| 摘要 |
PROBLEM TO BE SOLVED: To improve the sealing efficiency of a member turning around a support shaft by including a magnetic field forming member and a magnetizable member positioned adjacent thereto, and providing the magnetizable member with a part increased in thickness in the direction parallel to the shaft with increase in its distance from the shaft. SOLUTION: A magnetic seal 132 includes a main body, that is, a magnet 117. The magnet 117 is like the form of a washer having a flat parallel surface 121 and a cylindrical outer surface 123, and the outer surface 123 is concentric with a cylindrical bore 125 of the magnet 117. The seal 132 further includes a shunt, that is a magnetic field forming device 142, and the forming device 142 has a circular outer surface 150 concentric with the cylindrical bore 152 of the forming device. The thickness 154 of the forming device 142 is reduced by the bore 152 and the surface 156 of the forming device 142 having a suitable form decreases the thickness. For example, the thickness 154 of the forming device 142 is constant at a part of the forming device 142 and decreased at the radial distance of the part of a slope of the forming device 142. When the thickness TOS is two times of the thickness of TIS sealing efficiency is remarkably improved. |
