| 摘要 |
PROBLEM TO BE SOLVED: To provide a fluid dynamic bearing capable of obtaining a stable thrust floating characteristic even though temperature at operating circumstances is changed. SOLUTION: The relationship among a gap A of a thrust dynamic pressure generating groove surface, a gap B of an oil sump at an outer peripheral surface of a flange 3, a gap C between a surface at a sleeve 1 side of the flange 3 and the sleeve 1, a gap G of a radial dynamic pressure generating groove, a gap D of an oil sump between the gap G and the gap C, and a gap H of an oil sump at a bearing releasing side adjacent to the gap G is G<H, A<B and A<D, C<B and C<D, and B<H and D<H. A coefficient of viscosity of oil or base oil of grease is 4 centistokes or more at 40°C. The fluid dynamic bearing obtains a stable thrust floating characteristic so that one of an outer periphery of the sleeve 1 and an outer periphery of a shaft 2 is fixed on a base 6, and the other outer periphery is rotatably fixed on a hub rotor 7. COPYRIGHT: (C)2004,JPO&NCIPI
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