| 摘要 |
This invention relates to a valve characterized by a hollow cylindrical body, the interior of which houses a segmented conical plug for axial movement with its apex pointed upstream. A frustoconical seat inside the hollow body also faces upstream and cooperates with similarly shaped surfaces at the base of each plug segment to cam the latter into cone-forming relation upon axial movement thereof in a downstream direction. In closed position these opposed frustoconical surfaces mate to define a continuous annular fluid tight seal. Downstream of the segmented plug subassembly is an externally ribbed tubular slide mounted for limited reciprocating movement in an axial direction back and forth between the axially spaced endwalls of an inwardly opening annular groove. Externally operated means are provided which, upon actuation, shift the slide between its extended upstream position and its retracted downstream one by exerting a suitable axially directed force against the appropriate face of the rib. Leaf springs normally biasing the segments of the cone subassembly into open position connect the latter to the adjacent upstream end of the slide. Actuation of the slide into extended position opens the valve while retraction of the slide closes same. The segments of the plug cooperate in closed position to define a fluid-tight seal and at least one of the mating surfaces is covered, coated or otherwise treated so as to effect such a seal, the same thing being true of the mating surfaces between the plug and seat therefor.
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