| 摘要 |
PURPOSE:To improve the pressure resistance of a sealed portion by providing a cylindrical magnet, two outside shielding plates provided at both ends in the axial direction and each constituted of a circular plate made of a nonmagnetic material, a magnetic fluid, and an inside shielding plate constituted of a circular plate made of a nonmagnetic material. CONSTITUTION:When a pressure difference is generated between the right and left of a sealing device 40 and the pressure at the left side is made larger than that at the right side, for example, a magnetic fluid 44 existing in the circular space at the left tends to be moved to the right side. However, a mass difference is generated between the magnetic fluid 44 in the left side space and the magnetic fluid 44 in the right side space, thus the centrifugal force has a force moving the magnetic fluid 44 from the right side to the left side. In addition, the magnetic force serves as a holding force, and the movement of the magnetic fluid 44 is negated. That is, the magnetic fluid 44 is not moved practically between the right and left circular spaces and firmly held at the holding portion. |
