Patent ID: 8064166
Filing Date: 2011-11-22
Classification: F16C,G11B

Abstract:
1. A hydrodynamic bearing device, comprising: a fixed portion; a rotary portion that rotates with respect to the fixed portion; a lubricant that fills a microscopic gap between the rotary portion and the fixed portion; a hydrodynamic bearing portion that supports the rotary portion rotatably with respect to the fixed portion via the lubricant; a bearing seal portion formed between the rotary portion and the fixed portion, near the open end of the hydrodynamic bearing portion; and at least one annular groove, provided to the rotary portion and/or the fixed portion at the bearing seal portion, with a cross section in the shape approximated by an arc or a substantially polygonal shape, and in which the relationship between the groove width W in a direction along the surface constituting the bearing seal portion and the groove depth Dg in a direction perpendicular to the surface constituting the bearing seal portion is determined on the basis of the following relational formula: