Patent ID: 7033078
Filing Date: 2006-04-25
Classification: F16C,G02B,G11B,H02K

Abstract:
1. A hydrodynamic bearing assembly, comprising: a column shaft having an outer surface parallel to an axis; a hollow cylindrical sleeve having an inner surface rotatably arranged around the outer surface of said shaft; and a radial bearing for generating a radial dynamic pressure due to a relative rotation between said sleeve and said shaft to keep them away from each other; wherein either one of the outer surface of said shaft and the inner surface of the sleeve includes at least one annular groove perpendicular to the axis, the annular groove is such that a depth ratio defined by the depth of the annular groove relative to a diameter of the surface is approximately 0.01 or less, and a width ratio defined by the width of the annular groove relative to a length of the bearing assembly is approximately 0.2 or less.