JPH04110569A - Gas cycle freezing device - Google Patents

Abstract

PURPOSE:To prevent vibration or noise from being generated, obviate a motor for driving a cam follower and prevent a complex and large-sized device from being attained by a method wherein a driving piston is connected to a cam mechanism, a plurality of cam followers are arranged at the cam mechanism in a displaced of predetermined angle to each other. CONSTITUTION:A displacer 11 is stored in a cylinder chamber 15 of a cylinder 14. A driving piston 12 is connected to a lower end. The driving piston 12 extends into a driving pressure chamber 20 and slidably supported through a driving bearing 27 A flange 17a of a flange member 17 is provided with a main cam follower 26 and a sub-cam follower 29 which are displaced and disposed by a predetermined angle displacement and they are disposed inside a cam frame member 25 in such a way as they may be contacted to it. Cam frame member 25, flange member 17, main and sub-cam followers 26, 29 constitute a cam mechanism. Since the driving piston 12 is connected to the cam mechanism, it is possible to prevent vibration or noise from being generated under a reciprocation of the displacer 11 and its striking against an inside an end surface of the cylinder 14. In particular, it is possible to eliminate a motor for driving the cam follower and to prevent a complex and large-sized device.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gas cycle refrigeration system, such as a gas cycle refrigeration system that is used in a cryopump (low-temperature vacuum pump) or the like to generate extremely low temperatures.

[Conventional technology]

Conventional gas cycle refrigeration systems are generally divided into two types: a GM cycle system in which the displacer is mechanically driven;
M that drives the displacer only by the pressure difference between both ends
-There is a crane bay cycle method.

An example of an M-Tsurubay cycle type refrigeration system is shown in FIG. 4. In the figure, the switching rotary valve 24 alternately switches between the high pressure side and the low pressure side of the compressor 22.
5 and the drive pressure chamber 20, the displacer 11 in the cylinder chamber 15 and the drive piston 12 connected to the upper end of the displacer 11 and protruding into the drive pressure chamber 20 are connected to the high pressure of the compressor 22. It is caused to reciprocate in the vertical direction by the pressure difference of low pressure.

Note that a regenerator 18 is housed inside the displacer 11, and the regenerator 18 communicates with the upper cylinder chamber 15 and the lower expansion chamber 15a of the displacer 11, so the interior of the cylinder 14 is completely the same. The high pressure and low pressure are separated by a seal member 19 interposed between the drive piston 12 and the structure 16. Therefore, due to the pressure difference between high and low pressure, the displacer 1
1 and the driving piston 12 connected thereto is a force equal to the pressure difference multiplied by the cross-sectional area of the driving piston 12.

[Problem to be solved by the invention]

However, in such a conventional M-Tsurubay cycle type gas cycle refrigeration apparatus, the displacer 11 reciprocates without mechanical connection, so the apparatus is simpler than the G-M cycle type. Although it has the advantage of being miniaturized, there is a problem in that it collides with the inner side of the end face of the cylinder 14, causing vibration and noise. In particular, vibration causes problems such as blurring of images when using a microscopic mirror, CCD (photoelectric conversion device), etc. in a vacuum chamber, and the problem that other work that is sensitive to vibration cannot be performed inside a vacuum chamber. occurs.

Therefore, it is an object of the present invention to solve the above problems.

[Means to solve the problem]

In order to solve the above problems, the present invention includes a displacer that lowers the temperature of the expansion chamber by being displaced, and a drive piston that is connected to the displacer and is integrally displaced. In a gas cycle refrigeration system that applies a driving force to displace a displacer by a pressure difference between a high pressure and a low pressure acting on the gas cycle, the driving piston is connected to a cam mechanism, and the cam mechanism is provided with a plurality of cam followers shifted by a predetermined angle from each other. It is made up of things like this.

[For production]

According to the gas cycle refrigeration system having such a configuration, the drive piston, which is connected to the displacer and is integrally displaced, is connected to the cam mechanism, so the displacer reciprocates with mechanical connection, which is different from the conventional method. It is possible to prevent the displacer from colliding with the inner side of the end face of the cylinder and causing vibration and noise.

Furthermore, by providing the cam mechanism with a plurality of cam followers shifted from each other by a predetermined angle, even if one cam follower is at the dead center position, the other cam follower is always at a position other than the dead center. Since a motor or the like for driving the cam follower is not required, it is possible to prevent the device from becoming complicated and large.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. Figures 1 to 3 show the gas cycle refrigeration system according to the present invention! It is a figure showing one example of this.

In the gas cycle refrigeration system shown in FIG.
is a displacer, and this displacer 11 is housed in a cylinder chamber 15 in a cylinder 14. A drive piston 12 is located at the lower end of the four-displacer 11 in the figure.
The drive piston 12 extends into a drive pressure chamber 20 separated from the cylinder chamber 15, and its intermediate and tip portions are slidably supported via a dry bearing 27. has been done.

The drive piston 12 is connected to a Scotch-shaped cam frame member 25 that operates within the drive pressure chamber 20, and a flange member 17 is provided near the cam frame member 25 via a bearing as shown in FIG. It is rotatably supported. A main cam follower 26 and a sub-cam follower 29 are implanted in the flange portion L7a of the flange member 17, and these cam followers 26 and 29 are arranged to be shifted from each other by a predetermined angle, and these cam followers 26 and 29 are in contact with the inside of the cam frame member 25. Possibly located. The tip of the driving piston 12 is fitted into a sliding hole 39, which communicates with the driving pressure chamber 20 and is always at the same pressure.

The cam frame member 25, flange member 17, main.

The secondary cam followers 26, 29 constitute a cam mechanism. One side (left side in FIG. 2) of the cam frame member 25 moves in contact with the structure 10 via a Teflon sheet 30, thereby preventing the drive piston 12 from rotating around it. .

A seal member 19 such as a rubber O-ring is interposed between the displacer 11 and the cylinder 14, and a similar seal member 19 is provided between the drive piston 12 and the elliptical body.
is interposed.

Inside the displacer 11, a regenerator 18 is housed, which is made by stacking a large number of multi-surface area members such as copper gold IL#iW or filled with fine copper metal particles. The displacer 11 communicates with the cylinder chamber 15 at both upper and lower ends. The upper end portion of the cylinder chamber 15 is an expansion chamber 15a, which is a portion where extremely low temperatures can be generated by the vertical and reciprocating movement of the displacer 11.

A compressor (not shown) is installed at the lower side of the elliptical corpse 16 in the figure.
The high-pressure side and low-pressure side of the valve are connected by piping, and a switching rotary valve 24 driven by a motor 23 is provided near the connection. The switching rotary valve 24 alternately communicates the high pressure side and the low pressure side of the compressor with the cylinder chamber 15 and the drive pressure chamber 20 by its switching operation.
The cylinder chamber 15 and the drive pressure chamber 20 are alternately switched between high pressure PH and low pressure Pt.

In an actual example of a gas cycle refrigeration system as shown in 2.
Due to the operation of the switching rotary valve 24, the cylinder chamber 15
By alternately switching between high pressure PH and low pressure P[ in the drive pressure chamber 20 and the drive pressure chamber 20, the displacer 11 moves the drive piston 12,
It reciprocates in the vertical direction in the figure integrally with the cam frame member 25. When the displacer 11 moves downward, the high-pressure refrigerant scum in the lower part of the cylinder chamber 15 enters the regenerator I8, and is cooled to some extent by the regenerator 18, while the expansion chamber
5a. Then, the refrigerant scum is further cooled by adiabatically expanding to a low pressure. Displacer 1
1 moves upward, the low-pressure refrigerant gas in the expansion chamber 15a enters the regenerator 18 and moves to the lower part of the cylinder chamber 15 while further cooling the regenerator 18. This! ! By returning the expansion chamber 15a, the expansion chamber 15a can be cooled in stages to reach an extremely low temperature, and can be used as a cryopump or the like.

Further, a cam frame member 25 is connected to the middle of the drive piston 12, and inside the cam frame member 25, a main cam follower 26 is implanted in the flange portion 17a of the flange member 17 and rotates integrally with the cam frame member 25. and secondary cam follower 2
9 is inserted, the movements are performed in the following order.

First, in FIG. 3(a), the rotation center B of the flange member 17 and the axial center A of the main cam follower 26 are both on the axis of the drive piston 12, and the main cam follower 26 is positioned relative to the cam frame member 25. It is related to the top dead center position. In this case, if there is no sub-cam follower 29, as shown in Fig. 5(a).
Even if the Scotch choke 41 attempts to move downward in the drawing due to the force F, the follower 44 cannot rotate around the center of rotation B, and as a result, the Scotch choke 41 cannot also move downward in the drawing. Such a case can be solved by connecting the rotating shaft of the flange member 17 to the motor 31 and driving it, as shown in FIG. 5(b). However, in the embodiment of the present invention described above, since the sub cam follower 29 is provided in addition to the main cam follower 26,
The problem can be solved without providing such a motor 31.

That is, when the cam frame member 25 is slightly lowered from the state shown in FIG. 3(a), the cam frame member 2 is lowered as shown in FIG. 3(b).
5 contacts the sub-cam follower 29 and presses it downward. At this time, the axial center of the sub-cam follower 29 is slightly shifted from the axis of the drive piston 12, which is coincident with the rotation center B of the flange member 17 and the center A of the main cam follower 26, so the sub-cam follower By pressing the tree 29, the sub cam follower 29 can be lowered, that is, the flange member 17 can be rotated.

When the flange member 17 rotates a little, the main cam follower 26 comes into contact with the upper side of the cam frame member 25 and presses it downward, as shown in FIG. 3(c). At this time, since the axial center A of the main cam follower 26 is slightly shifted from the axis of the drive piston 12 where the rotation center B of the flange member 17 is located, the main cam follower 26 can be lowered by pressing. The flange member 17 rotates.

Then, when the main cam follower 26 comes to the position shown in FIG.
), the flange member 17 rotates further, and when the flange member 17 reaches the position shown in the figure (f>), the sub cam follower 2
9 is located on the axis of the drive piston 12 and coincides with the center B of the flange member 17.
When the main cam follower 26 rotates, as shown in FIG.

When the cam frame member 25 rises, it operates in the same way, and the sub cam follower 29 and the main cam follower 26
The rotation of the flange member 17 and the reciprocating movement of the cam frame member 25 can be performed smoothly. Since the drive piston 12 is thus connected to the cam frame member 25 of the cam mechanism and moves integrally, further movement is restricted at both the top dead center and bottom dead center positions of the main cam follower 26. Therefore, as in the conventional case, the displacer 11 is connected to the cylinder 14.
Collision with the inner side of the end face 1. This can prevent vibrations and noise from occurring.

Further, in the embodiment of the present invention, the main cam follower 2
Since the sub cam follower 29 is provided in addition to the cam follower 6, the drive piston 12 and the cam frame member 25 cannot be moved at the top or bottom dead center even if a motor is not provided to connect to the rotating shaft of the flange member 17 and drive it. This can be reliably prevented. Therefore, it is possible to prevent the device from becoming more complicated and larger.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to prevent the displacer from colliding with the inner side of the end face of the cylinder one by one and causing vibration and noise as in the conventional case. In addition, even if one cam follower is at the dead center, the other cam follower is always at a position other than the dead center, so a motor or the like is not required to drive the cam follower. Complication and enlargement can be prevented.

[Brief explanation of the drawing]

1 to 3 are diagrams showing an embodiment of a gas cycle refrigeration system according to the present invention, in which FIG. 1 is a sectional view of the gas cycle refrigeration system, FIG. 2 is a side sectional view of the vicinity of the cam mechanism,
Figures 3 (a) to (g) are diagrams showing the operation of the cam mechanism in order, Figure 4 is a schematic diagram of a conventional gas cycle refrigeration system, and Figure 5 (a) is a front view of a conventional Scotchoke mechanism. FIG. 3B is a side view thereof. 11... Displacer 12... Drive piston 15...
Cylinder chamber 15a...Expansion chamber 17...Flange member 25...Cam frame member 26...Main cam follower 29...Sub-cam follower Patent Applicant Seiko Seiki Co., Ltd. Representative Patent Attorney Keinosuke Hayashi Side sectional view of the compressor cam mechanism Figure 2 (Cl) Figure 3 (b) showing the operation of the cam mechanism Figure 3 showing the operation of the cam mechanism Schematic diagram of a conventional refrigeration system Fig. 4, -2] Diagram showing a conventional Scotchoke mechanism Fig. 5

Claims (1)

[Claims] A drive device that includes a displacer that makes an expansion chamber at a low temperature by being displaced, and a drive piston that is connected to the displacer and is integrally displaced, and that displaces the displacer by a pressure difference between a high pressure and a low pressure that act on both ends of the drive piston. In gas cycle refrigeration equipment that provides power,
A gas cycle refrigeration system characterized in that the drive piston is connected to a cam mechanism, and the cam mechanism is provided with a plurality of cam followers shifted from each other by a predetermined angle.