| 摘要 |
The disclosed valve comprises a casing (1), a seat (2), a swivelling flap (4) with a convex rear surface (10) which generates a lift force that presses the flap (4) against a stop piece (21). In order to ensure that the flap (4) presses against the stop piece (21) and to prevent the flap (4) from hitting the convex rear surface (10) when it is in the open position, grooves have been inserted at the point (9) of outflow, in the direction of the flap in this position and along the longitudinal axis of the casing. Inside the grooves, vortexes are created, producing a vacuum that increases the pressure of the flap (4) against the stop piece (21). When the flap is in the open position, the grooves (28) may have a base which is either parallel to the longitudinal axis (17) of the casing (1), or inclined downwards. The stop piece (21) can be arched and streamlined for the flow. Grooves may also be placed on the upper surface of said stop piece.
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