| 摘要 |
PURPOSE:To prevent outflow and flying of magnetic fluid to the outer peripheral side owing to rotation of a rotary shaft and to reduce the occurrence of a problem on contamination of surroundings. CONSTITUTION:A barrier 10 protruded further outward from the outer surface of a pole piece is formed on a pole piece 1 and a magnetic fluid holding surface 12 is formed in a portion extending from the tip surface 4 of the pole piece 1 through the outer surface to the barrier 10. Magnetic fluid 7 is held between the tip surface 4 of the pole piece 1 and a magnetic body 6. The barrier 10 is formed of a material with which the contact angle of the magnetic fluid 7 is higher than that of the magnetic fluid with the pole pieces 1 and 2, and this constitution prevents outflow and flying of the magnetic fluid 7 to surroundings. Further, a prevention effect is ensured by forming a stepped part 13 at the vicinity of the barrier 10. |
