JPH061996U - Refrigerator connection structure in cryogenic container - Google Patents

Abstract

(57) [Summary] [Purpose] Satisfactory stable cooling performance of the shield member by the refrigerator. [Structure] The refrigerator 22 is fixed to the vacuum container 20 and
The 80K heat conduction block 34 is connected to the shield plate 18. The inner shaft 42 having the spring portion 44 is fixed to the 80K heat conduction block 34, and the flange portion 30 of the vacuum container 20 is fixed.
The outer shaft 41 is fixed to the outer shaft 41 and the inner shaft 4
2 so that the distance between the two shafts can be varied.
Connect via.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a structure for connecting a cold storage refrigerator to the shield member in a cryostat, particularly in a cryostat such as a cryostat in which a shield member is arranged in a vacuum container.

[0002]

[Prior art]

 In a cryostat containing a cryogenic substance inside, for example, a superconducting magnet and liquid helium inside, a holding time of liquid helium is reduced from the viewpoint of reducing operating cost and workload. It is very important to make it as long as possible. As a means for this, it is very important to arrange a radiation shield plate between the liquid helium tank of the cryostat and the outer vacuum container, and connect a refrigerator to this radiation shield plate to maintain a low temperature state. It is effective (see, for example, Japanese Patent Laid-Open No. 3-94483).

FIG. 4 shows an example of a connection structure between a refrigerator and a radiation shield plate in a conventional cryostat. The illustrated cryostat comprises a liquid helium tank 80, a radiation shield plate having a temperature level of 20K (hereinafter referred to as a 20K shield plate) 82, an 80K shield plate 84, and a vacuum container 86 in this order from the inside thereof, and a vacuum container 86 is provided. A flange 87 is formed on the outside of the container 86, and a refrigerator 90 is attached to the flange 87 via a flange 88. This refrigerator 90 is a two-stage refrigerator having an 80K cold end (cold output part) 92a and a 20K cold end 92b, and a thin-walled cylindrical housing 91a is placed in a motor housing portion 91 containing a motor for driving an expansion device. 80K cold end 92a is connected, and further, 20K cold end 92b is connected through a housing 91b having the same shape. The entire refrigerator 90 is arranged so that the 80K cold end 92a is located just outside the 80K shield plate 84, and the 20K cold end 92b is located just outside the 20K shield plate 82.

On the other hand, a copper 80K heat conduction block 93 is integrally connected to the flange portion 87 via a bellows 96, and a 20K heat conduction block 94 is connected to the 80K heat conduction block 93 via a bellows 98. Connected together. These heat conduction blocks 93, 94 are connected to the 80K shield plate 84 and the 20K shield plate 82 via the copper wire 95 so as to be able to transfer heat, and are displaced in the inside and outside directions of the container (upward and downward directions in the figure). It is possible. Then, by the tensile spring force of each bellows 96, 98, the 80K heat conduction block 93 and the 20K heat conduction block 94 come into contact with the lower surfaces of the outer peripheral portions of the 80K cold end 92a and the 20K cold end 92b, respectively, with a predetermined surface pressure. As a result, the heat transfer between the 80K cold end 92a and the 80K shield plate 84 via the 80K heat conduction block 93 and the copper mesh wire 95, and via the 20K heat conduction block 94 and the copper mesh wire 95. Heat is transferred between the 20K cold end 92b and the 20K shield plate 82.

[0005]

[Problems to be solved by the device]

 In the above structure, the heat transfer coefficient from the 80K cold end 92a to the 80K heat conduction block 93 is determined by the surface pressure of the heat contact portions of the two, in other words, the bellows 96 pulls the 80K heat conduction block 93 with a spring force. That is, it is determined by the spring constant of the bellows 96. Therefore, in order to increase the heat transfer rate and thus the cooling efficiency, it is important to increase the spring constant of the bellows 96 to obtain a large surface pressure. However, in the refrigerator 90, the housing 91a that supports the cold end 92a. Is made of a thin metal pipe having a small cross-sectional area in order to obtain a high heat insulating property. Therefore, if the spring constant is increased and a too large load is applied, the housing 91a may be deformed and the cooling efficiency may be lowered. Therefore, the spring constant of the bellows 96 must be set to a specific and appropriate value.

However, the spring constant of the bellows 96 varies in manufacturing, and it is very difficult to always stably manufacture the bellows 96 having a desired spring constant. Therefore, when the spring constant is deviated to a low value, sufficient surface pressure cannot be obtained, so that the cooling efficiency of the shield plate 84 is lowered, while when the spring constant is deviated to a high value, an excessive pressure is applied. Therefore, the housing 91a may be deformed.

In view of such circumstances, it is an object of the present invention to provide a refrigerator connection structure that can obtain the cooling capacity of the shield member by the refrigerator with stability.

[0008]

[Means for Solving the Problems]

 The present invention relates to a cryocontainer including an outer container, a shield member housed in the outer container, and a refrigerator fixed to the outer container and connected to the shield member. A heat conducting member connected to the cold output of the refrigerator from the inside of the container, the heat conducting member being connected to the shield member so as to be able to transfer heat to the inside and outside of the container, and the heat conducting member and the outside. A connecting member for connecting with the container, and as the connecting member, an inner connecting member extending from the heat conducting member in the outer direction of the container, an outer connecting member extending in the inner direction of the container from the outer container, and an inner connecting member And an outer connecting member, and an intermediate connecting member that connects the outer connecting member and the outer connecting member so that the distance between the inner and outer connecting members is variable, and the container is provided on at least one of the inner connecting member and the outer connecting member. A spring portion provided outwardly, is obtained by pressure contact with the upper Symbol cold output unit the heat conducting member in its tension spring force (claim 1).

More specifically, the intermediate connecting member is rotatably attached to one end of the inner connecting member and the outer connecting member, and is screwed to the other end and the intermediate connecting member. It is preferable to provide a possible threaded portion (Claim 2).

[0010]

[Action]

 According to the above configuration, even if the spring constants of the spring portions formed on the outer connecting member and the inner connecting member vary, by changing the distance between the inner connecting member and the outer connecting member accordingly. It is possible to adjust the tension spring force of the spring portion and thus the surface pressure between the heat conducting member and the cold output portion of the refrigerator to a desired value.

More specifically, according to the structure of claim 2, by rotating the intermediate connecting member with the intermediate connecting member and the inner connecting member or the outer connecting member screwed together, the inner connecting member and the inner connecting member are rotated. The distance to the outer connecting member can be changed.

[0012]

【Example】

 A first embodiment of the present invention will be described with reference to FIGS.

The cryostat (cryogenic container) 10 shown in FIG. 3 is provided with a liquid helium tank 14 for containing a donut-shaped superconducting magnet 12 and liquid helium 13, and the liquid helium tank 14 is in a vacuum state inside the vacuum container 20. The radiation shield plate with a temperature level of 20K (hereinafter referred to as a 20K shield plate) 16 and the radiation shield plate with a temperature level of 80K (hereinafter, , 80K shield plate) 18 are sequentially arranged from the inside. Specifically, a neck pipe 14a for releasing evaporated helium gas is extended upward from the upper part of the liquid helium tank 14, and an upper end portion of the neck pipe 14a is welded to an upper end portion of the vacuum container 20. At the same time, the upper ends of both shield plates 16 and 18 are fixed to the mid-abdomen of the neck tube 14a.

Further, in this cryostat 10, a refrigerator 22 is connected to both the shield plates 16 and 18 in order to maintain a low temperature in the liquid helium tank 14.

This connection structure is shown in FIG. The refrigerator 22 shown in the figure has a cold end (cold output part in the present invention; hereinafter referred to as 80K cold end) 24 having a temperature level of 80K and a cold end (hereinafter referred to as 20K cold end) 26 having a temperature level of 20K in order. It is a two-stage refrigerator having the above, and is provided with a motor housing portion 21 in which a motor for driving the expansion device is incorporated. The 80K cold end 24 is connected to the motor housing portion 21 through a thin-walled cylindrical housing 23, and the 20K cold end 26 is connected through the same-shaped housing 25. The outer diameter of each part is larger in the order of the motor housing 22, the housing 23, and the housing 25. The outer diameter of the 80K cold end 24 is slightly larger than the outer diameter of the housing 23, and the outer diameter of the 20K cold end 26 is the outer diameter of the housing 25. It is slightly larger than the outer diameter.

As a mounting structure of the refrigerator 22, a flange portion 30 is extended upward from a ceiling wall of the vacuum container 20, and a flange 32 is fixed to the flange portion 30. The flange 32 is provided with a central through hole 31 having a diameter larger than that of the 80K cold end 24. With the housings 23 and 25 inserted into the vacuum container 20 through the central through hole 31, the motor housing portion is The peripheral portion of 21 is fixed to the flange 32.

On the other hand, a through hole 18a is provided on the 80K shield plate 18 at a position corresponding to the position where the refrigerator 22 is disposed, and a position directly above the through hole 18a, in other words, the 80K cold end. An 80K heat conduction block 34 made of a material having a high heat transfer coefficient such as copper is horizontally arranged at a position where it can come into contact with 24. The 80K heat conduction block 34 has an outer diameter that is larger than the outer diameter of the 80K cold end 24 and smaller than the hole diameter of the through hole 18a, and its peripheral portion is 80K shielded via the copper wire 38. It is connected to the plate 18 in a heat transferable manner.

A through hole 33 having a hole diameter larger than the outer diameter of the 20K cold end 26 is provided in the center of the 80K heat conduction block 34, and the housing 25 and the housing 25 from the outside to the inside of the through hole 33 are provided. The 20K cold end 26 is inserted. On the other hand, the through hole 16a is provided in the 20K shield plate 18 at a position corresponding to the position where the refrigerator 22 is disposed, and the position immediately above the through hole 16a, in other words, the 20K cold end 26, is contacted. The 20K heat conduction block 36 is horizontally arranged at a possible position. The 20K heat conduction block 36 has an outer diameter that is larger than the outer diameter of the 20K cold end 26 and smaller than the hole diameter of the through hole 16a, and the peripheral edge portion of the 20K heat conduction block 36 is connected to the 20K shield plate 16 via the copper mesh wire 40. Is connected in a heat transferable manner to.

The 80K heat conduction block 34 is connected to the flange portion 30 via a plurality of connection members 40, which is a feature of the present invention. These connecting members 40 are arranged side by side in the circumferential direction of the flange portion 30 and the 80K heat conduction block 34.

Each connecting member 40 includes an outer shaft (outer connecting member) 41 extending downward from the lower surface of the inner peripheral portion of the flange portion 30 and an inner shaft (inner connecting portion) extending upward from the upper surface of the outer peripheral portion of the 80K heat conduction block 34. Member) 42, and both shafts 41, 42 are aligned in a straight line. A coil-shaped spring portion 44 is formed in the middle of the inner shaft 42, and the spring portion 44 is pulled upward and downward.

The inner shaft 42 and the outer shaft 41 are connected via a nut member (intermediate connecting member) 46. As shown in FIG. 2, the nut member 46 is formed in a cylindrical shape having a vertical through hole in the center, and an internal thread 46a is formed on the upper inner peripheral surface of the through hole and a lower inner peripheral surface is formed. An internal thread 46b opposite to the internal thread 46a is formed. On the other hand, a male screw 41a that can be screwed with the female screw 46a is formed on the outer peripheral surface of the lower end of the outer shaft 41, and a male screw 42a that can be screwed with the female screw 46b is formed on the outer peripheral surface of the upper end of the inner shaft 42. In the state where these are screwed together, the nut member rotation stopping nut 48 is tightened above and below the nut member 46.

Therefore, by loosening the upper and lower nuts 48 and rotating the nut member 46, the lower end portion of the outer shaft 41 and the upper end portion of the inner shaft 42 can be brought close to or separated from each other. .

The 20K heat conduction block 36 is connected to the 80K heat conduction block 34 via a plurality of connection members 50 similar to the connection member 40. That is, the connecting member 50 includes an outer shaft 51 extending downward from the lower surface of the 80K heat conduction block 34 and an inner shaft 52 extending upward from the upper surface of the 20K heat conduction block 36. A coiled spring portion 54 is formed on the inner surface of the inner shaft 52 and the upper end of the outer shaft 51 is connected via a nut member 56 having the same structure as the nut member 46 shown in FIG. There is. The lower surface of the outer peripheral portion of the 80K cold end 24 is pressed against the upper surface of the inner peripheral portion of the 80K heat conduction block 34 by the tensile spring force of the spring portion 44, and the lower surface of the 20K cold end 26 is heated by the tensile spring force of the spring portion 54. The lower surface of the outer peripheral portion of the motor housing portion 21 of the refrigerator 22 is fixed to the upper surface of the flange 32 while being pressed against the upper surface of the conduction block 36.

According to such a structure, the 80K heat conduction block 34 is pressed against the lower surface of the 80K cold end 24 by the tension spring force of the spring portion 44, and the 20K heat conduction block 36 is caused by the tension spring force of the panel portion 54. Since it comes into pressure contact with the lower surface of the 20K cold end 26, the cold pressure output from the 80K cold end 24 is transmitted to the 80K shield plate 18 via the 80K heat conduction block 34 and the copper mesh wire 38 due to these surface pressures. The cold output from the 20K cold end 26 is transmitted to the 20K shield plate 16 via the 20K heat conduction block 36 and the copper mesh wire 40.

Here, the heat transfer coefficient from the 80K cold end 24 to the 80K heat conduction block 34 is determined by the surface pressure between the 80K cold end 24 and the 80K heat conduction block 34, which is the surface pressure of the spring portion 44. If there is variation in the spring constant, it will naturally change accordingly.

However, in this structure, the lower end portion of the outer shaft 41 and the upper end portion of the inner shaft 42 are freely brought close to each other by loosening the detent nut 48 shown in FIG. 2 and rotating the nut member 46. Since this operation can be performed or they can be separated from each other, by performing this operation in advance in accordance with the spring constant of each spring portion 44, even if there is a variation in this spring constant, the desired tension spring in each connecting member 40 can be obtained. You can get a stable power. That is, when the spring constant of the spring portion 44 is larger than the standard, the nut member 46 is rotated to separate the outer shaft 41 and the inner shaft 42 from each other, thereby reducing the amount of expansion of the spring portion 44 and reducing the spring amount. When the spring constant of the spring portion 44 is smaller than the standard, the nut member 46 is turned to bring the outer shaft 41 and the inner shaft 42 closer to each other, and the extension of the spring portion 44 is suppressed. By increasing the amount and increasing the tensile force of the spring portion 44, a desired tensile bending force can be obtained regardless of the spring constant of the spring portion 44. As a result, the surface pressure can be adjusted to a desired pressure at all times, and a stable cooling capacity of the refrigerator 22 can be obtained. Similarly, by adjusting the connecting member 50 in the nut member 56, the surface pressure between the 20K cold end 26 and the 20K heat conduction block 36 can be always kept constant regardless of the spring constant of the spring portion 54. .

The present invention is not limited to such an embodiment, and the following modes can be adopted as an example.

(1) In the above embodiment, the spring portion 44 is formed on the inner shaft 42 side. However, the present invention is not limited to this, and the spring portion 44 may be formed on the outer shaft 41 side. However, the spring portions 44 may be formed on both the outer shaft 41 and the inner shaft 42.

(2) In the above embodiment, the nut member 46 screwed to both the outer shaft 41 and the inner shaft 42 is used as the intermediate connecting member in the present invention. The same effect as described above can be obtained by screwing only one end of the outer shaft 41 or the inner shaft 42 and simply rotatably mounting the other end. . Further, in the present invention, a male screw may be provided on the side of the intermediate connecting member and a female screw may be provided on the outer connecting member or the inner connecting member.

(3) In the above embodiment, the two-stage refrigerator 22 is used to cool both the 80K shield plate 18 and the 20K shield plate 16, but only one of the shield plates is used as a refrigerator. The present invention can also be applied to the case of connecting. For example, when only the 20 K shield plate 16 is cooled by the refrigerator 22, if the 20 K heat conduction block 36 is directly connected to the vacuum container 20 side through a connecting member similar to the connecting member 40. Good.

Further, it goes without saying that the present invention can be applied to a cryogenic container provided with only a single shield plate.

(4) In the above embodiment, the inner shaft 42 is formed with the spring portion 44 integrally with the inner shaft 42. However, the inner shaft 42 is divided into two in the axial direction, and these divided shafts are divided. Even if they are connected to each other via a ready-made spring member, the same effect as described above can be obtained.

[0033]

[Effect of device]

 INDUSTRIAL APPLICABILITY As described above, the present invention connects the outer container that houses the shield member and the heat conducting member that is connected to the shield member side and is in contact with the cold output portion of the refrigerator, and as a means thereof The inner connecting member on the side of the conductive member and the outer connecting member on the side of the outer container are connected by an intermediate connecting member so that the distance between the inside and the outside of the container is variable, and the inner connecting member and the outer connecting member are connected. Since the surface pressure between the heat conducting member and the cold output portion is obtained by the tensile spring force of the spring portion provided in at least one of the spring portions, even if the spring constant of the spring portion varies. By adjusting the separation distance between the inner connecting member and the outer connecting member accordingly, a constant surface pressure can always be obtained, which stabilizes the cooling capacity of the shield plate by the refrigerator. Effect that can be achieved There is.

More specifically, in the structure according to claim 2, since the connection is performed in a state where the intermediate connecting member is screwed into the inner connecting member or the outer connecting member, only the intermediate connecting member is rotated. With such a simple operation, the distance between the outer connecting member and the inner connecting member can be adjusted, that is, the surface pressure between the refrigerator cold output portion and the heat conducting member can be adjusted.

[Brief description of drawings]

FIG. 1 is a sectional front view showing a mounting structure of a refrigerator provided in a cryostat according to an embodiment of the present invention.

FIG. 2 is a sectional front view of a nut member used in the above structure.

FIG. 3 is an overall configuration diagram of the cryostat.

FIG. 4 is a cross-sectional front view showing a mounting structure of a refrigerator in a conventional cryostat.

[Explanation of symbols]

 10 Cryostat (low temperature container) 18 80K shield plate (shield member) 20 Vacuum container (outer container) 22 Refrigerator 24 80K cold end (cold output part) 34 80K heat conduction block (heat conduction member) 40 Connection member 41 Outer shaft ( Outer connecting member) 42 Inner shaft (inner connecting member) 44 Spring portion 46 Nut member (intermediate connecting member)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazunori Saito 1-5-5 Takatsukadai, Nishi-ku, Kobe City Kobe Steel Research Institute, Kobe Steel Research Institute

Claims (2)

[Scope of utility model registration request] 1. A cryogenic container comprising an outer container, a shield member housed in the outer container, and a refrigerator fixed to the outer container and connected to the shield member. A heat transfer member which is connected to the shield member so as to be movable and movable inward and outward of the container with respect to the shield member, and which comes into contact with the cold output part of the refrigerator from the inside of the container; With a connecting member for connecting, as the connecting member,
The inner connecting member extending in the container outer direction from the heat conducting member, the outer connecting member extending in the container inner direction from the outer container, and the separation distance between the inner connecting member and the outer connecting member in the container inner and outer directions are variable. And a spring portion is provided on at least one of the inner connecting member and the outer connecting member, and the heat conducting member is brought into pressure contact with the cold output portion by a tension spring force of the spring portion. A refrigerator connection structure in a cryogenic container characterized by: 2. The refrigerator connecting structure for a cryogenic container according to claim 1, wherein the intermediate connecting member is an inner connecting member,
A refrigerator connection structure in a cryogenic container, which is rotatably mounted on one of the ends of the outer connecting member, and is provided with a screw part which can be screwed into the other end and the intermediate connecting member. .