Patent ID: 7422370
Filing Date: 2008-09-09
Classification: F16C,G11B,H02K,Y10T

Abstract:
1. A fluid dynamic bearing system comprising: a stationary sleeve; a rotating shaft axially disposed through the sleeve; a journal gap between the shaft and sleeve, said gap defined by first and second interfacial surfaces between the shaft and sleeve; at least one set of fluid dynamic grooves formed on the first interfacial surface of the journal gap; and at least one step defined on the second interfacial surface of the journal gap and extending in a non-axial direction, wherein the at least one step reduces the journal gap in a localized region, and wherein the sleeve and shaft are operable to move axially relative to each other during operation by, at least in part, hydraulic force generated by interaction of the at least one set of fluid dynamic grooves and the step with a fluid disposed in the gap, such that the at least one step moves away from an apex of the at least one set of fluid dynamic groove; such that the hydraulic force maintains the stationary sleeve and the rotating shaft in a substantially fixed relative axial position with respect to each other during operation despite viscosity changes in the fluid which would otherwise cause the stationary sleeve and the rotating shaft to move from the substantially fixed axial position.