| 摘要 |
PURPOSE:To lengthen the life of a seal by a method wherein the magnetic fluid is caught and held by a magnetic force inbetween a dynamic pressure seal ring, equipped with a dynamic pressure generating groove, and a seal ring, being opposed thereto, and is rotated integrally with a shaft under pressing one of the seal ring. CONSTITUTION:When a shaft 2 begins to rotate, a magnetic fluid is concentrated toward the central part of a seal surface due to the pumping effect of a dynamic pressure generating groove 23a. According thereto, a sufficient lubricating film, generated by the magnetic fluid, is formed already at a very low speed (about 10-20rpm) simultaneously with the starting substantially and the seal rings 23, 25 are rotated under a noncontacting condition each other due to a fluid lubrication, therefore, the abrasion of the surfaces of the seal rings 23, 25 is very small. The resistance of the seal against the pressure during a normal operation arrives at about 5-200atm in accordance with the internal pressure at the central part of he surface of the seal, which is generated by the effect of the dynamic pressure generating groove 23a, therefore, a perfect rotary seal against the pressure of a wide range from a vacuum seal to a high-pressure seal may be effected easily. |
