| 摘要 |
PURPOSE:To miniaturize a bearing device and manufacture it inexpensively without the contamination of an external atmosphere by using magnetic fluid for bearing fluid, and preventing its outward leakage by means of magnetic seals, and moreover providing force feed mechanisms opposite to oil collecting grooves to return the magnetic fluid into fluid reservoirs. CONSTITUTION:Four fluid reservoirs 22 in peripheral direction are provided on the inner periphery of the middle part 21b of a casing main body 21, and magnetic seals 23L, 23R formed of permanent magnets 24 and magnetic yokes 25a, 25b are provided at the ends of the inner peripheral surfaces of both end parts 21a, 21c respectively. In addition to that, oil collecting grooves 28L, 28R communicating with the fluid reservoirs 22 through gaps 27 end a circulating passage 29 are formed to cause force feed mechanisms 30L, 30R formed opposite to the oil collecting grooves 28L, 28R to forcedly feed magnetic fluid into the fluid reservoirs 22. The outward leakage of the magnetic fluid can be therefore certainly prevented to improve force feed efficiency for the use of a bearing device in vacuum condition, and moreover the bearing device can be miniaturized and inexpensively manufactured.
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