JPH01114670A - Cryogenic refrigerator - Google Patents

Abstract

PURPOSE: To improve a refrigerating capacity by a constitution wherein an expandible-contractible gas chamber formed of an elastic material is provided at a high-temperature end of a pulse tube, and a liquid coolant is filled around the gas chamber so that it communicates with an outside liquid reservoir through an orifice and further functions preferably as a working fluid. CONSTITUTION: When a piston 5 of a compressor 4 is depressed, an internal pressure of a pulse tube 1 rises in a moment and thereafter high pressure gas is introduced gently into the tube 1 from a low-temperature end 1a through a regenerator 2. At this time, the gas in the tube 1 is compressed adiabatically and the temperature thereof rises, while the volume of a gas chamber 10 at a high-temperature end 1b is expanded by a gas pressure. Then a liquid coolant 12 filled in a power absorbing chamber 11 surrounding the gas chamber 10 cools down compressed gas in the gas chamber 10, while a liquid pressure rises relatively and the liquid flows out into an outside liquid reservoir 13 from a communication passage 14 through an orifice 15. As the result, the liquid coolant 12 in the power absorbing chamber 11 takes out the energy of the compressed gas in the tube 1 as expansion work and this is converted into thermal energy by the orifice 15 and vanished.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pulse tube type cryogenic refrigerator that uses a pulse tube to achieve a cryogenic temperature of 100'' or less.

[Prior Art] In recent years, a pulse tube refrigerator using a pulse tube has been proposed as a small-sized cryogenic bath method that does not require any moving parts at extremely low temperatures.

This refrigerator utilizes the heat exchange function of a pulse tube, which creates a temperature gradient when gas is introduced inside and reciprocated, creating a low-temperature end on the gas introduction side and a high-temperature end on the opposite side. A major feature is that it does not suffer from performance deterioration due to vibration or wear caused by the presence of moving parts.

The previously proposed pulse tube refrigerator is a combination of a pulse tube generator and its specific configuration is shown in FIG. That is, the low temperature end 1a of the pulse tube 1 and the low temperature end 2a of the regenerator 2 are connected to the heat absorption section (
The gas supplied from the compressor 4 to the high temperature end 2b side of the regenerator 2 via the aftercooler 7 is connected to the pulse tube 1 via the regenerator 2 and the heat absorption section 3. The gas is introduced from the low temperature end 1a toward the high temperature end lb.

In this pulse tube refrigerator, the gas compressed by the piston power of the compressor 4 passes through the inside of the regenerator 2 and enters the heat absorption section 3 and the low temperature end 1a of the pulse tube 1a while being precooled. Low temperature end 1a
The high-pressure gas introduced into the high-temperature end 1
Compress toward b. At this time, the gas in the pulse tube 1 undergoes adiabatic compression and moves through the tube 1 with a temperature gradient while increasing in temperature. Then, the compressed gas enters the heat radiation part (heat exchanger) 8 of the pulse tube high temperature end 1b,
Here, heat is radiated and cooled. Next, when the piston 5 is pulled up, the gas that has released heat in the heat radiation part 8 expands adiabatically in the pulse tube 1 and cools down, and then returns while cooling the heat absorption part 3 and the regenerator 2, and this cycle is repeated. 100 to the heat absorption part 3 that cools the object to be cooled.
Extremely low temperatures below ° can be achieved.

[Problems to be Solved by the Invention As described above, the copulse tube refrigerator generates cold by repeating adiabatic compression and expansion by the action of the gas piston inside the pulse tube, but it is difficult to improve the refrigeration efficiency. In order to increase the temperature, it is important to release the retained energy of the gas as efficiently as possible in the adiabatic compression stroke toward the high-temperature end in the tube, and then move to the adiabatic expansion stroke.

However, in the case of the above-mentioned pulse tube refrigerator, the heat dissipation section (water-cooled heat exchanger) 8 placed on the high-temperature end of the tube simply releases heat energy from the compressed gas in the tube. There is a certain limit to the amount of cold that can be obtained by self-cooling the gas.

The present invention focuses on these problems and focuses on improving the refrigerating capacity of a pulse tube type compact cryogenic refrigerator that can eliminate low-temperature moving parts.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an expandable and contractible gas chamber made of an elastic material at the high-temperature end of the pulse tube, and also provides a gas chamber around the gas chamber. A power absorption chamber is provided which communicates with an external liquid reservoir via an orifice and is preferably filled with a cooling liquid as a working fluid.

[Operation] If a power absorption mechanism is added to the high-temperature end of the pulse tube, when the high-pressure gas introduced into the low-temperature end of the tube adiabatically compresses the gas inside the tube toward the high-temperature end, The gas chamber at the high temperature end expands, and the resulting change in volume forces the coolant in the power absorption chamber to be discharged through the orifice into an external reservoir. At this time, the liquid reservoir communicating with the gas chamber performs a damper function, extracts the energy of the compressed gas from the gas chamber as expansion work, and consumes it as heat energy in the orifice. If the working fluid filled in the liquid reservoir is also used as a cooling fluid, the effect of cooling the compressed gas in the gas chamber is simultaneously exerted, increasing the degree of energy absorption in the negative layer. Therefore, the compressed gas within the pulse tube achieves efficient energy absorption, which directly leads to an increase in refrigeration capacity.

[Example code] An embodiment of the present invention will be described below with reference to FIG. 1.

However, this embodiment shows a system configuration in the case of a Stirling cycle, similar to the conventional example shown in FIG.

The basic configuration of the cryogenic refrigerator according to the present invention is the same as that of the pulse tube refrigerator described above, and in the figure, 1 is a hollow pulse tube made of a thin stainless steel pipe, etc., and 2 is a heat storage element inside. The low-temperature ends 1a12a of both are connected by mounting or a generator, and a heat absorption part 3 for cooling the object to be cooled is provided between them. A compressor 4 fitted with a piston 5 is connected to the high temperature end 2b of the regenerator 2.
A gas passage 6 for introducing and introducing gas is communicated with the compression chamber, and an aftercooler 7 is provided in the middle of the passage 6.

On the other hand, at the high temperature end (normal temperature end) 1b of the pulse tube 1,
In place of the conventional water-cooled heat exchanger 8, a power absorption mechanism according to the present invention is provided. This mechanism is constructed as follows.

First, the high-temperature end 1b of the pulse tube 1 is narrowed to a small diameter, and a gas chamber 10 is provided above the high-temperature end 1b into which the gas rising in the tube 1 is introduced with force. This gas chamber 10 is formed in the shape of a balloon with a thin film-like elastic material, and the opening edge at one lower part is connected to the upper end of the tube.
b, and can be expanded and contracted as shown by the arrows in the figure by the gas pressure of the compressed gas introduced into the inside.

Further, a power absorption chamber 11 made of a rigid container is provided around the gas chamber 10 to liquid-tightly surround the gas chamber 10. The inside of the power absorption chamber 11 is filled with a cooling liquid 12 as a working fluid, which is in contact with the outer surface of the gas chamber 10 . The cooling liquid 12 plays the role of cooling the gas chamber 10 and at the same time extracting the work of gas expansion, which is the primary aim of the present invention, and is an incompressible liquid (for example, water).

Furthermore, a liquid reservoir 13 for storing a cooling fluid (working fluid) 12 is provided outside the power absorption chamber 11, and an orifice 15 is inserted between one side of the power absorption chamber 11 and the bottom of the liquid reservoir 13. They are communicated through a communication channel 14. In this case, the liquid reservoir 13 has an offset spring 13b interposed on the back surface of the fitting piston 13a, and the coolant 13 stored therein.
It consists of a hydraulic cylinder that keeps the hydraulic pressure of 2 approximately constant.

The cryogenic refrigerator having the above configuration operates a refrigeration cycle similar to the conventional pulse tube refrigerator described above, and at this time, the power absorption mechanism added to the high temperature end 1b of the pulse tube 1 operates effectively. do. When the piston 5 of the compressor 4 is pushed down, the internal pressure of the pulse tube 1 rises instantaneously, and then passes through the regenerator 2 to the low temperature end 1a.
High pressure gas is slowly introduced into the tube 1. At this time, the gas in the tube 1 is adiabatically compressed and heated, and the gas pressure expands the volume of the gas chamber 10 at the high temperature end 1b. Then, the power absorption chamber 11 around the gas chamber 10
The coolant 12 filled with water cools the compressed gas in the gas chamber 10, and the liquid pressure increases relatively, causing the communication flow path 1 to cool.
4 through an orifice 15 into an external reservoir 13. As a result, the cooling liquid 12 in the power absorption chamber 11 extracts the energy of the compressed gas in the tube 1 as expansion work, converts it into thermal energy in the orifice 15, and dissipates it.

In this way, the power absorption mechanism cools the compressed gas during the adiabatic compression stroke of the pulse tube 1, and at the same time extracts the retained energy as expansion work.
When the piston 5 of the compressor 4 is pulled up and the gas in the tube 1 is rapidly expanded into an adiabatic expansion stroke, the expanded gas that is self-cooled and pushed out from the low temperature end 1a of the tube 1 can be brought to a cryogenic temperature. , it becomes possible to develop a large refrigerating capacity by the heat absorbing section 3 which is cooled by the return gas. In addition, during the expansion stroke of the pulse tube 1, the liquid pressure in the power absorption chamber 11 decreases relatively as the gas chamber 10 contracts, and the cooling liquid 1 is filled inside by the piston action of the liquid reservoir 13.
2 will be automatically replenished.

Although the embodiment of the present invention has the above-described configuration, operation, and effect, the form of the gas chamber 10 formed at the high temperature end 1b of the pulse tube 1 is of course not limited to the one illustrated, and may be other than that described above, such as a bellows. Alternatively, a diaphragm may be used.

Further, the refrigeration cycle can also be operated by a GM cycle, provided that a timing valve is added.

[Effects of the Invention] As described above, the cryogenic refrigerator of the present invention takes advantage of the pulse tube refrigerator's feature of eliminating low-temperature moving parts by installing a predetermined power absorption mechanism at the high temperature end of the pulse tube. However, it can compensate for the lack of refrigeration capacity.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a cryogenic refrigerator showing an embodiment of the present invention. FIG. 2 is a system diagram showing the configuration of a conventional pulse tube refrigerator. 1...Pulse tube 2...Regenerator 1
a s 2 a...low temperature end 1b, 2b...high temperature end 3...endothermic part

Claims (2)

[Claims] (1) A feature is that an expandable and contractible gas chamber made of an elastic material is provided at the high-temperature end of the pulse tube, and a power absorption chamber is provided around this gas chamber that communicates with an external liquid reservoir through an orifice. Cryogenic refrigerator. (2) The cryogenic refrigerator according to claim 1, wherein the liquid reservoir in the power absorption chamber is filled with cooling liquid.