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  Cooling unitUSPTO Application #: 20060225447Title: Cooling unit Abstract: A cooling unit which contains refrigerant for exchanging heat with an object member of cooling includes a refrigerant passage and cooling means. The refrigerant passage allows the refrigerant to circulate therethrough. The cooling means communicates with the refrigerant passage for supplying the refrigerant passage with the refrigerant. The cooling means includes a refrigeration circuit, a compressor, a condenser, decompression means, an evaporator, a refrigerant supply path, a refrigerant return path, refrigerant control means and first pressure control means. The refrigerant control means has an on mode which allows the refrigerant to circulate through the refrigerant passage at a flow rate which enables the refrigerant to maintain gas-liquid two-phase flow by allowing the condenser to communicate with the refrigerant passage, and an off mode which prevents the refrigerant from circulating through the refrigerant passage by preventing the condenser from communicating with the refrigerant passage. (end of abstract)
Agent: Morgan & Finnegan, L.L.P. - New York, NY, US Inventors: Shinya Yamamoto, Hideyuki Ito, Ryosuke Koshizaka, Osamu Uchiyama, Mamoru Kuwahara, Takeshi Kawata, Satoru Kuramoto USPTO Applicaton #: 20060225447 - Class: 062197000 (USPTO) Related Patent Categories: Refrigeration, Automatic Control, Refrigeration Producer, Bypass, E.g., Compressor Unloading, Of Expansion Zone The Patent Description & Claims data below is from USPTO Patent Application 20060225447. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] The present invention relates to a cooling unit, and in particular to a cooling unit which requires strict temperature control for use in a semiconductor production unit. [0002] In a conventional cooling unit such as a chiller unit for use in a semiconductor production unit, primary refrigerant such as fluorocarbon which circulates through a refrigeration circuit cools secondary refrigerant such as water, and the cooled secondary refrigerant cools an object member of cooling. In this case, the object member is not directly cooled by the refrigeration circuit but is indirectly cooled by the refrigeration circuit through the secondary refrigerant thereby to degrade cooling efficiency of the chiller unit. [0003] To solve the above problem, a chiller unit in which an object member of cooling is directly cooled by only refrigerant such as fluorocarbon which circulates through a refrigeration circuit is disclosed by Japanese Unexamined Patent Application Publication (KOKAI) No. 2003-174016. In this chiller unit, the refrigerant compressed by a compressor of the refrigeration circuit is condensed by a condenser of the refrigeration circuit, and then the condensed refrigerant is transmitted into a refrigerant passage formed in a susceptor of a vacuum treatment unit through a regulating valve which regulates flow rate of the refrigerant thereby to cool a body to be treated which is disposed on the susceptor. That is, the refrigerant passage itself serves as what is called an evaporator of the refrigeration circuit. The refrigerant which has cooled the body is returned to the compressor so as to circulate through the refrigeration circuit again. [0004] However, when the chiller unit of the above reference is applied to a case where an object member of cooling which is expected to reach temperature above a boiling point of the refrigerant is maintained at a constant temperature above the boiling point of the refrigerant, the conventional cooling method in which the regulating valve of the chiller unit controls the flow rate of the refrigerant cannot maintain the object member at the constant temperature due to the temperature of the object member above the boiling point of the refrigerant. That is, even if a part of the object member is maintained at the constant temperature, the other part of the object member is not maintained at the constant temperature. Consequently, temperature in the object member becomes irregular. Specifically, when the flow rate of the refrigerant flowing in the refrigerant passage is extremely small, even if the refrigerant is capable of cooling the object member in the vicinity of an inlet of the refrigerant passage, the refrigerant is completely vaporized or dried out in the middle of the refrigerant passage, so that absorption of heat using latent heat of vaporization is not performed. In this case, temperature of a part of the object member adjacent to an outlet of the refrigerant passage rises above that adjacent to the inlet of the refrigerant passage. That is, temperature in the object member becomes irregular. On the other hand, when the flow rate of the refrigerant flowing in the refrigerant passage is excessively large, a part of the object member adjacent to the inlet of the refrigerant passage is overcooled, so that temperature control is lost and therefore the object member is not maintained at a predetermined temperature. SUMMARY OF THE INVENTION [0005] The present invention is directed to a cooling unit capable of substantially uniformly cooling an object member of cooling to a desired temperature. [0006] In accordance with an aspect of the present invention, a cooling unit which contains refrigerant for exchanging heat with an object member of cooling includes a refrigerant passage and cooling means. The refrigerant passage allows the refrigerant to circulate therethrough. The cooling means communicates with the refrigerant passage for supplying the refrigerant passage with the refrigerant. The cooling means includes a refrigeration circuit, a compressor, a condenser, decompression means, an evaporator, a refrigerant supply path, a refrigerant return path, refrigerant control means and first pressure control means. The refrigeration circuit allows the refrigerant to circulate therethrough. The compressor is disposed in the refrigeration circuit. The condenser is also disposed in the refrigeration circuit. The decompression means is also disposed in the refrigeration circuit. The evaporator is also disposed in the refrigeration circuit. One end of the refrigerant supply path is connected to a part of the refrigeration circuit between the condenser and the decompression means and the other end thereof is connected to an inlet of the refrigerant passage. One end of the refrigerant return path is connected to an outlet of the refrigerant passage and the other end thereof is located downstream from the decompression means and is connected to a part of the refrigeration circuit between the decompression means and the compressor. The refrigerant control means is disposed in the refrigerant supply path for allowing the condenser to communicate with the refrigerant passage or preventing the condenser from communicating with the refrigerant passage. The first pressure control means is also disposed in the refrigerant supply path for controlling pressure in the refrigerant passage. The refrigerant control means has an on mode which allows the refrigerant to circulate through the refrigerant passage at a flow rate which enables the refrigerant to maintain gas-liquid two-phase flow by allowing the condenser to communicate with the refrigerant passage, and an off mode which prevents the refrigerant from circulating through the refrigerant passage by preventing the condenser from communicating with the refrigerant passage. [0007] It is not intended that the invention be summarized here in its entirety. Rather, other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0008] The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention, together with objects and advantages thereof, may best be understood by reference to the following description, together with the accompanying drawings, in which: [0009] FIG. 1 is a schematic diagram showing a cooling unit according to a first embodiment of the present invention; [0010] FIG. 2 is a graph explaining an on-off control of the cooling unit according to the first embodiment of the present invention; [0011] FIG. 3 is a graph representing the relationship between flow rate of fluorocarbon R134 which circulates through a refrigerant passage 3 and temperature fluctuation which is temperature difference between maximum temperature and minimum temperature in a shower plate 2 of the cooling unit according to the first embodiment of the present invention; [0012] FIG. 4 is a schematic diagram showing a cooling unit according to a second embodiment of the present invention; [0013] FIG. 5 is a schematic diagram showing a cooling unit according to a third embodiment of the present invention; [0014] FIG. 6 is a schematic diagram showing a cooling unit according to a fourth embodiment of the present invention; and [0015] FIG. 7 is a graph explaining the relationship between a duty ratio and circulation of fluorocarbon in a cooling unit according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0016] The following will describe embodiments of the present invention with reference to the accompanying drawings. [0017] A cooling unit according to a first embodiment of the present invention will now be described with reference to FIG. 1. In the first embodiment, a chiller unit 10 that serves as cooling means and a refrigerant passage 3 form the cooling unit. [0018] A vacuum treatment unit 1 includes a vacuum chamber 6 therein. In the vacuum chamber 6, a susceptor 4 on which a body 5 to be treated is disposed is provided. In the upper part of the vacuum chamber 6, a shower plate 2 that serves as an object member of cooling is provided so as to face the susceptor 4. Inside an upper wall 7 of the vacuum treatment unit 1 in the vicinity of the shower plate 2, a refrigerant passage 3 is provided. Also, inside the upper wall 7, a temperature sensor 8 that serves as temperature detection means is provided for detecting temperature of the upper wall 7 in the vicinity of the shower plate 2. [0019] The chiller unit 10 includes a diaphragm type compressor 11, a condenser 12, an expansion valve 14 that serves as decompression means, an evaporator 15 and a refrigeration circuit 18 through which fluorocarbon R134a (hereinafter referred to as fluorocarbon) that serves as a refrigerant circulates. The compressor 11, the condenser 12, the expansion valve 14 and the evaporator 15 are disposed in the refrigeration circuit 18. The refrigeration circuit 18 includes a cooling-water path 16 through which cooling water circulates. In the evaporator 15 and the condenser 12, heat exchange is performed between the cooling water in the cooling-water path 16 and the fluorocarbon in the refrigeration circuit 18. In the cooling-water path 16, a valve 17 is interposed between the evaporator 15 and the condenser 12. In the refrigeration circuit 18, the condenser 12 and the expansion valve 14 have a branch point 18a therebetween at which the refrigeration circuit 18 is divided into two paths. One path 18b is in communication with the expansion valve 14 that serves as the decompression means to form a part of refrigeration circuit 18, and the other path 18c is in communication with an inlet 3a of the refrigerant passage 3. The path 18c forms a refrigerant supply path. In the path 18c, an on-off valve 21 is provided. When the on-off valve 21 is opened, the on-off valve 21 allows the refrigerant to be supplied into the refrigerant passage 3 through the path 18c. When the on-off valve 21 is closed, the on-off valve 21 prevents the refrigerant from being supplied into the refrigerant passage 3 through the path 18c. The on-off valve 21 forms refrigerant control means. In the state where the on-off valve 21 is opened, the on-off valve 21 also serves as an expansion valve which is first pressure control means in the refrigerant supply path. The on-off valve 21 is electrically connected to a controller 9 together with the temperature sensor 8. In the controller 9, an upper limit value and a lower limit value about detection value of the temperature sensor 8 are set. The upper limit value serves as a first predetermined temperature and the lower limit value serves as a second predetermined temperature. Also, the expansion valve 14 and the evaporator 15 has a meeting point 18d therebetween, which is in communication with an outlet 3b of the refrigerant passage 3 through a path 18e which forms a refrigerant return path. In the path 18e, a first accumulator 22 and a constant pressure valve 23 are provided. The accumulator 22 accumulates liquid fluorocarbon therein. The constant pressure valve 23 is second pressure control means in the refrigerant return path for adjusting pressure in the refrigerant passage 3 to a constant value. [0020] Operation of the cooling unit according to the first embodiment will now be described with reference to FIG. 1. When the vacuum treatment unit 1 is started to treat the body 5 in the vacuum chamber 6 of the vacuum treatment unit 1, the compressor 11 is started and at the same time the cooling water circulates through the cooling-water path 16 so that operation of the refrigeration circuit 18 of the chiller unit 10 is started. When the fluorocarbon exchanges heat with the cooling water in the evaporator 15, the fluorocarbon with gas-liquid two-phase flow is evaporated, which is introduced into the compressor 11. The fluorocarbon is compressed by the compressor 11 and is discharged therefrom in the form of gas at high temperature and pressure. When the gaseous fluorocarbon discharged from the compressor 11 exchanges heat with the cooling water cooled by the evaporator 15 in the condenser 12, the gaseous fluorocarbon is cooled thereby to condense the gaseous fluorocarbon into liquid fluorocarbon. Following the condensation of the fluorocarbon in the condenser 12, the liquid fluorocarbon is separated at the branch point 18a so as to circulate through the paths 18b, 18c. As will be described later, when the on-off valve 21 is opened, the fluorocarbon which has circulated through the path 18c is supplied into the refrigerant passage 3. At this time, the fluorocarbon which has circulated through the path 18c is decompressed by the on-off valve 21 that serves as the expansion valve, and supplied into the refrigerant passage 3 in the form of gas-liquid two-phase flow. On the other hand, the fluorocarbon which circulates through the path 18b is decompressed by the expansion valve 14 to form the fluorocarbon with gas-liquid two-phase flow, and then meets the fluorocarbon which has circulated through the path 18e in the meeting point 18d as will be described later. Subsequently, when the gas-liquid two-phase flow fluorocarbon flows into the evaporator 15, as described above the gas-liquid two-phase flow fluorocarbon exchanges heat with the cooling water in the cooling-water path 16, thereby to cool the cooling water. Then, the fluorocarbon is returned to the compressor 11, thus circulating through the refrigeration circuit 18. Continue reading... Full patent description for Cooling unit Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Cooling unit patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. 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