Electric power generating turbine engine fuel supply system

A turbine engine fuel supply system includes a priority flow line, a plurality of secondary fuel loads, a fluid-powered metering pump, a mechanically-driven fuel pump, and an electric machine. The fluid-powered metering pump, upon receiving fuel at its fuel inlet, rotates at a rotational speed, discharges the fuel from its fuel outlet at a flow rate dependent on the rotational speed, and supplies a first drive torque. The mechanically-driven fuel pump receives a second drive torque and, in response, draws fuel into its fuel inlet and discharges the fuel from its outlet to the fluid-powered metering pump fuel inlet to drive the fluid-powered metering fuel pump. The electric machine receives the first drive torque from the fluid-powered metering pump and generates electrical power.

TECHNICAL FIELD

The present invention generally relates to turbine engine fuel supply systems and, more particularly, to a turbine engine fuel supply system that is configured with a pump driven generator that at least selectively generates electrical power.

BACKGROUND

Typical gas turbine engine fuel supply systems include a fuel source, such as a fuel tank, and one or more pumps. The one or more pumps draw fuel from the fuel tank and deliver pressurized fuel to one or more primary fuel loads and to one or more secondary fuel loads via one or more supply lines. Generally, the primary fuel loads, which include the fuel manifolds in the engine combustor, are supplied with fuel via, for example, a priority flow line. The secondary fuel loads, which may include a motive flow valve and regulator, one or more variable geometry actuators, and one or more bleed valves, are supplied with fuel via, for example, a secondary flow line.

Recently, there has been a desire to implement fuel supply systems with electric pumps. In such systems, fuel flow is controlled by, for example, controlling the speed of the electric pump, rather than the position of a metering valve and/or a bypass flow valve. Preferably, the electric pump is sized to supply the maximum fuel flow that may be needed by allow of the system loads. Thus, for systems that include one or more secondary fuel loads, the electric pump may need to be sized to supply a higher flow rate than what is needed by just the primary fuel loads. As a result, the overall fuel system design may exhibit certain undesirable drawbacks. For example, a relatively larger electric pump may generate excessive fuel system heat, and/or may increase overall fuel system weight and costs.

Hence, there is a need for a fuel supply system that uses an electric pump to control fuel flow to one or more primary loads and that is able to supply fuel to secondary fuel loads without generating excessive fuel system heat, and/or increasing overall fuel system weight and/or costs. The present invention addresses one or more of these needs.

BRIEF SUMMARY

In one embodiment, and by way of example only, a turbine engine fuel supply system includes a priority flow line, a plurality of secondary fuel loads, a fluid-powered metering pump, a mechanically-driven fuel pump, and an electric machine. The priority flow line is configured to supply fuel to one or more gas turbine engine fuel manifolds. The fluid-powered metering pump has a fuel inlet and a fuel outlet, and is coupled to receive fuel at its fuel inlet. The fluid-powered metering pump, upon receipt of the fuel at its fuel inlet, rotates at a rotational speed, discharges the fuel from its fuel outlet for supply to the priority flow line at a flow rate dependent on the rotational speed, and supplies a first drive torque. The mechanically-driven fuel pump has a fuel inlet and a fuel outlet. The mechanically-driven fuel pump fuel outlet is in fluid communication with the fluid-powered metering pump fuel inlet. The mechanically-driven fuel pump is adapted to receive a second drive torque and is operable, upon receipt of the second drive torque, to draw fuel into its fuel inlet and discharge the fuel from its outlet to the plurality of secondary fuel loads and to the fluid-powered metering pump fuel inlet to drive the fluid-powered metering fuel pump. The electric machine is connected to receive the first drive torque from the fluid-powered metering pump and is operable, upon receipt thereof, to generate electrical power.

In another exemplary embodiment, a gas turbine engine system includes a gas turbine engine, a plurality of secondary fuel loads, an fluid-powered metering pump, a mechanically-driven fuel pump, and an electric machine. The gas turbine engine includes one or more fuel manifolds and a gearbox. The fluid-powered metering pump has a fuel inlet and a fuel outlet, and is coupled to receive fuel at its fuel inlet. The fluid-powered metering pump, upon receipt of the fuel at its fuel inlet, rotates at a rotational speed, discharges the fuel from its fuel outlet for supply to the one or more fuel loads at a flow rate dependent on the rotational speed, and supplies a first drive torque. The mechanically-driven fuel pump has a fuel inlet and a fuel outlet. The mechanically-driven fuel pump fuel outlet is in fluid communication with the fluid-powered metering pump fuel inlet. The mechanically-driven fuel pump is adapted to receive a second drive torque and is operable, upon receipt of the second drive torque, to draw fuel into its fuel inlet and discharge the fuel from its outlet to the plurality of secondary fuel loads and to the fluid-powered metering pump fuel inlet to drive the fluid-powered metering fuel pump. The electric machine is connected to receive the first drive torque from the fluid-powered metering pump and is operable, upon receipt thereof, to generate electrical power.

In yet another exemplary embodiment, a turbine engine fuel supply system includes a priority flow line, a plurality of secondary fuel loads, a fluid-powered metering pump, a mechanically-driven fuel pump, a differential pressure control valve, an electric machine, an electrical load, and a controller. The priority flow line is configured to supply fuel to one or more gas turbine engine fuel manifolds. The fluid-powered metering pump has a fuel inlet and a fuel outlet, and is coupled to receive fuel at its fuel inlet. The fluid-powered metering pump, upon receipt of the fuel at its fuel inlet, rotates at a rotational speed, discharges the fuel from its fuel outlet for supply to the priority flow line at a flow rate dependent on the rotational speed, and supplies a first drive torque. The mechanically-driven fuel pump has a fuel inlet and a fuel outlet. The mechanically-driven fuel pump fuel outlet is in fluid communication with the fluid-powered metering pump fuel inlet. The mechanically-driven fuel pump is adapted to receive a second drive torque and is operable, upon receipt of the second drive torque, to draw fuel into its fuel inlet and discharge the fuel from its outlet to the plurality of secondary fuel loads and to the fluid-powered metering pump fuel inlet to drive the fluid-powered metering fuel pump. The differential pressure control valve is in fluid communication with the fluid-powered metering pump fuel inlet and the fluid-powered metering pump fuel outlet, and is operable to maintain a constant differential pressure across the fluid-powered metering pump. The electric machine is connected to receive the first drive torque from the fluid-powered metering pump and is operable, upon receipt thereof, to generate electrical power. The electrical load is connected to selectively receive the electrical power generated by the electric machine. The controller is operable to selectively connect and vary the electrical load to thereby control the rotational speed and the flow rate of the fluid-powered metering pump.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. In this regard, although an embodiment of the invention is described as being implemented in an aircraft and for a gas turbine engine, it will be appreciated that the invention may be implemented in numerous and varied end-use environments where fuel flow to primary and secondary fuel loads is controlled.

Turning now toFIG. 1, a simplified schematic diagram of one embodiment of a fuel delivery and control system for a gas turbine engine, such as a turbofan jet aircraft engine, is depicted. The system100includes a fuel source102, a fluid-powered metering pump104, a mechanically-driven fuel pump106, a metering pump differential pressure control valve108, a fuel shut-off valve110, and a controller112. The fuel source102, which is preferably implemented as one or more tanks, stores fuel that is to be supplied to a plurality of fuel loads114(e.g.114-1,114-2,114-3, . . .114-N). It will be appreciated that the number and type of fuel loads may vary, and may include one or more gas turbine engine fuel manifolds114-1, one or more surge valves114-2, one or more variable geometry actuators114-3, and one or more bleed valves114-4, just to name a few. The fuel loads114are preferably classified as primary and secondary fuel loads based, for example, on functionality. Though the classifications may vary, the one or more gas turbine engine fuel manifolds114-1, which are disposed within the combustor zone of a gas turbine engine115, are typically classified as primary fuel loads. Moreover, the one or more surge valves114-2, the one or more variable geometry actuators114-3, and the one or more ejector valves114-4are typically classified as secondary fuel loads. Although not depicted as such for clarity, it will be appreciated that one or more of the secondary fuel loads may additionally be disposed within the gas turbine engine115.

A supply line116is coupled to the fuel source102and, via the pumps104,106, delivers the fuel to the fuel loads114. It is noted that the supply line116is, for convenience, depicted and described as including a priority flow line116-1and a secondary flow line116-2. The priority flow line116-1preferably delivers fuel to the primary fuel loads (e.g.,114-1), and the secondary flow line116-2preferably delivers fuel to the secondary fuel loads (e.g.,114-2,114-3,114-4, . . .114-N). AsFIG. 1further depicts, the system may optionally include a secondary flow line pressure regulator117and an ultimate relief valve119.

The fluid-powered metering pump104is positioned in flow-series in the supply line116, and is preferably a positive displacement pump such as, for example, a fixed displacement, variable speed positive displacement piston pump. The fluid-powered metering pump104includes a fuel inlet103and a fuel outlet105and, as this nomenclature connotes, is driven, at least during normal system100operations, by fluid. More specifically, the fluid-powered metering pump104is configured to be responsive to fuel supplied to its fuel inlet103to rotate and discharge fuel out its fuel outlet105and to the priority flow line116-1. The fluid-powered metering pump104is additionally configured to discharge the fuel at a flow rate that is dependent on its rotational speed. The manner in which the rotational speed of the fluid-powered metering pump104is controlled will be described further below.

The mechanically-driven fuel pump106is also positioned in flow-series in the supply line116, and includes a fuel inlet107and a fuel outlet109. The mechanically-driven fuel pump106draws fuel into its fuel inlet107and discharges the fuel, also at a relatively high pressure, via its fuel outlet107, to the fluid-powered metering pump fuel inlet103and to the secondary flow line116-2. The mechanically-driven pump106may be variously implemented, but in the depicted embodiment it includes an input shaft124and a fluid pump126. The input shaft124is coupled to, and receives an engine drive torque from, the gas turbine engine115. Specifically, at least in the depicted embodiment, the input shaft124is coupled to the gas turbine engine gearbox117and, upon receipt of the engine drive torque, supplies a pump drive torque to the fluid pump126. The fluid pump126is preferably a high pressure pump, such as a positive displacement pump, and is coupled to the input shaft124. The fluid pump126is responsive to the pump drive torque supplied from the input shaft124to draw fuel into its fuel inlet107and discharge the fuel from its fuel outlet109for supply to the fluid-powered metering pump fuel inlet103and, via the secondary flow line116-2, to the plurality of secondary fuel loads114-2,114-3,114-4, . . .114-N. It may thus be appreciated that fuel is supplied to the secondary fuel loads114-2,114-3,114-4, . . .114-N independent of the fluid-powered metering pump104. It may thus be appreciated that the mechanically-driven pump106is sized to supply sufficient fluid power to simultaneously drive the fluid-operated metering pump104and the secondary fuel loads114-2,114-3,114-4, . . .114-N.

In the depicted embodiment, the system100includes an additional boost pump118, such as a relatively low horsepower centrifugal pump. The boost pump118, if included, takes a suction directly on the fuel source102and provides sufficient suction head for the fluid-powered metering pump104and the mechanically-driven pump106. It will additionally be appreciated that the boost pump118may be either mechanically driven by the engine, or electrically driven by a non-illustrated motor. Moreover, the boost pump118may, in some embodiments, not be included. Although not depicted, it will be appreciated that the system100may additionally include a low pressure pump within the fuel tank(s)102to supply fuel to the boost pump118.

The metering pump differential pressure control valve108is in fluid communication with the fluid-powered metering pump fuel inlet103and the fluid-powered metering pump fuel outlet105, and is configured to maintain a constant differential pressure across the fluid-powered metering pump104. To do so, the metering pump differential pressure control valve108includes at least a first reference port125, a second reference port127, an inlet port129, an outlet port131, and a variable area flow orifice133. The first reference port125and the inlet port129are both in fluid communication with the metering pump fuel inlet103, the second reference port127is in fluid communication with the fuel metering pump fuel outlet105, the outlet port131is in fluid communication with the mechanically driven pump fuel inlet107, and the variable area flow orifice is in fluid communication between the inlet port129and the outlet port131. The metering pump differential pressure control valve108, via the first and second reference ports125,127, senses the differential pressure across the fluid-powered metering pump104, and is operable to adjust the area of the variable area flow orifice133, and thus the flow between the inlet and outlet ports129,131, to maintain a substantially constant differential pressure across the fluid-powered metering pump104. It will be appreciated that in some embodiments the system100could be implemented without the metering pump differential pressure control valve108. However, the reason for including it in the preferred embodiment will be discussed further below.

The fuel shut-off valve110is positioned in flow-series in the priority flow line116-1downstream of the fluid-powered metering pump104. More specifically, the fuel shut-off valve110is mounted on the priority flow line116-1between the fluid-powered metering pump104and the one or more fuel manifolds114-1. The fuel shut-off valve110, at least in the depicted embodiment, is implemented using a three-way valve, and is movable between a closed position and an open position. As such, the fuel shut-off valve110includes an inlet111that is in fluid communication with the fluid-powered metering pump outlet105, an engine outlet113that is in fluid communication with the one or more fuel manifolds114-1, and a return outlet121that is in fluid communication with the mechanically-driven fuel pump inlet107via a start load valve123. In the closed position, fuel flow through the fuel shut-off valve108and to the one or more fuel manifolds114-1is prohibited. Conversely, in the open position, fuel flow through the fuel shut-off valve108may occur. It will be appreciated that the fuel shut-off valve108may not be included in some embodiments. It will additionally be appreciated that the fuel shut-off valve108, at least in some embodiments, may include only two flow ports.

As was noted above, the flow rate at which the fluid-powered metering pump104supplies fuel is dependent upon its rotational speed. In the depicted system100, the rotational speed of the fluid-powered metering pump104is controlled via an electric machine122and one or more electrical loads123. More specifically, and as may be readily understood, as the fluid-powered metering pump104rotates, it generates a drive torque. The electric machine122is connected to receive the drive torque from the fluid-powered metering pump104and is configured, upon receipt of the drive torque, to generate electrical power. The electric machine122is preferably a DC brushless machine that may be operated as either a motor or a generator, though it will be appreciated that it could be implemented as various other types of AC or DC machines that may be operated as both a motor and a generator. It will additionally be appreciated that a plurality of electrical machines122could be coupled to the fluid-powered metering pump104, if needed or desired, to provide redundancy.

The one or more electrical loads123are connected to at least selectively receive the electrical power generated by the electric machine122. For clarity, only a single electrical load123is depicted, though it will be appreciated that the system100could include a plurality of various electrical loads. Moreover, the one or more electrical loads123may be variously implemented. For example, the one or more electrical loads123could be implemented as load resistances. Alternatively, a power bus and/or one or more electrical loads on the power bus could implement the one or more electrical loads123. Moreover, combinations of load resistances and a power bus could also be used.

It was noted above that metering pump differential pressure control valve108, though optional, is included in the preferred system embodiments. This is because the control laws used to control the speed of the fluid-powered metering pump104, and thus the fuel flow rate to the engine115, are relatively easier to implement if a constant (or at least substantially constant) differential pressure is maintained across the fluid-powered metering pump104. If the differential pressure were not controlled to a constant value, the control laws would be much more complex to implement.

The controller112is configured to selectively connect the electrical load123to, and to controllably vary the electrical load123on, the electric machine122. In doing so, the controller112thereby controls the rotational speed and the flow rate of the fluid-powered metering pump104. Preferably, the controller112is adapted to receive one or more signals128representative of a desired fuel flow rate for the one or more engine fuel manifolds114-1. The controller112, in response to the command signal128, controls the electrical load123on the electric machine122to control the rotational speed of the fluid-powered metering pump104. It will be appreciated that in some embodiments, the system100could be implemented with more than one controller112, most notably in system embodiments that include more than one electric machine122.

In addition to the above, the controller112may also, at least in some embodiments be configured to selectively control the supply of electrical current to the electric machine122, to thereby controllably drive the fluid-powered metering pump104. Preferably, this configuration is implemented during, for example, a start-up of the system100, when the mechanically-driven fuel pump106may not supply sufficient fuel to drive the fluid-powered metering pump104. During this configuration, the controller112is responsive to the command signal128to control the current supplied to the electric machine122such that it generates a drive torque to drive the fluid-powered metering pump104. Thereafter, when the mechanically-driven fuel pump106is supplying sufficient fuel to drive the fluid-powered metering pump104, the controller112controls the electric machine122to operate as a generator.

The system100, at least in the depicted embodiment, further includes an engine control150. The engine control150, which may be implemented as a Full Authority Digital Engine Controller (FADEC) or other electronic engine controller (EEC), controls the flow rate of fuel to the one or more fuel manifolds114-1. To do so, the engine control150receives various input signals and controls the fuel flow rate to the one or more fuel manifolds114-1accordingly. In particular, the engine control150receives one or more signals152representative of a desired fuel flow to be delivered to the one or more engine fuel manifolds114-1. The engine control150, in response to the one or more signals152, automatically generates the above-mentioned command signal128that is supplied to the controller112. It will be appreciated that in some embodiments, as depicted using the dotted line inFIG. 1, the controller112and the engine control150may be integrated together.