Patent ID: 7360950
Filing Date: 2008-04-22
Classification: F16C,G02B,G11B,H02K

Abstract:
1. A hydrodynamic bearing assembly, comprising: a radial bearing including a column shaft having an outer surface parallel to a longitudinal axis of said shaft, and a hollow cylindrical sleeve having an inner surface rotatably arranged around the outer surface of said shaft, said radial bearing for generating a radial dynamic pressure due to a relative rotation between said sleeve and said shaft; and a thrust bearing including a thrust plate formed or secured onto either one of said shaft and said sleeve, and a thrust opposing surface formed or secured onto the other one of said shaft and said sleeve, said thrust bearing for generating a thrust dynamic pressure due to the relative rotation between said thrust plate and said thrust opposing surface; wherein said thrust bearing is a pump-out type, and conducts the fluid in the thrust bearing in the direction from the axis to circumference, wherein at least one longitudinal groove is formed on either one of the outer surface of said shaft and the inner surface of said sleeve, the longitudinal groove extending parallel or inclined to the axis between both ends along the axis, and wherein the at least one longitudinal groove has a depth ratio defined by a depth of the groove to a diameter of said shaft is within the range from approximately 0.0001 to not more than 0.0001.