| 摘要 |
PURPOSE:To prevent the intrusion of foreign matter from outside, by utilizing magnetic fluid as lubrication liquid for generating dynamic pressure, and as well by incoporating magnets in the peripheral section of opposing surface parts which carry out relative rotations. CONSTITUTION:Magnetic fluid is used as lubrication liquid for generating dynamic pressure, and an annular magnetic mamber 7 is attached to a bearing support member 3 such that the magnetic member 7 surrounds around the opposing surfaces of bearing members 4, 5. The magnetic member 7 is integrally incorporated with an inward projecting part 9 which extends to a position near to an annular magnetic member 8 attached to the outer peripheral surface of a rotary side bearing member 4, and further, is integrally incorporated at its lower section with an annular magnetic member 11 through permanent magnets 10 with the inward edge of the member 11 being set near to the magnetic member 8. With this arrangement, the magnetic member 7, the inward projecting part 9 and the magnetic members 8, 11 establish a closed magnetic circuit 12. |
