Turbomachine with parallel electrical hybridization

Abstract

Disclosed is a hybrid turbomachine (10), in particular for a rotary-wing aircraft, comprising a gas generator (13) having a first shaft (16), at least one electric machine (11) having a second shaft (17), and a rotating equipment (15) coupled to a third mechanical shaft (18). The hybrid turbomachine (10) further comprises a switching coupling means (20) configured to couple the third mechanical shaft (18) to the first mechanical shaft (16) or the second mechanical shaft (17), depending on the operating phases of the gas generator (13) and the electric machine (11).

Description

[0001] Description

[0002] Title of the invention: Parallel electric hybrid turbomachine

[0003] Technical Field

[0004] The present invention relates to the general field of aeronautical turbomachines and more particularly to aeronautical turbomachines with free turbines having a certain level of parallel electric hybridization.

[0005] The invention relates more particularly to the lubrication and cooling assembly of propulsion systems such as the gas turbine, the electric machine and the propeller pitch control.

[0006] Prior art

[0007] A free turbine helicopter engine generally comprises a gas generator and a free turbine driven in rotation by the gas flow generated by the gas generator, as well as a reversible electrical machine which can be coupled to the gas generator in particular to set the gas generator in rotation during a start-up phase of the engine.

[0008] Traditionally, a gas generator consists of at least one compressor and one turbine coupled in rotation. The operating principle is as follows: fresh air entering the turbine engine is compressed by the rotation of the compressor before being sent to a combustion chamber where it is mixed with fuel. The gases burned during combustion are then evacuated at high speed.

[0009] A first expansion then occurs in the gas generator turbine, during which the latter extracts the energy necessary to drive the compressor. The gas generator turbine does not absorb all the kinetic energy of the burnt gases and the excess kinetic energy corresponds to the gas flow generated by the gas generator. The latter therefore provides kinetic energy to the free turbine so that a second expansion occurs in the free turbine which transforms this kinetic energy into mechanical energy in order to drive a receiving organ, such as the rotor of the helicopter.

[0010] On conventional turbomachine architectures comprising a gas generator and a free turbine (Low Pressure or LP) driving the propulsion element, the oil pump for lubricating and cooling the rotating elements is connected to the gas generator (typically being driven by a high pressure shaft via an accessory box), in order to be able to operate from its start. On certain applications, there is also an oil pump on the low pressure drive line to lubricate certain elements of this low pressure line, such as pinions or bearings for example, when it is rotating.

[0011] On a free turbine engine, the low-pressure drive line is connected to the free turbine and the main rotor. In certain phases, for example when the gas generator is switched off, the low-pressure drive line can continue to rotate due to the inertia of the main rotor. This is even though the main oil pump for the high-pressure circuit stops when the gas generator stops. There is therefore a potential need to lubricate the low-pressure line, which the main oil pump can no longer provide during this short phase since it is no longer supplied with mechanical power.

[0012] Document FR 2929324 A1 discloses a free turbine turbomachine equipped with a device for performing coupling switching between the gas generator and the free turbine. The switching device described in this document uses two freewheels, making it possible to start the gas generator of a free turbine turboshaft engine, then to generate non-propulsive electrical energy by taking mechanical energy from the free turbine shaft.

[0013] Also known from document FR 3115812 A1 is a free turbine turbomachine comprising another coupling switching device between the gas generator and the free turbine with a single freewheel.

[0014] Furthermore, in the context of a parallel hybrid turbomachine, certain operating phases (such as a takeoff or cruise phase) are carried out in purely electric propulsion (100% electric) with the gas generator off or at idle. It is also possible to have purely electric operations in the event of a gas generator failure or in electric taxi mode. In these cases of 100% electric propulsion, the oil pump connected to the gas generator is inactive. It is therefore usually necessary to have another source of oil supply, such as a low-pressure pump, to cool the electric machine and the rotating elements of the rotating shaft lines and possibly to control the pitch of a propeller in the case of a turboprop.

[0015] Statement of the invention

[0016] To this end, the present invention proposes a hybrid turbomachine comprising a mechanical drive switch for rotating equipment making it possible to switch the source of power for driving the rotating equipment between the gas turbine and the electric machine depending on the operating phases of the turbomachine, to do without any auxiliary source, and therefore achieve a saving in financial cost, mass, and size.

[0017] In one subject of the invention, an electrically hybridized turbomachine is proposed, in particular for a rotary wing aircraft, comprising a gas generator provided with a first mechanical shaft, at least one electrical machine, preferably reversible, provided with a second mechanical shaft, and rotating equipment coupled to a third mechanical shaft.

[0018] According to a technical characteristic of the invention, the turbomachine comprises a commutative coupling means configured to couple the third mechanical shaft with the first mechanical shaft or the second mechanical shaft depending on the operating phases of the gas generator and the electrical machine.

[0019] The commutative coupling means thus makes it possible to switch the drive of the rotating equipment from the gas generator to the electric machine and vice versa depending on the operating phases of the turbomachine.

[0020] The invention thus makes it possible to avoid duplicating rotating equipment requiring a source of mechanical power, and thus to avoid additional costs, and greater bulk and mass.

[0021] Indeed, the invention thus makes it possible to avoid having a first rotating equipment coupled to the gas turbine and a second rotating equipment identical to the first rotating equipment coupled to the electric machine to ensure that the first or second rotating equipment is always in operation regardless of the operating phase of the hybrid turbomachine, and more particularly regardless of the source of mechanical power in operation. In the case of purely electric propulsion, the gas turbine being switched off or idling, the third mechanical shaft connected to the rotating equipment is driven by the electric machine via the commutative coupling means and the second mechanical shaft. In the case of purely thermal propulsion, the electric machine being stopped, the third mechanical shaft connected to the rotating equipment is driven by the gas turbine via the commutative coupling means and the first mechanical shaft.

[0022] In the case of hybrid propulsion, i.e. in a case where the gas turbine and the electric machine are in operation, the third mechanical shaft connected to the rotating equipment is driven by the mechanical power source transmitting the high speed between the electric machine and the gas turbine, modulo any speed reducers included in the commutative coupling means and which can be coupled to the first mechanical shaft and to the second mechanical shaft.

[0023] When the hybrid turbomachine is for a rotary wing aircraft, the rotary wing is driven either by the gas turbine or by the electric machine.

[0024] According to a first aspect of the turbomachine, the commutative coupling means comprises a first unidirectional coupling means connected between the first mechanical shaft and the third mechanical shaft and a second unidirectional coupling means connected between the second mechanical shaft and the third mechanical shaft, the first unidirectional coupling means and the second unidirectional coupling means being configured to transmit a mechanical torque only to the third mechanical shaft.

[0025] The unidirectional coupling means, such as a freewheel for example, allows the power to be transmitted in only one direction between the two shafts. The gas generator will not be able to drive the free turbine under any circumstances.

[0026] According to a second aspect of the turbomachine, the commutative coupling means further comprises a coupling wheel comprising a hub connected to the third mechanical shaft and teeth on its periphery coupled to the first unidirectional coupling means and to the second unidirectional coupling means.

[0027] According to a third aspect of the turbomachine, the first one-way coupling means comprises a first freewheel and a first speed reducer, and the second one-way coupling means comprises a second freewheel and a second speed reducer.

[0028] Using a speed reducer with each of the freewheels allows the rotation speed to be adapted to the terminals of each freewheel and allows two shafts to be connected which do not necessarily rotate at the same rotation speed.

[0029] The transmission ratio is determined by technological considerations or by power take-off needs to drive accessories for example.

[0030] In a fourth embodiment of the turbomachine according to the invention, the commutative coupling means may comprise a hydraulic coupler or a clutch, or piloted dogs.

[0031] Advantageously, the rotating equipment may be an oil pump. The invention thus makes it possible to communalize the oil pump to lubricate or cool the gas turbine and the electric machine during the different operating phases of a hybrid turbomachine with a single oil pump.

[0032] Rotating equipment can also be a cooling unit or an alternator.

[0033] In a fifth embodiment of the turbomachine according to the invention, the turbomachine may further comprise an accessory box mechanically coupled between the third mechanical shaft at the input and several rotating equipment at the output.

[0034] In one subject of the invention, there is provided a rotary wing aircraft comprising at least one turbomachine as defined above.

[0035] Brief description of the drawings

[0036] [Fig. 1] Figure 1, already described, is a simplified schematic view of a free turbine turbomachine according to the state of the art.

[0037] [Fig. 2] Figure 2 is a diagram of a free turbine turbomachine according to one embodiment of the invention.

[0038] Description of the embodiments In Figure 1 is shown schematically a free turbine turbomachine according to the state of the art, for starting, an electric machine 1 in a motor operation drives the mechanical shaft 2 of the gas generator 3, until the rotation of the latter is maintained by the combustion of fuel. The shaft 8 of the free turbine 9 being mechanically decoupled from the shaft 2 of the gas generator, the electric machine 1 does not drive the shaft 8. The free turbine 9 is then driven only by the gas flow leaving the gas generator. The rotational drive of the compressor by the electric machine 1 operating as a motor in fact makes it possible to circulate air in the compressor 4 and therefore to bring compressed air into the combustion chamber 5 in order to initiate combustion.This combustion then produces the gas flow enabling the turbine 6 of the gas turbine 3 to rotate, after which the compressor 4 is directly rotated by the turbine 6, which means that the gas generator 3 operates autonomously, indicating the end of the start-up phase of the turbine engine.

[0039] It is known that aircraft, in which such turboshaft engines are intended to be integrated, include numerous electrical components that need to be powered by electrical energy. For example, for a vertical take-off and landing aircraft with electric propulsion, it is necessary to power all the electric rotors that equip it with electrical energy.

[0040] On a turbomachine as illustrated in Figure 1, the equipment, or accessories, such as the fuel pump, and the oil pump are mechanically connected to the shaft 2 of the gas generator 3 via an accessory box.

[0041] Once the start-up phase is complete, it is known to use the electrical machine 1 if it is reversible in a generator operating mode to produce non-propulsive electrical energy (28V network for example) to supply electricity to the electrical equipment. The electrical machine 1 generates electrical energy by taking mechanical power from the shaft 2 of the gas generator 3, the rotational kinetic energy taken from the gas generator being transformed into electrical energy by said machine. This electrical machine 1 may be non-reversible and consist of a simple starter, such as a choke, if the need for electrical generation does not exist.

[0042] Figure 2 schematically shows a free turbine turbomachine 10 according to one embodiment of the invention.

[0043] The turbomachine 10 comprises a free turbine (not shown), a gas generator 11, an electric machine 12, an oil pump 15, a first coupling switch 13 and a second coupling switch 14.

[0044] The gas generator 11 comprises a first mechanical shaft 16 mechanically connected to the first coupling switch 13.

[0045] The electrical machine 12 comprises a second mechanical shaft 17 connected to the second coupling switch 14. This mechanical connection between the electrical machine 12 and the second mechanical shaft 17 can be made directly so that the second mechanical shaft 17 and the rotor of the electrical machine 12 rotate at the same speed. It can also be made indirectly via a reducer so as to obtain different rotation speeds between the two members, in particular in the case where the nominal rotation speeds of the two members are intended to be different.

[0046] The oil pump 15 comprises a third mechanical shaft 18 mechanically connected to a coupling wheel 19, the coupling wheel 19 comprising a hub coupled to the third mechanical shaft 18 and coupling teeth on the circular periphery, the teeth being coupled to the first coupling switch 13 on the one hand and to the second coupling switch 14 on the other hand.

[0047] The first coupling switch 13, the second coupling switch 14 and the coupling wheel 19 form a commutative coupling means 20.

[0048] The first coupling switch 13 comprises a first freewheel 21 and a first reducer 22. The first reducer 22 is mechanically connected between the first freewheel 21 and the first mechanical shaft 16. The first freewheel 21 is mechanically coupled between the first reducer 22 and the coupling wheel 19.

[0049] The second coupling switch 14 comprises a second freewheel 23 and a second reduction gear 24. The second reduction gear 24 is mechanically connected between the second freewheel 22 and the second mechanical shaft 17. The second freewheel 23 is mechanically coupled between the second reduction gear 24 and the coupling wheel 19.

[0050] In a variant, the oil pump could be replaced by an accessory box coupled at the input to the third mechanical shaft 18 and at the output to a plurality of mechanically driven accessories, including a fuel pump for example.

[0051] The turbomachine 10 thus configured makes it possible to easily switch from one power source to the other between the gas generator 11 and the electric machine 12 without the intervention of an electronic control unit. The free turbine turbomachine according to the present invention thus makes it possible to optimize the mass, cost and reliability of the switching system and therefore of the turbomachine.

Claims

Claims

1. Electrically hybridized turbomachine (10), in particular for a rotary wing aircraft capable of being driven, comprising a gas generator (11) provided with a first mechanical shaft (16), at least one electrical machine (12) provided with a second mechanical shaft (17), and rotating equipment (15) coupled to a third mechanical shaft (18), characterized in that it comprises a commutative coupling means (20) configured to couple the third mechanical shaft (18) with the first mechanical shaft (16) or with the second mechanical shaft (17) as a function of the operating phases of the gas generator (11) and the electrical machine (12) to thereby switch the drive of the rotating equipment (15) from the gas generator (11) to the electrical machine (12) and vice versa as a function of the operating phases of the turbomachine (10).

2. A turbomachine (10) according to claim 1, wherein the commutative coupling means (20) comprises a first unidirectional coupling means (13) connected between the first mechanical shaft (16) and the third mechanical shaft (18) and a second unidirectional coupling means (14) connected between the second mechanical shaft (17) and the third mechanical shaft (18), the first unidirectional coupling means (13) and the second unidirectional coupling means (14) being configured to transmit mechanical torque only to the third mechanical shaft (18).

3. A turbomachine (10) according to claim 2, wherein the commutative coupling means (20) further comprises a coupling wheel (19) having a hub connected to the third mechanical shaft (18) and teeth on its periphery coupled to the first unidirectional coupling means (13) and to the second unidirectional coupling means (14).

4. Turbomachine (10) according to one of claims 2 or 3, in which the first unidirectional coupling means (13) comprises a first freewheel (21) and a first speed reducer (22), and the second unidirectional coupling means (14) comprises a second freewheel (23) and a second speed reducer (24).

5. A turbomachine (10) according to claim 1, wherein the commutative coupling means comprises a hydraulic coupler or a clutch, or piloted dogs.

6. Turbomachine (10) according to one of claims 1 to 5, in which the rotating equipment is an oil pump (15).

7. Turbomachine (10) according to one of claims 1 to 5, in which the rotating equipment is a cooling unit or an alternator.

8. Turbomachine (10) according to one of claims 1 to 5, further comprising an accessory box mechanically coupled between the third mechanical shaft (18) at the input and several rotating equipment at the output.

9. Rotary wing aircraft comprising at least one turbomachine (10) according to one of claims 1 to 8.

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