Patent ID: 7648281
Filing Date: 2010-01-19
Classification: F16C

Abstract:
1. A fluid dynamic bearing comprising: a shaft member; a bearing member spaced apart from the shaft member by a first gap; a flange disposed on the shaft member, the flange having a first large diameter portion and a first small diameter portion on an outer periphery thereof and in this order from a second axial side toward a first axial side of the shaft member opposite to the second axial side; an annular member fixed to the bearing member, the annular member having a second large diameter portion and a second small diameter portion on an inner periphery thereof, the second large diameter portion and the second small diameter portion facing the first large diameter portion and the first small diameter portion, respectively; and a lubricating fluid, wherein a first axial side-end of the bearing member and a second axial side-end of the flange define a second gap therebetween, the second gap communicating with the first gap; the flange and the annular member define a third gap therebetween; the first axial side-end of the bearing member and a second axial side-end of the annular member define a fourth gap therebetween; the annular member faces a fifth gap on an outer periphery thereof, the fifth gap communicating with the second and third gaps through the fourth gap and communicating with a vent ensuring ventilation toward an outside of the fluid dynamic bearing; and the lubricating fluid fills the first to fifth gaps continuously so as to have a fluid surface thereof located in the third and fifth gaps.