JP2617681B2 - Cryogenic refrigeration equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cryogenic refrigeration apparatus using a Gifford McMahon (GM) cycle or the like, and in particular, a cryogenic refrigeration apparatus having a function of raising a cooling unit in a cryogenic state to room temperature. According to.

For example, in a cryopump using a Gifford-McMahon cycle cryogenic refrigerator, when raising the temperature of the cooling part to room temperature, dry nitrogen gas was introduced into the conventional vacuum tank, or an electric current was passed through a heater equipped with the cooling part. The method of raising the temperature by Joule heat generated by
Each of these methods requires some special equipment and has a drawback that the panel temperature does not rise quickly.

Therefore, a method of raising the temperature by reversely rotating the drive motor of the refrigerator to reversely operate the refrigeration cycle was proposed in U.S. Pat.No. 4,520,630, but this method is based on the phase of the displacer and the opening and closing timing of the valve in the heating mode operation. However, there is a problem that a sufficient temperature raising effect cannot be obtained.

DISCLOSURE OF THE INVENTION An object of the present invention is to use a method for reverse operation of a refrigeration cycle in a cryogenic refrigerator using a Gifford McMahon (GM) cycle without using special equipment for raising the temperature of a cooling unit. Another object of the present invention is to provide a cryogenic refrigerator capable of shortening the time required for raising the temperature of the cooling unit to room temperature.

In order to achieve the above object, in the present invention, at least one cylinder, at least one displacer having a regenerator inside and reciprocating in the cylinder, and an outer portion of both ends of the displacer The upper and lower vacancies provided in the cylinder and communicating with each other via a regenerator inside the displacer, and the flow of high-pressure refrigerant gas to the vacancy and low-pressure refrigerant gas from the vacancy A rotary valve device for controlling, and a reversible motor for controlling the reciprocation of the displacer while rotating the rotary valve device forward and backward, and a refrigerant in the lower chamber when the rotary valve device rotates forward. The gas is adiabatically expanded to generate cold, and when the rotary valve device rotates in the reverse direction, the refrigerant gas is adiabatically compressed in the lower chamber to generate heat. Gifford was so as to produce
In the McMahon cycle type cryogenic refrigerator, means is provided for differentiating the opening / closing timing of the rotary valve device with respect to the reciprocating motion of the displacer between forward rotation and reverse rotation.

In a preferred embodiment of the present invention, the rotary valve device comprises a fixed valve body and a valve plate rotatably supported in surface contact with the valve body,
Means for differentiating the opening / closing timing of the rotary valve device with respect to the reciprocating movement of the displacer during normal rotation and during reverse rotation is an engagement groove formed on the back surface of the valve plate and extending in the circumferential direction over a predetermined angle, A pin portion provided on a crank driven by the reversible motor and engaging with an engagement groove of the valve plate. Thus, when the crank is rotated forward or backward, the pin portion is connected to one end of the engagement groove. Alternatively, the valve plate is idled without rotating until it engages with the other end.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of a Gifford-McMahon cycle refrigerator according to the present invention, and FIG. 2 is a valve plate of a rotary valve device used in the refrigerator, taken along line II-II in FIG. FIG. 3 is an exploded perspective view of a drive mechanism for a valve plate and a scotch yoke, FIG. 4 is an exploded perspective view of a valve plate and a valve body constituting a rotary valve device, and FIG. 5 is a conventional Gifford McMahon cycle. FIG. 6 is a motor connection wiring diagram of the refrigerator, and FIG. 6 is a motor connection wiring diagram of the Gifford-McMahon cycle refrigerator according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION In FIG. 1, a compressor 1 sucks a refrigerant gas from a low pressure side 1a, increases the pressure, cools it, and discharges it to a high pressure side 1b.

The refrigerator 2 is divided into a housing part 23 and a cylinder part 10. Cylinders 10a, 10b arranged in two stages above and below,
Integrated displacers 3a, 3b with built-in regenerators 4 and 5 are slidably provided, and a vacant chamber 11 (first stage lower vacant chamber) between the displacers 3a, 3b and the cylinders 10a, 10b. ),
12 (second stage lower room) and 13 (upper room) are formed.
The vacancies 11, 12, and 13 are connected to each other by displacers 3a and 3b containing regenerators 4 and 5 by cooling channels L1 to L4. In addition, flanges 6 and 7 are closely attached to the outer periphery of the lower portions of the cylinders 10a and 10b in a heat conductive relationship.

Displacers 3a and 3b are connected to scotch yoke 22 supported by sliding bearings 17a and 17b, and driven by reversible motor 15, crank 14, and scotch yoke 22 to form a cylinder.
Reciprocates in 10a and 10b. When the volumes of the vacant chambers 11 and 12 in the cylinders 10a and 10b increase with the reciprocating movement of the displacers 3a and 3b, the volume of the vacant chamber 13 decreases, and when the volumes of the vacant chambers 11 and 12 decrease, the vacant chamber The volume of 13 changes so as to increase, and the refrigerant gas moves between the cavities 11, 12, and 13 through the refrigerant channels L1 to L4.

A rotary valve device RV that controls the flow of the refrigerant gas is arranged between the compressor 1 and the cylinders 10a and 10b, and
The refrigerant gas sent from the high pressure side 1b of the cylinder 10a,
The refrigerant gas is guided to the inside of the compressor 10b and is sent out from the cylinders 10a and 10b to the low pressure side 1a of the compressor 1.

The rotary valve device RV comprises a valve body 8 and a valve plate 9, and the valve body 8 is fixed in the housing by fixing pins 19. Also, the valve plate 9 is
As shown in FIGS. 3 and 4, a circumferential engagement groove 16 that engages with the pin portion 14a of the crank 14 that drives the Scotch yoke 22.
(In the embodiment, a circumferential angle of 280 °), the pin portion 14a is engaged with the engaging groove 16 by the rotation of the crank 14 in the forward or reverse direction.
When it engages with the end 16a or 16b of the shaft 16, the movement of the crank 14, that is, the rotation of the reversible motor shaft 15a is transmitted to the valve plate 9, and the valve plate 9 rotates. The circumferential engagement groove 16 and the pin portion 14a are associated with a motion of the valve plate 9 and the reversible motor shaft 15a between the forward rotation and the reverse rotation of the motor at an angle of 280 ° in the embodiment. Will be connected.

A refrigerant gas intake hole 8b connected to the high pressure side 1b of the compressor 1 is penetrated through the center of the valve body 8, and the intake hole 8b is centered on the valve plate side end surface 8a as shown in FIG. An arcuate groove 8c is provided on a concentric circle, one end of which is opened in the groove 8c, and a through hole 8d which is in communication with the discharge hole 8e which is formed in the main body 8 and whose other end is opened to the side surface is formed. 8e opens to the vacant chamber 13 via the passage 20. A groove extending radially from the center of the end surface 9a of the valve plate 9 on the valve body side.
9d and an arc-shaped groove of the valve body 8 penetrating from the end face 9a of the valve plate 9 to the opposite end face 9b.
An arc-shaped hole 9c is formed at a position on the same circumference as
b, groove 9d, arc-shaped groove 8c and through hole 8d form an intake valve,
An exhaust valve is formed by the through hole 8d, the arcuate groove 8c, and the arcuate hole 9c.

FIG. 5 shows the connection wiring and rotation direction of the reversible motor. That is, the conventional refrigerator has the motor shaft by the switch Sa.
15a is made to perform only forward rotation. On the other hand, the rotation direction of the motor shaft 15a according to the present invention is provided with the changeover switch Sb as shown in FIG. 6 so that the CW contact (forward rotation) in the cooling mode and the CCW contact in the temperature rising mode. It has a structure that can be switched to a contact point (reverse rotation).

Cooling mode operation is performed by the forward rotation of the reversible motor 15. At this time, the pin portion 14a of the crank 14 engages with one end 16a of the engagement groove 16 of the valve plate 9 to rotate the valve plate 9 in the forward direction.

Before the displacers 3a and 3b reach the position of the bottom dead center LP (in the embodiment, before reaching the position of 20 ° from the bottom dead center), the exhaust valve is closed and the through hole 8d, the arc-shaped groove 8c, and the groove are formed.
A flow path is formed between the housing 9d and the air chamber 9d (the intake valve is opened), and the high-pressure refrigerant gas starts to fill the vacant space 13 through the flow path 20 in the housing. That is, before the displacers 3a and 3b reach the bottom dead center, the intake valves are open. Displacer 3a, 3
b starts to rise after passing through the bottom dead center, and the refrigerant gas passes through the regenerators 4, 5 from top to bottom, and fills the vacancies 11, 12.

When the displacers 3a, 3b reach the position before reaching the top dead center UP (in the embodiment, before the top dead center by an angle of 65 °), the intake valve closes. When the displacers 3a, 3b reach the position before reaching the top dead center (in the embodiment, before the top dead center by an angle of 45 °), the flow passage is formed between the through hole 8d and the arc-shaped groove 8c and the arc-shaped hole 9c. Is formed (exhaust valve is open). The high-pressure refrigerant gas adiabatically expands to generate cold, which cools the flanges 6 and 7, and passes from the bottom to the top while cooling the regenerators 4,5 and begins to flow back to the low-pressure side 1a of the compressor 1. .

If the displacers 3a and 3b reach a position (in this embodiment, at an angle of 20 ° from the bottom dead center) before reaching the bottom dead center LP, the exhaust valve closes, the intake valve opens, and one cycle ends.

The temperature increasing mode operation is performed by the reverse rotation of the reversible motor 15. Unlike the case of the cooling mode operation, the pin portion 14a of the crank 14 engages with the other end 16b of the engagement groove 16 of the valve plate 9 to rotate the valve plate 9 in the opposite direction.

Displacers 3a and 3b are in front of the top dead center UP (3
The exhaust valve closes when it reaches the position 5 mm (before), and when it reaches the position before the top dead center (in this example, 15 mm before), the through hole
A flow path is formed between the groove 8d, the arcuate groove 8c, and the groove 9d (the intake valve is open), and the high-pressure refrigerant gas passes through the flow path in the housing 20 and passes through the regenerators 4 and 5, and the empty chamber 11 The flanges 6 and 7 in the low temperature state are heated by the compression heat (adiabatic compression work when gas is packed) at that time.

When the displacers 3a and 3b reach the position before reaching the bottom dead center (in the embodiment, an angle of 60 ° before the bottom dead center), the intake valve closes, and at the same time, the through hole 8d, the arc-shaped groove 8c, and the arc-shaped hole 9c A flow path is formed between them (the exhaust valve is opened), and the refrigerant gas in the empty chamber 13 adiabatically expands to generate cold. The low-pressure refrigerant gas whose temperature has dropped is directly exchanged with the regenerators 4 and 5 without exchanging heat.
And is returned to the low pressure side 1a of the compressor 1.

When the displacer 3 reaches the position before the top dead center (35 ° before in the embodiment), the exhaust valve is closed and one cycle is completed.

Industrial applicability When the cryo pump is regenerated, the conventional method of stopping the operation of the refrigerator and supplying heat to the cryopanel surface with externally heated gas or a heater increases the temperature of the regenerator inside the displacer. Although it took time to raise the panel temperature because of the difficulty, in the present invention, the regenerator inside the displacer was heated first to generate heat by adiabatically compressing the refrigerant inside the cylinder of the refrigerator, and the temperature was raised. During the mode operation, the opening and closing of the intake valve and the exhaust valve of the refrigerator are automatically adjusted to the optimal timing for performing the temperature raising operation, so that the temperature rising time of the cryopanel can be greatly reduced.

Claims (3)

(57) [Claims] At least one cylinder, at least one displacer having a regenerator therein and reciprocating in the cylinder, and provided inside the cylinder outside both ends of the displacer. A vacant chamber that communicates with each other via a regenerator inside the displacer, a rotary valve device that controls the flow of high-pressure refrigerant gas to the vacant chamber and low-pressure refrigerant gas from the vacant chamber, and the rotary valve device. A reversible motor that controls the reciprocating motion of the displacer while rotating forward and backward, and when the rotary valve device rotates forward, adiabatic expansion of the refrigerant gas from the empty chamber to generate cold, When the valve device rotates reversely, the refrigerant gas is subjected to adiabatic compression of the refrigerant gas in the chamber to generate heat.
In a McMahon cycle type cryogenic refrigerator, a means is provided for varying the opening / closing timing of the rotary valve device with respect to reciprocation of the displacer between forward rotation and reverse rotation. 2. The rotary valve device according to claim 1, wherein said rotary valve device comprises a fixed valve body and a rotatably supported valve plate in surface contact with said valve body. An engaging groove extending in a circumferential direction, and a pin portion provided on a crank driven by the reversible motor and engaging with an engaging groove of the valve plate. Thus, when the crank is rotated forward or backward, the pin is rotated. The valve plate according to claim 1, wherein the valve plate is idled without rotating until the portion engages with one end or the other end of the engagement groove. Cryogenic refrigerator. 3. The cryogenic refrigerator according to claim 2, wherein an engagement groove is formed so that the idling is about 280 °.