JP2006017422A - Phase control mechanism for pulse tube refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phase control mechanism for an inexpensive, small, and lightweight pulse tube refrigerating machine having no vibrations. <P>SOLUTION: A coil part 412b excluding a lead-in part 411 from a high temperature end 34 in an inertance tube 41b is integrally housed and fixed in an interior of a buffer tank 42a. Since a coiled portion is fixed, it hardly vibrates, and since an inner and outer pressure difference of the inertance tube becomes substantially small in the buffer tank, thickness of the tube can be thinned, and usage of a resin tube becomes possible also. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a phase control mechanism of a pulse tube refrigerator that is a cryogenic refrigerator.

A pulse tube refrigerator is well known as a small refrigerator that generates an extremely low temperature such as liquid nitrogen temperature.
3 and 4 are conceptual diagrams showing the configuration of a conventional example of this pulse tube refrigerator. The pulse tube refrigerator includes a compressor 1, a high temperature side heat exchanger 2, an expander 3, and a phase control mechanism 4. The compressor 1 includes a pair of linear motors (motors in the figure) 11, a pair of pistons 12 reciprocally driven left and right by these, a cylinder 13 that surrounds the outside of the piston 12 and has a working gas inlet / outlet in the center, And a case 14 that hermetically wraps these outsides except for the entrance and exit of the working gas. The expander 3 includes a regenerator 31, a low temperature end 32, a pulse tube (pulse tube in the figure) 33, and a high temperature end 34. The phase control mechanism 4 includes an inertance tube 41 or 41a and a buffer tank. The inertance tube is a metal tube having an inner diameter of about 2 to 3 mm, has a length of about 2 to 4 m, and is mostly formed in a coil shape.

The principle of operation of the pulse tube refrigerator generating the cryogenic temperature is understood as follows.
In this refrigerator, helium gas or the like is used as a working gas for generating a cryogenic temperature. The working gas is sealed in the internal space from the compressor 1 to the phase control mechanism 4 at a pressure of about 1 to 3 MPa, and compression and expansion are repeated by the compressor 1. The working gas compressed by the piston 12 of the compressor 1 flows into the high temperature side heat exchanger 2 where the heat of compression is dissipated. The pressure of the working gas flowing out to the phase control mechanism 4 is controlled by the phase control action of the phase control mechanism 4, and the working gas flowing from the regenerator 31 through the low temperature end 32 to the pulse tube 33 performs expansion work. Cool the cold end 32. On the other hand, the amount of heat corresponding to the expansion work is radiated from the high temperature end portion 34. When the piston 12 operates in the suction direction, the low-temperature working gas returns to the compressor 1 while cooling the low temperature end 32 and the regenerator 31. By repeating the reciprocating motion of the working gas, a cryogenic temperature of 100K or less is obtained at the low temperature end portion 32.

The inertance tube 41 or 41a of the pulse tube refrigerator configured as described above includes an introduction portion 411 connected to the high temperature end portion 34, a coil portion 412 or 412a formed in an intermediate coil shape, and a lead-out portion 413 connected to the buffer tank 42. It is made by molding a metal pipe. The buffer tank 42 is manufactured by pressing or machining. Both are connected by joining, such as welding and brazing, and mechanical airtight connection methods, such as a metal seal.
The structure and operation of such a pulse tube refrigerator are disclosed in Patent Document 1 and Patent Document 2, for example.
JP 2002-206816 JP 2004-28501 A

As described above, the inertance tube 41 or 41a and the buffer tank 42, which are the phase control mechanism 4 of the pulse tube refrigerator according to the prior art, are manufactured separately from the other components and incorporated into the pulse tube refrigerator. In the case of the inertance tube 41 shown in FIG. 3, since the introduction part 411, the coil part 412 and the lead-out part 413 occupy spaces, the space occupied by the pulse tube refrigerator is large. To reduce the space, when the coil portion 412a of the inertance tube 41a is wound around the outer periphery of the case 14 of the compressor 1 as shown in FIG. 4, vibration from the compressor 1 interferes with the coil portion 412a. The inertance tube 41a may vibrate abnormally to generate abnormal noise.
Further, as described above, working gas having a pressure of about 1 to 3 MPa is also enclosed in the inertance tube 41 or 41a, and this inerting pressure and the compressor 1 are generated in the inertance tube 41 or 41a. Since the internal pressure is the sum of the operating pressures associated with the pressure vibrations, the strength required to withstand this pressure is required, and metal-made thick tubes are used. For this reason, it is difficult to form the inertance tube, and the material cost and the processing cost are high. The buffer tank 42 is the same, and its cost is high.

  An object of the present invention is to provide a phase control mechanism for a pulse tube refrigerator that is free from vibration and that is inexpensive, small and light, eliminating the above problems.

This invention is based on the fact that the amplitude of the pressure applied as compression and expansion to the working gas by the compressor is much smaller than the sealed pressure of the working gas sealed inside the pulse tube refrigerator. Inspired. That is, as described above, the working gas sealing pressure is about 1 to 3 MPa, which is 10 to 30 times the atmospheric pressure, whereas the pressure applied to the working gas by the compressor is the position inside the pulse tube refrigerator. The difference in pressure due to the pressure is as small as one-tenth of the enclosed pressure, so if you can replace part of the part that receives atmospheric pressure outside with a state that receives only this pressure difference, that part is necessary This is based on the idea that the pressure resistance can be greatly reduced.
The invention of claim 1 is a phase control mechanism of a pulse tube refrigerator that cools a predetermined portion of the flow path of the working gas to a cryogenic temperature by repeated compression and expansion of the sealed working gas by the compressor. At least a part of the inertance tube and the inertance tube in the buffer tank, which are components of the control mechanism, are fixedly housed inside the buffer tank.

The portion of the inertance tube stored inside the buffer tank receives the pressure in the buffer tank from the outside, so the difference in internal and external pressure of the pipe in that part is greatly reduced, and the thickness of the pipe in that part is greatly increased. Can be thinned. Further, since a clean inert gas such as helium is used as the working gas, the inertance tube portion housed in the buffer tank does not require corrosion resistance or rust prevention treatment. Furthermore, since the buffer tank is fixed and stored, the vibration of the inertance tube is suppressed.
According to a second aspect of the present invention, in the first aspect of the invention, the portion of the inertance tube that is fixedly housed inside the buffer tank is made of resin.
As described in the invention of claim 1, the portion of the inertance tube that is fixedly accommodated inside the buffer tank greatly reduces the difference between the internal and external pressures of the tube. It will be possible to adopt.

According to a third aspect of the invention, there is provided the buffer tank according to the first aspect of the invention, wherein the buffer tank is integrated with a case of the compressor.
By integrating the buffer tank with the compressor case, the number of parts can be reduced. Further, since the pressure difference received between the partition wall and the compressor case is small, the partition wall can be made into a thin partition wall having a suitable strength.

In the first aspect of the present invention, at least a part of the inertance tube is fixedly housed inside the buffer tank, so that the portion of the inertance tube housed in the buffer tank is made thinner. The portion does not require corrosion resistance or rust prevention treatment, and requires less space, and the vibration of the inertance tube can be suppressed by the effect of fixing the portion. Therefore, according to the present invention, it is possible to provide a phase control mechanism for a pulse tube refrigerator that does not vibrate and is inexpensive and small and light.
In the invention of claim 2, the portion of the inertance tube that is fixedly housed inside the buffer tank is made of resin. As described in the first aspect of the present invention, since the internal / external pressure difference of the pipe is greatly reduced, a resin pipe with less outgas can be adopted as the material due to the effect. Therefore, according to this invention, the cost of the phase control mechanism of the pulse tube refrigerator can be further reduced.

  According to a third aspect of the present invention, a buffer tank integrated with a compressor case is provided as a buffer tank. By integrating the buffer tank with the compressor case, the number of parts can be reduced. Further, since the pressure difference received between the partition wall and the compressor case is small, the partition wall can be made into a thin partition wall having a suitable strength. Therefore, according to this invention, the cost and weight of the phase control mechanism of the pulse tube refrigerator can be further reduced.

The best mode for carrying out the present invention will be described with reference to examples.
In addition, the same code | symbol is attached | subjected to the part of the same function as a prior art.

FIG. 1 shows the configuration of a first embodiment of a phase control mechanism of a pulse tube refrigerator according to the present invention, where (a) is a conceptual diagram of the entire refrigerator, and (b) is a conceptual diagram of a coil portion of the inertance tube. is there.
Since the pulse tube refrigerator using this embodiment has the same configuration as the conventional example except for the phase control mechanism 4a, only the phase control mechanism 4a will be described, and the description of the other parts will be omitted.
The phase control mechanism 4a of this embodiment is integrated so that the inertance tube 41b including the introduction portion 411 and the coil portion 412b, the fixture 414 that integrally fixes the coil portion 41b, and the fixture 414 do not vibrate. And a buffer tank 42a having a built-in coil portion 41b. The introduction part 411 of the inertance tube 41b is made of the same material as the conventional example (thick material having corrosion resistance: for example, a stainless steel pipe or a nickel-plated copper pipe), but the coil part 412b is cleaned cleanly. Made of degassed thin copper pipe. The reason why the coil portion 412b can be manufactured with a thin copper pipe is that the pressure difference between the inside and outside of the pipe is small because it is accommodated in the buffer tank 42a as described in the section “Means for Solving the Problems”. This is because the atmosphere becomes a clean inert gas atmosphere. The coil portion 412b integrated by the fixing tool 414 is fixed to the inside of the buffer tank 42a by press-fitting or partial welding. The end of the coil portion 412b is opened in the buffer tank 42a, and the inertance tube 41b of this embodiment does not have a lead-out portion as in the conventional example.

According to this embodiment, the coil portion 412b occupying most of the length of the inertance tube 41b can be made of a thin copper tube that is easy to mold and has no plating, and the coil portion 412b is made of the buffer tank 42a. Therefore, material costs and processing costs can be reduced, and the size and weight can be reduced. Furthermore, since the coil portion 412b is integrated and fixed, the inertance tube 41b does not vibrate.
In the above description, the coil portion 412b is made of a thin copper tube, but it may be a resin tube with little outgas, such as a Teflon (registered trademark) tube. In the case where the coil portion 412b is a resin pipe, the molding process is simplified and the number of assembly steps is reduced, so that the cost can be further reduced.

2A and 2B show a configuration of a phase control mechanism of a pulse tube refrigerator according to a second embodiment of the present invention, in which FIG. 2A is a conceptual diagram of the entire refrigerator, and FIG. 2B is a diagram of a coil portion of the buffer tank and inertance tube. It is a conceptual diagram which shows a structure.
In this embodiment, the compressor case and the buffer tank are integrated, and the coil portion of the inertance tube is fixed and accommodated in the buffer tank as in the first embodiment.
The case 15 of this embodiment has a structure in which the buffer tank 42b is integrated with the side surface of the case of the compressor 1, and the partition 15 is partitioned between the two. The coil portion 412c is housed and fixed in a hollow donut-shaped fixing tool 414a, and the fixing tool 414a is fixed to the case 15 by partial welding.

  In this embodiment, in addition to the same effects as in the first embodiment, the compressor case and the buffer tank are integrated, so that the number of parts is reduced, the overall configuration is further simplified, and at the same time, the partition 151 Therefore, the partition 151 can be made thin. As a result, this embodiment is further reduced in size and weight than the first embodiment.

The structure of Example 1 of the phase control mechanism of the pulse tube refrigerator by this invention is shown, (a) is a conceptual diagram of the whole refrigerator, (b) is a conceptual diagram of the coil part of the inertance tube The structure of Example 2 of the phase control mechanism of the pulse tube refrigerator by this invention is shown, (a) is a conceptual diagram of the whole refrigerator, (b) is the concept which shows the structure of the coil part of the buffer tank and inertance tube Figure Conceptual diagram of the entire refrigerator showing the configuration of an example of a phase control mechanism of a pulse tube refrigerator according to the prior art Partial conceptual view of the vicinity of the compressor showing the configuration of another example of the phase control mechanism of a pulse tube refrigerator according to the prior art

Explanation of symbols

1 Compressor
11 Motor 12 Piston
13 Cylinder 14 Case
15 Case 151 Partition 2 High-temperature side heat exchanger 3 Expander
31 Regenerator 32 Cold end
33 Pulse tube (Pulse tube) 34 High temperature end 4, 4a, 4b Phase control mechanism
41, 41a, 41b, 41c inertance tube
411 Introduction
412, 412a, 412b, 412c Coil section
413 Deriving part
414, 414a Fixing tool
42, 42a, 42b Buffer tank

Claims (3)

A phase control mechanism of a pulse tube refrigerator that cools a predetermined portion of a flow path of a working gas to a cryogenic temperature by repeated compression and expansion of the enclosed working gas by a compressor,
The inertance tube as a component of the phase control mechanism and at least a part of the inertance tube in the buffer tank are fixedly accommodated inside the buffer tank,
A phase control mechanism of a pulse tube refrigerator characterized by that. The portion of the inertance tube fixed and accommodated inside the buffer tank is made of resin,
The phase control mechanism of the pulse tube refrigerator according to claim 1. A buffer tank integrated with the compressor case as the buffer tank;
The phase control mechanism of the pulse tube refrigerator according to claim 1.

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