JP2627307B2 - Cryogenic expander - Google Patents

Description

The present invention relates to an improvement of a cryogenic expander using a gas cycle such as a Gifford McMahon cycle or a Solvay cycle.

(B) Conventional technology A conventional cryogenic expander is configured, for example, as disclosed in Japanese Patent Publication No. 45-4787. Here, a conventional example will be described with reference to this publication. 5 to 7, reference numeral 50 denotes a compressor for pressurizing a low-pressure refrigerant, and reference numerals 51 and 52 each have an intake valve 53 or an exhaust valve 54, and supply air for communicating the compressor 50 with the heat storage material 55. Pipe and exhaust pipe. Reference numeral 56 denotes a cylinder having a displacer 58 driven by a crank mechanism 57. The expansion space 59 is formed by the movement of the displacer, and the expansion space communicates with the heat storage material 55 by a pipe 60. The crank mechanism 57 for driving the displacer 58 is linked with the air supply valve 53 and the exhaust valve 54. The air supply valve 53 opens when the displacer 58 reaches the bottom dead center, and immediately before reaching the top dead center. Close to. Exhaust valve 54
Opens when the displacer 58 reaches its top dead center and closes when it reaches its bottom dead center. Reference numeral 61 denotes a load heat exchanger which is attached to a pipe 60 so as to cool an object to be cooled.

In the cryogenic expander of this structure, the refrigerant compressed by the compressor 50 is guided from the air supply valve 53 to the heat storage material 55, and the refrigerant precooled by the heat storage material is adiabatically expanded in the expansion space 59 and cooled by itself. When the exhaust valve 54 is opened, the load heat exchanger 61 is cooled by the refrigerant flowing from the expansion space 59 to the heat storage material 55, so that the object to be cooled is cooled to an extremely low temperature.

(C) Problems to be Solved by the Invention However, in the conventional heat storage material 55, since granular lead is sandwiched between brass or copper wire meshes 62, 62 having low elastic strength via felts 63, 63, the compressor is a compressor. Deformation and abrasion of lead occur due to vibrations and coolant flow caused by the operation of 50, and granular lead with a widened gap becomes easy to move, causing lead to adhere to each other and reduce the heat exchange area. However, there has been a problem that the refrigerant pressure loss increases and the refrigerating capacity decreases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to make it difficult for granular lead filled in a space in a displacer to adhere.

It is another object of the present invention to prevent the surfaces of the granular lead from contacting each other.

(D) Means for Solving the Problems In the present invention, the surface of granular lead which is filled in a displacer to form a heat storage material is made of a material having a different composition.

Further, in the present invention, a projection made of a material different from that of lead is provided on the surface of granular lead which is filled in the displacer to form a heat storage material.

(E) Operation The present invention is configured as described above to prevent the granular lead filled in the displacer from sticking together, and to reduce the heat exchange area of the heat storage material formed of the granular lead. It is intended to prevent the number from decreasing.

(F) Embodiment The present invention will be described below with reference to the embodiment shown in FIGS.

Reference numeral 1 denotes a compressor, to which a supply pipe 3 having a supply valve 2 and an exhaust pipe 5 having an exhaust valve 4 are connected. The supply pipe and the exhaust pipe are connected to a supply / exhaust port 8 provided on an upper wall 7 of the container 6 which is assembled and sealed. The container 6 is formed by a large-diameter first cylinder 9 and a small-diameter second cylinder 10. This first and second
A first displacer 12 and a second displacer 13 which reciprocate up and down by a shaft 11 connected to a driving device (not shown) are housed in the cylinder, and the displacer has a variable displacement. Buffer space 14, a first expansion space 15, and a second expansion space 16 are defined. Further, seal rings 17, 17 are attached to the outer periphery of the first and second displacers 12, 13, respectively. The buffer space 14 and the first and second expansion spaces 15 and 16 communicate with each other via a first space 18 in the first displacer 12 and a second space 19 in the second displacer 13. The first space 18 is filled with a heat storage material 20 formed of a copper wire mesh. The second space 19 is filled with a heat storage material 21 made of granular lead. Reference numerals 22 and 22 denote wire meshes provided on both sides in the second space 19, and the wire meshes sandwich the lead heat storage material 21 via felts 23 and 23. The granular lead forming the heat storage material has a half of its surface coated with a material having a low adhesion coefficient by plating, vapor deposition, sputtering, or the like to form a film 24 of a different material. This coating is formed of, for example, nickel, tungsten, titanium, or the like.

A load heat exchanger 26 for cooling an object to be cooled is attached to the bottom wall 25 of the second cylinder 10.

In the cryogenic expander configured as described above, the working refrigerant pressurized by the compressor 1 is supplied to the first and second displacers 12, 13 by the first and second displacers 12, 13 in the first and second cylinders 9, 10. 2 When the expansion space 15, 16 is at the lowest position (top dead center), the air supply valve 2
Is opened, the exhaust valve 4 is closed, and flows into the buffer space 14 from the air supply pipe 3. In the process of moving the first and second displacers 12, 13 from the expansion spaces 15, 16 to the buffer space 14, the working refrigerant in the buffer space 14 transfers the heat storage material 20 in the first space 18 of the first displacer 12. While flowing into the first expansion space 15 while being pre-cooled, the second expansion space while being pre-cooled by the heat storage materials 20 and 21 of the first and second spaces 18 and 19 of the first and second displacers 12 and 13. Flow into 16.
Thereafter, when the first displacer 12 reaches the uppermost position (bottom dead center) on the buffer space 14 side in the first cylinder 9,
When the air supply valve 2 is closed and the exhaust valve 4 is opened, the working refrigerant is
-It expands in the second expansion spaces 15 and 16 and is cooled by itself. Again, in the process in which the first and second displacers 12 and 13 move from the buffer space 14 to the first and second expansion spaces 15 and 16, the working refrigerant in the first and second expansion spaces 15 and 16 becomes the first and second expansion spaces 15 and 16. After cooling the heat storage materials 20 and 21 of the second displacers 12 and 13 respectively, the heat storage materials 20 and 21 pass through the buffer space 14 and return to the compressor 1 from the exhaust pipe 5. Thereafter, the load heat exchanger 26 on the bottom wall 25 of the second cylinder 10 is repeatedly cooled to an extremely low temperature.

The heat storage material 21 for pre-cooling the working refrigerant that cools the load heat exchanger 26 to a low temperature has a surface in contact with one another by coating a coating 24 with a material different from the material of lead on half of the surface of granular lead. Are less likely to be the same, and are less likely to adhere. The heat storage material is designed so that even if the same material adheres to each other, the heat storage material does not become a small mass. Therefore, the heat storage material 21 is prevented from decreasing the heat exchange area of the granular lead, and preventing the refrigerant capacity from decreasing.

According to the present invention, a half of the surface of the heat storage material 21 formed of granular lead is coated with a substance different in material from lead, thereby reducing the probability that the material in contact with the granular lead becomes the same, and condensing with the same substance. In addition to reducing the adhesion, it prevents the granular lead from becoming a large lump.

In the above description, half of the surfaces of the granular lead heat storage material 21 are coated with a material different from the material of the lead to reduce the probability that adjacent granular lead surfaces come into contact with the same material. Although it has been described that it is difficult to attach, as shown in FIG. 4, a protrusion 27 different from the material of the lead is provided on the surface of the granular lead, and the lead prevents the lead from coming into contact with each other. It goes without saying that a similar effect can be obtained even if the movement of the granular lead is restricted.

(G) Effects of the Invention Since the cryogenic expander of the present invention uses a material of a different composition for the surface of the granular lead which is filled in the displacer to form the heat storage material, the surface of the granular lead By reducing the probability that the same materials come into contact with each other, it is possible to prevent the granular lead from sticking and prevent the refrigerating capacity from being reduced.

Further, in the present invention, since a projection different from the material of this lead is provided on the surface of the granular lead forming the heat storage material,
By contacting this protrusion with the surface of other lead, it is possible to prevent the granular lead from contacting and sticking together, and to reduce the heat exchange area of the heat storage material and prevent the refrigeration capacity from decreasing. It is.

[Brief description of the drawings]

1 to 3 show the present invention, FIG. 1 is a cross-sectional view schematically showing a cryogenic expander, FIG. 2 is a cross-sectional view of a schematic regenerator, and FIG. FIG. 4 is an enlarged sectional view showing a state of filling with granular lead to be formed, FIG. 4 is an enlarged plan view of granular lead showing another embodiment, FIGS. 5 to 7 show a conventional example, and FIG. FIG. 6 is a schematic cross-sectional view of a low-temperature expander, FIG. 6 is a schematic cross-sectional view of a heat storage device, and FIG. 7 is an enlarged plan view showing a state of filling of granular lead forming a heat storage material. 9 first cylinder, 10 second cylinder, 12 first
Displacer, 13 ... Second displacer, 14 ...
... buffer space, 15 ... first expansion space, 16 ... second expansion space, 20, 21 ... heat storage material, 24 ... coating, 27 ... projection.

Claims (6)

(57) [Claims] 1. A cylinder, a displacer sliding back and forth in the cylinder, a buffer space and an expansion space defined inside the cylinder by the displacer, and a display communicating the buffer space and the expansion space. A cryogenic expander comprising a granular lead heat storage material filled in the interior of a sir, wherein the heat storage material has a granular lead surface made of a material having a different composition. . 2. The cryogenic expander according to claim 1, wherein a different material is coated on the surface of the granular lead. 3. The cryogenic expander according to claim 2, wherein the coating material is nickel, titanium, tungsten or the like. 4. A cylinder, a displacer reciprocatingly sliding in the cylinder, a buffer space and an expansion space defined inside the cylinder by the displacer, and a display communicating the buffer space and the expansion space. In a cryogenic expander comprising a granular lead heat storage material filled in the interior of a sir, the heat storage material is provided with a projection made of a material different from that of the lead on the surface of the granular lead. Cryogenic expander. 5. An expander for cryogenic use according to claim 4, wherein particles of a different material smaller than the lead are attached to the surface of the granular lead. 6. The cryogenic expander according to claim 5, wherein the particles to be attached to the surface of the lead are formed of a low-adhesion substance such as nickel, titanium and tungsten.