Spindle motor and disk drive apparatus

摘要

In a spindle motor, a shaft portion includes a columnar portion, an annular portion, and a recessed portion. A cap portion includes a flat plate portion and a projecting portion. The recessed portion includes a first side surface and a second side surface arranged radially outside the first side surface. A lower end portion of the projecting portion is arranged inside the recessed portion. The first side surface is arranged opposite to an inner circumferential surface of the projecting portion with a first region intervening therebetween. The second side surface is arranged opposite to an outer circumferential surface of the projecting portion with a second region intervening therebetween. A bottom portion of the recessed portion is arranged opposite to the lower end portion of the projecting portion with a third region intervening therebetween.

主权项

1. A spindle motor comprising:
a stationary portion including a shaft portion; and a rotating portion including a rotor magnet, and rotatably supported by the stationary portion through a lubricating oil; wherein the shaft portion includes:
a columnar portion arranged along a central axis and extending in a vertical direction;an annular portion arranged to extend radially outward from the columnar portion; andan annular recessed portion arranged to be recessed downward; the rotating portion includes:
a sleeve portion arranged opposite to the shaft portion;a tubular portion arranged to extend upward from a position radially outward of a gap between the shaft portion and the sleeve portion, and arranged opposite to the shaft portion; anda cap portion arranged near a top portion of the tubular portion; the cap portion includes:
a flat plate portion arranged to extend radially; anda projecting portion arranged radially inside the flat plate portion, and arranged to project downward from the flat plate portion; the lubricating oil is arranged in the gap between the shaft portion and the sleeve portion, the gap is arranged to be in communication with an upper seal portion defined between the annular portion and the tubular portion, and a liquid surface of the lubricating oil is located in the upper seal portion; the recessed portion includes a first side surface and a second side surface arranged radially outside the first side surface; a lower end portion of the projecting portion is arranged inside the recessed portion; the first side surface is arranged opposite to an inner circumferential surface of the projecting portion with a first region intervening therebetween; the second side surface is arranged opposite to an outer circumferential surface of the projecting portion with a second region intervening therebetween; a bottom portion of the recessed portion is arranged opposite to the lower end portion of the projecting portion with a third region intervening therebetween; and an average distance between the first side surface and the inner circumferential surface of the projecting portion is shorter than an average distance between the second side surface and the outer circumferential surface of the projecting portion and shorter than an average distance between the bottom portion of the recessed portion and the lower end portion of the projecting portion.