Patent ID: 7576947
Filing Date: 2009-08-18
Classification: F16C,G11B,H02K

Abstract:
1. A fluid dynamic pressure bearing device, comprising: a shaft member; a bearing member that supports the shaft member and allows relative rotation between the shaft member and the bearing member; a seal member with a top wall, the top wall having a protrusion hole through which an upper end portion of the shaft member protrudes, the seal member being arranged to cover an upper end portion of the bearing member; a closure member that closes a lower end portion of the bearing member; and a bearing gap including dynamic pressure grooves formed between the shaft member and the bearing member, and between the shaft member and the closure member, respectively; wherein: a radial dynamic pressure groove is formed in either an outer circumferential surface of the shaft member or an inner circumferential surface of the bearing member, the radial dynamic pressure groove generating a dynamic pressure force that receives a load in a radial direction; a first thrust dynamic pressure groove is formed in either a downward-facing surface of the shaft member or an upper surface of the closure member, the first thrust dynamic pressure groove generating a dynamic pressure force that receives a load in a thrust direction; a lubricant holding gap is formed between an upper end surface of the bearing member and an inner surface of the top wall of the seal member; a first capillary seal portion is formed between an outer circumferential surface of the bearing member and an inner circumferential surface of the seal member, the first capillary seal portion forming a cross-sectionally tapered shape that widens progressing downward; a second capillary seal portion is formed between the outer circumferential surface of the shaft member and an inner circumferential surface of the protrusion hole; and the bearing gap, the second capillary seal portion, the lubricant holding gap, and the first capillary seal portion are in communication with each other, and occupied by lubricant.