An electromagnet unit, a magnetic bearing device, and a vacuum pump with which displacement of a rotating body in a radial direction can be detected with precision. An upper electromagnet unit includes: radial electromagnets for supporting a rotor in a radial direction without contact; radial sensors for detecting displacement of the rotor in the radial direction; and a core around which coils are wound. Two radial electromagnets that are adjacent to each other in a circumferential direction of the core are disposed such that adjacent magnetic poles belonging respectively to the two radial electromagnets are homopolar, and a low magnetic flux interference region is formed between the two radial electromagnets. Each of the radial sensors is disposed in the low magnetic flux interference region.

A magnetic levitation control device comprises: a control signal generation section configured to generate a first excitation current control signal based on current deviation information on the excitation current detection signal with respect to the current setting signal and a second excitation current control signal based on the current setting signal; and a selection section including a first switching section configured to select either one of the first excitation current control signal or the second excitation current control signal or a second switching section configured to select either one of a third excitation current control signal obtained by summation of the first excitation current control signal and the second excitation current control signal or the second excitation current control signal. The excitation amplifier is PWM-controlled based on the excitation current control signal selected by the selection section.

A reflection mechanism is disposed above a rotor blade. A chamfered surface of the rotor blade is formed to gradually open wide by 0 to 10 degrees toward the downstream side in the rotational direction, from an imaginary line passing through a rotational direction-side tip end point of a horizontal surface and drawn parallel to a rotating shaft. In the reflection mechanism, inclined plates, inclined at a predetermined angle, are arranged radially in the radial direction from a central disc portion. A particle reflected on the chamfered surface of the rotor blade collides with each inclined plate of the reflection mechanism and is then re-reflected and falls in the downstream direction. Since the particle can securely be reflected toward the reflection mechanism, the particle can be prevented from exiting through an inlet port to flow back toward a chamber.

The present disclosure can provide a vacuum pump capable of obtaining a rotation direction and correcting the rotation direction without adding a dedicated rotation direction sensor even in a state of low-speed rotation. The control device is capable of obtaining at least a first state in which a rotor shaft rotates at relatively high speed, and a second state in which the rotor shaft deviates within a gap between the rotor shaft and a protective bearing and rotates at relatively low speed while revolving, acquires output information of a radial displacement sensor, obtains a rotation direction of the rotor shaft in the second state on the basis of the output information, determines whether the rotation direction is normal or not, and when the rotation direction is not normal, stops the rotation and increases rotation speed to achieve a normal rotation direction.

A first arithmetic section calculates a current rotation component phase value and a current rotation component amplitude value. A second arithmetic section calculates a displacement rotation component phase value and a displacement rotation component amplitude value. A third arithmetic section calculates a ratio between the amplitude value of the current rotation frequency component and the amplitude value of the displacement rotation frequency component. Feedback control is performed such that the current rotation component phase value is equal to a value obtained by addition of a phase value of 180 degrees to the displacement rotation component phase value and that the amplitude value of the current rotation frequency component is equal to a product of the displacement rotation frequency component and the ratio.

To properly set a predetermined threshold for the number of times of occurrence of an abnormality for issuing an alarm. A vacuum pump system includes a storage, a pump controller, and a setter. The storage stores a first threshold for the number of times of occurrence of the abnormality for outputting the alarm. The pump controller counts the number of times of occurrence of the abnormality caused in a vacuum pump, determines whether or not the number of times of occurrence of the abnormality is the first threshold or more, and outputs the alarm in a case where the number of times of occurrence of the abnormality is the first threshold or more. The setter sets or changes the first threshold on the basis of an operation state of the vacuum pump.

A vacuum pump includes a control unit that monitors and controls a motor and a magnetic bearing, each being stored in a pump body. A temperature-adjustment function unit measures a temperature of the pump body by at least one temperature sensor disposed in the pump body and controls at least one heater or solenoid controlled valve based on the temperature. The temperature-adjustment function unit includes a first terminal capable of connecting or disconnecting the temperature sensor and a second terminal capable of connecting or disconnecting one of the heater and the solenoid controlled valve. A self-diagnosis unit capable of conducting a self-diagnosis of whether an input signal to the first terminal has been normally inputted or whether the signal has been normally outputted from the second terminal.

The invention relates to a bearing preload force gauge for indicating the bearing preload force on a turbomolecular pump rotor bearing. The gauge comprises a housing, an indicator for indicating the bearing preload force, and actuator coupled to an impeller engagement surface by a member configured to provide a resilient bias between the actuator and the impeller engagement surface. The invention also relates to a bearing preload tool and methods for measuring the bearing preload force on a turbomolecular pump.

A position deviation calculated by a subtractor of a vacuum pump is input to the PIDs of three modes. The first PID is a PID controller for a high-bias mode, the second PID is a PID controller for a high-rigidity mode, and the third PID is a PID controller for a low-rigidity mode. The output signal of the third PID is extracted as a change of an indicator current for each clock of a PWM frequency and then the mean value of a change of an indicator current for several clocks is determined in a calculating unit. At this point, a switching control unit performs an operation on whether the mean value of the averaged change of the indicator current is larger than a preset redetermined value and then according to the result, an value is outputted in the range of 0 to 1 from the switching control unit.

An electromagnetic rotating apparatus may include an electromagnet winding that consumes power generated during regeneration. A motor voltage monitoring circuit detects that a voltage at a motor driving main circuit is higher than a voltage during normal operation, due to overshoot or the like after arrival at a set speed during deceleration or acceleration of a motor. The motor voltage monitoring circuit transmits a high-voltage detection signal to a braking current adjusting circuit and a magnetic bearing control circuit. Upon receiving the high-voltage detection signal, the braking current adjusting circuit reduces a braking current command value for the motor so as to maintain an excitation voltage for the motor constant or reduce this excitation voltage, and an amplifier control circuit in the magnetic bearing control circuit increases a bias current flowing through an electromagnet winding to increase power consumption.