Fluid dynamic bearing and a storage disk drive with a spindle motor having the fluid dynamic bearing

Abstract

A hydrodynamic bearing having a bearing sleeve, a rotational shaft supported for rotation by the bearing sleeve, a bearing gap formed between the bearing sleeve and the rotational shaft, lubricating oil contained within the bearing gap, at least one hydrodynamic pressure-generating groove formed at an inner peripheral surface of the bearing sleeve; and an oil reservoir. The oil reservoir includes a gradually expanding section located in a position distanced from the pressure-generating groove and a first larger inner diameter, section located adjacently to the gradually expanding section. A second larger inner diameter section is located immediately below an opening of the bearing sleeve and an oil-repelling peripheral groove located between the first larger inner diameter section of the oil reservoir and the second larger inner diameter section. The oil-repelling peripheral groove and the second larger inner diameter section constitute an oil scatter and leakage prevention mechanism of the fluid dynamic bearing.