JPH0735070A - Cryopump - Google Patents

Abstract

PURPOSE:To provide a cryopump which performs the cooling cycles of a GM (gifford Mcmahon cycle) type refrigerator and presents the max. efficiency in the temp. rise cycle. CONSTITUTION:A cryopump performs the cooling cycle, in which the introduced gas in a cylinder 71 is expanded by reciprocative motions of a displacer 72 given by the regular direction rotating of a motor 21 and the opening/closing operations of a low pressure side and a high pressure side valve, and also the temp. rise cycle to rotate the motor 21 reversely. The pump is equipped with a rotary valve 27, in which two gas flow holes are formed, and provided with an arc-shaped groove which is engaged by a crank shaft 24 of a crank mechanism 23 and generates an idle motion when the motor 21 rotates reversely. A rotary valve disc 28 is furnished to generate the opening/closing motions as the low pressure side and high pressure side valves selectively in association with the rotary valve 27, and the arc-shaped groove generates the opening motion of the low pressure side valve before the displacer reaches the upper dead point in the cooling cycle, and also the opening motion of the high pressure side valve when the displacer is at the upper dead point in the temp. rise cycle.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a cryopump,
In particular, in a cryopump equipped with a Gifford McMahon cycle refrigerator and configured to execute a cooling cycle with maximum cooling efficiency, the opening timing of the high pressure side valve etc. for the reciprocating motion of the displacer is set to the optimum phase relationship. The present invention relates to a cryopump that realizes a temperature rising cycle with good temperature rising efficiency and uses this temperature rising cycle for regeneration.

[0002]

2. Description of the Related Art A cryopump equipped with a Gifford McMahon cycle refrigerator (hereinafter referred to as a GM refrigerator) requires structural regeneration. This regeneration is performed by liquefying the gas by heating the gas condensed and adsorbed in the cooling process on the charcoal panel and the condensation panel arranged on the cooling stage on the GM refrigerator cylinder in the pump container. It is vaporized and discharged to the outside of the pump container.

As a means for supplying heat used during regeneration, conventionally, a purge gas at room temperature (mainly nitrogen gas) has generally been introduced into the cryopump. The temperature of the gas is raised by the heat of the introduced purge gas and the heat transfer with the pump container.

In addition, in order to shorten the time required for regeneration, a purge gas heater is attached to increase the temperature of the purge gas introduced into the cryopump, or a heater is provided outside or inside the pump container. I was trying to get warm.

Each of the above-mentioned conventional heat supply means requires another gas or device, the added element becomes a heat load in the cooling process, and special equipment such as an external controller unit is required. There was a problem.

In contrast to the above conventional technique, a new heat generating means has been proposed in recent years. This heat generating means is a means for realizing a temperature rising cycle by reversing the cooling cycle of the refrigerator and utilizing the refrigerator itself as a heat source (Japanese Patent Publication No. 4-195). In this refrigerator, the motor for reciprocating the displacer in the cylinder is rotated in the reverse direction through the crank mechanism, and the operation timing of the valve element is different by 180 ° from the operation in the cooling cycle. In this way, the cooling cycle is reversed to create a temperature rising cycle, which is operated as heat generating means. This heat generating means does not require any special equipment and only needs to reverse the cooling cycle, so that the structure is simple and extremely convenient.

[0007]

[Problems to be Solved by the Invention] A GM type refrigerator is provided,
Assuming a cryopump configured to utilize a GM cycle to generate a cooling cycle and reverse the cooling cycle to generate a heating cycle, this cryopump maximizes cooling efficiency in the cooling cycle. In the temperature raising cycle, it is desirable to maximize the temperature raising efficiency. By maximizing the cooling efficiency, it is possible to shorten the start-up time and increase the throughput of the exhaust gas, while maximizing the temperature raising efficiency can shorten the time required for regeneration. In the above case, the operating condition that achieves the maximum cooling efficiency in the cooling cycle and the operating condition that achieves the maximum heating efficiency in the heating cycle are different from each other. Incarnation should be considered and set independently.

Here, with reference to FIGS. 8 (a) and 9, the cooling that has been actually carried out in the past is carried out from the viewpoint of maximizing the cooling efficiency of the cooling cycle in the cryopump equipped with the GM type refrigerator. The cycle will be described while clarifying the positional relationship with the displacer in the cylinder.

FIG. 9 shows an internal structure of a cylinder of a refrigerator arranged in a pump container, a high pressure side valve and a low pressure side valve. The structure shown is the basic structure of a conventional device. A displacer 72 that reciprocates in a sliding state is arranged in a cylindrical cylinder 71. Ring-shaped sealing members 73 and 74 are provided between the displacer 72 and the cylinder 71. Regarding the shapes of the cylinder 71 and the displacer 72, the diameter at the lower part in the drawing is small. Inside the displacer 72, for example, two regenerators 75 and 76 are provided. The regenerators 75 and 76 basically have a structure that allows gas to pass therethrough, and since the structure is known, detailed description thereof will be omitted. Holes for allowing gas to pass are formed in the upper surface portion, the intermediate portion, and the lower surface portion of the displacer 72. Gas flows through the holes in accordance with the moving state of the displacer, for example, as indicated by the broken line 77. Broken line 7
In the gas flow shown at 7, all possible directions of flow are indicated by arrows. Actually, in the figure, a flow in any one direction from top to bottom or bottom to top occurs depending on the operating condition. In the reciprocating motion of the displacer 72, the position at the upper end of the cylinder 71 in FIG. 9 is the top dead center position, and the position at the lower end is the bottom dead center position.

A connecting rod 7 is provided on the upper surface of the displacer 72.
8, the connecting rod 78 extends to the outside of the cylinder 71, and is connected to a rotary drive shaft of a motor (not shown) via a crank mechanism (not shown). A seal member 79 is provided between the connecting rod 78 and the cylinder 71. When the motor rotates in a certain direction, the connecting rod 78 reciprocates 80 according to the rotation of the motor by the action of the crank mechanism. Therefore, the displacer 72 connected to the connecting rod 78 also interlocks and reciprocates in the cylinder 71. Due to the reciprocating motion of the displacer 72, two spaces (compartment chambers) U and L partitioned by the displacer 72 are provided in the cylinder 71.
Is formed. The space U is an upper space in FIG. 9, and the space L is a lower space. In addition, as for the space L, two parts are formed in the illustrated example.

A low pressure gas chamber 81 is provided at the upper end of the cylinder 71.
A low pressure side valve 82 that enables connection with the high pressure gas chamber 83 and a high pressure side valve 84 that enables connection with the high pressure gas chamber 83 are provided. The opening / closing operation of the low pressure side valve 82 is controlled by the command signal 85, and the opening / closing operation of the high pressure side valve 84 is performed by the command signal 8.
Controlled by 7.

In the gas flow 77 shown in FIG. 9, the flow direction of the gas is one direction determined by the conditions at that time as described above, and the condition is the displacer 7.
2 moving direction, low pressure side valve 82 and high pressure side valve 84
It is given by the state of the opening and closing action of.

The basic cooling cycle of the GM type refrigerator will be described.

Step (1): When the displacer 72 is located at the top dead center, only the low pressure side valve is opened to expand the high pressure gas accumulated in the space L to generate cold. This expansion cools the periphery of the space L (cooling stage), and the movement of gas cools the regenerators 75 and 76.

Step (2): When the displacer 72 is at the bottom dead center as the reciprocating motion progresses, the low pressure side valve is closed and cold is stored in the regenerators 75 and 76.

Step (3): When the high pressure side valve 84 is opened,
Since the high pressure gas enters the space U and the displacer 72 moves upward at the same time, the high pressure gas is cooled when passing through the displacer 72 and moves to the space L.

Step (4): The displacer 72 reaches the top dead center and the high pressure side valve is closed. As a result space L
Is filled with low temperature high pressure gas.

Step (5): Next, the low pressure side valve 82 is opened. This step is actually step (1) above, thus returning to the first step (1).

As described above, cooling is performed by repeating steps (1) to (4). The above cycle is the basic cooling cycle. In the above basic GM type cooling cycle, when the displacer 72 is at the top dead center position, the high pressure side valve 84 is closed and the low pressure side valve 82 is opened.
The opening / closing operation of each valve is controlled so that the low pressure side valve 82 is closed and the high pressure side valve 84 is opened when the displacer 72 is at the bottom dead center position. Therefore, displacer 7
When 2 reaches the top dead center or the bottom dead center, the opening / closing timing of each valve is set, and the direction of the gas flow is reversed.

In the above basic cooling cycle, in the step (2), the gas is regenerated by the expansion of the high pressure gas into the regenerator 75,
When moving upward in 76, the displacer 72 moves toward the bottom dead center and the expanding gas passes through the regenerator at high speed, so that the expanding gas gives a large force to the displacer 72 and drives the displacer. There is a problem that a large load is applied to the motor. In addition, there is a problem that the time for heat exchange between the gas and the regenerator cannot be sufficiently taken and the cooling efficiency becomes poor.

Therefore, in the conventional actual GM type cooling cycle, the opening timing of the low pressure side valve 82 is shifted to the front side by the required phase α in order to improve the above problems.
An operation characteristic diagram showing this state is shown in FIG. Figure 8
In (a), the horizontal axis represents time and the vertical axis represents the position of the displacer 72 in the cylinder 71. The characteristic C1 expresses the reciprocating motion of the displacer 72, where 88 corresponds to the position of the top dead center and 89 corresponds to the position of the bottom dead center. Further, A shows a state where the low pressure side valve 82 is open, and B shows a state where the high pressure side valve 84 is open. As shown in FIG. 8A, the opening time 90 of the low pressure side valve 82.
Is displaced forward by a phase α relative to when displacer 72 reaches top dead center 88. This phase α is 0 °
<Α ≦ 90 °. By shifting the top dead center position of the displacer 72 and the opening time point of the low pressure side valve 82 in this way, the gas moving direction (from bottom to top) due to the expansion of the high pressure gas in the space L and the movement of the displacer 72 in the reciprocating motion. Since the direction (from the bottom to the top) is the same, the relative speed becomes small, and when passing through the regenerators 75 and 76 of the displacer 72, a sufficient time is taken for heat exchange between the gas and the regenerator, and The load on the motor driving the displacer 72 is also reduced. In this way, the cooling efficiency as a refrigerator is improved.

On the other hand, in order to increase the temperature raising efficiency in the temperature raising cycle which is made by reversing the cooling cycle of the refrigerator, the displacer 72 is placed at the top dead center in the cylinder 71 or at the rear side as appropriate. It is necessary to open the high-pressure side valve 84 by shifting it.

Now, considering the conventional actual GM type cooling cycle described above, the heat generating means disclosed in the above Japanese Patent Publication No. 4-195 will be examined. In the refrigerator realizing the heat generating means disclosed in this document, it is important that "the direction of the gas flow is reversed when the displacer (displacer) reaches the top dead center or the bottom dead center". Is clearly stated. That is, the GM type refrigerator assumed in this document is
This is a device that executes the basic cooling cycle described above.
Therefore, when the motor is rotated in the reverse direction and the operation timing of the valve element is different by 180 ° compared to the operation in the cooling cycle, the high pressure side valve is opened when the displacer 72 reaches the top dead center. Therefore, an efficient temperature raising cycle can be created.

However, in the refrigerator for executing the above-mentioned actual GM type cooling cycle, the motor is rotated in the reverse direction, and the operation timing of the valve element is different by 180 ° from the operation in the cooling cycle. However, it is not possible to realize a heating cycle with high heating efficiency.

In view of the above problems, the first object of the present invention is to solve the above problems by providing a GM type cooling cycle in which the opening point of the low pressure side valve is set before the displacer reaches the top dead center. A cryopump comprising a refrigerator configured to perform and reverse a cooling cycle to create a heating cycle, wherein the heating pump is used for regeneration,
An object of the present invention is to provide a cryopump capable of producing a temperature raising cycle with the highest temperature raising efficiency. A second object of the present invention is, in order to solve the above problem from a new point of view, a GM type in which the opening point of the low pressure side valve is set before the displacer reaches the top dead center in the normal rotation state of the motor. It is equipped with a refrigerator configured to execute a cooling cycle, converts the cooling cycle to a heating cycle with the highest heating efficiency while maintaining the normal rotation of the motor, and uses this heating cycle for regeneration. To provide a pump.

[0026]

The cryopump according to the present invention is constructed as follows.

A pump container, a cylinder arranged in the internal space of the pump container, and a regenerator having a gas passage formed therein are provided, and reciprocating motion can be performed in the cylinder while forming compartments at both ends of the cylinder. A low pressure side valve provided in the gas passage between one of the compartments of the cylinder and the low pressure side gas chamber, and a gas passage between the one of the compartments and the high pressure gas chamber. GM refrigerator including a high-pressure side valve, a motor capable of reciprocal rotation that causes a displacer to reciprocate through a crank mechanism, and an opening / closing execution unit that opens / closes the low-pressure side valve and the high-pressure side valve at appropriate timings. The gas introduced into the cylinder is expanded based on the relationship between the reciprocating motion of the displacer caused by the normal rotation of the motor and the opening / closing operation of the low pressure side valve and the high pressure side valve. Is a cryopump configured to perform a cooling cycle by rotating the motor and to reverse the cooling cycle by rotating the motor to create a heating cycle, and perform regeneration using the heating cycle. A fixed rotary valve in which a gas flow hole is formed, and an arc-shaped groove is formed on one surface for engaging with the crankshaft of the crank mechanism and performing idle operation when the motor reverses its rotation direction, and another location Is provided with a rotary valve disc that is rotatably mounted and is formed with a shape for selectively opening and closing as a low pressure side valve or a high pressure side valve in relation to the rotary valve. The opening / closing execution means is formed in the arc-shaped groove before the displacer reaches the top dead center in the cooling cycle. Displacer in the open operation is carried out and firing cycle of the low-pressure side valve is formed as the opening operation of the high-pressure side valve is performed at the time of top dead center or a suitably rear by dots.

In the above structure, preferably, the arcuate groove is formed and the angle thereof is in the range of 200 ° to 360 °.

A displacer provided with a pump container, a cylinder arranged in the internal space of the pump container, and a regenerator having a gas flow path formed therein and reciprocating in the cylinder while forming compartments at both ends of the cylinder. A low pressure side valve provided in a gas passage between one compartment of the cylinder and the low pressure side gas chamber, and a high pressure side valve provided in a gas passage between the one compartment and the high pressure gas chamber , A GM refrigerator including a motor that causes the displacer to reciprocate through a crank mechanism, and an opening / closing execution unit that opens and closes the low-pressure side valve and the high-pressure side valve at appropriate timings. A cooling cycle is created by expanding the gas introduced into the cylinder based on the relationship between the reciprocating motion and the opening / closing operation of the low pressure side valve and the high pressure side valve. In the cryopump, while the motor keeps the normal rotation operation, the opening / closing execution means creates the cooling cycle by performing the opening operation of the low-pressure side valve before the displacer reaches the top dead center, and the displacer moves upward. The temperature raising cycle for regeneration is constructed by performing the opening operation of the high-pressure side valve at the dead point or the rear side thereof as appropriate.

[0030]

In the cryopump according to the present invention, the cryopump is provided with a GM type refrigerator for performing a cooling cycle in which the low-pressure side valve is opened before the displacer reaches the top dead center, and the cooling cycle is reversed. A heating cycle is created by using the heating cycle for regeneration. In making the temperature raising cycle, the above cooling cycle is simply 180 °
Even if it is reversed, that is, even if the motor involved in the reciprocating motion of the displacer is reversed and the valve opening / closing timing is 180 ° out of phase compared with the case of the cooling cycle, an efficient temperature raising cycle cannot be obtained. Can not. In order to make an efficient temperature raising cycle, the displacer needs to open the high pressure side valve at the time of the top dead center or an appropriate rear side thereof. Therefore, in order to realize the most efficient heating cycle by reversing the cooling cycle in which the low pressure side valve is opened before the displacer reaches the top dead center, the most desirable angle greater than 180 ° is achieved. The valve opening and closing timing is adjusted with. In particular, the valve mechanism for the low-pressure side valve and the high-pressure side valve is simply configured as an integrated valve mechanism consisting of a rotary valve and a rotary valve disc, and the opening and closing timing of the low-pressure side valve and the opening and closing timing of the high-pressure side valve are controlled by the motor. Made it easy to change the rotation direction of.

Further, in another cryopump of the present invention, when the motor is rotating normally, the low pressure side valve and the high pressure side valve are opened and closed at appropriate timing in a state where the normal rotation is maintained. Based on the function of the opening / closing execution means, a cooling cycle is created by opening the low-pressure side valve before the displacer reaches top dead center, and at the same time when the displacer is at top dead center or appropriately rear side thereof, By performing the opening operation of the side valve, the temperature raising cycle for regeneration is created, and the cycle conversion can be selectively performed between the cooling cycle and the temperature raising cycle as needed. Such opening / closing execution means is generally realized by an electronic control means.

[0032]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the internal structure of a GM type refrigerator applied to the cryopump according to the present invention, and FIG. 2 shows the overall structure of the cryopump according to the present invention. The refrigerator shown in FIG. 1 is shown with the positional relationship upside down in the refrigerator shown in FIG.

First, the overall structure of the cryopump will be described. In FIG. 2, 1 is a processing chamber, and 2 is a cryopump attached to the processing chamber 1. The cryopump 2 includes a louver 3, which communicates with the internal space of the processing chamber 1 through an opening, a pump container 4, and a GM type refrigerator 5. In the processing chamber 1, a gate valve 1 a is usually provided corresponding to the opening of the louver 3. The pump container 4 has a relief valve 6. The refrigerator 5 is attached to the pump container 4 in an airtight manner.
A freezing stage 7 and a second freezing stage 8 are provided. The radiation shield 9 is in contact with the first freezing stage 7, and the second freezing stage 8 is located inside the radiation shield 9. A charcoal panel 10 and a condensing panel 11 are attached to the second freezing stage 8.

In the refrigerator 5, the first refrigerating stage 7 and the second refrigerating stage 7 in the cylinder are cooled to a temperature of 30 to 100K and a temperature of 4 to 20K by performing a cooling step and repeating adiabatic expansion to generate cold. . Further, the condensation panel 11 is cooled to 20K or less, and the louver 3 is cooled to 100K or less.

The configuration of the GM type refrigerator according to the present invention will be described with reference to FIG. In FIG. 1, elements that are substantially the same as the elements described in FIG. 9 are assigned the same reference numerals. That is, 71 is a cylinder, 72 is a displacer that reciprocates in the cylinder 71 and forms a partition chamber on the top dead center side and the bottom dead center side, 73 and 74 are ring-shaped seal members, and 75 and 7
6 is a regenerator, 78 is a connecting rod, 79 is a seal member, 81 is a low pressure gas chamber, and 83 is a high pressure gas chamber.

Other components shown in FIG. 1 will be described. Reference numeral 21 is a motor for reciprocating the displacer 72, 21a is a drive shaft of the motor 21, and 22 is a control device for controlling the forward and reverse rotation operations of the motor 21. Reference numeral 23 is a crank mechanism that converts the rotational movement of the motor 21 into reciprocating motion of the connecting rod 78, and 24 is a crankshaft. The crankshaft 24 is rotatably supported by the bearing 25 of the connecting rod 78. 26 is a crank box,
The crank box 26 is formed airtight. The crank box 26 has a structure that communicates with the low pressure gas chamber 81, and is provided with a valve mechanism including a rotary valve 27 and a rotary valve disc 28. The rotary valve 27 is fixed to the crank box 26, and has holes 27a and 27b formed at the central position and substantially the intermediate position between the central part and the outer peripheral part as shown in FIG. As shown in FIG. 1, a pipe 29 leading to the high pressure gas chamber 83 is connected to the hole 27a, and a pipe 30 leading to a compartment (space) on the top dead center side of the cylinder 71 is connected to the hole 27b. On the other hand, the rotary valve disc 28 has a support frame 31.
Is rotatably attached to the bearing via a bearing 32.
In the rotary valve disc 28, the crank mechanism 23
An arcuate groove 33 as shown in FIG. 3 is formed on the side surface. The tip of the crankshaft 24 is engaged with the arcuate groove 33. Further, in the surface of the rotary valve disc 28 on the rotary valve 27 side, an elongated recess 28a as shown in FIG. 4 is formed. Further, the rotary valve disc 28 has a substantially arcuate hole 28b as shown in FIG.
Is formed.

The rotary valve disk 28 is normally or reversely rotated based on the rotation operation of the crankshaft 24 of the crank mechanism 23, and the rotary valve disk 28 rotates with respect to the fixed rotary valve 27,
The opening / closing function of the high-pressure side valve and the opening / closing function of the low-pressure side valve are realized based on the relative positional relationship between the two. As shown in FIG. 6, the rotary valve disc 28 rotates, and the concave portion 28 a thereof has holes 27 a and 27 b of the rotary valve 27.
At the position where the high pressure gas is connected, the high pressure gas flows as shown by the broken line 34, and the high pressure gas is supplied from the high pressure gas chamber 83 to the cylinder 71. Similarly, as shown in FIG.
When the position 8b is aligned with the hole 27b of the rotary valve 27, the low-pressure gas flows as shown by the broken line 35 and passes from the cylinder 71 through the crankbox 26 to the low-pressure gas chamber 8
Low-pressure gas is discharged to 1. As described above, it operates as a high pressure side valve and a low pressure side valve based on the positional relationship between the rotary valve 27 and the rotary valve disc 28.

The rotary valve disk 28 is used for the motor 2
Crank mechanism 2 that is interlocked with the rotational movement of the drive shaft 21a of No. 1
3 receives the force from the crankshaft 24 and rotates. As shown in FIG. 3, the rotary valve disc 28 rotates normally when the tip of the crankshaft 24 hits one end of the arcuate groove 33 and rotates, and contacts the other end of the arcuate groove 33 to rotate. Sometimes reverse. When the crankshaft 24 of the rotary valve disc 28 in the forward rotation state starts reverse rotation,
The rotary valve disc 28 does not rotate until the tip of the crankshaft 24 contacts the other end of the arcuate groove 33, and the tip of the crankshaft 24 moves along the arcuate groove 33. Become. During this time, only the reciprocating motion of the displacer 72 is reversed via the crank mechanism 23, and the open / closed state of the high pressure side valve and the low pressure side valve is maintained as it is. The tip of the crankshaft 24 has an arcuate groove 33.
When moving along it, the open / close operation of the high pressure side valve and the low pressure side valve is performed as an idle operation (a state in which nothing is done).

As shown in FIG. 3, the angle θ at which the arcuate groove 33 is formed is in the range of 200 ° ≦ θ <360 °. Therefore, when the motor 21 in the forward rotation state starts reverse rotation,
The operation of the displacer 72 that reciprocates in the cylinder 71 immediately starts the opposite operation, but the rotary valve 27
Regarding the opening / closing operation of the valve mechanism composed of the rotary valve disk 28 and the rotary valve disk 28, the opening / closing operation of the high pressure side valve and the low pressure side valve is restarted with a phase delay θ of 200 ° ≦ θ <360 °.

When the motor 21 in the cryopump 2 having the above-described configuration is rotated in the normal direction, the GM type refrigerator 5 repeats adiabatic expansion based on a combination of the reciprocating movement of the displacer 72 and the opening / closing operation of the valve mechanism to execute a cooling cycle. To do. In this case, the cooling cycle is the actual cooling cycle described above in which the low pressure side valve was opened before the displacer 72 reached top dead center. Therefore, when the rotary valve disc 28 normally rotates by the crankshaft 24 in the positional relationship shown in FIG. 3, the relationship shown in FIG. 6 or 7 periodically occurs due to the relationship with the rotary valve 27, and FIG. The actual cooling cycle as shown in (a) is performed. Next, when the motor 21 is rotated in the reverse direction, the displacer 7 is moved through the crank mechanism 23.
2 begins to move in opposite directions in its reciprocating motion. However, the rotary valve plate 28 of the valve mechanism is held in a stopped state only by moving the tip of the crankshaft 24 in the arcuate groove 33 toward the other end. The tip of the crankshaft 24 has an arcuate groove 3
When the other end of 3 is contacted, the rotary valve disc 28 starts to rotate in the reverse direction. Rotary valve disc 28
8 rotates in the reverse direction in relation to the rotary valve 27 between the opening / closing timing of the high pressure side valve and the low pressure side valve and the reciprocating movement of the displacer 72.
The relationship shown in (b) is formed. That is, when the displacer 72 reaches the top dead center 88 or at the rear side thereof appropriately, the high-pressure side valve is opened (the state shown in FIG. 6) so that an appropriate opening / closing timing is formed. In other words, FIG.
In order to convert the actual cooling cycle shown in (a) into the heating cycle that achieves the optimum heating efficiency as shown in FIG. 8 (b), the arcuate groove 33 is set to 200 ° ≦ θ <360.
It is necessary to adjust the opening / closing timing by forming the valve mechanism at an angle θ of 0 ° and performing an idle operation for the opening / closing operation of the valve mechanism. In this way, by rotating the motor 21 in the reverse direction, adiabatic compression can be repeated and a highly efficient temperature raising cycle can be created. And this heating cycle can be utilized for regeneration of the cryopump.

When the cooling cycle shown in FIG. 8 (a) is performed in the cooling step, the structure of the conventional refrigerator (Japanese Patent Publication No. 4-195) (opening and closing in the heating cycle compared to the cooling cycle) And the regeneration according to the present invention (when the phase is 180 ° out of phase) with the configuration according to the present invention (in the temperature raising cycle, the opening / closing timing is shifted by about 200 ° to 360 ° in phase). As a result of experimentally studying the difference from the regeneration by the temperature raising cycle obtained in (1), it takes 60 minutes to raise the temperature to 290 K in the conventional apparatus, whereas it takes 30 minutes in the apparatus according to the present invention. In this case, N ₂ gas is flowing at 10 l / min in both the conventional apparatus and this apparatus. Therefore, if the cryopump GM type refrigerator according to the present invention is used,
It is possible to realize a heating cycle with maximum heating efficiency and perform regeneration in a short time.

In the above embodiment, the opening / closing execution means for opening / closing the low pressure side valve and the high pressure side valve at appropriate timing is provided in the rotary valve 27 and the rotary valve disk 28 which operate in association with the forward / reverse operation of the motor 21. It is formed by a combination structure. As another embodiment, the opening / closing execution means for opening and closing the low pressure side valve and the high pressure side valve at appropriate timing is constituted by, for example, an electronic control means, and the low pressure side valve of the low pressure side valve is maintained while the motor 21 is kept in the normal rotation state. By setting the opening / closing operation and the opening / closing operation of the high-pressure side valve in the same manner as the timing described in the above embodiment, the cooling cycle and the temperature rising cycle may be created with the motor rotating normally. In the case of this embodiment, a cooling cycle or a heating cycle can be selectively formed as needed.

[0044]

As is clear from the above description, according to the present invention, in a cryopump equipped with a GM type refrigerator,
In the case where the low pressure side valve is configured to open before the displacer in the cylinder reaches the top dead center and the cooling cycle of maximum cooling efficiency is executed, when the cooling cycle is reversed to realize the heating cycle, Since the opening / closing timing of the valve mechanism is shifted in the range of 200 ° ≦ θ <360 ° compared to the opening / closing timing in the case of the cooling cycle, the high pressure side valve is opened when the displacer reaches the top dead center. Therefore, it is possible to realize the temperature rising cycle with the maximum temperature rising efficiency and perform the regeneration.

Further, by combining the rotary valve and the rotary valve plate as the valve mechanism, the low pressure side valve and the high pressure side valve can be realized by one valve mechanism, and the structure is simplified.

The electronic control means realizes the opening / closing execution means for opening / closing the low pressure side valve and the high pressure side valve, and the opening / closing timing of the low pressure side valve and the high pressure side valve in the cooling cycle is kept while the motor for reciprocating the displacer is rotated in the forward direction. Since the low-pressure side valve and the high-pressure side valve of the heating cycle can be selectively opened and closed at different timings, the heating cycle can be selectively generated as needed during the cooling cycle. It is possible to simplify the configuration in the sense that the reverse rotation operation of is unnecessary.

[Brief description of drawings]

FIG. 1 is a GM applied to a cryopump according to the present invention.
It is sectional drawing which shows the structure of a type refrigerator.

FIG. 2 is a front view of a cryopump.

FIG. 3 is a front view of a rotary valve plate.

FIG. 4 is a rear view of the rotary valve plate.

FIG. 5 is a front view of a rotary valve.

FIG. 6 is a partial cross-sectional view showing an open state of a functional portion that operates as a high pressure side valve in the valve mechanism.

FIG. 7 is a partial cross-sectional view showing an open state of a functional portion that operates as a low pressure side valve in the valve mechanism.

FIG. 8 is an operational characteristic diagram showing a cooling cycle and a heating cycle according to the apparatus of the present invention.

FIG. 9 is a cross-sectional view showing a configuration of a general GM type refrigerator.

[Explanation of symbols]

 1 processing chamber 2 cryopump 3 louver 4 pump container 5 GM type refrigerator 7 first refrigeration stage 8 second refrigeration stage 21 motor 23 crank mechanism 24 crankshaft 26 crankbox 27 rotary valve 28 rotary valve disc 71 cylinder 72 displacer 75, 76 Regenerator 81 Low-pressure gas chamber 82 High-pressure gas chamber

Claims (3)

[Claims] 1. A pump container, a cylinder arranged in an internal space of the pump container, and a regenerator having a gas passage formed therein, and reciprocating motion in the cylinder while forming compartments on both ends of the cylinder. A displacer provided so as to perform a low pressure side valve provided in a gas passage between one of the compartments of the cylinder and the low pressure side gas chamber, and between the one compartment and the high pressure gas chamber. High-pressure side valve provided in the gas passage, a motor capable of forward and reverse rotation that causes the displacer to perform the reciprocating movement through a crank mechanism, and the low-pressure side valve and the high-pressure side valve are opened and closed at appropriate timings. G including opening / closing execution means
An M type refrigerator is provided, and cooling is performed by expanding the gas introduced into the cylinder based on the relationship between the reciprocating movement of the displacer by the normal rotation of the motor and the opening / closing operation of the low pressure side valve and the high pressure side valve. In the cryopump in which a cycle is created and the cooling cycle is reversed by reversing the motor to create a heating cycle, and regeneration is performed using this heating cycle, two gas flow holes are formed. And a fixed rotary valve having an arc-shaped groove formed on one surface to engage with the crankshaft of the crank mechanism to perform an idle operation when the motor reverses its rotation direction, and the rotary valve is provided at another location. A shape for selectively performing the opening / closing operation as the low pressure side valve or the high pressure side valve is formed in relation to And a rotary valve disc rotatably attached to the rotary valve, the rotary valve and the rotary valve disc forming the opening / closing execution means, the arcuate groove before the displacer reaches the top dead center in the cooling cycle. The opening operation of the low pressure side valve is performed at the time point of, and the displacer is formed such that the opening operation of the high pressure side valve is performed at the time of the top dead center or the rear side in the temperature raising cycle. And a cryopump. 2. The cryopump according to claim 1, wherein an angle θ at which the arcuate groove is formed is 200 ° ≦ θ <
A cryopump having a 360 °. 3. A reciprocating motion in the cylinder comprising a pump container, a cylinder arranged in the internal space of the pump container, and a regenerator having a gas passage formed therein and forming compartments at both ends of the cylinder. And a low-pressure side valve provided in a gas passage between one of the compartments of the cylinder and the low-pressure side gas chamber, and a gas passage between the one compartment and the high-pressure gas chamber. GM refrigerator including a high-pressure side valve, a motor that causes the displacer to perform the reciprocating motion via a crank mechanism, and an opening / closing execution unit that opens and closes the low-pressure side valve and the high-pressure side valve at appropriate timings. And introducing into the cylinder based on the relationship between the reciprocating movement of the displacer by the normal rotation of the motor and the opening / closing operation of the low pressure side valve and the high pressure side valve. In a cryopump that creates a cooling cycle by expanding the introduced gas, in the state in which the motor maintains a normal rotation operation, the opening / closing execution means is configured to set the low-pressure side at a time before the displacer reaches top dead center. The cooling cycle is formed by performing the opening operation of the valve, and the heating cycle for regeneration is formed by performing the opening operation of the high pressure side valve at the time when the displacer is at the top dead center or the rear side thereof. A cryopump characterized by that.