JPS603491A - Cryopump - Google Patents

Abstract

PURPOSE:To prevent the lowering of a pump performance due to an increase in thermal load and as well to shorten the time for starting of operation to aim at enhancing the efficiency of operation is aimed at being enhanced, by connecting a heat pipe between a section which is heated to a high temperature by the thermal load of a cryopump, and a low temperature section. CONSTITUTION:When the thermal load of a pump increases, the section which are heated to a relatively high temperature by the thermal load of the pump, such as, for example, a baffle 9, are connected to low temperature sections such as, for example, a refrigerator first stage 3. With this arrangement, the heat from the baffle 9, etc. is transmitted to the first stage 3 through a heat pipe 11 which operates at a low temperature and which utilizes nitrogen gas as working liquid, and therefore, the temperature gradient therebetween may be limited to a minimum so that a cryopump is driven, without lowering the degree of vacuum, even if the pump load increases. Further, the starting of pump operation may be made in a short time due to the provision of the heat pump, thereby the efficiency of operation may be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cryopump used for evacuation.

Cryopumps are generally housed inside the pump case.

A shield that is attached to the first stage of the refrigerator and has a baffle at the opening, and a cryopump that is attached to the second stage of the refrigerator cylinder inside the shield% 7
Water vapor cooled to 0° or less is exhausted using a vacuum cleaner and a shield, and nitrogen, hydrogen, etc. are exhausted using a cryo-channel at 20°. As the heat load increases, the heat load on the shields and baffles also increases.As a result, a temperature gradient occurs in the VC of these shields, etc., resulting in a reduction in exhaust performance.

To explain this further, the shield and the nototsufuru are cooled by heat conduction from the first stage of the refrigerator, so if a large pump heat load is applied, the first stage of the refrigerator will not be sufficiently cooled. Despite this, the transmission muff is limited in the shield and the notch, and the temperature of the tip of the shield and the baffle is significantly higher than that of the first stage.For example, when the shield etc. In this case, the vapor pressure of water becomes 6.10-7 Torr, so a system that exhausts a lot of water cannot achieve a high vacuum of less than 10-7 Torr, and the probability of water vapor adhesion decreases, resulting in poor exhaust performance. decreases.

In large cryopumps, the seal F: 'Yapuffle is hard, and the heat receiving area is also large, so the heat load is also large.If the pump has an inlet diameter of about 50α, approximately 50 to 8oW of heat is frozen. When the machine enters the first stage, is there any temperature or moisture in the first stage? The temperature is 70 to 100"K, which is sufficient to condense and exhaust water, but shields and baffles have a temperature of 120 to 160 degrees K, making it impossible to condense moisture and exhaust it.

In order to improve the heat conduction of the shield or baffle and eliminate the temperature gradient caused by the increase in heat load, it is possible to increase the thickness of the shield, etc.
The III rating is also undesirable because it has a small screen and increases heat capacity, resulting in a long start-up time.

The purpose of the present invention is to reduce such temperature gradients, and the purpose of the present invention is to reduce such temperature gradients in the cryopump and other parts of the cryopump where the temperature becomes relatively high due to an increase in pump heat load, as well as the first stage of the refrigerator, etc. The low-temperature parts of the heat pump are connected to each other via a heat nozzle that operates at low temperatures.

To explain the implementation sequence of the present invention with reference to the drawings, (1) is a cryopump, (2Nj: pump case, +31 (4)
The first refrigerator installed in the pump case (2)
In the second stage and the second stage of the refrigerator, each stage t3) [4] is a moving part (
5) are formed at the top of two-stage cylinders (6) and (7) connected to each other. (8) Opening toward the intake port (2a) of the Vi pump case (2) (8a)
A hollow cylindrical shield attached to the stage (3),
(g) is a baffle concentrically fitted in the opening (8a), and QO is a cryonnel attached to the second stage (4) in the middle of the shield (8). When the moving part (5) operates, high-pressure helium expands adiabatically in the cylinder (6) (9 and each stage +3 at the top) [4
) is cooled.

Due to heat conduction from this, seal l-'' (8), baffle (9)
) and cryonomynel αO are cooled to condense and adsorb gas molecules.

The above purchase is almost the same as for conventional cryopumps, and according to this, when the heat load of the pump increases, the shield 1
8),, Although it is undesirable that a large temperature gradient occurs between the temperature of the baffle (9) and the first stage (3) of the refrigerator, which is at a high temperature and a low temperature, the baffle (9) is undesirable. 9), etc., and the low temperature section, such as the 1st stage with refrigerator (3), are connected to each other via the heat tube (II) Q, which operates at low temperatures, to reduce the temperature. The heat pipe α1) has a working fluid of 70° if a gas 1, such as fluorine gas, which does not solidify at temperatures below 10 Torr, is used as the working fluid. to 113°
It can be operated in the temperature range of 11° and can transfer tens of watts of heat. To attach the heat pipe (11), for example, as shown in the figure 31, insert the pipe αl) through the opening 021 surrounding the cryopanel, and attach each end to the Teikoku 1st stage. (3) and the baffle (9), respectively, or as shown in the second diagram, between the E16 shield (8) near the first stage (3) and the tip of the seal l'' (8). Also, when using heat pipes 01), depending on the operating conditions, the working fluid may be argon or other heat source.
can be used in combination to widen the operating temperature range of Heat Pizo.

Its operation will be explained.

The shield (8) and the baffle (9) are cooled to about 70'l (or less) and all water vapor from the inlet (2a) is exhausted, and the cryopanel CI (J is cooled to about 20° or less and 4
When the heat load on the pump increases during normal operation of adsorbing and exhausting hydrogen, etc., the first stage (3rd stage) of the refrigerator
) and the tip of the shield (8) and the baffle (9), there is a thermal difference that cannot be compensated for by the heat conduction of the shield, causing a large temperature gradient.
Heat is transferred to the first stage (3) through the baffle (9), etc.
Since the temperature gradient between the two can be kept to a minimum, the cryopump can be operated without reducing the degree of vacuum even if the pump heat load increases. Also, when starting pump operation, each stage (3) (4)
, Shield (8), Nonotsufuru (9), Cryonomynel C11, etc. are at room temperature, and the temperature gradually decreases until the temperature of Shield (8), Nonotsufuru (9) reaches 130°, and the temperature of the cryonomynel C11 decreases to 130°. When the channel u1 becomes 20 degrees or less, the pump operates, but by providing a heat pipe αυ, the amount of heat transfer limited by the shield (8) can be overcome and the pump operates in a short time. Furthermore, even if the shield (8) and baffle (9) are made relatively thin, the cooling time can be shortened and the increase in heat load can be withstood.

In this way, according to the present invention, the heat load of the cryopump (() is directly read from the high-temperature part and the low-temperature part through the heat pipe, so it is possible to prevent the pump performance from deteriorating due to an increase in heat load, and to start operation. This has the effect of shortening the shelf life, increasing operating efficiency, and making the shield and shield thinner, making it possible to reduce the weight of Bonzo.

[Brief explanation of drawings]

FIG. 1 is a cutaway side view of an embodiment of the present invention, and FIG. 2 is a cutaway side view of a modified version 1 thereof. (1)... Cryopump (3)... Refrigerator No. 1
Stage (9)...Baffle α...Heat pipe rotation-- 瀝-ζζζ-

Claims (1)

[Claims] The baffle in the cryopump and other parts whose temperature increases relatively as the pump heat load increases, and the low-temperature parts such as the first stage of the refrigerator are connected to each other via a heat nozzle that operates at low temperatures. Characteristic cryopump.