Patent ID: 8920033

Claim:
A fluid dynamic bearing comprising: a bearing bush ( 10 ) having a bore ( 12 ) therethrough concentric with a rotation axis, said bearing bush defining an annular portion of a stationary bearing surface area surrounding an opening of said bore in said stationary bearing surface area; a rotatable hub ( 26 ) having a hub bore concentric with said rotation axis and communicating with the bore of said bearing bush, said rotatable hub defining an annular portion of said rotatable bearing surface area surrounding an opening of said hub bore therein; a shaft ( 11 ) affixed to said rotatable hub and rotatably accommodated within the bore of the stationary bearing bush; and an axially facing stationar bearing surface area separated by a fluid bearing gap from an opposed axially facing bearing surface area rotatable on a rotation axis relative to the stationary bearing surface area, said stationary bearing surface area having a plurality of surface patterned grooves adapted to induce hydrodynamic fluid pressure within the fluid bearing gap; said plurality of surface patterned grooves being formed with spiral-shaped symmetry whereby each groove curves radially between inner and outer boundaries of the annular portion of said one of said stationary and rotatable bearing surface areas and is adapted to induce a hydrodynamic pressure distribution within said fluid bearing gap, each groove of a at least one group of said surface patterned grooves having one end engaging a portion of said inner boundary defined by the circumferential edge of a bore opening, the other end of each groove of said at least one group of surface patterned grooves defining a portion of said outer boundary, one or more other grooves of said surface patterned grooves being interrupted or terminating between said inner and outer boundaries.