JP3000106B2 - Cryostat - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cryostat for storing a refrigerant such as liquid helium. More specifically, the support structure of a coolant storage tank (hereinafter simply referred to as a coolant tank) accommodated in a vacuum tank is improved to reduce the amount of external heat intrusion, and to stabilize the positional relationship between the two tanks after the coolant is injected. It relates to a cryostat that can be held.

[Conventional technology]

As a technique for fixing and supporting a refrigerant tank in a vacuum tank in a cryostat, as shown in Japanese Utility Model Application Laid-Open No. 63-124766, a technique in which inner and outer tanks are connected to each other by using bolted posts, Japanese Patent Application Laid-Open No. 113968/1988 and Japanese Patent Application Laid-Open No. 63-261706 utilize the difference in thermal shrinkage of the structural material of the support portion to facilitate assembly and protect other parts.

In addition, as shown in JP-B-63-66043, the heat transfer distance of the support part was devised, and the FNL, U.S.A., Fermi National Laboratory, SSC cryostat ('March, 1986), P72 As shown in (2), there is a type in which a spring mechanism is provided to directly press and support the refrigerant tank and the superconducting coil housed in the refrigerant tank quite firmly.

[Problems to be solved by the invention]

Conventional devices of this type did not consider the imbalance of cooling of the coolant tank during the injection of the coolant, so a large thermal gradient during cooling (the structural material of the coolant tank is mostly FRP with low thermal conductivity, stainless steel Therefore, the support may receive an excessive force and deform unexpectedly due to the deformation of the refrigerant tank caused by the large thermal gradient between the refrigerant contact portion and the non-contact portion.

With such a deformation, the positional relationship between the vacuum tank and the refrigerant tank is broken, and when the superconducting coil is stored, it becomes difficult to center the coil and the like.

In addition, if the strength of the support is increased by increasing the cross-sectional area or the like, the deformation of the support is suppressed. However, if this method is adopted, the amount of heat entering the refrigerant tank increases, which leads to an increase in the amount of evaporation of the refrigerant.

A structure in which the refrigerant tank is suspended from the vacuum tank is also effective for preventing deformation of the support member. However, in this case, since there is no fixed point, it is difficult to place the refrigerant tank and confirm its position after cooling.

An object of the present invention is to eliminate the above-mentioned problems.

[Means for solving the problem]

In order to solve the above-mentioned problem, in the present invention, the first and second support members are provided between the vacuum tank at a plurality of positions at a position reference point immediately below the tank and at other positions.
The first support member at the position reference point has rigid connections at both ends of the two tanks, and the second support members provided at other positions have lower connections to the vacuum tank than the second support members. The connection is made through a variable-shaped support seat of high strength.

Further, the connection of the second support member to the coolant tank is performed by passing the second support member through the spherical seat provided in the coolant tank with a clearance on the outer periphery thereof being generated, and the spherical seat on the second support material side is connected to the spherical seat. This operation is performed through a relative displacement absorbing section in a direction perpendicular to the axis having a structure in which a corresponding spherical seat is brought into contact with the center of the tank.

[Action]

When the coolant tank thermally deforms (shrinks or expands), the deformable support seat is deformed, and the second support member supported by the support seat follows the coolant tank. Therefore, no excessive force is applied to the second support member, and even if a support member having a low cross-sectional area, which is advantageous in preventing heat intrusion, is used, its deformation does not occur.

Further, since both ends of the first support member at the position reference point are connected to each other in a rigid structure, the positional relationship between the vacuum tank and the refrigerant tank is determined based on the rigid support after cooling.

Further, since the connection of the second support member to the refrigerant tank is performed through the axial relative displacement absorbing portion having the above structure, the second support member can be freely adapted to the circumferential direction and torsion of the tank, and can be supported by the second support member. There is no loss of stability.

〔Example〕

FIG. 1 shows an example of application to a horizontal cylindrical cryostat. 1 is a vacuum tank, 2 is a refrigerant tank, 3 is a radiant heat shield plate of 80k, 20k, etc., and 4 is a refrigerant of liquid helium or the like.

5 is a first support member connecting 1 and 2 directly below 2;
Reference numeral 6 denotes a second support member that connects 1 and 2 at a position shifted by an arbitrary angle in the circumferential direction from 5, and 5 is preferably provided immediately below the center of gravity of 2. Also, 6 is from 5 in the case of the figure.
A total of two are provided at centrally symmetrical positions spaced 120 ° apart.

As shown in FIG. 2, both ends of the first support member 5 are connected to the tanks 1 and 2 by connecting portions having a rigid structure (screw connection to the fixed seat 7 in the figure). This is because the connection point of the first support is used as a reference for positioning of the tanks 1 and 2. For this purpose, the first support itself is also made of a material having the least heat shrinkage and expansion, for example, manufactured by filament winding. Preferred is CFRP.

On the other hand, as shown in FIG. 3, the second support member 6 has a deformable support seat 8 fixed to the inner surface of the vacuum chamber 1 and one end is fixed to the support seat 8 by screwing, and the other end is fixed. Are connected to the refrigerant tank 2 by using a movable connection portion 9 having a displacement absorption capability in a direction perpendicular to the axis.

Since the second support member needs heat insulation, stainless steel, GFRP, or CFRP, which has poor thermal conductivity, is used. It may be smaller than in the case of connecting.

The deformable support seat 8 is made of a material which is more easily deformed in consideration of a material for forming the second support seat. The position of the support seat 8 can be interchanged with that of the connecting portion 9, but when cooled, the support seat 8 becomes hard and hardly deformed.
It is preferable to provide it on the vacuum tank side.

The movable connecting part 9 includes a spherical seat 10 fixed to the refrigerant tank and a nut.
It comprises a movable spherical seat 11 integrated with 12 and abutted against 10, so that the seat 11 can slide 360 degrees in a plane perpendicular to the axis. In addition, even after the support member 6 is displaced to the maximum, the spherical seats 10 and 11 are not in contact with each other as shown in FIG. Sufficient clearance is secured between the seat 6 and the support member 6.

This connecting portion 9 is provided for the following reason. That is, when the support member 6 is on the opposite side of 180 from the member 5, such a connection is not necessary because the stress applied to the member 6 is only the radial force of the tank. However, when 6 is at the position shown in the figure, for example, when the refrigerant tank contracts and expands, the connection with the refrigerant tank becomes θ in FIG.
There is also a risk that the part will be displaced in the circumferential direction indicated by, and will be deformed if the part is a rigid structure connection. The larger the tank, the larger the amount of displacement in the θ direction, so the possibility of deformation is high.

Therefore, as a measure against the deformation, the amount of displacement in the θ direction is absorbed by the spherical seat. By taking this measure, the followability of the second support member 6 is further improved, and the refrigerant tank shrinks smoothly.

In the embodiment, the concave portion 13 was provided outside the refrigerant tank 2 and the connecting portion 9 was accommodated in the concave portion because the heat transfer path of the portion passing through the supporting material between the first and second portions became long, and the heat penetration amount However, this configuration may be adopted as needed.

In addition, the support members 5 and 6 are hollow in the embodiment, but may be solid.

In addition, the number of support members 6 and the mounting angle may be arbitrarily determined.

〔effect〕

As described above, in the present invention, the connection of the second support member provided at a position other than the position reference point to the vacuum tank is performed using the variable support seat, and the relative displacement amount of the refrigerant tank and the vacuum tank due to thermal stress is determined. Since it was made to absorb by the deformation of the above-mentioned deformable support seat, and in some cases, it was made to connect also with the refrigerant tank by the connecting part which has a displacement absorption capability in the direction perpendicular to the axis. No excessive force is applied.

Therefore, the second support member can reduce the cross-sectional area and reduce the amount of heat intrusion from the room temperature portion, which leads to suppression of evaporation of the refrigerant.

In addition, since the first support member at the reference point where the temperature falls fastest has rigid connections at both ends, the positional relationship between the vacuum tank and the refrigerant tank is determined based on the support member even after cooling, and the refrigerant tank In addition, the positioning of the superconducting coil and the like to be accommodated therein and the position management are facilitated.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of the present invention, and FIG.
FIG. 3 is an enlarged cross-sectional view of the connecting portion of the supporting member, FIG. 3 is an enlarged cross-sectional view of the connecting portion of the second supporting member, and FIG. 4 is a cross-sectional view showing a displaced state of the second supporting member. DESCRIPTION OF SYMBOLS 1 ... Vacuum tank, 2 ... Refrigerant tank, 5 ... 1st support material, 6 ... 2nd support material, 7 ... Fixed seat, 8 ... Deformable support seat, 9 ... Movable connection part, 10 , 11 ... spherical seat, 12 ... nut, 13 ... recess.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 39/04 H01F 7/22

Claims (1)

(57) [Claims] A refrigerant storage tank concentrically arranged in a horizontally arranged vacuum tank is provided between a vacuum reference tank at a plurality of positions other than a position reference point immediately below the storage tank and other positions. A second support member is provided and supported. Further, the first support member at the position reference point has rigid connections at both ends of the two tanks, and the second support member provided at other positions is a vacuum. The connection to the tank is made through a deformable support seat having a lower strength than the second support member, and the connection to the refrigerant storage tank is made by connecting the second support member to the outer periphery of the spherical seat provided in the refrigerant storage tank. A clearance is caused to penetrate, and a connection is made via a relative displacement absorption portion in a direction perpendicular to the axis of a structure in which a corresponding spherical seat on the second support material side is brought into contact with the spherical seat on the center side of the liquid storage tank. Cryostat.