JPH0729278Y2 - Rotor braking device for magnetic bearing type turbo molecular pump - Google Patents

Description

[Detailed Description of the Invention] << Industrial Application Field >> The present invention relates to a device for magnetically levitating and braking a rotor of a magnetic bearing type turbo-molecular pump during a power failure, and in particular to a battery used as a power source during a power failure. A device provided.

<< Prior Art >> In a magnetic bearing type turbo molecular pump, a rotor is magnetically levitated by a magnetic bearing, and in that state, it is rotationally driven by a motor.

Therefore, when the operation of the magnetic bearing is stopped due to a power failure, the rotating rotor damages the stator and the like.

In order to prevent damage to the inside of the pump during the power failure, a device of this type is provided in the pump, and the rotor is magnetically levitated and braked by the device during the power failure.

Conventionally, a battery has been used as a power source for magnetic levitation of the rotor and its braking during a power failure.

<< Problems to be Solved by the Invention >> However, since a large amount of electric power is consumed for braking the rotor, there is a problem in the conventional device that a large-sized battery must be used as a power source.

The present invention has been made in view of the above conventional problems,
It is an object of the present invention to provide a rotor braking device for a magnetic bearing type turbo-molecular pump, which can reduce the size of a battery used as a power source of the device in the event of a power failure.

<< Means for Solving Problems >> In order to achieve the above object, the present invention provides an electromagnet drive circuit for energizing an electromagnet of a magnetic bearing to magnetically levitate a rotor, and a power failure detection means for detecting a power failure of a power source. The electric motor braking circuit for braking the rotor drive motor at the time of power failure, the rotation speed detection means for detecting the rotation speed of the rotor drive motor, and the rotation speed detected by the rotation speed detection means at the time of power failure are preset. A magnetic bearing control circuit for controlling to stop the energization of the electromagnet when the rotation speed is reduced, an electromagnetic valve provided in a pipe for introducing a rotor braking gas into the pump from the outside, and an electric braking circuit for a power failure. Detection means for detecting the failure of the above, a power failure control circuit for opening and controlling the electromagnetic valve based on the control signal of the detection means, an electromagnet drive circuit, a magnetic bearing control circuit, a power failure control circuit. , Having a battery for supplying the power failure the operating current to the drive circuit of the solenoid valve, characterized in that.

<< Operation >> In the present invention, since the operating current is not supplied from the battery to the electric braking circuit that brakes the rotor driving motor, the electric power of the battery is not consumed for the electric braking of the rotor during a power failure.

Further, when a failure occurs in the circuit for electrically braking the rotor, the gas is introduced into the pump, so that the rotor is braked without consuming the electric power of the battery.

<< Embodiment >> A preferred embodiment of an apparatus according to the present invention will be described below with reference to the drawings.

In the figure, electromagnets 12-1, 12-2, 12-3, 12-4, 12-5 are provided in the main body 10 of the magnetic bearing type turbo-molecular pump, and a rotor (not shown) is arranged in a predetermined posture by them. It is magnetically levitated.

The electromagnets 12-1, 12-2, 12-3, 12-4, 12-5 are energized by the electromagnet drive circuit 14, and the energization control is performed by the magnetic bearing control circuit 16.

The rotor thus magnetically levitated is rotationally driven by the motor 18, and a drive current is supplied to the motor 18 from the inverter 20.

A direct current is supplied from the DC-DC converter 22 to the inverter 20, and the inverter 20 and the DC-DC converter 22 are controlled by the motor control circuit 24.

As a result, the rotor is magnetically levitated and is rotationally driven at a constant rotation speed while maintaining a predetermined posture.

The power source for driving the rotor to rotate is taken from an external AC power source 26, and its AC current is a DC power source circuit.
Converted to direct current by 28.

The DC power supply of the DC power supply circuit 28 is the DC-DC converter 22.
Are directly supplied to the magnetic bearing control circuit 16 and the motor control circuit 24 via the power source switching unit 30.
The magnetic bearing control circuit 16 supplies an operating current to 14 together with a control signal.

Further, the power switch 30 detects a power failure of the AC power supply 26, and at the time of detection, the output current of the battery 32 is switched from the power switch 30 to the magnetic bearing control circuit 16, the motor control circuit 24, and the power failure control circuit 34. ing.

At that time, the power failure of the AC power supply 26 is caused by the power switch 30 via the power failure control circuit 34, the magnetic bearing control circuit 16, the motor control circuit 24.
Have been notified to.

As a result, the rotors are electromagnets 12-1, 12-2, 12-3, 12-4, 12
By -5, magnetic levitation continues in a predetermined posture.

The electric control circuit 36 provided integrally with the inverter 20 electrically brakes the motor 18 in accordance with a control signal supplied from the motor control circuit 24 to the inverter 20.

In the electric braking circuit 36 of the present embodiment, the resistance braking of the motor 18 is performed, so that the rotor is electrically braked without the power of the battery 32 being consumed by the present device.

A pulse signal indicating the rotation speed of the motor 18 (that is, the rotation speed of the rotor) is obtained by the sensor 38, and the rotation speed of the motor 18 (rotation speed of the rotor) is detected by the rotation speed detection circuit 40 from the pulse signal. ing.

The detection signal is supplied to the magnetic bearing control circuit 16,
In the magnetic bearing control circuit 16, when it is confirmed by the detection signal of the rotation speed detection circuit 40 that the rotation speed of the motor 18 (rotor) has been reduced to a predetermined rotation speed by electric braking, the electromagnets 12-1, 12
A control signal for stopping the energization of −2, 12-3, 12-4, 12-5 is obtained.

As a result, the magnetic levitation of the rotor is stopped, and the rotor thereafter rotates in contact with a bearing (not shown).

When the power supply 26 fails as described above, the rotor is magnetically levitated using the output current of the battery 32, but the rotor is electrically braked by the electric braking circuit 36 without consuming the power of the battery 32.

Then, when the rotation speed of the rotor decreases, the magnetic levitation is terminated, and the rotor is supported by the bearing thereafter.

In addition, when the electric braking circuit 36 fails or fails when the AC power supply 26 fails, the rotor is braked during the power failure by introducing gas from the outside into the main body 10 of the magnetic bearing type turbo-molecular pump. It is done by.

Therefore, the gas for rotor braking is led from the outside to the inside of the main body 10 of the magnetic bearing type turbo-molecular pump via the pipe line 42, and the pipe line 42 is provided with the electromagnetic valve 44.

The electromagnetic valve 44 is driven by the valve drive circuit 46, and the valve drive circuit 46 is supplied with the control signal and the operating current from the power failure control circuit 34.

Further, the main circuit current (braking current) of the inverter 20 is monitored by the main circuit current monitoring circuit 48, and the monitoring signal is supplied to the power failure control circuit 34.

In the power outage control circuit 34, a control signal for opening and controlling the electromagnetic valve 44 is obtained from the monitoring signal of the main circuit current monitoring circuit 48 when the failure of the electric braking circuit 36 is detected, and the electromagnetic valve 44 is opened. As a result, the rotor braking gas is introduced into the main body 10 of the magnetic bearing type turbo-molecular pump from the outside.

Therefore, when the electric braking circuit 36 fails during the electric braking of the motor 18 (rotor) during a power failure, and when the electric braking circuit 36 fails, rotor braking by gas is performed instead of electric braking.

As described above, according to the present embodiment, the electric power of the battery 32 is not consumed for braking the motor 18 (that is, the rotor) when the AC power supply 26 is out of power, and is consumed only for its magnetic levitation. A small one with a small capacity can be used.

Therefore, it is possible to reduce the size and cost of the pump system.

Further, according to the present embodiment, when the electric braking circuit 36 fails, gas is introduced from the outside into the pump to brake the rotor, so that even when the electric braking circuit 36 fails, the rotor does not consume the power of the battery 32. Can brake.

Therefore, it is not necessary to use a large battery 32 in preparation for a failure of the electric braking circuit 36. Therefore, the pump system can be increased in size and cost can be increased while ensuring reliable braking of the rotor when the AC power supply 26 fails. It is possible to avoid it.

<Effect> As described above, according to the present invention, the rotor is braked without electric power consumption of the battery due to electric braking or gas introduction into the pump during a power failure. The pump system can be used, and therefore the size and cost of the pump system can be reduced.

[Brief description of drawings]

The drawing is a block diagram showing a preferred embodiment of the apparatus according to the present invention. 10 …… Main body of magnetic bearing type turbo molecular pump 12-1,12-2,12-3,12-4,12-5 …… Electromagnet 14 …… Electromagnetic drive circuit 16 …… Magnetic bearing control circuit 18 …… Motor 20 …… Inverter 22 …… DC-DC converter 24 …… Motor control circuit 26 …… External AC power supply 28 …… DC power supply circuit 30 …… Power switch 32 …… Battery 36 …… Electric braking circuit 38 …… Sensor 40 …… Revolution detection circuit 42 …… Pipe line 44 …… Electromagnetic valve 46 …… Valve drive circuit 48 …… Main circuit Current monitoring circuit

Claims (1)

[Scope of utility model registration request] 1. An electromagnet drive circuit for energizing an electromagnet of a magnetic bearing to magnetically levitate a rotor, a power failure detection means for detecting a power failure of a power supply, an electric braking circuit for braking a rotor drive motor at the time of power failure, and a rotor drive Number detecting means for detecting the number of rotations of the motor for driving, and a magnetic control for stopping the energization of the electromagnet when the number of rotations detected by the number of rotations detecting means decreases to a preset number of rotations during a power failure. A bearing control circuit, an electromagnetic valve provided in a pipe for introducing rotor braking gas into the pump from the outside, detection means for detecting a failure of the electric braking circuit at the time of power failure, and a control signal of the detection means. Supply the operating current to the electromagnet drive circuit, the magnetic bearing control circuit, the power failure control circuit, and the electromagnetic valve drive circuit when a power failure occurs. It has a battery, a rotor braking device of a magnetic bearing type turbo molecular pump, characterized in that.