On a conventional turboprop engine, the propeller is driven by a gas turbine (free turbine or linked turbine) via a reduction gear, the reduction gear placed between the propeller and the turbomachine can be of different types: simple gear train, Compound gear train, planetary, epicyclic, etc. In the same way, on a conventional helicopter, the main rotor which comprises the blades of the helicopter is also driven by a gas turbine via a reduction gear consisting of a main transmission box (BTP).

The propeller fitted to such a turboprop, as well as the main rotor 5 of a helicopter, are generally equipped with a de-icing system making it possible to take off the ice accumulating on the blades of the propeller or of the main rotor. Most current de-icing systems are electrical systems comprising, for example, electric heating mats fixed to the lower surface and upper surface of each blade, at the level of the leading edge, which go, when supplied with energy. , create heat to loosen the ice formed on the blade, which will then be ejected by centrifugation. This energy supply to the heating mats requires a power of several kilowatts delivered by a three-phase AC network,

To do this, it is necessary to supply electrical energy to the belts fixed to the blades, via equipment making it possible to transfer this electrical energy from a fixed part in the engine, to a rotating part, the propeller or the rotor. main.

Conventionally, this rotating transfer of electrical energy is carried out using a "brush + collector" system. On a conventional turboprop engine, the transfer is carried out by contact between the manifold mounted on the rear cover of the propeller and made up of one or more track (s) of conductive material, typically copper, and the brushes mounted on the reduction gear. motor and made of a conductive material rubbing against the copper track (s). A variant of this assembly is illustrated by patent EP2730506 issued to the American company Hamilton Sundstrand, with an assembly of the equipment necessary for the rotary transfer (brushes and collector) at the rear of the reducer and not between the reducer and the propeller as carried out. classically.

However, this solution has many drawbacks linked essentially to the friction of the brushes on the tracks of the collector, a significant source of wear of these brushes. This rapid wear therefore requires regular maintenance and then replacement operations, but the lack of knowledge of the real life of the brushes has the consequence of making the system unreliable.

In addition, the brushes are exposed to oil splashes, dust particles (including external particles such as sand, etc.) that can generate electric arcs at the contact level such as to initiate the combustion of flammable elements constituting the rear panel of the propeller (which may contain magnesium) and cause a fire start which may lead to the loss of the turbomachine.

Also, it is known from US Pat. No. 5,572,178 to integrate a single-phase rotating transformer on the motor shaft of an aircraft, in order to achieve a non-contact rotating transfer to supply an electrothermal or electromechanical defrost system of low or medium power. (from 300W to 500W per blade). However, such a solution is not suitable in the case of purely electrical systems requiring transfers of electrical power of the order of 1kW per blade and it would therefore be necessary to resort to a three-phase transformer which conventionally consists of three transformers. single-phase rotating units arranged side by side with the following drawbacks, however:

- the three-phase transformer thus constituted would be bulky in length, making it difficult to integrate on a shaft of the turbomachine without modifying its dimensions, which would have an overall impact on the length of the engine (involving an increase in mass and difficulties in 'integration on the aircraft),

- the mass of such a transformer would necessarily be high, 5 and it would increase with the internal diameter of the latter, and - mounted at the end of the shaft therefore cantilevered on a shaft that can undergo significant forces, l The addition of such a transformer would complicate the dynamics of the shaft line necessary to guarantee a small air gap, typically less than 1mm, over the entire length of this transformer.

Purpose and summary of the invention

The object of the invention is therefore to propose an integration of a rotating transformer in a propulsion unit for an aircraft which allows a contactless transfer of a significant electrical power to a bladed propeller driven by an engine of the assembly. propellant, for example to ensure the de-icing of the propellant blades, and requires little or no structural modifications. A common name of bladed thruster is used to describe both the propeller of an airplane and the main rotor of a helicopter, or a main rotor of a flying drone, the propeller shaft or the main rotor shaft being referred to in the same way as the propellant shaft.

This object is achieved by means of a propulsion unit for an aircraft, comprising an engine and a propellant shaft driven in rotation by the engine, said propellant shaft passing through a sealed casing containing a lubricating fluid, the propulsion unit further comprising a bladed thruster coupled to said thruster shaft and comprising electric power consuming electrical members, the seal between said sealed casing and said propellant shaft being provided by a dynamic seal housed between a rotating support for an integral dynamic seal angularly with said propellant shaft and a dynamic seal support flange integral with an end portion of said casing facing said propellant,said dynamic joint rotating support 0 being secured to said propellant shaft while being held axially in abutment against a support bearing of said propellant shaft, the propulsion assembly being characterized in that, in order to deliver electrical power to said members electrical, it comprises a rotating transformer rotated by said propellant shaft 5 and comprising on the one hand a stator, a housing of which is

secured to said dynamic seal support flange and on the other hand a rotor, a housing of which is secured to said propeller shaft.

Thus, by integrating the transformer directly at the level of the dynamic seal support flange in connection with the propellant shaft, structural modifications of the turbomachine as well as the forces supported by the transformer are limited. The transformer advantageously has a reduced air gap ensuring it is sufficiently compact for this integration.

Advantageously, said fixed part of the turbomachine is an end part of said reduction gear opposite to said propeller.

Preferably, said stator housing is integrated with said dynamic seal support flange to form one and the same part.

Advantageously, said dynamic seal support flange is secured to said housing end portion either by a plurality of screws or by a clamp.

According to one embodiment, said rotor housing is integrated into said dynamic joint rotating support to form one and the same part and said rotor housing is cantilevered on a shoulder of said propeller shaft, so by resting only 0 on a short length of the propellant shaft, it does not follow the bending movements. Said dynamic joint rotating support is clamped between said shoulder of said propellant shaft and the support bearing of said propellant shaft.

According to another embodiment, said rotor housing is secured to said propellant shaft by clamping between a shoulder of said propellant shaft and said rotating dynamic seal support.

Advantageously, said electric members each comprise one or more electric defrosting elements and said electric power is supplied to said paddle thruster for supplying said electric defrosting elements.

The invention finds application in particular to a turboprop or a turbojet for an airplane turbofan, a helicopter turbine engine or an electric motor for a flying drone.

Brief description of the drawings

Other characteristics and advantages of the invention will emerge from the following description of particular embodiments of the invention, given by way of non-limiting examples, with reference to the appended drawings, in which:

- Figure IA is a perspective schematically showing a first example of an aeronautical turbomachine allowing an implementation in accordance with the invention,

FIG. IB is a schematic view of a second example of an aeronautical turbomachine allowing an implementation in accordance with the invention,

FIG. 2 very schematically illustrates the integration of a transformer rotating with axial flow on a shaft of the turbomachine of FIG. IA,

FIG. 3 very schematically illustrates a variant of integration of a transformer rotating with axial flow on a shaft of the turbomachine of FIG. IA,

- Figure 4 shows a detail of assembly by collar of the transformer of Figure 2, and

0 - Figure 5 very schematically illustrates the integration of a transformer rotating radial flow on a shaft of the turbomachine of Figure IA.

5 Detailed description of embodiments

The principle of the invention is based on a particular integration in a transmission box or a reduction unit of an aeronautical turbomachine of a three-phase transformer rotating with radial flow of the “U-shaped” type (called TFU in the remainder of the document) or with axial flow. of type 0 "in E" (called TFE in the remainder of the document) as described for example in applications WO2013 / 167827 to WO2014 / 167830, the content of which is incorporated by reference, for the transfer of electrical power to a turbomachine propeller or a helicopter rotor and allowing, for the same electrical power, a gain in weight and size compared to a conventional three-phase transformer.

By aeronautical turbomachine, it is appropriate to consider both a turboprop or an airplane turbojet, a turboshaft engine

helicopter or an aircraft turbofan, preferably with a high dilution ratio.

As shown schematically in FIG. 1A relating to an airplane turboprop, a propeller 10 comprising a plurality of blades 12 arranged around a hub 14 and each comprising one or more electric de-icing elements 12A to 12D, is connected to a reduction gear 16 via a propeller shaft 18. The reducer is in turn connected to a gas turbine engine 20 of the aeronautical turbomachine via a drive shaft 22. The reducer ensures the speed conversion between the propeller disposed at the front of the reducer and which rotates at a determined speed and the gas turbine engine mounted at the rear of the reducer and which rotates at a much higher speed.

We find almost the same elements bearing the same references in Figure IB relating to a helicopter turbine engine. A helicopter main rotor 10 comprising a plurality of blades 12 arranged around a central body 14 is connected to a transmission box 16 via a rotor shaft 18. The transmission box which consists of a reducer with a large reduction ratio is connected in turn to a gas turbine engine 20 of the aeronautical turbomachine via a drive shaft 22. The gearbox 16 ensures the speed conversion between the rotor which rotates at a determined speed and the gas turbine engine which spins at a much higher speed.

In FIG. 2 which relates more particularly to an airplane turboprop engine (but without this example being limiting), the propeller shaft 18 shown in more detail (however without the various electrical wiring for connection to the de-icing elements and to the electrical power supply which have not been shown so as not to overload the drawing) and comprising in particular at one end of its front part 18A a flange 24 for fixing to the propeller 10, is supported in the reduction gear 16 it passes through a pair of bearings 26, 28, for example roller-type rolling bearings, this reduction gear being enclosed in a sealed casing 16A containing a lubricating fluid. A third bearing (not shown in the drawing) of the ball bearing type can complete the pair of bearings 26, 28 to take up the axial force of the propeller. The propeller shaft generally has in this front part (without this configuration being considered as limiting) a diameter

greater than the diameter of a rear part 18B. Dynamic sealing between the fixed reducer 16 and the rotating propeller shaft 18 is conventionally provided by a dynamic seal 30 housed between a rotating dynamic seal support 32 angularly secured to the propeller shaft 18 and a flange dynamic seal support 34 integral with the gearbox housing 16A. The dynamic seal rotating support is secured to the propeller shaft while being held axially in abutment against the bearing 28 for supporting the propeller shaft.

More precisely, in the embodiment shown in FIG. 2, the dynamic seal rotating support 32 is clamped between a shoulder 18C of the propeller shaft and the bearing 28, for example by means of a support device (not shown) provided to press axially on the bearing 28 in the direction of the shoulder 18C. This support device may for example comprise a nut bearing against the bearing 28 and a ball bearing bearing which may be provided at this location of the propeller shaft. The dynamic seal support flange is for its part fixed to the gearbox casing, advantageously by a plurality of screws 35.

According to a first embodiment of the invention, in order to deliver the electrical power necessary to supply the electrical defrosting element (s), it is proposed to place the rotary axial flow transformer (TFE 36) on this propeller shaft. passing through the reducer, at the output of this reducer (that is to say at the front of the propeller shaft, propeller side), between the flange 24 for fixing to the propeller and the casing 16A of the reducer. This location is chosen in preference to any other because it is present on most current reducer configurations because the length of the propeller shaft is conventionally constrained by the integration at this location of the “brush + collector” system. of the prior art. The transformer 36 coming in

In this first configuration, the stator 38 of the transformer 5 is integral with the reduction gear 16 and the rotor 40 is integral with the propeller shaft 18, a small axial air gap 42, typically less than 1 mm, being formed between the stator and the rotor. More precisely, the stator 38 is secured to the dynamic seal support flange 34 fixed to the gearbox housing by the plurality of screws 35 and which is modified to also serve as a support for a housing of this stator and thus form with the latter a alone and even

5 part 34. In the example illustrated, the rotor 40 is on the other hand simply mounted in a housing 40A shrunk onto the propeller shaft against a shoulder 18D of this propeller shaft.

This fixing of the rotor is of course in no way limiting and in the example of FIG. 3, the housing 40A of the rotor 40 is secured to the propeller shaft by clamping between this shoulder 18D and the rotating support of the dynamic seal. 32, which then extends axially by a tubular part 32A, one end of which bears against the housing 40A.

The advantages provided by this solution allowing the integration of the axial flow transformer on the propeller shaft as close as possible to the reduction gear (and in particular to the bearing 28 supporting the propeller shaft) are in particular the following:

Space saving due to integration into the dynamic sealing system of the gearbox,

0 A reduced propeller shaft overhang and less impact on the dynamics of the propeller shaft line,

A gain in weight because the configuration limits the number of intermediate parts necessary to fix the transformer, and

Limitation of air gap variations facilitated by axial flow mounting which is furthermore less sensitive to the effects of propeller shaft flexures.

In addition, the transformer is no longer a piece of equipment mounted on the reducer, but becomes a full part thereof, and therefore assembled at the same time as the reducer.

0 As shown in the variant of FIG. 4, the dynamic seal support flange 34 supporting the stator can also be assembled to the casing by another means than fixing by screw 35. For example, an assembly solution by collar 44 allows to save space and to bring the stator and the rotor closer to the bearing 28, which limits their deflections in operation.

FIG. 5 schematically illustrates (the electrical wiring having similarly been omitted) the integration of a rotating transformer with radial flux TFU on the propeller shaft 18 at the output of the reducer.

Similarly to the previous embodiment, the dynamic seal support flange 34 is modified by being extended by an axial circumferential wall 34A terminated by a radial return wall 34B to also form the housing of the stator 38 of the transformer, the assembly then constituting one and the same part. On the other hand, in this second embodiment, the rotating dynamic seal support 32 is in turn extended by an axial circumferential wall 32A terminated by a radial return wall 32B to form a rotor housing, the assembly constituting a single and same part held axially by clamping between the shoulder 18C of the propeller shaft 18 and the bearing 28 supporting the propeller shaft 18. In this way,

The advantages provided by this configuration of a TFU allowing integration on the propeller shaft 18 are multiple and in addition to the aforementioned advantages of saving space, mass and an overhang of the propeller shaft. reduced, this radial flow configuration allows the rotor 40 of the transformer to be decoupled from the propeller bending movements in order to limit the air gap variations. In fact, the rotor does not rest directly over the entire available length of the propeller shaft and is therefore not “driven” by the bending movements of this shaft.

In the embodiments described above, the propeller shaft 18 is formed in one piece. It is nevertheless possible to provide a propeller shaft produced in at least two parts, with for example an outer part called "attached flange" comprising the flange 24 for fixing to the propeller, this outer part being mounted so as to rotate. an inner part which carries the dynamic seal rotating support 32 and the shaft support bearing 28. A shoulder can be provided on the inner part of the shaft to form a stop against which the attached flange can be tightened by a nut, and this nut can clamp the dynamic seal rotating support between the attached flange and the shoulder. This embodiment allows in particular a

replacement of the rotating transformer, in the event of an electrical fault, without requiring complete removal of the reducer, but only by removing the propeller and the attached flange, thus facilitating maintenance operations.

With the invention, it is proposed an integration on the propeller shaft at the output of the reducer making it possible to optimize the size and the mass of the TFU and TFE transformer. However, it will be noted that if the aforementioned integration is preferably based on so-called “U” or “E” transformer technologies as described in applications WO2013 / 167827 to WO2014 / 167830, it is clear that they are also applicable for any type of polyphase axial or radial flux transformer.

It should also be noted that if the foregoing description has been made essentially with regard to an aircraft propulsion assembly as shown in FIG. 1A, it is understood that those skilled in the art will have no difficulty in putting into practice The invention works in the propulsion unit of a helicopter illustrated in FIG. IB and in which the sealed casing of the main gearbox (comprising a reduction gear capable of driving the main rotor of the helicopter) is similar to the aforementioned sealed casing . Likewise, the implementation of the invention at the level of the main rotor shaft of the helicopter is similar to that described above at the level of the propeller shaft of the airplane.

Likewise, a person skilled in the art will be able, without showing any proof of inventive step, to take as the sealed casing the sealed casing of an electric motor of a flying drone and as the propellant shaft the output shaft of this motor ensuring a direct drive of the motor. propellers (its bladed thruster) of this flying drone.

It will also be noted that if the present invention has been developed within the framework of the electrical rotary transfer for the supply of a propeller blade defrosting system, it is of course also applicable to all electrical components consuming electrical power and requiring therefore a rotating transfer of electrical energy to a propellant with blades whatever its use. These electrical components can thus be, without this list being exhaustive: a propeller pitch actuation system, a propeller balancing system, a system of measurements on the rotating part for example.

CLAIMS

1. Propulsion assembly for an aircraft, comprising an engine (20) and a propellant shaft (18) driven in rotation by the engine, said propellant shaft passing through a sealed casing (16A) containing a lubricating fluid, the propulsion assembly further comprising a propellant (10) with blades (12) coupled to said propellant shaft and comprising electrical members (12A - 12D) consumers of electrical power, the seal between said sealed housing and said propellant shaft being ensured by a dynamic seal (30) housed between a rotating dynamic seal support (32) secured angularly with said propellant shaft and a dynamic seal support flange (34) secured to an end portion of said facing casing of said thruster (10),said rotating dynamic joint support being secured to said propellant shaft while being held axially in abutment against a bearing (28) for supporting said propellant shaft, the propulsion assembly being characterized in that, in order to deliver electrical power to said electrical members, it comprises a rotating transformer (36) rotated by said propellant shaft and 0 comprising on the one hand a stator (38) of which a housing (34A, 34B) is secured to said dynamic seal support flange and on the other hand a rotor (40), a housing (40A; 32A, 32B) of which is secured to said propellant shaft.to deliver electrical power to said electrical components, it comprises a rotary transformer (36) rotated by said propellant shaft and 0 comprising on the one hand a stator (38) of which a housing (34A, 34B) is secured to said dynamic seal support flange and on the other hand a rotor (40), a housing (40A; 32A, 32B) of which is secured to said propellant shaft.to deliver electrical power to said electrical components, it comprises a rotary transformer (36) rotated by said propellant shaft and 0 comprising on the one hand a stator (38) of which a housing (34A, 34B) is secured to said dynamic seal support flange and on the other hand a rotor (40), a housing (40A; 32A, 32B) of which is secured to said propellant shaft.

2. Aircraft propulsion assembly according to claim 1, characterized in that said stator housing is integrated with said dynamic seal support flange to form one and the same part.

3. Propulsion assembly for an aircraft according to claim 1 or 0 to claim 2, characterized in that said dynamic seal support flange is secured to said housing end portion by a plurality of screws (35).

4. Aircraft propulsion assembly according to claim 1 or claim 2, characterized in that said seal support flange

dynamic is secured to said housing end portion by a clamp (44).

5. Aircraft propulsion assembly according to claim 1, characterized in that said rotor housing is integrated into said dynamic joint rotating support to form one and the same part.

6. Aircraft propulsion assembly according to claim 5, characterized in that said rotor housing is cantilevered on a shoulder (18C) of said propellant shaft, so that it rests only on a short length of the propellant shaft it does not follow the bending movements.

7. Aircraft propulsion assembly according to claim 6, characterized in that said dynamic joint rotating support (32) is clamped between said shoulder of said propellant shaft and the bearing (28) for supporting said propellant shaft.

8. Aircraft propulsion assembly according to claim 1, 0 characterized in that said rotor housing is secured to said propellant shaft by clamping between a shoulder (18D) of said propellant shaft and said dynamic joint rotating support.

9. A propulsion unit for an aircraft according to any one of claims 1 to 8, characterized in that said electrical members comprise one or more electrical de-icing elements (12A -12D) and said electrical power is supplied to said bladed thruster for the supply of said electrical defrosting elements.

0 10. A propulsion unit for an aircraft according to any one of claims 1 to 9, characterized in that said engine consists of a turboprop or an airplane turbofan engine, a helicopter turbine engine or a flying drone electric motor.