JP6440361B2 - Cryogenic refrigerator - Google Patents

Description

  The present invention relates to a regenerator-type cryogenic refrigerator that stores cold heat generated by expanding refrigerant gas in a regenerator material.

  A Gifford-McMahon (GM) refrigerator is known as a refrigerator that generates an extremely low temperature. The GM refrigerator changes the volume of the expansion space by reciprocating the displacer in the cylinder. The refrigerant gas is expanded in the expansion space by selectively connecting the expansion space, the discharge side of the compressor, and the intake side in response to the volume change. The GM refrigerator cools the object to be cooled using the cold generated at this time.

JP 2008-224161 A

  The cylinder in the GM refrigerator needs at least a length for the displacer to reciprocate. In particular, in the case of a multi-stage GM refrigerator that connects a plurality of displacers in series to generate cold, the overall length of the GM refrigerator is longer than that of a single-stage GM refrigerator.

  On the other hand, the GM refrigerator is used by being incorporated into a device utilizing superconductivity, for example. In this case, the refrigerator cannot be increased without limitation due to restrictions of the apparatus into which the refrigerator is incorporated, and in particular, it is required to shorten the overall length.

  This invention is made | formed in view of such a subject, The objective is to provide the technique which shortens the full length of a multistage cryogenic refrigerator.

  In order to solve the above problems, a cryogenic refrigerator according to an aspect of the present invention includes a connection pin, a low-temperature displacer having a first pin hole for inserting the connection pin, and a second pin hole for inserting the connection pin. The high-temperature side displacer is connected to the low-temperature side displacer with a connection pin, and the cylinder is provided for housing the low-temperature side displacer and the high-temperature side displacer. The axial direction of the low temperature side displacer is the first axial direction, the axial direction of the first pin hole is the second axial direction, and the direction perpendicular to the first and second axes is the third axial direction. When the clearance in the third axial direction between the pins is w and the clearance in the third axial direction between the cylinder and the low temperature displacer is β, β <w is established.

  According to the regenerator type refrigeration of the present invention, it is possible to provide a technique for shortening the overall length of a multistage cryogenic refrigerator.

It is a schematic diagram which shows the cross section of the cylinder in the two-stage type GM refrigerator which concerns on embodiment. It is a schematic diagram explaining the connection part of the high temperature side displacer and the low temperature side displacer in the two-stage GM refrigerator which concerns on embodiment. It is a schematic diagram explaining the comparative example of the connection part of a 1st stage displacer and a 2nd stage displacer. FIGS. 4A and 4B are schematic diagrams for explaining the difference between the GM refrigerator that employs the connecting portion according to the comparative example and the GM refrigerator according to the embodiment. It is a figure for demonstrating the difference of the full length of the GM refrigerator which employ | adopted the connection part which concerns on a comparative example, and the GM refrigerator which concerns on embodiment. It is a schematic diagram explaining the clearance between the connection pin and pin hole which concern on embodiment. It is a figure which shows the various aspects of the combination of the shape of a pin hole, and the cross-sectional shape of a connection pin.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

  Examples of the cryogenic refrigerator include a GM refrigerator and a Stirling refrigerator. Hereinafter, the cryogenic refrigerator according to the embodiment of the present invention will be described on the assumption of a two-stage GM refrigerator. However, the present invention can be applied to a refrigerator having a multi-stage displacer, and is not limited to a two-stage GM refrigerator.

  FIG. 1 is a schematic diagram showing a cross section of a cylinder in a two-stage GM refrigerator 10 according to an embodiment. The GM refrigerator 10 is a cryogenic refrigerator that uses, for example, helium gas as a refrigerant gas. As shown in FIG. 1, the GM refrigerator 10 includes a GM refrigerator drive unit 1, a compressor 2, a gas pipeline 3, and a two-stage cylinder 4. The two-stage cylinder 4 is fixed to the drive unit 1.

  The two-stage cylinder 4 includes a high-temperature side cylinder 4 a 1 and a low-temperature side cylinder 4 a 2, which are integrally formed to constitute the two-stage cylinder 4. The high temperature side cylinder 4a1 and the low temperature side cylinder 4a2 each have a high temperature end and a low temperature end. The low temperature end of the high temperature side cylinder 4a1 and the high temperature end of the low temperature side cylinder 4a2 are connected at the bottom of the high temperature side cylinder 4a1.

  The low temperature side cylinder 4a2 is formed in a form extending in the same axial direction as the high temperature side cylinder 4a1, and is a cylindrical member having a smaller diameter than the high temperature side cylinder 4a1. The high temperature side cylinder 4a1 accommodates the high temperature side displacer 4b1 so as to reciprocate in the longitudinal direction, and the low temperature side cylinder 4a2 accommodates the low temperature side displacer 4b2 so as to be capable of reciprocating in the longitudinal direction.

  For example, stainless steel is used for the high temperature side cylinder 4a1 and the low temperature side cylinder 4a2 in consideration of strength, thermal conductivity, helium blocking ability, and the like. The outer periphery of the low temperature side displacer 4b2 is a cylinder made of metal such as stainless steel. A film of an abrasion-resistant resin such as a fluororesin may be formed on the outer peripheral surface of the low temperature side displacer 4b2.

  A high temperature end of the high temperature side cylinder 4a1 is provided with a Scotch yoke mechanism (not shown) for reciprocatingly driving the high temperature side displacer 4b1 and the low temperature side displacer 4b2. The high temperature side displacer 4b1 and the low temperature side displacer 4b2 reciprocate along the high temperature side cylinder 4a1 and the low temperature side cylinder 4a2, respectively. Each of the high temperature side displacer 4b1 and the low temperature side displacer 4b2 includes a high temperature end and a low temperature end.

  The high temperature side displacer 4b1 has a cylindrical outer peripheral surface, and the high temperature side displacer 4b1 is filled with the first cold storage material E1. The internal volume of the high temperature side displacer 4b1 functions as a first regenerator.

  The room temperature chamber 12 is a space formed by the high temperature side cylinder 4a1 and the high temperature end of the high temperature side displacer 4b1, and its volume changes as the high temperature side displacer 4b1 moves back and forth. A seal 5a is mounted between a portion from the high temperature end of the high temperature side displacer 4b1 and the high temperature side cylinder 4a1.

  A first expansion space 18 for expanding the refrigerant gas is formed between the low temperature end of the high temperature side displacer 4b1 and the high temperature side cylinder 4a1. The volume of the first expansion space 18 changes with the reciprocating movement of the high temperature side displacer 4b1. A first cooling stage C1 that is thermally connected to the object to be cooled is disposed at a position corresponding to the first expansion space 18 in the outer periphery of the high temperature side cylinder 4a1. The first cooling stage C1 is cooled by cold generated when the refrigerant gas expands in the first expansion space 18.

The low temperature side displacer 4b2 has a cylindrical outer peripheral surface. Of the internal volume of the low temperature side displacer 4b2, the high temperature side region is filled with a second regenerator material E2 made of a nonmagnetic material such as lead or bismuth. The cold side of the partition member (not shown), different regenerator material is a high temperature side region, for example, a second regenerator material E2 of the magnetic material such as HoCu ₂ is filled. The internal volume of the low temperature side displacer 4b2 functions as a second regenerator.

  A second expansion space 26 is formed by the low temperature side cylinder 4a2 and the low temperature side displacer 4b2. The volume of the second expansion space 26 changes as the low-temperature side displacer 4b2 reciprocates. A second cooling stage C2 that is thermally connected to the object to be cooled is disposed at a position corresponding to the second expansion space 26 on the outer periphery of the low temperature side cylinder 4a2. The second cooling stage C2 is cooled by cold generated when the refrigerant gas expands in the second expansion space 26. A seal 5b is mounted between a portion from the high temperature end of the low temperature side displacer 4b2 and the low temperature side cylinder 4a2.

  For the high temperature side displacer 4b1, for example, phenol with cloth is used from the viewpoint of specific gravity, strength, thermal conductivity, and the like. The first regenerator material E1 is made of, for example, a wire mesh. The low-temperature side displacer 4b2 is configured by sandwiching a spherical second regenerator material E2 such as lead or bismuth in the axial direction with a felt and a wire mesh.

  FIG. 2 is a schematic diagram for explaining a connecting portion between the high temperature side displacer 4b1 and the low temperature side displacer 4b2 in the two-stage GM refrigerator 11 according to the embodiment.

  As shown in FIG. 2, the cylindrical recessed part 9 is provided in the low temperature end of the high temperature side displacer 4b1 which concerns on embodiment. A pin hole 7a 'penetrating the high temperature side displacer 4b1 and the cylindrical recess 9 is further provided at the low temperature end of the high temperature side displacer 4b1.

  The high temperature end of the low temperature side displacer 4b2 can be inserted into the cylindrical recess 9 provided in the high temperature side displacer 4b1. A pin hole 7b 'is provided at the high temperature end of the low temperature side displacer 4b2. In addition, the low temperature side displacer 4b2 is formed in the cylindrical recessed part 9 so that a certain amount of clearance may be left. As a result, the low temperature side displacer 4b2 can move by the amount of the gap while being inserted into the cylindrical recess 9 of the high temperature side displacer 4b1. In the assembly process of the GM refrigerator 10, when the high-temperature displacer 4b1 and the low-temperature displacer 4b2 are connected and inserted into the two-stage cylinder 4, it is easy to adjust the positions of the high-temperature displacer 4b1 and the low-temperature displacer 4b2. It becomes.

  The high temperature end of the low temperature side displacer 4b2 is inserted into the cylindrical recess 9 of the high temperature side displacer 4b1, and the connection pin 7a is inserted into the pin hole 7a 'and the pin hole 7b'. Thereby, the low temperature side displacer 4b2 is connected in the cylindrical recessed part 9 of the high temperature side displacer 4b1. Since the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are connected by the connection pin 7a, the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are rotatably connected with the connection pin 7a as a rotation axis. Further, the positions of the high temperature side displacer 4b1 and the low temperature side displacer 4b2 can be adjusted in the extending direction of the connection pin 7a. Thereby, in the assembly process of the GM refrigerator 10, when the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are connected and inserted into the two-stage cylinder 4, the shaft of the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are connected. The shaft can be easily adjusted.

  Here, when the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are connected by the connection pin 7a, the pin hole 7a 'and the pin hole 7b' constitute one pin hole into which the connection pin 7a is inserted. Accordingly, hereinafter, the pin hole 7a 'and the pin hole 7b' may be simply referred to as a pin hole 7 '.

  As an example of means for connecting the high temperature side displacer 4b1 and the low temperature side displacer 4b2, there is a mode in which, for example, a connecting member is inserted between the high temperature side displacer 4b1 and the low temperature side displacer 4b2. Hereinafter, a connection method via a connecting rod will be described as a comparative example of the connecting portion between the high temperature side displacer 4b1 and the low temperature side displacer 4b2 according to the embodiment.

  FIG. 3 is a schematic diagram for explaining a comparative example of the connecting portion between the high temperature side displacer 4b1 and the low temperature side displacer 4b2. As shown in FIG. 3, a cylindrical recess 8 composed of two cylindrical recesses having different diameters is provided at the center of the tip at the low temperature end of the high temperature side displacer 4 b 1 according to the comparative example. Further, a pin hole 7a 'penetrating the small diameter portion of the high temperature side displacer 4b1 and the cylindrical recess 8 is provided at the low temperature end of the high temperature side displacer 4b1.

  The connecting rod 6 can be inserted into a small diameter portion of the cylindrical recess 8 provided in the high temperature side displacer 4b1. One end of the connecting rod 6 is provided with a pin hole 6a communicating with a pin hole 7a 'provided in the high temperature side displacer 4b1.

  A pin hole 7b 'is provided at the high temperature end of the low temperature side displacer 4b2. At the other end of the connecting rod 6, a pin hole 6b communicating with the pin hole 7b 'provided at the high temperature end of the low temperature side displacer 4b2 is provided in a direction perpendicular to the pin hole 6a. The connecting rod 6 is formed so as to leave a certain gap in the cylindrical recess 8.

  One end of the connecting rod 6 is inserted into the small diameter portion of the cylindrical recess 8 of the high temperature side displacer 4b1, and the connection pin 7a is inserted into the pin hole 7a 'and the pin hole 6a. Thereby, the connecting rod 6 is connected in the small diameter part of the cylindrical recessed part 8 of the high temperature side displacer 4b1. Next, the high temperature end of the low temperature side displacer 4b2 is inserted into the large diameter portion of the cylindrical recess 8 of the high temperature side displacer 4b1. In addition, the other end of the connecting rod 6 is inserted into the high temperature end of the low temperature side displacer 4b2, and the connection pin 7b is inserted into the pin hole 7b 'and the pin hole 6b. Thereby, the connecting rod 6 is connected to the low temperature side displacer 4b1. As a result, the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are connected so as to be bent in the front-rear and left-right directions.

  FIGS. 4A and 4B are schematic diagrams for explaining the difference between the GM refrigerator 10 employing the connecting portion according to the comparative example and the GM refrigerator 11 according to the embodiment. More specifically, Fig.4 (a) is a figure which shows schematic structure of the GM refrigerator 10 which employ | adopted the connection part which concerns on a comparative example, FIG.4 (b) is the GM refrigerator 11 which concerns on embodiment. It is a figure which shows schematic structure of these.

  As shown in FIG. 4A, in the GM refrigerator 10 that employs the connecting portion according to the comparative example, the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are connected via a connecting rod 6. On the other hand, as shown in FIG. 4B, the GM refrigerator 11 according to the embodiment does not have the connecting rod 6. Therefore, in the GM refrigerator 11 according to the embodiment, the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are connected by one connection pin 7a. As a result, since the GM refrigerator 11 according to the embodiment does not require the connecting rod 6, the GM refrigerator 10 that employs the connecting portion according to the comparative example without reducing the refrigeration capacity and the manufacturing efficiency of the refrigerator, Compared to the length of the connecting rod 6, the total length is shortened.

  FIG. 5 is a diagram for explaining a difference in total length between the GM refrigerator that employs the connecting portion according to the comparative example and the GM refrigerator according to the embodiment. As shown in FIG. 4, the overall length of the GM refrigerator 11 according to the embodiment is shorter than that of the GM refrigerator 10 that employs the connecting portion according to the comparative example. In FIG. 5, the difference between the total length of the GM refrigerator 10 and the total length of the GM refrigerator 11 is indicated by L.

  Although it does not limit, as an example, the total length of the GM refrigerator 10 which employ | adopted the connection part which concerns on a comparative example is about 440 millimeters. On the other hand, the total length of the GM refrigerator 11 according to the embodiment is about 420 millimeters. For this reason, the overall length of the GM refrigerator 11 according to the embodiment is about 5% shorter than that of the GM refrigerator 10 employing the connecting portion according to the comparative example. Thereby, the freedom degree of incorporation when, for example, incorporating the GM refrigerator 11 into a device using superconductivity or the like can be increased.

  In the GM refrigerator 11 according to the embodiment, the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are connected by a single connection pin 7a. For this reason, compared with the GM refrigerator 10 which employ | adopted the connection part which concerns on a comparative example, the freedom degree of position adjustment with the high temperature side displacer 4b1 at the time of the assembly operation of the GM refrigerator 10 decreases.

  As described above, in the two-stage cylinder 4, the high temperature side cylinder 4a1 and the low temperature side cylinder 4a2 are integrally formed. In the assembly process of the GM refrigerator 10, the high temperature side displacer 4 b 1 and the low temperature side displacer 4 b 2 connected by the connection pin 7 a are inserted into the two-stage cylinder 4. At this time, if the axis of the high temperature side cylinder 4a1 and the axis of the low temperature side cylinder 4a2 are displaced due to problems such as processing accuracy, it is difficult to insert the high temperature side displacer 4b1 and the low temperature side displacer 4b2 into the two-stage cylinder 4. Become.

  In the connecting portion according to the comparative example, the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are connected by the two connection pins 7a and the connection pins 7b, so that the position adjustment between the high temperature side displacer 4b1 and the low temperature side displacer 4b2 is performed. Easy. However, in the connection using the connection pin 7a, the position adjustment in the axial direction of the connection pin 7a is easy, but the position adjustment in the direction perpendicular to the axial direction of the connection pin 7a is difficult.

  Therefore, the GM refrigerator 11 according to the embodiment is provided with a clearance between the connection pin 7a and the pin hole 7a ′ so that the position can be adjusted with respect to a direction perpendicular to the axial direction of the connection pin 7a. . Hereinafter, the clearance between the connection pin 7a and the pin hole 7a 'will be described.

  FIG. 6 is a schematic diagram for explaining the clearance between the connection pin 7a and the pin hole 7 'according to the embodiment. More specifically, FIG. 6 is a schematic diagram showing a cross-sectional view of the GM refrigerator 11 in a direction perpendicular to the axial direction of the connection pin 7a with the connection pin 7a inserted into the pin hole 7 '.

  Here, let the axial direction of the low temperature side displacer 4b2 be a 1st axial direction (Z-axis direction in FIG. 6). Further, the axial direction of the pin hole 7 ′ is defined as a second axial direction, and the direction perpendicular to the first axis and the second axis is defined as a third axial direction (Y-axis direction in FIG. 6). Although not shown in FIG. 6, the second axis direction corresponds to the X-axis direction in the three-dimensional orthogonal coordinate system.

  In the GM refrigerator 11 according to the embodiment, the pin hole 7 'is an insertion hole larger than the connection pin 7a. As a result, a gap (clearance) is formed between the connection pin 7a and the pin hole 7 ', and the position of the high temperature side displacer 4b1 and the low temperature side displacer 4b2 in the Y direction can be adjusted.

  As shown in FIG. 6, the clearance in the Z-axis (first axis) direction between the pin hole 7 'and the connection pin 7a is defined as h. The clearance in the Y-axis (third axis) direction between the pin hole 7 'and the connection pin 7a is w. Further, the clearance in the Z-axis direction between the low temperature end of the low temperature side displacer 4b2 and the low temperature side cylinder 4a2 is α, and the clearance in the Y axis direction between the low temperature side cylinder 4a2 and the low temperature side displacer 4b2 is β.

In the GM refrigerator 11 according to the embodiment, the clearance w in the Y-axis direction between the pin hole 7 ′ and the connection pin 7a is the clearance β in the Y-axis direction between the low temperature side cylinder 4a2 and the low temperature side displacer 4b2. It is comprised so that it may become larger. That is, the inner diameter of the pin hole 7 ′ and the thickness of the shaft of the connection pin 7a are set so that the following expression (1) is established.
β <w (1)

  The size of the clearance w in the Y-axis direction between the pin hole 7 ′ and the connection pin 7 a is determined in the Y-axis direction when the low-temperature displacer 4 b 2 is inserted into the low-temperature cylinder 4 a 2 in the assembly process of the GM refrigerator 11. Specifies the amount of adjustment. In the GM refrigerator 11 according to the embodiment, the adjustment amount is larger than the clearance β in the Y-axis direction between the low temperature side cylinder 4a2 and the low temperature side displacer 4b2. Thus, even if the axis of the high temperature side cylinder 4a1 and the axis of the low temperature side cylinder 4a2 are misaligned, the axis of the low temperature side cylinder 4a2 and the axis of the low temperature side displacer 4b2 can be adjusted. Since the low temperature side displacer 4b2 can be prevented from contacting the low temperature side cylinder 4a2 during the operation of the GM refrigerator 11, the reliability of the GM refrigerator 11 can be improved. Moreover, in the assembly process of the GM refrigerator 11, the position adjustment when inserting the low temperature side displacer 4b2 in the low temperature side cylinder 4a2 can also be performed, and the assembly of the GM refrigerator 11 becomes easy.

In the GM refrigerator 11 according to the embodiment, twice the clearance h in the Z-axis direction between the pin hole 7 ′ and the connection pin 7a is between the low temperature end of the low temperature side displacer 4b2 and the bottom of the low temperature side cylinder 4a2. It is comprised so that it may become narrower than clearance (alpha) between. That is, the inner diameter of the pin hole 7 ′ and the thickness of the shaft of the connection pin 7a are set so that the following expression (2) is established.
2h <α (2)

  Here, the clearance α between the low temperature end of the low temperature side displacer 4b2 and the bottom of the low temperature side cylinder 4a2 is the low temperature end of the low temperature side displacer 4b2 and the low temperature side cylinder 4a2 when the low temperature side displacer 4b2 is at the bottom dead center. The distance between the bottom of That is, this is the distance between the low-temperature end of the low-temperature side displacer 4b2 when the low-temperature end is closest to the bottom of the low-temperature side cylinder 4a2.

  The size of the clearance α defines the amount of adjustment in the Z-axis direction of the low temperature side displacer 4b2. That is, the low temperature side displacer 4b2 may be shifted by a distance of 2h in the Z-axis direction in the assembly process of the GM refrigerator 11. Since the GM refrigerator 11 is configured to satisfy the above formula (2), the distance α when the low temperature end of the low temperature side displacer 4b2 is closest to the bottom of the low temperature side cylinder 4a2 is Z in the low temperature side displacer 4b2. It becomes larger than the maximum value 2h of the deviation amount in the axial direction. Therefore, the low temperature end of the low temperature side displacer 4b2 is prevented from contacting the bottom of the low temperature side cylinder 4a2, and the reliability of the GM refrigerator 11 can be improved.

  The clearance α may be determined by experiments in consideration of the size of the GM refrigerator 11, required reliability, refrigeration performance, and the like, but is about several millimeters as an example. Further, the clearance h in the Z-axis direction between the pin hole 7 'and the connection pin 7a is less than 1 millimeter, preferably 0.1 millimeter or less.

  FIGS. 7A to 7D are views showing various modes of combinations of the shape of the pin hole 7 ′ and the cross-sectional shape of the connection pin 7 a.

FIG. 7A is a diagram showing a combination of the shape of the pin hole 7 ′ and the cross-sectional shape of the connection pin 7a when the connection pin 7a is a cylinder and the pin hole 7 ′ is a cylindrical space. is there. In this case, 'and Y-axis Direction clearance w between the connection pin 7a and a pin hole 7' the pin holes 7 as described above and Z-axis direction of the clearance h between the connection pins 7a and has a same length Become. More specifically, the clearance w and the clearance h are equal to t which is the difference between the radius of the cross section of the pin hole 7 ′ and the radius of the cross section of the connection pin 7a. That is, the following formula (3) is established.
w = h = t (3)

From the equations (1), (2), and (3), the following equation (4) is obtained.
β <t <α / 2 (4)

  In a general pin hinge, the connection pin 7a is often a cylinder, and the pin hole 7 'is often a cylindrical space. Therefore, when the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are connected by a general pin hinge, the above equation (4) is an equation that the GM refrigerator 11 should satisfy in order to improve the reliability of the GM refrigerator 11. It can also be said.

  By the way, when the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are connected using the connection pin 7a and the pin hole 7 'having the shape shown in FIG. 7A, the high temperature side displacer 4b1 and the low temperature are arranged with the connection pin 7a as the rotation axis. The side displacer 4b2 can rotate. However, in the assembly process of the GM refrigerator 11, the above-described clearance w and clearance h are meaningful, but the rotational motion of the high temperature side displacer 4b1 and the low temperature side displacer 4b2 is not necessarily required. Rather, it is convenient in the assembly process of the GM refrigerator 11 not to perform unnecessary rotation.

  FIG. 7B is a diagram showing a combination of the shape of the pin hole 7 ′ and the cross-sectional shape of the connection pin 7 a for restricting the rotation of the high temperature side displacer 4 b 1 and the low temperature side displacer 4 b 2. In the example shown in FIG. 7B, the connection pin 7a has a shape in which a part of a cylinder is cut out along a plane parallel to the long axis. For this reason, the cross section of the connection pin 7a shown in FIG. 7B has an arcuate shape. The pin hole 7 ′ has a shape in which the cross section of the connection pin 7 a is enlarged similarly.

  When the connection pin 7 a is inserted into the pin hole 7 ′ shown in FIG. 7B, at least a part of the wall surface of the pin hole 7 ′ and the surface of the connection pin 7 can be brought into surface contact. Thereby, it can control that high temperature side displacer 4b1 and low temperature side displacer 4b2 rotate.

  In the example shown in FIGS. 7A and 7B, the shape of the pin hole 7 'and the cross-sectional shape of the connection pin 7a are a circle or a shape based on a circle. However, the shape of the pin hole 7 ′ and the cross-sectional shape of the connection pin 7 a may not be circular, and may be, for example, a rectangle or an ellipse.

  FIG. 7C is a diagram illustrating a case where the shape of the pin hole 7 ′ and the cross-sectional shape of the connection pin 7 a are rectangular. In the example shown in FIG. 7C, as in the example shown in FIG. 7B, when the connecting pin 7a is inserted into the pin hole 7 ′, at least a part of the wall surface of the pin hole 7 ′ and the surface of the connecting pin 7a. Makes surface contact. Thereby, it can control that high temperature side displacer 4b1 and low temperature side displacer 4b2 rotate.

In the example shown in FIG. 7C, the clearance w in the Y-axis direction between the pin hole 7 ′ and the connection pin 7a is larger than the clearance h in the Z-axis direction between the pin hole 7 ′ and the connection pin 7a. Is also wide. That is, the following formula (5) is established.
h <w (5)

  As described above, the size of the clearance w defines the amount of adjustment in the Y-axis direction when the low temperature side displacer 4b2 is inserted into the low temperature side cylinder 4a2 in the assembly process of the GM refrigerator 11. Although the clearance h is less than 1 millimeter, the clearance w is preferably about several millimeters in order to increase the degree of freedom of adjustment in the assembly process. By making the shape of the pin hole 7 ′ and the cross-sectional shape of the connection pin 7 a rectangular, it is possible to provide a clearance w wider than the clearance h.

  FIG. 7D is a diagram illustrating a case where the shape of the pin hole 7 ′ and the cross-sectional shape of the connection pin 7 a are rectangular. In the example shown in FIG. 7D, the eccentricity is different between the ellipse that is the shape of the pin hole 7 'and the ellipse that is the cross-sectional shape of the connection pin 7a. More specifically, the eccentricity of the shape of the pin hole 7 'is larger than the eccentricity of the cross-sectional shape of the connection pin 7a. For this reason, the cross-sectional shape of the connection pin 7a is flatter than the cross-sectional shape of the connection pin 7a. As a result, the clearance w becomes wider than the clearance h, and the degree of freedom of adjustment in the assembly process of the GM refrigerator 11 can be improved.

  Further, since the cross-sectional shape of the connection pin 7a is flatter than the cross-sectional shape of the connection pin 7a, the rotation of the high-temperature side displacer 4b1 and the low-temperature side displacer 4b2 around the connection pin 7a can also be restricted.

  In the above description, the two-stage GM refrigerator is described as the GM refrigerator 11 according to the embodiment. However, those skilled in the art can understand that the present invention is useful for GM refrigerators having two or more stages.

  As explained above, according to the GM refrigerator 11 which concerns on embodiment, the full length of a multistage cryogenic refrigerator can be shortened.

  Further, in the GM refrigerator 11 according to the embodiment, a clearance is provided between the connection pin 7a for connecting the high temperature side displacer 4b1 and the low temperature side displacer 4b2 and the pin hole 7 'for inserting the connection pin 7a. Yes. Therefore, in the GM refrigerator 11 according to the embodiment, the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are coupled to be movable in the front-rear and left-right directions (X-axis direction and Y-axis direction). Therefore, it is easy to perform the insertion work into the two-stage cylinder 4 in a state where the high temperature side displacer 4b1 and the low temperature side displacer 4b2 are connected by the connection pin 7a. For this reason, it is not necessary to precisely process the cylinder and the displacer, so that the manufacturing cost can be reduced.

  Further, the low temperature side displacer 4b2 inserted into the two-stage cylinder 4 by a clearance between the connection pin 7a for connecting the high temperature side displacer 4b1 and the low temperature side displacer 4b2 and the pin hole 7 'for inserting the connection pin 7a. However, contact with the wall surface or bottom of the two-stage cylinder 4 is suppressed. Thereby, the reliability of the GM refrigerator 11 can be improved.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions are made to the above-described embodiments without departing from the scope of the present invention. be able to. For example, in the embodiment, the example in which the regenerator type refrigerator is a displacer type GM refrigerator has been described. However, the present invention is not limited to this, and the present invention can also be applied to a Stirling refrigerator, a Solvay refrigerator, and the like.

  DESCRIPTION OF SYMBOLS 1 Drive part, C1 1st cooling stage, E1 1st cool storage material, 2 Compressor, C2 2nd cooling stage, E2 2nd cool storage material, 3 Gas pipe line, 4 Two-stage cylinder, 4a1 High temperature side cylinder, 4a2 Low temperature Side cylinder, 4b1 high temperature side displacer, 4b2 low temperature side displacer, 5a, 5b seal, 6 connecting rod, 7 'pin hole, 7a connecting pin, 7', 7a 'pin hole, 9 cylindrical recess, 11 GM refrigerator, 12 chambers Greenhouse, 18 first expansion space, 26 second expansion space.

Claims (6)

Connection pins,
A low-temperature side displacer having a first pin hole for inserting the connection pin;
A second pin hole for inserting the connection pin, and a high temperature side displacer connected to the low temperature displacer with the connection pin;
A cylinder for accommodating the low temperature side displacer and the high temperature side displacer;
The axial direction of the low temperature displacer is the first axial direction, the axial direction of the first pin hole is the second axial direction, and the direction perpendicular to the first and second axes is the third axial direction, and the first pin The clearance in the third axial direction between the hole and the connecting pin is w, and the clearance in the third axial direction between the cylinder and the low temperature displacer is β, where the clearance w is the third axial direction in the third axial direction. When the difference between the pin hole diameter and the connection pin diameter is half, and the clearance β is half the difference between the cylinder diameter and the low temperature side displacer diameter in the third axis direction,
β <w
Is established ,
A clearance w in the third axial direction between the first pin hole and the connection pin is wider than a clearance h in the first axial direction between the first pin hole and the connection pin. cryogenic refrigerator according to claim half der Rukoto of the difference between the connection pin diameter as the first pin hole diameter in the axial direction.   The first axial clearance h between the first pin hole and the connection pin is less than 1 millimeter, and the clearance h is half the difference between the first pin hole diameter and the connection pin diameter in the first axial direction. The cryogenic refrigerator according to claim 1, wherein:   Twice the first axial clearance h between the first pin hole and the connecting pin is narrower than the clearance α between the low temperature end of the low temperature displacer and the bottom of the cylinder, and the clearance h is The cryogenic refrigerator according to claim 1 or 2, wherein the cryogenic refrigerator is half the difference between the first pin hole diameter and the connection pin diameter in the first axial direction. The connection pin is a cylinder, and the first pin hole is a cylindrical space,
The clearance between the cold end of the cold side displacer and the bottom of the cylinder is α,
When the difference between the radius of the cross section of the first pin hole and the radius of the cross section of the connection pin is t,
β <t <α / 2
The cryogenic refrigerator according to any one of claims 1 to 3 , wherein: Connection pins,
A low-temperature side displacer having a first pin hole for inserting the connection pin;
A second pin hole for inserting the connection pin, and a high temperature side displacer connected to the low temperature displacer with the connection pin;
A cylinder for accommodating the low temperature side displacer and the high temperature side displacer;
The axial direction of the low temperature displacer is the first axial direction, the axial direction of the first pin hole is the second axial direction, and the direction perpendicular to the first and second axes is the third axial direction, and the first pin The clearance in the third axial direction between the hole and the connecting pin is w, and the clearance in the third axial direction between the cylinder and the low temperature displacer is β, where the clearance w is the third axial direction in the third axial direction. When the difference between the pin hole diameter and the connection pin diameter is half, and the clearance β is half the difference between the cylinder diameter and the low temperature side displacer diameter in the third axis direction,
β <w
Is established,
The first when inserting the connection pin into the pin hole, cryogenic refrigerator you characterized in that at least a portion of the first pin hole in the wall and the connecting pin surface is in surface contact. The position of the low temperature side displacer and the high temperature side displacer in the third axis direction can be adjusted by the third axial clearance w between the first pin hole and the connection pin. The cryogenic refrigerator according to any one of claims 1 to 5 .

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