JP2732686B2 - refrigerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a refrigerator, and more particularly to a Gihod McMahon type refrigerator.

(Prior Art) There are various types of cryogenic refrigerators. Among these are Gihod McMahon type refrigerators. This refrigerator is generally configured as shown in FIG.

That is, this refrigerator is largely divided into a cold head 1 and a refrigerant gas guide / discharge system 2. The cold head 1 includes a closed cylinder 11, a displacer 12 reciprocally housed in the cylinder 11,
The displacer 12 is composed of a motor 13 which supplies power required for reciprocation.

The cylinder 11 includes a large-diameter first cylinder 14 and a small-diameter second cylinder 15 coaxially connected to the first cylinder 14. A first stage 16 as a cooling surface is formed at a boundary wall between the first cylinder 14 and the second cylinder 15.
And a one-stage stage at the tip wall of the cylinder 15.
A two-stage stage 17 having a lower temperature than 16 is constituted. The displacer 12 includes a first displacer 18 that reciprocates in the first cylinder 14 and a second displacer 19 that reciprocates in the second cylinder 15. 1st displacer
The 18 and the second displacer 19 are connected in the axial direction by a connecting member 20. A fluid passage 21 extending in the axial direction is formed inside the first displacer 18, and the fluid passage 21 accommodates a cold storage material 22 formed of a copper mesh or the like. Similarly, a fluid passage 23 extending in the axial direction is formed inside the second displacer 19, and the fluid passage 23 accommodates a cold storage material 24 formed of a lead ball or the like. Seal mechanisms 25 and 26 are mounted between the outer peripheral surface of the first displacer 18 and the inner peripheral surface of the first cylinder 14, and between the outer peripheral surface of the second displacer 19 and the inner peripheral surface of the second cylinder 15, respectively. Have been.

The seal mechanisms 25 and 26 are configured as shown in FIG. 3 to FIG. 5, for example, as a representative of the seal mechanism 26. That is, an end-shaped seal ring 28 is mounted in an annular groove 27 formed on the outer peripheral surface of the second displacer 19 so that the outer peripheral surface is in contact with the inner peripheral surface of the second cylinder 15. And an end-shaped spring ring 29 for pressing the seal ring 28 against the inner surface of the cylinder. The seal ring 28 is usually formed of a resin-based material, and at both ends thereof are formed joints 30 for overlapping both ends in the radial direction as shown in FIG.

The upper end of the first displacer 18 in the figure is a connecting rod 31,
Motor 13 via Scott yoke or crankshaft 32
Is connected to the rotating shaft. Therefore, when the rotating shaft of the motor 13 rotates, the displacer is synchronized with this rotation.
12 reciprocates as shown by the solid arrow 33 in the figure.

An inlet 34 and an outlet 35 for the refrigerant gas are provided in the upper part of the side wall of the first cylinder 14, and the inlet 34 and the outlet 35 are connected to the refrigerant gas guide / discharge system 2. The refrigerant gas guide / discharge system 2 constitutes a helium gas circulation system via the cylinder 11, and the discharge port 35 is connected to a low pressure valve 36, a compressor 37,
It is connected to the inlet 34 via 38. In other words, the refrigerant gas guide / discharge system 2 compresses helium gas of low pressure (about 5 atm) to high pressure (about 18 tm) by the compressor 37 and sends it into the cylinder 11. The opening and closing of the low-pressure valve 36 and the high-pressure valve 38 are controlled in a manner described below in relation to the reciprocation of the displacer 12.

The operation of the refrigerator configured as described above will be briefly described as follows. In this refrigerator, a portion where cold occurs, that is, a portion provided for a cooling surface is a first stage 16 and a second stage 17. These cool to about 30K and 8K, respectively, when there is no heat load. For this reason, a temperature gradient from room temperature (300K) to 30K is formed between the upper and lower ends of the first displacer 18 in the drawing, and a temperature gradient from 30K to 8K is formed between the upper and lower ends of the second displacer 19 in the drawing. . However, this temperature varies depending on the heat load of each stage, and is usually 1
30-80K for stage 16 and 8-20K for stage 17
Between.

When the motor 13 starts rotating, the displacer 12 reciprocates between a bottom dead center and a top dead center. When the displacer 12 is at the bottom dead center, the high pressure valve 38 opens and high pressure helium gas flows into the cold head 1. Next, the displacer 12 moves to the top dead center. As described above, the seal mechanisms 25, 25 are provided between the outer peripheral surface of the first displacer 18 and the inner peripheral surface of the first cylinder 14, and between the outer peripheral surface of the second displacer 19 and the inner peripheral surface of the second cylinder 15, respectively. 26 is installed. For this reason, when the displacer 12 moves to the top dead center, the high-pressure helium gas passes through the fluid passage 21 formed in the first displacer 18 and the fluid passage 23 formed in the second displacer 19, and passes through the first displacer 18. It flows into a one-stage expansion chamber 39 formed between the second displacer 19 and the second displacer 19 and a two-stage expansion chamber 40 formed between the second displacer 19 and the end wall of the second cylinder 15. Along with this flow, the high-pressure helium gas is cooled by the regenerator materials 22 and 24, and eventually the high-pressure helium gas flowing into the first-stage expansion chamber 39 becomes about 30K and the high-pressure helium gas flowing into the second-stage expansion chamber 40 Is cooled to about 8K. Here, the high pressure valve 38
Is closed and the low pressure valve 36 is opened. When the low-pressure valve 36 is opened in this manner, the high-pressure helium gas in the first-stage expansion chamber 39 and the second-stage expansion chamber 40 expands to generate cold. The first stage 16 and the second stage 17 are cooled by this cold. Then, the displacer 12 moves to the bottom dead center again, and accordingly, the helium gas in the first-stage expansion chamber 39 and the second-stage expansion chamber 40 is removed. The expanded helium gas passes through the fluid passage 2
While passing through 1,23, it is warmed by cold storage materials 22,24, and is discharged at normal temperature. Hereinafter, the above-described cycle is repeated to perform the refrigeration operation. This type of refrigerator is used for cooling a superconducting magnet, cooling an infrared sensor, or as a cooling source for a cryopump.

However, the conventional refrigerator configured as described above has the following problems. That is, first,
When the second displacers 18, 19 are filled with cold storage materials 22, 24,
Since a gap is created between the cold storage material and the displacer, when gas flows through this gap, the gas and the cold storage material cannot be effectively exchanged heat.

Assuming that the temperature of the first-stage expansion chamber 39 is 30K and the temperature of the second-stage expansion chamber 40 is 10K, if a leak occurs in the gap between the displacer and the cold storage material, the helium gas of 30K is discharged into the second displacer 19. 2 without contact with cold storage material 25
Into the step expansion chamber 40, and conversely, 10K helium gas
It will enter the step expansion chamber 39. As a result, the temperature of the first stage 16 decreases, and the temperature of the second stage 17 increases. FIG. 6 shows the helium gas leakage ratio (the ratio of helium gas flowing due to leakage to the total amount of helium gas flowing into the two-stage expansion chamber 40), the temperature of each stage (first stage 16, second stage 17), and The result obtained by calculating the relationship is shown.

As can be seen from this figure, leakage between the displacer and the cool storage material has a great effect on the temperature of each stage.

(Problems to be Solved by the Invention) As described above, the conventional Gihod McMahon type refrigerator has a problem that the refrigerating capacity is low due to gas leakage from the gap between the displacer and the cold storage material.

Therefore, an object of the present invention is to provide a refrigerator capable of suppressing the gas leakage and improving the refrigerating capacity.

[Configuration of the invention]

(Means for Solving the Problems) According to the present invention, in order to achieve the above object, the present invention fills a gap between a regenerator material and a displacer with a filler formed of a fibrous material in a cotton-like manner, thereby causing gas leakage. It is to prevent.

(Function) Glass fiber fills the gap between the cool storage material and the displacer,
By filling a fibrous material such as a ceramic fiber with a filling material formed in a cotton-like manner, gas leakage can be greatly reduced, whereby heat exchange between the gas and the cold storage material can be performed effectively.

(Embodiment) FIG. 1 shows an embodiment of the present invention. Second example showing conventional example
The same parts as those in the figure are denoted by the same reference numerals and description thereof is omitted.

When filling the first displacer 18 and the second displacer 19 with the cold storage materials 22 and 24 of copper mesh and lead sphere, the first displacer 18 and the second displacer
Filling material 47 is put along the peripheral wall inside 19, and thereafter, cold storage materials 22 and 24 are filled. This filler 47 is formed by forming artificial inorganic fibers such as glass fiber, metal fiber, and ceramic fiber as a fiber material into a flocculent shape to be a filler.

Thus, the cold storage materials 22, 24 and the first displacer 18,
By filling the above-mentioned filler 47 in the gaps 48 between the second displacer 19 and the second displacer 19, gas leakage is eliminated, and heat exchange between the cold storage materials 22 and 24 and the gas can be performed effectively.

〔The invention's effect〕

As described above, according to the present invention, gas leakage can be significantly reduced only by filling the gap between the cold storage material and the displacer, so that heat exchange is effectively performed with a simple configuration, and the refrigeration capacity And an excellent effect such as improvement of

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment according to the present invention, and FIG.
FIG. 1 is a schematic configuration diagram showing the configuration of a conventional refrigerator, FIGS. 3 to 5 are schematic configuration diagrams showing the structure of a two-stage seal, and FIG. FIG. 4 is a characteristic diagram illustrating a relationship. DESCRIPTION OF SYMBOLS 1 ... Cold head, 2 ... Refrigerant gas guide / discharge system, 11 ... Cylinder, 12 ... Displacer, 13 ... Motor, 14 ... 1st cylinder, 15 ... 2nd cylinder, 16 ... 1st stage, 17 ... 2nd
Stage, 18 first displacer, 19 second displacer, 21, 23 fluid passage, 22, 24 cold storage material, 27 annular groove, 39 first expansion chamber, 40 second expansion chamber, 41 seal Mechanism, 42, 43 ... outer seal ring, 44 ... inner seal ring, 45 ... spring ring, 46 ... cut, 47 ... filler,
48… The gap.

Claims (1)

(57) [Claims] 1. A closed cylinder, a displacer slidably disposed in the cylinder and having a passage containing a cold storage material therein, means for reciprocating the displacer, and one end of the cylinder An inlet and an outlet for the refrigerant gas provided in the cylinder, and a refrigerant gas that repeats a process of introducing a high-pressure refrigerant gas into the cylinder from the inlet in relation to the reciprocation of the displacer and then discharging the gas from the outlet. A refrigerator provided with a guiding / discharging means, characterized in that the refrigerator is provided with a filler formed by forming a fibrous material into a cotton-like shape in a gap between the displacer and the cold storage material in the displacer. .