| 摘要 |
PURPOSE:To prevent dispersion of magnetic fluid, by forming a stepped part having a large diameter on the all part or a part of the part on a rod which is surrounded by a magnet member and yokes. CONSTITUTION:A rod 13 made of ferromagnetic material is penetrated through the inner peripheries of a magnet member 11 and yokes 12a and 12b. A stepped part 14 having a large diameter part which has the outer diameter a little smaller than the inner diameter of the yoke and the length d in the axial direction smaller than the distance D between the outside walls of yokes the oppositely arranged and the sectional shape in convex form is formed on the part of the rod 13 which opposes to the inner surfaces of the yokes 12a and 12b. The gap between the outer periphery of the stepped part 14 and the inner peripheries of the yokes 12a and 12b is filled with magnetic fluid. Since the centrifugal force F which acts onto a bottom part 15' is shielded by the inner peripheral surface of the yoke, said centrifugal force is not formed to the force for dispersing magnetic fluid. |
