JPH0480311B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an improvement of a valve device for a cryogenic refrigerator using the Gifford-McMahon cycle.

(Prior Art) A cryogenic refrigerator using the Gifford-McMahon cycle requires a valve that switches the pressure in the working gas space between high pressure and low pressure in order to generate refrigeration.

For example, this type of valve is
Rotary valve disclosed in No. 28623, JP-A-58
Although various valves have been proposed, such as the slide valve disclosed in Japanese Patent Application No. 190663, poppet valves are generally used because of their sealing performance, reliability, etc.

An example of the configuration of a conventionally used poppet valve is shown in FIGS. 5 and 6. Motor (not shown)
The crankshaft 19 is driven by a crank pin 20 for driving a piston (not shown).
The crank pin 20 has eccentric cam disks 21 and 22 attached at a predetermined phase angle. Eccentric cam discs 21 and 22 are each connected to a high pressure valve device 2.
3 and the low-pressure valve device 24, and control the opening and closing of the valve devices 23 and 24 at relative timing θ determined by the eccentric positions of the eccentric cam discs 21 and 22. This generates the required refrigeration. That is, in the prior art, the relative opening/closing timing of the high-pressure valve device 23 and the low-pressure valve device 24 depends on the eccentric angle formed by precision machining of the crank.

(Problems to be Solved by the Invention) In the case of the conventional technology, since two eccentric discs are used, there are three centers: the rotation center of the crank, the center of the first eccentric cam disc, and the center of the second eccentric cam disc. exists. The linearity of these three centers affects the cycle angle. In other words, three eccentric machinings are required,
The processing process becomes complicated. In addition, the amount of eccentricity of the eccentric cam disk is small, generally in the range of 1 to 3 mm, and the machining error at the center position is amplified on the outer periphery, so the allowable range of eccentricity error is extremely strictly controlled. There is a problem in that it is difficult to maintain accuracy between the center of rotation and the valve axis.

An object of the present invention is to provide a highly accurate valve device for a cryogenic refrigerator that does not have the above-mentioned problems.

[Structure of the invention]

(Means for Solving the Problems) The valve device of the cryogenic refrigerator of the present invention relatively opens and closes at a timing determined by one eccentric cam member having its rotation center on the crank, and operates in a working gas space. The first and second valve devices are arranged to switch the internal pressure between high pressure and low pressure, and the first and second valve devices are respectively connected to the outer circumferential cam surface of the eccentric cam member by spring pressure. A slider that is in contact with the outer peripheral cam surface and can be driven by the outer cam surface is formed with an inlet passage and an outlet passage for the working gas, and guides and holds the slider so that the slider can move the inlet passage and the outlet passage. The housing part is characterized in that it has a housing part in which the parts are interrupted.

In the present invention, since only one eccentric cam disk is used to drive the high-pressure valve device and the low-pressure valve device, the drive system has two rotation centers, which makes it easy to achieve linearity and easy machining. , it is easy to obtain the required precision of the crank rotation center and valve axis.

The eccentric cam member here refers to, for example, a single eccentric cam disk having its rotation center on a crank driven by a motor as a driving source.

The first valve device is, for example, a device that includes an on-off valve that controls the flow of high-pressure fluid in a working gas space of a refrigerator. These valve devices are comprised of a housing in which a working gas inlet and outlet are formed, a spring held in the interior space of the housing, and a valve that is a slider pressed by the spring.

The slider is configured to appropriately contact the outer circumferential cam surface of the eccentric cam member and follow the cam surface under the action of spring pressure.

The second valve device is, for example, a device including an on-off valve that controls the flow of low-pressure fluid in a working gas space of a refrigerator. Similar to the first valve device described above, there is provided a housing in which an inlet passage and an outlet passage for a working gas, which is a fluid, are formed, a spring held within the internal space of this housing, and a direction in which the spring protrudes outside the housing. It consists of a slider that acts as a pressurized valve. slider,
That is, the valve is configured to appropriately contact and follow the outer circumferential cam surface of the eccentric cam member under the action of spring pressure.

High-pressure fluid refers to the high pressure supplied by the high-pressure fluid source in the Gifford-McMahon cycle mentioned above.
Refrigeration fluid with Ph.

Low pressure fluid refers to the expanded and cooled working fluid that is introduced into the low pressure reservoir in the Gifford-McMahon cycle.

A pair of lever-like members installed between the first valve device, the second valve device, and the outer peripheral surface of the eccentric cam member are arranged so that the position of the fulcrum can be changed by rotating the free ends of the lever-like members. This is the lever that is used. That is, by adjusting the rotational position of the lever, it is possible to change the protrusion amount or stroke of each slider of each valve device that comes into contact with the lever-like member. Therefore, the relative opening/closing timing of both valve devices can be arbitrarily selected.

(Operation) By the rotation of a single eccentric cam member, the low pressure valve device and the high pressure valve device that are in contact with the outer circumferential surface of this cam member operate at predetermined relative opening/closing timing, thereby opening the fluid introduction path and the fluid outlet path. Control opening and closing.
This controls the flow of high-pressure fluid and low-pressure fluid in order to function the cryogenic refrigerator using the Gifford-McMahon cycle. In the conventional technology, if the eccentricity of the eccentric cam member is 2mm, in order to guarantee an angular error of 1 degree, the eccentricity error must be kept within the range of 0.035mm, but according to the configuration of the present invention, the valve mounting part is connected to the crankshaft. Assuming that it is 50mm away from the center, a position error of 0.87mm is allowed.

(Embodiments of the invention) (First embodiment) A front view of a first embodiment of a valve device for a cryogenic refrigerator according to the present invention is shown in Fig. 1, and a left side view of the same is shown in Fig. 2.
As shown in the figure. A crank 2 having a shaft 1 (FIG. 2) driven by a motor (not shown) rotates an eccentric cam disk 3 for opening and closing a valve, maintains a correlation with a crank pin 4, and opens a first valve. A high-pressure valve device 5, which is a device, and a low-pressure valve device 6, which is a second valve device, are driven. The high-pressure valve device 5 has a housing 9 in which a fluid inlet passage 7 and a fluid outlet passage 8 are bored, and a slider 11 is pushed into the housing 9 by a spring 10 in a direction that projects outward from the housing 9. I did it like that. The tip of the slider 11 was in contact with the outer peripheral surface of the eccentric cam disc 3 for approximately half the circumference, and was kept in contact with the outer peripheral surface as appropriate.

The low-pressure valve device 6 has a housing 14 in which a fluid inlet passage 12 and a fluid outlet passage 13 are bored. I made it possible to do so. The tip of the slider 16 is connected to the eccentric cam disk 3
The contact surface was made to contact the outer circumferential surface for approximately half the circumference, and to maintain an appropriate contact state with this outer circumferential surface.

A high-pressure valve device 5 and a low-pressure valve device 6 are arranged in opposing positions with an eccentric cam disc 3 interposed therebetween. As a result, the relative timing between the high pressure valve device 5 and the low pressure valve device 6 is made to correspond to the cycle angle (θ) determined by the amount of deviation (d) between the valve mounting position and the center of the crank 2. I made it.

(Second Embodiment) FIG. 3 is a front view of a second embodiment of the valve device for a cryogenic refrigerator according to the present invention, and FIG. 4 is a left side view of the same.
As shown in the figure.

In this embodiment, unlike the first embodiment described above, the swingable levers 17 and 18 are replaced by the valve device 5,
6 and the outer peripheral surface of the eccentric cam disk 3.
Therefore, in this embodiment, the relative opening/closing timing (θ) of the high pressure valve device 5 and the low pressure valve device 6 and the fulcrum position of the lever-like member can be changed without replacing the crankshaft or changing the mounting position of the valve. It can be changed by simply That is, each sliding portion 11 of the valve device 5, 6 can be adjusted without changing the crank 1.
The stroke or relative timing of 16 is variable.

〔Effect of the invention〕

According to the valve device of the cryogenic refrigerator of the present invention,
A single eccentric cam member can open and close the high pressure valve device and the low pressure valve device, and the configuration is simple.
Furthermore, the relative opening/closing timing of both valve devices is determined by the position where the valve devices are installed, not by the eccentric angle determined by precision machining of the crank, so machining is easy and it is easy to achieve valve timing accuracy. Further, according to a modified embodiment of the present invention, the high pressure valve device and the low pressure valve device can be connected by simply changing the fulcrum position of the lever-like member without replacing the crankshaft or changing the mounting position of the valve device. The relative opening/closing timing with the valve device can be adjusted.

[Brief explanation of the drawing]

FIG. 1 is a front view of a first embodiment of the present invention, and FIG. 2 is a left side view of the first embodiment of the present invention. FIG. 3 is a front view of the second embodiment of the invention, and FIG. 4 is a left side view of the second embodiment of the invention. 5 and 6 are a front view and a left side view of the conventional device. 2... Crank, 3... Eccentric cam disk, 5... First valve device (high pressure valve device), 6... Second valve device (low pressure valve device), 9, 14... Housing, 11, 16... Slider , 10, 15... spring,
7,12...Introduction path, 8,13...Output path, 17,1
8...Lever-shaped member.

Claims (1)

[Scope of Claims] 1. In a cryogenic refrigerator using the Gifford-McMahon cycle, an eccentric cam member having its rotation center on the crank opens and closes relative to each other at a timing determined by the eccentric cam member. The first and second valve devices are arranged to switch the pressure between high pressure and low pressure, and the first and second valve devices are respectively brought into contact with the outer circumferential cam surface of the eccentric cam member by spring pressure, and A slider that can be driven by an outer peripheral cam surface and an introduction path and an outlet path for the working gas are formed, and the slider is guided and held, and the introduction path and the outlet path are interrupted by the slider. A valve device for a cryogenic refrigerator, characterized in that it has a housing portion. 2. The valve device for a cryogenic refrigerator according to claim 1, wherein the first valve device and the second valve device have variable relative opening and closing timings by changing the valve mounting positions. 3. Claim 1, wherein a pair of lever-like members whose fulcrum positions are variable are disposed between the first valve device, the second valve device, and the outer peripheral surface of the eccentric cam member. The valve device of the cryogenic refrigerator described above.