JP3038034U - Molecular pump - Google Patents

Abstract

(57) Abstract: For the use of a molecular pump used in processes such as etching and CVD where reaction products adhere, it is possible to perform water cleaning of the pump part without disassembling the rotating part. Provide a possible molecular pump. SOLUTION: The turbo molecular pump part 3 or the thread groove vacuum pump part 4 has a flow passage shape from the upstream side to the downstream side without a recess, and an exhaust port B is provided at the bottom of the pump part. Further, the O-rings 13, 14 and 15 are used to form a watertight structure in the fastening portion, and the purge gas supply pressure adjusting device 16 is used to adjust the purge gas pressure in the bearing housing 6 so that the cleaning water does not enter the bearing housing 6. .

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a molecular pump used in a vacuum generator required in the field of film forming industries such as semiconductors and liquid crystals.

[0002]

[Prior art]

 Molecular pumps include turbo molecular pumps, thread groove vacuum pumps, and composite molecular pumps that combine these two.

These molecular pumps rotate a rotor at a high speed to create a high vacuum. Generally, a bearing housing is arranged inside the rotor, and a driving shaft directly connected to the rotor is provided in the bearing housing. It has a structure in which a motor that drives the drive shaft and a magnetic bearing and a touch down bearing that support the drive shaft are built-in.

When these molecular pumps are used in a process such as etching or CVD (Chemical Vapor Deposition) in which a large amount of reaction products are generated, the reaction products adhere to the space between the moving and stationary blades of the pump section, and The rotation of may become defective.

In such a case, the molecular pump is removed from the apparatus and disassembled and washed to remove the deposits on the pump section.

[0006]

[Problems to be solved by the device]

 Since the molecular pump is a high-speed rotating machine, once disassembled, balancing work is required to rebalance the rotating parts. This work is difficult to handle at the installation site, and it is necessary to send the work to a molecular pump manufacturer, and the need for balancing work each time the pump is cleaned in this way was a troublesome problem.

Further, since most of the reaction products have a property of being soluble in water, it is considered that water is introduced into the pump section to wash the products without decomposing the molecular pump. In the structure of the pump, the cleaning water introduced into the pump may stay in the recess inside the pump, or the motor, magnetic bearings, touchdown bearings, etc. in the bearing housing may be flooded, causing these problems. was there.

An object of the present invention is to solve these problems and to provide a molecular pump capable of washing the pump with water without disassembling.

[0009]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention is a vertical molecular pump of a type having a bearing housing inside a rotor, and has a structure for preventing water from entering from the outer peripheral portion of the rotor into the bearing housing. And

[0010]

[Embodiment of the invention]

 An embodiment in which the present invention is applied to a composite molecular pump will be described with reference to FIG.

In the composite molecular pump 1 of the present invention, a turbo molecular pump section 3 is arranged on the upstream side and a thread groove vacuum pump section 4 is arranged on the downstream side.

The intake port A is located at the top of the pump, and the exhaust port B is located at the bottom of the pump flow path.

The rotor 2 is provided with a turbo molecular pump unit 3 and a rotor unit of a thread groove vacuum pump unit 4, respectively. The rotor 2 is fastened to the drive shaft 2a, and the drive shaft 2a is fastened to the bearing housing 6 via the magnetic bearings 5a and 5b.

The drive shaft 2a has a drive motor 7 mounted between the magnetic bearings 5a and 5b, and touch-down bearings 8 and 9 for starting rotation.

The drive motor 7 is a variable speed motor capable of driving the rotor 2 even at a low rotation speed.

Further, the bearing housing 6 is formed in such a shape that an upper portion thereof is inserted into the inside of the rotor 2, and a screw seal 10 is provided on an outer peripheral portion of the bearing housing 6 at the insertion portion. Is formed close to the inner circumference of the.

In the upper casing 11 forming the outer shell of the molecular pump 1, the turbo molecular pump unit 3 and the thread groove vacuum pump unit 4 are formed on the stator side inside thereof.

These pump parts have a structure in which the shape of the flow passage is as recessed as possible from the upstream side to the downstream side.

The rotor cover 12 on the uppermost portion of the rotor 2 is fastened to the rotor 2 with the O-ring 13 interposed therebetween to form a watertight structure.

Further, the fastening portion between the upper casing 11 and the lower casing 19 and the fastening portion between the bearing casing 6 and the lower casing 19 are also watertight structures using the O-ring 14 and the O-ring 15, respectively.

Reference numeral 16 denotes a purge gas supply pressure adjusting device, which is interposed between the purge gas supply unit 17 and the purge gas inlet 18. In addition, 19 shows a pressure gauge.

Next, the operation of this embodiment will be described.

When the reaction product adheres to the pump unit and needs to be removed, the pumping operation of the molecular pump 1 is interrupted and the pump unit is washed with water.

When the pump portion is washed with water, the intake port A is opened to the atmospheric pressure and the exhaust port B is sealed with a sealing flange (not shown). Introduce clean water to.

At this time, the O-rings 13, 14, 15 are arranged so that the cleaning water introduced to the outer peripheral side of the rotor 2 does not leak inside the rotor 2 or outside the upper and lower casings 11, 19. Works.

Further, in order to prevent the cleaning water from breaking through the screw seal 10 and entering the bearing casing 6, a purge gas such as nitrogen is supplied from the purge gas supply unit 17 and the purge gas pressure adjusting device 16 is used to adjust the bearing casing. The purge gas pressure in 6 is adjusted so that the cleaning water just stays at the screw seal 10.

This is because, for example, when the cleaning water is filled up to the upper surface of the intake port A, a pressure corresponding to a water column head having a height from the upper end of the screw seal 10 to the upper surface of the intake port A is applied to the purge gas. You may

The temperature of the washing water is 70 ° C. to 80 ° C., and the reaction product attached is dissolved and removed by repeating water injection and drainage to the pump section several times.

Further, by energizing the drive motor 7 to rotate the rotor 2 at a low speed, the cleaning effect can be enhanced.

The drainage of this washing water is easily performed by removing the sealing flange of the exhaust port B. Further, since the inside of the pump portion has no recess, cleaning water does not remain in the flow passage.

In the present embodiment, the example of the composite molecular pump is described, but this can be similarly applied to the case of only the turbo molecular pump or the thread groove vacuum pump.

[0032]

[Effect of the invention]

 As described above, according to the present invention, it is possible to provide a molecular pump capable of washing the pump portion with water without disassembling the rotating portion.

[Submission date] December 9, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

Reference numeral 16 denotes a purge gas supply pressure adjusting device, which is interposed between the purge gas supply unit 17 and the purge gas inlet 18. In addition, 20 shows a pressure gauge.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a composite molecular pump according to an embodiment of the present invention.

[Explanation of symbols]

 1 compound molecular pump 2 rotor 6 bearing housing 7 drive motor 10 screw seal 12 rotor covers 13, 14, 15 O-ring 16 purge gas supply pressure control device B exhaust port

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[Procedure amendment]

[Submission date] December 9, 1996

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

Claims (6)

[Utility model registration claims] 1. A vertical molecular pump of a type having a bearing housing inside a rotor, wherein the vertical molecular pump has a structure for preventing water from entering from the outer peripheral portion of the rotor into the bearing housing. 2. The pump portion on the outside of the rotor has a structure in which the shape of the flow passage has no recessed portion from the upstream side to the downstream side, and the exhaust port is provided at the bottom of the pump. The molecular pump according to claim 1, wherein: 3. The molecular pump according to claim 1, further comprising a rotor cover fastened to the uppermost portion of the rotor to cover the central recess. 4. A purge gas introducing means for introducing a purge gas into the bearing housing and a purge gas supply pressure adjusting means having a screw seal between the inside of the rotor and the outer circumference of the bearing housing, and the purge gas. The pressure control device is formed so as to prevent water from entering the inside of the bearing housing from the rotor side.
2. The molecular pump according to any one of 1. 5. The molecular pump according to claim 1, wherein the motor that drives the rotor is a variable speed motor that can also rotate the rotor at a low speed. 6. The molecular pump according to claim 1, wherein an O-ring is provided on each flange surface of the rotor, the bearing housing, and the housing to prevent water from entering.