Patent ID: 6914358
Filing Date: 2005-07-05
Classification: F16C,H02K

Abstract:
1. A spindle motor comprising: a shaft; a unilaterally open-ended cylindrical bearing member having a bearing hole into which said shaft is inserted and a closed-end surface axially opposing the inserted-end face of said shaft; a rotor fixed to one end of said shaft for rotation together therewith, and having a circular flat face extending radially outward from the circumferential surface of said shaft; a serial bearing clearance filled with oil, formed in between the inner peripheral surface of said bearing hole in said bearing member, and the circumferential surface of said shaft, and in between the end face along the open end of said bearing member, and the flat face of said rotor; a thrust bearing section provided with dynamic-pressure-generating grooves contoured to impart on the oil pressure acting radially inward during rotation of said rotor, and formed in between the end face along the open end of said bearing member and the flat face of said rotor; a radial bearing section provided with dynamic-pressure-generating grooves contoured to impart on the oil pressure acting inward from both ends axially during rotation of said rotor, and formed in between the inner peripheral surface of said bearing hole and the circumferential surface of said shaft; and a communicating passage formed in said bearing member so that one end of said communicating passage opens on said thrust bearing section radially inward with respect to said dynamic-pressure-generating grooves therein and so that both axial ends of said bearing clearance where said clearance if formed in between the inner peripheral surface of said bearing hole and the circumferential surface of said shaft communicate through said passage, for balancing pressure within said bearing clearances.