JPS6136143B2 - - Google Patents

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention relates to a cryogenic refrigerator,
More specifically, the present invention relates to a cryogenic refrigerator whose expansion side includes a first expansion space and a second expansion space defined by a convex cylinder and a convex piston.

(Prior art) In this type of conventional cryogenic refrigerator, a labyrinth seal is installed in the small diameter part of the convex piston, and the working gas in the first expansion space is transferred to the second expansion space, which is lower in temperature. It is designed to prevent leakage into the expansion space and reduce refrigeration efficiency.

(Problem to be Solved by the Invention) However, there is a clearance, albeit slight, between the labyrinth seal and the inner wall of the cylinder, and because of this, there is a clearance between the labyrinth seal and the inner wall of the cylinder.
It was not possible to completely prevent the working gas from leaking into the second expansion space.

Therefore, the technical object of the present invention is to eliminate such problems.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above technical problems, the technical means taken in the present invention is to configure a cryogenic refrigerator as follows.

- A compression cylinder 1, - A compression piston 2 that is installed in the compression cylinder 1 so as to be able to reciprocate in the vertical direction and defines a compression space 3 between it and the compression cylinder 1, - A convex expansion cylinder 11, - It is installed in the expansion cylinder 11 so as to be reciprocatable in the vertical direction, and a first stage expansion space 13 and a second stage expansion space 1 are provided between the expansion cylinder 11 and the expansion cylinder 11.
6; - a cooler 21 and a first stage regenerator 22 interposed in the operating circuit between the compression space 3 and the first stage expansion space 13; - the first stage regenerator 22; a second stage regenerator 23 interposed between the stage expansion space 13 and the second stage expansion space 16; the compression piston 2 and the expansion piston 1;
A lowest pressure chamber 37 formed on the lower side of the first stage expansion space 13 and the lowest pressure chamber 3 mounted on the outer periphery of the large diameter portion of the expansion piston 12;
a seal 15 airtightly partitioning the expansion piston 12 from the expansion piston 12;
The first expansion space 13 and the second expansion space 16
a labyrinth seal 17 that airtightly partitions the compression piston 2; a rod 4 that hangs downward from the compression piston 2 and projects into the drive chamber 36 through the lowest pressure chamber 37; - a rod 4 that extends downward from the expansion piston 12; a rod 14 that hangs down and enters the drive device chamber 36 through the lowest pressure chamber 37; an air collecting groove 41 formed in the expansion piston 12 and formed in the labyrinth seal 17; and the lowest pressure chamber 37; - A prime mover 38 that moves the compression piston 2 and the expansion piston 12 up and down with a predetermined phase difference through the drive shaft 32, and - The lowest pressure chamber 37 includes: The driving device chamber 36 is filled with a working gas having a pressure equal to or lower than the minimum value of the pressure change in the working circuit, and a working gas having an arbitrary pressure is sealed in the driving device chamber 36, respectively.

Cryogenic refrigerator.

(Operation) The above technical means operates as follows. That is, from the first stage expansion space to the second stage through the clearance between the labyrinth seal and the expansion cylinder.
The working gas leaking into the stage expansion space is always guided to the lowest pressure chamber through the air collection groove formed in the labyrinth seal and the pore formed in the expansion piston, so it leaks to the second expansion space. There is no need to warm up the working gas, which has reached a low temperature. Therefore, problems as in the conventional case are not caused, and extremely low temperatures can be obtained in the refrigeration load section.

(Example) Hereinafter, an example of the present invention will be described based on the accompanying drawings.

In the drawing, a compression space 3 formed by a compression cylinder 1 and a compression piston 2 is connected to a cooler 2.
1. Communicates with the first stage expansion space 13 through the first stage regenerator 22. The first stage expansion space 13 is
Furthermore, it communicates with the second stage expansion space 16 through the second stage regenerator 23 . Said second stage expansion space 1
6, and the first stage expansion space is formed by an expansion cylinder 11 and an expansion piston 12. Labyrinth seals 17 and 18 are provided on the side surface of the head of the expansion piston 12, and an air collection groove 41 is provided at an appropriate position between the labyrinth seals 17 and 18. Further, a pore 42 having an opening in the air collection groove 41 is formed inside the expansion piston 12 . The air collection groove 41 and the lowest pressure chamber 37 are configured to communicate with each other through the pores 42 .

Furthermore, the expansion piston 12 has a first stage expansion section 1.
Seal 15 to prevent working gas from leaking from 3.
is provided. A water-cooled pocket 39 is provided surrounding the outer periphery of the expansion cylinder 11 at the portion on which the seal 15 slides to remove heat generated during sliding.

Further, the expansion piston 12 is connected to a drive shaft 32 via a rod 14. The drive shaft 32 passes through a shaft seal 34 and connects to a prime mover 38.
is connected to.

The compression piston 2 is also provided with a seal 5 to prevent leakage of working gas. Furthermore, the compression piston 2 is connected to the drive shaft 32 via the rod 4.
is connected to. The drive shaft 32 is provided within a drive device chamber 36. The drive device chamber 36
is separated from the outside world by a machine wall 33 and separated from the lowest pressure chamber 37 by a partition wall 35.
The partition wall 35 is provided with a rod seal 31, and the rods 4, 14 are connected to the rod seal 3.
It passes through 1.

On the other hand, the compression space 3 is communicated with the lowest pressure chamber 37 through a one-way valve 51. The one-way valve 51 has a sealing slope 52 serving as a sealing seat surface,
and a sphere 53 that moves due to the pressure difference, and the sphere 53 and the sealing slope 5 until a predetermined pressure difference is reached.
2 and a spring 54 that presses them together so that they do not separate.

Furthermore, around the second stage expansion space 16,
A refrigeration load section 19 is provided.

Note that the pressure in the lowest chamber 37 is from the compression space 3 to the first
It is below the lowest pressure in the circuit leading to the stage expansion space 13, and the pressure in the drive device chamber 36 is arbitrary.

In the above configuration, when the drive shaft 32 is rotated by the prime mover 38, the compression piston 2 and the expansion piston 12 reciprocate via the rods 4 and 14, respectively. Then, the working gas in the compression space 3 is compressed, the compressed working gas is cooled by the cooler 21, and the first stage regenerator 2
2, the gas reaches the first stage expansion space 13 whose volume is increasing and expands, becoming a low-temperature gas (temperature T). The low-temperature working gas is further cooled while passing through the second-stage regenerator 23, reaches the second-stage expansion space 16, and becomes an even lower-temperature gas (temperature T) due to the expansion of the space 16, and the refrigeration load Part 1
Absorbs heat load from 9.

〔Effect of the invention〕

In order to solve the above technical problem, a contact sliding type seal may be used instead of a labyrinth seal. However, in this case, the refrigeration efficiency is significantly lowered due to the sliding heat of the seal, but as is clear from the above, the present invention has the advantage that such problems do not occur.

[Brief explanation of the drawing]

The drawing is a circuit diagram of an embodiment of a cryogenic refrigerator according to the present invention. 1... Compression cylinder, 2... Compression piston,
3... Compression space, 4... Rod, 11... Expansion cylinder, 12... Expansion piston, 13... First
stage expansion space, 14... rod, 15... seal,
16...Second stage expansion space, 17...Labyrinth seal, 21...Cooler, 22...Regenerator, 36...
...Drive device room, 37...Drive device room.

Claims (1)

[Scope of Claims] 1. A compression cylinder 1; a compression piston 2 mounted in the compression cylinder 1 so as to be able to reciprocate in the vertical direction and defining a compression space 3 between it and the compression cylinder 1; a convex-shaped compression piston 2; an expansion cylinder 11; a convex expansion piston that is installed in the expansion cylinder 11 so as to be able to reciprocate in the vertical direction and forms a first stage expansion space 13 and a second stage expansion space 16 between the expansion cylinder 11 and the expansion cylinder 11; 12. A cooler 21 and a first stage regenerator 22 interposed in the operating circuit between the compression space 3 and the first stage expansion space 13, the first stage expansion space 13 and the second stage expansion space a second stage regenerator 23 interposed between the compression piston 2 and the expansion piston 12;
a lowest pressure chamber 37 formed on the lower side of the expansion piston 12; a seal 15 mounted on the outer periphery of the large diameter portion of the expansion piston 12 to airtightly partition the first stage expansion space 13 and the lowest pressure chamber 37; A labyrinth seal 17 mounted on the small diameter portion of the piston 12 and airtightly partitions the first expansion space 13 and the second expansion space 16; a rod 4 that extends downwardly from the expansion piston 12 and projects into the drive chamber 36 through the lowest pressure chamber 37; , a pore 42 that communicates the air collection groove 41 formed in the labyrinth seal 17 with the lowest pressure chamber 37, and a drive shaft 32, the compression piston 2 and the expansion piston 12 are connected to each other with a predetermined phase difference. The lowest pressure chamber 37 is filled with working gas at a pressure equal to or lower than the minimum value of the pressure change in the operating circuit, and the drive chamber 36 is filled with operating gas at an arbitrary pressure. A cryogenic refrigerator that is filled with gas.