JP2012032125A - Cryogenic refrigeration coupling structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerator coupling structure for enabling attaching/detaching and re-cooling of the refrigerator in a short time-period, by suppressing a heat movement from the refrigerator at the room temperature to an object to be cooled which is cooled down to cryogenic temperature when attaching a cryogenic refrigerator thereon, while suppressing a volume of heat invasion into the object to be cooled.SOLUTION: The structure includes a heat contact portion having a flexible portion at least in a part thereof, which is coupled with a cold stage of the cryogenic refrigerator 1, wherein a heat contracting ring which has a heat contraction rate larger than that of the heat contact portion is provided on the outer peripheral portion of this heat contact portion.

Description

  The present invention relates to a refrigerator connecting structure that enables a refrigerator to be attached and detached in a state where an object to be cooled is cooled to an extremely low temperature in an apparatus using a cryogenic refrigerator, particularly a refrigerator-cooled superconducting magnet.

  A refrigerator-cooled superconducting magnet that cools a superconducting magnet with a cryogenic refrigerator has a great feature in that liquid helium is not required. Since liquid helium is unnecessary, energy consumption in the process of generating liquid helium becomes unnecessary, and energy saving can be promoted. These refrigerator-cooled superconducting magnets can be used to create a cryogenic environment at the touch of a button without replenishing liquid helium. From the ease of magnetic levitation trains, measurement of physical properties, magnetization and magnetic separation in strong magnetic field environments. Various applications are expected.

  A cryogenic refrigerator that realizes a cryogenic environment without using liquid helium requires regular maintenance due to structural problems described below. A Gifford-McMahon (GM) type refrigerator generally used for a refrigerator-cooled superconducting magnet requires maintenance once a year or every 15000 hours. This is due to wear caused by the reciprocating motion of the displacer that performs compression / expansion and heat exchange inside the cryogenic refrigerator, and the worn parts must be replaced. Further, since the purity of the helium gas filled in the cryogenic refrigerator gradually deteriorates, it is necessary to replace the helium gas.

  In order to perform maintenance of the cryogenic refrigerator, it is necessary to raise the temperature of the cryogenic refrigerator once to room temperature. Although the temperature raising time can be shortened by heating the heater, there is a problem that the temperature of the object to be cooled that is integrated with the cryogenic refrigerator increases. In addition, the heat capacity of the object to be cooled connected to the cooling stage of the cryogenic refrigerator is larger than the heat capacity of the cryogenic refrigerator itself, and the temperature rise time becomes longer by integrating the cryogenic refrigerator and the object to be cooled. There was a problem. Furthermore, since cooling must depend on the cooling capacity of the cryogenic refrigerator, there is a problem that the longer the temperature rise time, the longer the cooling time.

  With a refrigerator-cooled superconducting magnet that cools the object to be cooled only with a cryogenic refrigerator, the temperature of the object to be cooled may rise during maintenance of the cryogenic refrigerator, and the superconducting magnet may be lost. It is necessary to demagnetize the magnetic field generated from. Therefore, the function as a magnet cannot be exhibited during maintenance. In order to perform re-excitation as soon as possible, it is necessary to reduce the temperature rise of the superconducting magnet and re-cool to a temperature that can be excited in a short time.

  A refrigerator cooling structure using a conventional cryogenic refrigerator is shown in FIG. The cryogenic refrigerator 1 is attached to the vacuum vessel 3 and has a structure in which the object to be cooled 20 and the heat shield 4 are cooled by the second cooling stage 2 and the first cooling stage 7. The surroundings of the object to be cooled 20 and the heat shield 4 are in a vacuum state, and the amount of heat transfer from the vacuum vessel 3 at room temperature is suppressed to be small.

  At the time of maintenance of the cryogenic refrigerator 1, it is necessary to separate the second cooling stage 2 and the object to be cooled 20 of the cryogenic refrigerator 1 and the contact surfaces of the first cooling stage 7 and the heat shield 4. At that time, a vacuum wall 31 is installed around the cryogenic refrigerator 1 in order to make the circumference of the cryogenic refrigerator 1 atmospheric pressure. A part of the object to be cooled 20 and the heat shield 4 is also used as a part of the vacuum vessel 3.

  There are two main types of maintenance methods for solving this problem.

  The first method is a method of physically separating the cryogenic refrigerator from the object to be cooled. In the patent described in Patent Document 1, the cryogenic refrigerator is brought into thermal contact with the object to be cooled, and the cryogenic refrigerator and the object to be cooled are separable by loosening the screws at the room temperature. Moreover, in the patent document of patent document 2, it is possible to loosen the screw which connects a cryogenic refrigerator and a to-be-cooled object from a room temperature part, and to isolate | separate a cryogenic refrigerator from a to-be-cooled object. Furthermore, in the patent described in Patent Document 3, a spring shape is applied to the connecting portion between the cryogenic refrigerator and the object to be cooled. Both methods are characterized in that the cryogenic refrigerator and the object to be cooled are separated from each other while the object to be cooled is in a cryogenic state.

  As a second method, a method of raising the temperature of only the cryogenic refrigerator in a state where the cryogenic refrigerator and the object to be cooled are connected can be considered. A so-called thermal switch is applied to thermally separate the cryogenic refrigerator from the object to be cooled, and only the cryogenic refrigerator is heated. Since the displacer and the like in the cryogenic refrigerator are replaced after the temperature rise, it is not necessary to replace the refrigerator body.

  In the patent described in Patent Document 4, helium gas, which is a heat transfer medium, is filled between a cryogenic refrigerator and an object to be cooled and used as a heat switch. By exhausting the helium gas, there is no thermal connection (thermal connection) between the cryogenic refrigerator and the object to be cooled, and only the cryogenic refrigerator can be heated.

Japanese Patent Laid-Open No. 9-287838 Japanese Patent Laid-Open No. 2004-294041 JP-A-1-196479 JP 2002-252111 A

  Various patents have been proposed for maintenance of refrigerators, but each has its own problems.

  In the technique described in Patent Document 1, since a surface pressure is brought into contact with the object to be cooled, a support structure that can withstand this surface pressure is required, and the cross-sectional area of the support portion is increased, so that heat can enter the object to be cooled. There was a problem that the amount increased. In the technique described in Patent Document 2, it is necessary to bring the cooling stage of the cryogenic refrigerator into thermal contact with the object to be cooled before cooling the cryogenic refrigerator, and the temperature of the object to be cooled increases due to the heat capacity of the refrigerator. was there. In the technique described in Patent Document 3, the refrigerator at room temperature and the object to be cooled cooled to a very low temperature are in thermal contact when the refrigerator is attached, and the temperature of the object to be cooled increases due to the heat capacity of the refrigerator. there were. In the technique described in Patent Document 4, it takes time to raise the cryogenic refrigerator to room temperature, and there is a problem that it takes a long time to perform maintenance of the refrigerator.

  The object of the present invention is to reduce the time required for maintenance and re-cooling in a refrigerator-cooled superconducting magnet, to suppress the temperature rise of the superconducting magnet, and from the room-temperature refrigerator to the cryogenic temperature when the cryogenic refrigerator is installed. An object of the present invention is to provide a refrigerator connecting structure that suppresses heat transfer to a cooled object to be cooled and allows the refrigerator to be attached and detached and recooled in a short time.

  In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above-mentioned problems. To give an example, the first feature of the cryogenic refrigerator coupling structure of the present invention that solves the above-described problems is the cooling of the cryogenic refrigerator. A heat contact portion connected to the stage is provided, and a heat shrink ring having a heat shrink rate larger than that of the heat contact portion is provided on the outer peripheral portion of the heat contact portion. Thereby, since the shrink ring with a large amount of heat shrink fastens the inner heat contact portion, the heat contact between the heat contact portion and the connection portion of the object to be cooled is improved.

  The second feature of the present invention is that the thermal contact portion is in thermal contact with the flexible portion. By having the flexible portion, it is easy for the thermal contact portion to change the position and angle, and the thermal contact between the thermal contact portion and the connection portion of the object to be cooled is improved.

  The third feature of the present invention is that the thermal contact portion is divided in the circumferential direction. A heat contact part is divided | segmented, the heat contraction ring installed in the outer periphery of a heat contact part is cooled, and a heat contact part is tightened by shrinking. Thereby, the thermal contact between the thermal contact portion and the connection portion of the object to be cooled is improved.

  The fourth feature of the present invention is that the thermal contact portion that is in thermal contact with the cooling stage of the cryogenic refrigerator is in contact with the thermal contact portion when the cooling stage of the cryogenic refrigerator is at room temperature. There is a clearance between the connection part of the cooling object. There is no thermal contact between the cryogenic refrigerator at room temperature and the object to be cooled at cryogenic temperature, preventing the heat capacity of the cryogenic refrigerator at room temperature from moving to the object to be cooled at cryogenic temperature. ing.

  In addition, the fifth feature of the present invention is that the thermal contact portion and the heat shrink ring thermally coupled with the cooling stage of the cryogenic refrigerator are cooled by starting the cryogenic refrigerator after the maintenance. The contraction ring 5 is contracted by thermal contraction, and the heat contact portion and the connection portion of the object to be cooled are automatically brought into thermal contact. As a result, when the temperature of the cooling stage of the cryogenic refrigerator is high, the thermal contact portion thermally coupled to the cooling stage of the cryogenic refrigerator and the connection portion of the object to be cooled are in a non-contact state, and the temperature is high. Heat intrusion from the cooling stage to the connection portion of the object to be cooled can be suppressed, and a temperature rise of the object to be cooled can be suppressed to a minimum. As the temperature of the cooling stage of the cryogenic refrigerator decreases, the heat shrink ring that is thermally coupled to the heat contact portion gradually heat shrinks, and the connection portion between the heat contact portion and the object to be cooled is below a certain temperature. It automatically makes thermal contact.

  By having the cryogenic refrigerator connection structure in the present invention, heat transfer from the cryogenic refrigerator in the normal temperature state to the object to be cooled during maintenance of the cryogenic refrigerator is suppressed, and the temperature of the object to be cooled is in the extremely low temperature state. Maintained.

  In the process of cooling the cryogenic refrigerator, the object to be cooled automatically comes into thermal contact with the heat conduction means in thermal contact with the cryogenic refrigerator due to the thermal contraction of the heat shrink ring. With the heat conducting means cooled by the cryogenic refrigerator, the heat conducting means and the object to be cooled are in thermal contact with each other, so that the temperature rise of the object to be cooled can be suppressed to a minimum.

It is sectional drawing of the cryogenic refrigerator connection part which shows the 1st Example of this invention. It is detailed sectional drawing of the cryogenic refrigerator coupling structure in the 2nd cooling stage in a 1st Example. It is sectional drawing which looked at the refrigerator coupling structure in a 1st Example from the upper surface. It is detailed sectional drawing of the cryogenic refrigerator connection structure in the 2nd cooling stage which shows the 2nd Example of this invention. It is a detailed sectional view of the cryogenic refrigerator connecting structure in the first cooling stage in the third embodiment of the present invention. It is detail sectional drawing of the cryogenic refrigerator connection structure in the 1st cooling stage in the 4th Example of this invention. It is sectional drawing which shows the conventional refrigerator connection structure. It is a figure (example from Hiroyasu Sugawara, "Introduction to cryogenic engineering", Tokyo Denki University Press, published in July 1999, p. 292) showing an example of heat shrinkage of the main constituent materials.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a cryogenic refrigerator connecting portion showing a first embodiment of the present invention.

  The cryogenic refrigerator 1 is attached to the vacuum vessel 3 and has a structure in which the object to be cooled 20 and the heat shield 4 are cooled by the second cooling stage 2 and the first cooling stage 7. The surroundings of the object to be cooled 20 and the heat shield 4 are in a vacuum state, and the amount of heat transfer from the vacuum vessel 3 at room temperature is suppressed to be small. At the time of maintenance of the cryogenic refrigerator 1, it is necessary to separate the second cooling stage 2 and the object to be cooled 20 of the cryogenic refrigerator 1 and the contact surfaces of the first cooling stage 7 and the heat shield 4. At that time, a vacuum wall 31 is installed around the cryogenic refrigerator 1 in order to change the circumference of the cryogenic refrigerator 1 from a vacuum state to an atmospheric pressure. A part of the object to be cooled 20 and the heat shield 4 is also used as a part of the vacuum vessel 3.

  The cryogenic refrigerator 1 is, for example, a GM refrigerator, and includes a first cooling stage 7 and a second cooling stage 2 that generate cold. The first cooling stage 7 is cooled between 30K and 80K. The second cooling stage 2 is cooled to 30K or less.

  The object to be cooled that is cooled by the first cooling stage 7 of the cryogenic refrigerator 1 is mainly the heat shield 4. The heat shield 4 receives radiation from the vacuum vessel 3 at room temperature. In order to reduce the amount of radiant heat received by the heat shield 4, a heat insulating material called a laminated heat insulating material (not shown) is installed between the heat shield 4 and the vacuum vessel 3. The heat shield 4 is also used, for example, as a thermal anchor for a current lead (not shown), and is also applied to suppress heat conduction that is transmitted through the current lead to the object to be cooled.

  In the second cooling stage 2 of the cryogenic refrigerator 1, the object to be cooled 20 that operates in a cryogenic cooling environment is cooled. The object 20 to be cooled is, for example, a superconducting magnet or a SQUID application device. In addition, other devices using a cryogenic environment are also applicable.

  The object to be cooled 20 cooled by the second cooling stage 2 of the cryogenic refrigerator 1 has a connecting portion 21, and the connecting portion 21 is cooled by the second cooling stage 2 of the cryogenic refrigerator 1. The object to be cooled 20 is cooled to a very low temperature.

  The heat shield 4 cooled by the first cooling stage 7 of the cryogenic refrigerator 1 has a connecting portion 72, and heat is generated by cooling the connecting portion 72 by the first cooling stage 7 of the cryogenic refrigerator 1. The shield 4 can be cooled to a very low temperature.

  The cryogenic refrigerator 1 is fixed to the vacuum vessel 3. The vacuum vessel 3 can be evacuated and evacuated by a vacuum pump (not shown). Around the cryogenic refrigerator 1, a closed wall 32 different from the vacuum chamber around the object to be cooled 20 is formed by a vacuum wall 31 serving as a partition. When removing the cryogenic refrigerator 1, it removes by making the closed space 32 into atmospheric pressure. At this time, the closed space 32 is filled with helium gas to prevent condensation / condensation in the cryogenic part.

  In the second cooling stage 2, at least one flexible portion 11 and the thermal contact portion 12 between the object to be cooled are thermally coupled. Similarly, a connecting portion 72 that is a thermal contact portion between at least one flexible portion 71 and an object to be cooled is thermally coupled to the first cooling stage. The flexible part 11 and the flexible part 71 are made of a material having high thermal conductivity such as oxygen-free copper or high-purity aluminum. The flexible part 11 and the flexible part 71 are bundles of, for example, an oxygen-free copper wire or a high-purity aluminum wire, and have both high thermal conductivity and flexibility.

  The thermal contact portion 12 and the thermal contact portion 72 are made of copper or aluminum having a high thermal conductivity. The thermal contact portion 12 and the flexible portion 11 are thermally coupled. Similarly, the thermal contact portion 72 and the flexible portion 71 are also in thermal contact.

  A heat shrink ring 5 is installed on the outer periphery of the heat contact portion 12. A heat shrink ring 51 is installed on the outer periphery of the heat contact portion 72. The heat shrink ring 5 and the heat shrink ring 51 are made of, for example, a fluorine resin such as Teflon (registered trademark) or a polymer compound such as nylon. In addition, a heater 6 and a heater 61 are provided adjacent to the heat shrink ring 5 and the heat shrink ring 51. The heat contact portion 72 and the connecting portion 91 are fastened by the heat shrink ring 51.

  The function of each element when the refrigerator is attached will be described with reference to FIG. 2 for the second cooling stage 2 of the cryogenic refrigerator 1. FIG. 2 is a detailed cross-sectional view of the cryogenic refrigerator coupling structure in the second cooling stage in the first embodiment.

  The second cooling stage 2 is thermally coupled to the thermal contact part 12 through at least a part of the flexible part 11. The thermal contact portion 12 has a structure divided in the circumferential direction, and each divided thermal contact portion has a structure movable in the radial direction. A heat shrink ring 5 and a heater 6 are installed on the outer periphery of the heat contact portion 12. The heat contact portion 12 and the heat shrink ring 5 are configured such that at least a part of the heat contact portion divided in the circumferential direction is thermally coupled.

  A certain clearance is provided between the thermal contact portion 12 and the coupling portion 21 that are thermally coupled to the second cooling stage 2 via the flexible portion 11 when the thermal contact portion 12 is in a normal temperature state. Is designed to occur. Therefore, in the state where the room-temperature cryogenic refrigerator 1 is attached, the heat contact portion 12 and the connection portion 21 in the second cooling stage are in a non-contact state, and heat transfer from the room temperature cooling stage 2 to the connection portion 21 is performed. Does not occur.

  After the cryogenic refrigerator 1 is attached, when the cryogenic refrigerator 1 is operated to gradually lower the temperature of the second cooling stage 2, a thermal contact portion thermally coupled to the second cooling stage 2 The temperature of 12 also decreases gradually. Moreover, the temperature of the heat shrink ring 5 attached to the outer periphery of the thermal contact portion 12 also decreases.

  The heat shrink ring 5 has a larger heat shrinkage rate at the time of cryogenic cooling than the heat contact portion 12 of the second cooling stage. FIG. 8 is a diagram showing the relationship between the amount of heat shrinkage and temperature of main constituent materials (extracted from Hiroyasu Sugawara, “Introduction to Low Temperature Engineering”, published by Tokyo Denki University Press, July 1999, P.292).

  For example, when the heat contact portion is copper, the heat shrinkage is about 0.3% from the normal temperature when cooled to about 50K, whereas it is cooled to 50K when the heat shrink ring 5 or the heat shrink ring 51 is nylon. In the case of Teflon (registered trademark), it contracts 2.0% from the normal temperature when cooled to 50K.

  Although the thermal contact portion 12 is thermally contracted as the temperature decreases, the thermal contraction amount of the thermal contraction ring 5 is larger than the thermal contraction amount of the thermal contact portion 12, so that the thermal contraction ring 5 gradually tightens the thermal contact portion 12. . When the temperature of the cryogenic refrigerator 1 is high due to the thermal contact, heat transfer from the cryogenic refrigerator 1 to the object to be cooled 20 occurs, but the cryogenic refrigerator 1 is heated in a sufficiently cooled state. Since it contacts, the amount of heat transfer is small, and the temperature rise of the to-be-cooled object 20 can be suppressed small.

  Next, the process of removing the refrigerator will be described using FIG. 1 and FIG.

  In order to separate the connecting portion 21 in the cryogenic state from the second cooling stage 2 of the cryogenic refrigerator 1, the heater 6 attached to the outer periphery of the heat shrink ring 5 is heated. As the temperature of the heat shrink ring 5 rises, the amount of heat shrink of the heat shrink ring 5 is reduced, and a clearance is generated between the heat contact portion 12 and the connecting portion 21 that have been tightened by the heat shrink ring 5. Similarly, the heater 61 attached to the outer periphery of the heat shrink ring 51 is heated in order to separate the connecting portion 91 in the cryogenic state from the first cooling stage 7 of the cryogenic refrigerator. When the temperature of the heat shrink ring 51 rises, the amount of heat shrink of the heat shrink ring 51 is reduced, and a clearance is generated between the heat contact portion 72 and the connecting portion 91 that are fastened by the heat shrink ring 51.

  The cryogenic refrigerator 1 can be removed at the time when both the first cooling stage 7 and the second cooling stage 2 of the refrigerator have clearance.

  FIG. 3 is a cross-sectional view of the heat contact portion 12 and the heat-shrink ring 5 as heat conduction means in the second cooling stage 2 as seen from above. The thermal contact portion 12 is divided in the circumferential direction. The thermal contact portion 12 is in thermal contact with the central connecting portion 21. A heat shrink ring 5 and a heater 6 are installed on the outer periphery of the heat contact portion 12.

  FIG. 3A shows the positional relationship between the thermal contact portion 12 and the connection portion 21 of the object to be cooled before cooling the cooling stage of the cryogenic refrigerator, that is, in a normal temperature state. In the normal temperature state, there is a clearance between the thermal contact portion 12 and the connecting portion 21, and heat transfer from the thermal contact portion 12 at normal temperature to the connecting portion 21 in the cryogenic state does not occur. Thereby, the temperature rise of the to-be-cooled object at the time of refrigerator connection can be suppressed.

  FIG. 3B is a diagram showing a positional relationship between the thermal contact portion 12 and the connecting portion 21 after cooling the cooling stage of the cryogenic refrigerator. By the second cooling stage 2 of the cryogenic refrigerator, the thermal contact portion 12, the heat shrink ring 5, and the heater 6 are cooled to a cryogenic temperature. The heat shrink ring 5 is thermally contracted by being cooled to a very low temperature. The heat shrink ring 5 is contracted by heat to shorten the circumference and to shrink in the radial direction. For example, in the case of a Teflon (registered trademark) ring with an inner diameter of 50 mm, the circumference is shortened by 2% by heat shrinking to 50K. This means that the diameter is reduced to 49 mm. When the diameter of the heat shrink ring 5 is reduced, the heat shrink ring 5 is tightened to the heat contact portion 12, and the heat contact portion 12 and the connecting portion 21 are in thermal contact.

  FIG. 4 is a detailed cross-sectional view of the cryogenic refrigerator connecting structure in the second cooling stage 2 in the second embodiment of the present invention. Only the parts different from the first embodiment will be described.

  The heat conducting means 122 is configured to support the heat shrink ring 5 from both the inside and outside. When the temperature of the second cooling stage 2 of the cryogenic refrigerator 1 rises, the outer periphery of the heat shrink ring 5 has a heat contact portion between the heat conducting means 122 and the heat shrink ring 5. The effect of pulling apart occurs.

  FIG. 5 is a detailed cross-sectional view of the cryogenic refrigerator connecting structure in the first cooling stage in the third embodiment of the present invention. With reference to FIG. 5, a cryogenic refrigerator connecting structure in the first cooling stage 7 of the cryogenic refrigerator 1 will be described.

  The first cooling stage 7 is thermally coupled to the thermal contact part 72 through at least a part of the flexible part 71. The thermal contact portion 72 has a structure divided in the circumferential direction, and each divided thermal contact portion has a structure movable in the radial direction. A heat shrink ring 51 and a heater 61 are installed on the outer periphery of the heat contact portion 72. The heat contact portion 72 and the heat shrink ring 51 are shaped such that at least a part of the heat contact portion divided in the circumferential direction is thermally coupled.

  A certain clearance is provided between the thermal contact portion 72 and the coupling portion 91 that are thermally coupled to the first cooling stage 7 via the flexible portion 71 when the thermal contact portion 72 is in a normal temperature state. Is designed to occur. Therefore, in a state in which the cryogenic refrigerator 1 at room temperature is attached, the thermal contact portion 72 and the connecting portion 91 in the first cooling stage are not in contact with each other, and the room temperature cryogenic refrigerator 1 is connected to the connecting portion 91. There is no heat transfer.

  When the cryogenic refrigerator 1 is operated and the temperature of the first cooling stage 7 is gradually lowered after the cryogenic refrigerator 1 is attached, a thermal contact portion thermally coupled to the first cooling stage 7 The temperature at 72 also decreases gradually. In addition, the temperature of the heat shrink ring 51 attached to the outer periphery of the heat contact portion 72 is also lowered.

  The heat shrink ring 51 has a larger heat shrinkage rate at the time of cryogenic cooling than the heat contact portion 72 of the first cooling stage. Although the thermal contact portion 72 is thermally contracted as the temperature decreases, the thermal contraction amount of the thermal contraction ring 51 is larger than the thermal contraction amount of the thermal contact portion 72, so that the thermal contraction ring 51 gradually tightens the thermal contact portion 72. . When the temperature of the cryogenic refrigerator 1 is high due to thermal contact, heat transfer from the cryogenic refrigerator 1 to the heat shield 4 occurs, but the cryogenic refrigerator 1 is in thermal contact in a sufficiently cooled state. Therefore, the amount of heat transfer is small, and the temperature rise of the heat shield 4 can be suppressed to a small level.

  Next, the process of removing the refrigerator will be described with reference to FIG.

  In order to separate the connecting portion 71 in the cryogenic state from the first cooling stage 7 of the cryogenic refrigerator 1, the heater 61 attached to the outer periphery of the heat shrink ring 51 is heated. When the temperature of the heat shrink ring 51 rises, the amount of heat shrink of the heat shrink ring 51 is reduced, and a clearance is generated between the heat contact portion 72 and the connecting portion 91 that are fastened by the heat shrink ring 51. Similarly, the heater 61 attached to the outer periphery of the heat shrink ring 51 is heated in order to separate the connecting portion 91 in the cryogenic state from the first cooling stage 7 of the cryogenic refrigerator. When the temperature of the heat shrink ring 51 rises, the amount of heat shrink of the heat shrink ring 51 is reduced, and a clearance is generated between the heat contact portion 72 and the connecting portion 91 that are fastened by the heat shrink ring 51. The cryogenic refrigerator 1 can be removed at the time when both the first cooling stage and the second cooling stage of the refrigerator have clearance.

  FIG. 6 is a detailed cross-sectional view of the cryogenic refrigerator connecting structure in the first cooling stage 7 in the third embodiment of the present invention.

  The heat conducting means 78 is configured to support the heat shrink ring 51 from both the inside and outside. When the temperature of the first cooling stage 7 of the cryogenic refrigerator 1 rises, the outer periphery of the heat shrink ring 51 is the heat contact portion 78 when the heat conduction means 78 and the heat shrink ring 51 are in close contact. The effect of pulling apart occurs.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. In addition, a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of a certain embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit. Further, each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files for realizing each function can be stored in a recording device such as a memory, a hard disk, or an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, or a DVD.

DESCRIPTION OF SYMBOLS 1 Cryogenic refrigerator 2 2nd cooling stage 3 Vacuum container 4 Heat shield 5 Heat shrink ring 6 Heater 7 1st cooling stage 11 Flexible part 12 Thermal contact part
20 Cooled object 21 Connecting part 31 Vacuum wall 32 Closed space

Claims (7)

A vacuum container for storing the object to be cooled inside;
A heat shield installed between the object to be cooled and the vacuum vessel;
A cooling stage for cooling the object to be cooled and the heat shield to a cryogenic temperature;
In a cryogenic containment vessel having a cryogenic refrigerator connected to the vacuum vessel via a connection structure,
The connection structure includes a heat contact portion connected to the cooling stage, and a heat shrink ring having a heat shrink rate larger than that of the heat contact portion is provided on an outer peripheral portion of the heat contact portion. Cryogenic refrigerator connection structure. In the connection structure of the cryogenic containment vessel according to claim 1,
The cooling stage has a first cooling stage and a second cooling stage,
A connecting portion between the heat shield and the first cooling stage of the cryogenic refrigerator, and a connecting portion between the object to be cooled and the second cooling stage of the cryogenic refrigerator,
In the two connecting portions, each of the two contact portions has a thermal contact portion connected to the first cooling stage of the cryogenic refrigerator and the second cooling stage of the cryogenic refrigerator, and the outer peripheral portion of the thermal contact portion. A cryogenic refrigerator coupling structure, a cryogenic storage container coupling structure, wherein a heat shrinking ring having a thermal contraction rate larger than that of the thermal contact portion is provided. In the connection structure of the cryogenic containment vessel according to claim 1,
The connecting structure for a cryogenic storage container, wherein the thermal contact part has at least a part of a flexible part. In the connection structure of the cryogenic containment vessel according to claim 1,
A connection structure for a cryogenic containment vessel, wherein the thermal contact portion is divided in a circumferential direction. In the connection structure of the cryogenic containment vessel according to claim 1,
A process in which a clearance occurs between the first cooling stage of the cryogenic refrigerator and the heat shield when the cryogenic refrigerator is at room temperature, and the first cooling stage of the cryogenic refrigerator reaches a cryogenic state. The structure for connecting a cryogenic containment vessel, wherein the heat contact ring and the heat shield are automatically brought into thermal contact with each other when the heat shrink ring is thermally contracted. In the connection structure of the cryogenic containment vessel according to claim 1,
A clearance occurs between the second cooling stage of the cryogenic refrigerator and the object to be cooled when the cryogenic refrigerator is in a normal temperature state, and the second cooling stage of the cryogenic refrigerator reaches a cryogenic state. A structure for connecting a cryogenic containment vessel, wherein a heat contact portion and a portion to be cooled automatically come into thermal contact with each other by heat shrinking of the heat shrink ring during the process.   A cryogenic storage container having a connecting structure for a cryogenic storage container according to any one of claims 1 to 6.

Images