Abstract: A temperature compensated fluid metering valve has a body including a ported sleeve in which a metering element is slidable, the thermal coefficient of expansion of the sleeve and metering element being identical and different from that of the body. The sleeve is secured at one of its ends to the body and a device for detecting the position of the metering element is secured to the body at the other end of the sleeve. The dimensions of the body and the coefficients of expansion are selected so a change in temperature results in an apparent position error signal from the device, this signal repositioning the metering element to compensate for changes in specific gravity of the metered fluid as a result of the temperature change.

Abstract: A gas turbine engine fuel control has spill value responsive to an input control signal, for spilling fuel from a supply passage. A pressurizing valve controls flow from the supply passage to the engine, in response to the pressure in the supply passage. A throttle valve in series with the pressurizing valve maintains the pressure difference across the pressurizing valve substantially constant. A selector valve is operable to shut both the pressurizing valve and a shut-off element in the throttle valve.

Abstract: A fuel control for a gas turbine engine comprises a metering device and a pressure relief valve for spilling fuel from an upstream side of the metering device. The relief valve is also responsive to a servo pressure which is regulated by a valve which is operated when a speed of the engine rises above a predetermined level, so that in these circumstances an increased amount of fuel is spilled to reduce flow to the engine. A further valve is operable to vent the servo pressure completely, and to effect spill of substantially all of the fuel, when engine shut-down is required.

Abstract: A fuel control system for a gas turbine engine comprises a variable metering device and a flow limiting valve arranged in series. The limiting valve is servo pressure operated to reduce fuel flow in response to unacceptably high levels of certain engine operating conditions and is additionally movable to a fully shut condition when the engine is stopped. The servo operating pressure is controlled by an electrically actuated pilot valve which can be energized to a first level to provide flow limitation, and to a second, higher level to effect shut down. The pilot valve can also be energized in a reverse direction to open the limiting valve when starting the engine.

Abstract: A gas turbine engine fuel control system has a three-dimensional cam which is positioned by sensed values of engine compressor inlet and outlet pressures. The cam has two profiles which respectively indicate a desired ratio of the compressor pressures and a desired fuel flow. Interlinked cam followers engage the respective cam profiles and are also responsive to a device for setting a desired engine thrust. The cam follower linkage positions a variable metering device for the engine fuel supply.

Abstract: A shut-off valve arrangement for a gas turbine engine fuel supply system includes a shut-off valve in a fuel supply line to the engine, and a drain valve communicating with said supply line downstream of the shut-off valve. Said shut-off valve and drain valve are responsive to a servo pressure signal which is applied through flow restrictors such that the drain valve shuts before the shut-off valve, but opens after the shut-off valve.

Abstract: A fuel control for a gas turbine engine reheat system has a plurality of metering valves operated by an electrical control circuit for regulating fuel flow from a pump to respective burners of the reheat system. The pump has an inlet throttle which is also operated by the control circuit so that pump delivery is substantially equal to the sum of the detected fuel flows through the metering valves. The value of a measured pressure drop across one metering valve is compared with a desired value of that pressure drop, and a difference between these values is used to adjust the control signal to the pump inlet throttle, and thereby render the pump delivery more nearly equal to the aforesaid total flow.

Abstract: A servo-operated shut-off valve arrangement has a main valve responsive to a servo pressure and fluid pressure operated pilot valve for controlling the servo pressure. The pilot valve has two stable operating positions in which the main valve servo pressure is respectively vented and maintained. The fluid pressure which operates the pilot valve is controlled by a valve device movable in opposite directions from a center-stable position to effect movement of the pilot valve. The pilot valve co-operates with the center-stable valve device so that the pilot valve remains in the position in which it was last urged by movement of the valve device away from its stable central position.

Abstract: A fuel control system for a gas turbine engine has a main metering valve which is positioned by a servo pressure signal controlled by a pilot valve. The pilot valve is responsive to compressor pressures within the engine and also to the operating position of the main metering valve. Response to the main metering valve position is variable in accordance with the difference between desired and actual engine speeds, and is effected by varying the position of a force multiplying roller interposed between the main metering valve and the pilot valve.

Abstract: A fuel control system has a main metering device and a flow limiting throttle valve arranged in series, and a spill valve responsive to a pressure drop within the system, for maintaining this pressure drop constant, the arrangement being that when the throttle valve is fully open the spill valve is responsive to the pressure drop across the metering device only, and in all other conditions of the throttle valve the spill valve is responsive to the total pressure drop across the series arrangement of the metering device and throttle valve.

Abstract: A throttle valve has a control member which is angularly positioned by two stepper motors which drive the control member through differential gearing. The drives to the control member are arranged so that a single step displacement of the respective motors in the same direction drives the control member by different amounts in opposite directions, providing a high resolution drive. The control member may be driven at a high speed by reversing one of the motors.

Abstract: A fluid flow control valve, particularly for use in a gas turbine engine fuel control system has an orifice with a closure member which is urged open by a pressure signal and which is urged shut by a biasing spring. The bias applied by the spring is variable by an input control lever and the response of the spring bias variation to lever movement is itself adjustable.