INTERNALLY LUBRICATED TRANSMISSION MECHANISM AND ASSOCIATED ELECTRIC PROPULSION ASSEMBLY

Abstract

The invention relates to an internally lubricated transmission mechanism (M), comprising: - a speed reduction device including at least a first transmission shaft (10) extending along a first axis of rotation (X1) and coaxially carrying a first gear (11), - a hollow-shaped housing (40a, 40b) including a base (61) and a peripheral wall (62) formed of the same material as the base, the peripheral wall partially surrounding the speed reduction device, - a lubricant receiving and distribution manifold (50) disposed in the housing (60) between the peripheral wall (62) and the first axis of rotation (X), characterized in that the manifold (50) includes at least a bottom (52), an outer rim (58) and an additional collection device (60) connected to the outer rim, the additional collection device (60) being supported on the peripheral wall and / or the base of the housing. (Fig. 2)

Description

Title of the invention: INTERNALLY LUBRICATED TRANSMISSION MECHANISM AND ASSOCIATED ELECTRIC PROPULSION ASSEMBLY Technical field of the invention

[0001] The invention relates to the internal lubrication, for example by splash lubrication, of the components of a transmission mechanism, and in particular of a transmission mechanism comprising a speed reduction device. Prior art

[0002] To lubricate the components of a transmission mechanism, and in particular the rotating guide bearings and gears of such a mechanism, it is known to place the moving components of the mechanism inside a housing containing lubricating oil. However, the moving components, for example the transmission shafts supporting the pinion and gear of a gear, are not completely immersed in the oil. It is the movement of the transmission mechanism that, by splashing, mixes the oil and projects it throughout the entire internal volume of the housing, to ensure the desired lubrication of the entire mechanism, including the non-immersed parts.

[0003] This type of transmission mechanism generally includes a so-called "passive" lubrication device, i.e., one without a pump, in which a ramp is formed within the casing to facilitate the upward flow of lubricant from the bottom of the casing, thus dispersing the lubricant in different areas of the speed reduction device. One or more fluid collectors are also placed in the casing to collect oil splashes. The fluid collector then redistributes the fluid to different locations within the casing by means of supply lines that channel the fluid flow to the guide bearings and gears.

[0004] Document DE102010030035 Al discloses such a transmission mechanism. This document shows two fluid collectors that recover oil spray within the transmission mechanism. However, the arrangement and shape of the fluid collectors do not allow for the recovery of a large quantity of fluid sprayed into the housing. The amount of fluid recovered also depends on the rotational speed of the gears that spray the oil. There is a need to improve the efficiency of such a transmission mechanism.

[0005] Guide bearings, for example ball bearings, must be continuously lubricated and are generally permeated by a flow of lubricating fluid. When insufficiently lubricated, guide bearings are at risk of overheating. The solution proposed in document DE102010030035 Al does not guarantee sufficient fluid flow within the guide bearing. Description of the invention

[0006] The invention aims to remedy the disadvantages of the prior art and to propose a transmission mechanism combining good lubrication of the guide bearings and low energy consumption at high speed.

[0007] To this end, according to a first aspect of the invention, an internally lubricated transmission mechanism is proposed, comprising:

[0008] - a speed reduction device comprising at least a first shaft of transmission extending along a first axis of rotation XI and coaxially carrying a first gear,

[0009] - a hollow-shaped housing comprising a base and a peripheral wall of material with the base, the peripheral wall partially surrounding the speed reduction device,

[0010] - a lubricant receiving and distribution manifold disposed in the crankcase between the peripheral wall and the first axis of rotation XI,

[0011] in which the lubricant receiving and distribution manifold comprises at least a base, an outer perimeter and an additional collection device linked to the outer perimeter, the additional collection device being supported on the peripheral wall and / or the base of the housing.

[0012] This transmission mechanism with its lubricant receiving and distribution manifold equipped with its additional collection device has the advantage of recovering and distributing a significant quantity of lubricant present within the speed reduction device, while retaining the principle of passive lubrication.

[0013] The additional collection device contributes to lubricant recovery by being positioned on the upper part of the collector. The lubricant is projected by the first gear towards the peripheral wall of the housing. The lubricant is then stopped by the additional collection device and finally falls back into the collector by gravity. The collector occupies a central position within the speed reducer, which allows it to receive all the lubricant spray from the first gear as well as from other gears also present within the speed reduction device.

[0014] Preferably, the lubricant receiving and distribution manifold is arranged axially, along the first axis of rotation XI, between the housing base and the first gear, the first gear rotating about the first axis of rotation XI in a preferred direction, the additional collection device facing the The first gear is oriented to receive the lubricant projected by the teeth. Thanks to the orientation of the helical teeth, the lubricant is projected towards the lubricant receiving and distribution manifold.

[0015] Advantageously, the outer periphery of the first gear can extend radially beyond the outer perimeter of the lubricant receiving and distribution manifold. This facilitates lubricant recovery.

[0016] According to one aspect of the invention, the transmission mechanism comprises a first guide bearing supporting the first transmission shaft relative to the casing, the first guide bearing being inserted into a first cylindrical housing provided in the casing, the lubricant receiving and distribution manifold comprising a lubricant outlet line opening towards the cylindrical housing.

[0017] Preferably, the additional collection device is attached to the outer perimeter or made of material with the outer perimeter, the additional collection device comprising a collection wall which forms the junction between the lubricant receiving and distribution manifold and the housing.

[0018] For example, the end of the collection wall in contact with the housing includes a geometric shape that follows the internal shape of the housing, for example a curvilinear shape.

[0019] According to a variant of the invention, the additional collection device is an added part comprising the collection wall and a reinforcement wall disposed on one of the edges of the collection wall, the reinforcement wall includes a mounting surface bearing against the outer perimeter of the lubricant receiving and distribution collector.

[0020] The additional collection device can be made of stamped metal or injected plastic.

[0021] Advantageously, the reinforcing wall may include snap-on tabs which extend towards the lubricant receiving and distribution manifold, the additional collection device being snapped onto the outer perimeter.

[0022] According to another embodiment of the invention, the additional collection device is formed from a single piece of material with an outer rim, the lubricant receiving and distribution manifold comprising a flexible zone connecting the outer rim to the collection wall, the flexible zone being created by localized material necking or by localized material removal. The flexible zone allows for dimensional tolerances and ensures contact with the peripheral wall or the base of the housing under all circumstances.

[0023] According to another variant of the invention, the additional collection device is a sealing gasket attached to the outer perimeter.

[0024] For example, the sealing gasket may include a sealing lip that connects the lubricant receiving and distribution manifold to the housing. Advantageously, the sealing lip acts as a collection wall. The sealing lip can deform elastically. The sealing gasket allows for dimensional tolerances and ensures contact with the peripheral wall or the base of the housing under all circumstances.

[0025] For example, the sealing gasket can be overmolded on the outer perimeter of the lubricant receiving and distribution manifold.

[0026] For example, the sealing gasket can be inserted into a groove formed on the outer perimeter of the lubricant receiving and distribution manifold.

[0027] According to one aspect of the invention, the housing comprises, on the inner face of the peripheral wall, at least one drip edge located directly above the lubricant receiving and distribution manifold. The drip edge is in the form of a material protrusion, and the additional collection device rests upon the drip edge. For example, the profile of the drip edge may be linear and oriented in the direction of the housing's demolding process when the housing is cast. In another example, the drip edge may be cone-shaped. In yet another example, the drip edge may be machined directly into the housing. The drip edge allows for the recovery of more lubricant within the manifold. The lubricant that runs down the peripheral wall preferentially returns to the manifold by following the shape of the drip edge rather than returning directly to the bottom of the gearbox.

[0028] According to one aspect of the invention, the transmission mechanism comprises a breather supported by the housing, the inner end of the breather opening into a cavity formed in the housing, the collection wall of the additional collection device at least partially covering the inlet of the cavity. For example, the inlet of the cavity opens into the base of the main housing. The breather is configured in particular to prevent the pressure in the space enclosed by the housing from becoming too high relative to the pressure outside the space. The collection wall prevents the direct projection of lubricant into the cavity and onto the breather itself. For the purposes of the invention, the term "cover" means both covering with contact and covering without contact.

[0029] The transmission mechanism according to the invention may have one or more of the characteristics described below, either combined or taken independently of each other:

[0030] - the first toothed wheel rotates around the first axis of rotation in one direction The preferred configuration is the lubricant receiving and distribution manifold, positioned to face the first gear so as to receive the lubricant sprayed by the teeth. According to For example, the preferred direction of rotation of the first toothed wheel is the one that allows the motor vehicle to move forward.

[0031] - the peripheral wall of the housing comprises a cylindrical surface coaxial with the first axis of rotation which partially surrounds the outer periphery of the first gear.

[0032] - a closing cover is attached to the main cover so as to form a enclosed chamber around the speed reduction device, the lubricant receiving and distribution manifold being held in position partially either by the main casing or by the closing casing.

[0033] - a closing cover is attached to the main cover so as to form a enclosed chamber around the speed reduction device, the lubricant receiving and distribution manifold being held in position partly by the main housing and partly by the closing housing.

[0034] - the closing housing has on its inner face at least one drip edge located at the vertical alignment of the lubricant receiving and distribution manifold.

[0035] - the main casing has on its inner face at least one drip edge located vertically of the lubricant receiving and distribution manifold.

[0036] The invention also relates, according to another of its aspects, to an electric propulsion assembly comprising an electric machine and a transmission mechanism incorporating all or part of the characteristics mentioned above, the speed reduction system comprising a second transmission shaft guided in rotation around a second axis of rotation X2 by a second guide bearing, and a third transmission shaft guided in rotation around a third axis of rotation X3 by a third guide bearing, one of the transmission shafts chosen from the first, second and third transmission shafts is fixed in rotation to the rotor shaft of the electric machine.

[0037] Preferably, a first guide bearing supports the first transmission shaft relative to the housing, the first guide bearing being inserted into a first cylindrical housing provided in the housing, the second guide bearing being inserted into a second cylindrical housing provided in the housing, the third guide bearing being inserted into a third cylindrical housing provided in the housing, the lubricant receiving and distribution manifold comprising lubricant outlet lines opening towards the cylindrical housing of at least two guide bearings chosen from the first, second and third guide bearings.

[0038] Other features and advantages of the invention are highlighted by the following description of non-limiting examples of implementation of the different aspects of the invention. brief description of the figures

[0039] Other features and advantages of the invention will become apparent from the following description, with reference to the accompanying figures, which illustrate: [Fig.l]: a partial front view of a transmission mechanism according to a first embodiment, shown without the closing casing.

[0040] [Fig.2]: a cross-sectional view of the transmission mechanism of the [Fig.1].

[0041] [Fig.3]: a cross-sectional view of a transmission mechanism according to a second mode of realization.

[0042] [Fig.4]: a partial cross-sectional view of a transmission mechanism according to a third embodiment.

[0043] [Fig.5]: a partial cross-sectional view of a transmission mechanism according to a fourth embodiment. DETAILED description of a method of implementation

[0044] Figures 1 and 2 show an internally lubricated transmission mechanism M according to a first embodiment of the invention. This transmission mechanism M is integrated within an electric propulsion unit 1 of a vehicle, in particular an electric motor vehicle, or a secondary powertrain. For example, it could be a secondary electric powertrain of a hybrid vehicle, in particular intended for the rear axle of the vehicle.

[0045] In the description and claims, the terms "external" and "internal," as well as the orientations "axial" and "radial," shall be used to designate, according to the definitions given in the description, elements of the transmission system. By convention, the "axial" orientation relates to the reference axes X, Y, or Z or to directions parallel to these axes, and the "radial" orientation is directed orthogonally to the reference axes X, Y, and Z. A "radially internal" element is located closer to the reference axis than a "radially external" element.

[0046] The terms "upper", "lower", "top", "bottom", and "bottom" should be taken into consideration when viewing the transmission mechanism M in a position / incline similar to its position when mounted on a vehicle parked horizontally.

[0047] The electric propulsion assembly 1 includes an electric machine 60 and the transmission mechanism M which transmits the torque from the electric machine to the wheels of the electric or hybrid vehicle.

[0048] The electric machine 60 can be, for example, an induction electric motor, comprising a rotor and a stator, electrically supplied with three-phase alternating current by accumulator batteries via a current converter (not represented in [Fig.1]. The electrical machine may be of another type, for example axial flux.

[0049] The electric machine 60 is held on a housing 40a, 40b. The housing generally consists of a main housing 40a supporting the electric machine and a closing housing 40b bearing against the main housing 40a, at a joint 48, to seal a cavity delimited by the main housing 40a and the closing housing 40b. The electric machine drives an input shaft of the transmission mechanism M which enters the main housing 40a.

[0050] The transmission mechanism M includes a speed reduction device R comprising a first transmission shaft 10 extending along a first axis of rotation XI and coaxially carrying a first gear 11. A first guide bearing 100a supports the first transmission shaft 10 relative to the main housing 40a, the first guide bearing 100a being inserted into a first cylindrical housing 41 formed in the main housing 40a. Another first guide bearing 100b supports the first transmission shaft 10 relative to the closing housing 40b.

[0051] The first transmission shaft 10 mentioned above corresponds to the intermediate shaft of the speed reduction device R which will be described below in the different embodiments.

[0052] The speed reduction device R includes a second transmission shaft 20 corresponding to the input shaft of the transmission mechanism M intended to be driven by the electric machine. This input shaft of the transmission mechanism M is rotationally fixed to the motor shaft of the electric machine. This second transmission shaft 20 is guided in rotation about a second axis of rotation X2 by a second guide bearing 200a. The second guide bearing 200a supports the second transmission shaft 20 relative to the main housing 40a, the second guide bearing 200a being inserted into a second cylindrical housing 42 provided in the main housing 40a. Another second guide bearing 200b supports the second transmission shaft 20 relative to the closing housing 40b.

[0053] The speed reduction device R also includes a third transmission shaft 30 guided in rotation about a third axis of rotation X3 by a third guide bearing 300a, 300b. The third transmission shaft 30, also called the output shaft of the transmission mechanism M, includes a torque output gear 31. The third transmission shaft 30 further includes a fixed rotational link with a planet carrier of a differential 32, or constitutes the planet carrier of the differential 32. The differential 32 may be open or limited-slip, depending on the desired properties.

[0054] The first transmission shaft 10 supports the first gear 11 and an intermediate pinion 12. The first gear 11 forms a first reduction stage with the first pinion 21 of the second transmission shaft 20, and the intermediate pinion 12 forms a second reduction stage with the torque output gear 31 of the third transmission shaft 30.

[0055] The first, second and third axes of rotation XI, X2, X3 are parallel to each other.

[0056] The hollow-shaped main housing 40a comprises a base 45 and a peripheral wall 46 formed from the same material as the base, the peripheral wall partially surrounding the speed reduction device R. The peripheral wall 46 partially surrounds the first gear 11. In this example, the speed reducer comprises a single speed ratio.

[0057] Figure 1 is a simplified front view of the transmission mechanism M according to the first embodiment of the invention, shown without its closing casing so as to visualize the interior of the speed reduction device. Figure 2 partially shows the same transmission mechanism M in cross-section.

[0058] In [Fig. 1], the transmission mechanism M is shown in a position corresponding to its position when mounted in a vehicle parked on a horizontal plane. It comprises a relatively low part and a relatively high part.

[0059] In order to improve lubrication within the transmission mechanism M, the latter includes, in particular, a lubrication device comprising:

[0060] - a lubricant receiving and distribution manifold 50 comprising at a base 52 and an outer perimeter 58, the lubricant receiving and distribution collector 50 being disposed in the main casing 40a between the peripheral wall 46 and the first axis of rotation XI;

[0061] - an additional collection device 60 linked to the outer perimeter 58, the device of additional collection 60 being supported on the peripheral wall 46 of the casing; and

[0062] - the first gear 11 movable in rotation about the first axis of rotation XI which projects lubricant from the external teeth towards the collector.

[0063] The lubricant receiving and distribution manifold 50 is arranged axially, along the first axis of rotation XI, between the base 45 of the main housing 40a and the first toothed wheel 11, the first toothed wheel 11 rotating around the first axis of rotation XI in a preferred direction, the lubricant receiving and distribution manifold 50 facing the first toothed wheel 11 so as to receive the lubricant projected by the teeth.

[0064] The bottom 52 and the outer perimeter 58 form a collection reservoir arranged next to the first toothed wheel 11.

[0065] The additional collection device 60 includes a collection wall 61 which connects the lubricant receiving and distribution manifold 50 to the main housing 40a. The end of the collection wall 61 in contact with the housing comprises a geometric shape that conforms to the inner shape of the housing, so as to form a partial seal behind the additional collection device 60.

[0066] In this example, the collector 50 is held in position partially by the main housing 40a, using fixing tabs not shown.

[0067] Figure 2 illustrates the lubrication of this transmission mechanism M, which is partially achieved by the projection of lubricant (represented by the black arrows), for example oil 80, conveyed by the first gear 11. The oil from the bottom of the speed reduction device R is raised upwards by means of the rotation of the first gear 11, and is then projected towards the peripheral wall 46 of the housing in the direction of the manifold 50. Since the outer periphery 1la of the first gear 11 extends radially beyond the outer circumference 58 of the lubricant receiving and distribution manifold 50, the lubricant can more easily fall back into it.

[0068] The first gear 11 rotates about the first axis of rotation XI in a preferred direction. In this example, the preferred direction of rotation of the first gear is that which allows the motor vehicle to move forward. The lubricant receiving and distribution manifold 50, facing the first gear 11, receives only a portion of the lubricant sprayed by the teeth. Another portion of the lubricant is sprayed onto the peripheral wall 46 and onto the collection wall 61 of the additional collection device 60.

[0069] The lubricant 80 runs down the collection wall 61 and falls back by gravity into the collector 50.

[0070] As illustrated in [Fig.2], the lubricant is then distributed to different areas of the transmission mechanism M. The manifold 50 has a plurality of holes or channels 53 allowing streams of lubricating oil to flow onto different areas of the speed reduction device R.

[0071] The oil 80 collected by the lubricant receiving and distribution manifold 50 is then partially directed into a groove 49 formed in the main housing 40a in order to be conveyed to the guide bearing 100a, as illustrated by the arrows in [Fig. 2]. The groove 49 opens into the upper part of the first cylindrical housing 4L

[0072] The lubricating oil flow is thus directed towards the guide bearing 100a to an available space between the bottom of the first cylindrical housing 41 and the rear face of the guide bearing 100a. By gravity, the lubricating fluid flows down the groove 49 and then enters the cavity formed by the first housing cylindrical 41 of the main housing 40a before exiting through the lower part of the first guide bearing 100a.

[0073] As illustrated in [Fig. 2], the additional collection device 60 is attached to the outer edge 58 of the lubricant receiving and distribution manifold 50. The additional collection device 60 is made of injection-molded plastic. The additional collection device is an added component comprising the collection wall 61 and a reinforcing wall 62 located on one edge of the collection wall. For added stability, the reinforcing wall 62 includes a bearing surface 62a that rests against the outer edge 58 of the lubricant receiving and distribution manifold.

[0074] The reinforcing wall 62 includes snap-on tabs 63 which extend towards the lubricant receiving and distribution manifold 50, the additional collection device 60 being snapped onto the outer perimeter 58.

[0075] Stiffening ribs are provided between the reinforcement wall and the collection wall.

[0076] Alternatively, the additional collection device 60 can be made of stamped metal.

[0077] The main housing 40a has on the inner face of the peripheral wall 46 a drip edge 90 located directly above the collector 50, the drip edge 90 taking the form of a protrusion of material. The drip edge 90 allows for the recovery of more lubricant within the collector.

[0078] We will now describe, with reference to [Fig.3], a transmission mechanism M according to a second embodiment of the invention which differs from the first embodiment in that the additional collection device 60 is made of material with the outer perimeter 58 of the lubricant receiving and distribution collector 50.

[0079] The lubricant receiving and distribution manifold 50 includes a flexible zone 55 connecting the outer periphery 58 to the collection wall 61. In order to absorb dimensional tolerances and ensure contact with the peripheral wall 46, the collection wall 61 is elastically articulated at the flexible zone 55. The flexible zone 55 is formed by a localized material necking.

[0080] The end of the collection wall 61 in contact with the housing includes a geometric shape that conforms to the inner shape of the housing, so as to form a partial seal behind the additional collection device 60.

[0081] Alternatively, the softened zone 55 can be achieved by a localized removal of material, for example a series of oblong holes aligned along a direction.

[0082] The additional collection device 60 may also have another complementary function, which is to partially seal certain internal areas of the transmission mechanism M. In some cases, the transmission mechanism M includes a breather 70 arranged on an upper part of the main housing 40a. The breather 70 is configured to prevent the pressure in the space enclosed by the housing 40a, 40b from becoming too high relative to the pressure outside the space.

[0083] As illustrated in [Fig. 3], the breather 70 is supported by the housing, and the inner end of the breather opens into a cavity 47 formed in the housing. The collection wall 61 of the additional collection device 60 at least partially covers the inlet of the cavity 47 and prevents the direct projection of lubricant into the cavity and onto the breather itself.

[0084] We will now describe, with reference to [Fig.4], a transmission mechanism M according to a third embodiment of the invention which differs from the first embodiment in that the additional collection device 60 is a sealing gasket attached to the outer perimeter 58 of the lubricant receiving and distribution collector 50.

[0085] As illustrated in [Fig.4], the sealing gasket 60 is here overmolded on the outer perimeter 58 of the lubricant receiving and distribution manifold.

[0086] The sealing gasket 60 includes a sealing lip 69 which forms the connection between the lubricant receiving and distribution manifold 50 and the main housing 40a. The sealing lip 69 acts as a collection wall and deforms elastically in order to absorb dimensional tolerances and ensure contact with the peripheral wall 46 and the base 45.

[0087] For greater stability, the sealing gasket 60 includes a mounting surface 67 bearing against the outer perimeter 58 of the lubricant receiving and distribution manifold.

[0088] We will now describe, with reference to [Fig. 5], a transmission mechanism M according to a fourth embodiment of the invention, which differs from the first embodiment in that the additional collection device 60 is a sealing gasket attached to the outer periphery 58 of the lubricant receiving and distribution manifold 50. More precisely, the sealing gasket 60 is inserted into a groove 59 formed on the outer periphery 58 of the lubricant receiving and distribution manifold 50. The groove 59 partially surrounds the bottom 52.

[0089] As illustrated in [Fig.4], the sealing gasket 60 is here overmolded on the outer perimeter 58 of the lubricant receiving and distribution manifold.

[0090] The sealing gasket 60 comprises an elastic body 68 which connects the lubricant receiving and distribution manifold 50 to the main housing 40a. The body 68 deforms elastically to absorb dimensional tolerances and ensure contact with the peripheral wall 46.

[0091] In the various embodiments described here, the additional collection device 60 ensures contact between the collection wall 61 and the peripheral wall 46 despite the large possible variations in their relative positions, linked to the processes for obtaining the housings and oil collectors, while maintaining simple assembly methods that do not require additional fastening components.

[0092] Naturally, the invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different embodiments of the invention without departing from its scope. For example, the invention described here in the context of a single-ratio speed reduction device can also be applied to a two-ratio or even more-ratio speed reduction device. The invention can also be applied to a coaxial-type speed reduction device in which the input and output shafts of the transmission mechanism M are concentric.

Claims

Demands

1. Internally lubricated transmission mechanism (M) comprising: - a speed reduction device (R) including at least a first transmission shaft (10) extending along a first axis of rotation (XI) and coaxially carrying a first gear (11), - a hollow-shaped housing (40a, 40b) including a base (45) and a peripheral wall (46) formed of the same material as the base, the peripheral wall partially surrounding the speed reduction device (R), - a lubricant receiving and distribution manifold (50) disposed in the housing (40a, 40b) between the peripheral wall (46) and the first axis of rotation (XI), characterized in that the lubricant receiving and distribution manifold (50) includes at least a bottom (52), an outer rim (58) and an additional collection device (60) connected to the outer rim,the additional collection device (60) being supported on the peripheral wall and / or the base of the housing.

2. Transmission mechanism (M) according to claim 1, wherein the lubricant receiving and distribution manifold (50) is arranged axially, along the first axis of rotation (XI), between the base of the housing and the first toothed wheel, the first toothed wheel (11) rotating about the first axis of rotation (XI) in a preferred direction, the lubricant receiving and distribution manifold (50) facing the first toothed wheel (11) so as to receive the lubricant projected by the teeth.

3. Transmission mechanism (M) according to claim 1 or 2, comprising a first guide bearing (100a, 100b) supporting the first transmission shaft (10) relative to the housing (40a, 40b), the first guide bearing being inserted in a first cylindrical housing (41) provided in the housing, the lubricant receiving and distribution manifold (50) comprising a lubricant outlet line (53) opening towards the cylindrical housing (41).

4. Transmission mechanism (M) according to any one of claims 1 to 3, comprising a breather (70) supported by the housing (40a, 40b), the inner end (71) of the breather opening into a cavity (47) formed in the housing, the collection wall (61) of the additional collection device (60) covers at least partially the inlet of the cavity (47).

5. Transmission mechanism (M) according to any one of the preceding claims, wherein the additional collection device (60) is attached to the outer perimeter (58) or formed from material with the outer perimeter (58), the additional collection device (60) comprising a collection wall (61) which forms the junction between the lubricant receiving and distribution manifold (50) and the housing (40a, 40b).

6. Transmission mechanism (M) according to the preceding claim, wherein the end of the collection wall (61) in contact with the housing comprises a geometric shape that follows the internal shape of the housing, for example a curvilinear shape.

7. Transmission mechanism (M) according to claim 5 or 6, wherein the additional collection device (60) is an added part comprising the collection wall (61) and a reinforcing wall (62) disposed on one of the edges of the collection wall, the reinforcing wall (62) comprising a mounting surface (62a) bearing against the outer perimeter (58) of the lubricant receiving and distribution collector (50).

8. Transmission mechanism (M) according to the preceding claim, wherein the reinforcing wall (62) includes snap-on tabs (63) which extend towards the lubricant receiving and distribution manifold (50), the additional collection device (60) being snap-on onto the outer perimeter (58).

9. Transmission mechanism (M) according to claim 5 or 6, wherein the additional collection device (60) is made of material with the outer perimeter (58), the lubricant receiving and distribution collector (50) comprising a flexible zone (55) connecting the outer perimeter and the collection wall (61), the flexible zone (55) being made by localized material necking or by localized material removal.

10. Transmission mechanism (M) according to any one of claims 1 to 6, wherein the additional collection device (60) is a sealing gasket attached to the outer perimeter (58).

11. Transmission mechanism (M) according to the preceding claim, wherein the sealing gasket (60) comprises a lip sealing (69) which connects the lubricant receiving and distribution manifold (50) and the housing (60), the sealing lip acting as a collection wall (61).

12. Transmission mechanism (M) according to claim 10 or 11, wherein the sealing gasket (60) is overmolded on the outer perimeter (58) of the lubricant receiving and distribution manifold (50).

13. Transmission mechanism (M) according to claim 10, wherein the sealing ring is inserted into a groove (59) formed on the outer perimeter (58) of the lubricant receiving and distribution manifold (50).

14. Transmission mechanism (M) according to any one of the preceding claims, wherein the housing (40a, 40b) has on the inner face of the peripheral wall (46) at least one drip edge (90) located in line with the lubricant receiving and distribution manifold (50), the drip edge (90) taking the form of an outgrowth of material and the additional collection device (60) resting on the drip edge (90).

15. Electric propulsion assembly (1) comprising an electric machine (60) and a transmission mechanism (M) according to any one of the preceding claims, the speed reduction system (R) comprising a second transmission shaft (20) guided in rotation about a second axis of rotation (X2) by a second guide bearing (200a, 200b), and a third transmission shaft (30) guided in rotation about a third axis of rotation (X3) by a third guide bearing (300a, 300b), one of the transmission shafts selected from the first, second and third transmission shafts (10, 20, 30) is rotationally fixed to the motor shaft of the electric machine.

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