JP2006342688A - Evacuation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an evacuation system capable of improving efficiency in the evacuation system, by operating to a process state in an optimal state. <P>SOLUTION: This evacuation system 10 has vacuum pumps 20 and 30 and a pressure sensor 50 arranged in a vacuum area in the evacuation system 10. The vacuum pumps 20 and 30 have a pair of rotors for transferring gas, a motor for rotating the pair of rotors, a timing gear for synchronizing the pair of rotors, and drivers 26 and 36 for controlling a rotating speed of the motor. The evacuation system 10 also has a control part 60 for controlling a rotating speed of the rotors via the drivers 26 and 36 of the vacuum pumps 20 and 30 on the basis of pressure detected by the pressure sensor 50. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an evacuation system, and more particularly to an evacuation system that evacuates a vacuum chamber used in a semiconductor manufacturing process, a liquid crystal manufacturing process, and the like.

  Conventionally, in a semiconductor manufacturing process, a liquid crystal manufacturing process, and the like, a vacuum exhaust system that exhausts a vacuum chamber to a vacuum is used. In such an evacuation system, the vacuum pump is rated for operation regardless of the situation of the semiconductor manufacturing process, the liquid crystal manufacturing process, and the like. However, if the rated operation of the vacuum pump is continued regardless of the process state, the load on the vacuum pump increases as the amount of gas (gas load) transferred by the vacuum pump increases. For this reason, there exists a problem that the efficiency of a vacuum exhaust system worsens and the lifetime of a vacuum pump becomes short.

  In the evacuation system, the vacuum pump is cooled by cooling water, and this cooling water is always supplied to the vacuum pump regardless of the process state. For this reason, when the load is small, the cooling water is supplied more than necessary, and there is a problem that the cooling water is wasted.

  Further, depending on the type of process gas introduced into the vacuum pump, reaction by-products may solidify inside the vacuum pump. Such reaction by-products can be mixed into pump rotor bearings and lubricating oil, which can shorten the life of the vacuum pump, preventing reaction by-products from entering the vacuum pump bearings. For this purpose, nitrogen gas (shaft seal gas) is introduced.

  In conventional evacuation systems, a fixed amount of shaft seal gas is always introduced regardless of the process conditions. However, introduction of a large amount of shaft seal gas affects the ultimate pressure of the pump when there is no load. In some cases, the amount of shaft seal gas to be reduced must be reduced. However, if the amount of the shaft seal gas is reduced, there is a problem that the reaction by-product is mixed into the bearings of the pump rotor and the lubricating oil and the vacuum pump is stopped.

  The present invention has been made in view of such problems of the prior art, and provides a vacuum exhaust system that can be operated in a state optimal for a process state to improve the efficiency of the vacuum exhaust system. Objective.

  According to the first aspect of the present invention, there is provided a vacuum exhaust system capable of operating a vacuum pump at a rotation speed optimum for a process state to improve the efficiency of the vacuum exhaust system and extend the life of the vacuum pump. Is done. The evacuation system includes at least one vacuum pump and a pressure sensor installed in a vacuum region in the evacuation system. The vacuum pump includes a pair of rotors that transfer gas, a motor that rotates the pair of rotors, a timing gear that synchronizes the pair of rotors, and a driver that controls the rotation speed of the motor. The vacuum exhaust system further includes a control unit that controls the rotational speed of the rotor via a driver of the at least one vacuum pump based on the pressure detected by the pressure sensor.

  The at least one vacuum pump is preferably composed of a front-stage vacuum pump and a rear-stage vacuum pump, and the controller controls the rotational speed of the rotor of the front-stage pump based on the pressure detected by the pressure sensor. It is preferable to control. Moreover, it is preferable that the said control part reduces the rotational speed of the said rotor, when the pressure detected by the said pressure sensor becomes larger than predetermined value.

  According to the second aspect of the present invention, there is provided an evacuation system that can supply cooling water to a vacuum pump at a flow rate optimum for a process state, thereby improving the efficiency of the evacuation system and eliminating waste of the cooling water. Provided. The evacuation system includes at least one vacuum pump, a pressure sensor installed in a vacuum region in the evacuation system, and a cooling water system that supplies cooling water to the at least one vacuum pump. The vacuum pump includes a pair of rotors that transfer gas, a motor that rotates the pair of rotors, and a timing gear that synchronizes the pair of rotors. The vacuum exhaust system further includes a control unit that controls the flow rate of the cooling water flowing through the cooling water system based on the pressure detected by the pressure sensor. The control unit preferably increases the flow rate of the cooling water flowing through the cooling water system when the pressure detected by the pressure sensor becomes larger than a predetermined value.

  According to the third aspect of the present invention, the shaft seal gas is supplied to the vacuum pump at a flow rate optimum for the process state, thereby improving the efficiency of the vacuum exhaust system and mixing reaction by-products in the bearing portion of the vacuum pump. An evacuation system that can prevent this is provided. The evacuation system includes at least one vacuum pump, a pressure sensor installed in a vacuum region in the evacuation system, and a gas system that supplies a shaft seal gas to the at least one vacuum pump. The vacuum pump includes a pair of rotors that transfer gas, a motor that rotates the pair of rotors, and a timing gear that synchronizes the pair of rotors. The vacuum exhaust system further includes a control unit that controls the flow rate of the shaft seal gas flowing through the gas system based on the pressure detected by the pressure sensor. The control unit preferably increases the flow rate of the shaft seal gas flowing through the gas system when the pressure detected by the pressure sensor becomes larger than a predetermined value.

  According to the fourth aspect of the present invention, there is provided an evacuation system capable of operating a vacuum pump at a rotation speed optimum for a process state to improve the efficiency of the evacuation system and prolong the life of the vacuum pump. Is done. The evacuation system includes at least one vacuum pump. The vacuum pump includes a pair of rotors that transfer gas, a motor that rotates the pair of rotors, a timing gear that synchronizes the pair of rotors, and a driver that controls the rotation speed of the motor. The vacuum evacuation system is configured to control a rotational speed of the rotor via a driver of the at least one vacuum pump based on a signal indicating a process state in a vacuum chamber to which the at least one vacuum pump is connected. Is further provided.

  According to the fifth aspect of the present invention, there is provided an evacuation system capable of supplying cooling water to a vacuum pump at a flow rate optimum for a process state, improving efficiency of the evacuation system and eliminating waste of cooling water. Provided. The vacuum exhaust system includes at least one vacuum pump and a cooling water system that supplies cooling water to the at least one vacuum pump. The vacuum pump includes a pair of rotors that transfer gas, a motor that rotates the pair of rotors, and a timing gear that synchronizes the pair of rotors. The vacuum exhaust system further includes a control unit that controls the flow rate of the cooling water flowing through the cooling water system based on a signal indicating a process state in the vacuum chamber to which the at least one vacuum pump is connected.

  According to the sixth aspect of the present invention, the shaft seal gas is supplied to the vacuum pump at a flow rate optimum for the process state to improve the efficiency of the vacuum exhaust system and the reaction by-product is mixed in the bearing portion of the vacuum pump. An evacuation system that can prevent this is provided. The vacuum exhaust system includes at least one vacuum pump and a gas system that supplies shaft seal gas to the at least one vacuum pump. The vacuum pump includes a pair of rotors that transfer gas, a motor that rotates the pair of rotors, and a timing gear that synchronizes the pair of rotors. The evacuation system further includes a control unit that controls the flow rate of the shaft seal gas flowing through the gas system based on a signal indicating a process state in a vacuum chamber to which the at least one vacuum pump is connected.

  According to the first and fourth aspects of the present invention, the pressure sensor detects the pressure in the vacuum region in the evacuation system, and based on the detected pressure, or on the basis of a signal indicating the state of the process, Since the rotation speed of the rotor of the vacuum pump can be controlled, the rotation speed of the vacuum pump can be adjusted to the optimum speed for the process state. Therefore, the efficiency of the vacuum exhaust system can be improved and the life of the vacuum pump can be extended.

  According to the second and fifth aspects of the present invention, the pressure sensor detects the pressure in the vacuum region in the evacuation system, and based on the detected pressure or on the basis of the signal indicating the state of the process, Since the flow rate of the cooling water supplied to the vacuum pump can be controlled, the flow rate of the cooling water supplied to the vacuum pump can be adjusted to an optimum amount for the process state. Therefore, the efficiency of the vacuum exhaust system can be improved and the waste of cooling water can be eliminated.

    According to the third and sixth aspects of the present invention, the pressure sensor detects the pressure in the vacuum region in the evacuation system, and based on the detected pressure or based on the signal indicating the state of the process, Since the flow rate of the shaft seal gas supplied to the vacuum pump can be controlled, the flow rate of the shaft seal gas supplied to the vacuum pump can be adjusted to an optimum amount for the process state. Therefore, the efficiency of the vacuum exhaust system can be improved, and reaction by-products can be prevented from being mixed into the bearing portion of the vacuum pump without affecting the ultimate pressure of the pump when there is no load.

  Hereinafter, embodiments of an evacuation system according to the present invention will be described in detail with reference to FIGS. 1 to 8. 1 to 8, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic diagram showing an evacuation system 10 according to the first embodiment of the present invention. As shown in FIG. 1, this evacuation system 10 evacuates a vacuum chamber 12 used in a semiconductor manufacturing process, a liquid crystal manufacturing process, and the like, and includes two vacuum pumps 20 and 30 and a pre-stage vacuum pump. 20 and a post-stage vacuum pump 30, a pressure sensor 50 that detects the pressure inside the connection pipe 40, and a controller 60 that controls the vacuum pumps 20 and 30. The pressure sensor 50 detects the pressure of the gas in the connection pipe 40 that is a vacuum region, and a signal of the detected pressure value is sent to the control unit 60. The pressure sensor 50 may be attached anywhere in the vacuum region. For example, the pressure sensor 50 may be attached between the vacuum chamber 12 and the upstream vacuum pump 20.

  The front-stage vacuum pump 20 includes a casing 21 that houses a pair of rotors, a motor stator 22 that rotates the rotor, a gear cover 23 that houses a timing gear that rotates the pair of rotors in synchronization, a casing 21, and a motor stator 22. , A second side cover 25 disposed between the casing 21 and the gear cover 23, and a driver 26 for controlling the rotational speed of the motor stator 22. ing. The driver 26 receives the signal from the control unit 60 and rotates the motor at a predetermined rotation speed.

  When the motor stator 22 is driven in the front-stage vacuum pump 20, the pair of rotors rotate in the opposite direction without contact while holding a slight gap between the inner surface of the casing 21 and the rotors. As the pair of rotors rotate, the gas on the suction side is confined between the rotor and the casing 21 and transferred to the connection pipe 40 on the discharge side.

  The rear vacuum pump 30 includes a casing 31 that houses a pair of rotors, a motor stator 32 that houses a motor that rotates the rotor, a gear cover 33 that houses a timing gear that rotates the pair of rotors in synchronization, and a casing 31. And a gear cover 33, and a driver 36 for controlling the rotational speed of the motor stator 32. The driver 36 receives the signal from the control unit 60 and rotates the motor at a predetermined rotation speed.

  When the motor stator 32 is driven in the rear-stage vacuum pump 30, the pair of rotors rotate in the opposite direction without contact while holding a slight gap between the inner surface of the casing 31 and the rotors. As the pair of rotors rotate, the gas in the connection pipe 40 on the suction side is confined between the rotor and the casing 31 and transferred to the discharge side.

  Here, when the amount of gas (gas load) transferred by the vacuum pumps 20 and 30 increases, the load applied to the vacuum pumps 20 and 30 also increases, and the pressure of the gas in the connection pipe 40 also increases. Therefore, in the present embodiment, when the pressure of the gas in the connection pipe 40 is detected by the pressure sensor 50 and the detected pressure value exceeds a predetermined set value, the pre-stage vacuum pump 20 and / or the post-stage vacuum pump. A command (signal) is sent from the controller 60 to the driver 26 and / or the driver 36 so as to reduce the rotational speed of the motor 30. In this way, the load on the vacuum pumps 20 and 30 when the amount of gas to be transferred increases is reduced.

  Further, the process state of the vacuum chamber 12 can be grasped by the pressure value detected by the pressure sensor 50. For example, the stop and start of the semiconductor manufacturing process and the liquid crystal manufacturing process in the vacuum chamber 12 can be detected based on the pressure value detected by the pressure sensor 50. Therefore, the process state of the vacuum chamber 12 is grasped from the pressure value detected by the pressure sensor 50, and the rotation speed of the front-stage vacuum pump 20 and / or the rear-stage vacuum pump 30 is controlled so that the rotation speed is suitable for the process state. May be.

  For example, when the process is stopped, as shown in FIG. 2A, the rotational speed of the rear vacuum pump 30 may be decreased after the rotational speed of the front vacuum pump 20 is first decreased. Further, at the start of the process, as shown in FIG. 2B, the rotational speed of the front vacuum pump 20 may be increased after the rotational speed of the rear vacuum pump 30 is first increased. The rear-stage vacuum pump 30 greatly affects the exhaust performance of the vacuum exhaust system 10. For example, when the rotational speed is increased again after lowering the rotational speed, the calorific value does not increase immediately. Therefore, the rotational speed of the rear vacuum pump 30 is not changed as it is, and the rotor and the casing 31 due to thermal expansion are not changed. The clearance between them may be kept constant. Further, considering the countermeasures for the reaction by-products, it is preferable to keep the rotation speed of the rear vacuum pump 30 constant in order to maintain the temperature.

  FIG. 3 is a schematic diagram showing an evacuation system 110 according to the second embodiment of the present invention. As shown in FIG. 3, the evacuation system 110 includes a cooling water system 170 that supplies cooling water to the upstream vacuum pump 20 and the downstream vacuum pump 30 in addition to the configuration of the first embodiment. This cooling water system 170 passes cooling water from the introduction port 171 through the motor stator 32 of the rear vacuum pump 30, the rotor final stage 131 of the casing 31, and the gear cover 33, and further the gear cover 23 of the front vacuum pump 20 and the motor. After passing through the stator 22, it is discharged from the discharge port 172, and the rear vacuum pump 30 and the front vacuum pump 20 are cooled.

  A normal line 173 and an increase line 174 are provided upstream of the downstream vacuum pump 30 in the cooling water system 170. The flow rate of the cooling water flowing in the normal line 173 is, for example, 1 l / min, and the flow rate of the cooling water flowing in the increase line 174 is, for example, 5 l / min. The increase line 174 is provided with a solenoid valve 175.

  In this embodiment, the process state of the vacuum chamber 12 is grasped from the pressure value detected by the pressure sensor 50, and the cooling water flowing through the cooling water system 170 is adjusted so that the flow rate is suitable for the process state. That is, when the pressure value detected by the pressure sensor 50 exceeds a predetermined set value, the electromagnetic valve 175 of the increase line 174 is opened, and the amount of cooling water flowing through the cooling water system 170 is increased. In this way, the amount of cooling water flowing through the cooling water system 170 can be adjusted to an appropriate amount according to the process state, so that waste of cooling water is eliminated and the vacuum pumps 20 and 30 are efficiently cooled. Can do.

  Further, instead of the normal line 173 and the increase line 174, an electromagnetic valve 176 is provided in the vicinity of the introduction port 171, and the total flow rate of the cooling water system 170 is adjusted by opening and closing the electromagnetic valve 176. Also good. Furthermore, instead of the pressure sensor 50 installed in the connection pipe 40, a pressure sensor 177 is provided in the connection pipe 13 that connects the upstream vacuum pump 20 and the vacuum chamber 12, and based on the pressure value detected by the pressure sensor 177. The amount of cooling water flowing through the cooling water system 170 may be controlled.

  Here, since the rotor last stage part 131 of the casing 31 is on the atmospheric pressure side, the heat generation amount is increased. Therefore, in the present embodiment, the cooling water system 170 is passed through the rotor final stage 131 of the casing 31 to cool the rotor final stage 131 with the cooling water. However, if the rotor final stage 131 is cooled too much, the gas may solidify and adhere to the casing 31. For this reason, in this embodiment, the temperature sensor 132 is provided in the rotor final stage 131, the temperature of the rotor final stage 131 is measured, and the rotor final stage 131 is maintained at a moderately high temperature. As shown in FIG. 3, a three-way valve 178 is provided in the cooling water system 170 upstream of the rotor final stage 131, and this three-way valve 178 is connected to the downstream side of the rotor final stage 131. A bypass pipe 179 is attached.

  FIG. 4 is a schematic diagram showing an evacuation system 210 in the third embodiment of the present invention. As shown in FIG. 4, in addition to the configuration of the first embodiment, the vacuum exhaust system 210 includes a nitrogen gas system 270 that supplies nitrogen gas as a shaft seal gas to the front vacuum pump 20 and the rear vacuum pump 30. I have. This nitrogen gas system 270 is supplied with nitrogen from the introduction port 271 to the first side cover 24, the second side cover 25 of the front vacuum pump 20, the shaft seal portion 231a in the casing 31 of the rear vacuum pump 30, and the side cover 35, respectively. Gas is supplied to prevent reaction by-products from entering the bearing portions of the front vacuum pump 20 and the rear vacuum pump 30.

  The nitrogen gas system 270 includes a normal line 273 and an increase line 274, and the increase line 274 is provided with an electromagnetic valve 275. In the present embodiment, the process state of a vacuum chamber (not shown) is grasped from the pressure value detected by the pressure sensor 50, and the nitrogen gas flowing through the nitrogen gas system 270 is adjusted so that the flow rate is suitable for the process state. . That is, when the pressure value detected by the pressure sensor 50 exceeds a predetermined set value, the electromagnetic valve 275 of the increase line 274 is opened, and the amount of nitrogen gas flowing through the nitrogen gas system 270 is increased. Thus, since the amount of nitrogen gas flowing through the nitrogen gas system 270 can be adjusted to an appropriate amount according to the process state, the vacuum pump 20, without affecting the ultimate pressure of the pump at no load, It is possible to prevent reaction by-products from entering the 30 bearing portions.

  Since the upstream vacuum pump 20 lowers the ultimate pressure of the upstream vacuum chamber, the flow rate of nitrogen gas flowing into the upstream vacuum pump 20 through the increase line 274a is increased through the increase line 274b. It is less than the flow rate of nitrogen gas flowing into 30. Also, electromagnetic valves (for example, indicated by reference numerals 276 and 277) are respectively provided in the supply parts to the front-stage vacuum pump 20 and the rear-stage vacuum pump 30 of the nitrogen gas system 270, and the amount of nitrogen gas supplied to each part is individually controlled. May be.

  FIG. 5 is a schematic diagram showing an evacuation system 310 according to the fourth embodiment of the present invention. As shown in FIG. 5, this evacuation system 310 uses an external input signal 370 indicating a process state instead of using the pressure sensor 50 in the evacuation system 10 in the first embodiment shown in FIG. And the rotational speeds of the front vacuum pump 20 and the rear vacuum pump 30 are adjusted based on the external input signal 370. About another point, it is the same as that of 1st Embodiment mentioned above.

  FIG. 6 is a schematic diagram showing an evacuation system 410 according to the fifth embodiment of the present invention. As shown in FIG. 6, this evacuation system 410 uses an external input signal 370 indicating a process state instead of using the pressure sensor 50 in the evacuation system 110 in the second embodiment shown in FIG. And the flow rate of the cooling water supplied to the upstream vacuum pump 20 and the downstream vacuum pump 30 is adjusted based on the external input signal 370. Other points are the same as in the second embodiment described above.

  FIG. 7 is a schematic diagram showing an evacuation system 510 according to the sixth embodiment of the present invention. As shown in FIG. 7, this evacuation system 510 uses an external input signal 370 indicating a process state instead of using the pressure sensor 50 in the evacuation system 210 in the third embodiment shown in FIG. And the flow rate of the nitrogen gas supplied to the pre-stage vacuum pump 20 and the post-stage vacuum pump 30 is adjusted based on the external input signal 370. Other points are the same as in the third embodiment described above.

  FIG. 8 is a schematic diagram showing an evacuation system 610 according to the seventh embodiment of the present invention. This vacuum exhaust system 610 is a combination of the first to sixth embodiments described above. In this case, based on the pressure value detected by the pressure sensor 50, the rotational speeds of the upstream vacuum pump 20 and the downstream vacuum pump 30, the flow rate of the cooling water supplied to the upstream vacuum pump 20 and the downstream vacuum pump 30, and the upstream The flow rate of nitrogen gas supplied to the vacuum pump 20 and the post-stage vacuum pump 30 may be adjusted, or an external input signal 370 indicating a process state is input to the control unit 60, and based on the external input signal 370. , Rotational speeds of the front vacuum pump 20 and the rear vacuum pump 30, the flow rate of cooling water supplied to the front vacuum pump 20 and the rear vacuum pump 30, and the flow rate of nitrogen gas supplied to the front vacuum pump 20 and the rear vacuum pump 30 May be adjusted.

  Here, the external input signal 370 is a signal indicating the stop and start of the process, and is information indicating the process state more accurately than the detection value of the pressure sensor 50. Therefore, when the external input signal 370 can be used, it is not necessary to use the pressure sensor 50. Further, if the process stop or start can be input to the control unit 60 as the external input signal 370 before the actual process time, the process can be stopped or started after the front-stage vacuum pump 20 and the rear-stage vacuum pump 30 are optimized. It becomes.

  Although one embodiment of the present invention has been described so far, it is needless to say that the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea.

It is a schematic diagram which shows the vacuum exhaust system in the 1st Embodiment of this invention. It is a graph which shows the change of the rotational speed in the 1st Embodiment of this invention. It is a schematic diagram which shows the vacuum exhaust system in the 2nd Embodiment of this invention. It is a schematic diagram which shows the vacuum exhaust system in the 3rd Embodiment of this invention. It is a schematic diagram which shows the vacuum exhaust system in the 4th Embodiment of this invention. It is a schematic diagram which shows the vacuum exhaust system in the 5th Embodiment of this invention. It is a schematic diagram which shows the vacuum exhaust system in the 6th Embodiment of this invention. It is a schematic diagram which shows the vacuum exhaust system in the 7th Embodiment of this invention.

Explanation of symbols

10, 110, 210, 310, 410, 510, 610 Vacuum exhaust system 12 Vacuum chamber 20, 30 Vacuum pump 21, 31 Casing 22, 32 Motor stator 23, 33 Gear cover 24, 25, 35 Side cover 26, 36 Driver 50 , 177 Pressure sensor 60 Controller 170 Cooling water system 173, 273 Normal line 174, 274 Increase line 175, 176, 275 Solenoid valve 270 Nitrogen gas system 370 External input signal

Claims (10)

At least one vacuum pump comprising a pair of rotors for transferring gas, a motor for rotating the pair of rotors, a timing gear for synchronizing the pair of rotors, and a driver for controlling the rotational speed of the motor;
A pressure sensor installed in a vacuum region in the evacuation system;
A controller that controls the rotational speed of the rotor via a driver of the at least one vacuum pump based on the pressure detected by the pressure sensor;
A vacuum exhaust system characterized by comprising: The at least one vacuum pump is composed of a front vacuum pump and a rear vacuum pump,
2. The vacuum exhaust system according to claim 1, wherein the control unit controls a rotational speed of a rotor of the upstream pump based on a pressure detected by the pressure sensor.   3. The vacuum exhaust system according to claim 1, wherein the controller reduces the rotational speed of the rotor when the pressure detected by the pressure sensor becomes greater than a predetermined value. 4. At least one vacuum pump comprising a pair of rotors for transferring gas, a motor for rotating the pair of rotors, and a timing gear for synchronizing the pair of rotors;
A pressure sensor installed in a vacuum region in the evacuation system;
A cooling water system for supplying cooling water to the at least one vacuum pump;
Based on the pressure detected by the pressure sensor, a controller that controls the flow rate of the cooling water flowing through the cooling water system,
A vacuum exhaust system characterized by comprising:   The vacuum exhaust system according to claim 4, wherein the control unit increases a flow rate of the cooling water flowing through the cooling water system when a pressure detected by the pressure sensor becomes larger than a predetermined value. At least one vacuum pump comprising a pair of rotors for transferring gas, a motor for rotating the pair of rotors, and a timing gear for synchronizing the pair of rotors;
A pressure sensor installed in a vacuum region in the evacuation system;
A gas system for supplying a shaft seal gas to the at least one vacuum pump;
A control unit for controlling the flow rate of the shaft seal gas flowing through the gas system based on the pressure detected by the pressure sensor;
A vacuum exhaust system characterized by comprising:   The vacuum exhaust system according to claim 6, wherein the control unit increases the flow rate of the shaft seal gas flowing through the gas system when the pressure detected by the pressure sensor becomes larger than a predetermined value. At least one vacuum pump comprising a pair of rotors for transferring gas, a motor for rotating the pair of rotors, a timing gear for synchronizing the pair of rotors, and a driver for controlling the rotational speed of the motor;
A controller that controls the rotational speed of the rotor via a driver of the at least one vacuum pump based on a signal indicating a state of a process in a vacuum chamber to which the at least one vacuum pump is connected;
A vacuum exhaust system characterized by comprising: At least one vacuum pump comprising a pair of rotors for transferring gas, a motor for rotating the pair of rotors, and a timing gear for synchronizing the pair of rotors;
A cooling water system for supplying cooling water to the at least one vacuum pump;
A control unit for controlling a flow rate of cooling water flowing through the cooling water system based on a signal indicating a process state in a vacuum chamber to which the at least one vacuum pump is connected;
A vacuum exhaust system characterized by comprising: At least one vacuum pump comprising a pair of rotors for transferring gas, a motor for rotating the pair of rotors, and a timing gear for synchronizing the pair of rotors;
A gas system for supplying a shaft seal gas to the at least one vacuum pump;
A controller that controls the flow rate of the shaft seal gas flowing through the gas system based on a signal indicating a process state in a vacuum chamber to which the at least one vacuum pump is connected;
A vacuum exhaust system characterized by comprising:

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