Patent ID: 11891959
Assignee: ROLLS-ROYCE PLC
Field: Engines, pumps, turbines (Mechanical engineering)
Classification: CPC F | IPC F

Claim 16:
17. A fuel control system for a gas turbine engine, the fuel control system comprising:
a fuel metering valve comprising:
a valve body configured to adjust a flow of a fuel between a supply line and a delivery line;
a valve actuating unit configured to move the valve body, wherein the valve actuating unit is electrically powered; and
a valve detent configured to retain the valve body in a current body position of the valve body upon loss of electrical power to the valve actuating unit;

a pressure raising and shut-off valve (PRSOV) fluidly connected to the delivery line and comprising a valve member movable between an open position and a closed position, wherein, in the open position, the valve member allows the flow of the fuel from the delivery line to an engine line that is in fluid communication with one or more burners of the gas turbine engine and wherein, in the closed position, the valve member prevents the flow of the fuel from the delivery line to the engine line; and
a shutoff effector comprising:
a first stage unit that is electrically powered; and
a second stage unit fluidly connected to the PRSOV and controlled by the first stage unit, wherein the second stage unit is configured to actuate the valve member of the PRSOV, the second stage unit comprising a spool movable between a first spool position and a second spool position, wherein, in the first spool position of the spool, the valve member of the PRSOV is in the open position, and wherein, in the second spool position of the spool, the valve member of the PRSOV is in the closed position;

wherein, upon loss of electrical power to the first stage unit when the spool is in the first spool position, the first stage unit is configured to:
control the second stage unit to move the spool to the second spool position over a predetermined time duration from loss of electrical power to the first stage unit, such that the valve member of the PRSOV moves to the closed position after the predetermined time duration and allows the flow of the fuel from the delivery line to the engine line during the predetermined time duration, wherein, after the predetermined time duration, the valve member of the PRSOV is at the closed position to prevent the flow of the fuel from the delivery line to the engine line; or
control the second stage unit to retain the spool in the first spool position, such that the valve member of the PRSOV is retained in the open position;

wherein the first stage unit comprises:
a movable member movable at least between a first end position corresponding to the first spool position of the spool of the second stage unit and a second end position corresponding to the second spool position of the spool of the second stage unit;
a stage actuating unit configured to actuate the movable member between the first end position and the second end position, wherein the stage actuating unit is electrically powered, such that loss of electrical power to the first stage unit corresponds to loss of electrical power to the stage actuating unit, wherein, in the first end position of the movable member, the first stage unit controls the second stage unit to move the spool to the first spool position, and, in the second end position of the movable member, the first stage unit controls the second stage unit to move the spool to the second spool position;
a fluid chamber at least partially receiving the movable member therein;
a first chamber port fluidly communicating with the fluid chamber, wherein the movable member is configured to close the first chamber port in the first end position;
a second chamber port fluidly communicating with the fluid chamber, wherein the movable member is configured to close the second chamber port in the second end position;
a third chamber port fluidly communicating with the fluid chamber, wherein the third chamber port is open irrespective of a position of the movable member;
a first input port configured to receive a high pressure fuel flow from the supply line and fluidly connected with each of the first chamber port and the second chamber port;
a second input port configured to receive a low pressure fuel flow from a low pressure line and fluidly connected to the third chamber port;
a first output port fluidly connected to the first chamber port; and
a second output port fluidly connected to the second chamber port.