WO2005042979A1

WO2005042979A1 - Rotary dry vacuum pump

Info

Publication number: WO2005042979A1
Application number: PCT/JP2004/015639
Authority: WO
Inventors: Daisuke Inoue; Satoshi Fujii
Original assignee: Nabtesco Corporation
Priority date: 2003-10-21
Filing date: 2004-10-21
Publication date: 2005-05-12
Also published as: JPWO2005042979A1; TW200525086A; CN1871436A; US20080038132A1; EP1681469A1; KR20060087599A

Abstract

A rotary dry vacuum pump has had a problem that, when a canned motor is used in a drive section, a reaction produced gas enters inside the canned motor, causing a motor failure that leads to a failure of the rotary dry vacuum pump. A rotary dry vacuum pump with rotor of the invention has one or more rotors received in a housing, bearings supporting rotating shafts of the rotors, a suction opening and discharge opening for fluid, formed in the housing, and a motor for rotatingly driving at least one of the one or more rotors. The motor has a stator iron core fixed in the housing of the motor, a partition wall installed on the inner diameter side of the stator is adhered and fixed to the housing to seal off the inside of the partition wall, a rotor is adhered and fixed to a rotating shaft in the separation wall so as to be rotatable, and a gas inlet for pouring a purge gas into the partition wall is provided.

Description

Specification

Rotary dry vacuum pump

Technical field

The present invention relates to a rotary dry vacuum pump having a structure in which a reaction product gas hardly flows into a canned motor which is a power unit of a rotary dry vacuum pump used in a device for flowing a reaction product gas such as a semiconductor manufacturing apparatus. Things.

Background art

A problem in the semiconductor manufacturing process is that impurities such as oil are mixed in the reaction chamber 1 to contaminate the semiconductor. In particular, mixing of oil from a vacuum pump for exhausting gas in the reaction chamber becomes a problem. Therefore, a rotary dry vacuum pump has been conventionally used. Rotary dry vacuum pumps include a screw type, a roots type and a scroll type. However, such a rotary dry vacuum pump has a rotating shaft for rotating the rotor, and a bearing is used to support the rotating shaft. Lubricating oil is usually attached to the bearing, and a shaft seal is arranged between the exhaust chamber and the bearing to prevent oil molecules of the lubricating oil from entering the exhaust chamber of the rotary dry vacuum pump. I was However, if this shaft seal is worn, it may leak through the shaft seal from the exhaust chamber of the rotary dry vacuum pump into the reaction chamber. This is because the motor for rotating the rotor is in the atmosphere and the pressure difference between the motor side and the vacuum exhaust chamber side is large. Therefore, if a gap was formed due to wear of the shaft seal, etc., the air leaked into the exhaust chamber, which reduced the performance of the pump. Therefore, it has come to be used for a rotary dry vacuum pump having a canned motor power rotary drive that can make the pressure inside the motor almost the same as the exhaust chamber. The structure of the canned motor is such that the stator core has a stator winding that generates a rotating magnetic field, and the inside of the partition is sealed by a metal thin-walled cylindrical partition (can) mounted on the frame, side plates, and the stator inner diameter side. The rotating shaft supported by the bearing fixed to the bracket has a rotatable structure with a rotor attached. (Patent Document 1)

Patent Document 1: JP-A-2003-189529 Disclosure of the invention

Problems to be solved by the invention

[0003] When the canned motor is used as a drive unit of a rotary dry vacuum pump for a semiconductor manufacturing apparatus for flowing a reaction product gas while applying force, the inside of the partition wall in which the rotor is housed is evacuated during operation. . Therefore, when the motor is stopped and returned to the atmospheric pressure, the reaction product gas is mixed into the motor from the exhaust chamber and the reaction product adheres to the components inside the partition wall of the canned motor, causing the motor to fail. There was a problem that it would. At that time, if reaction products also adhered to the bearing ゃ shaft seal, it also caused a failure of the pump itself.

Means for solving the problem

[0004] In order to solve this, according to the present invention, according to the first aspect of the present invention, one or more rotors housed in a housing, a bearing for supporting a rotating shaft of these rotors, In a rotary dry vacuum pump having a fluid suction port and a discharge port formed in the housing and a rotary rotor configured to rotate at least one of the one or more rotors, the motor is a stator. A partition provided with an iron core and mounted on the inner diameter side of the stator is fixed to the housing to seal the inside of the partition, and a rotor is rotatably arranged in the partition, and at least one of the plurality of rotors is provided. The rotating shaft of the rotor and the rotating shaft of the rotor are fixedly connected to each other, and the rotor is driven to rotate, and a gas injection port for flowing a purge gas into the partition wall is provided. If the purge gas inlet is formed in the flange of the motor, the processing is easy. The partition walls may be made of a magnetic metal. The purge gas can also flow through a bearing that rotatably supports the rotating shaft of the rotor.

[0005] In the invention of claim 2, the rotating shaft of the motor and the rotating shaft of the rotor are integrally formed. As an assembly example, after fixing the rotor to a flange constituting a housing, a rotor of a motor is fixed to an end of the rotor by a predetermined means on a rotating shaft, and the end is formed by a cylindrical member constituting a partition. The inside of the partition is sealed by fixing to the flange and further covering with a flange constituting the partition. An O-ring should be placed where sealing is required. [0006] According to the invention of claim 3, the motor is arranged on the intake port side. At this time, in order to reduce the amount of bearing force lubricating oil disposed between the exhaust chamber and the motor to leak into the motor, grease may be used instead of lubricating oil. Further effects can be further enhanced by placing the rotary dry vacuum pump vertically and arranging the bearing and motor at the top. In addition, a rotary dry vacuum pump with multiple rotating shafts is installed vertically, a timing gear that requires lubrication for synchronization is arranged on the lower discharge port side, and the motor is arranged on the intake side. Prevent the exhaust chamber from being contaminated by lubricating oil.

[0007] According to the invention of claim 4, a flow rate adjusting means is provided in a pipe for sending a purge gas to the purge gas inlet. As the flow rate adjusting means, there are a means for reducing the flow rate of the purge gas through a purge gas flow hole of a predetermined size in the purge gas flow path, a manual valve as required, and a solenoid valve on the N2 supply side. The solenoid valve is opened and adjusted by the valve when the gas flow rate changes when the pump is stopped, before or after that, and during operation, especially when the pressure in the exhaust chamber becomes higher than the pressure in the motor bulkhead due to increase. By flowing the flow rate as the purge gas, the process gas is prevented from entering the bearing section and the motor section.

Once the flow rate is determined, an orifice that allows the same amount of gas to flow instead of a valve can be installed in the piping to eliminate the adjustment valve.

In addition, when adjusting the inflow amount of gas, it is possible to adjust the opening time of the electromagnetic valve or to use an electromagnetic valve having a flow rate adjusting function.

[0008] According to the invention of claim 5, a pressure measuring instrument for measuring the pressure in the partition wall or a pressure measuring instrument for measuring the pressure in the exhaust chamber is provided. The difference between the two pressure values may be taken, and the flow rate may be adjusted by an electromagnetic valve so that the pressure in the partition wall is equal to or greater than the pressure in the exhaust chamber. Also, the inflow amount and flow rate of the purge gas can be adjusted with only one pressure. As a pressure measuring device, there is a thin film semiconductor detector and the like. Further, the inflow amount and the flow rate of the purge gas can be adjusted by measuring the pressure in a chamber of a semiconductor manufacturing apparatus or the like which is evacuated by a vacuum pump. The inflow and flow rate of gas may be adjusted only by changing the pressure in the chamber, but may be adjusted according to the pressure in the partition.

[0009] According to the invention of claim 6, for measuring the rotation speed of the rotor or the rotor of the motor. Measurement means were provided. As the rotation speed measuring means, the rotation speed is detected by attaching an encoder to the rotor of the motor or detecting the magnetism of the permanent magnet of the rotor at a specific position. The inflow amount and flow rate of the purge gas are adjusted by the rotation speed. For example, when the number of revolutions decreases, the flow of the purge gas is controlled, and the flow rate and the flow rate of the gas are adjusted according to the rate of change of the number of revolutions.

[0010] According to the invention of claim 7, means for measuring the power consumption of the motor is provided. The gas flow is adjusted by the power consumption. For example, if the power consumption fluctuates due to an increase in the intake gas amount during operation, control of the purge gas flow is performed, and the inflow amount and flow rate of the purge gas are adjusted according to the change in the power consumption at the time of stoppage. You can do it.

According to the invention of claim 8, the reaction product gas flow meter is provided near the intake port or the exhaust port. The flow rate of the purge gas is adjusted according to the change in the flow rate of the reaction product gas. For example, when the flow rate of the reaction product gas increases, control is performed such as increasing the flow rate of the purge gas. Further, the flow rate of the purge gas may be adjusted according to the flow rate of the gas flowing into the chamber.

The invention's effect

[0012] According to the invention of claim 1, one or more rotors housed in a housing, a bearing for supporting a rotating shaft of these rotors, and a fluid intake port and a discharge port formed in the housing. A rotary dry vacuum pump having a rotary rotor composed of a motor that rotationally drives at least one of the single or multiple rotors, wherein the motor includes a stator core fixed inside a motor housing, A partition mounted on the inner diameter side of the stator is fixed to the housing to seal the inside of the partition, and a rotor is fixed to a rotating shaft in the partition so as to be rotatable, and a purge gas flows into the partition. Due to the gas inlet, the reaction product gas force in the vacuum exhaust chamber and the inside of the bulkhead from the exhaust chamber when the inside of the vacuum exhaust chamber and the bulkhead return to atmospheric pressure when the pump is stopped. In order to prevent the product from accumulating in the motor components such as the rotor due to leakage and causing the motor not to operate or break down, the purge gas should be supplied to prevent the reaction product gas from flowing into the partition from the vacuum exhaust chamber. it can. In addition, by similarly supplying the purge gas to the bearing, it is possible to prevent the reaction product from adhering to the bearing and to prevent the bearing from malfunctioning. [0013] According to the invention of claim 2, by forming the rotation shaft of the motor and the rotation shaft of the rotor integrally, the joining part of the two rotation shafts becomes unnecessary, and further two rotation shafts are eliminated. There is no need to align the turning axes.

[0014] According to the invention of claim 3, by arranging the motor on the intake port side, normally, a portion that requires lubricating oil to prevent the exhaust chamber from being contaminated with oil is discharged. It is located on the exit side. Therefore, by arranging the motor on the side of the intake port where lubricating oil is not used much, it is possible to minimize lubricating oil from entering the partition wall.

[0015] According to the invention of claim 4, the pipe for sending gas to the purge gas inlet is provided with a flow rate adjusting means. With such a configuration, the minimum amount of purge gas required to prevent the process gas from entering the partition wall during the stop can be supplied, thereby suppressing useless use of N2 and adhering to the bearing. Diffusion of the lubricating material into the exhaust chamber can be minimized.

According to the invention of claim 5, a pressure measuring instrument for measuring the pressure in the partition or a pressure measuring instrument for measuring the pressure in the exhaust chamber is provided. With such a configuration, the flow rate of the purge gas can be controlled by an electromagnetic valve or the like so that the pressure in the partition wall becomes slightly higher than the pressure in the exhaust chamber.

[0017] According to the invention of claim 6, by providing a measuring means for measuring the number of rotations of the rotor or the rotor of the motor, it becomes possible to control the flow of only a necessary purge gas. This eliminates the waste of gas and the leakage of purge gas into the exhaust chamber, which does not deteriorate the exhaust capacity.

[0018] According to the invention of claim 7, since the means for measuring the power consumption of the motor is provided, it is possible to control the flow of only the necessary purge gas, thereby wasting gas and purging the purge gas into the exhaust chamber. Does not leak and deteriorates the exhaust capacity.

According to the invention of claim 8, by providing a gas flow meter near the intake port or the exhaust port, it becomes possible to control the flow of only a necessary purge gas, thereby wasting gas and reducing exhaust gas into the exhaust chamber. This prevents the purge gas from leaking and deteriorating the exhaust capacity.

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 shows a screw vacuum pump as an embodiment of the rotary dry vacuum pump according to the present invention.

[0021] The vacuum pump 200 includes two screw rotors 202 and 204.

Screw rotors 202 and 204 are housed inside housing 210. More specifically, the screw rotor 202 is rotatably supported on the housing 210 by bearings 231 and 233, and the screw rotor 204 is rotatably supported on the housing 210 by bearings 234 and 236. In addition, the timing gears 251 and 253, the motor 241 and the seals 237, 238, 239 and 240 are placed as shown in the figure. Here, the shears 237 and 238 separate the bearings 231 and 233 from the inner chamber 210b of the rotor and set the bearings 231 and 233 together. This prevents leap oil from leaking into the screw rotor storage room 210b and prevents foreign substances from entering the bearings 231 and 233 from the screw rotor storage room 210b. Similarly, the shears 239 and 240 separate the bearings 234 and 236 from the inner chamber 210b of the rotor, prevent the lubricating oil of the bearings 234 and 236 from leaking into the screw rotor storage chamber 210b, and prevent the rotation of the screw rotor. It prevents foreign matter from entering the bearings 234 and 236 from the storage room 210b. As the chinoles 237, 238, 239, and 240, there are a non-contact seal such as an insect-type chinolle, a magnetic fluid seal, and a labyrinth.

Further, timing gears 251 and 253 for rotating the screw rotor 202 with the rotation of the screw rotor 204 are fixed to one ends of the screw rotor 202 and the screw rotor 204 so as to mesh with each other. . Further, a motor 241 is physically connected to the other end of the screw rotor 202.

The screw rotor storage chamber 210b is formed on a wall of the housing 210, and an external force of the housing 210 is also provided by an intake port (not shown) for sucking a compressible fluid into the housing 210. The screw rotor storage chamber 210 b communicates with the outside of the housing 210, and a screw outlet (not shown) is formed in the wall of the housing 210 to discharge a compressible fluid from inside the housing 210 to outside the housing 210. ) Communicates with the outside of the housing 210. Here, the suction port is communicated with a not-shown vacuum vessel, and the discharge port is shown in FIG.

[0024] The housing 210 includes a first housing member 211, a second housing member 212, and a second housing member 212. The third housing member 213, the fourth housing member 214, and the fifth housing member 215 are formed. Here, the first housing member 211 constitutes an intake side flange and also serves as a housing for the canned motor 241. The second housing member 212, the third housing member 213, and the fourth housing member 214 form a housing body, and the second housing member 212, the third housing member 213, and the fourth housing member 214 form a vacuum exhaust chamber. Have been. Bearings 231 and 234 and shaft seals 237 and 239 are fixed to the second housing member 212. Further, the fourth housing member 214 is fixed with the bearings 233 and 236 and the shaft shear rollers 238 and 240.

Next, a configuration of the canned motor 241 which is a driving unit of the vacuum pump 200 according to the present embodiment will be described. The canned motor 241 has a stator core 261 provided with a stator winding for generating a rotating magnetic field. On the inner diameter side of the stator, a rotor 265 is fixed to a rotating shaft 263 of a canned motor 241 integrated with the rotor 202. A partition (can) 281 is separated between the stator core 261 and the rotor 265, and the partition 281 is tightly fixed to the second housing member 212. The flange 267 of the canned motor 241 is tightly fixed to the partition wall 281, and the rotor 265 is also sealed against external air. A purge gas (for example, nitrogen gas or argon gas) is supplied to the inside of the partition wall 281 in which the joint is sealed with a ring or the like (not shown), the housing second member 212 and the canned motor 241 sealed with the flange 267. Injection hole 269 for flowing is open. The injection hole 269 is provided with a flow passage 271 for introducing a purge gas, and the flow passage 271 has flow rate adjusting means (for example, a manual valve, an orifice, etc.) 273 for adjusting the flow rate of the purge gas, and a solenoid valve 273. 275 is installed.

Next, the operation of the vacuum pump 200 according to the present embodiment will be described.

First, when the canned motor 241 rotates the screw rotor 202, the timing gears 253 and 251 are fixed to one end of the screw rotor 204 and one end of the screw rotor 202 so as to mesh with each other. The screw rotor 204 rotates with the rotation of the screw rotor 202. As the screw rotor 202 and the screw rotor 204 rotate, the compressible fluid in the screw rotor storage chamber 210b is also transferred to the communication passage 210c with the intake-port-side force, and is discharged through the communication passage 210c. Also, screw rotor storage room 2 When the compressible fluid in 10b is discharged to the outside of the screw rotor storage chamber 210b through the communication passage 210c, a new compressible fluid is sucked into the screw rotor storage chamber 210b through the suction port and the force of the vacuum container is also suctioned. You.

At this time, the inside of the canned motor 241 sealed by the housing first member 211, the housing second member 212, and the flange 267 is evacuated.

Therefore, when the vacuum pump is stopped, the pressure in the exhaust chamber 210c rises, and the gas in the exhaust chamber 210c reduces the pressure of the canned motor 241 sealed by the housing first member 211, the housing second member 212, and the flange 267 with low pressure. It flows back inside. When the gas in the exhaust chamber is a corrosive gas or a reaction product gas, the gas may cause corrosion of the rotor 265 and the rotating shaft 263, and may cause a failure of the canned motor 241 due to adherence of products. Therefore, when a corrosive gas or a reaction product gas flows, the pressure inside the canned motor 241 sealed by the housing first member 211, the housing second member 212, and the flange 267 becomes higher than the pressure inside the exhaust chamber 210c. Purge gas as described above. Therefore, assuming that the flow rate of the purge gas is P1 inside the can motor and the pressure inside the exhaust chamber 210c closest to the can motor 241 is P2, the flow rate may be such that P1≥P2 after the pump stops. The operation sequence is as follows: When the pump stops or before or after the pump stops, the solenoid valve is opened, and the flow rate L adjusted by the valve (manual valve or solenoid valve or orifice) is flowed as purge gas, so that the bearing section, Prevent process gas from entering the motor. If the time T required for P1 to reach the atmospheric pressure is preliminarily measured, the solenoid valve can be opened and the flow rate L can be supplied only during the time T.

Therefore, a minimum necessary purge gas can be supplied, useless use of the purge gas can be suppressed, and diffusion of the lubricant adhering to the bearing portion into the exhaust chamber can be minimized. Further, the pressure inside the canned motor 241 sealed by the housing first member 211, the housing second member 212 and the flange 267 is measured by a pressure gauge P1, and the pressure inside the exhaust chamber 210c is measured by a pressure gauge P2. There is also a method of controlling the flow rate with an electromagnetic valve so that the difference between the pressures becomes P1≥P2. (Instead of “valve + solenoid valve”, use an electromagnetic valve that can freely control the flow rate.) The flow rate control is not limited to stoppage, but continues to flow the purge gas slightly during operation so that P1 ≥ P2. The flow rate of the reaction product gas may change during the operation. In such a case, the pressure in the exhaust chamber may change, so the flow rate of the purge gas is controlled so that P1 ≥ P2.

Further, the pressure in the exhaust chamber can be replaced with the pressure in the semiconductor manufacturing apparatus chamber using the vacuum pump.

In this embodiment, the flow rate of the purge gas is controlled by comparing the two pressures. The flow rate can be controlled by any one of the pressure inside the motor partition wall, the pressure inside the exhaust chamber, or the pressure inside the chamber.

In this embodiment, the pressure can be measured to control the force by controlling the flow rate of the purge gas, or by controlling the rotation speed of the rotor, the power consumption, and the flow rate of the reaction product gas. Monkey

Further, in the present embodiment, the force indicated only for the purge gas to the motor If the purge gas is allowed to flow also to the bearing, a reaction product adheres to the bearing and the rotary dry vacuum pump loses power. Can also be prevented.

[0029] In general, a semiconductor manufacturing apparatus dislikes contamination by oil. However, as in the present embodiment, a vertically installed mold is used, and an intake port is arranged upward with a discharge port arranged downward. The gears 251 and 253 are disposed below, and the canned motor 241 which does not use lubricating oil and is not likely to be contaminated by lubricating oil is disposed on the intake side. This can minimize contamination of the intake side with oil. The effect is further enhanced by using vacuum grease as a lubricant for the bearing on the intake side.

[0030] In the present embodiment, the volume transfer type screw vacuum pump has been described. However, the present invention is applied to a vacuum pump in which a rotary shaft of a claw type, a roots type, a scroll type, or the like is driven by a motor. be able to.

In addition, each of a plurality of stages of vacuum pumps, for example, a two-stage screw vacuum pump, may have the structure of the rotary dry vacuum pump of the present invention.

The pressure, gas flow rate, power consumption, and number of revolutions are converted into data electric signals and sent to the signal processing means. From the data electric signals, the flow rate of the purge gas is determined by the signal processing means. , And transmitted to the flow rate adjusting means, and the flow rate of the purge gas is adjusted by an electromagnetic valve or the like. Industrial applicability

[0031] The present invention can be applied to a vacuum pump having a rotating shaft for flowing and exhausting extremely dilute reaction product gas and a motor for driving the rotating shaft, such as a semiconductor manufacturing apparatus.

Brief Description of Drawings

FIG. 1 is an axial sectional view of the screw vacuum pump of the present invention.

Explanation of symbols

[0033] 200 vacuum pump

202, 204 screw rotor

210 housing

210b Rotor storage room

231, 233, 234, 236 bearings

251, 253 Timing gear

237, 238, 239, 240 Shaft seal

241 canned motor

261 Stator core

263 Rotating shaft

265 rotor

267 Flange

269 Injection hole

271 Flow passage

Claims

The scope of the claims

[1] One or more rotors housed in a housing, bearings for supporting the rotating shafts of these rotors, fluid inlets and outlets formed in the housing, and one or more rotors In a rotary dry vacuum pump having a rotary rotor configured to rotate at least one of the motors, the motor includes a stator core, and a partition mounted on a stator inner diameter side is fixed to the housing and the partition is fixed to the housing. A rotor is rotatably arranged in the partition wall, and a rotation shaft of at least one of the plurality of rotors and a rotation shaft of the rotor are fixed to drive the rotor to rotate. A rotary dry vacuum pump characterized by having a gas inlet for flowing a purge gas into a partition wall.

[2] The rotary dry vacuum pump according to claim 1, wherein a rotation axis of the motor and a rotation axis of the rotor are formed integrally.

3. The rotary dry vacuum pump according to claim 12, wherein the motor is arranged on an intake port side.

4. The rotary dry vacuum pump according to claim 13, wherein flow rate adjusting means is provided in a pipe for sending a purge gas to the purge gas inlet.

[5] The rotation according to claim 14, wherein a pressure measuring instrument for measuring the pressure in the partition wall or a pressure measuring instrument for measuring the pressure in the exhaust chamber is provided. Dry vacuum pump.

6. The rotary dry vacuum pump according to claim 14, further comprising a measuring unit for measuring a rotation speed of a rotor or a rotor of the motor.

7. The rotary dry vacuum pump according to claim 14, further comprising means for measuring power consumption of the motor.

[8] The rotary dry vacuum pump according to claim 14, wherein a gas flow meter is provided near the intake port or the exhaust port or in a vacuum chamber.