| 摘要 |
PROBLEM TO BE SOLVED: To provide a turbo molecular pump capable of increasing pump performance at all times. SOLUTION: A turbo molecular pump is provided with a casing 3, a rotor 4 arranged in the casing 3, a displacement detection means 12 of the rotor 4, a plurality of sets of control type magnetic bearings 13, 14, 15 supporting the rotor 4 in a non-contact manner by a plurality of electromagnets 19 (19a, 19b), 20, 21 (21a, 21b), a plurality of stator blades 11 provided in the casing 3 in a fixed manner, a plurality of rotor blades 10 arranged between the stator blades 11 provided on the rotor 4 in a fixed manner, and an electromagnet control means controlling a position of the rotor 4 by controlling the electromagnets 19, 20, 21 based on outputs of the displacement detection means 12. The electromagnet control means controls a position of the rotor 4 in the axial direction in such a way that a size of a clearance in the axial direction between each rotor blade 10 and the stator blade 11 on one side is smaller than a size of a clearance in the axial direction between each rotor blade 10 and the stator blade 11 on the other side and the size of the clearance in the axial direction on one side becomes a desired value.
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