JPH09133419A - Pulse tube freezer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make generated cold to further lower temperature without constructing a pulse tube into multiple stages by providing the tapered cylindrical pulse tube. SOLUTION: A pulse tube freezer includes a tapered cylindrical pulse tube 1 having an upper part set to be a large diameter and a lower part set to be a small diameter, and further includes therein a cylindrical gap cold storage unit 2 containing He gas capable of serving as a cold storage member for example between an outer shell cylinder 2a and an inner shell cylinder 2b. An upper end of the gap cold storage unit 2 is communicated with a supply pipe line 3 for supplying He gas from the compressor and is communicated with a reservoir tank 5 through a first orifice 4 and with the supply pipe line 3 through a second orifice 6. In the pulse tube freezer, the tapered cylindrical pulse tube 1 is used so that it is equivalent to one where the number of stages of a pulse tube is set to be infinite and hence lower temperature cold is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse tube refrigerator, and more particularly to a pulse tube refrigerator capable of achieving a lower temperature.

[0002]

2. Description of the Related Art Heretofore, a pulse tube refrigerator having a simpler structure of a GM (Gifford McMahon) refrigerator and an ST (Stirling) refrigerator has been proposed. FIG. 3 is a schematic view showing an example of a conventionally proposed pulse tube refrigerator.

This pulse tube refrigerator has a compressor 21.
The refrigerant gas is isothermally (adiabatically) compressed by, and the compressed refrigerant gas is guided to the regenerator 22 for isothermal cooling. Then, the isothermally cooled refrigerant gas is guided to the cylindrical pulse tube 23. Gas is pre-filled in the pulse tube 23, and the refrigerant gas adiabatically pushes out the pre-filled gas. That is, this pre-enclosed gas functions equivalently to the piston, and in the Stirling refrigerator, the refrigerant gas pushes out the work against the solid piston, whereas in the pulse tube refrigerator, the refrigerant gas causes the gas piston ( The extruding work will be performed for the gas that is enclosed beforehand.

In this pulse tube 23, the refrigerant gas supply side is the low temperature end heat exchange, and the opposite side is the high temperature end heat exchange. Then, when the refrigeration load absorbs heat due to the heat exchange at the low temperature end, the increment of the enthalpy is transported from the low temperature end to the high temperature end by the pushing work of the gas spring in the pulse tube 23. By this action, the pulse tube refrigerator can generate cold.

The heat exchange at the high temperature end of the pulse tube 23 is communicated with the reservoir tank 25 via the orifice 24 and, if necessary, with the discharge part of the compressor 21 via an orifice (not shown). This corresponds to a means for providing an external phase difference between the compression piston and the expansion piston in the case of a Stirling refrigerator, and is generally called a phase shifter.

Further, such a pulse tube refrigerator does not require a solid piston, and has the advantage of achieving low vibration, low cost, and high reliability, but has the drawback of low efficiency. It is known that Further, in order to further reduce the temperature of the cold generated by the pulse tube refrigerator, it is necessary to configure the pulse tube in multiple stages as shown in FIG.

In FIGS. 3 and 4, the flow of the refrigerant gas is shown by arrows.

[0008]

If the pulse tube has a multi-stage structure as shown in FIG. 4, the structure of the pulse tube refrigerator is significantly complicated as a whole, and the pulse tube refrigerator is complicated to manufacture. There is an inconvenience that it will end up. Further, when the pulse tube has a multi-stage configuration, it is preferable to provide a phase shifter for each pulse tube, so that the above-mentioned inconvenience becomes more remarkable from this aspect as well.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a pulse tube refrigerator capable of further reducing the temperature of generated cold without using a pulse tube having a multi-stage structure. It is an object.

[0010]

A pulse tube refrigerator according to a first aspect of the present invention has a tapered tube pulse tube. According to another aspect of the pulse tube refrigerator of the present invention, a pulse regenerator having a tapered cylindrical shape has a gap regenerator that cools isothermally compressed gas isobarically and supplies the gas to the small diameter side of the pulse tube. .

In the pulse tube refrigerator of the third aspect, the large diameter side of the pulse tube is communicated with the reservoir tank via the orifice.

[0012]

According to the pulse tube refrigerator of the first aspect, since the pulse tube refrigerator has the tapered tubular pulse tube, it is possible to obtain a pulse tube refrigerator equivalent to the number of stages of the pulse tube set to infinity. Therefore, it is possible to significantly suppress the complication of the structure and the complexity of manufacturing, and it is possible to lower the generated cold.

According to another aspect of the pulse tube refrigerator of the present invention, the taper tube-shaped pulse tube has a gap regenerator for isothermally cooling the isothermally compressed gas and supplying the gas to the small diameter side of the pulse tube. Therefore, the structure can be simplified as compared with the case where the regenerator is separately provided and connected in series with the pulse tube. Further, the gap regenerator serves as a counter when exchanging heat with the gas in the pulse tube, and the working fluid itself can be used as a regenerator material, so the problem of insufficient heat capacity of the regenerator at extremely low temperatures (for example, 20 K or less) is solved The efficiency can be improved.

In the pulse tube refrigerator of claim 3, since the large diameter side of the pulse tube communicates with the reservoir tank through the orifice, the phase difference between the pressure and the flow velocity wave can be controlled, The efficiency can be increased.

[0015]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a schematic vertical sectional view of an essential part showing an embodiment of the pulse tube refrigerator of the present invention. This pulse tube refrigerator has a tapered tube-shaped pulse tube 1 whose upper portion has a large diameter and whose lower portion has a small diameter.
Inside, there is a cylindrical gap regenerator 2. Then, the upper end portion of the gap regenerator 2 is communicated with the supply pipeline 3 for supplying the compressed He gas from the compressor (not shown). Further, the upper end portion of the pulse tube 1 communicates with the reservoir tank 5 via the first orifice 4 and also communicates with the supply pipeline 3 via the second orifice 6. Further, the gap regenerator 2 is communicated with the pulse tube 1 at its lower end, and the lower end of the pulse tube 1 is set to low temperature end heat exchange and the upper end is set to high temperature end heat exchange. In addition, 7 is a flange for attachment.

The gap regenerator 2 is an outer shell cylinder 2a.
Between the inner shell 2b and the inner shell cylinder 2b, for example, He gas that can function as a regenerator material is housed.
A closing plate 2c is provided at the end of the cylinder 2b to separate the space defined by b from other spaces. Also, the movement of He gas is shown by an arrow.

The operation of the pulse tube refrigerator having the above structure is as follows. In this pulse tube refrigerator,
Since the tapered tube pulse tube 1 is used, it is equivalent to setting the number of stages of the pulse tube to infinity, and the cold generated can be made colder, and when the pulse tube has multiple stages. It is possible to significantly suppress the complication of the structure as compared with. Of course, the production of the pulse tube refrigerator can be simplified.

Further, since the gap regenerator 2 serves as a counter when exchanging heat with the He gas in the pulse tube 1, and the He gas can be used as a regenerator material,
The problem of insufficient heat capacity of the regenerator material at extremely low temperatures (for example, 20 K or less) can be solved, and the refrigeration efficiency can be improved. Furthermore, since the phase shifter is constituted by the first orifice 4, the reservoir tank 5 and the second orifice 6 and the phase difference between the pressure and the flow velocity wave is controlled, the refrigeration efficiency can be improved also from this aspect. .

Further, since the pulse tube refrigerator does not use the fixed piston but uses the gas piston, there is no mechanical vibrating portion and the generation of magnetic noise can be greatly reduced. FIG. 2 is a schematic vertical sectional view showing another embodiment of the pulse tube refrigerator of the present invention.

This pulse tube refrigerator has a pulse tube refrigerator shown in FIG. 1 in which the gap regenerator 2 is replaced by a regenerator 8 having a taper smaller than that of the pulse tube 1 (its material is conventionally known). The other components are the same as those of the pulse tube refrigerator of FIG. As the regenerator 8, it is preferable to use a magnetic regenerator material to prevent insufficient heat capacity of the regenerator material at an extremely low temperature (for example, 20 K or less).

The movement of He gas is indicated by an arrow. Even when this pulse tube refrigerator is adopted, since the tapered tube pulse tube 1 is adopted, it becomes equivalent to setting the number of stages of the pulse tube to infinity,
The generated cold can be made lower in temperature, and the complication of the structure can be significantly suppressed as compared with the case where the pulse tube has multiple stages. Of course, the production of the pulse tube refrigerator can be simplified.

Since the phase shifter is constituted by the first orifice 4, the reservoir tank 5 and the second orifice 6 and the phase difference between the pressure and the flow velocity wave is controlled, the refrigerating efficiency is improved also from this aspect. be able to.
Further, since the pulse tube refrigerator does not use the fixed piston but uses the gas piston, there is no mechanical vibrating portion, and the generation of magnetic noise can be significantly reduced.

Although the modification type pulse tube refrigerator has been described above as an example, it is needless to say that the same can be applied to a basic type pulse tube refrigerator.

[0024]

According to the invention of claim 1, it is possible to obtain a pulse tube refrigerator which is equivalent to setting the number of stages of the pulse tube to infinity, and significantly suppress the complication of the structure and the complexity of manufacturing. In addition to the above, there is a unique effect that the generated cold can be lowered in temperature.

According to the invention of claim 2, the structure can be simplified as compared with the case where the regenerator is separately provided and connected in series with the pulse tube, and the gap regenerator is a gas in the pulse tube. It becomes a counter when exchanging heat with, and the working fluid itself can be used as a regenerator material, so it is possible to solve the problem of insufficient heat capacity of the regenerator at extremely low temperatures (for example, 20 K or less) and improve efficiency. Has a unique effect.

The invention of claim 3 has a unique effect that the phase difference between the pressure and the flow velocity wave can be controlled and the efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional view of an essential part showing an embodiment of a pulse tube refrigerator of the present invention.

FIG. 2 is a schematic vertical sectional view of an essential part showing another embodiment of the pulse tube refrigerator of the present invention.

FIG. 3 is a schematic vertical cross-sectional view showing an example of a conventionally proposed pulse tube refrigerator.

FIG. 4 is a schematic vertical cross-sectional view showing an example of a pulse tube refrigerator in which pulse tubes are configured in multiple stages.

[Explanation of symbols]

 1 pulse tube 2 gap regenerator 4 first orifice 5 reservoir tank

Claims (3)

[Claims] 1. A pulse tube refrigerator comprising a pulse tube (1) having a tapered cylindrical shape. 2. A gap regenerator (2) for isothermally cooling an isothermally compressed gas and supplying it to the small diameter side of the pulse tube (1) in a tapered tube-shaped pulse tube (1). The pulse tube refrigerator according to claim 1, which has. 3. The pulse tube refrigerator according to claim 1, wherein the large diameter side of the pulse tube (1) communicates with the reservoir tank (5) through the orifice (4).