Patent ID: 8294312
Filing Date: 2012-10-23
Classification: F16C,G11B,H02K

Abstract:
1. A sintered bearing impregnated with oil for a spindle motor, comprising: an inner circumference surface configured to form a hole through the bearing; an outer circumference surface opposite from the inner circumference surface in a radial direction; a top surface at an uppermost portion of the bearing in a vertical direction perpendicular to the radial direction; and a bottom surface at a lowermost portion of the bearing in the vertical direction, wherein the inner circumference surface consists of an inner circumferential upper surface, an inner circumferential lower surface, and an inner circumferential middle surface between the inner circumferential upper surface and the inner circumferential lower surface in the vertical direction, wherein at least one of the entire inner circumferential upper surface and the entire inner circumferential lower surface of the inner circumference surface of the bearing is denser than the entire inner circumferential middle surface; wherein the outer circumference surface consists of an outer circumferential upper surface, an outer circumferential lower surface, and an outer circumferential middle surface between the outer circumferential upper surface and the outer circumferential lower surface in the vertical direction, wherein at least one of the entire outer circumferential upper surface and the entire outer circumferential lower surface of the outer circumference surface of the bearing is denser than the entire outer circumferential middle surface.