VEHICLE TRANSMISSION ARRANGEMENT AND METHOD FOR ASSEMBLING A VEHICLE TRANSMISSION ARRANGEMENT

Description

technical field

[0001] The invention relates to a transmission assembly, in particular for an electric or hybrid vehicle, as well as to its assembly method. Prior art

[0002] In document FR3086124 A1, a front bearing of an electric machine housing is mounted on a transmission casing. The mounting is radially external to the electric machine, and the mounting areas create an undesirable additional bulk. Compactness is a key design constraint for powertrains.

[0003] Furthermore, the front bearing, which also supports the stator, is rotatably mounted around the drive shaft via a bearing (see [ fig.2 The front bearing is therefore likely to absorb different stresses, these stresses being able to come from the rotation of the rotor (unbalance) or from the reduction gear depending on the architecture of the powertrain.

[0004] This document also discloses the definition of a cooling chamber with a radially external face of the front bearing and a radially internal face of the rear bearing. The cooling chamber is isolated by seals located in grooves formed in the front bearing on either side of the cooling chamber.

[0005] The invention aims to overcome the drawbacks of the prior art and to provide a compact transmission assembly, while ensuring good sealing between the electric motor and the transmission mechanism (gearbox), as well as at the cooling chamber. The invention also aims to facilitate the manufacture of this transmission assembly.

[0006] To this end, according to a first aspect of the invention, a transmission assembly for a vehicle is proposed, said transmission assembly comprising: an electrical machine comprising a rotor rotating about a first axis of rotation (X) and a stator arranged radially outside the rotor, a transmission device comprising a transmission shaft driven by the rotor and extending along the first axis of rotation X, an output shaft and a transmission mechanism arranged to transmit torque between the transmission shaft and the output shaft, a transmission housing defining an internal space within which at least part of the transmission mechanism is disposed, in particular a gear driven by the transmission shaft, a stator support having an internal housing extending along the first axis of rotation (X), the stator being fixed to the stator support inside this internal housing, a cooling chamber delimited in part by a radially external face of the stator support, the stator support comprising two annular grooves extending around the first axis of rotation (X) and arranged axially on either side of the cooling chamber, each annular groove housing an annular seal arranged to ensure the sealing of the cooling chamber.

[0007] According to the invention, the stator support is formed in a separate piece from the transmission housing and includes a fixing area fixed to the transmission housing; the fixing area being located closer to the first axis of rotation (X) than the stator.

[0008] In other words, the attachment area is located radially inside the stator.

[0009] Thus, the fixing area being located radially inside the stator, it is easily accessible before the introduction of the rotor and it does not generate additional bulk as when the fixing points are radially outside the stator.

[0010] In addition, having a stator support formed in a separate piece from the transmission housing makes it easier to machine the grooves, especially when the transmission housing has a portion radially covering the stator cooling chamber.

[0011] In addition, the transmission assembly is more modular and it is easier to customize the transmission assembly when changes need to be made to the electric machine alone.

[0012] The transmission assembly may also include one or more of the following characteristics: The stator is substantially cylindrical and has an inner diameter located at a first distance from the first axis of rotation X. The second distance separating the mounting area from the first axis of rotation X is less than the first distance. The transmission assembly also includes an outer electrical machine casing arranged radially outside the stator support; the cooling chamber is partially delimited by a radially internal face of the outer electrical machine casing. Preferably, the outer electrical machine casing has an overall cylindrical or frustoconical shape extending along the first axis of rotation X. Preferably, the cooling chamber has an overall cylindrical or frustoconical shape extending around the first axis of rotation X.Preferably, the cylindrical or frustoconical cooling chamber is delimited only by the outer casing of the electric motor and the stator support. In one embodiment, the outer casing of the electric motor is formed in a separate piece from the transmission housing, the piece in which the outer casing of the electric motor is formed thus forming an electric motor housing. In another embodiment, the outer casing of the electric motor is formed in a cylindrical or frustoconical portion of the transmission housing extending axially. In other words, the outer casing of the electric motor is formed as a single unit within the transmission housing. Optionally, a cover closes this cylindrical portion of the transmission housing. Preferably, a first bearing, in particular a first roller bearing, is radially interposed between the transmission housing and the transmission shaft.Preferably, the first bearing is housed in a wall of the transmission housing located axially on the side of the electric machine. Preferably, the first bearing is located outside the internal space of the transmission housing. The internal space is sealed and delimited by its walls and by the gaskets in its openings. Preferably, the first bearing is arranged radially inside the mounting area of ​​the stator support. In one embodiment, there is a plane perpendicular to the first axis of rotation X that intersects both the first bearing and the mounting area of ​​the stator support. Preferably, the stator support is arranged at a distance from the first bearing. Thus, by not being in contact with the first bearing, the stator support does not bear the forces from the shafts and gears of the transmission mechanism. Preferably, the stator support includes a flange arranged around the first axis of rotation X.Preferably, the flange extends in a plane perpendicular to the first axis of rotation X. Preferably, the stator support mounting area is located on this flange. The mounting area extends continuously or discontinuously around the first axis of rotation X. The stator support and the transmission housing have a common bonding interface; this common bonding interface is formed on a plane, preferably a plane perpendicular to the first axis of rotation X. This plane may optionally pass through the first bearing. In other words, there is a plane perpendicular to the first axis of rotation X passing through the common bonding interface and the first bearing. The stator support and the transmission housing are assembled against each other with fasteners such as screws or rivets. Thus, each screwing or riveting area forms a portion of the assembly area, which is then discontinuous around the first axis of rotation.Alternatively, the transmission housing and the stator support are welded to each other continuously or discontinuously around the first axis of rotation X. Preferably, the transmission housing has a connecting area that cooperates with the mounting area of ​​the stator support. This connecting area comprises a first group of holes, and the mounting area of ​​the stator support comprises a second group of holes arranged axially opposite the first group of holes. Fasteners such as screws secure the stator support to the transmission housing. Preferably, the holes in the first group of holes are blind holes, thus ensuring the gearbox is sealed. The fasteners are screws, and the holes in the first group of holes are tapped. Each fastener cooperates with a blind hole. The holes in the second group of holes may be through holes.Preferably, the holes in the first and second groups of holes extend axially. Preferably, the stator support includes a cylindrical portion into which the stator is fitted. Preferably, the stator has an outside diameter D and is supported by the stator support over its outside diameter D, in particular by shrink fitting or press fitting. Preferably, the transmission housing includes a first housing piece having a first portion with a connecting area cooperating with the mounting area of ​​the stator support, and a second portion radially covering a part of the external casing of the electrical machine such that there is a plane perpendicular to the first axis of rotation X that passes through the cooling chamber and intersects the second portion of the first housing piece.Thus, despite the presence of the second portion of the first housing piece above at least one groove, this groove can be easily machined before mounting the stator support onto the first housing piece. If applicable, the first and second portions of the transmission assembly each overlap a part of the transmission mechanism. In other words, the first and second portions of the first housing piece are therefore made as a single unit. Preferably, a differential is arranged, at least partially, within the second portion of the first housing piece. This housing and stator support design allows for adaptation to specific powertrain architectures, particularly those with a differential arranged to overlap the electric motor.Having a common transmission housing that integrates with the mounting area and also encloses all or part of the differential simplifies the design and assembly of the entire powertrain. A disconnect device capable of interrupting torque transmission between the electric motor and the output shaft can also be incorporated, at least partially, into the second portion of the first housing. The first housing has an opening through which the drive shaft passes. The first bearing is radially positioned between the first housing and the drive shaft. The transmission assembly is an electric drive axle or electric powertrain that can be mounted on either the front or rear axle of a vehicle. The electric motor can be synchronous or asynchronous, low-voltage or high-voltage.For example, the voltage of the electric machine is greater than or equal to 48V, or for example, greater than or equal to 72V. In one embodiment, the electric machine housing has a bell shape within which the stator support, the stator, and the rotor are arranged. Preferably, the electric machine housing or cover includes a bore within which a second bearing, in particular a roller bearing, is mounted. The drive shaft is rotatably mounted relative to the electric machine housing or cover via this second bearing. In one embodiment, the drive shaft comprises a first section and a second section butted together and mounted to rotate with each other about the first axis of rotation X, for example, by means of splines.Preferably, the first section is mounted rotationally fixed to the rotor about the first axis of rotation X, inside the rotor. In particular, the first section is fixed directly to the rotor. Preferably, the second section is mounted rotationally fixed to a gear of the transmission mechanism. The first section of the transmission shaft comprises a first end zone and a second end zone, the first end zone being mounted inside the first bearing and the second end zone being mounted inside the second bearing. Preferably, the transmission housing has a first centering surface extending around the first axis of rotation X. If applicable, the stator support is centered on this first centering surface. Preferably, the first centering surface is cylindrical, for example, in the shape of a right cylinder.The stator support includes a centering surface that cooperates with the first centering surface of the transmission housing. Preferably, the transmission housing has a second centering surface extending around the first axis of rotation (X). If applicable, the electric motor housing is centered on this second centering surface. Preferably, the second centering surface is cylindrical, for example, in the shape of a right cylinder. Preferably, the electric motor housing includes a centering surface that cooperates with the second centering surface of the transmission housing. In particular, the centering surface of the electric motor housing is located at the inlet of the bell housing, i.e., in the largest opening of the bell housing. In particular, the centering surface of the electric motor housing and the opening in the electric motor housing are axially positioned opposite each other.Preferably, the first centering surface of the transmission housing is radially oriented inward. Preferably, the second centering surface of the transmission housing is radially oriented outward. Preferably, the transmission housing includes a centering ring arranged around the first axis of rotation X and projecting axially toward the stator. Preferably, the first centering surface is located on the radially inner face of this centering ring. Preferably, the second centering surface is located on the radially outer face of this centering ring. In one embodiment, the second portion of the first part of the transmission housing covers the two grooves. Advantageously, the transmission mechanism includes a gearbox driven by the rotor of the electric machine via the transmission shaft.Preferably, the output shaft extends parallel to the transmission shaft along a second axis of rotation Y. In one embodiment, a third annular groove is formed in the stator support, and an annular seal is disposed in this groove to provide a seal between the stator support and the transmission housing. A cavity may be formed between this annular seal and the mounting area of ​​the stator support. If applicable, the third groove is arranged radially opposite the centering ring, inside the centering ring.

[0013] The invention also relates to a method for assembling a transmission assembly for a vehicle, said assembly method comprising the following steps: supplying an electric machine rotor and stator, supplying a transmission device comprising at least a portion of a transmission shaft suitable for being driven by the rotor and extending along a first axis of rotation X, an output shaft and a transmission mechanism arranged to transmit torque between the transmission shaft and the output shaft, as well as a transmission housing defining an internal space within which is disposed at least a portion of the transmission mechanism, in particular a pinion driven by the transmission shaft, supplying a stator support comprising a cooling chamber delimited in part by a radially external face of the stator support, the stator support comprising two annular grooves extending around the first axis of rotation (X) and arranged axially on either side of the cooling chamber,each annular groove able to accommodate an annular seal arranged to ensure the sealing of the cooling chamber, the stator support being formed in a separate piece from the transmission housing and the stator support comprising a mounting area, the transmission housing comprising a connecting area cooperating with the mounting area (140) of the stator support, , the assembly process further includes the following steps: mount the stator in the internal housing of the stator support (14) and fix the fixing area of ​​the stator support to the connecting area of ​​the transmission housing so that the rotor and the stator extend along the first axis of rotation X, the fixing area (140) being located closer to the first axis of rotation (X) than the stator (12), then mount the rotor, which is free to rotate about the first axis of rotation (X) and fixed in rotation to said at least a part of the transmission shaft (19), radially inside the stator. Brief description of the figures

[0014] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of several particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings. [ fig.1 ] There [ fig.1] is a schematic diagram of a transmission system corresponding to a first embodiment. fig.2 ] There [ fig.2 ] is a cross-sectional view of a transmission assembly according to the first embodiment. fig.3 ] There [ fig.3 ] is a zoomed cross-sectional view of the mounting area of ​​the transmission assembly of the [ fig.2 ]. fig.4 ] There [ fig.4 ] is an exploded isometric view of the transmission assembly of the [ fig.2 ]. fig.5 ] There [ fig.5 ] is a schematic diagram of a transmission assembly corresponding to a second embodiment. Description of the implementation methods

[0015] In the description and claims, the terms "external" and "internal," as well as the orientations "axial" and "radial," will be used to designate, according to the definitions given in the description, elements of the transmission assembly. By convention, the first axis of rotation X of the transmission assembly determines the "axial" orientation, and a "radial" orientation is directed orthogonally to the axial orientation, intersecting the first axis of rotation X. The "circumferential" orientation is directed orthogonally to the first axis of rotation and orthogonally to a radial direction. The terms "external" and "internal" are used to define the relative position of one element with respect to another, with reference to the first axis of rotation X of the transmission assembly; an element close to the first axis of rotation X is thus described as internal, as opposed to an external element located radially at the periphery.

[0016] The following is described in relation to the figures 1 to 4 a transmission system according to a first embodiment.

[0017] The basic diagram of the [ Fig. 1 [ ] presents in a simplified way a transmission assembly 1 for a vehicle. This transmission assembly 1 includes an electric machine 10 comprising a rotor 11 movable in rotation about a first axis of rotation X and a stator 12 arranged radially outside the rotor.

[0018] The transmission assembly 1 also includes a transmission device 28 comprising a transmission shaft 19 driven by the rotor 11 and extending along the first axis of rotation X, as well as an output shaft 29 and a transmission mechanism 25 arranged to transmit torque between the transmission shaft 19 and the output shaft 29.

[0019] A transmission housing 20 defines an internal space 200 within which is disposed at least part of the transmission mechanism 25, in particular a toothed wheel driven by the transmission shaft 19.

[0020] The transmission assembly 1 also includes a stator support 14 having an internal housing extending along the first axis of rotation X. The stator 12 is fixed to the stator support 14 inside this internal housing.

[0021] A cooling chamber 15 is partially delimited by a radially external face of the stator support 14. The stator support 14 includes two annular grooves 16 and 17 extending around the first axis of rotation X and arranged axially on either side of the cooling chamber 15. Each annular groove 16 and 17 can receive an annular seal arranged to ensure the sealing of the cooling chamber 15.

[0022] The stator support 14 is formed in a separate piece from the transmission housing 20 and includes a mounting area 140 fixed to the transmission housing 20.

[0023] The mounting area 140 is located closer to the first axis of rotation X than the stator 12. In other words, the mounting area 140 is located radially inside the stator. Thus, the mounting area 140 is easily accessible before the rotor is inserted and does not create additional bulk, unlike transmission assemblies where the corresponding mounting points are radially outside the stator.

[0024] The stator 12 is substantially cylindrical and has an internal diameter d located at a first distance r1 from the first axis of rotation X. The second distance r2 separating the fixing area 140 from the first axis of rotation X is therefore less than the first distance r1.

[0025] The transmission assembly also includes an external electrical machine casing 13 arranged radially outside the stator support 14.

[0026] The cooling chamber 15 is delimited in part by a radially internal face of the external electrical machine casing 13. Here, the cooling chamber 15 is delimited only by the external electrical machine casing 13 and by the stator support 14.

[0027] In this diagram, the external casing of the electrical machine 13 and the cooling chamber 15 have an overall cylindrical shape extending along the first axis of rotation X.

[0028] According to the first embodiment, the external casing of the electric machine 13 is formed in a separate part from the housing of the transmission casing 20. The part in which the external casing of the electric machine 13 is made here forms an electric machine casing.

[0029] On the [ fig.2 [ ], a first embodiment is represented in more detail. In this figure, we can see for example that the external casing of the electrical machine 13 and the cooling chamber 15 have an overall slightly frustoconical shape extending along the first axis of rotation X.

[0030] A first bearing housing 41 is radially interposed between the transmission housing 20 and the transmission shaft 19. This first bearing housing 41 is housed in a wall of the transmission housing located axially on the side of the electric machine.

[0031] The first bearing 41 is located outside the internal space 200 of the transmission housing 20. The internal space 200 is preferably sealed and is delimited by its walls as well as by the seals arranged in its openings.

[0032] The first bearing 41 is arranged radially within the mounting area 140 of the stator support 14. There is a plane perpendicular to the first axis of rotation X that intersects both the first bearing 41 and the mounting area of ​​the stator support. The stator support 14 is positioned at a distance from the first bearing 41. Thus, by not being in contact with the first bearing, the stator support does not bear the stresses from the shafts and gears of the transmission mechanism.

[0033] The stator support 14 and the transmission housing 20 have a common linkage interface; the common linkage interface being formed on a plane perpendicular to the first axis of rotation X. This plane passes through the first bearing 41.

[0034] As can be seen on the [ fig.2], the stator support 14 includes a flange 143 arranged around the first axis of rotation X and the fixing area 140 of the stator support is located on this flange 143. The flange 143 extends in a plane perpendicular to the first axis of rotation X.

[0035] The fixation area can extend around the first axis of rotation X continuously or discontinuously.

[0036] In the embodiment shown in the [ fig.2 The stator support 14 and the transmission housing 20 are assembled against each other with fasteners such as screws or rivets. Thus, each screwing or riveting area forms a portion of the assembly area, which is then discontinuous around the first axis of rotation.

[0037] Alternatively, the transmission housing and the stator support can be welded to each other continuously or discontinuously around the first axis of rotation X.

[0038] The transmission housing has a connecting area cooperating with the mounting area 140 of the stator support 14. The connecting area of ​​the transmission housing includes a first group of holes and the mounting area 140 of the stator support 14 includes a second group of holes arranged axially opposite the first group of holes, and a plurality of screws ensures the assembly of the stator support 14 and the transmission housing 20.

[0039] Advantageously, the holes in the first group of holes are blind holes. Thus, a seal with the transmission housing 20 is ensured at the mounting area 140.

[0040] The holes in the second group of holes can be through holes. The holes in the first and second groups of holes preferably extend axially.

[0041] The stator support 14 comprises a cylindrical portion into which the stator is fitted. The stator has an outside diameter D and is supported by the stator support 14 on its outside diameter D, notably by shrink fitting or press fitting.

[0042] You should refer to Figures 1 And 4 To view the transmission assembly as a whole. The transmission assembly is an electric powertrain that can be mounted on the front or rear axle of a car. The electric motor can be synchronous or asynchronous, low voltage or high voltage. For example, the voltage of the electric motor is greater than or equal to 48V, or greater than or equal to 72V.

[0043] Advantageously, the transmission mechanism includes a reducer 20 driven by the rotor 11 of the electric machine 10 via the transmission shaft 19.

[0044] The output shaft of the transmission device extends parallel to the transmission shaft 19 (and to the first axis of rotation X) along a second axis of rotation Y.

[0045] It can be seen that the transmission housing 20 comprises a first housing piece 21 having a first portion 21A with a connecting area cooperating with the mounting area 140 of the stator support 14, and a second portion 21B radially covering part of the outer casing of the electric machine 13. In other words, the first portion 21A and the second portion 21B of the first housing piece 21 are thus made as a single unit. There is a plane P perpendicular to the first axis of rotation X which passes through the cooling chamber 15 and intersects the second portion 21B of the first housing piece 21. Thus, despite the presence of the second portion of the first housing piece 21 above the grooves 16 and 17, it can be easily machined before mounting the stator support 14 onto the first housing piece 21.

[0046] A differential is arranged at least in part in the second portion 21B of the first housing piece 21. Having a common transmission housing piece cooperating with the mounting area and also enclosing the differential simplifies the design and assembly of the powertrain as a whole.

[0047] The first housing piece 21 has an opening 26 through which the transmission shaft 19 passes. The first bearing 41 is radially interposed between the first housing piece 21 and the transmission shaft 19.

[0048] In Fig. 2, we see that the electrical machine casing has a bell shape inside which are arranged the stator support 14, the stator 12, and the rotor 11.

[0049] The electric machine housing includes a bore inside which a second bearing 42 is mounted, the drive shaft being mounted to rotate relative to the electric machine housing via this second bearing.

[0050] The transmission shaft 19 comprises a first section 193 and a second section 194 joined together and mounted to rotate together around the first axis of rotation X, for example by means of splines 195. The first section 193 is mounted to rotate together with the rotor 11 with respect to the first axis of rotation X, inside the rotor 11.

[0051] Meanwhile, the second section is mounted to rotate securely around a toothed wheel of the transmission mechanism.

[0052] The first section 193 of the transmission shaft 19 comprises a first end zone 191 and a second end zone 192, the first end zone being mounted inside the first bearing 41 and the second end zone being mounted inside the second bearing 42.

[0053] On the [ fig.3 [ ], it can be seen that the transmission housing 20 has a first cylindrical centering surface 241 extending around the first axis of rotation X. The first centering surface 241 of the transmission housing 20 is radially oriented inwards. The stator support 14 includes a centering surface cooperating with the first centering surface 241 of the transmission housing.

[0054] The transmission housing 20 also has a second cylindrical centering surface 242 extending around the first axis of rotation X. The second centering surface 242 of the transmission housing 20 is radially turned outwards.

[0055] The electric motor housing includes a centering surface cooperating with the second centering surface 242 of the transmission housing 20. The centering surface of the electric motor housing is located at the inlet of the bell housing, that is, in the largest opening of the bell housing. The centering surface of the electric motor housing and the hole 43 of the electric motor housing are arranged axially opposite each other.

[0056] The transmission housing 20 includes a centering ring 24 arranged around the first axis of rotation X and projecting axially towards the stator 12. The first centering surface 241 is disposed on the radially inner face of this centering ring 24. The second centering surface 242 is disposed on the radially outer face of this centering ring 24.

[0057] In the first embodiment, a third annular groove 51 is formed in the stator support 14, and an annular seal is disposed in this groove to ensure a seal between the stator support 14 and the transmission housing 20. A cavity can be formed between this annular seal and the mounting area of ​​the stator support. Here, the third groove is arranged radially opposite the centering ring 24, inside the centering ring 24.

[0058] The assembly process for the transmission unit includes the following steps: supply the rotor 11 and the stator 12 of the electric machine, supply the transmission device 28 comprising at least a portion of the transmission shaft 19 suitable for being driven by the rotor 11 and extending along a first axis of rotation X, an output shaft 29 and a transmission mechanism 25 arranged to transmit torque between said at least a portion of the transmission shaft 19 and the output shaft 29, as well as a transmission housing 20 defining an internal space 200 within which is disposed at least a portion of the transmission mechanism 25, in particular a pinion driven by the transmission shaft 19, supply a stator support 14 comprising a cooling chamber 15 delimited in part by a radially external face of the stator support 14, the stator support 14 comprising two annular grooves 16,17 extending around the first axis of rotation X and arranged axially on either side of the cooling chamber 15, each annular groove 16, 17 being able to accommodate an annular seal arranged to ensure the sealing of the cooling chamber 15, the stator support 14 being formed in a separate piece from the transmission housing 20 and the stator support 14 comprising a mounting area 140, the transmission housing comprising a connecting area cooperating with the mounting area 140 of the stator support 14. ,

[0059] The assembly process also includes the following steps: mount the stator in the internal housing of the stator support 14 and fix the fixing area of ​​the stator support on the connecting area of ​​the transmission housing so that the rotor and the stator extend along the first axis of rotation X, the fixing area 140 being located closer to the first axis of rotation X than the stator 12, then mount the rotor, which is free to rotate about the first axis of rotation X and fixed in rotation to said at least a part of the transmission shaft 19, radially inside the stator.

[0060] As mentioned previously, the rotor 11 is first secured with a first section 193 of the transmission shaft 19 before being joined to a second section 194 of the transmission shaft previously integrated into the transmission device 28.

[0061] The rotational rigid connection between the two shaft sections can be ensured by complementary splines or by means of a joining piece such as a coupling sleeve.

[0062] In the second embodiment shown on the [ fig.5 The external casing of the electrical machine is formed in a cylindrical or frustoconical portion of the transmission housing 20 extending axially. In other words, the external casing of the electrical machine is formed as a single piece within the transmission housing 20.

[0063] If necessary, a cover closes this cylindrical portion of the transmission housing and the second bearing housing is then mounted between the first section of the transmission shaft and the cover to mount these two moving elements in rotation relative to each other with respect to the first axis of rotation X.

Claims

1. Transmission assembly (1) for a vehicle, said transmission assembly comprising: - an electric machine (10) comprising a rotor (11) rotatable about a first axis of rotation (X) and a stator (12) arranged radially outside the rotor, - a transmission device (28) comprising a transmission shaft (19) driven by the rotor (11) and extending along the first axis of rotation X, an output shaft (29) and a transmission mechanism (25) arranged so as to transmit the torque between the transmission shaft (19) and the output shaft (29), - a transmission casing (20) defining an internal space (200) inside which is arranged at least part of the transmission mechanism (25), in particular a toothed wheel driven by the transmission shaft (19), - a stator support (14) having an internal housing extending along the first axis of rotation (X), the stator (12) being attached to the stator support (14) inside this internal housing, - a cooling chamber (15) delimited in part by a radially external face of the stator support (14), the stator support (14) comprising two annular grooves (16, 17) extending around the first axis of rotation (X) and arranged axially on either side of the cooling chamber (15), each annular groove (16, 17) accommodating an annular seal arranged so as to ensure sealing of the cooling chamber (15), characterized in that the stator support (14) is formed in a part separate from the transmission casing (20) and comprises an attachment zone (140) attached to the transmission casing; the attachment zone (140) being situated closer to the first axis of rotation (X) than the stator (12).

2. Transmission assembly (1) according to Claim 1, also comprising an external electric machine envelope (13) arranged radially outside the stator support (14); the cooling chamber (15) being delimited in part by a radially internal face of the external electric machine envelope (13).

3. Transmission assembly (1) according to Claim 2, wherein the external electric machine envelope is formed in a part separate from the transmission casing, the part in which the external electric machine envelope is formed thus forming an electric machine casing.

4. Transmission assembly (1) according to Claim 2, wherein the external electric machine envelope is formed in a cylindrical or frustoconical portion of the transmission casing extending axially.

5. Transmission assembly (1) according to one of the preceding claims, wherein a first bearing (41), in particular a first rolling bearing, is interposed radially between the transmission casing (20) and the transmission shaft (19).

6. Transmission assembly (1) according to the preceding claim, wherein the stator support is arranged at a distance from the first bearing (41).

7. Transmission assembly (1) according to one of the preceding claims, wherein the stator support (14) comprises a flange (143) arranged around the first axis of rotation (X), the attachment zone (140) of the stator support being situated on this flange (143).

8. Transmission assembly (1) according to one of the preceding claims, wherein the stator support (14) and the transmission casing are assembled one against the other with assembly elements such as screws or rivets.

9. Transmission assembly (1) according to the preceding claim, wherein the transmission casing comprises a connection zone cooperating with the attachment zone (140) of the stator support (14), the connection zone comprising a first group of holes and the attachment zone (140) of the stator support (14) comprising a second group of holes arranged axially opposite the first group of holes, and the assembly elements such as screws ensure the assembly of the stator support and the transmission casing, the holes of the first group of holes being blind holes.

10. Transmission assembly (1) according to one of the preceding claims, wherein the transmission casing (20) comprises a first casing part (21) having: - a first portion (21A) provided with the connection zone cooperating with the attachment zone (140) of the stator support (14), and - a second portion (21B) radially covering part of the external electric machine envelope (13) so that there is a plane (P) perpendicular to the first axis of rotation (X) which passes through the cooling chamber (15) and which intersects the second portion (21B) of the first casing part (21); the first portion (21A) and the second portion (21B) of the transmission assembly each covering part of the transmission mechanism (25).

11. Transmission assembly (1) according to the preceding claim, wherein a differential is arranged at least in part in the second portion (21B) of the first casing part (21) .

12. Transmission assembly (1) according to Claim 3, wherein the transmission casing has a first centring surface (241) extending around the first axis of rotation (X), the stator support (14) comprising a centring surface cooperating with the first centring surface (241) of the transmission casing; the transmission casing having a second centring surface (242) extending around the first axis of rotation (X); the electric machine casing (18) comprising a centring surface cooperating with the second centring surface (242) of the transmission casing.

13. Transmission assembly (1) according to the preceding claim, wherein the transmission casing comprises a centring ring (24) arranged around the first axis of rotation X and projecting axially toward the stator; the first centring surface (241) being arranged on the radially internal face of this centring ring (24); and the second centring surface (242) being arranged on the radially external face of this centring ring (24).

14. Method for assembling a transmission assembly (1) for a vehicle, said assembly method comprising the following steps: - providing a rotor (11) and a stator (12) of an electric machine, - providing a transmission device (28) comprising at least part of a transmission shaft (19) able to be driven by the rotor (11) and extending along a first axis of rotation X, an output shaft (29) and a transmission mechanism (25) arranged so as to transmit the torque between the transmission shaft (19) and the output shaft (29), and a transmission casing (20) defining an internal space (200) inside which is arranged at least part of the transmission mechanism (25), in particular a pinion driven by the transmission shaft (19), - providing a stator support (14) comprising a cooling chamber (15) delimited in part by a radially external face of the stator support (14), the stator support (14) comprising two annular grooves (16, 17) extending around the first axis of rotation (X) and arranged axially on either side of the cooling chamber (15), each annular groove (16, 17) being able to accommodate an annular seal arranged so as to ensure sealing of the cooling chamber (15), the stator support (14) being formed in a part separate from the transmission casing (20) and the stator support (14) comprising an attachment zone (140), the transmission casing comprising a connection zone cooperating with the attachment zone (140) of the stator support (14), the assembly method further comprising the following steps: - mounting the stator in the internal housing of the stator support (14) and attaching the attachment zone of the stator support to the connection zone of the transmission casing in such a way that the rotor and the stator extend along the first axis of rotation X, the attachment zone (140) being situated closer to the first axis of rotation (X) than the stator (12), - then mounting the rotor, which is rotatable about the first axis of rotation (X) and coupled in rotation with the transmission shaft (19), radially inside the stator.