JP2006009759A - Turbo-molecular pump device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turbo-molecular pump device capable of lengthening a service life of a touch-down bearing by positively stopping a rotor in a short time when the touch-down bearing is operated, and shortening the operating time of the touch-down bearing. <P>SOLUTION: When an emergency stop signal is inputted from an emergency stop signal input terminal 22, or a signal is outputted from a touch-down sensor 2 by the operation of the touch-down bearing 17, the emergency stop signal or the signal from the touch-down sensor 2 is outputted to a DSP (digital signal processor) control device 3 and outputted to a stop signal generating circuit 4 through an OR circuit 18. Control performed by the DSP control device 3 is thereby stopped, and the stop signal generating circuit 4 outputs an emergency stop slowing-down characteristic pattern signal for stopping the rotor 12 in a shorter time than the time required to stop the rotor 12 by the DSP control device 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a turbo molecular pump device.

  Conventionally, as a turbo molecular pump device, there is one described in Japanese Patent Application Laid-Open No. 09-068222 (Patent Document 1).

  The turbo molecular pump device includes a rotor, a motor that drives the rotor, a magnetic bearing that supports the rotor in a magnetic non-contact manner, an inverter control circuit that changes a rotational speed of the motor, and an operation of the magnetic bearing. A magnetic bearing control circuit for controlling the rotor, a touch-down bearing that mechanically supports the rotor when the magnetic bearing cannot support the rotor, and a heating braking circuit.

  When the supply of electric power from the power supply side is stopped due to a power supply abnormality or the like, the motor induces a voltage as a generator while the rotor continues to rotate due to inertial force. The inverter control circuit and the magnetic bearing control circuit are adapted to be supplied with regenerative power from the motor instead of the power supply when the power supply voltage decreases. While the regenerative power supplied from the motor can drive the inverter control circuit and the magnetic bearing control circuit, the regenerative power performs motor control and magnetic levitation control.

  The inverter control circuit diverts the regenerative power from the motor to the motor and the heat braking circuit. The inverter control circuit performs regenerative braking by returning electric power to the motor, and the inverter control circuit performs heat generating braking by flowing regenerative power through the resistance of the heat generating braking circuit. .

  The inverter control and the magnetic levitation control are stopped when the rotational speed of the rotor is reduced and the voltage from the motor acting as a generator is lower than the voltage required for driving the inverter control circuit and the magnetic bearing control circuit. It has become. When the inverter control and the magnetic levitation control are stopped, the motor is connected in series with the heat generation braking circuit to perform heat generation control, and the rotor is supported by a touch-down bearing and is also braked by this friction.

However, in the conventional turbo molecular pump, when the inverter control and the magnetic levitation control are stopped and the touchdown bearing is operated, the motor is stopped. Therefore, the rotor is stopped after the inverter control and the magnetic levitation control are stopped. There is a problem that it cannot be done in a short time, the touch down bearing is operated for a long time, the touch down bearing is likely to be damaged, and the life of the touch down bearing is shortened.
Japanese Patent Application Laid-Open No. 09-068222

  Accordingly, an object of the present invention is to provide a turbo molecular pump capable of extending the life of a touchdown bearing by reliably stopping the rotor in a short time when the touchdown bearing is operated and shortening the time during which the touchdown bearing is operating. To provide an apparatus.

In order to solve the above problems, the turbomolecular pump device of the present invention is
A turbo-molecular pump body having a magnetic bearing that magnetically supports the rotor in a non-contact manner, a touchdown bearing that mechanically supports the rotor, and a motor that drives the rotor;
A touchdown sensor for detecting the operation of the touchdown bearing;
A rotation speed control device that outputs a signal representing acceleration and deceleration of the turbo molecular pump and outputs a signal of a normal deceleration characteristic pattern at the time of a normal stop,
A stop signal that receives a signal representing the operation of the touchdown bearing from the touchdown sensor and outputs a signal of an emergency stop deceleration characteristic pattern that decelerates faster than the normal deceleration characteristic pattern signal of the rotational speed control device Generating circuit;
A motor driver control circuit that receives signals from the rotation speed control device and the stop signal generation circuit;
And a motor driver that drives the motor in response to a signal from the motor driver control circuit.

  According to the present invention, when the touchdown sensor detects the operation of the touchdown bearing, the stop signal generation circuit causes the emergency stop to decelerate faster than the signal of the normal deceleration characteristic pattern of the rotation speed control device. The deceleration characteristic pattern signal is output to the motor driver control circuit. Therefore, the motor can be controlled based on the emergency stop deceleration characteristic pattern signal to stop the rotation of the rotor, and the rotor can be reliably stopped in a short time when the touchdown bearing is operated. When the touch-down bearing is activated, the rotor can be surely stopped faster than during normal stop. Therefore, there is less risk of damage to the touchdown bearing, and the life of the touchdown bearing is significantly longer than before.

  In one embodiment, the turbo molecular pump device includes an input terminal for receiving the emergency stop signal from the outside, and the stop signal generating circuit is connected to the external from the input terminal or through the input terminal. When the emergency stop signal is received, the emergency stop deceleration characteristic pattern signal is output.

  According to the above embodiment, when it is desired to stop the turbo molecular pump urgently, the turbo molecular pump can be stopped immediately in a short time compared with the conventional apparatus by inputting an emergency stop signal from the outside.

  According to the turbo molecular pump device of the present invention, when the touch-down bearing is operated, the stop signal generation circuit outputs an emergency stop deceleration characteristic pattern signal to the motor driver control circuit that decelerates faster than the rotational speed control device. Therefore, when the touchdown bearing is activated, the rotor can be reliably stopped in a short time. Therefore, the risk of damage to the touchdown bearing is reduced, and the life of the touchdown bearing is significantly longer than before.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram schematically showing a turbo molecular pump device according to an embodiment of the present invention.

  The turbo molecular pump device includes a turbo molecular pump 1, a touchdown sensor 2, a DSP (digital signal processor) control device 3 as a rotation speed control device, a stop signal generation circuit 4, and a motor driver control circuit 5. And a motor driver 6, a rotation speed detection sensor 7, and an emergency stop signal input terminal 22 to which an emergency stop signal is input. The output side of the touchdown sensor 2 and the input side of the OR circuit 18, and the emergency stop signal input terminal 22 and the input side of the OR circuit 18 are connected. The output side of the OR circuit 18 is a stop signal generating circuit. 4 input terminals 20. The stop signal generation circuit 4, the motor driver control circuit 5, and the motor driver 6 constitute an inverter unit. The motor driver 6 serves as an inverter body.

  In FIG. 1, the touchdown sensor 2 and the rotation speed detection sensor 7 are illustrated at a position away from the turbo molecular pump 1, but actually, the touchdown sensor 2 and the rotation speed detection sensor 7 are illustrated. Is installed in the turbo molecular pump 1.

  The turbo molecular pump 1 mechanically supports the motor 11, the rotor 12 driven by the motor 11, two sets of upper and lower magnetic bearings 15 and 16 that support the rotor 12 in a non-contact manner in the radial direction, and the rotor 12. And a touch-down bearing 17.

  The magnetic bearings 15 and 16 are configured to support the rotor 12 magnetically in a non-contact manner at a predetermined target position in the radial direction by being supplied with electric power from a power source. Further, the touchdown bearing 17 receives an external impact due to an earthquake or the like when the rotor 12 becomes uncontrollable, or when a load exceeding the load capacity of the magnetic bearings 15 and 16 is applied to the magnetic bearings 15 and 16. If the magnetic bearings 15 and 16 cannot support the rotor 12, such as when air enters the turbo molecular pump 1 or when the gas discharge flow rate is large, the rotor 12 is mechanically supported. It is supposed to be. In the above case, the touch-down bearing 17 prevents contact between the magnetic bearings 15 and 16 and the rotor 12 and contact between the rotor 12 and the housing of the turbo molecular pump 1, thereby damaging the turbo molecular pump 1. It is designed to prevent this.

  The touch-down sensor 2 is a vibration sensor, and when the touch-down bearing 17 is operated, the operation of the touch-down bearing 17 is detected by detecting the vibration of the touch-down bearing 17 and outputs a signal. ing. The rotational speed sensor 7 detects the rotational speed of the rotor 12 to detect the rotational speed of the motor 11 and outputs a signal.

  When the DSP control device 3 receives a signal from the rotation speed sensor 7, the DSP control device 3 outputs a voltage signal as a signal representing an acceleration or deceleration signal according to a signal of an operation table input in advance to the memory of the DSP control circuit 3. It outputs to the control circuit 5. Specifically, when the DSP control device 3 outputs an acceleration signal in accordance with the signal of the operation table, a voltage signal larger than 2.5 V as an example of the reference voltage (the higher the voltage, the higher the acceleration rate becomes. When a large command is output to the motor driver control circuit 5 and a deceleration signal is output in accordance with the signal of the operation table, a voltage signal smaller than 2.5V (the smaller the voltage, the lower the rate of deceleration) Is output to the motor driver control circuit 5.

  The stop signal generation circuit 4 inputs at least one of the touchdown signal output from the touchdown sensor 2 and the emergency stop signal from the emergency stop signal input terminal 22 to the OR18 circuit. When a signal is received via the input terminal 20, a uniform voltage larger than 2.5V is output to the motor driver control circuit 5. Then, the rotor 12 is surely stopped in a time shorter than the time until the rotor 12 is stopped by the DSP control device 3. The input terminal 20 is a terminal that receives an emergency stop signal from the outside (manual input by the user).

  The motor driver control circuit 5 receives the signal from the DSP control device 3 and the signal from the stop signal generation circuit 4 (the signal is not received simultaneously from the DSP control device 3 and the stop signal generation circuit 4), and the motor driver 6 is generated, and this signal is output to the motor driver 6. The motor driver 6 controls the rotational speed of the motor 11 by outputting signals to the input / output terminals U, V and W of the motor 11.

  In the above configuration, when the turbo molecular pump 1 is operated, the DSP control circuit 3 accelerates according to the signal from the rotational speed sensor 7 and the signal based on the acceleration / deceleration table input in advance in the memory of the DSP control circuit 3. A deceleration signal (the acceleration and deceleration signals are not output simultaneously) is output to the motor driver control circuit 5. Specifically, the DSP control circuit 3 calculates the actual rotational speed of the motor 11 based on the signal from the rotational speed sensor 7, and controls the slip of the motor 11, that is, the slip of the rotational speed per unit time (to be output). By adjusting the rotational speed and the actual rotational speed of the rotor, a signal based on the acceleration / deceleration table is output (for example, when acceleration / deceleration is performed at 20 Hz in 10 seconds, the slip is 2Hz / 1 second). The motor driver control circuit 5 drives and controls the motor driver 6 based on the acceleration and deceleration signals, thereby controlling the rotational speed of the rotor 12 to the rotational speed according to the acceleration / deceleration table. .

  Further, when the turbo molecular pump 1 is normally stopped, the DSP control circuit 3 displays the signal from the rotation speed sensor 7 and the deceleration characteristic pattern (table) at the time of normal stop inputted in advance in the memory of the DSP control circuit 3. According to the signal, an acceleration or deceleration signal is output to the motor driver control circuit 5. The motor driver control circuit 5 controls the motor driver 6 based on the deceleration signal according to the deceleration characteristic pattern, thereby reducing the rotational speed of the rotor 12 to zero.

  On the other hand, when an emergency stop signal is input from the emergency stop signal input terminal 22 or when the touchdown bearing 17 is activated and a signal is output from the touchdown sensor 2, the emergency stop signal or the touchdown sensor 2 outputs the signal. Is output to the DSP control device 3 and is also output to the stop signal generation circuit 4 via the OR circuit 18. Then, the control by the DSP control device 3 is stopped, and the stop signal generation circuit 4 outputs a uniform and large voltage to the motor driver control circuit 5. Then, the stop signal generating circuit 4 stops the rotor 12 in a time shorter than the time until the rotor 12 is stopped by the DSP control device 3.

  FIG. 2 shows an example of a normal deceleration characteristic pattern signal 31 output by the DSP control device 3 during a normal stop, and an emergency stop deceleration characteristic pattern signal output by the stop signal generation circuit 4 during an emergency stop. FIG.

  In FIG. 2, the time axis in the signal 31 of the normal deceleration characteristic pattern is based on the signal 32 of the emergency stop deceleration characteristic with reference to the time when the rotation speed becomes R3 (0 seconds). Is based on the time when the touch-down bearing is activated (assuming that the rotation speed at this time is R3).

  As shown in FIG. 2, in the signal 31 of the normal deceleration characteristic pattern, the slip per unit time fluctuates so as to increase with the passage of time.

  Specifically, the slip per unit time until time T1 is set to (R3-R2) / T1, and the slip per unit time from time T1 to T3 is greater than (R3-R2) / T1 (R2 -R1) / (T3-T1), and the slip per unit time from time T3 to time T4 when the motor stops is larger than (R2-R1) / (T3-T1) R1 / (T4-T3) ) Is set.

  Thus, in the normal deceleration characteristic pattern signal 31, the slip per unit time is changed so as to increase with the passage of time, and when the inertia of the rotor 12 is large, the slip is reduced, while the inertia of the rotor 12 is increased. By increasing the slip as the speed decreases, a smooth stop operation is realized and the rotor 12 is prevented from being damaged by the influence of sudden braking.

  On the other hand, in the signal 32 of the emergency stop deceleration characteristic pattern, the slip per unit time is set to a constant value R3 / T2 until the rotor 12 stops after the touch-down bearing is activated. In the signal 32 of the emergency stop deceleration characteristic pattern, the rotor 12 is stopped faster than usual as shown in FIG. 2 so that T2 <T4. The operating time of the touch-down bearing used in such a state is shortened to extend the life of the touch-down bearing.

  According to the turbo molecular pump device of the above-described embodiment, the stop signal generation circuit 4 causes the emergency stop deceleration characteristic pattern to decelerate faster than the DSP control device 3 when the touchdown sensor 2 detects the operation of the touchdown bearing 17. The signal 32 is output to the motor driver control circuit 5. Therefore, the rotor 12 can be stopped based on the signal 32 of the emergency stop deceleration characteristic pattern, and the rotor can be reliably stopped in a short time when the touchdown bearing 17 is operated. Therefore, the possibility of damaging the touch-down bearing 17 can be reduced, and the life of the touch-down bearing can be made much longer than before.

  Further, according to the turbo molecular pump device of the above embodiment, when the turbo molecular pump 1 is urgently stopped, an emergency stop signal is input from the outside, so that the turbo molecular pump device can be quickly and quickly compared with the conventional device. The molecular pump 1 can be stopped.

  In the turbo molecular pump device of the above embodiment, the reference voltage for accelerating or decelerating the motor 11 is 2.5 V, but the reference voltage for accelerating or decelerating the motor 11 is 2.5 V. It may be set to a voltage other than.

  In the turbo molecular pump device of the above embodiment, the touchdown sensor 2 is a vibration sensor. However, in the turbo molecular pump device of the present invention, the touchdown sensor is not a vibration sensor such as a position detection sensor or a temperature sensor. This sensor may be used.

  Further, in the turbo molecular pump device of the above embodiment, the normal stop pattern signal 31 is a polygonal line pattern signal whose slip per unit time increases as the rotation speed decreases. The signal of the stop pattern may be a signal of a pattern other than the polygonal line pattern, such as a signal of a curve pattern in which slip per unit time increases as the rotational speed decreases.

  In the turbo molecular pump device of the above embodiment, the emergency stop pattern signal 32 is a linear pattern signal. However, the emergency stop pattern signal causes the rotor 12 to move faster than the normal stop pattern signal. Of course, as long as it is a signal to be stopped, a signal having a pattern of any shape such as a signal of a polygonal line pattern or a signal of a curve pattern may be used. In addition, the signal of the emergency stop pattern, the signal of the pattern that stops the rotor faster than the signal of the normal stop pattern, and a finer stop pattern that considers damage to the rotor and the touchdown bearing are realized. By making the pattern signal that the slip per unit time increases as the rotor speed decreases, the emergency stop of the rotor can be made more reliably and in a shorter time than in the case of normal stop, and damage to the rotor and touchdown bearings Can also be prevented.

It is a figure showing typically the turbo-molecular pump device of one embodiment of this invention. It is a figure which shows an example of the signal of the normal deceleration characteristic pattern which a DSP control apparatus outputs at the time of a normal stop, and the signal of the pattern of the emergency stop deceleration characteristic which a stop signal generation circuit outputs at the time of an emergency stop.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Turbo molecular pump 2 Touchdown sensor 3 DSP control apparatus 4 Stop signal generation circuit 5 Motor driver control circuit 6 Motor driver 7 Rotation speed detection sensor 11 Motor 12 Rotor 15, 16 Magnetic bearing 17 Touchdown bearing 20 Input terminal 22 Emergency stop signal Input terminal 31 Normal deceleration characteristics pattern signal 32 Emergency stop deceleration characteristics pattern signal

Claims (2)

A turbo-molecular pump body having a magnetic bearing that magnetically supports the rotor in a non-contact manner, a touchdown bearing that mechanically supports the rotor, and a motor that drives the rotor;
A touchdown sensor for detecting the operation of the touchdown bearing;
A rotation speed control device that outputs a signal representing acceleration and deceleration of the turbo molecular pump and outputs a signal of a normal deceleration characteristic pattern at the time of a normal stop,
A stop signal that receives a signal representing the operation of the touchdown bearing from the touchdown sensor and outputs a signal of an emergency stop deceleration characteristic pattern that decelerates faster than the normal deceleration characteristic pattern signal of the rotational speed control device Generating circuit;
A motor driver control circuit that receives signals from the rotation speed control device and the stop signal generation circuit;
A turbo molecular pump device comprising: a motor driver that receives a signal from the motor driver control circuit and drives the motor. The turbo-molecular pump according to claim 1,
The stop signal generating circuit has an input terminal for receiving an emergency stop signal from the outside, and the stop signal generating circuit receives the emergency stop signal from the outside through the input terminal or via the input terminal. A turbo molecular pump device that outputs a deceleration characteristic pattern signal of

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