US Patent 7284542 Tapered toroidal flow control valve and fuel metering device

A fuel metering device utilizing a tapered toroid shaped flow control valve placed between a pressure chamber and a discharge space, with a seal, fixedly mounted to the valve, fluidically isolating the pressure chamber from the discharge space when the valve is in its closed position, and a rotary actuator capable to move the toroidal valve about a fixed fulcrum to deliver a precisely metered amount of a preferably gaseous fuel to an internal combustion engine. The device further comprises a biasing spring, to close the valve when the rotary actuator is de-energized, and a rotary position sensor, which, in co-operation with the rotary actuator enable accurate angular positioning of the valve.