Abstract: A reservoir includes first and second chambers, and a piston having first and second ends disposed in the first and second chambers, respectively. The first and second ends isolate a first area from a second area within the first and second chambers. The first area of the first chamber is in fluid communication with a high pressure fluid source and the second area of the first chamber is in fluid communication with a low pressure fluid source. An orifice is formed in the first end and is configured to allow fluid communication between the upper and lower areas of the first chamber. A pumping system and an aircraft are also disclosed.

Abstract: A fuel system for a gas turbine engine includes an engine fuel manifold, a hydraulic actuator, and a drain piston assembly. The hydraulic actuator actuates in response to a change in pressures within the hydraulic actuator. The drain piston assembly is fluidically connected to both the hydraulic actuator and the engine fuel manifold. The drain piston assembly receives fuel from the engine fuel manifold and sends fuel to the hydraulic actuator during engine shut down.

Abstract: A gear pump has a pair of meshed gears for rotating within a gear pump chamber, and a motor driving at least one of the gears. A discharge line passes fluid downstream from the gear pump chamber, and a suction line delivers fluid into the gear pump chamber. A bypass valve communicates with the discharge line. A shutoff valve communicates with the discharge line. The bypass valve opens at a lower pressure than the shutoff valve. A bypass line communicating the discharge line to the suction line when the bypass valve is open. The gear pump is configured to compress air. In addition, a gear pump arrangement that can be mounted in either of two attitudes is described, as is a method of operating a gear pump.

Abstract: A fuel flow system for a gas turbine engine includes a first pump, a second pump, a bypass loop, an integrating bypass valve and a pilot valve. The first pump connects to an actuator and a metering valve. The second pump connects to the metering valve and is arranged in parallel with the first pump. The bypass loop recycles fuel flow from the first pump and the second pump to inlets of the first pump and second pump integrating bypass valve includes first and second windows. The first window regulates fuel from the first pump through the bypass loop and the second window that regulates fuel from the second pump through the bypass loop. The pilot valve controls the size of the first and second windows.

Abstract: A gear pump has a pair of meshed gears for rotating within a gear pump chamber, and a motor driving at least one of the gears. A discharge line passes fluid downstream from the gear pump chamber, and a suction line delivers fluid into the gear pump chamber. A bypass valve communicates with the discharge line. A shutoff valve communicates with the discharge line. The bypass valve opens at a lower pressure than the shutoff valve. A bypass line communicating the discharge line to the suction line when the bypass valve is open. The gear pump is configured to compress air. In addition, a gear pump arrangement that can be mounted in either of two attitudes is described, as is a method of operating a gear pump.

Abstract: A fuel flow system for a gas turbine engine includes a first pump, a second pump, a bypass loop, an integrating bypass valve and a pilot valve. The first pump connects to an actuator and a metering valve. The second pump connects to the metering valve and is arranged in parallel with the first pump. The bypass loop recycles fuel flow from the first pump and the second pump to inlets of the first pump and second pump integrating bypass valve includes first and second windows. The first window regulates fuel from the first pump through the bypass loop and the second window that regulates fuel from the second pump through the bypass loop. The pilot valve controls the size of the first and second windows.

Abstract: A fuel flow system for a gas turbine includes a first pump, a main fuel flow path and a second pump. The first pump is connected to an actuator and a metering valve. The main fuel flow path is formed between the first pump and the metering valve. The second pump is connected to the main fuel flow path and supplements the fuel flow from the first pump under certain conditions. The second pump and first pump are in parallel.

Abstract: A system allows pumps to run in parallel and preventing back flow through a non-operational pump. The system includes a first pump in parallel with a second pump. The system further includes a check valve in fluid communication with the first pump for preventing flow through the first pump when the first pump is not operating. The system further includes a sensing valve in fluid communication with the first pump and the second pump. The system also includes a load sharing valve in fluid communication with the check valve, the sensing valve, and the second pump for controlling a system flow, wherein the system flow is provided by the first pump when the second pump is not operating, and wherein the system flow is provided by the second pump when the first pump is not operating, and wherein the system flow includes a portion of flow from both the first and second pumps when both pumps are operational.

Abstract: An electronic control for a variable delivery, positive displacement fuel pump includes a flow sensor located at the fuel outlet to the engine. The flow sensor provides a signal, indicative of actual fuel flow to the engine, to an electronic engine control. The electronic engine control compares actual fuel flow with desired fuel flow, and upon any difference therebetween commands an electrohydraulic servo valve to position a pump control actuator. The pump control actuator controls the amount of fuel delivered by the pump. Also, fuel flow upstream of the flow sensor is bypassed in a line to another section of the electrohydraulic servo valve. The electronic engine control commands a small amount of fuel to be bypassed back to the pump inlet during normal operating conditions. However, upon the occurrence of a transient condition, the electronic engine control causes more or less fuel to be bypassed back to the pump inlet.

Abstract: A hydromechanical control system for a variable delivery, positive displacement fuel pump includes a variable area orifice metering window through which fuel from the pump outlet passes on its way to a gas turbine aircraft engine. The fuel pressures on either side of the fuel metering window are ported to corresponding sides of a spool of a pump control valve. The position of the valve spool controls the fuel flow to either side of a pump control actuator, whose movement varies the displacement of the pump. A bypass fuel flow upstream of the fuel metering valve is also ported to the pump control valve. During steady-state pump operation, a relatively small and constant value of fuel flow is bypassed through the pump control valve and back to the pump inlet. However, upon increasing or decreasing pump speed transients, the bypass fuel flow is increased or decreased in a proportional amount. In this way, improved control of the pump during transient conditions is achieved.

Abstract: A novel centrifugal pumping system is disclosed for supplying fuel to aircraft gas turbines. The system has a common rotor with two different sets of impeller blades on opposite sides. A regenerative/liquid-ring starting pump is located on one side of the rotor, and a centrifugal impeller is located on the other. During engine start-up, the regenerative/liquid-ring pump is capable of priming itself and supplies engine fluid and pressure. The starting pump delivers fuel until the main pump reaches a speed sufficient to provide adequate pressure for fuel delivery. At that time, the starting pump is switched off, via a valving system.

Abstract: In a fuel staging system, metered fuel from a fuel metering unit is directed into a fuel inlet line coupled to a sequence valve. A minimum pressure valve maintains the pressure of the fuel flowing through the fuel inlet line at a minimum pressure above the low pressure of the system in order to ensure sufficient force margins to stroke the sequence valve. A main fuel manifold is coupled downstream of the sequence valve, and a plurality of main fuel nozzles are each coupled to the main fuel manifold through a respective main nozzle shut-off valve. A first set of pilot nozzles is coupled to the main fuel manifold through the sequence valve, and a second set of pilot nozzles is coupled to the main fuel manifold through the sequence valve. At low engine speeds, in the first and/or second pilot open positions, fuel flows to either pilot nozzle through the main fuel manifold, and the main fuel nozzles are isolated from the main fuel manifold by the main nozzle shut-off valves.

Abstract: A pressure regulating valve 10 determines a fixed constant pressure drop across a metering valve 16 at a given altitude by comparing ambient pressure with a vacuum. Evacuated bellows 76 reacts with changes in altitude to bias a poppet 54 via rod 90, adjusting screw 100 and lever 66 towards or away from outlet 54.