JPH0454070B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cryopump, and particularly to a cryopump suitable for maintaining pumping speed.

[Conventional technology]

Conventional devices are discussed in the Buoy, Day, and I Cryogenic Engineering Handbook (published by Uchida Rokakuba Shinsha on September 15, 1982), page 372, and in Japanese Patent Application Laid-open No. 131779/1983.

[Problem to be solved by the invention]

In the former prior art, no consideration is given to maintaining the roundness of the first cryopanel, which is made of equal thickness to reduce the heat capacity, and the first cryopanel and the vacuum chamber come into contact with each other, resulting in heat leakage. Also,
If an exhaust speed control board is used, this control board and the first cryopanel may come into contact, generating dust, locking the movement of the control board, or causing excessive stress between the first cryopanel and the exhaust speed control board. There were problems such as the creation of gaps and the inability to reduce the exhaust speed.

Furthermore, as typified by the latter prior art, many cryopumps do not have variable pumping speed.

The purpose of the present invention is to expand the variable range of pumping speed of a variable pumping speed cryopump, and
An object of the present invention is to provide a cryopump that suppresses dust generation.

[Means to solve the problem]

The above purpose is to arrange a screen that can be opened freely for controlling the exhaust speed, and to prevent the screen from coming into contact with the inner wall of the cylindrical first cryopanel due to the movement of the screen, and to reduce the gap between the screen and the thin first cryopanel. This is achieved by providing the first cryopanel with a restraining member (a reinforcing ring serving as a shape retaining means) for maintaining the perfect circle of the cylinder so that the distance is minimized.

The cryopump of the present invention comprises a vacuum chamber 5, a refrigerator 1 which is arranged through the bottom of the vacuum chamber 5 and has a plurality of temperature stages, and a cylindrical container housed in the vacuum chamber 5. a first cryopanel 4 that is housed within the first cryopanel 4 and is in thermal contact with one temperature stage of the refrigerator; A second cryopanel 5 with a lower temperature level than the panel 4, and a first cryopanel 4
Batsuful 8 with louver 7 placed on the opening side of
and a screen 13 that opens and closes around a rotating body provided at the lower center of the Batsuful 8, and is reinforced along the cylinder of the first cryopanel 4 on the opening side of the first cryopanel 4 and in front of the screen 13. It is characterized in that a ring 15 is provided.

[Effect]

Since the present invention uses an exhaust speed control screen, the exhaust speed is variable. Screen is 0°~
The opening can be adjusted within a 360° range.

The roundness of the first cryopanel can be maintained by the reinforcing ring provided on the outside or inside of the first cryopanel so that the circular cross-sectional shape of the first cryopanel is not deformed. Therefore, the gap between the outer periphery of the screen for pumping speed control, which rotates concentrically with the circular cross-section of the first cryopanel, and the first cryopanel is formed to be a constant gap and minimized, thereby narrowing the pumping speed to the minimum value. Therefore, the variable range of the exhaust speed can be expanded, and since the two can maintain a non-contact state, generation of dust can be prevented.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

A first cryopanel 4 and a second cryopanel 5 are provided in good thermal contact with the first temperature stage 2 and second temperature stage 3 of the refrigerator 1, which generate cold due to adiabatic expansion of a working fluid such as helium gas, respectively. It is integrated into. At the end of the first cryopanel 4, knobs 6 with female thread grooves are provided at four locations in the cross direction by soldering or silver brazing on the inside of the first cryopanel 4, and the knobs 6 have a conical cone shape. A double-sided panel 8 with a panel 7 attached is integrated with screws 9 with good thermal contact. These cryopanels are isolated from the atmosphere in a vacuum chamber 10, and are separated from the atmosphere by a flange 11.
Attach to the object to be evacuated with.

Further, a rotating body 12 is provided at the lower center of the buttful 8, a screen 13 is attached to this, and a screen starting point body 14 is fixed in one radial direction of the buttful 8.
With the starting point as the starting point, the screen 1 is rotated around the rotating body 12.
Open and close 3 in a fan shape in the range of 0° to 360°.

A reinforcing ring 15 is integrated inside the first cryopanel 4 in order to maintain this degree of vacuum.

During operation of this cryopump, the first cryopanel 4 is cooled to approximately 80K, high boiling point gases such as water and carbon dioxide gas in the exhaust gas are condensed and exhausted, and the
The second cryopanel 5 cooled to 20K condenses, adsorbs, and exhausts low-boiling point gases such as nitrogen, oxygen, argon, and hydrogen.

When the screen 13 is closed, the second cryopanel 5 faces the entire surface of the object to be evacuated, so the pumping speed reaches its maximum value.On the other hand, when the screen 13 is expanded, the second cryopanel 5 The entire surface will be covered, and the pumping speed will be at its minimum value. The wider the range between the maximum value and the minimum value, the better the variability of the exhaust speed.

When the screen 13 is fully expanded, the exhaust gas flows between the inside of the first cryopanel 4 and the screen 1.
3, and is condensed and adsorbed by the second cryopanel 5. Therefore, by keeping this gap small, the minimum value can be further reduced. Therefore, it is necessary to form the inside of the first cryopanel 4 into a perfect circle with high precision.

However, the first cryopanel 4 is made thin in order to have a low heat capacity, and it is difficult to form it into a perfect circle.

Therefore, by attaching a reinforcing ring 15 made of a strong material to maintain a perfect circle, this gap can be reduced and the peripheral edge of the screen 13 and the inner wall of the first cryopanel 4 can be kept in a non-contact state as much as possible. This has the effect of preventing the generation of dust and locking of the screen.

FIG. 2 shows another embodiment of the present invention, and the difference from FIG. 1 is that the first cryopanel 4
Instead of separately providing the reinforcing ring 15 inside the first cryopanel, the first cryopanel itself is plastically worked into a concave shape to form the reinforcing ring 16, so that the shape is maintained in a perfect circle. In addition, the first cryopanel tip 17 is bent inward to make it easier to maintain a perfect circle state.

According to this embodiment, since the perfect circle state can be maintained without separately providing a reinforcing ring, there is an effect that the heat capacity of the first cryopanel is not increased and the manufacturing cost can be reduced.

FIG. 3 shows still another embodiment of the present invention, and the difference from FIG.
8 is provided, and the full 8 is attached to the reinforcing ring 18.

According to this embodiment, since the female screw can be machined to an accurate position, when attaching the Batsuful 8, the first cryopanel will not be restrained and deformed due to the incorrect position of the female screw, so that it can be more perfectly circular. There is an effect that can be maintained.

〔Effect of the invention〕

According to the present invention, it is possible to maintain the perfect circular state of the thin-walled cryopanel, to make the gap between it and the screen for varying the exhaust speed sufficiently small, and to maintain a non-contact state, thereby reducing the minimum value of the exhaust speed. That is, there is an effect of expanding the variable range and preventing the generation of dust due to contact or the like.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a cryopump according to one embodiment of the present invention, and FIGS. 2 and 3 are cross-sectional views of the upper end of a cryopump showing other embodiments of the present invention. 4...First cryopanel, 5...Second cryopanel, 8...Batsuful, 10...Vacuum chamber, 1
3... Screen, 15... Reinforcement ring.

Claims (1)

[Claims] 1. A vacuum chamber, a refrigerator disposed through the bottom of the vacuum chamber and equipped with a plurality of temperature stages, and a cylindrical container housed in the vacuum chamber that connects one temperature stage of the refrigerator to the temperature stage. a first cryopanel in contact with the cryopanel, and a second cryopanel that is housed within the first cryopanel and is in thermal contact with another temperature stage of the refrigerator and is at a lower temperature level than the first cryopanel. A cryopanel, a buttful with a louver disposed on the opening side of the first cryopanel, and a screen that opens and closes around a rotating body provided at the lower center of the buttful,
A cryopump characterized in that a reinforcing ring is provided along the cylinder of the first cryopanel on the opening side of the cryopanel and in front of the screen.