Pump actuation apparatus and associated pumping system, aircraft and fuel supply method

Abstract

The invention relates to an actuation device (12) for a fuel pump (20) of an aircraft engine (18), the actuation device (12) comprising an electric motor (24), a generator (26) and an electrical connection member (27), the electric motor (24) being an asynchronous electric machine with a Darlington coupling, the asynchronous electric machine comprising a first rotor (32) coupled to the pump (20) to actuate the pump and a first stator (34) comprising at least one input phase (36) each comprising two windings (39), the generator (26) comprising a second rotor (32) mechanically coupled to a shaft (37) of the engine (18) and a second stator (40) comprising at least one output phase (42), the electrical connection member (27) being configured to connect each output phase (42) to an input phase (36) and to connect the windings (39) of each input phase (36) in series or in parallel according to the speed of the engine (18).

Description

Technical Field

[0001] The present invention relates to an actuation device designed to drive at least one fuel pump in a fuel pumping system for an aircraft engine.

[0002] The present invention also relates to a fuel pumping system, an aircraft embedded with such a pumping system, and a method for supplying fuel to the engine of such an aircraft.

[0003] This invention is applicable to the aviation field, and particularly to the fuel supply of aircraft engines. Background Technology

[0004] It is known that at least one pump is used on an aircraft to deliver fuel from the aircraft's fuel tank to the aircraft's engine in a fuel injection system. This pump (typically a positive displacement pump) is usually actuated via the aircraft's hydraulic circuit.

[0005] In the context of electrification of some aircraft actuators (including fuel delivery lines), it has been proposed to drive the pumps described above using rotary electric motors. More specifically, it has been proposed to set up a first rotary electric motor, called a "generator," and a second rotary electric motor, called a "motor," which are electrically connected to each other. In this case, the output shaft of the motor is coupled to the pump used to drive the motor, and the shaft of the generator is coupled to the shaft of the aircraft's engine. The generator and motor are typically composed of three-phase motors. In this way, during the operation of the aircraft's engine, the generator delivers current with a frequency proportional to the rotational speed of the aircraft's engine (also called "velocity"). Therefore, the rotational speed at the output of the motor is proportional to the engine speed, thereby driving the pump to deliver fuel at a flow rate proportional to the engine speed.

[0006] Nevertheless, this actuation device is not entirely satisfactory.

[0007] In practice, to ensure that the engine can properly supply fuel regardless of its speed, the pump driven by such an actuation device is sized such that, for any given speed, the flow rate supplied by the pump is at least equal to the flow rate required by the engine at said speed. Generally, this sizing determination involves selecting a pump with an appropriate displacement.

[0008] However, as Figure 1 As shown, curve 2, which shows the change in the required fuel flow rate as a function of the engine speed, is generally a concave increasing curve. In this case, the displacement is determined by the following operating point between the lowest speed operating point shown by point 4 (corresponding to the engine fan's rotation phase, or "windmill") and the highest speed operating point shown by point 6 (corresponding to the takeoff phase, or "takeoff"): this operating point has the highest ratio of required fuel flow rate to engine speed.

[0009] With the displacement determined by the minimum operating speed point 4, the fuel flow rate supplied by the pump (represented by line 8 passing through said minimum operating speed point 4) is always higher than the fuel flow rate required by the engine. For example, at the maximum operating speed point 6, the excess fuel flow rate is represented by arrow 10. In this case, it is necessary to install a fuel recirculation device.

[0010] During operation, a fuel recirculation system (typically connected to the engine's gearbox output) draws mechanical power from that output and dissipates a portion of that power as heat. However, this heat dissipation is detrimental because the fuel circuit (which includes the injection system) is used as a cooling source for the oil circuit. Any additional heat dissipation negatively impacts the size of the heat exchanger.

[0011] Therefore, the present invention aims to provide a pump-actuated device that, for any given operating point of an engine, results in a smaller difference between the fuel flow rate required at said operating point and the fuel flow rate supplied by the pump, i.e., the pump-actuated device reduces the need for fuel recirculation. Summary of the Invention

[0012] Therefore, the object of the present invention is an actuation device of the aforementioned type, which includes an electric motor rotating a motor, a generator rotating a motor, and an electrical connection component.

[0013] The electric rotary motor is an asynchronous motor with a Dahlander coupling. This asynchronous motor includes a first rotor and a first stator. The first rotor is designed to be mechanically coupled to each pump to actuate each pump. The first stator includes at least one input phase, each input phase comprising two windings.

[0014] The generator rotary motor includes a second rotor and a second stator, the second rotor being mechanically coupled to a shaft forming a drive shaft of the engine, and the second stator including at least one output phase.

[0015] The electrical connection components are configured to electrically connect each output phase to an input phase.

[0016] The electrical connection components are also configured to connect the corresponding windings in series or in parallel for each input phase, depending on the engine speed.

[0017] In fact, even when the highest ratio of required fuel flow to engine speed corresponds to the lowest speed operating point (i.e., the automatic fan rotation phase), this actuation device allows selection of the highest speed operating point used to determine pump size (especially pump displacement). In this case, through its operation, the electrically connected device can achieve two different operating modes:

[0018] - For speeds higher than the so-called "switching" speed, the motor windings are connected according to a first configuration, and then the motor is driven by the generator via the power supply of the generator at a rotational speed proportional to the engine speed and at a first proportionality ratio; and

[0019] - When the speed is below the switching speed, the motor windings are connected according to the second configuration, and then the motor is driven by the generator through the power supply of the generator at a rotational speed proportional to the speed of the engine and at a second proportionality ratio, which is higher than the first proportionality ratio.

[0020] Specifically, the switching speed corresponds to the speed at which the fuel flow supplied in the first configuration is equal to the fuel flow required by the engine.

[0021] As described above, due to the actuation device according to the present invention, the difference between the fuel flow rate required by the aircraft's engine at any given operating point and the fuel flow rate supplied by the pump is much smaller than the difference obtained by known actuation devices. Therefore, the fuel recirculation requirement is significantly reduced.

[0022] According to other advantageous aspects of the invention, the actuating device includes one or more of the following features, considered individually or in any technically possible combination:

[0023] - The electrical connection components are configured such that for each input phase of the electric motor rotating motor, if the motor speed is less than or equal to a predetermined switching speed, the corresponding windings are connected in parallel, otherwise the corresponding windings are connected in series.

[0024] - The electric rotary motor includes three input phases connected together in a delta configuration. The two windings of each input phase are electrically connected together at their midpoints via the ends of the two windings. Each winding of a given input phase is connected at its end opposite the corresponding midpoint to a corresponding winding of another corresponding input phase, forming a vertex.

[0025] The electrical connection components include a control stage, a first-stage switch, a second-stage switch, and a third-stage switch.

[0026] Each input of the first-stage switch is electrically connected to the corresponding output phase of the generator's rotating motor, and each output of the first-stage switch is connected to the midpoint of the corresponding input phase.

[0027] Each input of the second-stage switch is electrically connected to the corresponding output phase of the generator's rotating motor, and each output of the second-stage switch is connected to the corresponding vertex of the first stator.

[0028] The input phases of the third-stage switch are connected together, and each output phase of the third-stage switch is connected to the midpoint of the corresponding input phase.

[0029] The control stage is configured to turn on the first-stage switch and turn off each of the second and third-stage switches when the engine speed exceeds a predetermined switching speed.

[0030] The control level is also configured to control the first-stage switch to be in the off state when the engine speed is lower than or equal to a predetermined switching speed, and to control each of the second-stage and third-stage switches to be in the on state.

[0031] Furthermore, the object of the present invention is a fuel pumping system for an aircraft engine, the pumping system comprising at least one fuel pump and an actuation device as defined above, wherein a first rotor of an electric motor is mechanically coupled to each pump to actuate each pump.

[0032] Furthermore, the object of the present invention is an aircraft incorporating a pumping system as defined above, wherein each pump is inserted between the aircraft's fuel tank and the fuel injection device of the aircraft's engine, and the second rotor of the generator rotary motor is mechanically connected to the engine shaft.

[0033] Another object of the present invention is a method for supplying fuel to an engine of an aircraft as defined above, the method comprising connecting each output phase of a generator rotary motor to an input phase of an electric motor rotary motor, the supply method further comprising, for each input phase, connecting the corresponding windings in series or in parallel according to the speed of the engine.

[0034] According to an advantageous aspect, the supply method includes, for each input phase, connecting the corresponding windings in parallel if the engine speed is less than or equal to a predetermined switching speed, and otherwise connecting the corresponding windings in series. Attached Figure Description

[0035] The invention will be better understood through the following description, given only as a non-limiting example and with reference to the accompanying drawings, in which:

[0036] Figure 1 It is a graph showing the functional relationship between the engine's fuel demand and the rotational speed of the engine's high-pressure shaft.

[0037] Figure 2 This is a schematic diagram of the pumping system according to the present invention.

[0038] Figure 3 and Figure 1 Similarly, it also shows the influence of Figure 2 The change in the flow rate of fuel supplied by the pumping system. Detailed Implementation

[0039] Figure 2 A fuel pumping system 12, specifically for an aircraft engine, according to the present invention, is shown.

[0040] The pumping system 12 is designed to deliver fuel from the fuel tank 14 of the aircraft (not shown) to the fuel injection device 16 of the aircraft's engine 18.

[0041] More specifically, the pumping system 12 includes at least one rotary pump 20 and an actuation device 22, the at least one rotary pump being arranged between the fuel tank 14 and the injection device 16, the actuation device being intended to drive the pump or each pump 20.

[0042] Each pump 20 is a positive displacement pump or a centrifugal pump.

[0043] The actuation device 22 includes an electric motor rotating motor 24 (referred to as "electric motor"), a generator rotating motor 26 (referred to as "generator"), and an electrical connection member 27.

[0044] The electric motor 24 is configured to receive electrical energy from the generator 26 and convert the received electrical energy into mechanical energy intended to actuate the pump or each pump 20.

[0045] The electric motor 24 is an asynchronous motor with a Daland coupling. The electric motor 24 includes a rotor 32 (referred to as the "first rotor") and a stator 34 (referred to as the "first stator").

[0046] The first rotor 32 is mechanically connected to at least one pump 20 to actuate the at least one pump.

[0047] The first stator 34 includes at least one phase 36, referred to as the “input phase”, and in particular includes three input phases 36.

[0048] Each input phase 36 of the motor 24 is connected to the corresponding output phase 42 of the generator 26 via an electrical connection member 27, which will be described later.

[0049] Each input phase 36 includes two windings 39, each winding having two ends. For each input phase 36, the two corresponding windings 39 are electrically connected together at a midpoint 46 through one end of the winding. Furthermore, for each winding 39, the end opposite the midpoint 46, associated with reference numeral 48, is connected to an electrical connection member 27.

[0050] like Figure 2 As shown, the end 48 of each input phase 36 is connected at vertex 49 to the end 48 of another corresponding input phase 36, such that the input phases 36 are connected together in a delta configuration. However, a star configuration of the input phases 36 can also be considered.

[0051] Advantageously, particularly for facilitating the starting of the motor 24, the actuation device 22 also includes a connecting member (not shown) configured to switch the input phase between delta and star connections.

[0052] The generator 26 is configured to draw mechanical energy from the shaft 37 (so-called "drive shaft") of the engine 18 and convert the drawn mechanical energy into electrical energy. For example, the drive shaft 37 is the low-pressure shaft of the engine 18.

[0053] The generator 26 includes a rotor 38 (referred to as the "second rotor") and a stator 40 (referred to as the "second stator").

[0054] The second rotor 38 is mechanically connected to the engine drive shaft 37 via any suitable mechanical transmission component (such as a reduction gear).

[0055] The second stator 40 includes at least one phase 42, referred to as an "output phase". More specifically, the number of output phases 42 of the second stator is equal to the number of input phases 36 of the first stator 34, specifically three output phases 42. Each output phase 42 is electrically connected to an electrical connection member 27, which is used to connect each output phase to a corresponding input phase 36.

[0056] Preferably, the generator 26 is a permanent magnet synchronous motor or an asynchronous motor.

[0057] Electrical connection member 27 is configured to electrically connect each output phase 42 to the input phase 36. Furthermore, electrical connection member 27 is configured to connect the corresponding winding 39 in series or parallel for each input phase 36 of the motor 24, depending on the current speed of the engine 18.

[0058] The electrical connection component 27 includes a control stage 50, a first-stage switch 52, a second-stage switch 54, and a third-stage switch 56.

[0059] Control level 50 is configured to control the on or off state of each of the switches 52, 54, 56 (i.e., each of the corresponding switches).

[0060] Each stage of switches 52, 54, and 56 includes the same number of switches 58 as input phase 36. In particular, each stage of switches includes three switches.

[0061] Advantageously, each switch 58 is a relay, contactor, or electronic switch to limit the risk of switch degradation over time.

[0062] Each input of the first-stage switch 52 (i.e., the input of each switch in the first-stage switch) is electrically connected to the corresponding output phase 42 of the generator 26. Furthermore, each output of the first-stage switch 52 (i.e., the output of each switch in the first-stage switch) is connected to the midpoint 46 of the corresponding input phase 36.

[0063] Each input of the second-stage switch 54 is electrically connected to the corresponding output phase 42 of the generator 26. Furthermore, each output of the second-stage switch 54 is connected to the corresponding vertex 49 of the first stator 34.

[0064] Finally, the inputs of the third-stage switch 56 are electrically connected together. Furthermore, each output of the third-stage switch 56 is connected to the midpoint 46 of the corresponding input phase 36.

[0065] The control stage 50 of the electrical connection component 27 is adapted to control the state of each of the first-stage, second-stage, and third-stage switches according to the speed of the engine 18.

[0066] For example, this speed of the engine is derived from the rotational speed of the shaft of engine 18 (especially drive shaft 37), or from information representing the flight phase of the aircraft, or from the aircraft pilot commands.

[0067] More specifically, when the speed of engine 18 is higher than a predetermined switching speed, control level 50 is configured to control:

[0068] - To put the first-stage switch 52 in the ON state (i.e., to put each switch in the first-stage switch in the ON state); and

[0069] - Put each of the second-stage switches 54 and the third-stage switches 56 into the off state (i.e., put each of the corresponding second-stage switches and third-stage switches into the off state).

[0070] In this way, for each input phase 36, the corresponding winding 39 is connected in series. Furthermore, each input phase 36 is connected to the corresponding output phase 42. Therefore, during operation, the motor 24 is driven by the generator 26 at a rotational speed proportional to the engine speed and at a first proportionality ratio k1, powered by the generator. In this configuration, the fuel flow rate delivered by the pumping system 12 is... Figure 3 The line segment 70, which is included between points 72 and 66, is shown in the diagram and will be described later.

[0071] Furthermore, when the speed of engine 18 is lower than or equal to the predetermined switching speed, control level 50 is configured to control:

[0072] - To put the first-stage switch 52 in the off state; and

[0073] - To put each of the second-stage switches 54 and the third-stage switch 56 into the ON state.

[0074] In this way, for each input phase 36, the corresponding winding 39 is connected in parallel. Furthermore, each input phase 36 is connected to the corresponding output phase 42. Therefore, during operation, the motor 24 is driven by the generator 26 at a rotational speed proportional to the engine speed and at a second proportionality ratio k2, which is twice the first proportionality ratio k1, via the power supply from the generator. In this configuration, the fuel flow rate delivered by the pumping system 12 is... Figure 3 The line segment 68, which is included between the origin and point 72, is shown in the middle.

[0075] Now refer to Figure 3 Limit the switching speed.

[0076] In this figure, curve 62 represents the variation of the fuel flow required by engine 18 as a function of the engine's speed. Curve 62 extends from point 64 (the lowest operating speed of engine 18) to point 66 (the highest operating speed).

[0077] Point 64 is associated with the following operating point: for which the required fuel flow rate to engine speed 18 ratio is higher than the required fuel flow rate to engine speed ratio associated with point 66.

[0078] As mentioned earlier, this curve 62 typically increases with speed and is generally concave.

[0079] The line 68 passing through the lowest speed operating point 64 represents the fuel flow rate supplied by the pumping system 12 when the corresponding windings 39 are connected in parallel for each input phase 36 of the motor 24.

[0080] The displacement of pump 20 is selected such that the fuel flow rate supplied by pumping system 12 at point 64 is at least equal to the fuel flow rate required by the electric motor, and the windings 39 of each input phase 36 are connected in parallel.

[0081] In addition, line 70 indicates the fuel flow rate supplied by the pumping system 12 when the windings 39 of each input phase 36 of the motor 24 are connected in series.

[0082] like Figure 3 As shown, for any speed higher than the speed associated with the intersection 72 of the straight line 70 and the curve 62, the pumping system 12 is capable of supplying fuel to the engine 18 at a flow rate higher than or equal to the flow rate required by the engine. In this pumping system, the windings 39 of each input phase 36 of the electric motor 24 are connected in series. The intersection forms a switching point, and the associated speed is referred to as the "switching speed".

[0083] As can be seen in the figure, after the switching speed is exceeded, the demand for fuel recirculation is significantly reduced when the pump 20 is driven to supply fuel to the injection device 16 at a flow rate along line 68 (arrow 76).

[0084] Alternatively, the switching speed is a predetermined speed that is different from the speed corresponding to the operating point 72 described above.

[0085] The operation of pumping system 12 will now be described.

[0086] During the operation of the engine 18, the electrical connection member 27 controls the configuration of the winding 39 of the input phase 36 according to the speed of the engine 18.

[0087] As long as the speed of engine 18 is lower than or equal to the predetermined switching speed, control stage 50 controls each switch 52, 54, 56 so that the windings 39 of each input phase 36 of motor 24 are connected in parallel, and each input phase 36 is connected to the corresponding output phase 42 of generator 26.

[0088] In this configuration, the electric motor 24 drives the pump 20 at its maximum speed based on the current received from the generator 26. In this way, by virtue of the determined pump size, the pump 20 delivers fuel to the engine 18 at a flow rate at least equal to the fuel flow rate required by the engine 18.

[0089] If the speed of engine 18 exceeds the predetermined switching speed, then control stage 50 controls each stage switch 52, 54, 56, so that the windings 39 of each input phase 36 of motor 24 are connected in series, and each input phase 36 is connected to the corresponding output phase 42 of generator 26.

[0090] In this configuration, pump 20 is driven at a speed proportional to the engine speed, but delivers fuel to engine 18 at half the flow rate that would be obtained if the windings 39 of each input phase 36 were connected in parallel. However, the supplied fuel flow rate is at least equal to the fuel flow rate required by the engine, and the fuel recirculation requirement is reduced.

Claims

1. An actuating device (12) for driving at least one fuel pump (20) of a fuel pumping system (2) for an aircraft engine (18), said actuating device (12) comprising an electric motor rotary motor (24), a generator rotary motor (26), and an electrical connection member (27), The electric rotary motor (24) is an asynchronous motor with a Darland coupling, the asynchronous motor including a first rotor (32) and a first stator (34), the first rotor being mechanically coupled to each pump (20) to actuate each pump, the first stator including at least one input phase (36), each input phase including two windings (39). The generator rotary motor (26) includes a second rotor (32) and a second stator (40), the second rotor being mechanically coupled to a shaft (37) forming a drive shaft of the engine (18), and the second stator including at least one output phase (42). The electrical connection member (27) is configured to electrically connect each output phase (42) to the input phase (36). The electrical connection member (27) is also configured to connect the corresponding winding (39) in series or in parallel for each input phase (36) according to the speed of the engine (18).

2. The actuation device (12) according to claim 1, wherein, The electrical connection member (27) is configured such that for each input phase (36) of the electric motor (24), if the speed of the motor is less than or equal to a predetermined switching speed, the corresponding winding (39) is connected in parallel, otherwise the corresponding winding is connected in series.

3. The actuation device (12) according to claim 1 or 2, wherein, The electric rotary motor (24) includes three input phases (36) connected together in a delta configuration. The two windings (39) of each input phase (36) are electrically connected together at a midpoint (46) through the ends of the two windings, and each winding (39) of a given input phase (36) is connected at the end of the winding opposite to the corresponding midpoint (46) to the corresponding winding (39) of another corresponding input phase (36) to form a vertex (49). The electrical connection component (27) includes a control stage (50), a first-stage switch (52), a second-stage switch (54), and a third-stage switch (56). Each input of the first-stage switch (52) is electrically connected to a corresponding output phase (42) of the generator rotary motor (26), and each output of the first-stage switch (52) is connected to the midpoint (46) of a corresponding input phase (36). Each input of the second-stage switch (54) is electrically connected to a corresponding output phase (42) of the generator rotary motor (26), and each output of the second-stage switch (54) is connected to a corresponding vertex (49) of the first stator (34). The inputs of the third-stage switch (56) are electrically connected together, and each output of the third-stage switch (56) is connected to the midpoint (46) of the corresponding input phase (36). The control stage (50) is configured to control the first stage switch (52) to be in the ON state and to control each of the second stage switch (54) and the third stage switch (56) to be in the OFF state when the speed of the engine (18) is higher than a predetermined switching speed. The control stage (50) is also configured to control the first stage switch (52) to be in the off state and to control each of the second stage switch (54) and the third stage switch (56) to be in the on state when the speed of the engine (18) is lower than or equal to the predetermined switching speed.

4. A fuel pumping system (12) for an aircraft engine, the pumping system (12) comprising at least one fuel pump (20) and an actuation device (12) according to any one of claims 1 to 3, wherein the first rotor (32) of the electric motor rotating motor (24) is mechanically coupled to each pump (20) to actuate each pump.

5. An aircraft incorporating a pumping system (12) according to claim 4, wherein each pump (20) is inserted between the fuel tank (14) of the aircraft and the fuel injection device (16) of the engine (18) of the aircraft, and the second rotor (38) of the generator rotary motor (26) is mechanically coupled to the shaft (37) of the engine (18).

6. A method for supplying fuel to an engine of an aircraft according to claim 5, the method comprising connecting each output phase (42) of the generator rotary motor (26) to an input phase (36) of the electric motor rotary motor (24), the supply method further comprising, for each input phase (36), connecting the corresponding windings (39) in series or in parallel according to the speed of the engine.

7. The method for supplying fuel to an engine (18) according to claim 6, the method comprising, for each input phase (36), connecting the corresponding windings (39) in parallel if the speed of the engine is less than or equal to a predetermined switching speed, and otherwise connecting the corresponding windings in series.

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