JPS59214280A - Cryostat - Google Patents

Abstract

PURPOSE:To mount or demount a refrigerator easily without thermally disturbing a body to be cooled by transmitting cold heat generated from the refrigerator over a cryostat through a thermal contactor and recondensing the vaporized gas of a refrigerant. CONSTITUTION:An expanding machine 8 for a refrigerator has two stepped cold generating means, and cold heat generated at each step is connected to a cold absorbing section in a receiver 24 through a leaf spring 32 from a cylinder 9. The gate of varporized liquid nitrogen 26 is re-liquefied by a condenser 31 corresponding to a first step through a pipe 29, and returned to a vessel 25 through a pipe 30. When the expanding machine 8 gets trouble and is repaired, a valve 28 is opened, and the expanding machine 8 is drawn out of the receiver 24.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to equipment that operates at extremely low temperatures, particularly to a taliostat that maintains superconducting applied equipment at extremely low temperatures.

[Prior art]

When cooling relatively small superconducting equipment, it is conceivable to use a small refrigerator. FIG. 1 shows an example of a conventional method. 1 is the superconducting coil that is the object to be cooled, 2 is the liquid helium that completely cools the superconducting coil, and 3 is the superconducting coil 1
and liquid helium 2, and is supported within a vacuum container 4 via a heat insulating support 5. Reference numeral 6 denotes a shield installed inside the Makabe container 4 so as to surround the container 3, which is cooled to around the temperature of liquid nitrogen by a refrigerant.

7 may be divided into two pipes for introducing and discharging liquid helium or gaseous helium during the initial stage of cooling.

8 is an expander of a small refrigerator called Gifford-McMahon cycle or Truvey cycle, and cylinder 9
There is a piston 10 with a built-in regenerator therein, which is reciprocated by a drive part 11.

FIG. 1 shows a two-stage expander, in which cold is generated at the tip of each stage, and cooling pipes 12 and 13 are fixed to take out the cold. The refrigerant helium supplied via the first heat exchanger 14 is cooled by the cooling pipe 12, and then cooled by the cooling body 6.
into the second heat exchanger 15, and then into the cooling pipe 1.
3, the temperature is further lowered, the liquid passes through the third heat exchanger 16, expands at the expansion valve 17, and partially liquefies. The refrigerant is in the condenser 18
The third heat exchanger 16 and the second heat exchanger 15
, through the respective low pressure sides of the first heat exchanger 14 and return to the room temperature compressor system 19. The expander, heat exchanger, and compressor system are connected by connecting pipes 20 and 21. The compressor system includes a compressor body, a cooler, a pressure buffer, a filter or a purifier.

During operation of the device, the injection valve 22 is closed, and the superconducting coil 1 is cooled with liquid helium whose temperature is slightly higher than that of the liquid in the condenser 18.

When considering failures, movable parts are most likely to fail, so in the example of FIG. 1, the probability of failure of the expander 8 is high. In order to repair this, the entire Taliostat must be warmed up to room temperature and then disassembled. This makes it impossible to use the superconducting coil continuously.

In this way, in the past, when a refrigerator broke down, the equipment was stopped from being used.
This was a very big problem for devices that were used on a regular basis.

[Purpose of the invention]

An object of the present invention is to facilitate the replacement of parts when a refrigerator breaks down, and to enable continuous maintenance of extremely low temperatures.

[Summary of the invention]

The feature of the present invention is that it is removably fitted to the main body of the frozen root taliostat, and that the cold heat generated by the refrigerator is transmitted to the taliostat via a thermal contact such as a metal plate spring. The reason is that the vaporized refrigerant gas can be recondensed.

[Embodiments of the invention]

An embodiment of the present invention will now be described with reference to FIG. FIG. 2 shows the heat exchangers 14, 15, 16 and expansion valve 17 shown in FIG. There is no condenser 18 loop. therefore,
The evaporated gas of liquid helium escapes from the taliostat without recondensing.

Refrigerators reduce this evaporation rate as much as possible and can be used for long periods of time.
: Introduced to make it possible. 23 is a baffle plate placed between the shield body 6 at liquid nitrogen temperature and the container 3 at liquid helium temperature, a part of which is connected to the expander 8 of the refrigerator.
-ys of the receptor 24 containing the. Also, shi? A liquid nitrogen container 25 is installed connected to the enclosure 6, and liquid nitrogen 26 is supplied through a supply pipe 27. Container 25
and receiver 26 are connected by tubes 29 and 30 and condenser 31. The receiver 24 and the cylinder 9 are in contact via a number of strip-shaped leaf springs 32.

The evaporated gas of the liquid helium 2 passes through the discharge pipe 33, cools the shield plate 23, and then exits the receiver 24 from the low-temperature side to the high-temperature side while thermally contacting it, and finally becomes gas at room temperature. Go outside of Taliostat.

The expander 8 has two cold generation stages, and the cold heat generated in each stage is transferred from the cylinder 9 to the receptor 24 via the leaf spring 32.
connected to the cold absorption section of The vaporized liquid nitrogen 26 gas passes through a pipe 29, is re-liquefied in a condenser 31 corresponding to the first stage (liquid nitrogen temperature level), and returns to the container 25 via a pipe 30. At this time, if necessary, valve 28'f! : Close container 2
5 can also be sealed. The temperature of the second stage is approximately 20°C, and cold heat is transferred to the baffle plate 23 by heat conduction. In case of failure or repair of the expander 8, open the valve 28 fully and open the expander 8?
It is only necessary to withdraw it from the il-receptor 24.

FIG. 3 shows an example in which a Claude cycle is used as the refrigerator, and only the vicinity of the refrigerator in FIG. 1 is shown. This refrigerator also has two cold generation stages, the upper stage being at the liquid nitrogen temperature level (100-70K) and the lower stage being at the liquid helium temperature level (5-3K). The helium gas at normal temperature, which has become high pressure in the compressor, passes through the entire supply pipe 40, enters the cold box 41, passes through the first heat exchanger 42, and part of it is brought to an intermediate pressure in the first expander 43. It expands, performs work on the outside, lowers its temperature, and cools the first cooling stage 45 provided in the middle of the side wall 44 of the cold box 41.

After that, heat is exchanged from the middle of the second heat exchanger 46, and then the second expander 47 expands to the pressure of the return gas (almost atmospheric pressure), and the temperature drops and enters the return line. . A portion of the high pressure gas is transferred to the second heat exchanger 46. Third heat exchanger 48
It is partially liquefied after the expansion valve 5o via the fourth heat exchanger 49 and cools the second cooling stage 51. The return gas is the 4th.
Third. Second. Each first heat exchanger 49°48.46.42
The gas becomes a low-pressure gas at room temperature and returns to the compressor via the recovery pipe 52. The first cooling stage 45 and the second cooling stage 51id are in thermal contact with a part of the gas loop 53, 54 by brazing or the like, while a large number of leaf springs 55 with good thermal conductivity Thermal contact is maintained with .56. Side wall 4
4 are fitted into a receiver 24 which is airtightly attached to the vacuum vessel 4 of the Taliostat, and the plates contact each other at the leaf springs 55 and 56 to transfer heat. A condenser 31 is attached by brazing or the like to the portion of the receiver 24 corresponding to the first cooling stage, and is connected to the liquid nitrogen container 25 by tubes 29 and 30.

Similarly, a condenser 57 is attached to the part of the receiver 24 corresponding to the second cooling stage and is connected by tubes 58 and 59 to the container 3 of liquid helium. With such a configuration, the liquid helium container 3 and the liquid nitrogen container 25 can be completely sealed.

FIG. 4 shows another embodiment of the thermal contact portion using a leaf spring, in which a step 60 with a gentle slope is provided on the receptor 24 which is to be in contact with the leaf spring 55 attached to the side wall 44. . In this way, when inserting the cold box, the contact between the leaf spring 55 and the receptor 24 can be weakened or non-sliding until the predetermined position is reached, making insertion easy and causing less wear. In addition, in order to reduce the thermal resistance of the contact, both surfaces of the contact may be coated with a metal such as silver, rhodium, or indium.

FIG. 5 shows another embodiment of the contact portion, in which the side wall 44
A cooling stage 61 made of copper to which a part 53 of a cooling loop is attached is entirely provided at the bottom of the cooling stage 61, and a leaf spring 62 is thermally connected to the bottom surface of the cooling stage 61 made of copper. On the other hand, a copper condensing vessel 63 is provided at a portion of the receiver 24 facing the cooling stage 61 and is connected to a liquid nitrogen or liquid helium vessel through a pipe 64. In such a configuration, the thermal contact by the plate spring 62 is performed by compressive force, so that the contact pressure can be increased and the thermal resistance can be completely eliminated.
4 can be made smaller.

6 and 7 show other embodiments of leaf springs 55 and 58. That is, one strip-shaped leaf spring is installed in the cooling stage 45.
Instead of attaching the leaf springs one by one, an integrated leaf spring 6° or 61 is used, which is made by cutting a cylindrical flat plate and providing a protrusion to provide a spring action. In this way, the installation of the leaf spring can be done simply by tightening bolts at several points on the circumference or by gluing the fixed side by soldering or the like, which simplifies the work. In addition, a shape memory alloy is used for this type of leaf spring so that it does not come into contact with the receptor 24 at room temperature, but when the temperature of the cooling stage 45 or the side wall 44 drops, the leaf spring contacts the receptor 24 and transfers heat. It's okay.

〔Effect of the invention〕

As described above, according to the present invention, the refrigerating machine can be easily attached and detached in the taliostat without causing any thermal disturbance to the object to be cooled, which increases the reliability of the device. Contributes to sexual improvement.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing a conventional embodiment, FIG. 2 is a schematic cross-sectional view showing one embodiment of the present invention, and FIG. 3 is a schematic cross-sectional view showing another embodiment of the present invention. FIG. 4 is a sectional view showing a part of another embodiment of the present invention, and FIG. 5 is an analytical view showing a part of another practical example of the invention. 6 and 7 are cross-sectional views showing a portion of another embodiment of the present invention. l...Superconducting coal, 2...Liquid helium, 26
...liquid nitrogen, 6...shield body, 23...shield plate, 8...expander, 9...cylinder, 24...
・Receptor, 31... Condenser, 3.2, 55.58...
・Leaf spring. Agent Patent Attorney Akio Takahashi No. 11E2] 20 Z Z Z Figure ¥13 12] ¥'> 4- [2] Figure 5

Claims (1)

[Claims] 1. An object to be cooled that operates at a cryogenic temperature, a container for storing the object and a first coolant, a container for storing a second coolant that at least partially surrounds the object, and a barrier body connected to the object; A vacuum container enclosing these, a refrigerator with a built-in expander, at least two cylindrical bodies of different diameters with the cold generating part of the refrigerator exposed on the circumference and enclosing the refrigerator, and the cylindrical body a receiver fitted into the vacuum container and airtightly attached to the vacuum container; a condenser in communication with the first or second coolant container in a part of the receiver; A taliostat characterized in that a thermal contact member made of a leaf spring or the like is interposed between the condenser portion and the cylindrical cold generation portion.