GM refrigerator

Abstract

To provide a GM refrigerator in which a maximum value of load torque imposed on a drive force source can be reduced.SOLUTION: A GM refrigerator 10 comprises: a cylinder member 11 in which working gas is filled into an in-cylinder space 110; a displacer 12 which is arranged in axially reciprocatable manner in the in-cylinder space 110; a crankshaft 15 which rotates with the rotation of a rotating shaft 141 of an electric motor 14; a scotch yoke 16 reciprocally moving the displacer 12 by the rotation of the crankshaft 15; a housing 13 which is arranged at a side of a high temperature end portion of the cylinder member 11, and in which the scotch yoke 16 is arranged; a pressure vibration mechanism 17 which is constituted in such a manner that a volume and pressure of the working gas in a low-temperature end portion and the high-temperature end portion of the in-cylinder space 110 are varied following a GM cycle; and a first spring 21 and a second spring 22 elastically energizing the displacer 12 toward a side of the low-temperature end portion from the side of the high-temperature end portion.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a GM (Gifford McMahon) refrigerator. [Background technology]

[0002] Conventionally, a GM refrigerator includes a cylinder member having a low temperature end and a high temperature end and filled with a working gas such as helium, a displacer that moves the working gas by reciprocating inside the cylinder member between the low temperature end and the high temperature end, a drive mechanism that moves the displacer back and forth inside the cylinder member, and a pressure oscillation mechanism that applies high and low pressure alternately to the internal space of the cylinder member in conjunction with the reciprocating movement of the displacer so that the volume and pressure of the working gas in the internal space of the cylinder member vary in accordance with a GM cycle (Gifford McMahon cycle).

[0003] Patent Document 1 discloses a GM refrigerator that includes an electric motor, a crankshaft, and a Scotch yoke connected to the displacer as a drive mechanism for reciprocating the displacer. The drive mechanism of Patent Document 1 is configured to eccentrically rotate the crank pin of the crankshaft by the rotational power of the electric motor and convert the eccentric rotation of the crank pin into reciprocating movement of the Scotch yoke, thereby reciprocating the displacer.

[0004] In such a drive mechanism, the load torque transmitted from the displacer to the crank pin of the crankshaft via the Scotch yoke acts on the rotating shaft of the electric motor in a direction that tries to stop the rotation of the rotating shaft. The load torque applied to the rotating shaft of the electric motor varies depending on the position of the displacer during one cycle of the GM cycle (in other words, the phase of the GM cycle). For this reason, an electric motor that outputs a drive torque larger than the maximum value of the fluctuating load torque must be applied to the drive mechanism of the GM refrigerator. Furthermore, as the drive torque increases, the size and weight of the electric motor also increase, leading to an increase in the size and weight of the GM refrigerator. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-161146 A Summary of the Invention

[0006] (Problem to be solved by the invention) The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a GM refrigerator that can reduce the maximum value of the load torque applied to the driving force source.

[0007] (Means for solving the problem) In order to solve the above problems, the GM refrigerator of the present invention has: a cylinder member having a high temperature end on one end side and a low temperature end on the other end side, and an internal space of the cylinder that is filled with a working gas; a displacer filled with a cold storage material and disposed in the cylinder space so as to be reciprocally movable in a first direction, which is an axial direction of the cylinder member; A driving force source having a rotating shaft that outputs rotational power; a crankshaft having an eccentric portion connected to the rotary shaft and eccentrically rotating about an axis of the rotary shaft as the rotary shaft rotates; a Scotch yoke including: a frame-shaped portion formed in a frame shape to define an inner space, into which the eccentric portion of the crankshaft is inserted; and a first rod portion having one end connected to the frame-shaped portion and the other end connected to the displacer, wherein the eccentric rotation of the eccentric portion within the inner space causes the frame-shaped portion and the first rod portion to reciprocate in the first direction, thereby reciprocating the displacer in the first direction within the cylinder internal space; a housing disposed on the high temperature end side of the cylinder member, the housing defining a space therein in which the Scotch yoke is disposed; a pressure oscillation mechanism including a compressor that generates high and low pressures, and that alternately applies the high and low pressures generated by the compressor to the cylinder space in association with the reciprocating movement of the displacer so that the volume and pressure of the working gas in the low temperature end and the high temperature end of the cylinder space fluctuate according to a GM cycle; a biasing member that elastically biases the displacer in a direction from the high temperature end toward the low temperature end of the cylinder member in the first direction; Equipped with.

[0008] In the GM refrigerator of the present invention, the maximum value of the load torque (torque applied to the rotating shaft of the driving force source from outside the driving force source, with a positive value in the opposite direction to the driving torque output by the driving force source) generated by a cause other than the biasing force of the biasing member exists while the displacer moves in the space inside the cylinder from the high temperature end side to the low temperature end side. The biasing member of the GM refrigerator of the present invention is configured to elastically bias the displacer from the high temperature end side to the low temperature end side. That is, the torque due to the biasing force of the biasing member acts in a direction that reduces the load torque while the displacer moves from the high temperature end side to the low temperature end side. This makes it possible to reduce the maximum value of the load torque. This makes it possible to reduce the driving torque required of the electric motor, and therefore makes it possible to apply a smaller and lighter electric motor than in a configuration without a biasing member. As a result, it is possible to reduce the size and weight of the GM refrigerator. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view of a GM refrigerator according to this embodiment. [Diagram 2] FIG. 2 is a schematic cross-sectional view of the GM refrigerator according to this embodiment, taken along line II-II of FIG. [Diagram 3] FIG. 3 is a schematic diagram illustrating the load torque applied to the electric motor. [Figure 4] FIG. 4 is a graph showing a schematic diagram of the fluctuation of the load torque applied to the electric motor. [Diagram 5]FIG. 5 is a graph showing a schematic diagram of the fluctuation of the load torque applied to the electric motor. [Figure 6] FIG. 6 is a graph showing a schematic diagram of the fluctuation of the load torque applied to the electric motor. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (GM refrigerator configuration) Figures 1 and 2 are schematic cross-sectional views of a GM refrigerator 10 according to this embodiment. Note that Figure 2 is a cross-sectional view taken along the line II-II in Figure 1. The GM refrigerator 10 according to this embodiment includes a cylinder member 11, a displacer 12, a housing 13, an electric motor 14, a crankshaft 15, a Scotch yoke 16, and a pressure vibration mechanism 17. The pressure vibration mechanism 17 includes a compressor 18, a high-pressure valve 19, a low-pressure valve 20, and an opening / closing control mechanism (not shown). Note that, although this embodiment shows an example in which the GM refrigerator 10 is a single-stage type, the GM refrigerator 10 is not limited to being a single-stage type.

[0011] The cylinder member 11 is a member having a substantially cylindrical configuration with a space 110 provided therein. Hereinafter, this space may be referred to as the "cylinder space 110". The cylinder space 110 is filled with a working gas (e.g., helium gas). Of both ends in the axial direction of the cylinder member 11, the end closer to the housing 13 described later is referred to as the high-temperature end, and the end farther from the housing 13 is referred to as the low-temperature end. In this embodiment, the cylinder member 11 has a bottomed tubular configuration in which the high-temperature end side in the axial direction is open and the low-temperature end side is closed. The opening of the cylinder member 11 is closed by attaching the housing 13 to the open side of the cylinder member 11. The axial direction of the cylinder member 11 is an example of the first direction of the present invention. In this embodiment, the axial direction (first direction) of the cylinder member 11 is a direction substantially parallel to the up-down direction. In this embodiment, the cylinder member 11 is arranged so that the high-temperature end is located on the upper side and the low-temperature end is located on the lower side. 1 and 2, the upper direction is indicated by an arrow Up and the lower direction is indicated by an arrow Dw, but the orientation of the cylinder member 11 is not limited thereto.

[0012] A cold head 30 (cold heat transfer member) is attached to the outer circumferential side surface and end face of the low-temperature end of the cylinder member 11. The cold head 30 is a member for transferring the cold generated at the low-temperature end of the cylinder member 11 to an object to be cooled.

[0013] In the cylinder space 110, the displacer 12 is disposed so as to be capable of reciprocating in the axial direction. The displacer 12 has a substantially cylindrical shape with a space 120 provided therein. Hereinafter, this space 120 may be referred to as a "cold storage chamber 120." The axial length of the displacer 12 is shorter than the axial length of the cylinder space 110. In the cylinder space 110, a back space 111 and an expansion space 112 are formed by the displacer 12 and a base plate 31 (described later). It can also be said that the cylinder space 110 is partitioned by the displacer 12 and the base plate 31 into the back space 111 on the high temperature end side and the expansion space 112 on the low temperature end side.

[0014] The back space 111 is a space located closer to the housing 13 than one axial end face of the displacer 12 that is closer to the housing 13 (i.e., the end face closer to the high temperature end of the cylinder member 11). The expansion space 112 is a space located farther from the housing 13 than the other axial end face of the displacer 12 (i.e., the end face closer to the low temperature end of the cylinder member 11). In other words, the back space 111 is a space formed at the high temperature end of the cylinder member 11 and its vicinity, and the expansion space 112 is a space formed at the low temperature end of the cylinder member 11 and its vicinity.

[0015] An annular seal ring 32 is attached to the outer circumferential surface of the displacer 12 at or near the end thereof that is closer to the housing 13. This seal ring 32 blocks the movement of working gas between the back space 111 and the expansion space 112 through a gap between the outer circumferential surface of the displacer 12 and the inner circumferential surface of the cylinder member 11.

[0016] The cold storage chamber 120 of the displacer 12 is filled with a cold storage material 121 made of a material having a large specific heat at low temperatures of about 30 to 100 K. The cold storage material 121 can be made of a laminate such as a wire mesh made of a copper alloy, for example.

[0017] A first communication passage 122 is provided in the displacer 12 and the base plate 31. The first communication passage 122 is a path that communicates the cold storage chamber 120 and the back space 111. One end of the first communication passage 122 is provided on the surface of the base plate 31 facing the housing 13. Furthermore, a second communication passage 123 is provided in the displacer 12. The second communication passage 123 is a path that communicates the cold storage chamber 120 and the expansion space 112. One end of the second communication passage 123 is provided on the side peripheral surface of the displacer 12, near the end face on the side close to the low temperature end of the cylinder member 11. In this way, the expansion space 112 and the back space 111 communicate with each other through the first communication passage 122 of the displacer 12 and the base plate 31, the cold storage chamber 120 of the displacer 12, and the second communication passage 123 of the displacer 12.

[0018] A housing 13 is attached to the high temperature end of the cylinder member 11 so as to be aligned in the axial direction with respect to the cylinder member 11. The housing 13 includes a housing body 131, a housing cap 132, and a spring housing 133. The housing cap 132 is attached to the housing body 131 to form a space 130 inside the housing 13. Hereinafter, this space may be referred to as the "housing internal space 130." The housing internal space 130 is filled with a working gas.

[0019] The housing body 131 has a box-like configuration with a bottom that is closed on the side closer to the cylinder member 11 and open on the opposite side. The opening on the high temperature end side of the cylinder member 11 is blocked by a part of the housing body 131 that corresponds to the "bottom of the box." A first rod insertion hole 134 is provided in the part of the housing body 131 that corresponds to the "bottom of the box." The first rod insertion hole 134 is a through hole that penetrates the housing body 131 in a direction substantially parallel to the axial direction of the cylinder member 11 and communicates between the housing internal space 130 and the cylinder internal space 110. The first rod insertion hole 134 is configured to allow a first rod portion 162 of the Scotch yoke 16, which will be described later, to be inserted therethrough.

[0020] The housing body 131 is provided with a high-pressure path 136, a first low-pressure path 137, and a second low-pressure path 138. The high-pressure path 136, the first low-pressure path 137, and the second low-pressure path 138 are all paths through which the working gas can flow. The high-pressure path 136 is configured to communicate between the intra-cylinder space 110 and the outside of the housing body 131 when the housing body 131 is attached to the cylinder member 11. The first low-pressure path 137 is configured to communicate between the intra-cylinder space 110 and the housing intra-space 130 when the housing body 131 is attached to the cylinder member 11. The second low-pressure path 138 is configured to communicate between the intra-housing space 130 and the outside of the housing body 131.

[0021] The housing cap 132 is a generally plate-shaped member, and is attached to the housing body 131 on the side opposite to the cylinder member 11, thereby closing (covering) the opening of the housing body 131. A second rod insertion hole 135 is provided in the housing cap 132. The second rod insertion hole 135 is a through-hole that passes through the housing cap 132 in a direction generally parallel to the axial direction of the cylinder member 11, and is configured to allow a second rod portion 163 of the Scotch yoke 16, which will be described later, to be inserted therethrough.

[0022] The spring housing 133 is a cylindrical member having one open end and the other closed end. The spring housing 133 is configured to be able to accommodate the first spring 21 therein. The spring housing 133 is attached to the housing cap 132 with the open side facing the housing cap 132 so as to cover the second rod insertion hole 135 provided in the housing cap 132.

[0023] The electric motor 14 is an example of a driving force source of the present invention. The electric motor 14 is arranged such that the axis C of the rotating shaft 141 is aligned with the axis C of the rotating shaft 141. M The electric motor 14 is disposed in a direction substantially perpendicular to the axial direction (first direction) of the cylinder member 11. The electric motor 14 is attached to the outer periphery of the housing body 131.

[0024] The crankshaft 15 includes a main shaft 151 and a crank pin 152. The crank pin 152 is an example of an eccentric portion of the present invention. The main shaft 151 of the crankshaft 15 is coaxially connected to the rotating shaft 141 of the electric motor 14. Therefore, the crank pin 152 of the crankshaft 15 is aligned with the axis C of the rotating shaft 141 of the electric motor 14 by the operation of the electric motor 14. M It rotates eccentrically in a circular orbit around the center.

[0025] The Scotch yoke 16 includes a frame portion 161, a first rod portion 162, and a second rod portion 163. The frame portion 161 is a substantially quadrilateral frame-shaped portion (which can also be called a picture frame-shaped portion) having an inner space that is an opening on the inner circumference when viewed in the axial direction of the crank pin 152. The frame portion 161 is disposed in the housing inner space 130, and the crank pin 152 having a bearing 33 attached to its outer circumference is inserted into the inner space of the frame portion 161. The first rod portion 162 and the second rod portion 163 are rod-shaped portions that extend from the frame portion 161 to opposite sides in the axial direction of the cylinder member 11. The first rod portion 162 is inserted into the first rod insertion hole 134 of the housing body 131, and the tip portion of the first rod portion 162 is located in the cylinder inner space 110. The displacer 12 is attached to the tip portion of the first rod portion 162 via the base plate 31. The base plate 31 is a substantially disk-shaped member. The base plate 31 is joined to the tip end of the first rod portion 162, and is attached to an end surface located on the high temperature end side of the displacer 12 with the first rod portion 162 joined. The second rod portion 163 is inserted into the second rod insertion hole 135 of the housing cap 132, and the tip end of the second rod portion 163 is located inside the spring housing 133.

[0026] A plain bearing 34 and a seal ring 35 are disposed inside the first rod insertion hole 134, and a plain bearing 34 is disposed inside the second rod insertion hole 135. The first rod portion 162 and the second rod portion 163 are supported via the plain bearing 34 so as to be linearly movable relative to the housing 13 in a direction substantially parallel to the axial direction of the cylinder member 11. The seal ring 35 disposed inside the first rod insertion hole 134 blocks the flow of working gas through the first rod insertion hole 134.

[0027] When the crankshaft 15 rotates due to the rotational power output by the electric motor 14, the crank pin 152 of the crankshaft 15 is aligned with the axis C of the rotary shaft 141 of the electric motor 14. M1 and 2), the displacer 12 moves back and forth in the axial direction of the cylinder member 11. The reciprocating movement of the Scotch yoke 16 causes the displacer 12 to move back and forth in the axial direction of the cylinder member 11 within the cylinder interior space 110. For ease of explanation, the position of the end of the reciprocating movement range of the displacer 12 caused by the crankshaft 15 and the Scotch yoke 16 that is closer to the low temperature end of the cylinder member 11 (the lower end position in Figs. 1 and 2) may be referred to as the first dead center, and the position of the end of the reciprocating movement range of the displacer 12 that is closer to the high temperature end of the cylinder member 11 (the upper end position in Figs. 1 and 2) may be referred to as the second dead center.

[0028] The first spring 21 and the second spring 22 are examples of the first elastic compression coil spring and the second elastic compression coil spring of the biasing member of the present invention. The first spring 21 and the second spring 22 are configured to constantly elastically bias the Scotch yoke 16 and the displacer 12 toward the first dead center. The first spring 21 and the second spring 22 are both applied with compression coil springs that can be elastically compressed and deformed. The first spring 21 is housed inside the spring housing 133 and is arranged coaxially with the second rod portion 163 and between the bottom surface inside the spring housing 133 and the end (e.g., end surface) of the second rod portion 163 of the Scotch yoke 16 via a spring seat 23 installed on the end surface of the second rod portion 163. The first spring 21 constantly elastically biases the end of the second rod portion 163 of the Scotch yoke 16 toward the first dead center, thereby constantly elastically biasing the displacer 12 from the second dead center toward the first dead center via the Scotch yoke 16. The second spring 22 is disposed between an end face of the displacer 12 on the high temperature end side and an end face of the housing 13 on the side closer to the cylinder member 11. The second spring 22 is disposed coaxially with the first rod portion 162 and surrounding the first rod portion 162 (around the first rod portion 162). The second spring 22 constantly elastically biases the end face of the base plate 31 on the side closer to the housing 13, thereby constantly elastically biasing the displacer 12 from the second dead center toward the first dead center. In this embodiment, the base plate 31 is attached to the displacer 12, so strictly speaking, the second spring 22 is disposed between the base plate 31 and the housing 13. The second spring 22 constantly elastically biases the displacer 12 from the second dead center side toward the first dead center side via the base plate 31.

[0029] The compressor 18 has a low pressure port 182 and a high pressure port 181. The compressor 18 is configured to suck in low pressure working gas from the low pressure port 182, compress the working gas inside, release heat of compression to the outside from a heat sink (not shown), and discharge the compressed high pressure working gas from the high pressure port 181. Therefore, low pressure is generated on the low pressure port 182 side of the compressor 18, and high pressure is generated on the high pressure port 181 side of the compressor 18. The high pressure port 181 of the compressor 18 is connected to an end of the high pressure path 136 of the housing body 131 on the "outer periphery side of the housing body 131". The low pressure port 182 of the compressor 18 is connected to an end of the second low pressure path 138 of the housing body 131 on the "outer periphery side of the housing body 131".

[0030] The high pressure valve 19 and the low pressure valve 20 are configured to allow the flow of the working gas when in an open state, and not allow the flow of the working gas (block the flow of the working gas) when in a closed state. The high pressure valve 19 is provided on a high pressure path 136 of the housing body 131. Therefore, when the high pressure valve 19 is in an open state, the high pressure path 136 is opened, and the high pressure port 181 of the compressor 18 and the intra-cylinder space 110 are in communication (a state in which the high pressure generated on the side of the high pressure port 181 of the compressor 18 is applied to the intra-cylinder space 110), and when the high pressure valve 19 is in a closed state, the high pressure path 136 is closed, and the high pressure port 181 of the compressor 18 and the intra-cylinder space 110 are blocked (a state in which the high pressure generated on the side of the high pressure port 181 of the compressor 18 is not applied to the intra-cylinder space 110).

[0031] The low-pressure valve 20 is provided on the first low-pressure path 137. When the low-pressure valve 20 is in an open state, the first low-pressure path 137 is opened, and the low-pressure port 182 of the compressor 18 and the intra-cylinder space 110 are in communication with each other (the working gas present in the intra-cylinder space 110 is sucked into the low-pressure port 182 of the compressor 18 through the first low-pressure path 137, the intra-housing space 130, and the second low-pressure path 138), and when the low-pressure valve 20 is in a closed state, the first low-pressure path 137 is closed, and the intra-housing space 130 and the intra-cylinder space 110 are blocked off (the working gas present in the intra-cylinder space 110 cannot move to the intra-housing space 130 through the first low-pressure path 137).

[0032] The opening / closing control mechanism (not shown) is configured to switch between the open and closed states of the high pressure valve 19 and the low pressure valve 20 in conjunction with the position of the displacer 12. The operation of switching between the open and closed states of the high pressure valve 19 and the low pressure valve 20 by the opening / closing control mechanism will be described later. For example, the opening / closing control mechanism described in JP 2017-161146 A (referred to as a "valve opening / closing control unit" in the document) can be used as the opening / closing control mechanism.

[0033] (GM refrigerator operation) Next, the operation of the GM refrigerator 10 according to this embodiment will be described. When the electric motor 14 is operated, the crank pin 152 of the crankshaft 15 is aligned with the axis C of the rotating shaft 141 of the electric motor 14. MThe crank pin 152 rotates eccentrically about the center of the crankshaft 152. The eccentric rotation of the crank pin 152 causes the Scotch yoke 16 to move back and forth, and the displacer 12 joined to the Scotch yoke 16 moves back and forth in the axial direction in the cylinder space 110. The pressure in the cylinder space 110 fluctuates in conjunction with the movement of the displacer 12 due to the operation of the pressure vibration mechanism 17. The reciprocating movement of the displacer 12 and the operation of the pressure vibration mechanism 17 periodically repeat the high-pressure transfer stroke, expansion stroke, low-pressure transfer stroke, and compression stroke described below in this order. In other words, a GM cycle is realized. The repetition frequency of the GM cycle of the GM refrigerator 10 is set to one frequency (for example, 1.2 Hz) within a range of about 0.5 to 3 Hz.

[0034] The high-pressure transfer stroke is a stroke in which the high-pressure working gas present in the back space 111 and the high-pressure working gas discharged from the compressor 18 are transferred to the expansion space 112. The high-pressure transfer stroke starts from a state in which the displacer 12 is located at the first dead center, the high-pressure valve 19 is open, and the low-pressure valve 20 is closed. In this state, the volume of the expansion space 112 is minimum, and the volume of the back space 111 is maximum. In this state, the high pressure generated in the high-pressure port 181 of the compressor 18 is maintained in a state in which it is applied to the intra-cylinder space 110 via the high-pressure path 136. When the displacer 12 moves toward the second dead center with respect to the cylinder member 11, the volume of the back space 111 decreases and the volume of the expansion space 112 increases. Therefore, the high-pressure working gas present in the rear space 111 and the high-pressure working gas discharged from the compressor 18 flow into the cold storage chamber 120 through the first communication passage 122, and the working gas that has flowed into the cold storage chamber 120 is cooled by the cold storage material 121, which removes heat from the working gas. Then, the working gas cooled by the cold storage material 121 flows into the expansion space 112 through the second communication passage 123.

[0035] The expansion stroke is a stroke in which the working gas present in the expansion space 112 is expanded (pressurized). Specifically, the opening / closing control mechanism of the pressure oscillation mechanism 17 switches the high-pressure valve 19 to a closed state and switches the low-pressure valve 20 to an open state when the displacer 12 reaches the second dead center. As a result, the low pressure generated in the low-pressure port 182 of the compressor 18 is applied (pressurized) through the second low-pressure path 138, the housing inner space 130, and the first low-pressure path 137. Therefore, the working gas present in the expansion space 112 expands. The expansion work performed at this time generates cold heat in the expansion space 112 (i.e., the low-temperature end of the cylinder member 11).

[0036] The low-pressure transfer stroke is a stroke in which the low-pressure working gas present in the expansion space 112 is moved to the back space 111 and sucked into the compressor 18 via the space inside the housing 13. Specifically, when the displacer 12 moves from the second dead center toward the first dead center, the volume of the expansion space 112 decreases and the volume of the back space 111 increases. As a result, the working gas present in the expansion space 112 flows into the back space 111 through the second communication passage 123, the cold storage chamber 120, and the first communication passage 122. At this time, the cold storage material 121 arranged in the cold storage chamber 120 is cooled by the cold energy of the working gas, that is, the heat of the cold storage material 121 is transferred to the working gas, and the temperature of the working gas increases. The working gas that has flowed into the back space 111 is sucked into the compressor 18 through the housing inner space 130.

[0037] The compression stroke is a stroke for compressing (pressurizing) the working gas present in the back space 111. Specifically, when the displacer 12 reaches the first dead center, the opening / closing control mechanism of the pressure vibration mechanism 17 switches the low pressure valve 20 to a closed state and switches the high pressure valve 19 to an open state. This increases the internal pressure of the cylinder space 110. That is, the working gas present in the back space 111 is compressed. The heat generated by this compression is once transferred to the regenerator material 121 in the next high pressure transfer stroke, and then transferred again to the working gas in the subsequent low pressure transfer stroke, sent to the compressor 18, and released to the outside from a heat radiator (not shown) in the compressor 18.

[0038] In this way, the pressure vibration mechanism 17 applies high and low pressure to the cylinder space 110 in conjunction with the reciprocating movement of the displacer 12 in the cylinder space 110. This realizes a GM cycle (high pressure transfer stroke, expansion stroke, low pressure transfer stroke, compression stroke), and cold is generated in the expansion space 112. The cold generated in the expansion space 112 is transferred to the object to be cooled via the cold head 30.

[0039] (load torque) Next, the load torque will be described. FIG. 3 is a schematic diagram for explaining the load torque. The electric motor 14 is subjected to a load torque when moving the displacer 12. In this embodiment, the load torque is "a torque applied to the rotating shaft 141 of the electric motor 14 from the outside of the electric motor 14, and has a positive value (positive direction) in the opposite direction to the drive torque output by the electric motor 14 (the opposite direction to the rotation direction R of the crankshaft 15 in FIG. 3)." That is, in this embodiment, a positive load torque acts in a direction to stop the rotation of the rotating shaft 141 of the electric motor 14 due to the drive torque, and a negative load torque acts in a direction to assist the drive torque of the rotating shaft 141 of the electric motor 14.

[0040] As shown in FIG. 3, the load torque is a ratio of the load (force) W applied to the crank pin 152 of the crankshaft 15 in the axial direction to the axis C of the rotating shaft 141 of the electric motor 14. MThe load torque is calculated by multiplying the distance L in the direction perpendicular to the axial direction of the cylinder member 11 from the contact point P (the point of application of the load W) between the bearing 33 attached to the crank pin 152 and the frame portion 161 of the Scotch yoke 16 to the contact point P. Causes of the load torque include, for example, Pressure difference between the cylinder space 110 and the housing space 130 Friction between the seal ring 32 provided on the displacer 12 and the inner circumferential surface of the cylinder member 11 Gravity acting on the displacer 12 and the scotch yoke 16 Friction between the first rod portion 162 and the sliding bearing 34 and the seal ring 35 arranged inside the first rod insertion hole 134 Friction between the second rod portion 163 and the sliding bearing 34 arranged inside the second rod insertion hole 135 The pressure difference between the back space 111 and the expansion space 112 occurs due to the flow resistance when the working gas moves between the back space 111 and the expansion space 112 through the inside of the displacer 12. The biasing force of the first spring 21 and the second spring 22 Includes:

[0041] 4 is a graph showing a schematic diagram of the load torque fluctuation during one cycle of a GM cycle when the first spring 21 and the second spring 22 are not provided (i.e., a conventional configuration). Note that the load torque values ​​in the graph are merely examples, and the load torque values ​​are not limited to the values ​​in the graph (the same applies to FIGS. 5 and 6). In this graph, the phase θ is the phase θ of the axial center C of the rotating shaft 141 of the electric motor 14, which is parallel to the axial direction (vertical direction) of the cylinder member 11 when viewed in the axial direction of the rotating shaft 141 of the electric motor 14. M and the axis C of the rotating shaft 141 of the electric motor 14. M and the axis C of the crank pin 152 CThe phase θ is the angle between the line passing through the axis of the rotor 14 and the axis of the cylinder 12 (see FIG. 3). The phase θ is 0° when the displacer 12 is located at the first dead center, and is an angle whose positive value is the rotational direction R of the rotary shaft 141 of the electric motor 14. When the phase θ is 0° (=360°), it is the compression stroke, the period when the phase θ transitions from 0° to 180° is the high-pressure transfer stroke, when the phase θ is 180° is the expansion stroke, and the period when the phase θ transitions from 180° to 360° is the low-pressure transfer stroke.

[0042] As shown in Fig. 4, the load torque varies depending on the phase θ (in other words, the position of the displacer 12) during one cycle of the GM cycle. Specifically, when the phase θ is 0° and 180°, the distance L is 0, and the load torque is approximately 0. Also, there is one maximum value of the load torque when the phase θ is between 0° and 180° (i.e., during the high-pressure transfer stroke) and when the phase θ is between 180° and 360° (i.e., during the low-pressure transfer stroke).

[0043] As shown in FIG. 4, the maximum value of the load torque that exists when the phase θ is between 180° and 360° is greater than the maximum value of the load torque that exists when the phase θ is between 0° and 180°. The reason is as follows. Since the high-pressure transfer stroke occurs while the phase transitions from 0° to 180°, the internal pressure of the cylinder space 110 is higher than the internal pressure of the housing space 130. Therefore, a load (force) is applied from the cylinder space 110 toward the housing space 130 to the Scotch yoke 16, the load (force) being calculated by the product of the "cross-sectional area of ​​the first rod portion 162" and the "pressure difference between the cylinder space 110 and the housing space 130". Therefore, the load torque applied to the rotating shaft 141 of the electric motor 14 includes the torque due to this load. Hereinafter, this torque may be referred to as the "first rod portion pressure difference torque".

[0044] The first rod pressure difference torque acts in the same direction as the rotation direction of the crank pin 152 of the crankshaft 15 while the phase θ transitions from 0° to 180°, so the load torque is reduced. In contrast, while the phase θ transitions from 180° to 360°, this is a low-pressure transfer stroke, so there is almost no pressure difference between the cylinder space 110 and the housing space 130. Therefore, almost no first rod pressure difference torque is generated during this period, so the maximum value of the load torque that exists between the phase θ of 180° and 360° is larger than the maximum value of the load torque that exists between the phase θ of 0° and 180°. The maximum value of the load torque that exists between the phase θ of 180° and 360° is the maximum value of the load torque.

[0045] If the drive torque output by the electric motor 14 is small, fluctuations in the load torque may cause the electric motor 14 to step out. For this reason, the electric motor 14 must be configured to be able to output a drive torque that is somewhat greater than the maximum value of the load torque. However, as the drive torque increases, the electric motor generally becomes larger and heavier, which leads to an increase in the size and weight of the GM refrigerator.

[0046] In this embodiment, the first spring 21 and the second spring 22 reduce the maximum value of the load torque. Hereinafter, the load torque generated by the first spring 21 and the second spring 22 may be referred to as "spring torque". FIG. 5 is a graph that shows a schematic diagram of the load torque when the first spring 21 and the second spring 22 are not provided, the spring torque, and the load torque when the first spring 21 and the second spring 22 are provided. The spring torque is calculated as the product of the biasing force of the first spring 21 and the second spring 22 (the force in the axial direction of the cylinder member 11) and the distance L (see FIG. 3). Since the distance L is maximum when the phase θ is 90° and 270°, the spring torque is maximum when the phase θ is in the vicinity of 90° and is minimum when the phase is in the vicinity of 270°. In addition, since the biasing forces of the first spring 21 and the second spring 22 become larger as the phase θ approaches 180°, the phase θ at which the spring torque becomes maximum and the phase θ at which the spring torque becomes minimum shift toward the 180° side.

[0047] The first spring 21 and the second spring 22 constantly elastically bias the Scotch yoke 16 and the displacer 12 from the second dead center side toward the first dead center side. Therefore, while the phase θ transitions from 180° to 360° (i.e., while the displacer 12 moves from the second dead center toward the first dead center), the spring torque is a negative value and acts in the same direction as the drive torque of the electric motor 14. Therefore, with this configuration, the maximum value of the load torque can be reduced.

[0048] On the other hand, while the phase θ transitions from 0° to 180° (i.e., while the displacer 12 moves from the first dead center to the second dead center), the spring torque has a positive value and acts in a direction to stop the rotation of the rotating shaft 141 of the electric motor 14. For this reason, the spring torque increases the "maximum value of the load torque while the phase θ is from 0° to 180°" from T1 to T3. Then, when the absolute value of the spring torque becomes equal to or greater than the difference ΔT between the "maximum value T2 of the load torque when the phase θ is from 180° to 360°" and the "maximum value T1 of the load torque when the phase θ is from 0° to 180°" when the first spring 21 and the second spring 22 are not provided (hereinafter, this difference may be referred to as the "load torque difference ΔT before reduction"), the "maximum value T3 of the load torque when the phase θ is from 0° to 180°" increased by the spring torque becomes equal to or greater than the "maximum value T2 of the load torque when the phase θ is from 180° to 360°" when the load torque is not reduced by the spring torque. For this reason, in this case, the effect of reducing the load torque by the spring torque is lost.

[0049] Therefore, in this embodiment, the biasing forces of the first spring 21 and the second spring 22 are specified so that the absolute value of the spring torque is "greater than 0 and less than the absolute value of the pre-reduction load torque difference ΔT." With this configuration, it is possible to prevent the "maximum value T3 of the load torque when the phase θ is between 0° and 180°" increased by the spring torque from becoming equal to or greater than the "maximum value T2 of the load torque when the phase θ is between 180° and 360°" when the load torque is not reduced by the spring torque. Therefore, the maximum value of the load torque can be reduced compared to a configuration in which the first spring 21 and the second spring 22 are not provided.

[0050] In addition, the absolute value of the spring torque is preferably approximately 0.5 times the absolute value of the pre-reduction load torque difference ΔT at the phase θ where the load torque has a maximum value (specifically, approximately 90° and approximately 270°). If the absolute value of the spring torque is approximately 0.5 times the absolute value of the pre-reduction load torque difference ΔT at the phase θ where the load torque has a maximum value, the "maximum value T3 of the load torque when the phase θ is between 0° and 180°" increased by the spring torque and the "maximum value T4 of the load torque when the phase θ is between 180° and 360°" reduced by the spring torque become approximately the same. Therefore, the reduction amount of the maximum value of the load torque can be maximized. This configuration can also be said to be a configuration that reduces the maximum value of the load torque by reducing or setting to zero (in other words, leveling) the difference between the "maximum value T3 of the load torque when the phase θ is between 180° and 360°" and the "maximum value T4 of the load torque when the phase θ is between 0° and 180°".

[0051] Note that the "maximum values ​​T2, T4 of the load torque when the phase θ is between 180° and 360°" and the "maximum values ​​T1, T3 of the load torque when the phase θ is between 0° and 180°" are both determined according to the masses of the displacer 12 and the Scotch yoke 16, the frictional force caused by the seal ring 32, the frictional force caused by the sliding bearing 34 and the seal ring 35, and the eccentricity dimension of the axis of the crank pin 152 relative to the axis of the main shaft 151 of the crankshaft 15. For this reason, the specific values ​​of the biasing forces of the first spring 21 and the second spring 22 (i.e., the specific spring constant values) are determined based on these. Furthermore, if the GM refrigerator 10 is configured to include the first spring 21 and the second spring 22 as in this embodiment, the biasing forces of the first spring 21 and the second spring 22 are specified so that the sum of the spring torques caused by the first spring 21 and the second spring 22 is within the above-mentioned range.

[0052] FIG. 6 is a graph showing the variation of the load torque in a configuration in which the cross-sectional area of ​​the first rod portion 162 (more precisely, the cross-sectional area of ​​the portion of the first rod portion 162 inserted into the first rod insertion hole 134) is larger than that in FIG. 5. When the cross-sectional area of ​​the first rod portion 162 is larger, the first rod portion pressure difference torque also becomes larger. When the first rod portion pressure difference torque becomes larger, the maximum value T1 of the load torque between the phase θ of 0° and 180° in the case where the first spring 21 and the second spring 22 are not provided becomes smaller. As a result, the pre-reduction load torque difference ΔT becomes larger. Therefore, the reduction amount of the "maximum value T2 of the load torque between the phase θ of 180° and 360°" (i.e., the maximum value of the load torque) due to the spring torque can be increased. Therefore, the electric motor 14 can be further reduced in size and weight.

[0053] Furthermore, if the Scotch yoke 16 and the displacer 12 are configured to be constantly elastically biased by the first spring 21 and the second spring 22, it is possible to prevent or suppress rattling between the bearing 33 attached to the crank pin 152 of the crankshaft 15 and the frame-shaped portion 161 of the Scotch yoke 16. Also, if the Scotch yoke 16 and the base plate 31 are configured to be constantly elastically biased by the second spring 22, it is possible to prevent or suppress rattling at the joint between the Scotch yoke 16 and the base plate 31. As a result, it is possible to prevent or suppress wear of each member at these points.

[0054] In addition, when the first spring 21 is provided outside the housing 13 as in the embodiment, the internal structure of the housing 13 and the cylinder member 11 does not need to be changed from the conventional structure in order to arrange the first spring 21. Therefore, the arrangement of the first spring 21 is easy. On the other hand, when the second spring 22 is provided in the cylinder space 110 as in the embodiment, no space is required for arranging the second spring 22 outside the housing 13 and the cylinder member 11, so the external dimensions of the housing 13 and the cylinder member 11 do not become large. In addition, when the first spring 21 and the second spring 22 (i.e., a plurality of springs) are arranged as in the embodiment, the first spring 21 and the second spring 22 can be made smaller than when only one of the first spring 21 and the second spring 22 is arranged. Therefore, the space required for arranging the first spring 21 and the second spring 22 may be small, so that it is easy to secure the arrangement space for the first spring 21 and the second spring 22.

[0055] In the above embodiment, the GM refrigerator 10 includes the first spring 21 and the second spring 22, but the present invention is not limited to this configuration. For example, the GM refrigerator 10 may include only one of the first spring 21 and the second spring 22. The GM refrigerator 10 may include a spring (biasing member) other than the first spring 21 and the second spring 22. Furthermore, the positions of the first spring 21 and the second spring 22 are not limited to those in the above embodiment. For example, a compression coil spring may be provided in the housing inner space 130. In this case, a configuration in which the compression coil spring is installed between the housing cap 132 and the frame-shaped portion 161 of the Scotch yoke 16 and biases the housing cap 132 and the frame-shaped portion 161 of the Scotch yoke 16 in a direction separating them can be applied.

[0056] (Summary of the embodiment) The GM refrigerator 10 according to this embodiment has: a cylinder member 11 having a high temperature end on one end side and a low temperature end on the other end side, and an internal space 110 of the cylinder filled with a working gas; a displacer 12 filled with a cold storage material 121 and arranged in the cylinder internal space 110 so as to be reciprocally movable in the cylinder internal space 110 in a first direction which is an axial direction of the cylinder member 11; A driving force source (electric motor 14) having a rotating shaft 141 that outputs rotational power; The rotary shaft 141 is connected to the rotary shaft 141, and the axis C of the rotary shaft 141 moves in accordance with the rotation of the rotary shaft 141. M A crankshaft 15 having an eccentric part (crank pin 152) that rotates eccentrically around a center of the crankshaft 15, a Scotch yoke 16 including a frame-shaped portion 161 formed in a frame shape to define an inner space, into which the eccentric portion (crank pin 152) of the crankshaft 15 is inserted, and a first rod portion 162 having one end connected to the frame-shaped portion 161 and the other end connected to the displacer 12, wherein the eccentric portion (crank pin 152) rotates eccentrically within the inner space to cause the frame-shaped portion 161 and the first rod portion 162 to reciprocate in the first direction, thereby causing the displacer 12 to reciprocate in the first direction within the cylinder internal space 110; a housing 13 disposed on the high temperature end side of the cylinder member 11 and having a space formed therein in which the Scotch yoke 16 is disposed; a pressure oscillation mechanism 17 that alternately applies the high and low pressures generated by the compressor 18 to the cylinder space 110 in response to the reciprocating movement of the displacer 12 so that the volume and pressure of the working gas in the low temperature end and the high temperature end of the cylinder space 110 vary according to a GM cycle; and a biasing member (a first spring 21 and a second spring 22) that elastically biases the displacer 12 in a direction from the high temperature end toward the low temperature end of the cylinder member 11 in the first direction.

[0057] In this case, the pressure vibration mechanism 17 is a high pressure passage 136 communicating a high pressure port 181 of the compressor 18 with the high temperature end of the cylinder space 110; a high-pressure valve 19 that is provided on the high-pressure path 136 and is configured to be switchable between an open state that opens the high-pressure path 136 and a closed state that blocks the high-pressure path 136; a low-pressure path (first low-pressure path 137) that communicates between a low-pressure port 182 of the compressor 18 and the high-temperature end of the cylinder internal space 110 via an internal space of the housing 13; a low-pressure valve 20 that is provided on the low-pressure path (first low-pressure path 137) and is configured to be switchable between an open state that opens the low-pressure path (first low-pressure path 137) and a closed state that blocks the low-pressure path, The high pressure valve 19 and the low pressure valve 20 are switched between open and closed states so that the volume and pressure of the working gas in the low temperature end and the high temperature end of the in-cylinder space 110 vary according to a GM cycle.

[0058] In the GM refrigerator 10 according to this embodiment, the load torque, which is the torque applied from outside the driving force source (electric motor 14) to the rotating shaft 141 of the driving force source (electric motor 14), is a maximum value caused by a factor other than the biasing member (first spring 21 and second spring 22) while the displacer 12 moves in the cylinder inner space 110 from the high temperature end side to the low temperature end side. The biasing member (first spring 21 and second spring 22) of the GM refrigerator 10 is configured to elastically bias the displacer 12 from the high temperature end side to the low temperature end side. In other words, the spring torque, which is the torque caused by the biasing force of the biasing member (first spring 21 and second spring 22), acts in a direction to reduce the load torque while the displacer 12 moves from the high temperature end side to the low temperature end side (it can also be said that the spring torque acts to assist the rotation of the rotating shaft 141 caused by the driving torque). This makes it possible to reduce the maximum value of the load torque. Therefore, the drive torque required for electric motor 14 can be reduced, and therefore, compared to a configuration that does not include biasing members (first spring 21 and second spring 22), a smaller, lighter electric motor 14 with smaller drive torque can be used. As a result, the GM refrigerator 10 can be made smaller and lighter.

[0059] Furthermore, according to this embodiment, the elastic biasing force of the biasing members (first spring 21 and second spring 22) can prevent or suppress rattling between the bearing 33 attached to the crank pin 152 of the crankshaft 15 and the frame-shaped portion 161 of the Scotch yoke 16. The elastic biasing force of the biasing member (second spring 22) can also prevent or suppress rattling at the joint between the Scotch yoke 16 and the base plate 31. As a result, wear of each member at these joints can be prevented or suppressed.

[0060] The GM cycle of the GM refrigerator 10 according to this embodiment includes a high-pressure transfer stroke in which the compressor 18 moves the displacer 12 from the low-temperature end side toward the high-temperature end side while maintaining the pressure in the high-temperature end of the cylinder internal space 110 at a pressure higher than the internal pressure of the housing 13, and a low-pressure transfer stroke in which the compressor 18 moves the displacer 12 from the high-temperature end side toward the low-temperature end side while sucking in the working gas in the cylinder internal space 110 via the internal space of the housing 13, The absolute value of the torque (spring torque) applied to the rotating shaft 141 by the biasing force of the biasing member (first spring 21 and second spring 22) is greater than 0 and less than the absolute value of "the difference between the maximum value of the torque due to loads other than the biasing force of the biasing member (first spring 21 and second spring 22) during the high-pressure transfer stroke and the maximum value of the torque due to loads other than the biasing force of the biasing member (first spring 21 and second spring 22) during the low-pressure transfer stroke."

[0061] As described above, the torque (spring torque) by the biasing members (first spring 21 and second spring 22) acts in a direction to increase the load torque in the high-pressure transfer stroke. Therefore, in a configuration in which the biasing members (first spring 21 and second spring 22) are arranged, the maximum value of the load torque in the high-pressure transfer stroke is larger than in a configuration in which the biasing members (first spring 21 and second spring 22) are not arranged. Therefore, if the biasing force of the biasing members (first spring 21 and second spring 22) is excessively large, the maximum value T3 of the load torque in the high-pressure transfer stroke increased by the spring torque may become equal to or greater than the maximum value T1 of the load torque in the low-pressure transfer stroke when it is not reduced by the spring torque.

[0062] Therefore, in this embodiment, the biasing force of the biasing members (first spring 21 and second spring 22) is specified so that the absolute value of the spring torque is less than the absolute value of the pre-reduction load torque difference ΔT. With this configuration, the maximum value T3 of the load torque in the high-pressure transfer stroke increased by the spring torque can be prevented from becoming equal to or greater than the maximum value T2 of the load torque in the low-pressure transfer stroke when it is not reduced by the spring torque (i.e., the maximum value T2 of the load torque in a configuration in which the biasing members (first spring 21 and second spring 22) are not disposed). This makes it possible to reduce the maximum value of the load torque. However, in order to achieve the effect of reducing the maximum value of the load torque, the absolute value of the spring torque is greater than 0.

[0063] In addition, the biasing force of the biasing member (first spring 21 and second spring 22) is preferably specified so that the absolute value of the spring torque is approximately 0.5 times the absolute value of the load torque difference before reduction ΔT. When the absolute value of this spring torque is approximately 0.5 times the absolute value of the load torque difference before reduction ΔT, the "maximum value T3 of the load torque in the high-pressure transfer stroke increased by the spring torque" and the "maximum value T4 of the load torque in the low-pressure transfer stroke reduced by the spring torque" can be made approximately the same. Therefore, the reduction amount of the "maximum value T4 of the load torque in the low-pressure transfer stroke reduced by the spring torque" can be maximized within a range in which the "maximum value T3 of the load torque in the high-pressure transfer stroke increased by the spring torque" does not exceed the "maximum value T4 of the load torque in the low-pressure transfer stroke reduced by the spring torque". In other words, the reduction amount of the load torque can be maximized.

[0064] In addition, in a configuration in which multiple biasing members (first spring 21 and second spring 22) are arranged in GM refrigerator 10, the biasing force of each biasing member (first spring 21 and second spring 22) is specified so that the "total value of the spring torque due to the biasing forces of the multiple biasing members (first spring 21 and second spring 22)" is within the above-mentioned range.

[0065] The GM refrigerator 10 according to this embodiment has: A biasing member accommodating member (spring housing 133) is provided on the opposite side of the housing 13 to the cylinder member 11, The Scotch yoke 16 includes a second rod portion 163, one end of which projects from the housing 13 toward the opposite side to the cylinder member 11 and the other end of which is connected to the frame portion 161 of the Scotch yoke 16. The biasing member (first spring 21 and second spring 22) is accommodated inside the biasing member accommodating member (spring housing 133) and includes a first elastic compression coil spring (first spring 21) that elastically biases the second rod portion 163 of the Scotch yoke 16 in the first direction from the high temperature end toward the low temperature end of the cylinder member 11.

[0066] According to this configuration, the mounting structure of the first elastic compression coil spring (first spring 21) is simpler than a configuration in which the second elastic compression coil spring (second spring 22) is disposed inside the housing 13 or inside the cylinder member 11. In addition, the first elastic compression coil spring (first spring 21) can be disposed without changing the configuration of the cylinder member 11 and the housing body 131.

[0067] The biasing member (first spring 21 and second spring 22) includes a second elastic compression coil spring (second spring 22) interposed between the housing 13 and the high-temperature end of the displacer 12 and disposed around the first rod portion 162.

[0068] According to this configuration, no space is required outside the housing 13 or the cylinder member 11 to arrange the second elastic compression coil spring (second spring 22), so the second elastic compression coil spring (second spring 22) can be arranged without increasing the size of the housing 13 or the cylinder member 11 (i.e., without increasing the size of the GM refrigerator 10).

[0069] Although the embodiments of the present invention have been described above, the present invention should not be limited to the above embodiments. For example, the above embodiments show a single-stage GM refrigerator 10, but the present invention is also applicable to a two-stage refrigerator. Furthermore, the position and number of the biasing members are not limited. The point is that the GM refrigerator 10 may be configured to include "a biasing member that elastically biases the displacer 12 from the high temperature end side toward the low temperature end side."

[0070] In the above embodiment, the low temperature end is located on the lower side and the high temperature end is located on the upper side, but the present invention is not limited to such a configuration. The orientation of the cylinder member 11 is not limited.

[0071] In the above embodiment, the first rod portion 162 of the Scotch yoke 16 and the displacer 12 are connected (coupled) via the base plate 31, but the present invention is not limited to such a configuration. For example, the first rod portion 162 of the Scotch yoke 16 and the displacer 12 may be directly connected (the base plate 31 may not be provided).

[0072] Furthermore, in the above embodiment, the operation of the GM refrigerator 10 is described as being such that the period during which the phase θ transitions from 0° to 180° is a high-pressure transfer stroke, when the phase θ is 180° (when the displacer 12 is located at the second dead center) is an expansion stroke, the period during which the phase θ transitions from 180° to 360° is a low-pressure transfer stroke, and when the phase θ is 0° (=360°) (when the displacer 12 is located at the first dead center), but is not limited to an operation in which the expansion stroke and compression stroke are performed at a single point where the phase θ is 180° and 0° (=360°), respectively.

[0073] For example, the period during which the phase θ transitions from 0° to 160° is a high-pressure transfer stroke, the period during which the phase θ transitions from 160° to 180° is an expansion stroke (e.g., a stroke in which the high-pressure valve is switched to a closed state when the phase θ is 160°, and the low-pressure valve is switched to an open state when the phase θ is 170°), the period during which the phase θ transitions from 180° to 340° is a low-pressure transfer stroke, and the period during which the phase θ transitions from 340° to 0° (=360°) is a compression stroke (e.g., a stroke in which the low-pressure valve is switched to a closed state when the phase θ is 340°, and the high-pressure valve is switched to an open state when the phase θ is 350°), that is, the expansion stroke and compression stroke may each have a predetermined phase width near the second dead center and the first dead center, respectively. In this way, even if a phase width is provided in the expansion stroke and the compression stroke near the second dead center and the first dead center, respectively, the position of the displacer 12, which is connected to the Scotch yoke 16 and moves back and forth, changes in accordance with the cosine function of time. Therefore, the position change of the displacer 12 due to the phase change near the second dead center and the first dead center is small, and the displacer 12 is positioned approximately at the second dead center and the first dead center. Therefore, the load torque during one cycle becomes approximately the same as the load torque during one cycle in the above embodiment, and the same effect as in the above embodiment can be obtained. [Explanation of symbols]

[0074] 10...GM refrigerator, 11...cylinder member, 12...displacer, 13...housing, 14...electric motor, 141...rotating shaft, 15...crankshaft, 152...crankpin, 16...scotch yoke, 17...pressure oscillation mechanism, 18...compressor, 21...first spring, 22...second spring, 110...cylinder space, 111...back space, 112...expansion space, 130...housing space, 161...frame-shaped portion, 162...first rod portion, 163...second rod portion

Claims

1. a cylinder member having a high temperature end on one end side and a low temperature end on the other end side, and an internal space of the cylinder that is filled with a working gas; a displacer filled with a cold storage material and disposed in the cylinder space so as to be reciprocally movable in a first direction, which is an axial direction of the cylinder member; A driving force source having a rotating shaft that outputs rotational power; a crankshaft having an eccentric portion connected to the rotary shaft and eccentrically rotating about an axis of the rotary shaft as the rotary shaft rotates; a Scotch yoke including: a frame-shaped portion formed in a frame shape to define an inner space, into which the eccentric portion of the crankshaft is inserted; and a first rod portion having one end connected to the frame-shaped portion and the other end connected to the displacer, wherein the eccentric rotation of the eccentric portion within the inner space causes the frame-shaped portion and the first rod portion to reciprocate in the first direction, thereby reciprocating the displacer in the first direction within the cylinder internal space; a housing disposed on the high temperature end side of the cylinder member, the housing defining a space therein in which the Scotch yoke is disposed; a pressure oscillation mechanism that alternately applies the high pressure and the low pressure generated by the compressor to the cylinder space in association with the reciprocating movement of the displacer so that the volume and pressure of the working gas in the low temperature end and the high temperature end of the cylinder space fluctuate according to a GM cycle; a biasing member that elastically biases the displacer in a direction from the high temperature end toward the low temperature end of the cylinder member in the first direction; Equipped with a GM refrigerator.

2. 2. The GM refrigerator according to claim 1, The pressure vibration mechanism includes: a high-pressure passage communicating a high-pressure port of the compressor with the high-temperature end of the cylinder interior space; a high-pressure valve provided on the high-pressure path and configured to be switchable between an open state that opens the high-pressure path and a closed state that blocks the high-pressure path; a low pressure passage that communicates a low pressure port of the compressor and the high temperature end of the cylinder space via an internal space of the housing; a low pressure valve that is provided on the low pressure path and is configured to be switchable between an open state that opens the low pressure path and a closed state that blocks the low pressure path, The high pressure valve and the low pressure valve are switched between open and closed states such that the volume and pressure of the working gas in the low temperature end and the high temperature end of the in-cylinder space fluctuate according to a GM cycle. GM refrigerator.

3. 3. The GM refrigerator according to claim 1 or 2, The GM cycle includes a high-pressure transfer stroke in which the compressor moves the displacer from the low-temperature end side toward the high-temperature end side while maintaining a pressure in the high-temperature end of the cylinder space higher than an internal pressure of the housing, and a low-pressure transfer stroke in which the compressor moves the displacer from the high-temperature end side toward the low-temperature end side while sucking in the working gas in the cylinder space via an internal space of the housing, a magnitude of an absolute value of a torque applied to the rotating shaft by the biasing force of the biasing member is greater than 0 and is less than a difference between a maximum value of a torque due to a load other than the biasing force of the biasing member in the high-pressure transfer stroke and a maximum value of a torque due to a load other than the biasing force of the biasing member in the low-pressure transfer stroke.

4. 4. The GM refrigerator according to claim 3, a biasing member accommodating member provided on the opposite side of the housing to the cylinder member, the Scotch yoke includes a second rod portion having one end protruding from the housing toward the opposite side to the cylinder member and the other end connected to the frame portion of the Scotch yoke; the biasing member includes a first elastic compression coil spring that is accommodated inside the biasing member accommodating member and elastically biases the second rod portion of the Scotch yoke in a direction from the high temperature end toward the low temperature end of the cylinder member in the first direction.

5. 4. The GM refrigerator according to claim 3, the biasing member includes a second elastic compression coil spring interposed between the housing and the high temperature end of the displacer and disposed around the first rod portion.

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