HYBRID ELECTRIC PROPELLER ASSEMBLY FOR AIRCRAFT

Abstract

The invention relates to a propulsion unit (1) for an aircraft, comprising: a propeller, with a longitudinal axis, provided with variable-pitch blades (6), an electric motor rotating the propeller, a mechanism for controlling the pitch of the blades, in a hub of the propeller, translating axially, a control rod (16) integral in translation with the control mechanism (14) and passing axially through the electric motor to have a downstream end (16b) opposite the propeller, a return spring, in the hub, acting on the control mechanism to force the latter to move towards a blade-feathering position, and, a mechanical locking system (50) connected to the downstream end (16b) of the control rod and configured to allow the control rod and the control mechanism to be held in a propulsion position of the aircraft. Figure for abstract: Figure 3

Description

Title of the invention: HYBRID ELECTRIC PROPELLER ASSEMBLY FOR AIRCRAFT Field of invention

[0001] The present invention relates to the field of distributed hybrid electric propulsion for aircraft. It also relates to an aircraft comprising such hybrid electric propulsion. Technical background

[0002] Current aircraft equipped with a thermal propulsion system are among the largest emitters of greenhouse gases that affect the climate. Hybridization and electrification are ways to reduce greenhouse gases, particularly in the aeronautical field. A propulsion system for an aircraft generally comprises a propeller or a fan that is driven by a gas turbine to move the aircraft. Electric hybridization consists of combining the technologies of fossil fuel combustion engines and electric motors.

[0003] Electrical machines, for example, are electromechanical devices based on electromagnetism allowing the conversion of electrical energy, for example, into mechanical energy (generator mode) or reversibly, allowing the production of electricity from mechanical energy (motor mode). The electrical machine can behave equally in generator mode as in motor mode.

[0004] The available electrical energy is generally used to power various equipment of the aircraft, which allows for example to reduce the mass as well as the maintenance costs but could also allow to drive at least in part a propeller or a fan for its propulsion. Summary of the invention

[0005] The objective of the present invention is to provide a solution allowing on the one hand feathering of the blades of a propeller of an electric propulsion unit, autonomously and independently, and on the other hand to ensure simple locking of the position of the blades in an operating position called "no flight". This operating position allows the propeller to produce thrust in flight.

[0006] We achieve this objective in accordance with the invention by means of a propulsion unit for aircraft, comprising: - a propeller, with a longitudinal axis, fitted with blades with variable pitch angle, - an electric motor for driving the rotation of the propeller, - a blade pitch angle control mechanism, located in a hub of the propeller, movable in translation along the longitudinal axis, - a rod for controlling the movement of the mechanism, which is securely connected in translation to the control mechanism and which passes axially through the electric motor to have a downstream end arranged on the side opposite the propeller relative to the electric motor, - a return spring located in the propeller hub and acting on the control mechanism so as to force the control mechanism to move to a blade feathering position, and - a mechanical locking system connected to the downstream end of the control rod and configured so as to allow the control rod and the control mechanism to be held in a propulsion position corresponding to a blade angle suitable for the propulsion of the aircraft.

[0007] Thus, this solution makes it possible to achieve the aforementioned objective. In particular, such a configuration is simple, of the all-or-nothing type. The spring is integrated into the propulsion unit and supported by the propulsion unit itself. The return spring allows the blades to occupy a feathering position autonomously and without involving additional members such as an actuator. The locking system which is connected to the control rod makes it possible to maintain the control mechanism at least in the “no-flight” position of the blades in a simple, reliable and secure manner.

[0008] The assembly also includes one or more of the following features, taken alone or in combination:

[0009] - the control mechanism comprises a control ring centered on the axis longitudinal and connected to the propeller blades via connecting elements, the control ring being rotated by the propeller hub.

[0010] - the mechanical locking system comprises a frame which is fixed to a housing of the electric motor, a slider to which the downstream end of the control rod is connected, and an axial guide path in which the slider is able to move.

[0011] - the locking system comprises a lever member which is pivotally mounted by relative to the chassis, the chassis comprises a first wall and a second wall which are parallel to each other and to the longitudinal axis, the first and second walls each comprising a guide groove forming said axial guide path and extending along the longitudinal axis, and in that the lever member comprises two parallel plates which are each provided with a through groove forming a split cam path and which are arranged outside the first and second walls, the plates being on the one hand each pivotally mounted relative to one of the first and second walls and are on the other hand connected to each other by a roller, the slide passing, along a radial axis, both the guide grooves and the through grooves.

[0012] - the downstream end of the control rod is connected by a ball joint to a slide extending along an axis, anti-friction rings centered on the axis being arranged on the one hand, between one of the first and second walls and the ball joint and on the other hand, between each plate and one of the first and second walls.

[0013] - the lever member is connected to an actuating device acting on it so as to cause it to pivot.

[0014] - the mechanical locking system is reversible and is configured so as to allow the control rod and control mechanism to move from the feathering position to the propeller blade propulsion position.

[0015] - the frame comprises a first wall and a second wall which are parallel between them and with respect to the longitudinal axis, the first and second walls each comprising a first guide groove extending along the longitudinal axis and forming said axial guide path, as well as a second guide groove which extends in a direction perpendicular to the longitudinal axis, the assembly further comprising the first slider to which the downstream end of the control rod is connected and which passes, along a radial axis, through the first guide grooves, and a second slider passing through the second guide grooves, the first and second sliders being connected to each other by a pair of connecting rods.

[0016] - the return spring is mounted integral in rotation with the control ring, the control rod comprising an upstream part passing through the control ring and which rotates relative to the upstream part via rolling bearings.

[0017] - the rolling bearings comprise an upstream radial rolling bearing and a downstream bearing with axial rolling bearing, the upstream bearing comprising an inner ring secured to the upstream part of the control rod and an outer ring secured to the control ring, the downstream bearing comprising an upstream ring secured to the control ring and a downstream ring secured to the upstream part of the control rod.

[0018] — the downstream end of the control rod comprises a tip carrying the connection kneecap.

[0019] The invention also relates to an aircraft wing comprising at least one propulsion unit as mentioned above.

[0020] The invention further relates to an aircraft comprising at least one wing as mentioned above or at least one assembly as mentioned above. Brief description of the figures

[0021] The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly, upon reading the description ex detailed application which will follow, of embodiments of the invention given as purely illustrative and non-limiting examples, with reference to the appended schematic drawings in which:

[0022] [Fig.l] [Fig.l] is a perspective view of an aircraft wing comprising several propulsion units according to the invention;

[0023] [Fig.2] [Fig.2] is an axial sectional view of an example of a propulsion unit mounted on an aircraft according to the invention;

[0024] [Fig.3] [Fig.3] is a partial axial sectional view of a propeller driven by an electric motor according to the invention;

[0025] [Fig.4] [Fig.4] is a detail view of a propeller blade control mechanism according to [Fig.3];

[0026] [Fig.5] [Fig.5] is a perspective view of an example of a locking system of a blade control mechanism of a propeller according to the invention;

[0027] [Fig.6] [Fig.6] is a perspective view of an example of a locking system of a blade control mechanism of a propeller according to the invention;

[0028] [Fig.7] [Fig.7] is a detailed view of a member of the locking system according to [Fig.6];

[0029] [Fig.8] [Fig.8] represents in perspective a propulsion unit with a locking system in the locked position according to the invention;

[0030] [Fig.9] [Fig.9] represents in perspective the locking system in the unlocked position according to [Fig.8];

[0031] [Fig.10-11] Figure 10-11 shows another embodiment of a locking system in a locked position according to the invention in Figure 10 and the locking system in an unlocked position according to the invention in Figure H;

[0032] [Fig. 12] [Fig. 12] is a front view of the locking system according to Figure 10-11;

[0033] [Fig. 13] [Fig. 13] is a detail view of the locking system in the unlocked position according to Figure 11. Detailed description of the invention

[0034] The invention applies to a distributed electric propulsion unit 1 comprising a propeller 2 or fan with variable-pitch blades. In the present application, the term “distributed” means that the driving power required for propulsion is distributed over several engine components. The propulsion unit 1 is intended to equip, for example, an aircraft 3 and preferably an airplane so as to provide thrust for the movement of the aircraft. The aircraft 3 comprises, in a known manner, two wings 4 arranged on either side of a fuselage (not shown) and each wing 4 is equipped with at least one propulsion unit 1.

[0035] In the remainder of the invention, the term “propeller” is used to designate either a fan or a propeller.

[0036] [Fig.l] represents an example of an aircraft wing 4. The wing 4 extends in a span direction A and is equipped with three propulsion units 1 which are distributed along the span direction A. The propulsion units 1 are arranged on an upstream edge 5 of the wing 4 called the leading edge.

[0037] In the present invention, and generally, the terms "upstream" and "downstream" are defined with respect to the circulation of air with respect to the aircraft and here along a longitudinal axis X. The terms "axial" and "axially" are also defined with respect to the longitudinal axis X. Similarly, the terms "radial", "internal" and "external" are defined with respect to a radial axis Z perpendicular to the longitudinal axis X and with respect to the distance from the longitudinal axis X.

[0038] Each propulsion unit 1 comprises a propeller 2 with a longitudinal axis X which is provided with blades 6 with a variable pitch angle. The blades 6 of the propeller here are not shrouded. Each propeller 2 extends radially outwards from a hub 7 covered for example by a nacelle 8, and it propels the air outside the nacelle 8 to provide the required thrust. Each nacelle 8 extends along the longitudinal axis X. Each propeller 2 comprises for example three blades 6 as shown in [Fig.l]. Of course, the propellers 2 could comprise a different number of blades.

[0039] With reference to [Fig.2], each propeller 2 is driven in rotation around the longitudinal axis X by an electric motor 10. The latter is enclosed by the nacelle 8. The electric motor 10 is powered for example by a battery. Advantageously, the electric motor 10 is connected to a control unit (not shown) which is intended to control it. The control unit can receive information relating to the electric motor 10 and thus send it control commands.

[0040] The hub 7 comprises, for example, housings (not shown) which are intended to receive the root 13 of the blades 6 so as to be able to pivot them along a setting axis B. The setting axis B is, in a non-limiting manner, parallel to the radial axis Z.

[0041] The variable-pitch blades 6 can occupy different angular positions depending on the operating conditions of the propulsion unit 1 and the flight phases concerned. Each blade 6 pivots between a working position (thrust position) and an extreme blade feathering position. In particular, in the so-called “no-flight” thrust position (or propulsion position), the propeller blades 6 make it possible to generate thrust so as to contribute to the forward movement of the aircraft and each have a pitch angle of, for example, 30° relative to the plane of rotation of the blades. In the extreme feathering position, the blades 6 are then as far as possible away from the direction of forward movement of the aircraft, for example in the case failure of the propulsion unit 1, which makes it possible to limit the aerodynamic drag as well as its potential rotation by entrainment effect (wind turbine operating mode). In this last position, the blade pitch angle is positive, and is generally of the order of 90° relative to the plane of rotation of the blades.

[0042] The propulsion unit 1 comprises a control mechanism 14 for controlling the pitch angle of the blades 6. The control mechanism 14 is advantageously located in the hub 7. The control mechanism 14 comprises, for example, a control ring 15 which is centered on the longitudinal axis X and connecting elements (not shown) which connect the blades 6 to the control ring 15. The control ring 15 is advantageously located radially inside the hub 7. The connecting elements are advantageously, but not limited to, connecting rods (not shown). Each connecting rod comprises a first end connected to a root 13 of the blade 6 and a second end connected to the control ring 15.

[0043] In the present example, the control ring 15 is driven in rotation around the longitudinal axis X by the hub 7.

[0044] In Figures 3 and 4, the propulsion unit 1 comprises a control rod 16 which acts on the control mechanism 14. In particular, the control rod 16 extends along the longitudinal axis X between an upstream end 16a and a downstream end 16b. The control rod 16 passes axially through the electric motor 10. The upstream and downstream ends 16a, 16b are on either side of the electric motor 10 axially. More precisely, the control rod 16 comprises an upstream portion 17 which is integral with the control ring 15. In other words, the control rod 16 controls the movement of the control mechanism 14 to which it is integrally connected.

[0045] The upstream part 17 passes through the control ring 15 rotating relative to the upstream part 17 via at least one rolling bearing. The control ring 15 comprises for this purpose a bore 18 passing through along the longitudinal axis X. The upstream part 17 carries in the present example the upstream end 16a. There are two rolling bearings illustrated in this figure and which are called upstream bearing 19a and downstream bearing 19b. Advantageously, but not limitingly, the upstream bearing 19a is a radial bearing and the downstream bearing 18b is an axial bearing.

[0046] The upstream bearing 19a comprises an inner ring 20a which is secured to the upstream part 17 of the control rod 16 and an outer ring 20b which is secured to the control ring 15. The outer ring 19b radially surrounds the inner ring 20a. Rolling members 20c, preferably balls, are arranged between the outer and inner rings. Optionally, the control ring 15 comprises a recess 21 which opens into the bore 18 and onto an upstream lateral surface 22. The outer ring 20b is housed in this recess 21. The downstream bearing 19b comprises an upstream ring 23a secured to the control ring 15 and a downstream ring 23b secured to the upstream part 17 of the control rod 16. The upstream ring 23a is arranged axially upstream of the downstream bearing 23b. Rolling members 23c, preferably balls, are arranged between the upstream and downstream rings 23a, 23b. Optionally, the control ring 15 comprises a recess 24 which is centered on the longitudinal axis. The recess 24 opens on the one hand into the bore 18 and on the other hand onto a downstream lateral surface 24 of the control ring 15. The upstream ring 23a is housed in the recess 24. The downstream ring 23b is for example axially blocked by a stop surface 25 carried by a shoulder 26 (see [Fig.4]) of the upstream part 17 of the control rod 16.

[0047] Advantageously, but not limited to, the upstream and downstream bearings 19a, 19b are lubricated using lubricant so as to guarantee their performance and extend their service life. The lubricant is for example oil or grease.

[0048] With reference to [Fig. 4], a cover 27 is mounted integral in rotation with the control ring 15. The cover 27 is configured so as to isolate the lubricant at this location. The cover 27 is mounted upstream of the control rod 16 and the upstream bearing 19a. For this, the control ring 15 comprises for example a first wall 28 which extends from the upstream lateral surface 22 and along the longitudinal axis X. The first wall 28 surrounds the opening of the recess 21. The cover 27 comprises a bottom 29 and a skirt 30 which extends from the bottom 29 along an axis of revolution C. The skirt 30 comprises a free edge 31 which delimits an opening 32 opening into the interior of the cover 27. The skirt 30 is installed inside the first wall 28 of the control ring 15 and coaxially with the longitudinal axis X. The free edge 31 of the cover 27 is in contact with a portion of the upstream lateral surface 22.The cover 17 makes it possible to contain the lubricant at least from the upstream bearing 19a.

[0049] According to an advantageous, but non-limiting, characteristic, the control ring 15 comprises a second wall 33 which extends from the downstream lateral surface along the longitudinal axis X. The second wall 33 envelops at least a part of the upstream part 17 of the control rod 16. The second wall 33 further extends inside a hollow shaft section 34 which is integral on the one hand with the hub 7, and on the other hand with a drive shaft 35 of the electric motor 10 which is also hollow. The control rod 16 extends through the shaft section 34 and the drive shaft 35. This area is preferably sealed, that is to say there is no lubrication circuit. Nevertheless, a lubricant is contained around the control rod 16.

[0050] In [Fig.4], the control rod 16 comprises a downstream portion 36 which is connected to a locking system 50 described later. The downstream portion 36 carries the downstream end 16b of the control rod. Advantageously, but not limitingly, the part upstream 16a and the downstream part 36 are connected to each other via an articulated connection 37. This makes it possible to contain misalignments during the movement of the control rod 16. The articulated connection 37 is for example a ball joint or is of the cardan type.

[0051] According to an optional characteristic, the control rod 16 comprises a device for adjusting its length 38. For this purpose, the downstream part 36 comprises an upstream end 16bb which is equipped with a threaded rod 39a of which a first end 38aa is housed in a bore 17a of a downstream end 16aa of the upstream part 17. The downstream end 16aa is opposite the upstream end 16a of the upstream part 17. The first end 39aa is mounted in an articulated manner in the downstream end 16aa so as to form the articulated connection 37. The threaded rod 39a comprises a second end 39ab (axially opposite the first end 39aa) which is screwed into a bore 36a of the upstream end 16bb. The threaded rod 39a extends along the longitudinal axis X. A locking nut 39b makes it possible to lock the threaded rod 39a on the downstream part 36.This length adjustment device 38 makes it possible to adjust the length of the control rod 16 when mounting the locking system 50 so as to obtain precise timing of the blades 6, in particular in the propulsion position.

[0052] Still in [Fig.4], the propulsion unit 1 comprises a device 40 for feathering the blades 6 of the propeller 2. Feathering the propeller blades makes it possible to reduce the overall drag of the aircraft which can occur in certain phases of flight where the propellers are not used for propulsion of the aircraft and / or to manage feared events in the electrical chain (presence of an abnormal voltage, passivation of short circuits). Indeed, in the case where the propeller, which is not feathered, is driven in free rotation by the air flow passing through it (Windmilling) this could generate a high voltage level in the electrical lines.

[0053] Advantageously, but not limitingly, an elastic return element 42 is mounted in the propulsion unit 1 and acts on the control mechanism 14 so as to force the control mechanism 14 to move towards a blade feathering position. In the present example, the elastic return element 42 comprises a return spring 43, and preferably a compression spring. Preferably, this is a single return spring 43. The latter extends along the longitudinal axis X and is housed at least partly in a housing 44 of the control ring 15. The housing 44 is annular and centered on the longitudinal axis X. In other words, the return spring 43 is mounted integral in rotation with the control ring 15. One of the walls of the housing 44 is formed by the first wall of the control ring 15. The return spring 43 is partly guided in the housing 44.

[0054] The return spring 43 extends between a first end 43a and a second end 43b. The first end 43a bears for example on the control ring (and preferably on the bottom 45 of the annular housing). Advantageously, the return spring 43 is permanently in abutment against the control ring 15 in the two extreme positions. Advantageously, but not limitingly, the second end 43b bears against a cover 46. The latter is arranged opposite the control ring 15. The cover 46 comprises for example a bottom 47a in which a groove 48 is formed intended to house the second end 43b of the return spring 43. The return spring 43 is advantageously in a compressed state in [Fig.4], which corresponds to the propulsion position.The elastic potential energy of the compressed return spring 43 is used to move the control ring 15 from the propulsion position to the blade feathering position, when the locking system moves to an unlocked position.

[0055] The cover 46 is, in this exemplary embodiment, secured to the hub 17. Advantageously, but not limitingly, the cover 46 comprises for this purpose a cylindrical wall 47b, with an axis centered on the longitudinal axis X, which is fixed to a wall 49 via fixing members 76. The cover 46 is preferably mounted upstream of the hood 27. The space formed between the cover 46 and the hood 27 makes it possible to contain the return spring 43, this space preferably being free of lubricant.

[0056] According to another advantageous, but non-limiting, characteristic, an adjustment member 77 makes it possible to adjust the position of at least one of the elements such as the elastic return element 42 (here the return spring 43) and the control rod 16. The adjustment member is for example a screw which is mounted on the bottom 47a of the cover and which extends along the longitudinal axis X.

[0057] Advantageously, but not limitingly, the return spring 43 surrounds the cover 27. This configuration makes it easier to mount the return spring 43 and the cover 27 because the latter serves as a stop for adjusting the “no flight” propulsion position via the adjustment element 77.

[0058] With reference to figures 3, 5 and 6, the propulsion unit 1 comprises a mechanical locking system 50 connected to the downstream end 16b of the control rod 16. The mechanical locking system 50 is configured so as to allow the control rod 16 and the control mechanism 14 to be held in a propulsion position corresponding to an angle of the blades adapted to the propulsion of the aircraft, i.e. the thrust or “no flight” position.

[0059] The locking system 50 is connected to an actuating device 80 capable of pivoting a lever member 66 of the locking system 50 to act on the feathering device. This actuating device 80 may comprise a cable, preferably in traction, attached to a pivoting element 71 mounted on the lever member 66.

[0060] The mechanical locking system 50 comprises a frame 51 which is fixed to a casing 52 of the electric motor 10. The frame 51 comprises for this purpose, for example, at least one flange 53 which comprises a through orifice 54. In the present example, there are four flanges 53. Each flange 53 comprises a median plane which is perpendicular to the longitudinal axis X and the axis of the orifices 54 extends axially. Each flange 53 is mounted on the casing 52 using fixing members 55 such as screws. The frame 51 comprises a body 56 of substantially parallelepipedal general shape. The body 56 comprises a first wall 57 and a second wall 58 which are parallel to each other and to the longitudinal axis X. The first and second walls 57, 58 are arranged at a distance from each other. Advantageously, the median planes of the first and second walls 57, 58 are perpendicular to the median plane of the flanges 53.The first and second walls 57, 58 are optionally connected on three sides by a first partition 59, a second partition 60 and a third partition 61. The first and second partitions 59, 60 are parallel to each other and each have a median plane which is perpendicular to the plane of the first and second walls 57, 58 and which is parallel to the longitudinal axis X. The third partition 61 has a median plane perpendicular to the median plane of the first and second walls 57, 58 and to the median plane of the first and second partitions 59, 60. The frame 51 has an opening 62 (visible in [Fig. 6]) which opens into the space 63 formed by the first and second walls 57, 58 and which is opposite the third partition 61. The flanges 53 are each connected to the body 56 of the frame 51 by an arm 64.

[0061] Advantageously, but not limitatively, the first wall 57 and the second wall 58 each comprise a guide groove 65 which extends along the longitudinal axis X. The guide grooves 65 are opposite one another. Each guide groove 65 passes for example through the first and second walls 57, 58 on either side in a direction perpendicular to their median plane. Each guide groove 65 opens into the space 63 formed between the first and second walls 57, 58.

[0062] According to an advantageous, but non-limiting, characteristic, the locking system 50 comprises a lever member 66 which is pivotally mounted relative to the frame 51. The lever member 66 comprises, for example, two plates 67 which are parallel to each other. Each plate 67 extends between a first end 67a and a second end 67b. Each plate 67 is pivotally mounted on one of the first and second walls 57, 58 according to a pivot connection. They are arranged at a distance from each other.

[0063] Advantageously, but not limitatively, each first wall 57 and second wall 58 comprises for example a pin 68 which extends outwards and which is received respectively in a hole 69 made in each plate 67. The plates 67 are advantageously arranged outside the first and second walls 57, 58. The plates 67 have for example a median plane which is parallel to the planes of the first and second walls 57, 58. According to the illustrated embodiment, the holes 69 are located towards the first ends 67a of the plates 67.

[0064] Each plate 67 comprises a through groove 70 forming a split cam path 74. This groove 70, also called “cam groove” or “cam through groove” herein, extends between the first and second ends 67a, 67b of the plates 67. Advantageously, but not limitingly, each cam groove 70 has a J or L shape.

[0065] The plates 67 are also, for example, connected to each other towards their second ends 67b by a pivoting roller 71 having an axis of revolution D. The axis of revolution D is here perpendicular to the longitudinal axis X and to the plates 67.

[0066] The locking system 50 comprises a slider 72 which is connected to the downstream end 16b of the control rod 16. Advantageously, but not limitingly, the downstream end 16b extends inside the chassis 51, and preferably inside the first and second walls 57, 58. The downstream end 16b optionally comprises an end piece 73 which is provided with a through hole with an axis parallel to the axis of revolution D. The control rod 16 is connected to the slider 72 via a ball joint. This ball joint is preferably arranged at the end piece 73. The end piece 73 has a median plane which is parallel to the planes of the first and second walls 57, 58. The slider 72 has a cylindrical body with an axis E and preferably a circular cross-section. The slider 72 passes through the through hole to which it is secured and extends on either side of the end piece 73.Such a configuration with the ball joint makes it possible to avoid the risks of twisting of the slide 72 given the forces applied to it. Alternatively, the slide 72 extends on either side from the end piece 73 with which it is formed from a single piece (made of material).

[0067] Advantageously, but not limitingly, the slider 72 is able to move in an axial guide path. In the present exemplary embodiment, the axial guide path is formed by the guide grooves 65. In particular, the slider 72 passes through the axial guide grooves 65 of the first and second walls 57, 58 and the through hole of the end piece 73.

[0068] The locking system 50 advantageously, but not limited to, comprises a split cam path 74 in which the slider 72 moves. In the present embodiment, the cam grooves 70 of the lever member 66 form the split cam path 74. The slider 72 passes through both the guide grooves 65 and the cam grooves 70. The split cam path 74 has a first portion 74a which extends in a first direction and a second portion 74b which extends in a second direction different from the first direction. The second direction may be perpendicular to the first direction or have an inclination. The change of direction may also be formed by a curvature.

[0069] Advantageously, the slider 72 moves between a locking position and an unlocking position. The slider 72 moves more precisely in the split cam path 74 and in the guide grooves 65 between the locking position and the unlocking position.

[0070] As stated previously, each lever member 66 is connected to the actuating device 80. More specifically, the actuating device 80 comprises at least one cable or rod which is fixed to the pivoting roller 71. In the case of a cable, the actuation of the latter in one direction or the other makes it possible to pivot the lever member 66 relative to the frame 51 and thus to change the pitch of the propeller blades. The cable may have mechanical properties making it possible to withstand tensile or compressive forces. The actuating device 80 is connected to a control member (not shown) which may be a lever or any equivalent element which can be actuated automatically or manually by an operator in the cockpit.

[0071] Alternatively, the locking systems 50 of each propulsion unit 1 are connected by a single actuating device 80.

[0072] In [Fig. 7] are illustrated rings 75 which advantageously make it possible to limit friction during the movement of the slide 72. The anti-friction rings 75 are arranged on either side of the ball joint connection (and in particular of the end piece 73) along the axis E. Advantageously, but not limitingly, at least one anti-friction ring 75 is arranged along the axis E between a plate 67 and one of the first and second walls 57, 58, and between the ball joint connection 73 and one of the first and second walls 57, 58.

[0073] The anti-friction rings 75 are for example made of a polymer material and preferably a polytetrafluoroethylene called PTFE which has good friction properties.

[0074] Alternatively, the anti-friction rings 75 are made of an elastic material of the elastomer type so as to limit mechanical shocks in the locking system.

[0075] [Fig. 8] represents the extreme working position of the blades 6 of the propeller. In this position, the blades 6 are arranged so as to allow the aircraft to move forward, i.e. the propulsion or “no flight” position. The locking system 50 is in a locked position and the slider 72 is located at a first end cam grooves 70 forming the split cam path 74. The return spring 43 located in the hub 7, which is compressed in this state, is in axial support against the control ring 15 and exerts a force which pushes the slider 72 into an area of ​​the split cam path 74 which no longer allows the latter to move, and preferably into the second portion 74b of the split cam path 74. The slider 72 is in this position in axial abutment against a portion of the wall of the cam path 74.

[0076] [Fig. 9] represents the extreme feathering position. In this position, the chord of the blades is substantially parallel to the longitudinal axis (+ / - 10%). The locking system 50 is in an unlocked position and the slider 72 is located at a second end of the cam grooves 70 forming the split cam path 74. The return spring 43, which is relaxed in this state, is still in axial support against the control ring 15.

[0077] To move from the extreme working position (propulsion position) to the extreme feathering position, the actuating device 80, here the cable, exerts a tensile force on the lever member 66 which causes it to pivot relative to the chassis 51 and which allows the slider 72 to move in the split cam path 74. The position of the lever member 66 after pivoting means that the first portion 74a of the split cam path 74 is parallel to the guide grooves 65 of the first and second walls 57, 58. The slider 72 is then free to slide downstream (toward the second end of the cam grooves and in particular at the level of the first portions 73a) and thus to allow the translation of the control rod 16 which itself is integral in translation with the control ring 15 on which the force of the return spring 43 is exerted. The translational movement of the ring control 15 acts on the position of the blades.The control rod 16 is fixed in rotation, while the control ring 15 rotates with the hub 7 of the propeller.

[0078] Figures 10 to 13 show another embodiment of a locking system 50' which is reversible, i.e. the blades 6 can be moved back into their "no flight" propulsion position to move the aircraft forward. In this example, elements that are identical or substantially identical and / or with the same functions are represented by the same reference numerals. This embodiment differs from the previous one in that the locking system 50 does not have a lever member pivoting about a fixed axis. In this example embodiment, the control rod 16 is moved so as to overcome the force of the return spring 43.

[0079] In particular, the frame 51 fixed to the casing 52 of the electric motor 10 comprises the first and second walls 57, 58 which are superimposed and at a distance from each other so as to form the internal space 63. Each first and second wall 57, 58 is provided with two guide grooves 65', 65”. A first guide groove guide 65' extends in a direction parallel to the longitudinal axis X and a second guide groove 65” extends in a direction perpendicular to the direction of the first guide groove 65' (or the longitudinal axis X). The first guide groove 65' forms the axial guide path in which a slide is able to move. Advantageously, the directions of the first and second guide grooves 65', 65” are perpendicular. The first and second guide grooves 65', 65” form the equivalent of the split cam path 74 of the previous embodiment.

[0080] The downstream end 16b of the control rod 16 is connected to a first slider 72' which slides in the first grooves 65' of the first and second walls 57, 58 (having the same configuration as that of the embodiments of FIGS. 5 to 7). The locking system 50' comprises a second slider 72” which is connected to the first slider 72' by means of a pair of connecting rods 78 (a single connecting rod 78 is shown in Figure 10-11). The second slider 72” slides in the second guide grooves 65” of the first and second walls 57, 58. Advantageously, the first and second sliders 72', 72” have parallel axes and are perpendicular to the median planes of the first and second walls 57 and 58. Each connecting rod 78 comprises, for example, a first end 78a connected to the first slider 72' and a second end 78b connected to the second slider 72”.

[0081] Advantageously, but not limitatively, the length L of the first groove 65' defines the stroke C1 of the control rod 16.

[0082] Hooking means 79 of the actuating device 80 (visible in particular in [Fig.12]) are provided on the second slide 72”. The hooking means 79 extend along an axis which is parallel to the direction of the second grooves 65”.

[0083] In Figure 10 which shows the locking system 50' in the locked position, the connecting rods 78 are inclined relative to the longitudinal axis X or the direction of the first grooves 65'. The angle of inclination a is for example between 5° and 20°. The first slider 72' is located at the first ends 65'a of the first guide grooves 65' and the second slider 72” is located at the first ends 65”a of the second guide grooves 65”.

[0084] In Figure 11, the locking system 50' is in the unlocked position. In this case, the first slider 72' is located at the second ends 65”b of the first guide grooves 65' and the second slider 72" is located at the second ends 65 ”b of the second guide grooves 65". The angle of inclination a of the pair of connecting rods 78 relative to the second grooves 65”, as shown in [Fig. 13], is preferably greater than 20° in the unlocked position. The angle of inclination a (alpha) is preferably greater than 30° so as to limit the force to be transmitted to the cable (here a tensile force according to arrow 81) to overcome the action of the return spring 43 of the control rod 16 and allow the return to the locked position (rearm the system in the pitch setting position for flight).

Claims

Claims

1. Propulsion assembly (1) for an aircraft, comprising: - a propeller (2), with a longitudinal axis (X), provided with blades (6) with a variable pitch angle, - an electric motor (10) for driving the propeller in rotation, - a control mechanism (14) for the pitch angle of the blades, located in a hub (7) of the propeller (2), movable in translation along the longitudinal axis (X), - a control rod (16) for the movement of the mechanism, which is securely connected in translation to the control mechanism (14) and which axially passes through the electric motor (10) to have a downstream end (16b) arranged on the side opposite the propeller (2) relative to the electric motor (10), - a return spring (43) located in the hub (7) of the propeller and acting on the control mechanism (14) so ​​as to force the control mechanism (14) to move towards a position of in the flag of the blades,and - a mechanical locking system (50) connected to the downstream end (16b) of the control rod (16) and configured so as to allow the control rod (16) and the control mechanism (14) to be held in a propulsion position corresponding to an angle of the blades (6) adapted to the propulsion of the aircraft.,

2. An assembly according to claim 1, characterized in that the control mechanism (14) comprises a control ring (15) centered on the longitudinal axis (X) and connected to the blades (6) of the propeller via connecting elements, the control ring (15) being driven in rotation by the hub (7) of the propeller.

3. Assembly according to one of the preceding claims, characterized in that the mechanical locking system (50) comprises a frame (51) which is fixed to a casing of the electric motor (10), a slider (72, 72') to which the downstream end (16b) of the control rod (16) is connected, and an axial guide path (65, 65') in which the slider (72, 72') is able to move.

4. Assembly according to the preceding claim, characterized in that the locking system comprises a lever member (66) which is pivotally mounted relative to the chassis (51), the chassis (51) comprises a first wall (57) and a second wall (58) which are parallel between them and relative to the longitudinal axis (X), the first and second walls (57, 58) each comprising a guide groove (65) forming said axial guide path and extending along the longitudinal axis (X), and in that the lever member (66) comprises two parallel plates (67) which are each provided with a through groove (70) forming a split cam path (74) and which are arranged outside the first and second walls (57, 58), the plates (67) being on the one hand each pivotally mounted relative to one of the first and second walls (57, 58) and are on the other hand connected to each other by a roller (71), the slide (72) passing, along a radial axis, both the guide grooves (65) and the through grooves (70).

5. Assembly according to the preceding claim, characterized in that the downstream end (16b) of the control rod (16) is connected by a ball joint to a slide (72) extending along an axis, anti-friction rings (75) centered on the axis being arranged on the one hand, between one of the first and second walls (57, 58) and the ball joint (73) and on the other hand, between each plate (67) and one of the first and second walls (57, 58).

6. Assembly according to one of claims 4 and 5, characterized in that the lever member (66) is connected to an actuating device (80) acting on it so as to cause it to pivot.

7. Assembly according to one of claims 1 to 3, characterized in that the mechanical locking system (70) is reversible and is configured so as to allow the passage of the control rod (16) and the control mechanism (14) from the feathering position to the propulsion position of the blades (6) of the propeller (2).

8. Assembly according to the preceding claim taken in dependence on claim 3, characterized in that the frame (51) comprises a first wall (57) and a second wall (58) which are parallel to each other and with respect to the longitudinal axis (X), the first and second walls (57, 58) each comprising a first guide groove (65') extending along the longitudinal axis (X) and forming said axial guide path, as well as a second guide groove (65”) which extends in a direction perpendicular to the longitudinal axis (X), the assembly further comprising the first slide (72') to which the downstream end of the control rod (16) is connected and which passes, along a radial axis, the first guide grooves (65'), and a second slider (72”) passing through the second guide grooves (65”), the first and second sliders being connected to each other by a pair of connecting rods (78).

9. Assembly according to one of claims 2 to 8, characterized in that the return spring (43) is mounted integral in rotation with the control ring (15), the control rod (16) comprising an upstream part (17) passing through the control ring (15) and which rotates relative to the upstream part (17) via rolling bearings (19a, 19b).

10. Assembly according to the preceding claim, characterized in that the rolling bearings (19a, 19b) comprise an upstream bearing (19a) with radial rolling and a downstream bearing (19b) with axial rolling, the upstream bearing (19a) comprising an inner ring (20a) secured to the upstream part (17) of the control rod (16) and an outer ring (20b) secured to the control ring (15), the downstream bearing (19b) comprising an upstream ring (23a) secured to the control ring (15) and a downstream ring (23a) secured to the upstream part (17) of the control rod (16).

11. Aircraft wing (4) comprising at least one propulsion unit (1) according to any one of the preceding claims.

12. Aircraft comprising an aircraft wing (4) according to the preceding claim or a propulsion unit (1) according to one of claims 1 to 10.

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