| 摘要 |
PURPOSE:To dispense with any pressure rise at the times of starting and stopping, by installing a swell of a taper or a step on a sealing surface of either a ring or a runner or both, in the case of a noncontact type static seal consisting of the resting ring and the rotating runner. CONSTITUTION:A fluid in a seal clearance 9 flows in the same circumferential direction as a direction of rotation owing to its viscosity simultaneously with rotation of a runner 3, and dynamic pressure 13 is generated inside the seal clearance 9 by this flow and form of a sealing surface 16. When there is not differential pressure in the seal, the clearance 9 between sealing surfaces 16 is set up so as to cause power to be produced by this dynamic pressure 13 to be balanced with dead load of a ring 4. The smaller in the clearance 9, the larger in the dynamic pressure, so that the ring 4 is uplifted and restored to the original clearance 9. In contrast to this, the larger in the clearance 9, the smaller in the dynamic pressure, so that the ring 4 goes down with its own weight, returning to the original clearance 9. Thus, the clearance 9 between sealing surface 16 is kept constant. Therefore, even if there is no differential surface at the times of starting and stopping of a rotary machine, sealing can be done.
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