United Technologies Corporation

Mark R Tardif

Gerald P Dyer

David L Chapski

According to the present invention, a fuel control has an electronic primary control for scheduling a flow of fuel to an engine in a primary mode and hydromechanical secondary control for scheduling the flow of fuel to the engine in a backup mode. The fuel control also has a tracking piston and link whose position is responsive to the HMU during the operation of the electronic primary control. The tracking piston and link effectively changes the power lever angle sensed by the HMU so that in the event of a transfer of control from the electronic primary control to the HMU, changes in the scheduled fuel flow to the engine are minimized.

Thrust bump system for fuel controls

A start, shutoff and overspeed system includes a shutoff valve which permits the flow of fuel to an engine when the pressure of the main flow of fuel received from the fuel pump at first end of the shutoff valve exceeds a bias pressure at a second end of the shutoff valve. The bias pressure at the second end of the shutoff valve is controlled by an overspeed governor valve operating in conjunction with a start solenoid valve and shutoff solenoid valve. The overspeed governor positions a spool valve in response to engine speed. During engine start the spool valve sets the bias pressure to a first pressure which closes the shutoff valve, permitting fuel flow to the engine. As speed increases the spool must transition to a second position to maintain the shutoff valve in a closed position. If the spool fails to transition, the start solenoid will set the bias pressure such that the shutoff valve will prevent engine start. The overspeed governor will transition to a third position, for an overspeed condition, which controls the bias pressure such that the engine will operate at a reduced speed. The shutoff solenoid operates to shut the engine down regardless of overspeed governor or start solenoid position.

Growing community of inventors

Andover, CT, United States of America

Mark R Tardif