JPH02247461A - refrigerator - Google Patents

Abstract

PURPOSE:To obtain a high reliability, small-sized, and low cost helium refrigerator where no impurities are clogged in a Joule and Thomson (J/T) circuit by allowing gasified helium after expansion to cool gasified helium prior to the in-flow of said J/T valve, and a thermal shield plate, then returning said gasified helium to a compressor, and supplying the helium to an expansion equipment circuit after it is pressurized. CONSTITUTION:Since a low temperature expansion chamber of an expansion equipment is communicated with a J/T valve 11, high purity gasified helium is constantly supplied to the J/T valve under a low temperature operating state. Therefore, the heating surface of a heat exchanger 10 laid out between the equipment and the valve is free from contamination by impurities, which is quite effective to produce constantly stabilized extreme cold temperature at the J/T valve. Moreover, as low temperature and high pressure gasified helium is directly supplied to a high pressure circuit of the J/T circuit from the expansion equipment, it is not necessary to install a heat exchanger which ranges from ambient temperature up to the temperature of the expansion chamber of the expansion equipment. It is, therefore, possible to reduce the size of a container for the device and manufacture the device at low cost as well.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a refrigerator, and particularly to a small helium refrigerator that has a large low-temperature refrigeration capacity and is highly reliable.

[Conventional technology]

Conventional small heleum refrigerators, especially cryogenic refrigerators with a freezing temperature of 3 to 5, have an expander 1 as a cold generation means and an expansion It consisted of a Joule-Thomson circuit (hereinafter referred to as the 31 circuit) that was independent of the aircraft's gas flow circuit and the low-temperature region.

The gas helium compressed by the first compressor 2 is supplied to the expander 1, and the gas is expanded inside the J-T circuit heat exchanger 3,
In the first and second stages with 4 placed, the temperature is about 50
K and generates refrigeration to about 15. The gas helium after expansion is returned to the first compressor 2. On the other hand, the first part of J'1 is composed of the following equipment. The gas helium pressurized by the second compressor 5 is transferred to the heat exchanger 6,3°7.8,4,9
, 10 and is cooled through the Joule-Trosson valve 11 (
Hereinafter referred to as J-T valve), Joule-Thomson expansion is performed to generate refrigeration at a temperature of 3 to 5. After cooling the object to be cooled in the heat exchanger 12, the heat exchanger 10, 8.6 After heat exchange, the compressor returns to the second compressor 5. Further, in order to protect the cryogenic part from radiant heat from the outside, a first heat shield plate 13 and a second shield plate 14 are arranged, and the cryogenic part is cooled, for example, by a heat exchanger 7.9 in the middle of the J-T circuit. These low-temperature parts are housed in a container 15, and the inside is vacuum-insulated.

1st. Since the second compressors 2 and 5 usually inject lubricating oil into the gas as a coolant during the gas compression process, oil with a concentration of about 0.1 pps+ remains in the compressed gas. The flow of gas inside the expander periodically goes in and out of the same flow path (the regenerator built into the expander and the expansion chamber), so the oil that flows in with the gas inside the expander has a temperature range from room temperature to extreme temperature when it flows in. It condenses and precipitates in the expander, which has a temperature distribution down to low temperatures, but
When the gas flows out after expansion, the precipitated oil vaporizes and flows out of the expander together with the gas, according to the relationship between saturation temperature and saturation pressure. That is, oil does not continue to accumulate inside the expander, and the expander can be operated for a long time without any trouble.

However, in the J-Bay circuit, the gas helium that exits the second compressor 5 moves through only one circuit, so as the temperature decreases, the oil in the gas continues to precipitate inside the heat exchanger. The performance of the J-PARC may deteriorate and the temperature may not drop
Problems such as precipitation and blockage occurred in the orifice inside the valve. This kind of trouble also occurs due to impurities other than music, such as moisture and air, for the same reason.

Additionally, the J-T circuit requires many heat exchangers to cool the helium gas at low temperatures. In particular, the heat exchanger 6
is a gas helium at room temperature at a temperature of 300℃ and a temperature of about 60K.
Since the temperature difference is as large as 240 degrees Celsius, the heat exchanger becomes large in size, which hinders the miniaturization and cost reduction of refrigerators.

SUMMARY OF THE INVENTION An object of the present invention is to provide a highly reliable, compact, and low-cost compact helium refrigerator in which the inside of a J-T circuit is not clogged with impurities.

[Means to solve the problem]

In order to achieve the above object, in the present invention, a part of the gas helium in the expansion circuit is taken out of the expander from the low-temperature part of the expander, and is transferred to the high pressure of the J.1'' circuit.

This high-pressure, low-temperature gas helium is led to the low-temperature section and is expanded by the J-par valve to generate a predetermined refrigerating capacity at extremely low temperatures.

The gas helium after expansion cools the gas helium before it flows into the J/T valve, cools the heat shield plate, etc., and then returns to the compressor, pressurizes it, and supplies it to the expander circuit.

[Effect]

Since the J-T circuit supplies high-pressure, low-temperature gas helium from a low-humidity section within the expander, this gas helium is sufficiently low-temperature purified within the expander and is a high-purity gas free of impurities such as oil, moisture, and air. As a result, the J-T valve is not clogged with impurities solidified at low temperatures, and stable refrigeration operation can be performed for a long period of time. Furthermore, since the temperature of the supply section is in a sufficiently low temperature range, low-temperature gas helium can be supplied. Therefore, the heat exchanger that was required to cool down to this temperature range is no longer necessary, allowing the equipment to be made smaller, and the Ni
The manufacturing cost can be reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The high-pressure gas helium at a pressure of about 21 atmospheres that has flowed into the regenerator type expander 1 is cooled by a first to ninth refrigerant such as all-copper steel in a reciprocating displacer 16, and is heated to a temperature of about 35.
The remainder flows into the expansion chamber 17 and is further cooled to a low temperature by a second cold storage material 18 such as lead, and is expanded to a temperature of about 12.
9. Here, the gas in each expansion chamber expands to a pressure of about 7 atmospheres, generates cold, flows backward in the path it came in, cools each cold storage material, and returns to the first compressor 2. On the other hand, a part of the high-pressure, low-temperature, high-purity gas helium whose pressure is in the range of 21 to 7 atmospheres in the second* stretching machine chamber 19 is taken out and further cooled to a temperature of about 5.6 K in the heat exchanger 10. , into the J-T valve 11. Approximately 1 more with J-T valve
The gas expands to atmospheric pressure, and the temperature drops to about 4.2 K, the liquefaction temperature of helium, and part of the gas liquefies. After the object to be cooled is cooled by the heat exchanger 12, it flows into the heat exchanger 10 and cooled with high pressure gas helium, and then the second shield plate 14. The first shield plate 13 is cooled and returned to the second compressor 5. Here, the gas is compressed to about 6 atmospheres and flows into the first compressor 2.

According to this embodiment, since the low-temperature expansion chamber of the expander and the J-T valve are communicated with each other, high-purity gas helium is always supplied to the J-T valve during low-temperature operation, and the gas is placed between the J-T valve and the J-T valve. without contaminating the heat transfer surface of the heat exchanger 10 with impurities.
Further, there is an effect that the J-T valve is not blocked by impurities, and the J-T valve can always generate stable cryogenic cooling. In addition, low-temperature high-pressure gas helium is supplied to J-1 from the expander.
Since it is directly supplied to the high pressure circuit of the circuit, there is no need for a heat exchanger from room temperature to the temperature of the expander room.
This has the effect that the device container can be made smaller and manufactured at low cost. In this embodiment, the gas helium in the second expansion chamber is supplied to the high pressure side of the heat exchanger 10, but even if it is supplied from the first expansion chamber, the same effect is produced, and the heat exchanger 10 is Even if the gas helium is supplied directly from the second expansion chamber to the J-T valve instead, the same effect will occur.

In addition, in this embodiment, the J-T valve and the second expansion chamber are placed apart, but the same effect can be achieved even if an orifice hole having the same function as the J-T valve is built into the wall of the expansion chamber. produce an effect.

Furthermore, as for the expander, any means that generates refrigeration by expanding gas such as Gifford-Maxhon-Trubay, reverse Stirling, Billmeyer pulse tube, Claude cycle, etc. can be applied.

Furthermore, even when the J·'r valve and the heat exchanger 10 are not provided, the heat exchanger 12 is connected to the second pl! of the expander 1. 3 room 19
can be cooled to a temperature level of This is effective and effective when it is absolutely desired to separate the expander 1 and the heat exchanger 12.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to supply high-purity, high-pressure, low-temperature gas helium to the J-T valve circuit.
- Since the number of heat exchangers in a 1゛ circuit can be reduced, the device can be made smaller and manufactured at lower cost.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a refrigerator illustrating the structure of a small helium refrigerator according to an embodiment of the present invention, and FIG. 2 is a structural sectional view of a conventional refrigerator. 1... Expander, 19... Second expansion chamber, 11... J
-T valve. Agent: Patent attorney Masaru Koyō'K), 1st/2nd //

Claims (1)

[Scope of Claims] 1. A refrigerator that cools an object to be cooled with a first cold generating means that expands high pressure gas to generate cold, and a high pressure gas cooled by the cold of the first cold generating means, A portion of the high-pressure gas is guided from the low temperature section of the first cold generating means to the outside of the first cold generating means through a low temperature pipe, and after cooling the object to be cooled, the low temperature pipe is passed through the first cold generating means. Zuni,
A refrigerator characterized by communicating with the room temperature range. 2. The refrigerator according to claim 1, characterized in that a second cold generating means is provided in the middle of the low temperature piping.