Abstract: The present invention provides a turbo-molecular pump in which an exhaust action is achieved by virtue of the combination of stationary blades and rotor blades adapted to rotate at high speed and to cooperate with each other to impart momentum to gaseous molecules rushing in against the blades under an extremely low-pressurized condition. Disposed inside the casing are a fixed shaft and the rotor, the latter being movably supported by a pair of active radial magnetic bearings. A motor is interposed between said pair of magnetic bearings. A dynamic damper is provided at one end of the fixed shaft to inhibit the occurrence of vibrations.

Abstract: An active magnetic bearing apparatus wherein an object designed to be suspended is supported by a plurality of active magnetic bearings and is suspended in a non-contact state so that the object is caused to move in either a rotational or reciprocating manner in such a state. The magnetic force of the respective active magnetic bearings is controlled electrically. A delay control mechanism is provided to cause a delay in the starting-up time for the respective active magnetic bearings so that these bearings are caused to start up sequentially when they are activated, thus making it possible to make the capacity of the power source as small as possible.

Abstract: A rotation control system for preventing unbalance vibrations and synchronous disturbance vibrations of a rotary member suspended by a magnetic bearing. This system includes a vibration detector which detects radial vibration of the rotary member. On the basis of the detected radial vibration, a compensating signal which has the same amplitude and cycle as the vibration component having the rotational frequency is generated. The difference between the detected vibration and the compensating signal is obtained and used for controlling the radial position of the magnetic bearing.

Abstract: An active type magnetic bearing system includes magnetic bearings for suspending a rotary body to permit it to rotate about its rotational axis. A control system supplies the magnetic bearings with signals to control the radial position of the rotary body, and comprises displacement detecting circuits for detecting any displacement of the radial position of the rotary body and a control circuit for producing a control signal which serves to suppress any unstable vibration of the rotary body.