Patent ID: 8449191

Claim:
A bearing structure comprising: a rotating body including a rotating shaft; a sleeve having the rotating shaft inserted therein such that the rotating shaft is rotatable with respect to the sleeve; a sleeve support portion having a bottom, being substantially tubular, extending in an axial direction, and arranged to support the sleeve; and a base portion connected to an axial end of the sleeve support portion; wherein the sleeve support portion includes: an opening portion arranged to receive the rotating shaft; a cavity portion arranged to contain the sleeve; and a plurality of ribs provided on an inner surface of the cavity portion and extending in the axial direction, the ribs being spaced from each other in a circumferential direction centered on the rotating shaft; wherein each of the ribs includes an axial contact surface arranged to contact at least a portion of a radially outer surface of the sleeve; the ribs include a plurality of different types of ribs, each of the plurality of different types of ribs having differently positioned ones of the axial contact surfaces on an axially opening portion side thereof; and at least one of the ribs is arranged such that an axially upper portion of its axial contact surface is positioned axially above a center of gravity of the rotating body and at least another one of the ribs is arranged such that its axial contact surface is positioned axially below the center of gravity of the rotating body.