| 摘要 |
PROBLEM TO BE SOLVED: To provide a bearing unit which enables the prevention of the function decline due to evaporation of magnetic fluid. SOLUTION: The bearing unit 1 is provided with a fixed shaft 2, an outer ring sleeve 4 and magnetic fluid. The fixed shaft 2 has a shaft side radial surface and a shaft side thrust surface. The outer ring sleeve 4 is disposed rotatably for the fixed shaft 2 in the outer periphery of the fixed shaft 2, has an outer ring side radial surface comprising the shaft side radial surface and the radial bearing surface, and an outer ring side thrust surface comprising the shaft side thrust surface and the thrust bearing surface, and also is made of a porous material. A magnetic fluid is injected between the radial bearing surface and between the thrust bearing surface. In at least one bearing surface of either radial bearing surface or thrust bearing surface, a plurality of magnetic poles are formed in one surface of two surfaces forming the bearing surface. A dynamic pressure generating means is provided in the radial bearing surface and the thrust bearing surface. COPYRIGHT: (C)2007,JPO&INPIT
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