Staged bearing surface compliance for hydrodynamic fluid bearing

Abstract

A hydrodynamic fluid bearing includes a pivoted shoe which can tilt in response to the hydrodynamic fluid forces generated between the bearing surfaces, and a locally conformable bearing layer attached to the shoe facing the opposing bearing surface. The pivoted shoe can pivot to conform to changes in the pitch of the opposing bearing surface and can tilt to the correct slope to generate the hydrodynamic supporting fluid wedge, and can also conform to the shape of the opposing bearing surface if it becomes thermally distorted or 'dished'. The compliant layer at the top surface of the shoe can conform to smaller area bearing irregularities, and in addition, can locally conform under hydrodynamic forces to assume the ideal configuration to generate the optimum hydrodynamic wedge. The support on which the pivoted shoe is mounted can itself be pivoted on a gimbal ring to provide large area compliance with the bearing surface to follow, if necessary, precession or other large scale runout of the bearing surface. Each stage of the compliant support can be designed to give the stiffness and damping best suited for that stage of support.