| 摘要 |
PROBLEM TO BE SOLVED: To provide a touchdown bearing device capable of surely supporting a shaft by predetermined times even if the shaft has a long lifetime and rotation speed of the shaft is high, and a turbo-molecular pump of which touchdown bearing device has a long lifetime. SOLUTION: The touchdown bearing device 10 comprises a first inner ring 31 externally fitted and fixed on a rotary shaft 3, a first outer ring 32 radially opposed to the first inner ring 31, a first ball 33 interposed between the first inner ring 31 and the first outer ring 32, a second inner ring 51 radially opposed to the first outer ring 32, a second outer ring 52 internally fitted and fixed in an inner circumference surface of the housing 2, and a second ball 53 interposed between the second inner ring 51 and the second outer ring 52. The touchdown bearing device 10 is configured so that when a magnetic bearing normally operate, the first outer ring 32 and the second inner ring 51 are in a non-contact state, and that meanwhile, when the magnetic bearing does not normally operate, the rotary shaft 3 is supported by the second inner ring 51 so as to support the first outer ring 32 against the housing 2. COPYRIGHT: (C)2008,JPO&INPIT
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