Patent ID: 8922943

Claim:
A fluid dynamic bearing apparatus comprising: a shaft arranged to extend in a vertical direction with a central axis provided in a center thereof; a thrust washer arranged to project radially outward from an outer circumferential surface of the shaft; and a rotating member supported to be rotatable with respect to the shaft and the thrust washer; wherein the rotating member includes: a cylindrical portion arranged radially opposite to the shaft with a first radial gap located therebetween, and axially opposed to the thrust washer with an axial gap intervening therebetween; and a flat plate portion arranged to extend radially outward from a vicinity of an upper end portion of the cylindrical portion, and including an inner circumferential surface arranged radially opposite to an outer circumferential surface of the thrust washer with a second radial gap arranged therebetween, the second radial gap including a pumping gap; the second radial gap and the axial gap are in communication with each other, and are filled with lubricating oil; at least one of the outer circumferential surface of the thrust washer and the inner circumferential surface of the flat plate portion includes a pumping groove arranged to push a portion of the lubricating oil which is present in the second radial gap in a direction of the axial gap; and the axial gap includes: a thrust gap; and an oil buffer arranged radially outward of the thrust gap, and having an axial dimension greater than that of the thrust gap.