| 摘要 |
<p>BALL VALVE AND SEAT ASSEMBLY () A ball valve having an improved relationship between the ball and associated seat rings and an improved seat ring design for such valves. The ball is mounted for selective rotation and limited axial movement in a valve body passageway. Seat rings disposed on diametrically opposite sides of the ball about valve inlet and outlet openings each include a first ball engaging surface. A frusto-conical disc spring mounted between each seat ring and an associated valve body shoulder urge the seat rings into engagement with the ball. A reinforcing ring disposed at the forward end of each seat ring acts as a rigid bearing surface. Component sizing is such that in the assembled valve, the seat rings are slightly rotatably flexed outwardly of each other in response to the first surfaces thereof engaging the ball. At the same time, the disc springs are partially compressed while continuously urging the seat ring first surfaces into ball engagement. When the valve is closed under fluid pressure conditions, the ball is shifted downstream causing the downstream seat ring to be further rotatably flexed in the direction of ball movement. The upstream seat ring is simultaneously rotatably flexed in the same direction under the influence of its disc spring. At typical fluid operating pressures, the downstream disc spring is fully compressed to a generally flattened condition and the ball is shifted away from all contact by the upstream seat ring. In this condition, the upstream reinforcing ring prevents upstream seat ring displacement and also prevents seat ring distortion when the valve is reopened. A groove may be advantageously included in the seat ring rear faces to accommodate ease of rotational flexure.</p> |
