Patent ID: 8005603

Claim:
A fuel control system for a gas engine, comprising: an air/fuel mixing venturi which supplies an air/fuel mixture to a gas fuel engine, the venturi having a reduced area throat, an air supply inlet to the venturi, and a plurality of gas fuel injection ports at the venturi throat, whereby gas flows through the injection ports to the venturi throat as a function of flow of air through the air supply inlet; a fuel metering assembly which controls the supply of gaseous fuel to the gas fuel injection ports of the air/fuel mixing venturi; an air/fuel ratio control module which establishes a first differential pressure setpoint between gaseous fuel and air inputs to the air/fuel mixing venturi, the first differential pressure setpoint being adjusted as a function of an engine operating parameter; a first differential pressure sensor which detects a differential pressure between the actual pressure of fuel supplied to a fuel inlet of an air/fuel mixing venturi and the air inlet pressure to an air inlet of the venturi; and a first pressure control module associated with the air/fuel ratio control module and first differential pressure sensor which controls the fuel metering assembly to vary the injection pressure of gaseous fuel supplied to the air/fuel mixing venturi based on a detected difference between the first differential pressure setpoint and the detected differential pressure.