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

Abstract

A 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) having a rim (16) having an axis of rotation (X), - an electric motor (20) having 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 reduction gear (28) which includes: - a movable ring gear (38) fixed for rotation to the motor shaft (20), - a movable sun gear (32) fixed for rotation to the rim (16), - a fixed sun gear (56) attached to a stator of the device (10), and - planet gears (34) which are meshed with the ring gear and the sun gears. Figure for the abbreviation: Figure 7

Description

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

[0001] The present invention relates to a drive device for 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 taxiing, also called taxiing, can be achieved by propelling the aircraft using its turbomachinery.

[0003] To limit fuel consumption and environmental impact, it is known to perform this taxiing electrically. Electric taxiing is achieved by driving the wheels of a landing gear with 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 was 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 shaft and the output shaft of a mechanical system.

[0007] In the distant field of aircraft turbomachinery, 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, epi-cycloidal, intermediate line, series reduction stage, etc.

[0009] In the state of the art of turbofan engines, gearboxes are of the planetary or epicyclic type. Such a gearbox comprises a central pinion, called the sun gear, a ring gear, and gears called planet gears, which mesh between the sun gear and the ring gear. The planet gears are held by a frame called the planet carrier. The sun gear, ring gear, and planet carrier are planetary because their axes of revolution coincide with the longitudinal axis of the turbomachine. The planet gears each have a different axis of revolution, equally spaced on the same operating diameter around the axis of the planet gears. These axes are parallel to the longitudinal axis of the turbomachine.

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

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

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

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

[0014] Reducers can be composed of one or more meshing stages. This meshing is achieved in various ways such as by contact, by friction or by magnetic fields.

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

[0016] A satellite may comprise one or two gear stages. A single-stage satellite comprises teeth that may be straight, helical, or chevron-shaped, and whose teeth are located on the same diameter. These teeth cooperate with both the sun gear and the crown gear.

[0017] A two-stage satellite comprises two sets of teeth 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 gear.

[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 drive system for at least one landing gear wheel, the use of an electric motor and a gearbox to drive the wheel generates significant space constraints. The gearbox's outer diameter is limited by the wheel rim size, and its inner diameter is severely constrained by the wheel hub diameter. Furthermore, the use of an electric motor, which typically rotates at high speeds, necessitates a gearbox with a high reduction ratio to provide an output speed that matches the low rotational speed of the wheel. Epicyclic and planetary gear sets of current technology cannot achieve these levels of reduction within such a compact footprint.

[0020] The invention proposes 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 drive device for 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 engine shaft and the rim, this mechanical transmission system including a mechanical reducer,

[0025] characterized in that the mechanical reducer comprises:

[0026] - a movable crown centered on the axis and having internal teeth, this the rotating crown being fixed to the motor shaft,

[0027] - a movable solar element centered on the axis and having external teeth, this solar element the mobile being fixed in rotation to the rim,

[0028] - a fixed solar element centered on the axis and having external teeth, this fixed solar element being configured to be attached to a stator of the device, and

[0029] - satellites which are meshed with the corona and the solar system, the satellites being carried by a mobile satellite carrier rotating around the axis, each of the satellites having two external teeth meshed respectively with the teeth of the fixed and mobile sun gears, one of these external teeth being further meshed with the teeth of the crown.

[0030] The invention thus proposes a drive device for at least one wheel of an aircraft landing gear, which is equipped with a dual-seal gearbox with independent and different functions. One of the solar elements is fixed and the other is rotatable. The rotatable solar element forms a torque output of the gearbox, the input of the gearbox being formed by the ring gear. The planet carrier is also rotatable. It can rotate freely and therefore be independent of any rotor of the electric motor.

[0031] The invention is compatible with a multi-stage gearbox as mentioned above. It is also compatible with gears of any type (straight, helical, herringbone, etc.). Furthermore, the invention is compatible with a planet carrier of the one-piece type or of the cage and cage type. These different types of gearboxes are well known to those skilled in the art. The solution proposed below is compatible with any type of planet carrier, whether composed of rolling elements, a hydrodynamic bearing, etc.

[0032] The proposed solution is therefore similar to a device equipped with a "reverse" Wolfrom type mechanical reducer, this reducer having two solar elements, respectively fixed and mobile, instead of two rings, respectively fixed and mobile, in a classic Wolfrom type reducer.

[0033] The device according to the invention may comprise one or more of the following features

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040] the following, taken individually or in combination with each other: • the teeth of the fixed and moving solar elements have the same diameter; • the teeth of the fixed and moving solar elements have different diameters; • the teeth of the fixed and moving solar elements have different numbers of teeth; • The teeth of the crown and the teeth of the moving sun gear are meshed with the same toothing on each of the satellites; • the teeth of the crown and the teeth of the fixed solar element are meshed with the same teeth of each of the satellites; • the crown is meshed with one of the teeth of each of the satellites and extends around the other tooth of each of the satellites; • all the teeth are chosen from straight, helical or herringbone teeth; • the motor has an annular shape centered on the axis and is arranged axially between the wheel and the reducer; • the motor extends at least partially around the mobile solar panel; • The teeth of each of the satellites have different diameters, the teeth of smaller diameter of each of the satellites meshing with the teeth of the fixed solar, and the teeth of larger diameter of each of the satellites meshing with the teeth of the mobile solar; • the electric motor is positioned on the side of the crown and on the opposite side to the fixed solar panel; — the teeth of each of the satellites have identical diameters and different numbers of teeth; — the teeth of each of the satellites have different diameters, the teeth of the smallest diameter of each of the satellites meshing with the teeth of the mobile solar, and the teeth of the largest diameter of each of the satellites meshing with the teeth of the fixed solar; — the electric motor is positioned on the side of the fixed solar panel; - the mobile solar element is centered and guided by two bearings, the first bearing of which is located at the right of the teeth of the solar element, and the second bearing is axially offset from these teeth; - the second bearing is located to the right of the said motor, and radially inside it; - the motor shaft is centered and guided by two bearings which are arranged radially inside a rotor of said motor; - the second bearing is arranged radially inside the motor shaft guide bearings, and is located axially between these bearings;

[0041] each of the satellites is centered and guided by two bearings which are located respectively at the right of the teeth of this satellite;

[0042] — the satellites are each centered and guided by two roller bearings carried by the satellite carriers, the teeth of each of the satellites being located between these roller bearings;

[0043] — the satellites are each centered and guided by two needle bearings carried by the satellite carrier, each of the needle bearings being radially aligned with one of the satellite's teeth. Brief description of the figures

[0044] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:

[0045] [Fig-1] [Fig.1] is a schematic perspective view of a train wheel aircraft landing gear and a drive device for this wheel,

[0046] [Fig.2] [Fig.2] is a partial axial cross-sectional view of a mechanical reducer,

[0047] [Fig.3] [Fig.3] is a very schematic partial axial cross-sectional view of a reducer for a device according to an embodiment of the invention,

[0048] [Fig.4] [Fig.4] is viewed similarly to [Fig.3] and illustrates a variant of the realization implementation of the system;

[0049] [Fig. 5] [Fig. 5] is a view similar to that of [Fig. 3] and illustrates another alternative implementation of the device;

[0050] [Fig.6] [Fig.6] is a schematic axial cross-sectional view of a wheel of a train aircraft landing gear and a drive device for this wheel according to one embodiment of the invention,

[0051] [Fig.7] [Fig.7] is a larger-scale view of part of [Fig.6], and

[0052] [Fig.8] [Fig.8] is a schematic perspective view of the reducer of the device training of the [Fig.6]. Detailed description of the invention

[0053] Fig. 1 shows a drive device 10 for at least one wheel 12 of an aircraft landing gear 14.

[0054] The wheel 12 has a rim 16 which has an axis of rotation X. In a conventional manner, this rim 16 has a general tubular or disc shape and carries a tire 18 on its periphery.

[0055] The device 10 includes 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.

[0056] In the example shown, the motor 20 and the system 22 each have a generally annular shape and are centered on the X-axis. They are arranged next to each other and The system 22 is installed between the motor 20 and the rim 16. Part of the system 22, or even part of the motor 20, could be housed in the rim 16 to reduce 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.

[0057] The mechanical transmission system 22 includes a mechanical reducer 28, an example of which is illustrated in [Fig.2].

[0058] Figure 2 shows an epicyclic gearbox 28. At the input, the gearbox 28 is connected to a shaft 30, for example via internal splines 32a. Thus, the shaft 30 drives a planetary gear called the sun gear 32. Conventionally, the sun gear 32 drives a series of gears called satellites 34, which are equally spaced around the same diameter around the X-axis of rotation of the sun gear 32. This diameter is equal to twice the operating center distance between the sun gear 32 and the satellites 34. The number of satellites 34 is generally defined as between three and seven.

[0059] 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 ring 38.

[0060] The output we have: • In this epicyclic configuration, the set of satellites 34 drives the satellite carrier 36 in rotation around the X axis. The ring 38 is fixed to a stator via a ring carrier 40 and the satellite carrier 36 is fixed to another shaft 42. • In another planetary configuration, the set of satellites 34 is held by a satellite carrier 36 which is fixed to a stator. Each satellite drives the ring gear 38 which is connected to the shaft 42 via a ring gear carrier 40. • In another differential configuration, the set of satellites 34 is held by a satellite carrier 36 which is connected to the shaft 30. Each satellite 34 drives the ring 38 which is brought to the shaft 42 via a ring carrier 40.

[0061] Each satellite 34 is mounted to rotate freely by means of a bearing 44, for example, a roller bearing or hydrodynamic bearing. Each bearing 44 is mounted on one of the axes 36b of the satellite carrier 36, and all the axes 36b are positioned relative to each other by means of one or more structural frames 36a of the satellite 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, inspection, repair, or replacement, the axes 36b and the frame 36a may be separated into several parts.

[0062] For the same reasons mentioned above, the teeth 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 sets of chevron teeth cooperating with a crown 38 separated into two half-crowns: • An upstream ring 38a consisting of a rim 38aa and a half-flange for fixing 38ab. On the rim 38aa is the front helix meshed with a helix of the teeth 34a of each satellite 34. The helix of the teeth 34a also meshes with that of the solar 32. • A downstream ring 38b consisting of a rim 38ba and a half-flange for fixing 38bb. On the rim 38ba is the rear helix meshed with a helix of the teeth 34a of each satellite 34. The helix of the teeth 34a also meshes with that of the solar 32.

[0063] If the helix widths vary between the solar 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.

[0064] Figure 2 illustrates the case of a single-stage gear reducer, that is to say that the same toothing 34a of each satellite 34 cooperates with both the solar 32 and the crown 38. Even though the toothing 34a comprises two sets of teeth, these teeth have the same average diameter and form a single toothing called a chevron.

[0065] The mounting half-flange 38ab of the upstream ring 38a and the mounting half-flange 38bb of the downstream ring 38b form the mounting flange 38c of the crown. The crown 38 is fixed to the crown carrier 40 by assembling the mounting flange 38c of the crown 38 and a mounting flange 40a of the crown carrier 40 using a bolted assembly, for example.

[0066] 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.1].

[0067] The reducer 28 of the device 10 according to the invention comprises all the features described above insofar as they are not contrary to or do not contradict what follows.

[0068] The references used in Figures 3 and following and already used in Figures 1 and 2 therefore designate identical or similar elements.

[0069] Figures 3 to 5 illustrate embodiments of a reducer 28 for a device 10 according to the invention, which comprises:

[0070] - a movable ring 38 centered on the X axis and movable around this axis, the movable crown 38 comprising internal teeth 38d,

[0071] - a movable solar 32 centered on the X-axis and movable around this X-axis, the solar mobile 32 comprising external teeth 32a,

[0072] - a fixed solar element 56 centered on the X-axis and comprising an external toothing 56a, this fixed solar panel 56 being configured to be fixed to a stator of device 10, and

[0073] - satellites 34 which are meshed with the solar 32, 56 and the corona 38, the sa tellites 34 being carried by a satellite carrier 36 partially shown which is mobile in rotation around the X axis.

[0074] Each of the satellites 34 has two external teeth 34a, 34b meshed respectively with the teeth 32a, 56a of the fixed sun 32 and mobile 56. One of these external teeth 34a, 34b is further meshed with the teeth 38d of the ring 38.

[0075] In the context of the present invention, the crown 38 is coupled to the shaft 30 of the electric motor 20. The movable solar element 32 is coupled to the shaft 42 of the rim 16 or directly to the rim 16. The invention is also compatible with a disengagement system between the output of the gearbox and the rim (for example, via a movable dog clutch).

[0076] Each of the satellites 34 is meshed with the solar elements 32, 56 and the ring gear 38 and comprises a first external toothing 34a of average diameter Dl, and a second external toothing 34b of average diameter D2, different from DL. In the example shown, Dl is greater than D2. Alternatively, the toothings 34a and 34b could have equal diameters Dl and D2 and different numbers of teeth, so as to have different modules.

[0077] In the embodiment of [Fig. 3], the toothed gear 34a of diameter D1 of each satellite 34 is meshed with the toothed gear 32a of the movable solar element 32 and the toothed gear 38d of the ring 38. The toothed gears 32a, 34a and 38d are thus in the same plane PI perpendicular to the X axis. The toothed gear 34b of diameter D2 of each satellite 34 is meshed with the toothed gear 56a of the fixed solar element 56.

[0078] In the embodiment of [Fig. 4], the toothed gear 34a of diameter D1 of each satellite 34 is meshed with the toothed gear 56a of the fixed solar element 56 and the toothed gear 38d of the ring 38. The toothed gear 34b of diameter D2 of each satellite 34 is meshed with the toothed gear 32a of the movable solar element 32. The toothed gears 56a, 34a and 38d are thus in the same plane PI perpendicular to the X axis.

[0079] In the embodiment of [Fig. 5], the toothed 34a of diameter D1 of each satellite 34 is meshed with the toothed 32a of the movable solar 32. The toothed 34b of diameter D2 of each satellite 34 is meshed with the toothed 56a of the fixed solar 56 and with the toothed 38d of the ring 38. The toothed 56a, 34b and 38d are thus in the same plane PI perpendicular to the axis X.

[0080] In the embodiment of [Fig.5], it is further noted that the crown 38 or the shaft 30 to which it is connected extends around the teeth 34a of the satellites 34.

[0081] In the configuration of [Fig. 3] where the solar element 32 and the movable ring gear 38 mesh with the same teeth 34a of the satellite gears 34, it can be said that the output (torque) of the reducer is aligned with its input. In the configuration of Figures 4 and 5 where the solar 32 and the movable crown 38 mesh teeth 34a, 34b different from the satellites 34, we can say that the output (of torque) of the reducer is opposite to its input.

[0082] The number of teeth of the rotating solar element 32 may differ from the number of teeth of the fixed solar element 56 so as to have different diameters on the two solar elements. Alternatively, the diameters may be equal provided that the two solar elements 32 and 56 have different modules. The direction of rotation of the rotating solar element 32 may depend on the relative diameters of the two solar elements 32 and 56. For example, when the number of teeth of the rotating solar element 32 is greater than that of the fixed solar element 56, the reduction gear 28 is counter-rotating, that is, the rotating solar element 32 rotates in the opposite direction to the ring gear 38. When the number of teeth of the rotating solar element 32 is less than that of the fixed solar element 56, the reduction gear 28 is co-rotating, that is, the ring gear 38 and the solar element 32 rotate in the same direction.

[0083] Figures 6 to 8 illustrate more concretely an embodiment of a device 10 for driving a wheel 12 of a landing gear 14.

[0084] Fig. 6 further shows the position of the motor 20 next to, and in particular to the right of, the reducer 28. Alternatively, the motor 20 could be located to the left of the reducer 28.

[0085] The motor 20 has an annular shape and is arranged next to the ring 38 and on the opposite side of the fixed solar 56. The motor 20 extends at least partly around the movable solar 32 or the shaft 42 connected to this solar.

[0086] The ring 38 and the motor 20 are located on circumferences of the same or nearly the same diameter. The reference numerals 20a and 20b designate, respectively, the rotor and stator of the motor 20, both of which are annular. The stator 20b is fixed to or supported by the housing 26, and the rotor 20a is guided in rotation by roller bearings 46 on the stator or the housing.

[0087] The shaft 30, and in particular the rotor 20a, of the motor 20 is centered and guided by two bearings 46 which are arranged radially inside the rotor 20a.

[0088] The movable solar 32 is centered and guided by two bearings 48, 50, of which a first bearing 48 is located at the right of the toothing 32a of the solar 32, and a second bearing 50 is axially offset from this toothing 32a.

[0089] The second bearing 50 can be located opposite the motor 20, and radially inside it.

[0090] In the example shown, the second bearing 50 is arranged radially inside the bearings 46 for guiding the shaft 30 of the motor 20, and is located axially between these bearings 46.

[0091] The satellite carrier 36 carries the bearings 44 for guiding the satellites 34. The satellite carrier 36 is independent, meaning that it is not connected to the rest of the motor by any torque transmission. It can be supported by any bearing. with the corona 38 or the solar 32. It can also be completely free without support and simply balanced by the satellites 34.

[0092] The teeth 34a, 34b of each of the satellites have different diameters, the smaller diameter tooth 34b of each of the satellites 34 meshes with the tooth 56a of the fixed solar 56. The larger diameter tooth 34a of each of the satellites 34 meshes with the tooth 32a of the mobile solar 32 and the tooth 38d of the ring 38. We therefore find the configuration of [Fig.3].

[0093] Alternatively, the teeth 34a, 34b could have identical diameters with different numbers of teeth.

[0094] The number of satellites 34 of the reducer is equal to five in this example.

[0095] The satellites 34 can be guided by rolling bearings 44 which are at number two per satellite 34 and are mounted around the longitudinal ends of each satellite, between these ends and the satellite carrier s 36.

[0096] The bearings 44 can be roller bearings carried by the planet carrier 36, the teeth 34a, 34b of each of the planets 34 being located between these bearings 44. Alternatively, the bearings 44 can be needle bearings carried by the planet carrier 36, each of the needle bearings being radially aligned with one of the teeth 34a, 34b of the planet 34 for example, as in the illustrated example.

[0097] The present invention makes it possible to obtain a significant reduction ratio in a compact size compared to other more conventional architectures (epi-cycloidal or planetary gear train), and can be integrated more easily into certain systems than a conventional Wolfrom gear train. In the specific case of a conventional Wolfrom, for example, access to solar energy could be more complicated for a large-diameter motor.

Claims

Demands

1. A device (10) for driving at least one wheel (12) of an aircraft landing gear (14), said device (10) comprising: - at least one landing gear wheel (12), this wheel (12) having a rim (16) having an axis of rotation (X), - an electric motor (20) having a shaft (30), - a mechanical transmission system (22) between the shaft of the motor (20) and the rim (16), this mechanical transmission system (22) comprising a mechanical reduction gear (28), characterized in that the mechanical reduction gear (28) comprises: - a movable ring gear (38) centered on the axis (X) and having internal teeth (38d), this movable ring gear (38) being rotationally fixed to the shaft of the motor (20), - a movable sun gear (32) centered on the axis (X) and having external teeth (32a), this movable sun gear (32) being rotationally fixed to the rim (16), - a fixed solar element (56) centered on the axis (X) and which has an external toothing (56a),this fixed solar element (56) being configured to be fixed to a stator of the device (10), and - satellites (34) which are meshed with the crown and the solar elements, the satellites (34) being carried by a satellite carrier (36) rotating about the axis (X), each of the satellites (34) having two external teeth (34a, 34b) meshed respectively with the teeth (32a, 56a) of the fixed and rotating solar elements (32, 56), one of these external teeth (34a, 34b) being further meshed with the teeth (38a) of the crown (38).

2. Device (10) according to claim 1, wherein the teeth (32a, 56a) of the fixed and moving solar elements (32, 56) have the same diameter.

3. Device (10) according to claim 1, wherein the teeth (32a, 56a) of the fixed and moving solar (32, 56) have different diameters.

4. Device (10) according to any one of claims 1 to 3, wherein the teeth (32a, 56a) of the fixed and movable solars (32, 56) have different numbers of teeth.

5. Device (10) according to any one of claims 1 to 4, wherein the teeth (38d) of the crown (38) and the teeth (32a) of the mobile solar element (32) are meshed with the same teeth (34a, 34b) of each of the satellites (34).

6. Device (10) according to any one of claims 1 to 4, wherein the teeth (38d) of the crown (38) and the teeth (56a) of the fixed solar (56) are meshed with the same teeth (34a, 34b) of each of the satellites (34).

7. Device (10) according to any one of the preceding claims, wherein the crown (38) is meshed with one of the teeth (34a, 34b) of each of the satellites (34) and extends around the other teeth (34b, 34a) of each of the satellites (34).

8. Device (10) according to any one of the preceding claims, wherein all the teeth (32a, 34a, 34b, 38d, 56a) are selected from straight, helical or herringbone teeth.

9. Device (10) according to any one of the preceding claims, wherein the motor (20) has an annular shape centered on the axis (X) and is arranged axially between the wheel and the reducer (28).

10. Device (10) according to any one of the preceding claims, wherein the motor (20) extends at least partially around the mobile solar element (32).

11. Device (10) according to any one of the preceding claims, wherein the teeth (34a, 34b) of each of the satellites (34) have different diameters (D1, D2), the tooth (34b) of smaller diameter (D2) of each of the satellites (34) meshing with the tooth (56a) of the fixed solar (56), and the tooth (34a) of larger diameter of each of the satellites (34) meshing with the tooth (32a) of the mobile solar (32).

12. Device (10) according to any one of the preceding claims, in which the electric motor (20) is disposed on the side of the crown (38) and on the opposite side of the fixed solar (56). Device (10) according to any one of the preceding claims, in which the movable solar (32) is centered and guided by two bearings (48, 50) of which a first bearing (48) is located at the toothing (32a) of the solar, and a second bearing (50) is axially offset from this toothing (32a).

13. Device according to the preceding claim, wherein the second bearing (50) is located at the right of said motor (20), and radially inside it.

14. Device (10) according to any one of the preceding claims, wherein the shaft (30) of the motor (20) is centered and guided by two bearings (46) which are arranged radially inside a rotor (20a) of said motor.

15. A device according to all claims 14 and 15, wherein the second bearing (50) is arranged radially inside the bearings (48, 50) for guiding the shaft (30) of the motor (20), and is located axially between these levels (48, 50).

16. Device (10) according to any one of the preceding claims, in which each of the satellites (34) is centered and guided by two bearings (44) which are located respectively at the teeth (34a, 34b) of this satellite (34).

Images