JPH0636452Y2 - Cryogenic refrigerator - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a refrigerator used for cooling an extremely low temperature (for example, a temperature of 100K or less) device.

[Conventional technology]

FIG. 2 is a conventional structure which is composed of a Jouille-Thomson loop consisting of a reciprocating refrigerator and a heat exchanger using a piston or displacer such as a Stirling cycle, a Gifode McMahon cycle, a Solvay cycle, etc. It is a system diagram of the ultra-low temperature refrigerator. FIG. 3 is a system diagram of a pulse tube refrigerator used conventionally.

First, FIG. 2 will be described. Reference numeral 1 is the reciprocating refrigerator, 2 is the Jouille-Thomson loop, 3 is a gas compressor for supplying high-pressure helium gas to the reciprocating refrigerator 1, 4
Is a high-pressure gas pipe, 5 is a low-pressure gas pipe in which the helium gas adiabatically expanded in the reciprocating refrigerator 1 returns to the gas compressor 3, 6 is a first-stage cold generating part in which the reciprocating refrigerator 1 produces cold,
Reference numeral 7 is a second-stage cold generation part. The first stage cold generation unit 6 has a minimum temperature of about 40K, and the second stage cold generation unit 7
Is about 10K as the lowest temperature. 8 is a gas compressor for supplying high-pressure helium gas to the Jouille-Thomson loop 2, 9 is high-pressure gas pipe, 10 is low-pressure gas pipe, 1
1, 12 and 13 are heat exchangers for exchanging heat between the high-pressure helium gas and the low-pressure helium gas, recovering the cold of the low-pressure helium gas, and cooling the high-pressure helium gas. 14,15 are impurities in high-pressure helium gas (gas other than helium gas,
A low-temperature adsorber for removing foreign substances such as dust), and the gas passage inside the adsorber is filled with activated carbon, molecular sieves, and the like. 16, 17 are heat exchangers for cooling the high-pressure helium gas by exchanging heat between the first-stage cold generating part 6 and the second-stage cold generating part 7, and 18 is a high-pressure helium gas
It is a Gyur-Thomson valve for Thomson expansion (isoenthalpy expansion) to generate low-pressure and cryogenic helium gas. Reference numeral 19 is a cooling unit for mounting an object to be cooled for cooling to an extremely low temperature. Reference numeral 20 denotes a heat shield plate for preventing the radiant heat from entering from the room temperature portion to the low temperature portion, which is thermally connected to the first stage cold generating portion 6 to be cooled, and the heat load of the radiant heat that enters is reduced to the first stage cold. It is absorbed by the generation unit 6. Reference numeral 21 is a vacuum container for vacuum heat insulation, and 22 is a vacuum part for heat insulation.

In the Jouille-Thomson loop 2, the high pressure helium gas in the gas compressor 8 is passed through the high pressure gas pipe 9 and the heat exchanger 11 to exchange heat with the low temperature / low pressure helium gas returned to the low temperature / high pressure helium gas. It becomes gas. After passing through the low temperature adsorber 14 to remove gases other than water and helium gas, such as oxygen gas, having a high boiling point (80 K or more),
In the heat exchanger 16, the high pressure helium gas becomes even lower in temperature. Similarly, the high pressure helium gas cooled to around 10K in the heat exchangers 12, 17, 13 is a gas other than helium gas in the low temperature adsorber 15, such as hydrogen gas, after removing the gas having a boiling point of 20K or more,
Adiabatic expansion is performed by the Jouille-Thomson valve 18. As a result, the temperature of the low-pressure gas becomes 10 K or less, and the desired cooling temperature can be obtained. The low-temperature helium gas, which has cooled the object to be cooled in the cooling unit 19, exchanges heat with the heat exchangers 13, 12, 11 to recover cold, and then returns to room temperature and returns to the gas compressor 8.

Next, FIG. 3 will be described. 31 is a gas compressor that supplies high-pressure helium gas, 32 is high-pressure gas piping, 33 is low-pressure gas piping, 34 is high-pressure gas supplied to the freezing section, or low-pressure gas is exhausted from the freezing section to the gas compressor 31. It is a rotary valve that performs switching for returning. Reference numeral 35 is a gas pipe for sending high-pressure helium gas to the freezing section and returning low-pressure helium gas from the freezing section. The rotary valve 34 periodically reciprocates the high-pressure gas and the low-pressure gas at about 100 times / minute. Reference numeral 36 denotes a regenerator, which is filled with a copper wire mesh (100 mesh to 400 mesh) or a lead ball having a diameter of 1 mm or less as a regenerator material. 37 is a gas pipe similar to 35. Reference numeral 38 denotes a cold generation part, which cools by attaching an object to be cooled. 39 is made of a porous sintered metal such as ceramics, and has a rectifying function for helium gas and a heat exchange function for sufficiently recovering the low temperature / low pressure helium gas discharged. 40 is a pulse tube made of a material with poor heat conduction such as stainless steel, in which high-pressure helium gas moves to the upper part, and when the pressure becomes low next, the helium gas moves to the lower part. Helium gas repeats this intermittent vertical reciprocating motion. Reference numeral 41 denotes a heat dissipation part, which is made of a material having good heat conductivity such as copper. Reference numerals 42 and 43 are an inlet of cooling water and an outlet of cooling water for cooling the heat radiating portion 41.

The freezing principle of FIG. 3 is as follows. The high-pressure helium gas compressed by the gas compressor 31 passes through the high-pressure gas pipe 32, the rotary valve 34, and the gas pipe 35, is cooled by the regenerator 36, and then passes through the gas pipe 37 and the sintered metal portion 39 to be pulsed. Enter tube 40. There is initially low-pressure helium gas in the pulse tube, but the low-pressure helium gas in the tube is also compressed by the compression action of the high-pressure gas. Due to this compression action, heat of compression is generated in the tube, and the temperature of the gas forms a temperature gradient that is high near the heat radiating portion 41 and low near the sintered metal portion 39. Most of the compression heat is generated in the vicinity of the heat radiating section 41, so the cooling water removes the heat. Next, when the rotary valve 34 is switched to the low pressure side of the gas compressor 31, the high pressure gas inside the pulse tube 40 adiabatically expands and the temperature drops. The temperature of this gas is lower than that at the start of compression because heat is removed before the expansion starts, and as a result, the lower part of the pulse tube 40, that is, the vicinity of the sintered metal part 39, becomes the lowest temperature part, An object to be cooled can be attached to the cold generation part 38 to cool it. By repeating the above cycle, cold is generated intermittently. Therefore, according to the configuration shown in FIG. 3, when the heat radiating section 41 is at room temperature, the cold generating section 38 can obtain the temperature of 124K. it can.

[Problems to be solved by the invention]

In the refrigerator shown in FIG. 2, heat exchangers 11,12,13,16,17 are required in the Jouille-Thomson loop, so the cost of the device is high and the space for the heat exchanger is large.
Therefore, the entire refrigerator shown in Fig. 2 is inevitably expensive and large. Further, impurities (moisture, oil, etc. solidified at a low temperature, dust, etc.) contained in the helium gas block the Djuul-Thomson valve 18 during operation, which causes a problem.

The pulse tube refrigerator shown in FIG. 3 shows a type that produces cold in one stage. It is possible to obtain even lower temperatures by increasing this in multiple stages, but at present the temperature
It is difficult to reach below 10K.

[Means for solving problems]

The present invention solves the above-mentioned problems of the prior art and comprises a reciprocating refrigerator and a pulse tube refrigerator using a piston or a displacer such as a Stirling cycle, a Gifode McMahon cycle, a Solvay cycle, etc. And a heat dissipation part of the pulse tube refrigerator is thermally connected to a cold generation part of the reciprocating refrigerator.

[Action]

The cryogenic refrigerator of the present invention uses a conventional reciprocating refrigerator to generate cryogenic temperatures up to 10K to 20K, and a pulse tube refrigerator to generate cryogenic temperatures below 10K. Are used in combination with each other so that heat is drawn up in two steps.

〔Example〕

FIG. 1 is a system diagram of an embodiment of the present invention. 2 and 3 have the same reference numerals, the description thereof is omitted. In FIG. 1, the reciprocating refrigerator 1 includes a first-stage cold generating unit 6 and a second-stage cold generating unit 7, each having a temperature of 60K to 8K.
Cold temperatures of about 0K and about 10K to 20K are generated. The second-stage cold generation unit 7 is thermally connected to the heat radiation unit 41 of the pulse tube refrigerator to cool the heat radiation unit 41. Since the regenerator 36 of the pulse tube refrigerator has a high temperature part at room temperature (about 300K) and a low temperature part at extremely low temperature (10K or less), most of the invasion heat due to heat conduction from the room temperature part 20 It is structured so that it is absorbed by the first-stage cold generation part 6 via the.

The high-pressure helium gas in the gas compressor 31 is supplied with the high-pressure gas pipe 32, the rotary valve 34, the gas pipe 35, and the regenerator 36.
After being cooled down to a temperature of about 10 K through the gas pipe 37 and the sintered metal portion 39, the pulse tube 40 is entered. The heat of gas compression inside the pulse tube is absorbed by the second stage cold generation section 7 via the heat dissipation section 41. Next, when the rotary valve 34 is switched to the low pressure side, the gas inside the pulse tube adiabatically expands and the temperature of the cold generation part 38 drops below 10K to generate cold. The helium gas that has reached a low temperature passes through the gas pipe 37, the cold is recovered by the regenerator 36, and the temperature becomes room temperature. The low-pressure helium gas that has reached room temperature returns to the gas compressor 31 through the gas pipe 35, the rotary valve 34, and the low-pressure gas pipe 33. About 1 minute of the above refrigeration cycle
By carrying out about 100 times, it is possible to intermittently generate a cold temperature of 10 K or less.

[Effect of device]

As described in detail above, the present invention uses a reciprocating refrigerator having a relatively high efficiency to generate cold at temperatures of 10K to 20K, and a pulse tube refrigerator to generate cold at temperatures of 10K or less. It has a complex structure. In this combination, the regenerator is used without using the countercurrent heat exchanger, and because the regenerator performs the role of the low-temperature adsorber, an independent low-temperature adsorber is unnecessary, and so on. The cryogenic refrigerator as a whole can be made smaller, lighter and less expensive. In addition, since there is no drive unit such as the Jule Thomson valve in the low temperature part, there are few failures and high reliability.

In short, according to the present invention, it is possible to provide a cryogenic refrigerator having a small size, a light weight, a low price and a high reliability.

[Brief description of drawings]

FIG. 1 is a system diagram of one embodiment of the present invention, FIG. 2 and FIG.
The figure is a conventional system diagram. 1 ... Reciprocating refrigerator, 2 ... Jouille-Thomson loop, 3 ... Compressor, 4 ... High-pressure gas pipe, 5 ... Low-pressure gas pipe, 6 ... First stage cold generation part, 7 ... Second stage cold generation part, 8 ... Gas compressor, 9 ... High-pressure gas pipe, 10 ... Low-pressure gas pipe, 11 ... Heat exchanger, 12 ... Heat exchanger, 13 ... Heat exchanger, 14 ...... Low temperature adsorber, 15 ...... Low temperature adsorber, 16 ...... Heat exchanger, 17 ...... Heat exchanger, 18 ...... Jule Thomson valve, 19 ...... Cooling section, 20 ...... Heat shield plate, 21 ・ ・ ・… Vacuum container, 22 …… Vacuum part, 31 …… Gas compressor, 32 …… High pressure gas piping, 33 …… Low pressure gas piping, 34 …… Rotary valve, 35 …… Gas piping, 36 …… Regenerator, 37 ...... Gas pipe, 38 …… Cold generation part, 39 …… Porous sintered metal, 40 …… Pulse tube, 41 …… Radiation part, 42 …… Cooling water inlet, 43 …… Cooling water outlet.

Claims (1)

[Scope of utility model registration request] 1. A reciprocating refrigerator using a piston or a displacer such as a Stirling cycle, a Gifode-McMahon cycle, a Solvay cycle, and a pulse tube refrigerator, and a cold generation part of the reciprocating refrigerator. A cryogenic refrigerator characterized in that the heat dissipation portion of the pulse tube refrigerator is thermally connected.