Patent ID: 8284513

Claim:
A bearing mechanism comprising: a fixed shaft arranged to extend in a vertical direction along a central axis; a sleeve portion including the fixed shaft arranged therein, and arranged to rotate with respect to the fixed shaft, the fixed shaft and the sleeve portion together defining a radial gap therebetween; a first thrust portion arranged to spread radially outward from the fixed shaft, and including an upper surface arranged opposite to a lower surface of the sleeve portion, the lower surface of the sleeve portion and the upper surface of the first thrust portion together defining a first thrust gap therebetween; a cover portion attached to the sleeve portion, and arranged opposite to an outside surface of the first thrust portion; and a lubricating oil; wherein the sleeve portion includes a communicating channel extending upward from a bottom thereof to be in communication with an upper portion of the radial gap; the outside surface of the first thrust portion and the cover portion together define a tapered gap therebetween, the tapered gap gradually increasing in width in a downward direction, and including an interface of the lubricating oil therewithin; the lubricating oil is arranged in the radial gap, the communicating channel, the first thrust gap, and the tapered gap; the radial gap includes a radial bearing portion arranged to generate a radial dynamic pressure on the lubricating oil through first dynamic pressure grooves; the first thrust gap includes a first thrust bearing portion arranged to generate a thrust dynamic pressure on the lubricating oil through second dynamic pressure grooves; the lower surface of the sleeve portion includes an outer circumferential portion arranged radially outward of the first thrust gap, the outer circumferential portion including a lower end opening of the communicating channel defined therein; the outside surface of the first thrust portion includes either a substantially conical surface which gradually decreases in distance from the central axis in the downward direction, or a substantially cylindrical surface extending in parallel or substantially in parallel with the central axis; a radially outermost portion of the outside surface of the first thrust portion is arranged closer to the central axis than a wall surface in plan view; the tapered gap is arranged closer to the central axis than a radially outermost point of the wall surface; and the outer circumferential portion and the cover portion together define a guide gap therebetween to direct the lubricating oil from the lower end opening in a direction of the tapered gap and toward the first thrust gap.