JPH05259515A - Position adjustment mechanism of cryostat - Google Patents

Abstract

PURPOSE:To provide the function of absorbing positioning stroke movement and thermal contraction movement and a cushion function during transportation by combining a dynamic bellows and a coil spring. CONSTITUTION:A refrigerant bath 3 is supported by a supporting rod. The supporting rod is integrally formed of a lower supporting rod 11a whose one end is fixed to the refrigerant bath 3 and an upper supporting rod 11b which is taken out to the outside passing through a vacuum bath 6. A nut 12 for position adjustment is screwed to an upper end part of the upper supporting rod 11b. A pedestal 7 is attached to the vacuum bath 6 and a coil spring 10 is interposed on the pedestal 7. The pedestal 7 is provided with a dynamic bellows 8 whose upper end and lower end are airtightly welded. A position of the refrigerant bath 3 is adjusted by rotating the nut 12. A tension applied to the supporting rod in the process is absorbed by displacement of the coil spring 10 and a movement amount is absorbed by displacement of the dynamic bellows 8. The coil spring 10 functions as a cushion during transportation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position adjusting mechanism for a refrigerant tank housed inside a cryostat.

[0002]

2. Description of the Related Art FIG. 1 is a sectional view of an example of a conventional position adjusting mechanism for a cryostat. (See Jpn. Pat. Appln. 1-32603). A structure such as a refrigerant tank is housed in a casing 21 of the cryostat via a support member 22. The position adjusting mechanism includes a cylinder 23 fixed to the casing 21 of the cryostat, a rod 24 with a thread that is slidably and non-rotatably inserted into the cylinder 23, and a nut that is screwed into the thread portion of the rod 24. Has 30.

The cylinder 23 includes a cylindrical portion 23a and the cylindrical portion 23a.
It has a flange 23b formed at the outer end of a and a rectangular hole 23c formed at the inner end. The rod 24 has a threaded portion 25 at one end and a mounting portion 26 to the support member 22 at the other end. Furthermore, in the middle part of the rod 24,
A sliding portion 27 that slidably contacts the inner wall of the cylinder 23 is formed, and a fitting groove 28 for an O-ring 29 is formed on the outer periphery of the sliding portion 27. And the cylinder located on the side of the support member 22
The rectangular part is engaged with the rectangular hole 23c of 23 in a non-rotating manner.
24a is formed.

The nut 30 is locked on the surface of the flange 23b of the cylinder 23 which is in contact with the outer surface of the housing 21. And
When this nut 30 is tightened, the rod 24 moves outward,
The support member 22 connected to the end of the rod 24 is displaced in the same direction.

[0005]

The above-described conventional position adjusting mechanism is a cylinder system in which a rod and a cylinder are combined and the position is adjusted by sliding the rod. However, the following problems are encountered. There is a point. (1) Vacuum sealing in the cryostat of the sliding part of the rod is performed by providing an O-ring groove in the rod and positioning the O-ring in the groove.
The ring deteriorates and the sealing performance deteriorates. (2) If the rod is slightly eccentric, an uneven load is applied to the O-ring, a problem occurs in the sealing property, and the O-ring is damaged quickly. (3) Since there is no mechanism for absorbing the amount of heat shrinkage during cooling, it is necessary to leave the rod in a free state or a state close to it in advance. However, in such a state, the displacement of the internal structure cannot be regulated. .. (4) There is no cushion mechanism for transporting the cryostat, and it is necessary to separately prepare a cushion mechanism for transport.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above problems and provides a position adjusting mechanism for a cryostat which has a cushioning function during transportation in addition to a function of absorbing a position moving stroke and a thermal contraction moving amount. The feature is that the support rod of the refrigerant tank is taken out by penetrating to the outside of the vacuum tank accommodating the refrigerant tank, and combined with the dynamic bellows and the coil spring in this portion, it is configured to perform the above function. is there.

[0007]

1 is a partially cutaway sectional view of a concrete example of a cryostat having a position adjusting mechanism of the present invention, and FIG. 2 is a detailed sectional view of a position adjusting mechanism portion. In the drawing, reference numeral 1 is a superconducting coil housed in the refrigerant tank 3,
The inside is filled with a refrigerant 2 such as liquid helium or liquid hydrogen. The refrigerant tank 3 is housed in a vacuum tank 6 forming an outer cylinder, a vacuum heat insulating layer 4 is formed in the vacuum tank 6, and a radiant heat shield plate is provided between the vacuum tank 6 and the refrigerant tank 3. 5
Is provided.

The coolant tank 3 is supported by a support rod. This support rod is a lower support rod whose one end is fixed to the refrigerant tank 3.
11a and an upper support rod that penetrates the vacuum chamber 6 and is taken out to the outside
An end portion of 11b is integrated by screwing, and a screw for a necessary stroke is cut at the upper end portion of the upper supporting rod 11b, and a nut 12 for position adjustment is screwed into this. The upper support rod 11b is included on the vacuum chamber 6 and the pedestal 7 is attached with screws.
A seat 9b mounted on the pedestal 7, which is attached by 13
The coil spring 10 is inserted between the seat 9a provided on the lower part of the nut 12 and the nut 12. As the coil spring 10, a coil spring having a necessary spring constant according to the load is used. Further, inside the pedestal 7, there is provided a dynamic bellows 8 whose upper end is hermetically welded 14a to the upper support rod 11b and whose lower end is hermetically welded 14b to the upper surface of the vacuum chamber 6. Then, the welds 14a, 14
The b serves as a vacuum seal for the penetrating portion of the support rod 11b of the vacuum chamber 6. Reference numeral 15 is a cover that covers the position adjusting mechanism.

[0009]

The position of the refrigerant tank 3 is adjusted by rotating the nut 12 screwed onto the upper end of the upper support rod 11b. Further, since the refrigerant tank 3 contracts during cooling, tension is applied to the support rod, but this force is absorbed by the displacement of the coil spring 10. Further, the moving amount of the support rod moving up and down is absorbed by the displacement of the dynamic bellows 8. Furthermore, the coil spring 10 exerts a cushioning action during transportation.

The degree of vacuum in the vacuum chamber 6 is 1 × 10 ^-7 to 1 × 10 ^-6
In the order of Torr, if both ends of the dynamic bellows 8 are hermetically welded to the support rod 11b and the upper surface of the vacuum chamber 6 to form a seal portion, even if the support rod is displaced,
Sealability does not matter.

[0011]

As described above, according to the position adjusting mechanism of the present invention, the use of the coil spring can absorb the displacement stress of the support rod, the refrigerant tank, etc. at the time of thermal contraction, so that the support rod can be destroyed or It is possible to prevent excessive load. In addition, the coil spring also serves as a cushion during transportation. By using the dynamic bellows, the stroke can be absorbed comfortably even if the support rod is eccentric. Also, the vacuum sealing can be surely performed by welding, and there is no problem even if the number of repetitions is large, and the life is extended.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view of a specific example of a cryostat having a position adjusting mechanism of the present invention.

FIG. 2 is a detailed cross-sectional view of the position adjusting mechanism portion of FIG.

FIG. 3 is a sectional view of an example of a conventional cryostat position adjusting mechanism.

[Explanation of symbols]

 1 Superconducting magnet 2 Refrigerant 3 Refrigerant tank 4 Vacuum insulation layer 5 Radiant heat shield plate 6 Vacuum tank 7 Pedestal 8 Dynamic bellows 9a, 9b Coil spring seat 10 Coil spring 11a, 11b Support rod 12 Position adjusting nut 13 Mounting screws 14a, 14b Welding seal part 15 cover

Claims (1)

[Claims] 1. A support rod of a refrigerant tank is penetrated and taken out of a vacuum tank accommodating the refrigerant tank, and is combined with a dynamic bellows and a coil spring in this portion to absorb a position movement stroke and a heat contraction movement amount. The position adjustment mechanism of the cryostat, which is characterized.