Dynamic pressure bearing, spindle motor using dynamic pressure bearing, and rotary device having the spindle motor as driving source

摘要

A spindle motor has a rotor, a stator and a dynamic pressure bearing for supporting the rotor for rotation relative to the stator. The dynamic pressure bearing comprises a rotational shaft mounted for undergoing rotation and having a thrust bearing portion and a radial bearing portion. A bearing member rotatably supports the rotational shaft and has a closed end forming a small diameter cylinder portion for receiving the radial bearing portion of the rotational shaft and an open end forming a large diameter cylinder portion for receiving the thrust bearing portion of the rotational shaft such that first gaps for receiving a lubricating oil are formed between the rotational shaft and the bearing member. A thrust pressure member is connected to the bearing member to form a capillary seal between the rotational shaft and the open end of the bearing member and to form second gaps between the thrust pressure member and the rotational shaft for receiving a lubricating oil. An oil receiving groove is formed in at least one of the thrust pressure member and the rotational shaft for receiving a lubricating oil.