Fluid control valve and liner therefor

A liner for use in a fluid control valve including a housing defining an inlet opening, a substantially coaxial outlet opening and an interior cavity therebetween, a baffle extending transversely across the central portion of the cavity to define an annular passageway for the flow of fluid from the inlet opening to the outlet opening, a plurality of ribs extending from the periphery of the baffle toward the inlet opening of the housing to provide a generally frustoconical grill having a plurality of ports therein, an elastomeric, concavo-convex liner disposed on the upstream side of the baffle with its peripheral edge in sealing relation with the periphery of the baffle so as to define a control chamber between the liner and the baffle, the inner surface of said grill and the outer surface of said liner being in confronting relation, the baffle having a central protuberance projecting toward the liner upon which the liner is draped during inversion of the liner, and means for decreasing and increasing the fluid pressure in the control chamber, a decrease of the pressure in the chamber causing the liner to invert and to roll along the frustoconical grill from a closed position where all of the ports are covered by the liner to positions where progressively greater areas of the ports are exposed thereby permitting controlled and progressively increasing fluid flow through the ports and through the annular passageway, an increase in the pressure of the chamber causing reverse movement of the liner, said liner having an outer surface which with the valve in its closed position is spaced apart from the inner surface of said grill, said outer surface being conical over a portion of its area of confrontation with the inner surface of said grill adjacent the periphery of said baffle.