JPH0566511B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cryogenic refrigeration device applicable to cryopumps, He liquefaction devices, and the like.

[Prior Art] Conventionally, this type of refrigeration equipment has a piston-shaped displacer slidably fitted in a cylinder, and the displacer is reciprocated to reduce the low temperature between the displacer and the cylinder. The volume of the expansion chamber formed between the end and the end can be increased or decreased, and by expanding or contracting the expansion chamber, the gas can be expanded in sequence to run a predetermined refrigeration cycle.

By the way, there are conventional types in which the regenerator is held inside the displacer and types in which it is disposed outside the cylinder, but both have the following problems. . That is, a displacer in which a regenerator is provided has a disadvantage in that the inertial mass of the movable part is large and vibrations are likely to occur. Further, in the case where the regenerator is provided outside the cylinder (including the outer circumferential surface of the cylinder wall), there is a problem that there is a wasted volume inside the displacer, and the bulk of the entire device increases. Furthermore, various mechanisms have been devised to control the movement of this displacer, but each of them increases the number of gas seals and adds complicated moving parts, making the device complicated. was.

In order to eliminate such inconveniences, the cryogenic refrigeration equipment is equipped with an internal regenerator supported by a fixed member,
a movable shell that is slidably fitted around the outer periphery of the regenerator and forms an internal expansion chamber between the low temperature end of the regenerator and the low temperature end of the regenerator; an external regenerator; a casing that is provided to surround the external regenerator and forms an external expansion chamber between the low temperature end of the external regenerator and the movable shell; It has been considered to include a timing valve that connects to the air supply system path or the exhaust system path at a preset timing. If it's something like this,
Since the pressure of the cooling gas can be used to slide the working shell, there is no need for a drive unit and the structure is simple.In addition, the working shell can undergo two adiabatic expansions per reciprocation, so it can be made larger for the same size. It has the advantage of providing refrigeration capacity.

However, such a method also has the following disadvantages. That is, unless the regenerator uses a material such as GdRh, which is not easily available, the specific heat (cold storage capacity) will drop sharply at temperatures above 15 K due to the Debye temperature. As a result, it was extremely difficult for conventional refrigeration equipment to lower the temperature to about the liquid He temperature (4.2 K) required for use in SQUIDs and the like. Therefore, it is difficult to achieve an extremely low temperature of about 4.2K using only a gas cycle system using a regenerator.

[Problems to be Solved by the Invention] The present invention has been made by focusing on the above-mentioned circumstances, and even in a gas cycle system using a regenerator, it is possible to reduce the He liquefaction temperature without complicating the structure. The purpose of the present invention is to provide a cryogenic refrigeration device that can realize the following.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a cryogenic refrigeration system consisting of multiple stages, and includes an internal regenerator disposed from one stage and supported by a fixed member; An internal expansion chamber is formed between a spacer disposed at the final stage and fixedly supported, and a low temperature end of the internal regenerator that is slidably fitted around the outer periphery of the internal regenerator, and the final stage is connected to the spacer. A hollow movable shell that is slidably disposed on the outer periphery of the movable shell via a gas passage and forms a final internal expansion chamber between the low-temperature side end of the shell and the spacer, and the outer periphery of the movable shell except for the final stage. An external expansion chamber communicating with the external regenerator is formed between an external regenerator disposed in the regenerator and the movable shell provided to surround the regenerator, and the final stage is connected to the movable regenerator. a casing that surrounds the outer periphery of the final stage of the shell via a gas passage and forms a final external expansion chamber between the movable shell and the low temperature side end of the final stage; and a high temperature end of each of the first stage regenerators. and a timing valve that connects the air supply system to the air supply system path or the exhaust system path at a preset timing, and the gas that flows in and out of the final internal expansion chamber and the gas that flows in and out of the final external expansion chamber. It is characterized in that heat exchange can be performed between the two through the final stage of the movable shell.

[Function] According to such a configuration, as the movable shell reciprocates, the internal expansion chamber formed inside the movable shell and the external expansion chamber formed outside the movable shell alternately expand and contract. I will do it. Therefore, the high-pressure gas introduced into each internal expansion chamber from the air supply system path expands in this expansion chamber and becomes low temperature, while the high-pressure gas introduced from the air supply system path into the external expansion chamber It expands in this expansion chamber and becomes cold. Further, the expansion/contraction of the internal expansion chamber and the expansion/contraction of the external expansion chamber are out of phase by 180 degrees. Therefore, gas flows in opposite directions through the gas passage to the final internal expansion chamber and the gas passage to the final external expansion chamber, and at this time, heat exchange is performed through the final stage of the movable shell. . By the heat exchange, a cryogenic state of approximately the liquefaction temperature of He can be achieved in the final stage.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic longitudinal cross-sectional view of a small-sized cryogenic refrigerator according to the present invention, and 1 in the figure is a base serving as a fixing member. The base 1 has a pair of inlet and outlet ports 2 and 3. One of the inflow and outflow ports 2 is
A hole is provided in the center of the base 1, and a communication pipe 4 is airtightly fitted and fixed to the upper half of the inflow/outflow port 2. This communication pipe 4 extends upward, and a mounting disk 6 is attached to its upper end. A first stage internal regenerator 7 is placed and fixed on this mounting disc 6. This internal regenerator 7
is a structure in which heat storage elements and spacers are stacked alternately in multiple stages. The heat storage element is a disc-shaped element made of copper or the like, and has a large number of ventilation holes that pass through it vertically. The spacer is made of stainless steel wire or the like. The high temperature end (normal temperature end) 7a of this internal regenerator 7 communicates with the inflow/outflow port 2 via the port 6a bored in the mounting disc 6 and the communication pipe 4, and the port 6b. It communicates with the chamber 8 via. Further, the low temperature end 7b of the internal regenerator 7 is communicated with the high temperature end 11a of the second stage internal regenerator 11 via a communication path 9a formed in the mounting member 9.
This internal regenerator 11 is also fixed by stacking heat storage elements and spaces in multiple stages alternately. Furthermore, the low temperature end 11 of this second-stage internal regenerator 11
A spacer 13 is fixed to b via a mounting member 12. And these internal regenerators 7 and 11
The first stage and second stage of a hollow movable shell 14 are slidably fitted on the outer periphery of the spacer 13, and the final stage of the movable shell 14 is slidably disposed on the outer periphery of the spacer 13 via the gas passage 16. ing. That is, the movable shell 14 has a three-stage cylindrical shape, and its first-stage portion 14a surrounds the first-stage internal regenerator 7, and its second-stage portion 14b surrounds the second-stage internal regenerator 7. Eye internal regenerator 1
1, and further surrounds the spacer 13 via the gas passage 16 by a third or final stage portion 14c. Note that this gas passage 16 is connected to a port 12 formed in the mounting member 12.
It communicates with the low temperature end 11b of the regenerator 11 via a. A first-stage internal expansion chamber 17 is formed between the first-stage ceiling wall 14d of the movable shell 14 and the low-temperature end 7b of the first-stage internal regenerator 7, and the regenerator 7 and the attached They communicate through a communication path 9a and a communication hole 9b of the member 9. In addition, the ceiling wall 14e of the second stage portion 14b and the internal regenerator 1
A second stage internal expansion chamber 18 is formed between the low temperature end 11b of the first stage and the second stage internal expansion chamber 18. Further, a final internal expansion chamber 19 is formed between the low temperature side end of the spacer 13 and the top wall 14f of the final stage portion 14c. A shaft hole 14h is bored in the center of the bottom wall 14g at the end of the first stage of the movable shell 14 on the high temperature side. They are fitted so that they can slide through them. Also, a first stage external regenerator 23 held in a casing 22 around the outer periphery of the movable shell 14
A second stage external regenerator 24 is also provided. The casing 22 is cylindrical and has a plurality of stages, with a base portion 22a surrounding the external regenerator 23 and a first-stage portion 22b surrounding the external regenerator 24. A ceiling wall 22c is provided at the end on the low temperature side, and a ceiling wall 22d is provided at the end on the low temperature side of the first stage. The first stage external expansion chamber 26 is located between the high temperature end 24a of the second stage external regenerator 24 and the top wall 14d of the movable shell 14, and the top wall 22f of the second stage portion 22e of the casing 22. A second stage external expansion chamber 27 is formed between the movable shell 14 and the top wall 14e of the movable shell 14, respectively. Both of the external regenerators 23 and 24 are formed by stacking regenerator elements and spacers in multiple stages alternately. There is. The heat storage element is an annular element made of copper or the like, and has a large number of ventilation holes that pass through it vertically. The spacer is made of stainless steel wire or the like. Further, the third stage, that is, the final stage portion 22i of the casing 22 connects the outer periphery of the final stage 14c of the movable shell 14 to the gas passage 2.
The movable shell 14 is surrounded by a ceiling wall 22j via the movable shell 14
A final external expansion chamber 29 is formed between the final stage 14c and the low temperature side end of the final stage 14c.

Note that the high temperature end 23a of the first stage external regenerator 23
communicates with the inflow/outflow port 3 via the chamber 30. Also, the low temperature end 2 of this regenerator 23
3b communicates with the high temperature end 24a of the second stage external regenerator 24 via the external expansion chamber 26. The low temperature end 24b of this second stage external regenerator 24
is in communication with the external expansion chamber 27. Further, this external expansion chamber 27 communicates with a final external expansion chamber 29 via a gas passage 28.

Both the inflow and outflow ports 2 and 3 are connected to an air supply system path 32 or an exhaust system path 33 via a timing valve 31. Specifically, the timing valve 31 is composed of a slide valve or the like in which a port is operated by a motor to switch ports.
It is designed to switch in the manner shown by symbols in FIG. That is, at position A, one outflow/inflow port 2 is connected to the air supply system path 32, and the other outflow/inflow port 3 is connected to the exhaust system path 33. In addition, at position B, one of the inflow and outflow ports 2 is connected to the exhaust system path 33, and
The other inflow/outflow port 3 is connected to an air supply system path 32. The position A and the position B are alternately switched. The air supply line 32 is for supplying high pressure gas discharged from the outlet 34a of the compressor 34 to the air supply port 31a of the timing valve 31 through the cooler 35, and the exhaust line 33 is for supplying the high pressure gas discharged from the outlet 34a of the compressor 34 to the air supply port 31a of the timing valve 31 This is for guiding low pressure gas discharged from the exhaust port 31b of the timing valve 31 to the intake port 34b of the compressor 34.

Next, the operation of this embodiment will be explained.

The internal expansion chambers 17, 18, 19 are the smallest, and the external expansion chambers 26, 27, 29 are the largest (Fig. 1, Fig. 2 a)
(see), the timing valve 31 is set to position A to connect one inflow/outflow port 2 to the air supply system path 32 and connect the other outflow/inflow port 3 to the exhaust system path 33. As a result, high-pressure gas flows from the compressor 34 through the air supply system 32 to the one inflow/outflow port 2 . The high-pressure gas that has flowed into the inflow/outflow port 2 is guided to the high temperature end 7a of the first-stage internal regenerator 7 via the communication pipe 4 and port 6a, and the gas that has passed through the regenerator 7 is transferred to the mounting member 9. It is introduced into the first stage internal expansion chamber 17 via the communication path 9a and the communication hole 9b. Further, a part of the gas that has passed through this regenerator 7 is introduced into the second-stage internal regenerator 11 via the communication path 9a of the mounting member 9, and passes through the second-stage internal regenerator 11. and is introduced into the second-stage internal expansion chamber 18. Further, a part of the gas introduced into the second-stage internal expansion chamber 18 passes through the gas passage 16 and enters the final internal expansion chamber 19.
will be introduced to Further, a part of the high pressure gas introduced through the communication pipe 4 and the port 6a is also guided to the chamber 8 through the port 6b. In this state, the movable shell 14 is pressed upward by the high pressure gas in the internal expansion chambers 17, 18 and 19, while the pressure of the high pressure gas in the chamber 8 is forced downward. However, the pressure receiving area of the movable shell 14 for receiving the axial pressure component with respect to the expansion chambers 17, 18 and 19 is larger than the pressure receiving area of the movable shell 14 with respect to the axial direction pressure component of the chamber 8. Since the movable shell 14 is larger by an amount corresponding to the area (see FIG. 3a), the movable shell 14 is urged upward and moved by the difference (see FIG. 3a).
(see figure b). In this way, the internal expansion chamber 17,
When the volumes of 18 and 19 reach their maximum and are filled with high-pressure gas, the timing valve 31 is switched to position B, one of the inflow and outflow ports 2 is connected to the exhaust system path 33, and the other The inflow/outflow port 3 is communicated with the air supply line 32 (see FIG. 2c). As a result, the internal expansion chamber 1
Some of the gas in 7, 18 and 19 is in gas passage 1.
6. The air is blown out through the regenerators 11 and 7 and the communication pipe 4 into the exhaust system 33 and returned to the air intake port 34b of the compressor 34. At this time, the internal expansion chamber 1
The gases remaining in 7, 18 and 19 do the work of pushing out other gases and cool themselves. At this stage, since the timing valve 31 is held at position B as described above, the high pressure gas discharged from the compressor 34 flows into the other inflow/outflow port 3 through the air supply line 32. The high pressure gas flowing into the inflow/outflow port 3 is guided through the chamber 30 to the high temperature end 23a of the first stage external regenerator 23, and is introduced into the first stage external expansion chamber 26 through this regenerator 23. Further, a part of the gas introduced into the external expansion chamber 26 passes through the second-stage external regenerator 24 and passes through the second-stage external expansion chamber 27.
A portion of the gas is further introduced into the final external expansion chamber 29 via the gas passage 28. . In this state, the movable shell 14 is pressed downward by the high pressure gas in the external expansion chambers 26, 27 and 29, while the pressure of the high pressure gas in the chamber 30 pushes the movable shell 14 downward. is forced upward. However, the pressure receiving area of the movable shell 14 for receiving the axial pressure component for the external expansion chambers 26, 27, and 29 is larger than the pressure receiving area for receiving the axial pressure component for the chamber 30. (see FIG. 3b), and the movable shell is urged downward and moved by the difference (see FIG. 2d). At this time, the internal expansion chamber 17,
The low-temperature gas remaining in the movable shell 14 and the internal regenerator 1
1 and 7 while being cooled, and is pushed out to the exhaust system path 33. In this way, the external expansion chambers 26, 2
When the volumes of ports 7 and 29 reach their maximum and are filled with high-pressure gas, the timing valve 31 is switched to position A again, the other inflow/outflow port 3 is connected to the exhaust system path 33, and one The inlet/outlet port 2 of the air outlet 2 is communicated with the air supply line 32 (see FIG. 2a). As a result, a portion of the gas in the external expansion chambers 26, 27 and 29 passes through the gas passage 28 and the external regenerators 24 and 23 to the exhaust system path 3.
3 to the air intake port 34 of the compressor 34.
Returned to b. At this time, the external expansion chambers 26, 2
The gas remaining at 7 and 29 cools itself by pushing out other gases. At this stage, the high-pressure gas discharged from the compressor 34 is again supplied to one of the inflow and outflow ports 2, and is precooled while being precooled and transferred to the internal regenerators 7, 11 and the gas passage 1.
6 and is introduced into the internal expansion chambers 17, 18 and 19, and the movable shell 14 moves upward again. At this time, the external expansion chamber 26,
The low temperature gas remaining in 27 and 29 is transferred to the final stage portion 14c of the movable shell 14, the external regenerator 24,
23 while being cooled, and is pushed out to the exhaust system path 33. Therefore, by repeating the above operations, the Gifford-McMahon Cycle is carried out, and the upper end portion of the casing 22 becomes extremely cold.

In this way, it performs its freezing action,
This is the first stage portion 14a of the movable shell 14.
Expansion chambers 17 and 26 are provided on both upper and lower sides of the ceiling wall 14d, respectively, and the ceiling wall 1 of the second stage portion 14b is
Expansion chambers 18 and 27 are provided on both upper and lower sides of 4e, and the expansion chambers 17 and 27 are provided through different regenerators 7 and 23, respectively.
Gas is supplied to the expansion chambers 18 and 27 through the regenerators 11 and 24, respectively. Therefore, independent refrigeration cycles are operated using the expansion chambers 17, 18 and regenerators 7, 11, and the expansion chambers 26, 27 and regenerators 23, 24, respectively. Moreover, the expansion chamber 17,
18 and the expansion chambers 26 and 27 alternately expand and contract due to the reciprocating motion of the movable shell 14, so that the expansion operation can be performed twice for each reciprocating motion of the movable shell 14, and the same frequency If so, the refrigeration capacity can be approximately doubled compared to conventional ones.

Further, the final stage is provided with a final internal expansion chamber 19 and a final external expansion chamber 29 that alternately expand and contract, and the final internal expansion chamber 19 and the final external expansion chamber 2
When the movable shell 9 alternately expands and contracts, the gas passing through the gas passages 16 and 28 flows in opposite directions and exchanges heat through the final stage portion 14c of the movable shell 14. In this way, in the final stage, heat is exchanged with the gas without using a regenerator, so there is no restriction by the Debye temperature. Therefore, it is possible to achieve extremely low temperatures around the He liquefaction temperature (4.2K).

Moreover, since the movable part is a hollow shell, the inertial mass is small and vibration can be significantly reduced. In addition, since the regenerators 7 and 11 are disposed by effectively utilizing the internal space of the movable shell 14, it is possible to make the regenerator more compact than conventional products in which the regenerators are disposed outside the casing.

In addition, when operating the Gift McMahon cycle as in this embodiment, the movable shell 14
By utilizing the fact that the pressure receiving area on the normal temperature end side of the movable shell 14 is smaller than the pressure receiving area on the low temperature end side due to the presence of the communication pipe 4 penetrated to the high temperature end side of the movable shell 14, the movable shell 14 is connected to high pressure gas. It becomes possible to move only by biasing force. Therefore, no mechanism for operating the displacer (movable shell) is required, and the structure can be greatly simplified.

Note that the present invention is not limited to a refrigeration system operating on the Gifford-McMahon cycle, but can be similarly applied to, for example, a small-sized cryogenic refrigeration system using a Solvay cycle, a Stirling cycle, or the like.

Further, in the above embodiment, a three-stage type was described, but the present invention is of course applicable to a two-stage type and a multi-stage type of four or more stages.

Also, the spacer provided at the final stage is made hollow.
Fill the casing with He gas or
The spacer may be filled with gas, or both the inside of the spacer and the casing portion may be filled with He gas.

Further, the final stage portion of the movable shell may have a means (for example, a fin-like convex portion) for increasing the contact area with the gas on its surface. It is often done.

[Effects of the Invention] Since the present invention has the above-described configuration, it is possible to provide a cryogenic refrigeration device that can achieve a He liquefaction temperature without complicating the structure even if it is a gas cycle system. It is.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a longitudinal sectional view, Fig. 2 a, b, c, and d are explanatory diagrams of operation, and Fig. 3 a, b explains pressure distribution on the movable shell. FIG. 1... Fixed member (base), 7, 11... Internal regenerator, 14... Movable shell, 16, 28... Gas passage, 17, 18... Internal expansion chamber, 19... Final internal expansion Chamber, 22...Casing, 23, 24
... External regenerator, 26, 27 ... External expansion chamber, 2
9... Final external expansion chamber, 31... Timing valve, 32... Air supply system path, 33... Exhaust system path.

Claims (1)

[Claims] 1 A cryogenic refrigeration system consisting of multiple stages, including an internal regenerator disposed in the first stage and supported by a fixed member, a spacer disposed in the final stage and fixedly supported, and the internal regenerator. A final stage is slidably fitted on the outer periphery of the spacer to form an internal expansion chamber between it and the low temperature end of the regenerator, and a final stage is slidably disposed on the outer periphery of the spacer via a gas passage, and the low temperature end thereof is slidably fitted on the outer periphery of the spacer. a hollow movable shell forming a final internal expansion chamber between the movable shell and the spacer; an external regenerator disposed around the outer periphery of the movable shell except for the final stage; An external expansion chamber is formed between the movable shell and the external regenerator, and a final stage surrounds the outer periphery of the final stage of the movable shell via a gas passage. a casing that forms a final external expansion chamber between the low-temperature side end of the stage, and a timing valve that connects the high-temperature end of each of the regenerators of the first stage to an air supply system path or an exhaust system path at a preset timing. and heat exchange can be performed between the gas flowing in and out of the final internal expansion chamber and the gas flowing in and out of the final external expansion chamber through the final stage of the movable shell. A cryogenic freezing device characterized by: