Bearing unit, and motor using same

Abstract

A bearing unit is provided which supports a shaft () rotatably. It includes the shaft (), a radial bearing () to support the shaft () circumferentially, a thrust bearing () to support the shaft () at one of thrusting-directional ends of the latter, a housing () having disposed therein the radial bearing () and thrust bearing () supporting together the shaft () and which is filled with a viscous fluid (), and a spacer member () disposed inside the housing () to keep a gap defined between the end face of the radial bearing () and one side of a radial projection () included in the shaft (). On the end face of the radial breading () opposite to one side of the radial projection (), there is formed a first dynamic pressure producing recess () which produces a dynamic pressure by the viscous fluid. Also, on the side of the thrust bearing () opposite to the other side of the radial projection (), there is formed a second dynamic pressure producing recess () which produces a dynamic pressure by the viscous fluid. As the shaft () rotates, the viscous fluid is circulated through the first and second dynamic pressure producing recesses () to produce a dynamic pressure between the shaft and the radial and thrust bearings, respectively. The space member () provided as above permits to control the gap between the radial projection () and first and second dynamic pressure producing recesses (), respectively, with a high accuracy.