JPH0525366B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a removable radiant heat shield refrigerator device with a superconducting magnet that can be attached and detached without breaking the vacuum of a cryostat.

[Conventional technology]

FIG. 6 is a partial cross-sectional view showing an example of a conventional superconducting magnet, showing the cross-sectional structure of one side of the magnet formed in an annular shape surrounding an axis Z-Z.
In the figure, 1 is a cryostat, which is cooled to an absolute temperature of about 77K by a liquid nitrogen container 5N between a helium container 3 containing a superconducting coil 7 immersed in liquid helium 6 and a vacuum tank 2 surrounding it. The low-temperature radiant heat shield 4 is thermally conductively connected to a port 5P communicating with the helium container 3, and is maintained at about 20K, and is maintained at about 20K in a vacuum. Radiant heat from the side of the container 2 is absorbed by the medium and low temperature radiant heat shields 4 and 5 to reduce consumption of the liquid helium 6 contained in the helium container 3. In such a conventional superconducting electromagnet, the cryostat 1 has a large outer diameter because it houses a 5N liquid nitrogen container, and requires replenishment of liquid helium and liquid nitrogen, making maintenance work complicated and replenishment difficult. There was a drawback that the device became complicated.

FIG. 7 is a side sectional view of the main parts of the improved conventional device, in which a two-stage helium refrigerator 11 dedicated to cooling the medium and low temperature radiant heat shields 5 and 4 is partitioned into the vacuum chamber 2 of the cryostat 1. It is provided removably within the storage container 21. That is, the storage container 21 is airtightly connected to the upper flange 23, which is airtightly connected to the vacuum container 2, and the two-stage helium refrigerator 11 (hereinafter simply referred to as the refrigerator) to support the refrigerator. It consists of a lid plate 22, an intermediate flange 25 airtightly connected to the upper flange 23 via a telescoping tube 24, and a bottom plate 27 airtightly connected to the intermediate flange 25 via a telescoping tube 26. The interior of the storage container 21 can be evacuated via an exhaust pipe 39.

The refrigerator 11, which is airtightly connected and supported by the lid plate 22, is equipped with a low-temperature cooling head 14 at the tip of a series body of cylinders 12 and 13 (hereinafter referred to as a stepped cylinder), and a medium-temperature cooling head 15 at the intermediate step. The temperature reached by the low-temperature cooling head 14 is almost the absolute temperature due to the helium refrigerant circulating between the circulation system consisting of a plurality of heat exchangers built into the refrigerator and the compressor (not shown).
20K, the temperature reached by the medium temperature cooling head 15 is cooled to a predetermined temperature in the range of 50K to 80K.

The medium temperature cooling head 15 is connected using four holes 32B to a cross-shaped heat conduction plate 32 which has an insertion hole 32A for the cylinder 13 in the center shown in FIG. 10, and the details of the heat conduction plate 32 are shown in FIG. A terminal hole 25 is connected to the intermediate flange 25 shown by bolts 34 passing through four holes 32C and 25C, respectively, and is formed in the outer protrusion of the telescopic tube of the intermediate flange.
A heat conduction path is formed between the medium temperature cooling head 15 and the medium temperature radiant heat shield 5 by attaching a heat conduction lead 17 made of a flexible thermal conductor that connects the medium temperature radiant heat shield 5 to the medium temperature cooling head 15. On the other hand, the low temperature cooling head 14 is bolted to the four screw holes 36E of the cross-shaped heat conduction plate 36 as shown in FIG. The heat conductive plate 36 is fixed to the bottom plate 27 by bolts 38 passing through four holes 36F, and
8 is a low-temperature radiant heat shield 4 by a heat conduction lead 18
A heat conduction path on the low temperature side is formed by being connected to.

In addition, in order to enable attachment and detachment of the two-stage helium refrigerator 11 to and from the storage container 21 installed in advance in the vacuum chamber 2, the insertion opening 35 of the attachment/detachment tool 33 for the eight evenly distributed coupling bolts 34 and 38 is provided. As shown in FIG. 8, which is a plan view of the cover plate 22, eight pieces are provided on the same circumference, and a ninth
As shown in the figure, a cutout 25F is formed through which the cross-shaped heat conductive plate 36 on the low temperature side can pass. Therefore, when attempting to remove the refrigerator, the four holes 25
By vertically inserting the attachment/detachment tool 33 from the insertion port 35 corresponding to C, the medium temperature side coupling bolt 34 can be removed.
The low-temperature side coupling bolt 38 located below can be removed through the insertion opening corresponding to the notch 25F.
Therefore, by removing the coupling bolts 37 between the cover plate 22 and the support flange 23, the refrigerator 11 can be pulled out from the storage container 21 with the cover plate 22, heat conductive plates 32 and 36 coupled together.

In the improved conventional device described above, the radiant heat shields 5 and 4, which have two layers of medium temperature and low temperature, are cooled to predetermined temperatures, for example, 80K and 20K by the refrigerator, so there is no need to provide a liquid nitrogen container 5N in the cryostat 1. This has the advantage that the outer diameter of the cryostat is reduced and maintenance becomes easier.
Since the refrigerator is housed in the storage container 21 and separated from the high vacuum section in the vacuum chamber 2, in the event of a malfunction of the refrigerator, it is possible to attach and detach the refrigerator while leaving the vacuum chamber 2 in a vacuum. Once humid air enters and the insulation material (not shown) inside the vacuum chamber absorbs moisture, the problem is that it takes a very long time to remove this moisture and restore high vacuum again. It can be avoided.

[Problem that the invention seeks to solve]

In the refrigerator device with the improved removable radiant heat shield described above, the storage container 21 is returned to atmospheric pressure while the high vacuum in the vacuum chamber 2 is maintained.
1, an external pressure of 1 kgf/cm ² is applied to the storage container 21 from the atmospheric pressure side, and the bottom plate 27
is pulled in the direction of stretching the telescopic tube under a huge load of P=πD ² /4Kgf (D is the inner diameter of the telescopic tube, cm). The telescopic tubes 24 and 26 are equipped with connecting bolts to suppress excess elongation so that the telescopic tubes are not damaged, but most of the above load is applied to the cylinders 13 and 12 of the refrigerator 11, which have small diameters. This may lead to damage to the cylinder 13 on the low temperature side. In particular, because the main focus of the construction is to make it easier to attach and detach the refrigerator by vertically inserting the coupling bolt attachment/detachment tool, the inner diameter of the expandable tube becomes large, and the inner diameter increases to the square of the inner diameter. There was a drawback that the proportionally increasing load P became significantly large. In addition, the structure becomes complicated, as it requires a number of tool insertion holes corresponding to all the connecting bolts on the medium and low temperature sides, and a heat conduction plate is required on each of the medium and low temperature sides. The disadvantage was that the assembly work and the disassembly work of the refrigerator were complicated.

This invention aims to reduce the load applied to the refrigerator and facilitate assembly and disassembly work by streamlining the structure of the device.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention includes a storage container that partitions the inside of the vacuum container of a cryostat, and a medium-temperature cooling head and a distal end of a stepped cylinder that is removably supported by the storage container. It is equipped with a two-stage helium refrigerator having a low-temperature cooling head in the vacuum chamber, and a medium-temperature radiant heat shield and a low-temperature radiant heat shield enclosed in the vacuum container so as to double surround the helium container containing the superconducting coil to a predetermined temperature. In the cooling device, the lid plate is airtightly connected to the vacuum container, the lid plate is airtightly connected to the lid plate via an expansion tube, and is heat conductively connected to the medium temperature radiant heat shield, and the low temperature cooling head passes through the center of the lid plate. an intermediate flange that also serves as a medium-temperature heat conduction plate having a hole that can be opened, and an intermediate flange that also serves as a low-temperature heat conduction plate that is airtightly coupled to the intermediate flange via a telescopic tube having an inner diameter smaller than that of the telescopic tube and heat conductively coupled to the low-temperature radiant heat shield. A storage container consisting of a bottom plate, and a middle temperature cooling head which is airtightly connected and supported to the center of the lid plate and inserted into the storage container, a medium temperature cooling head on the intermediate flange, and a low temperature cooling head on the bottom plate facing the axis of the stepped cylinder. The two-stage helium refrigerator was previously connected by the same number of connecting bolts that maintained a predetermined angle and were arranged in the same angular area in the circumferential direction, and the connecting bolts were attached to each of the lid plate and the intermediate flange. and an insertion hole for an attachment/detachment tool for the coupling bolt formed in the extension direction of the axis of the coupling bolt in the arrangement angle region.

[Effect]

In the structure of this invention, the intermediate flange has the function of a heat conductive plate on the medium temperature side, and the bottom plate has the function of a heat conductive plate on the low temperature side, and the medium temperature cooling head is bolted to the intermediate flange at a position close to the cylinder for low temperature cooling. Since the head is bolted to the bottom plate at a position close to the cylinder, it is possible to reduce the required area of the bottom plate, or in other words, to reduce the inner diameter of the telescopic tube between the bottom plate and the intermediate flange, allowing the vacuum chamber to be stored in a vacuum state. When the container is brought to atmospheric pressure, the load applied to the refrigerator cylinder is reduced. In addition, the number and circumferential position of the connecting bolts on the medium-temperature side and the low-temperature side are equal to each other, and they are inclined toward the axis of the cylinder, and the attachment/detachment tool is inserted into the cover plate and intermediate flange on an extension of the axis of the connecting bolts. Since the coupling bolts and insertion holes are aligned so that holes are provided, it is possible to attach and detach the coupling bolts on both the medium temperature side and the low temperature side placed in the same angular area by inserting the attachment/detachment tool diagonally from the insertion hole. Therefore, by reducing the number of insertion holes and eliminating the heat conductive plate, the structure can be simplified and assembly and disassembly work can be made easier.

〔Example〕

The present invention will be explained below based on examples.

FIG. 1 is a side sectional view showing a device according to an embodiment of the present invention, and the same parts as in the prior art are given the same reference numerals and detailed explanations will be omitted. In the figure, the storage container 41 includes a lid plate 42 that is airtightly connected to the vacuum chamber 2, an intermediate flange 45 that also serves as a medium temperature heat conduction plate that is airtightly connected via a telescopic tube 44, and an inner diameter smaller than that of the telescopic tube 44. The intermediate flange 45 and the bottom plate 47 are airtightly connected to each other via a telescopic tube 46, and the bottom plate 47 also serves as a low temperature heat conduction plate. They are each thermally conductively coupled to the radiant heat shield 4. The refrigerator 11 is hermetically bolted to the center of the lid plate 42, and the stepped cylinders 12 and 13 are inserted into the storage container 41. The medium temperature cooling head 55 is heat conductively connected to the intermediate flange by a connecting bolt 57, and the low temperature The cooling head 54 is heat conductively connected to the bottom plate 54 by connecting bolts 58, thereby forming heat conduction paths on the medium temperature side and the low temperature side.

Fig. 2 is a plan view of the lid plate in the embodiment device, Fig. 3 is a plan view of the medium temperature cooling head, Fig. 4 is a plan view of the intermediate flange, and Fig. 5 is a plan view of the low temperature cooling head. The figures are shown so that the circumferential positional relationships correspond to each other. The low temperature cooling head 54 is formed in a cross shape as shown in FIG. 5, and the medium temperature cooling head 55 is formed in a circular shape as shown in FIG. They are coupled to the stepped cylinder of the refrigerator 11 so that the angular regions of their arrangement substantially coincide with each other. Further, a cross-shaped hole 45B through which the low-temperature cooling head 54 can pass is formed in the intermediate flange 45 in a direction 45° different from that of the low-temperature cooling head 54. Therefore, the refrigerator 11 is rotated 45 degrees in the circumferential direction and inserted into the storage container 41, and the low-temperature cooling head 54 is inserted.
After passing through the hole 45B of the intermediate flange, the refrigerator 1
1 by 45 degrees in the opposite direction, the refrigerator will be set in its normal position in the storage container.

In addition, four connecting bolts 57 and 5 are provided, respectively.
Reference numeral 8 denotes an attachment/detachment tool 33 formed on the cover plate 42 whose axial extension direction is shown in FIG. 2 in the coupled state.
It is installed obliquely toward the axis of the stepped cylinder so as to coincide with the center p of the insertion hole 62 of the cooling head, and its inclination angle is maintained by the inclination angle of the upper surface of the cooling head and the inclination angle of the bolt holes 55A, 45A, 54A, etc. be done. Also, the coupling bolt 58 on the low temperature cooling head side
As shown in FIG. 4, an insertion hole 65 for an attachment/detachment tool is formed in the intermediate flange 45 on the line connecting the points P and 45 in the same angular direction as the coupling screw hole 45A of the coupling bolt 57. Therefore, in order to attach and detach the four connecting bolts 57 and 58 of the refrigerator 11 set in the fixed position of the storage container 41, the attachment/detachment tool 33 holding the bolts must be inserted through the four insertion holes 62 to the two axes. This can be easily done by inserting along the

In the embodiment device configured in this way,
The inner diameter of the telescopic tube 46 between the intermediate flange and the bottom plate can be reduced to 60% of that of the conventional device. This is the tensile load applied to the cylinder 13 in the conventional device.
This means that 1000Kgf can be reduced to 360Kgf, thereby avoiding damage to the refrigerator. In addition, the number of insertion holes for the attachment/detachment tool is reduced to half of that of the conventional device, and the number of parts is reduced because the intermediate flange and bottom plate also serve as the heat conductive plate in the conventional device. The structure is simplified and assembly and disassembly work is facilitated.

〔Effect of the invention〕

As described above, this invention allows the intermediate flange and bottom plate of a storage container that airtightly partitions the inside of a vacuum chamber to also function as a heat conductive plate in a conventional device, and also connects the cooling head of a refrigerator to the intermediate flange and bottom plate. The structure is streamlined by making relative alignment between the bolt installation structure arrangement and the insertion part of the connection bolt attachment/detachment tool. As a result, the inner diameter of the expansion tube on the bottom plate side is smaller than that of the conventional device.
60%, and the tensile load applied to the refrigerator cylinder when the storage container is brought to atmospheric pressure is approximately 1/1 of that of conventional equipment.
3, it is possible to provide a removable radiant heat shield refrigerator device with a superconducting magnet that can remove the refrigerator while maintaining the high vacuum state of the vacuum chamber without damaging the refrigerator. In addition, the structure is simplified, making it easier to assemble and disassemble the device, and there are advantages in improving economic efficiency.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing an embodiment of the device of the present invention, FIGS. 2, 3, 4, and 5 are plan views showing different main parts of the embodiment device, and FIG. FIG. 7 is a side sectional view showing the main parts of a conventional superconducting magnet. FIG. 7 is a side sectional view showing an improved conventional device. FIGS. 8, 9, 10, and 11 are improved conventional devices. FIG. 1... Cryostat, 2... Vacuum chamber, 3...
...Helium container, 4...Low temperature radiant heat shield, 5
...Medium temperature radiant heat shield, 6...Liquid helium,
7... Superconducting coil, 11... Two-stage helium refrigerator, 12, 13... Stepped cylinder, 14, 54
...Low temperature cooling head, 15,55...Medium temperature cooling head, 21,41...Storage container, 22,42...
Lid plate, 24, 44, 26... Telescopic tube, 46... Telescopic pipe (reduced), 25, 45... Intermediate flange, 2
7, 47... Bottom plate, 34, 57... Connection bolt (medium temperature side), 38, 58... Connection bolt (low temperature side),
35, 62, 65...insertion hole.

Claims (1)

[Scope of Claims] 1. A storage container that partitions the inside of the vacuum container of the cryostat, and a stepped cylinder that is removably supported by the storage container and has a medium-temperature cooling head in the middle part and a low-temperature cooling head in the tip part. and a helium refrigerator for cooling a medium-temperature radiant heat shield and a low-temperature radiant heat shield enclosed in the vacuum container to a predetermined temperature, respectively, so as to double surround a helium container housing a superconducting coil, A lid plate is airtightly connected to the lid plate, and a medium temperature heat conduction plate is airtightly connected to the lid plate via an expansion tube, is heat conductively connected to the medium temperature radiant heat shield, and has a hole in the center thereof through which the low temperature cooling head can pass. a storage container comprising an intermediate flange that also serves as a low-temperature heat conduction plate; and a bottom plate that also serves as a low-temperature heat conduction plate that is airtightly connected to the intermediate flange via a telescopic tube having an inner diameter smaller than that of the expandable tube and thermally conductively connected to the low-temperature radiant heat shield, and the lid; They are airtightly connected and supported at the center of the plate and inserted into the storage container, with a medium-temperature cooling head attached to the intermediate flange and a low-temperature cooling head attached to the bottom plate while maintaining a predetermined angle toward the axis of the stepped cylinder in the circumferential direction. The two-stage helium refrigerator is connected to each other by the same number of connecting bolts arranged in the same angular area, and the connecting bolts are connected to each other by the connecting bolts arranged in the same angular area. A superconducting magnet detachable radiant heat shield refrigerating machine device, comprising an insertion hole for an attachment/detachment tool for the coupling bolt formed in the extending direction of the axis. 2. In what is stated in claim 1,
The temperature reached by the low-temperature cooling head of a two-stage helium refrigerator is approximately 20K, and the temperature reached by the medium-temperature cooling head is 50K.
A removable radiant heat shield refrigerator device with a superconducting magnet characterized by a temperature of 80K to 80K.