JPS61213453A - Cryogenic refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a cryogenic refrigeration system, particularly a compact, highly efficient,
The present invention relates to a cryogenic refrigeration system suitable for achieving high reliability.

[Background of the invention]

Conventionally, low-temperature refrigeration equipment has been described in "Handbook of Cryogenic Engineering," Uchida Tsuruga Shinsha, 1st edition, September 15, 1980, p. 138.
As described in ~141, a helium liquefaction device is constructed by incorporating a Joule-Thomson expansion system (hereinafter referred to as JT system) into a Gifford-McMahon refrigerator.

However, this equipment requires a large number of heat exchangers and a compressor for the JT system in addition to the Gifford-McMahon refrigerator, resulting in large equipment, low efficiency, and lack of reliability. was there.

[Purpose of the invention]

The present invention is a ninth step in solving the problems of the prior art as described above, and reduces the driving force of the magnetic refrigerator.
The objective is to provide a cryogenic refrigeration system that is compact, highly efficient, and highly reliable.

[Summary of the invention]

The configuration of the cryogenic refrigeration apparatus according to the present invention includes:
An extremely low-temperature cooling system that contains liquid helium and helium gas in which the object to be cooled is immersed and cools the object to an extremely low temperature using a gas refrigerator and a magnetic refrigerator that is connected to the cooling stage of the gas refrigerator by a heat transfer member. In the low-temperature refrigeration apparatus, the magnetic refrigerator is disposed in the helium gas so as to be movable in the horizontal direction, with a high-temperature side heat dissipation section connected to the heat transfer body and a gap maintained between the high-temperature side heat dissipation section and the high-temperature side heat dissipation section. A work object consisting of a heat insulating member and a plurality of magnetic bodies, and a super-dynamic coil located in a direction perpendicular to the direction of movement of the work object and to apply a magnetic field to the magnetic bodies of the work object. The magnetic body alternately passes through a high magnetic field region and a low magnetic field region as the work object moves backward.

As an additional note, the present invention performs freezing from room temperature (approximately 300 K) to approximately 10 Kt using a small gas refrigerator such as a Gifford-McMahon refrigerator or a Stirling refrigerator, and from a temperature of 10 to a liquid helium temperature (approximately 4K), the refrigeration cycle consists of a magnetic refrigerator.

Thermal connection between the lowest temperature stage of a small gas refrigerator and the magnetic refrigerator is achieved by heat conduction of helium gas in a minute gap, and heat transfer at the liquid helium temperature is achieved by condensation heat transfer of helium gas. It consists of the following:

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5.

First, FIG. 1 is a sectional view of a cryogenic refrigeration apparatus according to an embodiment of the present invention.

In FIG. 1, numeral 1 indicates an object to be cooled, such as a superconducting coil or a superconducting electronic device, which is immersed in liquid helium z. This liquid helium 2 is stored in a container 3, and this container 3 and a vacuum container 4 at room temperature (approximately 300 K) constitute a heat insulating container. There is a vacuum between the vacuum container 4 and the container 3, and an intermediate temperature radiation shield plate 5 is provided. 6a is a vacuum layer between the container 3 and the intermediate temperature radiation shield plate 5;
6b is a vacuum layer between the vacuum container 4 and the intermediate gA degree radiation shield plate 5.

7a is a heat insulation load support provided between the container 3 and the intermediate temperature radiation shield plate 5, and 7b is a heat insulation load support provided between the intermediate temperature radiation shield plate 5 and the vacuum container 4. The load of the container 3 is supported by the vacuum container 4 by these adiabatic load supports 7a and 7b.

8 is a small gas refrigerator such as a Gifford-McMahon refrigerator or a Stirling refrigerator, and 9 is a magnetic refrigerator. are arranged horizontally.

Reference numerals 11a and llb indicate installation ports for high-pressure and low-pressure gas pipes connected to a compressor (not shown) of the gas refrigerator 8.

The intermediate temperature stage 12 of the gas refrigerator 8 is used to cool the intermediate temperature radiation shield plate 5 . The lowest temperature stage of the cooling stage of the gas refrigerator 8 (for example, IOK
A heat transfer body 15 is connected between the stage) 13 and the high temperature side heat radiation part 14 of the magnetic refrigerator 9. This heat transfer body 15 is made of a highly thermally conductive member such as copper or aluminum, and is a ninth element that radiates heat to the high temperature side heat radiating section 14 of the magnetic refrigerator 9 and transfers specific heat. The lowest temperature stage 13 of the magnetic refrigerator 9, the high temperature side heat radiation part 14, and the heat transfer body 15 are surrounded by a heat insulating member 16 and insulated from the helium gas 10.

Reference numeral 17 denotes a work object constituting the magnetic refrigerator 9, which is a piston related to a reciprocating body.

The piston 17 is formed of a heat insulating member 19 and at least two magnetic bodies 18a and 18b.

That is, a magnetic material 18a such as gadolinium gallium garnet (Gd5GaB of t ), which is a working material for magnetic refrigeration, is placed at a relatively distal end of the piston 17 .

18b are provided with a gap between them, and the other heat insulating member 19 is made of a material such as glass ceramics that has low thermal conductivity, low heat capacity, and has approximately the same thermal shrinkage rate as the magnetic materials 18a and 18b. There is.

This piston 17 is equipped with means for converting rotational motion into linear motion, such as a ball screw, and via a ratio converter 20,
Reciprocating motion is performed by rotating the motor 21 in forward and reverse directions. 22a
, 22b is a bearing, and 23 is a seal.

24 is a magnetic body 18a of the piston 17;

This superconducting coil 24 is a compact superconducting coil that applies a high magnetic field to the piston 18b, and is housed in the center of the renoid so as to surround the piston 17.
6t- is disposed in the helium gas 10 in a direction perpendicular to the direction of movement of the piston 17, that is, in a vertical direction.

Next, the operation of the nine cryogenic refrigeration apparatus constructed in this way will be explained.

The gas refrigerator 8 is constantly operated, and the high temperature side heat radiation part 14 of the magnetic refrigerator 9 is maintained at a temperature of approximately IOK by the heat transfer body 15 connected to the lowest temperature stage 13.

On the other hand, the superconducting coil 24 is operated in persistent current mode, and a high magnetic field is always present at the center of the solenoid.

Now, when the piston 17 is reciprocating and is in the position shown in FIG. 1 (that is, the piston 17 is at the leftmost position), the magnetic material 1811, which is the working substance, is in the high magnetic field region of the superconducting coil 24, and the magnetic material 18b is outside the magnetic field. Magnetic material 1
8a is magnetized and generates heat, and radiates heat to the high temperature side heat radiating section 14 by thermal conduction of the helium gas 10 in a small gap (approximately 5 to 50 μm) between the high temperature side heat radiating section 14 and the magnetic body 18a.

Next, when the piston 17 moves to the rightmost end (the magnetic material tea comes out of the high magnetic field region of the superelectric coil 24 and the helium gas 1
The other magnetic body 18b moves to the outside of the magnetic field at zero, that is, to the low magnetic field region, and the other magnetic body 18b enters the high magnetic field region. In the low magnetic field region, the magnetic material tea is adiabatically demagnetized by 11%, so its temperature decreases, and when the temperature becomes lower than the helium gas 10, the helium gas 1(l) is demagnetized on the direct surface of the magnetic material tea due to condensation heat transfer. Condensate and reliquefy.

The refrigeration cycle at this time is a reverse Carnot cycle.

Liquid helium 2 is exposed to heat intrusion from room temperature parts and objects to be cooled 1.
Heat constantly enters and evaporates due to the heat of
This evaporated content is to be reliquefied as described above.

According to this embodiment, due to the reciprocating movement of the piston 17, which is the work object, the magnetic materials 18a and 18b, which are the work materials, alternately pass through a high magnetic field region and a low magnetic field region and are magnetized and demagnetized, so that they are shifted by 180 degrees. This results in nine refrigeration cycles.

Also, in terms of the driving force for the reciprocating movement of the piston 17, since electromagnetic forces in opposite directions act on the magnetic bodies 18a and 18b during reciprocating movement, they cancel each other out and can perform reciprocating movement with a small driving force.

As described above, according to this embodiment, heat exchange or insulation between the high temperature side and the low temperature side in the magnetic refrigerator section is sufficiently performed.
In particular, since the driving force can be significantly reduced, the device can be made smaller and more efficient, and a highly reliable cryogenic refrigeration device can be provided.

Next, another embodiment of the present invention will be described with reference to FIGS. 2 and 3.

FIG. 2 shows a cryogenic freezing fi according to another embodiment of the present invention,
FIG. 3 is a perspective view showing the main parts of IT, taken along line A-A' in FIG.
FIG. In the figure, parts with the same reference numerals as those in FIG. 1 are the same parts as in the embodiment of FIG. 1, and therefore their explanation will be omitted.

In the embodiment shown in FIG. 2, the working object of the magnetic refrigerator 9A is a cylindrical rotating body placed in helium gas 10 with the axial direction of the rotating body aligned with the direction of gravity. be. In other words, the work object makes a rotational movement in the horizontal direction.

That is, as shown in FIGS. 2 and 3, a plurality of magnetic bodies 25, which are working materials, are provided on the outer periphery of a cylindrical body made of a heat insulating member 26, alternating with the heat insulating member 26, and
It consists of 28 is a member that insulates the upper surface of the magnetic body 25.

The rotating body 27 has a rotating shaft 34 supported by bearings 32 and 33.
It is directly connected to and rotated by a motor 21 located in the room temperature section.

Reference numeral 29 denotes a high temperature side heat dissipation section for the nine people of the single-gas refrigerator. The side heat dissipation part 29 and the magnetic body 25 are thermally connected via the helium gas 10 in a minute gap. The high temperature side heat radiation section 29 is connected to the lowest temperature stage 13 of the gas refrigerator 8 by the heat transfer body 15, and the high temperature side heat radiation section 29 is connected to the lowest temperature stage 13 of the gas refrigerator 8 by about 7
The temperature is maintained between 20 K and 20 K.

30 is a superelectric coil that forms a high magnetic field, and 31 is a superelectric coil that forms a low magnetic field, which are disposed to face each other with the rotating body 27 in between in a direction perpendicular to the rotating direction of the rotating body 270. .

A superelectric coil 30 is disposed on the high temperature side heat dissipation section 29 side, and a high magnetic field is applied to the magnetic body 25 in this area.
The region on the opposite side is set to almost zero magnetic field by the superelectric coil 31.

With such a configuration, when the rotating body 27 rotates, the magnetic bodies 25 provided on the outer periphery of the rotating body 27 periodically pass through high magnetic field and low magnetic field regions with each rotation. As a result, it is magnetized and generates heat in the high magnetic field region by the super electric coil 30, so the heat is exhausted to the high temperature side heat dissipation part 29, and then it is demagnetized in the low magnetic field region by the super electric coil 31,
The temperature of the magnetic body 25 decreases, causing the helium gas 10 to condense and liquefy.

According to this embodiment, the same effects as those described in the embodiment shown in FIG. 1 can be expected.

Next, still another embodiment of the present invention will be described with reference to FIGS. 4 and 5.

Here, FIG. 4 is a perspective view showing the main parts of a cryogenic refrigeration apparatus according to still another embodiment of the present invention, and FIG. 5 is an enlarged perspective view of the part provided with the magnetic material in FIG. 4. . In the figure, the parts in FIG. 1 with the same reference numerals as those in FIG. 2 are the same parts as in the embodiment in FIG. 2, and therefore the explanation thereof will be omitted.

In the embodiment shown in FIG. 4, the working object of the magnetic refrigerator 9B is a disk-shaped rotating body disposed in helium gas 10 with the axial direction of the rotating body aligned with the direction of gravity. It is.

In other words, the work object makes a rotational movement in the horizontal direction.

That is, as shown in FIG. 4, a heat insulating disc 36 made of a heat insulating member has a plurality of magnetic substances 35, which are working substances, fixed on its circumference in such a manner that they penetrate through the heat insulating disc 36 and are embedded. This constitutes a rotating body.

The heat insulating disc 36 related to the rotating body is directly connected to a rotating shaft 34 supported by bearings 32 and 33, and is rotated by the motor 21.

37 (synonyms of 37a and 37b) is a high temperature side heat sink related to the high temperature side heat sink of the magnetic refrigerator 9B.

The lowest temperature stage 13 of the gas refrigerator 8 and the magnetic refrigerator 9B
The high temperature side heat sinks 37a and 37b are thermally connected by a heat transfer body 15.

The high temperature side heat sinks 37a and 37b are arranged above the heat insulating disk 36 so that the gap between them and the upper surface of the magnetic body 35 is 10 to 100 μm. There is helium gas 10 in this gap, and the high temperature side heat sink 3 other than facing this gap
7 is insulated.

Heat insulating plates 38a and 38b are disposed on the surface of the heat insulating disk 36 opposite to the high temperature side heat sink 37 to reduce heat exchange with the helium gas 10 at the bottom.

Reference numerals 39a and 39b are V-strunk superelectric coils, which are disposed facing each other with the heat insulating disc 36 in between in a direction orthogonal to the rotational direction of the heat insulating disc 36. That is, a high magnetic field and a low magnetic field distribution are layered on the circumference of the magnetic body 35 by the superelectric coils 39a and 39b.

When the heat insulating disk 36 is rotated by the motor 21, the magnetic body 35 undergoes nine magnetic field changes according to the magnetic field distribution and rotation speed, and is magnetized in the high magnetic field region of the superelectric coil 39a and generates heat, dissipating heat on the high temperature side. Heat is radiated to the end 37a via the helium gas 10 in the gap, and when it moves to the low magnetic field region of the superelectric coil 39b, it is demagnetized, the temperature of the magnetic body 35 decreases, and the helium gas 1
0 is condensed and liquefied.

The outer surface of the heat insulating disc 36 other than the magnetic material 35 is coated with a synthetic resin having a low coefficient of friction, so that the heat insulating disc 36 is protected during rotation.
6 is a high temperature side heat sink 37a, 37b.

Alternatively, it is designed so that it can rotate even if it comes into contact with the heat insulating plates 38a and 38b.

40a and 40b are superconducting carp #39a and 39
The superconducting coils 39a and 39b can be cooled to approximately 5K using liquid helium 2.

As shown in FIG. 5, each of the plurality of magnetic bodies 35 provided in the heat insulating disk 36 has a plurality of pores 4 penetrating in the direction of gravity.
1 (diameter 0.2 to 2 holes) is perforated.

This pore 41 increases the condensation heat transfer area when the magnetic body 35 is demagnetized and the temperature decreases to condense and liquefy the helium gas 10, and also allows the condensed liquid to drop into the liquid helium 2 below. This is the ninth thing that makes it easier. As a result, the helium condensed and liquefied on the upper surface of the magnetic body 35 is condensed and liquefied on the inner surface of the pore 41, and the helium is condensed and liquefied on the upper surface of the magnetic body 35.
It flows to the lower surface of 5, condenses and liquefies on the lower surface, becomes together with 9 helium, and falls into the liquid helium 2.

Finally, liquid drainage grooves 42 and 43 are provided on the outer periphery of the upper and lower surfaces of each of the plurality of magnetic bodies 35.

This drainer @42.43 has a depth of approximately 0.5 to 2 at)
These grooves have a width of about 0.5 to 2 fi and prevent an oil film from spreading on the upper and lower surfaces of the magnetic body 35, and these liquid drainage grooves 42 and 43 are vertically communicated through pores 44. .

According to the embodiment shown in Fig. 4.5, the same effects as the first cause and the embodiments shown in Fig. 2 are expected, and helium gas
It has the unique effect of being able to efficiently drip the condensed liquid into the liquid helium 2 portion, thereby increasing the efficiency of the refrigeration cycle.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to significantly reduce the driving force of a magnetic refrigerator, and to provide a cryogenic refrigeration system that is compact, highly efficient, and highly reliable.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a cryogenic refrigeration apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view showing main parts of a cryogenic refrigeration apparatus according to another embodiment of the present invention, and FIG.・A-A in Figure 2
The fourth factor is a perspective view showing the main parts of a cryogenic refrigeration system according to yet another embodiment of the present invention, and FIG. It is a diagram. l...Object to be cooled, 2...Liquid helium, 3...Container, 4...Vacuum container, 8...Gas refrigerator, 9,9A
, 9B...Magnetic refrigerator, 10...Helium gas, 1
3...Lowest temperature stage, 14...High temperature side heat dissipation section,
15... Heat transfer body, 17... Piston, 18a, 1
8b, 25° 35...Magnetic material, 19.26...Insulating member, 21...Mo/, 24, 30, 31, 391,
39b--superconducting coil, 27--rotating body, 29-
...High temperature side heat dissipation part, 36...Insulating disk, 37a, 3'
lb...High temperature side heat sink, 41.44...Pore, 42
．． 43...Liquid cutting groove. Figure 1 Figure 2 Figure γ Figure 3

Claims (1)

[Claims] 1. A heat-insulating container containing liquid helium and helium gas in which an object to be cooled is immersed is connected to a gas refrigerator and a cooling stage of the gas refrigerator by a heat transfer member. In a cryogenic refrigerator that cools to a very low temperature with a magnetic refrigerator, the magnetic refrigerator has a high-temperature side heat radiating part connected to the heat transfer body, and a gap between the high-temperature side heat radiating part and the helium gas. A work object is arranged to be movable in the horizontal direction and is composed of a heat insulating member and a plurality of magnetic bodies, and a magnetic body of the work object is located in a direction perpendicular to the direction of movement of the work object. and a superelectric coil to which a magnetic field is applied, and the magnetic body is configured to alternately pass through a high magnetic field region and a low magnetic field region as the work object repeatedly moves. cryogenic refrigeration equipment. 2. In the item set forth in claim 1, the working object of the magnetic refrigerator is a reciprocating body formed by at least two magnetic bodies provided at intervals in a heat insulating member, horizontally in helium gas. The superelectric coil is arranged vertically in helium gas so as to surround the reciprocating body, and as the reciprocating body moves back and forth, the two magnetic coils A cryogenic refrigeration apparatus, wherein when each of the magnetic bodies is in a high magnetic field region of the superconducting coil, the other magnetic body is outside the magnetic field of the superconducting coil. 3. In the item described in claim 1, the working object of the magnetic refrigerator is a rotating body in which a plurality of magnetic bodies are provided on the outer periphery of a cylindrical body of a heat insulating member, and the rotating body is immersed in helium gas. The superelectric coil is arranged so that the axial direction and gravity direction of the rotating body coincide with each other, and the superelectric coil consists of a superconducting coil that forms a high magnetic field and a superconducting coil that forms a low magnetic field in the direction orthogonal to the rotation direction of the rotating body. are placed facing each other,
The cryogenic refrigeration apparatus is configured such that the magnetic body alternately passes through a high magnetic field region and a low magnetic field region as the rotating body rotates. 4. In the item described in claim 1, the working object of the magnetic refrigerator is a rotating body in which a plurality of magnetic bodies are provided on a disc of a heat insulating member, and the shaft of the rotating body is immersed in helium gas. The superelectric coil is arranged so that the direction of gravity matches the direction of gravity, and the superelectric coil is divided into a superelectric coil that forms a high magnetic field and a superelectric coil that forms a low magnetic field in a direction perpendicular to the rotation direction of the rotating body. 2. A cryogenic refrigeration system, wherein said magnetic body alternately passes through a high magnetic field region and a low magnetic field region as said rotating body rotates. 5. A cryogenic refrigeration device according to claim 4, wherein each of the plurality of magnetic bodies provided on the disk is provided with a pore that penetrates in the direction of gravity. 6. A cryogenic freezing apparatus according to claim 4, wherein liquid drain grooves are provided on the upper and lower surfaces of each of the plurality of magnetic bodies provided on the disk.