Fluid dynamic bearing unit and disk drive device including the same

摘要

A first sleeve rotatably extends around a shaft. First and second flanges are fixed to the shaft. A second sleeve extending around the first sleeve is fixed thereto. A first annular member fixed to the second sleeve surrounds the first flange. A second annular member fixed to the second flange surrounds a portion of the second sleeve. A first capillary seal includes a clearance between the first flange and the first annular member. A second capillary seal includes a clearance between the second annular member and the second sleeve. Lubricant is provided in the clearances in the first and second capillary seals. The second annular member and the second sleeve are designed so that the lubricant in the 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.

主权项

1. A disk drive device comprising:
a base; a top cover fixed to the base; a rotator comprising a hub on which a disk is to be mounted, a first annular enclosure, and a shaft enclosure, the rotator being disposed between the base and the top cover; a shaft assembly comprising a shaft retained in the shaft enclosure in a freely rotatable manner relative to the shaft enclosure, a projection, a flange including an opposing surface facing with a second end face of the shaft enclosure in an axial direction, and a second annular enclosure fixed to the flange and encircling at least a part of an outer circumferential surface of the shaft enclosure, the projection comprising an opposing portion facing with a first end face of the shaft enclosure in the axial direction, and an external portion at least partially encircled by the first annular enclosure, the shaft assembly having one end fixed to the base, and another end fixed to the top cover; a pair of radial dynamic pressure generating grooves provided in at least one of an outer circumferential surface of the shaft and an inner circumferential surface of the shaft enclosure in a manner distant from each other to generate dynamic pressure to a lubrication medium; a thrust dynamic pressure generating groove provided in at least any one of the opposing portion of the projection facing with the shaft enclosure, the first end face of the shaft enclosure, the surface of the flange facing with the shaft enclosure, and the second end face of the shaft enclosure to generate dynamic pressure to the lubrication medium; a first tapered space formed between the external portion of the projection and the first annular enclosure so as to have a width in a radial direction widespread toward the top cover in the axial direction to retain the lubrication medium; and a second tapered space formed between the second annular enclosure and the shaft enclosure so as to have a width in the radial direction widespread toward the top cover in the axial direction to retain the lubrication medium, wherein: the top cover comprises a cover protrusion that is a region corresponding to the shaft assembly and protrudes toward the shaft assembly in the axial direction to form an inward recess concaved toward the shaft assembly; the top cover is fixed by causing a first fastener that passes all a way through the top cover to be engaged with a second fastener provided in the shaft assembly, at least a part of the first fastener being retained in the recess of the cover protrusion; and the second fastener is provided so as to traverse at least one of the pair of radial dynamic pressure generating grooves in the axial direction.