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.

A rolling bearing includes an inner ring, an outer ring, and a plurality of balls interposed between the inner ring and the outer ring. The inner ring and the outer ring are made of stainless steel. A raceway surface with which the ball is in rolling-contact in each of the inner ring and the outer ring and is a superfinished surface and a coating layer made of a solid lubricating film is formed on the superfinished surface.

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.

A turbomachine according to an embodiment of the present disclosure may include a rotary shaft, a magnetic bearing including a core body configured to surround the rotary shaft, a plurality of poles radially extending from an inner surface of the core body toward the rotary shaft, and coils wound around the plurality of poles to levitate the rotary shaft by using a magnetic force generated by a magnetic field formed by applied electric current, a sleeve journal bearing disposed between the rotary shaft and the magnetic bearing so as to surround the rotary shaft and configured to levitate the rotary shaft by generating a dynamic pressure when the rotary shaft rotates, and a permanent magnet disposed between the plurality of poles and configured to support the rotary shaft by using a magnetic force.

A vacuum pump exhaust system and an exhausting method of the vacuum pump supply a purge gas to the vacuum pump such that an amount of the purge gas satisfies one of following conditions: an amount of the purge gas flowing at a higher velocity than a backflow velocity of gas exhausted by the vacuum pump on at least a part of a downstream side of the temperature sensor unit, and an amount of the purge gas having a pressure of one of an intermediate flow and a viscous flow around the temperature sensor unit. The exhaust system further includes a purge gas supply unit capable of controlling a flow rate of purge gas introduced into the vacuum pump. This configuration can prevent process gas from flowing backward so as to change the composition around the temperature sensor unit, thereby accurately measuring the temperature of the rotating portion.

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.

A magnetic bearing control apparatus and a vacuum pump which do not require a displacement sensor, which enable control with high accuracy, and which are small and low cost. A rate of change (di/dt) that is a time derivative of a current value I.sub.m flowing through an electromagnet varies in accordance with a magnitude of a displacement of a gap between a target member and the electromagnet. The rate of change (di/dt) can be obtained by detecting a voltage value V.sub.s that is generated at both ends of an inductive element. Therefore, by detecting the voltage value V.sub.s, the magnitude of the displacement of the gap can be estimated by calculation. Inductive elements are connected in series to electromagnets and the voltage V.sub.s between the inductive elements is detected by the differential input amplifier. A single period of switching of a PWM switching amplifier is constituted by a current control period of the electromagnet and a displacement detection period for detecting the rate of change (di/dt). In addition, the displacement detection period is further constituted by a current increase period and a current decrease period which are certain periods of time. The current increase period and the current decrease period are equal to each other.

A vacuum pump comprises: a base; a rotor shaft rotatably provided at the base; a rotor including rotor blades arranged in multiple stages and a rotor cylindrical portion, and attached to the rotor shaft; stationary blades each arranged between adjacent ones of the rotor blades, the stationary blades and the rotor blades forming a turbo exhaust portion; a stator forming, together with the rotor cylindrical portion, a screw groove exhaust portion; and a hexagon socket head cap screw configured to fix the stator to an upper surface of the base in a guiding path of the screw groove exhaust portion to which gas is guided from the turbo exhaust portion. The hexagon socket head cap screw is a bolt having a smaller height of a head portion than that of a hexagon socket head cap screw according to a provision of a country of use or an international organization.