JP2003065283A - Turbo molecular pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbo molecular pump which reduces time of rotation caused by inertia of a body of rotation after occurrence of an outage and improves durability of a touch bearing. SOLUTION: In a power supply device 1 of the turbo molecular pump, a load 8 for excess power consumption for consuming regenerative power, a transistor Q1 for on/off control of this load 8 for excess power consumption and a contact B of a relay K1 in parallel with this transistor Q1 are provided. By this, when control of the transistor Q1 becomes impossible due to outage, regenerative power of a motor 12 is electrified to the load 8 for excess power consumption through the contact B of the relay K1 for consumption. In this way, even after an inverter control circuit 6 does not function any more due to the outage, a load circuit of the motor 12 can operate, a deceleration force is given to a turbo mechanism body of rotation 16 and time to stop of the body of rotation can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbo molecular pump capable of responding to a power failure without damage.

[0002]

2. Description of the Related Art For example, in a semiconductor film forming apparatus or the like, a turbo molecular pump is used to evacuate the process chamber in order to make it a high vacuum. The structure of this turbo molecular pump is as schematically shown in FIG. 3, in which a turbo mechanism rotating body 16 having an exhaust function is driven by a motor 12 to rotate the pump body 11 and a power supply device 1 for driving the same. It is configured and connected to a process chamber (not shown) of a semiconductor manufacturing apparatus (not shown) or the like via an exhaust system (not shown). The pump body 11 is a fixed blade (not shown)
And a turbo mechanism rotating body 16 composed of a rotor on which fixed blades and rotary blades forming a turbine are formed, and a rotary shaft 1
3, a motor 12 driven to rotate at high speed via a magnetic bearing 14, a magnetic bearing 14 that supports the turbo mechanism rotor 16 in a non-contact manner by floating it at a high speed, a touch bearing 15 that supports the turbo mechanism rotor 16 when not energized, and the like. Composed. On the other hand, the power supply device 1 for rotationally driving the motor 12 includes an AC / DC converter 2 that returns AC electric energy from the commercial power supply 18 as input to primary DC power, and a rectifier 3 for preventing regenerative power backflow. , A three-phase inverter 4 to which the primary DC power is input, and an inverter control circuit 6 for controlling the three-phase inverter 4. Further, it comprises a magnetic bearing control circuit 7 and the like. The AC / DC converter 2 converts the AC power from the commercial power supply 18 into the primary DC power as described above. The rectifier 3 has a function as a diode for preventing backflow. The three-phase inverter 4 converts the DC power supplied from the AC / DC converter 2 into AC power having a frequency necessary for the rotation speed of the motor 12 set by the inverter control circuit 6, and supplies this power to the pump body 11. Then, the motor 12 is driven. The DC / DC converter 5 receives the primary DC power from the AC / DC converter 2, controls the voltage to the DC constant voltage for the control circuit here, and then supplies the power to the inverter control circuit 6 and the magnetic bearing control circuit 7. The inverter control circuit 6 controls the rotation of the motor 12 and turns on / off the transistor Q1. When the motor is on, the regenerative electric power generated during deceleration of the motor 12 is consumed through the surplus electric power consumption load 8. The output of the magnetic bearing control circuit 7 is supplied to the magnetic bearing 14 in which the pump body 11 is incorporated as electric power for magnetic levitation of the turbo mechanism rotor 16.

Such a magnetic levitation type turbo-molecular pump normally makes the turbo mechanism rotor 16 magnetically levitated,
Rotate at high speed (for example, 20,000 rpm). Therefore, in such a turbo molecular pump, it is necessary to recover the rotational energy of the turbo mechanism rotating body 16 at the time of deceleration, and the power is normally recovered from the motor 12 to the power supply device 1 side by the regenerative power. That is, it is surplus power. Therefore, in general, the power supply device 1 has a built-in surplus power consumption load 8 for consuming surplus power as shown in FIG. When the motor 12 is decelerating to generate regenerative electric power, the transistor Q1 is operated, and the surplus electric power is supplied to the surplus electric power consumption load 8 to consume heat.

On the other hand, when a power failure occurs, the turbo mechanism rotating body 16 continues to rotate due to the rotation inertia and gradually decelerates. At this time, the motor 12 also generates regenerative electric power. This regenerated power is also supplied to the magnetic bearing control circuit 7 via the DC / DC converter 5 in the power supply device 1, the magnetic bearing 14 continues to operate, and the turbo mechanism rotating body 16
The magnetic levitation state will be continuously maintained. As the turbo mechanism rotating body 16 further decelerates, the regenerative power also decreases. For example, when the speed is reduced to 6,000 rpm, the regenerative electric power necessary for maintaining the magnetic levitation of the turbo mechanism rotor 16 cannot be obtained. Therefore, the turbo mechanism rotor 16 is mechanically supported by the touch bearing 15 until the turbo mechanism rotor 16 stops. Will be. Further, in the rotating state where the magnetic levitation is lost, the inverter control circuit 6 that controls the drive of the motor 12 also loses the control function, so that the transistor Q1 also becomes inactive and the regenerative power consumption by the surplus power consumption load 8 can be performed. Disappear. Therefore, the rotation of the motor 12 cannot be controlled to be decelerated, and the turbo mechanism rotating body 16 is stopped by the rolling resistance and the air resistance of the touch bearing 15.

[0005]

In recent years, the diameter of the turbo molecular pump has been increased, and the moment of inertia of the turbo mechanism rotating body 16 is increasing. As a result, when the power failure occurs, the rotating body is magnetically levitated as described above. After losing the touch bearing 15
When this rotating body is supported only by itself, the time until the turbo mechanism rotating body 16 stops in the current drive mechanism is as long as approaching one hour. Therefore, if the state in which the turbo mechanism rotor 16 is supported by the touch bearing 15 is prolonged, the life of the touch bearing 15 is shortened because the weight of the rotor is large. The present invention is
In view of such circumstances, it is an object of the present invention to provide a turbo molecular pump capable of shortening the rotation time due to inertia of the rotating body after the occurrence of a power failure and improving the durability of the touch bearing. To do.

[0006]

In order to solve the above-mentioned problems, a turbo molecular pump provided by the present invention is provided with a power consumption load for consuming regenerative power provided in a power supply device,
A means for supplying regenerative current is provided even after the inverter control circuit loses its control function when a power failure occurs. As a result, the regenerative power generated by the motor is conducted to the power consumption load circuit even after the power failure occurs and the turbo mechanism rotating body is reduced to the rotation speed at which it loses the magnetic levitation state.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a first embodiment of a turbo molecular pump according to the present invention. In the figure, the components and parts indicated by the same reference numerals as those in FIG.
The detailed description of these functions and the like will be omitted. The present invention is characterized in that a transistor Q1 functioning as a switching circuit is connected in parallel with a contact B of a relay K1 as shown in FIG. The B contact is a contact having a function of keeping the off state when the relay coil is energized and keeping the on state when the relay coil is de-energized, and the relay K1 has such a function. There is. The transistor Q1 controls on / off of the surplus power consumption load 8 that consumes regenerative power by a signal from the inverter control circuit 6. The relay K1 is set to be in an operating state, that is, a coil is energized by the relay drive power from the DC / DC converter 5 during the normal drive of the turbo molecular pump. At this time, the B contact of the relay K1 is turned off.

The operation when a power failure occurs will be described below. When a power failure occurs, the rotation of the turbo mechanism rotating body 16 gradually decreases, and the regenerative power of the motor 12 decreases in proportion to this. Therefore, due to this decrease, DC / D
When the output of the C converter 5 becomes abnormal, the control signal to the relay K1 is cut off and the relay K1 is deactivated. When the relay K1 is not operated, the regenerative power of the motor 12 is consumed by the surplus power consumption load 8 through the B contact of the relay K1. At this point, as described above, DC / DC
Since the output of the converter 5 is abnormal, the inverter control circuit 6 does not operate and the transistor Q1 is turned off. However, the regenerative power current flowing to the excess power consumption load 8 is relayed from the transistor Q1 to the relay. It is switched to flow through the B contact of K1 and power is consumed. As described above, according to the present invention, by providing the B contact of the relay K1, the regenerative power of the motor 12 can be consumed by the surplus power consumption load 8 even after the inverter control circuit 6 stops operating. The deceleration force can be continuously applied, and the time until the turbo mechanism rotating body 16 is stopped can be shortened. The reduction of the rotation time due to the inertia of the rotating body can shorten the time required to start the recovery work from the power failure, and the rotation time of the turbo mechanism rotating body 16 by the touch bearing 15 can be shortened.
The durability of 5 can be improved.

FIG. 2 is a block diagram showing a second embodiment of the present invention. In this figure, the components denoted by the same reference numerals as those in FIG. 1 are the same as those in FIG. 1, and detailed description of their functions and the like will be omitted. The circuit configuration of the second embodiment of the present invention is as follows.
And a relay K2 for turning on / off the dedicated load 9 at the time of power failure. It is characterized in that the turbo mechanism rotating body 16 is stopped more quickly than in the first embodiment after the inverter control circuit 6 stops operating by providing the dedicated load 9 during a power failure in addition to the surplus power consumption load 8. .

Normally, the excess power consumption load 8 is a motor 12
Since the resistance value is determined assuming that the voltage of the regenerative power returned from is used in a high state, the regenerative power of the motor 12 will gradually decrease in the state where the rotation decreases after the magnetic levitation is stopped. In some cases, sufficient current may not flow to decelerate the turbo mechanism rotating body 16. For this reason, the dedicated load 9 during a power failure having the optimized resistance value shown in FIG. 2 is provided,
By using the load resistance via the B contact of the relay K2, a larger amount of current can be made to flow as compared with the first embodiment, so that a large deceleration force can be applied to the motor 12. As described above, the relay K is provided with the dedicated load 9 during a power failure having a resistance value such that a sufficient current flows even when the regenerative power of the motor 12 is low.
By connecting the two mechanical contacts as the load of the motor 12, it is possible to generate a sufficient deceleration force in the motor 12 until the rotation is stopped.

Although the present invention has been described above, it is not limited to the above and illustrated examples, but includes various modifications. For example, in the above description, the first embodiment
The function for stopping the inertial rotation of the motor 12 earlier by using the surplus power consumption load 8 as the load of the motor 12 and the surplus power consumption load 8 or the dedicated load 9 during a power failure as the load has been described in the second embodiment. It is also possible to install the excess power consumption load 8 and the circuit of the relay K1 and the circuit of the dedicated load 9 for the power failure and the relay K2 shown in FIG. 2 in parallel. In the case of a drive power supply with a built-in emergency power supply,
By providing a plurality of dedicated loads at the time of power failure having different resistance values, sequentially switching a plurality of relays connected to each of these by a timer, and by lowering the resistance value of the dedicated load at the time of power failure as the rotation of the motor 12 decreases, Further, the rotation of the turbo mechanism rotating body 16 can be stopped quickly.

[0012]

As described above, according to the present invention, the rotation time due to inertia of the rotating body after the occurrence of a power failure can be shortened, so that the time required for the recovery work from the power failure of the apparatus using the turbo molecular pump can be shortened. Moreover, since the rotation time of the rotating body by the touch bearing is shortened, the durability of the touch bearing can be improved. This extends the maintenance cycle of the turbo molecular pump and contributes to cost reduction of capital investment.

[Brief description of drawings]

FIG. 1 shows a block diagram of Embodiment 1 of a system for driving a turbo molecular pump according to the present invention.

FIG. 2 shows a block diagram of a second embodiment of a system for driving a turbo molecular pump according to the present invention.

FIG. 3 shows a block diagram of a system for driving a conventional turbo molecular pump.

[Explanation of symbols]

1 --- power supply 4 --- 3-phase inverter 6 --- Inverter control circuit 8--Load for surplus power consumption 9 --- Dedicated load during power failure 11 --- Pump body 12 --- motor 13 --- Rotation axis 15 --- Touch bearing 16 --- Turbo mechanism rotating body

Claims (2)

[Claims] 1. A turbo molecular pump main body for rotatably driving a turbo mechanism rotating body having an exhaust function with a motor, and a power supply device for supplying electric power to this motor.
In a turbo molecular pump that continues magnetic levitation of a rotating body with regenerative power from a motor obtained by decelerating the rotating body, a regenerative power consumption load for consuming regenerative power due to rotation of the motor, and this regenerative power A turbo molecular pump comprising: a switching circuit for turning on / off a power consumption load; and a relay connected in parallel to the switching circuit and operating in the event of a power failure in the power supply circuit. 2. A turbo molecular pump main body for rotatably driving a turbo mechanism rotating body having an exhaust function by a motor, and a power supply device for supplying electric power to this motor, which are obtained by decelerating the rotating body when a power failure occurs. In a turbo molecular pump that continues magnetic levitation of a rotating body with regenerative power from a motor, it is connected to a dedicated load for regenerative power consumption dedicated to a power failure and this dedicated load for regenerative power consumption during a power failure, and is turned on during a power failure. A turbo molecular pump, characterized in that: