| 摘要 |
A valve including an at least partially spherical valve control member and a valve seat where the valve control member is rotatable within a valve housing to obturate and to open at least one opening of the housing by bringing a passage through the valve control member out of and into alignment with the opening. The valve seat includes a radially outer disc portion which lies in a plane transverse to an axis of the opening and a radially inner generally frusto-conical, annular extension free at its narrower-diameter end. The frusto-conical extension is adapted to lie in the opening with a larger-diameter end inward of the housing, and to make substantially a line contact with an at least partially spherical surface of the valve control member when the latter obturates the opening. The disc portion is supported by the housing in such manner that a radially inner region of the disc portion and the frusto-conical extension are capable of flexing in response to movement of the valve control member outward and inward of the housing. The line contact moves relative to the frusto-conical extension but is at all times at a position where the radially outer disc portion is supported by the housing. |
