Monitoring system for monitoring a hybrid rotorcraft power plant, rotorcraft and associated method

Abstract

The present invention relates to a monitoring system (1) for monitoring a hybrid power plant (2) of a rotorcraft (3) comprising at least one rotor (4), said hybrid power plant (2) comprising an electric motor (5) comprising a first drive shaft (15), a heat engine (8) comprising a second drive shaft (18) and a power transmission box (9). The monitoring system comprising at least a first sensor (16, 17, 19) measuring first torque information representative of a first engine torque C1 transmitted by the first drive shaft (15) to a first input shaft (10) of the power transmission box (9) and a controller (31) comparing said first engine torque C1 with a first limit value VL1. Abstract figure: figure 1

Description

Title of the invention: Monitoring system for monitoring a hybrid rotorcraft power plant, rotorcraft and associated method

[0001] The present invention relates to the field of hybrid rotorcraft power plants comprising both a thermal engine and an electric motor capable of transmitting engine torque in parallel respectively to input shafts of a power transmission box. An output shaft of the power transmission box is connected to at least one rotor and allows it to be driven in rotation.

[0002] Furthermore, the term “rotor” may designate in particular a lift rotor, an anti-torque rotor for controlling the yaw movements of the rotorcraft or a propulsive or tractive propeller.

[0003] The invention proposes a solution for monitoring the mechanical behavior of such a hybrid power plant in order to detect excessive torques when the thermal and electric motors operate simultaneously, and to protect the power transmission box in the event of a breakdown or exceeding of limits.

[0004] Exceeding torque limits is indeed an undesirable situation which can cause damage to the power transmission box.

[0005] The present invention therefore aims to propose an innovative monitoring system aimed at protecting a power transmission box set in motion by a hybrid power plant.

[0006] The invention therefore relates to a monitoring system for monitoring a hybrid rotorcraft power plant comprising at least one rotor, the hybrid power plant comprising: - an electric motor electrically connected by an electrical connection to at least one source of electrical energy, the electric motor comprising a first drive shaft, - a heat engine comprising a second drive shaft, and - a power transmission box comprising: • a first input shaft connected by a first mechanical connection to the first drive shaft, • a second input shaft connected by a second mechanical link to the second drive shaft, and • an output shaft connected by a third mechanical connection to said at least one rotor.

[0007] According to the invention, such a monitoring system is remarkable in that it comprises: - at least one first sensor measuring a first torque information representative of a first engine torque Cl transmitted by the first engine shaft to the first input shaft, - a memory storing a first limit value VL1 relating to the first motor torque Cl, and - a controller comparing the first engine torque Cl with the first limit value VL1 and accordingly controlling a first reversible transmission device configured to transmit, and alternatively, prevent the transmission of the first engine torque Cl, the first reversible transmission device being controlled to allow the first motor shaft to rotate the first input shaft when the first engine torque Cl is less than the first limit value VL1 and to prevent the first motor shaft from rotating the first input shaft when the first engine torque Cl is greater than or equal to the first limit value VL1.

[0008] In other words, the measurement of the first torque information makes it possible to directly determine the value of the first engine torque Cl or to calculate this value of the first engine torque Cl. The first engine torque Cl is therefore a current value which can vary according to the torque requirements during a maneuver performed by the rotorcraft, the load on board the rotorcraft and external conditions such as atmospheric pressure and wind force. In addition, the onboard load can be entered by a pilot or possibly be measured and include the mass of the onboard fuel and the mass of the crew present in the rotorcraft.

[0009] The first limit value VL1 is predetermined and fixed. It can in particular be determined by tests, flight tests or simulations. In addition, this first limit value VL1 can be specific to the rotorcraft or even to the hybrid power plant.

[0010] The controller then monitors the variations of the first engine torque Cl and when this first engine torque Cl becomes equal to or greater than the first limit value VL1, it generates a control command which is transmitted to the first reversible transmission device. This control command then aims to prevent, at least temporarily, the first engine shaft from rotating the first input shaft and therefore prevents the first engine torque Cl from being transmitted to the first input shaft.

[0011] The total engine torque transmitted to the output shaft is then a function solely of that supplied by the heat engine via the second mechanical connection and the second input shaft.

[0012] This control order can also be maintained until the end of the flight or for a predetermined duration allowing the rotorcraft pilot to act on the rotorcraft pilot controls.

[0013] Advantageously, a display of information representative of the first engine torque C1 and of the first limit value VL1 can then allow the pilot of the rotorcraft to act on flight controls to reduce the value of the first engine torque C1 before reaching the first limit value VL1.

[0014] Furthermore, several embodiments of the first reversible transmission device can be envisaged.

[0015] Thus, according to a first embodiment, the first reversible transmission device may comprise a first clutch positioned in the first mechanical connection, the first clutch being arranged in an engaged state when the first torque Cl is less than the first limit value VL1 and the first clutch being arranged in a disengaged state when the first torque Cl is greater than or equal to the first limit value VL1.

[0016] Such a first clutch can thus be controlled mechanically, hydraulically or electrically by the controller. When the first clutch is arranged in the disengaged state, the first engine torque C1 is then immediately cancelled by a reversible break or a disengagement of the mechanical transmission in the first mechanical connection.

[0017] According to a second embodiment, the first reversible transmission device may comprise an electrical switch positioned in the electrical connection, the electrical switch being arranged in a closed state when the first torque C1 is less than the first limit value VL1 and the electrical switch being arranged in an open state when the first torque is greater than or equal to the first limit value VL1.

[0018] Such a switch may for example be a relay or a switch electrically controlled by the controller. In this case, when the switch is arranged in the open state, the first couple C1 is then immediately cancelled by a reversible cutoff of the electrical power supply in the electrical connection.

[0019] Advantageously, the electrical connection may comprise an inverter transforming a direct electric current from the electricity stored in said at least one source of electrical energy into an alternating electric current supplying electricity to the electric motor, the electrical switch being positioned in a direction of circulation of the electric current between the at least one source of electrical energy and the inverter.

[0020] Thus, the electrical switch can cut off the power supply to the electric motor by opening its power supply circuit between the electrical energy source(s) and the inverter.

[0021] Alternatively, the electrical switch may be positioned in a direction of circulation of electric current between the inverter and at least one electricity supply terminal of the electric motor.

[0022] In this case, the electrical switch can cut off the power supply to the electric motor by opening its power supply circuit between the inverter and a power supply terminal of the electric motor.

[0023] In practice, said at least one first sensor may comprise a voltage sensor measuring an electrical supply voltage between two electricity supply terminals of the electric motor, said at least one first sensor comprising an intensity sensor measuring an electrical supply intensity of the electric current flowing in the electrical connection.

[0024] As a result, the monitoring system may include voltage and current sensors capable of measuring the electrical power consumed by the electric motor.

[0025] Alternatively or additionally, said at least one first sensor may comprise a rotation speed sensor measuring a rotation speed of the first motor shaft relative to a casing of the electric motor.

[0026] Thus, knowing the electrical power consumed by the electric motor, the efficiency of the electric motor and the rotation speed of the first motor shaft, the controller can calculate the first motor torque transmitted by the first motor shaft to the first input shaft according to the formula:

[0027] ri _

[0028] where U is the electrical supply voltage between two electrical supply terminals of the electric motor,

[0029] I is the electrical intensity of the supply of the electric current flowing in the electrical connection,

[0030] p is the efficiency of the electric motor, and

[0031] co is the rotational speed of the first motor shaft.

[0032] Advantageously and whatever the construction of the power plant, the monitoring system may comprise: - at least one second sensor measuring a second torque information representative of a second engine torque C2 transmitted by the second engine shaft to the second input shaft, - the memory storing a second limit value VL2 relating to the second engine torque C2, and - the controller comparing the second engine torque C2 with the second limit value VL2 and controlling a second reversible transmission device configured to transmit, and alternatively, prevent the transmission of the second engine torque C2, the second reversible transmission device being controlled to allow the second engine shaft to rotate the second input shaft when the second engine torque C2 is less than the second limit value VL2 and to prevent the second engine shaft from rotating the second input shaft when the second engine torque C2 is greater than or equal to the second limit value VL2.

[0033] In other words, the measurement of the second torque information makes it possible to directly determine the value of the second engine torque C2 or to calculate this value of the second engine torque C2. The second engine torque C2 is therefore also a current value which can vary according to the torque requirements during a maneuver performed by the rotorcraft, the load on board the rotorcraft and external conditions such as atmospheric pressure and wind force.

[0034] The second limit value VL2 is predetermined and fixed. It can in particular be determined by tests, flight tests or simulations and be specific to the rotorcraft or the power plant.

[0035] The controller then monitors the variations of the second engine torque C2 and when this second engine torque C2 is greater than or equal to the second limit value VL2, it generates a control command which is transmitted to the second reversible device for transmitting the second engine torque C2. This control command then aims to prevent, at least temporarily, the second engine shaft from rotating the second input shaft and therefore cancels the second engine torque C2.

[0036] The total engine torque transmitted to the output shaft is then zero or equal to the first engine torque CL

[0037] This control order can also be maintained until the end of the flight or for a predetermined duration allowing the rotorcraft pilot to act on the rotorcraft pilot controls.

[0038] Furthermore, a display of information representative of the second engine torque C2 and of the second limit value VL2 can then allow the pilot of the rotorcraft to act on flight controls to reduce the value of the second engine torque C2 before reaching the second limit value VL2.

[0039] According to a first exemplary embodiment, the second reversible transmission device may comprise a second clutch positioned in the second mechanical connection, the second clutch being arranged in an engaged state when the second engine torque C2 is less than the second limit value VL2 and the clutch being arranged in a disengaged state when the second torque C2 is equal to or greater than the second limit value VL2.

[0040] Such a second clutch can thus be controlled mechanically, hydraulically or electrically by the controller. When the second clutch is arranged in the disengaged state, the second engine torque C2 is then immediately canceled or prevented from being transmitted by a reversible break or disengagement of the mechanical transmission in the second mechanical link.

[0041] According to a second exemplary embodiment, the second reversible transmission device may comprise a fuel metering device supplying fuel to the heat engine, the fuel metering device being arranged in a passing state with a non-zero fuel flow rate when the second engine torque C2 is less than the second limit value VL2 and the fuel metering device being arranged in a blocked state without fuel flow rate when the second engine torque C2 is equal to or greater than the second limit value VL2.

[0042] Thus, the fuel metering device can cut off the fuel supply to the heat engine by stopping a flow of fuel circulating in a fuel supply circuit between the tank and a combustion chamber of the heat engine.

[0043] According to a third exemplary embodiment, the second reversible transmission device may comprise a cut-off valve supplying fuel to a fuel meter, the fuel cut-off valve being arranged in the open position with a non-zero fuel flow rate when the second engine torque C2 is less than the second limit value VL2 and the cut-off valve being arranged in a closed position to cut off the fuel flow rate when the second engine torque C2 is equal to or greater than the second limit value VL2.

[0044] Consequently, such a cut-off valve is independent of the fuel metering device in order to prevent a failure of the fuel metering device, for example blocked in a passing state with a non-zero fuel flow rate, from preventing the second reversible transmission device from cutting the thermal engine and therefore canceling the transmission of the second engine torque C2.

[0045] In practice, in the second exemplary embodiment and the third exemplary embodiment, the second reversible transmission device also comprises a freewheel arranged between the second drive shaft and the second input shaft in order to automatically uncouple the heat engine when the latter is no longer supplied with fuel.

[0046] In practice, said at least one second sensor may comprise a torque meter directly measuring the second engine torque C2.

[0047] Such a torque meter can then be arranged in the second mechanical connection between the second drive shaft and the second input shaft.

[0048] Advantageously and whatever the preceding embodiments, the monitoring system can comprise: - at least a third sensor measuring a third torque information representative of a third engine torque C3 transmitted by the output shaft to said at least one rotor, - the memory storing a third limit value VL3 relating to the third engine torque C3, and - the controller comparing the third engine torque C3 with the third limit value VL3 and controlling at least one reversible transmission device among the first and second reversible transmission devices, said at least one reversible transmission device being controlled to allow the first and second engine shafts to rotate the first and second input shafts when the third engine torque C3 is less than the third limit value VL3 and to prevent at least one of the first and second engine shafts from rotating the first or second input shaft respectively when the third engine torque C3 is greater than or equal to the third limit value VL3.

[0049] In other words, the measurement of the third torque information makes it possible to directly determine the value of the third engine torque C3 or to calculate this value of the third engine torque C3. The third engine torque C3 is therefore also a current value which can vary according to the torque requirements during a particular maneuver performed by the rotorcraft, the load on board the rotorcraft and external conditions such as atmospheric pressure and wind force.

[0050] Alternatively, the monitoring system may be devoid of a sensor measuring a third torque information representative of a third engine torque C3 transmitted by the output shaft. In this case, the value of the third engine torque C3 may be determined directly by the controller by calculating the sum of the first engine torque C1 and the second engine torque C2.

[0051] Regardless of whether the third engine torque C3 is measured or calculated, the third limit value VL3 is predetermined and fixed. It can be determined in particular by tests, flight tests or simulations.

[0052] The controller then monitors the variations of the third engine torque C3 and when this third engine torque C3 is greater than or equal to the third limit value VL3, it generates a control command which is transmitted to at least one of the first and second reversible devices for transmitting the first and second engine torque. This control command then aims to prevent, at least temporarily, the first and / or the second engine shaft from rotating the first and / or the second input shaft and therefore cancels the first engine torque C1 and / or the second engine torque C2.

[0053] The total engine torque transmitted to the output shaft can then be equal to the first engine torque C1, to the second engine torque C2 or be zero.

[0054] This control order can also be maintained until the end of the flight or still for a predetermined duration allowing the rotorcraft pilot to act on the rotorcraft pilot controls in order to decrease the third engine torque C3 below the third limit value VL3 when exceeding the third limit value VL3 is due to a pilot maneuver.

[0055] According to a first variant embodiment of the invention, when the third engine torque C3 is greater than or equal to the third limit value VL3, the controller can first control the first reversible transmission device to prevent the first engine shaft from rotating the first input shaft, then, if the third engine torque C3 remains greater than or equal to the third limit value VL3 after the control of the first reversible transmission device, the controller controls the second reversible transmission device to prevent the second engine shaft from rotating the second input shaft.

[0056] In this case, the controller therefore generates, in a first step, a first control order which is transmitted to the first reversible device for transmitting the first engine torque C1 and, in a second step, a second control order which is transmitted to the second reversible device for transmitting the second engine torque C2. The controller thus makes it possible to sequentially prevent the transmission of the first engine torque C1 to the first input shaft and then of the second engine torque C2 to the second input shaft.

[0057] According to a second variant embodiment of the invention, when the third engine torque C3 is greater than or equal to the third limit value VL3, the controller can simultaneously control the first reversible transmission device to prevent the first motor shaft from rotating the first input shaft and the second reversible transmission device to prevent the second motor shaft from rotating the second input shaft.

[0058] According to a third variant embodiment of the invention, when the third engine torque C3 is greater than or equal to the third limit value VL3, the controller can firstly identify a most powerful engine and a least powerful engine among the electric engine and the thermal engine and then firstly control a reversible transmission device corresponding to the least powerful engine, then, if the third engine torque C3 remains greater than or equal to the third limit value VL3, the other reversible transmission device corresponding to the most powerful engine.

[0059] Such a third variant embodiment of the invention thus makes it possible to maintain maximum availability of propulsion power for the rotorcraft.

[0060] According to a fourth variant embodiment of the invention, when the third motor torque C3 is greater than or equal to the third limit value VL3, the controller can firstly identify a motor with a maximum of available energy and a motor with a minimum of available energy among the electric motor and the motor thermal then first control a reversible transmission device corresponding to the motor with the minimum available energy then, if the third motor torque C3 remains greater than or equal to the third limit value VL3, the other reversible transmission device corresponding to the motor with the maximum available energy.

[0061] Such a fourth variant embodiment of the invention thus makes it possible to favor a maximum flight duration for the rotorcraft.

[0062] Furthermore, the choice between the different variant embodiments of the invention may depend, for example, on a type of mission carried out or may even be arbitrary depending on the piloting preferences of a pilot.

[0063] In this case, the controller therefore generates at the same time a first control order which is transmitted to the first reversible device for transmitting the first motor torque C1 and a second control order which is transmitted to the second reversible device for transmitting the second motor torque C2. The controller then makes it possible to simultaneously cancel the first motor torque C1 and the second motor torque C2.

[0064] The invention also relates to a rotorcraft comprising a aforementioned hybrid power plant and at least one rotor.

[0065] Such a rotorcraft is remarkable in that it includes a aforementioned monitoring system for the hybrid power plant.

[0066] The present invention also relates to a monitoring method for monitoring a hybrid rotorcraft power plant comprising at least one rotor, the hybrid power plant comprising: - an electric motor electrically connected by an electrical connection to at least one source of electrical energy, the electric motor comprising a first drive shaft, - a heat engine comprising a second drive shaft, and - a power transmission box comprising: • a first input shaft connected by a first mechanical connection to the first drive shaft, • a second input shaft connected by a second mechanical link to the second drive shaft, and • an output shaft connected by a third mechanical connection to said at least one rotor,

[0067] According to the invention, such a method is remarkable in that it comprises at least the following steps: - measurement with at least one sensor of a first torque information representative of a first motor torque Cl transmitted by the first motor shaft at the first input tree, - comparison with a controller between the first motor torque Cl and a first limit value VL1, and - control with the controller of a first reversible transmission device configured to transmit, and alternatively, prevent the transmission of the first engine torque Cl, the first reversible transmission device being controlled to allow the first motor shaft to rotate the first input shaft when the first engine torque Cl is less than the first limit value VL1 and to prevent the first motor shaft from rotating the first input shaft when the first engine torque Cl is greater than or equal to the first limit value VL1.

[0068] Such a monitoring method is thus implemented in a rotorcraft and during a flight phase of the rotorcraft during which the engine torque transmitted to the rotor varies by increasing, for example during a regulation failure of the hybrid power plant or even a piloting maneuver requiring significant torque for the rotor or the power transmission box.

[0069] The invention and its advantages will appear in more detail in the context of the description which follows with examples given for illustrative purposes with reference to the appended figures which represent:

[0070] [Fig.l], a diagram of a rotorcraft equipped with a surveillance system according to the invention,

[0071] [Fig.2], a block diagram illustrating a first variant of the control of a first reversible transmission device, in accordance with the invention,

[0072] [Fig.3], a block diagram illustrating a first example of a second variant of the control of a first reversible transmission device, in accordance with the invention,

[0073] [Fig.4], a block diagram illustrating a second example of the second variant of the control of a first reversible transmission device, in accordance with the invention,

[0074] [Fig.5], a block diagram illustrating a first variant of the control of a second reversible transmission device, in accordance with the invention,

[0075] [Fig.6], a block diagram illustrating a second variant of the control of a second reversible transmission device, in accordance with the invention, and

[0076] [Fig.7], a block diagram illustrating a third variant of the control of a second reversible transmission device, in accordance with the invention, and

[0077] [Fig.8], a logic diagram representative of a monitoring method in accordance with the invention.

[0078] Elements present in several distinct figures are assigned a single reference.

[0079] As already mentioned, the invention relates to a monitoring system for monitoring a hybrid rotorcraft power plant.

[0080] As shown in [Fig. 1], such a rotorcraft comprises at least one rotor 4 which may be, for example, a lift rotor, an anti-torque rotor for controlling the yaw movements of the rotorcraft or a propulsive or tractive propeller.

[0081] Furthermore, such a hybrid power plant 2 comprises an electric motor 5 electrically connected by an electrical connection 6 to at least one electrical energy source 7. The electric motor 5 thus comprises a first drive shaft 15.

[0082] The hybrid power plant 2 also comprises a heat engine 8 comprising a second drive shaft 18.

[0083] Furthermore, this hybrid power plant 2 also comprises a power transmission box 9 comprising a first input shaft 10, a second input shaft 12 and an output shaft 20.

[0084] The first input shaft 10 is mechanically connected by a first mechanical connection 11 to the first drive shaft 15 and the second input shaft 12 is mechanically connected by a second mechanical connection 13 to the second drive shaft 18.

[0085] Furthermore, the output shaft 20 is mechanically connected by a third mechanical connection 21 to said at least one rotor 4.

[0086] Furthermore, each mechanical connection 11, 13 and 21 may comprise at least one shaft, at least one mechanical connector such as a freewheel, a clutch and a rotation speed reduction stage comprising gears, a pinion or a toothed wheel.

[0087] Such a monitoring system 1 comprises at least one first sensor 16, 17, 19 measuring a first torque information representative of a first engine torque C1 transmitted by the first engine shaft 15 to the first input shaft 10.

[0088] Such a first sensor 16, 17, 19 can thus comprise a voltage sensor 16 and a current sensor 17 arranged in the electrical connection 6.

[0089] As shown in more detail in [Fig.2], the voltage sensor 16 can measure an electrical supply voltage between two terminals 54, 55 supplying electricity to the electric motor 5 and the intensity sensor 17 can measure an electrical supply intensity of the electric current flowing in the electrical connection 6.

[0090] Furthermore, said first sensor 16, 17, 19 may also comprise a rotation speed sensor 19 measuring a rotation speed of the first motor shaft 15 relative to a casing 25 of the electric motor 5.

[0091] By sensor, we mean here a physical sensor capable of directly measuring the parameter in question but also a system which may comprise one or more physical sensor(s) as well as signal processing means making it possible to provide an estimate of the parameter from the measurements provided by these physical sensors. Similarly, the term measurement of this parameter will refer to both a raw measurement from a physical sensor and a measurement obtained by more or less complex signal processing from raw measurements.

[0092] The monitoring system 1 can then calculate the first engine torque Cl supplied by the first engine shaft 15 to the first input shaft 10 according to the formula:

[0093] C1 =

[0094] where U is the electrical supply voltage between the two electrical supply terminals 54, 55 of the electric motor 5,

[0095] I is the electrical intensity of the supply of the electric current flowing in the electrical connection 6,

[0096] p is the efficiency of the electric motor 5, and

[0097] co is the rotational speed of the first motor shaft 15 relative to the casing 25.

[0098] The monitoring system 1 comprises a memory 30 storing a first limit value VL1 relating to the first engine torque CL

[0099] The monitoring system 1 also comprises a controller 31 which receives or calculates the first engine torque Cl according to, for example, the formula previously illustrated. The controller 31 compares the first engine torque Cl with the first limit value VL1 and controls a first reversible transmission device 41, 51 configured to transmit, and alternatively, prevent the transmission of the first engine torque CL

[0100] This first reversible transmission device 41, 51 thus receives a control order from the controller 31 to allow the first motor shaft 15 to drive the first input shaft 10 in rotation when the first motor torque Cl is less than the first limit value VL1 and another control order to prevent the first motor shaft 15 from driving the first input shaft 10 in rotation when the first motor torque Cl is greater than or equal to the first limit value VL1.

[0101] The controller 31 may comprise, for example, at least one processor and at least one memory, at least one integrated circuit, at least one programmable system, at least one logic circuit, these examples not limiting the scope given to the expression “controller”. The term processor may also designate a central processing unit known by the acronym CPU, a graphics processing unit GPU, a digital unit known by the acronym DSP, a microcontroller, etc.

[0102] Different variants of the first reversible transmission device 41, 51 are thus represented in Figures 2 to 4.

[0103] As shown in [Fig.2], and according to a first variant of the first device reversible transmission 41,51, such a first reversible transmission device 41 may comprise a first clutch 42 positioned in the first mechanical connection 11.

[0104] Such a first clutch 42 is thus connected by wire or wireless means to the controller 31 and then receives a control order from the controller 31 to be in an engaged state when the first torque Cl is less than the first limit value VL1. Alternatively, when the first torque Cl is equal to or greater than the first limit value VL1, the first clutch 42 then receives another control order from the controller 31 to be in a disengaged state preventing the transmission of the first torque Cl to the first input shaft 10.

[0105] According to a second variant of the first reversible transmission device 41, 51, the first reversible transmission device 51 may comprise an electrical switch 52 positioned in the electrical connection 6.

[0106] Such an electrical switch 52 is further connected by wire or wireless means to the controller 31 and then receives a control order from the controller 31 to be in a closed state when the first torque Cl is less than the first limit value VL1. Alternatively, when the first torque Cl is greater than or equal to the first limit value VL1, the electrical switch 52 receives another control order from the controller 31 to be arranged in an open state, thus canceling the first torque Cl.

[0107] As shown in [Fig.3], this electrical connection 6 may comprise an inverter 53 transforming a direct electric current from the electricity stored in the electrical energy source 7 into an alternating electric current supplying electricity to the electric motor 5. The electrical switch 52 may then, according to a first example of the second variant, be positioned in a direction of circulation of the electric current between the electrical energy source 7 and the inverter 53.

[0108] According to a second example of the second variant as shown in [Fig.4], the electrical switch 52 can alternatively be positioned according to a direction of circulation of the electricity between the inverter 53 and at least one terminal 54, 55 supplying electricity to the electric motor 5.

[0109] Furthermore, the monitoring system 1 may comprise at least one second sensor 26 measuring a second torque information representative of a second engine torque C2 transmitted by the second engine shaft 18 to the second input shaft 12.

[0110] Advantageously, a second sensor 26 can comprise a torque meter 27 directly measuring the second engine torque C2.

[0111] The memory 30 can thus also make it possible to store a second limit value VL2 relating to the second engine torque C2.

[0112] Similarly, the controller 31 can receive or calculate the second motor torque C2 to then compare the second engine torque C2 with the second limit value VL2.

[0113] The controller 31 can then generate a control order to control a second reversible transmission device 61, 71 configured to transmit, and alternatively, prevent the transmission of the second engine torque C2.

[0114] Such a second reversible transmission device 61, 71 is thus controlled by the controller 31 to allow the second motor shaft 18 to drive the second input shaft 12 in rotation when the second motor torque C2 is less than the second limit value VL2.

[0115] Alternatively, the second reversible transmission device 61,71 can be controlled by the controller 31 to prevent the second motor shaft 18 from rotating the second input shaft 12 when the second motor torque C2 is greater than or equal to the second limit value VL2.

[0116] As shown in [Fig.5], a first variant of this second reversible transmission device 61 may comprise a second clutch 62 positioned in the second mechanical connection 13.

[0117] This second clutch 62 thus receives a control order from the controller 31 to be in an engaged state when the second engine torque C2 is less than the second limit value VL2.

[0118] Alternatively, the clutch 62 receives another control order from the controller 31 to be in a disengaged state when the second engine torque C2 is equal to or greater than the second limit value VL2. Therefore, the clutch 62 makes it possible, in its disengaged state, to prevent the transmission of the second engine torque C2 to the second input shaft 12.

[0119] As shown in [Fig.6], a second variant of this second reversible transmission device 71 may comprise a fuel metering device 72 supplying fuel to the heat engine 8. The fuel metering device 72 receives a control order from the controller 31 to be in a passing state with a non-zero fuel flow rate when the second engine torque C2 is less than the second limit value VL2.

[0120] Alternatively, when said second engine torque C2 is greater than or equal to said second limit value VL2, the fuel metering device 72 receives another control order from the controller 31 to be in a blocked state without fuel flow preventing the supply of fuel to the heat engine 8 and then preventing the second engine torque C2 from being transmitted to the second input shaft 12.

[0121] As shown in [Fig.7], a third variant of this second reversible transmission device 81 may comprise a closing valve 83 arranged upstream of the fuel metering device 72 supplying fuel to the heat engine 8. closing valve 83 receives a control order from the controller 31 to be in an open position with a non-zero fuel flow rate when the second engine torque C2 is less than the second limit value VL2.

[0122] Alternatively, when said second engine torque C2 is greater than or equal to the second limit value VL2, the closing valve 83 receives another control order from the controller 31 to be in a closed position to cut off the fuel flow and prevent the fuel supply to the heat engine 8. The second engine torque C2 can, in this case, no longer be transmitted to the second input shaft 12.

[0123] Furthermore, according to [Fig.l], the monitoring system 1 may also comprise at least one third sensor 28 measuring a third torque information representative of a third engine torque C3 transmitted by the output shaft 20 to said at least one rotor 4.

[0124] The memory 30 can thus make it possible to store a third limit value VL3 relating to the third engine torque C3.

[0125] As a result, the controller 31 can then compare the third engine torque C3 with the third limit value VL3 and generate at least one control order transmitted to at least one of the reversible transmission devices 41, 51, 61, 71 among the first and second reversible transmission devices.

[0126] Furthermore, the reversible transmission device(s) 41, 51, 61, 71 are then controlled to allow the first and second drive shafts 15, 18 to drive the first and second input shafts 10, 12 in rotation when the third drive torque C3 is less than the third limit value VL3 and to prevent at least one of the first and second drive shafts 15, 18 from driving the first or second input shaft 10, 12 in rotation respectively when the third drive torque C3 is greater than or equal to the third limit value VL3.

[0127] The monitoring system 1 may also comprise an alerter capable of generating a first alert and a second alert that are different from each other. Each alert may take the form of a visual alarm, for example by means of the emission of a light with a light-emitting diode or an equivalent or the display on a screen of one or more characters, an audible alarm by means of a loudspeaker, and / or a haptic alarm, for example using a vibrating unit vibrating an organ held or worn by an individual.

[0128] For example, a first alert can be generated when the first motor torque Cl is greater than or equal to a first alert value VA1 and a second alert can be generated when the first motor torque Cl is greater than or equal to a second alert value VA2 greater than the first alert value VAL

[0129] The first alert value VA1 is thus chosen to be lower than the first value VL1 limit. The second alert value VA2 can be chosen to be less than or equal to the first VL1 limit value.

[0130] The first alert may be a message or notice displayed on a display for the rotorcraft pilot.

[0131] The second alert may be a light and / or sound signal to the rotorcraft pilot.

[0132] As shown in [Fig.8], the invention also relates to a monitoring method 100 for monitoring a aforementioned hybrid power plant 2 of a rotorcraft 3 comprising at least one rotor 4.

[0133] Such a monitoring method 100 then comprises a measurement 101 with said at least one first sensor 16, 17, 19 of the first torque information representative of the first engine torque Cl, then a comparison 102 with the controller 31 between the first engine torque Cl and the first limit value VL1.

[0134] The monitoring method 100 then comprises a command 103 with the controller 31 of a first reversible transmission device 41, 51 configured to transmit, and alternatively, prevent the transmission of the first engine torque CL

[0135] Advantageously, the monitoring method 100 may comprise a preliminary step 110 of storing the first limit value VL1 in the memory 30.

[0136] Naturally, the present invention is subject to numerous variations as to its implementation. Although several embodiments have been described, it is understood that it is not conceivable to exhaustively identify all possible modes. It is of course conceivable to replace a means described by an equivalent means without departing from the scope of the present invention.

Claims

Claims

1. Monitoring system (1) for monitoring a hybrid power plant (2) of a rotorcraft (3) comprising at least one rotor (4), said hybrid power plant (2) comprising: - an electric motor (5) electrically connected by an electrical connection (6) to at least one source of electrical energy (7), said electric motor (5) comprising a first drive shaft (15), - a heat engine (8) comprising a second drive shaft (18), and - a power transmission box (9) comprising: • a first input shaft (10) connected by a first mechanical connection (11) to the first drive shaft (15), • a second input shaft (12) connected by a second mechanical connection (13) to the second drive shaft (18), and • an output shaft (20) connected by a third mechanical connection (21) to said at least one rotor (4), characterized in that said monitoring system (1) comprises: - at least one first sensor (16, 17, 19) measuring first torque information representative of a first engine torque Cl transmitted by said first engine shaft (15) to said first input shaft (10), - a memory (30) storing a first limit value VL1 relating to said first engine torque Cl, and - a controller (31) comparing said first engine torque Cl with said first limit value VL1 and consequently controlling a first reversible transmission device (41, 51) configured to transmit, and alternatively prevent the transmission of said first engine torque Cl, said first reversible transmission device (41, 51) being controlled to allow said first engine shaft (15) to rotate said first input shaft (10) when said first engine torque Cl is less than said first limit value VL1 and to prevent said first motor shaft (15) from rotating said first input shaft (10) when said first motor torque Cl is greater than or equal to said first limit value VL1.

2. System according to claim 1, characterized in that said first reversible transmission device (41) comprises a first clutch (42) positioned in said first mechanical connection (11), said first clutch (42) being arranged in an engaged state when said first torque Cl is less than said first limit value VL1 and said first clutch (42) being arranged in a disengaged state when said first torque Cl is greater than or equal to said first limit value VL1.

3. System according to claim 1, characterized in that said first reversible transmission device (51) comprises an electrical switch (52) positioned in said electrical connection (6), said electrical switch (52) being arranged in a closed state when said first torque Cl is less than said first limit value VL1 and said electrical switch (52) being arranged in an open state when said first torque Cl is greater than or equal to said first limit value VL1.

4. System according to claim 3, characterized in that said electrical connection (6) comprises an inverter (53) transforming a direct electric current of the electricity stored in said at least one source of electrical energy (7) into an alternating electric current supplying electricity to said electric motor (5), said electrical switch (52) being positioned in a direction of circulation of said electric current between said at least one source of electrical energy (7) and said inverter (53).

5. System according to claim 3, characterized in that said electrical connection (6) comprises an inverter (53) transforming a direct electric current of the electricity stored in said at least one source of electrical energy (7) into an alternating electric current supplying electricity to said electric motor (5), said electrical switch (52) being positioned in a direction of circulation of the electric current between said inverter (53) and at least one terminal (54, 55) supplying electricity to said electric motor (5).

6. System according to any one of claims 1 to 5, characterized in that said at least one first sensor (16, 17, 19) comprises a voltage sensor (16) measuring an electrical supply voltage between two terminals (54, 55) supplying electricity to said electric motor (5), said at least one first sensor (16, 17, 19) comprising an intensity sensor (17) measuring an electrical intensity of an electrical supply current flowing in said electrical connection (6).

7. System according to any one of claims 1 to 6, characterized in that said at least one first sensor (16, 17, 19) comprises a rotation speed sensor (19) measuring a rotation speed of said first motor shaft (15) relative to a casing (25) of said electric motor (5).

8. System according to any one of claims 1 to 7, characterized in that said monitoring system (1) comprises: - at least one second sensor (26) measuring a second torque information representative of a second engine torque C2 transmitted by said second engine shaft (18) to said second input shaft (12), - said memory (30) storing a second limit value VL2 relating to said second engine torque C2, and - said controller (31) comparing said second engine torque C2 with said second limit value VL2 and controlling a second reversible transmission device (61, 71, 81) configured to transmit, and alternatively prevent the transmission of said second engine torque C2, said second reversible transmission device (61, 71,81) being controlled to allow said second motor shaft (18) to rotate said second input shaft (12) when said second motor torque C2 is less than said second limit value VL2 and to prevent said second motor shaft (18) from rotating said second input shaft (12) when said second motor torque C2 is greater than or equal to said second limit value VL2.,

9. System according to claim 8, characterized in that said second reversible transmission device (61) comprises a second clutch (62) positioned in said second mechanical connection (13), said second clutch (62) being arranged in an engaged state when said second engine torque C2 is less than said second limit value VL2 and said clutch (62) being arranged in a disengaged state when said second torque C2 is greater than or equal to said second limit value VL2.

10. System according to claim 8, characterized in that said second reversible transmission device (71) comprises a fuel metering device (72) supplying fuel to said heat engine (8), said fuel metering device (72) being arranged in a passing state with a non-zero fuel flow rate when said second engine torque C2 is less than said second limit value VL2 and said fuel metering device (72) being arranged in a blocked state without fuel flow rate when said second engine torque C2 is equal to or greater than said second limit value VL2.

11. System according to claim 8, characterized in that said second reversible transmission device (81) comprises a cut-off valve (83) supplying fuel to a fuel meter (82), said cut-off valve (83) being arranged in the open position with a non-zero fuel flow rate when said second engine torque C2 is less than said second limit value VL2 and said cut-off valve (83) being arranged in a closed position to cut off the fuel flow rate when said second engine torque C2 is equal to or greater than said second limit value VL2.

12. System according to any one of claims 8 to 11, characterized in that said at least one second sensor (26) comprises a torque meter (27) directly measuring said second engine torque C2.

13. System according to any one of claims 8 to 12, characterized in that said monitoring system (1) comprises: - at least one third sensor (28) measuring a third torque information representative of a third engine torque C3 transmitted by said output shaft (20) to said at least one rotor (4), - said memory (30) storing a third limit value VL3 relating to said third engine torque C3, and - said controller (31) comparing said third engine torque C3 with said third limit value VL3 and controlling at least one reversible transmission device (41, 51, 61, 71) among said first and second reversible transmission devices, said at least one reversible transmission device (41, 51, 61, 71) being controlled to allow said first and second drive shafts (15, 18) to rotate said first and second input shafts (10, 12) when said third drive torque C3 is less than said third limit value VL3 and to prevent at least one of said first and second drive shafts (15, 18) from rotating respectively said first or said second input shaft (10, 12) when said third drive torque C3 is greater than or equal to said third limit value VL3.

14. System according to claim 13, characterized in that, when said third engine torque C3 is greater than or equal to said third limit value VL3, said controller (31) first controls said first reversible transmission device (41, 51) to prevent said first drive shaft (15) from rotating said first input shaft (10) then said controller (31) controls said second reversible transmission device (61, 71) to prevent said second drive shaft (18) from rotating said second input shaft (12).

15. System according to claim 13, characterized in that, when said third engine torque C3 is greater than or equal to said third limit value VL3, said controller (31) simultaneously controls said first reversible transmission device (41, 51) to prevent said first drive shaft (15) from rotating said first input shaft (10) and said second reversible transmission device (61, 71) to prevent said second drive shaft (18) from rotating said second input shaft (12).

16. Rotorcraft (3) comprising a hybrid power plant (2) and at least one rotor (4), said hybrid power plant (2) comprising: - an electric motor (5) electrically connected by an electrical connection (6) to at least one source of electrical energy (7), said electric motor (5) comprising a first drive shaft (15), a heat engine (8) comprising a second drive shaft (18), and a power transmission box (9) comprising: • a first input shaft (10) connected by a first mechanical connection (11) to the first drive shaft (15), • a second input shaft (12) connected by a second mechanical connection (13) to the second drive shaft (18), and • an output shaft (20) connected by a third mechanical connection (21) to said at least one rotor (4), characterized in that said rotorcraft (3) comprises a monitoring system (1) of said hybrid power plant (2) according to any one of claims 1 to 15.

17. Monitoring method (100) for monitoring a hybrid power plant (2) of a rotorcraft (3) comprising at least one rotor (4), said hybrid power plant (2) comprising: an electric motor (5) electrically connected by an electrical connection (6) to at least one source of electrical energy (7), said electric motor (5) comprising a first drive shaft (15), a heat engine (8) comprising a second drive shaft (18), and a power transmission box (9) comprising: • a first input shaft (10) connected by a first mechanical connection (11) to said first drive shaft (15), • a second input shaft (12) connected by a second mechanical connection (13) to said second drive shaft (18), and • an output shaft (20) connected by a third mechanical connection (21) to said at least one rotor (4), characterized in that said monitoring method (100) comprises at least minus the following steps: - measurement (101) with at least one first sensor (16, 17, 19) of first torque information representative of a first engine torque Cl transmitted by said first engine shaft (15) to said first input shaft (10), - comparison (102) with a controller (31) between said first motor torque Cl and a first limit value VL1, and - control (103) with said controller (31) of a first reversible transmission device (41, 51) configured to transmit, and alternatively, prevent the transmission of said first engine torque Cl, said first reversible transmission device (41, 51) being controlled to allow said first motor shaft (15) to rotate said first input shaft (10) when said first engine torque Cl is less than said first limit value VL1 and to prevent said first motor shaft (15) from rotating said first input shaft (10) when said first engine torque Cl is greater than or equal to said first limit value VL1.

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