Improved aircraft propulsion system

Abstract

Improved aircraft propulsion unit Propulsion unit (1, 1', 1'') for aircraft comprising at least two electric motors (20, 30) configured to be arranged in a wing (110) of the aircraft and each comprising a rotor having a motor shaft (22, 32) movable about a motor axis (X), at least one propeller (10) carried by a propeller shaft (12) movable about a propeller axis (A) and mechanically coupled to the motor shaft (22, 32) of the at least two electric motors (20, 30), the propeller axis (A) being perpendicular to the motor axis (X) of the at least two electric motors (20, 30). Figure for abstract: Fig. 2.

Description

Title of the invention: Improved aircraft propulsion system Technical field

[0001] The present invention relates to the general field of electric motor propellers intended to be arranged in the wings of aeronautical vehicles such as electrically powered aircraft, but not exclusively. The invention relates in particular to a propulsion assembly for aircraft comprising such electric motors, and to an aircraft comprising this propulsion assembly. Prior art

[0002] Propulsion systems (called "e-Propeller"), comprising an electric motor driving a rotating propeller, in particular via a mechanical power transmission, are used in a known manner in the field of aeronautics. In particular, these "e-Propeller" propulsion systems can be used on drones, flying taxis, small electric or hybrid thermal / electric aircraft. In the latter two cases, the "e-Propeller" systems are generally distributed along the wings or at the wingtips. The electrical energy comes from a battery (all electric) or via a generator driven by a thermal engine (hybrid).

[0003] The location of these "ePropellers" propulsion systems is not conventional and raises new integration issues. Furthermore, the increase in power requirements and the need for redundancy tend to multiply the number of electric motors required. However, the motors of these different existing propulsion systems generally have significant diameters and lengths, making their integration complex. In addition, certain motor architectures, requiring in particular the presence of reducers, result in a considerable increase in size, particularly in the case of the use of several motors or several propellers. This size significantly penalizes the aerodynamic performance of the aircraft. These various constraints make the integration of these systems into an aircraft wing complex.

[0004] There is therefore a need for an aircraft propulsion system, comprising electric motors, making it possible to overcome at least in part the aforementioned drawbacks. Statement of the invention

[0005] The present disclosure relates to a propulsion unit for aircraft comprising: - at least two electric motors configured to be arranged in a wing of the aircraft and each comprising a rotor having a motor shaft movable around an axis engine, - at least one propeller carried by a propeller shaft movable around a propeller axis and mechanically coupled to the motor shaft of the at least two electric motors, the propeller axis being perpendicular to the motor axis of the at least two electric motors.

[0006] It is understood that the propeller shaft is coupled to both of the electric motors via the drive shaft of each of them. The propeller is therefore driven in rotation by each of the motors. The axes of the motors are preferably both centered on the same motor axis and are both perpendicular to the propeller axis.

[0007] The architecture defined in the present disclosure allows the integration of the propulsion assembly within a wing of the aircraft, by offering the possibility of orienting the electric motors in the direction of the wing, while keeping the propeller axis perpendicular to the wing. This architecture also makes it possible to use several electric motors and to drive one or two propellers, potentially counter-rotating. In particular, taking into account the fact that the motors are installed perpendicular to the propeller axis, the propeller shaft may be through and have a second propeller.

[0008] This architecture also makes it possible to reduce drag. Indeed, the profile of a wing is defined to obtain the best aerodynamic performances. It comprises a wide and rounded leading edge and gradually evolves towards a thin and slender trailing edge. According to the architecture of the present disclosure, the electric motors can be placed in the leading edge area (in the main direction of the wing) which naturally has the largest available volume. In particular, the electric motors according to the present disclosure can be entirely arranged in a region of the wing closer to the leading edge than to the trailing edge.Conversely, in an architecture according to the prior art, in which the axes of the engines are arranged parallel to the propeller axis, the wing would necessarily have to be thicker locally, between the leading edge and the trailing edge over the entire length of the engine to be able to accommodate the latter, thus increasing the drag.

[0009] Thus, the electric or hybrid thermal / electric propulsion unit according to the present disclosure is particularly suitable for electrically powered aircraft such as drones, flying taxis, electric helicopters, or electric or hybrid thermal / electric aircraft.

[0010] In some embodiments, the drive shaft of each of the electric motors carries a motor bevel gear, and the propeller shaft carries at least one propeller bevel gear meshing with the motor bevel gear carried by the drive shaft of each of the electric motors.

[0011] When the propulsion unit comprises, for example, two motors, each electric motor has a bevel gear carried by its drive shaft and coupled to its rotor. The propeller bevel gear meshes with the two bevel gears of motor thus ensuring the transmission of mechanical power from the electric motors to the propeller. According to this architecture in which the propeller axis is perpendicular to the motor axis, the bevel gears thus allow the angle transmission to be achieved. This configuration also makes it possible to choose the direction of rotation of the propeller depending on the positioning of the gears.

[0012] In some embodiments, a thinned portion of the propeller bevel gear is oriented in a direction opposite to the propeller.

[0013] In some embodiments, a thinned portion of the propeller bevel gear is oriented in the direction of the propeller.

[0014] It is understood in the present disclosure that the bevel gears have a conical, or frustoconical, shape and are axisymmetrical around the axis along which the shaft which carries them extends. Given this conical or frustoconical shape, one axial end of these gears has a smaller diameter (thinned portion) than the opposite axial end.

[0015] Thus, according to this embodiment, the thinned portion of the propeller bevel gear can be oriented in a direction opposite to the propeller. In other words, the section of the propeller bevel gear becomes thinner as one moves away from the propeller, along the propeller axis. According to this case, the propeller gear meshes with a first side of the motor bevel gear of each motor, so that the propeller rotates in a first direction of rotation.

[0016] Conversely, the thinned portion of the propeller bevel gear may be oriented in the direction of the propeller. In other words, the section of the propeller bevel gear becomes thinner as one approaches the propeller, along the propeller axis. According to this case, the propeller gear is arranged at a different position on the propeller shaft, along the propeller axis, so as to mesh with a second side, opposite the first side, of the motor bevel gear of each motor, so that the propeller rotates in a second direction of rotation, opposite the first direction of rotation.

[0017] Consequently, according to this architecture in which the propeller axis is perpendicular to the motor axis, the direction of rotation of the propeller can be chosen independently of the direction of rotation of the electric motors and without increasing the number of parts, by choosing the orientation of the bevel gear of the propeller shaft.

[0018] In some embodiments, the propeller shaft includes a mechanical reducer disposed between the propeller bevel gear and the propeller, and configured to reduce the rotational speed of the propeller relative to the rotational speed of the electric motors.

[0019] Adding an additional mechanical reducer makes it possible to achieve a desired reduction ratio, in the case where the desired reduction ratio is not achievable with a single gear. This mechanical reducer can take the form of an epicyclic train.

[0020] In some embodiments, the propeller shaft comprises a first portion mechanically coupled to the motor shaft of the electric motors, and a second portion carrying the propeller, the first and second portions being radially offset from each other, and meshing with each other via a gear train.

[0021] By "radially offset" is meant that the first and second portions of the propeller shaft are offset relative to each other in a direction perpendicular to the propeller axis, and mesh with each other, preferably by a spur gear train. Thus, the axis of the first portion and the axis of the second portion are parallel to each other, and both perpendicular to the engine axis. This configuration makes it possible to offset the propeller axis relative to the plane in which the electric motors are located. When the propulsion assembly is arranged in an aircraft wing, offsetting the propeller axis relative to the plane of the wing can improve the aerodynamic performance of the craft.

[0022] In some embodiments, the at least two electric motors are arranged on either side of the propeller shaft so as to form a first pair of electric motors, the motor axis being a first motor axis, the propulsion assembly comprising at least a second pair of electric motors each comprising a rotor having a motor shaft movable around a second motor axis parallel to the first motor axis.

[0023] By "arranged on either side", it is understood that a first motor of the pair of motors is arranged on a first side of the propeller shaft, and that a second motor of the pair of motors is arranged on a second side of the propeller shaft, opposite the first side. In other words, the two motors of the pair of motors are arranged opposite each other, on each side of the propeller shaft. In addition, the rotors of the motors of each pair of motors are centered around the same axis. Thus, the rotors of the first pair of motors rotate around the first motor axis, and the rotors of the second pair of motors rotate around the second motor axis. The second motor axis is axially offset relative to the first motor axis, along the propeller axis.

[0024] Thus, the propeller shaft is mechanically coupled with each motor of each pair of motors. This architecture in which the propeller axis is perpendicular to the motor axis or motor axes is therefore compatible with multi-motor drives, while maintaining a limited footprint, which is very advantageous when the high power requirement requires multiplying the number of electric motors.

[0025] In some embodiments, the propeller shaft comprises as many gears conical propellers than pairs of electric motors.

[0026] According to this embodiment, the propeller shaft carries a plurality of propeller bevel gears distributed axially along the propeller shaft, such that each propeller bevel gear meshes with the motor bevel gears of a pair of motors. The mechanical power of the electric motors of each pair of motors can thus be transmitted efficiently to the propeller, while limiting the overall size.

[0027] In some embodiments, the propulsion assembly comprises a single propeller and an additional electric motor, the drive shaft of the rotor of the additional electric motor being parallel to the propeller shaft and being coupled to an end of the propeller shaft opposite the propeller.

[0028] The propeller shaft extends axially between a first and a second end. According to this embodiment, the single propeller is arranged at the first end of the shaft, and the additional electric motor is arranged and coupled to the second end of the propeller shaft. In addition, the motor axis of the rotor of this additional motor is parallel, preferably coincident with the propeller axis. It is thus possible to add an additional motor, in addition to the pair or pairs of motors arranged on either side of the propeller shaft, making it possible to obtain an odd number of electric motors. This star architecture makes it possible to further increase the number of electric motors, and therefore to increase the total power of the propulsion unit, while limiting the total size.

[0029] In some embodiments, the at least one propeller is a first propeller, the assembly including a second propeller disposed at an opposite end of the propeller shaft relative to the first propeller, and oriented in a direction opposite to the first propeller.

[0030] According to this embodiment, the second propeller is arranged on the second axial end of the propeller shaft, and is oriented in a direction opposite to the first propeller. In this case, the first and second propellers are carried by the same propeller shaft, and are coupled to the electric motors via the propeller bevel gear, or the propeller bevel gears when the assembly comprises several pairs of motors. Thus, taking into account this architecture in which the propeller axis is perpendicular to the motor axis, it is possible to arrange a through propeller shaft, comprising a propeller at each of its ends, these propellers being co-rotating.

[0031] In some embodiments, the at least one propeller is a first propeller and the propeller shaft is a first propeller shaft, the propulsion assembly comprising a second propeller oriented in a direction opposite to the first propeller and carried by a second propeller shaft distinct from the first propeller shaft, the second shaft propeller being movable around the propeller axis in a direction of rotation opposite to the first propeller.

[0032] According to this embodiment, the first and second propellers are carried by two separate propeller shafts, and are coupled to the electric motors via a first and a second propeller bevel gear carried respectively by each of the propeller shafts. In this case, each of the first and second bevel gears meshes with opposite sides of the motor bevel gears. Thus, given this architecture in which the propeller axis is perpendicular to the motor axis, it is possible to arrange two propellers on either side of the assembly, these propellers being counter-rotating.

[0033] In some embodiments, the propulsion assembly comprises at least one decoupling means configured to decouple the motors.

[0034] In particular, the decoupling means makes it possible to decouple the motors of a pair of motors, when one of them is faulty. The decoupling means can be achieved by adding a freewheel between each electric motor and its bevel gear, for example.

[0035] The present disclosure also relates to an aircraft comprising a wing extending along a main axis and a propulsion assembly according to any one of the preceding embodiments, the motor axis of the at least two electric motors being parallel to the main axis of the wing.

[0036] The aircraft is preferably an electrically powered aircraft such as a drone, a flying taxi, an electric helicopter, or an electric or hybrid thermal / electric aircraft. When the wing is an aircraft wing for example, the main axis corresponds to the direction in which the wing extends, from its root to its tip. Thus, according to this architecture, the motor axis of the motors is parallel to this main axis, while the propeller axis is perpendicular to the main axis. This architecture thus makes it possible to optimize the integration of the propulsion unit within the wing of the aircraft by orienting the electric motors in the direction of the wing, and by keeping the propeller axis perpendicular to the wing. Brief description of the drawings

[0037] The invention and its advantages will be better understood upon reading the detailed description given below of different embodiments of the invention given as non-limiting examples. This description refers to the appended pages of figures, in which:

[0038] [Fig.l] [Fig.l] is a schematic perspective view of a portion of an aircraft according to a first embodiment,

[0039] [Fig.2] [Fig.2] schematically represents a top view of an assembly propellant according to the first embodiment,

[0040] [Fig.3] [Fig.3] represents a first modified example of the propulsion assembly of [Fig.2],

[0041] [Fig.4A-4B] Figures 4A and 4B respectively represent two alternatives of a second modified example of the propulsion unit of [Fig.2],

[0042] [Fig.5] [Fig.5] represents a third modified example of the propulsion assembly of [Fig.2],

[0043] [Fig.6A-6B] Figures 6A and 6B show a fourth modified example of the propulsion unit of [Fig.2], respectively in a front view and in a side view,

[0044] [Fig.7A-7C] Figures 7A to 7C schematically represent views in person perspectives of different alternatives in which the propulsion unit according to the first embodiment comprises more than two electric motors,

[0045] [Fig.8] [Fig.8] schematically represents a detailed top view of the alternative of Figure 7B,

[0046] [Fig.9] [Fig.9] is a schematic perspective view of an aircraft, and of a portion thereof, according to a second embodiment,

[0047] [Fig. 10] [Fig. 10] is a schematic perspective view of an aircraft, and of a portion thereof, according to a third embodiment. Description of the embodiments

[0048] In the remainder of the description, a “top view” designates a view in a direction perpendicular to both the engine axis X and the propeller axis A, a “front view” designates a view in a direction parallel to the propeller axis A, and a “side view” designates a view in a direction parallel to the engine axis X.

[0049] A first embodiment of the invention will be described with reference to FIGS. 1 to 8. According to this embodiment, a propulsion assembly 1 according to the present description applies to a conventional wing, in particular to a wing 110 of an aircraft 100, fixed to the fuselage 120 of the aircraft 100.

[0050] The wing 110 extends in a main direction, from its root fixed to the fuselage 120, to its end opposite the root. The propulsion unit 1 comprises two electric motors 20, 30, arranged in the wing 110. The rotors of these motors (not shown) each rotate around the motor axis X, parallel to the main axis of the wing 110. The rotor of the electric motor 20 comprises a motor shaft 22 (not visible in [Fig. 1]), extending parallel to the motor axis X, and the rotor of the electric motor 30 comprises a motor shaft 32 (not visible in [Fig. 1]), also extending parallel to the motor axis X. The axes of rotation of the electric motors 20 and 30 are preferably coincident with each other, and coaxial with the X motor axis.

[0051] The propulsion assembly 1 further comprises a propeller 10 rotatable about a propeller axis A. The propeller 10 is carried by a propeller shaft 12, mechanically coupled to the electric motor 20, and to the electric motor 30, such that the rotation of the rotor of the motors 20, 30 jointly drives the rotation of the propeller 10.

[0052] According to the present disclosure, the propeller axis A is arranged perpendicular to the motor axis X. To do this, the mechanical coupling between the propeller shaft 12 and the motors 20 and 30 comprises bevel gears. More precisely, the motor shaft 22 carries at its end a motor bevel gear 24, rotatable about the motor axis X. Similarly, the motor shaft 32 carries at its end a motor bevel gear 34, rotatable about the motor axis X. In the example illustrated in [Fig. 2], the electric motors 20 and 30 form a pair of coaxial electric motors, arranged such that the motor bevel gears 24 and 34 are opposite each other, along the motor axis X.

[0053] Furthermore, the propeller shaft 12 also carries a propeller bevel gear 14, rotatable about the propeller axis A. The propeller bevel gear 14 is arranged along the propeller shaft 12, so as to mesh with both the motor bevel gear 24 and the motor bevel gear 34. The bevel gears 14, 24 and 34, and the connections between the propeller bevel gear 14 and the motor bevel gears 32, 34 are shown schematically in FIGS. 2 to 8. Given this architecture in which the propeller axis A is perpendicular to the motor axis X, the bevel gears 32, 34 and 14 thus make it possible to produce the angle transmission. Preferably, the ends of the drive shafts and the propeller shaft, and the bevel gears, are arranged inside a casing 50 protecting the latter and the mechanical connections.

[0054] In the examples illustrated in Figures 2 and 3, an upstream-downstream direction is defined as being the direction in which one approaches the propeller 10, along the propeller axis A. Thus, in the example illustrated in [Fig.2], the propeller bevel gear 14 meshes with a downstream side of the bevel gears 32, 34, that is to say the side of the bevel gears 32, 34 closest to the propeller 10. In this configuration, the propeller 10 rotates in a first direction of rotation RL

[0055] Conversely, in the example illustrated in [Fig. 3], the propeller bevel gear 14 meshes with an upstream side of the bevel gears 32, 34, i.e. the side of the bevel gears 32, 34 furthest from the propeller 10. To do this, the propeller bevel gear 14 is arranged further upstream along the propeller axis A, and is oriented in the opposite direction to the propeller bevel gear 14 illustrated in [Fig. 2]. In this configuration, the propeller 10 rotates in a second direction of rotation R2, opposite to the first direction of rotation RL. This possibility of modulating the direction of rotation of the propeller 10, by simply moving the propeller bevel gear 14, is made possible by the architecture of this propulsion unit, in which the propeller axis A is perpendicular to the engine axis X.

[0056] Figures 4A and 4B show modified examples of the propulsion assembly shown in [Fig. 2], in which the propulsion assembly 1 comprises two propellers 10, 10'. In Figure 4A, the propulsion assembly 1 comprises a single propeller shaft 12, and a single propeller bevel gear 14. A first propeller 10 is disposed at the downstream end of the propeller shaft 12, and a second propeller 10' is disposed at the upstream end of the propeller shaft 12, the upstream-downstream direction corresponding to the left-right direction in Figure 4A. According to this example, the two propellers 10, 10' are co-rotating, and both rotate in the first direction of rotation RI. In the example of Figure 4A, the propeller bevel gear 14 meshes with a downstream side of the motor bevel gears 24, 34.However, the propeller bevel gear 14 could also mesh with an upstream side of the motor bevel gears 24, 34, so that both propellers 10, 10' both rotate in the second direction of rotation R2.

[0057] In the example of Figure 4B, the propulsion assembly 1 comprises two propeller shafts 12 and 12', and two propeller bevel gears 14 and 14'. More precisely, the first propeller shaft 12 carries at its upstream end, a first propeller bevel gear 14, and carries at its downstream end the first propeller 10. Furthermore, the second propeller shaft 12' carries at its downstream end, a second propeller bevel gear 14', and carries at its upstream end the second propeller 10'. According to this configuration, the first propeller bevel gear 14 meshes with a downstream side of the motor bevel gears 24, 34, and the second propeller bevel gear 14' meshes with an upstream side of the motor bevel gears 24, 34. Therefore, according to this example, the two propellers 10, 10' are counter-rotating, and both rotate in rotation directions RI and R2 opposite to each other.

[0058] [Fig. 5] represents a modified example of the propulsion assembly shown in [Fig. 2], in which the propulsion assembly 1 comprises a mechanical reducer 15 arranged in the casing 50, on the propeller shaft 12, between the upstream end and the downstream end thereof. In other words, the mechanical reducer 15 is arranged between the propeller bevel gear 14 and the propeller 10. In this example, the mechanical reducer 15 takes the form of an epicyclic gear train comprising several wheels having different diameters, so as to reduce the rotational speed of the propeller 10 relative to the rotational speed of the propeller bevel gear 14, and therefore of the electric motors 20, 30. According to this configuration, the propeller shaft 12 comprises two portions, one extending between the propeller bevel gear 14 and the mechanical reducer 15, and the other extending between the mechanical reducer 15 and the propeller 10. These two portions extend both along the helix axis A, and are therefore coaxial.

[0059] Figures 6A and 6B show a modified example of the propulsion assembly in a front view (Figure 6A) and in a side view (Figure 6B). In this modified example, the propeller axis A is still perpendicular to the engine axis X, but is arranged in a plane different from the plane in which the engine axis X is located, i.e. the plane comprising the wing 110.

[0060] In this configuration, the propeller shaft 12 comprises a first portion 121 mechanically coupled to the motor shaft 22, 32 of the electric motors 20, 30, via the motor bevel gears 24, 34. The propeller shaft 12 further comprises a second portion 122 carrying the propeller 10 (not shown in FIGS. 6A and 6B). The first and second portions 121, 122 are radially offset from each other, in a direction perpendicular to the propeller axis A and to the motor axis X.

[0061] Furthermore, the first and second portions 121, 122 mesh with each other via a spur gear train 16. The spur gear train 16 comprises a first wheel 161 carried by the first portion 121, at the downstream end of the latter, and a second wheel 162, carried by the second portion 122 at the upstream end of the latter, and meshing with the first wheel 161.

[0062] According to this configuration, the first portion 121 of the propeller shaft 12 extends along a first axis A', perpendicular to the engine axis X and arranged in the same plane as the latter. Furthermore, the second portion 122 of the propeller shaft 12 extends along a second axis A, corresponding to the propeller axis perpendicular to the engine axis X and arranged in a plane different from the latter, being offset by a distance D relative to the first axis A'.

[0063] Figures 7A-7C show modified examples, in which the propulsion assembly 1 comprises more than two electric motors. Regardless of the configuration, the propulsion assembly comprises at least one pair of electric motors, each of the two motors of the pair of electric motors being arranged on either side of the propeller shaft 12.

[0064] In the example of Figure 7A, the propulsion assembly 1 comprises a pair of electric motors comprising two electric motors 20, 30 arranged on either side of the propeller shaft 12, that is to say facing each other on each side of the propeller shaft 12, so that the axis of rotation of each of these motors extends along the motor axis X, perpendicular to the propeller axis A.

[0065] In the examples of Figures 7B and 7C, the propulsion assembly 1 comprises two pairs of electric motors each comprising two electric motors. A first pair of motors comprises two electric motors 20, 30 with rotation axes coaxial, extending along a first motor axis XI perpendicular to the propeller axis 12. A second pair of motors comprises two electric motors 20', 30' with coaxial rotation axes, extending along a second motor axis X2 perpendicular to the propeller axis 12, and parallel to the first motor axis XI. The second motor axis X2 is set back from the first motor axis XI towards the upstream (relative to the propeller, not shown in FIGS. 7A to 7C). In this example, the propeller axis 12, the first motor axis XI and the second motor axis X2 all extend in the same plane, also comprising the wing 110.

[0066] The examples presented are not limiting, a greater number of pairs of electric motors can be envisaged, for example three, four or more.

[0067] The propulsion assembly 1 may also comprise an odd number of electric motors. Figures 7A and 7C illustrate examples in which the propulsion assembly 1 comprises three and five electric motors respectively. In this configuration, in addition to the pair(s) of electric motors arranged on either side of the propeller shaft 12, an additional electric motor 40 is arranged at the end of the propeller shaft 12, opposite the end carrying the propeller (not shown in Figures 7A-7C), necessarily unique in this case. In particular, the axis of rotation of this additional electric motor 40, more precisely the axis of rotation of the rotor of this motor, is parallel to the propeller axis 12, unlike the electric motors of the pair(s) of electric motors, and is coupled directly to the propeller shaft 12.

[0068] [Fig. 8] is a detailed view of the propulsion assembly 1 according to the example of FIG. 7B, according to which it comprises four electric motors, i.e. two pairs of electric motors. In this case, the propeller shaft 12 carries a first propeller bevel gear 141, meshing with the motor bevel gears 24, 34 of the electric motors 20, 30 of the first pair of electric motors. In addition, the propeller shaft 12 carries a second propeller bevel gear 142, arranged further upstream along the propeller shaft 12 than the first propeller bevel gear 141, relative to the propeller 10, so as to mesh with the motor bevel gears 24', 34' of the electric motors 20', 30' of the second pair of electric motors.It will be noted that the bevel gear 24' is carried by the motor shaft 22' of the electric motor 20', and the bevel gear 34' is carried by the motor shaft 32' of the electric motor 30', the motor shafts 22' and 32' both being coaxial with the second motor axis X2.

[0069] A second embodiment of the invention will be described with reference to [Fig.9]. According to this embodiment, a propulsion unit 1' according to the present disclosure applies to an aircraft 100' of the drone type, having an unconventional wing 110', comprising a lattice structure.

[0070] According to this lattice structure, the wing 110' comprises an annular main arm 115, and a plurality of interconnected arms within this annular arm, as illustrated on the right part of [Fig.9]. These different arms are connected to the annular main arm 115 so as to form connection nodes 114, each connection node 114 corresponding to the junction of three arm portions. The wing 110', comprising the different arms and connection nodes, extends in a horizontal plane, when the aircraft is placed on the ground. A propeller 10' is arranged at each of these connection nodes 114, such that the propeller axis A extends vertically, when the aircraft is placed on the ground.

[0071] The left part of [Fig.9] represents a detailed view of a junction between three arm portions of the wing 110', at one of the connection nodes 114. The propeller 10' is carried by a propeller arm 120, shown schematically in [Fig.9]. In addition, an electric motor is arranged in each of the arms of the wing 110', at the connection node 114, so as to be coupled with the propeller arm 120. More precisely, a first arm 111' of the wing 110' comprises a first electric motor 210, the axis of rotation of which is a first motor axis XI extending along the axis of this first arm. A second arm 112' of the wing 110' comprises a second electric motor 220, the axis of rotation of which is a second motor axis X2 extending along the axis of this second arm.A third arm 113' of the wing 110' comprises a third electric motor 230, the axis of rotation of which is a second motor axis X3 extending along the axis of this third arm.

[0072] Each of these three electric motors 210, 220, 230 comprises a motor shaft (not shown) coupled with the propeller shaft 120, by means of bevel gears (not shown). Thus, each of the motor axes XI, X2, X3 is perpendicular to the propeller axis A. According to this embodiment, the main axis of the wing 110' corresponds to the axis along which each arm of the wing extends. The arms having a cylindrical shape, the main axis of these arms is therefore the axis of these cylinders.

[0073] A third embodiment of the invention will be described with reference to [Fig. 10]. According to this embodiment, a 1” propulsion unit according to the present disclosure applies to a 100” aircraft of the helicopter type, having an unconventional 110” wing, integrated into an upper wall of the helicopter cabin, as illustrated on the right part of [Fig. 10]. A 10” propeller is arranged on this upper wall.

[0074] The left part of [Fig. 10] represents a schematic detailed view of the wing 110”, in particular of the upper wall of the helicopter cabin, in a side view and a top view. This comprises a plurality of electric motors arranged in a star around the propeller shaft 120 carrying the propeller 10”, such that each of these electric motors is mechanically coupled with this shaft 120.

[0075] More specifically, the propulsion unit 1” comprises eight electric motors 210, 220, 230, 240, 250, 260, 270, 280. In this example, the motors 210 and 250 are movable around a first motor axis XI, the motors 220 and 260 are movable around a second motor axis X2, the motors 230 and 270 are movable around a third motor axis X3, and the motors 240 and 280 are movable around a fourth motor axis X4. Each of the motor axes XI, X2, X3 and X4 is perpendicular to the propeller axis A.

[0076] Given the architecture of a helicopter, in which the axis of rotation of the propeller is vertical, the main axis of the wing 110” therefore corresponds to a direction extending in a horizontal plane, perpendicular to the axis of rotation of the propeller. Consequently, any direction extending in this horizontal plane constitutes a main direction of the wing 110”. Thus, each of the engines 210 to 280 extends in a main direction of the wing 110”.

[0077] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

Claims

1. Aircraft (100, 100', 100”) comprising a wing (110, 110', 110”) extending along a main axis and a propulsion assembly (1, 1', 1”) for aircraft (100) comprising: - at least two electric motors (20, 30) configured to be arranged in a wing (110) of the aircraft and each comprising a rotor having a drive shaft (22, 32) movable about a drive axis (X), - at least one propeller (10) carried by a propeller shaft (12) movable about a propeller axis (A) and mechanically coupled to the drive shaft (22, 32) of the at least two electric motors (20, 30), the propeller axis (A) being perpendicular to the drive axis (X) of the at least two electric motors (20, 30), wherein the drive shaft (22, 32) of each of the electric motors (20, 30) carries a motor bevel gear (24, 34), and the propeller shaft (12) carries at least one propeller bevel gear (14) meshing with the motor bevel gear (24, 34) carried by the drive shaft (22,32) of each of the electric motors (20, 30), and in which the motor axis (X) of the at least two electric motors is parallel to the main axis of the wing.,

2. An aircraft (100, 100', 100”) according to claim 1, wherein a thinned portion of the propeller bevel gear (14) is oriented in a direction opposite to the propeller (10), or the thinned portion of the propeller bevel gear (14) is oriented in the direction of the propeller (10).

3. An aircraft (100, 100', 100”) according to claim 1 or 2, wherein the at least two electric motors (20, 30) are arranged on either side of the propeller shaft (12) so as to form a first pair of electric motors, the motor axis being a first motor axis (XI), the propulsion assembly comprising at least a second pair of electric motors (20', 30') each comprising a rotor having a motor shaft (22', 32') movable about a second motor axis (X2) parallel to the first motor axis (XI).

4. An aircraft (100, 100', 100”) according to claim 3, wherein the propeller shaft (12) comprises as many propeller bevel gears (141, 142) as pairs of electric motors.

5. An aircraft (100, 100', 100”) according to any one of claims 1 to 4, comprising a single propeller (10) and an additional electric motor (40), the rotor drive shaft of the additional electric motor (40) being parallel to the propeller shaft (A) and being coupled to a end of the propeller shaft (12) opposite the propeller (10).

6. An aircraft (100, 100', 100”) according to any one of claims 1 to 5, wherein the at least one propeller (10) is a first propeller, the assembly comprising a second propeller (10') disposed at an opposite end of the propeller shaft (12) from the first propeller (10), and oriented in a direction opposite to the first propeller (10).

7. Aircraft (100, 100', 100”) according to claim 1 or 2, wherein the at least one propeller (10) is a first propeller and the propeller shaft (12) is a first propeller shaft, the propulsion assembly comprising a second propeller (10') oriented in a direction opposite to the first propeller (10) and carried by a second propeller shaft (12') separate from the first propeller shaft (12), the second propeller shaft (12') being movable about the propeller axis (A) in a direction of rotation opposite to the first propeller.

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