| 摘要 |
PURPOSE:To cut cost by reducing the number of parts, securing the coercive force of magnetic fluid by retreating the peripheral surface of an annular pole piece to an operating member side, in comparison with the peripheral surface of an annular magnetic body. CONSTITUTION:Though a portion of the magnetic fluxes of an annular magnet body 2 passes through a fixed housing 5 side, and a portion passages through a rotary shaft 7 side, the magnetic fluxes which pass through the fixed housing 5 side shall pass the magnetic pole surface exposure parts 20 and 21 having each large magnetic resistance, and the magnetic fluxes which pass through this part reduce. Therefore, the magnetic fluxes which pass through the rotary shaft 7 side increase, and the coercive force of the magnetic fluid 8, 9 can be secured. Therefore, even if a conventional annular surrounding member is not used, the coercive force of the magnetic fluid 8, 9 can be secured, and the number of parts of a sealing device can be reduced, enabling cost reduction. |
