DRIVE DEVICE FOR AT LEAST ONE WHEEL OF AN AIRCRAFT LANDING GEAR

Abstract

Device (10) for driving at least one wheel (12) of an aircraft landing gear (14), this device (10) comprising: - at least one landing gear wheel (12), - an electric motor (20) comprising a shaft (30), - a mechanical transmission system (22) between the motor shaft (20) and the rim (16), this mechanical transmission system (22) comprising a mechanical reducer (28) which comprises: - satellites (34) with a double meshing stage which comprise a first toothing (34a) and a second toothing (54a), - a fixed sun gear (32) which is meshed with one of the first and second toothings (34a, 54a), - a movable sun gear (56) which is meshed with the other of the first and second toothings (54a, 34a), and - a movable crown wheel (38) which is meshed with either of the first and second teeth (34a, 54a). Figure for abstract: Figure 6

Description

Title of the invention: DEVICE DRIVE OF AT LEAST ONE WHEEL OF AN AIRCRAFT LANDING GEAR Technical field of the invention

[0001] The present invention relates to a device for driving at least one wheel of an aircraft landing gear. Technical background

[0002] An aircraft includes landing gear equipped with wheels for moving the aircraft on the ground on a tarmac. This rolling, also called taxiing, can be achieved by propelling the aircraft using its turbomachines.

[0003] To limit fuel consumption and the impact on the environment, it is known to carry out this taxiing electrically. Electric taxiing is obtained by driving the wheels of a landing gear by an electric motor.

[0004] The present application proposes an improvement to existing technologies and thus relates to an electric motor device for driving at least one wheel of an aircraft landing gear.

[0005] A solution consisting of using a reducer to transmit the power of an electric motor to a wheel of a landing gear has been proposed by the Applicant in document EP-A1-3 882 136.

[0006] The role of a mechanical reducer is to modify the speed and torque ratio between the input axis and the output axis of a mechanical system.

[0007] In the distant field of aircraft turbomachines, it is known to use a mechanical reducer to ensure power transmission between two rotating mechanical shafts.

[0008] There are many types of reducers, for example differential, planetary, epicyclic, intermediate line, series reduction stages, etc.

[0009] In the state of the art of dual-flow turbomachines, the reducers are of the planetary or epicyclic type. Such a reducer comprises a central pinion, called a sun gear, a crown gear and pinions called satellites, which are meshed between the sun gear and the crown gear. The satellites are held by a frame called a planet carrier. The sun gear, the crown gear and the planet carrier are planetary gears because their axes of revolution coincide with the longitudinal axis of the turbomachine. The satellites each have a different axis of revolution equally distributed over the same operating diameter around the axis of the planetary gears. These axes are parallel to the longitudinal axis of the turbomachine.

[0010] There are several reducer architectures. In other similar applications, there are so-called differential or "compound" architectures.

[0011] - On a planetary reducer, the planet carrier is fixed and the crown constitutes the output shaft of the device which rotates in the opposite direction of the solar.

[0012] - On an epicyclic reducer, the crown is fixed and the planet carrier constitutes the output shaft of the device which rotates in the same direction as the solar.

[0013] - On a differential reducer, no element is fixed in rotation. The crown rotates in the opposite direction of the solar and the satellite carrier.

[0014] The reducers can be composed of one or more meshing stages. This meshing is ensured in different ways such as by contact, by friction or even by magnetic fields.

[0015] In the present application, the term "stage" or "teeth" means at least one series of meshing teeth with at least one series of complementary teeth. A toothing can be internal or external.

[0016] A satellite can comprise one or two meshing stages. A single-stage satellite comprises a toothing which can be straight, helical or herringbone and whose teeth are located on the same diameter. This toothing cooperates with both the sun gear and the crown.

[0017] A double-stage satellite comprises two sets of teeth which are located on different diameters. A first set of teeth cooperates with the sun gear and a second set of teeth generally cooperates with the crown.

[0018] A double-stage gear reducer has the advantage of having a higher reduction ratio than a single-stage gear reducer of the same size.

[0019] In the context of a device for driving at least one wheel of a landing gear, the use of an electric motor and a reduction gear for driving the wheel generates significant space constraints. The outer diameter of the reduction gear is limited by the dimension of the wheel rim, and the inner diameter of the reduction gear is strongly constrained by the diameter of the wheel hub. In addition, the use of an electric motor generally rotating at high speeds requires the use of a reduction gear offering a large reduction ratio in order to provide an output speed which corresponds to the low rotational speed of the wheel. The epicyclic and planetary type gears of current technology do not allow these levels of reduction to be obtained in such a restricted space.

[0020] The invention provides a solution to at least some of these problems, which is simple, effective and economical. Summary of the invention

[0021] The invention relates to a device for driving at least one wheel of an aircraft landing gear, this device comprising:

[0022] - at least one landing gear wheel, this wheel comprising a rim having a axis of rotation,

[0023] - an electric motor comprising a shaft,

[0024] - a mechanical transmission system between the motor shaft and the rim, this mechanical transmission system comprising a mechanical reducer,

[0025] characterized in that the mechanical reducer comprises:

[0026] - double-stage meshing satellites which are distributed around the axis and which are carried by a mobile planet carrier rotating around the axis, each of these satellites comprising a first toothing and a second toothing,

[0027] - a fixed sun which is centered on the axis and which includes external teeth meshed with one of the first and second teeth, this fixed solar being configured to be fixed to at least one stator of the device,

[0028] - a mobile sun which is centered on the axis and which includes external teeth meshed with the other of the first and second teeth, this sun gear being driven in rotation around the axis by the motor shaft, and

[0029] - a movable crown which is centered on the axis and which has internal teeth meshed with one or other of the first and second teeth, this crown being integral in rotation with the rim around the axis.

[0030] The invention thus proposes a device for driving at least one wheel of an aircraft landing gear, which is equipped with an independent double sun gear reducer. One of the sun gears is fixed and the other of the sun gears is mobile in rotation. It is therefore understood that the mobile sun gear forms an input (of torque) of the reducer, the output of the reducer being formed by the ring which is also mobile. The planet carrier is also mobile in rotation. It can be free in rotation and therefore independent of any rotor of the electric motor.

[0031] The invention is compatible with a multi-stage reducer as mentioned above. It is also compatible with a reducer whose planet carrier is rotatable such as epicyclic or differential reducers. It is also compatible with teeth of any type (straight, helical, chevron, etc.). The invention is furthermore compatible with a planet carrier of the monobloc type or of the cage and cage carrier type. These different types of reducer are well known to those skilled in the art. The solution proposed below is compatible with any type of satellite bearing, whether it is composed of rolling elements, a hydrodynamic bearing, etc.

[0032] The device according to the invention may comprise one or more of the following characteristics, taken in isolation from one another, or in combination with one another: • the teeth of the mobile sun and the mobile crown are meshed with the same teeth of each of the satellites; • the satellites are of the double-stage symmetrical meshing type, the first toothing being crossed by a median plane and being located between two series of teeth of the second toothing, the median plane being perpendicular to said axis and being a plane of symmetry of the first toothing and the series of teeth of the second toothing; • the teeth of the mobile solar unit are meshed with the first teeth of each of the satellites; • the teeth of the fixed sun gear are meshed with the series of teeth of the second teeth of each of the satellites; • the fixed solar comprises a first part comprising a series of teeth meshed with one of the series of teeth of the second toothing of each of the satellites, and a second part comprising a series of teeth meshed with the other of the series of teeth of the second toothing of each of the satellites; • the first part is connected to a stator of the electric motor, and the second part is connected to another stator of the device; • each of the first and second parts comprises an annular fixing flange; • the teeth of the moving crown are meshed with the first teeth of each of the satellites; • the teeth of the movable crown are meshed with the series of teeth of the second teeth of each of the satellites; • the first set of teeth comprises two series of teeth symmetrical with respect to the median plane. Brief description of the figures

[0033] Other characteristics and advantages will emerge from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which:

[0034] [Fig-1] [Fig.l] is a schematic perspective view of a wheel of a train aircraft landing gear and a device for driving this wheel,

[0035] [Fig.2] [Fig.2] is a partial axial sectional view of a mechanical reducer,

[0036] [Fig.3] [Fig.3] is another partial axial sectional view of a reducer mechanical,

[0037] [Fig.4] [Fig.4] is a schematic view in axial section and in perspective of a double-stage symmetrical gear reducer,

[0038] [Fig.5] [Fig.5] is another schematic view in axial section of the reducer of the [Fig.4] ;

[0039] [Fig.6] [Fig.6] is a very schematic axial sectional view of a device training according to one embodiment of the invention,

[0040] [Fig.7] [Fig.7] is a schematic perspective and axial section view of a device according to the embodiment of [Fig.6];

[0041] [Fig.8] [Fig.8] is a view similar to that of [Fig.6] and illustrates a variant of implementation of the device;

[0042] [Fig.9] [Fig.9] is a view similar to that of [Fig.6] and illustrates another variant embodiment of the device;

[0043] [Fig. 10] [Fig. 10] is a view similar to that of [Fig.6] and illustrates another variant embodiment of the device. Detailed description of the invention

[0044] [Fig.l] shows a device 10 for driving at least one wheel 12 of an aircraft landing gear 14.

[0045] The wheel 12 comprises a rim 16 which has an axis of rotation X. Conventionally, this rim 16 has a generally tubular or disc shape and carries a tire 18 at its periphery.

[0046] The device 10 comprises an electric motor 20 and a mechanical transmission system 22 between a shaft of the motor 20 and the rim 16 of the wheel 12.

[0047] In the example shown, the motor 20 and the system 22 each have a generally annular shape and are centered on the axis X. They are arranged next to each other and the system 22 is installed between the motor 20 and the rim 16. A part of the system 22, or even also a part of the motor 20, could be housed in the rim 16 to optimize the size of the device 10. The motor 20 and the system 22 can be protected by an external cylindrical cover 26 projecting on one side of the rim 16 or the tire 18.

[0048] The mechanical transmission system 22 comprises a mechanical reducer 28, examples of embodiment of which are illustrated in FIGS. 2 to 5.

[0049] [Fig.2] shows an epicyclic reducer 28. At the input, the reducer 28 is connected to a shaft 30, for example via internal splines 32b. Thus, the shaft 30 drives a planetary pinion called the sun gear 32. Conventionally, the sun gear 32 drives a series of pinions called satellites 34, which are equally distributed over the same diameter around the axis X of rotation of the sun gear 32. This diameter is equal to twice of the operating center distance between the solar 32 and the satellites 34. The number of satellites 34 is generally defined between three and seven.

[0050] The set of satellites 34 is held by a frame called a satellite carrier 36. Each satellite 34 rotates around its own Y axis, and meshes with a crown 38.

[0051] At the output we have: • In this epicyclic configuration, the set of satellites 34 drives the planet carrier 36 in rotation around the X axis. The crown 38 is fixed to a stator via a crown carrier 40 and the planet carrier 36 is fixed to another shaft 42. • In another planetary configuration, all of the planet gears 34 are held by a planet carrier 36 which is fixed to a stator. Each planet gear drives the crown 38 which is connected to the shaft 42 via a crown carrier 40. • In another differential configuration, all of the satellites 34 are held by a planet carrier 36 which is connected to the shaft 30. Each satellite 34 drives the crown 38 which is attached to the shaft 42 via a crown carrier 40.

[0052] Each satellite 34 is mounted to rotate freely using a bearing 44, for example of the rolling bearing or hydrodynamic bearing type. Each bearing 44 is mounted on one of the axes 36b of the planet carrier 36 and all the axes 36b are positioned relative to each other using one or more structural frames 36a of the planet carrier 36. There is a number of axes 36b and bearings 44 equal to the number of satellites 34. For reasons of operation, assembly, manufacturing, control, repair or replacement, the axes 36b and the frame 36a can be separated into several parts.

[0053] For the same reasons cited above, the toothing 34a of a satellite 34 can be separated into several helices or teeth each having a median plane P, P'. In the example shown, each satellite 34 comprises two series of chevron teeth cooperating with a crown 38 separated into two half-crowns: • An upstream ring 38a consisting of a rim 38aa and a fixing half-flange 38ab. On the rim 38aa is the front propeller meshed with a propeller of the toothing 34a of each satellite 34. The propeller of the toothing 34a also meshes with that of the sun 32. • A downstream ring 38b consisting of a rim 38ba and a half-fixing flange 38bb. On the rim 38ba is the rear propeller meshing with a propeller of the toothing 34a of each satellite 34. The propeller of the toothing 34a also meshes with that of the sun 32.

[0054] If the helix widths vary between the sun gear 32, the satellites 34 and the crown 38 because of the tooth overlaps, they are all centered on a median plane P for the upstream teeth and on another median plane P' for the downstream teeth.

[0055] [Fig.2] thus illustrates the case of a single-stage gear reducer, i.e. the same toothing 34a of each satellite 34 cooperates with both the sun gear 32 and the crown wheel 38. Even if the toothing 34a comprises two series of teeth, these teeth have the same average diameter and form a single toothing called a chevron.

[0056] The fixing half-flange 38ab of the upstream ring 38a and the fixing half-flange 38bb of the downstream ring 38b form the fixing flange 38c of the crown. The crown 38 is fixed to the crown carrier 40 by assembling the fixing flange 38c of the crown 38 and a fixing flange 40a of the crown carrier 40 using a bolted assembly for example.

[0057] [Fig. 3] shows another example of a reduction gear architecture, called a double meshing stage, in which each satellite 34 comprises two separate sets of teeth 34al, 34a2 configured to cooperate respectively with the crown 38 and the sun gear 32.

[0058] In this [Fig.3], the elements already described in the above are designated by the same references.

[0059] The toothing 34al for meshing with the crown 38 has an average diameter denoted D2 and is located in a median plane P. The toothing 34a2 for meshing with the sun 32 has an average diameter denoted DI and is located in another median plane P'. The median planes P, P' are parallel to each other and perpendicular to the axis X. The diameter D2 is less than the diameter DI. Finally, each toothing 34al, 34a2 here comprises a single helix.

[0060] Figures 4 and 5 show a reducer 28 with double symmetrical teeth, which comprises:

[0061] - a solar 32 having an axis of rotation X,

[0062] - a crown 38 which extends around the solar 32 and which is configured to be stationary in rotation around the X axis, and

[0063] - satellites 34 which are meshed with the sun 32 and the crown 38 and which are held by a planet carrier 36 which is configured to be rotatable about the X axis.

[0064] The plane H is defined as being a median plane perpendicular to the axis X and passing substantially through the middle of the reducer 28 ([Fig.5]).

[0065] The sun gear 32 comprises internal splines 32b for coupling with the shaft 30 as well as external teeth 32a for meshing with the planet gears 34. The teeth 32a have two series of adjacent teeth in a chevron pattern, separated from each other by an annular groove 46 oriented radially outwards. The teeth 32a are symmetrical with respect to plane H, its teeth being located on either side of plane H which passes through groove 46.

[0066] The crown 38 is formed by two independent rings 38a, 38b and comprises a toothing which is separated into two series of teeth 38dl, 38d2 in a chevron pattern carried respectively by the two rings.

[0067] The rings 38a, 38b are arranged symmetrically with respect to the plane H which therefore extends between these rings. The rings 38a, 38b are connected and fixed to a crown carrier 40 by means of annular connecting flanges 48. The flanges 48 are independent of one another, each flange having in axial half-section a general S-shape providing it with a certain radial flexibility by elastic deformation in operation.

[0068] Each ring 38a, 38b extends around the axis X and is fixed to the corresponding flange 48 by its external periphery. Its internal periphery comprises one of the teeth 38dl, 38d2.

[0069] The crown carrier 40 has a generally annular shape around the axis X and more particularly biconical. It thus comprises a first upstream section or on the left in the drawing, with an upstream end of smaller diameter, and a downstream end of larger diameter which is connected to the upstream end of larger diameter of the other section, downstream or on the right in the drawing. The larger diameter ends of the sections are therefore connected to each other, and their smaller diameter ends form the axial ends of the crown carrier 40.

[0070] The upstream end of the crown carrier 40 extends around the planet carrier 36 or a shaft 42 connected to this planet carrier, and is centered and guided in rotation on the planet carrier or the shaft by means of at least one bearing 50. In the same way, the downstream end of the crown carrier 40 extends around the planet carrier 36 or a shaft connected to this planet carrier s, and is centered and guided in rotation on the planet carrier or the shaft by means of at least one other bearing 52.

[0071] As is the case with the crown 38, the crown carrier 40 has a symmetry with respect to the plane H which cuts the crown carrier 40 in its middle and therefore passes through the ends of larger diameter of the aforementioned sections.

[0072] Each satellite 34 comprises a first toothing 34a of average diameter DI for meshing with the sun gear 32, and a second toothing 54aa of average diameter D2, different from DI and in particular less than D1, for meshing with the crown 38. The average diameters are measured from the Y axis of each satellite 34 and represent the average between the maximum diameter and the minimum diameter of a toothing of this satellite.

[0073] Each satellite 34 comprises a cylindrical sleeve 58 and an annular web 60 extending substantially radially outwards from the middle of this sleeve. 58. The toothing 54aa is separated into two series of chevron teeth 54al, 54a2 which are located respectively on the axial ends of the sleeve 58. The toothing 34a comprises two series of chevron teeth 34al, 34a2 which are located at the external periphery of the web 60 and which are separated from each other by an annular groove 55 opening radially outwards relative to the axis Y.

[0074] The teeth 34a are crossed in their middle by the plane H which passes through the groove 55, the teeth 34al, 34a2 therefore being arranged on either side of the plane H. The teeth 54al, 54a2 are also arranged symmetrically with respect to the plane H.

[0075] The toothing 34a and the external periphery of the web 60 have an axial dimension which is less than the axial distance between the rings 38a, 38b, as well as between the flanges 48, so that each satellite 34 can freely rotate in the crown carrier 40 and between the rings 38a, 38b and the flanges 48.

[0076] Each of the satellites 34 is guided in rotation by a hydrodynamic bearing 44 which comprises a cylindrical body 44a which passes through the satellite 34, and in particular its sleeve 58, and which is configured to form a film of guide oil inside the satellite.

[0077] The body 44a of a bearing 44 extends along the Y axis and comprises at its longitudinal ends extensions 44b housed in orifices forming seats of the planet carrier 36.

[0078] The body 44a is generally tubular and comprises an internal oil circulation bore which generally communicates with oil supply conduits to an external cylindrical surface of the body for the purpose of forming the oil film between this surface and an internal cylindrical surface of the satellite 34.

[0079] The present invention proposes, in a reduced size, to increase the reduction ratio of a mechanical reducer within the framework of a device 10 for driving at least one wheel of an aircraft landing gear, as illustrated in [Fig.l].

[0080] The reducer 28 of the device 10 according to the invention comprises all of the characteristics described above in relation to figures 3, 4 and 5 insofar as they are not contrary to or do not contradict what follows.

[0081] The references used in figures 6 and following and already used in figures 3, 4 and 5 therefore designate identical or similar elements.

[0082] Figures 6 to 10 illustrate embodiments of a reducer 28 according to the invention, which comprises:

[0083] - double-stage meshing satellites 34 which are distributed around the X axis and which are carried by a stellite carrier 36 movable in rotation around the axis X, each of these satellites 34 comprising a first toothing 34a and a second toothing 54a,

[0084] - a fixed solar 32 which is centered on the X axis and which includes external teeth 32a meshed with one of the first and second teeth 34a, 54a, this solar 32 being configured to be fixed to at least one stator of the device 10,

[0085] - a mobile solar 56 which is centered on the X axis and which includes external teeth 56a meshed with the other of the first and second teeth 34a, 54a, this sun 56 being movable in rotation around the axis X, and

[0086] - a movable crown 38 which is centered on the X axis and which has a toothing internal 38d meshed with one or other of the first and second teeth 34a, 54a, this crown 38 being movable in rotation around the axis X.

[0087] In the context of the present invention, the solar 56 is coupled with the shaft 30 of the electric motor 20. The crown 38 is coupled to the shaft 42 of the rim or to the rim 16 directly.

[0088] In the example shown, each of the satellites 34 is meshed with the sun gears 32, 56 and the crown 38 and comprises a first external toothing 34a of average diameter D1, and a second external toothing 54a of average diameter D2, different from D1. In the example shown, D1 is greater than D2. Alternatively, the teeth 34a and 54a could have equal diameters D1 and D2 and different numbers of teeth, so as to have different modules.

[0089] Reference 44a designates the cylindrical body of the hydrodynamic guide bearing of each satellite 34, as mentioned above.

[0090] The stellite carrier 36 can be supported by any bearing with the sun 56 or the crown 38. It can also be completely free without support and simply balanced by the satellites 34.

[0091] In the embodiment of figures 6 and 7, the toothing 34a of diameter Dl of each satellite 34 is meshed with the toothing 56a of the sun gear 56 and the toothing 38d of the movable crown 38. The toothings 56a, 34a and 38d are thus in the same plane PI perpendicular to the axis X.

[0092] The toothing 54a of diameter D2 of each satellite 34 is meshed with the sun 32.

[0093] In the example shown, the satellites 34 are of the double-stage type. of symmetrical meshing, as in Figures 4 and 5, that is to say that the first toothing 34a is crossed by a median plane H and is located between two series of teeth 54a 1, 54a2 of the second toothing 54a. The median plane H is perpendicular to the axis X and is a plane of symmetry of the first toothing 34a and of the series of teeth 54al, 54a2 of the second toothing 54a.

[0094] The first toothing 34a may further comprise two series of teeth symmetrical with respect to the median plane H, as described previously with reference to FIGS. 4 and 5.

[0095] In the example shown, the fixed sun gear 32 comprises a first part 58 comprising a series of teeth 32al meshed with one of the series of teeth 54a2 of the second toothing 54 of each of the satellites 34, and a second part 60 comprising a series of teeth 32a2 meshed with the other of the series of teeth 54al of the second toothing 54a of each of the satellites 34.

[0096] The first part 58 can be connected to a stator of the electric motor 20.

[0097] The second part 60 can be connected to another stator of the device 10.

[0098] Each of the first and second parts 58, 60 may comprise an annular fixing flange 58a, 60a visible in [Fig.7].

[0099] In the embodiment of [Fig.8], the satellites 34 are of the double meshing stage type but not symmetrical, as in [Fig.3].

[0100] The toothing 34a of diameter DI of each satellite 34 is meshed with the toothing 38d of the crown 38.

[0101] The toothing 54a of diameter D2 of each satellite 34 is meshed with the toothing 32a of the fixed sun gear 32.

[0102] The toothing 34a of diameter DI of each satellite 34 is meshed with the toothing 56a of the mobile sun 56.

[0103] The teeth 34a, 56a and 38d are therefore located in the same plane PI perpendicular to the axis X.

[0104] The solar 32 can be connected to a stator of the electric motor 20.

[0105] The variant embodiment of [Fig.9] differs from the embodiment of figures 6 and 7 essentially in that the toothing 38d of the crown 38 comprises two series of teeth 38dl, 38d2 which are respectively meshed with the series of teeth 54a2, 54a1 of the sun 32, and in particular of the two parts 60, 58 of this sun 32.

[0106] The series of teeth 54al of each of the satellites 34, as well as the series of teeth 32a2 and 38dl, are located in a plane PI perpendicular to the axis X.

[0107] The series of teeth 54a2 of each of the satellites 34, as well as the series of teeth 32al and 38d2, are located in a plane P2 perpendicular to the axis X.

[0108] The toothing 34a of diameter DI of each satellite 34 is meshed with the toothing 56a of the sun 56, and these toothings 34a, 56a are located in the median plane of symmetry H.

[0109] The embodiment variant of [Fig. 10] differs from the embodiment of [Fig. 8] essentially in that the toothing 38d of the crown 38 is meshed with the toothing 54a of diameter D2 of each satellite 34. The toothing 32a of the fixed sun 32 is also meshed with the toothing 54a of each satellite 34. These toothings 38d and 32a are located in a plane PI perpendicular to the axis X.

[0110] The toothing 34a of diameter DI of each satellite 34 is meshed with the toothing 56a of the mobile sun 56.

[0111] This invention makes it possible to obtain a high reduction ratio in a small footprint compared to other more conventional architectures (epicyclic or planetary gear train).

[0112] In addition, making the satellites symmetrical makes it possible to eliminate the tilting moments in the reducer. This therefore makes it possible to: - reduce the forces to be taken up by the satellite bearings (compared to a non-symmetrical architecture), - reduce the size of the satellite bearings (compared to a non-symmetrical architecture), - increase efficiency (compared to a non-symmetrical architecture), - reduce the size (compared to an epicyclic or planetary gear), and - reduce the mass (compared to an epicyclic or planetary gear train).

Claims

Claims

1. Device (10) for driving at least one wheel (12) of an aircraft landing gear (14), this device (10) comprising: - at least one landing gear wheel (12), this wheel (12) comprising a rim (16) having an axis of rotation (X), - an electric motor (20) comprising a shaft (30), - a mechanical transmission system (22) between the motor shaft (20) and the rim (16), this mechanical transmission system (22) comprising a mechanical reducer (28), characterized in that the mechanical reducer (28) comprises: - satellites (34) with a double meshing stage which are distributed around the axis (X) and which are carried by a planet carrier (36) movable in rotation around the axis (X), each of these satellites (34) comprising a first toothing (34a) and a second toothing (54a), - a fixed sun gear (32) which is centered on the axis (X) and which comprises an external toothing (32a) meshed with one of the first and second toothings (34a, 54a),this fixed solar (32) being configured to be fixed to at least one stator of the device (10), - a mobile solar (56) which is centered on the axis (X) and which comprises an external toothing (56a) meshed with the other of the first and second toothings (54a, 34a), this solar (56) being driven in rotation about the axis (X) by the shaft (30) of the motor (20), and - a mobile crown (38) which is centered on the axis (X) and which comprises an internal toothing (38d) meshed with one or the other of the first and second toothings (34a, 54a), this crown (38) being integral in rotation with the rim (16) about the axis (X).,

2. Device (10) according to claim 1, in which the teeth (56a, 38d) of the mobile sun gear (56) and of the mobile crown (38) are meshed with the same teeth (34a) of each of the satellites (34).

3. Device (10) according to one of the preceding claims, in which the satellites (34) are of the double-stage symmetrical meshing type, the first toothing (34a) being crossed by a median plane (H) and being located between two series of teeth (54al, 54a2) of the second toothing (54a), the median plane (H) being perpendicular to said axis (X) and being a plane of symmetry of the first toothing (34a) and of the series of teeth (54al, 54a2) of the second toothing (54).

4. Device (10) according to claim 3, in which the toothing (56a) of the mobile sun (56) is meshed with the first toothing (34a) of each of the satellites (34).

5. Device (10) according to claim 3 or 4, in which the toothing (32a) of the fixed sun gear (32) is meshed with the series of teeth (54al, 54a2) of the second toothing (54a) of each of the satellites (34).

6. Device (10) according to claim 5, wherein the fixed sun (32) comprises a first part (58) comprising a series of teeth (32al) meshed with one of the series of teeth (54a2) of the second toothing (54a) of each of the satellites (34), and a second part (60) comprising a series of teeth (32a2) meshed with the other of the series of teeth (54al) of the second toothing (54a) of each of the satellites (34).

7. Device (10) according to claim 6, wherein the first part (58) is connected to a stator of the electric motor (20), and the second part (60) is connected to another stator of the device (10).

8. A device (10) according to claim 6 or 7, wherein each of the first and second portions (58, 60) comprises an annular fixing flange (58a, 60a).

9. Device (10) according to one of claims 3 to 7, in which the toothing (38d) of the movable crown (38) is meshed with the first toothing (34a) of each of the satellites (34).

10. Device (10) according to one of claims 3 to 7, in which the toothing (38d) of the movable crown (38) is meshed with the series of teeth (54al, 54a2) of the second toothing (54) of each of the satellites (34).

11. Device (10) according to one of claims 3 to 10, in which the first toothing (34a) comprises two series of teeth symmetrical with respect to the median plane (H).

Images