Patent ID: 8107195
Filing Date: 2012-01-31
Classification: F16C,G11B,Y10T

Abstract:
1. A fluid dynamic bearing unit comprising: a shaft; a first sleeve accommodating at least a portion of the shaft and being rotatable relative to the shaft; a first flange fixed to the shaft and spaced from a first end surface of the first sleeve; a second flange fixed to the shaft and spaced from a second end surface of the first sleeve opposite to the first end surface thereof; a second sleeve fixed to the first sleeve and extending around the first sleeve; a first annular member fixed to a first end of the second sleeve and surrounding the first flange; a second annular member fixed to the second flange and surrounding a portion of the second sleeve; a pair of radial dynamic pressure grooves provided in at least one of an outer circumferential surface of the shaft and an inner circumferential surface of the first sleeve and spaced in an axial direction; a first thrust dynamic pressure groove provided in at least one of the first flange and the first end surface of the first sleeve; a second thrust dynamic pressure groove provided in at least one of the second flange and the second end surface of the first sleeve; a first capillary seal including a first clearance between the first flange and the first annular member and having a first open end, wherein the first clearance at a first position is wider as the first position moves toward the first open end; a second capillary seal including a second clearance between the second annular member and the portion of the second sleeve and having a second open end, wherein the second clearance at a second position is wider as the second position moves toward the second open end; and lubricant provided in the radial dynamic pressure grooves, the first and second thrust dynamic pressure grooves, and the first and second capillary seals; wherein the second annular member and the second sleeve are designed so that the lubricant in the second clearance in the second capillary seal can be viewed from a point in a radial position which is outward of the second sleeve as seen in an axial direction.