Patent ID: 6505968
Filing Date: 2003-01-14
Classification: F16C,G11B,H02K

Abstract:
A hydrodynamic bearing assembly, comprising:a pair of relatively moving members separated by a fluid-filled gap, the hydrodynamic bearing assembly having a stiffness defined by the size of the fluid-filled gap, the pair relatively moving members including a stator member having a hydrodynamic surface and a rotor member having a surface facing the stator member hydrodynamic surface, wherein the stator member includes a thrust plate and the stator member hydrodynamic surface includes at least one thrust surface upon the thrust plate; an electrically activated means for changing the size of the fluid-filed gap to change the stiffness of the bearing, the electrically activated means includes at least one piezoelectric member located within the thrust plate so that when the at least one piezoelectric member expands the at least one thrust surface moves closer to the facing rotor member; and a control system for receiving a signal signifying a rotational speed of the bearing assembly, wherein the control system sends a signal to the electrically activated means to increase the size of the fluid-filled gap when the rotational speed of the bearing assembly increases.