METHOD AND DEVICE FOR OPTIMIZING THE ELECTRICAL ENERGY OF A HYBRID-ENGINED AIRCRAFT

Abstract

Method for optimizing available electrical energy during a flight of an aircraft (100) comprising one or more turbomachines hybridized with one or more reversible electric motors, wherein the method includes in said flight the integration of at least one glide phase (31, 41) with one or more of said turbomachines switched off, for which an autorotation of a fan, or low-pressure turbine, (1) or of a rotating wing of each of said turbomachines drives said reversible electric motors (4) operating as electrical generators and supplying electrical energy (5) during said glide phase.

Description

Title of the invention: METHOD AND DEVICE FOR OPTIMIZING THE ELECTRICAL ENERGY OF A HYBRID-POWERED AIRCRAFT Technical field

[0001] The invention relates to the field of motorization of heavier-than-air aircraft for transporting objects and / or people from an origin to a destination by air. To do this, a heavier-than-air aircraft needs to be equipped with a certain number of engines, the principle of which is to generate the thrust necessary to cause and maintain the lift of the aircraft throughout its use.

[0002] Currently, the use of electrical energy for the motorization of airplanes or helicopters represents a major challenge in the years to come, with a view to reducing harmful emissions and the consumption of non-renewable sources, in particular fossil fuels. Prior art

[0003] Hybrid or electric motorization for aircraft is being studied in particular in all aeronautical companies around the world. The main emerging concepts are based on the addition of an electric motor to ensure the mechanical transformation necessary for the propulsion of the aircraft, drawing its necessary electrical energy from on-board storage modules, such as batteries.

[0004] These batteries can thus store electrical energy during use of the device to supply energy to the associated electric motor. They must be charged before use and their charging capacity is directly dependent on their dimensions. Technical problem

[0005] Currently, a major problem is that storing electrical energy resources in batteries is too cumbersome: an electric motor has the major drawback of requiring a very large quantity of batteries, the mass of which is very substantial. In the case of aircraft, mass is a critical factor to take into account, because its influence is of primary importance on the quantity of energy necessary for its transport in the air. It is for this reason that the elements constituting an aircraft (of which the engines are part) are constantly optimized to minimize their mass. Concerning batteries, some studies show that with current technologies, the equivalent in weight of a second aircraft connected to the first would be required to power the engines of the latter, which is not profitable. Aircraft such as transport planes or helicopters therefore remain dependent on the use of thermal engines such as turbomachines.

[0006] However, there are studies of electrically powered aircraft such as in document US20150097079 A1 which provide for battery recharging in flight phases where the electric thrusters become wind turbines. In this document, the route that the aircraft can follow depends on the atmospheric / climatic conditions, the altitude regain being done in particular in an ascending air column when such an air column is present. It is therefore not suggested in this document to carry out an imposed route by repeatedly chaining sequences comprising a glider flight phase (energy recovery) followed by a powered flight phase for altitude regain independently of the atmospheric conditions on the route of the aircraft. The aircraft described is therefore not really usable for commercial flights.

[0007] Document FR3003845A1 describes an aircraft equipped in particular at the wingtips with turbine-type electric generators (known under the English name Ram Air Turbine RAT) which make it possible to supply electrical energy to power electrical or electronic equipment of the aircraft. These generators cannot, however, participate in generating the thrust allowing the aircraft to fly. Statement of the invention

[0008] In view of the prior art and to address this problem of insufficient load capacity, the present disclosure proposes an aircraft with hybrid turbomachines associated with a load module in glider mode and a method for optimizing the energy consumption of this aircraft which comprises phases of recovery of electrical energy within the hybrid turbomachine of the aircraft and phases of restitution of said electrical energy in addition to the thermal energy supplied by the turbomachines.

[0009] More specifically, the present invention proposes a method for optimizing available electrical energy during a flight of an aircraft which comprises one or more hybridized turbomachines with one or more reversible electric motors, the method comprising in said flight the integration of at least one gliding flight phase with one or more of said turbomachines switched off for which an autorotation of a fan or a rotating wing of a said turbomachine drives said reversible electric motor associated with this turbomachine, said reversible electric motor operating as an electric generator and providing electrical energy during said gliding flight phase.

[0010] This makes it possible in particular to charge batteries storing said electrical energy, in particular during the descent phase of the aircraft.

[0011] Advantageously, the flight of the aircraft comprising at least one climb phase, one level flight phase and one descent phase, one or more gliding flight phases are integrated into the descent phase.

[0012] This makes it possible to reduce the aircraft's consumption of fuel for supplying the turbomachines, particularly during the aircraft's descent phase.

[0013] Advantageously, the flight of the aircraft comprising at least one climb phase, one level flight phase and one descent phase, one or more gliding flight phases are integrated into the level flight phase. This makes it possible in particular to maintain the charge of the electrical energy storage batteries.

[0014] Preferably, the electrical energy accumulated during the gliding flight phase(s) is at least partly stored and used to provide additional power to the turbomachine(s) during flight phases that consume a lot of energy. For example, this makes it possible to provide additional energy during a takeoff phase of a subsequent flight.

[0015] The electrical energy generated during the gliding flight phase(s) can in particular be used to compensate for the shutdown of the turbomachine(s) and to power electrical or electronic equipment of the aircraft with the turbomachine(s) stopped.

[0016] The invention further relates to an aircraft suitable for implementing the method of the invention and which comprises at least one reversible electric motor connected directly or indirectly to a turbine shaft of a turbomachine and to an on-board energy storage device, the reversible electric motor and the turbomachine constituting a hybrid turbomachine.

[0017] The shaft may be a low pressure turbine shaft in a turbojet or a free turbine shaft in a turboshaft or turboprop engine.

[0018] Said reversible electric motor can be positioned directly in continuity with said turbine shaft.

[0019] According to an alternative embodiment, said reversible electric motor can be positioned outside the turbomachine and mechanically connected to said turbine shaft.

[0020] According to a particularly advantageous embodiment, the electric motor is configured to be able to drive a fan, a propeller or a rotary wing driven by the turbomachine and provide thrust to the aircraft. Brief description of the drawings

[0021] Other characteristics, details and advantages of the invention will appear on reading the detailed description below of non-limiting exemplary embodiments, and on analyzing the appended drawings, in which:

[0022] [Fig. 1] shows a schematic diagram of a hybridized turbomachine in an operating mode where a reversible electric motor provides mechanical power to the turbomachine;

[0023] [Fig.2] shows a schematic diagram of a hybridized turbomachine in an operating mode where a reversible electric motor receives mechanical power from the turbomachine and transforms it into electrical energy;

[0024] [Fig.3] shows an example of flight with gliding phases;

[0025] [Fig.4A] and [Fig.4B] show diagrams of a flight comprising glide phases of the present disclosure.

[0026] [Fig.5] shows a diagram of application to a helicopter. Description of the embodiments

[0027] The following drawings and description contain elements which may not only serve to better understand the present invention, but also contribute to its definition, where appropriate.

[0028] Reference is now made to [Fig. 1] which schematically represents a turbojet-type turbomachine of an aircraft 100, said turbomachine comprising a low-pressure turbine 1, a high-pressure compressor 2 with combustion chamber, a shaft 3 of the low-pressure turbine also called fan. To produce a hybrid turbomachine, a reversible electric motor 4 is arranged on the shaft of said turbine. The motor is configured to be able to operate as an electric motor M in order to drive the turbomachine and to increase the available thrust power of the engine when the reversible electric motor operates in engine mode powered by an electrical source 6. In an alternative embodiment, the reversible electric motor can be connected to a free turbine shaft in a turboshaft or turboprop.

[0029] In the context of the present disclosure according to the example of [Fig.2], the rotational kinetic energy of the engines and in particular of their fan 1, maintained by the movement of the aircraft 100, can then be recovered by the reversible electric motor 4 which then operates in generator mode G, alternator or dynamo for example. The reversible electric motor 4, again according to the example positioned at the main shaft of the engine or low-pressure turbine shaft to which the fan 1 is connected, can then act as a source of electrical energy which can be recovered to be at least partly stored in a storage device 6 for example in the form of on-board batteries and possibly at least partly used on the aircraft to power electrical or electronic devices of the aircraft.

[0030] The stored electrical energy can, in the context of the present disclosure, be directly reinjected subsequently into the reversible electric motor 4 to increase the thrust power of the turbomachine with which it is associated, for example for a progressive restart control.

[0031] The present disclosure thus proposes an energy recovery technology that makes it possible to convert part of the kinetic energy of the fan 1 of the turbomachine in a “free rotation” situation into another energy, here electrical, rather than dissipating it in pure loss in the form of thermal energy. This free rotation situation corresponds to an autorotation of the fan of an aircraft engine or an autorotation of the rotary wing of a helicopter which then functions as a wind turbine. This is also referred to as a “windmilling” phase in English. The combustion chamber 2 of the engine or of the turbomachine is then switched off and the fan drives the reversible electric motor which functions as an electric generator 4.

[0032] Free rotation can be achieved when the aircraft voluntarily enters a flight situation without fueling its engines. In this case, the fuel supply is stopped, and the combustion chamber of each engine is therefore extinguished. The aircraft then begins a slow and controlled descent slowed by the natural lift of the aircraft. This situation amounts to making the aircraft glide over a certain distance.

[0033] The energy source of the turbomachines in [Fig.l] is therefore mixed: fuel supplying the combustion chamber 2 with its compressors and additional electrical energy, typically stored in the battery storage device 6 for the electrical assistance provided by the reversible electric motor 4 during certain flight phases where additional power is necessary.

[0034] For example, the electrical energy recovered during a descent phase of a first flight can be used to provide additional power during the takeoff of the next flight.

[0035] The electric machine of the reversible electric motor type in generator mode can be positioned directly within the low pressure turbine shaft which is connected to the fan shaft either directly or by a reducer. Similarly, in the case where the fan is replaced by a propeller of a turboprop or a rotary wing of a helicopter, the reversible electric motor can be connected to the shaft which will drive the propeller or the rotary wing directly or through an angle transmission and a reducer. This electric machine can also be connected to a free turbine shaft in a turboshaft or turboprop. The reversible electric motor operating in generator mode is driven by the rotation of the fan during an autorotation phase (windmilling in English) to exploit the rotation of the latter when this mode is activated. The electric machine reversible can also be positioned outside the engine and connected by a secondary shaft and a cascade of gears to the low pressure turbine shaft which itself drives the fan, a propeller shaft for a turboprop or the shaft of a rotary wing in the case of a helicopter, depending on the configuration of the aircraft.

[0036] [Fig. 5] represents in particular the case of a helicopter 60 comprising a turbine engine 61, driving a main propeller 62 through a right-angle gearbox 63 and a shaft 63a for which the reversible electric motor 64 is coupled at the output of the turbine engine on the axis of the gearbox at the level of an output shaft of an anti-torque rotor 65. The reversible motor 64 is associated with an electric accumulator 66 possibly supplying electrical or electronic equipment 67 of the helicopter as well as possibly a computer 68 for controlling the turbine engine 61.

[0037] [Fig. 3] illustrates an example of adaptation of a flight cycle of an aircraft according to the present disclosure, with a phase of climbing to cruising altitude, a flight maintained in an air corridor, and a descent phase in anticipation of a landing. This adaptation proposes to take advantage of the cruising and descent phases to chain glide cycles, during which the aircraft will be able to recover energy by gliding.

[0038] Thus, associated with the electrical energy recovery and supply system, a new piloting mode is proposed to maximize the electrical energy recovery phases throughout the flight. According to the example, this mode may comprise, in a stabilized flight phase 20 after a climb phase 10, the integration of flight phases 40 provided with sequences represented in double dotted lines and comprising phases of gliding flight of the aircraft 41 during which the engines are put into free rotation, which produces energy recovery phases with charging 44 of the batteries, causing the aircraft to follow a trajectory of slight altitude drop but controlled by the studied aerodynamic profile of the fuselage and the wings of the aircraft. Between each energy recovery phase, a phase of restarting the turbomachines 42 and of progressive ascent to altitude 43 of the aircraft may be carried out to regain at least part of the lost altitude.If the turbomachine has an electric starter, part of the electrical energy recovered and charged into the batteries during a recovery phase can be used to restart the turbomachine. During the phases of gradual ascent to altitude of the aircraft, the turbomachines can then possibly be partly driven by the electrical energy 45 recovered by the energy recovery module. In this configuration the reversible electric motor injects mechanical power into the LP (low pressure) shafts (or the fan shafts) of the turbomachines. The electric motor then provides electrical assistance to . the propulsion of hybrid turbomachines. During the phases of gradual ascent to altitude 43 of the aircraft, the turbomachines can be supplied with fuel so as to provide a nominal power corresponding to their maximum efficiency, which makes it possible to optimize fuel consumption during each phase of ascent to altitude. The trajectory of the ascent to altitude, and in particular the angle of climb, can be adapted so that the speed of the aircraft remains within a certain range while the turbomachines operate at nominal power with or without electric propulsion assistance. The turbomachines can therefore operate intermittently and essentially at nominal power during a flight, which, taking into account the fact that electric propulsion assistance is possible during most or all of the phases of ascent to altitude, can make it possible to improve the overall efficiency of the flight and therefore fuel consumption.

[0039] In this operating mode, it is necessary to take advantage of the phases of flight at cruising altitude to chain together gliding flight cycles, during which the aircraft will be able to generate energy by gliding. A cruising phase is translated here by a level flight phase. This assumes that after each gliding phase which constitutes a gentle descent integrated into the level flight phase, the turbomachine will be restarted and assisted by the electric motors to allow the aircraft to regain altitude: return to the nominal cruising altitude, or even to an altitude which decreases a little with each cycle or which is adapted according to the weather conditions for example, possibility of climbing higher in the event of ascending winds. A phase of flight at cruising altitude with gliding flight cycles is therefore carried out by changes in altitude back and forth between two levels.

[0040] To ensure energy savings, it is possible to propose the addition of an on-board energy consumption calculator, responsible for estimating the energy savings based on what it records during the previous plateau / glide phases. This would provide predictive consumption for the following flight phases and could even propose an adaptation of the altitude stages to be adopted in order to maximize the energy savings, particularly with a view to minimizing consumption. Because atmospheric conditions, flight location, air corridor, weather, etc. can have an impact on the efficiency of the solution, and the flight trajectory by successive stages could therefore be optimized based on in-flight measurements.

[0041] [Fig.4A] thus provides a level flight 20a which includes ascents 430 of the aircraft 100 towards a constant altitude 50 in the case of appropriate flight conditions.

[0042] In the case of decreasing level flight, the energy thus recovered by replacing a level flight at constant altitude with a decreasing level flight contributes to the overall saving of energy required on board the aircraft. It can also to power other life-related components on board the aircraft, such as on-board electronic equipment. Energy recovery piloting also involves making the most of the aircraft's overall aerodynamics to maximize the gliding flight phases, during which the gliding energy recovery module generates electrical energy, which is then stored in an energy storage device such as batteries, by exploiting the free rotation of the fans or rotary wings.

[0043] [Fig.4B] corresponds to such a case of flight in decreasing levels 20b is carried out, levels of decreasing altitudes 51, 52, 53 being carried out, for example before a descent phase, the ascent phases 431 being shorter in this case of decreasing levels.

[0044] The solution may also provide adaptive levels which may be determined at the end of each energy recovery phase, or glide phase, taking into account in particular a measurement or estimation of the recovered electrical energy. For example, if this has increased compared to the previous recovery phase, the power supplied to the electrical assistance may be increased accordingly during the gradual ascent to altitude of the aircraft, and therefore the altitude regained before the next glide phase may be increased. And conversely if the recovered electrical energy has decreased.

[0045] Similarly, in the descent phase 30, the utility of the device is maximized, the turbomachine(s) can be stopped to perform one or more gliding flight phases 31 shown diagrammatically in dotted lines and in which the reversible electric motors operate as a generator to produce electrical power 44 and recharge the batteries, for example, with a view to providing power during a subsequent takeoff or during the landing phase.

[0046] The present disclosure thus proposes a method for optimizing available electrical energy during a flight of an aircraft comprising one or more hybridized turbomachines with one or more reversible electric motors, this method comprising during a flight such as a commercial flight of the aircraft the integration of at least one gliding flight phase 31, 41 with one or more of said turbomachines switched off for which an autorotation of the fan(s) 1 of said turbomachines of the aircraft drives one or more of said reversible electric motors 4 operating as electrical generators and providing electrical energy 5 during said gliding flight phase.

[0047] The flight of the aircraft comprising at least one climb phase 10, one level flight phase 20 and one descent phase 30, one or more gliding flight phases 31 are integrated into the descent phase.

[0048] The flight of the aircraft comprising at least one climb phase, one level flight phase and one descent phase, one or more gliding flight phases 41 are integrated into the level flight phase, the gliding flight phases being able in this case to be followed by climb flight phases 43 with possible participation of the reversible electric motor(s) in the thrust of the aircraft's turbomachine(s).

[0049] The electrical energy 5 accumulated during the gliding flight phase(s) can be at least partly stored, for example in batteries 6 and used to provide additional power 7 to the turbomachines 2 during flight phases that consume a lot of energy.

[0050] The electrical energy 5 generated during the gliding flight phase(s) is used to compensate for the shutdown of the turbomachine(s) and to power electrical or electronic equipment 8 of the aircraft 100, with the turbomachine(s) stopped.

[0051] Of course, the energy storage device 6 can be recharged each time the aircraft stops to benefit from maximum power on takeoff, the electrical energy recovered during the descent phases of the aircraft however making it possible to reduce the need to recharge the storage device.

[0052] The invention is not limited to the examples shown and, as stated above, the reversible electric motor may be located outside the turbomachine or on a shaft different from the shaft of the low pressure turbine driving the fan.

Claims

Claims

1. Method for optimizing available electrical energy during a flight of an aircraft (100) comprising one or more hybridized turbomachines with one or more reversible electric motors, characterized in that the method comprises in said flight the integration of at least one gliding flight phase (31, 41) with one or more of said turbomachines switched off for which an autorotation of a low-pressure turbine (1) or of a rotary wing of a said turbomachine drives said reversible electric motor (4, 64) associated with this turbomachine, said reversible electric motor operating as an electric generator (G) and providing electrical energy (5) during said gliding flight phase, and for which the flight of the aircraft comprising at least a climb phase, a level flight phase and a descent phase, one or more gliding flight phases (41) are integrated into the level flight phase.

2. Optimization method according to claim 1, for which the flight of the aircraft comprising at least a climb phase (10), a level flight phase (20) and a descent phase (30), one or more gliding flight phases (31) are integrated into the descent phase.

3. Optimization method according to any one of the preceding claims, for which the electrical energy (5) accumulated during the gliding flight phase(s) is at least partly stored (6) and used to provide additional power (7) to the turbomachine(s) (2) during flight phases that consume a lot of energy.

4. Optimization method according to any one of the preceding claims, for which the electrical energy (5) generated during the gliding flight phase(s) is used to compensate for the shutdown of the turbomachine(s) and to power electrical or electronic equipment (8) of the aircraft with the turbomachine(s) stopped.

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