Patent ID: 8584441

Claim:
A fuel metering system for supplying fuel to a load, comprising: a gas turbine engine controller adapted to receive throttle input commands and configured, in response thereto, to supply hangar position commands; a variable displacement piston pump including an adjustable hangar that is movable to a plurality of positions, the variable displacement piston pump configured to receive a drive torque and, upon receipt of the drive torque, to supply fuel to the load at a flow rate and a discharge pressure that are dependent on drive speed and adjustable hangar position; a hangar actuator coupled to receive the hangar position commands and configured, in response thereto, to move the adjustable hangar to the commanded position, the hangar actuator comprising: a first piston engaging the adjustable hangar and coupled to receive a first force, the first piston responsive to the first force to supply a hangar position force to the adjustable hangar; a bias spring engaging the first piston and supplying the first force thereto; a second piston engaging the adjustable hangar and coupled to receive fuel at the discharge pressure, the second piston configured to supply a pressure control force to the adjustable hangar that opposes the hangar position force; and an electromechanical actuator engaging the bias spring and coupled to receive the hangar position commands, the electromechanical actuator configured, in response to the hangar position commands, to set the bias spring to thereby control the first force that is supplied to the first piston.