JPH0147713B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultra-low temperature refrigerator, and more specifically, it is capable of efficiently generating refrigeration of 10 K or less with a simple mechanism in a short time, and is capable of generating freezing at a temperature of 10 K or less using a reverse Stirling cycle or a Gibbard-McMahon cycle. This article relates to ultra-low temperature refrigerators, which are expanding the scope of their use.

The present invention provides a refrigerator in which a compression space, a cooler, a regenerator, a regenerative heat exchanger, and an expansion space are sequentially connected to each other, and a space surrounding an outer wall side of a flow path of the regenerative heat exchanger; The compression space, the space in the regenerator, the flow path of the regenerative heat exchanger, the expansion space, and the buffer space communicate with each other via a restriction, and the inner wall of the flow path of the regenerative heat exchanger Heat exchange is performed between the working gas (helium gas) flowing on the side and the working gas (helium gas) on the outer wall side of the flow path of the regenerative heat exchanger through the wall forming the flow path. Therefore, the present invention provides an ultra-low temperature refrigerator capable of efficiently generating refrigeration in an expansion space in a short period of time. In the case of a refrigerator having second and third expansion spaces, the present invention provides an ultra-low temperature refrigerator that can efficiently generate refrigeration of 10 K or less in the third expansion space in a short time.

An embodiment of the present invention will be described based on FIG. 1 and FIG.
Passes through the regenerator 5 and through communication pipes 6 and 7,
They 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
It passes through communication pipes 11 and 12 and communicates with one end side of the second expansion space 10 and the third regenerator 13, respectively.
The other end side of the third regenerator 13 passes through a communication pipe 14 and communicates with one end side of a flow path 15a of a regenerative heat exchanger 15. The other end of the flow path 15a communicates with the third expansion space 17 through a communication pipe 16.
The third expansion space 17 sequentially includes a communication pipe 18, an aperture 1
9. A space 15b surrounding the outer wall side of the flow path 15a of the regenerative heat exchanger 15 via the communication pipe 20
is connected to.

The refrigeration circuit configured in this manner is filled with refrigeration of working gas 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.
A seal 31 for gas sealing is also provided on a part of the outer wall of the rod 22.

The first expansion space 8, the second expansion space 10, and the third expansion space 17 are each formed by an expansion cylinder 24 and an expansion piston 25, each having a two-stage convex shape. On the outer periphery of each stage of the expansion piston 25, piston rings 26, 27, and 28 are installed to seal the first, second, and third expansion spaces 8, 10, and 17 with gas. Also, the expansion piston 25 has a rod 29.
A seal 30 for gas sealing is installed on a part of the outer wall of the rod. The rods 22 and 29 are connected to a reciprocating mechanism (for example, a crank mechanism), not shown, so that the expansion piston 25 is advanced in phase by about 90 degrees from the compression piston 2.

The present invention can also be applied to refrigerators such as Gifford cycle, Gifford McMahon cycle, Solvay cycle, etc. that use switching valves.

To explain the operation of the present invention, the compressed space 3
The working gas (helium gas, etc.) is compressed by the compression piston 2, cooled by the cooler 4, passed through the first regenerator 5, further cooled, and then passed through the communication pipe 6,
7 and flow into the first expansion space 8 and the second regenerator 9, respectively. The working gas that has entered the first expansion space 8 is expanded by the expansion piston 25, and its temperature drops and refrigeration occurs. By the way, the working gas that has flowed into the second regenerator 9 is further cooled and passes through the communication pipe 11.
through the second expansion space 10 and the third through the communication pipe 12.
It flows into the regenerator 13. The working gas that has flowed into the second expansion space 10 is expanded by the expansion of the expansion piston 25, and refrigeration occurs at a temperature lower than that of the first expansion space 8. The working gas flowing into the third regenerator 13 is further cooled and sequentially flows into the communication pipe 14 and the flow path 15a of the regenerative heat exchanger 15. Channel 1
The working gas flowing into the third expansion space 17 passes through the communication pipe 16 while cooling the helium gas in the space 15b of the heat exchanger 15 through the wall forming the flow path 15a. The working gas that has flowed into the third expansion space 17 is expanded by the expansion piston 25 to generate refrigeration at a lower temperature than the second expansion space. The working gas that has finished expanding in the third expansion space 17 is compressed by the expansion piston 25 and is transferred to the communication pipe 1.
6 and flows into the flow path 15a of the regenerative heat exchanger 15, the helium gas in the space 15b of the regenerative heat exchanger 15 is cooled through the wall forming the flow path 15a, while passing through the communication pipe 14. Third regenerator 13
flows into. The working gas that has flowed into the third regenerator 13 is heated and flows into the second regenerator 9 through the communication pipe 12 . Furthermore, the working gas that has finished expanding in the second expansion space 10 also flows into the second regenerator 9 through the communication pipe 11 due to compression by the expansion piston 25. The working gas that has flowed into the second regenerator 9 is further warmed and flows into the first regenerator 5 through the communication pipe 7 . The working gas that has expanded into the first expansion space 8 also flows into the first regenerator 5 through the communication pipe 6 due to compression by the expansion piston 25 . The working gas that has flowed into the first regenerator 5 is further warmed, flows into the cooler 4, and further flows into the compression space 3.

By the way, when the temperature of the regenerative heat exchanger 15 decreases, the temperature of the helium gas in the space 15b of the regenerative heat exchanger 15 decreases, and the pressure in the space 15b decreases. When the pressure in the space 15b decreases, the working gas in the third expansion space 17 flows into the space 15b through the communication pipe 18, the throttle 19, and the communication pipe 20, and the pressure in the space 15b becomes approximately equal to the average pressure of the refrigeration cycle. be equal.

Figure 2b shows the change in pressure in this situation, where _P1 shows the change in pressure in the third expansion space 17, which changes greatly due to the action of the compression piston 2 and expansion piston 25, but in a regenerative heat exchanger. Due to the restriction 19, the pressure in the space 15b changes very little as shown at _P2 .

In this way, one cycle is formed. When this refrigeration cycle is repeated many times, the first expansion space 8,
The temperature of the working gas in each of the second expansion space 10 and the third expansion space 17 gradually decreases, and the temperature of the working gas in each of the second expansion space 10 and the third expansion space 17 gradually decreases.
100K, the second expansion space is approximately 30K, the third expansion space is approximately 15K, and the regenerative heat exchanger 15 is also approximately 15K.

By the way, when the temperature of the regenerative heat exchanger 15 reaches about 15K, the working gas that flows into the third regenerator 13 through the second regenerator 9 and the communication pipe 12 is further cooled and passes through the communication pipe 14 to the regenerative heat exchanger. 15 channels 15a
flows into. The working gas flowing into the flow path 15a passes through the wall forming the flow path 15a and passes through the heat exchanger 15.
It is further cooled by the helium gas in the space 15b and flows into the third expansion space 17 through the communication pipe 16. The working gas flowing into the third expansion space 17 is frozen at a temperature lower than 15K by the expansion of the expansion piston 25. The working gas that has finished expanding in the third expansion space 17 is compressed by the expansion piston 25 and passes through the communication pipe 16 to the regenerative heat exchanger 1.
5 flows into the flow path 15a. The working gas that has flowed into the flow path 15a is heated by the helium gas in the space 15b of the regenerative heat exchanger 15 through the wall forming the flow path 15, and passes through the communication pipe 14 to the third regenerator 1.
Flows into 3. The working gas that has flowed into the third regenerator 13 is further warmed and passes through the communication pipe 12 to the second regenerator 13.
It flows into the regenerator 9. The working gas that has finished expanding in the second expansion space 10 and the first expansion space 8 returns to the compression space 3 by the same action as described above and completes one cycle. After the temperature of the regenerative heat exchanger 15 reaches approximately 15K in this manner, by repeating this refrigeration cycle many times, the first expansion space 8 generates refrigeration of approximately 70K, and the second expansion space 10 generates refrigeration of approximately 70K. Generates approximately 25K of refrigeration. The working gas in the communication pipe 14 is about 15K, and the third expansion space 17 generates refrigeration at about 4K.

Next, when the operation of the refrigerator is stopped, the temperature in the space 15b of the regenerative heat exchanger 15 rises, and the pressure in the space 15b increases. 13, the flow path 15a of the regenerative heat exchanger 15, each expansion space 8, 1
It becomes higher than the pressure of 0.17. As a result, space 1
The helium gas in 5b is supplied through the communication pipe 20, the aperture 19,
flows into the third expansion space 17 through the communication pipe 18,
The pressure in the space 15b becomes approximately equal to the pressure in the space forming the refrigeration cycle.

In addition, Figure 3 shows the heat capacity per unit volume of 10at helium gas and a lead ball, which is clearly 15K.
The following shows that helium gas has a large heat capacity, and above 15K, the heat capacity per unit volume of a lead ball is larger than the heat capacity of helium gas.

As described above, according to the present invention, the space 15b of the regenerative heat exchanger 15 is connected to the space forming the refrigeration cycle through the throttle, so even if the temperature of the regenerative heat exchanger 15 drops, Helium gas is supplied through the throttle 19 so that the pressure in the space 15b of the heat exchanger 15 is maintained at an intermediate pressure between the pressure in the third expansion space 3.

As a result, the helium gas in the space 15b of the regenerative heat exchanger 15 and the helium gas in the flow path 15a are connected to each other through the wall forming the flow path 15a, utilizing the above-mentioned property of high heat capacity of helium gas (approximately 15 K or less). Since the heat is exchanged, the third expansion space 17
Freezing at temperatures below 10K is achieved efficiently and with a simple mechanism.

Since the third regenerator is provided between the regenerative heat exchanger 15 and the second regenerator, during the process in which the temperature of the third expansion space 17 decreases from room temperature to about 15K, the third regenerator
Cold storage material such as lead in the cold storage device 13 and the third cold storage device 1
As shown in the graph shown in Figure 3, the working gas (helium gas) flowing in the third expansion space 17 utilized heat exchange due to the large heat capacity of lead (approximately 15 K or more), and refrigeration occurred in the third expansion space 17. The regenerative heat exchanger 15 can be cooled down to about 15K in a short time using the working gas, and as a result, refrigeration of 10K or less can be achieved in a short time.

Since there are no moving parts such as one-way valves or safety valves in the low-temperature part, there is less risk of failure.
Third expansion space 17 and storage type heat exchanger space 15b
Since it communicates with only through the aperture, the space 15
b does not become the dead volume of the space forming the refrigeration cycle. As a result, the dead volume of the space forming the refrigeration cycle can be reduced, improving the efficiency of the refrigerator. Space 1 of regenerative heat exchanger 15
5b forms a refrigeration cycle through the throttle, so when the operation of the refrigerator is stopped, the helium gas in the space of the regenerative heat exchanger 15 passes through the throttle 19 as the temperature rises to form the refrigeration cycle. Flow into the space where you want to be. As a result, the pressure in the space 15b of the regenerative heat exchanger 15 does not rise abnormally, and there is no need to provide a safety valve or the like in the regenerative heat exchanger.

FIG. 4 shows another embodiment of the invention. The spaces 15b of the regenerative heat exchanger 15 of the third regenerator 13 are communicated with each other through a communication pipe 46, an aperture 32, and a communication pipe 33, and the other configurations are the same as in FIG. 1.

FIG. 5 shows another embodiment of the invention. In the middle of the flow path 15a of the regenerative heat exchanger 15 and the space 15b
are communicated sequentially through a communication pipe 34, an aperture 35, and a communication pipe 36, and the other configurations are the same as those shown in FIG.

The operations in FIGS. 4 and 5 are similar to those in FIG. 1.

FIG. 6 shows another embodiment of the invention. Between the buffer space 47 and the space 15b of the regenerative heat exchanger 15, there is a communication pipe 37, a communication pipe 38 wrapped around the outer wall of the first regenerator 5, a communication pipe 39, and a communication wrapped around the outer wall of the second regenerator 9. The pipe 40, the communication pipe 41, the communication pipe 42 wrapped around the outer wall of the third regenerator 13, the communication pipe 43, the throttle 44, and the communication pipe 45 are made to communicate with each other, and the other configurations are the same as those in FIG.

To explain the operation shown in FIG. 6, the pressure in the buffer space 47 causes the space 15 of the regenerative heat exchanger 15 to
When the pressure b is low, the working gas in the buffer space 47 passes through the communication pipe 37 and flows into the communication pipe 38. The working gas flowing into the communication pipe 38 is cooled by the first regenerator 5, passes through the communication pipe 39, and flows into the communication pipe 40. The working gas that has flowed into the communication pipe 40 is
It is cooled by the regenerator 9 and flows into the communication pipe 42 through the communication pipe 41 . The working gas flowing into the communication pipe 42 is cooled by the third regenerator 42, and sequentially flows into the space 15b of the regenerative heat exchanger 15 through the communication pipe 43, the throttle 44, and the communication pipe 45.

When the pressure in the buffer space 47 is lower than the pressure in the space 15b of the regenerative heat exchanger 15, the helium gas in the space 15b of the regenerative heat exchanger 15 passes through the communication pipe 45, the throttle 44, and the communication pipe 43 in sequence. Then, it flows into the communication pipe 42. The working gas that has flowed into the communication pipe 42 is heated by the third regenerator 13 and flows into the communication pipe 40 through the communication pipe 41 . Communication pipe 40
The working gas that has flowed into the second regenerator is further warmed by the second regenerator and flows into the communication pipe 38 through the communication pipe 39 . The working gas flowing into the communication pipe 38 is further warmed by the first regenerator and flows into the buffer space 47 through the communication pipe 37 . Other operations are exactly similar to the implementation shown in FIG.

Similar to the embodiment shown in Fig. 1, the embodiment shown in Figs. 4 to 6 also has the effect that refrigeration of 10K or less occurs in the third expansion space in an extremely short time, and in the regenerative heat exchanger. Also, it is not necessary to install a safety valve, etc., and it is possible to provide an extremely efficient ultra-low temperature refrigerator.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of an ultra-low temperature refrigerator according to an embodiment of the present invention, FIG. 2a is an enlarged sectional view of a constriction part,
FIG. 2b is a graph showing changes in the working gas pressure (P ₁ ) in the third expansion space 16 and the working gas pressure (P ₂ ) in the space 15b in the regenerative heat exchanger, Figure 3 is a graph showing a comparison of the heat capacities of helium gas (working gas) and lead, and Figures 4~
FIG. 6 is a schematic sectional view showing another modified embodiment of the present invention. 15: Regenerative heat exchanger, 15a: Flow path, 15
b: Space inside the heat exchanger, 19: Aperture.

Claims (1)

[Claims] 1. In a refrigerator in which a compression space, a cooler, a regenerator, a regenerative heat exchanger, and an expansion space are connected in sequence, the space surrounding the outer wall side of the flow path of the regenerative heat exchanger and the compression space , which communicates with any one of the space in the regenerator, the flow path of the regenerative heat exchanger, the expansion space, and the buffer space through a restriction, and flows on the inner wall side of the flow path of the regenerative heat exchanger. The heat exchanger is characterized in that heat is exchanged between the working gas (helium gas) and the working gas (helium gas) on the outer wall side of the flow path of the regenerative heat exchanger through the wall forming the flow path. Ultra-low temperature refrigerator.