JPH0412378B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to a low-temperature device for generating low temperature, which includes two systems of refrigerators, one in a high-temperature region and one in a low-temperature region.

The present invention can be used in a refrigeration device that generates refrigeration at a temperature of about 5K or less, and this refrigeration device is installed in a cryostat that houses a superconducting magnet cooled with liquid helium, and the cryostat is penetrated into the cryostat. It is used in cooling devices that liquefy helium gas that evaporates due to heat and maintains a constant amount of liquid helium in a cryostat.

(Prior art and its problems) As a prior art related to the present invention, US Pat.
A cryogenic device is already known as shown in document No. 4335579. This one, as shown in Figure 5,
A crankshaft 102 rotated by a power source 101, a piston 103 slid by the crankshaft 102, and expansion parts 104, 10.
5. A high-temperature region refrigerator having low-temperature parts 106 and 107, a compression part, a heat radiation part, and a heat exchanger (not shown), and a crankshaft 109 rotated by a power source 108, by the crankshaft 109. A refrigerator in a low-temperature region includes sliding pistons 110 and 111, a compression section 112, an expansion section 113, a heat radiation section 114, and a regenerator 115. The heat dissipation section 114 is thermally coupled to the low temperature section 107,
The heat of compression of the working gas generated in the compression section 112 of the refrigerator in the low temperature region is absorbed by the low temperature section 107. Further, the compression cylinder 116 and expansion cylinder 117 of the refrigerator in the low temperature region are connected to the low temperature section 10.
6 through a pre-cooling plate 118, thereby reducing heat flowing from the normal temperature section into the compression section 112 and the expansion section 113.

Piston rings 119, 120, 121, 12
2 is a seal that prevents communication of working gas.

In this conventional cryogenic apparatus, the compression cylinder 116
For example, even though the expansion cylinder 117 is cooled in the low temperature section 106 of the refrigerator in the high temperature region via the precooling plate 118, the temperature of the compression section 112 is low.
When the temperature of the expansion section 113 is at the 10K level and the temperature of the expansion section 113 is at the 4K level, the temperature of the low temperature section 106 is at the 20K level.
13, there is a heat intrusion of about 0.5 watts. For this reason, the efficiency of the entire device deteriorates, and in order to obtain the same refrigeration output in the expansion section 113 of the refrigerator in the low temperature region, a large input is required for the entire low temperature device, which increases the size and weight of the device. This is because a compression section 112 and an expansion section 113 of a refrigerator in a low temperature region are arranged on a piston 11 that is slidably disposed within cylinders 116 and 117.
1,110, the working gas enters the gap formed between the cylinders of the piston to allow the piston to slide, and the heat carried by this working gas from the normal temperature part and transmitted through the piston. This is because the heat cannot be reduced sufficiently.

Furthermore, in the conventional refrigerator, the piston 103,
Resin such as Bakelite is used as the material for 110 and 111 in order to suppress heat conduction. Therefore, the gas generated from the resin, the crankshaft 10
Lubricating oil used in bearings 2,109 or piston rings 119, 120, 121, 122
Impurities such as abrasion powder from the compressor were mixed into the working gas, and the performance of the refrigerator was degraded due to surface contamination of the heat radiating section 114 and the regenerator 115.

(Technical Problems of the Present Invention) The present invention aims to eliminate the above-mentioned problems of the conventional technology by reducing heat intrusion from the room temperature region to improve refrigeration efficiency, and by preventing impurities from being mixed into the working gas. , as a technical problem to be solved.

(Technical means of the present invention and its effects) The means taken to achieve the above technical problem is that one or more compression sections and one or more expansion sections constituting a refrigerator in a high temperature region are all connected to a turbine. 1, which constitutes a refrigerator in a low temperature region.
One or more compression parts and one or more expansion parts are constructed of metal bellows.

Since the basic structure of the present invention is as described above, the working gas in the compression section and the expansion section that constitute the refrigerator in the low temperature region is retained therein by the bellows and is isolated from the normal temperature section. Heat intrusion from the normal temperature section due to the working gas is reduced.

Furthermore, since all surfaces in contact with the working gas in a refrigerator operating in a low-temperature region are made of metal, very little gas is generated from the surfaces, and impurities such as lubricating oil and abrasion powder are never mixed into the working gas. Therefore, performance deterioration of the refrigerator due to surface contamination of the heat radiating section and the regenerator does not occur.

Even in refrigerators operating in high-temperature regions, gas bearings can be used as turbine bearings, so impurities are not mixed into the working gas, and the performance of the refrigerator does not deteriorate.

(Example) An example of the present invention will be described below based on FIG. In FIG. 1, the cryogenic device according to the present invention is
It consists of a high-temperature region refrigerator and a low-temperature region refrigerator. A high-temperature region refrigerator includes a compression turbine 1, a heat radiation section 2, a heat exchanger 3, and an expansion turbine 4, which are linked to a power source such as a motor. A refrigerator in a low-temperature region has rod-shaped connecting members 5 and 6 that are connected to a crankshaft or the like that is connected to a power source such as a motor, and the lower ends of these connecting members 5 and 6 are
A compression bellows 7 and an expansion bellows 8 are fixed. The other end of the bellows 7, 8 is a support cylinder 9, 10.
are fixed respectively. The connecting member 5,
6. The support cylinders 9 and 10 are formed of small thermally conductive members.

The compression bellows 7 and the expansion bellows 8 are communicated through a heat radiation section 11, a regenerator 12, and a condenser 13. The heat radiation section 11 is provided with a flow path 14 through which low-temperature working gas of the refrigerator in the high-temperature region can enter and exit. The upper ends of the connecting members 5 and 6 are respectively connected to a crankshaft or the like and are connected to a connecting block 1 that reciprocates.
5, 16 via bellows 17, 18,
One end of these bellows 17, 18 is connected to the vacuum container 1.
It is installed on 9.

The volumes of the compression bellows 7 and the expansion space 8 of the low-temperature region refrigerator, which are composed of the compression bellows 7, the heat radiation part 11, the regenerator 12, the condenser 13, and the expansion space 8, are linked to the power source, crankshaft, etc. By driving the expansion bellows 8 to advance approximately 90 degrees with respect to the compression bellows 7, the expansion bellows 8 generates refrigeration and compresses. The bellows 7 generates compression heat. The compression heat and the heat that enters the compression section from room temperature are absorbed by the low temperature working gas of the refrigerator in the high temperature region in the heat radiation section 11, and the above heat becomes a refrigeration load of the refrigerator in the high temperature region. By constructing the expansion part with a bellows 8, one end of which is interlocked with the heat insulating connecting member 6, and the other end fixed with the heat insulating support cylinder 10, it is possible to fit into the gap between the piston and the cylinder in a conventional piston/cylinder type refrigerator. The heat carried by the existing working gas to the expansion space can be eliminated, and the conductive heat transmitted through the piston and cylinder can also be reduced, and the expansion work generated in the expansion bellows 8 can be effectively extracted to the outside as refrigeration output.

Similarly, by configuring the compression part with a bellows 7, one end of which is interlocked with the heat insulating connecting member 6, and the other end fixed with the heat insulating support cylinder 9, it is possible to reduce the heat that enters the compression bellows, thereby reducing the heat in the high temperature region. The refrigeration load on the refrigerator can be reduced.

The volume change of bellows 7, 8 is
This is done by reciprocating the heat insulating connecting members 5 and 6 fixed to one end of the . The connecting members 5 and 6 are fixed to one end of the bellows 17 and 18 in the normal temperature section, which make the vacuum container 19 vacuum-tight with respect to the atmosphere. Connecting rods 15 and 16 that transmit the reciprocating motion of the drive mechanism of the normal temperature section are further fixed to this end face, and the reciprocating motion of the connecting rods 15 and 16 is directly transmitted to the heat insulating connecting member 5, via bellows 17 and 18. 6.

On the other hand, in a high-temperature region refrigerator composed of a compression turbine 1, a radiator 2, a heat exchanger 3, an expansion turbine 4, and a flow path 14, the compression turbine 1 is linked to a power source such as a motor. ,
The bearing is a gas bearing that uses working gas. In the compression turbine 1, the compressed working gas generates heat. This compression heat is removed by the heat radiator 2. The working gas exiting the radiator 2 exchanges heat with the working gas exiting from the flow path 14 in the heat exchanger 3, is cooled, and flows into the expansion turbine 4. expansion turbine 4
is linked to a power absorption device such as a generator,
Expansion work is dissipated by high frequency resistance outside the vacuum vessel 19. The working gas generates refrigeration by rotating the expansion turbine 4. The working gas that has exited the expansion turbine 4 flows into the flow path 14 and cools the working gas flowing through the radiator 11 in the refrigerator in the low temperature region. The gas exiting the flow path 14 flows into the heat exchanger 3, exchanges heat with the working gas exiting the radiator 2, is heated, and returns to the compression turbine 1.

As described above, in the present invention, the metal bellows 7 and 8 are used for the refrigerator in the low temperature region, and the turbines 1 and 4 using gas bearings are used in the refrigerator in the high temperature region. There is no possibility that impurities such as outgas from the resin, lubricating oil from the bearings, and abrasion powder from the piston rings will mix into the working gas, contaminate the surfaces of the heat dissipation section and regenerator, and cause deterioration in the performance of the refrigerator. do not have.

A first modification of the present invention will be described below with reference to FIG. In FIG. 2, the refrigerator in the low temperature region is exactly the same as the embodiment shown in FIG. 1, but the refrigerator in the high temperature region is different. Expansion turbine 21, 4
is a series two-stage expansion method, and the heat exchangers 20 and 22
It also has a two-tier configuration. Since the expansion turbine 21 performs expansion work on the working gas between the heat exchangers 20 and 22, the inefficiency of the heat exchangers 20 and 22 is compensated for, so the performance of the refrigerator in the high temperature region is improved. This is improved compared to the embodiment shown in FIG.

Next, a second modification of the present invention will be explained with reference to FIG. In FIG. 3, the refrigerator in the low temperature region is exactly the same as the embodiment shown in FIG.
The refrigerators in the high temperature range are different. expansion turbine 3
1 and 4 are parallel two-stage expansion type, and heat exchanger 3
0, 32, and 33 have a three-stage configuration. A part of the high pressure working gas leaving the heat exchanger 30 enters the expansion turbine 31 and performs expansion work in the expansion turbine 31.
It joins with the low pressure working gas exiting the heat exchanger 33. Since the inefficiency of the heat exchangers 30, 32, and 33 is compensated for by the expansion work produced by the expansion turbine 31, the performance of the refrigerator in the high temperature region is improved compared to the embodiment shown in FIG.

Furthermore, a third modification of the present invention will be explained with reference to FIG. In FIG. 4, the refrigerator in the high temperature region is exactly the same as the embodiment shown in FIG.
The refrigerators in the low temperature range are different. The regenerator 2 in FIG. 1 is divided into two regenerators 40 and 41 in FIG.
It communicates with An expansion bellows 42 is fixed to the lower end of a rod-shaped connecting member 43 that is interlocked with a crankshaft or the like that is connected to a power source such as a motor. The other end of the expansion bellows 42 is fixed to a support cylinder 44 . The solution of the expansion bellows 42 is changed by reciprocating a heat insulating connecting member 43 fixed to one end of the expansion bellows 42. This connecting member 43 makes the vacuum container 19 vacuum-tight with respect to the atmosphere: it is fixed to one end of a bellows 45 in the normal temperature section. A connecting rod 46 that transmits the reciprocating motion of the drive mechanism of the normal temperature section is further fixed to this end surface.
The reciprocating motion of the connecting rod 46 is directly transmitted to the heat insulating connecting member 43 via the bellows 45. The phase of the reciprocating movement of the connecting rod 46 is matched to that of the connecting rod 16.

In this way, in the modification shown in FIG. 4, the regenerator 40,
41, the working gas performs expansion work by the expansion bellows 42, so it is possible to compensate for the inefficiency of the regenerators 40 and 41, and compared to the embodiment shown in FIG. Improves machine performance.

In addition to the above-mentioned modifications, in a high-temperature region refrigerator, a plurality of compression turbines 1 and radiators 2 may be provided to perform multistage compression. Further, in a refrigerator for a low temperature region, a plurality of compression bellows 7 and a plurality of radiators 11 can be provided to perform multistage compression.

(Effects) In order to eliminate the drawbacks of the prior art, the low temperature apparatus shown in FIG. 6 can also be used. The low-temperature device shown in FIG.
It is composed of a valve 66, a condenser 67, and a vacuum vessel 68. The compression turbine 60 is linked to a power source such as a motor, and the bearing is a gas bearing that uses working gas. The working gas compressed in the compression turbine 60 generates heat. This compression heat is removed by a heat radiator 61. The working gas leaving the radiator 61 flows into the heat exchanger 62 and is cooled. A portion of the working gas exiting the heat exchanger 62 flows into the expansion turbine 65, expands to generate refrigeration, and merges with the working gas exiting the heat exchanger 64. Most of the working gas leaving the heat exchanger 62 flows into the heat exchanger 63 and is further cooled, and flows into the heat exchanger 64 where it is further cooled. The working gas leaving the heat exchanger 64 undergoes Joel-Thompson expansion at the L-T valve 66 and is degraded. Thereafter, the working gas (liquid) flows into the condenser 67, and the helium evaporated within the condenser 67 is condensed. The working gas exiting the condenser 67 is heated by heat exchangers 64, 63, and 62 and returned to the compression turbine 60. The vacuum container 68 acts as a heat insulator between the low temperature part and the atmosphere.

In this way, in addition to the expansion turbine 65, the J-T
Helium can be condensed using the valve 65,
It is also possible to reduce heat intrusion from the room temperature section, and it is also possible to prevent impurities from being mixed into the working gas. However, Joel-Thompson expansion is an isenthalpic process and is basically an irreversible process, so the refrigeration efficiency is low. Furthermore, the temperature of refrigeration generated by the expansion turbine 65 is generally limited to about 15K.
Even if the working gas is further cooled by the heat exchanger 64, J
- In order to expand and liquefy the working gas in the T-valve 66, the pressure of the working gas is increased in the compression turbine 60.
It is necessary to increase the voltage from 1 atm to around 15 atm.
Turbine-type compressors can process a larger flow rate of gas than piston-type compressors, but the pressure ratio is lower, and this tendency is especially noticeable for light gases like He. For example, the pressure ratio is
It takes an 11-stage compression turbine to achieve 12.6.

As described above, the cryogenic device shown in FIG. 6, which is another solution to the conventional technology, suffers from a decrease in refrigeration efficiency and
This creates two problems that require more than one stage compression turbine.

In contrast, in the present invention, both the high-temperature region refrigerator and the low-temperature region refrigerator are basically reversible processes, and the refrigeration efficiency is high. Moreover, the pressure ratio required for the compression turbine of the refrigerator in the high temperature range may be about 2 to 3, since Joule-Thompson expansion is not used, and the number of stages of the compression turbine may be small. Furthermore, since the circuits of the high-temperature region refrigerator and the low-temperature region refrigerator are completely independent, the working gas of the high-temperature region refrigerator uses a gas other than helium, such as nitrogen, neon, or a mixture of helium and neon. be able to. Since these gases are heavier than helium, the pressure ratio of the compression turbine 1 can be increased.

[Brief explanation of drawings]

1, 2, 3, and 4 are explanatory diagrams showing a first embodiment, a second embodiment, a third embodiment, and a fourth embodiment of the present invention, and FIG. 5 shows a conventional example. The sectional view shown in FIG. 6 is an explanatory diagram showing a comparative example. In the diagram: 1...Compression turbine, 2...Radiator, 3
...Heat exchanger, 4...Expansion turbine, 5,6...
Connection member, 7... Compression bellows, 8... Expansion bellows, 9, 10... Cylinder, 11... Heat radiation part, 12
...Regenerator, 13... Condenser, 15, 16... Connecting rod.

Claims (1)

[Claims] 1. In a low-temperature device that exchanges heat between the working gas of a refrigerator in a low-temperature region and the working gas of a refrigerator in a high-temperature region, the refrigerator in the high-temperature region has one or more compression parts and expansion parts each consisting of a turbine using a gas bearing. The refrigerator in the low-temperature region has one or more compression parts and expansion parts made of metal bellows that are expandable and contracted by a connecting member connected to a power source and supported by a support cylinder, and the support A low temperature device characterized in that the cylinder and the connecting member are connected by another bellows.