JP2015117872A - Cryogenic refrigerating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for reducing an influence of an external magnetic field on a motor that a cryogenic refrigerating machine includes.SOLUTION: In a cryogenic refrigerating machine suitable for cooling a superconducting coil, a drive rotary shaft 31a is connected to a motor 31. A Scotch-yoke mechanism 32 converts rotation of the drive rotary shaft 31a into reciprocal motion. The drive rotary shaft 31a is supported rotatably at a plurality of places in its longer direction, and the places include one end part of the drive rotary shaft 31 connected to the motor 31 and the other end part of the drive rotary shaft 31a connected to the Scotch-yoke mechanism 32. Further, a motor housing part 5 which houses the motor 31 and a housing 3 which houses a rotary valve 40 and the Scotch-yoke mechanism 32 are separated from each other, and both are constituted separately so as to reduce an influence of an external magnetic field that the superconducting coil generates on the motor 31.

Description

  The present invention relates to a regenerator refrigerator that stores cold energy generated by expanding refrigerant gas in a regenerator material, and more particularly to a cryogenic refrigerator that is suitable for cooling a superconducting coil.

  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 expands 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.

JP 2013-2687 A

  Generally, a motor is used as power for reciprocating movement of a displacer in the GM refrigerator. Further, the GM refrigerator is used by being incorporated in a device utilizing superconductivity, for example, and may be used for cooling the superconducting coil.

  When a GM refrigerator is used to cool a superconducting coil, if a magnet motor is used as the motor for the reciprocating movement of the displacer, the motor torque decreases due to the magnetic field generated by the superconducting coil that is the cooling target. There is a case. As a result, the operation of the GM refrigerator may be hindered.

  This invention is made | formed in view of such a subject, The objective is to provide the technique which reduces the influence of the external magnetic field which the motor with which a low-temperature refrigerator is equipped receives.

  In order to solve the above problems, a cryogenic refrigerator according to an aspect of the present invention includes a motor, a drive rotary shaft connected to the motor, a Scotch yoke mechanism that converts the rotation of the drive rotary shaft into a reciprocating motion, Is provided. The drive rotary shaft is rotatably supported at a plurality of locations in the longitudinal direction, and the plurality of locations are one end of the drive rotary shaft connected to the motor and the drive rotary shaft connected to the Scotch yoke mechanism. And the other end.

  ADVANTAGE OF THE INVENTION According to this invention, the technique which reduces the influence of the external magnetic field which the motor with which a cryogenic refrigerator is equipped receives can be provided.

It is sectional drawing of the GM refrigerator which is one embodiment of this invention. It is a disassembled perspective view which expands and shows a scotch yoke mechanism. It is a disassembled perspective view which expands and shows a rotary valve. FIGS. 4A to 4B are diagrams illustrating an arrangement when cooling a superconducting coil to be cooled using the GM refrigerator according to the embodiment. It is sectional drawing of the GM refrigerator which concerns on the modification of this invention.

  Embodiments of the present invention will be described with reference to the drawings.

  First, the overall configuration of the cryogenic refrigerator of the embodiment will be described. FIG. 1 to FIG. 3 are diagrams for explaining a cryogenic refrigerator that is an embodiment of the present invention. In the present embodiment, a Gifford McMahon refrigerator (hereinafter referred to as GM refrigerator 10) will be described as an example of the cryogenic refrigerator. A GM refrigerator 10 according to the present embodiment includes a compressor 1, a cylinder 2, a housing 3, a motor housing portion 5, and the like.

  The compressor 1 collects low-pressure refrigerant gas from the intake side to which the low-pressure pipe 1a is connected, compresses this, and then supplies the high-pressure refrigerant gas to the high-pressure pipe 1b connected to the discharge side. As the refrigerant gas, helium gas can be used, but is not limited thereto.

  In the present embodiment, a two-stage GM refrigerator 10 will be described as an example. In the two-stage GM refrigerator 10, the cylinder 2 has two cylinders, a first-stage cylinder 11 and a second-stage cylinder 12. A first stage displacer 13 is inserted into the first stage cylinder 11. A second stage displacer 14 is inserted into the second stage cylinder 12.

  The first stage displacer 13 and the second stage displacer 14 are connected to each other, and are configured to reciprocate in the cylinder axial direction inside the cylinders 11 and 12, respectively. Internal spaces 15 and 16 are formed inside the displacers 13 and 14, respectively. The internal spaces 15 and 16 are filled with a regenerator material, and function as regenerators 17 and 18.

  The first stage displacer 13 located at the upper part is connected to a drive shaft 36 that extends upward (in the Z1 direction). The drive shaft 36 constitutes a part of a scotch yoke mechanism 32 described later.

  Further, a gas flow path L1 is formed on the high temperature end side (Z1 direction side end portion) of the first stage displacer 13. Further, on the low temperature end side (Z2 direction side end portion) of the first stage displacer 13, a gas flow path L <b> 2 that connects the internal space 15 and the first stage expansion space 21 is formed.

  A first stage expansion space 21 is formed at the low temperature side end of the first stage cylinder 11 (the end on the direction indicated by the arrow Z2 in FIG. 1). Further, an upper chamber 23 is formed at the high temperature side end of the first stage cylinder 11 (the end on the direction side indicated by the arrow Z1 in FIG. 1).

  Further, a second stage expansion chamber 22 is formed at the low temperature side end (the end on the direction indicated by the arrow Z2 in FIG. 1) in the second stage cylinder 12.

  The second stage displacer 14 is attached to the lower part of the first stage displacer 13 by a coupling mechanism (not shown). A gas flow path L3 that connects the first-stage expansion space 21 and the internal space 16 is formed at the high-temperature side end of the second-stage displacer 14 (the end on the direction indicated by the arrow Z1 in FIG. 1). Has been. In addition, a gas flow path L4 that communicates the internal space 16 and the second stage expansion chamber 22 is provided at the low temperature side end part (the end part in the direction indicated by the arrow Z2 in FIG. 1) of the second stage displacer 14. Is formed.

  The first stage cooling stage 19 is disposed on the outer peripheral surface of the first stage cylinder 11 at a position facing the first stage expansion space 21. The second stage cooling stage 20 is disposed on the outer peripheral surface of the second stage cylinder 12 at a position facing the second stage expansion chamber 22.

  The first stage displacer 13 and the second stage displacer 14 are moved in the first stage cylinder 11 and the second stage cylinder 12 in the vertical direction (arrows Z1 and Z2 directions) in the figure by the scotch yoke mechanism 32. To do.

  As shown in FIG. 1, the housing 3 has a rotary valve 40 and the like, and the motor accommodating portion 5 accommodates the motor 31.

  The motor 31, the drive rotation shaft 31 a, and the scotch yoke mechanism 32 constitute a drive device 30. The motor 31 generates a rotational driving force, and a rotating shaft connected to the motor 31 (hereinafter referred to as “driving rotating shaft 31 a”) transmits the rotational motion of the motor 31 to the scotch yoke mechanism 32. The motor 31 corresponds to the rotation drive unit in the present invention.

  FIG. 2 shows the Scotch yoke mechanism 32 in an enlarged manner. The scotch yoke mechanism 32 includes a crank 33, a scotch yoke 34, and the like. The scotch yoke mechanism 32 can be driven by driving means such as a motor 31.

  The crank 33 is fixed to the drive rotating shaft 31a. The crank 33 is configured such that a crank pin 33b is provided at a position eccentric from the mounting position of the drive rotating shaft 31a. Therefore, when the crank 33 is attached to the drive rotation shaft 31a, the crank pin 33b is eccentric with respect to the drive rotation shaft 31a. In this sense, the crank pin 33b functions as an eccentric rotating body. The drive rotating shaft 31a is rotatably supported at a plurality of locations in the longitudinal direction. More specifically, it is supported by the first drive rotary bearing 60a, the second drive rotary bearing 60b, and the third drive rotary bearing 60c. The first drive rotary bearing 60 a is provided at the end of the motor 31 opposite to the Scotch yoke mechanism 32. The second drive rotary bearing 60b supports the drive rotary shaft 31a at the output side end of the motor. The third drive rotary bearing 60c supports the drive rotary shaft 31a at the end connected to the scotch yoke mechanism.

  The scotch yoke 34 includes a drive shaft 36a, a drive shaft 36b, a yoke plate 35, a roller bearing 37, and the like. A housing space is formed in the housing 3. This accommodation space is an airtight container having airtightness for accommodating the scotch yoke 34 and a rotor valve 42 of the rotary valve 40 described later. Therefore, hereinafter, the accommodation space in the housing 3 is referred to as an “airtight container 4” in the present specification. The airtight container 4 communicates with the intake port of the compressor 1 through the low pressure pipe 1a. Therefore, the airtight container 4 is always maintained at a low pressure.

  The drive shaft 36a extends upward (Z1 direction) from the yoke plate 35. The drive shaft 36 a is supported by a sliding bearing 38 a provided in the housing 3. Therefore, the drive shaft 36a is configured to be movable in the vertical direction in the figure (the directions of arrows Z1 and Z2 in the figure).

  The drive shaft 36b extends downward (Z2 direction) from the yoke plate 35. The drive shaft 36 b is supported by a sliding bearing 38 b provided in the housing 3. Therefore, the drive shaft 36 is also configured to be movable in the vertical direction in the figure (the directions of arrows Z1 and Z2 in the figure).

  The drive shaft 36a and the drive shaft 36b are supported by the slide bearing 38a and the slide bearing 38b, respectively, so that the scotch yoke 34 can move in the vertical direction (the directions of arrows Z1 and Z2 in the figure) within the housing 3. It has become.

  In the present embodiment, the term “axial direction” is sometimes used to express the positional relationship of the components of the cryogenic refrigerator in an easily understandable manner. The axial direction represents the direction in which the drive shaft 36a and the drive shaft 36b extend, and also coincides with the direction in which the displacers 13 and 14 move. For the sake of convenience, the relative proximity to the expansion space or the cooling stage in the axial direction may be referred to as “lower” and the relative distance from the expansion space or the cooling stage may be referred to as “upper”. That is, it is sometimes called “upper” when it is relatively far from the end on the low temperature side and “lower” when it is relatively close. Such expressions are not related to the arrangement when the GM refrigerator 10 is attached. For example, the GM refrigerator 10 may be attached with the expansion space facing upward in the vertical direction.

  The yoke plate 35 has a horizontally long window 35a. The horizontally long window 35a extends in a direction intersecting with the extending direction of the drive shaft 36a and the drive shaft 36b, for example, a direction orthogonal to each other (directions of arrows X1 and X2 in FIG. 2).

  The roller bearing 37 is disposed in the horizontally long window 35a. The roller bearing 37 is configured to be able to roll within the horizontally long window 35a. A hole 37 a that engages with the crank pin 33 b is formed at the center position of the roller bearing 37. The laterally long window 35a allows lateral movement of the crank pin 33b and the roller bearing 37. The horizontally long window 35a includes an upper frame portion and a lower frame portion extending in the horizontal direction, and extending in the axial direction or the vertical direction at the horizontal ends of the upper frame portion and the lower frame portion, and the upper frame portion and the lower frame. A first side frame part and a second side frame part that join the parts.

  When the motor 31 is driven and the drive rotary shaft 31a rotates, the crank pin 33b rotates to draw an arc. As a result, the scotch yoke 34 reciprocates in the directions of arrows Z1 and Z2 in the figure. At this time, the roller bearing 37 reciprocates in the horizontal window 35a in the directions indicated by arrows X1 and X2.

  The first stage displacer 13 is connected to a drive shaft 36 b disposed below the scotch yoke 34. Therefore, when the Scotch yoke 34 reciprocates in the directions of arrows Z1 and Z2 in the drawing, the first stage displacer 13 and the second stage displacer 14 connected thereto are also the first stage cylinder 11 and the second stage. The cylinder 12 reciprocates in the directions of arrows Z1 and Z2.

  Next, the valve mechanism will be described. In the present embodiment, the rotary valve 40 is used as the valve mechanism.

  The rotary valve 40 switches the flow path of the refrigerant gas. The rotary valve 40 functions as a supply valve that guides the high-pressure refrigerant gas discharged from the discharge side of the compressor 1 to the upper chamber 23 of the first stage displacer 13 and also supplies the refrigerant gas from the upper chamber 23 to the compressor. 1 functions as an exhaust valve leading to the intake side.

  The rotary valve 40 has a stator valve 41 and a rotor valve 42 as shown in FIG. 3 in addition to FIG. The stator valve 41 has a flat stator side sliding surface 45, and the rotor valve 42 has a flat rotor side sliding surface 50. The stator-side sliding surface 45 and the rotor-side sliding surface 50 are in surface contact with each other, thereby preventing refrigerant gas from leaking.

  The stator valve 41 is fixed in the housing 3 with a fixing pin 43. By fixing with the fixing pin 43, the rotation of the stator valve 41 is restricted.

  The rotor valve 42 is rotatably supported by a rotor valve bearing 62. An engagement hole (not shown) that engages with the crank pin 33b is formed in the opposite end surface 52 that is located on the opposite side of the rotor-side sliding surface 50 of the rotor valve 42. When the crank pin 33b is inserted into the roller bearing 37, the tip of the crank pin 33b projects from the roller bearing 37 in the direction of the arrow Y1 (see FIG. 1).

  The tip of the crank pin 33 b protruding from the roller bearing 37 is engaged with an engagement hole formed in the rotor valve 42. Therefore, when the crank pin 33b rotates (eccentric rotation), the rotor valve 42 rotates in synchronization with the scotch yoke mechanism 32.

  The stator valve 41 has a refrigerant gas supply hole 44, an arc-shaped groove 46, and a gas flow path 49. The refrigerant gas supply hole 44 is connected to the high-pressure pipe 1 b of the compressor 1 and is formed so as to penetrate the central portion of the stator valve 41.

  The arc-shaped groove 46 is formed in the stator side sliding surface 45. The arc-shaped groove 46 has an arc shape centered on the refrigerant gas supply hole 44.

  The gas flow path 49 is formed across the stator valve 41 and the housing 3. One end of the gas flow path 49 on the valve side opens into the arc-shaped groove 46 to form an opening 48. Further, in the gas flow path 49, a discharge port 47 is opened on the side surface of the stator valve 41. The discharge port 47 communicates with the gas flow path 49 in the housing. The other end of the gas flow path 49 in the housing is connected to the expansion space 21 via the upper chamber 23, the gas flow path L1, the regenerator 17, and the like.

  On the other hand, the rotor valve 42 has an oval groove 51 and an arc-shaped hole 53.

  The oval groove 51 is formed on the rotor side sliding surface 50 so as to extend in the radial direction from the center thereof. The arc-shaped hole 53 penetrates from the rotor-side sliding surface 50 of the rotor valve 42 to the opposite end surface 52 and is connected to the airtight container 4. The arc-shaped hole 53 is formed on the same circumference as the arc-shaped groove 46 of the stator valve 41.

  The refrigerant gas supply hole 44, the oval groove 51, the arc-shaped groove 46, and the opening 48 constitute a supply valve. The opening 48, the arc-shaped groove 46, and the arc-shaped hole 53 constitute an exhaust valve. In the present embodiment, the spaces existing inside the valve such as the oval groove 51 and the arc-shaped groove 46 may be collectively referred to as a valve internal space.

  In the GM refrigerator 10 having the above-described configuration, when the rotational driving force of the motor 31 is transmitted to the scotch yoke mechanism 32 via the drive rotating shaft 31a and the scotch yoke mechanism 32 is driven, the scotch yoke 34 is Z1, Z2 Move back and forth in the direction. By the operation of the scotch yoke 34, the first stage displacer 13 and the second stage displacer 14 move between the bottom dead center LP and the top dead center UP in the first stage cylinder 11 and the second stage cylinder 12. Move back and forth.

  When the first stage displacer 13 and the second stage displacer 14 reach the bottom dead center LP, the exhaust valve is closed and the supply valve is opened. That is, a refrigerant gas flow path is formed between the refrigerant gas supply hole 44, the oval groove 51, the arc-shaped groove 46, and the gas flow path 49.

  Therefore, the high-pressure refrigerant gas begins to be filled from the compressor 1 into the upper chamber 23. Thereafter, the first-stage displacer 13 and the second-stage displacer 14 start to rise past the bottom dead center LP, and the refrigerant gas passes from the top to the bottom of the regenerators 17 and 18 to enter the expansion spaces 21 and 22. It will be filled.

  When the first stage displacer 13 and the second stage displacer 14 reach the top dead center UP, the supply valve is closed and the exhaust valve is opened. That is, a refrigerant gas flow path is formed between the gas flow path 49, the arc-shaped groove 46, and the arc-shaped hole 53.

  As a result, the high-pressure refrigerant gas expands in the expansion spaces 21 and 22 to generate cold and cool the cooling stages 19 and 20. The low-temperature refrigerant gas that has generated cold flows from the bottom to the top while cooling the regenerator material in the regenerators 17 and 18, and then returns to the low-pressure pipe 1 a of the compressor 1.

  Thereafter, when the first stage displacer 13 and the second stage displacer 14 reach the bottom dead center LP, the exhaust valve is closed and the supply valve is opened to complete one cycle. In this way, the cooling stages 19 and 20 of the GM refrigerator 10 are cooled to an extremely low temperature by repeating the compression and expansion cycles of the refrigerant gas. The cooling stages 19 and 20 of the GM refrigerator 10 conduct the cold generated by expanding the refrigerant gas in the expansion spaces 21 and 22 to the outside of the first stage cylinder 11 and the second stage cylinder 12. .

  As described above, in the GM refrigerator 10 according to the embodiment, the driving force of the driving device such as the motor 31 is converted into the reciprocating movement of the first stage displacer 13 and the second stage displacer 14 so that Is generated. As a result, the temperature of the second cooling stage 20 becomes an extremely low temperature of about 4K.

  An example of a cooling object of the GM refrigerator 10 according to the embodiment is a superconducting coil. A superconducting coil is generally used to generate a strong magnetic field. For this reason, when the GM refrigerator 10 is used for cooling the superconducting coil, the motor 31 is also exposed to the magnetic field generated by the superconducting coil. Due to the influence of this magnetic field, the output torque of the motor 31 may decrease. As a result, if the output torque of the motor 31 falls below the torque required for reciprocating the first stage displacer 13 and the second stage displacer 14, the GM refrigerator 10 may not be able to operate normally.

  In order to reduce the influence of the motor 31 from the external magnetic field generated by the superconducting coil, a heat transfer member is attached to the second stage cooling stage 20 to extend the GM refrigerator 10, and the motor 31 and the superconducting coil are connected. The distance may be increased. However, by making the heat transfer member longer, the heat transfer distance between the second stage cooling stage 20 and the superconducting coil becomes longer, and the loss increases accordingly. For this reason, there is a limit to the method of lengthening the heat transfer member. In addition, the overall height of the GM refrigerator 10 is increased, which may hinder installation.

  In order to solve these problems, in the GM refrigerator 10 according to the embodiment, the motor housing 5 that houses the motor 31 and the housing 3 that houses the rotary valve 40 and the Scotch yoke mechanism 32 are separated, It is comprised so that both may leave | separate. Therefore, the entire length of the drive rotating shaft 31a becomes longer than in the case where the motor housing portion 5 and the housing 3 are brought close to each other and configured as a single unit.

  Since the drive rotating shaft 31a is a member that transmits the rotational motion of the motor 31 to the Scotch yoke mechanism 32, it may be housed in a container for protection. This container is adjacent to the hermetic container 4 in the housing 3. For this reason, in order to maintain the airtightness of the airtight container 4 in the housing 3, the container for accommodating the motor 31 also has airtightness. Hereinafter, in this specification, the airtight container 4 may be referred to as a “first airtight container 4”. In addition, an airtight container that accommodates the drive rotation shaft 31a is referred to as a “second airtight container 6”. In order to maintain the airtightness of the first airtight container 4, a first seal member 64 a is provided between the first airtight container 4 and the second airtight container 6. The first seal member 64a is outside the third drive rotary bearing 60c when viewed from the axial direction of the drive rotary shaft 31a (a position farther from the drive rotary shaft 31a than the third drive rotary bearing 60c in the radial direction of the drive rotary shaft 31a). And the space between the first airtight container 4 and the second airtight container 6 is sealed. That is, the first seal member 64a has a larger diameter than the third drive rotary bearing 60c.

  A second seal member 64b is provided between the second hermetic container 6 and the motor housing portion. The second seal member 64b is located outside the second drive rotary bearing 60b when viewed from the axial direction of the drive rotary shaft 31a (a position farther from the drive rotary shaft 31a than the second drive rotary bearing 60b in the radial direction of the drive rotary shaft 31a). ) And seals between the second hermetic container 6 and the motor housing 5. That is, the second seal member 64b has a larger diameter than the second drive rotary bearing 60b. The airtightness of the airtight container 4 can be reliably maintained by the first seal member 64a and the second seal member 64b.

  Compared with the case where the motor housing portion 5 and the housing 3 are arranged close to each other so as to be integrated with each other, the total length of the drive rotating shaft 31a becomes longer. Therefore, as shown in FIG. 1, the drive rotary shaft 31a is rotatably supported at a plurality of locations in the longitudinal direction by, for example, the second drive rotary bearing 60b and the third drive rotary bearing 60c. A second seal member 64b is provided between the second hermetic container 6 and the motor housing 5, so that the airtightness of the second hermetic container 6 is maintained. The second seal member 64 b seals between the two airtight container 6 and the motor housing 5. The second airtight container 6 connects the motor housing part 5 and the first airtight container 4 so as to separate the motor housing part 5 from the first airtight container 4.

  Thus, by separating the motor housing 5 and the housing 3 and separating them from each other, the distance between the motor 31 and the second cooling stage 20 is increased, and a superconducting coil is generated. It is possible to reduce the influence of the motor 31 due to the magnetic field. Further, unlike the case where the motor housing portion 5 and the housing 3 are made close to each other by separating the motor housing portion 5 and the housing 3 from each other, the motor housing portion 5 is integrated. Among the wall surfaces constituting 5, a side wall 5 a through which the drive rotation shaft 31 a passes appears.

  The motor housing portion 5 according to the embodiment has a substantially rectangular parallelepiped shape having a side wall, a top wall, and a bottom wall so as to cover the entire surface of the motor 31. And the magnetic wall surface which comprises the motor accommodating part 5 is equipped with the magnetic shielding member. In particular, since the magnetic shield member can be provided on the side wall 5a and the bottom wall 5b, which are surfaces facing the second cooling stage 20 where the superconducting coil is installed, the motor 31 is driven from the magnetic field generated by the superconducting coil. The influence received can be reduced effectively. Furthermore, by providing a magnetic shield member on the other wall surface such as the top wall, the influence of the motor 31 from the magnetic field generated by the superconducting coil can be reduced more effectively.

  FIGS. 4A and 4B are diagrams illustrating an arrangement when cooling the superconducting coil 70 to be cooled using the GM refrigerator 10 according to the embodiment. Fig.4 (a) is a figure which shows arrangement | positioning at the time of seeing from the upper direction of the GM refrigerator 10, and FIG.4 (b) shows the BB sectional drawing in Fig.4 (a).

  As shown in FIG. 4A, the superconducting coil 70 is an annular coil, and is disposed in a vacuum container (not shown). The superconducting coil 70 is provided with a cooling member 72 at one end in the axial direction of the superconducting coil 70, and is cooled by the four GM refrigerators 10.

  More specifically, a heat transfer rod 74 is connected to each second stage cooling stage 20 of the four GM refrigerators 10, and the cold generated by the GM refrigerator 10 passes through the heat transfer rods 74. It is transmitted to the cooling member 72. The GM refrigerator 10 and the heat transfer rod 74 are provided in, for example, four equal distributions in the circumferential direction of the cooling member 72. The heat transfer rod 74 is not an essential component, and the second cooling stage 20 may be in direct contact with the cooling member 72.

  As shown in FIG. 4, in the GM refrigerator 10 according to the embodiment, the axial direction of the superconducting coil 70 to be cooled is parallel to the axial directions of the first stage cylinder 11 and the second stage cylinder 12. As described above, the cooling member 72 is installed. Further, the drive rotation shaft 31 a that connects the motor 31 and the Scotch yoke mechanism 32 is installed so as to face the radial direction of the superconducting coil 70. As described above, in the GM refrigerator 10 according to the embodiment, the motor housing portion 5 and the housing 3 are separated, and the length of the drive rotating shaft 31a is such that the motor housing portion 5 and the housing 3 are integrated. It is longer than the length of the drive rotating shaft in the case where it is configured. As a result, the distance between the motor housing portion 5 that houses the motor 31 and the superconducting coil 70 is longer than when the motor housing portion 5 and the housing 3 are integrally formed. Moreover, the motor accommodating part 5 which accommodates the motor 31 will be arrange | positioned in the radial direction outer side with respect to the superconducting coil 70 which is an annular | circular shaped coil. Thereby, the influence which the motor 31 receives from the magnetic field which a superconducting coil generate | occur | produces can be reduced.

  As explained above, according to the GM refrigerator 10 which concerns on embodiment, the influence of the external magnetic field which the motor 31 with which the GM refrigerator 10 is provided can be reduced.

  In particular, the GM refrigerator 10 according to the embodiment does not change the overall height as compared with the case where the influence of the external magnetic field is reduced by inserting a long heat transfer rod between the superconducting coil 70 and the GM refrigerator 10. Thus, the influence of the external magnetic field received by the motor 31 can be reduced. Since the GM refrigerator 10 becomes compact, the freedom degree of installation of the GM refrigerator 10 can be improved. Since the heat transfer rod 74 can be omitted or shortened, the influence of the external magnetic field received by the motor 31 can be reduced while maintaining the heat transfer efficiency of the GM refrigerator 10.

  Further, by separating the motor housing portion 5 that houses the motor 31 and the housing 3 that houses the scotch yoke mechanism 32 and the like, the power of the motor 31 is supplied to the scotch yoke mechanism 32 among the wall surfaces constituting the motor housing portion 5. The magnetic shield member can cover a portion other than the portion through which the drive rotating shaft 31a is transmitted. Thereby, the influence of the external magnetic field which the motor 31 receives can be reduced efficiently.

  As mentioned above, although this invention was demonstrated based on embodiment, embodiment only shows the principle and application of this invention. In the embodiment, many modifications and arrangements can be made without departing from the spirit of the present invention defined in the claims. For example, instead of the second hermetic container 6, a bearing that maintains hermeticity may be used for the third drive rotary bearing 60c so that the hermeticity of the first hermetic container is maintained.

(First modification)
FIG. 5 is a cross-sectional view of a GM refrigerator 10 according to a modification of the embodiment. Similarly to the GM refrigerator 10 shown in FIG. 1, the GM refrigerator 10 according to the modified example includes a drive rotation shaft 31 a, a second drive rotation bearing 60 b at the output side end of the motor 31, a Scotch yoke mechanism 32, and the like. It is supported at at least two places with the third drive rotary bearing 60c at the end on the connecting side. This is because the GM refrigerator 10 according to the modified example also uses a long drive rotating shaft 31a, similarly to the GM refrigerator 10 shown in FIG. Thereby, the distance of the motor 31 and the 2nd cooling stage 20 becomes long, and the influence of the external magnetic field which the motor 31 receives can be reduced.

  As shown in FIG. 5, unlike the GM refrigerator 10 shown in FIG. 1, the GM refrigerator 10 which concerns on a modification does not have the 2nd airtight container 6 which accommodates the drive rotating shaft 31a. Instead, the GM refrigerator 10 according to the modification is connected to a region where the first airtight container 4 is expanded and accommodates the motor 31, and the drive rotating shaft 31 a is accommodated in the first airtight container 4. Compared with the GM refrigerator 10 shown in FIG. 1, there is an effect in that the airtightness of the first airtight container 4 can be maintained without using the first seal member 64a, the second seal member 64b, and the like. Moreover, since the motor accommodating part 5, the 2nd airtight container 6, and the housing 3 are not isolate | separated but become an integral structure, the intensity | strength of the GM refrigerator 10 can be improved.

(Second modification)
The case where the distance between the motor 31 and the second stage cooling stage 20 is increased by elongating the drive rotation shaft 31a that connects the motor 31 and the scotch yoke mechanism 32 has been described. Instead of this, or in addition to this, the heat transfer rod 74 connecting the GM refrigerator 10 and the cooling member 72 may be extended in the horizontal direction. Although not shown, for example, in FIG. 4B described above, the total height of the GM refrigerator 10 is increased by extending the heat transfer rod 74 in the lateral direction of FIG. 4B (radial direction of the superconducting coil). While suppressing this, the distance between the motor 31 and the second cooling stage 20 can be increased. Although the heat transfer distance may be extended by extending the heat transfer rod 74 and the cooling efficiency may be deteriorated, the conventional GM refrigerator 10 in which the motor housing portion 5 and the housing 3 are made close to each other and integrated with each other. Since it can be diverted, it is advantageous in terms of cost.

  DESCRIPTION OF SYMBOLS 1 Compressor, 1a Low pressure piping, 1b High pressure piping, 2 Cylinder, 3 Housing, 4 1st airtight container, 5 Motor accommodating part, 6 2nd airtight container, 10 GM refrigerator, 11 1st stage cylinder, 12 2nd Stage cylinder, 13 First stage displacer, 14 Second stage displacer, 17 Regenerator, 19 First stage cooling stage, 20 Second stage cooling stage, 21 First stage expansion space, 22 Second stage Eye expansion chamber, 23 upper chamber, 30 drive device, 31 motor, 31a drive rotation shaft, 32 scotch yoke mechanism, 33 crank, 33b crank pin, 34 scotch yoke, 35 yoke plate, 35a horizontal window, 36 drive shaft, 37 roller Bearing, 38a, 38b Sliding bearing, 40 Rotary valve, 41 Stator Valve, 42 Rotor valve, 43 Fixed pin, 44 Refrigerant gas supply hole, 45 Stator side sliding surface, 46 Arc-shaped groove, 47 Discharge port, 48 Opening, 49 Gas flow path, 50 Rotor side sliding surface, 51 Length Circular groove, 52 opposite end face, 53 arc-shaped hole, 60a first drive rotary bearing, 60b second drive rotary bearing, 60c third drive rotary bearing, 62 rotor valve bearing, 64a first seal member, 64b second seal Member, 70 superconducting coil, 72 cooling member, 74 heat transfer rod.

Claims (5)

A cryogenic refrigerator suitable for cooling superconducting coils,
A motor,
A drive rotary shaft coupled to the motor;
A scotch yoke mechanism that converts the rotation of the drive rotary shaft into a reciprocating motion, and
The drive rotation shaft is rotatably supported at a plurality of locations in the longitudinal direction, and the plurality of locations are connected to one end of the drive rotation shaft connected to the motor and to the Scotch yoke mechanism. A cryogenic refrigerator comprising the other end of the drive rotating shaft. A motor accommodating portion for accommodating the motor;
The motor accommodating portion includes a side wall, a top wall, and a bottom wall,
The cryogenic refrigerator according to claim 1, wherein at least the bottom wall and the side wall through which the drive rotating shaft passes are each provided with a magnetic shield member. A first hermetic container configured to receive the refrigerant gas used to cool the superconducting coil by accommodating the Scotch yoke mechanism;
The cryogenic refrigerator according to claim 1, further comprising a second hermetic container that accommodates the drive rotating shaft.   The said 2nd airtight container connects the said motor accommodating part and the said 1st airtight container so that the motor accommodating part which accommodates the said motor may be separated from the said 1st airtight container. Cryogenic refrigerator. A first seal member for sealing between the first hermetic container and the second hermetic container;
5. The cryogenic refrigerator according to claim 3, further comprising a second seal member that seals between the second hermetic container and a motor housing portion that houses the motor.

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