Method and configuration for an auxiliary power engine to deliver propulsive and/or non-propulsive energy in a helicopter architecture

CA 02876952 2014-12-16 WO 2014/001683 1 PCT / FR2013 / 051379 METHOD AND CONFIGURATION OF PROPULSIVE AND / OR NON-PROPULSIVE ENERGY SUPPLY IN A HELICOPTER ARCHITECTURE BY AN AUXILIARY POWER MOTOR TECHNICAL FIELD [0001] L The invention relates to a method and an architecture configuration for providing propulsive and / or non-propulsive energy in a helicopter architecture by an auxiliary power engine, for example an auxiliary power unit known by the abbreviated name APU (initials of Auxiliary Power Unit in English terminology), as well as an architecture for implementing this method. The energy input is said to be direct insofar as it does not pass through the main engines of the helicopter.

By auxiliary engine is meant any thermal system which makes it possible to provide power, such as an APU unit, but also generally a gas turbine with a free or linked turbine, of the main engine type, or even a thermal engine, by example a diesel engine, or a fuel cell.

Current helicopters are systematically equipped with main engines used for propulsion, and sometimes with an APU group whose function is to provide non-propulsive energy to the ground (ignition of the engines, electrical and pneumatic transient) or in theft, when the main engines are unable to do so (for example in the event of an engine failure or failure).

Helicopters are equipped with main engines which are used for propulsion and sometimes with an auxiliary engine.

Currently, the auxiliary engines are APU groups: they are small gas turbines capable of providing non-propulsive power ¨ electrical, mechanical, hydraulic and / or pneumatic ¨ on the ground or in the various phases of flight where the main engines do not. are unable to do so: transition phase (takeoff, landing) or search, engine failure, electrical machine failure, etc.

For example, in an engine failure regime (abbreviated as OEI regime, initials of One Engine lnoperative in English terminology), the group CA 02876952 2014-12-16 WO 2014/001683 2 PCT / FR2013 / 051379 APU is on for that it provides non-propulsive energy in order to lighten or eliminate the electrical contribution of the remaining motor.

When the main engines are operational, the APU groups therefore remain off in flight, which represents an unnecessary load. The invention relates to optimizing the use of APU groups in order to make their presence profitable.

STATE OF THE ART [0005] A gas turbine conventionally comprises, as a base, a gas generator formed of a compressor - combustion chamber - turbine assembly, arranged between an air inlet and an exhaust nozzle.

In operation, fuel is injected into the chamber and the combustion of the fuel / air mixture provides energetic gases.

These hot gases are expanded in the turbine which mechanically drives the compressor via a high pressure shaft (HP for short).

This type of architecture and operation is equally valid for the main engines of helicopters and for the APU units.

For the main engines, the drive shaft also transmits the power available to provide propulsive energy to the helicopter's rotors ¨ main rotor and anti-torque rotor ¨ as well as non-propulsive energy ( electric, pneumatic, hydraulic).

The power is transmitted via a main transmission box called BTP.

In modern engines, the combustion gases undergo a second expansion in a free turbine before driving the BTP.

BTP transmits power to the rotors, to the electrical system that supplies the helicopter's on-board electrical network, as well as to other energy-consuming equipment (pump, charge compressor, etc.), in particular the control system. ECS air conditioning (initials for Environmental Conditioning System in English terminology).

[0007] For APU groups, their turbine only drives accessories that consume non-propulsive energy via a gearbox mounted on their shaft.

Current helicopter architectures comprising a group CA 02876952 2014-12-16 WO 2014/001683 3 PCT / FR2013 / 051379 APU therefore do not use all the power capacity available to provide non-propulsive and propulsive energy in flight .

In particular, when the main engines are operational, the APU group is switched off and therefore represents an unnecessary load.

DISCLOSURE OF THE INVENTION [0008] The invention aims to optimize all of the motorization available on a helicopter equipped with an auxiliary motor by allowing the latter to provide non-propulsive and / or propulsive energy in flight.

To do this, this auxiliary motor is coupled so as to be able to participate in the supply of propulsive energy, that is to say mechanical or electrical, and non-propulsive electrical energy of the aircraft, in the phases of flight where a contribution additional energy makes it possible to improve the performance of the helicopter and / or to satisfy an optimized distribution of the energy sources.

More specifically, the present invention relates to a method of supplying propulsive and / or non-propulsive energy in a helicopter architecture comprising an on-board electrical network, a main engine coupled to a mechanical transmission system which drives propulsion units in flight.

A mechanical / electrical energy conversion coupled to the mechanical transmission system and / or to the main engine provides non-propulsive energy to the on-board electrical network.

The method consists in coupling by energy conversion an additional auxiliary motor to the on-board network, in order to be able to supply it, on the ground, with non-propulsive energy as well as to the main engine for starting it, and to be able to supply it, in flight , non-propulsive energy to the on-board network, in addition to and until replacement of the sample taken from the mechanical transmission system and / or the main engine.

Advantageously, the auxiliary motor also supplies electrical energy to a dedicated motorization on the mechanical transmission system to increase or partially supply the propulsive power.

CA 02876952 2014-12-16 WO 2014/001683 4 PCT / FR2013 / 051379 [0011] Preferably, the mechanical transmission system comprising a speed reduction system, the auxiliary motor can also or alternatively be coupled directly to this transmission system. speed reduction to supply propulsive energy to at least one propulsion component of the helicopter, then coupled via a reversible energy conversion to the on-board network to provide non-propulsive energy as well as to the main engine for starting it.

The auxiliary motor can then supply propulsive energy to the anti-torque rotor called RAC and / or to the main rotor.

Under these conditions, the auxiliary engine is operational to provide propulsive and / or non-propulsive energy as a function of the needs in the various phases of flight, in normal or asymmetrical operation of the main engines.

Asymmetrical operation can be involuntary (case of failure or breakdown) or voluntary (transient phases, acceleration, etc.).

According to preferred embodiments:

- the electrical energy of the on-board network comes from a modulation between the energy taken from the mechanical transmission system and the main engine via energy conversion;

- the energy conversion is only connected to the reduction system so that the electrical energy from the on-board network only comes from the auxiliary engine via the reduction system when the main engine is switched off;

- the auxiliary engine is integrated into the MGB of the mechanical transmission system so that it supplies electrical energy to the on-board network by converting energy with generators on the MGB and propulsive energy to at least one propulsion unit via the construction industry.

The invention also relates to a configuration for supplying propulsive and / or non-propulsive energy in a helicopter.

This configuration comprises a basic on-board electrical network, two main motors and a system for converting mechanical / electrical energy between a MGB of a CA 02876952 2014-12-16 WO 2014/001683 5 PCT / FR2013 / 051379 mechanical transmission to the propulsion units and means for receiving electrical energy comprising the on-board network and power electronics in conjunction with starters of the main engines, the configuration being characterized in that it also comprises an auxiliary power motor for supplying electrical energy to the means for receiving electrical energy via the energy conversion system and mechanical coupling means between the auxiliary motor and the minus one propulsion unit.

The energy conversion system may include generators or reversible motor-generator sets in connection with the construction industry and / or the main motors and / or the auxiliary motor to supply electrical energy to the on-board network and to power electronics.

According to particular embodiments:

- the connection between the auxiliary engine and at least one of the propulsion components is made by a dedicated engine on this component and / or motor generators on the construction industry via the power electronics activated by the linked energy conversion system to the auxiliary engine;

- the auxiliary engine is integrated on the MGB in conjunction with generators to provide non-propulsive energy, the auxiliary engine being able to supply non-propulsive energy to the on-board network and to the power electronics via the generators on BTP and propulsive energy via BTP to at least one propulsion unit, namely to the main rotor and / or to the RAC;

- the connection between the auxiliary motor and the energy conversion system is made via a reduction unit belonging to the mechanical transmission system;

- the mechanical transmission system comprising a reduction unit, this reduction unit directly connects the auxiliary engine to the MGB and / or to the RAC drive shaft, and the auxiliary engine to a motor generator and / or to at least one generator partially or totally forming CA 02876952 2014-12-16 WO 2014/001683 6 PCT / FR2013 / 051379 energy conversion system for supplying electrical energy to the on-board network and to the power electronics;

- the reduction unit comprises at least two speed reduction gear lines coupled by at least one connecting shaft between the auxiliary motor mounted on the first line and a power take-off on the BTP or RAC mounted on the second line , and in which at least one connecting shaft is equipped with a reversible decoupling means and a freewheel so that, respectively, the auxiliary motor does not drive the main rotor on the ground and the main rotor does not drive the auxiliary motor on the ground or in flight;

- in the case where the generator (s) of the energy conversion system is (are) directly connected to the reduction unit, the connecting shaft equipped with the reversible decoupling means and the wheel freewheel drives the power take-off and the generator (s) mounted via another freewheel on the second gear line and / or on at least one second connecting shaft equipped with a freewheel between a generator and the auxiliary motor;

- in the case where the auxiliary motor has a free turbine, the free turbine drives the generator (s) on the second gear line of the reduction unit by a connecting shaft equipped with a free wheel and a brake or on a third gear line mounted with a freewheel on a connecting shaft equipped with a reversible decoupling means and a freewheel, as well as on at least a second connecting shaft mounted with a freewheel between the free turbine and generator;

- The reversible decoupling means is chosen from a hydraulic coupler, a dog clutch and a clutch.

BRIEF DESCRIPTION OF THE FIGURES [0017] Other aspects, characteristics and advantages of the invention will appear in the non-limiting description which follows, relating to particular embodiments, with reference to the appended drawings which represent, respectively:

CA 02876952 2014-12-16 WO 2014/001683 7 PCT / FR2013 / 051379 - in figures la and lb, an example of a diagrammatic configuration of energy input supplied by an auxiliary motor of the APU group type to the on-board network and to an electric motor mounted on the shaft of the RAC in the case where the generators of the energy conversion system are mounted directly on the BTP (figure la) or in reversible motor-generator groups (figure lb) mounted on the BTP box ;

FIG. 2, an example of a diagrammatic configuration of energy input by an APU group in which the APU group is integrated into the construction industry and coupled to the electric generators of the energy conversion system or to the construction industry;

- in Figures 3a and 3b, diagrammatic examples of configuration and reducer of this configuration, in the case where the APU group is coupled to the BTP / RAC box via a speed reducer assembly on which is coupled a reversible motor-generator of the energy conversion system and where the generators of this conversion system are mounted on the BTP;

- in Figures 4a and 4b, diagrammatic examples of configuration and reducer of this configuration, in the case where the APU group is coupled to the BTP / RAC box via a speed reducer assembly according to Figures 3a and 3b, and where the generators of the energy conversion system are mounted on the reduction assembly;

- in Figures 5a to 5d, diagrams of the reducer according to Figures 4a and 4b in four operating phases, respectively: starting of the main motors by the APU group on the ground with the connecting shaft of the reducer uncoupled, the APU group and main motors switched on in flight, APU unit off and main engines on in flight, and APU unit on and one main engine inoperative or partially defective;

- in Figures 6a and 6b, diagrammatic examples of configuration and reducer according to Figures 4a and 4b in the case where the energy conversion comprises only generators coupled to the reduction assembly;

CA 02876952 2014-12-16 WO 2014/001683 8 PCT / FR2013 / 051379 - in Figures 7a to 7d, diagrams of the reducer according to Figures 6a and 6b in the four operating phases corresponding to Figures 5a to 5d;

and FIGS. 8a and 8b, two diagrams of reduction assemblies in the case where the auxiliary engine is a gas turbine with a free turbine, respectively without and with a means for reversible coupling of the free turbine.

DETAILED DESCRIPTION OF EMBODIMENTS [0018] In all the figures, identical or equivalent elements, exercising the same function, are identified with identical or derived reference signs.

In the case where several figures represent an element referenced by the same sign, this reference refers to the passage in which the element corresponding to this sign is described.

Referring to Figures la and lb, the schematic architecture configuration illustrates the supply of energy or power (at the moment) supplied by an auxiliary motor 3 of the APU group type to the on-board network 2 as well as 'to the anti-torque rotor (called RAC) 4 or to the main gearbox (called BTP) 40 of a helicopter.

A basic architecture 1 comprises two main engines 5a and 5b which drive, via the BTP 40, the shaft 4B of the main rotor 41 of the helicopter wing and the shaft 4A of the RAC 4.

The main engines 5a and 5b also supply electrical energy in flight to the onboard network 2 via the BTP 40 box.

This basic architecture 1 is completed by the auxiliary engine, the APU group 3 in the example illustrated.

A mechanical / electrical energy conversion system makes it possible to supply electrical energy to the on-board network 2 from the mechanical components, namely: the APU group 3, the BTP 40 gearbox and / or the main engines 5a and 5b .

This conversion system comprises, coupled to each component, and depending on the configurations: at least one dedicated electric generator 6, for example an alternator, at least one reversible electric machine 7 - a motor-generator or motor-generator or starter / generator - , and / or an electric drive motor 8 or 8a, for example a starter or a dedicated electric motor.

CA 02876952 2014-12-16 WO 2014/001683 9 PCT / FR2013 / 051379 [0021] More specifically, the APU group 3 is coupled to a starter 8, actuated by a battery 8b, and to an electric generator 6.

Once the APU group has started, the generator 6 supplies electrical energy to the onboard electrical network 2 of the helicopter on the electrical line B, as well as to the starters 8 of the main motors 5a and 5b on the electrical line A via electronics. power 9.

The BTP 40 also supplies electrical energy to the on-board network 2 via generators 6 (Figure 1a) or motor-generators 7 (Figure 1 b) on lines C. The use in flight of the power delivered by the generator 6 of the APU group 3 to supply the electrical network 2 of the helicopter then makes it possible to modulate until the electrical offtake made on the generators 6 or the motor-generators 7 connected is eliminated. at BTP 40.

In addition, the generator 6 in conjunction with the APU group 3 supplies - via the power electronics 9- either the electric motor 8a, dedicated to driving the shaft 4A of the RAC 4 or the main rotor 41 via the BTP 40 (figure la), or at least one of the motors of the motor-generators 7 substituted for the generators 6 (figure lb).

The dedicated electric motor 8a is, in the example, mounted on the shaft 4A of the RAC 4, but it can be mounted on the BTP or on the shaft 4B of the main rotor 41 in other mounting examples.

[0024] Alternatively, the main motors 5a and 5b can be coupled to a reversible electric machine or to an electric generator - with a separate starter - in order to generate the electricity.

The modulation of the electrical supply operated by the supply of power originating from the auxiliary motor again makes it possible to reduce to the point of eliminating the electrical offtake operated on the main motors.

In an example of operation of the APU group 3 during a mission, first on the ground and then in flight, the different phases of the energy conversion system can succeed each other over time as follows:

- on the ground :

CA 02876952 2014-12-16 WO 2014/001683 10 PCT / FR2013 / 051379 - starting (battery 8b, starter 8) of the APU group 3, - supply of the onboard network 2 and starting of the main engines 5a and 5b by the APU group 3, - supply of the on-board network 2 by the main motors 5a and 5b via the generators 6 (figure la) or the reversible electric machines 7 (figure lb) mounted on the BTP 40, - extinction of the APU group 3;

- flight:

- restarting of the APU group 3 and supplying the onboard network 2 to relieve the offtake on the BTP 40 (figure lb), which generates additional power on the main rotor, - supplying the electric motor 8 on the BTP 40 and / or on the RAC 4 by the APU group 3, making it possible to increase the power on the main rotor 41.

An architectural configuration diagram of the type illustrated in FIG. 2 makes it possible to optimize the integration of the auxiliary engine, here an APU group 30.

A speed reduction assembly, of the type described below with freewheel (s) and dog clutch or equivalent (see for example the description with reference to FIG. 6b), is advantageously integrated to achieve such an optimization by allowing to provide propulsive and non-propulsive energy.

In this example, the APU group 30 is equipped with known connection means to allow its direct integration into the BTP 40, which is coupled to the electric generators 6 of the energy conversion system.

The APU 30 group is then able to provide:

- electrical energy to the on-board network 2 and to the power electronics 9 via the generators 6 on the BTP 40, and - mechanical propulsion energy to the main rotor 41 via the BTP 40 and / or directly to RAC drive shaft 4A 4.

CA 02876952 2014-12-16 WO 2014/001683 ii PCT / FR2013 / 051379 [0027] In addition, the integration of the APU group 30, or more generally of any auxiliary motor, advantageously makes it possible to pool certain functions or equipment (reduction of speed, oil circuit, etc.) and limit interfaces.

[0028] Alternatively or in combination with the solutions of electric transmission of the energy input of the auxiliary engine, such as those described above, solutions of mechanical transmission between the auxiliary engine and the drive of the BTP / RAC assembly -via a speed reducer assembly are now described.

These mechanical architecture configurations make it possible to meet the same needs.

Referring to Figures 3a and 3b, examples of architectural configuration diagrams and a reduction gear of this architecture are illustrated.

In this configuration, the energy conversion system is formed by the generators 6a and 6b coupled to the BTP 40 and by a motor-generator 7 coupled to a speed reduction assembly 11a to supply electrical energy to the on-board network. 2 and power electronics 9.

The battery 8a is here directly connected to the power electronics 9 in order only to supply and start the motor-generator 7 of the APU group 3.

The APU auxiliary unit 3 is coupled to the shaft 4A of the RAC 4 via the speed reduction assembly 11a, to which the energy conversion motor-generator 7 is coupled.

Alternatively, the APU group can be coupled to the BTP and the generators 6a and 6b can be replaced by reversible or dedicated machines integrated on the main engines (alternative not shown).

The reduction unit IIa constitutes with the BTP 40 a mechanical transmission system.

In the non-limiting example illustrated, the reduction unit 11a directly connects the APU group 3 to the shaft 4A and to the reversible motor generator 7.

As shown in Figure 3b, the reduction unit 11a comprises two parallel lines of speed reduction gears, 111 and 112, coupled by at least one connecting shaft 11L between the APU group 3 and the socket movement CA 02876952 2014-12-16 WO 2014/001683 12 PCT / FR2013 / 051379 11M on the BTP 40 or the RAC 4.

The BTP 40 provides mechanical power over time to the main rotor 41.

In the gear line 111, the APU group 3 supplies mechanical power to the equipment 15 (pump, charge compressor, etc.) and to the motor generator 7.

The 11M power take-off on the BTP 40 / RAC 4 assembly is geared to line 112.

The connecting shaft 11L is equipped with a reversible decoupling means, here a dog clutch 12, and a freewheel 13a.

The dog clutch 12 is used to disconnect the APU group 3 so that this group 3 does not drive on the ground (in the operating phases where the APU group 3 is conventionally used), the BTP 40 and / or the RAC 4 (hereinafter BTP / RAC assembly), and more particularly the main rotor 41.

The freewheel 13a makes it possible to prevent in flight, and continuously (that is to say without risk of malfunction under standard conditions), that the main rotor 41 ¨ driven by the main motors does not in turn drive the APU group 3.

In addition, the freewheel 13a also allows the ground to be able to reconnect the dog clutch 12 at zero torque.

Under these conditions, the reduction assembly 11a advantageously makes it possible to reduce the speed between the APU group 3 and the power take-off 11M on the BTP 40 / RAC 4 assembly, in order to be able to inject mechanical power.

The power of the APU unit in flight on the BTP / RAC assembly is then supplied as needed.

An improvement in the performance of the helicopter in flight is obtained in particular in the following cases:

- by the supply of the on-board electrical network 2 by the motor generator 7 to make it possible to reduce or even eliminate the electrical offtake on the generators 6a and 6b connected to the BTP 40;

- by the use of the freewheel 13a to drive only the generator of the motor-generator 7 by the auxiliary motor (the APU group 3) CA 02876952 2014-12-16 WO 2014/001683 13 PCT / FR2013 / 051379 when the main rotor 41 rotates (the speed of the auxiliary motor always remaining lower than that of the main rotor);

- by the alternative or cumulative supply of mechanical power to the BTP 40 / RAC 4 assembly from the reducer.

[0036] According to a variant, the generators of the conversion system are integrated on the reduction gear and not on the BTP.

This variant is illustrated by Figures 4a and 4b, with examples of architectural and reducer configuration diagrams where the APU group 3 is coupled to the BTP 40 / RAC 4 assembly via the speed reducer assembly 11a, and where the generators 6a and 6b of the energy conversion system are mounted on the reduction assembly 11a.

The reduction assembly 11a (Figure 4b) uses the elements of Figure 3b, with the gear lines 111 and 112, the connecting shaft 11L, the clutch 12 and the freewheel 13a, arranged in the same way.

The generator 6a is then mounted directly on the connecting shaft 11L and the generator 6b is driven on an additional gear pinion 11P.

Alternatively, the dog clutch 12 can be placed on a link line different from the link 11L, so as to only drive a single electrical machine on the ground.

Figures 5a to 5d illustrate four operating phases of the gear 1 1 a: when the APU group 3 is lit on the ground while the main engines 5a / 5b are off (figure 5a), when the APU group 3 and the main engines 5a / 5b are lit on the ground or in flight (figure 5b), when the APU group 3 is off and the main engines 5a / 5b on in flight (Figure 5c), and when APU group 3 is on and a main engine is inoperative or in partial failure (Figure 5d).

Referring to Figure 5a, the connecting shaft 11L is decoupled and the APU group 3 provides mechanical power (arrow F1) to the equipment 15 as well as to the motor-generator 7 for supplying the electrical network to board 2 and power electronics 9 (figure 4a).

CA 02876952 2014-12-16 WO 2014/001683 14 PCT / FR2013 / 051379 [0040] With reference to FIG. 5b, the APU group 3 always supplies mechanical power (arrow F1) to its equipment 15 and to the generator of the motorcycle - generator 7 (if the need for additional power is expressed, for example for the on-board network) via the gear line 112.

The dog clutch 12 being engaged (arrow F2), the APU group 3 can also supply mechanical propulsive power - via the gear line 111- to the power take-off 11M of the BTP 40 / RAC 4 assembly (arrow F3) to supply propulsive power in particular to the RAC rotor 4, as well as to the generators 6a and 6b (arrows F4) to supply electrical power to the on-board network.

The main engines 5a / 5b being switched on, the BTP 40, also driven by these engines 5a / 5b, can also transmit power to the generators 6a / 6b.

Referring to Figure 5c, the APU group 3 being off but the engines 5a / 5b on, the RAC 4 is driven (arrow f3) by the BTP 40, itself driven by the engines 5a / 5b and then transmits the power to the generators 6a and 6b (arrows F4) to supply the non-propulsive power to the on-board network 2, but does not transmit power to the APU group 3 since the freewheel 13a is disconnected.

Referring to Figure 5d, a main engine being at idle or stopped (voluntarily or involuntarily) and the clutch 12 engaged (arrow F2), the APU group 3 provides on the gear line 112, via the shaft link 11L, all the non-propulsive power and part of the propulsive power (the arrow F5 in dotted lines indicates that the drawdown on the BTP 40 is then reduced, thus increasing the power on the main rotor 41), namely:

- the mechanical power (arrow F1) to the equipment 15 and to the generator of the motor-generator 7 (if necessary), - the propulsive power to the power take-off 11M of the BTP 40 / RAC 4 assembly (arrow F3), in particular to the RAC 4 and possibly to the main rotor 41, as well as - non-propulsive power to the generators 6a and 6b (arrows F4) to supply electric power.

CA 02876952 2014-12-16 WO 2014/001683 15 PCT / FR2013 / 051379 [0043] A variant of the previous configuration, illustrated by Figures 6a and 6b, uses the same diagrams as Figures 4a and 4b.

But the architectural configuration of FIG. 6a presents an energy conversion system constituted only by the generators 6a and 6b, coupled to a reduction assembly 11b, that is to say without the motor-generator 7 of FIGS. 3a. / 3b and 4a / 4b.

A specific starter 8a comprising a freewheel (not shown) activated by the battery 8b is therefore used.

Alternatively, this starter 8a can be replaced by a reversible direct current or alternating current machine in order to meet an additional need (safety, reliability, power level, etc.).

This electric machine will only be driven by the APU group.

Referring to Figure 6b, the connecting shaft 11L is equipped with the reversible dog clutch 12 and the freewheel 13a to drive the power take-off 11M of the BTP 40 / RAC 4 assembly, like the connecting shaft 11L (Figures 3b and 4b). The connecting shaft 11N also drives, on a third gear line 113, the generators 6a and 6b via gear pinions 11P.

The third gear line 113 is mounted via freewheels 13b and 13c respectively on the connecting shaft 11L and on a second connecting shaft 11N between a generator 6b and the APU group 3.

The generators 6a and 6b of the APU group 3 are used on the ground in conventional APU mode, which makes it possible with this configuration to pool the electrical generation functions.

The reduction unit 11b has the same advantages as the assembly 11a as presented above, in particular the main rotor cannot be driven on the ground, and the auxiliary motor (APU group 3) is not trainable by the main rotor in flight.

In addition, the energy conversion generators 6a and 6b are driven by the auxiliary engine on the ground when the engines are off, and by the MGB on the ground or in flight when the auxiliary engine is off (or even when its speed of rotation is lower than the speed of the shaft 11L, the freewheels 13a and 13c then being released).

CA 02876952 2014-12-16 WO 2014/001683 16 PCT / FR2013 / 051379 [0047] More particularly, the diagrams of FIGS. 7a to 7d illustrate the same four operating phases of FIGS. 5a to 5d when the reduction assembly is of the type 11b, illustrated in Figure 6b.

Referring to Figure 7a, the connecting shaft 11L is decoupled and the APU group 3 provides mechanical power (arrows F1) to the equipment and to the reversible machine 8 in order to provide electrical energy if necessary, as well as the electric power via the generators 6a and 6b by the second connecting shaft 11N (arrows F6).

If the machine 8 is a simple starter, a freewheel is advantageously integrated to avoid driving it unnecessarily.

Referring to Figure 7b, the APU group 3 still provides mechanical power (arrows F1) to its equipment 15 and to the reversible machine 8 (if necessary) via the gear line 111.

The dog clutch 12 being engaged (arrow F2), the APU group 3 can also supply mechanical propulsive power - via the gear line 112- to the power take-off 11M of the BTP 40 / RAC 4 assembly (arrow F3 ) to provide propulsive power in particular to the RAC 4 rotor.

The APU group 3 can also supply mechanical power to the generators 6a and 6b (arrows F4) via the gear line 113 to deliver electrical power to the on-board network 2.

The APU group 3 can also directly supply power to the generators 6a and 6b via the connecting shaft 11N, in particular when the dog clutch 12 is disconnected.

But the main engines 5a / 5b being switched on, the BTP 40, driven by these engines 5a / 5b, can also transmit power to the generators 6a and 6b (arrow F7).

Referring to Figure 7c, the APU group 3 being off but the engines 5a / 5b on, the BTP 40 -driven by the engines 5a / 5b- then transmits power to the generators 6a and 6b (arrows F7) to supply the non-propulsive power to the on-board network 2, but does not transmit power to the APU group 3 because the freewheels 13a and 13b are disconnected.

CA 02876952 2014-12-16 WO 2014/001683 17 PCT / FR2013 / 051379 [0051] With reference to FIG. 7d, a main engine 5a being at idle (arrow F5 in dotted lines) or stopped (voluntarily or involuntarily) and the clutch 12 engaged, the APU group 3 supplies mechanical power (arrow F1) to the equipment 15 and to the reversible machine 8 (if necessary), propulsive power to the power take-off 11M of the BTP 40 / RAC 4 assembly (arrows F3) - in particular to the RAC 4 and possibly to the main rotor 41 as well as to the generators 6a and 6b (arrows F4) to provide electrical power to the on-board network 2.

Thus, the APU group 3 supplies on the gear lines 112 and 113 all the non-propulsive power and part of the propulsive power.

The APU group 3 can also directly supply power to the generators 6a and 6b via the connecting shaft 11N (arrow F8), in particular when the dog clutch 12 is disconnected.

The previous architectures have an auxiliary engine of the APU group type, having a single power shaft (for example: diesel engine or linked turbine).

For an auxiliary engine having a main engine type power free turbine, two power shafts are available: the free turbine shaft and the gas generator shaft.

Two architectures of reduction assemblies 11c and 11d are described below with reference to FIGS. 8a and 8b to illustrate the power take-off from the two shafts of a free turbine gas turbine 10 as an auxiliary engine.

In these Figures 8a and 8b, the reduction assemblies 11c and 11d are respectively without and with a dog clutch 12, as means of reversible coupling of the shaft 10L of the free turbine 100.

The diagram of the reducer of figure 8a resumes that of figure 4b, with two lines of gears 111 and 112, and that of figure 8b takes again the diagram of reducer 6b, with three lines of gears 111 to 113.

Referring to Figure 8a, the reduction assembly 11c is a double gear line 111 and 112. The shaft 10L of the free turbine 100 drives the generators 6a and 6b on the second gear line 112, via the connecting shaft 11L mounted with the freewheel 13a. The connecting shaft 11L does not have CA 02876952 2014-12-16 WO 2014/001683 18 PCT / FR2013 / 051379 disengagement system, but the freewheel 13a to prevent the free turbine 100 from being driven by the construction industry 40. The shaft 10L is mounted on a portion 111a of the first line of gears 111 via a brake 17. The shaft 10G of the gas generator 101 of the gas turbine 10 is mounted on a portion 111b of the first line of gears. gears 111, independent of the portion 111a. The shaft 10G drives on this line 111b the equipment 15 and the generator of the motor-generator 7, independently of the free turbine 100.

The brake 17 makes it possible to block the shaft 10L of the free turbine on the ground in order to use the gas turbine 10 in conventional operation of an APU group (APU mode: electrical generation by the motor-generator 7 and generation pneumatic by a charge compressor on the 10G shaft of the gas generator, etc.).

This brake 17 can be advantageously shared with the brake of the shaft of the rotor RAC 4.

This architecture is similar to a three-engine helicopter architecture in which the third engine - forming the auxiliary engine - is asymmetrical in power compared to the other two.

The architecture of the reduction assembly 11d, illustrated in FIG. 8b, incorporates all the elements of the reduction assembly 11b of FIG. 6b with the same functions.

The difference in structure relates to the independence of the connections of the shaft 10L of the free turbine 100 of the gas turbine 10, mounted on the portion 111a, and of the shaft 10G of the gas generator 101 of this gas turbine. gas 10, mounted on portion 111b.

The gas turbine 10 in this architecture replaces the APU group 3 of FIG. 6b as an auxiliary engine.

In particular, the third gear line 113 is mounted with a freewheel 13b on the connecting shaft 11L equipped with a reversible clutch 12 or equivalent and the freewheel 13a, as well as on the second connecting shaft 1 1 N with a freewheel 13c, between the shaft 10L of the free turbine 100 and the power supply generator 6a.

Thus, the accessories (equipment 15: pump, charge compressor, etc., and starter 8a) connected to the gas generator 101 are separate CA 02876952 2014-12-16 WO 2014/001683 19 PCT / FR2013 / 051379 accessories (generators 6a and 6b and helicopter equipment: BTP 40, RAC 4, etc.) connected to the free turbine 100.

A regulation of the auxiliary free turbine engine will be different from that of the turbine engine linked when the auxiliary engine is connected to the BTP / RAC socket assembly because this RAC is then linked to the free turbine 10 and not to the generator of gas 101 [0059] The invention is not limited to the examples described and shown, in particular the freewheels can be replaced by equivalent means (decoupling sleeve, viscous coupling, epicyclic gear, etc.) or the different components (freewheel, dog clutch, etc.) can be placed differently on the different sprocket lines.

The scope of auxiliary engine terminology extends to engines of technology other than that of a gas turbine (eg diesel engine, fuel cell, etc.).

Thus, this auxiliary engine can be the engine of a tri-turbine helicopter of smaller dimensions and performance than those of the other two main engines.