Multi-stage support element for compliant hydrodynamic bearings

A compliant hydrodynamic fluid film bearing, comprising:

• first and second relatively moving members defining therebetween a gap;
• a bearing assembly disposed in said gap and attached to said first member, said second member rotating relative to said bearing assembly and generating a hydrodynamic fluid film between said bearing assembly and said second member for dynamic support of one member by the other member;
• said bearing assembly including a smooth flexible thin bearing sheet and a resilient support element underlying and supporting said bearing sheet in bearing relationship to said second member;
• said support element deflecting under the load exerted by said hydrodynamic fluid film to present an inclined bearing surface of said bearing sheet to the relatively moving surface of said second member;
• said support element being formed of at least two separate foil members, stacked one over the other;
• each of said foil members having raised resilient projections which provide the resilient, compliant support for said bearing sheet, said projections being distributed across said foil members in a similar pattern on both foil members such that said projections are aligned perpendicularly beneath the plane of the overlying bearing sheet in operation;
• said projections on said other foil member being smaller, stiffer, and stronger than said projections on said one foil member;
• whereby said projections constitute a staged parallel spring array for supporting said bearing sheet on said one foil member at low speed, low load conditions wherein greater compliance is desired, and during high-speed, high-load conditions said one foil member projections deflect to the level of said other foil member projections which are stiffer than said one foil member projections and, with said other foil member projections, support the increased load with increased stiffness and damping.