Patent ID: 8441759

Claim:
A fluid dynamic bearing unit comprising: a shaft; a sleeve accommodating the shaft in a rotatable manner; a first flange fixed to the shaft at a position spaced from a first end surface of the sleeve; a second flange fixed to the shaft at a position spaced from a second end surface of the sleeve; a first annular member provided at a first end of the sleeve and surrounding an outer circumferential surface of the first flange; a second annular member provided at an outer periphery of the second flange and surrounding an outer circumferential surface of the sleeve; a pair of radial dynamic pressure grooves provided in at least either one of an outer circumferential surface of the shaft and an inner circumferential surface of the sleeve and at positions spaced apart from each other in an axial direction; a thrust dynamic pressure groove provided in at least any one of a surface of the first flange facing the sleeve, the first end surface of the sleeve, a surface of the second flange facing the sleeve, and the second end surface of the sleeve; a first capillary seal formed in a gap between the first flange and the first annular member, the gap becoming wide toward an open side; a second capillary seal formed in an other gap between the second annular member and the sleeve, the other gap becoming wide toward the open side; and a lubricant filled in the radial dynamic pressure grooves, the thrust dynamic pressure groove, and the first and second capillary seals, the other gap between the second annular member and the sleeve being opened toward the first flange from the second flange.