JPH048896A - Vacuum pump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vacuum pump whose exhaust port is operated at atmospheric pressure, and in particular to a dry vacuum pump suitable for use in processes where reaction products tend to adhere. Regarding pumps.

[Conventional technology]

Dry vacuum pumps have the excellent feature of providing a clean vacuum because there is no oil or water in the flow path through which the gas flowing in from the intake port passes. The temperature inside the pump becomes high because of this. Therefore, conventionally, a cooling jacket was provided outside the heat generating part to perform water cooling.

FIG. 2 is a sectional view of a conventional dry vacuum pump. Intake port 1. A rotor 4 rotatably supported by a bearing 6 and a stationary stator 5 are provided inside a casing 3 having an exhaust port 2. Gas sucked in through the intake port 1 is sequentially compressed by the compression action of the rotor 4 and the stator 5, and is exhausted to the atmosphere through the exhaust port 2.

During the compression process, the gas generates compression heat, but the exhaust port 2
The closer it is to , the greater the amount of compression heat. In order to remove this compression heat, a cooling jacket 9 is provided outside the stator 5 in the example shown in FIG. 2, and the stator 5 is cooled with water supplied from a water supply port 13.

This type of conventional technology is disclosed in Japanese Patent Application Laid-Open No. 61-247893.
There is something described in the publication.

[Problem to be solved by the invention]

In the above conventional technology, the metal cooling jacket is directly
Since it was cooled by passing water through it, the cooling effect was very good.

However, when the sublimation temperature of the suction gas is high and the internal temperature of the pump is low, the gas solidifies and deposits as a reaction product inside the pump, blocking the pump flow path and eventually causing rotor lock.

Furthermore, if the amount of cooling water is reduced below a certain amount, there are problems such as temperature non-uniformity, which reduces pump performance, and deposits of limescale in areas where the flow rate is slow.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vacuum pump that prevents the gas from solidifying even when gas having a high sublimation temperature is sucked into the pump flow path and prevents reaction products from being deposited.

[Means to solve the problem]

In order to achieve the above object, the present invention uniformly increases the temperature inside the pump by reducing the thermal conductivity of the inner surface of the cooling jacket, and directs substances with high sublimation temperature sucked in from the intake port to the gas phase side. It was possible to maintain the temperature above .

[Effect]

For example, the gas emitted from a reactor in semiconductor manufacturing equipment depends on the relationship between the vapor pressure and temperature of the substance.

As the pressure approaches the atmospheric pressure, unless the temperature is high, it becomes solid, and it will adhere and deposit in the pump channel as a reaction product.

Since a pump generates a large amount of heat through compression, reducing the thermal conductivity of the inner surface of the cooling jacket allows the pump flow path to be kept at a constant high temperature. Thereby,
Since the gas passing through the pump channel can be kept at a constant high temperature, it is possible to prevent reaction products from adhering and accumulating.

〔Example〕

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

In FIG. 1, a casing 3 having an intake port 1 and an exhaust port 2 includes a rotor 4 supported by a bearing 7 and driven by a motor 8, and a stator 5 attached so as to surround the rotor 4. There is a pump mechanism section 6.

The gas sucked in from the intake port 1 is transferred to the rotor 4 and stator 5.
Due to the compression action of , the air is sequentially compressed and exhausted to the atmosphere through the exhaust port 2 . A cooling jacket 9 is provided on the outside of the stator 5.
is provided, and a plastic plate 10 is pasted on its inner surface with adhesive. and.

A closed space is formed by sealing with a rubber O-ring 11 and a jacket cover 12. The jacket cover 12 is provided with a water supply port 13 and a drain port 14, and the cooling water that flows in from the water supply port 13 removes the heat generated when gas is compressed by the pump mechanism 6, and is drained. Mouth 1
It is discharged from 4.

Next, the operation of one embodiment of the present invention will be explained.

Gas sucked in through the intake port 1 is sequentially compressed within a flow path of a pump mechanism section 6 consisting of a rotor 4 and a stator 5, and is exhausted to the atmosphere through an exhaust port 2. During the exhaust process,
In the portion where the rotor 4 is rotating at high speed, the gas becomes high temperature, and the heat is conducted to the stator 5. As it is,
In this case, the gas temperature increases and the compression action of the pump mechanism 6 deteriorates, reducing pump performance, and the rotor 4 and stator 5 come into contact due to thermal expansion. do.

For example, when the inlet port 1 of the vacuum pump is connected to an aluminum dry etching device of semiconductor manufacturing equipment,
As a reaction product after etching.

Aluminum chloride (AnCRa) is produced. As shown in FIG. 3, this sublimation temperature characteristic diagram is divided into an in-phase side and a gas phase side depending on the relationship between pressure and temperature.

In FIG. 3, reference numeral 15 indicates data of the prior art, and reference numeral 16 indicates an embodiment of the present invention.

When cooled by flowing cooling water directly into the cooling jacket 9, the internal temperature of the stator 5 is located on the solid phase side of the sublimation temperature characteristic diagram of AQCQs, and the inner wall of the stator 5 is
s adheres and accumulates. Therefore, when a plastic plate 1o is attached to the inner surface of the cooling jacket 9, the temperature gradient between the cooling water and the gas inside the stator 5 becomes large because plastic has a lower thermal conductivity than iron at about 1710. , the temperature of the gas can be kept high. As a result, the internal temperature of the stator 5 can be set to a position on the gas phase side of the sublimation temperature characteristic diagram of AQCQ3, and reaction products are not deposited on the inner wall of the stator 5.

Note that instead of the plastic plate 10, a material with a lower thermal conductivity than metal other than plastic may be attached, or
A similar effect can also be obtained by applying a liquid substance that solidifies into a film with low thermal conductivity to the inner surface of the cooling jacket 9.

〔Effect of the invention〕

According to the present invention, since the temperature inside the stator can be increased, it is possible to prevent reaction products from adhering to the pump mechanism.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a vacuum pump according to an embodiment of the present invention, Fig. 2 is a longitudinal sectional view of a conventional vacuum pump, and Fig. 3 is an ARCQ
FIG. 3 is a sublimation temperature characteristic diagram and a temperature characteristic diagram of a. 4... Rotor, 5... Stator, 6... Pump mechanism section. 9... Cooling jacket, 10... Plastic plate,
12...Jacket cover

Claims (1)

[Scope of Claims] 1. A vacuum pump that compresses low-pressure gas sucked in from an intake port and exhausts it to the atmosphere from an exhaust port by the action of a pump portion consisting of a rotor and a stator provided in a casing, wherein: A vacuum pump characterized by a removable cooling jacket cover provided on the outer periphery.