Patent ID: 7196868

Claim:
A hydrodynamic bearing comprising: (a) a cabinet including a base and a cover; (b) a fixed shaft including a first end having a mounting part fixed on one of said base and said cover, and a second end at the opposite side of said fixed shaft; (c) a flange in an annular shape, with said second end of said fixed shaft inserted into its inside, and fixed on said second end of said fixed shaft, thereby being substantially perpendicular to the axial direction of said fixed shaft; (d) a sleeve, when said fixed shaft is inserted into its inside, allowed to revolve around said fixed shaft and placed where a hollow provided on an inner surface of said sleeve is in the vicinity of a surface of said flange; (e) a thrust plate in an annular shape and fixed on one of opening ends of said sleeve, thereby being placed close to said flange when said second end of said fixed shaft is inserted inside said thrust plate; and (f) a lubricant with which the whole of radial dynamic pressure grooves provided at least one of a side of said fixed shaft and an inner surface of said sleeve, and the whole of thrust dynamic pressure grooves provided at least one of a surface of said flange, a surface of said hollow of said sleeve, and a surface of said thrust plate, are filled and covered; wherein: (g) a circulation hole connecting spaces over and under said flange to each other is provided, and said lubricant circulates on surfaces of said flange through said circulation hole; and (h) a vent connecting spaces around a joint between said fixed shaft and said flange to each other is provided inside said fixed shaft.