An axial flow vacuum pump for evacuating a chamber in a semiconductor manufacturing process comprises a rotor having a plurality of rotor blades and a stator having a plurality of stator blades, wherein the rotor blades and stator blades have a curved shape.

A magnetic bearing device and a vacuum pump configured to recover from an abnormal state, such as oscillation in a magnetic bearing levitation system with low false detection of abnormalities. The magnetic bearing device includes a magnetic bearing controller that controls the magnetic bearing, and detects an abnormality of control by the magnetic bearing controller and configured to correct control parameters while continuing an operation of the magnetic bearing device. The device also detects abnormality of the control by the magnetic bearing controller based on an abnormality condition having a larger degree of abnormality than the first abnormality condition, and a stopping means for stopping the operation of the magnetic bearing device.

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.

There are provided a vacuum pump which can effectively prevent stress corrosion cracking of a rotating body and has excellent corrosion resistance, and a rotating body of the vacuum pump. In a vacuum pump (e.g., a turbo-molecular pump 100) exhausting gas by rotation of a rotating body 103, the rotating body 103 has, on a surface thereof, a first area 1 covered with a first surface treatment layer 1A and a second area 2 covered with a second surface treatment layer 2A, and a boundary portion 3 between the first area 1 and the second area 2 has an area in which the surface treatment layers 1A and 1B of the first and second areas 1 and 2 overlap each other.

A magnetic bearing device comprises a radial magnetic bearing configured to magnetically levitate and support a rotor shaft in a radial direction; an axial magnetic bearing configured to magnetically levitate and support, in an axial direction, a rotor disc rotatable together with the rotor shaft; and an axial displacement sensor disposed on a surface of an electromagnet core of the axial magnetic bearing facing the rotor disc and configured to detect axial displacement of the rotor disc.

According to one aspect of the present disclosure, a turbomachine (100) is provided. The turbomachine includes: a rotor extending in an axial direction and comprising a driven side configured to be connected to a driving unit and a second side opposite the driven side; a housing extending around at least a portion of the rotor, wherein a main flow path for a process fluid extends between the rotor and the housing; a sealing arrangement, particularly a dry gas seal, configured for sealing a gap between the rotor and the housing at the driven side of the rotor; and a first magnetic bearing supporting the second side of the rotor. A fluid passage for a portion of the process fluid extends from the main flow path through a bearing gap of the first magnetic bearing. According to a further aspect, a method of operating a turbomachine is described.

A magnetic bearing control device is configured to detect, by a sensor, excitation current supplied from an excitation amplifier to a magnetic bearing configured to magnetically levitate a rotor, thereby generating a voltage equivalent signal for PWM control of the excitation amplifier based on a current setting signal based on a deviation of a rotor levitation position with respect to a target levitation position and an excitation current detection signal of the sensor. The voltage equivalent signal is generated based on the current setting signal and a current deviation signal as a difference between the current setting signal and the excitation current detection signal.

Magnetic bearings are used to support high speed machinery, for example, pumps, compressors, motors and generators, and require active electronics and an automatic feedback control system to realize their function. This invention pertains to improvements of the design of automatic control systems for magnetic bearings to enable system performance validation without requiring all the external components of the rotating apparatus to be present.

A rotation mechanism (20) of a vacuum pump (100) includes a magnetic bearing unit (21) having a first outer diameter (91), the magnetic bearing unit (21) being operable as a first radial magnetic bearing (40), and a motor unit (22) provided on a side of a second end (11b) of a rotary shaft (11) relative to the magnetic bearing unit, the motor unit (22) having a second outer diameter (92) larger than the first outer diameter, the motor unit (22) being operable as both a motor (30) and a second radial magnetic bearing (50).

A magnetic bearing device and a vacuum pump configured to measure with high sensitivity a natural vibration mode of a rotating body in a floating system using a magnetic bearing. The natural vibration to be measured is a bending mode of the rotating body, a natural vibration mode of the rotor blades, a vibration mode associated with the stator, and a rigid body mode of the rotating body. The natural vibration may be computed by a central processing unit (CPU) of a control device or may be computed externally. In this manner, the natural vibration mode can be detected with high sensitivity.