JP2003155981A - Operation control method for vacuum pump and operation controller thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress power loss while suppressing cost of a vacuum pump. SOLUTION: An inverter 10 controls rotation speed of an electric motor M using an alternate current power supply E as a power supply based on command control of a controller 11. The controller 11 detects a value of a current supplied to the electric motor M from the inverter 10. The controller 11 adjusts a voltage outputted from the inverter 10 so that the detected current value approaches the set current value to control rotation speed of the electric motor M.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention moves a gas transfer body in a pump chamber based on the rotation of a rotary shaft, and transfers gas by the operation of the gas transfer body to bring a suction action to a suction action target region. The present invention relates to an operation control method and an operation control device in a vacuum pump.

[0002]

2. Description of the Related Art In the vacuum pump disclosed in Japanese Patent Laid-Open No. 5-231381, the actual intake pressure at the intake port of the vacuum pump is detected, the set intake pressure is compared with the actual intake pressure, and the deviation of this comparison is detected. The rotation speed of the electric motor is controlled based on When the actual intake pressure is greater than the set intake pressure, the rotation speed of the vacuum pump is increased, and when the actual intake pressure is less than the set intake pressure, the rotation speed of the vacuum pump is reduced. Such operation control is
Brings power loss suppression effect.

[0003]

However, although a pressure detector for detecting the actual intake pressure at the intake port of the vacuum pump is required, the use of the pressure detector increases the cost of the vacuum pump. .

It is an object of the present invention to suppress the power loss while suppressing the cost of the vacuum pump.

[0005]

To this end, the present invention moves a gas transfer body in a pump chamber based on the rotation of a rotary shaft driven by an electric motor, and transfers and sucks gas by the operation of the gas transfer body. The present invention is directed to a vacuum pump that exerts a suction action on an action target area. In the invention of claim 1, a pump torque that is a load of the electric motor that is generated by the transfer of the gas and that reflects the pressure and flow rate of the gas is used. The detected pump torque is compared with the preset pump torque, and the rotation speed of the electric motor is controlled so that the detected pump torque approaches the preset pump torque. .

According to the invention of claim 2, in claim 1,
When the suction action target region is a load lock chamber, and an electric opening / closing means is interposed between the vacuum pump and the load lock chamber, and when the pressure of the suction action target region of the vacuum pump is reduced to a set pressure, When the detected pump torque reaches the pump torque corresponding to the set pressure by performing the rotation speed control toward the transient target pressure lower than the set pressure in the state where the electric opening / closing means is in the open state. In addition, the electric opening / closing means is closed.

According to the invention of claim 3, in claim 2,
When performing rotation speed control toward a transitional target pressure lower than the set pressure, the electric motor is driven at a preset first rotation speed, and the detected pump torque is the transitional target pressure. When the pressure becomes equal to or lower than the pump torque corresponding to the pressure, the electric motor is driven at a preset second rotation speed lower than the first rotation speed.

According to another aspect of the present invention, there is provided pump torque detecting means for detecting a pump torque which is a load of the electric motor and which is caused by the transfer of the gas and reflects the pressure and flow rate of the gas, and the pump torque detecting means. Rotation control means for comparing the pump torque detected by the above-mentioned pump torque with a preset pump torque, and controlling the rotation speed of the electric motor so that the detected pump torque approaches the preset pump torque. An operation control device having the above was constructed.

According to the invention of claim 5, in claim 4,
In the case where the suction action target region is a load lock chamber, the electric opening / closing means is interposed between the vacuum pump and the load lock chamber, and the pressure of the suction action target region of the vacuum pump is reduced to a set pressure, The rotation control means controls the rotation speed of the electric motor with the transitional target pressure lower than the set pressure as a target in a state where the electric opening / closing means is in an open state, and the electric opening / closing means,
When the pump torque detected by the pump torque detecting means reaches the pump torque corresponding to the set pressure, the pump torque is closed.

According to the invention of claim 6, in claim 5,
When the pump torque detected by the pump torque detection means exceeds the preset pump torque, the rotation control means drives the electric motor at a preset first rotation speed, and the detection is performed. When the pump torque thus set becomes equal to or lower than the preset pump torque, the electric motor is driven at a preset second rotation speed lower than the first rotation speed.

According to a seventh aspect of the present invention, in any one of the fourth to sixth aspects, the pump torque detecting means is a current detecting means for detecting a value of a current supplied to the electric motor.

In the inventions of claims 1 and 4, if the electric motor is driven so that the detected pump torque approaches the pump torque reflecting the desired pressure and flow rate of gas, power loss is suppressed. The detection of the pump torque reflecting the gas pressure / flow rate is cheaper than the case of directly detecting the gas pressure / flow rate.

In the inventions of claims 2 and 5, an electric opening / closing means is attached to the load lock chamber side, and control of the device on the load lock chamber side and control of the device on the vacuum pump side are independent of each other. To do. in this case,
The control that confirms the closed state of the electrical switching means at a transient target pressure lower than the set pressure is effective in correctly controlling the device on the vacuum pump side after the electrical switching means is closed. Is.

In the inventions of claims 3 and 6, the rotation speed of the electric motor is only two types, that is, the first rotation speed and the second rotation speed which are set in advance, and the operation control in the vacuum pump is performed. , A simple control of switching between the first rotation speed and the second rotation speed.

In the invention of claim 7, the value of the current supplied to the electric motor reflects the pump torque. The current detection is simple with regard to the detection of the pump torque that becomes the load of the electric motor.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment embodying the present invention will be described below with reference to FIGS.

Reference numeral C1 shown in FIG. 1 is a vacuum chamber for performing, for example, a semiconductor manufacturing operation. C2 is a load lock chamber for waiting a work (not shown) supplied to the vacuum chamber C1 and waiting for carrying out the work completed in the vacuum chamber C1. The inside of the vacuum chamber C1 is brought to a desired low pressure state by the vacuum pump Po1. A vacuum pump Po2 is connected to the load lock chamber C2 via a normally closed electromagnetic opening / closing valve 36. The inside of the load lock chamber C2 is brought to a desired low pressure state by the vacuum pump Po2. The inside of the load lock chamber C2 is a suction action target region for the vacuum pump Po2.

In the present embodiment, the vacuum pumps Po1 and P1
o2 is a roots pump type, and is shown in FIG. 2 and FIG.
(B) and (c) show the internal structures of the vacuum pumps Po1 and Po2.

As shown in FIG. 2, the rotor housing 12
A pair of rotating shafts 15 and 16 are rotatably supported by the front housing 13 and the rear housing 14 joined to each other. A rotor 17 formed integrally with the rotating shaft 15,
18, 19, 20, 21 and the rotors 22, 23, 24, 25, 26 integrally formed with the rotary shaft 16 mesh with each other in a one-to-one correspondence with the pump chamber 2 in the rotor housing 12.
It is housed at 7, 28, 29, 30, 31.

The rear housing 14 includes a gear housing 3
2 is assembled. The rotary shafts 15 and 16 penetrate the rear housing 14 and project into the gear housing 32. At the protruding end of each rotary shaft 15, 16, there is a gear 33,
34 are fastened together in a meshed state. An electric motor M is attached to the gear housing 32. The driving force of the electric motor M is transmitted to the rotating shaft 15, and the rotating shaft 15 is driven by the electric motor M as shown in FIGS.
It is rotated in the direction of arrow R1 in (c). The rotation of the rotary shaft 15 is transmitted to the rotary shaft 16 via the gears 33 and 34,
The rotating shaft 16 rotates in a direction opposite to the rotating shaft 15 as shown by an arrow R2 in FIGS. 3 (a), 3 (b) and 3 (c).

The gas introduced into the pump chamber 27 through the inlet 121 (shown in FIG. 3A) formed in the rotor housing 12 is compressed by the rotation of the rotors 17 and 22 and inside the chamber forming wall 35. Is transferred to the adjacent pump chamber 28 via the passage 351 (illustrated in FIG. 3B). Less than,
Similarly, for gases, the order in which the volume of the pump chamber becomes smaller,
That is, the pump chambers 28, 29, 30, 31 are transferred in this order. The gas transferred to the pump chamber 31 is
By the rotation of 6, the discharge is performed to the outside from the discharge port 122 formed in the rotor housing 12 [shown in FIG. 3 (c)]. The rotors 17 to 26 are gas transfer bodies that transfer gas.

As shown in FIGS. 1 and 2, the vacuum pump P
An inverter 10 is electrically connected to the o2 electric motor M. The inverter 10 controls the rotation speed of the electric motor M using the AC power source E as a power source based on the command control of the control device 11. The control device 11 detects the value of the current supplied from the inverter 10 to the electric motor M. The current value supplied from the inverter 10 to the electric motor M is
It reflects the pump torque that is the load on the electric motor M. That is, the control device 11 is detecting the pump torque which becomes the load of the electric motor M. Control device 11
Is a current detecting means as a pump torque detecting means for detecting a pump torque acting as a load of the electric motor M.

The curve H in FIG. 4 is a rotation speed curve representing the rotation speed control of the control device 11. The curve J is the control device 1
Vacuum pump Po2 that changes based on the rotation speed control of No. 1
Represents the pressure in the flow path between the solenoid valve 36 and the electromagnetic on-off valve 36. A curve F indicates a load lock chamber C2 that changes based on the opening / closing of the electric gate 37 and the rotation speed control of the control device 11.
Represents the internal pressure. The curve G represents the change in the current value supplied to the electric motor M of the vacuum pump Po2.

The set pressure P1 shown in FIG. 4 is set as a desired pressure in the load lock chamber C2, and the pressure P2 is lower than the set pressure P1.
This is a transient target pressure in the flow path between o2 and the solenoid opening / closing valve 36. The set current value W1 shown in FIG. 4 is supplied from the inverter 10 to the electric motor M when the electromagnetic opening / closing valve 36 is in the open state and the pressure in the load lock chamber C2 is the set pressure P1. This is the expected current value. The set current value W2 shown in FIG.
6 is in the closed state, and at the rotational speed N1, the value of the current expected to be supplied from the inverter 10 to the electric motor M when the pressure in the flow passage is the transient target pressure P2. is there. The set current value W2 is a value smaller than the set current value W1.

In the load lock chamber C2, the work supplied to the vacuum chamber C1 is loaded into the load lock chamber C2.
In order to carry in the finished work from the load lock chamber C2 as well as to carry it into the inside 2, the electric gate 37 is opened to open to the atmosphere. The work in the load lock chamber C2 is supplied to the vacuum chamber C1 by opening the electric gate 38. An electromagnetic opening / closing valve 36 as electric opening / closing means,
The electric gates 37 and 38 are subjected to opening / closing control of an opening / closing control device 39 different from the control device 11. The pressure in the load lock chamber C2 is detected by the pressure detector 40.
The opening / closing control device 39 controls opening / closing of the electromagnetic opening / closing valve 36 based on the pressure detection information obtained from the pressure detector 40.

When the electric gate 37 is opened (at time t1 shown in FIG. 4), the electromagnetic on-off valve 36 is in the closed state, and the communication between the load lock chamber C2 and the vacuum pump Po2 is cut off. When the load lock chamber C2 is open to the atmosphere, the vacuum pump Po2 is driven at a preset standby rotation speed N2 (a preset second rotation speed). The standby rotation speed N2 is the same as the load lock chamber C2 when the electromagnetic opening / closing valve 36 is in the open state.
It is the rotation speed at which the internal pressure is expected to be maintained at the set pressure P1. That is, the standby rotation speed N2 is set so that the pressure P1 is estimated when the detected current value is W2 and the rotation speed is N2. After the work is supplied to the load lock chamber C2, the opening / closing control device 39 commands the closing of the electric gate 37 and the opening of the electromagnetic opening / closing valve 36 (see FIG. 4).
Command at time t2). This makes the electric gate 3
7 is closed, and the inside of the load lock chamber C2 is shut off from the atmosphere. Further, the vacuum pump Po2 communicates with the load lock chamber C2 in the atmospheric pressure state.

When the electromagnetic opening / closing valve 36 is opened, the pump torque in the vacuum pump Po2 increases and the value of the current supplied to the electric motor M of the vacuum pump Po2 increases.
The control device 11 that detects the value of the current supplied from the inverter 10 to the electric motor M compares the detected current value with the set current value W1. When the supplied current value reaches the set current value W1, the control device 11 rotates the electric motor M from the standby rotation speed (second rotation speed) N2 to the maximum rotation speed (preset first rotation speed) N1. Switch speed. This rotation speed switching reduces the pressure in the load lock chamber C2 and the pressure in the flow path between the electromagnetic opening / closing valve 36 and the vacuum pump Po2.

After switching the rotation speed of the electric motor M from the standby rotation speed N2 to the maximum rotation speed N1, the inverter 10
The control device 11 that detects the value of the current supplied from the electric motor M to the electric motor M compares the detected current value with the set current value W1. The larger the pressure in the load lock chamber C2, that is, the larger the flow rate of the exhaust gas transferred by the vacuum pump Po2, the larger the pump torque that is the load of the electric motor M, and the value of the current supplied to the electric motor M becomes. large. Therefore, the detected current value decreases as the pressure inside the load lock chamber C2 is reduced.

When the pressure detector 40 detects the pressure P1 (pressure in the load lock chamber C2) (time t3 in FIG. 4).
The opening / closing control device 39 commands the closing of the electromagnetic opening / closing valve 36, and the electromagnetic opening / closing valve 36 is closed. As a result, the communication between the load lock chamber C2 and the vacuum pump Po2 is cut off. At this time, the pressure in the load lock chamber C2 and the pressure in the flow path between the electromagnetic opening / closing valve 36 and the vacuum pump Po2 are set pressure P1.

After the electromagnetic opening / closing valve 36 is closed, the pressure in the flow path between the electromagnetic opening / closing valve 36 and the vacuum pump Po2 is the vacuum pump Po2 driven by the electric motor M at the first rotation speed N1. The pressure is further reduced by the suction action of. That is,
The value of the current supplied to the vacuum pump Po2 decreases. When the detected current value reaches the set current value W2 (at time t4 in FIG. 4), the control device 11 controls the first rotation speed N.
The rotation speed of the electric motor M is switched from 1 to the second rotation speed (standby rotation speed) N2. At this time, the solenoid on-off valve 3
The pressure in the flow path between 6 and the vacuum pump Po2 is expected to be the set pressure P2 (<P1). When the rotation speed of the electric motor M is switched from the first rotation speed N1 to the second rotation speed N2, the pressure in the flow path between the electromagnetic opening / closing valve 36 and the vacuum pump Po2 is set from the transient target pressure P2. Expected to be pressure P1.

The inverter 10 and the control device 11 compare the detected current value (that is, the detected pump torque) with the preset current value (that is, the preset pump torque) and detect the detected current value. A rotation control unit that controls the rotation speed of the electric motor M is configured so that the generated current value approaches a preset current value.

The following effects are obtained in the first embodiment. (1-1) The control device 11 drives the motor so that the detected current value approaches the set current value, in other words, the detected pump torque approaches the set pump torque that reflects the desired pressure. The rotation speed of the motor M is controlled. In the first embodiment, the rotational speed of the electric motor M is driven at the first rotational speed N1 to perform pressure control toward the transient target pressure P2. Then, when the detected pump torque reaches the pump torque corresponding to the transient target pressure P2, the control for switching the rotation speed of the electric motor M to the second rotation speed N2 lower than the first rotation speed N1 is performed. Done. That is, the control device 11 controls the rotation speed of the electric motor M based on the detected current value.
Such operation control of the vacuum pump Po2 suppresses power loss.

(1-2) The pressure detector is expensive. Moreover, a structure is required to install a pressure detector so that the pressure in the exhaust gas existing region (for example, the exhaust gas flow path from the inlet 121 to the load lock chamber C2) can be detected. Adopting such a structure also brings about an increase in cost. It is also possible to detect the flow rate of the exhaust gas instead of detecting the pressure of the exhaust gas and control the rotation speed of the electric motor M based on the detected flow rate. However, the current detection has the same cost disadvantage as the pressure detection.

The pump torque reflecting the pressure / flow rate of the exhaust gas can be detected by detecting the value of the current supplied from the inverter 10 to the electric motor M. The detection of the pump torque that reflects the pressure / flow rate of the exhaust gas is advantageous in terms of cost as compared with the case where the pressure of the exhaust gas or the flow rate of the exhaust gas is directly detected.

(1-3) There are only two rotation speeds of the electric motor M, that is, a first rotation speed N1 and a second rotation speed N2 which are set in advance. Therefore, the operation control in the vacuum pump Po2 is performed by the first rotation speed N1 and the second rotation speed N.
The control is switched to 2 and the operation control of the vacuum pump Po2 is facilitated.

(1-4) From the inverter 10 to the electric motor M
The value of the current supplied to the motor accurately reflects the pump torque that is the load of the electric motor M. The current detecting means is an appropriate means for increasing the accuracy of detecting the pump torque, and is simple in detecting the pump torque.

(1-5) As the first rotation speed N1 is higher, the time required to reach the set pressure P1 is shorter. However, since the operation exceeding the maximum capacity of the vacuum pump Po2 cannot be performed, operating with the maximum capacity of the vacuum pump Po2 (that is, driving at the maximum continuous speed N1) minimizes the time required to reach the set pressure P1. . Such shortening of the time leads to shortening of the working time of the working process of semiconductor manufacturing described above.

(1-6) When a vacuum pump capable of achieving the set pressure P1 with the maximum capacity is used, the maximum rotation speed of the vacuum pump achieves the transient target pressure P2 lower than the set pressure P1 with the maximum capacity. Possible vacuum pump Po2
Is smaller than the maximum rotation speed N1. Set pressure P from the beginning
When controlling the rotational speed of the electric motor with the target value of 1, a vacuum pump that can achieve the set pressure P1 with the maximum capacity can be used. However, when performing the rotational speed control of the electric motor targeting the transient target pressure P2 lower than the set pressure P1, the vacuum pump Po2 capable of achieving the transient target pressure P2 lower than the set pressure P1 by the maximum capacity. Will need to be adopted. That is, in the rotation speed control of the electric motor targeting the transient target pressure P2, the time required to reach the set pressure P1 is shortened by using the vacuum pump Po2 that can achieve the transient target pressure P2 with the maximum capacity. Bring Moreover, since the rotation speed of the electric motor M is switched from the maximum rotation speed N1 to the standby rotation speed N2 after the pump torque in the vacuum pump Po2 reaches the pump torque corresponding to the transient target pressure P2, power loss is suppressed. To be done.

(1-7) When the electromagnetic on-off valve 36 is a device attached to the load lock chamber C2 side, the control device 11
Controls the device on the vacuum pump Po2 side, and the opening / closing control device 39 controls the device on the load lock chamber C2 side. That is, the control device 11 and the opening / closing control device 39 perform control independent of each other, and the control device 11 cannot use the pressure information obtained from the pressure detector 40. The control device 11 uses the pressure information estimated based on the current value detection, and the use of such pressure information suppresses the cost of the vacuum pump Po2.

When there is a gas flow in the flow path between the load lock chamber C2 and the vacuum pump Po2 when the electromagnetic opening / closing valve 36 is in the open state, the accuracy of pressure estimation by current value detection is when there is no gas flow. Somewhat lower than. Therefore, determining that the electromagnetic on-off valve 36 has been switched from open to closed by the pressure P1 estimated based on the current value detection may cause erroneous detection.

If the transient target pressure P2 is properly set, the transient target pressure P2 is estimated by detecting the current value when there is no gas flow. Therefore, when it is determined by the pressure P2 (<P1) that is estimated based on the current value detection that the electromagnetic opening / closing valve 36 has been switched from open to closed, the above-mentioned erroneous detection is avoided. That is, at the transient target pressure P2 lower than the set pressure P1, the electromagnetic opening / closing valve 36
The control for confirming the closed state is effective in correctly controlling the device on the vacuum pump Po2 side after the electromagnetic opening / closing valve 36 is closed.

Next, a second embodiment shown in FIGS. 5 and 6 will be described. The same symbols are used for the same components as those in the first embodiment. The vacuum pump Po1 having the vacuum chamber C1 as the suction action target region is controlled by the rotation control means including the inverter 10A and the control device 11A. The desired pressure in the vacuum chamber C1 is the load lock chamber C
It is set to a pressure P3 lower than the set pressure P1 in 2. The maximum rotation speed N1 of the electric motor M can reduce the pressure in the vacuum chamber C1 to a pressure lower than the set pressure P3. A curve H1 in FIG. 6 represents a change in the rotation speed of the electric motor M, and a curve G1 represents the electric motor M.
Represents the change in the current value supplied to the. The curve F1 represents the pressure change in the vacuum chamber C1, and the curve J1 represents the pressure change at the inlet of the vacuum pump Po1. Current value W3
Is a set current value expected to be supplied to the vacuum pump Po1 when the pressure in the vacuum chamber C1 is the set pressure P3.

When the electric gate 38 is opened (at time t5 in FIG. 6), the rotation speed of the electric motor M is maintained at the standby rotation speed N3, and the inside of the vacuum chamber C1 has a low set pressure P3. Is expected to be. When the electric gate 38 is opened, the control device 11A feedback-controls the rotation speed of the electric motor M based on the feedback of the detected supply current value. A curve portion H11 in the curve H1 representing the rotation speed change in FIG. 6 represents the rotation speed change due to the feedback control after the electric gate 38 is opened. When the electric gate 38 is opened, the pressure in the load lock chamber C2 is higher than the pressure in the vacuum chamber C1, so that the pressure in the vacuum chamber C1 is set to the set pressure P.
Rise from 3. Then, the current value supplied to the electric motor M increases in accordance with the pressure increase in the vacuum chamber C1. As the value of the current supplied to the electric motor M increases, the rotation speed of the electric motor M increases from the standby rotation speed N3. At time t6 in FIG. 6, the electric gate 38 is closed.

The rotation speed of the electric motor M is the maximum rotation speed N.
When it reaches 1 (at time t7 in FIG. 6), the control device 11A stops the feedback control and performs control to maintain the rotation speed of the electric motor M at the maximum rotation speed N1 (curve H1 in FIG. 6). Curve portion H12). The pressure in the vacuum chamber C1 decreases as the rotation speed of the electric motor M increases. The current value supplied to the electric motor M decreases as the pressure in the vacuum chamber C1 decreases.

When the detected supply current value reaches the set current value W3 (at time t8 in FIG. 6), the controller 11A
Restarts the feedback control based on the detected supply current value so that the detected supply current value approaches the set current value W3 (curve portion H1 in curve H1 in FIG. 6).
3). When the rotation speed of the electric motor M reaches the standby rotation speed N3 (at time t9 in FIG. 6), the control device 1
1A performs control to stop the feedback control and maintain the rotation speed of the electric motor M at the standby rotation speed N3 (curve portion H14 in curve H1 in FIG. 6).

In the second embodiment, the same effects as the items (1-1), (1-2) and (1-4) in the first embodiment can be obtained. In the example of FIG. 6, the case where the rotation speed reaches the maximum rotation speed N1 has been described, but since the increase in the rotation speed changes depending on the change in pressure, the rotation speed does not always reach the maximum rotation speed N1.

The following embodiments are possible in the present invention. (1) A strain detector detects the strain of the rotary shaft 15 or the rotary shaft 16 that reflects the pump torque, compares the detected strain with a preset strain, and the detected strain is preset. Control the rotation speed of the electric motor so that it converges to the distortion. In this case, a strain detecting element may be attached to the peripheral surface of the rotary shaft 15 or the rotary shaft 16 to detect the strain on the peripheral surface of the rotary shaft 15 or the rotary shaft 16.

(2) In the first embodiment, the rotational speed control of the electric motor M targeting the set pressure P1 is performed from the beginning. (3) In the first embodiment, in the rotational speed control toward the transient target pressure P2 lower than the set pressure P1 without the electromagnetic opening / closing valve 36, the detected supply current value is set to the set current value W2. Feedback control to make it converge,
After the detected supply current value reaches the set current value W2, in the rotation speed control with the set pressure P1 as the target pressure, feedback control is performed to converge the detected supply current value to the set current value W1. thing.

(4) In the second embodiment, the standby rotation speed N3 may not be set. In this case, in order to keep the pressure in the vacuum chamber C1 at the set pressure P3, feedback control based on the detected current value may always be performed so that the detected supply current value approaches the set current value W3.

[0050]

As described above in detail, in the present invention, the detected pump torque is compared with the preset pump torque, and the electric motor is adjusted so that the detected pump torque approaches the preset pump torque. Since the rotation speed of the vacuum pump is controlled, there is an excellent effect that the power loss can be suppressed while suppressing the cost of the vacuum pump.

[Brief description of drawings]

FIG. 1 is a simplified diagram showing a schematic configuration of a first embodiment.

FIG. 2 is a plan sectional view of a vacuum pump.

3A is a cross-sectional view taken along the line AA of FIG. Figure 2 (b) is
BB line sectional drawing. (C) is CC sectional view taken on the line of FIG.

FIG. 4 is a graph for explaining rotation speed control.

FIG. 5 is a simplified diagram showing a schematic configuration of a second embodiment.

FIG. 6 is a graph for explaining rotation speed control.

[Explanation of symbols]

10, 10A ... Inverter constituting rotation control means. 1
1, 11A ... A control device which is a pump torque detection means and also constitutes a rotation control means. 15, 16 ... Rotating shaft. 1
7-26 ... A rotor which is a gas transfer body. 27-31 ... Pump room. 36 ... An electromagnetic opening / closing valve as an electric opening / closing means. M ...
Electric motor. Po1, Po2 ... Roots pumps that are vacuum pumps. C1 ... A vacuum chamber which is a suction target region.
C2 ... A load lock chamber which is a suction target region.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Osamu Uchiyama             2-1, Toyota-cho, Kariya City, Aichi Stock Association             Inside Toyota Toyota Industries F-term (reference) 3H045 AA05 AA09 AA16 AA26 AA38                       BA32 CA21 CA29 DA07 EA36

Claims (7)

[Claims] 1. A gas transfer body in a pump chamber is moved based on the rotation of a rotary shaft driven by an electric motor, and gas is transferred by the operation of the gas transfer body to exert a suction action on a suction action target region. In a vacuum pump, a pump torque that is generated by the transfer of the gas and that is a load of the electric motor that reflects the pressure / flow rate of the gas is detected, and the detected pump torque is compared with a preset pump torque. Then, the operation control method in the vacuum pump, wherein the rotation speed of the electric motor is controlled so that the detected pump torque approaches a preset pump torque. 2. The suction action target region is a load lock chamber, and an electric opening / closing means is interposed between the vacuum pump and the load lock chamber, and a pressure of the suction action target region of the vacuum pump is provided. When decreasing to a set pressure, the rotational speed control is performed toward a transient target pressure lower than the set pressure in a state where the electric switching means is in an open state, and the detected pump torque is set to the set pressure. The operation control method for a vacuum pump according to claim 1, wherein the electric switching means is closed when a corresponding pump torque is reached. 3. When performing rotational speed control toward a transient target pressure lower than the set pressure, the electric motor is driven at a preset first rotational speed, and the detected pump torque is set. The electric motor is driven at a preset second rotation speed lower than the first rotation speed when is less than or equal to the pump torque corresponding to the transient target pressure. Control method for the vacuum pump of the above. 4. A gas transfer body in a pump chamber is moved based on the rotation of a rotary shaft driven by an electric motor, and gas is transferred by the operation of the gas transfer body to exert a suction action on a suction action target region. In a vacuum pump, pump torque detection means for detecting a pump torque that is a load of the electric motor and that is generated by the transfer of the gas and that reflects the pressure / flow rate of the gas; and a pump torque detected by the pump torque detection means. And a preset pump torque, and a rotation control means for controlling the rotation speed of the electric motor so that the detected pump torque approaches the preset pump torque. Operation control device. 5. The suction action target area is a load lock chamber, and an electric opening / closing means is interposed between the vacuum pump and the load lock chamber to control the pressure of the suction action target area of the vacuum pump. When reducing to a set pressure, the rotation control means controls the rotation speed of the electric motor with the transient target pressure lower than the set pressure as a target in a state where the electric switching means is in an open state,
The operation control device for a vacuum pump according to claim 4, wherein the electric switching means is closed when the pump torque detected by the pump torque detecting means reaches a pump torque corresponding to the set pressure. 6. When the pump torque detected by the pump torque detecting means exceeds the preset pump torque, the rotation control means causes the electric motor to operate at a preset first rotation speed. When it is driven and the detected pump torque becomes equal to or lower than the preset pump torque, the electric motor is driven at a preset second rotation speed lower than the first rotation speed. The operation control device in the vacuum pump according to claim 5. 7. The operation control in a vacuum pump according to claim 4, wherein the pump torque detecting means is a current detecting means for detecting a value of a current supplied to the electric motor. apparatus.