand in the same way as sodium montmorillonite. However, if the material should dry out, for example due to low rain fall or a falling water table calcium montmorillonite cannot shrink back to its original size upon loss of water without cracking. After cracking and upon re-wetting the clay can not re-wet so as to reform the waterproof barrier. Thus, a calcium bentonite waterproofing material should only be used in cases where permanent wetness is to be encountered.
All sodium containing montmorillonites do have a problem when the water which comes into contact with them is contaminated by salts, particularly sea water or other salts which render the ground water ionised and highly active. In ground water calcium is invariably present in quantity from soil and minerals. When such ionic calcium comes into contact with montmorillonite it tends to convert the montmorillonite from the sodium to the calcium form with the disadvantage which has been outlined above.
This particular process makes it generally unwise to use even sodium montmorillonite in a situation where the ground water can become rapidly ionised or contaminated by leachates or the like. In particular, fertilisers are a particularly notorious cause of ground water ionisation and can cause sodium montmorillonite break down.
In a paper entitled “Preparation of Montmorillonite—Polyacrylate Intercalation Compounds and the Water Absorbing Property” by Ogawa et al published in Clay Science Number 7 243 251 (1989), the authors have described the introduction of a acrylamide into montmorillonite and the polymerisation of the acrylamide to form a polyacrylamide intercalation compound. The enhanced water-absorbing properties of the compound are noted.
It is to be appreciated, of course, that the processes carried out in the Ogawa paper were essentially laboratory processes involving small amounts of material. No techniques were described for making any useful product and there was no discussion of the advantages of high density such compounds as waterproofing agents.
OBJECT OF THE INVENTION
It is an object of the present invention to provide a waterproofing material in sheet form whereby the above described disadvantages of mats incorporating dry or semi-hydrated particles (hydrated in situ), are reduced or minimised.
It is a further object to provide a waterproofing sheet which is reliably waterproof, and not subject to leakage in small local areas.
It is yet another object of the invention to provide a waterproofing material in sheet form which is less susceptible then hitherto to damage by leachates or salt water.
It is yet another object of the invention to provide a denser, and consequently less bulky and easier to handle waterproofing material in sheet form than hitherto.
SUMMARY OF THE INVENTION
The invention provides a novel method of making a waterproofing laminate material comprising the steps of mixing a particulate smectite clay with a liquid to form a mixture, said mixture containing clay in a range from 50% to 75% by weight and water in a range 10% to 30%, kneading said mixture in a high speed, high shear mixer to form a substantially homogeneous deformable mass, forming said mass by extrusion under vacuum into a waterproofing sheet, and laminating said sheet with a flexible, porous, carrier sheet to form a laminate structure free of loose particulate material
In this respect, use of a mixer capable of high speeds and high shear action in order to thoroughly mix the liquid and granular components together and knead the resulting mixture is essential to ensure that a homogenous plastic (i.e deformable) mass is obtained .
Subsequent extrusion under vacuum is also essential to ensure removal of any potential air pockets in the mixture and a high density in the final product, which is desirably as thin as practical, so as to be as cost effective as possible.
In order to achieve an even pressure during extrusion, yet obtain a relatively wide, thin sheet of waterproofing material, it has been found particularly advantageous for the plastic mass to be extruded in annular form, using a conical, or bell shaped insert in the extrusion die, for example. Then, immediately after formation, the annulus or pipe can be slit, and supported as appropriate as it in uncurled and brought into contact with the carrier sheet.
After forming the laminate material can be subjected to a drying step to remove excess water from the waterproofing layer and cause it to loose a degree of elasticity so that it is less likely to deform further during transportation and storage. Such drying also increases the swellability of the smectite clay upon contact with water in use.
Union of the smectite containing layer with the carrier sheet can be by adhesive, but desirably no adhesive is used, the mixture of smectite (and other substance(s)) being such as to allow pressure to force the plastic mass into the interstices of the carrier sheet (which is desirably of a textile nature) so as physically to unite the two. Similar connection can be effected between the waterproofing layer and any overlying cover sheet.
Naturally, the invention also provides the waterproofing laminate material, free of loose particulate material, which results from the aforesaid method. Said material comprises a flexible, porous carrier sheet laminated to a waterproofing sheet which is formed by extrusion under vacuum from a substantially homogenous deformable mass consisting of a mixture of particulate smectite clay and a liquid, in which respect the clay is in a range from 50% to 75% by weight of the mixture and the liquid comprises water in a range from 10% to 30% by weight of the mixture.
Additives which modify the behaviour of the smectite clay under certain specified conditions such as salt water, or presence of strong leachates, radiation hydrocarbons or organic chemicals can be added at the mixing stage, particularly to the liquid component of the mixture, to be operative when the smectite is in use.
Organic materials such as methanol, ethanol and other alcohols, glycerine, diesel and other oils and fats can be added to the water.
Alcohols have particular advantages. The y are introduced primarily to increasing the flexibility and reducing the stiffness of the mixture thus assisting in its processing, i.e. a length of the clay can then be bent easily without breaking. Methanol and glycerol are particularly useful additives in this respect. Whilst alcohols are generally expensive, they are also usually far more volatile than water. Thus, a plastic mass made using methyl alcohol can, after having been formed into a cohesive continuous layer be dried using less heat than would be necessary to drive out the water from a similar mass. In addition to this however, the alcohol driven off can be condensed and reused thus offsetting the cost thereof.
The montmorillonite mesh size can be anything from 50 mesh or smaller, desirably, however the size is a maximum of 100. In practice a mesh size of 200 has been found useful although variations downwards from about 100 mesh do work although with less desirable qualities. Finer meshes are perfectly acceptable, but tend to be unnecessary. The smectite used is desirably sodium montmorillonite although calcium montmorillonite (modified by treatment with sodium hydroxide) can be used. As the montmorillonite is usually broken down significantly during mixing to micro sizes, initial grain size is not critical.
The waterproofing sheet may be sandwiched between the carrier sheet and cover sheet.
The fabrics used as carrier sheet and/or cover sheet can be conventional woven or non-woven textile such as nylon or polypropylene or polyester.
Waterproofing material in accordance with the invention can be used, for example, as roofing material or to provide a seal for a pipe or other plumbing fittings.
Acrylate or polyacrylate compounds may desirably be added to the liquid for mixing with the clay. In the sodium cation form the acrylate can replace the sodium cations which normally coat the outer layers of the smectite clay plates. These sodium ions are not readily displaced by calcium or other ions which may be present in leachate or fertilisers contaminated ground water, so that a highly effective barrier, which is resistant to breakdown is formed in this way.
Another advantage of incorporating acrylate or polyacrylate compounds is that adhesive compatible thereto, such as cyano acrylate adhesive, is effective to adhere the resulting sheet material to upright surfaces, such adhesion previously being rather difficult to accomplish due to the ineffectiveness of most adhesives.
A further problem of smectite clay when used as a waterproofing material, is that its function is very dependent on the amount of montmorillonite used. For example when a body of a montmorillonite is constrained between two surfaces, such as the concrete of a structure and the ground, when contacted by water it swells and forms a high pressure layer which prevents ingress of water to the structure and therefore effectively waterproofs it. To increase the waterproofing efficiency of the clay body, larger quantities of montmorillonite can be used. However, higher quantities of montmorillonite mean thicker sheets of material which are more difficult to handle and which are heavier gave more transportation costs and are bulky. In sheets which consist principally of particulate montmorillonite there can be significant difficulty in getting a large quantity into a small area. Sheet material used for waterproofing in ground situation or for roofs, walls and the like tend to have relatively low densities. This is because they are generally made from particulate montmorillonite adhered to a support sheet as of plastics material or textile material and secured thereto by a variety of means ranging from adhesive to needling to sewing or be embedment in a mesh of fibres.
The invention provides a smectite clay waterproofing material having a density greater than 1000 kg m −3 (62.43 lb/ft 3 ).
The waterproofing material can be a sheet at least a meter (39.4 inches) wide and desirably up to four meters (157.5 inches) wide or more.
The pressure applied during extrusion, and after a suction treatment which has removed excess air and possible other gases, reduces the number of voids in the product as-well as urging the molecules of the product closer together to produce a denser product.
Reinforcement can be provided in the middle of the smectite containing layer.
The reinforcement can be secured to the cover sheet and/or the support sheet.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described further, by way of example, with reference to the accompanying drawings wherein:
FIG. 1 is a schematic perspective view illustrating apparatus suitable for carrying out a preferred method of the invention;
FIG. 2 is a cross-sectional view illustrating a preferred waterproofing material of the invention;
FIG. 3 is an enlarged schematic side view also illustrating how the method of the invention is carried out using the apparatus of FIG. 1;
FIG. 3 a is an enlargement of the encircled detail in FIG. 3;
FIG. 4 is a view similar to FIG. 2 but illustrating a modified material of the invention;
FIG. 5 is a view similar to FIG. 4 but illustrating a still further modified material;
FIG. 6 is a cross-sectional view illustrating an overlap joint made using material of the present invention similar to that shown in FIG. 2; and
FIG. 7 is an enlarged view of the portion ringed at numeral X in FIG. 6 .
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
As shown in FIG. 2, the preferred waterproofing material ( 10 ) of the invention is a laminate consisting of a core layer ( 11 ) containing montmorillonite. The core layer ( 11 ) is united with a support sheet ( 12 ) and is desirably but not essentially overlaid by a cover sheet ( 13 ).
The essentials of the material ( 10 ) of the invention will probably be best apparent from a detailed description of the way it is made and the apparatus which is used to make it.
Referring, therefore, to FIGS. 1 and 3, it will be seen that preferred apparatus of the invention comprises one or more silos ( 14 ) containing particulate sodium bentonite clay linked by respective feeder pipes ( 15 ) to a high speed, high shear mixer ( 16 ). Supply means for liquid components, namely water into which other constituents, such as alcohol, polyacrylates, carboxymethyl cellulose, have been dissolved, takes the form of tanks or nozzles ( 17 ) leading into the mixer ( 16 ). A mixing paddle ( 18 ) is shown diagrammatically in FIG. 3 . The mixer ( 16 ) is connected by a duct ( 19 ) to an extruder ( 20 ) which includes a vacuum chamber ( 22 ). Within the extruder, there is a cavity for receiving a deformable mass, which reduces in dimension from the end adjacent the inlet duct ( 19 ) to the outlet at die ( 24 ).
The aforesaid cavity is divided into two compartments by a perforated partition (not shown). A conventional worm or screw extends the length of the cavity, including through the partition and serves to convey the kneaded mixture received the mixer ( 16 ) through to the die ( 24 ). As the material is forced through the apertures of the partition it is further mixed and compressed. The tapering shape of the cavity contributes to compression of the material, which is then subject to suction (vacuum) as it approaches the die ( 24 ). This removes any air trapped or potentially trapped within the mixture so as to avoid any gap or weakness in the eventual waterproof sheet.
The die ( 24 ) is formed with a circular aperture and fitted with a conical or bell shaped insert so that the material is extruded in annular form, as shown in FIG. 1 . This believed to be the most effective way of obtaining an even pressure across a distance of anything from 1 to 4 m (approximately 3.25 to 13.0 feet) and obtaining a pipe having a diameter of between 30 and 170 cm and a thickness between 4 and 6 mm. The resulting pipe of extruded material is immediately slit at the top, as indicated in FIG. 1, by positioning a knife or blade at that position, adjacent the die ( 24 ). The material ( 30 ) is then supported upon rollers as it is gradually uncurled and lowered onto a roller conveyor ( 26 ).
Support and cover sheets ( 32 , 34 ) of geotextile material (woven or non-woven) are brought into engagement with the waterproofing sheet ( 30 ) as indicated in FIG. 3 . Their adhesion to the waterproofing material ( 30 ) may be enhanced by passing between one or more pressure nips (not shown), as this will more reliably embed the fabric of the sheets ( 32 ) and/or ( 34 ) into the deformable waterproofing layer ( 30 ).
The final laminate is formed into a roll ( 36 ) ready for storage or transportation.
As shown in FIG. 3 a , the particles of partially hydrated bentonite clay and to come into alignment as the degassed homogenised material is forced through the die ( 24 ). The support sheet ( 32 ) is preferably a sheet of woven material which is relatively loose weave, being quite porous in a direction transverse to its plane. It can be made of any geotexile material which is suitable for disposal within the ground for long periods. Typical materials for weaving or forming the fabric of the sheet ( 32 ) can be polypropylene, polyesters including nylon, and many other plastics materials alone or in blends. The material should be sufficiently strong to support the composite laminate to be formed and can be similar to many of the facing sheets used in relation to the prior known materials discussed in the introduction hereto. Polypropylene and cotton mixers can also be used. A typical support and/or cover sheet can be of a print weave and of a weight from 30 to 2000 g per square meter.
The particulate montmorillonite can be supplied to the hopper ( 14 ) from a mill or like supply and in the preferred embodiment is of 200 mesh. Finer mesh can be sued although great advantages are not obtained. Meshes up to 50 mesh can be used, but at sizes greater than 100 mesh, union between the montmorillonite particles is less effective.
The process which takes place in the mixer ( 16 ) can be either a continuous or a bath process. Within the mixer ( 16 ) a measured quantity (i.e. weight) or montmorillonite is mixed with a measured quantity of liquid from the tanks ( 17 ) to produce a shapable mass.
In making a typical product in accordance with the invention 5 kilogrammes of montmorillonite were mixed with 0.446 kilogrammes of sodium carboxymethyl cellulose (CMC), 2.5 liters of methanol and 1.8 liters of water. Both the CMC and the methanol make the mixed and kneaded product more flexible and extrudable.
Although the above particular mixtures have proved suitable many variations can be made.
Methanol alone or water alone can be used, but neither of these is satisfactory.
The material desirably contains a bulking agent, an anti-fungicidal preserving agent, to prevent growth of mould in or on the material and desirably a lubricant to assist in the extrusion process and provide a degree of flexibility to the plastic mass. CMC is a very desirable substance in that it provides all these properties. It has anti-fungicidal properties, it is a lubricant and it makes the product more flexible. It also has the great advantage that upon contact by water, in use, it dissolves. Those areas of the outer surface of the material when first contacted by water have the CMC dissolved out of them leaving micro pores into which more water can penetrate, wash out more CMC and cause rapid expansion of the adjacent montmorillonite.
This greatly increases the rate of water transfer into the material. A bulking agent which dissolves in water and aids water ingress to the montmorillonite is very desirable.
Instead of being provided by a single material these properties can be provided by other materials. Although many synthetic materials do have these properties, they tend to be expensive and simple plat extracts which are much cheaper than desired. As a bulking agent/lubricant guargum can be used or starch. In connection with these two materials a separate preservative such as any conventional anti-fungicidal or anti-microbial agent would have to be used.
Any convenient liquid alcohol can be used having from 1 to 12 carbon atoms. Above C12 alcohols tend to be too viscose for use but below that number any convenient alcohol can be used. It is expected, however, that methyl alcohol will be used because of its cheapness and easy availability. The CMC can be in the form of sodium carboxy methyl cellulose or any other convenient compound thereof. Protection against bacterial attack is important because the bacterial reactions can produce hydro carbons which react with the sodium ions in the clay. This can reduce the swellability of the clay.
The montmorillonite used is desirably sodium montmorillonite but calcium montmorillonite or treated calcium montmorillonite and other smectites can also be used.
If reinforcement is required within the montmorillonite layer in order that it can be laid on steep slopes without loss of function it can be desirable to incorporate a reinforcing layer within the plastic mass, as shown in FIGS. 4 and 5. This can be done by embedding a reinforcing layer ( 40 ) into the mass ( 11 ) as it is being extruded, the result being shown in FIG. 4 . In this respect, it must be mentioned that the plastic mass of waterproofing material can be extruded as a sheet, rather than a pipe which is slit to form a sheet, within the scope of the invention, although extrusion as a sheet does not produce such a good evenly spread layer when such a wide sheet is required.
The reinforcing layer can be made in the form of a core ( 42 ) having bristles ( 44 ) or comparable formations extending outwards, as shown in FIG. 5, which, with the cored ( 42 ) disposed centrally in the body of montmorillonite ( 11 ), extend to the surface thereof and contact and possibly project through the surface layers ( 12 , 13 ). The material of the reinforcement and the surface layers can be made such that the exposed bristles can be heat sealed to contact and be secured to the outer layers. It is envisaged that it would be possible for the montmorillonite mass to be extruded or formed into a pair of sheets and the reinforcement fed between them and to have its bristles projecting through each of the two part layers of the montmorillonite core and project to the other surfaces thereof and be united with the support/cover sheets.
The substance which convert the powdered montmorillonite into a plastic fluent mass may need some degree of treatment, for example by evaporation, drying or partial chemical change to ensure that the final material cannot deform further in use or in storage. This can be effected by means of a treatment facility (not shown) which the finished laminate is passed through.
When the liquid in the mixture is essentially water or an evaporable liquid the treatment facility will be in the form of an oven and it may reduce the solvent water convent of the montmorillonite containing layer from 20% down to 5% or less.
After leaving the treatment facility the laminate can be allowed to cool and then be fed to a store roll in conventional manner. A knife or the like can be provided for cutting the laminate as it leaves the oven when the roll is full.
As previously mentioned, the laminate may be passed between one or more pairs of rollers to cause the support/cover sheets ( 32 , 34 ) to be partially embedded in surface zones of the plastic mass of material forming the core ( 11 ) whilst the core is in a plastic state. There is no need for any adhesive, which is an expensive and unreliable component.
If the core is treated, either by evaporation or chemically so as to cause the core to harden, there is a physical locking of the surface portions of the core ( 11 ) with portions of the fabrics ( 32 , 34 ) physically uniting them to the surface without the need for adhesive.
This has two important consequences.
Firstly, because a good portion of the sheets ( 32 , 34 ) are embedded within the material of the core, only a small portion of the body of the fabric is exposed above the surface. Thus, in use that fabric surface will be in contact either with anchoring overburden (at least 150 mm of overlying material is recommended to protect such layers) or the underlying earth. The overburden or the earth penetrates the fabric quite easily (it is a very open fabric and after there is intimate contact between the overburden and the underlying earth). This again has two important consequences. Firstly, once the support layer ( 32 ) (which will normally be in contact with underlying earth) is intimately connected by the earth ground water enters contacts the montmorillonite and causes swelling which creates a seal.
It is a further advantage that because of the intimate contact of the underlying soil or the overburden with the montmorillonite through the support and cover sheets ( 32 , 34 ) there is no possibility that either the cover sheet ( 34 ) or the support sheet ( 32 ) can allow any venting of gas laterally through the fabric.
The second advantage of this is illustrated in FIGS. 6 and 7. In FIG. 6 a first piece ( 47 ) of the laminate material of the invention is shown overlapping a lower piece ( 48 ), both lying on the ground ( 49 ). The overlap cover sheet ( 50 ) of the second sheet ( 48 ) is in contact with the support sheet ( 51 ) on the piece ( 47 ). As illustrated in FIG. 7 the sheets ( 50 ) and ( 51 ) are in intimate contact and they are significantly penetrated by montmorillonite from the respective cores of the two laminate sheets. Upon entry of water in the direction of arrow ( 52 ) or ( 53 ) the montmorillonite in one or each of the cores can swell and expand into the unfilled portions of the fabric ( 50 , 51 ) and forming effectively a continuous layer of expanded montmorillonite uniting the two cores and providing a completely water tight seal.
The invention is not limited to the precise details of the foregoing and variations can be made thereto.
As well as montmorillonite, saponite and other smectites can be used.
In carrying out a preferred process a batch of about 60 kilogrammes was prepared, the figures given in the following being percentage by weight for the various components.
Firstly, 25% water was added to a mixer, followed by 16% sodium polyacrylate. To these was added 5% methyl alcohol. When these three had been mixed half of the total bentonite load of 63% was added. Once the mixture had become smooth 1% carboxy methyl cellulose (CMC) and a small (about 0.1%) of sodium hexametaphosphate was added. Both these materials were added slowly and after they had been added the mixture was stirred for some while. Thereafter the other half of the bentonite was added, the mixture kneaded for a short time and then passed to an extrusion machine wherein it was first driven towards a perforated plate whence it emerged in vermicelli-like form into a vacuum chamber. In the vacuum chamber air and any other gases such as reaction products and probably some evaporated alcohol are extracted.
The material is then driven towards an extrusion head.
The percentages of the various materials used can be varied as follows:
ITEM
PERCENTAGE RANGE (BY WEIGHT)
Water
15-25
Sodium Polyacrylate
8-16
(Methyl) Alcohol
0-5
Wyoming Bentonite
50-75
Carboxy Methyl Cellulose
0-3
Sodium Hexameta Phosphate
0-0.5
The function of the pressure during extrusion is to increase the density of the product by eliminating voids which might otherwise form within a less than coherent mass. This, together with the vacuum step which has removed air has the effect of compressing the material to a high density. This moves the molecules slightly closer together during extrusion thus increasing the rate of reaction and encouraging the formation of a complex from the intercalated polyacrylate. Desirably the density is greater than 1,000 kilogrammes per meter 3 (62.43 lb/ft 3 ) and a preferred density is over 1,300 kilogrammes per meter 3 .
The process described above produces a sheet material which can be used to form an ideal barrier against aggressive ionised fluids. Such ionised fluid will usually be leachates from plants or sites or may be atmospheric water or ground water contacting the capping of a landfill site. It has been found that fertiliser and other materials which may be applied to foliage above a landfill site forms a highly ionised material as aggressive as any leachate and which can seriously damage conventional bentonite liners.
The material referred to above has the acrylate or other liner so securely attached to the bentonite interlayers that the cation exchange capacity (CEC) of the material is nil or very low. This means that there is no possibility of the smectite turning to a calcium form which will not reswell after drying out. Further, as the liner is preferably a plastics material the inherently stable nature of the polymeric plastics material makes the possibility of it being attached by leachate or strong solutions quite remote. | 4y
|
BACKGROUND OF THE INVENTION
[0001] The subject matter described herein relates generally to operating wind turbines and, more particularly, to adjusting the power output of one or more wind turbines to provide a relatively more uniform output thereby improving the system frequency and other system control objectives such as scheduled power interchange.
[0002] Electricity generated from wind power can be highly variable due to the variations in wind speed and direction. This variation may cause rapid increases or drops in energy output delivered by wind turbines and wind plants to the power grid, which in turn, may have an adverse effect on the power grid. Because of the adverse effects on the power grid, various adverse cost impacts may occur, including that a wind farm operator may be required to pay a monetary penalty for providing more or less power than is typically produced, that the grid operator may need to run more expensive reserve generation or may incur fines for violating scheduled power interchange with neighboring systems. There is a need for wind power generation system that maintains a relatively more steady power output when connected to the power grid.
BRIEF DESCRIPTION OF THE INVENTION
[0003] In one aspect, a system for use in controlling a wind turbine's power output by a wind turbine controller is provided. The method includes determining a predicted wind speed for the wind turbine, determining a current wind turbine power output, and determining a predicted wind turbine power output utilizing the predicted wind speed. The method also includes comparing the current wind turbine power output to the predicted wind turbine power output and adjusting the wind turbine power output based on the comparison of the current wind turbine power output and the predicted wind turbine power output.
[0004] In another aspect, a system for use in operating a plurality of wind turbines controlling a wind turbine's power output is provided. The system includes a plurality of wind turbine controllers, each wind turbine controller of the plurality of wind turbine controllers operatively coupled to a wind turbine of a plurality of wind turbines, and a site controller coupled in communication with the plurality of wind turbine controllers and configured to determine a predicted wind speed for the wind turbine, determine a current wind turbine power output, and determine a predicted wind turbine power output utilizing the predicted wind speed. The site controller is also configured to compare the current wind turbine power output to the predicted wind turbine power output, and adjust the wind turbine power output based on the comparison of the current wind turbine power output and the predicted wind turbine power output.
[0005] In another aspect, a device for use in controlling a wind turbine's power output is provided. The device includes a memory device configured to store a target power output range, a processor coupled to the memory device and programmed to: determine a predicted wind speed for the wind turbine, determine a current wind turbine power output, determine a predicted wind turbine power output utilizing the predicted wind speed, and compare the current wind turbine power output to the predicted wind turbine power output, and a communication interface coupled to the processor and configured to adjust the wind turbine power output based on the comparison of the current wind turbine power output and the predicted wind turbine power output of at least a first wind turbine controller of the plurality of wind turbine controllers.
[0006] In yet another aspect, one or more computer readable storage media having computer-executable instructions embodied thereon are provided. The one or more computer readable storage media include computer-executable instructions embodied thereon, wherein when executed by at least one processor, the computer-executable instructions cause the processor to determine a predicted wind speed for a wind turbine, determine a current wind turbine power output, and determine a predicted wind turbine power output utilizing the predicted wind speed.
[0007] The one or more computer readable storage media also include computer-executable instructions that cause the processor to compare the current wind turbine power output to the predicted wind turbine power output, and adjust the wind turbine power output based on the comparison of the current wind turbine power output and the predicted wind turbine power output.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a perspective view of an exemplary wind turbine.
[0009] FIG. 2 is a block diagram illustrating an exemplary wind turbine controller for use with the wind turbine shown in FIG. 1 .
[0010] FIG. 3 is a block diagram illustrating an exemplary computing device.
[0011] FIG. 4 is a block diagram illustrating an exemplary system for use in operating one or more wind turbines, such as the wind turbine shown in FIG. 1 .
[0012] FIG. 5 is a flowchart of an exemplary method for use in operating one or more wind turbines using the system shown in FIG. 4 .
[0013] FIG. 6 is an exemplary graph showing the relationship between power output of wind turbine 100 versus time using the method shown in FIG. 5 .
[0014] FIG. 7 is an exemplary graph showing the relationship between power output of wind turbine 100 versus time using the method shown in FIG. 5 .
DETAILED DESCRIPTION OF THE INVENTION
[0015] The embodiments described herein facilitate operating one or more wind turbines in a site by maintaining a relatively steady power output in response to meteorological conditions. Power output may be determined by direct measurement and/or by calculating wind speeds based on wind turbine characteristics (e.g., wind turbine dimensions, blade geometry, and/or blade surface roughness) and/or operating conditions (e.g., wind speed and/or wind direction). When a power output level deviates from a target power output level, an operational adjustment may be transmitted to one or more wind turbine controllers that are coupled to the wind turbines.
[0016] A target power output level may include, without limitation, a power output level defined by a regulation (e.g., enacted by a municipality or other government body), by a command issued by the power system operator, by a contractual or property-based obligation, or by a preference of an operator of a wind turbine site.
[0017] In some embodiments, in response to a predicted wind speed that would correspond to a predicted power output level below the target power output level, an operational adjustment is calculated to gradually decrease the power output to avoid severe power output changes. In other embodiments, in response to a predicted wind speed that would correspond to a predicted power output level at or above the target power output level, an operational adjustment is calculated to permit a gradual increase of the power output to avoid an unacceptably rapid increase in power output. In other embodiments, in response to a predicted wind speed that would correspond to a predicted power output level that would correspond to a rate-of-change at or above the target power output threshold, an operational adjustment is calculated to permit a gradual change of the power output to avoid an unacceptably rapid change in the rate-of-change of the power output.
[0018] Embodiments are described herein with reference to geographic positions. As used herein the term “geographic position” refers to a point in a two-dimensional or three-dimensional space. For example, a geographic position may be expressed in two dimensions as a latitude and a longitude, or in three dimensions as a latitude, a longitude, and an elevation.
[0019] FIG. 1 is a perspective view of an exemplary wind turbine 100 . Wind turbine 100 includes a nacelle 102 that houses a generator (not shown in FIG. 1 ). Nacelle 102 is mounted on a tower 104 (only a portion of tower 104 is shown in FIG. 1 ). Tower 104 may have any suitable height that facilitates operation of wind turbine 100 as described herein. In an exemplary embodiment, wind turbine 100 also includes a rotor 106 that includes three rotor blades 108 coupled to a rotating hub 110 . Alternatively, wind turbine 100 may include any number of rotor blades 108 that enable operation of wind turbine 100 as described herein. In an exemplary embodiment, wind turbine 100 includes a gearbox (not shown) that is rotatably coupled to rotor 106 and to the generator, and an energy storage device (not shown) including, but not limited to, a capacitor, a battery, a flywheel, and rotor 106 . In one embodiment, the energy storage device is configured to allow access to an inherent inertia of the wind turbine 100 using a device such as, but not limited to, a flywheel, and rotor 106 .
[0020] In some embodiments, wind turbine 100 includes one or more sensors 120 and/or control devices 135 (shown in FIG. 2 ). Sensors 120 sense or detect wind turbine operating conditions. For example, sensor(s) 120 may include a wind speed and/or a direction sensor (e.g., an anemometer), an ambient air temperature sensor, an air density sensor, an atmospheric pressure sensor, a humidity sensor, a power output sensor, a blade pitch sensor, a turbine speed sensor, a gear ratio sensor, and/or any sensor suitable for use with wind turbine 100 . Each sensor 120 is located according to its function. For example, an anemometer may be positioned on an outside surface of nacelle 102 , such that the anemometer is exposed to air surrounding wind turbine 100 . Each sensor 120 generates and transmits one or more signals corresponding to a detected operating condition. For example, an anemometer transmits a signal indicating a wind speed and/or a wind direction. In the exemplary embodiment, sensor 120 is a light detection and ranging (LIDAR) system sensor and is configured to predict wind speeds. Moreover, each sensor 120 may transmit a signal continuously, periodically, or only once, for example, though other signal timings are also contemplated. Furthermore, each sensor 120 may transmit a signal either in an analog form or in a digital form. In one embodiment, a forecast for meteorological data is utilized in place of sensor 120 .
[0021] Control devices 135 are configured to control an operation of wind turbine 100 and may include, without limitation, a brake, a relay, a motor, a solenoid, and/or a servomechanism. A control device 135 may adjust a physical configuration of wind turbine 100 , such as an angle or pitch of rotor blades 108 and/or an orientation of nacelle 102 or rotor 106 with respect to tower 104 .
[0022] FIG. 2 is a block diagram illustrating an exemplary wind turbine controller 200 for use with wind turbine 100 . Wind turbine controller 200 includes a processor 205 for executing instructions and a memory device 210 configured to store data, such as computer-executable instructions and operating parameters. Wind turbine controller 200 also includes a communication interface 215 . Communication interface 215 is configured to be coupled in signal communication with one or more remote devices, such as another wind turbine controller 200 and/or a computing device (shown in FIG. 3 ).
[0023] In some embodiments, wind turbine controller 200 includes one or more sensor interfaces 220 . Sensor interface 220 is configured to be communicatively coupled to one or more sensors 120 , such as a first sensor 125 and a second sensor 130 , and may be configured to receive one or more signals from each sensor 120 . Sensor interface 220 facilitates monitoring and/or operating wind turbine 100 . For example, wind turbine controller 200 may monitor operating conditions (e.g., wind speed, wind direction, rotor speed, and/or power output) of wind turbine 100 based on signals provided by sensors 120 . In one embodiment, the wind turbine controller 200 is configured to calculate a power output produced by the corresponding wind turbine 100 based on one or more wind turbine characteristics (e.g., wind turbine dimensions and/or a rotor blade geometry), one or more operating parameters (e.g., a wind speed, a wind direction, a rotor blade tip speed, or a rotor blade pitch angle), and/or an operational state (e.g., disabled, curtailed, or normal) of a wind turbine 100 .
[0024] In an exemplary embodiment, processor 205 executes one or more monitoring software applications and/or control software applications. A software application may produce one or more operating parameters that indicate an operating condition, and memory device 210 may be configured to store the operating parameters. For example, a history of operating parameters may be stored in memory device 210 .
[0025] In some embodiments, wind turbine controller 200 also includes a control interface 225 , which is configured to be communicatively coupled to one or more control devices 135 , such as a first control device 140 and a second control device 145 . In one embodiment, wind turbine control interface 225 is configured to operate control device 135 including a brake to prevent rotor 106 (shown in FIG. 1 ) from rotating. In addition, or in the alternative, wind turbine control interface 225 may operate a control device 135 including a blade pitch servomechanism to adjust one or more rotor blades 108 (shown in FIG. 1 ) to a desired and/or predetermined pitch. In an alternative embodiment, electrical power and torque are operated by control device 135 . The brake, the blade pitch servomechanism, and the electrical power may be operated by the same control device 135 or a first control device 135 and a second control device 135 . In the exemplary embodiment, wind turbine controller 200 is configured to operate control devices 135 to achieve a desired power output.
[0026] FIG. 3 is a block diagram illustrating an exemplary computing device 300 . Computing device 300 includes a processor 305 for executing instructions. In some embodiments, executable instructions are stored in a memory device 310 . Memory device 310 is any device allowing information, such as executable instructions and/or other data, to be stored and retrieved.
[0027] In some embodiments, computing device 300 includes at least one presentation device 315 for presenting information to user 320 . Presentation device 315 is any component capable of conveying information to user 320 . Presentation device 315 may include, without limitation, a display device (e.g., a liquid crystal display (LCD), organic light emitting diode (OLED) display, or “electronic ink” display) and/or an audio output device (e.g., a speaker or headphones). In some embodiments, presentation device 315 includes an output adapter, such as a video adapter and/or an audio adapter. An output adapter is operatively coupled to processor 305 and configured to be operatively coupled to an output device, such as a display device or an audio output device.
[0028] In some embodiments, computing device 300 includes an input device 325 for receiving input from user 320 . Input device 325 may include, for example, a keyboard, a pointing device, a mouse, a stylus, a touch sensitive panel (e.g., a touch pad or a touch screen), a gyroscope, an accelerometer, a position detector, and/or an audio input device. A single component, such as a touch screen, may function as both an output device of presentation device 315 and input device 325 . Computing device 300 also includes a communication interface 330 , which is configured to be communicatively coupled to one or more wind turbine controllers 200 and/or one or more other computing devices 300 .
[0029] Stored in memory device 310 are, for example, computer readable instructions for determining and responding to power output levels, providing a user interface to user 320 via presentation device 315 , and/or receiving and processing input (e.g., target power output levels) from input device 325 . In addition, or alternatively, memory device 310 may be configured to store target power output levels, measured power output levels, calculated power output levels, and/or any other data suitable for use with the methods described herein.
[0030] FIG. 4 is a block diagram illustrating an exemplary system 400 for use in operating one or more wind turbines 100 . System 400 includes a network 405 . For example, network 405 may include, without limitation, the Internet, a local area network (LAN), a wide area network (WAN), a wireless LAN (WLAN), a mesh network, and/or a virtual private network (VPN).
[0031] In an exemplary embodiment, a wind turbine site 410 includes a plurality of wind turbines 100 , each of which includes a wind turbine controller 200 . One or more computing devices 300 (shown in FIG. 3 ), such as a site controller 415 , are configured to be coupled in signal communication with wind turbine controllers 200 via network 405 .
[0032] In an exemplary embodiment, site controller 415 is positioned at wind turbine site 410 . Alternatively, site controller 415 may be positioned outside wind turbine site 410 . For example, site controller 415 may be communicatively coupled to wind turbine controllers 200 at a plurality of wind turbine sites 410 .
[0033] Each of site controller 415 and wind turbine controller 200 includes a processor, (shown in FIGS. 2 and 3 ). A processor may include a processing unit, such as, without limitation, an integrated circuit (IC), an application specific integrated circuit (ASIC), a microcomputer, a programmable logic controller (PLC), and/or any other programmable circuit. A processor may include multiple processing units (e.g., in a multi-core configuration). Each of site controller 415 and wind turbine controller 200 is configurable to perform the operations described herein by programming the corresponding processor. For example, a processor may be programmed by encoding an operation as one or more executable instructions and providing the executable instructions to the processor in a memory device (also shown in FIGS. 2 and 3 ) that is coupled to the processor. A memory device may include, without limitation, one or more random access memory (RAM) devices, one or more storage devices, and/or one or more computer readable media.
[0034] In some embodiments, one or more wind speed sensors 420 are coupled in communication with site controller 415 . Wind speed sensors 420 are configured to provide a predicted wind speed for indicating a wind speed corresponding to a geographic position. In one embodiment, sensors 120 of one or more wind turbines 100 include a wind speed sensor 420 . Wind speed sensors 420 may be further configured to provide a direction associated with a predicted wind speed measurement. For example, a wind speed sensor 420 may provide wind level measurements associated with a plurality of directions at a single geographic position.
[0035] In an exemplary embodiment, system 400 enables operation of wind turbines 100 such that a relatively balanced system power output is maintained. System 400 may further enable operation of wind turbines 100 such that power output of site 410 is optimized within the bounds of the target power output levels.
[0036] FIG. 5 is a flowchart of an exemplary method 500 for use in operating one or more wind turbines 100 (shown in FIG. 1 ) using system 400 (shown in FIG. 4 ). All or a portion of method 500 may be performed by one or more computing devices 300 (shown in FIG. 3 ), such as, without limitation, wind turbine controller 200 , and/or site controller 415 (shown in FIGS. 2 and 4 ). In the exemplary embodiment, site controller 415 determines 505 predicted wind speeds associated with wind turbines 100 using sensors 120 and/or wind speed sensors 420 . The predicted wind speeds may be determined 505 in a time frame ranging from 1 second to 10 minutes in advance. In the exemplary embodiment, the predicted wind speeds are determined 505 at least one second in advance.
[0037] In the exemplary embodiment, the current power output of the wind turbine 100 is determined 510 by at least one of the wind turbine controller 200 and the site controller 415 . In one embodiment, wind turbine controller 200 calculates a power output level for wind turbine 100 and transmits the calculated power output level to site controller 415 . In an alternative embodiment, wind turbine controller 200 transmits the wind turbine characteristics, operating parameters, and/or operational state to site controller 415 and site controller 415 calculates the power output level produced by wind turbine 100 .
[0038] Whether performed by wind turbine controller 200 or site controller 415 , determining 510 a current power output level produced by a wind turbine 100 provides a current power output level associated with a corresponding geographic position at certain operating parameters.
[0039] In addition, or alternatively, wind speed sensors 420 may provide wind speed level measurements indicating a wind speed level associated with a geographic position and, optionally, with a plurality of directions. In some embodiments, wind speed sensor 420 is included as a sensor 120 of one or more wind turbines 100 . Site controller 415 determines 510 a current power output at one or more geographic positions based on the calculated and/or measured wind speed. When measured wind speed is used, the current power output may also be determined 510 .
[0040] In the exemplary embodiment, site controller 415 determines 515 if the predicted wind speed allows wind turbine 100 to produce power within a target power output range, using the determined 505 predicted wind speeds. In one embodiment, the target power output range is expressed as a specific power level in the range of zero to 100% of wind turbine rating, with deadband requirement which specifies the required accuracy in the range from zero to 100 percent of turbine rating. Alternatively, the target power output range can be any range that enables the disclosure to function as described herein. In an alternative embodiment, site controller 415 determines 515 if the predicted wind speed allow wind turbine 100 to produce a power output within a threshold value. The threshold value may be defined in absolute (e.g., 2 kW, 3 kW, or 5 kW) or relative (e.g., 3%, 5%, or 10%) terms.
[0041] In an alternative embodiment, site controller 415 determines 515 if the predicted wind speed will cause wind turbine 100 to produce a rate-of-change of power output outside of a threshold value. In one embodiment, the threshold value is may be defined in absolute (e.g., 2 MW/min, −2 MW/Min, −5 MW/min) or relative (e.g., +3%/min, −4%/min, −5%/10 minutes).
[0042] If the predicted wind speed will not allow wind turbine 100 to produce power within the target power output range or threshold value, site controller 415 calculates 520 a desired power output level for one or more wind turbines 100 . The calculated 520 desired output level is a power output level that can be supported by the determined 505 predicted wind speeds.
[0043] Based on the calculated 520 desired power output level associated with wind turbine 100 , site controller 415 determines 525 an operational adjustment. In one embodiment, determining 525 an operational adjustment includes transmitting the desired maximum power output level associated with a wind turbine 100 to a corresponding wind turbine controller 200 . In such an embodiment, wind turbine controller 200 is configured to adjust operating parameters of wind turbine 100 to achieve the desired power output. In an alternate embodiment, site controller 415 is configured to determine one or more operating parameters (e.g., a rotor blade pitch angle, a maximum rotor blade speed, and/or a maximum torque) for wind turbine 100 and transmit to wind turbine controller 200 an operational adjustment that includes the determined operating parameters.
[0044] Operational adjustments may be determined 525 such that a difference between a predicted power output, corresponding to a predicted wind speed, and the target power output level decreases when the operational adjustment is applied. In one embodiment, when the predicted power output corresponding to a predicted wind speed will be below the target power output range or threshold value, an operational adjustment is determined 525 to reduce the power output to prevent a severe loss of power. In an alternative embodiment, when the predicted wind speed will cause wind turbine 100 to produce a predicted power output above the target power output range or threshold value, an operational adjustment may be determined 525 to reduce the power output to maintain the power output within the target power output range or threshold value. In yet another alternative embodiment, if the current power output is below the target power output range or threshold value and the predicted power output will produce a predicted power output within the target power output range or threshold value, an operational adjustment may be determined 525 to increase the power output.
[0045] In the exemplary embodiment, when a decision to decrease the power output of wind turbine 100 is determined 525 , site controller 415 gradually reduces 530 the power output to the calculated 520 desired output level. In an alternative embodiment, if a decision to increase the power output is determined 525 , site controller 415 gradually increases 530 the power output to the calculated 520 desired output level. In the exemplary embodiment, to prevent the power output levels from varying dramatically, if at any time during the gradual increase/decrease of power output the current wind cannot sustain the gradual increase/decrease of power output, site controller 415 utilizes 535 energy stored within the energy storage device (not shown). When the gradual adjustment 530 has finished, wind turbine 100 is maintained 540 in the current operating conditions.
[0046] FIGS. 6 and 7 are exemplary graphs showing the relationship between power output of wind turbine 100 versus time using the method shown in FIG. 5 . A solid line 602 represents the power output resulting from a change in wind speed. A dashed line 604 represents the power output gradually adjusting 530 as a result of implementing the determined 525 operational adjustments. Portion 606 of solid line 602 represents the determined 510 current power output and portion 608 of solid line 602 represents the calculated 520 desired output level of wind turbine 100 .
[0047] In one embodiment, as shown in FIG. 6 , if site controller 415 makes a determination 525 to reduce the power output in response to a low predicted power output, an operational adjustment to gradually decrease 530 the power output to the calculated 520 desired output level is initialized at point 620 . The power output is gradually decreased 530 until the power output is below the calculated 520 desired output level, such as point 608 . From point 622 to point 624 , power output is above what can be produced from the current wind alone. When the power output arrives at the point 622 , at which point the power output cannot be sustained by the current wind, site controller 415 utilizes energy stored in the energy storage device until the current wind can sustain the power output, such as point 624 .
[0048] At point 624 , the power output falls below the calculated 520 desired output level until point 626 . From point 624 until point 626 , wind turbine 100 returns an equal amount of energy used between points 622 to 624 to the energy storage device. At point 626 , the power output is kept in line with the calculated 520 desired output level and wind turbine 100 is maintained 540 at the current operating conditions.
[0049] In an alternative embodiment, as shown in FIG. 7 , if site controller 415 makes a determination 525 to increase the power output in response to a high predicted power output, an operational adjustment to gradually increase 530 the power output to the calculated 520 desired power output level is initialized at point 630 . The power output is gradually increased 530 to the calculated 520 desired output level. From point 630 to point 632 , power output is above what can be produced from the current wind alone. When the gradual increase 530 of power output is initialized at point 630 , at which point the power output cannot be sustained by the current wind, site controller 415 utilizes energy stored in the energy storage device until the current wind can sustain the power output, such as point 632 .
[0050] From point 632 , the power output continues to gradually increase towards the calculated 520 desired output level. In one embodiment, when the power output is capable of maintaining the calculated 520 desired output level, at point 634 , site controller 415 maintains the power output below the calculated 520 desired output level and returns power to the energy storage device until an equal amount of energy used between points 630 to 632 is returned to the energy storage device. The power output is then maintained 540 at the current operating conditions at the calculated 520 desired output level.
[0051] Method 500 may be performed repeatedly (e.g., continuously, periodically, or upon request), enabling continual adjustment to operation of wind turbines 100 in site 410 . For example, as the wind direction changes, the power output level at second geographic position 430 may increase, while the power output level at first geographic position 425 decreases. Accordingly, operational adjustments may be determined 525 and transmitted to ensure the target power output range or threshold value at second geographic position 430 is not exceeded.
[0052] Similarly, if a wind turbine, such as first wind turbine 435 , is disabled for maintenance or repair, or is operated at a reduced level of operation for any reason, the power output level decreases, and site controller 415 may automatically increase a desired maximum power output level associated with a second wind turbine 440 and a third wind turbine 445 , such that the power output of second wind turbine 440 and third wind turbine 445 is increased. When first wind turbine 435 is activated again, power output produced by first wind turbine 435 is reflected in the aggregate power output level, and site controller 415 may adjust the desired maximum power output level of second wind turbine 440 and third wind turbine 445 downward to ensure compliance with the target power output ranges or threshold levels.
[0053] Embodiments provided herein facilitate automatically and continually adjusting the operation of wind turbines based on a power output level at one or more geographic positions that are associated with a target power output range or threshold value. Adjusting wind turbine operation as described herein enables an operator of a wind turbine site to provide a relatively constant power output, and/or a relatively lower rate-of-change of power output when faced with variable metrological conditions.
[0054] The methods described herein may be encoded as executable instructions embodied in a computer readable storage medium including, without limitation, a memory device of a computing device. Such instructions, when executed by a processor, cause the processor to perform at least a portion of the methods described herein.
[0055] Exemplary embodiments of a wind turbine control system are described above in detail. The system, devices, wind turbine, and included assemblies are not limited to the specific embodiments described herein, but rather each component may be utilized independently and separately from other components described herein.
[0056] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. | 4y
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to artificial kidneys, and more particularly, to a method and system for pumping two liquids in equal quantities and with a continuous flow rate in two separate conduits of an artificial kidney.
2. Description of the Related Art
Artificial kidneys typically pump two liquids, for example, fresh and used dialysis liquid, into and out of a hemodialyser. An example of a known apparatus for pumping the two liquids is illustrated in FIG. 1 and includes, a pumping device 106 having two complementary chambers 112 and 113 associated with four valves 126, 127, 128 and 129, disposed, respectively, in lines 118, 119, 121 and 120. The operation of such a device is effected over two periods. During the first period, the valves 126 and 127 are closed, and valves 128 and 129 are open. A reciprocating piston 109, separating the two complementary chambers 112 and 113, is moved in direction A so as to aspirate a first liquid into chamber 112, and, at the same time, discharge an equal quantity of a second liquid from chamber 113. In the second period, valves 128 and 129 are closed, and valves 126 and 127 are open, and piston 109 is moved in direction R to discharge from chamber 112 a quantity of the first liquid into line 118, and to simultaneously aspirate a quantity of the second liquid into chamber 113 from line 119.
With the device depicted in FIG. 1, it is possible to pump two liquids in substantially equal quantities in two separate conduits, but the flows in the four lines 118, 119, 120 and 121, are discontinous due to the alternating movement of piston 109 during reciprocation.
To mitigate this drawback, apparatus have been proposed which, effectively, comprise two of the devices of FIG. 1 arranged in parallel. Such a system is illustrated in FIG. 2 and includes two pumping devices 206 and 206' having respective complementary chambers 212, 213 and 212', 213' associated with eight valves 226, 226'; 227, 227'; 228, 228'; and 229, 229', disposed in respective conduits or lines connected to the chambers of pumping devices 206 and 206' as shown.
Operation of the device of FIG. 2 is as follows. In a first period, valves 226, 227, 228' and 229' are closed; and valves 228, 229, 226' and 227' are opened. A pair of reciprocating pistons 209 and 209', disposed in pumps 206 and 206', respectively, are then moved in direction A. Movement of piston 209 in direction A aspirates the first liquid into chamber 212 from an intake line 220, and discharges the second liquid from chamber 213 into an outlet line 221. Simultaneously, movement of piston 209' in direction A, discharges the first liquid from chamber 213' into an outlet line 218, and aspirates the second liquid into chamber 212' from an intake line 219.
In a second period, valves 226, 227, 228' and 229' are opened, and valves 228, 229, 226' and 227' are closed. Reciprocating pistons 209 and 209' are then moved in direction R. Piston 209' upon being moved in direction R, aspirates the first liquid into chamber 213', and discharges the second liquid from chamber 212' into line 221. Simultaneously, movement of the piston 209 in direction R aspirates the second liquid into chamber 213 from line 219, and discharges the first liquid from chamber 212 into line 218.
By means of systems such as illustrated in FIG. 2, substantially continuous flow through lines 218, 219, 220, 221 can be attained.
A system similar to the one described above with reference to FIG. 2 is described in German Patent Application DOS 2 634 238. However, the embodiments of the device disclosed in that German patent utilize elastic members disposed in respective chambers rather than reciprocating pistons. The circulation of the fresh and used dialysis liquid comprising the first and second liquids is accomplished by two pumps displacing the membranes in the chambers to displace the dialysis liquid.
In principle, these prior art systems allow two liquids in two separate conduits to be pumped in substantially equal quantities and with a substantially continuous flow. However, small errors occur each time the valves (226, 227, 228, 229, 226', 227', 228', 229') are opened or closed. With a high frequency of opening and closing of the valves, the accumulation of these small errors leads to an even higher overall error.
It is therefore an object of the present invention to provide a method and an apparatus for pumping equal quantities of two liquids through two separate conduits in which the errors associated with the valves opening and closing are substantially reduced.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
SUMMARY OF THE INVENTION
A system is provided for pumping a predetermined quantity of a first liquid from a source through the outlet of a discharge line to be attached to an appliance such as a hemodialyser of an artificial kidney, and for pumping the same quantity of a second liquid from an intake line inlet into evacuation means, with both liquids moving at a substantially equal and constant flow. The system comprises a main reciprocating pump means having first and second complementary main chambers, and first and second auxiliary reciprocating pump means. The first auxiliary pump means has first and second complementary auxiliary chambers, and the second auxiliary pump means has third and fourth complementary auxiliary chambers. A drive means is provided for reciprocating the main pump means and the first and second auxiliary pump means in unison between a first and second direction such that the volume of the first main chamber varies inversely with the volume of the second and fourth auxiliary chambers, and directly with the volume of the first and third auxiliary chambers.
A first intake line means is provided for aspirating the predetermined quantity of the first liquid into the first main chamber from both the fourth auxiliary chamber and from a source of the first liquid during reciprocation of the pump means in the first direction, and for aspirating the quantity of the first liquid into the fourth auxiliary chamber from the source of the first liquid during reciprocation of the pump means in the second direction. A first discharge line means is provided for discharging the quantity of the first liquid into both the second auxiliary chamber and into a discharge line outlet during reciprocation of the pump means in the second direction, and for discharging the quantity of the first liquid into a discharge line outlet from the second auxiliary chamber during reciprocation of the pump means in the first direction.
A second intake line means is provided for aspirating the quantity of the second liquid into the second main chamber from both an intake line inlet and the third auxiliary chamber during reciprocation of the pump means in the second direction, and for aspirating the quantity of the second liquid into the third auxiliary chamber from an intake line inlet during reciprocation of the pump means in the first direction. A second discharge line means is provided for discharging the quantity of the second liquid into both the first auxiliary chamber and a drain during reciprocation of the pump means in the first direction, and for discharging the quantity of the second liquid into the drain from the first auxiliary chamber during reciprocation of the pump means in the second direction. The above described system operates such that the same quantity of the first and second liquid moves in a substantially constant flow during reciprocation of the pump means in both the first and the second direction.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate a presently preferred embodiment and method of the invention and, together with the general description given above and the detailed description of the preferred embodiment and method given below, serve to explain the principles of the invention.
FIG. 1 illustrates schematically a prior art pumping device having two complementary chambers associated with four valves;
FIG. 2 illustrates schematically a second prior art device essentially incorporating two of the devices illustrated in FIG. 1 disposed in parallel;
FIG. 3 schematically illustrates a first embodiment of the present invention applied to pumping dialysis liquid in an artificial kidney;
FIG. 4 graphically illustrates variations of flow with respect to time for a first liquid being pumped through the embodiment of the present invention illustrated in FIG. 3;
FIG. 5 graphically illustrates variations of flow with respect to time for a second liquid being pumped through the embodiment of the present invention illustrated in FIG. 3;
FIG. 6 schematically illustrates a second embodiment of the present invention; and
FIG. 7 schematically illustrates a third embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Reference will now be made in detail to the present preferred embodiments and method of the invention as illustrated in the accompanying drawings.
In accordance with the present invention, and as illustrated in FIG. 3, there is provided pumping system for an artificial kidney. As embodied herein, the pumping system is hooked to a hemodialyser 1 separated into two compartments 3 and 4 by a semi-permeable membrane 2 permitting dialysis and ultrafiltration of the blood. First compartment 3 is intended for the extracorporeal circulation of the blood, and second compartment 4 is intended for the circulation of the dialysis liquid flowing from a source 60, into the hemodialyser, then from the hemodialyser towards an evacuation means 62. As embodied herein, evacuation means 62 may include regeneration means.
In accordance with the invention the system includes a main reciprocating pump means and first and second auxiliary reciprocating pump means. As embodied herein, the main pump means comprises a main pump 6, and the first and second auxiliary pump means includes auxiliary pumps 7 and 8, respectively. Main pump 6 comprises a cylinder 40 which is separated into complementary first and second main chambers 12 and 13 by a piston 9. Each auxiliary pump 7 and 8 includes a cylinder 46 and 48, respectively, which are separated into first, second, third, and fourth auxiliary chambers 14, 15, 16, and 17, respectively, by a piston 10 disposed in cylinder 46 and a piston 11 disposed in cylinder 48. Each of the pistons is tightly sealed about its periphery in its respective cylinder. In the present preferred embodiment of the invention, pistons 10 and 11 are coaxial and fixedly connected to one another, and to main piston 9, by a rod 30. A drive means, which will be described hereinafter, is connected to rod 30 to move pistons 9, 10 and 11 in unison in a reciprocating motion between directions A and R.
Main chamber 12 of pump 6 holds the fresh dialysis liquid and is connected to dialysis liquid source 60 and to fourth auxiliary chamber 17 by a first intake line means. As embodied herein, the first intake line means includes lines 20 and 23 and valve means 28 disposed in line 20.
Main chamber 12 is also connected to an inlet 42 of hemodialyser 1 and to second auxiliary chamber 15 by a first discharge line means, which, as embodied herein comprises lines 18 and 24, and valve means 26 disposed in line 18.
Main chamber 13 holds the used dialysis liquid and is connected to an outlet 44 of hemodialyser 1 and to third auxiliary chamber 16 by a second intake line means, which, as embodied herein comprises lines 19 and 25, and valve means 27 disposed in line 25. Main chamber 13 is also connected to an evacuation or regeneration means 62 for the used dialysis liquid and to first auxiliary chamber 14 by a second discharge line means, which, as embodied herein, comprises lines 21 and 22, and valve means 29 disposed in line 21.
In each auxiliary pump 7 and 8, second and fourth auxiliary chambers 15 and 17 cycle fresh dialysis liquid, and first and third auxiliary chambers, 14 and 16, cycle the used dialysis liquid.
Auxiliary chamber 14 is connected to line 21 downstream of valve means 29 by line 22. Auxiliary chamber 15 is connected to discharge line 18 downstream of valve means 26 by line 24. Auxiliary chamber 16 is connected to output line 19 upstream of valve means 27 by line 25. Auxiliary chamber 17 is connected to intake line 20 upstream of valve means 28 by line 23.
Auxiliary chambers 14 and 16 regulate the flow of the used dialysis liquid, while auxiliary chambers 15 and 17 regulate the flow of the fresh dialysis liquid. The design of pumps 6, 7 and 8 is selected such that simultaneous displacement of the pistons disposed therein displaces a quantity of liquid in each main chamber 12 and 13 which is twice the quantity of liquid displaced in each auxiliary chamber 14, 15, 16 and 17. In the case where pumps 6, 7, and 8 have a circular cross section, auxiliary pumps 7 and 8 may be configured with a cross section equal to half the cross section of main pump 6.
Operation of the apparatus illustrated schematically in FIG. 3 is discussed below. Rod 30 is connected to each piston 9, 10 and 11 and is driven in a rectilinear reciprocating motion by any type of suitable motor or drive menas schematically represented by 50 to reciprocate pistons 9, 10 and 11 between a first direction represented by arrow A, and a second direction represented by arrow B.
In a first stage called the aspiration stage, valve means 26 and 27 are closed, and valve means 28 and 29 are open. Rod 30 is driven such that pistons 9, 10 and 11 are displaced in the direction of arrow A. The displacement of the pistons in direction A draws fresh dialysis liquid into chamber 12 and ejects used dialysis liquid from chamber 13. One half of the dialysis liquid drawn into chamber 12 comes from the source of fresh dialysis liquid 60, through line 20 and valve 28, and one-half of the fresh dialysis liquid drawn into chamber 12 comes from auxiliary chamber 17 via lines 23, 20 and valve 28.
With movement of pistons 9, 10 and 11 still in direction A, one-half of the dialysis liquid discharged from chamber 13 is drawn into auxiliary chamber 14 via lines 21, 22 and valve 29 by simultaneous displacement of pistons 9 and 10; and the other half of the dialysis liquid is discharged through line 21 and valve 29 to evacuation or regeneration means 60. Displacement of piston 10 in direction A simultaneously delivers the fresh dialysis liquid from auxiliary chamber 15 to hemodialyser 1 via lines 24 and 18 since valve 26 is closed. Displacement of the piston 11 in direction A aspirates used dialysis liquid from hemodialyser 1 into auxiliary chamber 16 via lines 19 and 25 since valve 27 is closed.
In a second stage called the delivery stage, rod 30 is driven such that pistons 9, 10 and 11 are displaced in the direction of arrow R. Valve means 26 and 27 are open, and valve means 28 and 29 are closed.
The decrease in volume of main chamber 12 by movement of piston 9 in direction R aspirates equal quantities of fresh dialysis liquid into auxiliary chamber 15 via lines 18, 24 and valve 26 on the one hand, and on the other hand, into hemodialyser 1 through line 18, valve 26, and first discharge line outlet 42. The increase in volume of chamber 13 and decrease in volume of chamber 16 by movement of pistons 9 and 11 in direction R aspirates used dialysis liquid into chamber 13 via outlet line 19 and valve 27 from hemodialyser 1, and from chamber 16 into chamber 13 via lines 19, 25 and valve 27.
In effect, the movement of pistons 9, 10 and 11 in direction R discharges used dialysis liquid from auxiliary chamber 16 and simultaneously aspirates fresh dialysis liquid into auxiliary chamber 17 via line 20 and line 23. At the same time, used dialysis liquid from auxiliary chamber 14 is discharged into line 21 from chamber 14 via line 22.
The successive closing and opening of the valve means 26, 27, 28 and 29 in the sequence described above, as well as the change in the direction of displacement of rod 30 and pistons 9, 10 and 11, may be actuated by means of end of travel contacts integral with rod 30 and associated with a guidance system (not shown) of any known type, such as a microprocessor for controlling the sequential opening and closing of the valves.
With reference to the graphs of FIGS. 4 and 5 illustrating the flows in the various lines, it will, on the one hand, be observed that the quantity of the fresh dialysis liquid, or first liquid, drawn into respective chambers is equal to the quantity of the used dialysis liquid, or second liquid, delivered into respective chambers by the pumping system according to the present invention, and, on the other hand, that the flows of the dialysis liquid are continuous in the lines 18 and 19, that is to say, at outlet 42 and at inlet 44.
All the graphs illustrated in FIGS. 4 and 5 indicate time on the x axis subdivided into successive aspiration and delivery stages of the system, and the flow, expressed in units of flow 0, +1, -1, and 2 on the y axis. For example, one may choose a flow unit to be equal to 500 ml/min.
The graphs lines of FIG. 4 correspond to the variations of flow in the lines which deliver fresh dialysis liquid to hemodialyser 1, and the graph lines of FIG. 5 correspond to the variations of flow in the corresponding lines which expel the used dialysis liquid.
Graph line 1 of FIG. 4 represents flow through line 20 upstream of the junction with line 23 and shows that the supply of fresh dialysis liquid is effected at a constant flow rate. Regardless of whether the system is in the aspiration stage or in the delivery stage, there is always one unit of flow in line 20 upstream from the junction with line 23. This unit of flow is delivered alternately, in accordance with the direction pistons 9 and 11 are moved, to either first main chamber 12 or fourth auxiliary chamber 17, depending on whether valve 28 is open or closed.
The graph line 2 represents the circulation in line 20 downstream from the junction with line 23. It will be seen that when valve 28 is open, that is to say, in the aspiration stage with pistons 9, 10 and 11 moved in direction A, the flow rate of the dialysis liquid is two units, one unit coming from auxiliary chamber 17 via line 23, and one unit coming from the dialysis liquid source 60. In the delivery stage of the apparatus, that is, movement of pistons 9, 10 and 11 in direction R, the flow in line 20 is zero since valve 28 is closed.
On the other hand, in graph line 3, it is seen that in line 18 upstream of the junction with line 24, the flow rate is zero in the aspiration stage since valve 26 is closed, and is equal to two units in the delivery stage with valve 26 open. The two units of flow in line 18 during the delivery stage are supplied from main chamber 12 as piston 9 moves in direction R. One unit of flow is delivered to auxiliary chamber 15 through line 24, and one unit is delivered through first discharge line outlet 42.
The graph line 4 represents the flow rate in line 24. In the aspiration stage, the flow rate is a positive one unit, that is to say, the dialysis liquid flows from chamber 15 towards line 18 since valve 26 is closed, while in the delivery stage, the flow rate is a negative one unit in line 24, the negative signifying that the liquid then flows from first main chamber 12 through lines 18 and 24 into auxiliary chamber 15 with valve 26 open.
The graph line 5 represents the flow rate of the dialysis liquid that passes through first discharge line outlet 42. It may be considered as the sum of the flow rates of the graph lines 3 and 4. It will then be seen that the flow rate at outlet 42 is continuous and equal to the flow provided by the source of the fresh dialysis liquid. During movement of pistons 9, 10 and 11 in direction R, one unit of flow is delivered to first discharge line outlet 42 from first main chamber 12, and during movement of the pistons in direction A, one unit of flow is delivered to outlet 42 from second auxiliary chamber 15.
Referring to the graph line 6 of FIG. 5, it will be seen that the flow rate of the used dialysis liquid through inlet 44 of second intake line 19 from the hemodialyser, upstream from the junction of line 25 is continuous and equal to one unit. This flow may be considered to be the sum of the flows of the graph line 7 and of graph line 8 described below.
The graph line 7 represents the flow rate of the dialysis liquid in line 25. In the aspiration stage, that is, movement of the pistons in direction A, the flow rate is a positive one unit, that is the liquid flows from inlet 44 through line 19 towards auxiliary chamber 16 since valve 27 is closed, while in the delivery stage the flow rate is a negative one unit, that is, the liquid flows from auxiliary chamber 16 into main chamber 13 since valve 27 is open.
The graph line 8 represents the flow rate in line 19 downstream from the junction with line 25. In the aspiration stage, that is to say when the valve 27 is closed and the pistons are moved in direction A, the flow rate is zero; and in the delivery stage, that is to say when the valve 27 is open and the pistons are moved in direction R, the flow rate is equal to two units, one unit coming from auxiliary chamber 16 via line 25 and one unit coming from hemodialyser 1 through line 19.
The graph line 9 represents the flow rate in line 21 upstream from the junction with line 22. In the aspiration stage, that is to say when the valve 29 is open, the flow rate is equal to two units delivered from first main chamber 13 as piston 9 moves in direction A. In the delivery stage, that is to say when the valve 29 is closed, the flow rate is zero.
The graph line 10 represents the flow rate in line 21 downstream from the junction with the line 22, this is, the flow of the used dialysis liquid directed to the evacuation or regeneration means 62. The flow rate in line 21 downstream of the junction with line 22 is continuous and equal to 1 unit. During movement of pistons 9, 10 and 11 in direction A with valve 29 open, one unit is delivered from main chamber 13, and during movement of the pistons in direction R with valve 29 closed, one unit is delivered from first auxiliary chamber 14.
A comparison of the graph lines 1 and 10 shows that the quantity of liquid entering the system through line 20 is equal to the quantity of liquid emerging from the system through line 21. Furthermore, the graph lines 5 and 6, representing the circulation of the dialysis liquid in lines 18 and 19, respectively, demonstrate that the dialysis liquid passes through hemodialyser 1 in a continuous flow.
The quantity of the dialysis liquid drawn in and delivered during each successive aspiration and delivery stage depends on the amplitude or stroke of piston 9. The total quantity of the dialysis liquid passing through the circuit during the treatment session as a whole, depends on the value of the flow rate and hence on the frequency of the aspiration and delivery stages, that is to say, on the speed at which the rod 30 is driven.
With continued reference to FIG. 3, an ultrafiltration pump 31 may be provided to draw off a quantity of dialysis liquid which is equal to the quantity of liquid which one wishes to eliminate from the patient's blood by ultrafiltration.
In fact, in the case where the dialysis liquid circuit is a non-deformable, closed circuit, any quantity of liquid withdrawn from the dialysis liquid circuit produces a low pressure in the circuit which creates a pressure gradient at the level of the hemodialyser on either side of membrane 2. This pressure gradient causes a quantity of ultrafiltrate from the patient's blood to pass across semi-permeable membrane 2 of hemodialyser 1. This quantity of ultrafiltrate is equal to the quantity of liquid withdrawn from the dialysis liquid circuit.
The dialysis liquid can be withdrawn from line 19, upstream from the junction with line 25, as represented in FIG. 3, but may also be withdrawn from line 18 downstream from the junction with line 24.
Although not represented in the drawings, provision may moreover be made in the dialysis liquid circuit for degassing devices, pressure transducers or flow detectors or any other accessory which is non-critical as far as the present invention is concerned.
According to a second preferred embodiment of the invention illustrated in FIG. 6, auxiliary pumps 7 and 8 are no longer disposed coaxially with main cylinder 6. The pistons are not driven by means of a single rod, but, for instance, by means of three rods 30a, 30b, 30c linked to a rod 30 which is driven in a rectilinear reciprocating motion by any known means familiar to one skilled in the art such as an electromagnetic motor.
In the case where, as illustrated in FIG. 6, the pumps 6, 7 and 8 are comprised of cylinders having a circular cross section, pistons 10 and 11 are preferably configured with a cross section having a surface area equal to half the surface area of the cross section of piston 9. Thus, when pistons 10 and 11 are driven with the same motion and the same amplitude as piston 9, the quantity of the liquid displaced in each of main chambers 12 and 13 is twice the quantity of liquid displaced simultaneously in each one of auxiliary chambers 14, 15, 16 and 17.
FIG. 6 illustrates, moreover, that the functions of the auxiliary chambers 15 and 17 may be reversed. In effect, according to this embodiment of the invention, chamber 15, complementary to chamber 14, is connected by a line 23 to aspiration line 20 for the first liquid. Auxiliary chamber 17, complementary to the auxiliary chamber 16, is connected by a line 24 to the delivery line 18 for the first liquid. In the same manner, it is possible to reverse the functions of the chambers 14 and 16 with respect to aspiration and delivery stages of each as compared to the embodiment of the invention illustrated in FIG. 3.
The circuit diagram of FIG. 7 illustrates another relative arrangement of auxiliary chambers 14, 15, 16 and 17. In this case, auxiliary pistons 10 and 11 are displaced at the same time and with the same amplitude as piston 9, but in opposite directions. Thus, when main piston 9 is displaced in the direction of arrow A, auxiliary pistons 10 and 11 are displaced in the direction of arrow R and vice versa. This relative motion may be obtained, for instance, by means of mechanisms using crank connecting rod systems.
In the embodiment of FIG. 7, auxiliary chamber 14 is connected by a line 22 to delivery line 21, downstream from valve 29. Auxiliary chamber 15, which is complementary to auxiliary chamber 14, is connected by a line 23 to aspiration line 20 upstream from valve 28. Auxiliary chamber 16 is connected by a line 25 to aspiration line 19, upstream from valve 27, and auxiliary chamber 17, which is complementary with auxiliary chamber 16, is connected by a line 24 to delivery line 18. The operation of the device according to this mode of embodiment is as follows.
In the aspiration stage, valves 26 and 27 are closed and valves 28 and 29 are open. Main piston 9 is displaced in the direction of arrow A and auxiliary pistons 10 and 11 are displaced in the direction of arrow R.
The increase in volume of main chamber 12 entails aspiration of the first liquid into chamber 12, one-half of the first liquid entering chamber 12 coming from aspiration line 20, and one-half from chamber 15 via line 23. The simultaneous decrease in volume of main chamber 13 entails the delivery of an equal volume of the second liquid from chamber 13, one-half into chamber 14 via line 22 and one-half into the evacuation or regeneration means via line 21. Simultaneously, movement of the piston 11 in direction R delivers the first liquid from auxiliary chamber 17 into delivery line 18 via line 24 and draws the second liquid coming from the aspiration line 19 into auxiliary chamber 16 via line 25.
In the delivery stage, valves 26 and 27 are open and valves 28 and 29 are closed. Piston 9 is displaced in the direction of arrow R and pistons 10 and 11 are displaced in the direction of arrow A.
The first liquid which is expelled from main chamber 12 by piston 9 moving in direction R is delivered into auxiliary chamber 17 via line 24, and into delivery line 18. The increase in volume of main chamber 13 entails the aspiration of the second liquid into chamber 13, one-half of the volume of liquid entering chamber 13 coming from auxiliary chamber 16 via line 25, and one-half from aspiration line 19. Simultaneously, movement of the piston 10 in direction A entails delivery of the second liquid from auxiliary chamber 14 towards the delivery line 21 via line 22, as well as aspiration of the first liquid into the chamber 15 from aspiration line 20 via line 23.
The embodiment of the present invention illustrated in FIG. 7 makes it possible to pump equal quantities of a first and a second liquid while maintaining a continuous flow in aspiration lines 19 and 20, and in delivery lines 18 and 21.
Many variations of the embodiments described and illustrated are within the grasp of one skilled in the art without thereby departing from the scope of the present invention. Thus the drive means of the pistons may be mechanical drive, but may also be a magnetic, electromagnetic or hydraulic drive.
With reference to FIG. 3, in the case of a hydraulic drive, that is to say, by means of pumps for example, one pump may be disposed in aspiration line 20 for the first liquid upstream from the junction with line 23, and one pump may be disposed in aspiration line 19 for the second liquid upstream from the junction with line 25. In this arrangement pumping device 6 no longer performs a motor function for the pumping. It is also possible, while remaining within the scope of the present invention, to replace the pistons by leakproof membranes or diaphragms.
Valves 26, 27, 28 and 29 are preferably control valves, such as electrovalves. However, these valves need not be control valves but may be replaced by any type of conventional obturating device, such as one-way valves. However, when using one-way or check valves in combination with hydraulic drives, there would be the risk of the first liquid continuously passing from aspiration line 20 towards delivery line 18, and the further risk of the second liquid passing from aspiration line 19 towards delivery line 21. The set of four valves 26, 27, 28 and 29 may also be replaced by any equivalent means such as a distributor allowing a selection of the lines of passage for the dialysis liquid.
In the modes of embodiment represented in FIGS. 3, 6 and 7, a cylindrical shape with a circular cross section was adopted for the cylinder of pumps 6, 7 and 8, with the area of the cross section of main cylinder 40 being twice the area of the cross section of each of the auxiliary cylinders. It is, however, possible to choose a non-circular cross section for the auxiliary cylinders, and accordingly modify the amplitude of the movement of the auxiliary pistons so that the quantity of the liquid simultaneously displaced in each of the corresponding auxiliary chambers with displacement of auxiliary pistons 10 and 11 is one-half the quantity of liquid displaced in each main chamber by main piston 9.
It is also possible that one or more of the cylinders of pumps 6, 7 and 8 be divided into two complementary chambers by means of an equalizer system designed in such a way that the two associated chambers should be complementary to each other.
Among the possible applications of the method and of the apparatus according to the present invention, there has been described the pumping of equal quantities of a fresh dialysis liquid and of a used dialysis liquid, as illustrated with reference to FIG. 3.
However, the objects of the present invention may also be attained within the framework of haemofiltration with reinjection. In fact, in that technique, the quantity of the liquid withdrawn from the blood by ultrafiltration is replaced, save for the adjustment of the patient's weight, by an equal quantity of a substitution liquid which is injected into the blood. The first liquid pumped is then the ultrafiltrated liquid and the second liquid is the substitution liquid.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative devices, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. | 4y
|
BACKGROUND OF THE INVENTION
The availability of rechargeable batteries has led to a variety of rechargeable battery-operated "cordless" devices including grass shears, hedge trimmers, toothbrushes, shrub trimmers, lawn mowers, flashlights, sprayers, screwdrivers, and the like. In some cases the batteries are housed in a nonremovable pack. The recharging circuitry usually comprises a separare charging unit. In some cases the charging circuitry is incorporated as a part of a rechargeable battery pack. It has also been previously proposed to provide a removable battery pack having its own recharging circuitry, the pack having AC type prongs and arranged so that the pack can be interconnected through the prongs to the device to be powered or through the same prongs to a household receptacle for recharging. It has also been suggested to have a removable rechargeable battery pack that could be connected to any one of several battery power consuming devices. This concept has been proposed both for portable pocket size cordless apparatus as well as heavier portable cordless apparatus such as a cordless hedge trimmer but only for a fixed energy requirement.
A representative collection of prior art patents dealing with the foregoing constructions includes U.S. Pat. Nos. 1,506,302; Ser. No. 427,480, Zdansky (A.P.C.), published June 15, 1943; 2,628,339; 2,818,498; 2,876,410; 2,982,881; 2,995,695; 3,013,198; 3,021,468; 3,027,507; 3,067,373; Re. 25,388; 3,109,132; 3,120,632; 3,145,404; 3,183,538; 3,275,819; 3,280,351; 3,281,636; 3,329,881; 3,360,708; 3,447,058; 3,533,119; 3,623,223; 3,742,832; 3,757,194 and 3,883,789.
In a more recent development, a system now on the market is directed to a range of cordless devices including grass shears, lanterns, drills, and shrub trimmers. Each device mates with a standardized "power handle" which serves both as a handle and to contain a rechargeable battery. This handle is required to be removed and placed in a stand-type charger for recharging. Such a system points up the advantages of standardizing the power unit portion of a cordless device. However, this system makes no provision for the power handle to be used except singly. There is no provision for varying the amount of available battery power even though one device in the system might require more or less battery power than another. Also, the power handle in such a system does not, itself, contain recharging circuitry and the handle is not adapted to be plugged directly into a household receptacle for recharging.
Despite the extensive development of the art, there has not heretofore been provided a family of cordless portable tools or devices characterized in respect to each device in the family having one or a plurality of outwardly opening pockets adapted to receive a corresponding number of identical rechargeable battery packs according to the energy and power requirements of the individual devices and which packs can be recharged from a household receptacle through the same prongs used for discharge. Further, the prior art has not provided a relatively flat, rectangular-shaped battery pack that can be installed and removed from the particular device with the prongs arranged so as not to require guideways for sliding the pack and so as to minimize the hazard of dropping the pack.
With all of the foregoing considerations in mind, it thus becomes the object of this invention to provide a type of construction for mass production of a wide range family of portable cordless devices which for each device can be duplicated with respect to incorporating a standardized selected number of battery pack receiving pockets in the device and providing a standard type of rechargeable battery pack unit incorporating recharging circuitry and which can be used singly or in plural groups corresponding to the number of pockets in the particular device and which can be safely placed in an ordinary household receptacle for recharging purposes.
SUMMARY OF THE INVENTION
The present invention is directed to individual portable cordless devices of the type which use removable rechargeable battery packs as well as to a family of such devices which are adapted to use a selected number of such battery pack units. Each device in the family has a housing which has one or more pockets of unique construction adapted to receive one or more of the interchangeable battery pack units. Thus, the invention is directed, for example, to a portable cordless device whose power requirements are such that only one of the rechargeable battery pack units is required. The invention is also directed to that type of portable cordless device whose power requirements might require two or three or more of such battery packs. Thus, the invention provides a versatile construction suitable to a wide range of types of devices and which may vary widely in the nature of the electrical load and in such matters as torque, peak power demand and speed.
In accordance with the present invention, each power consuming device or tool is complete requiring only the installation of one or more battery packs to render it operative. For example, the grass shear of the invention includes a motor properly sized to provide optimum performance for its specific purpose, i.e., grass shearing, and has a housing and handle formation to provide a balance and convenience of operation equal to that afforded by prior conventional grass shears. Similarly, the hedge trimmer of the invention is provided with a larger motor and a different housing and handle formation particularly suited to hedge trimming.
The invention devices thus contrast with prior devices of the type utilizing a common power handle which, unlike the present invention, necessarily requires compromise in construction and operation in any tool or device which is in the family of tools or devices using such a handle.
With respect to the power consuming device or unit, the invention is directed to forming one or more outwardly opening pockets in the housing of such device, each pocket having its base plane defined in the preferred embodiment by a base plate member which is the same for all members in the family of devices and which plate member includes an electrical receptacle for receiving the electrical prongs or blades of the battery pack. The plate member also co-operates with the remaining pocket structure to facilitate insertion, retention and removal of the battery pack.
As to the battery pack unit of the invention, such battery pack is characterized by being in a rather rectangular flat box-like shape and having a pair of AC type prongs projecting from a position intermediate the length and width of one flat sidewall surface of the pack. These prongs are adapted to be received by a corresponding set of receptacle openings provided in the base plate member or, for recharging, to be received by an ordinary household receptacle supply. The weight of the battery, rectifier means and a switch incorporated in the battery pack, is distributed both longitudinally and laterally over the battery pack so as to minimize the moment exerted by the pack whether the household receptacle openings being utilized are oriented vertically or horizontally.
Each pack is mechanically latched to its respective pocket and does not depend on its prongs for such mechanical interlocking.
The switch in the battery pack unit comprises a double-pole, double-throw, spring-loaded switch which is incorporated as a part of an AC prong assembly which mounts both the AC prongs of the battery pack and the switch. This switch connects the rectifier means to the battery during recharging and is activated and spring-loaded when the pack is installed and latched in its pocket to connect the prongs to the battery for discharge without requiring manual switching. Also, the switch spring causes the pack to tilt, i.e., to pop out, when unlatched.
To facilitate insertion, retention and removal of the pack, the pocket in each device in the family of devices is provided with an outwardly opening receptacle formation at one end of the pocket so that the battery is inserted and removed by first assuming a tilted position. When the battery pack is unlatched, it pops out and initially assumes such an outwardly tilted position. It is then withdrawn from the pocket by linear motion. During insertion, one end of the battery pack is first inserted in the receptacle formation in a tilted position and is then rocked about the inserted end of the pack, the receptacle formation insuring insertion of the prongs of the pack into the mentioned housing base plate receptacle of the device after which it is latched.
In one form of the invention the housing of the device is provided with oppositely facing pack receiving pockets positioned back to back.
The electrical receptacle in the base plates are offset from the base plate centerlines to permit the receptacles to interfit when arranged back to back thus permitting a substantial reduction in the bulk and weight of the tool.
The contact blades or prongs of the pack are similarly offset. To assure uniformity of the packs and pockets the offset construction is also used where the tool requires only one battery pack.
The invention also includes the use of a pair of spring contacts in the prong receiving receptacle of the device which makes both electrical and mechanical contact with the edges of the prongs being inserted and which insure both positive electrical and mechanical contact with the prongs. The mentioned switch spring in conjunction with these spring contacts causes the pack, when unlatched, to pop out as described. A configuration of internal rib constructions are incorporated within the pack housing which secures the internal components against end as well as side-applied shock. The device housing and the pack lend themselves to use of clam shell type housings which greatly facilitates fabrication of the device and pack on a mass production basis.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a pictorial view of a cordless electric grass shear and battery pack of the present invention;
FIG. 2 is a pictorial view of a cordless electric lantern with a battery pack of the invention;
FIG. 3 is a pictorial view of a cordless electric screwdriver and battery pack;
FIG. 4 is a pictorial view of a cordless electric shurb trimmer with the battery pack of the present invention;
FIG. 5 is a pictorial view of a garden sprayer incorporating dual pockets with two battery packs in a vertical orientation;
FIG. 6 is a side view of a heavy-duty shrub trimmer adapted to receive three battery packs in a balanced arrangement;
FIG. 7 is a perspective view illustrating the battery pack showing the AC prongs and latch feature;
FIG. 8 is an inverted perspective view of the battery pack and showing the latch feature;
FIG. 9 is an exploded, fragmentary view of the battery pack with a portion of the pack cutaway to show the inner components;
FIG. 10 is a vertical central section of the pack showing the latch in its normal position and with the wiring removed for purposes of illustration;
FIG. 11 is an enlarged fragmentary section of the latch showing the latch in its depressed position;
FIG. 12 is a section through the battery pocket;
FIG. 13 is a vertical section of the pocket, along line 13--13 of FIG. 12;
FIG. 14 is an end section view of the pocket, along line 14--14 of FIG. 13;
FIG. 15 is a schematic diagram of the electrical circuitry of a typical multiple pack tool or device;
FIG. 16 is a view of the inner surface of the pocket base plate or liner and shows the slot openings for receiving the AC prongs of the pack;
FIG. 17 is a side view of the pocket base plate or liner illustrated in FIG. 16;
FIG. 18 is a view of the outer surface of the liner;
FIG. 19 is an enlarged, fragmentary view of the spring contact member as it is initially engaged by the AC prong edges of the battery pack during insertion of the pack;
FIG. 20 is a view similar to FIG. 19 showing the prongs fully inserted;
FIG. 21 is a vertical section of the pocket similar to FIG. 13 with the liner installed;
FIG. 22 is a side view of a grass shear of the present invention with a portion of the shear housing broken away to illustrate the pocket and liner and a battery pack in the partially removed position;
FIG. 23 is a view similar to FIG. 22 with the battery pack inserted;
FIG. 24 is a side section view of a portion of the housing for a battery-operated device with dual pockets to hold two battery packs in a horizontal orientation;
FIG. 25 is a section view of the dual pockets of FIG. 24 taken substantially along line 24--25 of FIG. 24; and
FIG. 26 is a schematic circuit diagram of the charging and discharging circuitry of the battery pack.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIGS. 1-6 illustrate a system of six cordless, portable devices and tools which utilize one or more of the same interchangeable, rechargeable battery packs 10 as the source of power. Each tool or device is shown with one or more pack receiving pockets which receive the pack or packs and provides electrical connections to the tool or device. FIG. 1 depicts a lightweight grass shear 11 adapted to cut relatively narrow swaths of grass; FIG. 2 shows a lantern 12; FIG. 3, a screwdriver 13; and FIG. 4, a lightweight shrub trimmer 14. The versatility of the system is further illustrated with reference to tools and devices having heavier load requirements, as later explained, and as seen in FIG. 5 and FIG. 6 showing a cordless sprayer 133 having two packs 10 and a heavy duty hedge trimmer 135 having three packs 10 and each with a corresponding number of the standardized pockets. Each tool or device provides a handle formation.
Referring to FIGS. 7 and 8, battery pack 10, in the embodiment illustrated, has a generally rectangular, flat boxlike shape, i.e., a rectangular parallelepiped shape, and has rectangular, generally flat, side wall surfaces 16 and 17. Pack sides 21, 22, 23, 24, formed by side components 21a, 21b, 22a, 22b, 23a, 23b, 24a and 24b, provide a groove 25 which encircles the pack. Pack 10 of the present embodiment has its own latch as will be described. However, if the latch is made a part of the tool or device housing groove 25 can be used to receive the latch and retain the pack.
A pair of standard rigidly mounted AC blades or prongs 26, 27 extend from surface 16 and are oriented parallel to the central long axis of pack 10 with the prongs being located at a position intermediate the length and width of the wall surface 16. The blades are on opposite sides of, and offset different distances from, the longitudinal centerline of the pack for a purpose to appear.
Located between prongs 26, 27 is a switch actuator 28 which is engaged by a post member 113 in tool pocket 91 to switch the pack circuitry from the charging to the discharging mode when pack 10 is installed in a manner to be described later. Side surface 21 is provided with a resilient latch member 20 which is adapted to engage a ledge portion of the tool pocket in order to hold the pack in place.
FIG. 9 shows the outer pack body member 40 separated from pack body member 60 to show the internal components of the battery pack 10. Members 40 and 60 are essentially a pair of secured rectangular pan-shaped clam shell members. The internal components illustrated in FIGS. 9, 10 and 26 include rechargeable nickel-cadmium sub-c batteries 31, 32, 33, capacitor 35, printed circuit board 36, switch 37, diode bridge 154 and resistors 157, 158. Such circuitry minimizes weight and heat.
Members 40 and 60 are approximately 2 inches by 41/2 inches by 1/2 inch, have a wall thickness of about 1/8 inch and are preferably molded of an impact resistant, flame retardant polycarbonate. The interior wall surfaces of member 40 are provided with upper circuit board locators 57, 58 into which circuit board 36 slides into place during assembly. The interior of the top wall also includes two spike members 48, 49 which are positioned over switch 37 as shown in FIG. 10 to hold the switch in a rattle-proof, shock proof manner. A recessed area is provided in the front wall surface 21a of member 40 to accommodate latch 20. The recessed area and associated structural members will be described in conjunction with the description of latch 20.
Body member 60 is provided with battery locating ribs that aid in locating the batteries during assembly and also serve to keep the batteries in position during use and thereby reduce rattling. The interior of member 60 is also provided with lower circuit board locators 77, 78 which are aligned with upper circuit board locators 57, 58 and serve as a means of locating the circuit board during assembly and keeping the circuit board in position during use. A pair of live ribs 80, 81 span the width of member 60 and provide compartments for batteries 31, 32, 33. Live ribs 80, 81 are designed to be resilient and absorb shock from the batteries when the pack is accidentally dropped on either end. Structural ribs 82, 83 also serve to define compartments for batteries 31, 32, 33. The structural ribs 82, 83 are rigid and are designed to lend strength to the overall construction of the pack. The body members are snap fitted together and are then ultrasonically welded together.
Member 60 is provided with two slots through which AC prongs 26, 27 protrude. An aperture 90 is aligned over switch actuator 28 to expose the latter to a switch activating post 113 in the tool pocket as described later. The prong slots and aperture 90 are located off the centerline of member 60 to facilitate the construction of a dual pack as illustrated in FIGS. 5 and 6 and described later.
Member 60 also has a recess 59 for accommodating latch 20 which will now be described. Latch 20 in one embodiment was molded from an acetal resilient plastic material. Latch 20 provides a front notched surface 164 and a smooth front surface 171. Intermediate the length of the front surface is a latch groove 167 which is positioned so as to align with power pack groove 25 when latch 20 is in its normally non-depressed position in pack 10. Latch 20 also provides latch alignment members 160 and restraining knobs 163.
As best shown in FIG. 11, during assembly of pack 10, latch 20 slides into place with alignment members 160 against structural rib 83 on member 60 of pack 10.
After latch 20 is positioned in member 60, member 40 is snap-fitted and ultrasonically welded to member 60 so that the upper portion of latch 20 resides within recess 50 of member 40. When latch 20 is in its normally non-depressed position, front surfaces 164 and 171 essentially form a continuation of pack side member 21 as best shown in FIGS. 7 and 8.
The installed latch is adapted to hold pack 10 in place within pocket 91 by engagement of latch groove 167 and pocket lip 125 which is co-extensive with the latch. When pack 10 is pivoted or hinged into place in the manner previously described, pocket lip 125 initially engages smooth front surface 171 and causes resilient latch 20 to bend at point P (FIG. 11) to the depressed position shown in FIG. 11. Upon full insertion of pack 10 into pocket 91, lip 125 will fall into groove 167 thereby allowing latch 20 to return to its non-depressed position (FIG. 7). Knobs 163 on latch 20 are adapted to engage cavity wall surfaces 182 in member 40 when the latch is in its non-depressed position thereby preventing the latch from being pulled outwardly from the pack 10 beyond its normal position.
The battery pack unit 10 just described is adapted to fit into any one of the pockets, in any of the tools and devices which are part of the family of devices made according to the invention. What is next to be described is the pocket construction which can be employed singly or plurally in the devices and tools made according to the invention, so that any pocket can accept any pack which allows any pack to be used with any tool or device in the family in single and plural groups as required.
The receiving pocket 91 for the standardized pack 10 is depicted in FIGS. 12-14 and 21-23. In the embodiment being used for illustration, the standardized pocket 91 is formed as an integral part of the tool clam shell housing 93. Pocket 91 can be formed in the housing of each tool or device at a point where the battery pack 10 can be easily inserted into the pocket and provide overall tool balance. Pocket 91 is also adapted to provide means for locating and holding in place a standardized pocket liner 100 which is illustrated in FIGS. 16-18. In order to receive liner 100, each housing for the particular tool or device includes a plurality of liner locators 95 which extend from the housing interior wall surfaces of pocket 91 and are adapted to engage locator grooves 101 in liner 100. A front housing wall member 92 of pocket 91 is provided with a recess 99 which is adapted to receive a projection 105 on liner 100 as a further means for locating and holding in place liner 100. Pocket 91 is devoid of guideways and the like which enables the pack to be tiltably inserted and removed and to pop out when unlatched as elsewhere discussed.
It should be emphasized here that so far as is known, there has not been available in the marketplace a coordinated family of cordless, portable tools and devices having varying power requirements and in which each tool or device in the family has a housing which both forms a handle and mounts battery power consuming apparatus and in which such housing is adapted with one or more standardized outwardly opening pockets to accept a comparable number of identical battery packs with each pack having a battery recharging circuitry, AC type prongs and switching mechanism enabling the pack to be recharged from a household receptacle or to be used to power the device or tool.
A part of the present invention resides in providing a variety of portable cordless devices each of which can be powered by one or more removable rechargeable identical battery packs. In what is believed to be a departure from prior art practices, the battery receiving pocket in each housing includes the same base plate or liner member which provides a means for standardizing the location of the base and side peripheral planes of the pocket and for standardizing the positioning and securement of the AC prong receptacle openings in the tool and device. Thus a standardized outwardly opening pocket is achieved which can be used over a wide range of portable cordless tools and devices, e.g., grass shears, lanterns, sprayers, hedge trimmers, and the like.
Referring particularly to FIGS. 16-20, the pocket liner 100, which is a common component of each tool or device and serves as a base wall in pocket 91, includes a flat outer surface 107, an inwardly inclined surface 108, a lip portion 109, and an extension 105. Flat surface 107 is adapted to engage the flat inner wall surface of battery pack 10 when pack 10 is inserted into the pocket. Surfaces 108, 109 are adapted to facilitate the pivotal insertion and removal of pack 10 as later described. Surface 107 provides two prong receiving chamfered slots 111, 112.
As later explained, the circuitry provides for the internal battery pack to be normally connected to the AC prongs for recharging. However, the battery pack and device housing pocket are also provided with means to switch the internal battery pack circuitry to connect the AC prongs to the battery for discharge and use as a power source whenever the pack is inserted in the pocket. In this regard, it may be noted that switch activation post 113 is located between slots 111 and 112. When pack 10 is fully inserted into pocket 91, post 113 engages switch actuator 28 so as to switch the circuitry of pack 10 into the discharging mode. Contact spring holders 121, 122 provide in a central portion thereof post members 123, 124 which are each adapted to receive a contact spring 115 as best shown in FIGS. 19 and 20. Contact spring 115 is a curved leaf spring of resilient conductive metal having a loop locator portion 110, a retainer member 116, a U-shaped prong engagement portion 126, and a wire lead solder contact 114. Loop 110 is adapted to be press-fitted over one of post member 123, 124. When loop 110 is pressed into place, resilient retainer member 116 locates on post member 123 or 124 in order to hold contact spring 115 in place. Prong engagement portion 126 is normally in the external position shown in FIG. 19. As pack 10 is pivoted into pocket 91, one of prongs 26, 27 contacts spring 115 and bends it until pack 10 is fully inserted (FIG. 20). Spring 115 is thus adapted to provide exceptionally reliable electrical contact with the leading edges of AC prongs 26, 27. Wire lead solder contact 114 of contact spring 115 is adapted to electrically connect spring 115 to the appropriate wire leads of the tool motor or other device apparatus. Screw bosses 119, 120 serve as means to secure together two liners in the dual pocket version which will be described later with reference to FIGS. 24 and 25.
The method of insertion and removal of pack 10 into pocket 91 is best illustrated in FIGS. 22 and 23 with respect to a typical grass shear 11 adapted with a single pocket 91 and battery pack 10 according to the invention. The shear 11 is held by one hand with the pocket 91 facing downwardly. With the other hand, the operator picks up pack 10 with prongs 26, 27 facing upwardly. The end 23 of the pack 10 opposite latch 20 is then inserted into pocket 91 with surface 17 of pack 10 resting on pocket ledge 94 and with pack surface 16 residing proximate incline surface 108. Pack 10 is now rocked about ledge 94 until the side surface 16 of pack 10 lies flush against flat surface 107 of liner 100 (FIG. 23). During this rocking movement, prongs 26, 27 enter chamfered slots 111, 112 until prongs 26, 27 engage and bend contact springs 115. Also, during this rocking motion, spring activation post 113 engages switch actuator 28. When pack 10 is fully inserted, pocket lip 125 engages latch groove 167 in order to hold pack 10 in place without requiring guideways or the like. Thus the front receptacle portion of the pocket formed by the portions 108 and 109 of the liner, housing wall 92 and ledge 94 locates the pack for insertion, supports the pack during the rocking movement and holds the forward end of the pack securely in place.
It should be noted that the internal spring for switch 37 (FIG. 10) and contact springs 115 (FIG. 19) are both compressed by latching of pack 10. Thus pack 10 tends to tilt and pop out when unlatched. The removal of pack 10 from pocket 91 becomes a two-step operation which provides a degree of protection against accidental unlatching or dropping of pack 10. First, latch 20 is depressed so that latch groove 167 disengages pocket lip 125 and by the mentioned spring action and possible force of gravity, dependent on how the tool or device is positioned, pack 10 moves to and is held in a partially removed position as illustrated by FIG. 22. Thus, if latch 20 is accidentally depressed, pack 10 can move to the partially removed position and remain there until reinserted or removed.
FIGS. 5, 24, and 25 illustrate use of dual packs and pockets for tools or devices having high energy demands. The two-pack pocket 130 is adapted to receive two of the battery packs 10 with the packs' inner surfaces and AC prongs facing each other. Since the AC prongs on each battery pack 10 are offset from the longitudinal centerline of the pack, the opposing prongs of the two battery packs when inserted into pocket 130 interfit permitting a much more compact arrangement than would otherwise be possible and substantially reducing the bulk and weight of the tool.
The assembly of pocket 130 is facilitated by the mating of male bosses 119, 119' with female bosses 120, 120'. Screws 128, 129 are inserted into countersunk holes 127 (FIG. 18) which are located at the base of female bosses 120, 120'. Screws 128, 129 secure the bosses and, in conjunction with extensions 105, 105', serve to hold together liners 100, 100' in a parallel spaced relation. An important feature of pocket 130 is the interfitting of contact spring holders 121, 122, 121', 122'. As best shown in FIG. 16, contact spring holders 121, 122 are located offset from the centerline of liner 100 so that when liners 100, 100' are interconnected by their respective bosses 119, 120, 119', 120' in the assembly of a two pack pocket 130, the contact spring holders 121, 122, 121', 122' interfit so that the liners 100, 100' can be closely nested together to form pocket 130.
The two-pack pocket 130 accommodates tools or devices with higher energy demands than the single pack tools illustrated in FIGS. 1-4. A representative tool requiring a two pack pocket 130 is the heavy duty garden sprayer 133 illustrated in FIG. 5 and adapted to receive two oppositely disposed vertically end oriented packs 10.
A heavy duty hedge trimmer 135 requiring even more energy is illustrated in FIG. 6. Trimmer 135 is adapted to receive three packs 10 with one pack generally horizontal and fitting in a bottom pocket as in the tools of FIGS. 1-4 and two packs generally vertically side oriented fitting in opposite side pockets generally as shown in FIG. 24. Tool balance is achieved in all of the embodiments.
The electrical circuitry of a typical multiple pack tool or device illustrated in FIG. 15 and the pack circuitry is illustrated in FIG. 26. In FIG. 15, power consuming device 153 is illustrated as being a heavy duty device adapted to hold up to three battery packs 10 which are connected through manually operable switch 150 to the load unit of device 153 by the electrical contacts 115. Packs 10 are connected in parallel so that only one switch 150 needs to be located on device 153. Although a multiple pack tool or device will normally be operated with a battery pack 10 in each pack pocket, the parallel circuitry enables the operator to run the multiple pack tool or device with one or more of the pockets empty, though series circuitry can be employed.
In all the embodiments illustrated, it is recognized that in the typical tool or device the operator trigger or other type on-off switch 150 is suitably placed for operator control as shown in FIGS. 1-6.
The charging and discharging circuitry of pack 10 will now be described with reference to the schematic circuit diagram 140 of FIG. 26. A double-pole, double-throw switch 37 is adapted to place the circuitry in either a charging or discharging mode. Switch 37 includes six terminals 141, 142, 143, 144, 145, 146. AC terminals 141, 142 are connected to the charging circuitry. DC terminals 145, 146 are connected to the discharge circuitry. Common terminals 143, 144 are connected directly to the AC prongs 26, 27 and are, in the preferred embodiment, continuations of the prongs themselves. Movable contacts 151, 152 are spring loaded in such a manner that they normally connect AC terminal 141 to terminal 143 and AC terminal 142 to terminal 144 as depicted in FIG. 26. The charging circuitry comprises (1) a capacitor 35 which is adapted to drop the input voltage; (2) a diode bridge full wave rectifier 154; (3) batteries 31, 32, 33 connected in series; (4) a bleed resistor 157 which is selected to quickly bleed by completing a RC circuit with a short time constant; and (5) a surge resistor 158 which prevents the diode bridge 154 from receiving a large surge when capacitor 35 is completely discharged. The discharge circuitry is, of course, a direct connection between AC prongs 26, 27 (terminals 143, 144) and batteries 31, 32, 33.
The described pack circuitry has several practical advantages in that such full wave rectification circuitry minimizes both weight and internal heat. Pack 10 can essentially be encapsulated, though aperture 90 is preferably designed to provide sufficient clearance, both for member 28 and to vent pack 10 in the event of extraneous battery gases. In contrast, recharging circuitry of other types, e.g., half-wave rectification, would both increase weight and temperature and require positive venting.
As described previously, when battery pack 10 is assembled, switch actuator 28 is disposed between prongs 26, 27 in aperture 90.
When pack 10 is fully inserted into a standard tool pocket 91, switch activation post 113 is positioned so as to align with aperture 90 and depress switch actuator 28. The depression of actuator 28 compresses the return spring in switch 37 and places pack 10 in a discharge mode. At all times when pack 10 is not fully inserted into a pocket 91, pack 10 will be in the charging mode. This safety feature aids in preventing accidental discharge of pack 10 as well as preventing accidental shortage.
Pack 10 is plugged into a standard AC receptacle during charging, as previously explained, and uniquely complies with all known requirements relating to maximum weight for unsupported devices plugged into AC wall receptacles and maximum moment arms which can be exerted on the prongs when they are plugged into the receptacle. In the preferred embodiment, pack 10, including all of its components, weighs approximately 7.82 ounces. When pack 10 is plugged into a standard vertically aligned AC receptacle, the moment produced is approximately 4.4 inch ounces. When pack 10 is plugged into a horizontally aligned AC receptacle, the moment is approximately 4.9 inch ounces. In the embodiment shown, pack 10 has a width of about 2 inches, a length of about 41/2 inches, and a thickness of about 1 inch. Of particular significance is the fact that the pack is easy to grasp and handle and the particular arrangement of components allows the pack to be safely inserted in a standard receptacle whether the receptacle openings are vertically oriented or horizontally oriented. Thus, it can be seen that pack 10 provides a very useful configuration for multiple use, interchangeability and as a self-contained battery charger and still meets requirements for unsupported household receptacle rechargeable devices.
While recharging of the pack from a household receptacle is contemplated in the preferred embodiment, it is also contemplated, while not being shown, that the pack can be recharged in a suitable recharging stand. For example, such a stand may contain a suitable horizontal receptacle to receive and connect the pack prongs for recharging as well as actuate the switch 37 with the stand receptacle being connected to a separate AC supply. Also, such a stand may contain suitable circuitry for reducing the available AC voltage as, for example, in overseas use where higher receptacle voltages are experienced. Additionally, such a stand could employ supplemental fast charging circuitry to reduce the time required for recharging.
From the foregoing, it can be seen that the system of the invention thus provides both a unique battery pack as well as a unique battery pack pocket construction suited to economical mass production and which lend themselves to interchangeability of any pack with any pocket, multiple use of any pack with any tool or device, grouping of packs in plural groups for increasing available power, providing for any pack to be recharged simply by plugging into a typical 110-120 volt AC household receptacle and maintaining tool balance.
In summary, the invention now provides a unique system especially suited to portable cordless tools for which widespread application is envisioned. While single, two and three pack applications have been illustrated, it is, of course, apparent that a greater number of packs could be employed and that the specific pack and pocket constructions could be otherwise standardized without departing from the invention as hereafter claimed. Also, with other methods of recharging, it is apparent that the pack itself could be both larger and heavier while retaining many advantages of the invention. While the use of a separate standardized pocket liner or base member secured between clam shell housing halves is a preferred construction, it is also envisioned that a standardized pocket base plane could be established by molding the pocket base plate as part of the tool or device housing. | 4y
|
The invention relates to a power plant, and more particularly to an IGCC (integrated gasification combined cycle) power plant, and to a method for operating the same.
BACKGROUND OF THE INVENTION
The abbreviation IGCC stands for integrated gasification combined cycle. IGCC power plants are gas and steam turbine power plants (combined cycle (CC) power plants), having a stage for coal gasification connected upstream thereof. During coal gasification, a combustible gas containing carbon monoxide and hydrogen is produced from coal in a gasifier substoichiometrically (λ between approximately 0.2 and 0.4). Meanwhile, it is also possible, as an alternative, to use oil, refinery waste, biomass or waste. The product gas is cleaned and supplied to the gas and steam turbine process. This method allows for a gasifier efficiency of 0.6 and, when utilizing the residual heat, an efficiency of 0.8.
The IGCC process allows the technically simple carbon dioxide separation to be performed prior to the actual combustion process, because physically favorable conditions for separation are present in the form of a high overall pressure, and high concentrations of the gas components CO 2 and H 2 that are to be separated. In two additional steps, the carbon monoxide developed during the gasification can first be converted into carbon dioxide in a shift stage using steam, and then easily separated given the high pressure, and supplied to final waste disposal. This is a considerable advantage as compared to techniques in which the carbon dioxide must be removed from the flue gas. With atmospheric combustion, the flue gas contains more than 80 percent nitrogen, which is very difficult to remove. The IGCC technology can therefore make a significant contribution to lowering carbon dioxide emissions, and thus to reducing the greenhouse effect caused by humans.
A further advantage of the IGCC is the use of a gas turbine comprising a generator that generates electric power from the combustion of the gas, and the combined use of the waste heat of this gas turbine in a downstream steam turbine. Today, system efficiencies of 50 to 55 percent are possible, which clearly exceed the 40 to 45 percent of a regular coal power plant.
Heretofore, power plants of this design (see FIG. 1 or 2 ) have been operated in a manner wherein the gas produced during the gasification process (coal gas) is supplied directly as fuel gas to the CC process, after the necessary gas cleaning step. A combined cycle power plant (CCPP) is a power plant in which the principles of a gas turbine power plant and steam power plant are combined. A gas turbine is used as the heat source for a downstream waste heat recovery boiler, which in turn acts as a steam generator for the steam turbine. In this CC process, the coal gas is combusted in the combustion chamber of the gas turbine, and a portion of the energy inherent in the gas is converted into mechanical energy by expansion in a turbine process. The existing perceivable heat is utilized in a subsequent steam turbine process. The concentration of carbon dioxide, CO 2 , in the flue gas of this process is low. Typically, it is below 10% by volume. The CO 2 can be separated from the flue gas using the same method that is possible with today's ordinary steam power plants. It should be noted that the technical difficulty of separating the CO 2 increases as the concentration of CO 2 in the flue gas decreases. The technical difficulty of separating the CO 2 negatively impacts the efficiency of the method.
Separating the coal gas into fuel gas, which contains no, or only a small portion of, the carbon compounds CO (carbon monoxide) and CO 2 (carbon dioxide), and a gas flow, which exclusively or predominantly contains CO and CO 2 , is advantageous for the process of separating the CO 2 and conditioning the same for final waste disposal.
One possibility is to use a hydrogen membrane to bring about separation of the hydrogen from modified coal gas that is enriched with hydrogen by way of the shift reaction. This results in a residual gas that, depending on the process, may contain such a high proportion of CO 2 that it is possible to optionally liquefy the residual gas, and thereby prepare it for final waste disposal. This goal can be achieved, for example, using a membrane that is exclusively or predominantly permeable by hydrogen.
In one embodiment of this variant ( FIG. 3 ), the membrane is used without further flushing, which is to say that, because of the reduced pressure on the permeate side, the hydrogen diffuses by means of the natural driving force through the membrane. A considerable reduction in pressure is required to ensure that the driving force is also sufficient during the course of the separation process and to achieve a sufficiently high degree of separation of the hydrogen. The disadvantage is that the hydrogen produced in this way first has to be compressed from very low pressures to pressures of approximately 25 bar before it can be supplied to the combustion chamber. This H 2 recompression requires tremendous amounts of energy and is a key reason for the major efficiency losses in this process.
If a slightly higher pressure level is selected on the permeate side, so as to minimize the energy expenditure for the H 2 recompression, a considerable proportion of the hydrogen will disadvantageously remain in the retentate and not be supplied to the CC process. This hydrogen is either lost entirely for power generation, or can be used, after combustion, with oxygen, which is more complex to produce, only to produce power in a steam power process, the efficiency of which is lower than a CC process. During combustion with air, nitrogen would be introduced and the CO 2 -rich retentate would become disadvantageously polluted. Göttlicher [1] reports on earlier studies conducted on variants of such a concept.
A further modification of the IGCC process was likewise cited by Göttlicher [1]. Göttlicher also proposes the use of compressed nitrogen as a flushing gas as one possible way to improve the separation of hydrogen. To this end, the nitrogen is obtained from an air separation facility required for the gasification, as is done with the otherwise conventional IGCC process (see FIG. 4 ). The flushing mass flow of N 2 generally approximately corresponds to that of the hydrogen diffused through the membrane.
The flushing gas has thus changed at the outlet from the membrane and is now composed of about one half each of N 2 and H 2 . The H 2 partial pressure has risen to a value that is approximately half as high as the overall permeate pressure. The H 2 partial pressure on the feed side located directly opposite thereof, at the inlet of the feed into the membrane, is also approximately half the total pressure. This results in a driving force in the membrane that is substantially equal to zero, so that high separation degrees for H 2 can, at best, only be achieved with unreasonably large membrane surfaces.
DE 10 2008 011 771 describes a further IGCC power plant comprising H 2 membranes, wherein the first flushing gas source, in the form of an air separation facility, is supplemented by a further, stronger flushing gas source. So as to further improve the efficiency, the flue gas can be recirculated from the downstream steam turbine to the combustion chamber of the gas turbine (see FIG. 5 ). The flue gas recirculation, following stoichiometric air combustion, represents a second possible flushing gas source, which is distinguished by a low oxygen content. For this purpose, a portion of the gas turbine combustion chamber waste gas, which is already under high pressure, is conducted to the permeate side of the membrane. This effect is even better as the content of O 2 in the flue gas decreases, because oxygen may react directly with the H 2 permeate and would cause an unacceptably high increase in the temperature inside the H 2 membrane, for example of several hundred degrees. So as to keep the oxygen content of the waste gas/flue gas as low as possible, generally a substantially stoichiometric ratio of air and fuel (H 2 gas) is employed, which is reflected in the parameter λ˜1. In the standard IGCC, hyperstoichiometric air separation is carried out, and thus the large nitrogen-rich flue gas flow generally contains more than 10 mole percent oxygen, and thus is not suited as a flushing gas in this form.
The waste gas from the combustion chamber usually has temperatures above 1200° C., so that the flue gas first has to be cooled before being supplied to the H 2 membrane. The high-temperature recuperators required for this are generally expensive and/or are not available and may cause even further energy losses, for example when a final cooler is provided at the end of the hot side of the recuperator, which disadvantageously impacts the energy balance of the overall system.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved IGCC power plant, wherein a pressurized waste gas is produced, which comprises almost exclusively CO 2 and can therefore be liquefied with little additional energy expenditure. It is a further object of the invention to provide such an IGCC power plant having a simplified process, as compared to the known prior art, combined with an energetically improved supply of flushing gases. It is another object of the invention to provide a method for operating such an IGCC power plant, which has the aforementioned properties.
The objects of the invention are achieved by an IGCC power plant having all the characteristics according to the main claim and by a method for operating the same according to the additional independent claim. Advantageous embodiments of the power plant and of the method are disclosed in the claims relating to them, respectively.
The invention relates to an IGCC power plant comprising membranes for the purpose of separating gases utilizing flushing gases, and to a method for operating the same, which advantageously makes it possible to yield the flushing gases within the IGCC process.
The principle of the power plant according to the invention is based on the IGCC power plant comprising a membrane known from Göttlicher [1], however, the flushing gas for the membrane is not provided externally, for example by an air separation facility, but this flushing gas is advantageously primarily withdrawn directly from the process. Contrary to DE 10 2008 011 771, where the flue gas/waste gas of the gas turbine combustion chamber is used as the membrane flushing gas, and flue gas recirculation of the waste gas from the waste heat recovery boiler back into the gas turbine combustor is additionally provided for, in the present invention a portion of the waste gas of the gas turbine is advantageously used directly as a flushing gas for the H 2 membrane, after passing through the waste heat recovery boiler for the steam turbine, and is compressed even before the membrane to the necessary pressure for the subsequent combustion.
After the flushing gas has made the detour over the membrane and become enriched there with H 2 , it also fulfills the original function thereof in the burner, which is to say to deliberately cool the combustion process so that the desired turbine inlet temperature is reached. While this cooling originally took place by way of air, the O 2 component is now absent, which is compensated for by an accordingly higher amount of N 2 . A further difference from DE 10 2008 011 771, where the flushing gas quantity on the inside of the two gas cycle can be freely selected, is that in the present invention the flushing gas quantity is clearly defined by the overall conditions of the gas turbine process. However, it has been shown that the resulting typical flushing gas quantities are completely sufficient to be able to operate the membrane separation process very inexpensively. Contrary to DE 10 2008 011 771, where a complex high-temperature recuperator is required, in the present invention, the simple process (only one gas cycle) results in no, or only little, additional expenditure for converting the air burner cooling into burner cooling with recirculated O 2 -free N 2 waste gas, for the purpose of additionally sending this gas upstream of the burner (again without significant energy expenditure) as flushing gas through the permeate side of the H 2 membrane.
The method according to the invention described here is particularly advantageous as compared to the conventional IGCC methods because it yields waste gas that is almost exclusively composed of CO 2 , which is additionally produced under pressure. This waste gas can be liquefied with little additional energy expenditure, and the pressure required for final waste disposal can also be produced with little additional energy expenditure in light of the liquid CO 2 . In general, no step other than conditioning the waste gas for enrichment of the CO 2 is required, because all necessary steps are integral components of the method.
Compared to the existing known method proposed by Göttlicher (FIG. 4 in [1]), this has the advantage that the flushing gas for separating the hydrogen does not need to be entirely externally supplied to a membrane, for example from an air separation facility, but is produced predominantly within the process.
Compared to the IGCC power plant from the application DE 10 2008 011 771, the power plant according to the invention has the advantage that the flushing gas for separating the hydrogen is also advantageously produced within the process, however, two cycles are not required, but rather only one. The flushing gas used is not the high-temperature waste gas from the combustion chamber, but the moderately hot waste gas from the waste heat recovery boiler.
Compared to the IGCC power plants known from the prior art, the IGCC power plant according to the invention has a cycle system that comprises a hydrogen membrane for separating hydrogen from the process gas, a combustion chamber of the gas turbine, the gas turbine itself, and a waste heat recovery boiler connected downstream of the gas turbine to generate the steam for a steam turbine. The lines for the cycle system run from the waste gas side of the waste heat recovery boiler to a “large” N 2 compressor, from there to the permeate side of the hydrogen membrane, and from there to the combustion chamber of the gas turbine and on to the gas turbine and the waste heat recovery boiler. The “large” N 2 compressor has substantially taken the place of the original “large” air compressor, and in keeping with the now only stoichiometric air supply only a “small” air compressor is present. As described in DE 10 2008 011 771, where flue gas recirculation is also provided for, a compressor is provided in the flue gas recirculation so as to generate the pressure required in the burner of the gas turbine. During operation of the power plant, the pressure level on the permeate side of the membrane is identical to the pressure in the burner, and this pressure is identical to the gas turbine inlet pressure, because an additional compression stage, solely for the membrane, does not appear to be expedient. Optionally, and depending on the H 2 membrane that is used, this cycle system may also comprise heat exchangers disposed upstream and downstream of the hydrogen membrane, a fan, or an additional preheater.
To operate an IGCC power plant, fuel in the form of coal, biomass, or waste is substoichiometrically (λ between approximately 0.2 and 0.4) gasified into energy-rich gas in a gasifier. The resulting raw gas is cooled, wherein the waste heat is already introduced to a steam turbine cycle. Subsequently, the raw gas is cleaned and run through desulfurization facilities, filters and similar units. At this point, the gas is combusted in a gas turbine, with the combustion chamber often being integrated in the turbine housing. The waste heat is used to evaporate fluid in a secondary cycle. The steam as such is conducted through a steam turbine and expanded almost to a vacuum. The residual heat may be fed to a heat transfer network. In modern IGCC power plants, the CO present in the raw gas is converted into CO 2 by way of a shift stage and is then separated. To this end, both physical scrubbers and membranes may be employed.
In the method according to the invention for operating an IGCC power plant, a membrane that selectively separates hydrogen is employed. The fuel, notably coal, is gasified with the help of oxygen, advantageously from an air separation facility, and is conducted over a CO shift stage, and supplied to the H 2 membrane. The hydrogen transported through the membrane is supplied to the gas turbine combustion chamber together with the nitrogen of the flushing gas. In the combustion chamber, air is supplied in such a ratio that the resulting flue gas contains only small quantities of oxygen, so that the flue gas can be conducted as a flushing gas to the permeate side of the H 2 membrane after passing through the waste heat recovery boiler. Small quantities as defined by the present invention shall be understood to mean proportions of 0.1 to 1% by volume.
So as to achieve a suitable air to coal gas ratio, the air is supplied to the combustion chamber notably in a substantially stoichiometric ratio (λ˜1). In combustion engineering, the λ symbol denotes the combustion air ratio. In combustion engines, the air-fuel ratio (stoichiometric ratio) is stated as λ=1 when the optimal ratio, for example, of 4.7 kg air to 1 kg fuel (for gasoline) exists. λ>1 denotes excess air and λ<1 denotes a lack of air. Within the scope of the present invention, a substantially stoichiometric ratio (λ˜1) shall generally be understood as a ratio of λ=1±0.1.
In the method according to the invention, the flue gas, predominantly comprising N 2 and having temperatures around 400° C. after recompression, can advantageously be supplied directly to the H 2 membrane, without any interposed heat exchangers. Known porous, ceramic membranes typically operate at temperatures between approximately 150 and 400° C. Above 400° C., sintering processes can disadvantageously change the pore structure. Below 150° C., water, which in most applications of membrane power plants is present on the feed or permeate side, can result in blockage of the pores. The development of silica membranes has progressed quite far, however they exhibit stability problems in the presence of steam. For this reason, presently TiO 2 and ZrO 2 membrane layer structures are also under development. As differs from polymer membranes, with these ceramic membranes the pressure levels on both sides of the membrane should generally be substantially identical, because problems may otherwise occur in terms of the mechanical stability.
However, if the H 2 membrane used for the hydrogen separation requires different operating temperatures, it is also possible to adapt this concept without difficulty. For this purpose, in one embodiment of the invention, a portion of the permeate flow (H 2 /N 2 gas mixture of the outflowing flushing current) could be supplied to the inflow flushing current (N 2 ) by means of a circulating fan, which overcomes the pressure loss that takes place in the membrane, wherein this portion is burned in a preheater and the heat that is produced in the process is used directly to preheat the flushing gas before it enters the filter. As an alternative, the combustion heat could also be coupled in by way of a heat exchanger, for example if the introduction of product water into the membrane is to be prevented. In this case, the combustion gas would not return to the membrane and would be supplied directly to the burner of the gas turbine.
The required quantity of permeate to be burned, notably of the hydrogen yielded, depends on the required end temperature of the flushing gas and the mass flow thereof. A typical case would be the increase of the flushing gas temperature from 400 to 600° C. For this purpose, approximately 15% by volume or by weight of the permeate would have to be burned in the preheater (by comparison, according to FIG. 6 , the entire permeate supplies so much thermal heat that the temperature increase of the approximately 1.5 times greater N 2 -rich gas flow in the burner of the gas turbine is 4 times greater (400-1200° C.)). Such high operating temperatures for the flushing gas are particularly desirable when the membrane is a mixed protonic-electronic conductor. This conductor generally requires temperatures between 500 and 700° C. for optimal operation.
In a further embodiment of the invention, a polymer membrane is used for the hydrogen separation. In this case, the optimal operating temperature of the H 2 membrane is around 100° C., so that the flushing gas, before entering the membrane, is first cooled to this temperature by a recuperative heat exchanger. In the recuperative design, this cooling is accompanied by simultaneous heating of the permeate before this is introduced into the combustion chamber. Even this arrangement constitutes a considerable improvement in terms of process engineering compared to the process described in DE 10 2008 011 771 because, in this case, only low-temperature recuperators having low complexity are required, while in DE 10 2008 011 771 the heat exchangers must operate at a considerably higher temperature level (T>1000° C.).
Regardless of the selected operating temperature of the H 2 membrane, the process according to the invention also allows additional support of the flushing gas mass flow by supplying compressed N 2 from an air separation facility. Compressed N 2 here shall be understood as nitrogen gas at a pressure of at least approximately 20 bar, which is typically provided by an air separation facility specified for IGCC.
The invention advantageously combines a process for an IGCC power plant that is simplified, as compared to the known prior art, and has an improved energy balance. In addition, it can be adapted to the use of different hydrogen membranes and the related operating temperatures. An essential part of the invention is that, contrary to the standard IGCC, the waste gas from the gas turbine does not contain any, or only very little, oxygen and, because of this property, is suited for use as a flushing gas. The absence of oxygen is achieved by a sufficiently low, substantially stoichiometric fresh air supply. The absence of oxygen in the flushing gas ensures that the hydrogen that has permeated through the membrane does not burn when admixed to the flushing gas, which would result in unacceptably high increases in the temperature of the flushing gas and the membrane.
The IGCC power plant according to the invention, suited for carrying out the method, therefore comprises a gasifier for gasifying a solid fuel, a means for providing oxygen for the gasifier, at least one shift stage connected downstream of the gasifier for converting CO and steam into CO 2 and hydrogen, at least one gas cleaning stage connected downstream of the gasifier, a hydrogen-selective membrane connected downstream of the gasifier, a means for providing flushing gas for the permeate side of the membrane, and a gas turbine, wherein a line leads from the permeate side of the membrane to the combustion chamber of the gas turbine, and the means for providing the flushing gas is the gas turbine, and a further line is disposed from the waste heat recovery boiler connected downstream of the gas turbine to the permeate side of the membrane filter.
The IGCC power plant concepts known from the prior art, as presented in the introductory part of the present application, are shown in FIGS. 1 to 5 . The concept of an IGCC power plant according to the invention and the individual method steps for operating the same will be explained in detail hereinafter based on schematic diagrams ( FIGS. 6 to 8 ), wherein FIGS. 7 and 8 each show particularly advantageous embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 : is an IGCC process having no integrated air separation facility;
FIG. 2 : is an IGCC process having an integrated air separation facility;
FIG. 3 : is an IGCC process having an integrated air separation facility and an unflushed H 2 membrane for the separation of CO 2 ;
FIG. 4 : is an IGCC process having an integrated air separation facility and a modestly flushed H 2 membrane for the separation of CO 2 , the N 2 flushing gas originating entirely from the air separation facility, from [1];
FIG. 5 : is an IGCC process having an integrated air separation facility and a strongly flushed H 2 membrane for the separation of CO 2 , the N 2 flushing gas originating from the waste gas of the gas turbine combustion chamber [from DE 10 2008 011 771];
FIG. 6 : is an IGCC process according to the invention having an integrated air separation facility and a strongly flushed H 2 membrane for the separation of CO 2 , the N 2 flushing gas originating from the waste gas of the waste heat recovery boiler and optionally additionally from the air separation facility;
FIG. 7 : is an IGCC process according to the invention having an integrated air separation facility and a strongly flushed H 2 membrane for the separation of CO 2 , the N 2 flushing gas originating from the waste gas of the waste heat recovery boiler and optionally additionally from the air separation facility, with an additional preheating cycle for raising the flushing gas temperature from approximately 400 to 500-700° C. at the inlet into the membrane so as to be able to operate a membrane having characteristic operating temperatures of 500-700° C.; and
FIG. 8 : is an IGCC process according to the invention having an integrated air separation facility and a strongly flushed H 2 membrane for the separation of CO 2 , the N 2 flushing gas originating from the waste gas of the waste heat recovery boiler and optionally additionally from the air separation facility, with an additional recuperative heat exchanger for lowering the flushing gas temperature from approximately 400° C. to 100-300° C. at the inlet into the membrane so as to be able to operate a membrane having characteristic operating temperatures of approximately 100-300° C.
FIG. 9 : is an example of an unflushed H 2 membrane (see concept according to FIG. 3 );
FIG. 10 : is an example of a moderately flushed H 2 membrane (see concept according to FIG. 4 );
FIG. 11 : is an example of a strongly flushed H 2 membrane (see concepts according to FIGS. 5 to 8 ); and
FIG. 12 : shows standardized mole flows (rounded) as reference values in the flow chart of the IGCC power according to the invention (in the simple basic variant without additional measures for changing the temperature of the flushing gas), the schematic diagram of this power plant having already been shown in FIG. 6 , wherein K=compressor, GT=gas turbine, G=generator, AHK=waste heat recovery boiler, and DT=steam turbine.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIGS. 1 to 8 the following meanings apply:
1 Gasifier 2 Coal gas conditioning, optionally includes a shift stage 3 H 2 membrane 4 Combined cycle power plant, comprising:
4 a Combustion chamber of the gas turbine 4 b Gas turbine 4 c Waste heat recovery boiler 4 d Steam turbine
5 Air separation facility, and 6 Compressor 7 Heat exchanger 8 Preheater
Examples of a simulated hydrogen separation process are described in FIGS. 9 to 11 to provide a better understanding of the driving forces prevailing there.
In the IGCC process according to the invention ( FIGS. 6 to 8 ), the fuel, notably coal, is gasified in a gas flow having a low oxygen component. The ratio of the oxygen component to the component of nitrogen and argon should advantageously range approximately 20. In addition to oxygen, the gas flow may contain steam and CO 2 . To this end, the conditioned coal is converted in a gasifier ( 1 ) at high temperatures in the aforementioned gas flow at increased pressure, and preferably no less than 30 bar, into carbon monoxide-rich, hydrogen-containing process gas. This process is typically carried out at temperatures between 800 and 1500° C. The resulting gas is cooled. The excess heat is utilized in the overall process.
In a shift process ( 2 ), the carbon monoxide-rich process gas is subsequently converted to a hydrogen-rich product gas, which now contains the carbon dioxide to be separated. Matching the individual process steps, the process gas is subjected to different gas cleaning stages comprising solid matter and sulfur separation, which are not described in detail here. These gas cleaning steps can be disposed upstream of, downstream of, and between the individual shift stages. Steps necessary for gas cleaning may also be disposed within the shift stages.
In the method according to the invention, the coal gas should be separated from the CO 2 -containing gas flow by way of a specific operating membrane. To this end, in a further step, hydrogen (H 2 ), as the energy-carrying component, is separated from the product gas flow using a hydrogen-permeable membrane ( 3 ). The remaining coal gas enriched in this way, which is substantially CO 2 -free, is then supplied to the combined cycle (CC, 4 a - 4 d ) power plant. The CO 2 -rich residual gas containing only little H 2 remains under the operating pressure of the gasification and can be supplied to a conditioning process (remaining H 2 combustion, drying and compression to approximately 100 bar for CO 2 transport and storage).
The membrane ( 3 ) is preferably a membrane that conducts hydrogen ions, which is to say protons, and because of this transport mechanism is distinguished by high selectively for H 2 as compared to CO 2 . It is also possible to use a different membrane that is suited for separating hydrogen. In particular porous, ceramic membranes, mixed protonic-electronic conductors, and polymer membranes should be mentioned as H 2 membranes suitable for this purpose.
In the separating step, a flushing gas is used on the permeate side. This flushing gas normally has the same or similar pressure as that of the burner at the inlet to the gas turbine, because recompression of the flushing gas exiting the membrane is not provided for. In general, the process gas in the membrane has the same or similar pressure as that of the gasification, and in general the gasification has the same or similar pressure as that of the gas turbine.
However, conceivable applications of the H 2 membrane in the IGCC also include those in which the aforementioned pressure conditions are not approximately 1, and may certainly range up to approximately 2.
a) With membranes that have excellent mechanical stability, it may be advantageous to cut the permeate pressure in half, for example, so as to increase the driving force. In this case, the energy expenditure for the H 2 recompression still appears to be acceptable, compared to, for example, 6-fold pressure doubling from 0.5 to 32 bar in the case of a concept having a permeate vacuum instead of flushing.
b) Even today, IGCC developments are apparent in which the gasification pressure is raised considerably, in the range of 50 bar and above, which is to say approximately twice as high as the gas turbine pressure, which has changed less in the course of the development. With membranes that have excellent mechanical stability, it may also be advantageous to leave the permeate pressure equal to the gas turbine pressure, and to also leave the process gas pressure equal to the (now very high) gasifier pressure, so as to further increase the driving force.
Compared to ceramic membranes, polymer membranes appear to be suited well for use when high differential pressures occur. Their range of application today is 1 to 150 bar on the process gas side and 50 mbar to 20 bar on the permeate side (information according to BORSIG GmbH). In membrane plants using polymer membranes, CO 2 is already separated from natural gas, which is still under high pressure after production.
Hydrogen is withdrawn from the process gas, which on the primary side (process gas side, retentate side) comes in contact with the membrane, in that the hydrogen migrates through the membrane. The partial pressure difference of the hydrogen between the primary and permeate sides is the driving potential. The permeate side is the secondary side, which is to say the side of the membrane to which the hydrogen migrates. So as to maintain the hydrogen partial pressure difference, the supply of flushing gas must always be sufficient.
A step in this method that is essential to the invention is that the flushing gas is yielded directly from the combustion product of the gas turbine ( 4 a ), and more specifically only after the waste gas from the gas turbine ( 4 b ) has passed through the downstream waste heat recovery boiler ( 4 c ). At this point, the combustion product is present in a depressurized state (approximately 1 bar) and has a low temperature. The amount of waste gas that is withdrawn is always the amount that is required to limit the combustion temperature in the combustion chamber ( 4 a ) of the gas turbine. A combination compressor ( 6 ) both for N 2 (recirculated flue gas) and for air, which must be operated at uniform pressure, brings the gas flows, which are supplied in particular for the purpose of cooling the gas turbine combustion chamber ( 4 a ), to the necessary pressure level of the gas turbine.
The flushing gas substantially contains nitrogen, steam, and only a very small proportion of oxygen, because the combustion in the gas turbine ( 4 a - 4 b ) is generally carried out with a substantially stoichiometric oxygen-fuel ratio (as a further step of the method that is essential to the invention) (λ˜1), and low quantities of CO 2 and argon. A possible gas composition would be the following, for example:
N 2 : 65-75% by volume
H 2 O: 25-30% by volume
O 2 : 0.6-1% by volume
CO 2 : 0.6-1% by volume
Ar: 0.7-0.9% by volume
When using a membrane for which steam in such high concentration (caused by the enrichment due to the cycle system) cannot be tolerated, measures must be taken that lower the water content after outlet from the waste the heat recovery boiler ( 4 c ) to the necessary value, for example by cooling and condensation.
The excess of oxygen is also low because the flushing gas flow at the inlet into the membrane is primarily composed of recirculated flue gas. This recirculated flue gas is advantageously used as the flushing gas for the hydrogen membrane and also as a heat-absorbing gas for limiting the combustion temperature in the combustion chamber ( 4 a ) of the gas turbine.
A particularly advantageous operating temperature will be obtained for the membrane ( 3 ) depending on which type of H 2 membrane is selected for the hydrogen separation. Porous ceramic membranes, for example, operate particularly advantageously around 400° C., while mixed protonic-electronic conductors prefer higher temperatures between 500 and 700° C., and more particularly between 550 and 600° C. On the other hand, polymer membranes can also be used, however they should usually not be operated at more than 100° C.
In the embodiment of the IGCC process according to the invention, the recirculated flue gas is first at low temperatures downstream of the waste heat recovery boiler and upstream of the N 2 compressor ( 6 ). It is then raised to a temperature of approximately 400° C., in the N 2 compressor ( 6 ), during the compression from 1 bar to approximately 25 bar (with intercooling), so that advantageously no further temperature adjustment of the recirculated flue gas/flushing gas is required when using a porous, ceramic membrane (see FIG. 6 ).
If a mixed protonic-electronic conductor is provided as the hydrogen membrane, the process can be adjusted to the effect that a portion of the hydrogen/nitrogen mixture produced in the permeate area of the membrane is burned substantially stoichiometrically with small quantities of oxygen in a partial combustion step in a preheater ( 8 ) (see FIG. 7 ). The heat produced in this way can be used to sufficiently heat the flue gas/flushing gas on the permeate side of the H 2 membrane having insufficient temperatures. In this H 2 membrane ( 3 ), hydrogen permeates, for example in the form of protons, from the process gas side, which is the feed and retentate side, to the permeate side and is supplied to the flushing gas in this way.
In addition to the flushing gas, the gas flow present on the permeate side downstream of the membrane contains the essential quantity of hydrogen produced in the gas generation process. This gas substantially comprises nitrogen and hydrogen and is present at a pressure that allows this gas to flow as coal gas into the combustion chamber of the gas turbine.
FIGS. 9 to 11 show, by way of example, the H 2 separation as a function of different boundary conditions, in particular as a function of the permeate-side overall pressure and the quantity of N 2 flushing gas that is used. The following were predefined:
Feed=shifted coal gas at 25 bar (CO 2 =40 mole percent, H 2 =60 mole percent) and
Permeate=H 2 (CO 2 ) in FIG. 9 at 0.5 bar and
Flushing gas+permeate=N 2 +H 2 (CO 2 ) in FIGS. 10-11 at 25 bar.
FIG. 9 shows the circumstances for an unflushed H 2 membrane. The driving force is high upon entering the membrane, for example 14.5 bar, and initially the H 2 separation is progressing well. However, when the high separation degree range, which is extremely important with respect to the energy yield, is reached over the course of the separation process (90% separation and higher), the driving force decreases to zero before 100% separation is reached. This means that only degrees of separation that are considerably below 100%, for example 90%, can be implemented. 10% of the hydrogen will then not be available for power generation in the CC process. Additionally, in the example selected, the permeate (pure hydrogen) only has a pressure of 0.5 bar and therefore disadvantageously requires compression to the operating pressure before entering the combustion chamber. If a higher permeate pressure than 0.5 bar were selected so as to save compression energy, the driving force would be even lower, notably at the end of the separation process, and the achievable degree of H 2 separation would be less than approximately 90%.
FIG. 10 shows a simulation using a moderately flushed H 2 membrane, such as that which is described in the concepts of Göttlicher [1] and in DE 10 2008 011 771. The compressed N 2 generated from the air separation facility at a pressure of approximately 25 bar is used as the flushing gas. The mass flow ratio of N 2 to H 2 is no more than approximately 1:1.5, which means either that there is no driving force for the H 2 transport through the membrane or the driving force is substantially equal to zero. As a result, a high degree of separation will only be possible with unreasonably large membrane surfaces.
In contrast, the process according to the invention has considerable advantages. FIG. 11 shows the simulated H 2 separation for a strongly flushed H 2 membrane, wherein the flushing gas is provided in part from the air separation facility (compressed N 2 at 25 bar), however the majority is provided from the flue gas recirculation, also at 25 bar. The mass flow ratio of N 2 to H 2 now is approximately 4:1, which was determined by way of a simulation calculation using the commercial program PRO/II. Because of the strong flushing, the H 2 partial pressures in the flushing gas on the permeate side are low. The driving forces are therefore high, and notably at the end of the separation process the conditions are still sufficient (constantly positive driving force!) to achieve high separation degrees very close to 100%, which can be implemented by designing the membrane module with a moderately increased membrane surface.
The crucial advantage of the present invention is that the proposed operating process now allows very high H 2 separation degrees, for example of 97%, to be achieved, and a local significant increase in the membrane surface is only required in a small area at the end of the separation process, whereby the total surface of the membrane must only be slightly higher. The following considerations are provided as a reference.
In porous membranes, for example, the local permeate flow density is proportional to the driving force, which is to say to the H 2 partial pressure difference between the feed and permeate sides. Because the required local membrane surface is inverse to the permeate flow density, it is also inversely proportional to the H 2 partial pressure difference. In the middle of the separation process at 50% separation, this is approximately 5 bar, and with 90% and 97% separation, it is approximately 1 and 0.5 bar, respectively.
Assuming a membrane with 90% separation performance (on average, an approximately 5 bar driving force), approximately the same membrane surface again is additionally required to carry out the separation with a 90% to 97% degree of separation (in this end region, on average, an approximately 0.5 bar driving force).
H 2 separation degrees of 98 or 99% are also conceivable with strongly flushed H 2 membranes.
Further advantageous embodiments of the invention relate to improving the CO 2 separation and conditioning and the provision of oxygen and compressed N 2 by oxygen membranes instead of the aforementioned air separation facility.
Only a small quantity of hydrogen usually remains in the retentate of the H 2 membrane ( 3 ). This retentate substantially contains the carbon dioxide produced during the gas generation process as well as steam and the aforementioned remainder of hydrogen. This retentate has a pressure that is predetermined by the process. This pressure is preferably 20-30 bar and is usually only lowered by the pressure loss caused by the conductance of the gas flow through the apparatuses and pipes.
According to a particularly advantageous embodiment of the invention, the hydrogen remaining in the retentate is burned in a combustion step. The oxygen-containing gas required for this can advantageously be withdrawn from the oxidation gas upstream of the gasifier ( 1 ). In a special embodiment of the invention, for example, substantially pure oxygen can optionally be withdrawn for this purpose at an additional withdrawal site downstream of the oxygen compression and used in the combustion process.
The gas flow developing during this combustion which is under process pressure almost exclusively contains carbon dioxide (CO 2 ) and steam. A portion of this gas flow can be separated and, after cooling with condensation and separation of the water, supplied to the conditioning of the CO 2 . The option for such an increase in the component of CO 2 in this gas is a key advantage of this concept, which can result in more effective and cost-effective conditioning of CO 2 from this power plant.
According to a further advantageous embodiment of the invention, which is also partially described in DE 10 2008 011 771, another portion can optionally be used as flushing gas for an oxygen membrane for the purpose of separating oxygen from air. For this purpose, compressed air is removed downstream of the air compressor of the gas turbine and supplied to an oxygen membrane on the primary side. The flushing gas, advantageously a branched-off flow from the residual gas, is supplied to the secondary side, this being the permeate side of the membrane. The O 2 membrane is preferably a membrane that conducts oxygen ions. However, it is also possible to use a different membrane that is suited for separating oxygen. The driving potential in this separation process is the difference of the partial pressures of the oxygen on the air side and the permeate side. The oxygen migrates through the membrane to the permeate side into the flushing gas. In this way, a considerable portion of or the entire oxygen quantity required for the coal gasification can be separated from the air using a membrane, instead of the otherwise conventional air separation facility.
The gas flow on the permeate side primarily contains oxygen, flushing gas, which is to say CO 2 -rich residual gas, and foreign gases. The foreign gases substantially originate from the air, because they too permeate the membrane to a low degree. The ratio of the oxygen quantity to the quantities of these foreign gases is preferably around 20. Such a ratio usually allows for a carbon dioxide content in the dried waste gas of the gasification process of more than 95% by volume.
According to a further advantageous embodiment, which is also partially described in DE 10 2008 011 771, another portion of the oxygen quantity required for the gasification of the coal, this quantity being substantially free of foreign gases, can be yielded in a further separation step using a further membrane. Again, the ratio of the oxygen quantity to the foreign gas quantity in the permeate should preferably be around 20. However, no flushing gas is used on the permeate side to operate this further oxygen membrane. The partial pressure of the oxygen in the gas flow leaving this membrane on the permeate side is lower than the partial pressure of the oxygen on the retentate side. This creates a driving potential for oxygen permeation.
The oxygen flow that is obtained can be compressed to the necessary pressure by a compressor for further use. By varying the quantity, the oxygen yielded in this way can advantageously be used to regulate the oxygen concentration for gasification of the coal in the gasifier ( 1 ). If the oxygen membrane operated with flushing gas can supply the oxygen quantity required for the entire process, the second oxygen membrane and the related compressor may be eliminated.
The retentate from the oxygen membranes can be supplied as an oxidizing agent to the gas turbine. This will lower the demand for fresh air, which is supplied so as to limit the temperature of the gas turbine.
The waste gas flow (residual gas) originating from the combustion of the residual hydrogen, from which a portion is optionally separated upstream of the oxygen membrane, substantially comprises carbon dioxide and steam. Minor impurities can be due in particular to the different gas separation steps. This gas flow is present at the process pressure (gasifier pressure). The pressure in this gas flow is exclusively reduced by pressure losses caused by the gas flowing through the pipes and apparatuses. This pressure is maintained even after the gas has cooled to a temperature of below 40° C., for example, and after the related condensation of significant quantities of the water that is produced. After separating the water, the concentration of carbon dioxide CO 2 in the waste gas is more than 95% by volume.
In general, foreign gases can penetrate into the permeate when the separation of the gases in the membrane is incomplete. With the process described, however, the component of permanent gases is generally so low that a liquid phase of the CO 2 is possible even at ambient temperatures (up to 31° C.).
Because the pressure is substantially maintained in the process described, it is possible to liquefy the CO 2 using only one further pressure stage having only a low compression factor. With minor use of mechanical energy, liquid CO 2 can be brought to a pressure stage such as that which is required for underground storage or final waste disposal of the CO 2 .
FIG. 12 shows the mass flow ratios in the IGCC process according to the invention to provide a better understanding. Rounded values (reference values) are shown for standardized mole flows at key positions of the power plant. The reference variable selected was: C input(=CO 2 output)=100 [arbitrary mole flow unit]. In the IGCC power plant, the following reactions (gasification/(shift/combustion)) take place:
4C+O 2 +H 2 O=2CO+2H 2
CO+H 2 O═CO+H 2
2H 2 +O 2 =2H 2 O
The standardized mass flows (reference values) marked with (a) to (m) in FIG. 12 are listed in the table below:
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
(m)
C
100
—
—
—
—
—
—
—
100
—
—
—
—
O 2
25
—
—
—
—
—
—
75
—
—
—
—
—
H 2 O
50
—
—
—
—
—
—
—
—
150
—
—
—
CO
—
—
100
—
—
—
—
—
—
—
—
—
—
CO 2
—
—
—
100
—
—
—
—
—
—
—
100
—
H 2
—
—
50
150
150
150
—
—
—
—
—
—
—
N 2
—
100
—
—
600
—
600
300
400
900
500
—
400
Literature cited in the application:
[1] Göttlicher, Gerold, “Energetik der Kohlendioxidrückhaltung in Kraftwerken (Energetics of carbon dioxide pressure maintenance in power plants)”, (1999) VDI-Verlag GmbH, Düsseldorf, 1999, ISBN 3-18-342106-2 | 4y
|
CLAIM FOR PRIORITY
[0001] This application is a continuation of patent application Ser. No. 11/273,778, filed Nov. 15, 2005, now allowed, which is a continuation of patent application Ser. No. 10/732,934, filed Dec. 11, 2003, which claims priority under 35 USC §119(e) from Provisional Application Ser. No. 60/436,159 filed Dec. 23, 2002.
BACKGROUND OF INVENTION
[0002] The present invention is directed to the reduction of protein deposition on surfaces. The invention provides compositions and methods for inhibiting the deposition of protein on the surfaces of medical devices, particularly biomedical and prosthetic devices. The invention is based on the discovery that certain polymers and related copolymers comprising the monomer n-isopropylacrylamide (NIPAM), significantly inhibit protein deposition on the surfaces of contact lenses.
[0003] Proteins adsorb to almost all surfaces and the minimization or elimination of protein adsorption has been the subject of numerous studies, such as those reported by Lee, et al., in J. Biomed. Materials Res ., vol. 23, pages 351-368 (1989). Sensors, chromatographic supports, immunoassays, membranes for separation, biomedical implants, prosthetic devices (e.g., contact lenses) and many other devices or objects can be adversely affected by protein adsorption. A method and/or means for treating the surfaces of such objects so as to prevent or reduce protein deposition would therefore be quite advantageous.
[0004] The use of NIPAM-containing polymers to modify surfaces and control protein deposition on glass and silicon substrates has been previously described. The following publications provide further background regarding such modifications:
[0005] 1. Kidoki, et al., Langmuir, 17, pp. 2402-2407 (2001);
[0006] 2. Bohanon, et al., J. Biomater. Sci. Polymer Edn ., Vol. 8, No. 1, pp. 19-39 (1996);
[0007] 3. International (PCT) Patent Publication No. WO 02/30571 A2 (Sudor);
[0008] 4. U.S. Pat. No. 6,447,897 (Liang, et al.);
[0009] 5. U.S. Pat. No. 6,270,903 (Feng, et al.); and 6 . Huber, et al., Science , Vol. 301, pp. 352-354, Jul. 18, 2003.
[0010] The above-identified publications do not disclose or suggest that NIPAM-containing polymers could be used to modify the surfaces of medical devices, such as contact lenses, and to control protein deposition and release on such surfaces.
[0011] The terms “soft” and “hard” relative to contact lenses are generally associated with not only the relative hardness of the respective types of lenses, but also the type of polymeric material from which the lenses are formed. The term “soft” generally denotes a contact lens that is formed from a hydrophilic polymeric material, such as hydroxyethyl methacrylate or “HEMA”, while the term “hard” generally denotes a lens that is formed from a hydrophobic polymeric material, such as polymethylmethacrylate or “PMMA”. The surface chemistry and porosity of the hard and soft lenses is quite different. Soft lenses typically contain a large amount of water, are quite porous, and bear ionic charges on the exposed surfaces of the lenses, while hard lenses are considerably less porous and generally do not bear ionic surface charges.
[0012] The ionic surfaces and porous nature of soft contact lenses can lead to significant problems when the lenses come into contact with the tear film due to the complex composition of the tear film, which is largely comprised of proteins, lipids, enzymes and various electrolytes. Tear components include albumin, lactoferrin, lysozyme and a number of immunoglobulins. The uptake of proteins from the tear fluid onto the lens is a common problem and depends on a number of factors, including the nature of the materials from which the lens is made.
[0013] Soft contact lenses act as efficient substrates for protein deposition and adsorption. This fouling can lead to dehydration of the lens and instability of the tear film, resulting in discomfort and lack of tolerance in the wearer. Adsorption of proteins can also facilitate bacterial colonization and this can increase the risk of vision-threatening infections.
[0014] In view of the potential fouling of contact lenses and the problems created by such fouling, as discussed above, it is generally accepted that contact lens cleaning must be a regular part of a patient's lens care regimen. Many different types of cleaning agents have been utilized in the past for this purpose. Cleaning agents such as surfactants and enzymes are typically incorporated into contact lens care products to remove protein deposits. However, the use of these agents can lead to irritation, and in cases where rubbing and cleaning regimens are required, there is a possibility that the cleaning agents will not be used properly or will be used in a manner that damages the lenses. In view of the foregoing problems, it would be advantageous if the surfaces of contact lenses could be modified so as to prevent or reduce the adsorption of proteins to the surfaces.
[0015] Various attempts have been made to reduce protein deposit formation on contact lenses. The following patents may be referred to for further background regarding such attempts:
[0016] U.S. Pat. No. 4,411,932 describes the use of polymeric alcohols and polymeric ethers, including poly(ethylene glycol), polyethylene oxide and polyethylene glycol methyl ether, as prophylactic agents against soilant deposits on contact lenses;
[0017] U.S. Pat. No. 6,274,133 (Hu et al.) describes the use of cationic cellulose polymers to prevent the build-up of lipids and proteins on a silicone-hydrogel lens;
[0018] U.S. Pat. No. 6,323,165 (Heiler, et al.) describes the use of charged polyquaternium polymers to block the binding of proteins to hydrophilic contact lenses; and
[0019] U.S. Pat. No. 6,096,138 (Heiler, et al.) describes the use of polyquaternium polymers such as Luviquat® (BASF), which is a mixture of vinylpyrrolidone and vinylimidazolium moieties that can bind to hydrophilic contact lens materials, so as to block the binding of proteinaceous materials to the lenses.
[0020] These prior attempts to reduce protein binding have drawbacks. For example, cationic polymers may act as irritants upon contact with the eye when utilized at high concentrations. Additionally, due to the positive charge character of these macromolecules, complex formation with anionic surfactants or other components of CLC products may lead to flocculation and phase separation in the formulation, which is a significant problem. Accordingly, there is need for new approaches to provide protein resistant surfaces.
[0021] Due to the trend toward use of extended wear lenses, it would be useful to be able to provide contact lens wearers with a contact lens surface that inhibits adsorption of proteinaceous matter for extended time periods, without compromising the safety of the patient. The polymer should also be compatible in contact lens care solutions when storage, disinfection and/or cleaning are desired by the patient. The present invention is directed to satisfying these needs.
SUMMARY OF INVENTION
[0022] The present invention is directed to the use of polymers that are surface active and exhibit a temperature response in aqueous solutions. The polymers and related polymers (e.g., co-polymers) are formed from a N-isopropylacrylamide (“NIPAM”) monomer.
[0023] The present invention is based on a discovery that the NIPAM polymers and related polymers may be utilized to inhibit protein deposition on the surfaces of hydrogel contact lenses. The NIPAM polymers provide unique solution properties, and it has been discovered that these properties can be employed in formulations where protein resistant hydrogel surfaces are desired.
[0024] As discussed above, there is a need for improved approaches for modifying the adsorption of proteins on the surfaces of contact lenses. The present invention is based on a discovery that the NIPAM polymers described herein are uniquely suited for this purpose.
[0025] The NIPAM polymers described herein may be employed in various manners in order to achieve modification of contact lens surfaces and surfaces of other medical devices. For example, contact lenses can be stored in solutions containing NIPAM polymers prior to being worn. This prophylactic approach allows the polymers to form a protective layer on the surface of the lenses before the consumer even exposes the lenses to tear fluids containing protein. The NIPAM polymers may also be incorporated in multi-purpose solutions for treating contact lenses on a daily basis. Chemical grafting on surfaces to form permanent coatings of NIPAM polymers is another method for preparing protein resistant surfaces.
[0026] In addition to contact lenses, the surface modification techniques described herein may be applied to various medical devices where protein resistant surfaces are desired, such as intraocular lenses, catheters, cardiac stents, prosthetics, and other medical devices that undergo prolonged exposure to proteins during use in or on the bodies of humans or other mammals.
[0027] Although not wishing to be bound by theory it is believed that the NIPAM polymers described herein have a range of inherent physical properties (e.g., low interfacial free energy, hydrophilic-hydrophobic properties, very low toxicity, dynamic surface mobility and steric stabilization) that enable these polymers to exhibit superior protein inhibiting characteristics.
BRIEF DESCRIPTION OF DRAWINGS
[0028] FIG. 1 is a graph showing the results of the tests described in Example 1; and
[0029] FIG. 2 is a graph showing the results of the tests described in Example 3.
DETAILED DESCRIPTION OF THE INVENTION
[0030] The NIPAM polymers utilized in the present invention have the following formula:
wherein n is a whole number of from 10 to 3,000.
[0031] The NIPAM polymers utilized in the present invention include various types of polymers that comprise the above-described monomer. The polymers may be formed entirely from the NIPAM monomer identified above, or other monomers can be incorporated into the polymer by copolymerizing the NIPAM monomer with other monomers, such as acrylic acid, acrylamide, N-acetylacylamide, N,N-dimethylacrylamide and butyl methacrylate. In addition, modified polymers or copolymers containing the NIPAM monomer can be prepared by functionalization of end groups, preparation of block copolymers, and cross-linking of polymers. All such polymers, copolymers or modifications thereof are referred to herein as either “NIPAM polymers” or “PNIPAM”. The NIPAM polymers utilized in the present invention will typically have molecular weights of from 1,000 to 300,000 Daltons. The polymers are available from Polymer Source, Inc., Dorval, Quebec (Canada).
[0032] The amount of PNIPAM utilized in the compositions of the present invention will vary depending on the form of the compositions and the intended use thereof. The concentration of PNIPAM utilized will generally be an amount sufficient to obtain a solution surface tension of less than 50 milliNewtons per meter (“mNm −1 ”) at room temperature (23° C.).
[0033] The above-described NIPAM polymers are surface active, and therefore will readily adsorb to most types of surfaces. Factors such as the type of surface (hydrophobic versus hydrophilic), temperature, buffer and excipients will influence the interaction between the polymers and a surface, and will influence the magnitude of the interactions.
[0034] The above-described PNIPAM polymers may be combined with other components commonly utilized in products for treating contact lenses, such as rheology modifiers, enzymes, antimicrobial agents, surfactants, chelating agents or combinations thereof. The preferred surfactants include anionic surfactants, such as RLM 100, and nonionic surfactants, such as the poloxamines available under the name “Tetronic®”, and the poloxamers available under the name “Pluronic®”. Furthermore, a variety of buffering agents may be added, such as sodium borate, boric acid, sodium citrate, citric acid, sodium bicarbonate, phosphate buffers and combinations thereof.
[0035] The compositions of the present invention that are intended for use as CLC products will contain one or more ophthalmically acceptable antimicrobial agents in an amount effective to prevent microbial contamination of the compositions (referred to herein as “an amount effective to preserve”), or in an amount effective to disinfect contact lenses by substantially reducing the number of viable microorganisms present on the lenses (referred to herein as “an amount effective to disinfect”).
[0036] The levels of antimicrobial activity required to preserve ophthalmic compositions from microbial contamination or to disinfect contact lenses are well known to those skilled in the art, based both on personal experience and official, published standards, such as those set forth in the United States Pharmacopoeia (“USP”) and similar publications in other countries.
[0037] The invention is not limited relative to the types of antimicrobial agents that may be utilized. Examples of antimicrobial agents that may be used include: chlorhexidine, polyhexamethylene biguanide polymers (“PHMB”), polyquaternium-1, and the amino biguanides described in co-pending U.S. patent application Ser. No. 09/581,952 and corresponding International (PCT) Publication No. WO 99/32158, the entire contents of which are hereby incorporated in the present specification by reference.
[0038] The preferred antimicrobial agents are polyquaternium-1, and amino biguanides of the type described in U.S. patent application Ser. No. 09/581,952 and corresponding International (PCT) Publication No. WO 99/32158. The most preferred amino biguanide is identified in U.S. patent application Ser. No. 09/581,952 as “Compound Number 1”. This compound has the following structure:
It is referred to below by means of the code number “AL-8496”.
[0039] The ophthalmic compositions of the present invention will generally be formulated as sterile aqueous solutions. The compositions must be formulated so as to be compatible with ophthalmic tissues and contact lens materials. The compositions will generally have an osmolality of from about 200 to about 400 milliosmoles/kilogram water (“mOsm/kg”) and a physiologically compatible pH.
[0040] The compositions of the present invention and the ability of those compositions to reduce protein adsorption on contact lenses are further illustrated by the following Examples. Unmodified (i.e., non-ionic) NIPAM polymers and modified (i.e., end terminated with —COOH groups) NIPAM polymers were added to appropriately buffered solutions to demonstrate the ability of these polymers to reduce protein adsorption when utilized as components of buffered multi-purpose solutions for treating contact lenses. A simple means of producing PNIPAM-modified surfaces was used in order to mimic the contact lens disinfection/cleaning regime typically used by the consumer.
EXAMPLE 1
[0041] The tests described below were conducted to evaluate the ability of NIPAM polymers to modify contact lens surfaces and thereby reduce protein adsorption.
[0000] Materials/Methods
[0042] The materials and methods utilized in the evaluation were as follows:
[0000] Chemicals
[0043] Lysozyme (Sigma, Chicken egg white, grade 1, 3× crystalline), Trifluoroacetic Acid Anhydrous (Sigma, Protein sequencing grade) Acetonitrile (EM Science, HPLC grade), Sodium Phosphate Monobasic, Monohydrate (Sigma, ACS reagent grade), Sodium Phosphate Dibasic, Anhydrous (Sigma, ACS reagent grade), Sodium Chloride (Sigma, ultra pure grade), Unisol®4 (Alcon Laboratories, Inc., preservative-free. pH-balanced saline solution for rinsing)
[0044] The NIPAM polymers utilized are identified in Table 1 below. These polymers were purchased from Polymer Source Inc. and were used without further purification.
TABLE 1 Polymer Type M v × 10 3 M w /M n P2991-NIPAM Non-ionic 46,380 2.36 P604-NIPAM Non-ionic 71,600 2.44 P1239-NIPAM Non-ionic 122,000 2.50 P2426F2-NIPAM- Anionic 132,000 1.29 COOH
Lenses
[0045] Acuvue (Vistakon, a division of Johnson & Johnson Vision Products, Inc) lenses were used as the substrate in this study. The lenses had the following parameters: 42% etafilcon A, 58% water, FDA Group IV lens. Diameter, 14.0 mm; base curve, 8.8 mm; power, −2.00.
[0000] Formulations
[0046] The NIPAM and NIPAM-COOH polymers identified in Table 1 were formulated at pH 7.8 in a buffered vehicle containing 1.5% sorbitol, 0.6% boric acid and 0.32% NaCl. In a beaker, all the formulation chemicals except for the NIPAM polymers were weighed out and purified water was added (QS to 95%). The pH was adjusted to 7.8 with NaOH/HCl. The NIPAM polymer was weighed out and added to the buffer solution and this was stirred overnight to solubilize the polymer. The test formulations are shown in Table 2 below; the concentrations are expressed as weight/volume percent (“w/v %”):
TABLE 2 Formulation Numbers 9591-47C Component 9591-47A 9591-47B (Control) P2991-NIPAM 0.034 0.017 — Sorbitol 1.5 1.5 1.5 Boric Acid 0.6 0.6 0.6 Sodium Chloride 0.32 0.32 0.32 Purified Water QS QS QS pH 7.8 7.8 7.8
The test formulations were evaluated for their prophylaxis behavior using lysozyme as the model protein, as described below.
Preparation of Deposition Solution
[0047] Phosphate Buffered Saline (PBS) 1.311 g of monobasic sodium phosphate (monohydrate), 5.74 g of dibasic sodium phosphate (anhydrous), and 9.0 g of sodium chloride were dissolved in deionized water and the volume was brought to 1000 mL with deionized water, and pH was adjusted (as necessary). The final concentrations of sodium phosphate and sodium chloride were 0.05 M and 0.9%, respectively. The final pH was 7.4.
[0000] Lysozyme Solution
[0048] A 1.5-mg/mL lysozyme solution was prepared by dissolving 750 mg of lysozyme in 500-mL phosphate buffered saline pH adjusted to 7.4.
[0000] Lens Extraction Solution (ACN/TFA)
[0049] A lens extraction solution was prepared by mixing 1.0 ml of trifluoroacetic acid with 500-mL acetonitrile and 500 ml of deionized water. The pH of the solution ranged from 1.5 to 2.0.
[0000] Lens Presoak Procedure
[0050] Each lens was immersed in 3-mL of each test formulation and allowed to sit at room temperature overnight. The next morning, the lenses were removed from the test formulations and dabbed lightly on a towel.
[0000] Lens Deposition Procedure (Physiological Deposition Model)
[0051] Each presoaked lens was immersed in a Wheaton glass sample vial containing 3-mL of lysozyme solution. The vial was closed with a plastic snap cap and incubated in a constant temperature water bath at 37° C. for 24 hours. Three additional lenses were included as controls to establish the total amount of lysozyme deposited. After incubation, the deposited lenses were removed from their vials and rinsed by dipping into three consecutive beakers containing 200 ml Unisol®4 or water to remove any excess of the deposition solution.
[0000] Extraction and Determination of Lysozyme Extraction
[0052] The lenses were extracted with 5 ml of ACN/TFA extraction solution in a screw-capped glass scintillation vial. The extraction was done by shaking the vial with a rotary shaker (Red Rotor) at room temperature for at least 2 hours (usually overnight).
[0000] Calculations for the Determination of Lysozyme
[0053] Quantitative determination of the lysozyme of the lens extract was carried out using a fluorescence spectrophotometer interfaced with an autosampler and a computer. The fluorescence intensity of a 2 ml aliquot from each sample solution was measured by setting the excitation/emission wavelength at 280 nm/346 nm with excitation/emission slits of 2.5 nm/10 nm, respectively, and the sensitivity of the photomultiplier was set at 950 volts.
[0054] A lysozyme standard curve was established by diluting the lysozyme stock solution to concentrations ranging from 0 to 40 μg/ml, using the ACN/TFA extraction solution for the lens extract and the vehicle for the soaking solutions. The instrument settings for measuring the fluorescence intensity were the same for the lens extracts and lens soaking solutions.
[0055] The lysozyme concentrations for all of the samples were calculated based on the slope developed from the linear lysozyme standard curve. The % prophylaxis of each formulation was calculated by subtracting the amount of lysozyme in the lens extract from the amount of lysozyme from the control lenses (total deposit), then dividing that by the total deposit and multiplying by 100.
[0000] Results
[0056] FIG. 1 shows the % prophylaxis as a function of PNIPAM concentration (g/100 ml) for nonionic NIPAM polymers having molecular weights of 46,380; 71,600; and 122,000, respectively.
[0057] FIG. 1 shows that there was no significant PNIPAM molecular weight dependence on the % prophylaxis using the defined polymer concentrations. PNIPAM concentrations up to 0.2 g/100 ml gave % prophylaxis results of approximately 30%. With increasing PNIPAM concentrations above 0.2 g/100 ml the % prophylaxis could be increased to 50% to 60% using polymer concentrations between 0.4 g/100 ml and 0.65 g/100 ml. The % prophylaxis was not dependent on the molecular weight of the NIPAM polymers.
EXAMPLE 2
[0058] The prophylactic properties of NIPAM polymers were further evaluated using a 3-day cycling study. Two sets of lenses were prepared. One set was presoaked in the formulations shown in Table 2 before going into the lysozyme solution, whereas the other set was not. Both sets of lenses were then placed in the lysozyme solution for 8 hours (Day 1). At the end of the day all the lenses were rinsed and put in their respective formulations to soak overnight. The following day (Day 2), the lenses went back into the lysozyme for the day (8 hours). This was repeated to complete 3 cycles (3 Days). At the end of the experiment all the lenses were analyzed in accordance with the procedures described in Example 1. The results are presented in Table 3:
TABLE 3 Uptake of Amount Lysozyme Removed % Sample (ug/lens) sd (ug/lens) Prophylaxis sd 9591- 124.1 9.1 261.9 67.8 0.8 47A(PS) 9591- 151.5 3.9 234.5 60.8 0.6 47B(PS) 9591- 386.0 6.1 — — — 47C(PS) 9591-47A 206.3 2.7 174.9 45.9 1.2 9591-47B 221.3 10.4 159.9 41.9 0.9 9591-47C 381.2 7.1 — — — PS = Presoaked
[0059] The results demonstrate that the buffered solutions containing a NIPAM polymer (i.e., P2991-NIPAM) were effective in reducing protein uptake in both the presoaked and non-presoaked lenses. For example, the presoaked lenses treated with solutions containing concentrations of 0.034% and 0.017% of the NIPAM polymer demonstrated prophylaxis values of 67.8% and 60.8%, respectively. For the non-presoaked lenses the prophylaxis values were 45.9% and 41.9% at concentrations of 0.034% and 0.017%, respectively.
[0060] The results set forth in Table 3 demonstrate that treatment of the lenses with a NIPAM polymer solution prior to exposure to proteins is preferable. However, the results also show that even when the lenses have already been exposed to proteins prior to an initial treatment with a NIPAM polymer solution, the uptake of protein is reduced when the lenses are subsequently treated with a NIPAM polymer solution. Thus, the results of this study confirm that the compositions of the present invention are effective in reducing the formation of protein deposits on contact lenses, even when the lenses are repeatedly exposed to protein contamination.
EXAMPLE 3
[0061] The prophylaxis work was extended to formulations containing the antimicrobial agent AL-8496 with unmodified NIPAM (non-ionic) and modified NIPAM (end functionalized with COOH) polymers. The formulations evaluated are shown in Table 4, below:
TABLE 4 Formulations for Microbiology Evaluation of PNIPAM Formulations Containing A Contact Lens Disinfecting Agent (AL-8496) Formulation Numbers 9591- 9591- 9591- 9591- 9591-44I Component 44B 44C 44D 9591-44E 44F (Control) P2991- 0.087 0.21 NIPAM P2426F2- 0.040 0.10 0.25 NIPAMCOOH AL-8496* 0.0004 0.0004 0.0004 0.0004 0.0004 0.0004 Tetronic ® 0.1 0.1 0.1 0.1 0.1 0.1 1304 Sorbitol 0.4 0.4 0.4 0.4 0.4 0.4 Sodium 0.2 0.2 0.2 0.2 0.2 0.2 borate Sodium 0.6 0.6 0.6 0.6 0.6 0.6 citrate Propylene 1.0 1.0 1.0 1.0 1.0 1.0 glycol Disodium 0.05 0.05 0.05 0.05 0.05 0.05 edetate pH 7.8 7.8 7.8 7.8 7.8 7.8 % 37.4 ± 0.2 54.1 ± 1.0 51.0 ± 0.5 57.3 ± 0.4 62.8 ± 1.2 0.6 ± 0.0 Prophylaxis *As base
[0062] The procedures utilized were the same as in Example 1. FIG. 2 shows the prophylaxis data obtained using the overnight soak model with lenses pre-soaked in the respective PNIPAM formulations.
[0063] FIG. 2 shows that the prophylaxis properties of the NIPAM polymers were retained in the presence of the antimicrobial agent AL-8496 and other formulation components, including cleaning ingredients (e.g., citrate and Tetronic® 1304). The data demonstrate that both unmodified and modified NIPAM polymers can be incorporated into multi-purpose contact lens care formulations without compromising the prophylactic properties of the polymers.
EXAMPLE 4
[0064] The disinfection activity of the formulations shown in Table 4 above was also evaluated. The results are shown in Table 5 below.
TABLE 5 Disinfection Properties of PNIPAM Formulations containing AL-8496 Time 9591- 9591- 9591- 9591- 9591- 9591- Microorganism (hrs) 44B 44C 44D 44E 44F 44I Candida 6 2.8 3.0 3.0 3.4 3.2 3.0 albicans 24 3.9 4.5 6.0 6.0 5.3 6.0 Serratia 6 2.7 6.2 2.8 2.7 2.6 2.6 marcescens 24 5.5 6.2 5.5 6.2 5.5 4.9 Staphylococcus 6 5.5 4.5 5.5 4.4 4.3 4.9 aureus 24 6.2 5.0 6.2 6.2 6.2 5.2
[0065] The results demonstrate that the NIPAM polymers did not adversely affect the antimicrobial activity of the antimicrobial agent AL-8496.
EXAMPLE 5
[0066] Several formulations were evaluated to compare the prophylaxis properties of PNIPAM with two well-known block co-polymers, Tetronic® 1107 and Pluronic® F127. The formulation components and prophylaxis results are given in Table 6, below.
[0067] The evaluation was carried out using the same procedures as outlined in Example 1. The buffered solution utilized as a control (10581-85J) did not exhibit any prophylaxis properties. However, as shown in Table 6, the compositions of the present invention containing PNIPAM at concentrations of 0.2% (10581-85B) and 0.4% (10581-85C) produced prophylaxis results of 56.2% and 63%, respectively.
[0068] In contrast, the solutions containing Tetronic® 1107 and Pluronic® F127 block co-polymers at concentrations of up to 0.8% did not produce any significant prophylaxis.
TABLE 6 10581- 10581- 10581- 10581- 10581- 10581- 10581- Components 85B 85C 85E 85F 85H 85I 85J PNIPAM P2991 0.2 0.4 — — — — — Tetronic ® 1107 — — 0.4 0.8 — — — Pluronic ® F127 — — — — 0.4 0.8 — Sorbitol 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Boric Acid 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Sodium Chloride 0.32 0.32 0.32 0.32 0.32 0.32 0.32 Purified Water QS QS QS QS QS QS QS pH 7.8 7.8 7.8 7.8 7.8 7.8 7.8 % Prophylaxis 56.2 + 0.1 63.0 + 0.4 0.00 + 2.3 4.1 + 2.2 0.0 + 2.1 0.0 + 0.9 0.8 + 1.0 | 4y
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a reciprocating piston internal combustion engine including separate crankshaft end sections to which reciprocating pistons of the engine are connected by connecting rods. The crankshaft end sections are each drivingly connected to a countershaft through a releasable indexing drive connection and the countershaft is in turn drivingly connected to the cam shaft of the engine.
Prior patents disclosing similar structures are classified in Class 123, subclasses 52 A, 58 AB, 198 F and DIG. 7.
2. Description of Related Art
Examples of previously known structures including some of the general structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 861,205, 4,069,839, 4,389,985, 4,394,854 and 4,399,784.
However, the structures disclosed in the above-mentioned patents do not utilize the combination of structural features incorporated in the instant invention to provide a reciprocating piston internal combustion engine which may be conveniently operated on either of two different sets of cylinders in the improved manner disclosed.
SUMMARY OF THE INVENTION
The engine of the instant invention incorporates a pair of crankshaft end sections each having a pair of reciprocal pistons of a four cylinder engine drivingly connected thereto by the utilization of conventional connecting rods and the remote ends of the crankshaft sections are drivingly connected to a countershaft through the utilization of drive means each incorporating a releasable indexing drive connection and a releasable clutch assembly. The countershaft is in turn drivingly connected to the cam shaft of the engine for actuation of the intake and exhaust valves thereof.
The main object of this invention is to provide a multicylinder reciprocating piston internal combustion engine which may be operated on all cylinders of the engine or on either half the number of cylinders of the engine.
Another important object of the invention is to provide a combustion engine constructed in a manner whereby either half of the cylinders of the engine may be deactivated insofar as producing power while allowing only the other half of the cylinders of the engine to produce power.
A still further object of this invention is to provide a combustion engine in accordance with the preceding objects and constructed in a manner whereby the pistons in the deactivated cylinders of the engine are maintained stationary.
A final object of this invention is to be specifically enumerated herein is to provide a combustion engine in accordance with the preceding objects and which will conform to conventional forms of manufacture, be of simple construction and dependable in operation so as to provide a device that will be economically feasible, long lasting and relatively trouble free.
These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, where like numerals refer to like parts throughout.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partially schematic side elevational view of a combustion engine constructed in accordance with the present invention;
FIG. 2 is a front elevational view of the engine as seen from the left side of FIG. 1;
FIG. 3 is an enlarged fragmentary longitudinal vertical sectional view taken substantially upon the plane indicated by the section line 3--3 of FIG. 2;
FIG. 4 is a fragmentary enlarged transverse vertical sectional view taken substantially upon the plane indicated by the section line 4--4 of FIG. 3;
FIG. 5 is a fragmentary enlarged perspective view illustrating a portion of one of the indexing structures of the two drive connections between the countershaft of the engine and the corresponding crankshaft end;
FIG. 6 is a schematic view illustrating a modified form of drive connection between the engine crankshaft, the engine counter shaft and the engine cam shaft; and
FIG. 7 is a schematic view illustrating a third form of drive connection between the engine crankshaft, the engine countershaft and the engine cam shaft.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now more specifically to the drawings, the numeral 10 generally designates a reciprocating piston internal combustion engine including a block 12 defining four piston bores or cylinders 14 closed at their upper ends by a cylinder head 16 journalling a cam shaft 18 therefrom. The head 16 includes intake and exhaust valves 20 and 22 of the spring closed poppet type with which lobes 24 and 26 of the cam shaft 18 are operatively engaged for opening the valves 20 and 22. Of course, the intake and exhaust valves control the flow of intake and exhaust gases into and from the cylinders 14 through corresponding intake and exhaust passages (not shown) formed in the head 16.
The block 12 journals crankshaft structure referred to in general by the reference numeral 27 from the lower end thereof and the crankshaft structure 27 includes a pair of opposite end crankshaft sections 28 and 30 independently rotatable relative to the block 12. The lower end of the block is closed by the usual pan 32 and the engine further journals a countershaft 34 therefrom. The forward end of the countershaft 34 has a toothed pulley 36 mounted thereon and the forward end of the cam shaft 18 has a toothed pulley 38 mounted thereon whose circumference is twice the circumference of the pulley 36. An endless flexible toothed belt (or chain) 40 drivingly connects the pulley 36 to the pulley 38.
Front and rear driven gears 42 and 44 are journalled from the block 12 by bearings 46 and 48 and the front and rear ends of the front and rear crankshaft sections 28 and 30 include gear wheels 50 and 52 mounted thereon meshed with the gears 42 and 44. The gears 44 rotatably receive the opposite ends of the countershaft 34 therethrough and the gears 42 and 44 include clutch assemblies 54 and 56 which are remotely operable and of any suitable type. The clutch assemblies 54 and 56 may be actuated to clutch or drivingly connect the gears 42 and 44 to the shaft 34 or deactuated to allow relative rotation between the gears 42 and 44 and the shaft 34.
The cylinder portions 58 and 60 of a pair of double acting hydraulic cylinders 62 and 64 are stationarily mounted from the block 12 and include piston sleeves 66 and 68 extending therethrough equipped with piston portions 70 and 72 as well as spool portions 74 and 76. The cylinder portions 58 and 60 include seals 78 establishing fluid-tight seals between the cylinder portions 58 and 60 and the piston sleeves 66 and 68 and the shaft 34 is rotatably received through the piston sleeves 66 and 68 and has opposite end splines 80 and 82 thereon.
As may best be seen from FIG. 3, the gears 42 and 44 include inner end recesses which are provided with inner gear teeth as at 84 and 86 and the gears 42 and 44 are splined to the shaft 34 as at 88 and 90.
A pair of slide gears 92 and 94 are internally splined and slidably engaged with the splines 80 and 82 on the shaft 34. The slide gears are connected to the piston sleeves 66 and 68 through thrust bearings 96 and 98 and are axially displaceable into meshed engagement with the gear teeth 84 and 86. In addition, the inner ends of the gears 42 and 44 include ramp surfaces 100 and 102 and the gears 42 and 44 include outer keyways 104 and 106 which open outwardly through the ramp surfaces 100 and 102 and in which key lugs 108 and 110 carried by the gears 42 and 44 are receivable.
Combined fluid pressure inlet and fluid pressure return lines 112 and 114 open into opposite ends of each of the cylinder portions 58 and 60 and a fluid pressure bleed line 116 opens outwardly of each cylinder portion 58. The lines 112, 114 and 116 extend to any suitable source of hydraulic fluid under pressure and an associated hydraulic fluid reservoir (not shown). In addition, the clutch assemblies 54 and 56 may be of any suitable type that may be remotely actuated.
In operation, and assuming the previously described moving parts of the engine 10 are as illustrated in FIG. 3 of the drawings, the engine 10 is being operated only by the two rear cylinders or bores 14 and the pistons 118 disposed therein are connected to the rear crankshaft section 30 by connecting rods 120. Each front and rear pair of cylinders or bores 14 is provided with its own air and fuel induction system (not shown) and its own exhaust gas system (not shown).
When it is desired to operate the engine 10 by all four cylinders or bores 14, the valves 20 and 22 for the front cylinders are held open by remotely operable hydraulic thrusters 124, see FIG. 2, operatively associated therewith. The front clutch assembly 54 is actuated to cause the front gear 42 to rotate at the same speed as the counter shaft 34. Then, the hydraulic cylinder 62 is actuated by admitting fluid under pressure into the cylinder portion 58 through line 114. The piston 70 moves to the left as viewed in FIG. 3 and thereby causes the key lug 108 to engage the ramp surface 110. As the key lug 108 engage the ramp surface 110 excess fluid pressure is bled off by bleed line 116 and the clutch assembly 54 is released to allow key 108 to align with keyway 104. As the key 108 enters keyway 104 bleed line 116 is covered by spool portion 74 and full fluid pressure is available to cause final movement of the piston portion 70 to the left and full meshed engagement of the gear 94 with the gear teeth 84. Then, fluid pressure to the cylinder portion 58 and the thrusters 124 is relieved and the fuel injectors for the front cylinders 14 may be actuated. The engine 10 may be provided with a mini computer (not shown) for proper timed sequential control over fluid pressure to the cylinder portions 58 and 60, the clutch assemblies 54 and 56, the thrusters 124 and the fuel injection (if provided) for the front and rear cylinders.
If it is then desired to disable one pair of the cylinders or bores 14, either clutch assembly 54 and 56 may be engaged and the corresponding cylinder 62 and 64 may be actuated to withdraw the corresponding slide gear 92 or 94 from engagement with the associated gear 42 or 44.
With attention now invited more specifically to FIG. 6 of the drawings, it may be seen that the remote ends of the crankshaft sections 28 and 30 may be drivingly coupled to the corresponding ends of the countershaft 34 at a 2:1 ratio through the utilization of an endless flexible belt 128 and that the forward end of the countershaft 34 may be drivingly connected to the forward end of the cam shaft 18 by an endless flexible belt 130 at a ratio of 1:1.
On the other hand, with attention now invited more specifically to FIG. 7, the remote ends of the crankshaft sections 28 and 32 may be drivingly connected to the opposite ends of the countershaft 34 through the utilization of small and large gear wheels 132 and 134 mounted thereon at a 2:1 ratio and the forward end of the countershaft 34 may be drivingly connected to the forward end of the cam shaft 18 by an endless flexible belt 136 at a 1:1 ratio.
From FIG. 4 of the drawings, it may be seen that the ramp surface 100 extends approximately 90° about the corresponding gear. However, the ramp surface could extend 180°, 270° or substantially 360° about the gear.
Also, it is important to note that the path of power transmission from each crankshaft section to the countershaft 34 is first through the corresponding clutch and then through the corresponding sliding gear which is in fixed angular displacement relative to the countershaft 34 and that the camshaft 18 is constantly driven from the countershaft 34. Accordingly, the camshaft is maintained in proper "time" with the crankshaft.
The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. | 4y
|
BACKGROUND OF THE INVENTION
The invention relates to a method of producing amorphous carbon coatings on substrates by the degradation of a gaseous carbon compound in an ionized gaseous atmosphere within a reaction chamber, using an alternating electromagnetic field to excite the plasma.
The term "amorphous" applied to carbon coatings originates from initial studies indicating a largely amorphous structure. In the meantime, later studies have proven that a typical diamantine bond is also present within small areas. The term is, therefore, one of art and not rigor.
At the present time, the following is known concerning the basic conditions under which an amorphous carbon coating can be produced: the energy of the carbon ions or hydrocarbon radicals impinging upon the substrate must exceed a certain threshold value; approximately 30 atomic percent of hydrogen can be incorporated in the coating, and, depending on the conditions of formation, different sub-nomenclatures have become established in the art for the coatings, viz:
amorphous carbon
i-carbon (i represents "ion assisted")
a-C:H (hydrogenated amorphous carbon)
diamond-like carbon.
The amorphous carbon coatings have great hardness. They are chemically inert and permeable to infrared radiation, so that there is a considerable demand for such coatings as mechanical and chemical protective coatings on a wide variety of substrates in common use, and as an optically active coating on special optical substrates permeable to infrared radiation.
German Offenlegungsschrift No. 1,736,514 and the corresponding British Pat. No. 1,582,231 discloses a process for coating a substrate with amorphous carbon in a reaction chamber in which the substrate with the substrate holder forms one plate of a capacitor to which an electrical frequency of between 0.5 and 100 MHz is applied to produce a coating plasma from a monomer gas in the reaction chamber. The other plate of the capacitor can be the floor of the reaction chamber, but it can also be formed by a second plate in the reaction chamber. In either case, both plates are in the reaction chamber and consequently also exposed to the ionized gaseous atmosphere, and this would have to be the case in any event with the plate which forms the substrate holder. Contamination of the coating with the plate material can result.
Experience has shown, moreover, that the known method and apparatus can only achieve rates of carbon deposition of between 1.0 and 3.0 nm/sec. It is also difficult to obtain sufficient uniformity of coating thickness, because variations in the coating thickness can be caused by an irregular energy input into the plasma, and differences in monomer concentration near the substrate. This is further complicated by the fact that gaseous reaction products are formed as the coating builds up, which must be continuously pumped out. By the presently known method, in the case of planar substrates of a diameter of only 20 cm, thickness irregularities of approximately 5% are achieved over the entire area. Evidently this is true of no more than laboratory-scale production, which is not easily, if at all, transferrable to large technical processes.
It is therefore an object of the invention to provide a method of the kind described above, whereby the rates of deposition can be considerably increased and substrates of large area can be uniformly coated.
SUMMARY OF THE INVENTION
In accordance with the invention, a method of producing an amorphous carbon coating on a substrate within a reaction chamber comprises introducing a gaseous hydrocarbon compound within the reaction chamber and applying by at least one ladder-like wave guide an electromagnetic alternating field having a frequency in the microwave region to ionize the gaseous hydrocarbon compound to produce an amorphous carbon coating on the substrate.
Also in accordance with the invention, a substrate has an amorphous carbon coating and has between the substrate and the amorphous carbon coating an adhesion-mediating coating of a polymer selected from the group of siloxanes and silazanes.
The above-stated object is achieved in accordance with the invention, in the method described above, by selecting the frequency of the alternating electromagnetic field in the microwave region, and by delivering the microwave energy to the gaseous atmosphere by means of at least one ladder-like wave-guide structure situated outside of the reaction chamber.
The microwave region lies in a frequency range extending from about 915 to 2,540 MHz, i.e., the frequency is higher by at least a factor of about 10 than the frequency used in the state of the art. By the increase of the frequency, in conjunction with a corresponding output power increase, a deposition rate greater by at least a factor of 7 is achieved, i.e., by the method of the invention, deposition rates of about 20 nm/sec can be achieved easily. By situating the energy source for the excitation of the gas plasma, i.e., the ladder-like waveguide structure, outside of the reaction chamber and thus outside of the gaseous atmosphere, the energy input can be considerably increased without incurring problems that cannot be controlled electrically and thermally. The ladder-like waveguide, which of itself belongs to the state of the art, permits a uniform energy input over its entire length, so that the uniformity of the coating thickness, in conjunction with a relative movement of the substrate with respect to the waveguide structure, can be substantially improved. Even if the area of the substrate is increased, coatings can be produced in which the differences in thickness amount to less than about 3 to 4%.
Despite the high rates of deposition, the coatings achieved are extraordinarily hard, and have a high chemical stability, so that they can be used preferentially as protective coatings for a great number of substrates.
Suitable carbon compounds either in gaseous form or in a form which can be converted to the gaseous state are acetylene, benzene, methane, and other hydrocarbons in chain or cyclic form, preferably those which have multiple bonds.
While the method described above results in adequate strength of adhesion to special substrate materials such as germanium, in the case of mineral glass, metals, plastics and inorganic insulating material, the strength of adhesion can be further improved in the following manner:
(a) In an initial step in the method, a gas from the group of the siloxanes or silazanes is introduced into the reaction chamber.
(b) A ground coating of a polymer of the siloxanes or silazanes is formed on the substrates.
(c) Then the gaseous hydrocarbon compound is introduced into the reaction chamber.
(d) The amorphous carbon coating is formed on the ground coat.
The polymers formed of siloxane and/or silazane have proven to be excellent adhesion mediators, with respect to both the substrate material and the amorphous carbon coating. With regard to the strength of adhesion between the siloxane or silazane layer and the amorphous carbon coating, the following is also important: The reaction chamber, even in the case of a deliberate interruption of the siloxane or silazane feed, contains a certain amount of this gas, which gradually is consumed by condensation on the substrate surface. If, while sustaining a pressure-controlled gas supply, the gaseous hydrocarbon is introduced after the delivery of siloxane or silazane has ended, the silazane or siloxane concentration decreases approximately simultaneously while the concentration of the hydrocarbon compound is increasing. This procedure results in a gradual transition from one coating material to the other, which can be interpreted as a kind of interlocking between the coating materials. This method can be further improved by gradually throttling the delivery of the first reaction gas (siloxane, silazane) and gradually increasing the rate of delivery of the hydrocarbon compound to the rate required for stationary operation, thereby widening the zone of transition, thus still further increasing the adhesion effect.
It is furthermore possible to increase the hardness of the adhesion-mediating coating substantially by delivering the gases from the group of the siloxanes or silazanes to the reaction chamber in a mixture with an oxygen-containing gas or pure oxygen, the content of the oxygen-containing gas or oxygen being selected between 10 and 50%, by volume, of the total amount of gas. It is always advantageous to give the adhesion-mediating coating great hardness, even though it be very thin, in order to further improve the durability of the amorphous carbon coating, which in itself is very hard.
The invention also relates to a substrate provided with an amorphous carbon coating, in which an adhesion-mediating coating consisting of a polymer from the group of the siloxanes or silazanes is interposed between the substrate and the amorphous carbon coating.
Additional advantageous developments of the subject matter of the invention will be seen in the subordinate claims.
For a better understanding of the present invention, together with other and further objects thereof, reference is made to the following description, taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.
An embodiment of the subject matter of the invention and an apparatus for the performance of the method of the invention will be now be described, in conjunction with FIGS. 1 to 4.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 represents a cross section taken through a coated substrate,
FIG. 2 is a simplified perspective representation of an apparatus for the performance of the method of the invention.
FIG. 3 is a cross section of apparatus similar to that of FIG. 2, but in substantially greater detail, namely through a window supporting frame having two windows and ladder-like waveguides disposed in front of each window.
FIG. 4 is a vertical cross section through a reaction chamber set up vertically, in which the substrate holder and its drive are suspended vertically.
DESCRIPTION OF PREFERRED EMBODIMENTS
In FIG. 1 a substrate S consisting of mineral glass is represented, on which an adhesion-mediating coating H composed of a polymer of a siloxane or silazane is provided, on which, in turn, there is applied an amorphous carbon layer C in accordance with the invention. Between the two layers is a zone of transition or mixture M, which extends between two boundary surfaces represented in broken lines. At the bottom boundary surface the composition amounts to 100% of the polymer of the siloxane or silazane, while the composition at the upper boundary surface amounts to 100% of the amorphous carbon coating. Between these two boundary surfaces, the transition from the one to the other of the two coating materials is virtually continuous.
In FIG. 2 there is represented a reaction chamber 1 in which a substrate 2 of planar form is disposed on a planar substrate holder 3. The substrate 2 is transportable through the reaction chamber 1 in the direction of the arrow 4 by the substrate holder.
The substrate holder 3 can be transported between a supply magazine, which is not shown, and a receiving magazine, which also is not shown, the magazines being disposed one at each end of the reaction chamber 1. However, loading locks can also be provided at the two ends of the reaction chamber.
These principles of the construction of reaction chambers and locks or pressure stages, however, are the state of the art, so that there is no need to go further into the discussion thereof.
The reaction chamber 1 made of metal is provided with a window 5 of a material permeable to microwaves, such as vitreous fused silica or aluminum oxide ceramic, polytetrafluorethylene etc. The window is rectangular in plan, the length amounting to at least the width of the substrate 2 or of the substrate holder 3 transversely of the transport direction (arrow 4).
Above the window 5, two ladder waveguides 6 and 7 are disposed, each consisting, in accordance with FIG. 3, of two parallel straight rods 8 and 9 having between them crossbars 10 and 11 of equal length which are in metal-to-metal contact with the rods 8 and 9.
The crossbars 10 and 11 are alternately connected electrically to one of two central conductors which have been omitted for the sake of simplicity. The configuration and arrangement of such ladder waveguides are set forth in detail in U.S. Pat. No. 3,814,983, especially in FIGS. 4 to 8.
In accordance with FIG. 2, the first ladder waveguide is connected by a waveguide 8a to a microwave transmitter, the connection being indicated only diagrammatically by a broken line. The microwave generator of the microwave transmitter 9a preferably is a magnetron. The coupling of the ladder waveguide 6 to the hollow waveguide 8a is likewise state of the art and represented by way of example in U.S. Pat. No. 3,814,983, FIGS. 4 and 5. The far end of the ladder waveguide 6 is connected by another hollow waveguide 10a to a so-called dummy load 11 constituting a microwave short circuit. The ladder waveguide 6 runs at an acute angle to the window 5 and to the substrate carrier 3, the greatest distance being at the end at which the hollow waveguide 8a is located. The angle can be varied by displacing the hollow waveguide 8a in the directions indicated by the double arrow represented on the left side thereof. The angle is selected such that a uniform energy input into the plasma is produced over the length of the ladder waveguide, assuming constant discharge parameters.
The ladder waveguide 7, which preferably is also disposed lengthwise normal to the direction of transport of the substrate, is disposed alongside the ladder waveguide 6; however, it slopes in the opposite direction and forms the same acute angle with the substrate surface. The end of the ladder waveguide 7 that is farthest away from the substrate surface is also connected by a hollow waveguide 12 to the same microwave transmitter 9, in an entirely similar manner. The far end of the ladder waveguide is, again in an entirely similar manner, connected by another hollow waveguide 13 to another dummy load 14. All of the hollow waveguides 8a, 10a, 12 and 13 are disposed for longitudinal displacement in the direction of the double arrows for the purpose of a precise alignment of the ladder waveguides 6 and 7 relative to the substrate surface. A fine adjustment of the coating thickness distribution can additionally be achieved by adjusting the power distribution on the two ladder waveguides.
The plasma is formed within the reaction chamber which contains the reactive gases, such as siloxane or silazane for the adhesion-mediating coat and/or a gaseous hydrocarbon for the formation of the amorphous carbon coating. Oxygen or an oxygen-containing gas such as water vapor can additionally be introduced into the reaction chamber 1.
By means of the ladder waveguides 6 and 7, two elongated, plasma-filled spaces are formed beneath the window 5, through which the substrates run successively. It is apparent that the ladder waveguides 6 and 7 together with the terminally disposed waveguides, in their projection onto the window 5, lie within the open cross section of the latter. Those waveguides 8a and 12 through which the injection of power into the plasma is performed, lie at opposite ends of the substrate carrier, as seen transversely of the transport direction indicated by arrow 4.
Additional details of such an apparatus are disclosed in German Offenlegungsschrift No. 3,147,986.
FIG. 3 shows further details of a window 5a, which is a variant of the window 5 of FIG. 2. The reaction chamber 1a has several chamber walls, including a front wall 15 in which a supporting frame 16 is releasably fastened, in front of which there is a microwave shield 17 in the form of an oblong casing. In front of this casing, microwave transmitters and dummy loads are disposed in an out-of-parallel arrangement similar to FIG. 2, but they are not shown here.
The supporting frame 16 is of rectangular construction and is provided with two window openings 19 and 20 running parallel to the longer sides of the rectangle. Between the window openings is a frame member 21 running in the direction of the longest axis of symmetry of the supporting frame 16. A window 22 and 23, for example, of vitreous fused silica transparent to microwaves is situated in each of the window openings 19 and 20. The central frame member 21 has, along its longest axis, a means 25 for the distribution of the reaction gases referred to above, which in the present case consists of a plurality of openings 26 leading into the interior of the reaction chamber. The openings 26 are perpendicular to a longitudinal bore 27 in the central frame member 21, which in turn is connected, in a manner not shown, to a conduit delivering the gases from which a surface coating is to be formed on the substrate by the plasma reaction. A solid spreader plate 28 runs parallel to the longitudinal bore 27 opposite all of the openings, and its parallel longitudinal margins are slightly bent, as indicated, toward the central frame member 21, so that between the central frame member 21 and the spreader 28 two gas discharge gaps 29 and 30 are formed, which extend over the entire length of the central frame member. If a substrate is moved parallel to the windows 22 and 23 in a direction perpendicular to the long axis of the central frame member 21, the entire width of the substrate will be swept with a uniform stream of the reaction gases. Under the effect of the glow discharges burning in back of the windows 22 and 23, the desired coating forms on the surface of the substrate.
As seen in FIG. 3, cooling passages 31 are provided in the supporting frame 26 including the central frame member 21, through which cooling water flows during operation and which keep the overall temperature level of the supporting frame 16 low.
FIG. 3 also indicates, between the ladder waveguides 6a and 7a and the window openings 19 and 20, the adjusting shutters 32 and 33 whereby the distribution of the energy input into the reaction chamber longitudinally of the window openings 19 and 20 can be controlled. The adjusting shutters are fastened at both their extremities to adjusting spindles 34 which permit an adjustment of the position of the shutters 32 and 33 parallel to the plane of the windows.
As shown in FIG. 3, the ladder waveguides 6a and 7a are surrounded on the side opposite the windows 22 and 23 by a common microwave shielding 36 in the form of a rectangular metal box that is open on the window side. The waveguides corresponding to waveguides 8a, 10a, 12 and 13 of FIG. 2 are fastened to the microwave shielding by means of the supports 37, so that the result is a fixed spatial relationship of the waveguides and of the waveguide ladders 6a and 7a connected to the waveguides. The microwave transmitters and dummy loads are connected by means of terminal flanges 38. The microwave shield 36 has a back wall 36a through which the waveguides 18 are brought. Two reflectors 39 and 40, which are in the form of partially cylindrical troughs facing the waveguide ladders 6 and 7 and window openings 19 and 20, are disposed parallel to the back wall 36a. By virtue of these reflectors a substantially greater portion of the microwave power enters into the interior of the reaction chamber 1.
In FIG. 4, only the supporting frame corresponding to frame 26 and one of the two windows corresponding to windows 22 shown in FIG. 3 are represented. All of the rest of the parts of the apparatus situated outside of the reaction chamber 1a in FIG. 3 have been omitted for the sake of simplicity.
In FIG. 4 there is shown a vertical cross section through a vertically disposed reaction chamber 1b in the area of the supporting frame 16a and a window 22a transparent to microwaves, the direction of transport of the substrate holder 3a being perpendicular to the plane of the drawing. The substrate holder 3a is a planar plate suspended vertically, which is aligned parallel with the window. The substrate holder 3a is suspended by means of a bracket 51 from the upper run of an endless chain forming part of a transport system 37. The chain is passed around two sprockets, one in front of and the other behind the plane of the drawing. Two channel-shaped guides 38 and 39 made of a plastic that has low friction under the process conditions provide for the support of each run of the chain. The sprocket 40 situated in back of the plane of the section is mounted in a bearing 41 and is connected by an angle gear drive 42 and reduction gearing 43 to a drive motor 44. The sprockets 40, together with their bearing 41 plus the guides 38 and 39, are fastened to a supporting frame 45 which extends through the entire length of the reaction chamber 1. By means of the transport system it is possible to move the substrate holders 3a back and forth in the direction of the longest axis of the reaction chamber 1. The assembly represented in FIG. 4 is to be considered as being attached to the front wall 15a and to the supporting frame 16a.
In FIG. 4 it can also be seen that supports 53 bearing a continuous guide rail 54 are affixed to the floor 52 of the reaction chamber 1a. The substrate holder 3a engages this rail with a roller 55 to prevent the substrate holder from rocking or being deflected laterally. The reaction chamber la is reinforced by braces 60, 61 and 62 to withstand the low operating pressure. The substrate holder 3a can hold the substrate in position by any suitable means, for example, clamps (not shown).
EXAMPLES
Example 1
In an apparatus in accordance with FIGS. 3 and 4, a glass substrate measuring 0.4×0.4 meter was placed in the reaction chamber on an uncooled substrate holder. After the vessel had been evacuated to a pressure of less than 10 -4 mbar, hexamethyldisiloxane was let in and the feed thereof adjusted such that a constant pressure of 1×10 -2 mbar established itself. With an input power of 2 kW at 1.45 GHz in both ladders, a pressure of 4×10 -2 mbar established itself immediately after the ignition of the plasma. After two seconds the hexamethyldisiloxane feed was interrupted and replaced by acetylene while sustaining the operating pressure. After a stay of 50 sec in the plasma, the total thickness of the combined coatings was 1 micron, which corresponds to an average rate of deposition of 20 nm/s. The coating thickness variation over the entire surface of the substrate amounted to ±4%.
In the examination of the coating the following findings were made: the coating, with an index of refraction of 1.8, has a transmission in the infrared range averaging 95%. Also, in the infrared spectrum there were no indications of multiple carbon bonds. The coating is very hard (VH 5000 kg/mm 2 ) and has a substantially greater strength of adhesion than coatings with no adhesion mediator.
Example 2
In a second experiment, under otherwise identical conditions, benzene was used instead of acetylene. The coating that formed had the same properties as in Example 1.
While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention. | 4y
|
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of scanning probe microscopy and more particularly to a novel scanning force or atomic force microscope having a stationary sample stage and a beam tracking lens which may utilize an S-shaped piezoceramic scanner to provide relative motion between the probe tip of the atomic force microscope and the surface of the sample being scanned.
2. The Prior Art
The atomic force microscope ("AFM") belongs to a family of devices known as scanning probe microscopes ("SPMs"). These devices all use a probe with a sharp tip to scan a surface and measure the surface features such as topography as a function of probe-surface interaction at the location of the probe, generally yielding a two-dimensional array of data. SPMs comprise a number of different systems for measuring various types of probe-surface interactions. The first device of this family was the Scanning Tunneling Microscope ("STM") which is described in U.S. Pat. No. 4,724,318 to Binnig et al. The second device of the family is the AFM which this invention is directed to. Since the invention of the STM and the AFM, scanning probe microscopy has found applications in many areas of science and engineering due to its simplicity and high resolution at atomic dimensions.
AFMs typically employ a fine flexible cantilever with a small spring constant (in the range of 10 -1 to 10 -3 N/m) and a sharp probe tip disposed at the free end of the cantilever. The bending of the cantilever in an AFM is related to the atomic force exerted on the tip (in the range of 10 -8 to 10 -13 N) by the local topography of the sample surface. For measurement of the force, the optical beam deflection method, also known as the optical lever method (or "OLM") is frequently used. Pursuant to the OLM, a laser such as a diode laser is positioned so that its laser beam intersects the reflective side or back of the cantilever which is away from the surface of the sample being scanned ("sample surface"). The angle of reflection of the laser beam reflected off of the reflective back of the cantilever is sensed at a distance by a position sensitive photodetector device such as a bi-cell photodetector. The measured angle of reflection of the laser beam from the cantilever is thus related to the topography of the sample surface. Most AFM systems are designed to move the sample surface relative to a stationary probe tip (see, e.g., Binnig et al., Phys. Rev. Lett., 1982, 49, pp. 57-60; Phys. Rev. Lett., 1986, 56, pp. 930-933; Jahnamir et al., Scanning Microscopy, 1992, 6, pp. 625-660) in order to maintain the probe's optical alignment with respect to a stationary laser emitter. Thus, the sample is mounted at the end of a voltage controlled scanner made of a piezoceramic tube (also known as a "PZT"). The characteristics of the PZT and the range of the applied voltages determine the size of the scanned area as well as the resolution of the image of the sample surface. By using various different scanners having different PZTs, areas as small as several square nanometers, or as large as tens of thousands of square micrometers, can be characterized by the AFM.
In AFMs according to most of the prior art, the sample must be attached to the scanner. Such prior art AFMs operate with a stationary probe and moving sample as described above. The sample can be disturbed during operation of such prior art AFMs because the sample must be moved in order to scan an area of the sample surface. According to such prior art, it is also necessary to disturb the sample every time that the scanning range or scanning method (e.g., probe) is changed, because to accomplish such changes, disassembly and reassembly of all or part of the AFM system is required. This process often requires detaching the sample from its mount, adjusting the AFM, and then remounting the sample. Such requirements restrict the size and weight of the sample to be scanned. Prior art AFMs also often require that the detecting optics (e.g., the bi-cell photodetector) be moved during the scanning process. (See, e.g., Jahnamir et al., Supra). All of these changes and movements required by the prior art devices can affect both the sample and the measurement of its surface properties, limit the quality of the data obtained, and make different measurements of the same sample difficult or inconsistent. Disturbing the sample when changing scanners or scanning modes (e.g., STM, AFM), besides being time consuming, may interfere with the measurement(s) being made. This is usually true when working with adsorbates, or when working in situ in a liquid cell. Imaging under solution in a liquid cell can be performed both with and without electrochemical control. The significance and the application of working under electrochemical control is described and patented by S. Lindsay in U.S. Pat. No. 5,155,361. When working under electrochemical control, disconnecting the sample from the applied voltages for changing scanners or scanning modes can cause severe and irreversible changes to the sample surface.
SUMMARY OF THE INVENTION
According to the present invention the sample need not be disturbed in order to change either the scanners (scanning heads) or the scanning modes. Rather, it is the scanner with beam tracking lens that moves instead of the sample when various areas of the sample surface are to be scanned. Preferably the present invention may comprise one microscope with several interchangeable scanning heads. Tracking and focusing of the laser beam eliminate most errors due to beam deflection and enables AFM imaging of large areas (in the micrometer range) without losing resolution. Preferably the present invention may enable solution/electrochemical imaging of a surface or surfaces emersed in a liquid without moving the sample and disturbing the equilibrium of the sample in solution and may preferably include a stationary sample stage, a beam tracking lens and an S-shaped scanner.
OBJECTS AND ADVANTAGES OF THE INVENTION
Accordingly, it is an object of the present invention to provide a stationary stage atomic force microscope and method of operating same with the ability to map out the topography of a stationary sample substrate in the nanometer to micrometer range using an optical lever method deflection detection system with an S-shaped scanner while allowing for the easy changing of scanning modes and scanning heads without disturbing the sample.
Another object of the present invention is to provide new and improved means and method for carrying out scanning probe microscopy in which the moving probe is implemented using a simple beam tracking lens to guide the laser beam automatically with the moving probe in air or in solution where the sample is stationary and scanner heads and scanning modes can be changed without removing the sample or disassembly or reassembly of the microscope.
It is another object of the present invention to provide a unique stationary sample stage Scanning Probe Microscope with beam tracking lens using an optical lever method with a stationary sample and several interchangeable scanning heads to analyze samples with several scanning modes (including but not limited to: Scanning Tunneling and Atomic Force microscopies) and a wide range of scanning areas (from a few square nanometers to thousands of micrometers square) without requiring the removal of the sample and/or the disassembly and reassembly of the microscope and/or, in a liquid cell, the disassembly and reassembly of the liquid cell.
It is another object of the present invention to improve upon existing means of making AFM measurements.
Yet another object of the present invention is to provide a significant improvement over past SPM technology by providing for high, medium and low resolution imaging of surfaces in both air and solution without disturbing the test sample surface.
Another object of the present invention is to provide a novel design of a device embodying optical lever methodology for atomic force microscopy where the sample is stationary and the cantilever is moved during scanning. More particularly, it is an object of the present invention to provide a stable microscope which allows scanners to be changed without either removing the sample or disassembling and reassembling the microscope.
Another object of the present invention is to provide an atomic force microscope having an increased scanning range which is not limited by the size of the reflective surface on the back of the cantilever.
Another object of the present invention is to provide improved means and method for carrying out atomic force microscopy which achieve improved image quality for all scanning areas including large areas previously believed unattainable in prior devices having no beam tracking lens.
Yet another object of the present invention is to provide a novel and unique atomic force microscope which is capable of suffering substantially no errors as a result of beam deflection.
A further object of the present invention is to provide a novel and unique atomic force microscope having as S-shaped scanner which adjusts for tilt and thereby provides enhanced images at both low and high resolution.
These and many other objects and advantages of the present invention will become apparent to those of ordinary skill in the art from a consideration of the drawings and ensuing description of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of an atomic force microscope according to the present invention.
FIG. 2 is an isometric view of the atomic force microscope of FIG. 1.
FIG. 3 is a front view of an S-shaped scanner according to the present invention showing the application of scanning voltages thereto.
FIG. 4 is a rear view of the S-shaped scanner of FIG. 3.
FIG. 5 is a schematic diagram of an S-shaped scanner according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Those of ordinary skill in the art will realize that the following description of the present invention is illustrative only and is not intended to be in any way limiting. Other embodiments of the invention will readily suggest themselves to such skilled persons from an examination of the within disclosure.
The atomic force microscope of the present invention is identified by the reference numeral 10 in FIG. 2. Microscope 10 comprises a base member 11 having a plurality of leveling screws 12 depending therefrom and supporting a flat pedestal 13 thereupon. Pedestal 13 has a U-shaped opening 14 defined in the middle thereof. Microscope 10 further comprises a vertical support member 15 with which a horizontal support mount 16 is integrally formed to extend outwardly therefrom. A laser adjustment attachment 18, a PZT tube scanner 19, and the detector position adjustment attachment 20 are mounted on support mount 16 as hereinafter described in detail. U-shaped opening 14 provides space in which to position sample stage 21 in operative relationship to PZT tube scanner 19. Base member 11 preferably functions as a motorized translation stage to enable the height and the tilt of pedestal 13 to be adjusted as needed.
One end of the PZT tube scanner 19 is attached to the bottom surface 17 of support mount 16. The other end of PZT tube scanner 19 is connected with cantilever holder 22 and beam tracking lens 23. A cantilever probe 24 is secured to the free end 25 of cantilever holder 22.
A laser module 26 such as a diode laser element is attached to laser adjustment attachment 18 as shown in FIG. 2 which, as described, is attached to support mount 16. Support mount 16 has an opening 27 defined therethrough to allow the shank of laser module 26 to extend downwardly therethrough towards the cantilever probe 24. Laser module 26, thus positioned, produces a coherent, collimated laser light beam directed downwardly through beam tracking lens 23 toward the upper surface of cantilever probe 24.
Detector position adjustment attachment 20 comprises position sensitive photodetector module 28 and is likewise attached to support mount 16 adjacent to laser module 26. A clearance opening (not shown) is defined through support mount 16 to enable the photodetector embodied in position sensitive photodetector module 28 to receive laser light reflected from cantilever probe 24.
An L-shaped support member 32 is attached to the lower surface 33 of PZT tube scanner 19 and extends outwardly and upwardly therefrom. Lens support arm 34 is integrally formed with L-shaped member 32 and extends outwardly therefrom. Beam tracking lens 23 is seated within lens seating opening 36 formed in lens support arm 34 and secured thereto. The vertical arm 37 of L-shaped member 32 will be the same length as the focal length of beam tracking lens 23.
Cantilever holder 22 is formed preferably of flat steel and is attached to the bottom portion of L-shaped member 32 and extends outwardly therefrom. The distal end 38 of cantilever holder 22 carries cantilever probe 24 which is positioned directly under beam tracking lens 23.
Sample stage 21 is separate from pedestal 13 and the assembly of microscope 10 which is positioned on the top of motorized translational stage or base 11. Sample stage 21 normally will be formed of a block of stainless steel having a thickness sufficient to allow a sample 40, which is located on top of sample stage 21 to be engaged by cantilever probe 24 within the mechanical travel distance of base 11 in response to leveling screws 12 which are preferably motor driven.
As previously described, base 11 has three levelling screws 12 extending from the bottom which, in a preferred practice of this invention are controlled, individually, by three motors, or three thumb screws (not shown). The amount of available extension of the screws 12 governs the distance between the cantilever probe 24 and surface of sample 40.
As particularly shown in FIGS. 1 and 2, microscope 10 comprises a sample stage 21 supporting sample 40 and the cantilever probe 24. A collimated diode laser module 26 is mounted so as to remain stationary with respect to microscope 10 during operation of microscope 10. The cantilever probe or tip 24 is attached to PZT tube scanner 19 directly and in fixed relationship to beam tracking lens 23 as shown.
A beam tracking lens 23 is attached, as described above, to L-shaped member 32. Beam tracking lens 23 can be a commercial grade bi-convex lens (diameter 10 mm) of focal length 25 mm. Cantilever holder 22, including beam tracking lens 23, is so designed to be as light as possible (less than 20 g) and mechanically rigid.
The moving beam tracking lens (moving with the movement of the lower surface 33 of PZT tube scanner 19) acts as a guide to the stationary laser beam to follow the moving cantilever. Such tracking action is achieved based upon the geometric optical principal, that all rays passing through the beam tracking lens 23 go to one focal point, regardless of the positions of incidence at the lens aperture as shown in FIG. 1. If the upper reflective surface of cantilever probe 24 moves slightly out of the initial optic axis, the beam tracking lens 23 moves out of the axis the same amount, leaving the laser beam arriving at the outer portions of the lens, where the curvature of the lens makes the beam bend toward the axis. The degree of the bend is such that the beam is still focused at the focal point, which is fixed at the reflective back surface of the cantilever, thus the automatic tracking action is achieved without any complicated active-control elements.
The position sensitive photodetector module 28 mounted within detector position adjustment attachment 20 produces electrical signals indicating the change of the position of the light beam which is reflected from the reflective back of the moving cantilever 29. At the end of the moving cantilever 29 there is a sharp-pointed probe tip 24 to inspect the surfaces and topologies of the sample 40. The electrical signal from the position detector is the measure of the amount of the force of atomic interaction between the probe tip 24 the surface of sample 40. This is the result of the force causing the probe tip 24 to be pushed or pulled higher or lower thus producing a bend in the cantilever 29. Such bending makes the laser light beam, focused by the moving beam tracking lens 23, change its angle of deflection, which causes the reflected light beam to emerge in the direction of position sensitive photodetector module 28 with force-varying angles.
The motion of cantilever probe 24 also causes the absolute position of the focus to move. However, due to the intrinsic optical property, within the practical limit, such position changes do not contribute significantly to the direction of the reflected laser light beam. Therefore, only the reflection angle of the beam, which is proportional to the magnitude of the force acting on the cantilever probe 24, is the cause of the change of the position of the bright spot (due to the reflected laser light beam) on the position sensitive photodetector module 28.
Images are recorded from microscope 10 using existing art equipment such as the Model TAC 3.0 available from AT Corp. of Tempe, Ariz. During imaging, the beam tracking lens 23 focuses all of the parallel incident light rays from laser module 26 into a fixed focused position below the cantilever probe 24. During operation, PZT tube scanner 19, beam tracking lens 23, cantilever probe 24 and cantilever holder 22 are moved so that the cantilever probe 24 is translated across the desired area of the surface of sample 40 which remains stationary on sample stage 21. The laser beam detection with the optical lever method is performed by using beam tracking lens 23 to guide the laser beam automatically with the moving cantilever probe 24.
Although the laser, the bi-cell photodetector, and cantilever are virtually the same as described in the optical lever scheme, the present invention provides three noteworthy advantages compared to the conventional optical lever scheme. First, the cantilever probe is attached directly to the PZT tube scanner by the cantilever holder. Second, a beam tracking lens is attached to the moving probe holder and to the bottom of the PZT tube scanner. Third, an S-shaped PZT tube scanner is provided.
Unevenness with an AFM image is caused by three factors. First, the "mirror" (reflective back of cantilever 29) moves out of the laser beam spot, as anticipated. Thus, the maximum range of scanning, R 0 , may be expressed as:
R.sub.0 =(w.sup.2 +D.sup.2).sup.1/2
where w is the diameter of the laser spot, and D is the diameter of effective mirror area. When D and w are both equal to 20 μm, then R 0 =28 μm. Second, , a constant background slope of average 5% is observed even after the relative sample tilt is adjusted to its minimum. It is interpreted that the finite size of the cantilever mirror selectively reflects part of the beam wave front. The wave front is found to be already highly spherical, even at a small distance (larger than -100 μm) from the beam waist. In a typical experiment, the focal point is located 2 mm above the cantilever to allow the largest scanning area. Using Gaussian optics, this deviation is calculated. The results predict the background to have 3% slope, in agreement with the observed 5%. Third, the uneven field near the boundaries of the image in respect to the detector orientation. Such a deflection can exist when there is diffraction of the beam by the non-perpendicular edges, especially of triangular tube cantilevers. Other causes, such as non-linear PZT response, are not significant in the images discussed here.
These factors are corrected by adding the beam tracking lens. In a geometric optic regime, the simple lens focuses all of the parallel incident rays into a fixed focus position. The lens eliminates most errors. The percent error in this case can be obtained as follows. Consider that the lens moves out of the optical axis slightly, as the scanner moves; then, the beam is no longer parallel to the axis because it is directed to the cantilever. This changes the incident angle which, in turn, may result in a beam shift at the detector position. Therefore, if the maximum scanning area is P 2 , and the focal length of the lens is F, then the change of the reflection angle θ is given by θ=2P/F. In terms of height error Z, using the optical lever formula described by Saridin in "Scanning Force Microscopy" (Oxford U. Press) 1991, p. 120, θ=3Z/2L. Therefore, the percent error T is given by T=Z/P=4L/3F, where L is the length of the cantilever. When L=100 μm and F=25 mm, then F=0.50%. Compared to the previous lensless case, the error is reduced by an order of magnitude. Within the Gaussian optics frame, which covers the experimental conditions here, the error is linear in P. Based on these, the maximum scanning range using a moving probe can be larger than 100×100 μm 2 .
In order to move the cantilever, it is attached at the end of the scanning piezoceramic tube, which is controlled by the high voltages applied to the electrodes located at the side walls of the tube. When the PZT is bent by these voltages, it is accompanied by a tilt of the bottom surface as described by Carr, R. G. "Finite element analysis of PZT tube scanner motion for scanning tunneling microscopy", Journal of Microscopy, 152, pp. 379-385, 1988. This results in a large change in the probe height during scanning. The tilt is removed to less than experimental tolerances by using the special S-shaped scanner of this invention. Experiments demonstrate that this design and method yields excellent images in AFM. See Jung and Yaniv, Electronics Letters, 29, No. 3, pp. 264-265.
In the prior art, which makes the PZT tube bend in an L-shape, one of the electrodes is controlled by a scanning voltage, say, in the X direction (Vx+), and the opposite electrode is controlled by another voltage (Vx-) in the X direction. The tube bends by an amount proportional to the difference in the two high voltages in the X direction. In the orthogonal direction (Y), each of the two electrodes facing each other has another controlling voltage in the Y direction in a similar fashion. One is Vy+ and the other is Vy-. Therefore, the tube will bend in the Y direction in response to the difference between Vy+ and Vy-. In addition, the inner surface of the tubes is covered with a separate cylindrical metallic electrode. A separate voltage to control the amount of the extension of the tube is applied to that electrode (Vz). The amount of the voltage difference between the Vz and the average values of the Vx+, Vx-, Vy+ and Vy- determines the amount of the extension, which is used to adjust the height.
The S-shaped scanner 19, as shown in FIGS. 3, 4 and 5, is composed of two identical PZT scanners implemented one on the top of the other. Both parts have four independent electrodes around the side walls of the tube, thus the total number of independent electrodes in the S-shaped scanner of the current invention is eight. Each electrode occupies one quadrant and tracks on the side wall outer surface as shown in FIGS. 3 and 4 where "A" represents applied voltage Vx+, "B" represents Vx- voltage, "C" represents Vy- voltage, and "D" represents Vy+ applied voltage.
In the current invention, two of the tubes with the same electrode configuration as the prior art are used. The improvement is to make one body scanner by placing one on top of the other. This is achieved either by gluing two separately made PZT tubes together or separating the four quadrant electrodes by half, at the midway along the length of the scanner tube, thus realizing eight different electrodes. Then the top and bottom half electrodes are connected to the opposite polarities of the control voltages, such that if one of the top electrodes has Vx+, the bottom electrode at the same side has Vx- connected, and vice versa. At the orthogonal direction, Vy+is at the top, the Vy- is at the bottom, and vice versa. Therefore, although four additional electrodes are added, the number of necessary control voltages are the same, including the Vz which is connected at the inside electrode, to control the height as shown in FIG. 3.
When the top section of the S-shaped scanner bends to one side, the tilt is created at the end of the section, which is the exact mid-point of the tube. At the same time, the bottom part bends to the opposite direction, with exactly the same amount of the tilt but, in the opposite direction, because the relative polarities of the voltages are opposite. Therefore, the net tilt at the bottom of the overall tube is virtually eliminated, as long as the sections are of the identical property.
In fact, the two sections bend to the opposite directions. However, the direction of the tilt of the top part is to the same direction of the bend, which makes the bottom part displaced to the same direction as the bending. The bottom part is bending toward the opposite direction. The top surface of the tube is a fixed flat surface, and the bottom part bends from the tilt angle caused by the top section of the PZT tube toward the direction of the displacement. The bending of the bottom part always leaves the overall net displacement to the direction of the bending of the top part. This result is obtained because the direction of the tilt is the same as the direction of the bending; the amount of the tilt is proportional to the amount of the bending; and the two sections are exactly identical to each other.
Therefore, the tilt angles are eliminated, while achieving the net scanning motion of the PZT tube. When the bending occurs, the overall shape looks like as alphabet "S". The extension action in the Z-direction is not affected by such electrode configuration. FIG. 5 shows the S-shaped bending of the present invention.
Mathematically, two same sections of arcs taken from one circle connected tangentially at the one end to the opposite direction will always yield a net displacement between the two end points, so long as the arcs are less than one-half of the circle.
The displacement of the prior art L-shaped bending is given by:
d.sub.L =1/2(L/R).sup.2
where R is the radius of the arc and L is the length of the overall tube, if R>>L. The S-shape yields:
d.sub.s =2* 1/2×(L/R).sup.2 =1/4(L/R).sup.2
Therefore, the displacement is reduced by 1/2, which is compensated for by increasing the length of the PZT tube by 1.4 times.
While illustrative embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications than have been mentioned above are possible without departing from the inventive concepts set forth herein. The invention, therefore, is not to be limited except in the spirit of the appended claims. | 4y
|
BACKGROUND OF THE INVENTION
This invention relates to bipolar batteries of the zinc-bromine type and, more particularly, to bipolar batteries of the zinc-bromine type having shunt current protection systems.
Bipolar electrochemical flow battery systems are well known. See, for example, U.S. Ser. No. 189,363 entitled "Terminal Electrode" filed May 2, 1988 by J. Zagrodnik and G. Bowen, the disclosure of which is hereby incorporated by reference.
Numerous techniques have been developed to reduce or minimize the undesirable side effects caused by the occurrence of bypass or the so-called "shunt currents" occuring in bipolar batteries wherein aqueous anolyte and catholyte are fed by manifolds to the various respective cells in a bipolar battery. Shunt currents occur as a result of the current seeking other conductive passages such as the manifolds used to feed the aqueous anolyte and catholyte in addition to the desired passage through the series connected cells. An undesirable side effect is the poor distribution of zinc causing poor battery performance or shortened battery life.
A particularly interesting technique for reducing shunt currents is embodied in the description of U.S. Pat. No. 4,197,169 issued to Zahn et al. on Apr. 8, 1980 in which a protective electric current is induced in the manifolds which carry the liquid electrolyte to the bipolar cells. In U.S. Pat. No. 4,279,732 issued to Bellows et al. on July 21, 1981, the electrodes providing the protective current, i.e., "protective electrodes", are made annular in shape about the manifolds providing a substantially uniform current density profile through the electrolyte manifold but does not impede the electrolyte flow itself.
U.S. Pat. No. 4,285,794 issued to Bellows et al. on Aug. 25, 1981 is directed toward the structure of the protective electrodes in a system for reducing shunt currents in zinc-bromine type bipolar batteries. Specifically, the annular negative electrodes have an outer sleeve and an inner porous liner. The outer sleeve is fed a bromine-rich electrolyte for the purpose of supplying the electrolyte flowing through the electrode with bromine but the inner porous sleeve does not permit the bromine-rich electrolyte itself to mix with the electrolyte. The liner, however, does permit the passage of ionic currents at low resistance.
U.S. Pat. No. 4,277,317 issued to Grimes et al. on July 7, 1981 describes the reduction of shunt currents in a bipolar battery by interconnecting the electrolyte channels (which communicate with the manifolds) that provide electrolyte to the cells with connecting tunnels. A protective current is formed along the tunnels and is supplied by an external source or the terminal cells of the battery itself. As described in U.S. Pat. No. 4,312,735, to Grimes et al., issued on June 26, 1982, power consumption of the tunnels is further reduced by tapering the tunnels so as to provide a smaller cross-section --and a higher electrical resistance--at the midpoint of the tunnels.
A typical construction of a bipolar battery of the zinc-bromine type is embodied in a unitary structure having a thermoplastic box-like frame in which an assembly of conductive substrates are positioned adjacent thin microporous separators having electrolyte channels embossed thereupon. The substrates alternate being coated with positive and negative materials. The entire assembly is tightly fitted within the external frame and sealed together. A plurality of manifold tunnels extending through the entire frame and assembly connect the aqueous catholyte and anolyte reservoirs to the proper catholyte and anolyte channels. Pumps supply the proper flow to the liquids. Each of the end blocks of the frame is provided with an external terminal lug which is electrically connected to the terminal electrodes within the frame. Additionally, a plurality of anodic and cathodic shunt tunnels interconnecting the respective channels extend from one end block to another. Protective negative and positive electrodes are positioned on the end blocks and are electrically connected to the shunt tunnels as described in the aforementioned U.S. Pat. No. 4,277,367 to Grimes, et. al. As stated in the aforementioned U.S. Pat. No. 4,312,335, the tunnels may be tapered to reduce power consumption.
Because of the build-up of zinc dendritic material and corrosive effects of the bromine, it is desirable that the protective electrodes and associated components be easily and quickly replaced at appropriate intervals. None of the references cited above, however, provide for or teach the removal and replacement of the protective electrodes in an economic and expedient manner.
SUMMARY OF THE INVENTION
A bipolar battery having common aqueous electrolyte carrying manifolds is provided with a shunt current protection system comprising a first pair of shunt tunnels respectively communicating with the aqueous anolyte and catholyte at the inlet side of the channels communcating with the manifolds and a second pair of shunt tunnels respectively communicating with the aqueous anolyte and catholyte at the outlet side of the channels. A plurality of protective electrodes in electrical communication with the electrolyte within the shunt tunnels are positioned in the end blocks. Each protective electrode includes a member adapted to electrically contact an external electrical current source and a device for removably securing the member to its respective end block.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary embodiments of the protective electrode assembly of the present invention will hereinafter be described in conjunction with the appended drawing, wherein like designations denote like elements; and:
FIG. 1 is an exploded schematic perspective view of a bipolar battery illustrating a plurality of cells separated by separators and an external view of the protective electrodes in accordance with one embodiment of the present invention.
FIG. 2 is an exploded schematic perspective of a bipolar battery as illustrated in FIG. 1 excluding the manifolds, pump reservoir assemblies, and protective electrodes, and including one pair of the shunt tunnels.
FIG. 3 is a side sectional view of a protective anode electrode assembly and a portion of the adjacent battery in accordance with one embodiment of the present invention.
FIG. 3a is a top plan view of a metal contactor employed with the embodiment shown in FIG. 3.
FIG. 3b is a perspective view of a protective electrode employed with the embodiment shown in FIG. 3.
FIG. 4 is a side sectional view showing a protective cathode electrode assembly and a portion of the adjacent battery in accordance with the embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Reference is made to the prior art bipolar battery of FIG. 1, in which character numeral 10 generally denotes a bipolar flow battery having a plurality of alternating separators 14 and electrodes 12. Disposed on one side of each electrode 12 is an anode half cell and on the opposite side a cathode half cell. The separators 14 and electrodes 12 may be friction welded together to form a sealed stack of cells. At each end of the battery is disposed an end block 18 appropriately abutting a terminal electrode 20, and a extends through end block 18. At opposite diagonal corners of end block 18 are located protective electrodes 24.
A pumping system provides the aqueous anolyte and catholyte complex to the respective anode and cathode half cells. For example, the aqueous anolyte is located in reservoir 26 and is fed through anolyte pump 28 through manifold 30 to a pattern of long, winding anolyte inlet and outlet channels which may be incorporated into one or both sides of separator 14 and electrodes 12. Anolyte moves across the faces of anode half cells as shown by arrows 29 and into return manifold 32, finally returning to reservoir 26. In a similar fashion, the aqueous catholyte complex located in the lower half of reservoir 36 is fed to manifold 38 via pump 40 to the patterns of channels formed on the faces of separator 14 and the cathode half cells of electrodes. The aqueous catholyte then moves into return manifold 42 and is returned to reservoir 36. Contemporaneously and commonly filed application Ser. No. 247,035 (assigned to the same assignee as the present application) describes in detail the structure of such channels, and is incorporated herein by way of reference.
Shunt currents are a common phenomena in batteries consisting of a series connection of cells which have a common conductive electrolyte such as the one discussed in reference to FIG. 1. The potential difference between the cells induces current to flow through the electrolyte flow channels from cells of higher potential to cells of lower potential, thus their value is zero when the battery voltage is zero but they get progressively higher as the battery voltage increases. These shunt currents produce two negative effects: (1) the shunt currents are parasitic to the battery, and (2) a maldistribution of zinc occurs which is detrimental to both battery performance and life.
When shunt currents flow between cells, electrons are consumed at the higher potential cells. This occurs through the plating of zinc (Zn ++ +2e - →Zn o ) at the anodes or the dissolution of bromine (Br 2 +2e - →2Br - ) at the cathodes. The current is then carried ionically through the electrolyte channel, into the manifold, such as manifolds 30, 32, 38 and 42, and through the electrolyte channels of adjacent lower potential cells. At the electrode surfaces of the lower potential cells, electrons are generated. This occurs through the dissolution of zinc (Zn o →Zn ++ +2e - ) at the anodes or the formation of bromine (2Br - →Br 2 +2e - ) at the cathodes.
The shunt current reactions occurring at the cathodes is not harmful since bromine is normally flushed from the stack and resupplied to the cells as needed for discharge. However, the net result of the anode shunt current reactions is that zinc is removed from the low potential side of the stack and redistributed to the high potential side of the stack. This results in a nonuniform performance of the cells which is detrimental to overall battery performance. Furthermore, the replating of zinc at the high potential anodes will occur preferentially at the closest point at which the electrode contacts the incoming electrolyte channels. As a result, zinc tends to plate from the edge of the electrode into the electrolyte flow channels. Eventually this will cause blockage of the flow channels, restricting electrolyte flow, and causing battery failure.
The shunt current protection system (SCP) does not reduce the parasitic draw on the battery. In fact, a slightly higher parasitic loss is required for protected systems than for systems in which the shunt currents are allowed to occur. However, by eliminating the flow of shunt currents, the SCP system eliminates the catastrophic failure mechanism of dendritic zinc plating into the flow channels, as well as the performance decline associated with the lack of a uniform zinc distribution from cell to cell.
The cells in a bipolar zinc/bromine battery are in electrical contact with one another through four common electrolyte paths, namely, the anolyte inlets and outlets and the catholyte inlets and outlets. Thus, the SCP system must prevent current from flowing through any of these pathways to be successful.
To accomplish the elimination or reduction of current from flowing through the manifold passageways, the shunt current protection system is provided involving four tunnels, two of which are shown in FIG. 2 as tunnels 60 and 62. For clarity, the anolyte and catholyte manifolds illustrated in FIG. 1 are shown only as intersections as is the other pair of shunt tunnels. Each tunnel 60 and 62 corresponds to one of the four electrolyte pathways for shunt currents as discussed above and runs essentially perpendicular to the electrolyte channels on the surfaces of the separator and electrodes. The intersection of tunnels and channels occur at a point close to the electrode surface. A protective electrode 24 (as shown in FIG. 1) is placed at both ends of tunnels 60 and 62 in end blocks 18. The required number of electrodes can be eight, but may also be as small as four as described below.
The SCP electrodes are connected to the battery terminals at their respective ends of the battery stack. Thus, the potential across the SCP electrode pairs is the same as the potential of the battery at all times. The potential between the SCP electrode pairs induces a current to flow through the tunnels. The level of the current depends on the resistance of the electrolyte which fills the tunnel. Since the electrolyte resistance is the same throughout the tunnel, a uniform voltage gradient is established from one end of the tunnel to the other. This voltage gradient will closely approximate the voltage gradient along the series connection of electrodes in the battery stack. As a result, the voltage at each intersection between the tunnel and the electrolyte channel is forced to be equivalent to the voltage of the electrode itself. As a result, no potential exists between the electrode surfaces and the electrolyte at the intersection, and thus no shunt currents flow.
The description given above is simplified in that it assumes that the protective current flows directly through the tunnel from one SCP electrode to the other. In reality, some of the protective current will itself flow through the electrolyte channels, into the manifold, and back down the electrolyte channels of adjacent cells to rejoin the tunnel current. This causes the protective current in the tunnels to be highest at each end of the stack, to decrease through the tunnel to the center of the stack, and then to increase again to the opposite end of the stack. The protective current entering one end of the tunnel equals that leaving the other end.
The net effect of this variation in current level throughout the tunnel would be a nonuniform voltage gradient through the tunnel if the tunnel were of uniform diameter and thus of uniform resistance. This would lead to a mismatch between the electrode cell voltage and the tunnel voltage, and a potential would still exist for shunt currents to flow. To avoid this problem, the tunnels are tapered in a predetermined manner. The tunnel is larger on each end and gets progressively smaller toward the center of the stack. Thus, the resistance of the tunnel is lowest at each end of the stack and gets progressively higher toward the center of the stack. The resistance variation is designed to offset the variation in tunnel protective current according to Ohm's law, and thus maintain the uniform voltage gradient through the tunnel.
The passage of some of the protective current through the electrolyte channels is not harmful since it involves only ionic current flow and thus no detrimental zinc plating is involved. However, plating can occur at the solid interfaces between the tunnels and the protective electrodes. At the low potential side of the stack the normal reactions at the ends of the anolyte and catholyte tunnels, respectively, would be:
Zn.sup.o →Zn.sup.++ +2e.sup.- and 2Br.sup.- →Br.sub.2 +2e.sup.-.
However, since no zinc metal exists at the SCP electrode, the bromide to bromine reaction replaces the zinc reaction for the anolyte tunnel. At the high potential side of the stack, the normal reactions at the ends of the anolyte and catholyte tunnels, respectively, would be:
Zn.sup.++ +2e.sup.- →Zn.sup.o and Br.sub.2 +2e.sup.- 2Br.sup.-
The zinc plating reaction can be detrimental in the same manner as discussed for shunt currents. Zinc will plate onto the SCP electrode surface and eventually through the tunnel and back into the electrolyte channels. This can short out the SCP electrode pairs and disrupt the electrolyte flow. To avoid these problems, catholyte containing bromine is supplied to the face of the SCP electrode at the high potential side of the anolyte tunnels. The bromine reaction will then occur preferentially to the zinc plating reaction and these problems are avoided.
As discussed before, the protective electrode assembly in accordance with the present invention is easily removable and replaceable. The protective electrode assembly is employed at both ends of the battery in bores in the end block facilitating easy and quick removal in contrast to those heretofore used. To illustrate this reference is made to FIG. 3 and end block 18 at the high potential side of the battery wherein end block 18 is provided with a bore 19 suitably threaded for receiving a protective electrode assembly 70. Assembly 70 comprises an annular supply fitting 74 of a non-conducting material positioned in bore 19 bearing against annular protective electrode 72 made of a conductive material such as graphite. The opening in electrode 72 circumscribes the openings 66, 68 of tunnels 60 and 62 and is tightly held against gasket 76 by fitting 74 which is threadably engaged with the internal threads of bore 19. A second annular gasket 78 may be placed between the abutting interfaces of electrode 72 and supply fitting 74.
Anode tunnel 60 is sealed by a separator disc 80 anode of any material which has a low resistance to ionic transfer, but prevents the bromine containing catholyte from entering tunnel 60. An example of such a material may be a submicroporous material marketed under the tradename of Daramic and available from W. R. Grace Company. The aqueous catholyte is tapped from the catholyte manifold. Separator discs 80 are needed only to seal the anolyte tunnels at anode end, i.e. high potential ends, and are not necessary for catholyte tunnels.
A metal contactor 84 is positioned against the protective electrode 72 and functions to supply and remove current from electrode 72. As illustrated in FIG. 3A, contactor 84 is in the shape of an annular ring 85 and a tab 86 which extends through a small hole in the edge of end block 18. External electrical connection is made to tab 86.
The catholyte or catholyte complex phase may be tapped off by a small line at the outlet of pump 40 and is supplied to protective electrode 72 through an appropriate opening 90 in supply fitting 74. The catholyte thus flows through fitting 74, past contactor 84, through protective electrode 72, impinges against separator disc 80 and into tunnel 60. Because of the reactive nature of the catholyte, it is preferable that contactor 84 made of an inert material such as titanium or, alternatively, ensuring that gasket 76 overlaps the inside edge of the annular portion of contactor 84 to prevent the inside edge of contactor 84 from being exposed to the aqueous catholyte.
When fitting 74 is screwed into bore 19, the pressure exerted against contactor 84 tends to cause it to rotate with fitting 74. Unless made of resistive material, tab 86 would have a propensity to shear. To prevent shearing, electrode 72 is designed with an indentation or locking groove 92 as shown in FIG. 3B which allows a locking relationship with tab 86. Additionally, electrode 72 is provided with a longitudinal groove 94. A threaded locking pin 96 is inserted through a threaded opening in end wall 18 and bears against electrode 72 within groove 94 preventing electrode 72 from rotating with fitting 74 when being tightened.
Protective electrodes on the cathode side of battery may be comprised of a solid fitting and solid members with indentations and grooves for respective use with contactors and locking pins. Solid cylindrical fittings are appropriate since there is no necessity for aqueous catholyte flow through the protective electrode. A removable assembly of the solid type is depicted in FIG. 4. Protective electrode 98 is positioned at the bottom of bore 100 in end wall 18 and against an annular gasket 104 which circumscribes tunnels 101, 103. While no separator disk is required at the end of the anolyte tunnels, small annular gasket 106 is preferably used to prevent crossflow between tunnels. Contactor 108 is placed in contact with electrode 98 and tab 109 extends externally of the assembly. Solid fitting 110 is screwed into bore 19 and bears against removable electrode 98 via gasket member 112. As before, other removable protective electrode 98 and contactor 108 may be restrained against rotation by vertical set screw 114 which contacts a groove in the side wall of electrode 98.
Alternatively, however, the protective electrode (cathode) assembly used above may be constructed identically to the protective anode assembly. To accomplish this, it would be necessary to return the catholyte to the reservoir 36 via a small tube attached to the opening in supply fitting 110. Still another alternative would be to use the solid structure of the cathode protective assembly illustrated in FIG. 4 at all locations. To ensure a supply of catholyte, channels cut through from the terminal electrode to the end separators would be needed. In each alternative, however, the advantage of replaceable protective electrode assemblies would still be preserved.
It will be understood that the foregoing description is of a preferred exemplary embodiment of the present invention and that the invention is not limited to the specific forms shown. Modifications may be made in design and arrangement thereof within the scope of the present invention, as expressed in the appended claims. | 4y
|
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent application Ser. No. 11/557,587, filed Nov. 8, 2006, the disclosure of which is incorporated by reference herein in its entirety.
TRADEMARKS
[0002] IBM® is a registered trademark of International Business Machines Corporation, Armonk, N.Y., U.S.A. Other names used herein may be registered trademarks, trademarks or product names of International Business Machines Corporation or other companies.
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] This invention relates to computer systems and, more specifically, to a method and a system for maximizing the throughput of a computer system in the presence of one or more power constraints.
[0005] 2. Description of Background
[0006] From small clusters of computers to large supercomputers, peak power consumption places a major constraint on the scalability of computer systems. For purposes of cost effectiveness, a computing system may initially comprise a small number of computing elements. At some point, it may be necessary to scale the computing system by adding additional computing elements so as to increase the overall processing capacity of the system. However, each of the components added to the system also increases the overall power consumption of the aggregate system. Energy constraints may prevent the use of computer systems which are capable of providing high throughput. In particular, peak power consumption is constrained such that computer processors are unable to operate at full computational capacity. What is needed is a control system that maximizes throughput in view of energy constraints.
SUMMARY OF THE INVENTION
[0007] Methods are provided for maximizing the throughput of a computer system in the presence of one or more power constraints by repeatedly or continuously optimizing task scheduling and assignment for each of a plurality of components of the computer system. The components include a plurality of central processing units (CPUs) each operating at a corresponding operating frequency. The components also include a plurality of disk drives. The corresponding operating frequencies of one or more CPUs of the plurality of CPUs are adjusted to maximize computer system throughput under one or more power constraints. Optimizing task scheduling and assignment, as well as adjusting the corresponding operating frequencies of one or more CPUs, are performed by solving a mathematical optimization problem using a first methodology over a first time interval and a second methodology over a second time interval longer than the first time interval. The first methodology comprises a short-term heuristic solver for adapting to computer system changes that occur over the first time interval. The second methodology comprises a long-term solver for adapting to computer system changes that occur over the second time interval, wherein the second methodology has greater accuracy and greater computational complexity than the first methodology.
[0008] Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with advantages and features, refer to the description and to the drawings.
Technical Effects
[0009] As a result of the summarized invention, technically we have achieved a solution wherein the components of a computer system are proactively controlled so as to limit power consumption with minimal degradation in computer system throughput. By limiting power consumption in this manner, these components may be packed more densely than what is currently practicable while still conforming to predetermined limits on power dissipation and power consumption.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The subject matter, which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other objects, features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
[0011] FIG. 1 is a block diagram illustrating an exemplary embodiment of a system for maximizing the throughput of a computer system under peak power constraints.
[0012] FIG. 2 is a block diagram illustrating a further exemplary embodiment of a system for maximizing the throughput of a computer system under peak power constraints.
[0013] FIG. 3 is a flowchart illustrating an exemplary method for maximizing the throughput of a computer system under peak power constraints.
[0014] Like reference numerals are used to refer to like elements throughout the drawings. The detailed description explains the preferred embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The following description of systems and methods for maximizing the throughput of a computer system in the presence of power constraints utilizes the following terms:
[0016] “Workload” is defined as the amount of input/output (I/O) utilization, processor utilization, or any other performance metric of servers employed to process or transmit a data set.
[0017] “Throughput” is the amount of workload performed in a certain amount of time.
[0018] “Processing capacity” is the configuration-dependent maximum level of throughput.
[0019] “Frequency throttling” is an illustrative example of a technique for changing power consumption of a system by reducing or increasing the operational frequency of a system. For example, by reducing the operating frequency of a processor under light workload requirements, the processor (and system) employs a significantly less amount of power for operation, since power consumed is related to the power supply voltage and operating frequency. Although frequency throttling has been applied to central processing units (CPUs), the operational frequency or speed of system components other than CPUs may also be adjusted or controlled. As a general consideration, the operational frequency or speed of a component may be related to the energy consumption level of that component. Any of several techniques may be employed to adjust or control the frequency of a system component. These may, but need not, include changing the system supply voltage or controlling a clock gate to eliminate a portion or fraction of a clock signal. Changing the system supply voltage is an effective technique for adjusting the operational frequency of a system component, but a processing delay may occur until this voltage stabilizes. Controlling the clock gate will not cause a substantial processing delay. Illustratively, the embodiments disclosed herein may utilize any of a fixed set of operational frequencies available to a system component. The fixed set of operational frequencies is selected to provide energy efficient operation. Energy efficient operation often exhibits a non-linear dependence on processing speed, thus making system optimization more difficult. Accordingly, less efficient but readily available technologies may be used to provide system optimization, such as permitting a CPU to momentarily exceed its power budget.
[0020] FIG. 1 is a block diagram illustrating an exemplary embodiment of a system for maximizing the throughput of a computer system under peak power constraints. The system is capable of proactively managing and controlling large-scale computer systems ranging from small clusters to large data centers and supercomputers. Since these large-scale computer systems are to be managed and controlled, they are referred to hereinafter as a controlled system 101 .
[0021] In the illustrative example of FIG. 1 , controlled system 101 includes a first hardware component 103 and a second hardware component 105 . However, a typical controlled system 101 includes numerous hardware components such as computing devices, storage devices, I/O and network devices, cooling devices, and so forth. Each of these component categories could, but need not, be implemented using a plurality of virtually identical devices. A computing device could, for example, be implemented using a general purpose computer equipped with one or more central processing units (CPUs), random access memory (RAM), one or more hard disk drives, and a network adapter, and capable of executing an operating system such as Linux. The components could be organized in various architectures, e.g., flat (a group of standalone computers) or hierarchical (grouped into clusters of servers/cabinets/chassis in which peripherals are shared).
[0022] A controlling system 107 is employed to proactively manage and control controlled system 101 . Controlling system 107 is capable of interacting with a plurality of components of controlled system 101 . Illustratively, controlling system 107 is implemented using a software program running on a general-purpose computer referred to as a resource manager 109 . Resource manager 109 is capable of accessing a policy database 111 stored on a computer-readable storage medium. Controlling system 107 could, but need not, be a part of controlled system 101 . Controlling system 107 controls controlled system 101 by repeatedly or continuously receiving information from the hardware components of the controlled system (such as first hardware component 103 and second hardware component 105 ) related to the current configuration of the components, workload of the components, and performance of the components. Based upon this received information, controlling system 107 provides first and second hardware components 103 , 105 with electric power budgets and configuration changes. An electric power budget specifies an upper bound on power consumption for a component. Illustratively, a component may, but need not, be responsible for maintaining adherence to this electric power budget.
[0023] Controlling system 107 controls assignment of tasks to the hardware components such as, for example, migrating a task from first hardware component 103 to second hardware component 105 . Controlling system 107 maintains a set of power constraints while maximizing throughput of controlled system 101 . This functionality is implemented by controlling system 107 receiving one or more external inputs from external sources such as a first external sensor 113 and a second external sensor 115 . First external sensor 113 may represent a temperature sensor, an electric power controller, or another type of sensor. Similarly, second sensor 115 may represent a temperature sensor, an electric power sensor, or another type of sensor. Controlling system 107 also includes an input/output device 117 for accepting an input from a human operator and for providing an output to a human operator. In response to at least one of first external sensor 113 , second external sensor 115 , or input/output device 117 , resource manager 109 modifies power constraints and/or optimization parameters for controlled system 101 .
[0024] Controlling system 107 interacts with first and second external sensors 113 , 115 and first and second hardware components 103 , 105 to monitor controlled system 101 on a continuous or repeated basis. Typically, this monitoring is periodic and performed at fixed intervals such as every five seconds. Additionally or alternatively, this monitoring may include resource manager 109 sending a message to input/output device 117 in response to at least one of first external sensor 113 or second external sensor 115 sensing a predetermined event. During this monitoring process, controlling system 107 receives updated information from first hardware component 103 and second hardware component 105 pertaining to each component's current physical and logical configurations, as well as each component's current workload and performance.
[0025] Physical configuration data includes a component's installed hardware (such as RAM), the hardware's settings (e.g., CPU frequency and voltage), and available peripherals (e.g., active network and storage devices). Logical configuration data includes information regarding an operating system installed on the component, as well as any runtime parameters for the component. Workload data contains statistics regarding the task or tasks currently performed by the component. For example, if the component is a computing device, workload data includes a relative intensity for each of a plurality of tasks in terms of CPU, memory, disk space, or network access. If the component is a network or storage device, workload data includes the number and intensity of flows that traverse the component. Performance data includes information regarding the utilization of the component (such as a cache missed count), the progress of any task or tasks assigned to the component (such as the number of each task's instructions that have been executed), and the current physical conditions under which the component is operating (such as a device's power consumption and internal temperature).
[0026] Controlling system 107 outputs an electric power budget and configuration changes to each of a plurality of components, such as first hardware component 103 and second hardware component 105 . The power budget is a limit on the actual power consumption of the component. If controlling system 107 has control over an electric power supply, then the controlling system can physically enforce power budget limits for one or more components as, for example, by disconnecting power to components that violate the limit. Alternatively or additionally, each component is responsible for adhering to its power budget by routinely measuring its own power consumption and taking action in response thereto when measured power consumption exceeds the budget limit. If each component is responsible for adhering to its own power budget, this is helpful in situations where the response time of the component is shorter than the response time of controlling system 107 .
[0027] From time to time, controlling system 107 may receive an input from first external sensor 113 or second external sensor 115 and, in response thereto, modify one or more power constraints or configuration parameters. For example, overall power consumption may be severely constrained due to a power failure, or if a particular location exceeds a predetermined room temperature threshold, then all components proximate to that location might be constrained to a total power consumption which is considerably less than current (or recent) power consumption. By means of input/output device 117 , a human operator can manually place ad-hoc constraints or relax existing constraints, according to external considerations (i.e., short-term peak performance). Similarly, the operator may change various optimization parameters, for example, by modifying task priorities or by relaxing fairness requirements.
[0028] Controlling system 107 may instruct first hardware component 103 or second hardware component 105 to change its configuration. A configuration change includes any of: (a) shutting the component down or putting the component into a low-power consumption (standby) mode for a limited or indefinite time, (b) changing a component setting such as frequency and/or voltage, or (c) turning off some subcomponents of the component (like RAM, hard disks, or network adapters). Such changes may have a negative effect on component throughput, but one function of controlling system 107 is to assess controlled system 101 for the purpose of determining which change or changes will provide the least degradation of overall throughput.
[0029] Controlling system 107 controls assignment of tasks to first and second hardware components 103 , 105 . Controlling system 107 also controls migration of tasks from first hardware component 103 to second hardware component 105 , and from second hardware component 105 to first hardware component 103 . In order to implement these assignments and migrations, controlling system 107 may be provided with a list or set of permissible hardware components to which a given task or category of tasks may be assigned, a speed estimation algorithm for estimating execution speed of a task on every permissible hardware component, and a resource estimation algorithm for estimating time and bandwidth required for a potential migration. However, these estimation algorithms and task lists are greatly simplified if every single task is permissible on a set of substantially identical hardware components.
[0030] FIG. 2 is a block diagram illustrating a further exemplary embodiment of a system for maximizing the throughput of a computer system under peak power constraints. The embodiment of FIG. 2 is based upon the exemplary system depicted in FIG. 1 wherein controlled system 101 ( FIG. 1 ) includes M groups of machines, M representing a positive integer. For example, controlled system 101 of FIG. 1 may include a first group of machines 201 ( FIG. 2 ), a second group of machines 202 , and a third group of machines 203 . Each group contains at most K identical machines, where K is a positive integer greater than one, possibly with additional resources shared among these K identical machines. Machines in different groups need not be identical. For example, first group of machines 201 includes a first processing unit 211 and a second processing unit 212 . Illustratively, first and second processing units 211 , 212 may each be implemented, for example, using a CPU, a blade having one or more CPUs, or a computer server.
[0031] First and second processing units 211 , 212 are shown for purposes of illustration, as first group of machines 201 could include any number of processing units greater than zero. In the case of a blade implementation, a single chassis could be employed containing at most K blades and an Ethernet switch module. This chassis could possibly be accompanied by a dedicated storage server, with each blade running a Linux operating system. Each machine, which in this example includes each of K blades, is executing zero or more tasks assigned thereto by resource manager 109 . Resource manager 109 is illustratively implemented using a database server or web server. The assignment of tasks to machines may be determined in advance, may change with time, and/or may be determined exogenously (by a human operator, for instance). Optionally, each task is assigned a corresponding level of priority.
[0032] Second group of machines 202 includes a first network unit 221 and a second network unit 222 . However, first and second network units 221 , 222 are shown for purposes of illustration, as second group of machines 202 could include any number of network units greater than one. First and second network units 221 , 222 are illustratively implemented using network adapters. Third group of machines 203 includes a first storage unit 231 and a second storage unit 232 . However, first and second storage units 231 , 232 are shown for purposes of illustration, as third group of machines 203 could include any number of storage units greater than one. First and second storage units 231 , 232 are illustratively implemented using hard disk drives, storage drives for magnetic tape, or any other type of data storage drive that includes a computer readable storage medium.
[0033] Each group of machines 201 , 202 , 203 may be capable of controlling its maximum power consumption so as to adhere to a given limit called a power budget. Alternatively, each machine in each group of machines 201 , 202 , 203 may be capable of controlling its maximum power consumption so as to adhere to the power budget. Such control may be achieved, for example, by measuring actual power consumption at fixed or repeated intervals (e.g., every 2 milliseconds) and throttling the machine (i.e., decreasing CPU frequency) whenever the actual consumption approaches or exceeds the power budget limit. This limit can be changed in fixed intervals, such as every one second.
[0034] Controlling system 107 ( FIGS. 1 and 2 ) assigns a power budget to each of the M machine groups or, alternatively, to each machine. The power budgets must satisfy a constraint that the sum of power budgets cannot exceed a limiting value E max that was given to controlling system 107 . For example, controlling system 107 can possibly split the total power budget equally among the M groups by assigning a budget of E max /M to each group, but this allocation could possibly be improved, for example, if the various groups of machines (1) run different workloads, (2) contain different machines in terms of brand, model, or architecture, or (3) contain a different number of machines. Additionally, controlling system 107 guarantees certain fairness conditions, such that each group of machines may receive a minimum power budget of at least E max /8M, unless a smaller budget suffices for that group to handle its workload (i.e., in the case of a web server that receives very few hits).
[0035] Alternatively or additionally, controlling system 107 may assign tasks to individual machines. More precisely, each task is associated with a particular group of the M groups (fixed in advance), and controlling system 107 assigns the task to one of the machines in the particular group. This assignment can be changed over time. However, a certain overhead is incurred in changing the assignment in terms of latency caused by moving data. Controlling system 107 receives details regarding each machine, such as its utilization and power consumption, so as to identify over utilized and underutilized machines, and to transfer tasks from the former to the latter if the underutilized and over utilized machines are in the same group.
[0036] FIG. 3 is a flowchart illustrating an exemplary method for maximizing the throughput of a computer system under peak power constraints. The process commences at block 301 where logical and physical information is collected from controlled system 101 ( FIG. 1 ) and external sensors (such as first external sensor 113 and second external sensor 115 ). Next, a mixed integer optimization problem is formulated based upon one or more power constraints ( FIG. 3 , block 303 ). Formulation of this mixed integer optimization problem is described in greater detail hereinafter. The mixed integer optimization problem is solved (block 305 ). The configuration of controlled system 101 ( FIG. 1 ) is updated with a new power budget and new task allocations ( FIG. 3 , block 307 ). The process then loops back to block 301 .
[0037] The mixed integer optimization problem of block 303 is formulated as follows. One objective of controlling system 107 ( FIGS. 1 and 2 ) is to maximize overall throughput of controlled system 101 ( FIGS. 1 and 2 ) subject to given power constraints. The throughput is defined as the total number of instructions of all tasks in the system which are executed per unit of time (i.e., one second). Controlling system 107 also ensures additional properties, such as fairness, by introducing additional constraints that avoid undesired effects. In situations where time allows, controlling system 107 may solve a constrained optimization problem whose objective is to process as many instructions per time unit as possible. Accordingly, this optimization problem is formulated as a mixed integer programming problem to be solved during each of a plurality of time intervals.
[0038] The elements of the optimization problem are as follows. There is a set of indices of machines {1, . . . ,m}, a set of indices of tasks {1, . . . ,n}, and a set of indices of CPU frequencies {1, . . . ,s}. The following attributes of controlled system 101 are inputted to the mixed in integer programming problem as parameters:
[0039] W i —the importance (or “priority”) of task i:
[0040] M i —the machine on which task i is currently run (or 0 if none);
[0041] G ij —the cost of transferring task i to machine j≢M i ;
[0042] F k —the kth CPU frequency value (k=0,1, . . . ,s);
[0043] H ik —the average number of cycles per instruction for task i running on a machine operating at the kth CPU frequency (this estimate captures expected I/O and memory delays);
[0044] E max —Maximum-energy-consumption bound, which controlled system 101 must obey due to current physical conditions, such as temperature or power supply;
[0045] E jk —the amount of energy per time unit consumed by machine j when machine j is operating at frequency F k ;
[0046] B—a task-fairness parameter representing the maximum possible ratio between the number of CPU cycles planned for a single task and that of an average task.
[0047] Variables. The mixed integer linear programming problem looks for a currently optimal configuration for the managed system. This configuration includes assignment of tasks to machines and an allocation of an energy “budget” for each machine. The mixed integer linear programming problem is solved using an algorithm that uses one or more of the following decision variables:
[0048] z j —a Boolean variable indicating whether machine j is active or not;
[0049] x ij —a Boolean variable indicating whether or not task i is assigned to machine j;
[0050] y jk —a Boolean variable indicating whether or not machine j is working at frequency F k ;
[0051] ƒ ijk —a continuous variable representing the number of CPU cycles per time unit that is planned for task i on machine j running at the kth CPU frequency. Note that each task is processed by only one machine having a CPU that operates at only one frequency;
[0052] v ij —a continuous variable representing the number of instructions per time unit that is planned for task i on machine j. Each task is processed by only one machine;
[0053] u j —a continuous variable representing the energy upper bound (“budget”) allocated to machine j;
[0054] Objective function. The algorithm solves the problem of maximizing the total planned number of instructions per time unit. This quantity of instructions is equal to
[0000]
∑
i
=
1
n
∑
j
=
1
m
W
i
v
ij
.
[0000] In addition, the algorithm penalized the transferring of tasks from one machine to another; this quantity is equal to
[0000]
∑
i
=
1
n
∑
j
≠
M
k
G
ij
x
ij
.
[0000] Hence, the algorithm's objective function is given by
[0000]
∑
i
=
1
n
(
∑
j
=
1
m
W
i
v
ij
-
∑
j
≠
M
i
G
ij
x
ij
)
[0055] Constraints. The optimization is subject to constraints as follows. In the sequel, let [t]={1, . . . ,t}.
[0056] Consistency constraints:
[0000] x ij ≦z j for all iε[n], jε[m]
[0000] meaning that the tasks can be assigned only to active machines;
[0000]
∑
j
=
1
m
x
ij
=
1
for
all
i
∈
[
n
]
[0000] meaning that each task is assigned to a single machine;
[0000]
∑
k
=
0
s
y
jk
=
z
j
for
all
j
ɛ
[
m
]
[0000] meaning that one frequency has to be selected for each machine;
[0000] ƒ ijk ≦F s x ij for all iε[n],jε[m],kε[s]
[0000] meaning that task execution takes place only on assigned machines;
[0000] η ijk ≦F k y jk for all iε[n],jε[m],kε[s]
[0000] meaning that task execution takes place only at assigned CPU frequency;
[0000]
v
ij
≤
∑
k
=
1
s
f
ijk
/
H
ik
for
all
j
∈
[
m
]
[0000] meaning that the number of instructions planned is proportional to the number of cycles planned, according to that task's effectiveness at that frequency.
[0000]
∑
j
=
1
m
∑
k
=
1
s
f
ijk
≥
B
·
W
i
∑
l
=
1
n
W
l
·
∑
j
=
1
m
∑
k
=
1
s
F
k
y
jk
for
all
i
∈
[
n
]
[0000] meaning that the number of cycles planned for a task is at least a B-fraction the number of cycles planned for an average task.
[0000]
∑
k
=
1
s
E
jk
Y
jk
≤
u
j
for
all
j
∈
[
m
]
[0000] representing an energy budget constraint;
[0000]
∑
j
=
1
n
u
j
≤
E
max
[0000] representing the total energy constraint.
[0057] Remarks. A preferred embodiment may generalize or specialize the above by having some or all of the following properties.
Machines may each have different maximum CPU frequencies, and this property may be modeled by letting s be the maximum possible frequency and adding the constraint y ik =0 whenever machine j cannot run at the kth CPU frequency. Tasks cannot be transferred to other machines (i.e., task i must be assigned to machine M i ). The cost of transferring a task does not depend on the target machine, i.e., G ij is the same for all j≢M i . The m machines are partitioned into p groups, and a task can only be transferred to machines in the same group, i.e., G ij =∞ for all j in a different group than M i . The total energy consumption of a subset J ⊂ [m] of the machines might be limited to some amount E J (e.g., due to power failure or infrastructure), which is modeled by adding the constraint
[0000]
∑
j
∈
J
u
j
≤
E
J
The number of cycles planned for task i is limited by a bound C i (e.g., to model task serving a limited number of requests), which is modeled by adding the constraint
[0000]
∑
j
=
1
m
v
ij
≤
C
i
Additional fairness constraints can limit the ratio between the number of instructions planned for task i and that planned for task i′ by some parameters L 1 ,L 2 >0 (e.g., to make sure these tasks can progress simultaneously), which is modeled by adding the constraint
[0000]
L
1
∑
j
=
1
m
v
ij
≤
∑
j
=
1
m
v
i
′
j
≤
L
2
∑
j
=
1
m
v
ij
[0065] Updating the configuration of controlled system 101 ( FIG. 1 ) as described in block 307 of FIG. 3 may, but need not, include one or more of the following processes. Task scheduling and assignment may be optimized by scheduling a first task to be performed by at least one of the plurality of CPUs simultaneously with a second task to be performed by at least one of the plurality of disk drives. At least one CPU of the plurality of CPUs may be powered down, thereby scheduling a third task to be performed by fewer CPUs of the plurality of CPUs. At least one of the plurality of disk drives may be powered down, thereby scheduling a fourth task to be performed by fewer disk drives of the plurality of disk drives. A lower performing CPU of the plurality of CPUs may be allocated to a fifth task. A lower performing disk drive of the plurality of disk drives may be allocated to a sixth task. A seventh task and an eighth task may be scheduled to execute simultaneously on the plurality of CPUs, wherein the sixth and seventh tasks are independent of each other.
[0066] As described above the parameters to this model are given to the system based on the system configuration and recent estimates about the task resource requirements. Thus, every time the mixed-integer program is solved, the parameters may have different values, yielding a different solution. Similarly, new constraints may be added, permanently or temporarily, either by an operator or as an automatic response to existing conditions, again leading to changes in the solution.
[0067] The capabilities of the present invention can be implemented in software, firmware, hardware or some combination thereof As one example, one or more aspects of the present invention can be included in an article of manufacture (e.g., one or more computer program products) having, for instance, computer usable media. The media has embodied therein, for instance, computer readable program code means for providing and facilitating the capabilities of the present invention. The article of manufacture can be included as a part of a computer system or sold separately. Additionally, at least one program storage device readable by a machine, tangibly embodying at least one program of instructions executable by the machine to perform the capabilities of the present invention can be provided.
[0068] The flow diagrams depicted herein are just examples. There may be many variations to these diagrams or the steps or operations described therein without departing from the spirit of the invention. For instance, the steps may be performed in a differing order, or steps may be added, deleted or modified. All of these variations are considered a part of the claimed invention.
[0069] While the preferred embodiment to the invention has been described, it will be understood that those skilled in the art, both now and in the future, may make various improvements and enhancements which fall within the scope of the claims which follow. These claims should be construed to maintain the proper protection for the invention first described. | 4y
|
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] This application claims the benefit under Title 35 United States Code §119(e) of U.S. Provisional Patent Application Ser. No. 61/389,807; filed Oct. 5, 2010, the full disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to devices for the detection of particles and electromagnetic (EM) radiation and to methods for the manufacture of such devices. The present invention relates more specifically to methods for the more efficient manufacture of detection tubes using detection materials that require electron scrubbing to form an optimal detection device. The system provides electron scrubbing in a generally closed environment as part of the manufacturing process.
[0004] 2. Description of the Related Art
[0005] Various types of particle and EM radiation detectors (such as neutron detectors) depend upon the use of plates or surfaces of materials sensitive to the particles or radiation to be detected. Making such detectors operate in an optimal manner typically means manufacturing the material plate or surface to a very high level of uniformity and purity. The removal of surface contaminants becomes an important part of the manufacturing process. This process for removing contaminants from the sensitive detection surfaces and plates is often carried out using electron scrub guns. Such scrub devices excite the material to the point where contaminants and impurities are displaced from the surface and drawn away to be removed from the detector or to be held in a non-interfering position within the detector.
[0006] The typical contaminant removal process is a scrub then seal process where the scrubbing is carried out before or during a vacuum process and then the chamber within which the detector material is positioned is closed and sealed. This can be an expensive and complex manufacturing process often requiring highly sophisticated vacuum and exhaust chambers. Frequently the manufacturing process is slow with the scrub then seal steps operating on only one or a very few detector tube assemblies at a time.
[0007] Traditional detectors that require electron scrubbing would be typically manufactured in an open configuration before processing and sealing. This manufacturing configuration, primarily required by the manner of electron scrubbing, involves a large open area that exposes the entire set of active detector components. This results in a much greater threat to the quality of the detector derived from the manufacturing process whereby exposure of the detector internal components to particles generated during processing occurs. Detectors are generally high voltage devices with close parts spacing, and therefore the presence of particulate contamination results in a higher frequency of static discharge and high voltage arcing during operation.
[0008] Typical prior art electron sources (electron scrub guns) must be placed several inches away from the surfaces they are intended to activate or clean. This is due to the general emission shape of the electron stream which may be characterized as emitting from a point source or small area. The further the separation (throw distance) between the electron source and the surface to be cleaned, the wider the spread of the electron stream. To create a relatively uniform stream of electrons, the traditional electron source must be positioned further back from the detector plates being scrubbed to impart a uniform flux to the edges of the detector relative to the center of the detector. In many cases, this effect under-processes the detector peripheral areas while over-processing the detectors central area where the electron flux is greater. This uneven scrub often leads to detector image defects, such as darker, less responsive outer regions, if the overall detector is not sufficiently activated or scrubbed.
[0009] In contrast to electron scrub guns, electron emitting plates produce a much more uniform stream of electrons, which can be used to more uniformly scrub, or activate a detector's surface. It is also possible to position such an electron source closer to the detector surfaces that are being scrubbed during the detector activation and manufacturing process. In other words, the use of electron generating plates reduces the need to create separation between the emitter plate and the detector surface being activated or cleaned. The work done by an electron scrub source is a function of its flux (quantity of emitted electrons) and voltage separation between the electron generating plate and the surface to be cleaned or activated. The emission flux of an electron generating plate (or a stack of generating plates) used to clean surfaces in a vacuum is adjustable by varying the applied voltage separation between the generating plate and activation surface, as well as varying the number of electron generating plates placed in a series configuration in proximity to the detector plate or plates.
[0010] It would be desirable, therefore, to have a detector tube device, and a method for manufacturing the same, that were capable of utilizing electron generating plates as the electron scrub source so as to improve the manufacturing process and reduce the incidence of particle contaminants within the detector, and to further reduce variations in the quality and character of the detector plate surface after scrubbing. It would be helpful to configure the manufacturing process for a detector tube stack into a smaller space that requires fewer ancillary mechanical parts and hardware to draw a vacuum and then perform a sealing operation with the vacuum or near vacuum in place. It would be desirable to eliminate as many sources of significant particle generating hardware from the overall manufacturing system. It would be desirable to position and place the electron scrub source in close proximity to the detector plate(s) to be scrubbed, thereby again minimizing the space required for the manufacturing process and the number and size of the components required.
SUMMARY OF THE INVENTION
[0011] The present invention provides a new detector tube structure and manufacturing process that carries out electron scrubbing after the detector enclosure has already been closed and at least partially sealed. In this manner, much of the complex manufacturing equipment can be eliminated and large numbers of detectors may be manufactured at the same time. The present invention therefore involves a novel detector tube structure and a new method of manufacture for the same.
[0012] The application of electron generating plates to the closed detector manufacturing process reduces the size and complexity of the necessary vacuum system by eliminating many of the manipulation hardware components previously utilized to perform a seal in a vacuum. This eliminates many significant particle generating components from the overall vacuum process. The overall space within which the manufacturing process occurs is reduced due to the close proximity between the electron generating plates and the detector surfaces being activated and cleaned. This manufacturing volume reduction reduces systems that required separation distances between the scrub source and the scrub surface of several inches to significantly less than 1.0 inches and potentially down to under 0.1 inches. The reduction of the manufacturing process to a more compact configuration allows for higher performance operation in the detector and vacuum processing and produces a higher quality detector. The detectors produced by the systems and methods of the present invention are less likely to fail for electrostatic defects or for image or response non-uniformity. A detector with a greater operation lifetime is also produced as the vacuum levels of the lower volume vacuum systems consistently pump down to lower base vacuum pressures, thus producing detectors with lower levels of contaminating internal gas molecules, which can over time degrade the detector performance.
[0013] The present invention provides a novel structure that allows for the manufacturing process to place the electron scrub source in close proximity to the detector surfaces. This novel structure enables the manufacturing process to present a mechanically assembled detector to the vacuum processing steps. This is accomplished by placing the electron generating plate within the housing of the detector as opposed to external to the detector structure during the manufacturing process. This novel structure therefore permits a novel method of manufacture that achieves the benefits described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1A is a perspective view of the detector tube system of the present invention shown fully assembled.
[0015] FIG. 1B is a detailed cross-sectional view of the stack structure of the detector tube system of the present invention.
[0016] FIG. 2 is a detailed cross-sectional view of the plate stack of the present invention taken along section line A-A′ in FIG. 1B .
[0017] FIG. 3 is a top plan view of the detector tube system of the present invention shown with the potting removed.
[0018] FIG. 4 is a top plan view of the plate stack of the present invention shown removed from the container body for clarity.
[0019] FIG. 5A is a flow chart describing the individual device assembly process of the method of the present invention.
[0020] FIG. 5B is a flow chart describing the multi-device manufacturing process of the method of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] Reference is made first to FIG. 1A which is a perspective view of the detector tube system of the present invention shown fully assembled with the rear face of the tube positioned upright towards the top of the page and the front face of the tube hidden from view. Detector tube system 10 of the present invention, when fully assembled, is shown to be constructed from container body 12 that is welded to a rear end cap (not seen beneath the potting material) at rear end cap weld 20 . Electrical feed through conductors 24 are shown to extend through potting material 28 . Exhaust port 30 (to be connected to a vacuum source) is also shown extending through potting material 28 and is designed to be pinched off during the manufacturing process.
[0022] Reference is next made to FIG. 1B which shows a cross-sectional view of the detector tube stack 10 of the present invention. The assembly comprises a container body 12 which holds and positions a number of plates 32 , 34 , and 36 , in a stacked configuration as shown. Ceramic spacers/insulators 18 a - 18 d provide substrates for a plurality of electrical connections 26 . A formed end cap 16 is structured on the front of the container body 12 , as well as a second formed end cap 14 on the rear of the container body 12 . Appropriate welds 20 & 22 are positioned and made as indicated.
[0023] Electrical feed through conductors 24 (five in the preferred embodiment) are positioned and terminate in electrical connections 26 (again five in the preferred embodiment) as shown. An exhaust port 30 is placed and positioned as shown and is pinched off during the manufacturing process (as described in more detail below). A quantity of potting 28 is positioned within the formed end cap (rear) 14 of the container body 12 . The exhaust port 30 and electrical feed through connections 24 extend through the potting material 28 .
[0024] FIG. 2 is a detailed cross-sectional view of the stack configuration shown generally in FIG. 1B . The potting material 28 of thickness is shown at the top of this cross-section view where it is supported by the formed end cap (rear) 14 of the container body 12 . A collector plate 32 is positioned within the container body 12 using the spacers and insulator substrates 18 as described above. The collector plate 32 , having a thickness, is positioned in spaced relationship from formed end cap (rear) 14 , a distance, and from detection plate 34 (neutron sensitive material in the example shown) a distance, positioned within the center of the container body 12 . Detection plate 34 , having a thickness, is positioned in spaced relationship from electron generating plate 36 a distance of. The electron generating plate 36 , having a thickness , is positioned immediately inside the formed end cap (front) 16 of the container body 12 separated by a distance.
[0025] The electron emissions from the electron generating plate 36 bombard the neutron micro channel plate (MCP) 34 during the scrubbing process. The process is proximity focused rather than beam focused as in the prior art. The bias voltage across the neutron MCP creates a cascade typical of normal MCP operation. The current (electron flow) is collected by the anode (collector) plate 32 .
[0026] The components described above are mechanically located and fixed in position by the series of ceramic insulators and conductive contact surfaces as required. All of these components are sealed inside of the metal container that provides for a hermetic ultra high vacuum (UHV) environment for the device to function. As shown, the container includes electrical feed through connections, a pinch off pumping port, and a flashable getter.
[0027] Referencing back to FIG. 1B , the various plates, spacers, and electrical connections associated with the detector tube stack are characterized according to the normal functionality associated with each of the individual plates and layers. As shown in FIG. 1B , various electrical contacts are provided on the appropriate surfaces of the spacers to which electrical conductors may be connected to provide the necessary voltages for operation of the electron source during the manufacturing process, as well as the operation (signal detection) off of the detector plate after the detector tube stack manufacturing process is complete. These electrical connections may vary according to the specific construction of both the electron generating source (i.e., the number of electron generating plates in the component) as well as the particular arrangement of the spacers and the required electrical contacts. The electrical conductor representation shown in FIG. 1B and further in FIG. 3 (described below) are merely representative of a number of possible structures for making electrical connection to the internal components of the closed detector tube stack. Five such contacts are specified in the preferred embodiment as providing two contacts to the electron generating plate, two contacts to the detector plate, and a single contact to the collector plate. In addition, the metal can enclosure may be held at a set electrical potential.
[0028] FIG. 3 is a top plan view of the detector tube system of the present invention shown with the potting material removed for clarity. In this view, detector tube system 10 is again shown to be constructed primarily of container body 12 on top of which is positioned formed end cap (rear) 14 . A representative ceramic spacer 18 a is shown in dashed outline form in this view for purposes of identifying the alignment of one or more electrical feed through conductors 24 a - 24 c. Rear end cap weld 20 is shown as the seam between container body 12 and formed end cap rear) 14 . In addition, exhaust port 30 is shown as a cylindrical tube extending through formed end cap (rear) 14 and welded to the same at exhaust port weld 31 . Electrical feed through conductors 24 a - 24 c (five shown in this particular embodiment) are sealed against apertures formed in formed end cap (rear) 14 in the manner shown and are further sealed by the use of the potting material (not shown) as described above.
[0029] FIG. 4 is a top plan view of the plate stack of the present invention shown removed from the container body as a manner of clarifying the various diametrical sizes of the spacers and plates within the detector tube stack. In this view, ceramic spacers 18 a, 18 b, and 18 d are shown. Plate stack 19 in this view is shown to comprise collector plate 32 (positioned on the top in this view), as well as detector plate (neutron sensitive material) 34 shown in dashed outline form as hidden in this particular orientation. The relative differences between the diameters of the various components in the detector tube stack shown are established primarily to allow for ready access to the necessary electrical contacts positioned on each of the spacer components, and to center the various operational plates within the detector tube stack. A given exposed area for each of the relevant functional plates (collector plate 32 , detection plate 34 , and electron generating plate 36 ) will vary according to the overall requirements of the detector. This cross-sectional functional diameter is best seen in FIG. 1B where internally each of the functional plates are oriented and positioned parallel and in proximity to one another to define a circular exposure area between them that in turn defines the functional characteristics of the detector tube, both in the manufacturing process and in its operation.
[0030] The novel concepts of the invention include the use of a scrub source (the electron generating plate) inside of the packaged device. This allows for a completely welded metal container that is very robust and simple to manufacture. The scrub source can be used as a signal generator after the device is sealed to test and calibrate the device. The use of the getter (the collector plate) allows for residual gas pumping after the device is sealed and burned in.
[0031] The method of manufacture is generally as follows. The components include: the scrub source plate; the neutron sensitive plate; and the anode plate. These components are arranged in a stack using metal rings for electrical contacts and ceramic spacers to insulate each component from one another. Ceramic spacers are also located at the top and bottom of the stack to insulate the metal can from the sensor stack up. Each component plate has appropriate electrical connections and is attached to a feed through conductor.
[0032] The assembly process is as follows. A quality check is made of all components. The stack up of components is assembled with the scrub source plate, the neutron plate, the anode plate, the metal contact rings, and the contact spacers, as shown in FIGS. 1A , 1 B & 2 . The above components are stacked up with the correct spacing and are placed into the base section of the metal container (can). The electrical connections are made and the cover is placed onto the can. The cover is welded (laser or TIG) in place with a hermetic quality weld. The pinch off tube is connected to a helium leak detector and the can is leak checked.
[0033] Reference is next made to FIG. 5A for a furthe description of the individual device assembly process of the method of the present invention. Assembly process 100 begins at Step 102 whereby a quality check of all components to be assembled is carried out. This is followed at Step 104 by the arrangement of the component stack to include the scrub source plate, the neutron detection plate, the anode plate, as well as the various metal contact rings and the contact spacers described above. At Step 106 the arranged component stack is then installed into the base of the metal enclosure. Various electrical connections are made at Step 108 . The can cover is positioned and welded in place at Step 110 and the helium leak check is performed at Step 112 . The individual device assembly being completed, the process then proceeds to the multi-device process at Step 114 .
[0034] The next part of the process may be carried out on a number of detector enclosures being produced at the same time. An array of containers may be configured on assembly trees and processed in steps as a group. An advantage of this tree system of processing is that it is scalable. That is, tree one may carry out loading; tree two may carry out pumping and bake out; tree three may carry out scrubbing; and tree four may carry out pinch off, sealing, and unloading.
[0035] The manufacturing process is scalable since trees can be added anywhere on the line. It is likely that there would be multiple trees scrubbing at the same time, for example. If each process took one day to complete (for example), then day five would begin the second loading of tree one and every day would yield finished product after that.
[0036] Reference is next made to FIG. 5B which is a flow chart describing the multi-device manufacturing process of the method of the present invention. Multi-device process 120 is initiated at Step 122 where multiple manufactured containers are arranged on an assembly tree as described above. At Step 124 a vacuum source is connected and pumps down the containers to a pre-bake out pressure. The method than proceeds at Step 126 to carry out the container bake out process before initiating electron scrubbing at Step 128 . The duration of the scrubbing is adjusted according to power level and the desired signal to noise ratio for the detector at Step 130 . The multi-device process then proceeds at Step 132 by pinching off the tubing components on each of the devices and then sealing and unloading the individual containers from the assembly tree. This results in the finished product at Step 134 .
[0037] The manufacturing process is therefore highly efficient since there is less investment in assembly processing than with a hot or cold indium sealing process. Additionally, if the container/can fails a leak check, it can be re-worked and checked again many times. If the can is deemed unusable, it can be disassembled and the components can be re-used with little risk of damage. One key feature is that the sensor is packaged and sealed into the container/can before it is pumped. When the leak check is passed, the container/can is attached to a pumping station. A pumping station can accommodate a large quantity of containers/cans to be processed. The tree is then “pumped down” to a pre-bake out base pressure. An oven is placed around the loaded tree and the process is performed. When the bake is completed the scrubbing process can begin. Depending on the EV (power level of the scrub source), and required signal to noise ratio of the finished sensor, this scrubbing step in the process can take several days.
[0038] The various components in the assembly of the present invention may be constructed of various materials known in the art for such elements internally operational in a vacuum environment. The collector plate, for example, should be constructed of a conductive metal with an oxidation free surface that does not insulate against or resist the electrons that are generated by the internal workings of the detector. A nickel based material may be preferred, but polished aluminum or stainless steel may also be utilized for the material of the collector plate.
[0039] The basic concepts of the present invention may be implemented in conjunction with detector tube stacks that contain more than one electron generating plates and more than one neutron sensing micro channel plates (MCP). The multiple plates in each case would of course dictate additional electrical contacts in order to carry out the operation of each of the components either during the manufacturing process or during the operational process.
[0040] The typical exhaust port of the present invention may be constructed from copper vacuum tubing and may exit any surface of the detector, although the preferred embodiment places the same onto the rear end cap where each of the electrical penetrations are also made. The exhaust port may be directed straight out of the detector as shown in the figures, or may bend ninety degrees relative to the indicated attachment surfaces. Some flexibility with regard to the tubing is desired in order to allow multiple detectors to be variously stacked or arranged during processing in the multi-device manufacturing method described.
[0041] The relative dimensions and spacing in the detector tube stack (seen most accurately in FIG. 2 ) may also vary according to the specific characteristics required of the detector. In FIG. 2 the direction of particle detection is from the bottom of the page to the top, i.e., from the front of the detector to the rear. Formed end cap (front) 16 of the detector housing is a vacuum tight metal skin such as % inch to ¼ inch thick stainless steel or aluminum. Such thicknesses are necessary in order to prevent the vacuum within the detector from collapsing or crumpling the skin wall. The electron generating plate must be far enough away from this front face enclosure wall as to prevent any arcing. A preferred dimension ( ) may be 0.050 inches, or a distance in the range of 0.020 inches to 0.250 inches.
[0042] Electron generating plates are available in thicknesses similar to standard micro channel plates (MCP) such as 0.4 mm, 0.5 mm, or 1.0 mm thick. The spacing between the electron generating plate and the detection plate ( ) may be as small as 0.010 inches but is preferably in the range of 0.025 inches to 0.050 inches, again simply to avoid arcing between the plates. The thickness of the micro-channel plate (detector plate) may be a standard thickness, as described above ranging from 0.4 mm to 1.0 mm. Again these include commercially available products such as 0.4 mm, 0.5 mm, 0.6 mm, 0.8 mm, and 1.0 mm thick plates.
[0043] The spacing from the MCP to the detector output (collector plate) may be similar to the spacing between the remaining plates as described above. In the case that the detector output contact anode consists of a phosphor coated optic, a generally greater voltage is applied which requires increased spacing between the component and the formed end cap (rear) of the overall enclosure. This spacing may preferably be from 0.020 inches to 0.100 inches as higher voltages are usually used to accelerate detector signal electrons to surfaces requiring additional photonic output. The collector anode for the detector may be a thin sheet of metal as described above, such as 0.5 mm thickness.
[0044] Detectors, no matter how well they are pumped out in initial processing, are not immune to having less than all molecules or atoms of volatile species initially pumped out of the detector prior to the processing, or immune from bulk materials used to construct the detector that may outgas volatile species over the life of the detector. In either case gas may accumulate inside the detector after it has been sealed and a non-evaporable getter is normally positioned within the detector to sequester the molecules to the getter and remove them the operational internal surfaces of the detector plates. During the burn-in of a detector, a slow initial activation of the detector for the first time, care is taken to not electrically arc the internal components.
[0045] The various electrical contacts internal to the system (See FIG. 1B ) will have wire conductors welded or soldered to them that provide the various isolated voltages at the detector contact surfaces. These electrical conductors are attached and soldered to the inner post of the electrical feed through during the assembly phase prior to attaching them. Welding and electrical testing is typically done by hand. The loaded detector enclosures are baked under vacuum to several hundred degrees centigrade (between 300 and 500 degrees centigrade). The electron scrubbing occurs after the manufacturing systems and detectors have substantially cooled down to between room temperature and 100 degrees centigrade.
[0046] Assembly trees of loaded detectors may run with global common voltages to the same functional feed-through conductors or each detector may have dedicated power supplies as necessary. The level of process control tends to be better with dedicated power supplies to each of the individual detector components. Voltages and currents are slowly ramped up during MCP activations (scrubbing of the MCP component) to normal detector voltages and currents. Additional quality checks are carried out during the manufacturing process. A clean pumped out detector is interfaced or connected to a helium leak detection system wherein a small partial pressure of helium is introduced to the outer surfaces of the detector and a leak checker senses for small levels of helium penetrating through or around the detector's seals or surfaces.
[0047] The present invention again provides for multi-detector assembly steps that exceed the typical loading levels and output rates of traditional detector vacuum processing systems. The present invention may in practice hold several times more detectors than traditional vacuum manufacturing systems (twelve versus fifty detectors on-line at a time per system). Although the preferred embodiment of the present invention comprises a round (cylindrical) package at a 40 mm diameter format, various other configurations are possible. 50 mm or 75 mm round formats may function in the same manner as described above. It is also possible for a square 50 mm by 50 mm format to operate at the same manufacturing structures and through the same manufacturing steps as described above. On balance, the manufacture of a round detector is more efficient than that of a square detector but certain applications may prefer square detectors in their final use and in assemblies with various components in which the detector functionality will be carried out.
[0048] Although the present invention (apparatus and methods) has been described in conjunction with a preferred embodiment, those skilled in the art will recognize alternate embodiments appropriate for use with different types of detectors and different manufacturing environments. The example provided relates primarily to a neutron detector although other types of particle and EM radiation detectors could also be manufactured using the principles of the present invention. In addition, the specific geometry (shape and size) shown for the detector stack is likely to vary depending on the particular application to which the detector is placed. In the example shown the basic neutron detector might use, for example, a 40 mm tube body with a welded anode; an 18 mm neutron detector MCP style plate; and an 18 mm electron generating plate. The adaptor rings would be designed and fabricated to fit the 18 mm and 40 mm components as required and provide electrical contact to the tube body connections. The desired front end spacing would be set by the spacer placements and thicknesses. The welds would engage the typical indium trough at the front end of the 40 mm tube body. The construction would include a sensor stack container that would completely envelope the 40 mm tube body when the lid is attached and would further include five high vacuum electrical feed throughs, a nickel pinch off tube with CF flange attachment for pumping system connection, upper and lower ceramic spacers to insulate and stabilize the tube body inside of the can, all of which will minimize overlaps and virtual leak paths.
[0049] The basic methodology which may be adapted (again to specific types of detectors and specific manufacturing environments) includes the steps of: arranging and constructing the stack (and surrounding components); leak checking (re-working as necessary); connecting; pumping; baking; scrubbing; testing (basic operational); pinching off; and final testing (particle source).
[0050] A further improvement to the manufacturing process may be achieved through the use of an ion pump that is maintained on the container/can. This would provide the added benefits of removing any gasses released during testing and/or burn in. The ion pump may also function as a vacuum gauge to quantify any noise or sensitivity data during testing. Component damage can be avoided if the vacuum pressure is monitored and is not too high. | 4y
|
[0001] This application is a continuation-in-part of Ser. No. 09/149,241 filed Sep. 9, 1998 abandoned; continuation-in-part of Ser. No. 09/350,380 filed Jul. 8, 1999.
FIELD OF THE INVENTION
[0002] The present invention concerns compositions and methods of treating arthritis, repairing of articular joint surfaces and relief of symptoms associated with arthritis.
BACKGROUND OF THE INVENTION
[0003] Arthritis, a musculoskeletal disorder, is the leading cause of disability in the United States. The Centers for Disease Control and Prevention (CDC) stated that arthritis and other rheumatic conditions accounted for about 744,000 hospitalizations and 4 million days of care in 1997. Forty million Americans, representing 15% of the population, have some form of arthritis, and that figure is expected to increase to 59.4 million (18.2%) by the year 2020, an increase of 57% in the number of persons affected. Arthritis patients make more than 315 million physician visits and are hospitalized more than 8 million times a year. Arthritis costs the nation $65 billion annually in medical costs and lost productivity. Osteoarthritis (OA), or degenerative joint disease, is the most common type of arthritis, affected 20.7 million people (12.1%) of U.S. adults in 1990, now estimated at 37 million, and trailed chronic heart disease as the leading cause of Social Security payments due to long-term absence from work. Lawrence R C, et al. Arthritis & Rheumatism 1998;41:778-799.
[0004] Osteoarthritis usually presents as pain, which worsens with exercise or simply an X-ray that clearly shows thinning cartilage. Common joints affected are the knees, hips and spine, finger, base of thumb and base of the big toe. Osteoarthritis is characterized by degenerative changes in the articular cartilage and subsequent new bone formation at the articular margins. The primary defect in hyaline cartilage, at the articular surface of the joint, is an alteration in the ratio of total glycosaminoglycans to that of the collagen fiber content in the matrix. Yasuda K. Hokkaido Igaku Zasshi 1997 Jul;72(4):369-76. Paleontologists have found osteoarthritis to exist in almost every vertebrate. Joint cartilage consists of only 5 percent cells, and joint cartilage lesions do heal. Tindall W N. Business & Health Dec 1997;47-48. Bones directly underneath the cartilage injoints is called subchondral bone. This bone nourishes the cartilage with oxygen, water, and nutrients conveyed through microscopic channels. This supply route carries “chondroprotective agents” from the bloodstream to the cartilage.
[0005] Cartilage is the supporting structure of the body, but has no blood vessels, nerves or lymphatics, and consists of thick bundles of fibrous protein (collagen) which are woven to form the articular surface. Proteoglycans fill the extracellular spaces not occupied by collagen, and are a combination of protein and sugar. Each proteoglycan subunit contains a protein core attached to hundreds of long chains of specially modified sugars called glycosaminoglycans (GAGS). Glucosamine is the single most important component and precursor for GAGs. Glucosamine is almost completely absorbed by the GI tract into the bloodstream. Cartilage rebuilding is only as good as its GAG synthesis. Chondrocytes in the cartilage obtain glucosamine from the subchondral blood vessels and manufacture N-acetylglucosamine (NAG) and glucuronic acid, which make hyaluronan, which is half glucosamine, and provides the lubricating ability of joints.
[0006] There is no definitive answer regarding the cause of osteoarthritis. A natural erosion of cartilage occurs with age, but excessive loads placed on joints, obesity, heredity, trauma, decreased circulation, poor bone alignment, and repetitive stress motion play a role. Osteoarthritis may also be the result of free radical damage, thought to be a major cause of many diseases, including the aging process, cancer, heart disease and degenerative diseases.
[0007] Free radicals affect the immune system causing rheumatoid arthritis and osteoarthritis. Free radicals are atoms or atomic groups that are byproducts of normal metabolism, tobacco smoke, pollutants, car exhaust, bacteria, radiation, and chemicals which oxidize or damage otherwise healthy cells. They damage DNA, corrode cell membranes, and may play a role in the development of cancer, heart and lung disease, cataracts, and cause or accelerate the aging process. Bucci wrote that there is conclusive evidence that free radicals do most of their damage in rheumatoid arthritis, but also to the cartilage in osteoarthritis. Bucci L. Healing Arthritis the Natural Way Arlington, Tex.: Summit Publishing Group, 1995, pp. 34-5. In his best seller, Theodosakis stated that “Osteoarthritis may be the result of free radical damage. And to make matters worse, joint inflammation itself may trigger an even faster rate of new free radical formation. Prevention of free radical damage is a critical feature in treating and preventing osteoarthritis.” Theodosakis J, Adderly B, Fox B. The Arthritis Cure New York, St. Martin's Press, 1997, p 147-9. Unless the damage caused by free radical formation is addressed, any benefits obtained by using only chondroprotective agents could be nullified; similar to trying to fill a sieve with water, the relief is transient but pathology progresses.
[0008] There is no known drug that claims to reverse osteoarthritis. Most therapeutic agents are directed at reducing the inflammation and relieving pain. Non-steroidal anti-inflammatory drugs (NSAIDs) are the first line of treatment for osteoarthritis, but long-term use can lead to gastric ulcers, kidney damage, hearing loss and even inhibit cartilage formation.
SUMMARY OF THE INVENTION
[0009] This invention relates to the composition and method of treating arthritis, repairing of articular joint surfaces and the relief of symptoms associated with arthritis. The nitric oxide synthase inhibitor reduces the level of nitric oxide, the free radical responsible for the degradation of articular cartilage. Amino sugars are the building blocks of articular cartilage and have anti-inflammatory actions.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0010] Osteoarthritis is thought to be the result of decreased production and increased degradation of the cartilaginous matrix. Loss of this protective layer leads to roughening and fissuring of the cartilage and may eventually cause erosion severe enough to expose the bone. The current goal of osteoarthritis therapy is the relief of pain. NSAID use is limited by the fact that they do not change the natural course of the disease and may accelerate joint deterioration in the long run.
Nitric Oxide Synthase Inhibitors
[0011] The maintenance of articular cartilage requires a balance between anabolic and catabolic processes. An increase in some cytokines, such as interleukin-1 (IL-1), is associated with a decrease in the synthesis and increase in the degradation of proteoglycans and collagens necessary for the structural integrity of the cartilaginous matrix. While cytokines, such as transforming growth factor β (TGF β), stimulates chondrocyte synthesis of collagens and proteoglycans, reduces the activity of IL-1-stimulated proteinases, and opposes the inhibitory and catabolic effects of IL-1.
[0012] Patients presenting with either rheumatoid arthritis (RA) or osteoarthritis (OA) have been observed to have increased levels of NO in the synovial fluid. A significant source of NO production in these patients appeared to be articular chondrocytes. Henrotin Y E, et al, Nitric oxide downregulates cytokines, J of Rheumatology 1998;25(8):1595-1601. Nitric oxide (NO) is produced by articular chondrocytes in large amounts for extended periods of time by an inducible form of nitric oxide synthase (NOS) in response to activation by IL-1 and other agents. An increase in NO decreases the synthesis of proteoglycans and type II collagen. If NO production is blocked with the use of N G -monomethyl-L-arginine (L-NMA), an inhibitor of NOS, inhibition of proteoglycan synthesis by IL-1β is blocked, and concentration of TGF β is increased. Studer R K, Georgescu H I, Miller L A, Evans C H, Inhibition of transforming growth factor β production by nitric oxide-treated chondrocytes, Arthritis & Rheumatism 1999;42(2): 248-257.
[0013] Nitric oxide is a short lived, gaseous free radical that is synthesized from the terminal guanidino nitrogen of L-arginine in an oxidation reaction catalyzed by NOS. NOS expression is inducible by endotoxin, cytokines, growth factor and immune complexes. The overexpression of NOS in rheumatoid arthritis (RA) may result from increased levels of tumor necrosis factor-α (TNF-α), IL-1β, and other proinflammatory cytokines characteristic of this disease. Chondrocytes from patients with OA and RA spontaneously over express NOS and produce elevated levels of NO. St. Clair E W, Nitric oxide—friend or foe in arthritis? J of Rheumatology 1998;25(8):1451-1453.
[0014] Canadian researchers reduced the progression of experimental osteoarthritis in dogs by inhibiting inducible nitric oxide synthase (NOS). Pelletier J P, et al. Arthritis & Rheumatism 1998;41:1275-1286. Pelletier reported that osteoarthritis cartilage produced an increased amount of nitric oxide (NO) due to an increased level of inducible nitric oxide synthase in cartilage chondrocytes. Nitric oxide plays an important role in autoimmunity and inflammation. Normal cartilage does not produce NO or express NOS unless stimulated with cytokines. In the joint, NO, produced in response to cytokine stimulation, exerts a number of catabolic effects on chondrocyte functions which would be expected to promote the degradation of articular cartilage. These effects of NO on chondrocytes include: inhibition of collagen and proteoglycan synthesis, activation of metalloproteinases, increased susceptibility to injury by other oxidants, inhibition of actin polymerization, and apoptosis. NSAIDs, such as aspirin, and to a lesser extent, sodium salicylate, and tetracycline inhibit the expression of NOS protein. Clancy R M, Amin A R, Abramson S B. Arthritis & Rheumatism 1998;41:1141-1151.
[0015] Nitric oxide synthase inhibitors which may be employed include, but are not limited to: arginine-based analogues such as methylated arginines, substituted L-arginine, nitro-arginine, L-N G -nitroarginine, N G -mono-methyl-L-arginine (NMA), N-nitro-L-arginine methyl ester, N-amino-L-arginine, N-methyl-L-arginine, N G -monomethyl-L-arginine (L-NMA), L-N G -mono-methyl-arginine (L-NMMA); flavoprotein binders such as diphenylene iodonium and related iodonium derivatives, ornithine and ornithine derivatives such as N-imino-ethyl-L-ornithine; tetracycline; L-canavanine; citrulline; redox dyes such as methylene blue; calmodulin binders such as trifluoropiperazine and calcinarin; heme binders; zinc compounds; tetrahydropterin analogs such as aminoguanidine; and depleters of biopterin such as methotrexate.
[0016] The use of NOS inhibitors is well known in the art. Dawson et al, U.S. Pat. No. 5,266,594, discloses a method of preventing or treating glutamate neurotoxicity with a NOS inhibitor capable of penetrating the blood brain barrier. Ahluwalia et al, U.S. Pat. No. 5,468,476, discloses a method of reducing hair growth with a NOS inhibitor. Wahl et al, U.S. Pat. No. 5,449,688, discloses a method for treating chronic inflammatory conditions by parenterally or intravenously administering a NOS inhibitor. Stamler et al, U.S. Pat. No. 5,545,614, discloses a method for stimulating skeletal muscle contractions with a NOS inhibitor. Moncada et al, U.S. Pat. No. 5,585,402, discloses a method for inhibiting tissue damage by using a NOS inhibitor to decrease NO production in vascular endothelial cells. Dunn et al, U.S. Pat. No. 5,665,757, discloses a method for treating anxiety using a NOS inhibitor. Mjalli et al, U.S. Pat. No. 5,723,451, discloses a method for inhibiting NOS using one of eleven formulations. None of the above cited patents teach or suggest the use of the composition and method outlined in the present invention.
Amino Sugars
[0017] Agents that may repair, or at the very least, slow the degradation of articular cartilage have been described as possessing chondroprotective properties. Examples of these agents include: heparinoids (Arteparon, Rumalon), hyaluronic acid, piroxicam, tetracyclines, corticosteroids, chondroitin, and glucosamine sulfate. Da Camara C C, Dowless G V. Annals of Pharmacotherapy 1998;32:580-7.
[0018] Glucosamine from exogenous sources (food and supplements) may stop the progression of cartilage degradation and stimulate the production of new cartilage. Glucosamine absorbed by the gastrointestinal tract undergoes significant first-pass metabolism in the liver, with the resulting 26% bioavailibility. It is incorporated into plasma proteins as a result of hepatic metabolism, and concentrates in the articular cartilage. Clinical improvement of symptoms has been seen as early as one week after oral administration of glucosamine sulfate and has persisted for up to four weeks after discontinuation. Barclay T S, Tsourounis C, McCart G M. Glucosamine. Annals of Pharmacotherapy 1998;32:574-79.
[0019] Several commercial forms of glucosamine are available, including the sulfate, hydrochloride, and N-acetylglucosamine (NAG). Glucosamine hydrochloride has a higher concentration of glucosamine than the sulfate form. NAG is rapidly metabolized to make proteins and provides less glucosamine for cartilage repair. The composition of the invention could include one or a combination of the glucosamine forms. Patients have reported a more rapid response with higher dosages of glucosamine, but the therapeutic results with glucosamine alone have not been consistent. The dosage range for glucosamine can vary from 500 mg to 3000 mg a day, in divided doses, depending on body weight and severity of symptoms. One approach is to take 1,500 mg of glucosamine daily until symptoms have decreased, then reduce the dosage to 1,000 mg for two weeks and eventually stop treatment after symptoms cease or stay on a maintenance dose of 500 mg per day.
[0020] Adverse effects reported from glucosamine are gastrointestinal, such as heartburn and epigastric pain. Because the half-life of glucosamine in the blood is relatively short, a sustained-release form of the compound could avoid the adverse effects and provide a more uniform blood level. Talent J M, Gracy R W. Clinical Therapy 1996;18(6):1184-90.
[0021] The use of amino sugars is well known in the art. Jacobi, U.S. Pat. No. 3,859,436, discloses a topical composition of glucose, fructose, glucosamine and desoxyribose and ribose. Prudden, U.S. Pat. No. 4,006,224, discloses a method for treating inflammatory disorders of the gastrointestinal tract with D-glucosamine. Meisner, U.S. Pat. No. 4,590,067, discloses a composition for the prevention and treatment of periodontal disease comprising, bone meal, tyrosine, glucosamine and ascorbic acid. Speck, U.S. Pat. No. 4,870,061, discloses a method for treating degenerative joint disease by buccal administration of N-acetylglucosamine. Kludas, U.S. Pat. No. 5,036,056, discloses a method for treating damaged connective tissue with a connective tissue matrix of collagens, proteoglycans, glycosaminoglycans and glycoproteins. Henderson, U.S. Pat. Nos. 5,364,845 and 5,587,363, discloses a composition for the repair of connective tissue comprising glucosamine, chondroitin sulfate and manganese. Williams et al, U.S. Pat. No. 5,679,344, discloses a composition for articular disorders comprising glucosamine and proteases. Diaz et al, U.S. Pat. Nos. 5,795,576 and 5,891,441, discloses a composition and method for the elimination of undigested fat prior to digestion comprising, psyllium, glucosamine, glucomannan, apple pectin and stearic acid. Murad, U.S. Pat. No. 5,804,594, discloses an oral composition for improving skin conditions comprising, N-acetylglucosamine, ascorbic acid, amino acids, and a transition methal composition. Florio, U.S. Pat. No. 5,840,715, discloses a composition of nutritional supplements of gamma linolenic acid, eicosapentaenoic acid and docosahexaneoic acid, chondroitin sulfate, N-acetylglucosamine sulfate, glucosamine sulfate and manganese aspartate. Platt, U.S. Pat. No. 5,891,861, discloses a composition of oligomers of beta glucosamine to treat fungal diseases. Weisman, U.S. Pat. No. 5,888,514, discloses a composition of natural ingredients for treating bone and joint inflammation usingshark cartilage, glucosamine, herbs and enzymes. None of the above cited patents teach or suggest the composition or method outlined in the present invention.
[0022] Chondroitin sulfate is the major GAG in cartilage, and has a synergistic effect with glucosamine, but poorly absorbed by oral administration. Chondroitin sulfate is half galactosamine, which is made directly from glucosamine, and has great water retaining ability. Dosage range of chondroitin sulfate is 250 mg to 1,000 mg per day in divided doses. Morrison, U.S. Pat. No. 3,895,107, discloses a method of inhibiting atherosclerotic lesions by administering chondroitin sulfate. Walton et al, U.S. Pat. No. 4,489,065, discloses the binding of drugs to chondroitin for the controlled release of the drug. None of the above cited patents teach or suggest the use of the composition and method outlined in the present invention.
Zinc Compounds
[0023] Zinc plays a physiological role in the regulation of bone metabolism, by stimulating bone formation and mineralization and an inhibitory effect on bone resorption. Zinc activates aminoacyl-tRNA synthetase in osteoblastic cells, stimulates cellular protein synthesis, and inhibits osteoclast-like cell formation in marrow cells. Bone zinc content is decreased by development, with aging, skeletal unloading, and postmenopausal conditions. Zinc plays a role in the preservation of bone mass. Most zinc compounds, such as zinc sulfate, are useful for the prevention of osteoporosis, but a recent study confirmed that β-Alanyl-L-histidinato zinc (AHZ) has a potent effect on bone formation and calcification. Yamaguchi M, Role of Zinc in Bone Formation and Bone Resporption, J. of Trace Elements and Experimental Medicine 1998;11:119-135.
[0024] Zinc compounds have anti-inflammatory and anti-infective properties. In a recent published article, Petrus E J et al., Current Therapeutic Research , 1998;59/9:595-607, the inventor served as chief investigator for a randomized, double-masked, placebo-controlled clinical study of the effectiveness of zinc acetate lozenges on common cold symptoms in allergy-tested subjects. Those subjects who used the zinc lozenges had both a shorter duration and severity of common cold symptoms. Those subjects who were positive for allergies, were more responsive to zinc by having a shorter duration of nasal symptoms. The study cited many references that reported the benefits and effects of zinc compounds.
[0025] Zinc is an essential mineral found in every form of life on earth. Unlike other metals, zinc is virtually nontoxic. Zinc and its compounds have long been recognized as possessing certain therapeutic functions. Zinc compounds are acknowledged as astringents and beneficial in wound healing, reducing inflammation, and has antimicrobial, antifungal and antiviral activity. Zinc is the active agent in formulations to treat diaper rash, decubitus ulcers, and abrasions. Zinc stabilizes the cell membranes and inhibits the formation of free radicals. Zinc also strengthens the integrity of blood vessel walls by reducing the membrane permeability and stopping bleeding.
[0026] Zinc has an inhibitory effect on the release of histamine from mast cells due to its stabilizing effect of the mast cell membrane. Mast cells isolated from specimens of atherosclerotic plaques contained matrix metalloproteinase type 9, one of the enzymes that can produce collagen degradation. Kovanen Pt, et al. J. Am College of Cardiology 1998;32:606-612. The inhibitory effect of zinc on allergy and immunology make it an excellent enhancement to glucosamine and chondroitin therapy. Zinc is also a very potent inhibitor of nitric oxide synthase (NOS). Cuajungco M P, Lees G J Neurobiol Disease 1997;4(3-4):137-69.
[0027] In a preferred form of the invention, the composition uses a zinc salt such as zinc acetate, with the dosage range of 30 to 60 mg per day in divided doses. Zinc salts are selected from a group consisting of, but not limited to: zinc sulfate, zinc chloride, zinc acetate, zinc phenol sulfonate, zinc borate, zinc bromide, zinc nitrate, zinc glycerophosphate, zinc benzoate, zinc carbonate, zinc citrate, zinc hexafluorosilicate, zinc diacetate trihydrate, zinc oxide, zinc peroxide, zinc salicylate, zinc silicate, zinc stannate, zinc tannate, zinc titanate, zinc tetrafluoroborate, zinc gluconate, and zinc glycinate.
[0028] Zinc acetate is absorbed throughout the small intestine and has an excellent safety profile. It does not adversely alter serum albumin, bilirubin, aminotransferases, hematologic variables, iron metabolism or renal function indices. Zinc acetate has been assigned to FDA pregnancy category A, indicating that the possibility of fetal abnormalities appears remote. In several trials, no toxic adverse effects have been reported in any patient. The most common adverse effect of zinc therapy is gastrointestinal irritation, which is reported to occur in approximately 10% of patients. Anderson L A, Hakojarvi A L, Boudreaux S K. Annals of Pharmacotherapy 1998;32:78-87. A controlled-release formulation could reduce GI irritation and enhance absorption.
[0029] Although any suitable route of administration may be employed for providing the subject with an effective dosage of the composition according to the methods of the present invention, oral administration is preferred. Suitable routes include, for example, oral, rectal, parenteral, intravenous, topical, transdermal, subcutaneous, intramuscular, and like forms ofadministration may be employed. Suitable dosage forms include tablets, troches, dispersions, suspensions, solutions, capsules, patches, suppositories, creams, ointments, gels, and the like, although oral dosage forms are preferred. A topical composition, with a permeation enhancing amount of at least one penetration enhancer, in an appropriate pharmaceutical carrier, could be in the form of a gel, ointment, cream, solution or other means.
Enteric Coating
[0030] The use of pharmaceutical controlled release methods to deliver the composition to the gastrointestinal tract with a desired level of nitric oxide synthase inhibitors, amino sugars and other agents without the adverse gastrointestinal effects is well known in the art.
[0031] Enteric coatings are pH sensitive polymers designed to remain intact in the acidic environment of the stomach, but to dissolve in the more alkaline environment of the intestine. Some enteric coatings use blends of cellulose acetate phthalate polymers. Wu et al, U.S. Pat. No. 5,356,634 discloses an enteric coating composition of cellulose acetate phthalate (CAP) and cellulose acetate trimellitate polymers. Crook et al, U.S. Pat. No. 5,723,151 discloses a composition of cellulose acetate phthalate polymer and organic solvent. Some enteric coatings use polyvinylpyrrolidone (PVP). Sipos, U.S. Pat. No. 4,079,125 discloses a binder and stabilizer of PVP and a coating of CAP and diethyl phthalate. Patell, U.S. Pat. No. 4,775,536 discloses the use of an enteric polymer of an acrylic resin and an undercoat and overcoat of PVP. Hodges et al, U.S. Pat No. 5,225,202 discloses an enteric coated composition of hydroxypropylmethyl cellulose phthalate, a plasticizer of triethyl citrate and talc as an anti-adherent.
[0032] Some polymers commonly used for enteric coatings are cellulose acetate phthalate (CAP), hydroxypropyl methylcellulose phthalate (HPMCP), cellulose acetate trimellitate (CAT), hydroxypropyl methylcellulose acetate succinate (HPMCAS), polyvinyl acetate phthalate (PVAP) and acrylic resins. One formulation of the present invention uses 7 mg of polyvinylpirrolidone to coat the immunostimulant composition. The composition can be in the form of a tablet, capsule, granules, or pill for oral administration. Disintegration of the PVP enteric coating occurs in approximately 40 minutes, about the time the composition is in the intestine.
[0033] In addition to nitric oxide synthase inhibitors and amino sugars, the following active agents may supplement the composition to promote the development and maintenance of cartilage, include but are not limited to: vitamins, A, B, C, E; minerals, selenium, silica, manganese, magnesium, copper and boron; glycosaminoglycans; analgesics, anti-inflammatory agents, methyl-sulfonyl-methane, S-adenosyl-methionine, alpha-lipoic acid, aloe vera extract, preservatives, antioxidants, stabilizers, surfactants, anti-infective agents, adjuvants, anthocyanidins, proanthocyanidins, and herbal derivatives.
[0034] In a further aspect of this invention, for those who have difficulty swallowing a large tablet, due to esophageal strictures or other pathology, a therapeutically effective solution can be administered by a suspension of the active agents in a pharmaceutically acceptable carrier to provide a liquid form to be swallowed or sprayed onto the oral mucosa. By a “pharmaceutically acceptable carrier” is meant a composition, solvent, dispersion medium, coating, delivery vehicle or the like, which can be employed to administer the compositions of the present invention without undue adverse physiological effects.
[0035] Although illustrative embodiments of the invention have been shown and described, a wide range of modifications, change, and substitution is contemplated in the foregoing disclosure and in some instances, some features of the present invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention. The above-mentioned patents are hereby incorporated by reference.
[0036] This invention is further illustrated by the following examples which are to be regarded as illustrative only, and in no way limit the scope of the invention.
EXAMPLE 1
[0037] A 58 year old male with diagnosed osteoarthritis of both knees was started on a commercial composition of glucosamine hydrochloride 500 mg and chondroitin sulfate 400 mg taken three times a day for six months. The relief from pain and limitation of motion was inconsistent. A new composition, of the invention, comprising zinc acetate 20 mg and glucosamine sulfate 500 mg coated with polyvinylpirrolidone 7 mg taken three times a day was commenced. By the 21 st day of treatment with the new formulation, the knee pain subsided and range of motion was unrestricted. A maintenance dose of glucosamine sulfate 500 mg and zinc acetate 10 mg was then continued for six months and the pain relief and range of motion of the knees were maintained.
EXAMPLE 2
[0038] A 59 year old male with diagnosed osteoarthritis of the right foot with severe pain on running. He started on a commercial composition of a glucosamine complex (glucosamine hydrochloride, N-Acetylglucosamine and glucosamine sulfate) 500 mg and chondroitin sulfate 400 mg, taken three times a day for three months. The pain relief was inconsistent and required supplemental analgesics in order to obtain relief. A new composition, of the invention, comprising zinc acetate 20 mg and glucosamine sulfate 500 mg coated with polyvinylpirrolidone 7 mg taken three times a day was commenced. By the second week of treatment with the new formulation, the foot pain subsided and he was able to run and resume his tennis playing. A maintenance dose of glucosamine sulfate 500 mg and zinc acetate 10 mg was then continued for five months and the pain relief and ability to run and play sports continued.
EXAMPLE 3
[0039] A 12 year old Weimaraner developed weakness of his hind legs which limited his ability to jump and lift his leg to urinate. He was evaluated by the College of Veterinary Medicine at Texas A&M University and started on prednisone 20 mg per day but with limited success. He was then started on the new composition, of the invention, comprising zinc acetate 20 mg and glucosamine sulfate 500 mg coated with polyvinylpirrolidone 7 mg taken twice a day. After three weeks of treatment with the new formulation, he demonstrated increased strength of his hind legs and regained his ability to lift his leg on urinating and no pain on deep palpation of the hips. He was then maintained on glucosamine sulfate 500 mg and zinc acetate 10 mg, twice a day for 11 months until his death. While on the maintenance dose he continued to demonstrate strength in his hind legs.
[0040] Although illustrative embodiments of the invention have been shown and described, a wide range of modifications, change, and substitution is contemplated in the foregoing disclosure and in some instances, some features of the present invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention. | 4y
|