US20150168028A1 - Cryogenic refrigerator - Google Patents
Cryogenic refrigerator Download PDFInfo
- Publication number
- US20150168028A1 US20150168028A1 US14/567,576 US201414567576A US2015168028A1 US 20150168028 A1 US20150168028 A1 US 20150168028A1 US 201414567576 A US201414567576 A US 201414567576A US 2015168028 A1 US2015168028 A1 US 2015168028A1
- Authority
- US
- United States
- Prior art keywords
- refrigerant gas
- displacer
- expansion space
- cylinder
- cover portion
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/14—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/14—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle
- F25B9/145—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle pulse-tube cycle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
- F25B9/10—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point with several cooling stages
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2500/00—Problems to be solved
- F25B2500/09—Improving heat transfers
Definitions
- the present invention relates to a cryogenic refrigerator which generates Simon expansion and g cooling capacity using high pressure refrigerant gas supplied from a compressor, and particularly, to a displacer used in a cryogenic refrigerator.
- a Gifford-McMahon (GM) refrigerator As an example of a refrigerator which generates cryogenic temperatures, a Gifford-McMahon (GM) refrigerator is known.
- GM refrigerator a volume of an expansion space is changed by reciprocating a displacer in a cylinder.
- the expansion space and a discharge side and a suction side of a compressor are selectively connected to each other according to the volume change, and thus, the refrigerant gas is expanded in the expansion space.
- a cooling object is cooled by the cold refrigerant gas.
- a cryogenic refrigerator including: a displacer; a cover portion which is provided on a low temperature end of the displacer; and a cylinder which accommodates the displacer to be reciprocated in the longitudinal direction and to form an expansion space of a refrigerant gas between the cover portion and the cylinder.
- FIG. 1 is a schematic diagram illustrating a cryogenic refrigerator and a displacer according to an embodiment of the present invention.
- FIGS. 2A and 2B are diagrams illustrating an example of a refrigerator gas channel in the cryogenic refrigerator according to the embodiment of the present invention.
- FIGS. 3A and 3B are diagrams illustrating another example of the refrigerator gas channel according to the embodiment of the present invention.
- FIG. 4 is a schematic diagram illustrating a configuration of a two-stage cryogenic refrigerator according to another embodiment of the present invention.
- FIGS. 5A and 5B are schematic diagrams illustrating another configuration of the two-stage cryogenic refrigerator according to the embodiment of the present invention.
- FIG. 6 is a schematic diagram illustrating a cryogenic refrigerator and a displacer according to a modification of the embodiment of the present invention.
- a clearance is provided between the cylinder and the displacer.
- a cooling stage is provided on a low temperature end of the cylinder, and a portion of the clearance functions as a heat exchanger which performs heat exchange between a refrigerant gas in the clearance and the cooling stage.
- a loss referred to as a shuttle loss may occur due to heat conduction of the refrigerant gas existing in the clearance.
- the heat exchanger is lengthened and a heat exchange area between the refrigerant gas and the cooling stage is widened, the heat exchange efficiency between the refrigerant gas and the cooling stage will be improved.
- the shuttle loss is increased as the heat exchanger is lengthened. In this way, there is a trade-off relationship between an improvement of the heat exchange efficiency and a decrease of the shuttle loss by the change of the length of the heat exchanger.
- a cryogenic refrigerator 1 is a Gifford-McMahon (GM) type refrigerator using helium gas as a refrigerant gas.
- the cryogenic refrigerator 1 includes a displacer 2 , a cylinder 4 which forms an expansion space 3 between the displacer 2 and the cylinder 4 , and a bottomed cylindrical cooling stage 5 which is adjacent to the expansion space 3 and is positioned to externally enclose the space.
- the cooling stage 5 functions as a heat exchanger which performs heat exchange between a cooling object and the refrigerant gas.
- the displacer 2 includes a main body portion 2 a and a cover portion 2 b which is provided on a low temperature end.
- the cover portion 2 b may be configured of the same member as the main body portion 2 a . Moreover, the cover portion 2 b may be configured of a material having higher thermal conductivity than the main body portion 2 a . Accordingly, the cover portion 2 b also functions as a heat conduction portion which performs heat exchange between the refrigerant gas flowing to the inside of the cover portion 2 b and the cover portion.
- the cover portion 2 b is configured of a material having at least higher thermal conductivity than the main body portion 2 a , such as copper, aluminum, or stainless steel.
- the cooling stage 5 is configured of copper, aluminum, stainless steel, or the like.
- a compressor 12 recovers a low pressure refrigerant gas from a suction side, and after the compressor compresses the refrigerant gas, the compressor supplies a high pressure refrigerant gas to the cryogenic refrigerator 1 .
- a helium gas may be used as the refrigerant gas.
- the refrigerant gas is not limited thereto.
- the cylinder 4 accommodates the displacer 2 to be reciprocated in a longitudinal direction.
- the cylinder 4 is configured of stainless steel.
- a scotch yoke mechanism (not illustrated) which reciprocates the displacer 2 is provided on a high temperature end of the displacer 2 , and the displacer 2 reciprocates along an axial direction of the cylinder 4 .
- the displacer 2 has a cylindrical outer circumferential surface and a regenerator material is filled in the displacer 2 .
- An internal volume of the displacer 2 configures a regenerator 7 .
- Straightening devices (not illustrated) which straighten the flow of the helium gas may be provided on the upper end side and the lower end side of the regenerator 7 .
- An upper opening 11 which circulates the refrigerant gas from a room temperature chamber 8 to the displacer 2 , is formed on the high temperature end of the displacer 2 .
- the room temperature chamber 8 is a space which is formed of the cylinder 4 and the high temperature end of the displacer 2 , and a volume of the room temperature chamber is changed according to the reciprocation of the displacer 2 .
- a supply-exhaust common pipe is connected to the room temperature chamber 8 .
- a seal 15 is mounted between a portion on the high temperature end of the displacer 2 and the cylinder 4 .
- a refrigerant gas channel 16 which introduces the refrigerant gas into the expansion space 3 is formed on the low temperature end of the displacer 2 .
- the expansion space 3 is a space which is formed of the cylinder 4 and the displacer 2 , and a volume of the expansion space is changed according to the reciprocation of the displacer 2 .
- the cooling stage 5 which is thermally connected to the cooling object is disposed at a position corresponding to the expansion space 3 of the outer circumference and the bottom portion of the cylinder 4 , and the cooling stage 5 is cooled by the refrigerant gas flowing into the expansion space 3 through the refrigerant gas channel 16 .
- the main body portion 2 a of the displacer 2 may be formed of a phenol resin or the like.
- the regenerator material is configured of a wire screen or the like.
- FIG. 1 illustrates the state during the operation of the cryogenic refrigerator 1 . Accordingly, both outer diameters are the same as each other according to slight shrinkage of the main body portion 2 a from the low temperature. However, in normal temperatures, the outer diameter of the cover portion 2 b is slightly smaller than the outer diameter of the main body portion 2 a.
- the displacer 2 is positioned at a bottom dead center LP of the cylinder 4 . If the supply valve 13 is opened at the same time as that, or at timing slightly deviated from that, the high pressure refrigerant gas is supplied from the supply-exhaust common pipe into the cylinder 4 via the supply valve 13 . As a result, the high pressure refrigerant gas flows from the upper opening 11 positioned at the upper portion of the displacer 2 into the regenerator 7 positioned in the displacer 2 . The high pressure refrigerant gas flowing into the regenerator 7 is supplied to the expansion space 3 via the refrigerant gas channel 16 positioned at the lower portion of the displacer 2 while being cooled by the regenerator material.
- the supply valve 13 is closed. In this case, the displacer 2 is positioned at a top dead center UP in the cylinder 4 . If the return valve 14 is opened at the same time as that, or at timing slightly deviated from that, the refrigerant gas in the expansion space 3 is decompressed and expanded. The helium gas in the expansion space 3 , which drops to a low temperature by the expansion, absorbs heat from the cooling stage 5 .
- the displacer 2 moves toward the bottom dead center LP, and thus, the volume of the expansion space 3 is decreased.
- the refrigerant gas in the expansion space 3 is returned to the suction side of the compressor 12 via the refrigerant gas channel 16 , the regenerator 7 , and the upper opening 11 .
- the regenerator material is cooled by the refrigerant gas. This process is set to one cycle, and the cryogenic refrigerator 1 cools the cooling stage 5 by repeating the cooling cycle.
- the heat entering from the cooling stage 5 enters the cover portion 2 b via the refrigerant gas existing in the expansion space 3 . That is, when the low temperature refrigerant gas generated in the expansion space 3 passes through the refrigerant gas channel 16 , heat exchange between the refrigerant gas and the cover portion 2 b is performed.
- the heat entering the cover portion 2 b is further transmitted toward the expansion space 3 through the inner portion of the cover portion 2 b .
- the cover portion 2 b is provided on the low temperature end of the displacer 2 . Accordingly, the cover portion 2 b comes into contact with the low temperature refrigerant gas in the expansion space 3 , and it is possible to further improve the heat exchange efficiency between the cooling stage 5 and the refrigerant gas.
- the cover portion 2 b of the displacer 2 may be configured of a phenol resin or the like.
- the cover portion 2 b is configured of a material having higher thermal conductivity than the main body portion 2 a .
- the heat exchange between the refrigerant gas and the cover is decreased, and the heat exchange is not substantially performed. Accordingly, only the heat exchange between the low temperature refrigerant gas generated in the expansion space 3 and the cooling stage 5 is performed, and thus, the cooling efficiency is decreased. Therefore, preferably, in the cover of the displacer 2 , the cover portion 2 b is configured of a material having higher thermal conductivity than the main body portion 2 a.
- the refrigerant gas in the expansion space 3 is expanded by reciprocating the displacer 2 in the cylinder 4 , and thus, cooling capacity is generated.
- a clearance C is provided between the cylinder 4 and the displacer 2 to reciprocate the displacer 2 .
- a portion of the clearance C adjacent to the cooling stage 5 functions as a heat exchanger which performs heat exchange between the cooling stage 5 and the refrigerant gas in the clearance C.
- a technology in which the refrigerant gas channel 16 is directed in a radial direction of the cylinder 4 (a direction directed to the side surface of the cylinder 4 ) is also known. According to this method, there is an advantage that the heat exchange area is increased. However, the refrigerant gas channel 16 is bent, and the channel area is likely to be narrowed. As a result, a channel resistance is increased, and pressure loss occurs. In addition, when the displacer 2 reciprocates the cylinder 4 , loss due to heat conduction of the refrigerant gas existing in the clearance C occurs, that is, so-called “shuttle loss” occurs.
- the direction of the refrigerant gas channel 16 is provided to be inclined with respect to the longitudinal direction of the displacer 2 .
- the refrigerant gas channel 16 according to the embodiment will be described more specifically.
- FIG. 1 illustrates an example of the refrigerant gas channel 16 according to the embodiment.
- a first opening 17 is provided on the inside surface (hereinafter, referred to as an “inner surface 19 ”) of the displacer 2
- a second opening 18 is provided on the outside surface (hereinafter, referred to as an “outer surface 20 ”) of the displacer 2 .
- the refrigerant gas channel 16 has the first opening 17 at one end and the second opening 18 at the other end, and is provided so that the inner surface 19 and the outer surface 20 communicate with each other in the cover portion 2 b.
- the refrigerant gas channel 16 is provided so that the position of the first opening 17 and the position of the second opening 18 after the projection are different from each other. Accordingly, when the refrigerant gas flows from the first opening 17 and the second opening 18 into the expansion space 3 , the refrigerant gas flows out in a direction different from the longitudinal direction of the displacer 2 . As a result, in the cryogenic refrigerator 1 according to the embodiment, compared to the case where the refrigerant gas channel 16 is provided downward in FIG.
- the channel area of the refrigerant gas channel 16 can be increased, and thus, the shuttle loss and the pressure loss can be decreased.
- the refrigerant gas channel 16 is provided so that the refrigerant gas flowing out from the second opening 18 is directed to the side surface of the cylinder 4 . Accordingly, the refrigerant gas flowing out from the second opening 18 comes into contact with the side surface of the cylinder 4 and the movement direction of the refrigerant gas is changed, and thus, the motion of the refrigerant gas in the expansion space 3 becomes complicated. Therefore, the vortex of the refrigerant gas in the expansion space 3 is more easily generated, and the heat exchange efficiency between the refrigerant gas and the cooling stage 5 is further improved.
- a plurality of the refrigerant gas channels 16 through which the first opening 17 and the second opening 18 communicate with each other, are provided on the cover portion 2 b of the displacer 2 . Accordingly, the entire channel area of the refrigerant gas channels 16 can be increased, and it is possible to further decrease the pressure loss. Moreover, the refrigerant gas flows out of the plurality of locations into the expansion space 3 , and thus, the motion of the refrigerant gas in the expansion space 3 becomes complicated. Accordingly, turbulent flow of the refrigerant gas in the expansion space 3 is easily generated, and the heat exchange efficiency between the refrigerant gas and the cooling stage 5 is further improved.
- FIGS. 2A and 2B are diagrams illustrating other examples of the refrigerant gas channel 16 in the cryogenic refrigerator 1 according to the embodiment of the present invention.
- the refrigerant gas channel 16 has the first opening 17 as one end and the second opening 18 as the other end, and is provided so that the inner surface 19 and the outer surface 20 communicate with each other in the cover portion 2 b .
- the first opening 17 on the inner surface 19 is projected to the outer surface 20 along the longitudinal direction of the displacer 2 , the position of the first opening 17 and the position of the second opening 18 after the projection are different from each other.
- FIGS. 2A and 2B are different from the example illustrated in FIG. 1 . That is, the direction in which the refrigerant gas passing through one refrigerant gas channel 16 flows into the expansion space 3 is the same as the direction in which the refrigerant gas passing through other refrigerant gas channels 16 flow into the expansion space 3 . Accordingly, due to the motion of the refrigerant gas which flows into the expansion space 3 , a force operates in the direction in which the refrigerant gas in the expansion space 3 is rotated, and thus, the vortex is easily generated in the refrigerant gas in the expansion space 3 .
- the refrigerant gas channel 16 is formed in a spiral shape in the example illustrated in FIG.
- the example illustrated in FIG. 2A has an advantage in that machining of the refrigerant gas channel 16 is easily performed.
- the refrigerant gas channel 16 is lengthened. Accordingly, the example illustrated in FIG. 2B has an advantage in that the heat exchange efficiency between the refrigerant gas flowing through the refrigerant gas channel 16 and the cover portion 2 b is improved.
- FIGS. 3A and 3B are diagrams illustrating other examples of the refrigerant gas channel 16 according to the embodiment of the present invention, and are perspective diagrams illustrating the refrigerant gas channel 16 and the cover portion 2 b . More specifically, FIGS. 3A and 3B are diagrams which illustrate a case where four refrigerant gas channels 16 (channels 16 a , 16 b , 16 c , and 16 d of the refrigerant gas) are provided in the cover portion 2 b . Moreover, compared to the examples illustrated in FIGS. 1 to 2B , in FIGS. 3A and 3B , the shape of the cover portion 2 b are illustrated so as to be partially omitted.
- FIG. 3A illustrates an example in which four refrigerant gas channels 16 are linearly formed from the first opening 17 to the second opening 18 .
- FIG. 3B illustrates an example in which four refrigerant gas channels 16 are formed in a spiral shape from the first opening 17 to the second opening 18 .
- the direction in which the refrigerant gas passing through one refrigerant gas channel 16 flows into the expansion space 3 is different from a direction in which the refrigerant gas passing through another refrigerant gas channel 16 flows into the expansion space 3 .
- the refrigerant gas passing through the refrigerant gas channel 16 a flows out in a lower right direction in FIG. 3A in the expansion space 3 .
- the refrigerant gas passing through the refrigerant gas channel 16 c flows out to a side opposite to the flowing-out direction of the refrigerant gas passing the refrigerant gas channel 16 a in the expansion space 3 , that is, in a lower left direction in FIG. 3A .
- FIG. 3A four refrigerant gas channels 16 are provided to be rotationally symmetrical with respect to a central axis in the longitudinal direction of the displacer 2 .
- the central axis in the longitudinal direction of the displacer 2 coincides with a central axis when the cover portion 2 b is assumed as a column.
- four refrigerant gas channels 16 in FIG. 3A are provided to be rotationally symmetrical with respect to the central axis of the cover portion 2 b.
- the positions of the refrigerant gas channels 16 a , 16 b , 16 c , and 16 d after the rotation coincide with the positions of the refrigerant gas channels 16 b , 16 c , 16 d , and 16 a before the rotation.
- each of the positions of the refrigerant gas channels 16 a , 16 b , 16 c , and 16 d after the rotation coincide with any one of the positions of the refrigerant gas channels 16 a , 16 b , 16 c , and 16 d before the rotation.
- the refrigerant gas which passes through the refrigerant gas channels 16 a , 16 b , 16 c , and 16 d and flows into the expansion space 3 , is operated to rotate the refrigerant gas in the expansion space 3 in the same rotation direction.
- the vortex is easily generated in the refrigerant gas in the expansion space 3 , and it is possible to further improve the heat exchange efficiency between the refrigerant gas and the cover portion 2 b in the expansion space 3 .
- the cryogenic refrigerator 1 is a one-stage refrigerator.
- the cryogenic refrigerator 1 is not limited to the one-stage refrigerator but may be a multi-stage refrigerator.
- the cryogenic refrigerator 1 may be applied to a two-stage refrigerator.
- FIG. 4 is a schematic diagram illustrating a two-stage cryogenic refrigerator 31 according to another embodiment of the present invention. Similar to the above-described one-stage cryogenic refrigerator 1 , the cryogenic refrigerator 31 is a Gifford-McMahon (GM) type refrigerator using helium gas as a refrigerant gas. As illustrated in FIG. 4 , the cryogenic refrigerator 31 includes a first displacer 32 , and a second displacer 36 which is connected to the first displacer 32 in the longitudinal direction. For example, as illustrated in FIGS. 5A and 5B , the first displacer 32 and the second displacer 36 are connected to each other via a pin 33 , a connector 34 , and a pin 35 .
- GM Gifford-McMahon
- a first cylinder 37 is integrally formed with a second cylinder 38 , and the low temperature end of the first cylinder 37 and the high temperature end of the second cylinder 38 are connected to each other at the bottom portion of the first cylinder 37 .
- the second cylinder 38 is coaxially formed with the first cylinder 37 and is a cylinder member having a smaller diameter than the first cylinder 37 .
- the first cylinder 37 accommodates the first displacer 32 to be reciprocated in the longitudinal direction
- the second cylinder 38 accommodates the second displacer 36 to be reciprocated in the longitudinal direction.
- the first cylinder 37 and the second cylinder 38 are formed of stainless steel.
- the second displacer 36 is configured so that a film of an abrasion-resistant resin such as a fluorocarbon resin is covered on the outer circumferential surface of a pipe formed of metal such as stainless steel.
- the first displacer 32 has a cylindrical outer circumferential surface, and a first regenerator material (not illustrated) is filled in the first displacer 32 .
- the internal volume of the first displacer 32 functions as a first regenerator 41 .
- straightening devices may be installed on the upper portion and the lower portion of the first regenerator 41 .
- An upper opening 42 which circulates the refrigerant gas from a room temperature chamber 39 to the first displacer 32 , is formed on the high temperature end of the first displacer 32 .
- the room temperature chamber 39 is a space which is formed of the first cylinder 37 and the high temperature end of the first displacer 32 , and the volume of the room temperature chamber is changed according to the reciprocation of the first displacer 32 .
- a supply-exhaust common pipe is connected to the room temperature chamber 39 .
- a seal 46 is mounted between a portion on the high temperature end of the first displacer 32 and the first cylinder 37 .
- a refrigerant gas channel 48 which introduces the refrigerant gas into a first expansion space 47 is formed on the low temperature end of the first displacer 32 .
- the first expansion space 47 is a space which is formed of the first cylinder 37 and the first displacer 32 , and the volume of the expansion space is changed according to the reciprocation of the first displacer 32 .
- a first cooling stage 49 which is thermally connected to an object to be cooled (not illustrated) is disposed at a position corresponding to the first expansion space 47 of the outer circumference of the first cylinder 37 , and the first cooling stage 49 is cooled by the refrigerant gas of the first expansion space 47 .
- the second displacer 36 has a cylindrical outer circumferential surface, and a second regenerator material (not illustrated) is filled in the second displacer 36 .
- the internal volume of the second displacer 36 configures a second regenerator 50 .
- the first expansion space 47 and the high temperature end of the second displacer 36 communicate with each other through a communication path (not illustrated).
- the refrigerant gas circulates from the first expansion space 47 to the second regenerator 50 via the communication path.
- a refrigerant gas channel 56 for circulating the refrigerant gas into a second expansion space 51 is formed on the low temperature end of the second displacer 36 .
- the second expansion space 51 is a space which is formed of the second cylinder 38 and the second displacer 36 , and the volume of the expansion space is changed according to the reciprocation of the second displacer 36 .
- a second cooling stage 54 which is thermally connected to the cooling object is disposed at a position corresponding to the second expansion space 51 of the outer circumference of the second cylinder 38 , and the second cooling stage 54 is cooled by the refrigerant gas in the second expansion space 51 .
- the first displacer 32 is formed of fabric based on phenol or the like.
- the first regenerator material is configured of a wire screen or the like.
- the second regenerator material is configured by interposing a regenerator material such as a lead ball in the axial direction by a felt and a wire screen.
- a spiral groove 53 extending to the first expansion space 47 side in a spiral shape is formed on the outer circumference surface of the second displacer 36 .
- the refrigerant gas channel 48 is configured to communicate with the cover portion 32 b positioned at the low temperature end of the first displacer 32 .
- the refrigerant gas channel 56 is configured to communicate with the cover portion 52 b positioned at the low temperature end of the second displacer 36 .
- the refrigerant gas channel 48 and the refrigerant gas channel 56 are provided to be inclined with respect to the longitudinal directions of the first displacer 32 and the second displacer 36 . Accordingly, the refrigerant gas passing the refrigerant gas channel 48 generates a vortex of the refrigerant gas in the first expansion space 47 . Similarly, the refrigerant gas passing the refrigerant gas channel 56 generates a vortex of the refrigerant gas in the second expansion space 51 .
- FIGS. 5A and 5B are schematic diagrams illustrating other configurations of the two-stage cryogenic refrigerator 31 according to the embodiment of the present invention.
- the shapes of the refrigerant gas channels 56 communicating with the cover portions 52 b positioned at the low temperature ends of the second displacers 36 are different, and other portions are in common. Accordingly, the common portions are appropriately omitted or simplified and are described.
- the shape of the refrigerant gas channel 56 in the example illustrated in FIG. 5A is similar to the shape of the refrigerant gas channel 16 illustrated in FIG. 2A .
- the shape of the refrigerant gas channel 56 in FIG. 5B is similar to the shape of the refrigerant gas channel 16 illustrated in FIG. 2B . Accordingly, the effects are similar with each other, and it is possible to improve the heat exchange efficiency between the refrigerant gas in the second expansion space 51 and the second cooling stage 54 .
- cryogenic refrigerator 1 and the cryogenic refrigerator 31 it is possible to improve the heat exchange efficiency between the refrigerant gas and the heat exchanger while decreasing the shuttle loss.
- cryogenic refrigerators illustrate the cases where the number of the stages is one or two. However, the number of the stages can be appropriately changed to three or the like.
- the embodiments describe examples in which the cryogenic refrigerator is the GM refrigerator.
- the embodiments of the present invention are not limited thereto.
- the embodiments of the present invention can be applied to any refrigerator having the displacer such as a Stirling refrigerator or a Solvay refrigerator.
- FIGS. 4 to 5B describe the case of the refrigerant gas channel 48 in which the shape of the refrigerant gas channel 48 communicating with the cover portion 32 b positioned at the low temperature end of the first displacer 32 is similar to the shape of the refrigerant gas channel 16 illustrated in FIG. 1 .
- the shape of the refrigerant gas channel 48 in the two-stage cryogenic refrigerator 31 is not limited thereto. That is, for example, the shape of the refrigerant gas channel 48 may be the shapes illustrated in FIGS. 2A and 2B or FIGS. 3A and 3B , and the effects also are similar to those of cases illustrated in FIGS. 2A and 2B or FIGS. 3A and 3B .
- the refrigerant gas channel 16 may be provided so that the direction of the refrigerant gas flowing out of the second opening 18 is inclined with respect to the longitudinal direction of the displacer 2 , and is not limited as long as the first opening 17 or the second opening 18 is directed onto the cover of the low temperature end side of the displacer 2 .
- FIG. 6 is a schematic diagram illustrating the cryogenic refrigerator 1 and the displacer 2 according to a modification of the embodiment of the present invention.
- the first opening 17 and the second opening 18 positioned at both ends of the refrigerant gas channel 16 are provided on the main body portion 2 a of the displacer 2 .
- the first opening 17 and the second opening 18 are different from each other along the longitudinal direction of the displacer 2 , and the refrigerant gas channel 16 is directed in an inclined downward direction in FIG. 6 .
- the second opening 18 is positioned in the clearance C, and the gas, which flows from the first opening 17 and passes through the refrigerant gas channel 16 , flows out of the second opening 18 toward the side surface of the cylinder 4 . Accordingly, the refrigerant gas flowing out of the second opening 18 comes into contact with the side surface of the cylinder 4 , the movement direction of the refrigerant gas is changed, and thus, the motion of the refrigerant gas in the expansion space 3 becomes complicated. Therefore, a vortex of the refrigerant gas in the expansion space 3 is more easily generated, and it is possible to improve the heat exchange efficiency between the refrigerant gas and the cooling stage 5 . Moreover, it is possible to decrease the shuttle loss.
- the refrigerant gas channel in which both ends of the refrigerant gas channel are provided on the main body portion 2 a of the displacer 2 may be further provided.
- the refrigerant gas channel provided on the main body portion 2 a may be a so-called “horizontal jet channel” which is orthogonal with respect to the axial direction of the displacer 2 .
- the number of the stages is one.
- the modification can be also applied to a case where the number of the stages is two or more.
- the refrigerant gas channel 16 is provided on the side surface of the cylinder, and the refrigerant gas channel may be provided so that the direction of the refrigerant gas flowing out of the second opening 18 is inclined with respect to the longitudinal direction of the displacer 2 .
- the first opening 17 is provided on the inner surface 19 of the cover, and the second opening 18 may be provided on the side surface of the cylinder.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
- Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
Abstract
In a cryogenic refrigerator, a displacer includes a cover portion at a low temperature end of the displacer. A cylinder accommodates the displacer to be reciprocated in a longitudinal direction and forms an expansion space of a refrigerant gas between the cover portion and the cylinder. A refrigerant gas channel through which the displacer and the expansion space communicate with each other is formed in the cover portion. In the refrigerant gas channel, a flowing-out direction of the refrigerant gas flowing into the expansion space is inclined with respect to the longitudinal direction of the displacer.
Description
- Priority is claimed to Japanese Patent Application No. 2013-261441, filed Dec. 18, 2013, the entire content of which is incorporated herein by reference.
- 1. Technical Field
- The present invention relates to a cryogenic refrigerator which generates Simon expansion and g cooling capacity using high pressure refrigerant gas supplied from a compressor, and particularly, to a displacer used in a cryogenic refrigerator.
- 2. Description of Related Art
- As an example of a refrigerator which generates cryogenic temperatures, a Gifford-McMahon (GM) refrigerator is known. In the GM refrigerator, a volume of an expansion space is changed by reciprocating a displacer in a cylinder. The expansion space and a discharge side and a suction side of a compressor are selectively connected to each other according to the volume change, and thus, the refrigerant gas is expanded in the expansion space. A cooling object is cooled by the cold refrigerant gas.
- According to an embodiment of the present invention, there is provided a cryogenic refrigerator including: a displacer; a cover portion which is provided on a low temperature end of the displacer; and a cylinder which accommodates the displacer to be reciprocated in the longitudinal direction and to form an expansion space of a refrigerant gas between the cover portion and the cylinder. A refrigerant gas channel, through which the displacer and the expansion space communicate with each other, is formed in the cover portion, and a flowing-out direction of the refrigerant gas flowing into the expansion space is inclined with respect to the longitudinal direction of the displacer in the refrigerant gas channel.
-
FIG. 1 is a schematic diagram illustrating a cryogenic refrigerator and a displacer according to an embodiment of the present invention. -
FIGS. 2A and 2B are diagrams illustrating an example of a refrigerator gas channel in the cryogenic refrigerator according to the embodiment of the present invention. -
FIGS. 3A and 3B are diagrams illustrating another example of the refrigerator gas channel according to the embodiment of the present invention. -
FIG. 4 is a schematic diagram illustrating a configuration of a two-stage cryogenic refrigerator according to another embodiment of the present invention. -
FIGS. 5A and 5B are schematic diagrams illustrating another configuration of the two-stage cryogenic refrigerator according to the embodiment of the present invention. -
FIG. 6 is a schematic diagram illustrating a cryogenic refrigerator and a displacer according to a modification of the embodiment of the present invention. - In a refrigerator including a displacer such as a Gifford-McMahon refrigerator, in order to reciprocate the displacer in a cylinder, a clearance is provided between the cylinder and the displacer. A cooling stage is provided on a low temperature end of the cylinder, and a portion of the clearance functions as a heat exchanger which performs heat exchange between a refrigerant gas in the clearance and the cooling stage. Meanwhile, it is also known that a loss referred to as a shuttle loss may occur due to heat conduction of the refrigerant gas existing in the clearance.
- If the heat exchanger is lengthened and a heat exchange area between the refrigerant gas and the cooling stage is widened, the heat exchange efficiency between the refrigerant gas and the cooling stage will be improved. However, the shuttle loss is increased as the heat exchanger is lengthened. In this way, there is a trade-off relationship between an improvement of the heat exchange efficiency and a decrease of the shuttle loss by the change of the length of the heat exchanger.
- It is desirable to provide a technology which improves the heat exchange efficiency between a refrigerant gas and a heat exchanger while decreasing a shuttle loss.
- According to an embodiment of the present invention, it is possible to provide a technology which improves the heat exchange efficiency between a refrigerant gas and a heat exchanger while decreasing shuttle loss.
- An embodiment of the present invention will be described with reference to the drawings.
- For example, a cryogenic refrigerator 1 according to the embodiment is a Gifford-McMahon (GM) type refrigerator using helium gas as a refrigerant gas. The cryogenic refrigerator 1 includes a
displacer 2, acylinder 4 which forms anexpansion space 3 between thedisplacer 2 and thecylinder 4, and a bottomedcylindrical cooling stage 5 which is adjacent to theexpansion space 3 and is positioned to externally enclose the space. Thecooling stage 5 functions as a heat exchanger which performs heat exchange between a cooling object and the refrigerant gas. Thedisplacer 2 includes amain body portion 2 a and acover portion 2 b which is provided on a low temperature end. Thecover portion 2 b may be configured of the same member as themain body portion 2 a. Moreover, thecover portion 2 b may be configured of a material having higher thermal conductivity than themain body portion 2 a. Accordingly, thecover portion 2 b also functions as a heat conduction portion which performs heat exchange between the refrigerant gas flowing to the inside of thecover portion 2 b and the cover portion. For example, thecover portion 2 b is configured of a material having at least higher thermal conductivity than themain body portion 2 a, such as copper, aluminum, or stainless steel. For example, thecooling stage 5 is configured of copper, aluminum, stainless steel, or the like. - A
compressor 12 recovers a low pressure refrigerant gas from a suction side, and after the compressor compresses the refrigerant gas, the compressor supplies a high pressure refrigerant gas to the cryogenic refrigerator 1. For example, a helium gas may be used as the refrigerant gas. However, the refrigerant gas is not limited thereto. - The
cylinder 4 accommodates thedisplacer 2 to be reciprocated in a longitudinal direction. From the viewpoint of strength, thermal conductivity, helium shielding capability, or the like, for example, thecylinder 4 is configured of stainless steel. - A scotch yoke mechanism (not illustrated) which reciprocates the
displacer 2 is provided on a high temperature end of thedisplacer 2, and the displacer 2 reciprocates along an axial direction of thecylinder 4. - The
displacer 2 has a cylindrical outer circumferential surface and a regenerator material is filled in thedisplacer 2. An internal volume of thedisplacer 2 configures aregenerator 7. Straightening devices (not illustrated) which straighten the flow of the helium gas may be provided on the upper end side and the lower end side of theregenerator 7. - An
upper opening 11, which circulates the refrigerant gas from aroom temperature chamber 8 to thedisplacer 2, is formed on the high temperature end of thedisplacer 2. Theroom temperature chamber 8 is a space which is formed of thecylinder 4 and the high temperature end of thedisplacer 2, and a volume of the room temperature chamber is changed according to the reciprocation of thedisplacer 2. - In pipes which connect suction and discharge systems configured of the
compressor 12, asupply valve 13, and areturn valve 14 to each other, a supply-exhaust common pipe is connected to theroom temperature chamber 8. In addition, aseal 15 is mounted between a portion on the high temperature end of thedisplacer 2 and thecylinder 4. - A
refrigerant gas channel 16 which introduces the refrigerant gas into theexpansion space 3 is formed on the low temperature end of thedisplacer 2. Theexpansion space 3 is a space which is formed of thecylinder 4 and thedisplacer 2, and a volume of the expansion space is changed according to the reciprocation of thedisplacer 2. Thecooling stage 5 which is thermally connected to the cooling object is disposed at a position corresponding to theexpansion space 3 of the outer circumference and the bottom portion of thecylinder 4, and thecooling stage 5 is cooled by the refrigerant gas flowing into theexpansion space 3 through therefrigerant gas channel 16. - From the viewpoint of specific gravity, strength, thermal conductivity, or the like, for example, the
main body portion 2 a of thedisplacer 2 may be formed of a phenol resin or the like. For example, the regenerator material is configured of a wire screen or the like. In addition,FIG. 1 illustrates the state during the operation of the cryogenic refrigerator 1. Accordingly, both outer diameters are the same as each other according to slight shrinkage of themain body portion 2 a from the low temperature. However, in normal temperatures, the outer diameter of thecover portion 2 b is slightly smaller than the outer diameter of themain body portion 2 a. - Next, the operation of the cryogenic refrigerator 1 will be described. In a certain point of time of a refrigerant gas supply process, the
displacer 2 is positioned at a bottom dead center LP of thecylinder 4. If thesupply valve 13 is opened at the same time as that, or at timing slightly deviated from that, the high pressure refrigerant gas is supplied from the supply-exhaust common pipe into thecylinder 4 via thesupply valve 13. As a result, the high pressure refrigerant gas flows from theupper opening 11 positioned at the upper portion of thedisplacer 2 into theregenerator 7 positioned in thedisplacer 2. The high pressure refrigerant gas flowing into theregenerator 7 is supplied to theexpansion space 3 via therefrigerant gas channel 16 positioned at the lower portion of thedisplacer 2 while being cooled by the regenerator material. - If the
expansion space 3 is filled with the high pressure refrigerant gas, thesupply valve 13 is closed. In this case, thedisplacer 2 is positioned at a top dead center UP in thecylinder 4. If thereturn valve 14 is opened at the same time as that, or at timing slightly deviated from that, the refrigerant gas in theexpansion space 3 is decompressed and expanded. The helium gas in theexpansion space 3, which drops to a low temperature by the expansion, absorbs heat from thecooling stage 5. - The
displacer 2 moves toward the bottom dead center LP, and thus, the volume of theexpansion space 3 is decreased. The refrigerant gas in theexpansion space 3 is returned to the suction side of thecompressor 12 via therefrigerant gas channel 16, theregenerator 7, and theupper opening 11. In this case, the regenerator material is cooled by the refrigerant gas. This process is set to one cycle, and the cryogenic refrigerator 1 cools thecooling stage 5 by repeating the cooling cycle. - In the cryogenic refrigerator 1 and the
displacer 2 according to the embodiment, the heat entering from thecooling stage 5 enters thecover portion 2 b via the refrigerant gas existing in theexpansion space 3. That is, when the low temperature refrigerant gas generated in theexpansion space 3 passes through therefrigerant gas channel 16, heat exchange between the refrigerant gas and thecover portion 2 b is performed. - In addition, the heat entering the
cover portion 2 b is further transmitted toward theexpansion space 3 through the inner portion of thecover portion 2 b. As described above, thecover portion 2 b is provided on the low temperature end of thedisplacer 2. Accordingly, thecover portion 2 b comes into contact with the low temperature refrigerant gas in theexpansion space 3, and it is possible to further improve the heat exchange efficiency between the coolingstage 5 and the refrigerant gas. - In addition, for example, the
cover portion 2 b of thedisplacer 2 may be configured of a phenol resin or the like. However, compared to the cryogenic refrigerator 1 according to the present embodiment in which thecover portion 2 b is configured of a material having higher thermal conductivity than themain body portion 2 a, the heat exchange between the refrigerant gas and the cover is decreased, and the heat exchange is not substantially performed. Accordingly, only the heat exchange between the low temperature refrigerant gas generated in theexpansion space 3 and thecooling stage 5 is performed, and thus, the cooling efficiency is decreased. Therefore, preferably, in the cover of thedisplacer 2, thecover portion 2 b is configured of a material having higher thermal conductivity than themain body portion 2 a. - As described above, in the cryogenic refrigerator 1 according to the present embodiment, the refrigerant gas in the
expansion space 3 is expanded by reciprocating thedisplacer 2 in thecylinder 4, and thus, cooling capacity is generated. As illustrated inFIG. 1 , a clearance C is provided between thecylinder 4 and thedisplacer 2 to reciprocate thedisplacer 2. A portion of the clearance C adjacent to thecooling stage 5 functions as a heat exchanger which performs heat exchange between the coolingstage 5 and the refrigerant gas in the clearance C. - Here, in order to cause the refrigerant gas in the
displacer 2 to pass through the heat exchanger, a technology in which therefrigerant gas channel 16 is directed in a radial direction of the cylinder 4 (a direction directed to the side surface of the cylinder 4) is also known. According to this method, there is an advantage that the heat exchange area is increased. However, therefrigerant gas channel 16 is bent, and the channel area is likely to be narrowed. As a result, a channel resistance is increased, and pressure loss occurs. In addition, when thedisplacer 2 reciprocates thecylinder 4, loss due to heat conduction of the refrigerant gas existing in the clearance C occurs, that is, so-called “shuttle loss” occurs. - On the other hand, in order to decrease the shuttle loss, a technology in which the
refrigerant gas channel 16 is provided in the axial direction of thecylinder 4 and the refrigerant gas flows out to the bottom surface of thecylinder 4 is also known. In this method, since the heat exchange is not positively performed by the clearance C, the channel resistance of therefrigerant gas channel 16 can be decreased. Accordingly, compared to the method in which therefrigerant gas channel 16 is directed in the radial direction of thecylinder 4, the pressure loss or the shuttle loss is decreased. However, the heat exchange area between the refrigerant gas expanded in theexpansion space 3 and the cooling object is narrowed, and the heat exchange efficiency is decreased. - Accordingly, in the
refrigerant gas channel 16, through which thedisplacer 2 and theexpansion space 3 communicate with each other, according to the embodiment, when the refrigerant gas flowing from thedisplacer 2 into theexpansion space 3, the direction of therefrigerant gas channel 16 is provided to be inclined with respect to the longitudinal direction of thedisplacer 2. Hereinafter, therefrigerant gas channel 16 according to the embodiment will be described more specifically. -
FIG. 1 illustrates an example of therefrigerant gas channel 16 according to the embodiment. As illustrated inFIG. 1 , in thecover portion 2 b of thedisplacer 2, afirst opening 17 is provided on the inside surface (hereinafter, referred to as an “inner surface 19”) of thedisplacer 2, and asecond opening 18 is provided on the outside surface (hereinafter, referred to as an “outer surface 20”) of thedisplacer 2. Therefrigerant gas channel 16 has thefirst opening 17 at one end and thesecond opening 18 at the other end, and is provided so that theinner surface 19 and theouter surface 20 communicate with each other in thecover portion 2 b. - Here, when the
first opening 17 on theinner surface 19 is projected to theouter surface 20 along the longitudinal direction of thedisplacer 2, therefrigerant gas channel 16 is provided so that the position of thefirst opening 17 and the position of thesecond opening 18 after the projection are different from each other. Accordingly, when the refrigerant gas flows from thefirst opening 17 and thesecond opening 18 into theexpansion space 3, the refrigerant gas flows out in a direction different from the longitudinal direction of thedisplacer 2. As a result, in the cryogenic refrigerator 1 according to the embodiment, compared to the case where therefrigerant gas channel 16 is provided downward inFIG. 1 along the axial direction of thecylinder 4, a vortex of the refrigerant gas in theexpansion space 3 is easily generated due to the operation of the refrigerant gas which flows out of thesecond opening 18 into theexpansion space 3. Accordingly, the heat exchange efficiency between the refrigerant gas and thecooling stage 5 is improved. - Moreover, compared to the case where the
refrigerant gas channel 16 is directed in the radial direction of thecylinder 4, in the cryogenic refrigerator 1 according to the embodiment, the channel area of therefrigerant gas channel 16 can be increased, and thus, the shuttle loss and the pressure loss can be decreased. - Here, preferably, the
refrigerant gas channel 16 is provided so that the refrigerant gas flowing out from thesecond opening 18 is directed to the side surface of thecylinder 4. Accordingly, the refrigerant gas flowing out from thesecond opening 18 comes into contact with the side surface of thecylinder 4 and the movement direction of the refrigerant gas is changed, and thus, the motion of the refrigerant gas in theexpansion space 3 becomes complicated. Therefore, the vortex of the refrigerant gas in theexpansion space 3 is more easily generated, and the heat exchange efficiency between the refrigerant gas and thecooling stage 5 is further improved. - Moreover, preferably, a plurality of the
refrigerant gas channels 16, through which thefirst opening 17 and thesecond opening 18 communicate with each other, are provided on thecover portion 2 b of thedisplacer 2. Accordingly, the entire channel area of therefrigerant gas channels 16 can be increased, and it is possible to further decrease the pressure loss. Moreover, the refrigerant gas flows out of the plurality of locations into theexpansion space 3, and thus, the motion of the refrigerant gas in theexpansion space 3 becomes complicated. Accordingly, turbulent flow of the refrigerant gas in theexpansion space 3 is easily generated, and the heat exchange efficiency between the refrigerant gas and thecooling stage 5 is further improved. -
FIGS. 2A and 2B are diagrams illustrating other examples of therefrigerant gas channel 16 in the cryogenic refrigerator 1 according to the embodiment of the present invention. Also in the examples illustrated inFIGS. 2A and 2B , similar to the example illustrated inFIG. 1 , therefrigerant gas channel 16 has thefirst opening 17 as one end and thesecond opening 18 as the other end, and is provided so that theinner surface 19 and theouter surface 20 communicate with each other in thecover portion 2 b. In addition, when thefirst opening 17 on theinner surface 19 is projected to theouter surface 20 along the longitudinal direction of thedisplacer 2, the position of thefirst opening 17 and the position of thesecond opening 18 after the projection are different from each other. - However, the examples illustrated in
FIGS. 2A and 2B are different from the example illustrated inFIG. 1 . That is, the direction in which the refrigerant gas passing through onerefrigerant gas channel 16 flows into theexpansion space 3 is the same as the direction in which the refrigerant gas passing through otherrefrigerant gas channels 16 flow into theexpansion space 3. Accordingly, due to the motion of the refrigerant gas which flows into theexpansion space 3, a force operates in the direction in which the refrigerant gas in theexpansion space 3 is rotated, and thus, the vortex is easily generated in the refrigerant gas in theexpansion space 3. In addition, therefrigerant gas channel 16 is formed in a spiral shape in the example illustrated inFIG. 2B while therefrigerant gas channel 16 is linearly formed in the example illustrated inFIG. 2A . Compared to the example illustrated inFIG. 2B , the example illustrated inFIG. 2A has an advantage in that machining of therefrigerant gas channel 16 is easily performed. On the other hand, compared to the example illustrated inFIG. 2A , in the example illustrated inFIG. 2B , therefrigerant gas channel 16 is lengthened. Accordingly, the example illustrated inFIG. 2B has an advantage in that the heat exchange efficiency between the refrigerant gas flowing through therefrigerant gas channel 16 and thecover portion 2 b is improved. -
FIGS. 3A and 3B are diagrams illustrating other examples of therefrigerant gas channel 16 according to the embodiment of the present invention, and are perspective diagrams illustrating therefrigerant gas channel 16 and thecover portion 2 b. More specifically,FIGS. 3A and 3B are diagrams which illustrate a case where four refrigerant gas channels 16 (channels cover portion 2 b. Moreover, compared to the examples illustrated inFIGS. 1 to 2B , inFIGS. 3A and 3B , the shape of thecover portion 2 b are illustrated so as to be partially omitted. - Here,
FIG. 3A illustrates an example in which fourrefrigerant gas channels 16 are linearly formed from thefirst opening 17 to thesecond opening 18. Moreover,FIG. 3B illustrates an example in which fourrefrigerant gas channels 16 are formed in a spiral shape from thefirst opening 17 to thesecond opening 18. InFIGS. 3A and 3B , among fourrefrigerant gas channels 16, the direction in which the refrigerant gas passing through onerefrigerant gas channel 16 flows into theexpansion space 3 is different from a direction in which the refrigerant gas passing through anotherrefrigerant gas channel 16 flows into theexpansion space 3. - For example, in
FIG. 3A , the refrigerant gas passing through therefrigerant gas channel 16 a flows out in a lower right direction inFIG. 3A in theexpansion space 3. On the other hand, the refrigerant gas passing through therefrigerant gas channel 16 c flows out to a side opposite to the flowing-out direction of the refrigerant gas passing therefrigerant gas channel 16 a in theexpansion space 3, that is, in a lower left direction inFIG. 3A . Accordingly, due to the motion of the refrigerant gas which flows into theexpansion space 3, a force operates in the direction in which the refrigerant gas in theexpansion space 3 is rotated, and thus, the vortex is easily generated in the refrigerant gas in theexpansion space 3. - More specifically, in
FIG. 3A , fourrefrigerant gas channels 16 are provided to be rotationally symmetrical with respect to a central axis in the longitudinal direction of thedisplacer 2. Here, the central axis in the longitudinal direction of thedisplacer 2 coincides with a central axis when thecover portion 2 b is assumed as a column. Accordingly, fourrefrigerant gas channels 16 inFIG. 3A are provided to be rotationally symmetrical with respect to the central axis of thecover portion 2 b. - For example, if the
cover portion 2 b illustrated inFIG. 3A is rotated by 90° in a clockwise direction about the central axis, the positions of therefrigerant gas channels refrigerant gas channels refrigerant gas channels refrigerant gas channels - Accordingly, the refrigerant gas, which passes through the
refrigerant gas channels expansion space 3, is operated to rotate the refrigerant gas in theexpansion space 3 in the same rotation direction. As a result, the vortex is easily generated in the refrigerant gas in theexpansion space 3, and it is possible to further improve the heat exchange efficiency between the refrigerant gas and thecover portion 2 b in theexpansion space 3. - Moreover, similar to the example illustrated in
FIG. 3A , also in the example illustrated inFIG. 3B , fourrefrigerant gas channels 16 are provided to be rotationally symmetric with respect to the central axis in the longitudinal direction of thedisplacer 2. Accordingly, the effects also are similar to those of the example illustrated inFIG. 3A . That is, the vortex is easily generated in the refrigerant gas in theexpansion space 3, and it is possible to further improve the heat exchange efficiency between the refrigerant gas and thecover portion 2 b in theexpansion space 3. - As the above, it is described on the assumption that the cryogenic refrigerator 1 according to the embodiment is a one-stage refrigerator. The cryogenic refrigerator 1 is not limited to the one-stage refrigerator but may be a multi-stage refrigerator. For example, as described below, the cryogenic refrigerator 1 may be applied to a two-stage refrigerator.
-
FIG. 4 is a schematic diagram illustrating a two-stagecryogenic refrigerator 31 according to another embodiment of the present invention. Similar to the above-described one-stage cryogenic refrigerator 1, thecryogenic refrigerator 31 is a Gifford-McMahon (GM) type refrigerator using helium gas as a refrigerant gas. As illustrated inFIG. 4 , thecryogenic refrigerator 31 includes afirst displacer 32, and asecond displacer 36 which is connected to thefirst displacer 32 in the longitudinal direction. For example, as illustrated inFIGS. 5A and 5B , thefirst displacer 32 and thesecond displacer 36 are connected to each other via apin 33, aconnector 34, and apin 35. - A
first cylinder 37 is integrally formed with asecond cylinder 38, and the low temperature end of thefirst cylinder 37 and the high temperature end of thesecond cylinder 38 are connected to each other at the bottom portion of thefirst cylinder 37. Thesecond cylinder 38 is coaxially formed with thefirst cylinder 37 and is a cylinder member having a smaller diameter than thefirst cylinder 37. Thefirst cylinder 37 accommodates thefirst displacer 32 to be reciprocated in the longitudinal direction, and thesecond cylinder 38 accommodates thesecond displacer 36 to be reciprocated in the longitudinal direction. - Considering strength, thermal conductivity, helium shielding capability, or the like, for example, the
first cylinder 37 and thesecond cylinder 38 are formed of stainless steel. Thesecond displacer 36 is configured so that a film of an abrasion-resistant resin such as a fluorocarbon resin is covered on the outer circumferential surface of a pipe formed of metal such as stainless steel. - The
first displacer 32 has a cylindrical outer circumferential surface, and a first regenerator material (not illustrated) is filled in thefirst displacer 32. The internal volume of thefirst displacer 32 functions as afirst regenerator 41. Although it is not illustrated, straightening devices may be installed on the upper portion and the lower portion of thefirst regenerator 41. Anupper opening 42, which circulates the refrigerant gas from aroom temperature chamber 39 to thefirst displacer 32, is formed on the high temperature end of thefirst displacer 32. Theroom temperature chamber 39 is a space which is formed of thefirst cylinder 37 and the high temperature end of thefirst displacer 32, and the volume of the room temperature chamber is changed according to the reciprocation of thefirst displacer 32. In pipes which connect suction and exhaust systems configured of acompressor 43, asupply valve 44, and areturn valve 45 to each other, a supply-exhaust common pipe is connected to theroom temperature chamber 39. In addition, aseal 46 is mounted between a portion on the high temperature end of thefirst displacer 32 and thefirst cylinder 37. - A
refrigerant gas channel 48 which introduces the refrigerant gas into afirst expansion space 47 is formed on the low temperature end of thefirst displacer 32. Thefirst expansion space 47 is a space which is formed of thefirst cylinder 37 and thefirst displacer 32, and the volume of the expansion space is changed according to the reciprocation of thefirst displacer 32. Afirst cooling stage 49 which is thermally connected to an object to be cooled (not illustrated) is disposed at a position corresponding to thefirst expansion space 47 of the outer circumference of thefirst cylinder 37, and thefirst cooling stage 49 is cooled by the refrigerant gas of thefirst expansion space 47. - The
second displacer 36 has a cylindrical outer circumferential surface, and a second regenerator material (not illustrated) is filled in thesecond displacer 36. The internal volume of thesecond displacer 36 configures asecond regenerator 50. Thefirst expansion space 47 and the high temperature end of thesecond displacer 36 communicate with each other through a communication path (not illustrated). The refrigerant gas circulates from thefirst expansion space 47 to thesecond regenerator 50 via the communication path. - A
refrigerant gas channel 56 for circulating the refrigerant gas into asecond expansion space 51 is formed on the low temperature end of thesecond displacer 36. Thesecond expansion space 51 is a space which is formed of thesecond cylinder 38 and thesecond displacer 36, and the volume of the expansion space is changed according to the reciprocation of thesecond displacer 36. - A
second cooling stage 54 which is thermally connected to the cooling object is disposed at a position corresponding to thesecond expansion space 51 of the outer circumference of thesecond cylinder 38, and thesecond cooling stage 54 is cooled by the refrigerant gas in thesecond expansion space 51. - From the viewpoint of specific gravity, strength, thermal conductivity, or the like, the
first displacer 32 is formed of fabric based on phenol or the like. For example, the first regenerator material is configured of a wire screen or the like. In addition, for example, the second regenerator material is configured by interposing a regenerator material such as a lead ball in the axial direction by a felt and a wire screen. Moreover, aspiral groove 53 extending to thefirst expansion space 47 side in a spiral shape is formed on the outer circumference surface of thesecond displacer 36. - In the example illustrated in
FIG. 4 , therefrigerant gas channel 48 is configured to communicate with thecover portion 32 b positioned at the low temperature end of thefirst displacer 32. Therefrigerant gas channel 56 is configured to communicate with thecover portion 52 b positioned at the low temperature end of thesecond displacer 36. Similar to therefrigerant gas channel 16 illustrated inFIG. 1 , therefrigerant gas channel 48 and therefrigerant gas channel 56 are provided to be inclined with respect to the longitudinal directions of thefirst displacer 32 and thesecond displacer 36. Accordingly, the refrigerant gas passing therefrigerant gas channel 48 generates a vortex of the refrigerant gas in thefirst expansion space 47. Similarly, the refrigerant gas passing therefrigerant gas channel 56 generates a vortex of the refrigerant gas in thesecond expansion space 51. - As a result, it possible to improve the heat exchange efficiency between the refrigerant gas in the
first expansion space 47 and thefirst cooling stage 49, and the heat exchange efficiency between the refrigerant gas in thesecond expansion space 51 and thesecond cooling stage 54. Moreover, it is possible to decrease shuttle loss between thefirst cylinder 37 and thefirst displacer 32 and shuttle loss between thesecond cylinder 38 and thesecond displacer 36. -
FIGS. 5A and 5B are schematic diagrams illustrating other configurations of the two-stagecryogenic refrigerator 31 according to the embodiment of the present invention. Compared to the example illustrated inFIG. 4 , in the examples illustrated inFIGS. 5A and 5B , the shapes of therefrigerant gas channels 56 communicating with thecover portions 52 b positioned at the low temperature ends of thesecond displacers 36 are different, and other portions are in common. Accordingly, the common portions are appropriately omitted or simplified and are described. - The shape of the
refrigerant gas channel 56 in the example illustrated inFIG. 5A is similar to the shape of therefrigerant gas channel 16 illustrated inFIG. 2A . Moreover, the shape of therefrigerant gas channel 56 inFIG. 5B is similar to the shape of therefrigerant gas channel 16 illustrated inFIG. 2B . Accordingly, the effects are similar with each other, and it is possible to improve the heat exchange efficiency between the refrigerant gas in thesecond expansion space 51 and thesecond cooling stage 54. Moreover, it is possible to decrease shuttle loss between thefirst cylinder 37 and thefirst displacer 32 and shuttle loss between thesecond cylinder 38 and thesecond displacer 36. - As described above, in the cryogenic refrigerator 1 and the
cryogenic refrigerator 31 according to the embodiments, it is possible to improve the heat exchange efficiency between the refrigerant gas and the heat exchanger while decreasing the shuttle loss. - In the above, the present invention is described based on the embodiments. However, the embodiments only illustrate a principle or application of the present invention. Moreover, in the embodiments, various modifications or changes in the disposition can be performed within a scope which does not depart from the gist of the present invention defined in claims.
- For example, the above-described cryogenic refrigerators illustrate the cases where the number of the stages is one or two. However, the number of the stages can be appropriately changed to three or the like. Moreover, the embodiments describe examples in which the cryogenic refrigerator is the GM refrigerator. However, the embodiments of the present invention are not limited thereto. For example, the embodiments of the present invention can be applied to any refrigerator having the displacer such as a Stirling refrigerator or a Solvay refrigerator.
- In the above,
FIGS. 4 to 5B describe the case of therefrigerant gas channel 48 in which the shape of therefrigerant gas channel 48 communicating with thecover portion 32 b positioned at the low temperature end of thefirst displacer 32 is similar to the shape of therefrigerant gas channel 16 illustrated inFIG. 1 . However, the shape of therefrigerant gas channel 48 in the two-stagecryogenic refrigerator 31 is not limited thereto. That is, for example, the shape of therefrigerant gas channel 48 may be the shapes illustrated inFIGS. 2A and 2B orFIGS. 3A and 3B , and the effects also are similar to those of cases illustrated inFIGS. 2A and 2B orFIGS. 3A and 3B . - In the above, the case is described in which the
first opening 17 which is one end of therefrigerant gas channel 16 is provided on theinner surface 19 in the cover of the low temperature end side of thedisplacer 2 and thesecond opening 18 which is the other end is provided on theouter surface 20. Here, therefrigerant gas channel 16 may be provided so that the direction of the refrigerant gas flowing out of thesecond opening 18 is inclined with respect to the longitudinal direction of thedisplacer 2, and is not limited as long as thefirst opening 17 or thesecond opening 18 is directed onto the cover of the low temperature end side of thedisplacer 2. -
FIG. 6 is a schematic diagram illustrating the cryogenic refrigerator 1 and thedisplacer 2 according to a modification of the embodiment of the present invention. As illustrated inFIG. 6 , in the cryogenic refrigerator 1 according to the modification, thefirst opening 17 and thesecond opening 18 positioned at both ends of therefrigerant gas channel 16 are provided on themain body portion 2 a of thedisplacer 2. Here, thefirst opening 17 and thesecond opening 18 are different from each other along the longitudinal direction of thedisplacer 2, and therefrigerant gas channel 16 is directed in an inclined downward direction inFIG. 6 . - The
second opening 18 is positioned in the clearance C, and the gas, which flows from thefirst opening 17 and passes through therefrigerant gas channel 16, flows out of thesecond opening 18 toward the side surface of thecylinder 4. Accordingly, the refrigerant gas flowing out of thesecond opening 18 comes into contact with the side surface of thecylinder 4, the movement direction of the refrigerant gas is changed, and thus, the motion of the refrigerant gas in theexpansion space 3 becomes complicated. Therefore, a vortex of the refrigerant gas in theexpansion space 3 is more easily generated, and it is possible to improve the heat exchange efficiency between the refrigerant gas and thecooling stage 5. Moreover, it is possible to decrease the shuttle loss. - In the above, as illustrated in
FIG. 1 , the case is described in which thefirst opening 17 which is one end of therefrigerant gas channel 16 is provided on theinner surface 19 in the cover of the low temperature end side of thedisplacer 2, and thesecond opening 18 which is the other end is provided on theouter surface 20. In addition, for example, as illustrated inFIG. 6 , the refrigerant gas channel in which both ends of the refrigerant gas channel are provided on themain body portion 2 a of thedisplacer 2 may be further provided. In this case, the refrigerant gas channel provided on themain body portion 2 a may be a so-called “horizontal jet channel” which is orthogonal with respect to the axial direction of thedisplacer 2. - Moreover, in the cryogenic refrigerator 1 according to the modification, the number of the stages is one. However, the modification can be also applied to a case where the number of the stages is two or more. In each stage, the
refrigerant gas channel 16 is provided on the side surface of the cylinder, and the refrigerant gas channel may be provided so that the direction of the refrigerant gas flowing out of thesecond opening 18 is inclined with respect to the longitudinal direction of thedisplacer 2. In addition, thefirst opening 17 is provided on theinner surface 19 of the cover, and thesecond opening 18 may be provided on the side surface of the cylinder. - It should be understood that the invention is not limited to the above-described embodiment, but may be modified into various forms on the basis of the spirit of the invention. Additionally, the modifications are included in the scope of the invention.
Claims (5)
1. A cryogenic refrigerator comprising:
a displacer;
a cover portion which is provided on a low temperature end of the displacer; and
a cylinder which accommodates the displacer to be reciprocated in a longitudinal direction and to form an expansion space of a refrigerant gas between the cover portion and the cylinder,
wherein a refrigerant gas channel, through which the displacer and the expansion space communicate with each other, is formed in the cover portion, and
wherein a flowing-out direction of the refrigerant gas flowing into the expansion space is inclined with respect to the longitudinal direction of the displacer in the refrigerant gas channel.
2. The cryogenic refrigerator according to claim 1 ,
wherein the refrigerant gas channel is provided so that the refrigerant gas flowing into the expansion space is directed to a side surface of the cylinder.
3. The cryogenic refrigerator according to claim 1 ,
wherein the cover portion includes a plurality of the refrigerant gas channels.
4. The cryogenic refrigerator according to claim 3 ,
wherein among the plurality of refrigerant gas channels, a direction in which the refrigerant gas passing through one channel flows into the expansion space is different from a direction in which the refrigerant gas passing through other channels flows into the expansion space.
5. The cryogenic refrigerator according to claim 3 ,
wherein the plurality of refrigerant gas channels are provided to be rotationally symmetrical with respect to a central axis in the longitudinal direction of the displacer.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2013-261441 | 2013-12-18 | ||
JP2013261441A JP2015117885A (en) | 2013-12-18 | 2013-12-18 | Cryogenic refrigerating machine |
Publications (1)
Publication Number | Publication Date |
---|---|
US20150168028A1 true US20150168028A1 (en) | 2015-06-18 |
Family
ID=53367972
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US14/567,576 Abandoned US20150168028A1 (en) | 2013-12-18 | 2014-12-11 | Cryogenic refrigerator |
Country Status (3)
Country | Link |
---|---|
US (1) | US20150168028A1 (en) |
JP (1) | JP2015117885A (en) |
CN (1) | CN104729137A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN111578551A (en) * | 2019-02-19 | 2020-08-25 | 住友重机械工业株式会社 | Displacer assembly and cryogenic refrigerator |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP6573845B2 (en) * | 2016-05-31 | 2019-09-11 | 住友重機械工業株式会社 | Cryogenic refrigerator |
CN111936802B (en) * | 2018-04-06 | 2022-10-14 | 住友(Shi)美国低温研究有限公司 | Heat station for cooling circulating refrigerant |
US10753653B2 (en) | 2018-04-06 | 2020-08-25 | Sumitomo (Shi) Cryogenic Of America, Inc. | Heat station for cooling a circulating cryogen |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5398511A (en) * | 1992-03-30 | 1995-03-21 | Mitsubishi Denki Kabushiki Kaisha | Regenerative refrigerator |
US7213399B2 (en) * | 2002-06-29 | 2007-05-08 | Oerlikon Leybold Vacuum Gmbh | Refrigerator comprising a regenerator |
US20130074522A1 (en) * | 2011-09-26 | 2013-03-28 | Sumitomo Heavy Industries, Ltd. | Cryogenic refrigerator |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0356860Y2 (en) * | 1985-12-19 | 1991-12-24 | ||
JP2004183919A (en) * | 2002-11-29 | 2004-07-02 | Sumitomo Heavy Ind Ltd | Cryogenic refrigerator |
JP2011017457A (en) * | 2009-07-07 | 2011-01-27 | Toshiba Corp | Cold storage type refrigerator |
JP5468380B2 (en) * | 2009-12-24 | 2014-04-09 | 株式会社東芝 | Cold storage material and manufacturing method thereof |
JP2012193926A (en) * | 2011-03-17 | 2012-10-11 | Sumitomo Heavy Ind Ltd | Cryogenic refrigerator |
JP5714461B2 (en) * | 2011-09-21 | 2015-05-07 | 住友重機械工業株式会社 | Cryogenic refrigerator |
JP5917153B2 (en) * | 2012-01-06 | 2016-05-11 | 住友重機械工業株式会社 | Cryogenic refrigerator, displacer |
US9423160B2 (en) * | 2012-04-04 | 2016-08-23 | Sumitomo Heavy Industries, Ltd. | Regenerative refrigerator |
-
2013
- 2013-12-18 JP JP2013261441A patent/JP2015117885A/en active Pending
-
2014
- 2014-12-04 CN CN201410733757.1A patent/CN104729137A/en active Pending
- 2014-12-11 US US14/567,576 patent/US20150168028A1/en not_active Abandoned
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5398511A (en) * | 1992-03-30 | 1995-03-21 | Mitsubishi Denki Kabushiki Kaisha | Regenerative refrigerator |
US7213399B2 (en) * | 2002-06-29 | 2007-05-08 | Oerlikon Leybold Vacuum Gmbh | Refrigerator comprising a regenerator |
US20130074522A1 (en) * | 2011-09-26 | 2013-03-28 | Sumitomo Heavy Industries, Ltd. | Cryogenic refrigerator |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN111578551A (en) * | 2019-02-19 | 2020-08-25 | 住友重机械工业株式会社 | Displacer assembly and cryogenic refrigerator |
Also Published As
Publication number | Publication date |
---|---|
JP2015117885A (en) | 2015-06-25 |
CN104729137A (en) | 2015-06-24 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5917153B2 (en) | Cryogenic refrigerator, displacer | |
JP6403539B2 (en) | Cryogenic refrigerator | |
US9784479B2 (en) | Cryogenic refrigerator and displacer | |
US9423160B2 (en) | Regenerative refrigerator | |
US20150168028A1 (en) | Cryogenic refrigerator | |
US20160097567A1 (en) | Cryogenic refrigerator | |
US10274230B2 (en) | Annular portions protruding from a displacer and expansion space of a cryocooler | |
US20130219923A1 (en) | Cryogenic refrigerator | |
US9841212B2 (en) | Cryogenic refrigerator | |
JP5714461B2 (en) | Cryogenic refrigerator | |
US9494346B2 (en) | Cryogenic refrigerator | |
JP6376793B2 (en) | Regenerator type refrigerator | |
US20140026596A1 (en) | Cryogenic refrigerator | |
US9453662B2 (en) | Cryogenic refrigerator | |
US10976080B2 (en) | Pulse tube cryocooler and method of manufacturing pulse tube cryocooler | |
US20150233609A1 (en) | Cryogenic refrigerator | |
JP6440361B2 (en) | Cryogenic refrigerator | |
US9759459B2 (en) | Regenerator and regenerative refrigerator with insertion member | |
JP6284788B2 (en) | Displacer | |
JP2015166665A (en) | Cold storage device and partition unit |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: SUMITOMO HEAVY INDUSTRIES, LTD., JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LEI, TIAN;XU, MINGYAO;SIGNING DATES FROM 20141202 TO 20141204;REEL/FRAME:034482/0662 |
|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |