JP2000161801A - Pulse pipe refrigerating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress temperature increase at a low-temperature end by providing a porous plate in a pulse pipe and preventing a working medium being discharged into the pulse pipe from directly reaching the low-temperature end in a refrigerating machine with cold storage equipment for exchanging heat with the working medium that is transported between a compressor and the pulse pipe. SOLUTION: A working medium from a compressor 1 flows into cold stage equipment 3 through a high-pressure valve 2a, then flows into a pulse pipe 4, and then pushes the working medium already existing in the pulse pipe 4 toward a high-temperature end 41. Then, although the working medium passes through an orifice 6 and flows into a middle pressure chamber 7, compression heat being generated at the high-temperature end 41 of the pulse pipe 4 is emitted to the outside by a cooling fin 8. After that, when the high-pressure valve 2a is closed and the low-pressure valve 2b is opened, the working medium in the middle pressure chamber 7 momentarily passes through the orifice 6 and then flows into the pulse pipe 4. However, since a porous plate 43 is provided in the pulse pipe 4, the high-pressure gas cannot reach the low-temperature end 42 of the pulse pipe 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a pulse tube refrigerator. The pulse tube refrigerator has no moving parts in the low-temperature part, has a simple structure, and has a relatively low temperature. For this reason,
The application as a refrigerator with little vibration is expected. In addition, since the contaminants such as outgas do not adhere to the movable portion and hinder the movement, the life can be easily extended.

[0002]

2. Description of the Related Art The construction and operating principle of a conventional orifice type pulse tube refrigerator will be described with reference to FIG.

FIG. 7 is a schematic sectional view of a conventional orifice type pulse tube refrigerator. A discharge port and a suction port of the compressor 1 are connected to a high temperature end 31 of the regenerator 3 via a high pressure side valve 2a and a low pressure side valve 2b, respectively. The compressor 1 repeats discharge and suction of a working gas such as He. The arrows in the figure indicate the direction of the gas flow. When the high pressure side valve 2 a is opened and the low pressure side valve 2 b is closed, the compressed working gas is introduced into the regenerator 3. Close the high pressure side valve 2a,
When the low-pressure side valve 2b is opened, working gas is sucked from the regenerator 3 into the compressor 1.

[0004] Inside the regenerator 3, a flow path of a working gas is defined, and the flow path is filled with a regenerator material such as a wire mesh. The low temperature end 32 of the regenerator 3 communicates with the low temperature end 42 of the pulse tube 4 via the cooling passage 5. A cavity into which the working gas flows is defined in the pulse tube 4. The high-temperature end 41 of the pulse tube 4 is connected to the intermediate pressure chamber 7 via an orifice 6 for adjusting the flow rate of the working fluid.

[0005] The high-pressure working gas compressed by the compressor 1 is:
Passing through the regenerator 3 through the open high pressure side valve 2a,
It flows into the pulse tube 4. The working gas exchanges heat with the cold storage material when passing through the regenerator 3. When the working gas flows into the pulse tube 4, the working gas already existing in the pulse tube 4 is pushed by the newly flowing working gas and moves toward the high temperature end 41.

As a result, the pressure in the pulse tube 4 becomes higher than the pressure in the intermediate pressure chamber 7, and the working gas flows into the intermediate pressure chamber 7 through the orifice 6. At this time, heat of compression is generated at the high temperature end 41 of the pulse tube 4. This heat of compression is radiated to the outside by radiation fins 8 provided around the high temperature end 41 of the pulse tube 4.

Next, the high pressure side valve 2a is closed and the low pressure side valve 2b is opened. The working gas in the pulse tube 4
, And the temperature rises while cooling the wire mesh inside the regenerator 3, and returns to the suction port of the compressor 1. On this occasion,
The working gas in the intermediate pressure chamber 7 momentarily flows into the pulse tube 4 through the orifice 6.

Although the reason why the flow of the working gas causes the cold is not clear, it is considered that the cold accompanying the expansion of the working gas occurs at the low temperature end 42 of the pulse tube 4. As the generation of cold due to the expansion of the differential gas is repeated, the object to be cooled in contact with the cooling passage 5 is cooled.

[0009]

The orifice type pulse tube refrigerator is inferior to other refrigerators, such as a GM refrigerator, in terms of cooling efficiency. One of the causes of poor cooling efficiency is as follows. That is, when the returning hot working gas from the intermediate pressure chamber 7 passes through the orifice 6 and flows into the pulse tube 4, the working gas gushes out into the pulse tube 4. The ejected working gas penetrates through the working gas staying in the pulse tube 4 and reaches near the low temperature end 42. It is considered that the high temperature working gas that has reached the vicinity of the low temperature end 42 raises the temperature of the low temperature end 42.

In order to prevent such a phenomenon, according to the invention described in Japanese Patent Application Laid-Open No. 9-113051, a stopper member 9 and a moving member 1 are provided in a pulse tube 4 as shown in FIG.
0 is provided to buffer the return of the working gas from the intermediate pressure chamber 7. However, in the structure as shown in FIG. 8, since the moving member 10 exists in the pulse tube 4, the original feature and advantage of the pulse tube refrigerator having no movable portion are lost.

An object of the present invention is to provide a pulse tube refrigerator capable of increasing the cooling efficiency.

[0012]

According to one aspect of the present invention, a compressor for repeatedly supplying and recovering a working gas, a pulse tube defining a cavity therein, and one end of the compressor and one end of the pulse tube are provided. A regenerator connected between the compressor and the pulse tube for transporting the working gas and performing heat exchange with the transported working gas; an intermediate pressure chamber defining an internal cavity of a certain volume; A gas passage connected between the pressure chamber and the other end of the pulse tube, communicating the internal cavity of the intermediate pressure chamber with the internal cavity of the pulse tube, and having a flow path resistance to a working gas passing therethrough; And, in the internal cavity of the pulse tube, the differential gas flowing from the intermediate pressure chamber into the pulse tube is arranged at a position where the differential gas collides, and a plurality of through holes through which the working gas can pass are dispersed over the entire surface. A pulse tube refrigerator having a perforated plate is provided.

[0013] When the differential gas ejected from the intermediate pressure chamber into the pulse tube collides with the perforated plate, it is possible to prevent the high-temperature working gas from directly reaching the low-temperature end of the pulse tube. For this reason, the temperature rise at the low temperature end can be suppressed, and the refrigeration performance can be improved.

[0014]

FIG. 1 is a schematic sectional view of an orifice type pulse tube refrigerator according to an embodiment of the present invention. The basic configurations of the compressor 1, the regenerator 3, the pulse tube 4, and the intermediate pressure chamber 7 are the same as those of the conventional pulse tube refrigerator shown in FIG. Each component of the pulse tube refrigerator of FIG. 1 is assigned the same reference numeral as the corresponding component of the pulse tube refrigerator of FIG.

In the embodiment shown in FIG.
A perforated plate 43 is arranged near the high temperature end 41 of the inner cavity. The regenerator 3, cooling passage 5, and pulse tube 4
Is installed in a vacuum vessel for thermal insulation from the outside.

The porous plate 43 is formed by forming a large number of through holes having a predetermined diameter on a thin plate having a thickness of about 0.5 mm made of Al, stainless steel, Cu, resin or the like. These through holes are distributed almost uniformly over the entire surface of the thin plate. Various shapes can be considered for the shape of each hole, including a circle. Also, it may be a mesh.

FIG. 2 is a detailed sectional view of a mounting portion of the perforated plate 43 and the orifice 6. A pulse tube is constituted by the cylindrical member 4a and the perforated plate fixing member 4b. The cylindrical member 4a is provided with a through hole 11 provided in a wall of the vacuum vessel 11.
a is inserted from the vacuum side and fixed. A perforated plate fixing member 4b is attached to the outside of the vacuum vessel 11 so as to close the through hole 11a. A cavity 4c is formed in the perforated plate fixing member 4b. The cavity 4c has an opening on the surface of the perforated plate fixing member 4b facing the vacuum vessel 11. The opening of the cavity 4c is aligned with the through hole 11a. An orifice 6 is attached to the opening on the opposite side of the cavity 4c. The cavity 4 c communicates with the internal cavity of the intermediate pressure chamber 7 via the orifice 6.

The perforated plate 43 is fixed between the perforated plate fixing member 4b and the vacuum vessel 11. A step is formed along the circumference surrounding the opening of the cavity 4c. The perforated plate 43 is arranged at this step. The space between the porous plate 43 and the vacuum vessel 11 is kept airtight by an O-ring. Further, by elastically deforming the O-ring, the perforated plate 4
Position 3 is fixed.

FIG. 3A shows an example of the perforated plate 43.
A large number of through holes 44 having a diameter of about 0.5 mm are formed in the thin plate. Each through hole 44 is arranged at a position corresponding to the intersection of the lattice pattern. The aperture ratio is about 25%. Here, the opening ratio means the ratio of the total area of the openings of the holes to the total area of the thin plate. FIG. 3B shows a perforated plate 43.
Here is another example. Numerous through holes 44 with a diameter of about 0.7 mm
Are formed. Each through hole 44 is arranged at a position corresponding to an intersection when two sets of stripes cross each other at 60 °. The aperture ratio is about 50%.

FIG. 4 shows a result of a refrigerating performance test of the pulse tube refrigerator according to the embodiment. The refrigerator was operated while the low temperature part of the refrigerator was forcibly heated by the heater, and the ultimate temperature at the low temperature end was measured. The horizontal axis in FIG. 3 represents the refrigerating capacity of the refrigerator (corresponding to the power supplied to the heater) in units of “W”, and the vertical axis represents the temperature at the low temperature end in absolute temperature. The black circle symbols in the figure indicate the refrigerating performance of the pulse tube refrigerator according to the embodiment. For comparison, the refrigeration performance when the perforated plate 43 of FIG. 1 is not arranged is indicated by white circle symbols. The pulse tube refrigerator used in the test had a pulse tube having a diameter of 20 mm, a length of 200 mm, and an orifice diameter of 0.5 mm. The perforated plate used is that shown in FIG. The pulse tube refrigerator according to the embodiment has a higher refrigerating performance than a refrigerator without a perforated plate.

FIG. 5 is a graph showing the result of measuring how the refrigerating performance changes depending on the installation position of the perforated plate 43. The horizontal axis in FIG. 5 represents the distance L from the end of the orifice 6 on the pulse tube side shown in FIG.
m ", and the vertical axis represents the lowest attainable temperature in absolute temperature. When the distance L from the orifice was in the range of 15 mm to 25 mm, relatively high refrigeration performance was obtained.

FIG. 6 is a graph showing the results of measuring the difference in refrigeration performance due to the difference in the arrangement of the through holes in the perforated plate.
The horizontal axis in FIG. 6 represents the heat load applied to the low temperature end of the pulse tube refrigerator in W, and the vertical axis represents the temperature at the low temperature end in absolute temperature. The black circle symbol in the figure indicates the case where the perforated plate shown in FIG. A white circle symbol indicates a case where a perforated plate shown in FIG. 3A whose central portion is covered with a tape is used. The area of the area covered with tape is about 60
%.

When a perforated plate covered with a tape is mounted, the refrigerating performance is worse than when a perforated plate having a through hole formed on the entire surface is mounted. This cause is considered as follows.

When the holes of the perforated plate are uniformly distributed over the entire plate surface, the flow of the working gas is less likely to be disturbed. On the other hand, when the holes are unevenly distributed in a specific portion such as the peripheral portion of the plate, such as when the holes are closed with a tape, a turbulent flow occurs in the working gas. It is considered that the refrigeration performance is reduced due to the turbulence. Therefore, it is preferable that the through holes formed in the perforated plate are uniformly distributed on the plate surface.

In the above embodiment, each hole 44 of the perforated plate 43
Are 0.5 mm and 0.7 mm in diameter, but a polyhedron provided with through holes of other diameters may be used. The preferred range of the caliber is 0.2-0.7 mm, the more preferred range is 0.4 m
m to 0.8 mm. The preferred range of the aperture ratio is:
25 to 50%.

The present invention has been described in connection with the preferred embodiments.
The present invention is not limited to these. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0027]

As described above, according to the present invention,
The working gas ejected from the intermediate pressure chamber into the pulse tube collides with the perforated plate. Therefore, it is possible to prevent the high-temperature differential gas from directly reaching the low-temperature end. Thereby, the refrigeration efficiency can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic view of an orifice type pulse tube refrigerator according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a perforated plate mounting portion of the pulse tube refrigerator shown in FIG.

FIG. 3 is a plan view of a perforated plate mounted on a pulse tube of an orifice type pulse tube refrigerator according to an embodiment of the present invention.

FIG. 4 is a graph showing the refrigerating performance of the orifice type pulse tube refrigerator according to the embodiment of the present invention.

FIG. 5 is a graph showing a change in an attained temperature depending on a position of a perforated plate of an orifice type pulse tube refrigerator according to an embodiment of the present invention.

FIG. 6 is a graph showing a difference in refrigeration performance depending on an arrangement of holes in a perforated plate of an orifice type pulse tube refrigerator according to an embodiment of the present invention.

FIG. 7 is a schematic view of an orifice type pulse tube refrigerator according to a conventional example.

FIG. 8 is a schematic view of an orifice type pulse tube refrigerator according to another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor 2a, 2b High pressure side, low pressure side valve 3 Regenerator 4 Pulse tube 5 Cooling passage 6 Orifice 7 Intermediate pressure chamber 8 Radiation fin 9 Stopper member 10 Moving member 11 Vacuum container 31, 41 High temperature end 32, 42 Low temperature end 43 Perforated plate 44 Through hole

Claims (4)

[Claims] A compressor that repeats supply and recovery of a working gas; a pulse tube that defines a cavity therein; a compressor connected to one end of the pulse tube; A regenerator that transports the working gas between and exchanges heat with the transported working gas; an intermediate pressure chamber that defines an internal cavity of a certain volume; and between the intermediate pressure chamber and the other end of the pulse tube. Connected to
A gas flow path that communicates the internal cavity of the intermediate pressure chamber with the internal cavity of the pulse tube, and has a flow path resistance to a working gas passing therethrough; and, within the internal cavity of the pulse tube, the intermediate pressure chamber And a perforated plate in which a plurality of through-holes through which a working gas can pass are dispersed over the entire surface of the pulse tube refrigerator. 2. A plurality of through holes of the perforated plate each have a diameter in a range of 0.4 mm to 0.8 mm, and an opening ratio of a total opening area of the plurality of through holes to an area of the perforated plate is 25. The pulse tube refrigerator according to claim 1, wherein the range is from 50% to 50%. 3. The pulse tube refrigerator according to claim 2, wherein a distance from a connection point between the gas flow path and the pulse tube to the perforated plate is 5 to 20 mm. 4. The pulse tube refrigerator according to claim 1, wherein the through holes formed in the perforated plate are substantially uniformly dispersed on the surface of the perforated plate.