JPS6353465B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultra-low temperature refrigerator, and more specifically,
This invention relates to an ultra-low temperature refrigerator that can efficiently generate refrigeration of 10 K or less in a short time and expands the range of applications such as reverse Stirling cycle or Gifford-McMahon cycle.

An object of the present invention is to sequentially communicate a compression space, a cooler, a first regenerator, a second regenerator, a first expansion space, and a second expansion space, and a third regenerator is provided between the second regenerator and the expansion space. , a one-way valve and a heat exchanger are installed, and the 10K working gas (helium gas) flowing into and out of one end of the third regenerator side of the heat exchanger connects the high temperature side heat exchanger and the low temperature side heat exchanger of the heat exchanger. To provide an ultra-low temperature refrigerator in which working gases exchange heat with each other by utilizing the property of having a large heat capacity.

An embodiment of the present invention will be described based on FIGS. 1 and 2. A compression space 3 formed by a compression cylinder 1 and a compression piston 2 passes through a cooler 4, a first regenerator 5, a communication pipe 6, 7 and communicate with one end side of the first expansion space 8 and the second regenerator 9, respectively.

The other end side of the second regenerator 9 is connected to communication pipes 11 and 32.
, and communicate with the second expansion space 10 and one end side of the third regenerator 33, respectively. The other end of the third regenerator 33 is connected to one end of the communication pipes 12 and 13, and the other end of the communication pipes 12 and 13 is connected to one end of the one-way valve 14 and one end of the one-way valve 15, respectively. It's communicating. The other end sides of the one-way valves 14 and 15 are connected to the high temperature side heat exchanger 16a of the AC heat exchanger 16, respectively.
and communicates with one end side of the low temperature side heat exchanger 16b, and the high temperature side heat exchanger 16a and the low temperature side heat exchanger 16b.
The other end side communicates with one end of one-way valves 17 and 18, respectively. The other end sides of the one-way valves 17 and 18 communicate with a third expansion space 21 through communication pipes 19 and 20, respectively.

The third regenerator 33 includes a case 33a, filters 33b and 33c made of sintered metal, a regenerator material made of spherical lead with a large specific heat, and 33d the interior 3 of the case.
3e, and 14 and 15 are one-way valves that communicate with the AC heat exchanger 16. AC heat exchanger 1
6 is a case 16c, a high temperature side passage 16a, a low temperature side passage 16b, and the passage 16a is a finch tube 16.
e. It is made of 16f fins and is made of a metal (Cu-based) with good thermal conductivity. 17a and 18a are communication pipes to the one-way valves 17 and 18. The refrigeration circuit configured in this manner is filled with a refrigerant such as helium gas.

A rod 22 is connected to the compression piston 2, and a piston ring 23 for gas sealing is provided on a part of the outer circumference of the compression piston 2, and a part of the outer wall of the rod 22 is also provided for gas sealing. A seal 31 is provided for this purpose.

The first expansion space 8, the second expansion space 10, and the third expansion space 21 are each formed by an expansion cylinder 24 and an expansion piston 25, each having a three-stage convex shape. On the outer periphery of each stage of the expansion piston, the first,
Piston rings 26, 27, 28 are installed for gas sealing in the second and third expansion spaces 8, 10, 21. Further, a rod 29 is connected to the expansion piston 25, and a seal 30 for gas sealing is installed on a part of the outer wall of the rod 29. The rods 22 and 29 are connected to a reciprocating drive mechanism (for example, a crank) not shown, and the expansion piston 25
is arranged so that the phase is approximately 90° ahead of the compression piston 2.

2-1 to 2-4 show one cycle of the flow of working gas between the high temperature side heat exchanger 16a and the low temperature side heat exchanger 16 of the heat exchanger 16.

To explain the operation of the present invention in the above configuration, the working gas (helium etc.) in the compression space 3 is compressed by the compressor paston 2, cooled by the cooler 4, passed through the first cooler 5, further cooled and communicated. A first expansion space 8 and a second expansion space pass through the tubes 6 and 7, respectively.
It flows into the regenerator 9. The working gas that has entered the first expansion space 8 is expanded by the expansion piston 25 to approximately
Generates refrigeration at a temperature of 70K. By the way, the working gas that has flowed into the second regenerator 9 is further cooled, passes through the communication pipe 11 , passes through the second expansion space 10 and the communication pipe 32 , and flows into the third regenerator 33 . The working gas flowing into the second expansion space 10 is expanded by the expansion piston 25 and is frozen at a temperature of about 15K. Third
The working gas that has flowed into the regenerator 33 is further cooled by the granular lead and flows into the communication pipes 12 and 13.

The working gas flowing into the communication pipe 12 passes through the one-way valve 1
4, the high temperature side heat exchanger 16 of the heat exchanger 16
a, from the third expansion space 21 to the communication pipe 2
0 and the low temperature side heat exchanger 16b through the one-way valve 18
It enters the space of The one-way valve 17 and the communication pipe 1 are cooled by low-temperature working gas.
9 and flows into the third expansion space 21 . Third
The working gas flowing into the expansion space 21 is frozen at a temperature of about 4K by the expansion of the expansion piston 25. On the other hand, the working gas that has flowed into the communication pipe 13 does not flow into the low temperature heat exchanger 16b of the heat exchanger 16 due to the one-way valve 15.

The working gas that has finished expanding in the third expansion space 21 is
Due to the compression of the expansion piston 25, the communication pipe 19,
20. The working gas that has flowed into the communication no. 19 closes the one-way valve 17 and does not flow into the high temperature side heat exchanger 16a of the heat exchanger 16. On the other hand, when the working gas that has flowed into the communication hole 20 flows into the low-temperature heat exchanger 16b of the heat exchanger 16 through the one-way valve 18, it sequentially passes through the second regenerator 9, the one-way valve 14, and the high-temperature side. It receives heat from the high-temperature working gas that has entered the space of the heat exchanger 16a, and is warmed.
Then, it passes through the one-way valve 15 and the communication pipe 13 and flows into the third regenerator 33 . The working gas that has flowed into the third regenerator 33 is further warmed, flows into the communication pipe 32, and then flows into the second regenerator 9.

The working gas that has finished expanding in the second expansion space 10 also
Due to the compression of the expansion piston 25, the air flows through the communication pipe 11 and into the second regenerator 9. The working gas that has flowed into the second regenerator 9 is further warmed and flows into the first regenerator 5 . The working gas that has finished expanding in the first expansion space 8 is compressed by the expansion piston 25 and is moved to the communication pipe 6.
It flows into the first regenerator 5 through. First regenerator 5
The working gas that has flowed into the chamber is heated and flows into the cooler 4, and then into the compression space 3. In this way, one cycle is formed.

Next, heat exchange of working gas between the high temperature side heat exchanger 16a and the low temperature side heat exchanger 16b of the heat exchanger 16 will be explained based on FIGS. 2-1 to 2-4. When the expansion piston 25 is at bottom dead center, the pressure of the working gas is approximately close to the minimum pressure (as shown in FIG. 2-1). the communication pipes 11, 12, 13 the one-way valves 14, 15, the high temperature side heat exchanger 16a and the low temperature side heat exchanger 16b of the heat exchanger 16, the one-way valve 17,
18, communication pipes 19, 20, and third expansion space 2
The pressures of the working gas inside 1 are approximately equal,
The one-way valves 14, 14, 17, and 18 are closed by the force of the spring. FIG. 2-1 shows this state. Next, the expansion piston 25 moves from the bottom dead center toward the top dead center (as shown in FIG. 2-2).
The working gas in the third expansion space 21 is compressed, the pressure increases, and the one-way valve 18 is opened through the communication pipe 20, causing the low-temperature side heat exchanger 16 of the heat exchanger 16 to open.
flows into b. Furthermore, low temperature side heat exchanger 1
The working gas flowing into the third regenerator 33 opens the one-way valve 15 and flows into the third regenerator 33 through the communication pipe 13, increasing the pressure of the working gas in the third regenerator 33. The working gas whose pressure has increased in the third regenerator 33 further opens the one-way valve 14 and flows into the high-temperature side heat exchanger 16a, and then flows from the one-way valve 18 toward the one-way valve 15 on the low-temperature side. It is cooled by the cold working gas flowing through the heat exchanger 16b. On the other hand, the working gas flowing through the low temperature side heat exchanger 16b is warmed and flows into the third regenerator 33. Since the pressure of the working gas in the high temperature side heat exchanger 16a of the heat exchanger 16 is lower than that of the working gas in the communication pipe 19,
One-way valve 17 remains closed. When the expansion piston 25 reaches the top dead center, the pressure of the working gas becomes nearly the maximum pressure. (See Figure 2-3.) Next, the communication pipes 11, 12, 13, the one-way valves 14, 15, the high temperature side heat exchanger 16a and the low temperature side heat exchanger 16b of the heat exchanger 16, the one-way valve 17, 18, communication pipe 19, 2
0, and the working gas inside the third expansion space 21 is almost equal, and the one-way valves 14, 15, 18
is closed by the force of the spring. This situation is shown in Figure 2-3. When the expansion piston 25 expands from the top dead center toward the bottom dead center (as shown in FIG. 2-4).
The pressure of the working gas in the third expansion space 21 decreases while refrigeration of about 4K occurs.

As a result, the high temperature side heat exchanger 16 of the heat exchanger 16
The working gas pressure in a causes the one-way valve 17 to open. Further, the pressure of the working gas in the high temperature side heat exchanger 16a becomes lower than the pressure of the working gas in the communication pipe 12, and the one-way valve 14 also becomes open. In this way, the working gas in the third regenerator 33 is transferred to the communication pipe 12, the one-way valve 14, the high temperature side heat exchanger 16a, and the one-way valve 1.
7. Flows into the third expansion space 21 through the communication gap 19. On the other hand, the one-way valve 18
It remains closed because the pressure of the working gas has decreased. On the other hand, the working gas in the low-temperature side heat exchanger 16b of the heat exchanger 16 causes the one-way valve 15 to open due to the pressure drop of the working gas in the third regenerator 33. As a result, the cold working gas in the low temperature side heat exchanger 16b flows through the high temperature side heat exchanger 16b to the third regenerator 33 while cooling the working gas flowing from the one-way valve 14 to the one-way valve 17. Inflow.

In this way, heat exchange between the working gases takes place within the heat exchanger 16, and one cycle is completed.

FIG. 8 shows a conventional refrigerator of this type. After the working gas in the compression space 201 is compressed by the compression piston 209, it is cooled by the cooler 202, and the first
The first expansion space 204 is cooled by passing through the regenerator 203.
and flows into the second regenerator 205. The working gas that has flowed into the second regenerator 205 is further cooled and
It flows into the expansion space 206 and the third regenerator 207.
The working gas that has flowed into the third regenerator 207 is further cooled and flows into the third expansion space 208 . The first, second and third expansion spaces 204, 206, 20
The working gas flowing into the working gas 8 is frozen at temperatures of about 70K, about 15K, and about 10K in the first, second, and third expansion spaces by expansion of the expansion piston 210, respectively. By the way, the third regenerator is filled with a heat storage material such as lead. The specific heat of a heat storage material such as lead decreases significantly as the temperature decreases, so a large amount of heat storage material is required to exchange heat with the working gas.
As a result, the dead volume of the third regenerator increases,
Furthermore, the flow path resistance through which the working gas flows also increases, making it impossible to efficiently achieve 10K refrigeration in the third expansion space 208.

In the present invention, as shown in FIGS. 1 and 2, a third regenerator 33 is provided between the one-way valves 14, 15 and the second regenerator 9. The temperature of the gas is about 10 K, which makes it possible to make the efficiency of the heat exchanger 16 very high, and furthermore, the high temperature side heat exchanger 16 of the heat exchanger 16
A and the low temperature side heat exchanger 16b exchange heat between the working gas (helium gas) at about 10K by utilizing the above-mentioned property of helium gas having a large heat capacity, and as a result, the dead volume of the heat exchanger is reduced. Furthermore, the flow path resistance can be significantly reduced, and refrigeration of 10 K or less can be efficiently achieved in the third expansion space 10. Furthermore, the temperature can be lower than that of conventional refrigerators of this type. Furthermore, the amount of refrigeration increases, and as a result, the time from when the refrigerator starts operating until the temperature in the third expansion space 21 reaches a steady state of 10K or less can be shortened.

Another embodiment of the present invention shown in FIGS. 3 to 7 is a one-way valve when an AC heat exchanger and a one-way valve are used between the third regenerator 33 and the third expansion space 21. The device is simplified by using two. That is, to explain the apparatus shown in FIGS. 3 and 4, when the working gas flows from the third regenerator 33 to the third expansion space 21, the high temperature side passage 16a and the low temperature side passage 16b of the AC heat exchanger 16 Since the pressure inside is higher than the pressure in the third expansion space 21, the one-way valve 18 is closed and the one-way valve 17 is open. Therefore, from the third regenerator 33 to the low temperature side passage 1
No working gas flows into 6b, and the cold working gas that has already flowed from the third expansion space 21 is accumulated therein. The working gas flowing from the third regenerator 33 to the high temperature side passage 16a of the AC heat exchanger 16 is cooled by the working gas accumulated in the low temperature side passage 16b, and the one-way valve 17 and the communication pipe 17 are cooled. and flows into the third expansion space 21. From the third expansion space 21 to the third
When flowing in the direction of the regenerator 33, the AC heat exchanger 1
Since the pressure in the high temperature side passage 16a and the low temperature side passage 16b of No. 6 is lower than the pressure in the third expansion space 21, the one-way valve 17 is closed and the one-way valve 18 is open.
Therefore, the working gas does not flow from the third regenerator 33 to the high temperature side passage 16a, and the cold working gas that has already flowed from the third expansion space 21 is accumulated therein. From the third expansion space 21 to the communication pipe 20 and the one-way valve 1
The working gas that has flowed into the low-temperature side passage 16b through 8 is warmed by the working gas stored in the high-temperature side passage 16a, and then flows into the third regenerator 33. In this way, the working gases exchange heat with each other in the AC heat exchanger 16. Similar heat exchange is performed in the apparatuses shown in FIGS. 5 to 7.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a refrigerator according to an embodiment of the present invention, and FIGS. 2-1 to 2-4 are operational diagrams showing one cycle of the flow of working gas in the refrigerator shown in FIG.
FIG. 3 is a sectional view of a heat exchanger and a third regenerator, FIGS. 4 to 7 are schematic sectional views of other embodiments of the present invention, and FIG. 8 is a schematic sectional view of a conventional embodiment. be. 3: Compression space, 4: Cooler, 5: First regenerator,
8: First expansion space, 9: Second regenerator, 10: Second
Expansion space, 14, 15, 17, 18: one-way valve,
16: heat exchanger, 21: third expansion space, 33: third regenerator, 33b, 33e: sintered metal filter, 33d: regenerator such as a lead ball.

Claims (1)

[Claims] 1 The compression space, the cooler, the first regenerator, the second regenerator, and the third regenerator are connected in sequence, and the first regenerator and the second regenerator are connected to the first regenerator, respectively.
communicates with the expansion space and the second expansion space;
The third regenerator and the AC heat exchanger are interposed between the regenerator and the third expansion space, one-way valves are reciprocally provided at arbitrary positions of each phase of the AC heat exchanger, and the working gas A refrigerator in which both sides exchange heat.