Patent ID: 7438476

Claim:
A hydraulic dynamic bearing comprising: a flanged shaft having a thrust ring portion and a cylinder portion, a stepped sleeve having in order a small diameter cylinder portion, a large diameter cylinder portion and a cylindrical open end portion, a presser ring inserted into and fixed to the cylindrical open end portion of the sleeve, and a lubricating oil sealed in a fine gap including a thrust gap between the flanged shaft and the stepped sleeve, wherein a thrust dynamic pressure generating groove of a herringbone pattern is provided in either of a stationary face of the stepped sleeve and a rotation face of the flanged shaft, which form the thrust gap, the depth of the groove in an inner peripheral face side up to a return point of the herringbone pattern is shallower than the depth of the groove in an outer peripheral face side, and the depth of the groove is constant in the inner peripheral face side and in the outer peripheral face side.