| 摘要 |
PURPOSE: To prevent parts in a container from being contaminated by vacuum side infiltration of lubricant vapor when a pump fails to be stopped, by providing an electronic passive position regulating means having radially centering passive magnetic bearings and emergency bearings, which originate an unstable point, and especially containing a lowering disk for turbo-molecular pumps. CONSTITUTION: A rotor 5 is radially centered by two passive magnetic bearings, and the passive bearings are respectively formed of magnetic bearing-stators 10, each of which is located on a high vacuum end on a vacuum front end. The stator 10 and a rotor 9 of the magnetic bearing are formed of rings of the same polarity, which are concentrically piled up. An inner ring forming the stator 10 is integrally mounted with a housing, while an outer ring forming the rotor 9 is incorporated in the rotor 5. With an operating point of the magnetic bearing, since the rotor 9 is shifted with respect to the stator 10 in the direction of a high vacuum flange 2, a force in the direction of the flange is generated at the rotor 5, and the axial force is compensated by solenoids or lift-up magnets 11. Besides, current of the solenoid 11 is controlled by a position sensor 12.
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