| 摘要 |
<p>The stop or control valves used to interrupt or control fluids flowing through conduits, comprise a housing provided with inlets and outlets as well as an obturation member which can be in the shape of a cylindrical or frustoconical key, of a sphere or a flat slide valve. The obturation member comprises an inlet or recess, or it shows only a part of said geometrical shapes and is arranged so as to connect the inlet with the outlet in the open state and to block the path between the two passages in the closed state. These passages are provided with a waterproof seal, for instance a bellows seal, the effect of which is increased in case of an operating pressure increase. The known stop or control valves have the disadvantage that the seal has an unfavorable action on the liquid flow, that the prestress on the obturation member is partially low and that the seal is not free from wake space. Moreover, the bellows seal is pressure-sensitive and, consequently, can be damaged by too high pressures. In order to avoid those drawbacks an elastic sealing sleeve (5) provided with an arched section (6) is positioned in a part of the inlets and outlets; the convex part thereof is directed towards the axis of the flow conduit and bears on one side on the obturation member and on the other side on a shouldering, a stop or similar. The arched section (6) can bear, in case of an overpressure, on the wall of the housing (3).</p> |
