JP7450406B2 - Cryogenic equipment and thermal switches - Google Patents

Description

The present invention relates to cryogenic devices and thermal switches.

BACKGROUND ART Conventionally, superconducting magnet devices are known that cool superconducting coils by conduction cooling using a cryogenic refrigerator. This device is equipped with a thermal switch. In the steady operation state of the cryogenic refrigerator, the thermal switch is closed by applying contact pressure to the thermal switch, and a heat transfer path from the refrigerator to the superconducting coil is formed. If an abnormality is detected in the cryogenic refrigerator, the thermal switch is opened and the superconducting coil is insulated from the refrigerator.

JP2012-209381A

The inventor studied the above-mentioned thermal switch and recognized the following problems. Contact pressure in a thermal switch affects thermal resistance. In fact, to obtain the desired good thermal contact, fairly high contact pressures are required, which is not very easy. Pressurizing devices that apply contact pressure to thermal switches tend to be large-scale in order to achieve strong pressurization. Related structures such as thermal switches and cryogenic refrigerators that are subject to such large loads must also be designed to be robust to withstand such loads. On the other hand, insufficient contact pressure causes an increase in thermal resistance, which in turn causes a temperature difference. In this case, the cooling temperature of the superconducting coil may not be sufficiently lowered to the temperature that can be achieved by the refrigerator. In order to avoid insufficient cooling of the superconducting coils, it may be necessary to consider adopting a cryogenic refrigerator with greater cooling capacity or installing additional cryogenic refrigerators.

One exemplary object of an embodiment of the present invention is to provide a thermal switch and a cryogenic device equipped with the same that can relatively easily achieve good thermal contact.

According to an aspect of the present invention, a cryogenic device includes a first heat transfer component having a first heat transfer surface and a second heat transfer component having a shape insertable into the first heat transfer component and having a second heat transfer surface. a thermal switch, the first heat transfer surface and the second heat transfer surface slidingly contacting each other when the second heat transfer component is inserted into the first heat transfer component; a cryogenic refrigerator comprising a cooling stage thermally coupled to either the component or the second heat transfer component.

According to an aspect of the invention, a thermal switch for a cryogenic device includes a first heat transfer component attachable to one of the cooling side or the cooled side of the cryogenic device; a second heat transfer component that can be attached to the other side of the heat transfer component. The first heat transfer component has a first heat transfer surface, the second heat transfer component has a shape that can be inserted into the first heat transfer component, has a second heat transfer surface, and the second heat transfer component When inserted into the first heat transfer component, the first heat transfer surface and the second heat transfer surface contact each other while sliding.

Note that arbitrary combinations of the above-mentioned constituent elements and mutual substitution of constituent elements and expressions of the present invention among methods, devices, systems, etc. are also effective as aspects of the present invention.

According to the present invention, it is possible to provide a thermal switch that can relatively easily obtain good thermal contact, and a cryogenic device equipped with the thermal switch.

1 is a diagram schematically showing a thermal switch for a cryogenic device according to an embodiment; FIG. 1 is a diagram schematically showing a thermal switch for a cryogenic device according to an embodiment; FIG. 2 is a diagram schematically showing a cross section taken along line AA of the first heat transfer component shown in FIG. 1. FIG. FIG. 7 is a diagram schematically showing another example of the pressing mechanism provided in the thermal switch according to the embodiment. FIG. 7 is a diagram schematically showing a modification of the thermal switch according to the embodiment. 6(a) and 6(b) are diagrams schematically showing a modification of the thermal switch according to the embodiment. FIG. 1 is a diagram schematically showing a cryogenic device according to an embodiment. FIG. 2 is a schematic diagram showing a thermal switch according to a comparative example. FIG. 7 is a diagram schematically showing a modification of the thermal switch according to the embodiment. FIGS. 10(a) to 10(d) are diagrams schematically showing modifications of the installation of the thermal switch according to the embodiment. It is a figure which shows schematically the modification of the cryogenic apparatus based on embodiment. It is a figure which shows schematically the modification of the cryogenic apparatus based on embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 denoted by the same reference numerals, and overlapping explanations will be omitted as appropriate. The scales and shapes of the parts shown in the figures are set for convenience to facilitate explanation, and should not be interpreted in a limited manner unless otherwise stated. The embodiments are merely illustrative and do not limit the scope of the present invention. All features and combinations thereof described in the embodiments are not necessarily essential to the invention.

1 and 2 are diagrams schematically showing a thermal switch 10 for a cryogenic device according to an embodiment. FIG. 1 shows the thermal switch 10 in an off state, and FIG. 2 shows the thermal switch 10 in an on state.

The thermal switch 10 includes a first heat transfer component 12 that can be attached to either the cooling side or the cooled side of the cryogenic device, and a second heat transfer component that can be attached to the other of the cooling side or the cooled side of the cryogenic device. 14.

In this embodiment, the first heat transfer component 12 is attached to the first heat transfer member 16 on the cooled side, and the second heat transfer component 14 is attached to the second heat transfer member 18 on the cooled side. In order to obtain good thermal contact, the first heat transfer component 12 and the second heat transfer component 14 are securely fixed to the first heat transfer member 16 and the second heat transfer member 18, respectively. For example, the first heat transfer component 12 is fixed to the first heat transfer member 16 by caulking, and the second heat transfer component 14 is fixed to the second heat transfer member 18 by screws. However, the fixing of the heat transfer component to the heat transfer member is not limited to such mechanical bonding, and metallurgical bonding such as soldering or other appropriate bonding techniques may be used.

The second heat transfer component 14 has a shape that can be inserted into the first heat transfer component 12. In other words, the first heat transfer component 12 is a female terminal, and the second heat transfer component 14 is a male terminal, and coupling and separation can be switched by relative movement of both components. For example, the thermal switch 10 may be configured such that the first heat transfer member 16 is fixed such that the first heat transfer component 12 is stationary and the second heat transfer member 18 is movable with the second heat transfer component 14. One of the two parts is moved relative to the other. However, both of the two parts may be movable.

The first heat transfer component 12 has a first heat transfer surface 20 and the second heat transfer component 14 has a second heat transfer surface 22. The first heat transfer component 12 includes an insertion port 24 , and the first heat transfer surface 20 corresponds to the inner peripheral surface of the insertion port 24 . The second heat transfer component 14 is formed as a protrusion that can be inserted into the insertion opening 24, and the second heat transfer surface 22 corresponds to the outer peripheral surface of this protrusion.

The diameter of the first heat transfer surface 20 may be equal to the diameter of the second heat transfer surface 22. The dimensional tolerance of the diameter of each of the first heat transfer surface 20 and the second heat transfer surface 22 may be determined so that the first heat transfer surface 20 and the second heat transfer surface 22 contact each other while sliding. . Alternatively, as described later, when at least one of the first heat transfer surface 20 and the second heat transfer surface 22 is elastically flexible in the radial direction, the first heat transfer component 12 and the second heat transfer component 14 (that is, when the second heat transfer component 14 is not inserted into the first heat transfer component 12), the diameter of the insertion opening 24 of the first heat transfer component 12 is the same as that of the second heat transfer component 14. It may be slightly smaller than the diameter. The first heat transfer surface 20 and the second heat transfer surface 22 can slide with stronger contact surface pressure.

The first heat transfer component 12 and the second heat transfer component 14 are arranged on a common axis that is the central axis of both components, and linear relative movement along this axis causes the second heat transfer component 14 to move toward the first heat transfer component 14. It is inserted into the heat transfer component 12. In FIG. 1, the insertion direction 26 of the second heat transfer component 14 is illustrated by a downward arrow.

In this embodiment, both the first heat transfer surface 20 and the second heat transfer surface 22 are parallel to the insertion direction 26 of the second heat transfer component 14 into the first heat transfer component 12 . As an example, the first heat transfer component 12 is a socket having a cylindrical pin hole as the insertion opening 24, and the second heat transfer component 14 is a columnar or cylindrical pin.

However, as long as the first heat transfer surface 20 and the second heat transfer surface 22 contact each other while sliding when the second heat transfer component 14 is inserted into the first heat transfer component 12, the first heat transfer component 12 and The second heat transfer component 14 is not limited to having a circular cross section perpendicular to the insertion direction 26, and may have a square, rectangular, or other cross-sectional shape, for example.

When the second heat transfer component 14 is inserted into the first heat transfer component 12, the first heat transfer surface 20 and the second heat transfer surface 22 slide into contact with each other. Thus, the first heat transfer component 12 and the second heat transfer component 14 are mechanically and thermally coupled, and the thermal switch 10 is switched from off to on. As shown in FIG. 2, when the thermal switch 10 is in the on state, the first heat transfer component 12 and the second heat transfer component 14 are both stationary, and the first heat transfer surface 20 and the second heat transfer surface 22 are in contact with each other. maintain the condition.

When the second heat transfer component 14 is withdrawn from the first heat transfer component 12, the first heat transfer surface 20 and the second heat transfer surface 22 are separated by a reverse movement. As shown in FIG. 1, the first heat transfer component 12 and the second heat transfer component 14 are mechanically and thermally separated, and the thermal switch 10 is switched from on to off.

A tapered surface 25 may be formed at the entrance of the insertion port 24. The tapered surface 25 connects the outer circumferential surface of the first heat transfer component 12 to the first heat transfer surface 20, which is the inner circumferential surface of the first heat transfer component 12, and extends from the outside to the inside of the insertion port 24 in the radial direction. It slopes towards the depths.

As a result, when the second heat transfer component 14 is inserted into the first heat transfer component 12, the outer circumference of the tip of the second heat transfer component 14 first abuts against the tapered surface 25. The tapered surface 25 acts as a guide surface for guiding the second heat transfer component 14 to the insertion port 24, so that the second heat transfer component 14 is easily received in the insertion port 24. Further, even if there is some axial misalignment between the second heat transfer component 14 and the first heat transfer component 12, the second heat transfer component 14 is guided by the tapered surface 25 and inserted into the insertion port 24. be able to.

Note that a tapered surface may be formed at the tip of the second heat transfer component 14 instead of or together with the tapered surface 25. The tapered surface of the second heat transfer component 14 is inclined similarly to the tapered surface 25, and connects the second heat transfer surface 22, which is the outer peripheral surface of the second heat transfer component 14, to the tip surface of the second heat transfer component 14. You can.

In this embodiment, as shown in FIG. 2, when the thermal switch 10 is in the on state, the front end surface of the second heat transfer component 14 and the bottom surface of the insertion port 24 of the first heat transfer component 12 do not come into contact with each other. There is no need to keep pressing the first heat transfer component 12 and the second heat transfer component 14 against each other in the insertion direction 26 to maintain the on state. It is possible to reduce the rigidity of the thermal switch 10, its support structure, and pressurizing device in the insertion direction 26, and the device structure can be simplified. Alternatively, the tip end surface of the second heat transfer component 14 and the bottom surface of the insertion port 24 of the first heat transfer component 12 may be in contact, and in that case, the contact area between the first heat transfer component 12 and the second heat transfer component 14 This can be advantageous in reducing thermal resistance.

The first heat transfer component 12 and the second heat transfer component 14 are formed of a metal with high thermal conductivity, such as copper, aluminum, or other high thermal conductivity material. Similarly, the first heat transfer member 16 and the second heat transfer member 18 to which the first heat transfer component 12 and the second heat transfer component 14 are fixed, as well as other heat transfer paths mentioned herein, may be made of, for example, copper. Made of high thermal conductivity material.

The material forming the first heat transfer surface 20 and the second heat transfer surface 22 is not necessarily the same as the high thermal conductivity material forming the bodies of the first heat transfer component 12 and the second heat transfer component 14, respectively. , may be different. For example, the first heat transfer surface 20 and the second heat transfer surface 22 may be plated layers of high heat conductive metal, such as silver plated layers formed on a copper body.

Metallic materials with good thermal conductivity, such as copper, are typically relatively soft. Therefore, when the entire heat transfer component is formed only from such materials, the component tends to have low rigidity. When the second heat transfer component 14 is inserted into the first heat transfer component 12, they deform each other relatively easily, so that the contact surface pressure between the first heat transfer surface 20 and the second heat transfer surface 22 tends to be small. It is. In order to reduce the thermal resistance between the first heat transfer surface 20 and the second heat transfer surface 22, a high contact surface pressure is desired.

Therefore, the thermal switch 10 includes a pressing mechanism 30 provided on at least one of the first heat transfer component 12 and the second heat transfer component 14 so as to bring the first heat transfer surface 20 and the second heat transfer surface 22 into surface contact. Equipped with. The pressing mechanism 30 is incorporated into the first heat transfer component 12, as an example.

In this embodiment, the pressing mechanism 30 is configured to bring the first heat transfer surface 20 and the second heat transfer surface 22 into elastic surface contact. The pressing mechanism 30 is provided as a leaf spring layer integrated with the first heat transfer surface 20. The leaf spring layer is disposed on the outer circumference of the first heat transfer component 12 so as to surround the insertion opening 24, and is formed into a cylindrical shape as a whole. The leaf spring layer is made of a metal or other material that is harder than the material forming the heat transfer surface, such as brass or stainless steel. Therefore, the leaf spring layer has higher rigidity than the heat transfer section including the first heat transfer surface 20. Additionally, the material forming the leaf spring layer typically has a lower thermal conductivity than the material forming the heat transfer surface.

FIG. 3 is a diagram schematically showing a cross section taken along line AA of the first heat transfer component 12 shown in FIG. The pressing mechanism 30 may have a large number of slits 32 formed in the first heat transfer component 12. These slits 32 are parallel to the insertion direction 26 (ie the axis of the first heat transfer component 12). The first heat transfer component 12 is circumferentially divided into a large number of strip-shaped heat transfer elements by slits 32, and each heat transfer element has a first heat transfer surface 20 on the inside in the radial direction and a leaf spring layer. It has it on the outside in the radial direction. The first heat transfer component 12 may be divided into at least three strip-shaped heat transfer elements. In FIG. 3, as an example, it is divided into four parts.

However, although the slit 32 extends from the entrance of the insertion port 24 of the first heat transfer component 12 to the axially intermediate portion, it extends to the base of the first heat transfer component 12 fixed to the first heat transfer member 16. has not extended. In order to facilitate fixation to the first heat transfer member 16, the strip-shaped heat transfer elements are connected to each other in the circumferential direction on the first heat transfer member 16 side.

With such a pressing mechanism 30, the first heat transfer component 12 can be elastically deflected in a direction 28 perpendicular to the insertion direction 26. When the second heat transfer component 14 is inserted into the first heat transfer component 12, the second heat transfer component 14 elastically deforms the first heat transfer component 12 so as to spread it outward in the radial direction. As the second heat transfer surface 22 slides in the insertion direction 26 with respect to the first heat transfer surface 20, the first heat transfer surface 20 follows the shape of the second heat transfer surface 22, as shown in FIG. The first heat transfer surface 20 and the second heat transfer surface 22 come into elastic surface contact.

In this way, when the second heat transfer component 14 is inserted into the first heat transfer component 12 and the first heat transfer surface 20 and the second heat transfer surface 22 contact each other while sliding, the elasticity generated by the pressing mechanism 30 The force presses the first heat transfer surface 20 and the second heat transfer surface 22 together. Thereby, the first heat transfer component 12 can tighten the second heat transfer component 14 relatively strongly. Therefore, the pressing mechanism 30 can increase the contact pressure between the first heat transfer surface 20 and the second heat transfer surface 22 and reduce thermal resistance.

Note that the pressing mechanism 30 may be provided in the second heat transfer component 14. For example, the second heat transfer component 14 may have a cylindrical shape with a number of slits, thereby forming a number of strip-shaped heat transfer elements that are radially flexible. The pressing mechanism 30 may be provided on both the first heat transfer component 12 and the second heat transfer component 14.

FIG. 4 is a diagram schematically showing another example of the pressing mechanism 30 provided in the thermal switch 10 according to the embodiment. The pressing mechanism 30 may be configured as a restraining ring attached to the outer periphery of the first heat transfer component 12 having the slit 32. This restraint ring includes a C-shaped ring member 33 that is held in contact with the outer periphery of the first heat transfer component 12, and a fastening member 34 such as a bolt that fastens both ends of the ring member 33. When the first heat transfer component 12 is in its initial shape, there is play 35 in the circumferential direction between both ends of the ring member 33 and the fastening member 34 . Unlike the pressing mechanism 30 shown in FIG. 3, the first heat transfer component 12 does not need to have a leaf spring layer.

When the second heat transfer component 14 is inserted into the first heat transfer component 12 and the first heat transfer surface 20 is elastically pushed outward in the radial direction, the play 35 is reduced and both ends of the ring member 33 are connected to the fastening member. 34 is pressed. In this way, the pressing mechanism 30 can tighten the first heat transfer component 12 from the outer periphery. Therefore, the pressing mechanism 30 can increase the contact pressure between the first heat transfer surface 20 and the second heat transfer surface 22 and reduce thermal resistance.

FIG. 5 is a diagram schematically showing a modification of the thermal switch 10 according to the embodiment. The first heat transfer component 12 includes a plurality of insertion ports 24 each having a first heat transfer surface 20 . The second heat transfer component 14 includes a plurality of protrusions 36 each having a second heat transfer surface 22 and insertable into a corresponding one of the plurality of insertion ports 24 . In other words, one thermal switch 10 has a plurality of sets of first heat transfer surfaces 20 and second heat transfer surfaces 22.

In this way, by installing a large number of heat transfer surfaces, the contact area between the first heat transfer component 12 and the second heat transfer component 14 can be easily increased. Thereby, thermal resistance that may occur between the first heat transfer component 12 and the second heat transfer component 14 can be reduced.

The insertion opening 24 and the protrusion 36 can be arranged in various ways. As shown in FIG. 5, the array may be linearly arranged left and right, or various two-dimensional arrays such as a matrix or a circumference are also possible. Moreover, it is not essential that the insertion ports 24 and the protrusions 36 to be installed all have the same shape, and may have different shapes.

Further, it is not essential that both the first heat transfer surface 20 and the second heat transfer surface 22 be parallel to the insertion direction 26 of the second heat transfer component 14 into the first heat transfer component 12. 6(a) and 6(b) are diagrams schematically showing a modification of the thermal switch 10 according to the embodiment. FIG. 6(a) shows the thermal switch 10 in an off state, and FIG. 6(b) shows the thermal switch 10 in an on state. As shown, the first heat transfer surface 20 and the second heat transfer surface 22 may be somewhat inclined with respect to the insertion direction 26. As an example, the first heat transfer component 12 has a conical first heat transfer surface 20, and the second heat transfer component 14 has a corresponding frustoconical second heat transfer surface 22. You can. Even in this case, when the second heat transfer component 14 is inserted into the first heat transfer component 12, the first heat transfer surface 20 and the second heat transfer surface 22 contact each other while sliding. It can be configured as follows.

FIG. 7 is a diagram schematically showing a cryogenic apparatus 100 according to an embodiment. Cryogenic device 100 is configured to cool superconducting coil 102 or other object to be cooled. The cryogenic device 100 cools the superconducting coil 102 from room temperature to a cryogenic temperature and maintains the superconducting coil 102 at the cryogenic temperature while the superconducting coil 102 is in use. The cryogenic device 100 is installed in various high magnetic field utilization devices, and can generate the high magnetic field required by the devices using the superconducting coil 102. The cryogenic apparatus 100 may be used, for example, as a high magnetic field source for a silicon single crystal pulling apparatus using the magnetic field application Czochralski method. Alternatively, cryogenic device 100 may be mounted on a superconducting cyclotron.

The cryogenic device 100 includes a thermal switch 10. As described with reference to FIGS. 1 to 3, the thermal switch 10 has a first heat transfer component 12 having a first heat transfer surface 20 and a shape that can be inserted into the first heat transfer component 12. A second heat transfer component 14 having two heat transfer surfaces 22 is provided. When the second heat transfer component 14 is inserted into the first heat transfer component 12, the first heat transfer surface 20 and the second heat transfer surface 22 slide into contact with each other. The first heat transfer component 12 is attached to the first heat transfer member 16 on the cooled side, and the second heat transfer component 14 is attached to the second heat transfer member 18 on the cooling side. The thermal switch 10 also includes an operating member 40 .

Further, the cryogenic apparatus 100 includes a cryogenic refrigerator 110, a vacuum container 120, and a radiation shield 130. In this embodiment, the cryogenic apparatus 100 is not an immersion cooling type in which the superconducting coil 102 is cooled by immersing it in a cryogenic liquid coolant such as liquid helium. It is configured as a conduction cooling type with direct cooling.

The cryogenic refrigerator 110 includes a cooling stage 112 that cools an object by conduction cooling, more specifically, a single-stage cooling stage 112a and a two-stage cooling stage 112b. The cryogenic refrigerator 110 is installed in a vacuum container 120, and the first cooling stage 112a and the second cooling stage 112b are placed in the vacuum container 120.

The cryogenic refrigerator 110 includes a compressor (not shown) for a working gas (for example, helium gas) and an expander also called a cold head, and the compressor and expander constitute a refrigeration cycle of the cryogenic refrigerator 110. As a result, the first cooling stage 112a and the second cooling stage 112b are respectively cooled to desired cryogenic temperatures. The first cooling stage 112a is cooled to, for example, 30K to 80K, and the second cooling stage 112b is cooled to, for example, 3K to 20K. The single-stage cooling stage 112a and the second-stage cooling stage 112b are made of a metal material such as copper or other material with high thermal conductivity.

The cryogenic refrigerator 110 is, by way of example, a two-stage Gifford-McMahon (GM) refrigerator, but may also be a pulse tube refrigerator, a Stirling refrigerator, or other types of cryogenic refrigerators. You can. Cryogenic refrigerator 110 may be a single-stage GM refrigerator or other type of cryogenic refrigerator.

First heat transfer member 16 is thermally coupled to superconducting coil 102 via flexible heat transfer member 114 . The flexible heat transfer member 114 may be formed to be flexible, for example, as a bundle of thin wires or a laminate of foil, and may be formed of a highly thermally conductive material such as copper. Therefore, the first heat transfer component 12 is thermally coupled to the superconducting coil 102 via the first heat transfer member 16 and the flexible heat transfer member 114. Further, since the first heat transfer member 16 is fixed to the operating member 40, the first heat transfer component 12 on the first heat transfer member 16 moves to the second heat transfer component 12 as the operating member 40 moves. It is possible to move against.

The second heat transfer member 18 is fixed to the two-stage cooling stage 112b. Therefore, the second heat transfer component 14 is thermally coupled to the two-stage cooling stage 112b via the second heat transfer member 18. The second heat transfer component 14 on the second heat transfer member 18 is stationary.

Vacuum vessel 120 is configured to define a vacuum region therein and may be, for example, a cryostat. The superconducting coil 102, the thermal switch 10, the cooling stage 112 of the cryogenic refrigerator 110, and the radiation shield 130 are placed in a vacuum region and vacuum-insulated from the external environment.

The radiation shield 130 is thermally coupled to the first cooling stage 112a and is cooled to the cooling temperature of the first cooling stage 112a. The radiation shield 130 is arranged to surround the superconducting coil 102 that is cooled to a lower temperature, the two-stage cooling stage 112b of the cryogenic refrigerator 110, and other low-temperature parts, and protects these low-temperature parts from radiant heat from the outside. Can be thermally protected. Radiation shield 130 is formed of a metallic material, such as copper, or other material with high thermal conductivity. Radiation shield 130 is directly attached to single-stage cooling stage 112a and is thermally coupled to single-stage cooling stage 112a. Alternatively, the radiation shield 130 may be attached to the single-stage cooling stage 112a via a flexible or rigid heat transfer member.

The operating member 40 provided on the thermal switch 10 is operable from outside the vacuum vessel 120 so that the second heat transfer component 14 is inserted into the first heat transfer component 12 . In this embodiment, the first heat transfer component 12 is provided on the operating member and the second heat transfer component 14 is fixed to the vacuum vessel 120, as described above.

The operating member 40 is made of a heat insulating material such as fiber reinforced plastic (FRP). Alternatively, the operating member 40 may be formed of a material having a lower thermal conductivity than the highly thermally conductive material forming the heat transfer path in the cryogenic device 100, such as stainless steel.

The operating member 40 is a rod that extends linearly along the axis of the first heat transfer component 12 and the second heat transfer component 14. The operating member 40 may be a solid rod. Alternatively, the operating member 40 may have a hollow structure as shown. As a result, the cross-sectional area of the operating member 40 becomes smaller than that in the case where the operating member 40 is a solid rod, and the intrusion from the external environment of the vacuum container 120 into the low temperature part inside the vacuum container 120 through the operating member 40 becomes smaller. Heat can be reduced. One or more baffles 42 or partition plates may be installed in the hollow portion of the operating member 40, for example at an axially intermediate portion of the operating member 40. Baffle 42 serves to shield radiant heat that may enter through the hollow portion of operating member 40.

The operating member 40 penetrates the radiation shield 130 within the vacuum container 120. Radiation shield 130 has an opening 132 that receives operating member 40 . The opening 132 is, for example, a through hole formed in the radiation shield 130.

In order to block radiant heat that may enter the radiation shield 130 from the wall of the vacuum container 120 through the opening 132, a first cover 44 and a second cover 134 are provided to cover the gap between the operating member 40 and the radiation shield 130. Good too. It is not essential to provide both the first cover 44 and the second cover 134, and only one of them may be provided.

The first cover 44 covers the gap between the operating member 40 and the radiation shield 130, and serves as a so-called eaves. The first cover 44 is provided on the operating member 40 at a position close to the opening 132 of the radiation shield 130 on the wall side of the vacuum container 120, and extends radially outward from the operating member 40 in the shape of a brim. It is formed. The distance between the first cover 44 and the radiation shield 130 is determined so as not to impede movement of the operating member 40 for switching on/off the thermal switch 10.

The second cover 134 is provided in the opening 132 of the radiation shield 130 so as to close the gap between the operating member 40 and the radiation shield 130, and extends radially inward from the radiation shield 130 toward the operating member 40. . Since the operating member 40 is made of a heat insulating material, even if the second cover 134 comes into contact with the operating member 40, the thermal effect is small.

A thermal switch 10 is provided at one end of the operating member 40, while a support structure 50 is provided at the other end of the operating member 40. The operating member 40 is supported on the wall of the vacuum vessel 120 by a support structure 50 . Support structure 50 has a bellows 52 and a support flange 54. Bellows 52 connect the wall of vacuum vessel 120 to support flange 54 . Within the bellows 52, the operating member 40 is fixed to a support flange 54. The operating member 40 extends into the vacuum vessel 120 from the support flange 54 through an insertion hole formed in the wall of the vacuum vessel 120. The support flange 54 may be considered to be a part of the operating member 40 provided for operating the operating member 40 from outside the vacuum vessel 120.

The support structure 50 may be provided with a pressure device 56 configured to move the support flange 54. The operating member 40 can be operated from outside the vacuum container 120 using the pressurizing device 56. The pressurizing device 56 may have a movable mechanism such as a push screw type, and the movable mechanism may be manually operated to move the support flange 54. To operate the movable mechanism, the pressurizing device 56 may have a suitable drive source such as hydraulics, pneumatics, an electric motor, or an electromagnet.

When the support flange 54 is brought close to the vacuum vessel 120, the bellows 52 contracts and the operating member 40 is pushed into the vacuum vessel 120. The first heat transfer component 12 approaches the second heat transfer component 14 and the second heat transfer component 14 is inserted into the first heat transfer component 12 . At this time, the first heat transfer surface 20 and the second heat transfer surface 22 contact each other while sliding, and the first heat transfer component 12 and the second heat transfer component 14 are mechanically and thermally coupled, and the thermal switch 10 switches from off to on.

In this way, the two-stage cooling stage 112b of the cryogenic refrigerator 110 is transferred to the superconducting coil 102 via the second heat transfer member 18, the thermal switch 10, the first heat transfer member 16, and the flexible heat transfer member 114. is thermally coupled with. The superconducting coil 102 is cooled by the two-stage cooling stage 112b of the cryogenic refrigerator 110 to the cooling temperature of the two-stage cooling stage 112b. By energizing the superconducting coil 102 from a power source (not shown), the superconducting coil 102 can generate a strong magnetic field.

Conversely, when the support flange 54 is separated from the vacuum vessel 120, the bellows 52 is extended and the operating member 40 is pulled up. The first heat transfer component 12 and the second heat transfer component 14 are mechanically and thermally separated, and the thermal switch 10 is switched from on to off. Thereby, the superconducting coil 102 is thermally separated from the two-stage cooling stage 112b of the cryogenic refrigerator 110.

During long-term operation of the cryogenic apparatus 100, maintenance of the cryogenic refrigerator 110 may be required periodically. In this case, the thermal switch 10 is switched from on to off. The cryogenic refrigerator 110 is heated to a temperature convenient for maintenance work, such as room temperature, and is cooled again after the work is completed. Since thermal contact between the superconducting coil 102 and the cryogenic refrigerator 110 is released by the thermal switch 10, maintenance of the cryogenic refrigerator 110 can be performed while the superconducting coil 102 is maintained at a low temperature.

FIG. 8 is a schematic diagram showing a thermal switch 80 according to a comparative example. This thermal switch 80 is composed of a heat transfer body 81 and a heat transfer plate 82. The heat transfer body 81 is movable relative to the heat transfer plate 82, and the heat transfer body 81 and the heat transfer plate 82 have surfaces facing each other. Heat transfer body 81 approaches heat transfer plate 82, the two surfaces momentarily come into contact, and thermal switch 80 is turned on. The interface between the heat transfer body 81 and the heat transfer plate 82 is perpendicular to the relative movement direction 83 of the heat transfer body 81 . The contact pressure acting between the heat transfer body 81 and the heat transfer plate 82 is generated by pressing the heat transfer body 81 against the heat transfer plate 82, and the direction of this force corresponds to the relative movement direction 83.

In the configuration of the thermal switch 80 according to the comparative example, the contact surface pressure between the heat transfer body 81 and the heat transfer plate 82, and thus the thermal resistance, are closely correlated to the pressing force. In order to accurately achieve the desired thermal resistance, it is necessary to accurately adjust the pressing force each time the thermal switch 80 is turned on. However, this is not always easy. In addition, in order to sufficiently reduce the thermal resistance, it is required to considerably increase the contact surface pressure, that is, the force that presses the heat transfer body 81 and the heat transfer plate 82 together, which tends to result in a large-scale mechanism. . In other words, the thermal switch 80 according to the comparative example lacks reproducibility of thermal resistance when the thermal switch is turned on, and there is a limit to the reduction in thermal resistance that can be achieved.

In some cases, the cooling stage of the cryocooler itself is the heat transfer body 81, in which case the cryocooler must be designed robustly to withstand large loads to ensure a sufficiently low thermal resistance. . Furthermore, in a two-stage cryogenic refrigerator, the first-stage cooling stage and the second-stage cooling stage come into contact with their corresponding heat transfer plates simultaneously. The contact surface pressure between the first stage part and the second stage part is uniquely determined by the structural mechanical distribution of the pressing force from the cryogenic refrigerator to the heat exchanger plate. The pressing force may be distributed unbalanced, and the thermal resistance of either the first step portion or the second step portion may become higher. However, in order to solve this problem, it is difficult to independently adjust the contact surface pressure, that is, the thermal resistance, between the first step part and the second step part.

Therefore, in the thermal switch 80 according to the comparative example, the contact surface pressure is insufficient, the thermal resistance is high, and a temperature difference is likely to occur between the heat transfer body 81 and the heat transfer plate 82. In this case, the cooling temperature of the object to be cooled, such as the superconducting coil connected to the heat transfer plate 82, may not be sufficiently lowered to the temperature that can be achieved by the cryogenic refrigerator. In order to avoid insufficient cooling of the superconducting coils, it may be necessary to consider adopting a cryogenic refrigerator with greater cooling capacity or installing additional cryogenic refrigerators.

On the other hand, according to the thermal switch 10 according to the embodiment, as the first heat transfer component 12 and the second heat transfer component 14 move relative to each other, the first heat transfer surface 20 and the second heat transfer surface 22 contact each other while sliding. At this time, a force that presses the first heat transfer surface 20 and the second heat transfer surface 22 against each other, that is, a contact surface pressure acts, thereby making it possible to obtain thermal contact.

What should be noted here is that the contact surface pressure occurs in a direction different from the direction of relative movement, for example, in a direction substantially orthogonal to it. Therefore, the contact pressure and thermal resistance are independent or largely independent of the magnitude of the force causing the relative movement. As long as the first heat transfer component 12 and the second heat transfer component 14 can be inserted and removed, the force in the moving direction may be small. Therefore, the rigidity of the operating member 40 can be reduced, and the support structure 50 of the operating member 40 and the pressurizing device 56 can have a simple configuration.

The contact pressure that acts between the first heat transfer surface 20 and the second heat transfer surface 22, that is, the thermal resistance, mainly depends on the shapes, dimensions, materials, etc. of the first heat transfer component 12 and the second heat transfer component 14. This can be readily determined by the design of the thermal components. As in the comparative example, dynamic factors such as pressing force have no or little involvement in determining thermal resistance. Therefore, using the thermal switch 10 makes it easier to manage thermal resistance and improves reproducibility. Further, as described with reference to FIG. 5, for example, it is relatively easy to install a large number of thermal switches 10 side by side to increase the area of the heat transfer surface and lower the thermal resistance. It is possible to provide a thermal switch 10 that allows good thermal contact to be achieved relatively easily.

In particular, when both the first heat transfer surface 20 and the second heat transfer surface 22 are parallel to the direction of relative movement between the first heat transfer component 12 and the second heat transfer component 14, the first heat transfer surface 20 and the second heat transfer surface 22 are perpendicular to the direction of relative movement. The heat transfer surfaces press against each other in the direction of The on/off operation of the thermal switch 10 and the management of thermal resistance can be separated. Furthermore, when the second heat transfer component 14 is inserted into the first heat transfer component 12, the first heat transfer surface 20 and the second heat transfer surface 22 can easily slide into contact with each other.

Furthermore, in the thermal switch 80 of the comparative example, a soft intervening layer such as an indium sheet is often used sandwiched between the heat transfer body 81 and the heat transfer plate 82 in order to improve thermal contact. However, although these intervening layers are typically soft at room temperature, they become harder at cryogenic temperatures. When the thermal switch 80 is used, at least one of the heat transfer body 81 and the heat transfer plate 82 is cooled to an extremely low temperature. Due to this, the intervening layer is likely to deteriorate as the thermal switch 80 is repeatedly turned on and off, which becomes a factor in reducing the reproducibility of the thermal resistance of the thermal switch 80. Additionally, indium is one of the more expensive materials used in cryogenic equipment.

In the thermal switch 10 according to the embodiment, such an intervening layer may also be used between the first heat transfer surface 20 and the second heat transfer surface 22. However, according to the thermal switch 10 according to the embodiment, good thermal contact can be achieved without using such an intervening layer. Therefore, the above-mentioned disadvantages caused by the intervening layer do not occur.

The thermal switch 10 can also cope with thermal contraction due to cooling of the operating member 40. When the thermal switch 10 is in the on state, the heat transfer path from the cryogenic refrigerator 110 to the superconducting coil 102 is cooled. Accordingly, the operating member 40 may also undergo thermal contraction due to cooling, particularly at the end on the low temperature side. As a result, the first heat transfer component 12 and the second heat transfer component 14 of the thermal switch 10 may be moved some distance apart from each other. However, in this embodiment, the first heat transfer surface 20 and the second heat transfer surface 22 extend along this direction and are in contact with each other, so that the thermal switch 10 is not maintained in the on state. sell.

FIG. 9 is a diagram schematically showing a modification of the thermal switch 10 according to the embodiment. In the embodiment described above, the thermal switch 10 is switched on and off by reciprocating the operating member 40 in the axial direction, but as described below, the thermal switch 10 is configured to be switched on and off by rotating the operating member 40. may be done.

The operating member 40 is rotatable around an axis, as shown by an arrow 60 in FIG. An outer cylinder 61 having the first heat transfer component 12 (or the second heat transfer component 14) is attached to the tip of the operating member 40. Although the outer cylinder 61 is movable in the axial direction of the operating member 40 with respect to the operating member 40, the outer cylinder 61 is provided with a first heat transfer member (not shown in FIG. 9), for example, so as not to rotate together with the operating member 40. ) is supported by

The outer cylinder 61 has a pin receiving groove 62 extending in the circumferential direction in a part of its outer peripheral surface. A pin 63 that protrudes radially from the tip of the operating member 40 is inserted into the pin receiving groove 62 .
One end 62a of the pin receiving groove 62 is inclined toward the tip of the outer cylinder 61 with respect to the remaining portion 62b of the pin receiving groove 62.

When the operating member 40 rotates in the X direction, the pin 63 moves from the end portion 62a to the remaining portion 62b along the pin receiving groove 62 (in the X direction of the arrow 64), thereby causing the outer cylinder 61 to move into the first transmission position. It advances toward the second heat transfer component 14 together with the heat component 12 (in the X direction of arrow 65). In this way, the first heat transfer component 12 and the second heat transfer component 14 are coupled, and the thermal switch 10 is switched from off to on. Conversely, when the operating member 40 rotates in the Y direction, the pin 63 is returned to the end 62a along the pin receiving groove 62 (in the Y direction of arrow 64), and the outer cylinder 61 is moved together with the first heat transfer component 12. It is pulled back toward the operating member 40 (in the X direction of arrow 65). In this way, the first heat transfer component 12 and the second heat transfer component 14 are separated, and the thermal switch 10 is switched from on to off.

In the embodiment described above, the first heat transfer component 12 is movable and attached to the cooled side, and the second heat transfer component 14 is fixed and attached to the cooled side. There are many other ways to do it. A modification of the installation of the thermal switch 10 will be described with reference to FIGS. 10(a) to 10(c).

As shown in FIG. 10(a), the first heat transfer component 12 may be movable and attached to the cooling side, and the second heat transfer component 14 may be fixed and attached to the cooled side. The first heat transfer component 12 is provided on the first heat transfer member 16 fixed to the tip of the operating member 40 and is connected to the two-stage cooling stage 112b of the cryogenic refrigerator 110 via the flexible heat transfer member 114. There is. The second heat transfer component 14 is fixed to an object to be cooled, such as the superconducting coil 102, via the second heat transfer member 18.

As shown in FIG. 10(b), when the operating member 40 is pulled up, the thermal switch 10 is switched from off to on, and when the operating member 40 is pushed in, the thermal switch 10 is switched from on to off. good. The first heat transfer component 12 is fixed to an object to be cooled, such as the superconducting coil 102, via the first heat transfer member 16. The tip of the operating member 40 is fixed to the second heat transfer member 18 , and the second heat transfer component 14 is installed on the second heat transfer member 18 so as to face the first heat transfer component 12 . The operating member 40 is arranged parallel to, not coaxially with, the thermal switch 10. The second heat transfer member 18 is connected to a two-stage cooling stage 112b of the cryogenic refrigerator 110 via a flexible heat transfer member 114.

As shown in FIG. 10(c), a cryogenic refrigerator 110 may be used as the operating member. The cryogenic refrigerator 110 may be connected to and supported by the vacuum container 120 with a bellows 52, and the first heat transfer component 12 may be fixed to the two-stage cooling stage 112b of the cryogenic refrigerator 110. The second heat transfer component 14 is installed on the second heat transfer member 18 so as to face the first heat transfer component 12 . The second heat transfer component 14 is fixed to an object to be cooled, such as the superconducting coil 102, via the second heat transfer member 18. By moving the cryogenic refrigerator 110 in the axial direction, the thermal switch 10 can be turned on and off.

FIG. 11 is a diagram schematically showing a modification of the cryogenic apparatus 100 according to the embodiment. The cryogenic device 100 may include multiple cryogenic refrigerators 110 and multiple thermal switches 10 to cool one (or more) superconducting coils 102. The multiple cryogenic refrigerators 110 may be divided into multiple groups, and one thermal switch 10 may be provided for each group. In the example shown in FIG. 11, four cryogenic refrigerators 110 are divided into two groups of two. The thermal switch 10 can be turned on and off for each group of cryogenic refrigerators 110. Therefore, while the superconducting coil 102 is cooled by the cryogenic refrigerator 110 of one group, the cryogenic refrigerator 110 of the other group can be separated from the superconducting coil 102 for maintenance. In this way, maintenance of the cryogenic refrigerator 110 can be performed without stopping the superconducting coil 102.

FIG. 12 is a diagram schematically showing a modification of the cryogenic apparatus 100 according to the embodiment. The cryogenic device 100 may include a first thermal switch 10A and a second thermal switch 10B. The first thermal switch 10A is provided for thermal on/off switching between the two-stage cooling stage 112b of the cryogenic refrigerator 110 and the object to be cooled, such as the superconducting coil 102, as in the above-described embodiment.

The second thermal switch 10B may be provided to switch coupling and separation between the first cooling stage 112a and the second cooling stage 112b of the cryogenic refrigerator 110. The first heat transfer component 12 of the second thermal switch 10B is provided on the first heat transfer member 16 fixed to the tip of the operating member 40, and is connected to the first cooling stage of the cryogenic refrigerator 110 via the flexible heat transfer member 114. 112a. The second heat transfer component 14 of the second thermal switch 10B may be fixed to the two-stage cooling stage 112b of the cryogenic refrigerator 110 via the second heat transfer member 18 so as to face the first heat transfer component 12. good.

The second thermal switch 10B can be used for initial cooling in the cryogenic device 100, that is, rapid cooling from room temperature to a cryogenic temperature. Generally, the cooling capacity of the first stage of the cryogenic refrigerator 110 is larger than the cooling capacity of the second stage. Therefore, when cooling the second stage section from room temperature to the first stage cooling temperature in the initial cooling, the second thermal switch 10B is turned on. In this way, the second stage section can be rapidly cooled to the first stage cooling temperature using the first stage cooling capacity. Thereafter, the second thermal switch 10B is turned off, and the cryogenic apparatus 100 cools the second stage section by the second cooling stage 112b, as in normal operation.

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 embodiments, and that various design changes and modifications are possible, and that such modifications also fall within the scope of the present invention. By the way. Various features described in connection with one embodiment are also applicable to other embodiments. A new embodiment resulting from a combination has the effects of each of the combined embodiments.

In the embodiment described above, the thermal switch 10 is provided for thermally switching on/off the two-stage cooling stage 112b of the cryogenic refrigerator 110 and the object to be cooled thereby, but the present invention is not limited to this. Not limited to. The thermal switch 10 may be provided for thermally switching on and off the single cooling stage 112a of the cryogenic refrigerator 110 and the object to be cooled thereby (eg, the radiation shield 130). For example, the first heat transfer component 12 may be provided at the tip of the operating member 40 and connected to the radiation shield 130 via the flexible heat transfer member 114. The second heat transfer component 14 may be fixed to the single-stage cooling stage 112a so as to face the first heat transfer component 12. Alternatively, the thermal switch 10 is applicable not only to two-stage cryogenic refrigerators but also to single-stage or other multi-stage cryogenic refrigerators.

Although the present invention has been described using specific words based on the embodiments, the embodiments merely illustrate one aspect of the principles and applications of the present invention, and the embodiments do not include the claims. Many modifications and changes in arrangement are possible without departing from the spirit of the invention as defined in scope.

10 heat switch, 12 first heat transfer component, 14 second heat transfer component, 20 first heat transfer surface, 22 second heat transfer surface, 24 insertion port, 26 insertion direction, 30 pressing mechanism, 40 operating member, 100 pole cryogenic device, 110 cryogenic refrigerator, 112 cooling stage, 120 vacuum container, 130 radiation shield.

Claims (9)

an insertion port; a first heat transfer component having a first heat transfer surface on an inner peripheral surface of the insertion port ; and a first heat transfer component having a shape that can be inserted into the first heat transfer component and having a second heat transfer surface on the outer peripheral surface a second heat transfer component, wherein when the second heat transfer component is inserted into the first heat transfer component, the first heat transfer surface and the second heat transfer surface contact each other while sliding. a heat switch;
a pressing mechanism disposed on the outer periphery of the first heat transfer component so as to surround the insertion opening and configured to bring the first heat transfer surface and the second heat transfer surface into elastic surface contact;
A cryogenic apparatus comprising: a cryogenic refrigerator including a cooling stage thermally coupled to either the first heat transfer component or the second heat transfer component. The pressing mechanism includes a leaf spring layer integrated with the first heat transfer surface,
The cryogenic apparatus according to claim 1 , wherein the material forming the leaf spring layer is harder than the material forming the heat transfer surface . The first heat transfer component is circumferentially divided into a plurality of strip-shaped heat transfer elements by slits, and each heat transfer element has the first heat transfer surface on the inside in the radial direction and the leaf spring layer. The cryogenic device according to claim 2 , characterized in that the cryogenic device is provided on the outside in the radial direction . The pressing mechanism is
a C-shaped ring member held in contact with the outer periphery of the first heat transfer component;
a fastening member that fastens both ends of the ring member,
The cryogenic apparatus according to claim 1 , wherein when the first heat transfer component is in its initial shape, there is circumferential play between both ends of the ring member and the fastening member . The first heat transfer component includes a plurality of insertion ports each having the first heat transfer surface,
Claims 1 to 4, wherein the second heat transfer component includes a plurality of protrusions, each of which has the second heat transfer surface and is insertable into a corresponding one of the plurality of insertion ports. The cryogenic device according to any of the above. further comprising a vacuum container accommodating the cooling stage and the thermal switch,
The thermal switch includes an operating member that can be operated from outside the vacuum container so that the second heat transfer component is inserted into the first heat transfer component, and the heat transfer component is inserted into the first heat transfer component or the second heat transfer component. Claims 1 to 5, wherein one of the components is provided on the operating member, and the other of the first heat transfer component or the second heat transfer component is fixed to the vacuum container. The cryogenic device according to any one of the above. 7. The cryogenic device according to claim 6, wherein the operating member is made of a heat insulating material and has a hollow structure. The cryogenic apparatus according to claim 6 or 7, wherein the vacuum container includes a radiation shield through which the operating member passes, and a cover that covers a gap between the operating member and the radiation shield. . A thermal switch for a cryogenic device, the thermal switch comprising:
a first heat transfer component that can be attached to either the cooling side or the cooled side of the cryogenic device;
a second heat transfer component that can be attached to the other of the cooling side or the cooled side of the cryogenic device,
The first heat transfer component has an insertion port and a first heat transfer surface on an inner peripheral surface of the insertion port , and the second heat transfer component has a shape that can be inserted into the first heat transfer component. , having a second heat transfer surface on its outer peripheral surface ,
When the second heat transfer component is inserted into the first heat transfer component, the first heat transfer surface and the second heat transfer surface contact each other while sliding ,
The thermal switch is arranged on the outer periphery of the first heat transfer component so as to surround the insertion opening, and is configured to bring the first heat transfer surface and the second heat transfer surface into elastic surface contact. A thermal switch for a cryogenic device , further comprising a pressing mechanism .

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