SPINDLE MOTOR AND DISK DRIVE APPARATUS

摘要

A spindle motor includes a stationary portion and a rotating portion. The stationary portion includes a shaft and the rotating portion includes a sleeve portion, a hub, a magnet, and a cap. The sleeve portion is arranged opposite to the shaft. The hub is made of metal, and includes a top plate portion extending radially outward from the sleeve portion, and an outer tubular portion extending downward from an outer edge of the top plate portion. The magnet is fixed to the outer tubular portion and is arranged opposite to the stator. The cap is made of metal, and includes an annular plate-shaped portion fixed to an upper surface of the top plate portion. The magnet has a coefficient of thermal expansion greater than that of the hub. The cap has a coefficient of thermal expansion greater than that of both the hub and the magnet.

主权项

1. A spindle motor comprising:
a stationary portion including a stator; and a rotating portion rotatably supported by the stationary portion through a lubricating oil; wherein the stationary portion includes a shaft arranged along a central axis extending in a vertical direction; the rotating portion includes:
a sleeve portion including an inner circumferential surface arranged opposite to an outer circumferential surface of the shaft;a hub made of metal, and including a top plate portion extending radially outward from the sleeve portion, and an outer tubular portion extending downward from an outer edge of the top plate portion;a magnet made of bonded neodymium fixed to the outer tubular portion, and arranged opposite to the stator with a gap intervening therebetween; anda cap made of metal, and including an annular plate-shaped portion fixed to an upper surface of the top plate portion; the magnet has a coefficient of thermal expansion greater than a coefficient of thermal expansion of the hub; and the cap has a coefficient of thermal expansion greater than both the coefficients of thermal expansion of the hub and the magnet.