Fluid dynamic bearing system for spindle motor to drive storage disk of hard-disk drive, has separator groove in sleeve or shaft and comprising axial length, where ratio between distance and axial length is larger than specific range

摘要

The system has two fluid dynamic radial bearings (20, 22) forming bearing surfaces of a shaft (12) and/or a bearing sleeve (10). The bearing surfaces are attached together by bearing groove structures (20a, 22a). The radial bearings measure opposite distance (dL) from an apex line (20b) of one of the radial bearings up to an apex line (22b) of another one of the radial bearings. A separator groove (28) is arranged in the bearing sleeve or the shaft at an axial section of a bearing space and comprises axial length (Is). Ratio between the distance and the axial length is larger than 5. An independent claim is also included for a hard-disk drive comprising a spindle motor and a writing and reading device.