| 摘要 |
PURPOSE:To enable increase of an amount of magnetic fluid held and to improve durability of a seal, by a method wherein a pair of annular pole pieces formed by a magnetic material are laminated on both sides of an annular magnet body, the inside and the outside of which form different poles, to form a seal body. CONSTITUTION:Annular pole pieces 2a and 2b made of a magnetic material are laminated on both sides of an annular magnet body 1 the outer and the inside of which form different poles to form a seal body 3. The inner peripheral surfaces of the pole pieces 2a and 2b are protruded toward the central part side from the inner peripheral surface of the magnet body 1. A shaft 5 is pivotally supported in a central hole 4 by means of a bearing 10. Magnetic fluid 6 is located between the inner peripheral surface of the seal body 3 and the outer peripheral surface of the shaft 5. Thus, the magnetic flux, generated on the outer peripheral surface side of the shaft 5, of the seal body 3 is distributed to a region close to the outer peripheral surface side of the shaft 5. Since the pole pieces 2a and 2b are laminated to both sides of the magnet body 1, a region where a magnetic flux is generated is spread toward both sides of the magnet body 1, and an amount of magnetic fluid 6 held is increased. This constitution improves durability of a seal. |
