Patent ID: 8599513

Claim:
A bearing mechanism comprising: a shaft portion centered on a central axis extending in a vertical direction, and including a cylindrical outer circumferential surface; a sleeve portion including a sleeve body and an annular thrust plate, and arranged to be rotatable about the central axis relative to the shaft portion, the sleeve body including a through hole in which the shaft portion is accommodated, and the thrust plate being fixed to an end portion of the sleeve body on one of upper and lower sides; and an opposing portion arranged to extend radially outward from an end portion of the shaft portion on the one of the upper and lower sides, and including a surface arranged axially opposite to an end surface of the sleeve portion on the one of the upper and lower sides with a thrust gap defined therebetween; wherein the outer circumferential surface of the shaft portion and an inner circumferential surface of the sleeve portion are arranged to together define a radial gap therebetween, the radial gap including a radial dynamic pressure bearing portion defined therein; the thrust gap includes a thrust dynamic pressure bearing portion defined therein; a seal gap is continuously defined with an outer circumferential portion of the thrust gap, the seal gap including a seal portion defined therein; the sleeve body includes: an annular surface arranged to extend radially around the central axis, and arranged opposite to the thrust plate; and an annular body projecting portion arranged to project in an axial direction inside of the annular surface; an outer circumferential surface of the body projecting portion and an inner circumferential surface of the thrust plate are arranged to be in direct contact with each other or in indirect contact with each other with another member intervening therebetween; the sleeve portion includes: a first communicating channel including a mouth portion arranged to be open in the annular surface, and arranged to be in communication with an end portion of the radial gap on another one of the upper and lower sides; and a second communicating channel defined between the sleeve body and the thrust plate, and arranged to define at least a portion of a channel extending from the mouth portion to the seal gap; the mouth portion is arranged to axially overlap with the thrust dynamic pressure bearing portion; a circulation channel including the thrust gap, the radial gap, the first communicating channel, and the second communicating channel is arranged to be in communication with the seal gap; and the circulation channel and the seal gap are filled with a lubricating oil.