JP2017048937A - Cryogenic refrigeration machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce heat loss by compression heat which can occur in an expander of a cryogenic refrigeration machine.SOLUTION: A cryogenic refrigeration 10 includes: a displacer 24 having a cold storage device 16 which has a cold storage device high temperature part 16a on one side in the axial direction and has a cold storage device low temperature part 16b on the opposite side, and capable of reciprocating in the axial direction; an expander stationary portion 22 which is the expander stationary portion 22 for accommodating the displacer 24 and for supporting the displacer 24 in a manner reciprocating in the axial direction, which forms a gas space 44 between itself and the displacer 24 on the cold storage device high temperature part 16a side and which forms a gas expansion chamber 40 between itself and the displacer 24 on the cold storage device low temperature 16b side; a seal part 50 arranged between the displacer 24 and the expander stationary portion 22 so as to cut off an axial direction gas flow between the gas space 44 and the gas expansion chamber 40; and a first gas flow passage 36 which is for gas circulation between the expander stationary portion 22 and the cold storage device 16 and which is constituted so as to detour the gas space 44 and go through the seal part 50.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cryogenic refrigerator.

  A cryogenic refrigerator represented by a Gifford-McMahon (GM) refrigerator has an expander and a compressor for working gas (also referred to as refrigerant gas). Such an expander of a cryogenic refrigerator usually has a displacer that reciprocates in an axial direction by a driving means and a regenerator built in the displacer. The displacer is accommodated in a cylinder that guides the reciprocal movement. The variable volume formed between the two by the relative movement of the displacer with respect to the cylinder is used as an expansion chamber for the working gas. The expander adiabatically expands the high-pressure gas supplied from the compressor in the expansion chamber, thereby generating cold.

JP 2014-194291 A Japanese Patent Laying-Open No. 2015-117872

  Another variable volume, a so-called compression chamber, can be formed between the displacer and the cylinder in the axial direction on the opposite side of the expansion chamber. When the compression chamber is narrowed by the relative movement of the displacer with respect to the cylinder, the gas staying there can be compressed by the displacer. The heat of compression associated with gas compression can cause heat loss in the cryogenic refrigerator. In particular, the greater the capacity of the cryogenic refrigerator, the greater the heat loss due to compression heat.

  One exemplary object of one aspect of the present invention is to reduce heat loss due to compression heat that can occur in an expander of a cryogenic refrigerator.

  According to an aspect of the present invention, a cryogenic refrigerator includes a regenerator having a regenerator high-temperature part on one side in the axial direction and a regenerator low-temperature part on the opposite side, and is capable of reciprocating in the axial direction. And an expander stationary part that accommodates the displacer and supports the displacer so as to be capable of reciprocating in the axial direction, wherein a gas space is formed between the displacer and the regenerator at a high temperature part side, and the regenerator An expander stationary part forming a gas expansion chamber between the displacer on the low temperature side, and the displacer and the expander stationary so as to block an axial gas flow between the gas space and the gas expansion chamber. And a gas flow path for gas flow between the expander stationary part and the regenerator, bypassing the gas space and passing through the seal part. Cormorants and a gas flow path configured.

  In addition, what replaced the component and expression of this invention between methods, apparatuses, systems, etc. is also effective as an aspect of this invention.

  ADVANTAGE OF THE INVENTION According to this invention, the heat loss by the compression heat which can arise in the expander of a cryogenic refrigerator can be reduced.

The whole structure of the cryogenic refrigerator which concerns on one embodiment of this invention is shown schematically, and the cross section of the expander of a cryogenic refrigerator is shown schematically. The cross section of the principal part of the expander of the cryogenic refrigerator which concerns on one embodiment of this invention is shown roughly. 1 schematically shows a cross section of a part of an expander of a cryogenic refrigerator according to an embodiment of the present invention.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. Moreover, the structure described below is an illustration and does not limit the scope of the present invention at all.

  FIG. 1 is a diagram schematically showing a cryogenic refrigerator 10 according to an embodiment of the present invention. The illustrated cryogenic refrigerator 10 is a single-stage GM refrigerator. The basic structure and operation of the GM refrigerator are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2014-194291 and 2015-117872. These documents are incorporated herein by reference in their entirety.

  The cryogenic refrigerator 10 includes a compressor 12 that compresses the working gas and an expander 14 that cools the working gas by adiabatic expansion. The working gas is, for example, helium gas. The expander 14 is also called a cold head. The expander 14 is provided with a regenerator 16 for precooling the working gas. The cryogenic refrigerator 10 includes a gas pipe 18 including a first pipe 18a and a second pipe 18b that connect the compressor 12 and the expander 14, respectively.

  As is known, a working gas having a first high pressure is supplied from the discharge port of the compressor 12 to the expander 14 through the first pipe 18a. Due to the adiabatic expansion in the expander 14, the working gas is depressurized from the first high pressure to a lower second high pressure. The working gas having the second high pressure is recovered from the expander 14 to the suction port of the compressor 12 through the second pipe 18b. The compressor 12 compresses the recovered working gas having the second high pressure. Thus, the working gas is again boosted to the first high pressure. In general, both the first high pressure and the second high pressure are considerably higher than the atmospheric pressure. For convenience of explanation, the first high pressure and the second high pressure are also simply referred to as high pressure and low pressure, respectively.

  The expander 14 includes an expander movable part 20 and an expander stationary part 22. The expander movable portion 20 is configured to be capable of reciprocating in the axial direction (vertical direction in FIG. 1) with respect to the expander stationary portion 22. The moving direction of the expander movable portion 20 is indicated by an arrow A in FIG. The expander stationary part 22 is configured to support the expander movable part 20 so as to be capable of reciprocating in the axial direction. The expander stationary part 22 is configured as an airtight container that houses the expander movable part 20 together with high-pressure gas (including the first high-pressure gas and the second high-pressure gas).

  The expander movable part 20 includes a displacer 24 and a displacer drive shaft 26 that drives the reciprocation thereof. The displacer 24 incorporates a regenerator 16. The displacer 24 includes a displacer member 24 a that surrounds the regenerator 16. A cool storage material is filled in the internal space of the displacer member 24 a, whereby the cool storage 16 is formed in the displacer 24. The displacer 24 has, for example, a substantially cylindrical shape extending in the axial direction. The displacer member 24a has a substantially uniform outer diameter and inner diameter in the axial direction. Therefore, the regenerator 16 also has a substantially cylindrical shape extending in the axial direction.

  The expander stationary portion 22 roughly has a two-part configuration including a cylinder 28 and a drive mechanism housing 30. The axially upper part of the expander stationary part 22 is a drive mechanism housing 30, and the axially lower part of the expander stationary part 22 is a cylinder 28, which are firmly connected to each other. The cylinder 28 is configured to guide the reciprocating movement of the displacer 24. The cylinder 28 extends from the drive mechanism housing 30 in the axial direction. The cylinder 28 has a substantially uniform inner diameter in the axial direction, and thus the cylinder 28 has a substantially cylindrical inner surface extending in the axial direction. This inner diameter is slightly larger than the outer diameter of the displacer member 24a.

  The cylinder 28 includes a first thickness region 28a having a first thickness T1 in the radial direction and a second thickness region 28b having a second thickness T2 in the radial direction. The first thickness region 28a and the second thickness region 28b are annular portions having different diameters that extend in the circumferential direction and are adjacent to each other in the axial direction and continuous. The first thickness T1 is larger than the second thickness T2. Since the cylinder 28 has a constant inner diameter, the first outer diameter of the cylinder 28 in the first thickness region 28a is larger than the second outer diameter of the cylinder 28 in the second thickness region 28b. Each of the first outer diameter and the second outer diameter is substantially uniform in the axial direction. Thus, the cylinder 28 has the first step portion 28c on its outer surface. The first step portion 28c is located at the boundary between the first thickness region 28a and the second thickness region 28b.

  In this way, by forming a thick portion in the high temperature portion of the cylinder 28 and forming a thin portion in the low temperature portion of the cylinder 28, heat can be easily released from the high temperature portion of the cylinder 28 to the drive mechanism housing 30. Therefore, the heat intrusion from the high temperature portion of the cylinder 28 to the low temperature portion can be reduced.

  The cylinder 28 may have a second step portion 28d on its outer surface. The second step portion 28d is located at the boundary between the flange portion 28e and the first thickness region 28a. The flange portion 28 e is provided for attaching the cylinder 28 to the drive mechanism housing 30. The outer diameter of the flange portion 28e is larger than the first outer diameter of the first thickness region 28a.

  The expander stationary part 22 includes a cooling stage 32. The cooling stage 32 is fixed to the end of the cylinder 28 on the opposite side of the drive mechanism housing 30 in the axial direction. The cooling stage 32 is provided to conduct the cold generated by the expander 14 to other objects. The object is attached to the cooling stage 32 and is cooled by the cooling stage 32 when the cryogenic refrigerator 10 is operated.

  During the operation of the cryogenic refrigerator 10, the regenerator 16 has a regenerator high-temperature part 16a on one side (upper side in the figure) in the axial direction and a regenerator low-temperature part 16b on the opposite side (lower side in the figure). . Thus, the regenerator 16 has a temperature distribution in the axial direction. The other components of the expander 14 (eg, the displacer 24 and the cylinder 28) surrounding the regenerator 16 have an axial temperature distribution as well, so that the expander 14 has a high temperature section on one axial side during its operation. A low temperature part is provided on the other side in the axial direction. The high temperature part has a temperature of about room temperature, for example. The low temperature part varies depending on the use of the cryogenic refrigerator 10, but is cooled to a certain temperature included in a range of about 100 K to about 10 K, for example. The cooling stage 32 is fixed to the cylinder 28 so as to enclose the low temperature portion of the cylinder 28.

  In this document, the terms axial direction, radial direction, and circumferential direction are used for convenience of explanation. The axial direction represents the moving direction of the expander movable part 20 relative to the expander stationary part 22 as illustrated by the arrow A. The radial direction represents a direction perpendicular to the axial direction (lateral direction in the figure), and the circumferential direction represents a direction surrounding the axial direction. When an element of the expander 14 is relatively close to the cooling stage 32 with respect to the axial direction, it may be referred to as “lower” and when it is relatively far away, it may be referred to as “upper”. Therefore, the high temperature part and the low temperature part of the expander 14 are located in the upper part and the lower part in the axial direction, respectively. These expressions are only used to help understand the relative positional relationship between the elements of the expander 14 and are not related to the placement of the expander 14 when installed in the field. For example, the expander 14 may be installed with the cooling stage 32 facing upward and the drive mechanism housing 30 facing downward. Or the expander 14 may be installed so that an axial direction may correspond to a horizontal direction.

  The flow path configuration of the working gas in the expander 14 will be described. The expander 14 includes a valve portion 34, a first gas flow path 36, a second gas flow path 38, a gas expansion chamber 40, and a low pressure gas chamber 42. In short, the high-pressure gas flows from the first pipe 18 a into the gas expansion chamber 40 through the valve portion 34, the first gas flow path 36, the regenerator 16, and the second gas flow path 38. The return gas from the gas expansion chamber 40 is received by the low pressure gas chamber 42 via the second gas flow path 38, the regenerator 16, the first gas flow path 36, and the valve portion 34.

  The valve unit 34 is configured to control the pressure of the gas expansion chamber 40 in synchronization with the reciprocating movement of the displacer 24. The valve unit 34 functions as a part of a supply path for supplying high-pressure gas to the gas expansion chamber 40 and also functions as a part of a discharge path for discharging low-pressure gas from the gas expansion chamber 40. The valve unit 34 is configured to end the discharge of the low-pressure gas and start the supply of the high-pressure gas when the displacer 24 passes through the bottom dead center or the vicinity thereof. The valve unit 34 is configured to stop supplying the high-pressure gas and start discharging the low-pressure gas when the displacer 24 passes through the top dead center or the vicinity thereof. As described above, the valve unit 34 is configured to switch between the function of supplying and discharging the working gas in synchronization with the reciprocating movement of the displacer 24.

  The first gas flow path 36 is provided for gas flow between the expander stationary part 22 and the regenerator 16. The first gas flow path 36 connects the valve portion 34 to the regenerator high temperature portion 16a. Therefore, the first gas flow path 36 is formed in the high temperature part of the expander 14. Details of the first gas flow path 36 will be described later.

  The second gas flow path 38 is at least one opening of the displacer member 24 a formed to communicate the regenerator low temperature portion 16 b with the gas expansion chamber 40. The second gas flow path 38 is formed in the low temperature part of the expander 14.

  The gas expansion chamber 40 is formed between the cylinder 28 and the displacer 24 on the regenerator low temperature portion 16b side. The second thickness region 28 b of the cylinder 28 extends in the circumferential direction and the axial direction so as to surround the gas expansion chamber 40.

  The low pressure gas chamber 42 is defined inside the drive mechanism housing 30. The second pipe 18b is connected to the drive mechanism housing 30, whereby the low-pressure gas chamber 42 communicates with the suction port of the compressor 12 through the second pipe 18b. Therefore, the low pressure gas chamber 42 is always maintained at a low pressure.

  The expander 14 includes a gas space 44. Similarly to the gas expansion chamber 40, the gas space 44 is a variable volume formed between the expander movable portion 20 and the expander stationary portion 22. Due to the relative movement of the displacer 24 with respect to the cylinder 28, the volume of the gas space 44 varies in a complementary manner to the volume of the gas expansion chamber 40.

  The gas space 44 is formed between the expander stationary part 22 and the displacer 24 on the regenerator high temperature part 16a side. More specifically, the gas space 44 is sandwiched between the drive mechanism housing 30 and the displacer 24 in the axial direction, and is surrounded by the cylinder 28 in the circumferential direction. The gas space 44 is adjacent to the low pressure gas chamber 42. The first thickness region 28 a of the cylinder 28 extends in the circumferential direction and the axial direction so as to surround the gas space 44. The gas space 44 is also called a room temperature chamber.

  Importantly, the gas space 44 is not included in the flow path configuration described above. The gas space 44 is isolated from the regenerator 16. For this purpose, the first gas flow path 36 is formed so as to bypass the gas space 44. Therefore, although the gas space 44 is located at the same place as a space called a compression chamber in a conventional general expander, no working gas flows between the gas space 44 and the gas expansion chamber 40. Since there is substantially no compression of the working gas in the gas space 44, the gas space 44 is no longer a compression chamber.

  The displacer drive shaft 26 protrudes from the displacer 24 through the gas space 44 to the low pressure gas chamber 42. The expander stationary portion 22 includes a pair of drive shaft guides 46a and 46b that support the displacer drive shaft 26 so as to be movable in the axial direction. The drive shaft guides 46a and 46b are provided in the drive mechanism housing 30 so as to surround the displacer drive shaft 26, respectively. The gas space 44 communicates with the low-pressure gas chamber 42 through the clearance between the axially lower drive shaft guide 46 b and the displacer drive shaft 26. Therefore, the gas space 44 is also maintained at a low pressure similarly to the low-pressure gas chamber 42.

  Note that another opening for communicating the gas space 44 with the low-pressure gas chamber 42 may be formed in the expander stationary portion 22 (the cylinder 28 and / or the drive mechanism housing 30).

  Thus, the gas space 44 becomes a part of the low-pressure gas chamber 42, whereby the volume of the low-pressure gas chamber 42 can be effectively increased. The efficiency of the cryogenic refrigerator 10 increases as the volume of the low-pressure gas chamber 42 increases.

  The expander 14 includes a displacer driving mechanism 48 accommodated in the low pressure gas chamber 42. The displacer drive mechanism 48 includes a motor 48a and a scotch yoke mechanism 48b. The displacer drive shaft 26 forms a part of the scotch yoke mechanism 48b. The displacer drive shaft 26 is connected to the scotch yoke mechanism 48b so as to be driven in the axial direction by the scotch yoke mechanism 48b. Accordingly, the axial reciprocation of the displacer 24 is driven by the rotation of the motor 48a. The drive shaft guides 46a and 46b are at different positions in the axial direction with the scotch yoke mechanism 48b interposed therebetween.

  The valve unit 34 is connected to the displacer driving mechanism 48 and is accommodated in the driving mechanism housing 30. The valve part 34 takes the form of a rotary valve. Therefore, the valve portion 34 includes a rotor valve member 34a and a stator valve member 34b. The rotor valve member 34a is connected to the output shaft of the motor 48a so as to rotate by the rotation of the motor 48a. The rotor valve member 34a is in surface contact with the stator valve member 34b so as to rotate and slide with respect to the stator valve member 34b. The stator valve member 34 b is fixed to the drive mechanism housing 30. The stator valve member 34b is configured to receive high pressure gas entering the drive mechanism housing 30 from the first pipe 18a.

  FIG. 2 schematically shows a cross section of a main part of the expander 14 according to an embodiment of the present invention. In FIG. 2, the state when the displacer 24 is located at the bottom dead center is indicated by a solid line, and the state when the displacer 24 is located at the top dead center is indicated by a broken line.

  As shown in FIGS. 1 and 2, the expander 14 is disposed between the displacer 24 and the expander stationary portion 22 to block axial gas flow between the gas space 44 and the gas expansion chamber 40. The seal part 50 is provided. The seal portion 50 includes a first seal member 50a and a second seal member 50b that are arranged apart from each other in the axial direction so as to define a gas flow gap 52 therebetween. The first seal member 50 a is disposed between the displacer 24 and the first thickness region 28 a of the cylinder 28. The second seal member 50b is disposed between the displacer 24 and the first thickness region 28a (or the second thickness region 28b) of the cylinder 28. Thus, the seal portion 50 is attached to the high temperature portion of the displacer 24.

  The first seal member 50a and the second seal member 50b are respectively attached to the displacer member 24a and extend in the circumferential direction. The first seal member 50a is attached to the upper lid portion of the displacer member 24a, and the second seal member 50b is attached to the side tube portion of the displacer member 24a.

  The first seal member 50 a is configured to block the gas flow between the gas space 44 and the gas flow gap 52. The second seal member 50 b is configured to block the gas flow between the gas flow gap 52 and the gas expansion chamber 40. Each of the first seal member 50a and the second seal member 50b is, for example, a slipper seal. The first seal member 50a and the second seal member 50b may be other contact seals or non-contact seals as long as they have a desired sealing performance.

  The gas flow gap 52 is an annular cavity that surrounds the displacer 24 in the circumferential direction along these two seal members. The gas flow gap 52 is sandwiched between the displacer 24 and the cylinder 28 in the radial direction.

  The first gas flow path 36 is configured to bypass the gas space 44 and pass through the seal portion 50. The first gas flow path 36 includes a connection passage 54, a gas flow gap 52, and a communication passage 56. Since the gas flow gap 52 is sandwiched between the two seal members, no gas leakage from the first gas flow path 36 to the gas space 44 occurs. Similarly, no gas leakage from the first gas flow path 36 to the gas expansion chamber 40 occurs.

  The connection passage 54 is formed in the expander stationary part 22. The connection passage 54 starts from the valve portion 34 and ends at the gas flow gap 52. The connection passage 54 penetrates from the drive mechanism housing 30 to the first thickness region 28 a of the cylinder 28. The connection passage 54 extends in the drive mechanism housing 30 in the axial direction and is bent inward in the radial direction in the first thickness region 28 a of the cylinder 28. The connection passage 54 is provided on one side of the expander stationary portion 22 (the side where the valve portion 34 is disposed in the radial direction).

  An outlet 54 a of the connection passage 54 is open to the gas circulation gap 52 adjacent to the gas circulation gap 52 in the radial direction. The outlet 54 a of the connection passage 54 is formed in the first thickness region 28 a of the cylinder 28. The outlet 54 a of the connection passage 54 may be formed in the second thickness region 28 b of the cylinder 28.

  The outlet 54a of the connection passage 54 is set so as to be within the seal portion 50 (that is, between the first seal member 50a and the second seal member 50b) within the range of the stroke of the displacer 24. In other words, the outlet 54a of the connection passage 54 is positioned below the first seal member 50a in the axial direction when the displacer 24 is at bottom dead center (see the solid line in FIG. 2), and the displacer 24 is at top dead center. Sometimes it is located above the second seal member 50b in the axial direction (see the broken line in FIG. 2). Thus, the outlet 54a of the connection passage 54 has an axial position determined so as to be sandwiched between the first seal member 50a and the second seal member 50b during the reciprocating movement of the displacer 24. In this way, the connection of the connection passage 54 to the gas flow gap 52 can always be maintained throughout the cooling cycle.

  The communication path 56 is an opening formed in the displacer member 24a along the radial direction. The communication path 56 is formed between the first seal member 50a and the second seal member 50b in the axial direction. The communication path 56 communicates the gas circulation gap 52 with the regenerator high temperature portion 16a.

  The operation of the cryogenic refrigerator 10 having the above configuration will be described. When the displacer 24 moves to a position at or near the bottom dead center of the cylinder 28, the valve unit 34 is switched to connect the discharge port of the compressor 12 to the gas expansion chamber 40. The high-pressure gas enters the regenerator high-temperature part 16 a through the first gas flow path 36 from the valve part 34. At this time, the gas passes through the connection passage 54, the gas flow gap 52, and the communication passage 56. The gas is cooled while passing through the regenerator 16, and enters the gas expansion chamber 40 from the regenerator low temperature portion 16 b through the second gas flow path 38. While the gas flows into the gas expansion chamber 40, the displacer 24 moves toward the top dead center of the cylinder 28. Thereby, the volume of the gas expansion chamber 40 is increased. Thus, the gas expansion chamber 40 is filled with the high pressure gas.

  When the displacer 24 moves to a position at or near the top dead center of the cylinder 28, the valve unit 34 is switched to connect the suction port of the compressor 12 to the gas expansion chamber 40. The high pressure gas is expanded and cooled in the gas expansion chamber 40. The expanded gas enters the regenerator 16 from the gas expansion chamber 40 through the second gas flow path 38. The gas is cooled while passing through the regenerator 16. The gas returns from the regenerator 16 to the compressor 12 through the first gas flow path 36, the valve portion 34, and the low pressure gas chamber 42. While the gas flows out of the gas expansion chamber 40, the displacer 24 moves toward the bottom dead center of the cylinder 28. Thereby, the volume of the gas expansion chamber 40 is reduced, and the low-pressure gas is discharged from the gas expansion chamber 40.

  The above is one cooling cycle in the cryogenic refrigerator 10. The cryogenic refrigerator 10 cools the cooling stage 32 to a desired temperature by repeating the cooling cycle. Therefore, the cryogenic refrigerator 10 can cool the object thermally coupled to the cooling stage 32 to a cryogenic temperature.

  As described above, the first gas flow path 36 is formed so as to bypass the gas space 44 and pass through the seal portion 50. The working gas flow circulating through the compressor 12 and the expander 14 flows between the two seal members without passing through the gas space 44. Therefore, the gas space 44 generates little or no compression heat as opposed to gas compression occurring at a location corresponding to the gas space 44 in a conventional general expander. Therefore, the expander 14 of the cryogenic refrigerator 10 according to the embodiment can greatly reduce heat loss due to compression heat as compared with the conventional expander 14. Moreover, the efficiency of the cryogenic refrigerator 10 is improved. Such an advantage is remarkable in the cryogenic refrigerator 10 having a large volume of the gas space 44, that is, the large-capacity cryogenic refrigerator 10.

  In the above, this invention was demonstrated based on the Example. It will be understood by those skilled in the art that the present invention is not limited to the above-described embodiment, and various design changes are possible, various modifications are possible, and such modifications are within the scope of the present invention. By the way.

  FIG. 3 schematically shows a partial cross section of an expander 14 according to an embodiment of the present invention. In FIG. 3, a part of the cylinder 28 is indicated by a solid line and a part of the displacer 24 is indicated by a broken line to help understanding.

  The first gas flow path 36 can take various shapes. For example, the connection passage 54 may include an outlet groove 58 formed along the circumferential direction. The outlet groove 58 is continuous over the entire circumference. The connection passage 54 may include a plurality of outlet grooves or outlet holes arranged in the circumferential direction. Similarly, the communication path 56 of the displacer member 24a may also include at least one groove formed along the circumferential direction, or a plurality of holes arranged in the circumferential direction. In this way, the circumferential flow distribution of the working gas flowing into the regenerator 16 can be made uniform. This helps to uniform the temperature distribution in the cross section perpendicular to the axial direction of the regenerator 16.

  In the above, the embodiment has been described with reference to a single-stage GM refrigerator. The present invention is not limited to this, and the working gas flow path configuration according to the embodiment can be applied to a two-stage or multi-stage GM refrigerator or other cryogenic refrigerator having a displacer built-in regenerator. .

  10 cryogenic refrigerator, 14 expander, 16 regenerator, 16a regenerator high temperature part, 16b regenerator low temperature part, 22 expander stationary part, 24 displacer, 24a displacer member, 28 cylinder, 28a first thickness region, 28b 2nd thickness area, 34 valve part, 36 1st gas flow path, 40 gas expansion chamber, 42 low pressure gas chamber, 44 gas space, 50 seal part, 50a 1st seal member, 50b 2nd seal member, 52 gas distribution Clearance, 54 connection passage, 54a outlet, 56 communication passage, 58 outlet groove.

Claims (7)

A displacer having a regenerator having a regenerator high temperature part on one side in the axial direction and a regenerator low temperature part on the opposite side, and capable of reciprocating in the axial direction;
An expander stationary part that accommodates the displacer and supports the displacer so as to be capable of reciprocating in the axial direction, forming a gas space with the displacer on the regenerator high temperature part side, and the regenerator low temperature part An expander stationary part forming a gas expansion chamber with the displacer on the side of
A seal disposed between the displacer and the expander stationary portion to block axial gas flow between the gas space and the gas expansion chamber;
A gas flow path for gas flow between the expander stationary part and the regenerator, wherein the gas flow path is configured to bypass the gas space and pass through the seal portion. Features a cryogenic refrigerator. Further comprising a valve portion accommodated in the expander stationary portion and configured to control the pressure of the gas expansion chamber in synchronization with the reciprocating movement of the displacer;
The displacer comprises a displacer member having a substantially uniform outer diameter in the axial direction and surrounding the regenerator,
The seal portion includes first and second seal members that are spaced apart in the axial direction so as to define a gas flow gap therebetween, and the first and second seal members are respectively attached to the displacer member and are circumferentially mounted. Extending in a direction, the first seal member is configured to block a gas flow between the gas space and the gas flow gap, and the second seal member includes the gas flow gap and the gas expansion chamber. Configured to block the gas flow between
The gas flow path is
A connection passage formed in the stationary part of the expander, starting from the valve part and terminating in the gas flow gap;
The cryogenic refrigerator according to claim 1, further comprising: a communication path formed in the displacer member and communicating the gas circulation gap with the regenerator high-temperature portion. The expander stationary part includes an outlet of the connection passage that is adjacent to the gas flow gap in the radial direction and opened to the gas flow gap,
The pole according to claim 2, wherein the outlet of the connection passage has an axial position determined so as to be sandwiched between the first seal member and the second seal member during reciprocal movement of the displacer. Low temperature refrigerator. The expander stationary part includes a cylinder that guides the reciprocating movement of the displacer,
The cylinder includes an outlet of the connection passage that is adjacent to the gas flow gap in the radial direction and opened to the gas flow gap,
The cylinder extends in the circumferential direction and the axial direction so as to surround the gas space, and a first thickness region extending in a circumferential direction and an axial direction so as to surround the gas space and having a first thickness in the radial direction. A second thickness region having a second thickness in a radial direction, and the first thickness is greater than the second thickness,
The cryogenic refrigerator according to claim 2 or 3, wherein an outlet of the connection passage is formed in the first thickness region.   5. The pole according to claim 2, wherein the connection passage includes at least one outlet groove formed along a circumferential direction or a plurality of outlet holes arranged in the circumferential direction. Low temperature refrigerator. The expander stationary portion includes a gas chamber that receives the return gas from the gas expansion chamber through the gas flow path,
The cryogenic refrigerator according to claim 1, wherein the gas space communicates with the gas chamber.   The cryogenic refrigerator according to any one of claims 1 to 6, wherein the cryogenic refrigerator is a single-stage cryogenic refrigerator.

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