| 摘要 |
PURPOSE:To increase a sealing effect by a method wherein a rotary shaft is sealed by utilizing a magnetic force, restricting the magnetic fluid, a high dynamic pressure, generated by rotation, and a centrifugal force, generated in the magnetic fluid. CONSTITUTION:When a rotary shaft 1 begins to rotate, a magnetic fluid is concentrated to the central part of a sealing surface by the pumping effect of each dynamic pressure generating grooves 26, 30. According thereto, a sufficient lubricating film, generated by the magnetic fluid 22, is formed already at a very low speed (10-20rpm) simultaneously with the starting substantially. The resistance of the seal against a pressure during a normal operation arrives at 5- 200atm substantially in accordance with the hydraulic pressure at the central part of the sealing surface, which is generated by the effect of the dynamic pressure generating grooves 26, 30, therefore, a perfect dynamic pressure seal against the pressure of a wide range from a high vacuum seal to a high-pressure seal may be guaranteed. Furthermore, the magnetic fluid is restricted by the magnetic force perfectly under a high-speed rotation, therefore, oil will never be dispersed and a circumstance will never be spoiled in different from the case wherein a conventional bearing is employed. |
