Cryogenic refrigerator

Abstract

To protect a cryogenic refrigerator from an unexpected external force.SOLUTION: A cryogenic refrigerator 100 comprises a cold head 104 capable of being mounted on a vacuum container 20, a cold head mount 106 constituted so as to connect the cold head 104 to the vacuum container 20 so as to allow movement of the cold head 104 with respect to the vacuum container 20, a flexible line 108 connected to the cold head 104 outside the vacuum container 20, and a flexible line holder 110 constituted so as to fixedly hold the flexible line 108 with respect to the vacuum container 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to cryogenic refrigerators.

Background Art

[0002] Cryogenic refrigerators represented by Gifford-McMahon (GM) refrigerators are often used to provide cryogenic cooling for various cooling targets, such as cooling superconducting devices and condensing cryogenic liquids such as liquid helium. Conventionally, such cryogenic refrigerators are installed in a cryostat via bellows, and a thermal switch is realized that thermally connects or disconnects the cryogenic refrigerator to / from a cooling target in the cryostat by utilizing the vertical movement of the cryogenic refrigerator accompanied by the expansion and contraction of the bellows.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the thermal switch of the above-described type is on (i.e., when the cryogenic refrigerator is thermally connected to the cooling target), the cryogenic refrigerator can be rigidly fixed to the cryostat, whereas when the thermal switch is off (i.e., when the cryogenic refrigerator is temporarily disconnected from the cooling target), the cryogenic refrigerator tends to be supported by the cryostat with low rigidity, for example, due to the flexibility of the bellows.

[0005] When operating a cryogenic refrigerator on-site, various pipes and wires, such as flexible hoses for supplying and exhausting the working gas and cables for power supply, are connected to the cryogenic refrigerator and extend around it. One of the risks that can be anticipated in such a typical cryogenic refrigerator setup is the possibility of unexpected and large external forces acting on the cryogenic refrigerator from the piping, for example, if a worker passing near the cryogenic refrigerator trips over these pipes. Such unexpected external forces can cause problems, especially when the thermal switch is off. The external force may disrupt the position and orientation of the cryogenic refrigerator, causing interference and collision with surrounding structures, and in the worst case, potentially damaging the cryogenic refrigerator or its support structure.

[0006] One exemplary object of a certain aspect of the present invention is to protect a cryogenic refrigerator from unexpected external forces. [Means for solving the problem]

[0007] According to one aspect of the present invention, the cryogenic refrigerator comprises a cold head that can be mounted on a vacuum vessel, a cold head mount configured to connect the cold head to the vacuum vessel so as to allow movement of the cold head relative to the vacuum vessel, a flexible line connected to the cold head outside the vacuum vessel, and a flexible line holder configured to hold the flexible line fixedly with respect to the vacuum vessel. [Effects of the Invention]

[0008] According to the present invention, cryogenic refrigerators can be protected from unexpected external forces. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram showing a cryogenic apparatus according to an embodiment. [Figure 2] This diagram schematically shows the operating gas line of a cryogenic refrigerator according to a comparative example. [Figure 3]This diagram schematically shows an exemplary electrical connection that can be applied to the cryogenic refrigerator shown in Figure 1. [Figure 4] This figure schematically shows an exemplary drive source that can be applied to the cryogenic refrigerator shown in Figure 1. [Modes for carrying out the invention]

[0010] The embodiments for carrying out the present invention will be described in detail below with reference to the drawings. In the description and drawings, identical or equivalent components, members, and processes are denoted by the same reference numerals, and redundant descriptions will be omitted as appropriate. The scale and shape of the illustrated parts are set for convenience to facilitate the explanation and are not to be interpreted restrictively unless otherwise specified. The embodiments are illustrative and do not limit the scope of the present invention in any way. Not all features or combinations thereof described in the embodiments are necessarily essential to the invention.

[0011] Figure 1 is a schematic diagram showing a cryogenic apparatus 10 according to an embodiment. In this embodiment, the cryogenic apparatus 10 can be used as a cryogenic liquid storage device. The cryogenic apparatus 10 includes, for example, a vacuum container 20 for storing liquid hydrogen or other cryogenic liquids 12, and a cryogenic refrigerator 100 for cooling the stored cryogenic liquid 12 to a cryogenic temperature below its liquefaction temperature (in the case of liquid hydrogen, approximately -253°C (20K)).

[0012] The vacuum vessel 20 comprises an outer tank 22 and an inner tank 24. A vacuum insulation layer 26 is formed between the outer tank 22 and the inner tank 24. The outer tank 22 is configured to separate the vacuum insulation layer 26 from the surrounding environment of the cryogenic apparatus 10 (e.g., room temperature and atmospheric pressure environment). The inner tank 24 is configured to separate its internal volume from the vacuum insulation layer 26. The cryogenic liquid 12 is contained in the inner tank 24. The outer tank 22 and the inner tank 24 are formed of a metal material such as stainless steel or other suitable high-strength material to withstand the pressure difference between the inside and outside.

[0013] A thermal insulation structure 28, including a thermal insulation support 28a and a thermal insulation layer 28b, may be arranged in the vacuum insulation layer 26. The thermal insulation support 28a is formed from a rigid material with thermal insulation properties, such as fiber-reinforced plastic, and is configured to support the inner tank 24 in the outer tank 22. The thermal insulation layer 28b may comprise multilayer insulation (MLI). Together with or instead of the thermal insulation layer 28b, the thermal insulation structure 28 may include granular or other form of thermal insulation material (e.g., granular perlite) filled into the vacuum insulation layer 26.

[0014] The inner tank 24 includes a re-condensing section 30 provided in its tank wall. The re-condensing section 30 is cooled from outside the inner tank 24 by the cryogenic refrigerator 100. The re-condensing section 30 has a heat transfer surface 30a that is exposed to the outside of the inner tank 24 and in contact with the cryogenic refrigerator 100. The re-condensing section 30 may have fin-like protrusions or irregularities inside the inner tank 24 to increase the surface area in contact with the cryogenic liquid 12 or vaporized cryogenic liquid 12. The re-condensing section 30 is formed of, for example, pure copper (e.g., oxygen-free copper, tough pitch copper, etc.) or other high thermal conductivity metals.

[0015] The cryogenic refrigerator 100 comprises a compressor 102, a cold head 104 that can be mounted on a vacuum vessel 20, and a cold head mount 106 configured to connect the cold head 104 to the vacuum vessel 20 so as to allow the cold head 104 to move relative to the vacuum vessel 20.

[0016] The compressor 102 is configured to recover the working gas of the cryogenic refrigerator 100 from the cold head 104, pressurize the recovered working gas, and supply the working gas back to the cold head 104. The cold head 104 is also called the expander or refrigerator. The compressor 102 and the cold head 104 constitute the refrigeration cycle of the cryogenic refrigerator 100, thereby providing cryogenic cooling. The working gas is also called the refrigerant gas and is usually helium gas, but other suitable gases may be used.

[0017] In this embodiment, the cryogenic refrigerator 100 is a single-stage GM refrigerator. Accordingly, the cold head 104 comprises a cooling stage 104a, a cylinder 104b, a drive unit 104c, and a cold head flange 104d. The cooling stage 104a is formed of, for example, pure copper (e.g., oxygen-free copper, tough pitch copper, etc.) or another high thermal conductivity metal. During operation of the cryogenic refrigerator 100, the cooling stage 104a is cooled to a desired cryogenic temperature, for example, a temperature range below the liquefaction temperature of the cryogenic liquid 12. If the cryogenic liquid 12 is liquid hydrogen, the cooling stage 104a is cooled to a cooling temperature that falls within the temperature range of 10K to 30K (e.g., a cooling temperature around 20K, such as 20K±1K, 20K±2K, or 20K±5K).

[0018] Cylinder 104b connects the cooling stage 104a to the cold head flange 104d. Inside cylinder 104b, a displacer (not shown) is positioned to be movable in the axial direction (up and down in Figure 1) of cylinder 104b for controlling the volume of the working gas expansion space adjacent to the cooling stage 104a. Cylinder 104b and cold head flange 104d are typically made of a suitable metal material, such as stainless steel. The drive unit 104c is attached to the cold head flange 104d on the opposite side from cylinder 104b. The drive unit 104c is equipped with a cold head drive motor 104e, such as an electric motor, for driving the displacer inside cylinder 104b, and a pressure control mechanism (not shown), such as a rotary valve, for controlling the working gas pressure in the expansion space inside cylinder 104b.

[0019] As shown in FIG. 1, an outer tank 22 of a vacuum vessel 20 is provided with a mounting port 32 for mounting a cold head 104 to the vacuum vessel 20. When mounting, the cold head 104 is inserted into the vacuum vessel 20 through the mounting port 32 and removably attached to the mounting port 32 via a cold head mount 106. The cold head 104 is mounted to the vacuum vessel 20 such that a cooling stage 104a is disposed in a vacuum insulation layer 26 inside the vacuum vessel 20 and a drive unit 104c is disposed outside the vacuum vessel 20.

[0020] As an example, the mounting port 32 is formed on a top plate or an upper portion of the vacuum vessel 20. The cold head 104 is installed in the vacuum vessel 20 such that its central axis coincides with the vertical direction. However, the position of the mounting port 32 and the mounting posture of the cold head 104 are not limited thereto. For example, the mounting port 32 may be formed on a bottom plate or a lower portion of the vacuum vessel 20. The cold head 104 can be installed in a desired posture and may be installed in the vacuum vessel 20 such that its central axis coincides with an oblique direction or a horizontal direction.

[0021] The cold head mount 106 includes a mounting flange 106a attachable to the vacuum vessel 20 and an expandable and contractible airtight partition 106b connecting the cold head 104 to the mounting flange 106a. The mounting flange 106a is fixed to the mounting port 32 of the vacuum vessel 20 using fastening members such as bolts or other appropriate fixing means. Note that the mounting flange 106a may be fixed to the vacuum vessel 20 via a connecting member instead of being directly fixed to the vacuum vessel 20 as shown in the figure. The expandable and contractible airtight partition 106b is, for example, a bellows and connects a cold head flange 104d to the mounting flange 106a. Accordingly, the mounting port 32 is closed by the mounting flange 106a, the airtight partition 106b, and the cold head flange 104d, and the airtightness of the vacuum vessel 20 is maintained.

[0022] [[ID=!1]] The mounting flange 106a has an opening at its central part, and the expandable and contractible airtight partition wall 106b is formed in a cylindrical shape. The cylinder 104b of the cold head 104 extends into the vacuum vessel 20 through the expandable and contractible airtight partition wall 106b from the cold head flange 104d and through the opening of the mounting flange 106a.

[0023] Further, the cold head mount 106 includes a drive source 106c that is mounted on the cold head mount 106 and is configured to move the cold head 104 relative to the vacuum vessel 20. The drive source 106c may be configured to move the cold head 104 using appropriate power such as pneumatic pressure, hydraulic pressure, an electric motor, an electromagnet, etc., or may be operable to move the cold head 104 manually.

[0024] The drive source 106c is installed on the mounting flange 106a and is connected to the cold head flange 104d so as to move the cold head flange 104d in the expansion and contraction direction of the airtight partition wall 106b. Therefore, by operating the drive source 106c, the cold head flange 104d can be moved relative to the mounting flange 106a while expanding and contracting the airtight partition wall 106b. In the example shown in FIG. 1, the drive source 106c can move the cold head flange 104d (i.e., the cold head 104 relative to the vacuum vessel 20) up and down with respect to the mounting flange 106a.

[0025] In this way, the cold head mount 106 can act as a thermal switch to thermally connect or disconnect the cold head 104 to the inner chamber 24 of the vacuum vessel 20, which is a storage tank for the cryogenic liquid 12. In Figure 1, the state in which the thermal switch is ON is shown by a solid line, and the state in which the thermal switch is OFF is shown by a dashed line. When the thermal switch is ON, the cooling stage 104a of the cold head 104 comes into contact with the heat transfer surface 30a of the recondensation section 30 of the inner chamber 24. This allows the cooling stage 104a to cool the recondensation section 30 to the liquefaction temperature of the cryogenic liquid 12, thereby retaining the cryogenic liquid 12 in the inner chamber 24 and recondensing the vaporized cryogenic liquid 12. On the other hand, when the cold head 104 is lifted by the operation of the drive source 106c, the cooling stage 104a moves away from the heat transfer surface 30a of the recondensation section 30. Since the cooling stage 104a is located in the vacuum insulation layer 26, thermal contact between the cooling stage 104a and the recondensation section 30 is eliminated. At this time, the cold head 104 does not cool the inner tank 24.

[0026] Such thermal switches are advantageous in improving the energy efficiency of the cryogenic device 10. As an example of operation of the cryogenic refrigerator 100, it is conceivable to stop the cooling operation of the cryogenic refrigerator 100 when the vacuum vessel 20 has cooled sufficiently. At this time, if the cold head 104 remains in contact with the inner tank 24 of the vacuum vessel 20, the cold head 104 becomes a heat transfer path from the ambient environment of the cryogenic device 10 to the inner tank 24, which could cause unwanted heat intrusion into the cryogenic liquid 12. In contrast, when stopping the cryogenic refrigerator 100, such heat intrusion can be blocked by using a thermal switch to disconnect the cold head 104 from the inner tank 24.

[0027] For switching the thermal switch, the cryogenic device 10 may be provided with a sensor 34 that detects the physical quantity of the cryogenic liquid 12. The drive source 106c may be configured to receive an output signal from the sensor 34 indicating the detected physical quantity of the cryogenic liquid 12 and to move the cold head 104 based on the detected physical quantity of the cryogenic liquid 12.

[0028] For example, the sensor 34 may be placed in the inner chamber 24 of the vacuum vessel 20 and configured to measure the internal pressure of the inner chamber 24. The vapor pressure of the cryogenic liquid 12 in the inner chamber 24 is measured by the sensor 34. The drive source 106c may compare the measured pressure with a pressure threshold and operate to turn on the thermal switch if the measured pressure exceeds the pressure threshold and to turn off the thermal switch if the measured pressure falls below the pressure threshold. In this way, the internal pressure of the inner chamber 24 can be maintained at an appropriate pressure corresponding to the pressure threshold.

[0029] Alternatively, the sensor 34 may be configured to measure the temperature of the cryogenic liquid 12. In this case, the sensor 34 may be placed inside the inner tank 24 or installed in the recondensation section 30 of the inner tank 24. The drive source 106c may compare the measured temperature with a temperature threshold and operate to turn on the thermal switch when the measured temperature exceeds the temperature threshold and to turn off the thermal switch when the measured temperature falls below the temperature threshold. In this way, the cryogenic liquid 12 can be maintained at an appropriate temperature corresponding to the temperature threshold.

[0030] Furthermore, the cryogenic refrigerator 100 includes a flexible line 108 connected to a cold head 104 outside the vacuum vessel 20, and a flexible line holder 110 configured to hold the flexible line 108 fixedly to the vacuum vessel 20. The flexible line 108 connects the drive unit 104c of the cold head 104 to an external element (e.g., a compressor 102) located outside the vacuum vessel 20. The flexible line holder 110 is fixed to the mounting flange 106a of the cold head mount 106 and holds the flexible line 108 along the way from the cold head 104 to the external element. In other words, the flexible line holder 110 acts as an intermediate point that fixes the flexible line 108 to the vacuum vessel 20.

[0031] The compressor 102 may be located at a distance from the cold head 104 and vacuum vessel 20, for example, by being installed in a room or compartment separate from the room or compartment where the cold head 104 and vacuum vessel 20 are installed, and the length of the flexible line 108 may be, for example, 10 m or more. The flexible line holder 110 is fixed to the mounting flange 106a and holds the flexible line 108 at the end of the flexible line 108 on the cold head 104 side (for example, the end of the flexible line 108 that is within 10% or 5% of the total length of the flexible line 108).

[0032] In this embodiment, the flexible line 108 includes working gas lines for supplying working gas to or from the cold head 104, more specifically, a gas supply line 112 and a gas recovery line 114. The gas supply line 112 connects the working gas discharge port 102a of the compressor 102 to the high-pressure port 116a of the cold head 104, and the gas recovery line 114 connects the working gas intake port 102b of the compressor 102 to the low-pressure port 116b of the cold head 104.

[0033] Therefore, the working gas of the cryogenic refrigerator 100 is supplied from the compressor 102 to the cold head 104 through the gas supply line 112, and recovered from the cold head 104 to the compressor 102 through the gas recovery line 114. As is well known, the pressure of the working gas in the gas supply line 112 and the pressure of the working gas in the gas recovery line 114 are both considerably higher than atmospheric pressure and can be called the first high pressure and the second high pressure, respectively. For convenience of explanation, the first high pressure and the second high pressure are also simply called high pressure and low pressure, respectively. Typically, the high pressure is, for example, 2 to 3 MPa. The low pressure is, for example, 0.5 to 1.5 MPa, or about 0.8 MPa.

[0034] The flexible line holder 110 may include an operating gas line holder for holding such operating gas lines. The flexible line holder 110 may have a first holder for holding a gas supply line 112 and a second holder for holding a gas recovery line 114, and these two holders may be fixed to the mounting flange 106a. The flexible line holder 110 can be rigidly fixed to the mounting flange 106a by means of screws, welding, or other appropriate fastening means.

[0035] The two holders may be arranged side by side on the mounting flange 106a, or they may be arranged on the mounting flange 106a so as to sandwich the drive unit 104c, or they may be arranged at any other location on the mounting flange 106a. In the example shown in Figure 1, the flexible line holder 110 is attached to the upper surface of the mounting flange 106a, but it may also be attached to the lower surface of the mounting flange 106a or other part.

[0036] The gas supply line 112 comprises a first portion 112a extending from the high-pressure port 116a of the cold head 104 and a second portion 112b extending from the working gas discharge port 102a of the compressor 102. The flexible line holder 110 may be configured as an intermediate joint having an internal passage through which the working gas of the cryogenic refrigerator 100 can flow. For example, the first holder may be a first intermediate joint having a first internal passage. In this case, the first portion 112a of the gas supply line 112 is connected to the first holder at one end and to the high-pressure port 116a at the other end. The second portion 112b of the gas supply line 112 is connected to the first holder at one end and to the working gas discharge port 102a at the other end. Thus, the high-pressure working gas discharged from the working gas discharge port 102a flows into the cold head 104 through the second portion 112b, the first holder, and the first portion 112a.

[0037] Similarly, the gas recovery line 114 comprises a first portion 114a extending from the low-pressure port 116b of the cold head 104 and a second portion 114b extending from the working gas intake port 102b of the compressor 102. The flexible line holder 110 may be configured as an intermediate joint having an internal passage through which the working gas of the cryogenic refrigerator 100 can flow. For example, the second holder may be a second intermediate joint having a second internal passage. In this case, the first portion 114a of the gas recovery line 114 is connected to the second holder at one end and to the low-pressure port 116b at the other end. The second portion 114b of the gas recovery line 114 is connected to the second holder at one end and to the working gas intake port 102b at the other end. In this way, the low-pressure working gas flowing out from the low-pressure port 116b of the cold head 104 is recovered by the compressor 102 through the first part 114a, the second holder, and the second part 114b.

[0038] The gas supply line 112 and the gas recovery line 114 may be flexible piping, such as flexible hoses. Furthermore, the gas supply line 112 and the gas recovery line 114 may be detachable from the compressor 102, cold head 104, and flexible line 108, for example, to facilitate replacement due to wear and tear.

[0039] Figure 2 is a schematic diagram showing the operating gas line of a cryogenic refrigerator according to a comparative example. As shown in the figure, the cryogenic refrigerator 200 comprises a compressor 202 and a cold head 204. The compressor 202 and the cold head 204 are connected by a flexible hose 206. The cold head 204 is mounted on the vacuum vessel 20 so that it can be moved (raised and lowered) relative to the vacuum vessel 20. The cold head 204 can operate as a thermal switch by raising and lowering itself, thereby thermally connecting or disconnecting the cold head 204 from the object to be cooled 208. In Figure 2, the thermal switch is shown to be off, i.e., the cold head 204 is separated from the object to be cooled 208.

[0040] A worker passing near the cryogenic refrigerator 200 might trip over the flexible hose 206 by catching their foot 210 on it. If this happens, the flexible hose 206 will be instantly and strongly pulled by the tripped foot 210, potentially acting as a strong lateral load 212 on the cold head 204. Since the cold head 204 is supported by a low-rigidity support structure such as a bellows when the thermal switch is off, the lateral load 212 could disrupt the position and orientation of the cryogenic refrigerator 200, as shown by the black arrow 214 and dashed line in Figure 2, and in some cases, cause the cryogenic refrigerator 200 to collide with surrounding structures such as the vacuum container 20 or the object being cooled 208. As a result, the cryogenic refrigerator 200 and the surrounding structures may be damaged.

[0041] In contrast, according to this embodiment, the flexible line 108 is fixedly held to the vacuum vessel 20 by the flexible line holder 110. For the second portion of the flexible line 108 (e.g., 112b, 114b) on the side farther from the cold head 104, there is still a risk that an operator may trip over it. However, even if such a situation were to occur, the tensile force acting on the second portion would only be borne by the mounting flange 106a to which the flexible line holder 110 is fixed and the vacuum vessel 20. This tensile force would not be directly transmitted to the cold head 104, and it is expected that the position and orientation of the cold head 104 can be maintained even when the thermal switch is off. In this way, the cryogenic refrigerator 100 can be protected from unexpected external forces.

[0042] Figure 3 schematically shows an exemplary electrical connection that may be applied to the cryogenic refrigerator 100 shown in Figure 1. The flexible line 108 may be a power supply cable for supplying power to the cold head 104. The power supply cable connects a power supply 118 located outside the vacuum vessel 20 to the drive unit 104c of the cold head 104 (for example, the cold head drive motor 104e shown in Figure 1). In the exemplary configuration, the compressor 102 may be used as the power supply 118.

[0043] The flexible line holder 110 may also be a cable holder fixed to the mounting flange 106a and holding the power supply cable. In the illustrated example, the flexible line holder 110 is mounted to the mounting flange 106a so as to pass through the mounting flange 106a. This allows the power supply cable to be routed from one side of the mounting flange 106a (e.g., the top side) to the opposite side (e.g., the bottom side). This provides greater flexibility in the placement of the power supply cable compared to routing the power supply cable only on the top side of the mounting flange 106a.

[0044] Even in this manner, the cryogenic refrigerator 100 can be protected from unexpected external forces, similar to the embodiments described with reference to Figures 1 and 2. That is, even if an unexpected external force acts on the second portion of the flexible line 108 extending from the flexible line holder 110 to the power supply 118, this external force can be absorbed by the mounting flange 106a to which the flexible line holder 110 is fixed and the vacuum vessel 20. This reduces the adverse effects of external forces on the cold head 104.

[0045] As mentioned above, a flexible line holder 110 that penetrates the mounting flange 106a may be used as the holder for the operating gas line described with reference to Figure 1.

[0046] Figure 4 is a schematic diagram illustrating an exemplary drive source applicable to the cryogenic refrigerator 100 shown in Figure 1. The drive source 106c is mounted on a plate-shaped support 120 positioned above the cold head 104. The drive source 106c includes a movable piston 122 that penetrates the support 120 and protrudes downward. Multiple (e.g., four) guide rods 124 are erected on the mounting flange 106a so as to surround the cold head 104, and the support 120 is fixed to the ends of the guide rods 124. The guide rods 124 penetrate the cold head flange 104d in the vertical direction, and the cold head flange 104d is movable vertically along the guide rods 124.

[0047] Furthermore, a movable frame 126, including support columns 126a and movable plates 126b, is installed on the cold head flange 104d. Support columns 126a are erected on the cold head flange 104d, and movable plates 126b are fixed to support columns 126a so as to bridge the ends of the support columns 126a. The lower end of a movable piston 122 is fixed to the movable plate 126b.

[0048] Therefore, when the movable piston 122 moves up and down due to the operation of the drive source 106c, the cold head flange 104d can also move up and down via the movable frame 126. At this time, the cold head flange 104d moves up and down along the guide rod 124, accompanied by the expansion and contraction of the airtight partition wall 106b. In this way, the drive source 106c can provide movement of the cold head 104 relative to the vacuum vessel 20.

[0049] The cryogenic refrigerator 100 may also include another flexible line 128 connected to a drive source 106c and another flexible line holder 130 configured to hold the other flexible line 128 fixedly to the vacuum vessel 20. The drive source 106c may be, for example, an air cylinder, in which case the flexible line 128 may be a compressed air line for supplying and discharging compressed air to the drive source 106c. The flexible line holder 130 may be a holder fixed to the mounting flange 106a and for holding the compressed air line.

[0050] In this way, the cryogenic refrigerator 100 can be protected from unexpected external forces. That is, even if an unexpected external force acts on the second portion of the flexible line 128 extending from the flexible line holder 130 to the compressed air source 132, this external force can be absorbed by the mounting flange 106a to which the flexible line holder 130 is fixed and the vacuum vessel 20. This reduces the adverse effects of external forces on the cold head 104.

[0051] The present invention has been described above based on examples. Those skilled in the art will understand that the present invention is not limited to the above embodiments, that various design changes are possible, and that various modifications are possible, and that such modifications also fall within the scope of the present invention. Various features described in relation to one embodiment are applicable to other embodiments. New embodiments resulting from combinations will possess the combined effects of each of the embodiments combined.

[0052] The above-described embodiment explains the case where the operating gas line holder is an intermediate joint, but other configurations are also possible. For example, the operating gas line holder may be a suitable fixing device such as a hose clamp that holds the operating gas line, and such a fixing device may be fixed to the mounting flange 106a. In this case, the operating gas line does not need to be divided by the holder (the operating gas line does not need to be divided into a first part and a second part, and may be a single flexible hose).

[0053] The above-described embodiment illustrates the case where the flexible line holder 110 is fixed to the mounting flange 106a of the cold head mount 106, but other configurations are also possible. For example, the flexible line holder 110 may be fixed directly to the vacuum vessel 20. For example, the flexible line holder 110 may be fixed to the wall of the vacuum vessel 20 to which the mounting flange 106a is attached (i.e., to which the mounting opening 32 is provided), or to another part of the vacuum vessel 20.

[0054] The above-described embodiment uses the case where the cryogenic refrigerator 100 is a single-stage GM refrigerator as an example, but other configurations are also possible. For example, the cryogenic refrigerator 100 may be a two-stage GM refrigerator. In this case, the cryogenic refrigerator 100 may provide cryogenic cooling of about 4K or less, and the cryogenic liquid 12 may be liquid helium. Alternatively, the cryogenic refrigerator 100 may be a pulse tube refrigerator, a Stirling refrigerator, or another type of cryogenic refrigerator.

[0055] The above-described embodiment explains the case where the cryogenic device 10 is a storage device for cryogenic liquid 12, but other configurations are also possible. For example, the cryogenic device 10 may be a superconducting device, and the cryogenic refrigerator 100 may be used to cool a superconducting coil placed inside the vacuum vessel 20.

[0056] Although the present invention has been described using specific terms based on the embodiments, the embodiments only illustrate one aspect of the principle and application of the present invention, and many modifications and changes in arrangement are permitted in the embodiments, as long as they do not depart from the spirit of the present invention as defined in the claims. [Explanation of Symbols]

[0057] 20 Vacuum container, 100 Cryogenic refrigerator, 104 Cold head, 106 Cold head mount, 106a Mounting flange, 106b Airtight partition, 106c Drive source, 108 Flexible line, 110 Flexible line holder.

Claims

1. A cold head that can be mounted on a vacuum container, A cold head mount is configured to connect the cold head to the vacuum container so as to allow the movement of the cold head relative to the vacuum container, A flexible line connected to the cold head outside the vacuum container, The system includes a flexible line holder configured to hold the flexible line in a fixed manner relative to the vacuum container, The cold head mount comprises a mounting flange that can be attached to the vacuum vessel, and an expandable and expandable airtight partition that connects the cold head to the mounting flange. The cryogenic refrigerator is characterized in that the flexible line holder is fixed to the mounting flange.

2. The flexible line includes an operating gas line for supplying working gas to or discharging working gas from the cold head. The cryogenic refrigerator according to claim 1, characterized in that the flexible line holder includes an operating gas line holder that holds the operating gas line and is fixed to the mounting flange.

3. The flexible line includes a power supply cable for supplying power to the cold head. The cryogenic refrigerator according to claim 1, characterized in that the flexible line holder includes a cable holder that holds the power supply cable and is fixed to the mounting flange.

4. A drive source mounted on the cold head mount and configured to move the cold head relative to the vacuum vessel, Another flexible line connected to the aforementioned drive source, The cryogenic refrigerator according to any one of claims 1 to 3, further comprising another flexible line holder configured to hold the other flexible line in a fixed manner with respect to the vacuum vessel.

5. The cryogenic refrigerator according to claim 4, characterized in that the other flexible line holder is fixed to the mounting flange.

6. A cold head that can be mounted on a vacuum container, A cold head mount is configured to connect the cold head to the vacuum container so as to allow the movement of the cold head relative to the vacuum container, A flexible line is positioned exposed to the surrounding environment of the vacuum vessel and connected to the cold head outside the vacuum vessel, A cryogenic refrigerator comprising a flexible line holder configured to hold the flexible line fixedly with respect to the vacuum container in the aforementioned ambient environment.

Images