JPH05113260A - Gifford mcmahon refrigerator - Google Patents

Abstract

PURPOSE:To prevent an insert ring, by which a piston ring to be mounted in a displacer is smoothly inserted into a cylinder, from damaging the displacer by composing the insert ring of materials having a thermal shrinkage factor smaller than the displacer. CONSTITUTION:A Gifford McMahon refrigerator has an expander 2 including driving head 7, which produces cold-heat by expanding helium gas compressed by a compressor 1, and a displacer 6 having a built-in a cold-heat accumulator 8 is reciprocated inside a cylinder 5 by the power generated by the expander 2. A seal 9 is provided to prevent helium gas from flowing through a gap between the displacer 6 and the cylinder 5, and an insert ring 10 is used when the seal 9 is assembled in the cylinder 9. In this case, the displacer 6 is molded of cotton-cloth-reinforced phenol resin, for example, and the insert ring 10 is molded of no-additive Teflon which has a larger thermal shrinkage factor than the cotton-cloth-reinforced phenol resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a Gifford McMahon refrigerator.

[0002]

2. Description of the Related Art FIGS. 1 (a) and 1 (b) show, for example, a magazine "Operator's M".
anual Cryodyne Helium Refrigerator Model 350 '' (by
FIG. 2 is a cross-sectional configuration diagram of a two-stage Gifford-McMahon refrigerator shown in CTI Inc. 1969) and a cross-sectional configuration diagram showing a main part. In the figure, 1 is a compressor for compressing helium gas,
2 is an expander that expands helium gas to generate cold, 3 is a hose that sends compressed helium gas to the expander, 4 is a hose that returns expanded helium gas to the compressor,
5 is a cylinder, 6 is a displacer, 7 is a drive head for reciprocating the displacer 6 in the cylinder 5, 8 is a regenerator built in the displacer 6, and 9 is helium gas between the cylinder 5 and the displacer 6. A seal that prevents flow through the gap, 91 is a piston ring that is a component of the seal 9, 92 is a tension ring that presses the piston ring 91 against the inner wall of the cylinder 5, and 10 incorporates the seal 9 into the cylinder 5. It is an insert ring that is sometimes used.

Next, the operation will be described. FIG. 2 illustrates how the insert 9 is used to assemble the seal 9 into the cylinder 5. As shown in the figure, the displacer 6 is inserted into the cylinder 5 while the seal 9 is held by the insert ring 10 in advance. Since the outer diameter of the insert ring 10 is larger than the inner diameter of the lower portion of the cylinder 5, only the seal 9 enters the lower portion of the cylinder 5,
The insert ring 10 remains on top of the cylinder 5 as shown in FIG.

[0004]

Since the conventional insert ring 10 and displacer 6 were made of stainless steel and cotton cloth-filled phenolic resin, respectively, when cooled, the insert ring 10 and displacer 6 differ due to the difference in heat shrinkage. There is a gap between and. Therefore, during normal operation of the refrigerator, the insert ring 10 and the displacer 6
And reciprocate relatively. Therefore, the surface of the displacer 6 is often scraped by the insert ring 10. When the displacer is ground, powder is generated, and this powder has a problem that the performance of the refrigerator is significantly deteriorated.

The present invention has been made in order to solve the above problems, and an object thereof is to obtain a Gifford-McMahon refrigerator which eliminates the possibility that the displacer is scraped by the insert ring.

[0006]

In the Gifford-McMahon refrigerator according to the present invention, the insert ring is made of a material having a heat shrinkage ratio larger than that of the displacer (cotton cloth-containing phenolic resin), such as Teflon or no other additives. It is composed of the above resins.

[0007]

The insert ring in the present invention contracts when cooled and is fixed to the displacer. Therefore, during steady operation of the refrigerator, the insert ring reciprocates together with the displacer. Therefore, the displacer is not scraped by the insert ring.

[0008]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. The Gifford-McMahon refrigerator according to an embodiment of the present invention is the same as that shown in FIG.
10 is made of additive-free Teflon, which is a material having a higher heat shrinkage rate than the above-mentioned cotton cloth-filled phenol resin.

In the refrigerator made of the above materials, the method of incorporating the seal 9 into the cylinder using the insert ring 10 is the same as the conventional method.

In the refrigerator of the present invention, the cooling does not cause a gap between the insert ring 10 and the displacer 6, which is seen in the conventional one. That is, since the heat shrinkage rate of the insert ring 10 is higher than that of the displacer 6, the insert ring 10 is cooled by cooling.
Contracts more greatly and is fixed to the displacer 6. Therefore, during steady operation of the refrigerator, the insert ring reciprocates together with the displacer, the displacer is not scraped by the insert ring, and the performance of the refrigerator does not deteriorate.

Embodiment 2. Although the material of the insert ring 10 is Teflon without any additive in the above embodiment, it may be a resin without any additive such as polyethylene or Delrin, as long as the material has a heat shrinkage ratio higher than that of the displacer 6. Good.

[0012]

As described above, according to the present invention, the insert ring is made of a material having a heat shrinkage ratio higher than that of the displacer. Therefore, when cooled, the insert ring is fixed to the displacer, and thus the insert ring is fixed to the displacer. It has the effect of eliminating the possibility of scraping and improving the durability of the refrigerator.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram showing a two-stage Gifford-McMahon refrigerator.

FIG. 2 is an illustration showing a method of incorporating a seal into a cylinder using an insert ring.

[Explanation of symbols]

 1 Compressor 2 Expander 5 Cylinder 6 Displacer 9 Seal 91 Piston ring 10 Insert ring

Claims (1)

[Claims] 1. A Gifford-McMahon refrigerator comprising an insert ring for smoothly inserting a piston ring mounted as a seal on a displacer into a cylinder, the insert ring being made of a material having a heat shrinkage ratio higher than that of the displacer.