Sleeve, fluid dynamic pressure bearing including the sleeve, spindle motor including the fluid dynamic pressure bearing and electronic equipment including the spindle motor

摘要

A porous oil-impregnated sleeve is used for a fluid dynamic pressure bearing. The sleeve includes an inner surface, a first axial end face, a first recessed portion, and a first dynamic pressure generating groove. The first recessed portion is positioned on the other side of a line segment, which connects one-side end portion of the inner surface with an inner end portion of the first axial end face, in a cross-section including the central axis. A bottom portion of the first recessed portion, which has the longest distance between itself and the line segment, is positioned closer to the other side than a bottom portion of the first dynamic pressure generating groove in the axial direction.

主权项

1. A porous oil-impregnated sleeve that is used for a fluid dynamic pressure bearing and extends around a central axis, the porous oil-impregnated sleeve comprising:
an outer surface; an inner surface for inserting a shaft, the inner surface opposite to the outer surface, the shaft extending in an axial direction having a central axis; a first axial end face that is positioned on a first side in the axial direction; a second axial end face on a second side opposite to the first side in the axial direction; a first recessed portion connecting the inner surface with the first axial end face; and a first dynamic pressure generating groove having a first bottom portion, the first dynamic pressure generating groove positioned on the first axial end face, wherein the sleeve is filled with a lubricant, wherein the first recessed portion is recessed from a line segment connecting an end portion of the inner surface with an inner end portion of the first axial end face, in a cross-section along the central axis, and wherein the first recessed portion has a second bottom portion farthest away from the line segment, and wherein the second bottom portion is closer to the second side than the first bottom portion of the first dynamic pressure generating groove.