Abstract: A fuel system for a gas turbine engine that utilizes a centrifugal pump is presented. The system includes a fuel metering valve that is adapted to set a metered flow of fuel, and a throttle valve that is adapted to accurately control pressure drop across the fuel metering valve. The throttle valve has at least two variable orifices and a compensation chamber between the variable orifices. The throttle valve includes a differential valve piston slidable in a valve body. The differential valve piston comprises working surfaces of at least two different diameters such that changes in chamber pressures effect different axial forces upon the piston.

Abstract: A fuel system for a gas turbine engine that utilizes a centrifugal pump. The system includes a fuel metering valve that is adapted to set a metered flow of fuel, and a throttle valve that is adapted to accurately control pressure drop across the fuel metering valve. The throttle valve has at least two variable orifices and a compensation chamber between the variable orifices. The throttle valve includes a differential valve piston slidable in a valve body. The differential valve piston comprises working surfaces of at least two different diameters such that changes in chamber pressures effect different axial forces upon the piston.

Abstract: A fuel system having an ecology valve controlling liquid flow through a retention passage when pressurized liquid is passed through the valve is presented. The retention passage winds between the valve outlet and a cavity such that no matter which way the valve is oriented gravity alone is unable to drain liquid from the cavity to the outlet. The ecology valve serves to suction fuel from fuel nozzle passages upon engine shutdown. Fuel is temporarily stored in the cavity and the retention passage. The ecology valve also provides a fuel splitting function for providing a port geometry determined split between fuel nozzles in the fuel system.

Abstract: A fuel system having an ecology valve controlling liquid flow through a retention passage when pressurized liquid is passed through the valve is presented. The retention passage winds between the valve outlet and a cavity such that no matter which way the valve is oriented gravity alone is unable to drain liquid from the cavity to the outlet. The ecology valve serves to suction fuel from fuel nozzle passages upon engine shutdown. Fuel is temporarily stored in the cavity and the retention passage. The ecology valve also provides a fuel splitting function for providing a port geometry determined split between fuel nozzles in the fuel system.

Abstract: The present invention is directed toward an ecology valve that drains working fuel to the sump chamber of the ecology valve upon engine shut down. The ecology valve has a piston slidable in the piston chamber between shut-off and run positions. The piston divides the piston chamber into a sump chamber and an actuation chamber. Upon engine shut down, the piston slides toward the shut-off position and suctions sufficient fuel from the fuel manifold into the sump chamber to prevent coking of the nozzles. Upon the next engine start up, the actuation chamber is pressurized which drives the piston toward the run position and returns fuel contained in sump chamber to the fuel manifold. A drain passageway opens and fluidically connects the actuation chamber to sump chamber when the piston is sliding toward the shut-off position which allows fuel contained in the actuation chamber to drain to the sump chamber.

Abstract: The present invention is directed toward an ecology valve that drains working fuel to the sump chamber of the ecology valve upon engine shut down. The ecology valve has a piston slidable in the piston chamber between shut-off and run positions. The piston divides the piston chamber into a sump chamber and an actuation chamber. Upon engine shut down, the piston slides toward the shut-off position and suctions sufficient fuel from the fuel manifold into the sump chamber to prevent coking of the nozzles. Upon the next engine start up, the actuation chamber is pressurized which drives the piston toward the run position and returns fuel contained in sump chamber to the fuel manifold. A drain passageway opens and fluidically connects the actuation chamber to sump chamber when the piston is sliding toward the shut-off position which allows fuel contained in the actuation chamber to drain to the sump chamber.

Abstract: 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.

Abstract: A fuel system for a gas turbine aircraft engine including a ecology valve and a flow divider valve, both of simple and compact construction. The ecology valve is connected to the fuel manifolds supplied by the splitter valve, and serves to suction fuel from the fuel manifolds upon engine shutdown. The fuel is temporarily stored in reservoirs in the ecology valve and upon the next engine operating cycle, is returned to the manifold so that it can be burned. The splitter valve is of simplified light-weight construction and includes a single piston operated in two regions, a first for modulating primary and second flow depending on fuel pressure, and a second region for providing a fixed, port geometry determined split between the primary and secondary.

Abstract: A fuel metering unit for an aircraft gas turbine engine having both electronic and manual control, both compensated for altitude variations. A three-dimensional cam is used to control the position of a fuel metering valve. One axis of the 3-D cam is electronically controlled and another is mechanically controlled. Electronic control is the normal mode and sets the electronic axis to provide a fuel metering valve setting which delivers a mass flow rate to the engine as demanded by the position of the fuel lever as interpreted by the electronic control. Upon failure of the electronic control, the position of the 3-D cam along the electronic axis is mechanically locked so that any further changes in fuel metering valve position are a function solely of the position of the power lever as translated to the mechanical axis of the 3-D cam. Transfer from electronic to manual control is therefore "bumpless.

Abstract: A fuel metering unit for an aircraft gas turbine engine has both electronic and manual control, both compensated for altitude variations. A three-dimensional cam is used to control the position of a fuel metering valve. One axis of the 3-D cam is electronically controlled and another is mechanically controlled. Electronic control is the normal mode and sets the electronic axis to provide a fuel metering valve setting which delivers a mass flow rate to the engine as demanded by the position of the fuel lever as interpreted by the electronic control. Upon failure of the electronic control, the position of the 3-D cam along the electronic axis is mechanically locked so that any further changes in fuel metering valve position are a function solely of the position of the power lever as translated to the mechanical axis of the 3-D cam. Transfer from electronic to manual control is therefore "bumpless.

Abstract: A multiplexed hydraulic control system having a plurality of channels and a common source of modulated hydraulic fluid. The common source is shared among the plurality of channels by providing a plurality of selector valves, one for each channel, with electrical solenoids for the selector valves being individually controlled by a control means. In a normal operating mode, the selector valves are operated individually and the modulating means is controlled to direct fluid to the selected channel in accordance with the demands placed on movement of the actuator in that channel. In a second slewing mode, multiple selector valves are energized at the same time and the modulator is controlled to produce sufficient fluid flow to slew all of the actuators in the selected channels at a desired rate.

Abstract: A multiplexed hydraulic control system in which high force margins for the multiplexer are achieved by employing hydraulic oscillators as the multiplexer driving means. The multiplexer is typically in the form of a hydraulic cylinder having an input port and a plurality of output ports, with an operator in the cylinder for individually connecting the input port to the output ports. The hydraulic oscillator is mechanically coupled to the multiplexer operator, and oscillation of the former causes oscillation of the latter to sequentially connect the input to each of the outputs. Various means are taught for initiating reversal of the oscillator and controlling the oscillation speed.

Abstract: The pressure regulator includes a valve member which is supported to slide back and forth in a valve housing having a high pressure port, a low pressure port and a bypass port. Pressure fluid from the high pressure port is bypassed through the valve member via an orifice, a passage and a metering opening formed in the valve member, the passage communicating with a compensating chamber located between the valve member and the valve housing. As the bypass flow increases, the increased pressure drop across the orifice reduces the pressure in the chamber to compensate for the progressive resistance imposed upon the valve member by a bias spring and by increasing fluid reaction forces. The compensating chamber enables the regulator to maintain a more substantially constant pressure drop across the high and low pressure ports of the regulator at various bypass flow rates.