Method of activating an electric motor in a hybrid power plant of a multi-engined aircraft, and an aircraft

Abstract

A method of driving rotation of a rotor of an aircraft, said aircraft having at least two fuel-burning engines and an electric motor suitable for driving rotation of said rotor. Said rotor is driven by using said engines together. An authorization is generated only during at least one predetermined stage of flight, said authorization authorizing the use of the electric motor in order to drive said rotor in rotation. While said authorization is valid and if one of said engines has failed, then an operation order is generated to require said electric motor to operate. While said operation order is valid, said rotor is driven by each engine that has not failed together with said electric motor.

Claims

1. A method of driving rotation of a rotor of an aircraft, the aircraft having at least two fuel-burning engines and an electric motor suitable for driving rotation of the rotor, the aircraft further having a regulator in communication with the engines and the electric motor, the method comprising: driving the rotor by using the engines together; generating, by the regulator, an authorization only during the aircraft operating in one of at least one predetermined stage of flight, the authorization authorizing the use of the electric motor to drive the rotor in rotation; generating, by the regulator, while the authorization is valid, an operation order to require the electric motor to operate if one of the engines is considered as failed; driving, while the operation order is valid, the rotor by using each engine that is not considered as failed and by using the electric motor; and inhibiting, by the regulator, the electric motor from being used to drive the rotor other than when both conditions of (i) the aircraft is operating in one of the at least one predetermined stage of flight and (ii) one of the engines is considered as failed occur concurrently.

2. The method according to claim 1, wherein the regulator has one management system per engine and an avionics system communicating with the management systems, the avionics system configured to generate the authorization and transmit the authorization to each management system, and at least one of the management systems configured to generate the operation order and transmit the operation order to the electric motor.

3. The method according to claim 1, wherein each predetermined stage of flight is a stage of flight that requires a given power for driving the rotor, the given power being less than the maximum power delivered by the engines when one of the engines is considered as failed.

4. The method according to claim 1, further comprising inhibiting the authorization from being generated while the aircraft is standing on the ground.

5. The method according to claim 1, wherein the at least one predetermined stage of flight includes a stage of flight at low speed during which the aircraft has a speed of advance less than a threshold speed of advance.

6. The method according to claim 5, wherein a current speed is determined for the speed of advance of the aircraft and the regulator compares the current speed with the threshold speed of advance, the regulator generating the authorization when the current speed is less than the threshold speed of advance.

7. The method according to claim 1, wherein a predetermined stage of flight is a stage of flight with little power margin during which at least one engine presents a power margin relative to a predetermined power limit that is less than a power threshold.

8. The method according to claim 1, wherein a predetermined stage of flight is a single-engined stage of flight during which only a single one of the engines is in operation and is operating at a contingency overpower rating usable for only a predetermined duration.

9. The method according to claim 1, wherein an engine is considered as failed when the engine is delivering no power.

10. The method according to claim 1, wherein an engine is considered as failed when the engine is stopping or has stopped.

11. The method according to claim 1, wherein an engine is considered as failed when the engine is idling.

12. The method according to claim 1, wherein an engine is considered as failed when the power developed by the engine is frozen as a result of a malfunction of a system for regulating the flow of fuel and when the torque developed by the engine is less than a torque threshold.

13. The method according to claim 1, wherein an engine is considered as failed when the difference between the torque being developed by one engine and the torque being developed by another one of the engines is greater than a predetermined difference.

14. An aircraft comprising: at least one rotor; at least two fuel-burning engines suitable for driving the rotor in rotation; an electric motor suitable for driving the rotor in rotation; and a regulator in communication with the engines and the electric motor, the regulator configured to drive the rotor by using the engines together; generate an authorization only during the aircraft operating in one of at least one predetermined stage of flight, the authorization authorizing the use of the electric motor to drive the rotor in rotation; generate, while the authorization is valid, an operation order to require the electric motor to operate if one of the engines is considered as failed; drive, while the operation order is valid, the rotor by using each engine that is not considered as failed and by using the electric motor; and inhibit the electric motor from being used to drive the rotor other than when both conditions of (i) the aircraft is operating in one of the at least one predetermined stage of flight and (ii) one of the engines is considered as failed occur concurrently.

15. The aircraft according to claim 14, wherein the regulator includes one management system per engine, each management system configured to control one engine, the regulator further including an avionics system communicating with the management systems, the avionics system configured to generate the authorization and transmit the authorization to each management system, and at least one of the management systems configured to generate the operation order and transmit the operation order to the electric motor.

16. The aircraft according to claim 15, wherein the regulator includes at least one member selected from the following list: a measurement system for determining a speed of advance of the aircraft, one measurement device per engine for determining the torque being developed by the engine, one measurement device per engine for determining the power being developed by the engine, one sensor per engine for determining the speed of rotation of a member of the engine, and a touch device for determining whether the aircraft is standing on ground.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The invention and its advantages appear in greater detail from the context of the following description of examples given by way of illustration and with reference to the accompanying figures, in which:

(2) FIG. 1 is a diagram showing an aircraft of the invention; and

(3) FIG. 2 is a diagram showing the method of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(4) Elements present in more than one of the figures are given the same references in each of them.

(5) FIG. 1 shows an aircraft 1 of the invention.

(6) The aircraft 1 has an airframe 200 standing on ground 400 (which may be solid or liquid), via landing gear 300.

(7) The landing gear 300 may comprise skid landing gear or indeed landing gear with wheels or skis, for example. Landing gear 300 could also include buoyancy means (floats).

(8) The airframe 200 carries at least one rotor 2. Such a rotor 2 may be a main rotor 3 contributing to providing the aircraft with lift and possibly also propulsion. A rotor 2 may also comprise a rotor 4 for controlling yaw movement of the aircraft.

(9) In FIG. 1, the aircraft is a rotorcraft, and in particular a helicopter having a main rotor 3 and a yaw movement control rotor 4.

(10) In order to drive each rotor, the aircraft has a power plant with at least two fuel-burning engines 10.

(11) By way of example, each fuel-burning engine is mechanically connected to a main power transmission gearbox 5. The main gearbox 5 sets a rotor mast in rotation that drives the main rotor 3 in rotation. Furthermore, the main gearbox 5 may set a tail power transmission gearbox 6 in rotation, thereby driving rotation of the yaw movement control rotor 4.

(12) Such a fuel-burning engine 10 may be a turboshaft engine, for example. The engine then comprises a gas generator 13 followed by a power assembly 14. The power assembly 14 has at least one turbine mechanically driving the main gearbox 5.

(13) Furthermore, the rotor has at least one electric motor 50. In particular, the aircraft has one electric motor 50. Such an electric motor 50 may be any kind of motor capable of using electricity to drive at least one rotor.

(14) By way of example, each electric motor 50 is mechanically connected to the main gearbox 5.

(15) By way of illustration, the electric motor may include an electronic system (not shown), together with a stator 51 and a rotary member 52.

(16) Furthermore, the aircraft includes a regulator device 100.

(17) The function of the regulator device 100 is to control the fuel-burning engines 10 and the electric motor 50 by applying the method of the invention.

(18) The regulator device thus has one management system 20 per engine 10. A management system 20 may be of the FADEC type. Thus, a first engine 11 is controlled by a first management system 21, with the second engine 12 being controlled by a second management system 22.

(19) Under such circumstances, the management system may include a management computer 23 and a fuel metering unit 26.

(20) By way of example, such a management computer 23 possesses a processor 24 or the equivalent that executes instructions stored in a memory unit 25. Conventionally, the management computer applies regulation relationships stored in the memory unit, in particular for controlling the fuel metering unit of the associated engine.

(21) Each management system 20 may be connected directly or indirectly to measurement means 40 monitoring the operation of the associated engine, or indeed to measurement systems 35 of the aircraft.

(22) Thus, each management system may be connected over a wired or wireless connection to a sensor 41 measuring a speed of rotation Ng of the gas generator 13 of the engine it controls.

(23) Furthermore, each management system may be connected by a wired or wireless connection to a member 42 determining torque and/or power as developed by the power assembly 14 of the engine it controls. For example, a torque meter can be used to measure the torque developed by the power assembly 14 of the controlled engine. Furthermore, a conventional system serves to measure the speed at which the power assembly 14 is being driven in rotation. The power developed by the power assembly 14 is then equal to the product of the measured torque multiplied by the measured rotary drive speed at the point where the torque is measured.

(24) Under such conditions, the management systems of the engines may conventionally communicate with each other in order to exchange information about the operation of said engines.

(25) Furthermore, the regulator device 100 includes an avionics system 30 communicating via a wired or wireless connection with each engine 10 and with the electric motor 50.

(26) By way of example, the avionics system has at least one computer that is referred to for convenience as the avionics computer 31.

(27) Furthermore, the avionics system includes various measurement systems 35 for determining information about the operation of the aircraft.

(28) In particular, the avionics computer may communicate with a measurement system 36 suitable for determining the speed of advance of the aircraft. In particular, the measurement system 36 may include an air data computer (ADC) system and/or a positioning system, e.g. of the type known by the acronym GPS.

(29) The avionics computer may also communicate with a touch device 37. Such a touch device 37 serves to evaluate whether the aircraft is standing on the ground.

(30) By way of example, a touch device 37 may comprise a system for determining the force exerted on landing gear 300. If the force is less than a threshold, then the touch device 37 deduces that the aircraft is flying, i.e. that the aircraft is not standing on the ground 400.

(31) Furthermore, the avionics system may include one control selector 38 per engine. For example, a selector may be a selector having three positions, respectively for requiring an engine to operate, or to stop, or to idle.

(32) Under such circumstances, the aircraft 1 applies the method of the invention as shown in FIG. 2.

(33) During an initial step STP1, each rotor 2 is set into motion by the engines.

(34) The first engine 11 and the second engine 12 act together to drive the rotors 2 via the gearboxes 5 and 6. The management systems 20 control the fuel metering units 26 by applying appropriate regulation relationships.

(35) In contrast, the electric motor is not in operation in motor mode during this initial step STP1. The rotary member 52 therefore does not drive the rotors 2. The electric motor might possibly take energy from the main gearbox 5 by operating in an alternator mode.

(36) During a step STP2 of estimating the stage of flight, an authorization is generated to authorize using the electric motor 50 in order to drive rotation of the rotors 2, only if the aircraft is operating in a predetermined stage of flight.

(37) Issuing the authorization does not suffice to enable the electric motor to be used to drive the rotors, but it constitutes a prerequisite for such use.

(38) For example, the avionics system 30 determines the current stage of flight of the aircraft using the measurement systems 35, and it compares this current stage of flight with predetermined stages of flight.

(39) If the aircraft is flying in one of the predetermined stages of flight, the avionics system transmits said authorization to each management system 20.

(40) In this method, at least one predetermined stage of flight may be a stage of flight that requires a given power for driving the rotors 2, this given power being greater than the maximum power delivered by the engines 10 together in the event of a failure of one of said engines 10.

(41) Consequently, a predetermined stage of flight is a stage of flight during which each engine in isolation is not sufficient for obtaining the given power needed to maintain the current mission.

(42) In addition, authorization may be inhibited when the aircraft 1 is standing on the ground 400. Consequently, in this option, a predetermined stage of flight is a stage that occurs while in flight, in the strict meaning of the term flight, i.e. above the ground.

(43) Under such circumstances, the avionics computer 31 interrogates the touch device 37 to determine whether the aircraft is standing on the ground.

(44) For example, at least one predetermined stage of flight comprises a stage of flight at low speed. A stage of flight is said to be at low speed when the aircraft is moving at a speed of advance less than a threshold speed of advance.

(45) Under such circumstances, the avionics computer 31 interrogates the measurement system 36 to determine a current speed value for the speed of advance of the aircraft 1.

(46) The avionics computer 31 compares this current speed with a threshold speed of advance stored in a memory of the avionics computer 31. The authorization is then given by the avionics computer 31 if the current speed is less than the threshold speed of advance.

(47) Furthermore, said at least one predetermined stage of flight may comprise a stage of flight with little power margin. A stage of flight is said to be with little power margin when at least one engine 10 presents a power margin relative to a predetermined power limit that is less than a power threshold.

(48) Each management system transmits to the avionics system a current power that is being developed by the corresponding engine. Furthermore, the management system can transmit a power limit to be complied with for the current operating rating of the engine.

(49) Under such circumstances, the avionics computer 31 deduces a current power margin therefrom for each engine. The avionics computer 31 then compares this current power margin with a stored power limit. If the current power margin is less than the power limit, then the avionics computer issues said authorization.

(50) In addition, said at least one predetermined stage of flight may include a single-engined stage of flight. A stage of flight is said to be single-engined when only one engine 10 is in operation, with the sole engine 10 operating at a contingency overpower rating, which contingency overpower rating can be used for only a predetermined duration.

(51) Under such circumstances, the management systems inform the avionics system that an engine has failed. The management system of the engine that is in operation can specify which operating rating is in use.

(52) Specifically, the engine may operate at any one of a plurality of different overpower ratings.

(53) Under such circumstances, the avionics system issues authorization to use the electric motor if the engine 10 in operation is using a particular contingency overpower rating, namely a contingency overpower rating that can be used only for a predetermined duration.

(54) In a step STP3 of estimating the health of the engines, it is determined whether an engine needs to be considered as failed.

(55) If an engine is considered as failed and if said authorization has been given, then an operation order is generated to require the electric motor 50 to operate.

(56) In contrast, if an engine 10 is considered as failed and if said authorization has not been given, the operation order is not issued.

(57) For example, the operation order is issued by a management system 20. The operation order may be issued either by the management system considering the failure of an engine, or by the other management system, for example.

(58) This operation order is transmitted during a hybridizing step STP4 to the electric motor. The electric motor then operates in motor mode in order to contribute to driving rotation of the rotors 2.

(59) The operation order may be transmitted directly from a management system to the electric motor, or it may be transmitted indirectly via the avionics system 30.

(60) During the step STP3 of estimating the health of the engines, an engine 10 may be considered as failed when the engine 10 is not delivering any power.

(61) For example, the management system of an engine determines the current power being developed by that engine by interrogating the measurement device 42.

(62) If the current power is zero and if said authorization has been issued, the management system delivers the operation order.

(63) An engine 10 may also be considered as failed when the engine 10 is stopping or has stopped, whether voluntarily or involuntarily.

(64) By way of example, a management system may detect that the gas generator of a turboshaft engine or the crankshaft of a piston engine is not moving on the basis of information coming from a sensor 41.

(65) Such a failure may be detected in conventional manner, and may give rise to a FAIL DOWN alarm being issued.

(66) If a pilot operates the selector 38 in order to stop an engine voluntarily, the management system of that engine stops the associated engine. Furthermore, the management system issues the operation order if said authorization has been issued.

(67) An engine can also be considered as failed when the engine is idling.

(68) By way of example, a management system may detect that the gas generator of a turboshaft engine is rotating at a predetermined idling speed.

(69) Such a failure may be detected in conventional manner, and may give rise to a FAIL IDLE alarm being issued.

(70) If a pilot operates the selector 38 to cause an engine to idle, the management system of that engine then causes the associated engine to idle. Furthermore, the management system issues the operation order if said authorization has been issued.

(71) In addition, an engine 10 is considered as failed if the power developed by the engine 10 is frozen as a result of a malfunction of a system 23, 36 for regulating the fuel flow rate and if the torque developed by the engine 10 is less than a torque threshold.

(72) The management system of an engine can thus identify that the power developed by the neighboring engine has frozen when the level of torque exerted by the neighboring engine is less than a stored torque threshold. The management system then issues the operation order if said authorization has been issued.

(73) Such a failure can be detected in the usual manner, and may give rise to a FAIL FREEZE alarm being issued.

(74) An engine 10 is also considered as failed when the difference between the torque being developed by one engine 10 and the torque being developed by another engine 10 is greater than a predetermined difference.

(75) The management systems communicate with each other in order to compare the torque developed by the engines. If a large difference is identified between these torques, and if said authorization has been issued, the management system then issues the operation order.

(76) Naturally, the present invention may be subjected to numerous variations as to its implementation. Although several implementations are described, it will readily be understood that it is not conceivable to identify exhaustively all possible implementations. It is naturally possible to envisage replacing any of the means described by equivalent means without going beyond the ambit of the present invention.