| 摘要 |
PURPOSE:To improve the durability and radial rigidity, by making use of a fluorocarbon oil having a particular viscosity index as a lubricant for the bearing of a dynamic fluid bearing device. CONSTITUTION:A radial member 2 is fitted into a supporting member 1, and a radial 3 is fixed thereto. The internal periphery of the radial member 2 is provided with two-stage bearing surfaces 4, 4, i.e., upper and lower bearing surfaces. The rotating shaft 5 inserted into the radial member 2 is provided with dynamic pressure generating grooves 6, 6 respectively corresponding to bearing surfaces 4, 4 to constitute dynamic pressure radial bearings 7, 7. A dynamic pressure generating groove is provided also at the lower end face of the shaft 5 to constitute a dynamic pressure thrust bearing 8. A grease comprising a base composed of a fluoro oil or fluorocarbon oil having a viscosity index (VI) of 300-450 is used as the lubricant for bearing. The abrasion torque and radial rigidity of the bearing is proportional to the viscosity. Therefore, the higher the viscosity index of the lubricant, the better the results. Further, it is pref. that the lubricant bring about no change in the kinetic viscosity with temp. change. |
