Patent Grant
9513039
Field of the Invention
This invention generally relates to a heat exchanger adapted to be used in a vapor compression system. More specifically, this invention relates to a heat exchanger including a refrigerant distributor having a first tray part and a plurality of second tray parts.
Background Information
Vapor compression refrigeration has been the most commonly used method for air-conditioning of large buildings or the like. Conventional vapor compression refrigeration systems are typically provided with an evaporator, which is a heat exchanger that allows the refrigerant to evaporate from liquid to vapor while absorbing heat from liquid to be cooled passing through the evaporator. One type of evaporator includes a tube bundle having a plurality of horizontally extending heat transfer tubes through which the liquid to be cooled is circulated, and the tube bundle is housed inside a cylindrical shell. There are several known methods for evaporating the refrigerant in this type of evaporator. In a flooded evaporator, the shell is filled with liquid refrigerant and the heat transfer tubes are immersed in a pool of the liquid refrigerant so that the liquid refrigerant boils and/or evaporates as vapor. In a falling film evaporator, liquid refrigerant is deposited onto exterior surfaces of the heat transfer tubes from above so that a layer or a thin film of the liquid refrigerant is formed along the exterior surfaces of the heat transfer tubes. Heat from walls of the heat transfer tubes is transferred via convection and/or conduction through the liquid film to the vapor-liquid interface where part of the liquid refrigerant evaporates, and thus, heat is removed from the water flowing inside of the heat transfer tubes. The liquid refrigerant that does not evaporate falls vertically from the heat transfer tube at an upper position toward the heat transfer tube at a lower position by force of gravity. There is also a hybrid falling film evaporator, in which the liquid refrigerant is deposited on the exterior surfaces of some of the heat transfer tubes in the tube bundle and the other heat transfer tubes in the tube bundle are immersed in the liquid refrigerant that has been collected at the bottom portion of the shell.
Although the flooded evaporators exhibit high heat transfer performance, the flooded evaporators require a considerable amount of refrigerant because the heat transfer tubes are immersed in a pool of the liquid refrigerant. With recent development of new and high-cost refrigerant having a much lower global warming potential (such as R1234ze or R1234yf), it is desirable to reduce the refrigerant charge in the evaporator. The main advantage of the falling film evaporators is that the refrigerant charge can be reduced while ensuring good heat transfer performance. Therefore, the falling film evaporators have a significant potential to replace the flooded evaporators in large refrigeration systems.
In general, the rate of heat transfer between a surface (e.g., a surface of a heat transfer tube) and a substance (e.g., refrigerant) in a liquid state is much greater than the rate of heat transfer between the surface and the same substance in a gaseous state. Therefore, it is important for effective and efficient heat transfer performance to keep the tubes in the evaporator covered, or wetted, with liquid refrigerant during operation. With a flooded evaporator in which the tubes are immersed in a pool of the liquid refrigerant, performance of the evaporator can be maintained without significant degradation by controlling the liquid level within the evaporator shell even when the refrigerant circulation condition fluctuates. However, in a falling film evaporator, if all of refrigerant evaporates at an upper region of the tube bundle before it reaches a lower region, the lower tubes are left unwetted, thereby incapable of affecting heat transfer. Therefore, it is especially important in a falling film evaporator that there be a sufficient flow of liquid refrigerant over the tube bundle even when the refrigerant circulation condition fluctuates.
U.S. Patent Application Publication No. 2009/0178790 discloses a falling film evaporator including a refrigerant distribution assembly having an outer distributor and an inner distributor disposed within the outer distributor. Two-phase vapor-liquid refrigerant from a condenser first flows in the inner distributor. Vapor component of the two-phase refrigerant is discharged from the inner distributor into the outer distributor via a plurality of apertures formed in an upper portion of the inner distributor. A bottom portion of the inner distributor includes a plurality of openings through which the liquid component of the two-phase refrigerant is discharged into the outer distributor. The outer distributor has a plurality of apertures formed in lateral walls of the outer distributor to permit vapor refrigerant to flow from the outer distributor into a space within a hood enclosing the refrigerant distribution assembly. Liquid refrigerant collects in a bottom portion of the outer distributor and flows through distribution devices, such as nozzles, holes, openings, valves, etc., onto a tube bundle disposed below the refrigerant distribution assembly. Thus, with the refrigerant distribution assembly disclosed in this publication, vapor refrigerant is separated from liquid refrigerant, and only liquid refrigerant is discharged from the distribution devices toward the tube bundle.
U.S. Pat. No. 5,588,596 discloses a falling film evaporator including a vapor-liquid separator and a spray tree distribution system. The two-phase refrigerant from an expansion valve enters the vapor-liquid separator where the refrigerant is separated into vapor and liquid. The drain of the vapor-liquid separator is in fluid communication with and positioned above the spray tree distribution system which, in turn, is located above a tube bundle. The spray tree distribution system includes a manifold and a series of horizontal distribution tubes, each of which lies parallel to, in close proximity to, and directly above one uppermost tube of the tube bundle.
In a refrigerant distribution system that separates vapor refrigerant from liquid refrigerant and distributes only liquid refrigerant toward the tube bundle, a copious amount of refrigerant charge is required in order to ensure a sufficient flow of liquid refrigerant over the tube bundle so that all of the tubes remain wetted during operation. For example, in the refrigerant distribution assembly disclosed in U.S. Patent Application Publication No. 2009/0178790, levels (heights) of liquid refrigerant accumulated in both the inner distributor and the outer distributor are relatively high. Therefore, such a distribution system requires a relatively large amount of refrigerant charge. On the other hand, in the distribution system utilizing the spray tree distribution system disclosed in U.S. Pat. No. 5,588,596, the number and size of spray orifices formed in the distribution tubes need to be precisely controlled in view of a distribution flow amount and pressure loss due to the pipe length of the distribution tubes, and thus, structural complexity of the spray distribution system increases manufacturing cost. Moreover, the use of distribution tubes causes a higher pressure loss in the distribution system. Furthermore, distribution of the liquid refrigerant may become uneven due to reduced refrigerant flow rate when the evaporator operates under part-load condition.
More specifically, load of the vapor compression system fluctuates between, for example, 25% to 100%, and thus, the circulation amount of the refrigerant in the vapor compression system also fluctuates depending on operating conditions. In recent years, demand for better performance during part-load condition as well as during rated load condition has increased. With the flooded evaporator, performance of the evaporator can be maintained without significant degradation by controlling the liquid level within the evaporator shell even when the circulation amount of the refrigerant decreases under part-load condition. However, with the falling film evaporator, when the refrigerant distributed over the tube bundle decreases due to decrease in the circulation amount of the refrigerant, distribution of the refrigerant within the distributor system may become uneven, which could cause formation of dry patches in the tube bundle. Moreover, the evaporator may not be installed completely level, which could aggravate uneven distribution of the refrigerant over the tube bundle.
In view of the above, one object of the present invention is to provide a heat exchanger having a refrigerant distribution system that can reduce the amount of refrigerant charge while ensuring uniform distribution of the refrigerant over a heat transfer unit.
Another object of the present invention is to provide a heat exchanger having a refrigerant distribution system that promotes uniform distribution of the refrigerant over the heat transfer unit even when the evaporator is not completely level.
A heat exchanger according to one aspect of the present invention is adapted to be used in a vapor compression system, and includes a shell, a refrigerant distribution assembly and a heat transferring unit. The shell has a longitudinal center axis extending generally parallel to a horizontal plane. The refrigerant distribution assembly includes an inlet part, a first tray part, and a plurality of second tray parts. The inlet part is disposed inside of the shell and having at least one opening for discharging a refrigerant. The first tray part is disposed inside of the shell and continuously extending generally parallel to the longitudinal center axis of the shell to receive the refrigerant discharged from the opening of the inlet part. The first tray part has a plurality of first discharge apertures. The second tray parts are disposed inside of the shell below the first tray part to receive the refrigerant discharged from the first discharge apertures such that the refrigerant accumulated in the second tray parts does not communicate between the second tray parts. The second tray parts are aligned along a direction generally parallel to the longitudinal center axis of the shell, each of the second tray parts having a plurality of second discharge apertures. The heat transferring unit is disposed inside of the shell below the second tray parts so that the refrigerant discharged from the second discharge apertures of the second tray parts is supplied to the heat transferring unit.
A heat exchanger according to another aspect of the present invention is adapted to be used in a vapor compression system, and includes a shell, a refrigerant distribution assembly, and a heat transferring unit. The shell has a longitudinal center axis extending generally parallel to a horizontal plane. The refrigerant distribution assembly includes an inlet part, a first distribution part and a second distribution part. The inlet part discharges a refrigerant. The first distribution part accumulates the refrigerant discharged from the inlet part and for discharging the refrigerant downwardly. The second distribution part accumulates the refrigerant discharged from the first distribution part such that the refrigerant is divided into a plurality of portions that do not communicate with each other, and for discharging the refrigerant in each of the portions downwardly, a height of the refrigerant accumulated in the second distribution part being smaller than a height of the refrigerant accumulated in the first distribution part. The heat transferring unit performs heat transfer by using the refrigerant discharged from the second distribution part.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments.
Referring now to the attached drawings which form a part of this original disclosure:
Selected embodiments of the present invention will now be explained with reference to the drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
Referring initially to
As shown in
The evaporator 1 is a heat exchanger that removes heat from the liquid to be cooled (in this example, water) passing through the evaporator 1 to lower the temperature of the water as a circulating refrigerant evaporates in the evaporator 1. The refrigerant entering the evaporator 1 is in a two-phase gas/liquid state. The liquid refrigerant evaporates as the vapor refrigerant in the evaporator 1 while absorbing heat from the water.
The low pressure, low temperature vapor refrigerant is discharged from the evaporator 1 and enters the compressor 2 by suction. In the compressor 2, the vapor refrigerant is compressed to the higher pressure, higher temperature vapor. The compressor 2 may be any type of conventional compressor, for example, centrifugal compressor, scroll compressor, reciprocating compressor, screw compressor, etc.
Next, the high temperature, high pressure vapor refrigerant enters the condenser 3, which is another heat exchanger that removes heat from the vapor refrigerant causing it to condense from a gas state to a liquid state. The condenser 3 may be an air-cooled type, a water-cooled type, or any suitable type of condenser. The heat raises the temperature of cooling water or air passing through the condenser 3, and the heat is rejected to outside of the system as being carried by the cooling water or air.
The condensed liquid refrigerant then enters through the expansion device 4 where the refrigerant undergoes an abrupt reduction in pressure. The expansion device 4 may be as simple as an orifice plate or as complicated as an electronic modulating thermal expansion valve. The abrupt pressure reduction results in partial evaporation of the liquid refrigerant, and thus, the refrigerant entering the evaporator 1 is in a two-phase gas/liquid state.
Some examples of refrigerants used in the vapor compression system are hydrofluorocarbon (HFC) based refrigerants, for example, R-410A, R-407C, and R-134a, hydrofluoro olefin (HFO), unsaturated HFC based refrigerant, for example, R-1234ze, and R-1234yf, natural refrigerants, for example, R-717 and R-718, or any other suitable type of refrigerant.
The vapor compression system includes a control unit 5 that is operatively coupled to a drive mechanism of the compressor 2 to control operation of the vapor compression system.
It will be apparent to those skilled in the art from this disclosure that conventional compressor, condenser and expansion device may be used respectively as the compressor 2, the condenser 3 and the expansion device 4 in order to carry out the present invention. In other words, the compressor 2, the condenser 3 and the expansion device 4 are conventional components that are well known in the art. Since the compressor 2, the condenser 3 and the expansion device 4 are well known in the art, these structures will not be discussed or illustrated in detail herein. The vapor compression system may include a plurality of evaporators 1, compressors 2 and/or condensers 3.
Referring now to
The refrigerant distribution assembly 20 is configured and arranged to serve as both a gas-liquid separator and a refrigerant distributor. As shown in
As shown in
As shown in
As shown in
As shown in
In
As shown in
The heat transfer tubes 31 are configured and arranged to perform falling film evaporation of the liquid refrigerant. More specifically, the heat transfer tubes 31 are arranged such that the liquid refrigerant discharged from the refrigerant distribution assembly 20 forms a layer (or a film) along an exterior wall of each of the heat transfer tubes 31, where the liquid refrigerant evaporates as vapor refrigerant while it absorbs heat from the water flowing inside the heat transfer tubes 31. As shown in
Referring now to
In the first embodiment, the first tray part 22 and the second tray parts 23 are preferably arranged such that a height of the liquid refrigerant accumulated in the first tray part 22 is larger than a height of the liquid refrigerant accumulated in the second tray parts 23 when the evaporator 1 is in use. In other words, the size and number of the first discharge apertures 22a of the first tray part 22 and the second discharge apertures 23a of the second tray part 23 are adjusted to achieve the desired heights of the liquid refrigerant in the first tray part 22 and the second tray part 23. More specifically, a total cross-sectional area of the first discharge apertures 22a of the first tray part 22 and the a total cross-sectional area of the second discharge apertures 23a of the second tray part 23 are set so that the height of the liquid refrigerant accumulated in the first tray part 22 is larger than the height of the liquid refrigerant accumulated in the second tray parts 23 while maintaining the flow rate of the liquid refrigerant discharged from the first discharge apertures 22a and the flow rate of the liquid refrigerant discharged from the second discharge apertures 23a generally the same. Since the volume of the liquid refrigerant accumulated in the second tray parts 23 can be reduced according to the first embodiment, an overall charge of refrigerant can be reduced without degrading the heat transfer performance of the evaporator 1. Moreover, with the arrangement according to the first embodiment, even when the evaporator 1 is not completely level, the liquid refrigerant can be substantially evenly distributed from the refrigerant distribution assembly 20 onto the tube bundle 30 as described in more detail below.
One example of a method for determining the total cross-sectional area of the first discharge apertures 22a of the first tray part 22 and the total cross-sectional area of the second discharge apertures 23a of the second tray part 23 will be explained with reference to
When liquid in a container is discharged from an aperture formed in the container, a flow rate of the liquid discharged from the aperture is expressed by the following Equations (1) and (2).
Q=AV Equation (1)
V=C√{square root over (2gh)} Equation (2)
In Equations (1) and (2), “Q” represents the flow rate of the liquid discharged from the aperture, “A” represents a cross-sectional area of the aperture, “V” represents a flow velocity of the liquid discharged from the aperture, “h” represents a height of the liquid in the container, and “C” represents a prescribed correction coefficient. Thus, the flow rate Q of the liquid discharged from the aperture is a function of the cross-sectional area A of the aperture and the height h of the liquid in the container.
Therefore, by adjusting the total cross-sectional area of the first discharge apertures 22a and the total-cross sectional area of the second discharge apertures 23a, the height of the liquid refrigerant in the first tray part 22 and the height of the liquid refrigerant in each of the second tray parts 23 can be adjusted while maintaining substantially the same discharge flow rate from the first tray part 22 and the second tray parts 23. In general, it is preferable to set the height of the liquid refrigerant in the first tray part 22 and the height of the liquid refrigerant in the second tray parts 23 to the smallest possible value that achieves the desired flow rate throughout the various operating conditions, thereby reducing the refrigerant charge as much as possible. Thus, if the evaporator 1 is installed on a completely level surface, and if distribution of the liquid refrigerant from the inlet pipe part 21 is substantially even, it is preferable to set each of the total cross-sectional area of the first discharge apertures 22a and the total-cross sectional area of the second discharge apertures 23a to the largest possible value for achieving the desired flow rate throughout the various operating conditions so that the height of the liquid refrigerant in the first tray part 22 and the height of the liquid refrigerant of the second tray part 23 are kept small.
However, since the refrigerant entering into the inlet pipe part 21 is in a two-phase state, it is difficult to distribute the two-phase refrigerant evenly along the longitudinal direction from the inlet pipe part 21 to the first tray part 22. Moreover, it is very difficult to install the evaporator 1 completely level, and the longitudinal center axis C of the evaporator 1 may be slightly tilted with respect to the horizontal plane. When the evaporator 1 is slightly tilted, a height difference is created between the longitudinal ends of the evaporator 1. For example, if the evaporator 1 has an overall longitudinal length of about 3 meters, and is installed such that the longitudinal center axis C is inclined with respect to the horizontal plane at an inclination of 3/1000 rad (which is usually the maximum allowable inclination for installation), a height difference between the longitudinal ends of the evaporator is about 9 mm. In such a case, as shown in
However, when there is a height difference in the liquid refrigerant accumulated in the first tray part 22 due to inclination of the evaporator 1 as shown in
Accordingly, the total cross-sectional area of the first discharge apertures 22a is preferably set to strike a balance between suppressing the variation in the flow rate Q and keeping the height h of the liquid refrigerant as small as possible. In the first embodiment of the present invention, the total cross-sectional area of the first discharge apertures 22a is set so that the variation in the flow rate Q does not exceed more than 10% when there is a height difference in the liquid refrigerant accumulated in the first tray part 22, while the average height of the liquid refrigerant is kept as small as possible. It will be apparent to those skilled in the art from this disclosure that the optimal total cross-sectional area of the first discharge apertures 22a varies according to the size and capacity (i.e., maximum flow rate) of the individual evaporator. For instance, in the example shown in
The same principle as explained above applies when determining the total cross-sectional area of the second apertures 23a of the second tray part 23. However, since the longitudinal length of each of the second tray parts 23 is shorter than the first tray part 22, a height difference in the liquid refrigerant accumulated in each of the second tray parts 23 from one side to the other is smaller than that of the first tray part 22. Therefore, the height of the liquid refrigerant accumulated in each of the second tray parts 23 can be kept smaller than that of the first tray part 22.
Similarly, when there are provided three second tray parts 23 with each of the second tray parts 23 having a longitudinal length that is about one-third of the longitudinal length of the first tray part 22, a height difference in the liquid refrigerant accumulated in each of the second tray parts 23 from one side to the other is reduced to 3 mm. Therefore, the total cross-sectional area of the second discharge apertures 23a can be further enlarged so that an average height of the liquid refrigerant in each of the second tray sections 23 is about 14 mm, while maintaining the variation in the flow rate Q at about 10%. When there are provided four second tray parts 23 with each of the second tray parts 23 having a longitudinal length that is about one quarter of the longitudinal length of the first tray part 22, a height difference in the liquid refrigerant accumulated in each of the second tray parts 23 from one side to the other is reduced to 2.25 mm. Therefore, the total cross-sectional area of the second discharge apertures 23a can be further enlarged so that an average height of the liquid refrigerant in each of the second tray sections 23 is about 11 mm, while maintaining the variation in the flow rate Q at about 10%. When there are provided five second tray parts 23 with each of the second tray parts 23 having a longitudinal length that is about one-fifth of the longitudinal length of the first tray part 22, a height difference in the liquid refrigerant accumulated in each of the second tray parts 23 from one side to the other is reduced to 3 mm. Therefore, the total cross-sectional area of the second discharge apertures 23a can be enlarged so that an average height of the liquid refrigerant in each of the second tray sections 23 is about 9 mm, while maintaining the variation in the flow rate Q at about 10%.
As shown in
Accordingly, with the refrigerant distribution assembly 20 according to the first embodiment, even when distribution of the two-phase refrigerant from the inlet pipe part 21 to the first tray part 22 is not uniform, the liquid refrigerant is accumulated in the first tray part 22, which continuously extends in the longitudinal direction. Therefore, unevenness in the distribution of the liquid refrigerant from the inlet pipe part 21 is mitigated by the first tray part 22. Moreover, since a relatively large amount of the liquid refrigerant is accumulated in the first tray part 22, variation in the flow rate of the liquid refrigerant discharged from the first tray part 22 can be suppressed even when the evaporator 1 is not level. Furthermore, since a plurality of the second tray parts 23 are provided, the height of the liquid refrigerant accumulated in each of the second tray parts 23 can be reduced while maintaining the variation in the flow rate of the liquid refrigerant from the second tray parts 23 at or below a prescribed level (e.g., 10%). Accordingly, the refrigerant charge can be reduced while ensuring good heat transfer performance. Furthermore, the pressure loss in the refrigerant distribution assembly 20 can be reduced by using the first tray section 22 and the second tray sections 23 instead of pipes or tubes for distributing the liquid refrigerant.
In the above described embodiment, the second tray parts 23 are arranged as separate bodies that are spaced apart from each other. A longitudinal distance between the second tray parts 23 is set to be small enough so as not to form a gap in continuous distribution of the liquid refrigerant with respect to the longitudinal direction. Alternatively, the second tray parts 23 may be formed integrally as shown in
Moreover, in the first embodiment, the first discharge apertures 22a and the second discharge apertures 23a are illustrated as circular holes. However, the shape and configuration of the first discharge apertures 22a and the second discharge apertures 23a are not limited to a simple circular hole, and any suitable opening may be utilized as the first discharge apertures 22a and the second discharge apertures 23a.
An evaporator 1A according to a modified example of the first embodiment may be provided with a refrigerant recirculation system. More specifically, as shown in
Furthermore, an evaporator 1B according to another modified example of the first embodiment may be arranged as a hybrid evaporator that includes a falling film section and a flooded section as shown in
Referring now to
The evaporator 101 of the second embodiment is basically the same as the evaporator 1 of the first embodiment except that an intermediate tray part 60 is provided between the heat transfer tubes 31 in the supply line group of a tube bundle 130 and the heat transfer tubes 31 in the return line group of the tube bundle 130. The intermediate tray part 60 includes a plurality of discharge apertures 60a through which the liquid refrigerant is discharged downwardly. The discharge apertures 60a may be coupled to spray nozzles or the like that apply refrigerant in a predetermined pattern, such as a jet pattern, onto the heat transfer tubes 31 disposed below the discharge apertures 60a.
As discussed above, the evaporator 101 incorporates a two pass system in which the water first flows inside the heat transfer tubes 31 in the supply line group, which is disposed in a lower region of the tube bundle 130, and then is directed to flow inside the heat transfer tubes 31 in the return line group, which is disposed in an upper region of the tube bundle 130. Therefore, the water flowing inside the heat transfer tubes 31 in the supply line group near the inlet water chamber 13a has the highest temperature, and thus, a greater amount of heat transfer is required. For example, as shown in
Therefore, in the second embodiment, the intermediate tray part 60 is disposed at a location above the heat transfer tubes 31 which requires a greater amount of heat transfer. The liquid refrigerant falling from above is once received by the intermediate tray part 60, and redistributed evenly toward the heat transfer tubes 31 disposed below the intermediate tray part 60, which requires a greater amount of heat transfer. Accordingly, these portions of the heat transfer tubes 31 are prevented from drying up, and heat transfer can be efficiently performed by using substantially all surface areas of the exterior walls of the heat transfer tubes 31 in the tube bundle 130.
The total cross-sectional are of the discharge apertures 60a of the intermediate tray part 60 is preferably determined as explained above to strike a balance between suppressing the variation in the flow rate and keeping the height of the liquid refrigerant as small as possible.
Although, in
In the second embodiment, the refrigerant may be directly supplied to the intermediate tray part 60. In such a case, the portions of the heat transfer tubes 31 disposed below the intermediate tray part 60 can be reliable wetted by ensuring sufficient amount of the refrigerant is supplied to the intermediate tray part.
For example, as shown in
Moreover, as shown in
Moreover, an evaporator 101C may include the refrigerant recirculation system that directly supplies the recirculated refrigerant only to the intermediate tray part 60 as shown in
Furthermore, as shown in
In understanding the scope of the present invention, the term “comprising” and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. Also, the terms “part,” “section,” “portion,” “member” or “element” when used in the singular can have the dual meaning of a single part or a plurality of parts. As used herein to describe the above embodiments, the following directional terms “upper”, “lower”, “above”, “downward”, “vertical”, “horizontal”, “below” and “transverse” as well as any other similar directional terms refer to those directions of an evaporator when a longitudinal center axis thereof is oriented substantially horizontally as shown in
While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired. Components that are shown directly connected or contacting each other can have intermediate structures disposed between them. The functions of one element can be performed by two, and vice versa. The structures and functions of one embodiment can be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Every feature which is unique from the prior art, alone or in combination with other features, also should be considered a separate description of further inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
| Number | Name | Date | Kind |
|---|---|---|---|
| 939143 | Lillie | Nov 1909 | A |
| 5588596 | Hartfield et al. | Dec 1996 | A |
| 5645124 | Hartfield et al. | Jul 1997 | A |
| 6167713 | Hartfield et al. | Jan 2001 | B1 |
| 6253571 | Fujii et al. | Jul 2001 | B1 |
| 6606882 | Gupte | Aug 2003 | B1 |
| 6830099 | Moeykens | Dec 2004 | B2 |
| 6868695 | Dingel et al. | Mar 2005 | B1 |
| 7849710 | De Larminat et al. | Dec 2010 | B2 |
| 20020162352 | Ring et al. | Nov 2002 | A1 |
| 20080149311 | Liu et al. | Jun 2008 | A1 |
| 20090178790 | Schreiber et al. | Jul 2009 | A1 |
| 20100319395 | De Larminat et al. | Dec 2010 | A1 |
| 20110056664 | De Larminat et al. | Mar 2011 | A1 |
| Number | Date | Country |
|---|---|---|
| 1249032 | Mar 2000 | CN |
| 60-43966 | Mar 1985 | JP |
| 61-125588 | Jun 1986 | JP |
| 09-061080 | Mar 1997 | JP |
| 3364818 | Jan 2003 | JP |
| 2003-517560 | May 2003 | JP |
| 2007-198700 | Aug 2007 | JP |
| 2008-516187 | May 2008 | JP |
| 2011-510248 | Mar 2011 | JP |
| 9841798 | Sep 1998 | WO |
| Entry |
|---|
| Office Acton for the corresponding Chinese application No. 201380021198.5, issued on Dec. 16, 2015. |
| Number | Date | Country | |
|---|---|---|---|
| 20130277018 A1 | Oct 2013 | US |
