Water closet flushing device

Claim 1

A flush control mechanism for a water closet of the type having a flushing fluid storage reservoir whose contents are transferred selectively either in part or substantially entirely to a bowl to flush the bowl comprising: valve means in said reservoir selectively operable between open and closed positions and having a negative buoyancy characteristic at least when said valve means is open, said valve means normally assuming the closed position but when operated to its open position permitting the flow of flushing fluid to said bowl, said valve means comprising an enclosed chamber having a vent aperture at its bottom which is isolated from the fluid in said reservoir when said valve means is closed to thereby permit emptying of said chamber during closure of said valve means, said valve means further including an additional fluid entry aperture in said chamber upwardly of said vent aperture for permitting entry of fluid into said chamber only when said valve means is opened, whereby said chamber has positive buoyancy when said valve means is closed but quickly becomes flooded and acquires negative buoyancy upon opening of said valve means, a manually operated means operable between a first normal position and a second flushing position, and means responsive to a momentary actuation of said manually operated means to its second position for opening said valve means only until a predetermined portion of the fluid in said reservoir which is less than the full quantity thereof has been transferred to said bowl, said last-named means being responsive to a continued actuation of said manually operated means to its second position to maintain said valve means in its open position as long as said manually operated means remains in its said second position to permit transfer of substantially all of the fluid in said reservoir to said bowl.