Two stage fuel metering system for gas turbine

摘要

A novel two-stage fuel metering system is disclosed for metering the flown of fuel between a fuel supply and a combustion chamber of an engine the fuel in the supply being pressurized by a pump and delivered to the combustion chamber. The fuel metering system includes a first primary passageway for receiving fuel from a fuel supply and a second primary passageway fluidically connected to the first passageway for delivering fuel to a combustion chamber. A servo chamber is fluidically connected to both the first and second primary passageways and a servo valve is disposed between the first passageway and the servo chamber to selectively regulate the flow of fuel entering the chamber. A metering valve is disposed between the first and second passageways to regulate the flow of fuel from the first passageway to the second passageway the metering valve being biased to a closed position that obstructs the fuel flow. The metering valve further includes an actuating surface disposed in the chamber and responsive to the pressure in the chamber, wherein the metering valve is adapted to move from the closed position toward an open position in response to sufficient fuel pressure in the chamber. A conduit fluidically connects the chamber to the second passageway to restrict the flow of fuel therethrough to an upper limit.