Drive unit for a vehicle, AXLE and heavy-duty vehicle comprising such a drive unit

Abstract

A drive unit (5) for a vehicle (2) comprises: - an electric motor (8); - a transmission system; - a planetary gear train (20), comprising a housing (61), an input gear (22) driven by the transmission system, a ring gear (24), a sun gear (25), a planet carrier (27) and planet gears (21), the planet gears meshing with the ring gear and the sun gear, the input gear meshing with the transmission system; - a differential (40), driven by the planet carrier; - two wheel shafts (50, 52), extending along a rotation axis (X50) and driven by the differential. The planetary gar train is fitted concentrically around one of the two wheel shafts and rotates around the rotation axis. The ring gear is axially moveable, so as to slide onto the planet gears, between a first position, engaged with the housing, and a second position, engaged with the input gear.

Description

DRIVE UNIT FOR A VEHICLE, AXLE AND HEAVY-DUTY VEHICLE COMPRISING SUCH A DRIVE UNITTECHNICAL FIELD

[0001] The disclosure relates generally to electromobility applied to heavy-duty vehicles. In particular aspects, the disclosure relates to a drive unit for a vehicle, an axle comprising such a drive unit and a heavy-duty vehicle comprising such a drive unit. The disclosure can be applied to heavy-duty vehicles, such as trucks, buses, and construction equipment, and also to other vehicle types, such as automobiles among other vehicle types. Although the disclosure may be described with respect to a particular vehicle, the disclosure is not restricted to any particular vehicle.BACKGROUND

[0002] To decrease environmental impacts of heavy-duty vehicles, transport industry is moving towards electro mobility to replace internal combustion engines by electric motors. Traditionally, the electric motor is positioned in the same place as the internal combustion engine it replaces, i.e. under the truck cab, and may use a transmission.

[0003] However, positioning one or more electric motors as close as possible to the wheels, directly on their axle, is advantageous. Such configuration is known as electric axle or “E-axle” configuration and improves performance of the vehicle, by reducing losses in the transmission. In addition, such a configuration is more compact, freeing up space available for batteries.

[0004] One of the challenges for such a configuration is to make the electric axle as compact as possible, so as not to interfere with other vehicle features, such as the suspension or braking system. The invention aims to provide a particularly compact drive unit.SUMMARY

[0005] According to a first aspect of the disclosure, a drive unit, for a vehicle, comprises: at least one electric motor, a transmission system, a planetary gear train, comprising a housing, an input gear, a ring gear, a sun gear, a planet carrier and planet gears, the planet gears meshing with the ring gear and the sun gear, the input gear meshing with the transmission system,a differential, having an input element fixed in rotation with the planet carrier, and two wheel shafts, extending along a rotation axis and configured to drive wheels of the vehicle.The transmission system is configured to transmit motor torque generated by the at least one electric motor to the input gear of the planetary gear train, the planet carrier of the planetary gear train is configured to transmit said motor torque to the input element of the differential, and the differential is configured to distribute said motor torque to the two wheel shafts.The planetary gear train is fitted concentrically around one of the two wheel shafts, the planet carrier rotating around the rotation axis, and the ring gear is axially moveable, along the rotation axis, so as to slide onto the planet gears, between: a first position, in which the ring gear engages with the housing so that a rotation of the ring gear around the rotation axis is locked relative to the housing, and a second position, in which the ring gear engages with the input gear so as to be driven in rotation around the rotation axis by the input gear.

[0006] The first aspect of the disclosure may seek to improve the compactness of the drive unit. Indeed, thanks to the ring gear of the planetary gear train being axially moveable so as to be engaged or disengaged with the housing and the input gear, there is no need for an actuator located axially on a side of the planetary gear train, so that the axial compactness of the drive train is improved. Furthermore, as the planetary gear train is fitted concentrically around one of the two wheel shafts, the radial compactness of the drive unit is improved. In addition, as the planet carrier is fixed in rotation with the input element of the differential, there is no need for intermediate components between the differential and the planetary gear train, improving the general compactness of the drive unit. A technical benefit may include reducing the conflict with other components of the electric vehicle, such as the suspension or braking system.

[0007] Optionally in some examples, including in at least one preferred example, the planetary gear train is operable between two configurations: a first configuration, in which the ring gear is in its first position and in which the sun gear engages with the input gear so as to be driven in rotation by the input gear around the rotation axis, and a second configuration, in which the ring gear is in its second position and in which the sun gear engages with the input gear so as to be driven in rotation by the input gear around the rotation axis. A technical benefit may include allowing the planetary gear train to benefit from two gear ratios.

[0008] Optionally in some examples, including in at least one preferred example, the planetary gear train is further operable in a neutral configuration, in which the ring gear and / orthe sun gear are disengaged from the input gear and from the housing. A technical benefit may include allowing the planetary gear train to benefit from more gear ratios.

[0009] Optionally in some examples, including in at least one preferred example, the planetary gear train is further operable in a third configuration, in which the ring gear is in its second position and in which a rotation of the sun gear around the rotation axis is locked relative to the housing. A technical benefit may include allowing the planetary gear train to benefit from more gear ratios.

[0010] Optionally in some examples, including in at least one preferred example, in the third configuration of the planetary gear train, the rotation of the sun gear around the rotation axis is locked by engaging the sun gear with the housing. A technical benefit may include efficiently locking rotation of the sun gear.

[0011] Optionally in some examples, including in at least one preferred example, the drive unit further comprises a sun gear dog clutch including a control ring, axially moveable along the rotation axis and rotationally coupled with the sun gear. In the first and third configurations of the planetary gear train, the control ring is moved along the rotation axis in a position in which the control ring engages the sun gear with the input gear. In the second configuration of the planetary gear train, the control ring is moved along the rotation axis in a position in which the control ring engages the sun gear with the housing so that a rotation of the sun gear around the rotation axis is locked. A technical benefit may include efficiently engaging the sun gear with the housing or with the input gear.

[0012] Optionally in some examples, including in at least one preferred example, the drive unit further comprises a fork configured to axially move the control ring along the rotation axis. A technical benefit may include efficiently operating the control ring.

[0013] Optionally in some examples, including in at least one preferred example, the drive unit further comprises a ring gear dog clutch, provided between the input gear and the ring gear and operable between a coupled configuration, in which the ring gear is in the second position, and an uncoupled configuration, in which the ring gear is disengaged from the input gear. A technical benefit may include efficiently engaging or disengaging the sun gear with the input gear.

[0014] Optionally in some examples, including in at least one preferred example, the drive unit further comprises an actuating element, configured to move the ring gear along the rotation axis between its first position and its second position. A technical benefit may include efficiently engaging the sun gear with the housing or with the input gear.

[0015] Optionally in some examples, including in at least one preferred example, the actuating element is ring-shaped and fitted inside an external groove of the ring gear. A technical benefit may include increasing the axial compactness of the drive unit by fitting the actuating element in the groove of the ring gear.

[0016] Optionally in some examples, including in at least one preferred example, the differential comprises a differential housing, fixed to the planet carrier so that the differential housing is fixed in rotation with the planet carrier and fixed to the input element of the differential so that the differential housing is fixed in rotation with the input element. A technical benefit may include efficiently driving the input element of the differential with the planet carrier.

[0017] Optionally in some examples, including in at least one preferred example, the differential housing and the planet carrier are a single component. A technical benefit may include efficiently driving the input element of the differential with the planet carrier, reducing the complexity of the drive train and increasing its compactness, as the differential housing and the planet carrier are the same part.

[0018] Optionally in some examples, including in at least one preferred example, the input element of the differential is a differential cross. A technical benefit may include directly driving the differential cross of the differential with the planet carrier.

[0019] Optionally in some examples, including in at least one preferred example, the transmission system consists of a gear train, the input gear meshing with the gear train. A technical benefit may include allowing the planetary gear train to benefit from more gear ratios.

[0020] Optionally in some examples, including in at least one preferred example, the gear train includes a motor output shaft for each electric motor, each motor output shaft having a first pinion gear, and an intermediate shaft for each electric motor, each intermediate shaft having a second pinion gear and a third pinion gear, each second pinion gear meshing with a first pinion gear, each third pinion gear meshing with the input gear. A technical benefit may include obtaining a suitable reduction ratio between the electric motor(s) and the input gear, thanks to the two reduction stage.

[0021] Optionally in some examples, including in at least one preferred example, the housing encapsulates the ring gear, the sun gear, the planet carrier and the planet gear. A technical benefit may include improving the compactness of the drive unit and protecting the moving components of the planetary gear train from contaminants.

[0022] According to a second aspect of the disclosure, an axle comprises an axle body and a drive unit, the drive unit being as described here above. A technical benefit may include obtaining a compact axle, that can easily be fitted in a vehicle.

[0023] Optionally in some examples, including in at least one preferred example, the axle body is the housing of the planetary gear train. A technical benefit may include increasing the compactness of the axle.

[0024] Optionally in some examples, including in at least one preferred example, the axle further comprises a suspension system attached to the axle body.

[0025] According to a third aspect of the disclosure, a heavy-duty vehicle comprises a drive unit as described here above or an axle as described here above. The third aspect of the disclosure may seek to increase the available space in the vehicle and reduce conflict between the drive unit and other components of the vehicle. A technical benefit may include allowing the vehicle to have more components, such as batteries and facilitating the assembly of the vehicle.

[0026] The disclosed aspects, examples (including any preferred examples), and / or accompanying claims may be suitably combined with each other as would be apparent to anyone of ordinary skill in the art. Additional features and advantages are disclosed in the following description, claims, and drawings, and in part will be readily apparent therefrom to those skilled in the art or recognized by practicing the disclosure as described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Examples are described in more detail below with reference to the appended drawings.

[0028] FIG. 1 is an exemplary perspective view of a heavy-duty vehicle, e.g. a truck, according to one example.

[0029] FIG. 2. is an exemplary perspective view of an electric rear axle belonging to the vehicle of FIG. 1.

[0030] FIG. 3 is a side section view of the axle of FIG. 2.

[0031] FIG.4 and 5 are perspective views of the transmission system between electric motor(s) and gearbox of the axle.

[0032] FIG. 6 is a longitudinal section of FIG. 4.

[0033] FIG. 7 is an enlarged view according to rectangle VII of FIG. 6.

[0034] FIG. 8 is another longitudinal section of the axle.

[0035] FIG. 9 and 10 are section views of the gearbox in a first configuration.

[0036] FIG. 11 and 12 are section views of the gearbox in a second configuration.

[0037] FIG. 13 and 14 are section views of the gearbox in a third configuration.

[0038] FIG. 15 is a section of the gearbox.

[0039] FIG. 16 and 17 are enlarged views of FIG. 15.

[0040] FIG. 18 represents an axle provided with two wheel drive units according to a second example.

[0041] FIG. 19 represents two wheel drive unit according to a third example.

[0042] FIG. 20 is a schematic representation of another exemplary vehicle comprising a wheel drive unit.DETAILED DESCRIPTION

[0043] The detailed description set forth below provides information and examples of the disclosed technology with sufficient detail to enable those skilled in the art to practice the disclosure.

[0044] FIG. 1 is an exemplary perspective view of a heavy-duty vehicle 2. According to this example, the heavy-duty vehicle 2 is a truck. Alternatively, it can be any other heavy-duty vehicle such as a bus, an armored / military vehicle or construction equipment such as a wheel loader, a rigid or articulated hauler.

[0045] The vehicle 2 includes a front axle 4 and a rear axle 6, according to a 4*2 (or 4 by 2) configuration, which means that only the wheels of rear axle are driven. Obviously, many other configurations can be implemented, such as a 6 by 2 or a 6 by 4 configuration. Also, all wheels can be driven, e.g. according to a 4 by 4 configuration.

[0046] In the example, vehicle 2 includes a wheel drive unit or system 5 that is designed to be fitted on a chassis of the vehicle (not shown). More precisely, the wheel drive unit 5 is designed to be fastened to a suspension system which, itself, is fastened to the chassis, e.g. to one or both longitudinal steel beams / rails of the chassis, using fasteners such as bolts. The wheel drive unit is to be considered as independent / removable from the rest of the vehicle, like a spare part. The wheel drive unit is designed for driving one or more wheels in rotation. Accordingly, the wheel drive unit 5 includes at least one wheel shaft 50, 52, at the end of which is provided a wheel hub. In a variant not shown, the wheel shaft could be used to drivesomething other than a wheel. For instance, the wheel shaft 50, 52 could be used to drive a boat propeller or a track roller (for construction equipment). This means that the wheel drive unit can be used for other applications than vehicles on wheels.

[0047] According to a first embodiment, the wheel drive unit 5 is part of an axle, e.g. the rear axle 6, which is therefore designated as an ‘e-axle’ corresponding to an axle that directly supports the wheel drive unit. This is in opposition with traditional configurations wherein the wheel drive unit is often remote from the rear axle and wherein a propeller shaft is used for transmitting the torque. The wheel drive unit 5 comprises at least one electric motor 8, capable of generating a motor torque.

[0048] In one example, the wheel drive unit 5 also includes two wheel shafts 50, 52 and a differential 40 for distributing the torque to the two wheel shafts 50, 52. Preferably, and as shown on fig. 2 and 3, the wheel drive unit 5 comprises two electric motors 8. The rotation axes of the two wheel shafts are coincident / superimposed, the rotation axis of the two wheel shafts being designated as X50.

[0049] Preferably, differential 40 includes a differential housing 42.

[0050] The wheel drive unit 5 also includes a gearbox 20 for transmitting the torque of the motor(s) to the two wheel shafts 50 and 52, indirectly through the differential 40. Preferably, the gearbox 20 is provided with one, two or three speed ratios. Obviously, gearbox 20 is automatic, which means that the gears are shifted automatically as a function of torque demand on wheels and / or vehicle speed to adapt to driving conditions.

[0051] The wheel drive unit 5 also includes a transmission system between the electric motor(s) 8 and the gearbox 20. The transmission system is configured to transmit the motor torque generated by the electric motor(s) 8 to the gearbox 20.

[0052] In the example, each one of the two wheel shafts 50, 52 is connected to a wheel hub to which is fixed a wheel rim which, itself, supports a tyre. In other words, each wheel shaft 50, 52 extends between the differential 40 and a wheel hub.

[0053] The electric motor(s) 8 extend(s) parallel to the wheel shaft(s) 50, 52, which means that the rotation axis of each motor is parallel to the wheel shaft rotation axis X50. Needless to say that the rotation axis of the electric motor to which it is referred to is the rotation axis of output shaft / rotor. As a result, the electric motor(s) 8 extend(s) transversally (and horizontally) in the vehicle reference frame (the longitudinal direction being the vehicle movement direction front / rear). The advantage is that the electric motors 8 can benefit from the whole spacingbetween the two longitudinal beams, without requiring much space in the longitudinal direction.

[0054] In the example, the axle 6 comprises an axle body / housing 61 inside which are received the two wheel shafts 50, 52 and a suspension system attached to said axle body 61. Axle body 61 is only partially visible on the figures, e.g. on FIG. 3 and 15 to 17 for clarity / conciseness purpose. The suspension system ensures the connection / link between the axle 6 and the vehicle chassis consisting of two longitudinal steel beams. In the example, and as it is quite common on heavy-duty vehicles, the suspension system is pneumatic: It includes at least one air bellow at each (longitudinal) end of the axle. Preferably, four air bellows are provided, respectively two front air bellow 12 and two rear air bellow 10. The four air bellows each comprise a top interface for attachment to the chassis.

[0055] Such suspension system is well known from one skilled in heavy-duty vehicles architecture / structure, which is why no further details are given herein. According to the embodiment of FIG. 2, the suspension system includes two connecting rods hinged at one end, so as to form a so called ‘V-stay’ 16. A 4-air bellow suspension is a non-reactive suspension, which means that torque reaction does not generate suspension movements as the resisting torques are taken / ab sorbed by the V-stay 16 and reaction rods. It does not pass through the air bellows. A 4-air bellow suspension allows provides higher comfort regardless of the axle load is (by adjusting air pressure). A 4-air bellow suspension also enables a vertical chassis height adjustment (almost as it is a parallelogram movement) that can be used to adjust the truck height at a loading deck and to dock / undock trailers.

[0056] On top of that, the suspension system includes a shock absorber or damper 14 visible on Figures 2 and 3. In the example, the shock absorber 14 is a hydraulic cylinder.

[0057] Advantageously, each electric motor 8 is closer to the wheel shaft(s) rotation axis X50 than each rear air bellow 10. This means that the distance, measured radially, between the wheel shaft rotation axis X50 and the rear air bellow 10 is greater than the distance, measured radially, between the wheel shaft rotation axis X50 and the electric motor(s) 8. In addition, the electric motors 8 are located behind the rear air bellow 10 according to transversal direction, which means that the rear air bellow 10 acts, together with the tyre, as a shield / protection for the electric motor(s) 8 in case of a side crash. Besides, and since the two rear air bellows are located behind the electric motor(s) (far away from wheel shafts), they also act as protection members in case of a crash with a following vehicle or rear obstacle as the air bellows would get hit first and absorb kinetic energy.

[0058] Also, the electric motors 8 do not occupy much space in the vehicle longitudinal direction, which means that it leaves some space / room between the two chassis longitudinal beams, e.g. for fitting aftermarket elements or Bodybuilder.

[0059] In the example, the two electric motors 8 are fitted at the same distance from the wheel shaft rotation axis X50, resulting in that the two electric motors 8 are approximately fitted one above the other.

[0060] Advantageously, the transmission system to which it is referred to above consists of a gear train. For example, the gear train provides at least two reduction stages.

[0061] According to one example, the gear train includes a first pinion gear 32 provided on a motor output shaft 80 and an intermediate shaft 37 supporting a second and a third pinion gear, resp. 36 and 34. Second pinion gear 36 meshes with first pinion gear 32 and third pinion gear 34 meshes with an input gear 22 of the gearbox 20 (also known as the ‘main gear’).

[0062] Obviously, in case two electric motors are provided, as for the configuration of FIG. 2 and 3, a first pinion gear 32 is provided of the output shaft 80 of each motor 8 and two intermediate shafts 37 are provided, resp. one for each motor 8. Accordingly, there is a first, second and third pinion gear, resp. 32, 36 and 34, for each motor. All third gears 34 mesh with one and the same input gear 22 of the gearbox 20, which means that the motors 8 are spatially arranged around the input gear 22 of the gearbox 20.

[0063] Preferably, second and third pinion gears, resp. 36 and 34, are rotationally fixed one to the other.

[0064] According to one embodiment, second and third pinion gears, resp. 36 and 34, are arranged side by side along a rotation axis of intermediate shaft 37. In detail, second pinion gear 36 has a greater / larger diameter than third pinion gear 34. Also, third pinion gear 34 is fitted around a smooth sleeve 35 that is, in the example, integral with the second pinion gear 36. This smooth sleeve 35, which is itself fitted around the intermediate shaft 37, forms a shoulder with the second pinion gear 36, of larger diameter.

[0065] Preferably, the gearbox 20 is a planetary gear train. As a result, it includes a sun gear 25, planet gears 21 and a ring gear 24. Gearbox 20 also includes a fixed housing / casing encapsulating the elements of the planetary gear train.

[0066] In the example, there are five planet gears 21 but obviously more or less planet gears can be provided. Planet gears 21 mesh with the sun gear 25 and ring gear 24. They are spatially arranged between sun gear 25 and ring gear 24. Planet gears 21 are each fitted on a shaft / pin 26 that belongs to a planet carrier 27 and can each spin around said shaft 26. In the example,ring gear 24 can be moved axially, which means that it is slidable along a direction parallel to its central / rotation axis. In other words, ring gear 24 slides onto planet gears 21. As shown on FIG. 6, an actuating element 23 is provided. This actuating element 23 is ring-shaped and is fitted inside an external groove of ring gear 24, so that element 23 can push the ring gear 24 in one direction or the other.

[0067] In the example, planet carrier 27 can be considered as the output element of the gearbox and input gear 22 can be considered as the input element of the gearbox.

[0068] Preferably, the rotation axis of sun gear 25 is superimposed / coincident with the rotation axis of input gear 22. The rotation axis of input gear 22 is superimposed / coincident with the rotation axis of planet carrier 27. The rotation axis of planet carrier 27 is superimposed / coincident with the rotation axis of the wheel shaft(s) X50. As a result, rotation axis of planet carrier 27 is superimposed / coincident with rotation axis of differential input element, e.g. differential cross 44. All in all, this means that the gearbox / planetary drive train is fitted concentrically around the wheel shaft 50 and / or 52.

[0069] In the example of FIG. 7, a 4-point contact ball bearing 54 is radially arranged between the sun gear 25 and input gear 22. Preferably, the input gear 22 is pivotably attached to the gearbox housing 61. This input gear 22 takes / withstands the axial forces from the sun gear mesh thanks to the 4-point contact ball bearing 54 acting as a bidirectional thrust. Both axial loads (from input gear mesh and from sun gear being designed to counteract. The sun gear centering (radial loads) is achieved by the planet gear teeth and the clutch mechanism. This arrangement allows to have only one bearing to support sun gear, allowing to save mass, cost, space and efficiency. It also reduces the system hyper statism and releases production tolerances.

[0070] According to one example shown on FIG. 17, a double row tapered roller bearing 55 is fitted between the input gear 22 and the axle housing / body 61. This allows to completely remove the shimming from the assembly, ensures manufacturing efficiency and reliability, and makes the system easier to scale up and to regionalize. In variant, the double row tapered roller bearing 55 could be replaced by two unitized bearing (e.g. pre-set bearings).

[0071] According to a variant shown on FIG. 18, the design of input gear 22 is such that it allows replacing the double row tapered roller bearings by two tapered roller bearings fitted on each (axial) side of input gear. This makes the input gear straighter but adds preload complexity for the bearings and another housing slice.

[0072] Preferably, a needle roller bearing 58 is provided radially between the sun gear 25 and the planet carrier 27. The needles of such needle roller bearing 58 enable to radially support the differential mass on one side. As shown on FIG. 15 and 16, a ball bearing 56 is provided on the other side, such ball bearing 56 ensuring, on top of supporting differential mass, to hold the differential 40 in position in transversal direction (transversally). In detail, ball bearing 56 is arranged radially between differential housing 42 (rotating) and axle body 61 (non-rotating).

[0073] Advantageous, the fact of having a needle roller bearing 58 between the input gear 22 and the differential housing / planet carrier 27, allows to slide the differential unit / assembly into the input gear, without the need to add any stop. This simplify a lot the assembly, and contributes to the compacity of the system as the differential 40 is held in position by the ball bearing 56 on the other side

[0074] The 4-point contact ball bearing 54, the ball bearing 56 and the needle roller bearing 58 are non-preloaded bearings that are particularly visible on FIG. 16 and 17.

[0075] Preferably, the differential 40 to which it is referred to is mounted ‘floating’ inside axle body and therefore can be assimilated to a ‘floating’ differential. Basically, the differential 40 forms a single unit with the gearbox 20 as the differential housing 42 is fixed to planet carrier 27. As a result, the differential forces are transmitted through the planetary carrier (same component as differential housing 42). This assembly is subjected only to ‘pure’ torque, even if it’s the system which sees / supports the highest forces (the closest to the wheel), its bearings only have to support its mass. Instead of using two big taper roller bearings which are costly, heavy, pre-loaded and non-efficient, it can be supported by non-preloaded bearings, cheaper, more efficient and simpler to integrate.

[0076] A first configuration in which a first gear ratio (‘Gear 1’) is engaged is represented on FIG. 9 and 10. In such configuration, input gear 22 drives the sun gear 25 in rotation (Cf. arrow A2). Ring gear 24 is moved / located in a position (on the right on figure 10) in which it is engaged / coupled to the gearbox housing. As a result, the rotation of the ring gear 24 is locked, which forces the planet gears 21 to spin (Cf. arrow A3) and the planet carrier 27 to rotate in the same direction as the sun gear 25 (Cf. arrow Al).

[0077] A second configuration in which a second gear ratio (‘Gear 2’) is engaged is represented on FIG. 11 and 12. In such configuration, ring gear 24 is axially moved / located in a position (on the left on figure 12) in which it engages with input gear 22. As a result, ring gear 24 is in a position where it can be driven by the ring gear 24 in rotation. Ring gear 24 rotates (Cf. arrow A4). The rotation of the sun gear 25 is locked, which forces the planet gears21 to spin (Cf. arrow A3) and the planet carrier 27 to rotate in the same direction as the ring gear 24 (Cf. arrow Al).

[0078] A third configuration in which a third gear ratio (‘Gear 3’) is engaged is represented on FIG. 13 and 14. In such configuration, ring gear 24 is the same position / configuration as for ‘Gear 2’ : It engages with input gear 22, the rotation of which can therefore be transmitted to ring gear 24. As a result, input gear 22 drives both the sun gear 25 and the ring gear 24 at the same rotation speed (Cf. arrows A2 and A4 respectively). This involves that the planet gears 21 do not spin and forces the planet carrier 27 to rotate in the same direction (Cf. arrow Al). This configuration is also known as ‘Direct drive’ because the rotation speed of the gearbox input element is equal to the rotation speed of the gearbox output element.

[0079] Typically, 1stgear ratio can be used in situation where a high torque is to be delivered to the wheels, such as at low speed and / or starting.

[0080] 2ndgear ratio can be used for mid-range speed.

[0081] 3rdgear ratio (‘Direct drive’) can be used in cruising conditions, e.g. when moving on highways or the like.

[0082] Advantageously, the three different gear ratios can be selected using two separate clutches, e.g. dog clutches.

[0083] In the example, a first dog clutch is provided between the input gear 22 and the ring gear 24. In coupled configuration (dog clutch in a closed position), the ring gear 24 (which can be moved axially) is forced into a first position in which it is rotationally coupled to the input gear 22. In detail, splines or teeth of input gear 22 are engaged into corresponding grooves or teeth of ring gear 24. In an uncoupled configuration, (dog clutch open), the ring gear 24 is forced into a second position in which it is axially remote from the input gear 22 and in which it is not driven (locked).

[0084] Also, a second dog clutch is provided between the input gear 22 and the sun gear 25. As shown on FIG. 7, said second dog clutch includes a control ring 11 whose central axis is coincident / superimposed with that of input gear 22 and sun gear 25. Control ring 11 is moveable in translation. In detail, a fork (partially shown) enables to move control ring 11 in translation. Said fork includes two branches whose ends are fitted into a radial groove of the control ring. Slides, preferably frictionless slides, are provided at the ends of the fork branches to allow a free rotation of the control ring 11. Control ring 11 includes splines or the like on its radial internal surface, in order to engage with corresponding splines or grooves of the sun gear25. Advantageously, control ring 11 includes splines or the like on its radial external surface, in order to engage with corresponding splines or grooves of the input gear 22.

[0085] In a closed configuration of this second dog clutch, the control ring 11 is moved into a position in which it engages simultaneously with the sun gear 25 and input gear 22, thereby transmitting the rotation of input gear 22 to the sun gear 25. In the open configuration of this second dog clutch, the control ring 11 is moved axially away from the sun gear 25, so that it does not drive the sun gear 25 in rotation. Preferably, control ring 11 is also disconnected from input gear 22. As a result, sun gear 25 remains immobile (Non-driven).

[0086] In a variant not shown, control ring is fixed in rotation with sun gear 25. According to a first configuration (‘Gear 1’), control ring is forced into a position in which it is engaged with input gear 22, thereby driving the sun gear 25 from the rotation of input gear 22. In a second configuration (‘Gear 2’), control ring is forced into a position in which it is engaged with the gearbox housing, the rotation of control ring being locked / blocked. As a result, sun gear is also kept immobile (non-driven). In a third configuration (‘Gear 3’), control ring is forced into a position in which it is engaged with input gear 22, thereby driving the sun gear 25 from the rotation of input gear 22. In a neutral configuration, control ring is forced into a free position in which it neither engages with the sun gear, nor gearbox housing. In a preferred embodiment, control ring is a single part / component but in variant(s), it could be made of two or more separate components.

[0087] Advantageously, the gearbox 20 includes a neutral / freewheel configuration in which the first and second clutches are open, thereby disconnecting the input gear 22 from the sun gear 25 and from the ring gear 24. In such configuration, ring gear 24 is in an intermediate / free position in which it is neither engaged with gearbox housing nor input gear 22. As a result, a rotation of the wheel shaft(s) 50, 52 cannot be transmitted to the input gear 22. In such freewheel configuration, only the three bearings 54, 56 and 58 are rotating, which means no gear mesh and no splash losses.

[0088] In a variant not shown, the gearbox only includes two speed ratios. For instance, this can be achieved by having a fixed connection / coupling between the input gear 22 and sun gear 25. As a result, only one clutch would remain for actuating / moving the ring gear 24. This could be done for 6x4 trucks or Medium-Duty applications (and results in having only the start and cruise gears) in order to save even more mass and cost.

[0089] As it is well known from one skilled in the art, these clutches can be automatically actuated, e.g. electrically actuated or pneumatically / hydraulically actuated.

[0090] In the example, the planet carrier 27 of the gearbox 20 is fixed in rotation with the differential housing 42. In detail, the differential assembly 40 includes a differential cross 44 composed of four identically designed pins joining at the center of the differential cross. In this specific example, the differential cross 44 is fixed in rotation with the differential housing 42, which therefore rotates in normal operating conditions.

[0091] Obviously, this differential example is one design among others: In some variants, the differential assembly can be different. For instance, the differential assembly could include a crown wheel meshing with a drive pinion which, itself, would be driven by the planet carrier 27.

[0092] As shown on FIG. 15, a differential lock mechanism 60 is provided. This differential lock mechanism 60 is described in European patent No. EP23160898.5 incorporated herein, which is why no further details are given in relation to this differential lock mechanism.

[0093] FIG. 18 shows a second embodiment of the invention, in which the axle 6 comprises two wheel drive units 5 and 5’. The two wheel drive units 5 and 5’ are identical or similar to the one of first embodiment, with the exception that each wheel drive unit 5, 5” includes only one electric motor (But it could include two or more motors each). Similarly, the gearbox can be different: More or less gear ratios can be provided. For instance, it is possible to have a 2- speed gearbox on the left and a 3-speed gearbox on the right. Each wheel drive unit comprises its own gearbox and its own transmission. The two gearboxes are connected to one and the same differential assembly, which means that the two wheels can be driven using only one of the two electric motors. Another main benefit is that power transmission can be conserved during gearshift (which is known as ‘powershifting’): Indeed, when shifting gear on one side, gearbox can be kept engaged on the other side in order to keep torque to the wheel / differential. As a result, the driver does not even feel that gear is shifted, which improves driving comfort.

[0094] Considering that the two gearboxes each have three speed ratios, the combination of the two enables to reach at least 6 different speed ratios (1-1, 1-2, 1-3, 2-2, 2-3, 3-3). Obviously, more than 6 combinations can be obtained if the two gearboxes have different speed ratios. Also, additional combinations can be obtained by setting one gearbox to neutral.

[0095] FIG. 19 shows a third embodiment of the invention, in which two separate wheel drive units 5 and 5’ are provided, respectively one drive unit 5, 5’ for each wheel. According to this configuration, which is known as ‘Torque vectoring’, a direct connection is provided between the gearbox and the wheel shaft, which means that there is no differential assemblyand no axle per se. In detail, the planet carrier 27 of the gearbox 20 can be rotationally fixed / coupled to the wheel shaft 50 or 52. Advantageously, a clutch, e.g. dog clutch, can be provided between the gearbox planet carrier 27 and wheel shaft 50 or 52, which means that planet carrier 27 drives the wheel shaft 50 or 52 only in operating conditions when clutch is closed. In a variant, planet carrier 27 can be permanently coupled to wheel shaft without any clutch in-between.

[0096] Preferably, each wheel drive unit comprises its own suspension system to be attached / fastened to the vehicle chassis.

[0097] Optionally, the wheel drive unit further comprises a high-speed retarder, e.g. a hydraulic retarder. An example of hydraulic retarder is described in European patent application N° 22199350.4 which is incorporated herein.

[0098] Another exemplary heavy-duty vehicle 2 is now described with reference to the schematic representation of Figure 20, focusing of its drive unit 5. The drive unit 5 is part of an axle 6 as described here above. In the example, the heavy-duty vehicle 2 is an electric vehicle.

[0099] The drive unit 5 of the vehicle 2 of Figure 20 is similar to the one described here above, but comprises only one electric motor 8. The components similar to those described here above share the same reference and operate similarly.

[0100] Hence, the drive unit 5 of Figure 20 comprises an electric motor 8, a transmission system, a planetary gear train 20, or epicyclic gear train, a differential 40 and two wheel shafts 50, 52, both extending along a common rotation axis X50 and configured to drive wheels of the vehicle 2. In the example, the wheel shaft 50 drives a wheel 70 of the vehicle 2 and the wheel shaft 52 drives a wheel 72 of the vehicle.

[0101] The planetary gear train 20 comprises a housing 61, an input gear 22, a ring gear 24, a sun gear 25, a planet carrier 27 and planet gears 21, the planet gears being mounted onto the planet carrier so as to freely rotate around their respective axis and meshing with the ring gear 24 and the sun gear 25. Preferably, the housing 61 encapsulates the input gear 22, the ring gear 24, the sun gear 25, the planet carrier 27 and the planet gears 21. The housing 61 is only represented schematically in Figure 20, for the clarity of the drawing.

[0102] In the example, the housing 61 of the planetary gear train 20 is the same housing as the housing of the axle 6. In other words, a common housing is used for encapsulating the planetary gear train 20 and for encapsulating the other components of the axle 6.

[0103] The input gear 22 meshes with the transmission system, so that the transmission system is configured to transmit motor torque generated by the electric motor 8 to the input gear 22.

[0104] In the example, the transmission system consists of a gear train, with which the input gear meshes. More precisely, the gear train comprises a motor output shaft 80, driven by the electric motor 8 and having a first pinion gear 32; and an intermediate shaft 37 having a second pinion gear 36 meshing with the first pinion gear 32 and a third pinion gear 34 meshing with the input gear 22. As an alternative, not shown, the transmission system does not comprise an intermediate shaft, the first pinion gear 32 of the motor output shaft 80 directly meshing with the input gear 22.

[0105] The differential 40 comprises an input element 44, which is fixed in rotation with the planet carrier 27 so that the planet carrier is configured to transmit a motor torque circulating in the planetary gear train 20 to the input element 44 of the differential. The input element 44 rotates around the rotation axis X50.

[0106] In the example, the differential 40 comprises a differential housing 42, to which the input element 44 is fixed, so that the differential housing is fixed in rotation with the input element. Preferably, the input element 44 is a differential cross, comprising several pins, in the example four pins. In addition, in the example, the differential 40 also comprises output elements 74, 76, respectively driving the wheel shaft 50 and the wheel shaft 52, and planet gears 78. The planet gears 78 are mounted on the pins of the differential cross 44 and mesh with the output elements 74, 76. The planet gears 78 can rotate around their respective axis, which are orthogonal to the rotation axis X50, and can revolve around the rotation axis X50, by being carried by the input element 44.

[0107] Preferably, the differential housing 42 and the planet carrier 27 are a single component. In other words, the planet carrier acts as the differential housing and the input element 44 is fixed onto the planet carrier. To this end, the planet carrier 27 extends along the rotation axis X50 so as to extend around the input element 44 of the differential 40.

[0108] As the differential 40 is connected to the planetary gear train 20 and to the two wheel shafts 50, 52, the differential is configured to distribute the torque transmitted by the planetary gear train to the wheel shafts.

[0109] The planetary gear train 20, the differential 40 and the two wheel shafts 50, 52 are all coaxial, i.e. they all rotate around the rotation axis X50. In other words, the input gear 22,the ring gear 24, the sun gear 25, the planet carrier 27 and the differential housing 42 all rotate around the rotation axis X50.

[0110] In addition, the planetary gear train 20 is fitted concentrically around one of the two wheel shafts 50, 52, in the example around the wheel shaft 50. In other words, the input gear 22, and the sun gear 25 are traversed by the wheel shaft 50, i.e. they are mounted around the wheel shaft.

[0111] Preferably, the input shaft 22 is mounted on the housing 61 with a rolling bearing 55, such as a double row tapered roller bearing or a double row ball bearing. As an alternative, not shown, other roller bearing(s) can be used to mount the input shaft 22 on the housing 61.

[0112] Preferably, a rolling bearing 54, such as a four-point contact ball bearing is radially arranged between the sun gear 25 and input gear 22 and a rolling bearing 58, such as a needle roller bearing 58, is radially arranged between the sun gear 25 and the planet carrier 27. These bearings are not shown in Figure 20, for the clarity of the drawing. As an alternative, not shown, other roller bearing(s) can be arranged between the sun gear 25 and the input gear 22 and between the sun gear 25 and the planet carrier 27.

[0113] To allow the planetary gear train 20 to reach multiple gear ratios, the ring gear 24 of the planetary gear train 20 is axially moveable, along the rotation axis X50, so as to slide onto the planet gears 21, between a first position, in which the ring gear 24 engages with the housing 61 of the planetary gear train 20 so that a rotation of the ring gear 24 around the rotation axis X50 is locked relative to the housing, and a second position, in which the ring gear 24 engages with the input gear 22 so as to be driven in rotation around the rotation axis X50 by the input gear. In other words, in the first position, the ring gear 24 cannot rotate around the rotation axis X50 and, in the second position, the ring gear 24 is rotationally fixed relative to the input gear 22. Furthermore, the ring gear 24 always meshes with the planet gears 21, regardless of its position.

[0114] Hence, with the sun gear 25 engaging with the input gear 22, i.e. when the sun gear 25 is driven in rotation around the rotation axis X50 by the input gear 22, the planetary gear train 20 is operable between two configurations: a first configuration, or gear ratio, in which the ring gear 24 is in its first position, and a second configuration, or gear ratio, in which the ring gear is in its second position. The first configuration described here below correspond to the first configuration (‘Gear 1’) described here above and the second configuration described here below correspond to the third configuration (‘Gear 3’) described here above.

[0115] To allow shifting of the ring gear 24 between its first and second positions, the drive unit 5 comprises an actuating element 23, configured to move the ring gear along the rotation axis X50 between its first position and its second position. In the example, the actuating element 23 is ring-shaped and is fitted inside an external groove 80 of the ring gear 24, so that the actuating element 23 can push the ring gear 24 in one direction or the other along the rotation axis X50. As an alternative, not shown, the actuating element 23 is shaped differently and cooperates differently with the ring gear 24.

[0116] The actuating element 23 is a component producing a displacement of the ring gear 24 along the rotation axis X50 and is, for example, operated by a mechanical component, controlled by a driver of the vehicle 2 or automatically controlled, such as a shift fork, or operated by a pneumatic, hydraulic or electric component, such as a pneumatic actuator, a hydraulic cylinder or an electric motor.

[0117] In the example, to easily engage the ring gear 24 with the input gear 22 when the ring gear 24 is in its second position, the drive unit 5 comprises a first ring gear dog clutch 82, simplified on Figure 20, provided between the input gear 22 and the ring gear 24 and operable between a coupled configuration, in which the ring gear 24 is in the second position, and an uncoupled configuration, in which the ring gear 24 is disengaged from the input gear 22. For example, splines, or teeth, of the input gear 22 are engaged into corresponding grooves, or teeth, of the ring gear 24 when the first ring gear dog clutch 82 is in the coupled configuration and are disengaged from said corresponding grooves when the first ring gear dog clutch 82 is in the uncoupled configuration. Hence, the first ring gear dog clutch 82 is formed from the complementary splines and grooves of the input gear 22 and of the ring gear 24, which are engaged when the ring gear 24 is moved in its second position by the actuating element 23 and which are disengaged when the ring gear is not in its second position, i.e. is in its first position.

[0118] Preferably, to easily engage the ring gear 24 with the housing 61 when the ring gear 24 is in its first position, the drive unit 5 comprises a second ring gear dog clutch 84, simplified on Figure 20, provided between the housing 61 and the ring gear 24 and operable between a coupled configuration, in which the ring gear 24 is in the first position, and an uncoupled configuration, in which the ring gear 24 is disengaged from the housing 61. For example, splines, or teeth, of the housing 61 are engaged into corresponding grooves, or teeth, of the ring gear 24 when the second ring gear dog clutch 84 is in the coupled configuration and are disengaged from said corresponding grooves when the second ring gear dog clutch 84 is in the uncoupled configuration. Hence, the second ring gear dog clutch 84 is formed from thecomplementary splines and grooves of the housing 61 and of the ring gear 24, which are engaged when the ring gear 24 is moved in its first position by the actuating element 23 and which are disengaged when the ring gear is not in its first position, i.e. is in its second position.

[0119] Preferably, but optionally, the planetary gear train 20 can also reach a third configuration, corresponding to a third gear ratio, in which the ring gear 24 is in its second position, i.e. engaged with the input gear 22, and in which a rotation of the sun gear 25 around the rotation axis X50 is locked relative to the housing, for example by engaging the sun gear 25 with the housing 61. The third configuration described here below correspond to the second configuration (‘Gear 2’) described here above.

[0120] To this end, the drive unit 5 comprises a sun gear dog clutch 86, which is operable between a first configuration, in which the sun gear 25 engages with the input gear 22, and a second configuration, in which the sun gear 25 engages with the housing 61. In the example, the sun gear dog clutch 86 includes a control ring 11, axially moveable along the rotation axis X50 and rotationally coupled with the sun gear 25. In the example, the control ring 11 is fixedly mounted onto the input gear 22. An actuator, not shown, such as a fork, is configured to move the control ring 11 axially along the rotation axis X50.

[0121] When the control ring 11 moves the sun gear 25 so as to engage with the input gear 22, the sun gear 25 is driven by the input gear 22 and the planetary gear train 20 can reach its first and second configuration, depending on the position of the ring gear 24. When the control ring 11 moves the sun gear 25 so as to engage with the housing 61, the rotation of the sun gear 25 around the rotation axis X50 is locked and the planetary gear train 20 can reach its third configuration with the ring gear 24 in its second position.

[0122] As an alternative, not shown, the sun gear 25 is always engaged with the input gear 22 and the drive unit 5 does not comprise the sun gear dog clutch 86.

[0123] Preferably, but optionally, the planetary gear train 20 can also reach a neutral configuration, corresponding to a configuration in which the wheel shafts 50, 52 are disconnected from the electric motor 8, i.e. in which the input gear 22 of the planetary gear train 20 is disconnected from the input element 44 of the differential 40.

[0124] In the neutral configuration of the planetary gear train 20, the ring gear 24 is disengaged from the input gear 22 and from the housing 61, i.e. the ring gear 24 is in an intermediate position between its first and second position, and / or the sun gear 25 is disengaged from the input gear 22 and from the housing 61.

[0125] In the example, the neutral configuration is reached by operating the actuating element 23 and / or the control ring 11 to disengage the ring gear 24 and / or the sun gear 25 from the input gear 22 and from the housing 61. In the intermediate position of the ring gear 24, corresponding to a neutral position of the ring gear, i.e. when the ring gear 24 is disengaged from the input gear 22 and from the housing 61, the first ring gear dog clutch 82 and the second ring gear dog clutch 84 are in their uncoupled configurations. Similarly, when the sun gear 25 is disengaged from the input gear 22 and from the housing 61, the sun gear dog clutch 86 is operated in a third, or neutral, configuration, between the first and second configurations.

[0126] Practically speaking, it is sufficient to disengage only the ring gear 24 or the sun gear 25 from the input gear 22 and from the housing 61 to reach the neutral configuration of the planetary gear train 20. Indeed, when one of the ring gear 24 or sun gear 25 is disengaged while the other is engaged with the input gear 22, the disengaged component can rotate freely, and uncontrollably, around the rotation axis X50 so that no torque can be transmitted to the planet carrier 27. However, having both the ring gear 24 and the sun gear 25 disengaged from the input gear 22 and from the housing 61 allows to have a redundant neutral, improving safety, and decrease the number of spinning parts of the planetary gear train 20 in the neutral configuration, thus improving efficiency and reducing the number of components to lubricate.

[0127] Preferably, but optionally, the planetary gear train 20 can also reach a park configuration, corresponding to a configuration in which a rotation of the ring gear 24 around the rotation axis X50 is locked relative to the housing 61, i.e. in which the ring gear 24 is in its first position, and in which a rotation of the sun gear 25 around the rotation axis X50 is locked relative to the housing, i.e. in which the sun gear 25 is engaged with the housing 61. In this park configuration, as neither the ring gear 24 nor the sun gear 25 can rotate, the rotation of the planet carrier 27 is locked, therefore locking the differential 40 and the wheel shafts 50, 52. In other words, in the park configuration, a rotation of the wheel shafts 50, 52 around the rotation axis X50 is locked, preventing any movement of the vehicle 2. The park configuration is particularly advantageous to offer a mechanical park brake to the vehicle 2, which is independent of brakes of the vehicle.

[0128] As visible on Figure 20, the ring gear 24 is accessible through the housing 61 so as to be moveable with the actuating element 23.

[0129] Thanks to its conception, the drive unit 5 is particularly compact, facilitating its assembly in the axle 6 and reducing conflict with other parts of the axle 6, such as the suspension system. Firstly, having a ring gear 24 axially moveable saves axial space in thedrive unit 5, as there is therefore no need for an actuator located axially on a side of the planetary gear train to engage the ring gear with the input gear 22 or with the housing 61. Indeed, in comparison, the sun gear dog clutch 86 used to engage or disengage the sun gear 25 with the housing 61 or with the input gear 22 takes axial space. Secondly, as the planetary gear train 20 is fitted concentrically around the wheel shaft 50, the radial compactness of the drive unit 5 is improved. Thirdly, as the planet carrier 27 is fixed in rotation with the input element 44 of the differential 40, in the example by being the same component as the differential housing 42, there is no need for intermediate components between the differential 40 and the planetary gear train 20, improving the general compactness of the drive unit 5.

[0130] As an alternative, not shown, the drive unit 5 of Figure 20 comprises more than one electric motors 8, for example two electric motors. Preferably, with more than one electric motor, the transmission comprises a motor output shaft 80 for each electric motor 8, each motor output shaft 80 having a first pinion gear 32, and an intermediate shaft 37 for each electric motor, each intermediate shaft having a second pinion gear 36 and a third pinion gear 34, each second pinion gear 36 meshing with a first pinion gear 32, each third pinion gear 34 meshing with the input gear 22.

[0131] As an alternative, not shown, the drive unit 5 is used in an axle mounted on another type of vehicle than a heavy-duty vehicle, such as an automobile.

[0132] Example 1 : A wheel drive unit to be fitted on a chassis of a heavy-duty vehicle, said wheel drive unit comprising at least one wheel shaft, configured to drive a wheel in rotation, at least one electric motor, capable of generating a torque, a gearbox for transmitting the torque of the motor(s) to the wheel shaft(s),and a transmission system between the electric motor(s) and the gearbox. The transmission system consists of a gear train and a rotation axis of the electric motor is parallel to that of the wheel shaft(s).

[0133] Example 2: The wheel drive unit according to example 1, wherein the gear train comprises two or more reduction stages.

[0134] Example 3 : The wheel drive unit according to example 1 or 2, wherein the gear train includes a first pinion gear provided on a motor output shaft and an intermediate shaft comprising a second and a third pinion gear and wherein second pinion gear meshes with first pinion gear and third pinion gear meshes with an input gear of the gearbox.

[0135] Example 4: The wheel drive unit according to example 3, wherein second and third pinion gears are rotationally fixed one to the other.

[0136] Example 5: The wheel drive unit according to example 3 or 4, wherein second and third pinion gears are arranged side by side along intermediate shaft.

[0137] Example 6: The wheel drive unit according to any previous example, further comprising a second electric motor.

[0138] Example 7 : The wheel drive unit of any previous example, wherein the gearbox is a planetary gear train.

[0139] Example 8: The wheel drive unit according to previous example, wherein the gearbox includes a planet carrier that can be directly coupled in rotation with the wheel shaft.

[0140] Example 9 : The wheel drive unit according to any previous example, further comprising a high-speed retarder, e.g. a hydraulic retarder.

[0141] Example 10: The wheel drive unit according to any previous example, wherein the gearbox is fitted concentrically around the wheel shaft.

[0142] Example 11: The wheel drive unit according to any previous example, further comprising a suspension system to be attached to the vehicle chassis, wherein the suspension system includes at least one air bellow and wherein the electric motor is closer to the wheel shaft(s) rotation axis than the air bellow.

[0143] Example 12: The wheel drive unit according to any previous example, wherein the gearbox comprises at least two or three speed ratios and preferably a neutral configuration.

[0144] Example 13: An axle, comprising an axle body inside which is received a differential assembly through which two wheel shafts can be driven and at least one wheel drive unit according to any previous example, engaging with the differential assembly.

[0145] Example 14: The axle according to previous example, further comprising a second wheel drive unit, also engaging with the differential assembly.

[0146] Example 15: A heavy-duty vehicle comprising a wheel drive unit according to any one of examples 1 to 12 and / or an axle according to claim 13 or 14.

[0147] Example 16: The heavy-duty vehicle according to example 15, wherein the electric motor(s) of the wheel drive unit is located behind or in front of the differential assembly, that is respectively on the rear side or on the front side along the longitudinal direction of the vehicle.

[0148] Example 17: a drive unit, for a vehicle, the drive unit comprising: at least one electric motor, a transmission system,a planetary gear train, comprising a housing, an input gear, a ring gear, a sun gear, a planet carrier and planet gears, the planet gears meshing with the ring gear and the sun gear, the input gear meshing with the transmission system, a differential, having an input element fixed in rotation with the planet carrier, and two wheel shafts, extending along a rotation axis and configured to drive wheels of the vehicle.The transmission system is configured to transmit motor torque generated by the at least one electric motor to the input gear of the planetary gear train. The planet carrier of the planetary gear train is configured to transmit said motor torque to the input element of the differential. The differential is configured to distribute said motor torque to the two wheel shafts. The planetary gar train is fitted concentrically around one of the two wheel shafts, the planet carrier rotating around the rotation axis. The ring gear is axially moveable, along the rotation axis, so as to slide onto the planet gears, between a first position, in which the ring gear engages with the housing so that a rotation of the ring gear around the rotation axis is locked relative to the housing, and a second position, in which the ring gear engages with the input gear so as to be driven in rotation around the rotation axis by the input gear.

[0149] Example 18: the drive unit of example 17, wherein the planetary gear train is operable between two configurations: a first configuration, in which the ring gear is in its first position and in which the sun gear engages with the input gear so as to be driven in rotation by the input gear around the rotation axis, and a second configuration, in which the ring gear is in its second position and in which the sun gear engages with the input gear so as to be driven in rotation by the input gear around the rotation axis.

[0150] Example 19: the drive unit of example 18, wherein the planetary gear train is further operable in a neutral configuration, in which the ring gear and / or the sun gear are disengaged from the input gear and from the housing.

[0151] Example 20: the drive unit of any one of examples 17-18, wherein the planetary gear train is further operable in a third configuration, in which the ring gear is in its second position and in which a rotation of the sun gear around the rotation axis is locked relative to the housing.

[0152] Example 21 : the drive unit of example 20, wherein, in the third configuration of the planetary gear train, the rotation of the sun gear around the rotation axis is locked by engaging the sun gear with the housing.

[0153] Example 22: the drive unit of example 21, further comprising a sun gear dog clutch including a control ring, axially moveable along the rotation axis and rotationally coupled with the sun gear, wherein: in the first and third configurations of the planetary gear train, the control ring is moved along the rotation axis in a position in which the control ring engages the sun gear with the input gear; and in the second configuration of the planetary gear train, the control ring is moved along the rotation axis in a position in which the control ring engages the sun gear with the housing so that a rotation of the sun gear around the rotation axis is locked.

[0154] Example 23: the drive unit of example 22, further comprising a fork configured to axially move the control ring along the rotation axis.

[0155] Example 24: the drive unit of any one of examples 17-23, further comprising a ring gear dog clutch, provided between the input gear and the ring gear and operable between: a coupled configuration, in which the ring gear is in the second position; and an uncoupled configuration, in which the ring gear is disengaged from the input gear.

[0156] Example 25: the drive unit of any one of examples 17-24, further comprising an actuating element, configured to move the ring gear along the rotation axis between its first position and its second position.

[0157] Example 26: the drive unit of example 25, wherein the actuating element is ringshaped and fitted inside an external groove of the ring gear.

[0158] Example 27: the drive unit of any one of examples 17-26, wherein the differential comprises a differential housing, fixed to the planet carrier so that the differential housing is fixed in rotation with the planet carrier and fixed to the input element of the differential so that the differential housing is fixed in rotation with the input element.

[0159] Example 28: the drive unit of example 27, wherein the differential housing and the planet carrier are a single component.

[0160] Example 29: the drive unit of any one of examples 17-28, wherein the input element of the differential is a differential cross.

[0161] Example 30: the drive unit of any one of examples 17-29, wherein the transmission system consists of a gear train, the input gear meshing with the gear train.

[0162] Example 31 : the drive unit of example 30, wherein the gear train includes a motor output shaft for each electric motor, each motor output shaft having a first pinion gear, and an intermediate shaft for each electric motor, each intermediate shaft having a second pinion gear and a third pinion gear, each second pinion gear meshing with a first pinion gear, each third pinion gear meshing with the input gear.

[0163] Example 32: the drive unit of any one of examples 17-31, wherein the housing encapsulates the ring gear, the sun gear, the planet carrier and the planet gear.

[0164] Example 33: an axle, comprising an axle body and a drive unit, wherein the drive unit is according to any one of examples 17 to 32.

[0165] Example 34: the axle of example 33, wherein the axle body is the housing of the planetary gear train.

[0166] Example 35: the axle of any one of examples 33-34, further comprising a suspension system attached to the axle body.

[0167] Example 36: a heavy-duty vehicle comprising a drive unit according to any one of examples 17-32 or an axle according to any one of examples 33-35.

[0168] The terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It will be further understood that the terms "comprises," "comprising," "includes," and / or "including" when used herein specify the presence of stated features, integers, actions, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, actions, steps, operations, elements, components, and / or groups thereof.

[0169] It will be understood that, although the terms first, second, etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the present disclosure.

[0170] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element to another element as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

[0171] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0172] It is to be understood that the present disclosure is not limited to the aspects described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the present disclosure and appended claims. In the drawings and specification, there have been disclosed aspects for purposes of illustration only and not for purposes of limitation, the scope of the disclosure being set forth in the following claims.

Claims

ClaimsWhat is claimed is:

1. A drive unit (5), for a vehicle (2), the drive unit comprising: at least one electric motor (8), a transmission system, a planetary gear train (20), comprising a housing (61), an input gear (22), a ring gear (24), a sun gear (25), a planet carrier (27) and planet gears (21), the planet gears (21) meshing with the ring gear (24) and the sun gear (25), the input gear (22) meshing with the transmission system, a differential (40), having an input element (44) fixed in rotation with the planet carrier (27), and two wheel shafts (50, 52), extending along a rotation axis (X50) and configured to drive wheels (70, 72) of the vehicle (2), wherein the transmission system is configured to transmit motor torque generated by the at least one electric motor (8) to the input gear (22) of the planetary gear train (20), wherein the planet carrier (27) of the planetary gear train (20) is configured to transmit said motor torque to the input element (44) of the differential (40), wherein the differential (40) is configured to distribute said motor torque to the two wheel shafts (50, 52), wherein the planetary gar train (20) is fitted concentrically around one of the two wheel shafts (50, 52), the planet carrier (27) rotating around the rotation axis (X50), and wherein the ring gear (24) is axially moveable, along the rotation axis (X50), so as to slide onto the planet gears (21), between: a first position, in which the ring gear (24) engages with the housing (61) so that a rotation of the ring gear (24) around the rotation axis (X50) is locked relative to the housing, and a second position, in which the ring gear (24) engages with the input gear (22) so as to be driven in rotation around the rotation axis (X50) by the input gear.

2. The drive unit (5) of claim 1, wherein the planetary gear train (20) is operable between two configurations: a first configuration, in which the ring gear (24) is in its first position and in which the sun gear (25) engages with the input gear (22) so as to be driven in rotation by the input gear around the rotation axis (X50), and a second configuration, in which the ring gear (24) is in its second position and in which the sun gear (25) engages with the input gear (22) so as to be driven in rotation by the input gear around the rotation axis (X50).

3. The drive unit (5) of claim 2, wherein the planetary gear train (20) is further operable in a neutral configuration, in which the ring gear (24) and / or the sun gear (25) are disengaged from the input gear (22) and from the housing (61).

4. The drive unit (5) of any one of claims 2-3, wherein the planetary gear train (20) is further operable in a third configuration, in which the ring gear (24) is in its second position and in which a rotation of the sun gear (25) around the rotation axis (X50) is locked relative to the housing.

5. The drive unit (5) of claim 4, wherein, in the third configuration of the planetary gear train (20), the rotation of the sun gear (25) around the rotation axis (X50) is locked by engaging the sun gear (25) with the housing (61).

6. The drive unit (5) of claim 5, further comprising a sun gear dog clutch (86) including a control ring (11), axially moveable along the rotation axis (X50) and rotationally coupled with the sun gear (25), wherein: in the first and third configurations of the planetary gear train (20), the control ring (11) is moved along the rotation axis (X50) in a position in which the control ring engages the sun gear (25) with the input gear (22), and in the second configuration of the planetary gear train (20), the control ring (11) is moved along the rotation axis (X50) in a position in which the control ring engages the sun gear (25) with the housing (61) so that a rotation of the sun gear around the rotation axis (X50) is locked.

7. The drive unit (5) of claim 6, further comprising a fork configured to axially move the control ring (11) along the rotation axis (X50).

8. The drive unit (5) of any one of claims 1-7, further comprising a ring gear dog clutch (82), provided between the input gear (22) and the ring gear (24) and operable between: a coupled configuration, in which the ring gear (24) is in the second position, and an uncoupled configuration, in which the ring gear (24) is disengaged from the input gear (22).

9. The drive unit (5) of any one of claims 1-8, further comprising an actuating element (23), configured to move the ring gear along the rotation axis (X50) between its first position and its second position.

10. The drive unit (5) of claim 9, wherein the actuating element (23) is ring-shaped and fitted inside an external groove (80) of the ring gear (24).

11. The drive unit (5) of any one of claims 1-10, wherein the differential comprises a differential housing (42), fixed to the planet carrier (27) so that the differential housing is fixed in rotation with the planet carrier and fixed to the input element (44) of the differential (40) so that the differential housing is fixed in rotation with the input element.

12. The drive unit (5) of claim 11, wherein the differential housing (42) and the planet carrier (27) are a single component.

13. The drive unit (5) of any one of claims 1-12, wherein the input element (44) of the differential (40) is a differential cross.

14. The drive unit (5) of any one of claims 1-13, wherein the transmission system consists of a gear train, the input gear (22) meshing with the gear train.

15. The drive unit (5) of claim 14, wherein the gear train includes a motor output shaft (80) for each electric motor (8), each motor output shaft (80) having a first pinion gear (32), and an intermediate shaft (37) for each electric motor, each intermediate shaft having a secondpinion gear (36) and a third pinion gear (34), each second pinion gear (36) meshing with a first pinion gear (32), each third pinion gear (34) meshing with the input gear (22).

16. The drive unit (5) of any one of claims 1-15, wherein the housing (61) encapsulates the ring gear (24), the sun gear (25), the planet carrier (27) and the planet gear (21).

17. An axle (6), comprising an axle body (61) and a drive unit (5), wherein the drive unit is according to any one of claims 1 to 16.

18. The axle (6) of claim 17, wherein the axle body (61) is the housing (61) of the planetary gear train (20).

19. The axle (6) of any one of claims 17-18, further comprising a suspension system attached to the axle body (61).

20. A heavy-duty vehicle (2) comprising a drive unit (5) according to any one of claims 1-16 or an axle (6) according to any one of claims 17-19.

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