JP2021169874A - Fitting structure for cryogenic refrigeration machine and cryogenic refrigeration machine - Google Patents

Abstract

To provide preferable thermal contact between a cryogenic refrigeration machine and the fitting structure thereof.SOLUTION: A fitting structure 30 for a cryogenic refrigeration machine 10 includes: a first-stage heat transfer stage 36 coming into contact with a first-stage cooling stage 20 of the cryogenic refrigeration machine 10 or released from the contact with the movement of the cryogenic refrigeration machine 10; and a heat transfer structure 50 installed so as to be elastically displaceable relative to the first-stage heat transfer stage 36 and coming into contact with a second surface that is different from a first surface of the first-stage cooling stage 20 when the first-stage heat transfer stage 36 comes into contact with the first surface of the first-stage cooling stage 20.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cryogenic refrigerator mounting structure and a cryogenic refrigerator.

Conventionally, it is known that a cold head of a cryogenic refrigerator is attached to a cryogenic vacuum container such as a cryostat via a sleeve. An object to be cooled, such as a superconducting coil, is housed in the cryogenic vacuum vessel, and the object to be cooled is thermally coupled to the sleeve. By bringing the cold head into contact with the sleeve, the cryogenic refrigerator can cool the object to be cooled through the sleeve.

During the long-term operation of the cryogenic chiller, maintenance of the cryogenic chiller may be required on a regular basis. The operator can pull the cold head out of the sleeve somewhat to break the contact between the cold head and the sleeve and perform maintenance on the cryogenic refrigerator. The cryogenic refrigerator is heated to a temperature convenient for maintenance work, such as room temperature, and is recooled after the work is completed. By releasing the contact of the cold head, the object to be cooled can be kept at a low temperature. Therefore, the recooling time of the object to be cooled can be shortened as compared with the case where the object to be cooled is heated to room temperature together with the cryogenic refrigerator to perform maintenance on the cryogenic refrigerator, and the time required for maintenance is shortened. be able to.

Japanese Unexamined Patent Publication No. 2013-160393

The present inventor examined the above-mentioned mounting structure and recognized the following problems. Thermal contact between the cold head and the sleeve is achieved by pressing the cold head against the sleeve. This pressing force determines the contact pressure between the cold head and the sleeve. Contact pressure affects thermal resistance. Insufficient contact pressure leads to an increase in thermal resistance, which causes a temperature difference. If this temperature difference is large, the cooling temperature of the object to be cooled may not be sufficiently lower than the temperature that can be achieved by the cryogenic refrigerator. Cryogenic chillers with greater freezing capacity may have to be employed to avoid poor cooling of the object to be cooled.

In many cases, a two-stage cryogenic refrigerator is used, with a one-stage cooling stage cooling the radiation shield that thermally protects the object to be cooled, and a two-stage cooling stage cooling the object to be cooled. The pressing force from the cold head to the sleeve is structurally distributed to the contact pressure in the one-stage cooling stage and the contact pressure in the two-stage cooling stage. Therefore, there is a trade-off between the thermal resistance of the first and second stages. From the viewpoint of giving priority to avoiding poor cooling of the object to be cooled, it is desired to further increase the contact pressure in the two-stage cooling stage. However, as a result, the contact pressure in the one-stage cooling stage becomes small, the thermal resistance in the one-stage becomes high, and there is a concern that the cooling of the radiation shield will be insufficient this time.

One exemplary object of an aspect of the invention is to provide good thermal contact between a cryogenic refrigerator and its mounting structure.

According to certain aspects of the invention, a cryogenic refrigerator mounting structure is provided. The mounting structure is provided with a heat transfer stage that comes into contact with or is released from contact with the cooling stage of the ultra-low temperature refrigerator by moving the ultra-low temperature refrigerator, and a heat transfer stage that is elastically displaceable with respect to the heat transfer stage. It is provided with a heat transfer structure that contacts a second surface different from the first surface of the cooling stage when it comes into contact with the first surface of the cooling stage.

According to certain aspects of the invention, a cryogenic refrigerator mounting structure is provided. The cryogenic refrigerator is a two-stage cryogenic refrigerator. The mounting structure is provided with a one-stage heat transfer stage that comes into contact with or is released from contact with the one-stage cooling stage of the ultra-low temperature refrigerator by moving the ultra-low temperature refrigerator, and a one-stage heat transfer stage that is elastically displaceable with respect to the one-stage heat transfer stage. It is provided with a heat transfer structure that contacts a second surface different from the first surface of the one-stage cooling stage when the heat transfer stage contacts the first surface of the one-stage cooling stage.

According to an aspect of the present invention, the ultra-low temperature chiller is provided with a cooling stage and a cooling stage which are brought into contact with or released from the heat transfer stage provided in the mounting structure of the ultra-low temperature chiller by the movement of the ultra-low temperature chiller. On the other hand, it is provided so as to be elastically displaceable, and includes a heat transfer structure that contacts a second surface different from the first surface of the heat transfer stage when the cooling stage contacts the first surface of the heat transfer stage.

It should be noted that any combination of the above components or components and expressions of the present invention that are mutually replaced between methods, devices, systems, and the like are also effective as aspects of the present invention.

According to the present invention, good thermal contact can be provided between the cryogenic refrigerator and its mounting structure.

It is the schematic for demonstrating the mounting structure which concerns on embodiment. It is the schematic for demonstrating the mounting structure which concerns on embodiment. It is a partially enlarged view which shows the heat transfer structure shown in FIG. It is a partially enlarged view which shows the heat transfer structure shown in FIG. It is a figure which shows roughly the AA line cross section of the heat transfer structure shown in FIG. It is a figure which shows typically the modification of the heat transfer structure which concerns on embodiment. It is a figure which shows typically the other modification of the heat transfer structure which concerns on embodiment. It is a figure which shows typically the other modification of the heat transfer structure which concerns on embodiment. 9 (a) and 9 (b) are diagrams schematically showing other modifications of the heat transfer structure according to the embodiment. 10 (a) and 10 (b) are schematic views for explaining the cryogenic refrigerator according to the embodiment.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description and drawings, the same or equivalent components, members, and processes are designated by the same reference numerals, and duplicate description will be omitted as appropriate. The scales and shapes of the illustrated parts are set for convenience of explanation and are not interpreted in a limited manner unless otherwise specified. Embodiments are exemplary and do not limit the scope of the invention in any way. Not all features and combinations thereof described in the embodiments are essential to the invention.

1 and 2 are schematic views for explaining a mounting structure according to an embodiment. FIG. 1 shows a state in which the cryogenic refrigerator 10 and an object to be cooled 90 such as a superconducting coil are disconnected, and FIG. 2 shows a state in which the two are thermally coupled. It is shown.

The cryogenic refrigerator 10 is, in this embodiment, a two-stage Gift-McMahon (GM) refrigerator. The cryogenic refrigerator 10 includes a compressor 12 and a two-stage cold head 14.

The compressor 12 is configured to recover the refrigerant gas of the cryogenic refrigerator 10 from the cold head 14, pressurize the recovered refrigerant gas, and supply the refrigerant gas to the cold head 14 again. The cold head 14 is also called an expander, and can generate cold by adiabatically expanding the supplied refrigerant gas in an internal expansion chamber. The refrigeration cycle of the cryogenic refrigerator 10 (eg, GM) is performed by circulating the refrigerant gas between the compressor 12 and the cold head 14 with an appropriate combination of pressure fluctuation and volume fluctuation of the refrigerant gas in the cold head 14. A cycle) is configured to cool each cooling stage of the cold head 14 to the desired cryogenic temperature. The refrigerant gas, also referred to as a working gas, is usually helium gas, but other suitable gases may be used.

The cold head 14 includes a cold head flange 16, a one-stage cylinder 18, a one-stage cooling stage 20, a two-stage cylinder 22, and a two-stage cooling stage 24, which are arranged coaxially along the central axis of the cold head 14. .. The one-stage cylinder 18 connects the cold head flange 16 to the one-stage cooling stage 20, and the two-stage cylinder 22 connects the one-stage cooling stage 20 to the two-stage cooling stage 24. The one-stage cooling stage 20 and the two-stage cooling stage 24 are made of a highly thermally conductive metal such as copper (for example, pure copper) or other thermally conductive material. The one-stage cylinder 18 and the two-stage cylinder 22 are made of a metal such as stainless steel. The thermal conductivity of the heat conductive material forming the cooling stage is higher than the thermal conductivity of the material forming the cylinder.

A drive unit 17 is attached to the cold head flange 16. The drive unit 17 includes a motor that reciprocates the one-stage displacer and the two-stage displacer housed in the one-stage cylinder 18 and the two-stage cylinder 22, respectively, in the axial direction. The drive unit 17 also houses a pressure switching valve that is driven by the motor in synchronization with the displacer. The pressure switching valve is configured to periodically switch between the reception of the high-pressure refrigerant gas and the delivery of the low-pressure refrigerant gas to the cold head 14. The compressor 12, the cold head flange 16, and the drive unit 17 are arranged in the ambient environment 27.

The mounting structure 30 of the cryogenic refrigerator 10 is an instrument for mounting the cryogenic refrigerator 10 in a vacuum container 26, for example, a cryogenic vacuum container such as a cryostat. The mounting structure 30 is also referred to as a cold head accommodating sleeve, or simply a sleeve. The mounting structure 30 is installed in the vacuum vessel 26 so as to form an airtight region 28 isolated from the surrounding environment 27 between the cold head 14 and the mounting structure 30. The ambient environment 27 is, for example, an atmospheric pressure environment at room temperature. The airtight region 28 may be evacuated to vacuum or may be filled with an inert gas such as helium gas that does not liquefy at extremely low temperatures. Further, the mounting structure 30 is installed in the vacuum vessel 26 so as to partition the vacuum region 29 in the vacuum vessel 26 in combination with the vacuum vessel 26.

The mounting structure 30 may be provided to the customer by the manufacturer of the cryogenic refrigerator 10 together with the cryogenic refrigerator 10. It can be said that the cooling device for cooling the object to be cooled 90 is composed of the cryogenic refrigerator 10 and the mounting structure 30.

The mounting structure 30 is also configured in a two-stage manner corresponding to the cold head 14. The mounting structure 30 includes a sleeve flange 32, a one-stage sleeve body 34, a one-stage heat transfer stage 36, a two-stage heat transfer stage 38, and a two-stage heat transfer stage 40, which are arranged coaxially along the central axis of the cold head 14. Has been done.

As an example, the sleeve flange 32 is fixed to an opening formed in the top plate of the vacuum container 26, and the mounting structure 30 extends into the vacuum container 26 from this opening. Further, a cold head flange 16 is attached to the sleeve flange 32 by a fastening member 33 such as a bolt. When the cold head flange 16 and the sleeve flange 32 are fastened, the one-stage cooling stage 20 and the two-stage cooling stage 24 are pressed against the one-stage heat transfer stage 36 and the two-stage heat transfer stage 40, respectively. The sleeve flange 32 has an opening for receiving the cold head 14 in the radial direction with respect to the fastening member 33, and the cold head flange 16 is in contact with the inner peripheral surface of the opening.

When the cold head flange 16 and the sleeve flange 32 are released from being fastened by the fastening member 33, the cold head flange 16 is axially slidable with respect to the sleeve flange 32, whereby the cold head 14 can be slid. It is movable in the axial direction (vertical direction in FIGS. 1 and 2) with respect to the mounting structure 30. The movable range is, for example, within several cm, for example, about 2 to 3 cm. The operator manually, uses an auxiliary device such as a hydraulic jack, or activates a powered lifting device, if connected to it, to the cold head in this range of motion. 14 can be moved up and down in the axial direction.

A sealing member 42 such as an O-ring is sandwiched between the cold head flange 16 and the sleeve flange 32. The seal member 42 is arranged in a peripheral groove formed on the inner peripheral surface of the opening of the sleeve flange 32. Since the seal member 42 is provided, the airtight region 28 is isolated from the surrounding environment 27 even if the cold head 14 is moved in the axial direction within the above-mentioned movable range with respect to the mounting structure 30.

The one-stage sleeve body 34 connects the sleeve flange 32 to the one-stage heat transfer stage 36, and the two-stage sleeve body 38 connects the one-stage heat transfer stage 36 to the two-stage heat transfer stage 40. The one-stage sleeve body 34 and the two-stage sleeve body 38 are arranged so as to surround the one-stage cylinder 18 and the two-stage cylinder 22, respectively. At the center of the one-stage heat transfer stage 36, an opening is provided to connect the internal space of the one-stage sleeve body 34 to the internal space of the two-stage sleeve body 38. The two-stage cylinder 22 and the two-stage cooling stage 24 of the cold head 14 are inserted into the internal space of the two-stage sleeve body 38 through this opening. The one-stage heat transfer stage 36 and the two-stage heat transfer stage 40 are formed of a high heat transfer metal such as copper (for example, pure copper) or other heat transfer material. The one-stage sleeve body 34 and the two-stage sleeve body 38 are made of a metal such as stainless steel. The thermal conductivity of the heat conductive material forming the heat transfer stage is higher than the thermal conductivity of the material forming the sleeve body.

Therefore, the one-stage heat transfer stage 36 of the mounting structure 30 comes into contact with or is released from the one-stage cooling stage 20 of the cold head 14 by the movement of the cold head 14 of the cryogenic refrigerator 10. Similarly, the two-stage heat transfer stage 40 of the mounting structure 30 comes into contact with or is released from the two-stage cooling stage 24 by the movement of the cold head 14.

The mounting structure 30 includes a heat transfer structure 50 provided so as to be elastically displaceable with respect to the one-stage heat transfer stage 36, which will be described in detail later. The heat transfer structure 50 can be elastically displaced with respect to the one-stage heat transfer stage 36 in a direction perpendicular to the movement of the cold head 14 (that is, a radial direction perpendicular to the axial direction). The heat transfer structure 50 is attached to the one-stage heat transfer stage 36. The heat transfer structure 50 is arranged so that when the one-stage heat transfer stage 36 comes into contact with the first surface of the one-stage cooling stage 20, it comes into contact with a second surface different from the first surface of the one-stage cooling stage 20. In this embodiment, the first surface is the bottom surface 20a of the one-stage cooling stage 20, and the second surface is the side surface 20b of the one-stage cooling stage 20 at an angle with the bottom surface 20a of the one-stage cooling stage 20.

A radiation shield 92 is thermally coupled to the outer surface of the one-stage heat transfer stage 36 exposed to the vacuum region 29. The radiation shield 92 is arranged so as to surround the object to be cooled 90 in order to thermally protect the object 90 to be cooled. Only a part of the radiation shield 92 is shown in FIGS. 1 and 2. The radiation shield 92 may be attached directly to the one-stage heat transfer stage 36, or may be connected via a rigid or flexible heat transfer member. Another object to be cooled may be thermally bonded to the one-stage heat transfer stage 36 together with or instead of the radiation shield 92. Further, the object to be cooled 90 is thermally coupled to the outer surface of the two-stage heat transfer stage 40 exposed in the vacuum region 29. The object to be cooled 90 may be directly attached to the two-stage heat transfer stage 40, or may be connected via a rigid or flexible heat transfer member.

As shown in FIG. 1, in a state where the cold head 14 and the mounting structure 30 are released from thermal contact, the cold head 14 is located at, for example, the upper end of the movable range. At this time, the one-stage cooling stage 20 is physically separated from the one-stage heat transfer stage 36 and the heat transfer structure 50, and the two-stage cooling stage 24 is physically separated from the two-stage heat transfer stage 40. The object to be cooled 90 and the radiation shield 92 are not cooled. Is the thermal effect of the cold head 14 on the object to be cooled 90 and the radiant shield 92 limited even if the temperature of the cold head 14 is raised to a temperature higher than that of the object to be cooled 90 and the radiant shield 92, for example, room temperature? , Can be ignored. The object to be cooled 90 and the radiation shield 92 are maintained at a cryogenic temperature.

As shown in FIG. 2, when the cold head 14 and the mounting structure 30 are in thermal contact with each other, the cold head 14 is located at the lower end of the movable range. At this time, the one-stage cooling stage 20 physically contacts the one-stage heat transfer stage 36 and the heat transfer structure 50, whereby the one-stage cooling stage 20 passes through the one-stage heat transfer stage 36 and the heat transfer structure 50 to the radiation shield 92. In thermal contact with. At the same time, the two-stage cooling stage 24 physically contacts the two-stage heat transfer stage 40, whereby the two-stage cooling stage 24 makes thermal contact with the object to be cooled 90 via the two-stage heat transfer stage 40. In this way, the cryogenic refrigerator 10 can cool the object to be cooled 90 and the radiation shield 92. The radiation shield 92 can be cooled to, for example, 30K to 80K (usually 30K to 50K, for example 40K), and the object to be cooled 90 can be cooled to, for example, 3K to 20K (usually 3K to 4K).

3 and 4 are partially enlarged views showing the heat transfer structure 50 shown in FIGS. 1 and 2, respectively. FIG. 3 shows a state in which the contact between the one-stage cooling stage 20 and the one-stage heat transfer stage 36 is released, and FIG. 4 shows a state in which the one-stage cooling stage 20 and the one-stage heat transfer stage 36 are in contact with each other. FIG. 5 is a diagram schematically showing a cross section taken along line AA of the heat transfer structure 50 shown in FIG. For ease of understanding, the two-stage cylinder 22 of the cold head 14 is shown by a broken line in FIG.

The heat transfer structure 50 includes a plurality of heat transfer pieces 52, each of which is elastically displaceable with respect to the one-stage heat transfer stage 36. When the one-stage heat transfer stage 36 comes into contact with the first surface (for example, the bottom surface 20a) of the one-stage cooling stage 20, each of the plurality of heat transfer pieces 52 comes into contact with the second surface (for example, the side surface 20b) of the one-stage cooling stage 20.

The plurality of heat transfer pieces 52 are attached along the outer periphery of the one-stage heat transfer stage 36 so as to surround the one-stage cooling stage 20 when the one-stage cooling stage 20 of the cold head 14 is inserted. As shown in FIG. 5, two heat transfer pieces 52 adjacent to each other in the circumferential direction are separated by a slit 54. Further, as shown in FIGS. 3 and 4, the lower end of each heat transfer piece 52 is fixed to the one-stage heat transfer stage 36, from which each heat transfer piece 52 extends upward in the axial direction. Therefore, the upper end of each heat transfer piece 52 can be elastically displaced in the radial direction with respect to the one-stage heat transfer stage 36. Each heat transfer piece 52 may be a strip-shaped or wire-shaped heat transfer element extending in the axial direction.

Like the one-stage heat transfer stage 36, the heat transfer piece 52 is made of a high heat transfer metal such as copper (for example, pure copper) or other heat transfer material. Each heat transfer piece 52 and the one-stage heat transfer stage 36 are structurally integrated by mechanical joining such as screws, and are thermally coupled. Alternatively, the heat transfer piece 52 may be fixed to the one-stage heat transfer stage 36 by using metallurgical joining such as soldering or other appropriate joining techniques.

In FIG. 5, 12 heat transfer pieces 52 are shown as an example, but the number of heat transfer pieces 52 may be larger or smaller than this. Further, in this embodiment, the shape and dimensions (height, width, thickness) of each heat transfer piece 52 are the same, but this is not essential, and the shape or size of at least one heat transfer piece 52. May be different from at least one heat transfer piece 52.

As shown in FIG. 3, the inlet diameter (D1) of the heat transfer structure 50, that is, the radial distance between the upper ends of the two opposing heat transfer pieces 52 is equal to the diameter (D2) of the end face of the one-stage cooling stage 20. Or it may be slightly smaller. The dimensional tolerances of these two diameters (D1 and D2) may be set so that when the one-stage cooling stage 20 is inserted into the heat transfer structure 50, it comes into contact with the heat transfer piece 52 while sliding. The radial inward surface of each heat transfer piece 52 in contact with the side surface 20b of the one-stage cooling stage 20 may be parallel to the side surface 20b of the one-stage cooling stage 20.

The upper end surface of each heat transfer piece 52 may be a tapered surface 56. The tapered surface 56 connects the outer peripheral surface of each heat transfer piece 52 to the inner peripheral surface, and is inclined inward in the radial direction and downward in the axial direction. As a result, when the one-stage cooling stage 20 is inserted into the heat transfer structure 50, the outer periphery of the end surface of the one-stage cooling stage 20 first abuts on the tapered surface 56. The tapered surface 56 acts as a guide surface for guiding the one-stage cooling stage 20, whereby the one-stage cooling stage 20 is easily accepted by the heat transfer structure 50. Also, even if there is some misalignment between the cold head 14 and the mounting structure 30, the one-stage cooling stage 20 can be guided by the tapered surface 56 and inserted into the heat transfer structure 50.

The operation of the cryogenic refrigerator 10 and the mounting structure 30 having the above configuration will be described. When the timing at which maintenance of the cryogenic refrigerator 10 is permitted comes, the cooling operation of the cryogenic refrigerator 10 is stopped. At this time, as shown in FIGS. 2 and 4, the one-stage cooling stage 20 is in physical and thermal contact with the one-stage heat transfer stage 36 and the heat transfer structure 50, and the two-stage cooling stage 24 is a two-stage heat transfer stage. It is in physical and thermal contact with 40.

When the operator operates the fastening member 33, the fastening between the cold head flange 16 and the sleeve flange 32 is released. The cold head 14 is then pulled up somewhat from the mounting structure 30. Since the sealing member 42 is provided between the cold head flange 16 and the sleeve flange 32, the isolation of the airtight region 28 from the surrounding environment 27 is maintained.

Thus, as shown in FIGS. 1 and 3, the one-stage cooling stage 20 is physically separated from the one-stage heat transfer stage 36 and the heat transfer structure 50 and becomes thermally non-contact. The two-stage cooling stage 24 is physically separated from the two-stage heat transfer stage 40 and becomes thermally non-contact. The temperature of the cold head 14 can be raised while keeping the temperature of the object to be cooled 90 and the radiation shield 92 at low temperatures.

Maintenance of the cryogenic refrigerator 10 is performed. The drive unit 17 and the displacer of the cold head 14 are removed from the cold head 14. The outer structure of the cold head 14, that is, the cold head flange 16, the one-stage cylinder 18, the one-stage cooling stage 20, the two-stage cylinder 22, and the two-stage cooling stage 24 are directly mounted on the mounting structure 30. Then, the maintained (or new) drive unit 17 and the displacer are attached to the cold head 14. Then, the cooling operation of the cryogenic refrigerator 10 is restarted.

The operator pushes the cold head 14 back into the mounting structure 30. When the one-stage cooling stage 20 is inserted in the axial direction and slides in the axial direction with respect to each heat transfer piece 52, the one-stage cooling stage 20 pushes each heat transfer piece 52 radially outward (arrow 58 in FIG. 4). Elastically bend to spread. The radial inward surface of each heat transfer piece 52 follows the side surface 20b of the one-stage cooling stage 20, and the one-stage cooling stage 20 and each heat transfer piece 52 elastically follow the side surface 20b of the one-stage cooling stage 20 and as shown in FIGS. 2 and 4. Face contact. At the same time, the bottom surface 20a of the one-stage cooling stage 20 comes into contact with and pressed against the one-stage heat transfer stage 36.

Then, the cold head flange 16 and the sleeve flange 32 are fastened by the fastening member 33. The one-stage cooling stage 20 physically and thermally contacts the one-stage heat transfer stage 36 and the heat transfer structure 50, and the two-stage cooling stage 24 physically and thermally contacts the two-stage heat transfer stage 40. It returns to the state shown in FIG.

Therefore, according to the cryogenic refrigerator 10 and the mounting structure 30 according to the embodiment, the thermal contact with the mounting structure 30 is released by the movement of the cold head 14, and the object to be cooled 90 and the radiation shield 92 are kept at a low temperature. The temperature of the cold head 14 can be raised for maintenance. The recooling time of the object to be cooled 90 and the radiation shield 92 can be shortened as compared with the case where the object to be cooled 90 and the radiation shield 92 are heated to room temperature together with the cold head 14 to perform maintenance on the cryogenic refrigerator 10. , The time required for maintenance can be shortened.

By installing the heat transfer structure 50 having a large number of heat transfer pieces 52 on the one-stage heat transfer stage 36, the contact area between the one-stage cooling stage 20 and the one-stage heat transfer stage 36 can be increased, thereby increasing the contact area between the one-stage cooling stage 20 and the one-stage heat transfer stage 36. The heat resistance that may occur between the cooling stage 20 and the one-stage heat transfer stage 36 can be reduced. Further, when the one-stage cooling stage 20 is inserted into the heat transfer structure 50, it comes into contact with the heat transfer piece 52 while sliding, and the elastic force generated in the heat transfer piece 52 presses the heat transfer piece 52 against the one-stage cooling stage 20. In this way, the heat transfer structure 50 can tighten the one-stage cooling stage 20 relatively strongly. The contact surface pressure between the heat transfer structure 50 and the one-stage cooling stage 20 can be increased, and the thermal resistance can be reduced.

It should be noted here that the contact surface pressure occurs in a direction different from the direction of movement of the cold head 14, for example, in a direction substantially orthogonal to each other. Therefore, although the contact area is increased by the addition of the heat transfer structure 50, the force required to push the cold head 14 is not so increased. Therefore, the workload for moving the cold head 14 in the axial direction does not change much. The existing lifting device can be used as it is.

When the cold head 14 makes thermal contact with the mounting structure 30, the force for pushing the cold head 14 in the axial direction is structurally distributed to the first-stage portion and the second-stage portion, and as a result, the contact between the first-stage portion and the second-stage portion is performed. The surface pressure is determined. In the present embodiment, by installing the heat transfer structure 50 on the one-stage heat transfer stage 36, the thermal contact between the one-stage cooling stage 20 and the one-stage heat transfer stage 36 is improved. Therefore, the cold head 14 and the mounting structure 30 can be designed so that the contact surface pressure of the two-stage portion is larger than that of the one-stage portion. In this way, good thermal contact can be provided not only for the first-stage portion but also for the second-stage portion.

FIG. 6 is a diagram schematically showing a modified example of the heat transfer structure 50 according to the embodiment. As shown in FIG. 6, the one-stage cooling stage 20 may have an inclined surface 20c that connects the bottom surface 20a to the side surface 20b. Since the one-stage cooling stage 20 has a columnar shape, the inclined surface 20c has a shape corresponding to the side surface of the truncated cone. The bottom surface 20a of the one-stage cooling stage 20 may come into contact with the one-stage heat transfer stage 36. Corresponding to the shape of the one-stage cooling stage 20, each heat transfer piece 52 of the heat transfer structure 50 may have a first heat transfer surface 52b and a second heat transfer surface 52c. The first heat transfer surface 52b may come into contact with the side surface 20b of the one-stage cooling stage 20, and the second heat transfer surface 52c may come into contact with the inclined surface 20c of the one-stage cooling stage 20. The shape of the one-stage heat transfer stage 36 may be determined so that at least a part of the inclined surface 20c of the one-stage cooling stage 20 comes into contact with the one-stage heat transfer stage 36.

FIG. 7 is a diagram schematically showing another modification of the heat transfer structure 50 according to the embodiment. It is not essential that each heat transfer piece 52 of the heat transfer structure 50 be made of a single material. As shown in FIG. 7, the radial inward surface 60 of each heat transfer piece 52 in contact with the side surface 20b of the one-stage cooling stage 20 is different from the high heat transfer material forming the main body portion 62 of the heat transfer piece 52. It may be formed of a material. The surface 60 may be a plating layer of a high thermal conductive metal, for example, a gold, silver, or indium plating layer formed on a copper main body portion 62.

FIG. 8 is a diagram schematically showing another modification of the heat transfer structure 50 according to the embodiment. Typically, metal materials with good thermal conductivity, such as copper, are relatively soft. Therefore, when the entire heat transfer piece 52 is formed of only such a material, the heat transfer piece 52 tends to have low rigidity. Then, when the one-stage cooling stage 20 is inserted into the heat transfer structure 50, the heat transfer piece 52 is deformed relatively easily, so that the contact surface pressure between the one-stage cooling stage 20 and the heat transfer piece 52 tends to be small. .. A high contact surface pressure is desired to reduce thermal resistance.

Therefore, as shown in FIG. 8, the heat transfer piece 52 may have a two-layer structure of the main body portion 62 and the leaf spring layer 64. The main body portion 62 is formed of a high thermal conductive material such as copper and comes into contact with the one-stage cooling stage 20. The leaf spring layer 64 is arranged on the outer peripheral portion of the main body portion 62 and is integrated with the main body portion 62. The leaf spring layer 64 is formed of a metal or other material that is harder than the material forming the main body portion 62, such as brass or stainless steel. Therefore, the leaf spring layer 64 has higher rigidity than the main body portion 62. Further, the material forming the leaf spring layer 64 typically has a lower thermal conductivity than the main body portion 62. In this way, the elastic force generated in the heat transfer piece 52 when the one-stage cooling stage 20 is inserted into the heat transfer structure 50 is increased, and the contact surface pressure between the heat transfer structure 50 and the one-stage cooling stage 20 is increased. , Thermal resistance can be reduced.

9 (a) and 9 (b) are diagrams schematically showing other modifications of the heat transfer structure 50 according to the embodiment. The heat transfer structure 50 may be elastically supported by a sleeve, for example, the one-stage sleeve body 34 of the mounting structure 30. As shown in FIG. 9A, each heat transfer piece 52 may be supported by the one-stage sleeve body 34 by an elastic member 66 such as a spring. Even in this way, the elastic force generated in the heat transfer piece 52 when the one-stage cooling stage 20 is inserted into the heat transfer structure 50 can be increased. In this case, as shown in FIG. 9B, each heat transfer piece 52 is not rigidly connected to the one-stage heat transfer stage 36, but is connected to the one-stage heat transfer stage 36 by the flexible heat transfer member 68. May be connected.

10 (a) and 10 (b) are schematic views for explaining the cryogenic refrigerator according to the embodiment. FIG. 10A shows a state in which the contact between the one-stage cooling stage 20 and the one-stage heat transfer stage 36 is released, and FIG. 10B shows the contact between the one-stage cooling stage 20 and the one-stage heat transfer stage 36. The state is shown. In the above-described embodiment, the heat transfer structure 50 is provided in the mounting structure 30, but as described below, the heat transfer structure 50 may be provided in the cold head 14 of the cryogenic refrigerator. ..

Therefore, the heat transfer structure 50 may be provided so as to be elastically displaceable with respect to the one-stage cooling stage 20. The heat transfer structure 50 can be elastically displaced with respect to the one-stage cooling stage 20 in a direction perpendicular to the movement of the cold head 14 (that is, a radial direction perpendicular to the axial direction). The heat transfer structure 50 is attached to the one-stage cooling stage 20. The heat transfer structure 50 is arranged so that when the one-stage cooling stage 20 comes into contact with the first surface of the one-stage heat transfer stage 36, it comes into contact with a second surface different from the first surface of the one-stage heat transfer stage 36. In this embodiment, the first surface is the upper surface 36a of the one-stage heat transfer stage 36, and the second surface is the side surface 36b of the one-stage heat transfer stage 36 at an angle with the upper surface 36a of the one-stage heat transfer stage 36. ..

The heat transfer structure 50 includes a plurality of heat transfer pieces 52, each of which is elastically displaceable with respect to the one-stage cooling stage 20. When the one-stage cooling stage 20 comes into contact with the first surface (for example, the upper surface 36a) of the one-stage heat transfer stage 36, each of the plurality of heat transfer pieces 52 comes into contact with the second surface (for example, the side surface 36b) of the one-stage heat transfer stage 36. ..

Even in this way, good thermal contact can be provided between the cold head 14 of the cryogenic refrigerator and the mounting structure 30 thereof.

The present invention has been described above based on examples. It will be understood by those skilled in the art that the present invention is not limited to the above embodiment, various design changes are possible, various modifications are possible, and such modifications are also within the scope of the present invention. By the way. The various features described in relation to one embodiment are also applicable to other embodiments. The new embodiments resulting from the combination have the effects of each of the combined embodiments.

In the above-described embodiment, the heat transfer structure 50 is provided in the one-stage portion of the cold head 14 or the mounting structure 30, but the heat transfer structure 50 may be provided in the two-stage portion. Therefore, for example, the heat transfer structure 50 is provided so as to be elastically displaceable with respect to the two-stage heat transfer stage 40, and when the two-stage heat transfer stage 40 comes into contact with the first surface of the two-stage cooling stage 24, the two-stage heat transfer structure 50 is provided in two stages. It may come into contact with a second surface different from the first surface of the cooling stage 24. Further, the heat transfer structure 50 may be provided in a single-stage cold head or a mounting structure thereof.

The cryogenic refrigerator 10 is not limited to the GM refrigerator. The cryogenic refrigerator 10 may be a pulse tube refrigerator, a Stirling refrigerator, or another type of cryogenic refrigerator.

Although the present invention has been described using specific terms and phrases based on the embodiments, the embodiments show only one aspect of the principles and applications of the present invention, and the embodiments are claimed. Many modifications and arrangement changes are permitted within the range not departing from the idea of the present invention defined in the scope.

10 Cryogenic refrigerator, 20 1-stage cooling stage, 20a bottom surface, 20b side surface, 24 2-stage cooling stage, 30 mounting structure, 36 1-stage heat transfer stage, 40 2-stage heat transfer stage, 50 heat transfer structure, 52 heat transfer piece, 90 object to be cooled, 92 radiation shield.

Claims (7)

It is a mounting structure of a cryogenic refrigerator,
A heat transfer stage that comes into contact with or is released from contact with the cooling stage of the cryogenic refrigerator by moving the cryogenic refrigerator.
It is provided so as to be elastically displaceable with respect to the heat transfer stage, and when the heat transfer stage comes into contact with the first surface of the cooling stage, the heat transfer comes into contact with a second surface different from the first surface of the cooling stage. A cryogenic refrigerator mounting structure characterized by having a thermal structure. The heat transfer structure comprises a plurality of heat transfer pieces, each of which is elastically displaceable with respect to the heat transfer stage.
The cryogenic temperature according to claim 1, wherein each of the plurality of heat transfer pieces comes into contact with the second surface of the cooling stage when the heat transfer stage comes into contact with the first surface of the cooling stage. Refrigerator mounting structure. The first surface is the bottom surface of the cooling stage, and the second surface is the side surface of the cooling stage at an angle with the bottom surface of the cooling stage.
The cryogenic refrigerator according to claim 1 or 2, wherein the heat transfer structure can be elastically displaced with respect to the heat transfer stage in a direction perpendicular to the movement of the cryogenic refrigerator. Mounting structure. The mounting structure of the cryogenic refrigerator according to any one of claims 1 to 3, wherein the heat transfer structure is mounted on the heat transfer stage. Further provided with a sleeve connected to the heat transfer stage
The mounting structure of a cryogenic refrigerator according to any one of claims 1 to 4, wherein the heat transfer structure is elastically supported by the sleeve. It has a structure in which a cryogenic refrigerator is mounted, and the cryogenic refrigerator is a two-stage cryogenic refrigerator.
A one-stage heat transfer stage that comes into contact with or is released from contact with the one-stage cooling stage of the cryogenic refrigerator by moving the cryogenic refrigerator.
A second surface that is elastically displaceable with respect to the one-stage heat transfer stage and is different from the first surface of the one-stage cooling stage when the one-stage heat transfer stage comes into contact with the first surface of the one-stage cooling stage. A cryogenic refrigerator mounting structure characterized by having a heat transfer structure that comes into contact with the water. A cooling stage that comes into contact with or is released from the heat transfer stage provided in the mounting structure of the cryogenic refrigerator by moving the cryogenic refrigerator.
It is provided so as to be elastically displaceable with respect to the cooling stage, and when the cooling stage comes into contact with the first surface of the heat transfer stage, the heat transfer comes into contact with a second surface different from the first surface of the heat transfer stage. An ultra-low temperature refrigerator characterized by having a thermal structure.

Images