JPH0120699B2 - - 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 and expands the range of applications such as reverse Stirling cycle or Gifford-McMahon cycle.

The object of the present invention is to sequentially communicate a compression space, a cooler, a storage cooler, and an expansion space, and provide a one-way valve and a countercurrent heat exchanger between the storage cooler and the expansion space, so that the working gases can heat each other. The present invention provides an ultra-low temperature refrigerator that is replaceable.

An embodiment of the present invention will be described based on FIG. 1. A compression space 3 formed by a compression cylinder 1 and a compression piston 2 passes through a cooler 4, a first cooler 5, and communication pipes 6 and 7. a first expansion space 8, respectively;
It communicates with one end side of the second refrigerator 9. Said second
The other end of the refrigerator 9 communicates with the second expansion space 10, one end of the one-way valve 14, and one end of the one-way valve 15 through communication pipes 11, 12, and 13, respectively. The other end sides of the one-way valves 14 and 15 communicate with one end side of the high temperature heat exchanger 16a and the low temperature side heat exchanger 16b of the counterflow heat exchanger 16, respectively, and the high temperature side heat exchanger 16
a and the other end of the low-temperature side heat exchanger 16b communicate with one end of one-way valves 17 and 18, respectively. The other end sides of the one-way valves 17 and 18 are connected to the communication pipe 1, respectively.
It communicates with the third expansion space 21 through 9 and 20. A cross-sectional view of the countercurrent heat exchanger 16 is shown in FIG.
14a, 15a, 17a, and 18a are communication passages to one-way valves 14, 15, 17, and 18, respectively.
c is the case, 16d and 16e are the collectors, 1
6f is a tube and 16g is a fin. Fin 16g is made of metal (Cu-based) with good thermal conductivity. The refrigeration circuit configured in this manner is filled with a refrigerant such as helium gas. A rod 22 is communicated with the compression piston 2, and a piston ring 23 is provided on a part of the outer circumference of the compression piston 2 for gas sealing, and a part of the outer wall of the rod 22 is also provided with a piston ring 23 for gas sealing. A seal 31 is provided.

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 2, 3 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 mechanism), not shown, and are arranged so that the expansion piston 25 is ahead of the compression piston 2 by about 90 degrees in phase.

Figures 2-1 to 2-4 are the countercurrent heat exchanger 1.
6 high temperature heat exchanger 16a and low temperature side heat exchanger 16b
This figure shows one cycle of the working gas flow.

To explain the operation of the present invention in the above configuration, the working gas (helium gas, etc.) in the compression space 3 is compressed by the compression piston 2, cooled by the cooler 4, passed through the first cooler 5, It is further cooled and passes through the communication pipes 6 and 7, and flows into the first expansion chamber 8 and the second storage cooler 9, respectively. The working gas entering the second expansion space 8 is expanded by the expansion piston 25 to produce refrigeration at a temperature of about 70K. By the way, the working gas that has flowed into the second storage cooler 9 is further cooled and passes through the communication pipe 11 into the second expansion space 10.
and flows into the communication pipes 12 and 13. The working gas that has flowed into the second expansion space 10 is expanded by the expansion piston 25 to generate refrigeration at a temperature of approximately 15K. On the other hand, the working gas that has flowed into the communication pipe 12 passes through the one-way valve 14 and flows into the high temperature side heat exchanger 16a of the counterflow heat exchanger (hereinafter simply referred to as the heat exchanger) 16, and is then communicated from the third expansion space 21. The low-temperature working gas that enters the space of the low-temperature side heat exchanger 16b through the pipe 20 and the one-way valve 18 is cooled through the fin 16g, passes through the one-way valve 17 and the communication pipe 19, and enters the third expansion. It flows into the space 21. The working gas flowing into the third 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 counterflow 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 in through the communication pipe 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, the working gas that has flowed into the communication hole 20 closes the one-way valve 17.
When the gas flows into the low-temperature heat exchanger 16b of the heat exchanger 16, it receives heat from the high-temperature working gas that has entered the space of the high-temperature heat exchanger 16a, passing through the second cooler 9 and the one-way valve 14 in sequence. Warmed one-way valve 1
5 and the communication pipe 13 and flows into the second refrigerator 9.

The working gas that has been expanded in the second expansion space 10 is compressed by the expansion piston 25 and flows into the second cooler 9 through the communication pipe 11. The working gas that has flowed into the second cooler 9 is heated and flows into the first cooler 5. The working gas that has been expanded in the first expansion space 8 is compressed by the expansion piston 25 and flows into the first refrigerator 5 through the communication pipe 6. The working gas flowing into the first cooler 5 is warmed and flows into the cooler 4, and then into the compression space 3, thus forming one cycle.

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 the bottom dead center, the pressure of the working gas is almost at its lowest (as shown in Figure 2-1).
the second expansion space 10, the communication pipes 11, 12,
13, the one-way valves 14, 15, the heat exchanger 1
6 high temperature side heat exchanger 16a and low temperature side heat exchanger 16
b. The pressures of the working gas inside the one-way valves 17, 18, the communication pipes 19, 20, and the third expansion space 21 are approximately equal, so that the one-way valves 14, 15, 17,
18 is closed by the force of the spring. FIG. 2-1 shows this state. Next, when the expansion piston 25 moves from the bottom dead center toward the top dead center, the working gas in the third expansion space 21 (shown in FIG. Directional valve 1
8 is opened and flows into the low temperature side heat exchanger 16b of the heat exchanger 16. Furthermore, low temperature side heat exchanger 1
The working gas flowing into 6b opens the one-way valve 15, flows into the second cooler 9 through the communication pipe 13, and increases the pressure of the working gas in the second cooler 9. The working gas whose pressure has increased in the second storage cooler 9 opens the one-way valve 14 and flows into the high-temperature heat exchanger 16a, then flows from the one-way valve 18 to the one-way valve 15, and then passes through the low-temperature heat exchanger 16b. Cooled by flowing cold working gas. On the other hand, the working gas flowing through the low temperature side heat exchanger 16b is heated and flows into the second cooler 9. 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, the one-way valve 17 remains closed. FIG. 2-2 shows this state. Next, when the expansion piston 25 reaches the top dead center, the pressure of the working gas becomes close to the maximum pressure (as shown in FIG. 2-3).

Next, the second expansion space 10, the communication pipes 11, 12, 1
3. Internal operation of the one-way valves 14 and 15, the high-temperature heat exchanger 16a and the low-temperature side heat exchanger 16b of the heat exchanger 16, the one-way valves 17 and 18, the communication pipes 19 and 20, and the third expansion space 21 The gases become approximately equal, and the one-way valves 14, 15, 18 are closed by the force of the spring. The one-way valve 17 then remains closed. Figure 2-3 shows this state.

When the expansion piston 25 expands from the top dead center toward the bottom dead center, the working gas in the third expansion space 21 becomes approximately
The pressure decreases while generating 4K refrigeration (second
(shown in Figure 4).

As a result, the high temperature side heat exchanger 16 of the heat exchanger 16
The pressure of the working gas in a causes the one-way valve 17 to open. 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 second refrigerator 9 is transferred to the communication pipe 12, the one-way valve 14,
High temperature side heat exchanger 16a, one-way valve 17, communication pipe 1
9, it flows into the third expansion space 21, and the pressure in the second refrigerator 9 also decreases.

On the other hand, the one-way valve 18 maintains the closed state because the pressure of the working gas in the third expansion space 21 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 second cooler 9. As a result, the cooled working gas in the low temperature side heat exchanger 16b passes through the high temperature side heat exchanger 16a while cooling the working gas flowing from the one-way valve 14 to the one-way valve 17. 9. Figure 2-4 shows this situation. In this way, heat exchange between the working gases takes place within the countercurrent heat exchanger 16, completing one cycle.

To explain the conventional refrigerator of this type with reference to FIG. It flows into the expansion space 204 and the second refrigerator 205. The working gas that has flowed into the second cooler 205 is further cooled and flows into the second expansion space 206 and the third cooler 207. The working gas flowing into the third cooler 207 is further cooled and flows into the third expansion gas space 208.
flows into. the first, second and third expansion spaces 204;
The working gas flowing into the working gases 206 and 208 is frozen at temperatures of approximately 70K, approximately 15K, and approximately 10K in the first, second, and third expansion spaces by the expansion of the expansion piston 210, respectively. By the way, the third refrigerator 207
The interior is filled with heat storage materials such as lead. The specific heat of heat storage materials 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 third refrigerator 20
7 becomes large, and the flow path resistance through which the working gas flows also becomes large, making it impossible to efficiently achieve refrigeration below 10 K in the third expansion space 208.

The present invention provides a heat exchanger 1 as shown in FIG.
6 high temperature side heat exchanger 16a and low temperature side heat exchanger 16
At b, the working gas (helium gas) at about 15K or less exchanges heat with each other through the 16g fin. As a result, the dead volume of the heat exchanger can be reduced, and the flow path resistance can also be significantly reduced, and refrigeration of 10 K or less can be efficiently achieved in the third expansion space 10. Compared to conventional refrigerators of this type, it is possible to obtain lower temperatures.

Another embodiment of the present invention, shown in FIGS. 4 to 7, uses a countercurrent heat exchanger and a one-way valve between the second cooler 9 and the third expansion space 21. The device is simplified by using two directional valves. That is, to explain the apparatus shown in FIGS. 3 and 4, from the second refrigerator 9 to the third expansion space 21
When the working gas flows in the direction of the counterflow heat exchanger 1
Since the pressure in the high temperature side passage 16a and the low temperature side passage 16b of No. 6 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, the working gas does not flow from the second cooler 9 to the low temperature side passage 16b, and the cold working gas that has already flowed from the third expansion space 21 is accumulated therein. Second
From the storage cooler 9 to the high temperature side passage 16 of the countercurrent heat exchanger 16
The working gas that has flowed into the third expansion space 21 is cooled by the working gas stored in the low-temperature side passage 16b, and flows into the third expansion space 21 through the one-way valve 17 and the communication pipe. When flowing from the third expansion space 21 to the second cooler 9, the high temperature side passage 1 of the countercurrent heat exchanger 16
6a, the pressure in the low temperature side passage 16b is lower than the pressure in the third expansion space 21, so the one-way valve 17 is closed and the one-way valve 18 is open. Therefore, the working gas does not flow from the second cooler 9 to the high temperature side passage 16a, and the cold working gas that has already flowed from the second cooler 9 is accumulated therein. The low temperature passage 1 is passed from the third expansion space 21 through the communication pipe 20 and the one-way valve 18.
The working gas that has flowed into the high temperature side passage 16a
The second
It flows into the storage cooler 9. In this way, the working gases exchange heat with each other in the countercurrent 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 countercurrent heat exchanger, FIGS. 4 to 7 are schematic sectional views of other embodiments of the present invention, and FIG.
The figure is a schematic sectional view of a conventional embodiment. 3... Compression space, 4... Cooler, 5... First storage cooler, 8... First expansion space, 9... Second storage cooler,
10...Second expansion space, 14, 15, 17, 18
... One-way valve, 16 ... Countercurrent heat exchanger, 16c...
...Case, 16f...Finch Yube, 16g...
...Fin, 21...Third expansion space.

Claims (1)

[Claims] 1. Sequentially communicating the compression space, the cooler, the first storage cooler, and the second storage cooler, and communicating the first storage cooler and the second storage cooler with the first expansion space and the second expansion space, respectively. , a counter-current heat exchanger is interposed between the second cooler and the third expansion space, one-way valves are reciprocally provided at arbitrary positions of each phase of the counter-current heat exchanger, and the one-way valves are reciprocally operated. A refrigerator that exchanges heat between both gases.