JPH02123285A - Cryogenic expanding machine - Google Patents

Abstract

PURPOSE:To prevent reduction caused by agglutination in a heat exchanging area in a cryogenic expanding machine by forming a lead serving as a heat accumulating member into a linear shape, and bending up the lead or piling it up in a mesh-shape. CONSTITUTION:In a cryogenic expanding machine, a working refrigerant pressurized by a compressor 1 enters a buffer space 14 through an intake pipe 3, and flows into the second expanding space 16 as it is previously cooled by heat accumulating members 20, 21. After that, the working refrigerant expands in the expanding spaces 15, 16 to cool itself, and cools a load heat exchanger 26 to extremely low temperature in the course of the that time and then returns through an exhaust pipe 5 to the compressor 1. A lead formed in a linear shape is bent and tied up in a bundle to be filled up in the second space 19 as the heat accumulating member for such expanding machine. The lead therefore becomes hard to loosely move in different directions, and can be prevented from striking mutually to cause wear and meltedly sticking. Thus lowering of refrigerating capacity can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to an improvement in a cryogenic expander using a gas cycle such as a Gifford MacMapon cycle or a Solva cycle.

(b) Conventional technology Conventional cryogenic expanders are, for example, those published by the Japanese Patent Publications No. 1973 +, 47.
It is constructed as shown in Japanese Patent No. 87. Here, a conventional example will be explained with reference to this publication. In FIGS. 5 to 7, 50 is a compressor that pressurizes low-pressure refrigerant;
1.52 each have an intake valve 53 or an exhaust valve 54,
Additionally, there are an air supply vibe and an exhaust vibe that communicate the compressor 50 and the heat storage material 55. Reference numeral 56 denotes a cylinder having a displacer 58 driven by a crank mechanism 57. Movement of this displacer forms an expansion space 59, and this expansion space communicates with the heat storage material 55 through a vibro 0. Further, the crank mechanism 57 that drives the displacer 58 is linked with an air supply valve 53 and an exhaust valve 54, and the air supply valve 53 opens when the displacer 5B reaches the bottom dead center, and immediately before reaching the top dead center. Close to. Exhaust valve 54
opens when displacer 5B reaches top dead center,
Closes when bottom dead center is reached. 61 is a load heat exchanger, and this heat exchanger is attached to the vibro 0 to cool the object to be cooled.

In the cryogenic expander with this structure, the refrigerant compressed by the compressor 50 is guided from the air supply valve 53 to the heat storage material 55, and the refrigerant pre-cooled by the heat storage material is adiabatically expanded in the expansion space 59 to cool itself. , when the exhaust valve 54 is opened, the heat storage material 5 is discharged from the expansion space 59.
The load heat exchanger 61 is cooled by the refrigerant flowing to the refrigerant 5, so that the object to be cooled is cooled to an extremely low temperature.

(C) Problems to be Solved by the Invention However, since the conventional heat storage material 55 is formed by sandwiching granular lead between felts 62 and 62 and wire meshes 63 and 63, vibrations caused by the operation of the compressor 50 and When lead is densely packed due to the flow of refrigerant, the gap expands and the granular lead moves more easily, causing the lead to collide with each other and coagulate.
There was a problem in that the heat exchange area of the lead decreased and the refrigeration capacity decreased.

This invention solves the above-mentioned problem, and aims to prevent the heat exchange area of a heat storage material made of lead from decreasing.

(d) Means for Solving the Problems This invention provides a heat storage material to be filled inside a displacer that communicates a buffer space formed in a cylinder with an expansion space, by molding lead into a linear shape. It is formed by folding or overlapping each other into a net shape.

(E) Effect By having the above structure, the present invention prevents the lead filled inside the displacer from colliding with each other, and the heat exchange area of the heat storage material made of lead is reduced to ttIM.
I, so that it does not decrease.

(f) Examples The present invention will be explained below based on the examples shown in FIGS. 1 to 4.

Reference numeral 1 denotes a compressor, and an air supply vibe 3 having an air intake valve 2 and an exhaust vibe 5 having an exhaust valve 4 are connected to this compressor. The air supply and exhaust vibes are assembled together and connected to an air supply and exhaust port 8 provided on the upper wall 7 of the sealed container 6. The container 6 is formed of a first cylinder 9 with a large diameter and a second cylinder 10 with a small diameter. This first and second
A first displacer 12 and a second displacer 13 are housed in the cylinder and are moved up and down by a shaft 11 connected to a drive device (not shown). A buffer space 14, a first expansion space 15, and a second expansion space 16 are defined. Further, a seal ring 17 is provided on the outer periphery of the first and second displacers 12 and 13.
．． 17 is installed. buffer space 14 and the first
・The second expansion space 15.16 is the first displacer 1.
The first space 18 in the second displacer 2 and the second space 19 in the second displacer 13 communicate with each other. First space 18
The inside is filled with a heat storage material 20 made of wire mesh. Inside the second space 19 is a heat storage material 21 made of linear lead.
is filled. This heat storage material is formed by forming lead into a linear shape, bending the lead, and then stacking them together.

The heat storage material 21 is held in the second space 19 by a wire mesh 23.23 via a felt 22.22.

The linear lead is formed by using a core wire 24 made of extremely thin carbon, resin, metal, etc., and plating lead on this core wire by a method such as PvD+CvD, or by a drawing method.

A load heat exchanger 26 is attached to the bottom wall 25 of the second cylinder 10 to cool the object to be cooled.

In the cryogenic expander configured in this way, compression 4
The working refrigerant pressurized at 1111 moves from the first and second displacers 12 and 13 to the first and second expansion spaces 15 and 16 (II) at the lowest point (top dead center) in the first and second cylinders 9 and 10. )
, the air supply valve 2 is opened, the exhaust valve 4 is closed, and air flows from the air supply vibe 3 into the buffer space 14. Then, the first and second displacers 12 and 13 are moved to the expansion space 1.
In the process of moving from the 5 and 16 sides to the buffer space 14, the working refrigerant in the buffer space 14 flows into the first expansion space 15 while being pre-cooled by the heat storage material 20 in the first space 18 of the first displacer 12. , the first and second spaces 18 and 19 of the first and second displacers 12 and 13
The second expansion space 16 is pre-cooled with the heat storage material 20 and 21.
flows into. After that, the first displacer 12
When the uppermost point (bottom dead center) is reached on the side of the buffer space 14 in the cylinder 9, the air supply valve 2 is closed and the exhaust valve 4 is opened, and the working refrigerant flows into the first and second expansion spaces 15 and 16. It expands and cools itself. Again, the first and second displacer-1
2 and 13 from the buffer space 14 to the first and second expansion spaces 15 and 16, the first and second expansion spaces 1
5.16 working refrigerant is the first and second displacer 12
, 13 are cooled, passing through the buffer space 14 and returning from the exhaust vibe 5 to the compressor 1. Thereafter, the load heat exchanger 26 on the bottom wall 25 of the second cylinder 10 is repeatedly cooled to an extremely low temperature.

The heat storage material 21 that pre-cools the working refrigerant that cools the load heat exchanger 26 to a low temperature is made by bending lead formed into a linear shape, bundling it, and filling the second space 19 with the compressor 1.
The lead moves in different directions due to vibrations caused by the operation, the flow of the working refrigerant, and the reciprocating sliding of the second displacer 13.
This prevents them from colliding with each other, causing wear and adhesion. Therefore, the heat storage material 21
This prevents lead from adhering to each other, reducing the heat exchange area and eliminating gaps, thereby reducing the refrigerating capacity.

In the above description, the heat storage material 21 is formed by forming lead into a wire and then bending it. However, it may also be formed by plating lead on a bent core wire.
It goes without saying that similar effects can be obtained even if lead is foamed or the core wire is coated with gadolinium, yttrium, or erbium-based materials instead of lead.

(G) Effects of the Invention The cryogenic expander of the present invention has a displacer that communicates the buffer space formed in the cylinder with the expansion space.
The heat storage material to be filled inside was formed by forming lead into wires and then folding or overlapping the lead into a net shape. By forming the heat storage material with the heat storage material, it is possible to prevent the lead from colliding with each other and causing abrasion or adhesion due to the vibrations of the compressor, the flow of the working refrigerant, and the reciprocating sliding of the displacer. This can prevent the refrigerating capacity from decreasing due to a decrease in the exchange area.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a cryogenic expander showing an embodiment of the present invention, FIG. 2 is an enlarged perspective view of a main part of a heat storage material in an expander of this invention, and FIG. 3 is a main part of a heat storage material. Enlarged cross-sectional view,
Fig. 4 is an enlarged cross-sectional view of the main parts showing the heat storage material in a bent state, Fig. 5 is a cross-sectional view of a conventional cryogenic expander, Fig. 6 is a cross-sectional view of the heat storage device, and Fig. 7 is a cross-sectional view of the conventional cryogenic expander. FIG. 3 is an enlarged plan view showing a state in which granular lead is adhered. 9...First cylinder, 10...Second cylinder,
12...First displacer-13...Second displacer-14...Buffer space, 15...First
Expansion chamber, 16... Second expansion chamber, 21... Heat storage material. Figure 2 Figure 3rIJ Figure 4 Figure 7

Claims (1)

[Claims] 1. A cylinder, a displacer that slides back and forth within the cylinder, and a buffer space and an expansion space defined inside the cylinder by the displacer;
In a cryogenic expansion machine equipped with a heat storage material filled inside a displacer that communicates the buffer space and the expansion space, the heat storage material is made of lead formed into a linear shape, and
This cryogenic expander is characterized by being formed by folding or stacking this lead into a net shape.