JPH04328881A - Cryogenic device - Google Patents

Abstract

PURPOSE:To simplify a cryogenic device in support structure by a method wherein the thermal shrinkage of a multilayer radiation heat shield is absorbed through the deformation of the radiation heat shield itself and the sliding of the radiation heat shields on each other. CONSTITUTION:A cryogenic device is formed of a two-layered shield composed of a low temperature radiation heat shield 5 which is fully fixed by a horizontal support means 7 and fixed only in a vertical direction through a vertical support means 8 and a high temperature radiation heat shield 6 which is not fixed by the vertical support means 8, where the thermal shrinkage difference between the shields 5 and 6 is absorbed by the deformation of the high temperature radiation heat shield 6 and the sliding of the shields 5 and 6 on each other.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic device that houses, for example, a superconducting magnet winding, and more particularly to a support structure that supports a cryogenic container and a radiant heat shield within a vacuum container.

0002

2. Description of the Related Art FIG. 4 shows, for example,
7 is a cross-sectional view showing a support mechanism for a superconducting magnet winding container, which is a type of cryogenic device disclosed in Publication No. 7. FIG. In the figure,
1 is a cryogenic container that is kept cooled to an extremely low temperature, and 2
3a is a low-temperature radiant heat shield arranged to cover the outer wall of the cryogenic container 1; 3b is a high-temperature radiant heat shield arranged to cover the outside of the low-temperature radiant heat shield 3a. It is a shield. Reference numeral 4 denotes a hanging mechanism that suspends and supports the cryogenic container 1, the low temperature radiant heat shield 3a, and the high temperature radiant heat shield 3b from the vacuum container 2, and 12 holds the position of the vacuum container 2 and the cryogenic container 1, and its length is variable. This is a compression strut. FIG. 5 is an enlarged sectional view showing the configuration of the compression strut 12. As shown in FIG. In the figure,
12a is a first tube strut firmly fixed to the low-temperature radiant heat shield 3a and the high-temperature radiant heat shield 3b; 12b is a second tube strut partially fitted with the first tube strut 12a;
2c is a spring attached to press the second tube support 12b toward the cryogenic container 1;
A compression strut 12 is constituted by the compression struts 12c.

Next, the operation will be explained. Cryogenic container 1
It is suspended from the vacuum container 2 by a hanging mechanism 4 and its vertical position is fixed. On the other hand, in the horizontal direction, the compression strut 12 is moved between the cryogenic container 1 and the vacuum container 2 by the spring 12c.
It is supported by tightening the gap between the two. The intervals between the low-temperature radiant heat shield 3a, the high-temperature radiant heat shield 3b, and the vacuum container 2 are fixed because each is firmly fixed to the first tube support 12a. Next, the behavior of each component before and after cooling is as follows. Before cooling, the temperature of each component is the same as that of the vacuum container 2, and by adjusting the hanging mechanism 4 and compression strut 12, the cryogenic container 1, low temperature radiant heat shield 3a, and high temperature radiant heat shield 3b are moved to predetermined positions. Fixed.

On the other hand, the behavior of each component after cooling is such that the vacuum container 2 remains constant at room temperature, and the temperature decreases in the order of the high temperature radiant heat shield 3b, the low temperature radiant heat shield 3a, and the cryogenic container 1. Therefore, since the temperature of each component is different, there will be a difference in the amount of thermal contraction. Furthermore, hanging mechanism 4
Since the temperatures of the parts of the compressor struts 12 that are in contact with the vacuum vessel 2, the high temperature radiant heat shield 3b, the low temperature radiant heat shield 3a, and the cryogenic vessel 1 are different, a temperature gradient occurs and uneven thermal contraction occurs. . In the configuration of FIG. 3, the cryogenic container 1 moves upward with respect to the vacuum container 2 due to thermal contraction of the hanging mechanism 4. In addition, since the cryogenic container 1 itself also undergoes thermal contraction, the distance between the vacuum container 2 and the cryogenic container 1 at the attachment portion of the compression strut 18 further increases. For this displacement, compression strut 1
2, the second pipe support 12b is pushed out by the action of the spring 12c, and its entire length is extended to absorb the displacement. However, the high temperature radiant heat shield 3b and the low temperature radiant heat shield 3a are firmly fixed by the suspension mechanism 4 and the first tube strut 12a of the compression strut 12.
2 must have a sufficient cross-sectional area to support the stress caused by the difference in thermal contraction between the two radiant heat shields through shear and tension.

[0005]

[Problems to be Solved by the Invention] Since the conventional cryogenic equipment is constructed as described above, the normal temperature part and the cryogenic part are connected via a radiant heat shield support rod, and heat intrusion due to heat conduction is prevented. be. In addition, since deformation due to heat contraction is absorbed by the spring in the support rod, the structure of the support structure itself becomes complicated and the number of parts increases, and the support structure itself receives thermal stress due to heat contraction of the radiant heat shield. There are problems in that the component parts become larger and the number of support structures must be increased by shortening the distance between the support structures, which increases the amount of heat conducted into the cryogenic part.

[0006] This invention was made in order to solve the above-mentioned problems, and has a simple structure that eliminates heat intrusion due to heat conduction from a normal temperature area to an extremely low temperature area via a radiant heat shield support structure. The object of the present invention is to obtain a cryogenic device having a support structure that can easily absorb thermal contraction of a radiant heat shield.

[0007]

[Means for Solving the Problems] A cryogenic apparatus according to the present invention is such that a radiant heat shield provided to cover a cryogenic container housed in a vacuum container has an open top surface and covers the outer wall side of the cryogenic container. at least two layers of a low-temperature radiant heat shield disposed on the top surface and a high-temperature radiant heat shield disposed with an open top surface and disposed so as to cover the outer wall of the low-temperature radiant heat shield; Suspension means for supporting the radiant heat shield lid and the cryogenic container by suspending them from the inner wall of the upper surface of the vacuum container and suspending each of the radiant heat shield lid and the cryogenic container with a gap between them. and a plurality of them are arranged around the radiant heat shield and engage with each radiant heat shield,
Horizontal support means for positioning between the respective radiant heat shields and positioning both radiant heat shields in the horizontal direction by having an end protruding from the high temperature radiant heat shield side contact the inner wall of the vacuum container, and a bottom portion that engages with each radiant heat shield. and a vertical support means for positioning between the respective radiant heat shields and vertically positioning each radiant heat shield by having an end protruding from the high temperature radiant heat shield side contacting the bottom inner wall of the vacuum container. It is something that

[0008]

[Function] In the cryogenic apparatus of the present invention, the low temperature radiant heat shield is self-supporting and has no support part for the cryogenic container, so there is no heat intrusion from the radiant heat shield to the cryogenic container due to heat conduction. Further, the difference in the amount of thermal contraction of each layer of the radiant heat shield is absorbed by sliding the length change of each layer of the radiant heat shield in a fixed direction in the support structure and by deforming the radiant heat shield itself within an elastic deformation range. In addition, the difference in the amount of heat shrinkage between the vacuum container and the radiant heat shield is absorbed by sliding the tip of the support structure that supports the radiant heat shield and is in contact with the vacuum container, so the force acting on the support structure itself can be reduced. .

[0009]

[Example] Example 1. FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the horizontal support means in FIG. 1, and FIGS. 3a and 3b are enlarged sectional views of the vertical support means in FIG. 1. In the figure, 1 and 2 have the same structure as the conventional structure, so the explanation thereof will be omitted. 5 is a low-temperature radiant heat device consisting of a shielding part 5a having an opening 5b at the top and arranged to cover the cryogenic container 1 and the outer wall, a reinforcing plate 5c reinforcing this, and a plurality of screw seats 5d fixed to the bottom of the shielding part. The shield 6 is a high-temperature radiant heat shield consisting of a shielding part 6a having an opening 6b on the upper surface and arranged to cover the outer wall of the low-temperature radiant heat shield 5, and a reinforcing plate 6c for reinforcing the shield, 10 a high-temperature radiant heat shield having an air gap with the low-temperature radiant heat shield 5. 11 is a cooling pipe provided in contact with the low temperature radiant heat shield 5 and the radiant heat shield cover 10;
7 is a washer 7 attached to the reinforcing plate 5c of the low temperature radiant heat shield 5 on one side.
A holding rod 7a is held by a nut 7c and the other end is in contact with the high temperature radiant heat shield 6, and one end of the holding rod 7a is screwed to the other end, and the high temperature radiant heat shield 6 is held between a washer 7f and a nut 7d. and a horizontal support means 8 consisting of an adjustment rod 7b whose other end is in contact with the inner wall of the vacuum container 2; one end of the horizontal support means 8 is screwed onto the screw seat 5d on the central side, and the other end is inserted through the high temperature radiant heat shield 6 with a gap therebetween. A washer 8c whose end portion abuts the inner wall of the vacuum container 2 and is inserted through the high temperature radiant heat shield 6 is attached to a lower part and a retaining ring 8d is attached to determine the vertical position of both the radiant heat shields 5 and 6. Vertical support means consisting of a support member 8a and a support rod 8e, one of which is screwed onto the screw seat 5d on the end side and the other of which is inserted into the high temperature radiant heat shield 6 with a gap and whose end abuts the inner wall of the vacuum container 2. , 9 are suspended from the upper inner wall of the vacuum container 2, and the radiant heat shield lid 10 and the cryogenic container 1 are mounted on the lower side.
This is a suspension means for suspending the rods, each with a gap.

Next, the operation of the present invention will be explained. First, a method for assembling a cryogenic apparatus configured with the support means as described above involves attaching the holding rod 7a of the horizontal support means 7 and the support members 8a and support rods 8e of the vertical support means 8 to the low temperature radiant heat shield 5. It is attached and inserted into the high temperature radiant heat shield 6. After insertion, horizontally position both radiant heat shields and the vacuum container 2 using the adjustment rod 7b, and then tighten the nut 7.
d fixes the adjustment rod 7b, and the washer 8c and retaining ring 8d position the high-temperature radiant heat shield in the vertical direction, allowing support structure components to be easily attached from the outside of the radiant heat shield. Note that the support rod 8c does not support the high-temperature radiant heat shield 6, but supports part of the vertical support of the high-temperature radiant heat shield 6 with the horizontal support means 7 via the low-temperature radiant heat shield 5.

Next, the operation during cooling will be explained. The low-temperature radiant heat shield 5 is cooled by the cryogen flowing inside the cooling pipe 10. The high temperature radiant heat shield 6 takes a temperature at a balance point between the radiant heat from the low temperature radiant heat shield 5 and the radiant heat from the vacuum container 2. This causes a difference in the amount of thermal contraction between the two radiant heat shields. There are two directions of heat shrinkage: horizontal and vertical. Against horizontal heat contraction, the horizontal supporting means 7 completely fixes both radiant heat shields, and a reinforcing plate 5c is provided on the low temperature radiant heat shield 5 side at this position, and the reinforcing plate 6c of the high temperature radiant heat shield 6 is attached to this position. By avoiding this position, the high temperature radiant heat shield 6 can easily deform and absorb thermal contraction.

Also, the inner support member 8a of the vertical support means 8
The high-temperature radiant heat shield 6 is supported in the vertical direction but not fixed in the horizontal direction, so that it can slide in the horizontal direction to absorb heat shrinkage. At the inner support rod 8e portion of the vertical support means 8, the high temperature radiant heat shield 6 is not restrained at all, so there is no problem. Next, regarding thermal contraction in the vertical direction, since the high temperature radiant heat shield 6 is not restrained by the support rod 8e of the vertical support means 8, the thermal contraction of the low temperature radiant heat shield 5 is caused by the horizontal support means 7. It is absorbed by pushing down the lower plate of the high-temperature radiant heat shield 6. Furthermore, by separating the radiant heat shield support means and the cryogenic container support means, heat intrusion into the cryogenic container 1 due to heat conduction is eliminated, and furthermore, the cryogenic container can be removed without removing the radiant heat shield from the vacuum container 2 during disassembly.

Example 2. In the first embodiment, the difference in heat shrinkage is absorbed by bending the shielding part 6a of the high-temperature radiant heat shield 6. However, if both the radiant heat shields have high rigidity and cannot absorb the difference due to bending, there may be multiple radiant heat shields in the surrounding area. Only one of the horizontal support means 7 is connected to 7a or 7.
e, and all other parts are held by 8 of the radiation direction support means 8.
It has the same structure as a to 8d and can be slid in the circumferential direction for absorption. Further, thermal contraction in the vertical direction can be absorbed by sliding the outer side of the lower plate of the high-temperature radiant heat shield 6 by the horizontal supporting means 7 without bending it.

Example 3. Further, in the first embodiment, a two-layer shield has been described, but by making the vertical support means the same structure as the horizontal support means 7, it is possible to use the shield with two or more layers.

Example 4. Furthermore, by constructing the high-temperature radiant heat shield of the above embodiment with a highly permeable material such as permalloy, it is possible to install an object that is adversely affected by a magnetic field, such as a motor of a small refrigerator, in the vicinity of the vacuum container, or When storing items that are adversely affected by a magnetic field similar to the geomagnetic field, such as a Hall element, inside a vacuum container,
It can also serve as a function of magnetically shielding between the inside and outside of the vacuum container, and there is no need to provide a separate magnetic shield, resulting in the effect that effective performance can be obtained with a simple configuration.

[0016]

[Effects of the Invention] As described above, according to the present invention, the radiant heat shield provided to cover the cryogenic container housed in the vacuum container is arranged so as to open the top surface and cover the outer wall side of the cryogenic container. at least two layers of a high-temperature radiant heat shield having an open top surface and disposed to cover the outer wall of the low-temperature radiant heat shield; and a radiant heat shield lid having a gap with each radiant heat shield and disposed to cover the opening. Suspension means for suspending the radiant heat shield lid and the cryogenic container from the inner wall of the upper surface of the vacuum container and suspending each of the radiant heat shield lid and the cryogenic container with a gap therebetween; A plurality of radiant heat shields are arranged around the radiant heat shields to engage with each radiant heat shield to determine the position between the radiant heat shields, and the end protruding from the high temperature radiant heat shield side comes into contact with the inner wall of the vacuum container to horizontally position both the radiant heat shields. and a horizontal support means disposed at the bottom that engages with each radiant heat shield to determine the position between the respective radiant heat shields, and whose end protruding from the high temperature radiant heat shield side abuts the bottom inner wall of the vacuum vessel. Since it is configured with vertical support means to set the vertical position of each radiant heat shield, it has a simple configuration that eliminates heat intrusion due to heat conduction from the room temperature area to the cryogenic area through the radiant heat shield support structure, and also prevents radiant heat This has the effect of providing a cryogenic device with a support structure that can easily absorb thermal contraction of the shield. Furthermore, by configuring one layer of the multi-layer radiant heat shield to also serve as a magnetic shield, it is possible to obtain a function of magnetically shielding the inside and outside of the vacuum container with a simple configuration.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the horizontal support means in FIG. 1 of the present invention.

FIG. 3 is an enlarged sectional view of the vertical support means in FIG. 1 of the present invention.

FIG. 4 is a sectional view showing a support mechanism in a conventional cryogenic device.

FIG. 5 is an enlarged sectional view showing the configuration of the compression strut in FIG. 4;

[Explanation of symbols]

1 Cryogenic container 2 Vacuum container 5 Low temperature radiant heat shield 6 High temperature radiant heat shield 7 Horizontal support means 8 Vertical support means 9 Hanging means 10 Radiant heat shield lid

Claims (2)

[Claims] Claim 1: A cryogenic container cooled to an extremely low temperature by a cryogen, a vacuum container forming a vacuum insulation tank for storing the cryogenic container, and a vacuum container provided between the two containers so as to cover the cryogenic container. In a cryogenic apparatus comprising a radiant heat shield for thermal insulation, and a support element for holding the radiant heat shield and the cryogenic container in the vacuum container with a gap therebetween, the radiant heat shield has an open top surface and the cryogenic container a low-temperature radiant heat shield arranged to cover the outer wall side of the low-temperature radiant heat shield, and a high-temperature radiant heat shield having an open top surface and arranged to cover the outer wall of the low-temperature radiant heat shield, each having a gap with the radiant heat shield. and is formed by a radiant heat shield lid placed over the opening,
The supporting elements are suspended from the inner wall of the upper surface of the vacuum container and suspend each of the radiant heat shield lid and the cryogenic container with a gap therebetween, and a plurality of the supporting elements are arranged around the radiant heat shield and engage with each of the radiant heat shields. horizontal support means for positioning between the respective radiant heat shields, and for positioning the radiant heat shields in the horizontal direction by having an end protruding from the high temperature radiant heat shield contacting the inner wall of the vacuum container; The radiant heat shield is engaged with the radiant heat shield and positioned at the bottom, and the end portion protruding from the high temperature radiant heat shield side is in contact with the bottom inner wall of the vacuum container in the vertical direction of each of the radiant heat shields. 1. A cryogenic apparatus comprising: vertical support means for positioning. 2. The cryogenic apparatus according to claim 1, wherein one layer of the plurality of radiant heat shields also serves as a magnetic shield.