JPH01123955A - Suction exhaust device for cryogenic refrigerator - Google Patents

Abstract

PURPOSE: To improve the sealing characteristic of a slide valve disk and a valve seat and reduce leakage from the slide valve disk by providing pressing means for pressing the valve seat to the slide valve disk side on the surface of the valve seat housed in a hollow guide box opposite to the slide valve disk. CONSTITUTION: An air supply and exhaust device 13 comprises a hollow 16 guide box 17, a valve seat 18 housed in the guide box and a slide valve disk 19 sliding in a reciprocating manner while coming into contact with the valve seat. On the surface of the valve seat 18 opposite to the slide valve disk 19, is formed a pressure bearing surface 25 for receiving refrigerant pressure from the high pressure line 2 of a compressor 1. The valve seat 18 in contact with the slide valve disk 19 receives pressure from the high pressure line 2 on the pressure bearing surface 25 formed on the surface of valve seat 18 opposite to the slide valve disk 19, so that it is pressed to the slide valve disk 19 due to the pressure difference between valve seat and the hollow part 16 of the guide box 17 communicating with the low pressure line 3 of the compressor 1. Thus, the leakage of refrigerant from the recessed part 23 of the slide valve disk to the hollow part 16 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION B) Industrial Application Field This invention relates to an improvement in the supply and exhaust system of a cryogenic refrigerator equipped with a gas cycle such as a Gifford-McMahon cycle or a Solvay cycle.

(b) Conventional technology Conventional cryogenic refrigerators of this type are described in the "Vacuum Technology Manual" (published by Sangyo Tosho Co., Ltd., July 30, 1981, p. 2).
20) (see FIG. 5), a cylinder 50, a displacer 51 that reciprocates up and down within the cylinder, and a displacer 51 that moves the cylinder 50 up and down.
a buffer space 52 and an expansion space 53 that are defined inside the displacer 51;
A heat storage material 55 disposed in this gas flow path, a compression device 56 that compresses a working gas such as helium gas, and an air supply/exhaust port 57 of the cylinder 5o are connected to a high pressure line 58 and a low pressure line 59 of the compression device 56. It is equipped with an air supply/exhaust device 6o which is communicated alternately, and this air supply/exhaust device includes an air supply valve 61 and an exhaust valve 62.
is used. Further, a load 65 is connected to the cold head 63 of the cylinder 5o via a heat transfer member 64.

In the cryogenic refrigerator described above, when the displacer 51 is at the lowest position (top dead center) in the cylinder 50.

The air supply valve 61 is opened, the exhaust valve 62 is closed, and the working gas pressurized by the compression device 56 is caused to flow into the buffer space 52. In the process in which the displacer 51 moves from the lowest position to the highest position (bottom dead center) in the cylinder 50, the working gas in the buffer space 52 is cooled by the heat storage material 55 in the gas flow path 54 and flows into the expansion space 53. . Furthermore, as the displacer 51 moves, the volume of the expansion space 53 increases. When the displacer 51 is at the uppermost position in the cylinder 5o, the air supply valve 61 is closed and the exhaust valve 62 is opened. Therefore, the working gas expands in the expansion space 53, generating cold. After that, displacer 5
In the process of 1 moving from the top to the bottom, the expansion space 53
The working gas flows through the gas passage 54 while cooling the heat storage material 55, and is further exhausted to the low pressure line 59 through the buffer space 52 and the exhaust valve 62. By repeating the above.

The cold head 63 of the cylinder 50 is cooled and the load 6
5 is subjected to cryogenic cold.

(c) Problems to be Solved by the Invention In the cryogenic refrigerator described above, the air supply valve 6 of the air supply/exhaust device 6o
Two poppet valves are often used for the exhaust valve 1 and the exhaust valve 62. However, the system using two poppet valves had drawbacks such as a complicated structure, a large number of parts, and a large air supply and exhaust system.

Further, as disclosed in Japanese Patent Application Laid-open No. 60-213777, when supplying and exhausting working gas is performed by a supply and exhaust device using one spool valve, the outer peripheral surface of the spool valve body and the spool valve body 1. Since sealing is performed by contacting the inner peripheral surface of the cylindrical sleeve that reciprocally receives the
Weak resistance to leakage of working gas (there was a problem that the efficiency of the refrigerator decreased).

Furthermore, the air supply and exhaust system using rotary pulp as disclosed in Japanese Patent Application Laid-Open No. 60-138369 has the disadvantage that the valve body has a long travel distance (and a large amount of power is required to operate the valve body). there were.

This invention was made in view of the above-mentioned facts.1
The purpose of the present invention is to provide a supply/exhaust device for a cryogenic refrigerator that is compact and requires little power, while reducing leakage of working gas and improving refrigerator efficiency.

B) Means for Solving the Problems This invention provides an air supply and exhaust system with a hollow guide box, a valve seat housed in the guide box, and a slide valve body that slides back and forth while contacting the valve seat. The valve seat is provided with an air supply/exhaust communication hole that communicates with the air supply/exhaust port of the cylinder, and a high-pressure line communication hole that communicates with the high-pressure line of the compression device. A low-pressure line communication hole is provided in the slide valve body, and a recess is provided in the slide valve body to communicate the supply/exhaust port communication hole with the high-pressure line communication hole. It is equipped with a suppressing means for pressing the seat.

(e) Effect This invention is configured as described above.

The valve seat is pressed against the slide valve element by a pressing means to improve the sealing performance between the slide valve element and the valve seat and to reduce leakage from the slide valve element.

(f) Examples The present invention will be explained below based on the examples shown in FIGS. 1 to 3.

1 is a compression device, and a high pressure line 2 and a low pressure line 3 are connected to this compression device. A cylinder 4 houses a displacer 6 that slides back and forth by a shaft 5 driven by a crank mechanism (not shown).

A variable volume buffer space 7 and an expansion space 8 are defined by this displacer.

The buffer space and the expansion space communicate with each other via a space 9 within the displacer 6. A heat storage material 10 made of wire mesh is arranged within this space. The upper wall 11 of the cylinder 4 is provided with an air supply/exhaust port 12 that opens into the buffer space 7 .

13 is a supply/exhaust device connected to this supply/exhaust port.

This air supply/exhaust device alternately connects a high pressure line 2 and a low pressure line 3 to an air supply/exhaust port 12. Bottom wall 1 of cylinder 4
4 is attached with a load heat exchanger 15 for cooling the object to be cooled.

The supply/exhaust device 13 is formed of a guide box 17 having a hollow 16, a valve seat 18 housed in the guide box, and a slide valve body 19 that slides back and forth while contacting the valve seat. The valve seat 18 is provided with a supply/exhaust communication hole 20 communicating with the supply/exhaust port 12 of the cylinder 4 and a high pressure line communication hole 21 communicating with the high pressure line 2 of the compressor 1 . Slide valve body 1
9 is a pin 22 connected at one end to a drive device (not shown).
is pivotally supported and slidably attached to the guide box 17.

The slide valve body 19 is provided with a recess 23 that communicates the supply/exhaust communication hole 2o with the high pressure line communication hole 21. The guide box 17 is provided with a low pressure line communication hole 24 that opens into the hollow 16 and communicates with the low pressure line 3 of the compression device 1. A pressure receiving surface 2 that receives refrigerant pressure from the high pressure line 2 of the compression device 1 is provided on the surface of the valve seat 18 opposite to the slide valve body 19.
5 is formed.

The operating state of the slide valve body 19 in the air supply and exhaust system for a cryogenic refrigerator configured as described above will be explained. first,
When the displacer 6 is at the uppermost position (bottom dead center) in the cylinder 4, the slide valve body 19 of the air supply/exhaust device 13 is located on the right side as shown in FIG.

The supply/exhaust communication hole 20 and the low pressure line communication hole 24 are communicated with each other, and the refrigerant in the cylinder 4 is exhausted from the low pressure line 3 to the compression device 1. Next, the displacer 6 is moved to the cylinder 4.
When the slide valve body 19 of the air supply/exhaust device 13 is located at the lowest position (top dead center) on the left side as shown in FIG. communicate through.

Refrigerant pressurized by the compression device 1 is supplied into the cylinder 4. By repeating the above operations, the supply/exhaust device 13 connects the supply/exhaust port 12 of the cylinder 4 to the high pressure line 2 and the low pressure line 3 alternately.

The valve seat 18 that the slide valve body 19 comes into contact with is a pressure receiving surface 25 formed on the opposite side of the slide valve body, and is connected to the high pressure line 2.
By being under pressure from.

Pressed against the slide valve body 19 due to the pressure difference with the hollow 16 of the guide box 17 communicating with the low pressure line 3 of the compression device 1,
This is to prevent refrigerant from leaking from the recess 23 of the slide valve body into the hollow space 16. In addition, since the valve seat 18 is pressed against the slide valve body 19, even if the sliding surface between the valve seat and the slide valve body is worn out, the slide valve body 19
The sealing performance of the material is maintained so as not to deteriorate. For this reason,
Leakage of refrigerant from the recess 23 of the slide valve body 19 to the hollow space 16 is reduced (or the refrigeration capacity is improved. Moreover, since the seal width of the slide valve body 19 is narrowed,
It has been made smaller, has a smaller stroke, and is powered by a drive device with a smaller output.

In the above description, the valve seat 18 is pressed against the slide valve body 19 by a pressure difference, but as shown in FIG. 4, the valve seat 26 is pressed against the slide valve body 19 by a coil spring 27. Needless to say, the same effect can be obtained even if the method is done in this manner.

(G) Effects of the Invention The air supply and exhaust system for a cryogenic refrigerator according to the present invention includes a hollow guide box, a valve seat housed in the guide box, and a reciprocating slide while in contact with the valve seat. It consists of a sliding valve body that moves, and the valve seat is provided with an exhaust communication hole that communicates with the supply and exhaust port of the cylinder and a high pressure line communication hole that communicates with the high pressure line of the compression device.

The guide box is provided with a low pressure line communication hole that communicates with the low pressure line of the compression device, the slide valve body is provided with a recess that communicates the supply/exhaust port communication hole with the high pressure line communication hole, and the slide valve body of the valve seat is provided with a recess that communicates with the high pressure line communication hole. Since a suppressing means is provided on the opposite side of the slide valve body to press the valve seat toward the slide valve body, by pressing the valve seat against the slide valve body, the slide valve body can be made smaller and the seal width can be narrowed. However, leakage from the slide valve body can be reduced and refrigeration capacity can be improved. Moreover, since the slide valve body can be made smaller, this slide valve body can be driven by a drive device with a small output.

[Brief explanation of the drawing]

Figures 1 to 3 illustrate the present invention, with Figure 1 being a schematic cross-sectional view of a cryogenic refrigerator, Figure 2 being a cross-sectional view of the air supply/exhaust device in the exhaust state, and Figure 3 being the air supply state. A cross-sectional view of the air supply and exhaust system,
FIG. 4 is a sectional view of a supply/exhaust device showing another embodiment, and FIG. 5 is a schematic sectional view of a conventional cryogenic refrigerator. 1... Compression device, 2... High pressure line, 3...
・Low pressure line, 4... cylinder, da, 6...
Displacer. 7... Buffer space, Total... Expansion space, 9...
・Space, 10... Heat storage material, 12... Supply/exhaust port, 13
...Air supply/exhaust system, ■-6...Hollow, 17...Information box. 18.26... Valve seat, 19... Slide valve body. 20... Supply/exhaust communication hole, 21... High pressure line communication hole. 23... recess, 24... low pressure line communication hole, 25...
...Pressure receiving surface, 27...Coil spring.

Claims (1)

[Claims] 1. A cylinder, a displacer that slides back and forth within the cylinder, a buffer space and an expansion space defined inside the cylinder by the displacer, and a gas flow path that communicates these buffer spaces and the expansion space. In a cryogenic refrigerator comprising a heat storage material provided, a compression device, and an air supply/exhaust device that alternately communicates an air supply/exhaust port of a cylinder with a high pressure line and a low pressure line of the compression device, the air supply/exhaust device comprises: It is equipped with a hollow guide box, a valve seat housed in the guide box, and a slide valve body that slides back and forth while contacting the valve seat. The communication hole is provided with a high pressure line communication hole that communicates with the high pressure line of the compression device, and the guide box is provided with a low pressure line communication hole that communicates with the low pressure line of the compression device,
The slide valve body is provided with a recess that communicates the supply/exhaust port communication hole with the high-pressure line communication hole, and the surface of the valve seat opposite to the slide valve body has a pressing force that presses the valve seat toward the slide valve body. A supply/exhaust device for a cryogenic refrigerator, characterized in that a means is provided.