JPH0621724B2 - Air supply / exhaust device for cryogenic refrigerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention includes a compression device and a refrigeration cycle such as a Gifford McMahon cycle, a Solvay cycle, and the like, and is an extremely low temperature refrigerator used for obtaining extremely low temperature refrigeration. Of the air supply and exhaust system.

(B) Conventional technology This type of conventional cryogenic refrigerator is a "vacuum technical manual".
(Published on July 30, 1983 by Sangyo Tosho Co., Ltd., P22
0) (see FIG. 7), cylinder 1
A displacer 2 that reciprocates up and down in the cylinder 1, a buffer space 3 (first variable volume space) and an expansion space 4 (second variable volume space) that are partitioned and formed inside the cylinder 1 by the displacer 2. ), A gas passage 5 penetrating the displacer 2 and connecting the buffer space 3 and the expansion space 4, a regenerator 6 arranged in the gas passage 5, and a working gas such as helium gas is compressed. A compression device 7 and a supply / exhaust device 11 for alternately connecting the supply / exhaust port 8 of the cylinder 1 to the high-pressure line 9 and the low-pressure line 10 of the compression device 7 are provided.
And the exhaust valve 13 are used. Also, cylinder 1
A load 16 is connected to the cold head 14 via a heat transfer member 15.

In the cryogenic refrigerator described above, the displacer 2 is the cylinder 1
At the lowest position (top dead center), the air supply valve 12 is opened, the exhaust valve 13 is closed, and the working gas pressurized by the compression device 7 flows into the buffer space 3. Then, in the process in which the displacer 2 moves from the lowest position to the highest position (bottom dead center) in the cylinder 1, the working gas in the buffer space 3 is allowed to flow into the expansion space 4 while being cooled by the regenerator 6 in the gas flow path 5. . In addition, as the displacer 2 moves, the expansion space 4
The volume of is increasing. Displacer 2 is cylinder 1
When it is at the uppermost position, the air supply valve 12 is closed and the exhaust valve 13 is opened. Therefore, the working gas is expanded in the expanded air 4 and cold is generated. Then, in the process in which the displacer 2 moves from the top to the bottom, the working gas in the expansion space 4 flows through the gas flow path 5 while cooling the regenerator 6, and further passes through the buffer space 3 and the exhaust valve 13 to the low pressure line 10. Exhausted to. By repeating the above, the cold head 14 of the cylinder 1 is cooled, and the load 16 is given extremely low temperature.

(C) Problems to be Solved by the Invention In the cryogenic refrigerator described above, the air supply valve 12 of the air supply / exhaust device 11
A poppet valve is often used as the exhaust valve 13. As described above, the method of using the two poppet valves has an advantage that the supply / exhaust timing can be freely set so that the refrigerating capacity is efficiently exhibited. However, since it is a system in which the valve body collides with the valve seat, there is a drawback that the impact force becomes large when the stroke is made sufficiently large. For this reason, there is a problem that fine adjustment in micron units is required at the time of assembly, the assembly becomes troublesome, and the valve seat is easily worn (particularly worn out).

Further, as disclosed in Japanese Patent Application Laid-Open No. 60-213777, when a supply / exhaust device using one spool valve is used to supply / exhaust a working gas, a high-pressure port communicating with a high-pressure line of a compression device. And a medium pressure port communicating with the air supply / exhaust port of the cylinder, and further, a medium pressure port and a low pressure port communicating with the low pressure line of the compressor must be provided close to each other, and a sufficient sealing area cannot be obtained. Therefore, the resistance against leakage of the working gas is weak and there is a problem in reliability.

Furthermore, in the air supply / exhaust device using a rotary valve as disclosed in Japanese Patent Laid-Open No. 60-138369, the pressing force against the valve sliding surface due to the pressure difference of the working gas is large, and the reliability against wear is poor. It was a thing.

This invention has been made in view of the above facts,
An object of the present invention is to provide a supply / exhaust device for a cryogenic refrigerator in which supply / exhaust timing can be freely adjusted and which is highly reliable against wear and leakage of working gas.

(D) Means for Solving the Problems The present invention relates to a cylinder, a displacer that reciprocates in the cylinder, first and second variable volume spaces partitioned and formed in the cylinder by the displacer, and Cryogenics consisting of a regenerator arranged in the gas flow path that connects the variable volume space, a compression device, and a supply / exhaust device that alternately connects the supply / exhaust port of the cylinder to the high pressure line and the low pressure line of the compression device This is to improve the air supply / exhaust system of a refrigerator.

The cryogenic refrigerator air supply / exhaust device of the present invention has a pair of spool valve bodies that reciprocate while maintaining a predetermined phase difference, and two cylindrical voids that slidably hold these spool valve bodies. ,
And these tubular voids are connected to the air supply and exhaust ports of the cylinder, and one tubular void is connected to the high pressure line of the compressor.
And a pair of guides each having a connecting path for connecting the other cylindrical space to the low-pressure line of the compressor.

(E) Action With this configuration, since the communication control between the high pressure line and the air supply / exhaust port and the communication control between the air supply / exhaust port and the low pressure line are performed by different spool valve elements, the timing of the air supply / exhaust is paired. It is possible to freely set the spool valve body of each. Further, since the stroke of each spool valve element can be made sufficiently long, it is not necessary to finely adjust the supply / exhaust timing at the time of assembly, and the assembly becomes easy. Furthermore, since the sealing area between the spool valve element and the wall surface of the tubular space that guides it can be made large in the axial direction, leakage of the working gas can be minimized, and the spool valve element can receive a force other than sliding friction force. Since it is not added, it is resistant to wear and reliability can be improved.

(F) Embodiment An embodiment in which the present invention is applied to the cryogenic refrigerator shown in FIG. 2 will be described in detail below with reference to the drawings.

FIG. 1 shows an air supply / exhaust device according to an embodiment of the present invention. In FIG. 1, a through hole 1 is provided at both ends of the motor 17.
End cover 2 having 8, 19 and through holes 20, 21 respectively
2, 23 are provided, and the permeate 18 communicates with the low pressure line 9 of the compression device 7. Further, the hermetic terminal of the motor 17 is inserted into the through hole 19. A crankcase 24 is connected to the end cover 23, and a partition wall 25 with the cylinder 1 is attached to the lower side of the crankcase 24. Three crank pins 27, 28, 29 fixed eccentrically to the motor shaft 26 are disposed inside the crank case 24, and ball bearings 30, 31 are provided on the outer circumferences of these crank pins 27, 28, 29, respectively. , 32 are attached. A guide body 40 having two cylindrical cavities 33 and 34 and connecting paths 35 to 39 is integrally formed on the lower portion of the crankcase 24. And the cylindrical void 3
3, 34 are connected to the air supply / exhaust port 8 of the cylinder 1 via the communication passages 37, 38 and the communication passage 41 formed in the partition wall 25, and the cylindrical space 34 is compressed via the communication passages 35, 36. It is connected to the high pressure line 9 of the device 7, and the cylindrical space 33 is connected to the low pressure line 10 of the compression device 7 via the connection passage 39, the inside of the crankcase 24, the through holes 20 and 21, the motor 17 and the through hole 18. ing. Spool valve bodies 44 and 45 having circumferential grooves 42 and 43 are slidably accommodated in the cylindrical cavities 33 and 34, respectively. These spool valve bodies 4
4 and 45 are springs 4 at the ends on the partition wall 25 side.
The other end is always in contact with the ball bearings 31, 32 by being pressed by 6, 47. Further, the ball bearing 30 is connected to the shaft 49 of the displacer 2 via the guide 48.

The operation of the above-described embodiment is shown in FIG. 2 (a) (b) (c) to FIG.
This will be explained with reference to (a), (b) and (c). 2 (a) (b) (c) to FIG. 6 (a) (b) (c), A is the locus of the center of the crank pin 27, and B (C) is the center of the crank pin 28, 29. The locus is shown.

Now, when the center of the crank pin 27 is located at the position indicated by A1 in FIG. 2 (a), the centers of the crank pins 28 and 29 are located at positions B1 and C1 in FIG. 2 (b), respectively. At this time, the spool valve elements 44 and 45 are in the state shown in FIG.
The spool valve element 44 moves upward and the spool valve element 45 moves downward. Further, the high pressure line 9 of the compression device 7 and the air supply / exhaust port 8 of the cylinder 1 and the air supply / exhaust port 8 and the low pressure line 10 of the compression device 7 are shut off by the spool valve elements 44, 45. There is.

When the center of the crank pin 27 moves slightly clockwise and the displacer 2 approaches the lowest position (top dead center), the air supply / exhaust device enters the air supply area. In this air supply area, for example, when the center of the crank pin 27 is at the position A2 in FIG. 3 (a), the centers of the crank pins 28 and 29 are B in FIG. 3 (b).
It is located at position 2, C2. At this time, the spool valve element 44 still moves upward, and the spool valve element 45 reverses upward. Further, as shown in FIG. 3 (C), the spool valve body 4
Since the circumferential groove 42 of 4 is separated from the communication passages 37 and 39, and the circumferential groove 43 of the spool valve element 45 coincides with the communication passages 35 and 37, the high pressure line 9 of the compressor 7 is connected to the communication passages 36 and 35 and the cylinder. Cylinder 1 via the space 34 and the connecting paths 37, 38
The working gas is supplied to the inside of the cylinder 1 by communicating with the air supply / exhaust port 8.

When the center of the crank pin 27 is located at the position A3 in FIG. 4 (a), the centers of the crank pins 28 and 29 are respectively shown in FIG.
It is at the position indicated by B3 and C3 in (b). At this time, the spool valve element 44 is moving downward and the spool valve element 45 is moving upward. Further, as shown in FIG. 4C, the spool valve body 45 is disconnected from the connecting passages 35 and 37 of the circumferential groove 43 of the spool valve body 45, so that the high pressure line 9 and the air supply / exhaust port 8 are blocked by the spool valve body 45. And the circumferential groove 4 of the spool valve element 44.
Since 2 is separated from the communication paths 37 and 39, the air supply / exhaust port 8 and the low pressure line 10 are also cut off. In such a fully closed state, the center of the crank pin 27 is at the position A4 in FIG. 5 (a), and the centers of the clamp pins 28 and 29 are in FIG. 5 (b).
B4, C4 position of the spool valve body 4
It continues until 4, 45 move to the position of FIG.

When the clamp pins 27, 28, 29 are moved slightly clockwise from the positions shown in FIG. 5 and the displacer 2 approaches the uppermost position (bottom dead center), the air supply / exhaust device enters the exhaust area. In this exhaust region, for example, the center of the clamp pin 27 is shown in FIG.
When it is at the position A5 in (a), the centers of the crank pins 28 and 29 are at the positions B5 and C5 in FIG. 6 (b). At this time, the spool valve body 44 is reversed upward, and the spool valve body 45 is moving downward. Further, as shown in FIG. 6C, the circumferential groove 42 of the spool valve element 44 is connected to the connecting passages 37, 3
9 and the circumferential groove 43 of the spool valve body 45 is connected to the communication path 3
It is far from 5,37. Therefore, the air supply / exhaust port 8 of the cylinder 1 has the communication paths 41, 38, 37, the cylindrical cavity 33, the communication path 39, the inside of the crankcase 24, the through holes 20, 21,
The working gas in the cylinder 1 is exhausted by being communicated with the low pressure line 10 of the compression device 7 through the motor 17 and the through hole 18. By repeating the above-described operation, the air supply / exhaust device allows the air supply / exhaust port 8 to communicate with the high pressure line 9 and the low pressure line 10 alternately.

According to this embodiment, the communication control between the high pressure line 9 and the air supply / exhaust port 8 and the communication control between the air supply / exhaust port 8 and the low pressure line 10 are performed by the separate spool valve elements 45 and 44. The spool valve body 4 controls the timing of gas supply and exhaust.
5, 44 can be freely set, and the refrigerating capacity of the cryogenic refrigerator can be efficiently exhibited. That is, the air supply is started before the displacer 2 reaches the lowest position (top dead center) (30 ° in phase angle), and the displacer 2 reaches the highest position (bottom dead center) (30 in phase angle). Before starting the exhaust, prevent the efficiency from decreasing due to the delay of the flow of the working gas, and provide a 30 ° full-closed region when switching from the supply to the exhaust, which affects the refrigeration capacity too much. Therefore, the input of the compression device 7 can be significantly reduced. Further, since the strokes of the spool valve bodies 44 and 45 can be made sufficiently long, the work of finely adjusting the supply / exhaust timing at the time of assembly is unnecessary. Further, since the sealing area between the spool valve bodies 44, 45 and the cylindrical cavities 33, 34 of the guide body 40 can be made large in the axial direction, the leakage of the working gas can be extremely reduced. Furthermore, the force applied to the spool valve elements 44 and 45 is only sliding frictional force, wear of the spool valve elements 44 and 45 and the guide element 40 can be reduced, durability can be improved, and the power of the motor 17 can be reduced. You can also

(G) Effect of the Invention Since the present invention is configured as described above, the timing of supply and exhaust can be freely set, the refrigerating capacity can be efficiently exhibited, and further, wear of the valve body and the like The working gas leaks very little, the reliability is improved, the assembly is easy, and the power is small.

[Brief description of drawings]

FIG. 1 is a sectional view of an air supply / exhaust device for a cryogenic refrigerator showing an embodiment of the present invention, and FIGS. 2 (a) (b) (c) through 6 (a) (b).
(C) is an operation explanatory view of the air supply / exhaust device of the present invention, and FIG. 7 is a piping system diagram showing an example of a cryogenic refrigerator to which the present invention is applied. 1 ... Cylinder, 2 ... Displacer, 3 ... Buffer space (first variable volume space), 4 ... Expansion space (second variable volume space), 5 ... Gas flow path, 6 ... Regenerator ,
7 ... Compressor, 8 ... Air supply / exhaust port, 9 ... High pressure line,
10 ... Low pressure line, 11 ... Air supply / exhaust device, 33, 34
...... Cylindrical space (cylindrical space) 35-39 ...... Connecting path,
40 ... Guide body, 44, 45 ... Spool valve body.

Claims (1)

[Claims] 1. A cylinder, a displacer that reciprocates in the cylinder, and first and second variable volume spaces partitioned and formed inside the cylinder by the displacer.
It consists of a regenerator arranged in a gas flow path that connects these variable volume spaces, a compression device, and a supply / exhaust device that alternately connects the supply / exhaust port of the cylinder to the high pressure line and the low pressure line of the compression device. In the cryogenic refrigerator, the air supply / exhaust device includes a pair of spool valve bodies that reciprocate while maintaining a predetermined phase difference,
It has two cylindrical voids that slidably hold these spool valve elements, and these tubular voids are connected to the air supply / exhaust port of the cylinder, and one of the tubular voids is connected to the compression device. A supply / exhaust device for a cryogenic refrigerator, comprising: a high-pressure line; and a guide body having a connecting path that connects the other tubular space to the low-pressure line of the compressor.