- electromotive assembly with lubrication system

Abstract

Disclosed is an electromotive assembly (GEM) comprising: an electromotive unit UU having an electric machine (MEL) comprising a rotor shaft (1) and a rotor (9) mounted on the rotor shaft, and a differential mechanism (DF), mounted in the rotor shaft, the rotor shaft being a hollow tubular shaft; a first reduction gear (R1), comprising a reduction gear casing (CR1), mounted adjacent to the electromotive unit; a first, short auxiliary shaft (A1), constrained to rotate with one of the sun gears of the differential mechanism, and driving the first reduction gear; a lubrication system comprising an oil pump (PH) for providing a forced oil flow (FH) at least at a first inlet point (H1) on the casing (CR1) of the first reduction gear, wherein the lubrication system comprises oil conveying passages and / or channels for conveying the forced oil flow to the differential mechanism (DF), and the path of the oil passes through a central passage in the first short auxiliary shaft.

Description

[0001] DESCRIPTION

[0002] TITLE OF THE INVENTION: Electric motor unit with lubrication system

[0003]

[0001] The present invention relates to an electromotor unit for a vehicle axle, said electromotor unit comprising an electric machine, a differential and at least one reducer, said electromotor unit comprising a lubrication system.

[0004]

[0002] A transmission system which includes a differential and possibly a reduction gear or a gearbox is generally lubricated by axle / transmission oil, either simply by splashing, or by means of a lift pump which sprays certain parts of the transmission system, the oil returning to the reservoir by gravity.

[0005]

[0003] Furthermore, in the context of vehicle electrification, there is a tendency to integrate the differential mechanism as close as possible to the electric machine, and preferably upstream of the reducer.

[0006]

[0004] Some have already tried to install the differential at the heart of an electric motor rotor in the case of an electric motorization of a train or vehicle axle, as taught for example in documents EP0760549 or US11394270. However, it proves problematic to be able to ensure effective lubrication of the differential mechanism in these configurations.

[0007]

[0005] Moreover, in order to avoid using permanent magnets that consume rare earth natural resources, there is a tendency to use wound rotors, which must be excited from the stationary area through excitation friction rings, which occupies a substantial space at one end of the rotor shaft.

[0008]

[0006] Furthermore, in the case where the differential is integrated on the axis of the electric machine in the rotor shaft or in the vicinity of the rotor shaft, it is necessary to pass one of the intermediate transmission shafts through the rotor shaft from one side to the other.

[0009]

[0007] There therefore remains a need to propose a lubrication solution that combines objectives that are a priori contradictory.

[0010]

[0008] It is in this context that the inventors sought to propose a lubrication system that was particularly ingenious with regard to other requirements and other functions.

[0011]

[0009] To this end, an electromotor unit comprising is proposed here:

[0012] - an electromotive unit with an electric machine comprising a rotor shaft and a rotor mounted on the rotor shaft, and a differential mechanism mounted in the rotor shaft, the rotor shaft being hollow tubular,

[0013] - a first reduction gear, comprising a reduction gear housing, mounted adjacent to the electromotive unit,

[0014] - a first intermediate shaft, fixed in rotation to one of the planetary gears of the differential mechanism, and driving the first reduction gear,

[0015] - a lubrication system having a forced oil flow arriving at at least at a first entry point on the housing of the first reduction gear, the lubrication system comprising oil passages and / or channels to convey the forced oil flow to the differential mechanism, the oil path passing through a central passage of the first intermediate shaft.

[0010] Thanks to these arrangements, a solution is thus proposed to bring effective lubrication to the differential even when the differential is in a position that is not directly accessible at an external oil entry point (particularly due to the presence of electrical equipment, sensors, and the excitation connection of the wound rotor).

[0016]

[0011] The first intermediate shaft is a hollow shaft; the forced oil flow passes through its axial channel. According to one option, the first intermediate shaft is a short shaft, due to the position of the differential mechanism at the first end of the rotor shaft.

[0017]

[0012] It is noted that the lubrication system may include an oil pump to provide said forced oil flow.

[0018]

[0013] According to an advantageous embodiment, the reducer is a gear cascade reducer, preferably with coaxial input and output.

[0019]

[0014] The cost of these gearboxes is particularly attractive. An electric motor unit with an electric machine, a differential, and two gearboxes downstream of the differential proves to be an attractive form factor solution for integration into the vehicle architecture and a solution with a moderate cost.

[0020]

[0015] According to one embodiment, the differential mechanism comprises a cross-shaped planet carrier element with four arms, each arm being received in a bearing housed in a housing of the rotor shaft, the planet carrier element being driven by the rotor shaft, four planetary gears carried on the planet carrier element, two planetary gears meshing in the planetary gears, the oil conveying passages and / or channels bringing the forced oil flow to a central orifice of the planet carrier element.

[0021]

[0016] Advantageously, the main delivery point of the forced oil flow is located at the center of the satellite carrier element, which contributes to efficient and complete lubrication of the entire differential device.

[0022]

[0017] According to one embodiment, the planet carrier element includes internal channels (28) to bring oil to the bearings.

[0023]

[0018] Whereby the axis and back of the planetary gears can be lubricated, as well as the washers that support them. The progression of the oil towards areas distant from the axis is also aided by centrifugal force when the rotor shaft rotates.

[0024]

[0019] According to one embodiment, the oil path reaches the shaft via a blind hole in a pinion driven by the output of the reducer, through radial bores. This provides an elegant solution for delivering the oil flow to the axial region.

[0025]

[0020] According to one embodiment, the first entry point is at a distance from the axis, with an inlet channel preferably extending radially.

[0026]

[0021] According to one embodiment, an annular seal with a double axial lip is provided which delimits an intermediate buffer volume between the inlet channel and the radial drillings.

[0027]

[0022] According to one embodiment, a conveying cannula is provided which extends axially through the hub of the slow gear of the reducer and the first intermediate shaft.

[0028]

[0023] According to one embodiment, the differential mechanism is arranged at least partially in an axial area of ​​the rotor, upstream of the first reduction gear in the drive train. This contributes to reducing the overall size and improving the compactness of the electric motor unit.

[0024] In practice, the differential mechanism is housed at least partially inside the rotor shaft. According to one embodiment, the differential mechanism is substantially contained within diameter D1, where D1 is the outer diameter of the rotor shaft. The presence of the differential mechanism does not significantly increase the axial and radial dimensions of the motor. According to one embodiment, diameter D1 is less than 62 mm.

[0029]

[0025] According to one embodiment, the electromotor unit may further include a second reducer, a second intermediate shaft, fixed in rotation to the other of the planetary gears of the differential mechanism, the oil conveying passages and / or channels bringing part of the forced oil flow to the second reducer by passing through a central passage of the second intermediate shaft.

[0030]

[0026] From the first entry point on the side of the first reducer, the oil flow irrigates the entire electromotor unit including the second reducer.

[0031]

[0027] According to an alternative solution, a second entry point is provided on the housing of the second reducer.

[0032]

[0028] In this case, there is a double oil supply for the differential mechanism, which provides redundancy.

[0033]

[0029] According to one option, the second intermediate shaft is here a long shaft, due to the position of the differential mechanism at the first end of the rotor shaft.

[0034]

[0030] Optionally, each of the first and second reducers comprises a single reduction stage. This configuration proves to be simple, reliable, and inexpensive.

[0035]

[0031] Optionally, the first and second reducers are identical, the second reducer being rotated 180° relative to the first reducer. This reduces industrial diversity.

[0036]

[0032] The present invention also relates to a motor vehicle, comprising at least one electromotor unit as described above.

[0037]

[0033] The vehicle in question may be an electric or hybrid vehicle.

[0038]

[0034] The invention will be further detailed by describing non-limiting embodiments, and based on the accompanying figures illustrating variants of the invention, in which:

[0039] - [Fig.1] illustrates a front view of a first example of a motorized axle of a motor vehicle, in which the present invention is implemented;

[0040] - [Fig.2] schematically represents in cross-section an electromotor unit according to the first example of axle in figure 1;

[0041] - [Fig.3] schematically represents in cross-section the electromotor group of figure 2 in preparation before assembly;

[0042] - [Fig.4] shows in cross-section the region of the electromotor unit where the oil inlet is located;

[0043] - [Fig.5] schematically represents in partial section the axial zone of the electromotor group;

[0044] - [Fig.6] represents an exploded view, illustrating the elements involved in the differential device and also illustrating the assembly process of the device;

[0045] - [Fig.7] illustrates an exploded local axial cross-sectional view representing part of the satellite carrier equipment; - [Fig.8] illustrates an axial cross-sectional view of an example of an axial double-lip seal participating in the path and channels of the forced oil flow;

[0046] - [Fig.9] schematically represents an example of the general arrangement of the electromotor unit in relation to the vehicle reference frame and in particular in relation to the vertical.

[0047]

[0035] In the various figures, the same reference numerals designate identical or similar elements. For the sake of clarity, some elements are not necessarily shown to scale.

[0048]

[0036] Figure 1 shows an axle of a motor vehicle, in this case a motorized axle in which an electromotor unit GEM drives right and left wheels referenced 47 according to a first embodiment.

[0049]

[0037] In the illustrated example, this refers to an electric motor in a hybrid or pure electric vehicle.

[0050]

[0038] As will be seen in detail later, the rotor shaft drives a differential device DF, each of whose outputs in turn drives a speed reducer (R1, R2). Each of the reducers R1, R2 includes an output pinion which drives the respective wheel 47 by means of a homokinetic transmission T1, T2 as known per se.

[0051]

[0039] The reference numeral MEL designates the electric machine with a stator and a rotor. The electric machine operates as a motor or a generator depending on the driving conditions. The illustrated electric machine is radial flux, but the invention can also be applied to an axial flux electric machine.

[0052]

[0040] The reference GEM designates the electromotor group which includes the electric machine MEL, the differential device DF, the left reducer R1 (hereafter referred to as the first reducer) and the right reducer R2 (hereafter referred to as the second reducer).

[0053]

[0041] The differential device DF can be integrated, at least in part, into the rotor shaft. The reference numeral UU designates an electromotive unit comprising the electric machine and the differential device DF.

[0054]

[0042] Figures 2 and 3 illustrate, according to one possible embodiment, the position of the differential device DF in the electromotive unit UU relative to the electric machine. In Figure 3, the intermediate drive shafts are shown in a position prior to assembly; more specifically, this refers to the short intermediate shaft A1 (also called the first intermediate shaft) and the long intermediate shaft A2 (also called the second intermediate shaft).

[0055]

[0043] The MEL electric machine comprises a rotor shaft 1 and a rotor 9 mounted on the rotor shaft, the rotor shaft being hollow tubular.

[0056]

[0044] The first reducer R1 includes a reducer housing CR1, mounted adjacent to the electromotive unit UU. The electric machine includes a housing CM, composed here of three parts: a main housing C0 in the shape of a sleeve around the stator, a first end housing C1 and a second end housing C2.

[0057]

[0045] The electromotor group includes the short intermediate shaft A1, fixed in rotation to one of the planetary gears of the differential mechanism, in this case the second planetary gear 22.

[0058]

[0046] The shaft A1 is a hollow shaft, and fitted with grooves on its outer cylindrical wall, it drives the first reducer R1.

[0059]

[0047] When the vehicle travels along a curved road, one of the intermediate drive shafts rotates faster than the other, as is known, causing each planetary gear to rotate on its own axis, a phenomenon known as differential slippage. It is therefore necessary to lubricate the components involved in the rotation of the planetary gear on its own axis.

[0060]

[0048] The short intermediate shaft A1, once assembled, drives the first reducer R1 via the first input pinion of the reducer, marked 31. The long intermediate shaft A2, once assembled, drives the second reducer R2 via the second input pinion of the reducer, marked 32.

[0061]

[0049] The rotor shaft noted 1 is hollow and is configured to house the long intermediate shaft A2. The rotor shaft 1 is integral with the rotor 9 of the machine.

[0062]

[0050] The rotational locking of the rotor and the drive shaft can be achieved by a shrink-fitting process. In the illustrated example, grooves 1k are provided in the rotor shaft which receive internal projections of the rotor's ferromagnetic plates. The grooves and projections cooperate by complementary shapes.

[0063]

[0051] Referring to the figures, the rotor shaft has a tubular body. The rotor shaft 1 extends from a first axial end designated E1 to a second axial end designated E2 along a main axis designated Y1.

[0064]

[0052] The rotor shaft 1 includes housings 18 formed in the tubular body at the first axial end E1 (see figure 6). These housings 18 are intended to receive and drive a planet carrier element 2 forming part of the differential mechanism denoted DF.

[0065]

[0053] The rotor shaft 1 has in its main part an outside diameter D1 over a length denoted L1, as seen in figure 5.

[0066]

[0054] The rotor shaft 1 is mounted to rotate around Y1 relative to the machine housing CM by means of two bearings B1 and B2.

[0067]

[0055] The differential mechanism DF comprises a planet carrier element 2 received in the housings 18 via bearings described later. The differential mechanism DF is of the bevel gear type here.

[0068]

[0056] Each housing 18 has an opening directed axially opposite to the second axial end E2 to allow end mounting on the side of the first axial end E1, in the direction of E2.

[0069]

[0057] The planet carrier element 2 is driven in rotation by the rotor shaft 1. The transmission device includes four planet gears (23, 24, 25, 26) mounted for rotation on the planet carrier 2.

[0070]

[0058] The satellite carrier element 2 is cross-shaped with four identical arms. Each end includes an end trunnion 27 around which a satellite mounted at that location can rotate.

[0071]

[0059] Each of the branches of the cross-shaped satellite carrier element extends along a local axis WR perpendicular to the main axis Y1. The satellite carrier element 2 includes internal channels 28 in each branch to bring oil to the bearings 5 ​​(see figure 7).

[0072]

[0060] The satellite carrier element 2 is made of steel, just like the satellites and planetary gears.

[0073]

[0061] The differential mechanism DF comprises a first planetary pinion 21 and a second planetary pinion 22.

[0074]

[0062] Each planetary gear meshes with the satellite gears. The satellite gears do not mesh with each other.

[0075]

[0063] The first planetary gear 21 is suitable for driving the short intermediate shaft A1. The second planetary gear 22 is suitable for driving the long intermediate shaft A2.

[0064] The number of planetary gears could be two. Thus, generally, the transmission device comprises at least two planetary gears.

[0076]

[0065] A bearing 5 is provided interposed between each housing 18 and the satellite carrier 2. The bearing 5 allows the torque produced by the rotor to be taken up and transferred to the rotor shaft via the differential device.

[0077]

[0066] With reference to Figures 6 and 7, the bearing 5 can be mushroom-shaped. For example, each bearing 5 comprises a head 52 received in the respective opposite housing, and a bearing tube 51 around which a satellite is mounted.

[0078]

[0067] Each of the bearing heads comprises two straight edges 55 parallel to the main axis Y1 orthogonal to the local axis of the bearing tube.

[0079]

[0068] Each of the bearings includes a front edge 56 which, once assembled, is flush with the free edge 1a of the shaft.

[0080]

[0069] The head is convex outwards with an entry chamfer 57.

[0081]

[0070] The curvature follows the general profile of the outer wall of the rotor shaft once the bearing is in place.

[0082]

[0071] On the inner side, the head includes an annular flat 59 on which a washer rests. The annular flat surrounds the base of the bearing tube.

[0083]

[0072] The bearing tube receives on the inner side a trunnion 27 of the planet carrier 2 received in an inner bearing 50. Furthermore, the bearing tube receives on the outer side, i.e. on its external cylindrical bearing surface 58, the inner bore 44 of the planet which can whirl at this point.

[0084]

[0073] Each housing 18 comprises a semicircular housing base and two straight sides parallel to the Y1 axis. The housing is open at an opening opposite the housing base. Each housing can be easily obtained by a milling cutter.

[0085]

[0074] The second planetary gear 22 bears against a front face 6a of an annular planetary thrust bearing 6. The planetary thrust bearing 6 comprises a rear face which bears against a shoulder 160 provided in the rotor shaft.

[0086]

[0075] Advantageously, pressure washers (4,4') are provided on the back of the satellites and planetary gears.

[0087]

[0076] Pressure washers are non-flat washers at rest. They exhibit a certain elasticity and can return to a flat shape under compressive stress. The pressure washers 4' on the back of the planetary gears contribute to compensating axial play. The pressure washers 4 on the back of the satellite gears 45 contribute to compensating transverse play. The pressure washers also contribute to self-centering of the drive shafts during rotation. Furthermore, this allows hysteresis to be eliminated when the direction of torque changes.

[0088]

[0077] A differential cover, noted 7, is provided, inserted externally on the first axial end E1 of the rotor shaft 1. The differential cover 7 achieves the sandwich closure of the differential mechanism DF.

[0089]

[0078] The differential cover 7 is formed as a metal ferrule with a material thickness between 2 mm and 5 mm, preferably with a material thickness between 2.5 mm and 4 mm.

[0090]

[0079] The differential cover includes a capping skirt 70 delimited by a free circular border 74.

[0080] As seen in the figures, the differential cover 7 includes an axial opening 72 configured to allow passage for the first intermediate shaft A1.

[0091]

[0081] Furthermore, the rotor shaft 1 is configured to house the second intermediate shaft A2 up to an axial through opening noted 19 at the second axial end E2 of the rotor shaft.

[0092]

[0082] The differential cover 7 can be inserted by shrink fitting onto the rotor shaft 1.

[0093]

[0083] The wound rotor is electrically activated via excitation tracks P1, P2. The excitation tracks are arranged in an annular fashion at the second end E2 of the shaft opposite the position of the differential device.

[0094]

[0084] The excitation tracks are conductive, for example made of copper alloy. Opposite each track, one or more friction pads (not shown) are provided which make contact with the track and are pushed towards the track by an elastic system.

[0095]

[0085] The outer diameter of the long intermediate shaft A2 is chosen to be around 25 mm, for example, within a range of values ​​between 22 and 26 mm. It should be noted that, according to one option, the long intermediate shaft A2 has an axial lubrication passage 76 along its entire length.

[0096]

[0086] It is noted that the transmission device is devoid of bearings inside the rotor shaft, which makes it possible to increase the compactness of the differential mechanism.

[0097]

[0087] Bearing B1 is arranged to surround the second planetary gear 22, in the same axial position, for rotational guidance of the transmission device and, in particular, for guiding the rotor shaft. Bearing B1 is received in a bearing surface of the front housing C1 of the MEL machine.

[0098]

[0088] Reducers

[0099]

[0089] The first reducer R1 includes a reducer housing marked CR1.

[0100]

[0090] The first reducer R1 comprises an input pinion 31, a high-speed gear 41, a low-speed gear 42, the low-speed gear comprising a toothed output hub, into which a toothed shaft 63 of the homokinetic transmission 61 to a wheel is inserted (see figure 2).

[0101]

[0091] The input pinion 31 is guided in rotation by a bearing B3.

[0102]

[0092] The shaft of the high-speed gear 41 is guided in rotation around the axis Y2 on both sides by a bearing B5 and a bearing B7.

[0103]

[0093] The center distance separating the axis of the high-speed gear 41 from the main axis Y1 is denoted ER and is here between 100 mm and 130 mm. This is the same center distance that separates the axis of the high-speed gear 41 from the axis of the low-speed gear 42. Advantageously, the input and output of the first reducer are coaxial, on the axis Y1.

[0104]

[0094] The slow gear 42 forms the output of the reducer, with a radially internal spline 42b which cooperates with a radially external spline 66.

[0105]

[0095] The slow gear 42 includes a hub with an axial passage 42k.

[0106]

[0096] The shaft of the slow gear 42 is guided in rotation on the output side by a bearing B6 and on the opposite side by a needle bearing N1 mounted on an inner bearing of the input pinion 31 (see figure 4).

[0107]

[0097] The high-speed gear 41 comprises a first radially external, large-diameter toothed sector 41a and a second radially external, small-diameter toothed sector 41b, which drives a first radially external, large-diameter toothed sector 42a of the low-speed gear 42.

[0098] The low-speed gear 42 comprises radially internal splines, denoted 42b, for receiving the end of the constant velocity joint 61, in particular the splines 66.

[0108]

[0099] The second reducer R2 comprises an input pinion 32, a high-speed gear 41, a low-speed gear 42, the low-speed gear comprising a toothed output hub, into which a toothed shaft end of the homokinetic transmission 62 is inserted towards the other wheel.

[0109]

[0100] The second reducer R2 includes a reducer housing marked CR2.

[0110]

[0101] The second reducer R2 is similar or even identical to the first reducer, and the description given for the first reducer applies to the second reducer R2. Advantageously, two identical reducers can be used, one being rotated 180° relative to the other around an axis perpendicular to Y1.

[0111]

[0102] It is noted that each reducer comprises five bearings (four ball bearings B3, B4, B5 B6 B7 and one needle bearing N1) to guide in rotation three rotating parts namely the input pinion, the high-speed gear and the low-speed gear.

[0112]

[0103] Each reducer housing is formed in two pieces as can be seen in figures 2 and 3.

[0113]

[0104] Each CR1,CR2 gearbox housing is fixed to the CM machine housing at one end of the MEL electric machine.

[0114]

[0105] Once the assembly is complete, the MEL electric machine is interposed between the two reducers. The housings of the two reducers (CR1, CR2) are fixed to the CM housing of the electric machine to form a single assembled mechanical unit.

[0115]

[0106] Lubrication system

[0116]

[0107] The electric motor unit includes a lubrication system comprising an oil pump PH to provide a forced oil flow FH.

[0117]

[0108] The forced oil flow is brought to a first oil inlet point H1 on the housing CR1 of the first reducer. A filter 79 is provided to filter the circulating oil flow.

[0118]

[0109] The return of the oil to the oil reservoir (also called 'tank') is done by gravity.

[0119]

[0110] Generally, the lubrication system includes oil passages and / or channels to convey the forced oil flow to the differential mechanism DF, the oil path passing through a central passage 75 of the first short intermediate shaft.

[0120]

[0111] The first entry point H1 is at a distance EY from the axis, with an input channel F10, the input channel being provided in the housing of the first reducer R1.

[0121]

[0112] The inlet channel F10 extends radially in the direction of the axis and opens into an annular volume G4 which acts as an intermediate buffer volume. The intermediate buffer volume G4 is delimited by a specific axial double-lip seal 11.

[0122]

[0113] The annular volume G4 communicates with a second annular volume G5 of smaller diameter, located radially inside the buffer volume G4.

[0123]

[0114] The path of the forced oil flow continues towards the axis through radial holes F11 provided in the pinion 61 driven by the output of the reducer. This pinion 61, with a splined hub 66, forms part of the constant velocity transmission to the wheel 47.

[0115] There may be a single radial hole, two diametrically opposed radial holes F11, or three or more radial holes F11.

[0124]

[0116] The oil arrives in the axial zone in a blind hole cavity 68 formed in the grooved trunnion 63 delimited by its front edge 65.

[0125]

[0117] The path of the oil is schematically represented by the small black arrows in figure 4.

[0126]

[0118] The oil path then passes through a central passage 42k of the slow gear 42, then through a central passage 75 of the first short intermediate shaft A1.

[0127]

[0119] According to one option, a conveying cannula 17 is provided which extends axially through the hub of the slow gear 42 of the reducer and the first short intermediate shaft A1 by the axial passage 75.

[0128]

[0120] The axial conveying cannula 17 brings the forced oil flow to the central orifice 2H of the planet carrier element 2, passing as shown above through the central passage 42k of the slow gear 42 and the central passage 75 of the short shaft A1.

[0129]

[0121] To prevent excessive oil delivery into the first reducer, a groove 17a is provided at the first end of the delivery cannula, with an O-ring 175 received in the groove 17a. The forced oil flow is directed inside the delivery cannula 17.

[0130]

[0122] The first end of the cannula rests on a shoulder 64 provided in the pinion 61.

[0131]

[0123] In the illustrated example, the second end of the cannula, marked 171, is received inside the planet carrier element. The outside diameter of the cannula at the location of the second end 171 is slightly smaller than the diameter of the central hole 2H of the planet carrier element 2. This allows oil to flow backward towards the first reducer and also avoids friction at this location due to the relative speed (the planet carrier is fast while the delivery cannula rotates slowly, being driven by the output pinion of the reducer via the O-ring 175).

[0132]

[0124] On the outside of the output pinion 61 of the reducer, there is a lip seal noted 14, of known structure and functions, as well as a dust cover J15 (see figure 4).

[0133]

[0125] The intermediate buffer volume G4 is delimited by the lip seal 14, the axial double lip seal 11, and an annular portion 140 of the housing CR1

[0134]

[0126] As illustrated in Figure 8, the axial double-lip seal 11 is generally of revolution about the main axis Y1 and comprises a mounting portion 12 and a working portion 13. The working portion 13 comprises a first lip 15 configured to bear against a rotating bearing surface and a second lip 16 configured to bear against a stationary bearing surface. The mounting portion 12 comprises a rim 12a received in a cylindrical bearing surface 12b provided in the housing CR1.

[0135]

[0127] A passage 11b is provided to allow the oil to escape by overflow from the intermediate buffer volume G4 and flow into the second annular volume G5, which has a smaller diameter. The second annular volume G5, which has a smaller diameter, is connected to the radial bores F11.

[0136]

[0128] The passage 11b is arranged in an upper part of the joint 11, in the direction of the local vertical.

[0129] Lubrication of the second reducer

[0137]

[0130] According to a first option, the oil conveying passages and / or channels bring part of the forced oil flow to the second reducer R2 via a central passage 76 of the second long intermediate shaft A2.

[0138]

[0131] Optionally, as seen in figure 8, a small hole 2F may be provided which allows the oil to pass through the center of the satellite carrier to irrigate the passage provided inside the second long intermediate shaft.

[0139]

[0132] According to a second option, a second entry point H2 is provided on the housing of the second reducer R2, supplied from the PH pump by an auxiliary circuit represented in dotted lines in figure 2.

[0140]

[0133] It is advantageous to use two identical reducers (positions with a rotation of approximately 180°), and in this case the satellite carrier element can be supplied from both ends of the rotor shaft.

[0141]

[0134] In this case, the second reducer has a delivery cannula marked 170 similar to that described previously and therefore not described again here.

[0142]

[0135] Miscellaneous

[0143]

[0136] Regarding the orientation in space of the electromotor group, figures 2 to 5 illustrate a first example where the reducers are located above the main axis Y1, in other words the reducers form upward-directed projections with respect to the axis of the electromotor group.

[0144]

[0137] According to another configuration schematically illustrated in Figure 9, in which the X-axis corresponds to the longitudinal direction of the vehicle, the Y-axis to the transverse direction of the vehicle, and the Z-axis (correction) to the vertical, the electric motor unit is arranged horizontally, i.e., with the gearboxes forming a projection in the horizontal plane relative to the main axis Y1. Y2 can be at the same level as Y1 or slightly higher. Naturally, in this configuration, the first oil inlet point H1 is located above the main axis (therefore rotated approximately 90° relative to the configuration shown in Figures 2 to 5).

[0145]

[0138] Regarding the relative dimensions, it is noted that in one embodiment example, we have L1 / D1 > 2 where L1 is the axial length of the rotor shaft 1. The length of the electric machine is significant with regard to the access required for the forced oil flow to the heart of the machine.

[0146]

[0139] The axial passages for the oil may have a diameter between 4 mm and 6 mm. This applies in particular to axial passages 75, 76 and, if a delivery cannula 17 is used, to the inner diameter of the cannula.

[0147]

[0140] It is noted that the intermediate buffer volume G4 allows oil to be kept at this location directly and immediately usable from the first rotations in a start-up configuration, after a long stop or in the situation where the pump takes some time to deliver the forced oil flow to the inlet point H1.

[0148]

[0141] The flow of oil FH and the splash lubrication provide lubrication for the entire interior of the electric machine MEL and the entire interior of both gearboxes, including the needle bearings N1 and N2 and the various splines. Splines 42b and 66 and the needle bearing N1 are lubricated.

[0142] It should be noted that the electromotive unit UU integrates the differential function into a form factor that differs very little from a standalone electric machine form factor for the same power characteristics.

[0149]

[0143] According to a particular application example on a motor vehicle drive axle, D1 < 62 mm for a motor torque to be passed up to the order of 800 Nm.

[0150]

[0144] Moreover, the slippage is limited by the software functions.

[0151]

[0145] According to an advantageous arrangement, the slippage of the differential device is limited by the general behavior of the system and in general and in particular by the intervention of software which makes it possible to drastically reduce the torque and therefore the rotational speed of the motor in the event that one of the wheels slips.

[0152]

[0146] As known per se, it is provided as a position and rotation speed sensor for the rotor, represented by references 8 and 92 in Figure 4.

[0153]

[0147] Regarding terminology, it should be noted that "planetary gears" can be called simply "planetary" and "satellite gears" can be called simply "satellites".

Claims

1. DEMANDS 1. Electric motor unit (EMU) comprising: - an electromotive unit UU with an electric machine (MEL) comprising a rotor shaft (1) and a rotor (9) mounted on the rotor shaft, and a differential mechanism (DF) mounted in the rotor shaft (1), the rotor shaft being hollow tubular, - a first reducer (R1), comprising a reducer housing (CR1), mounted adjacent to the electromotive unit, - a first intermediate shaft (A1), fixed in rotation to one of the planetary gears of the differential mechanism, and driving the first reduction gear, - a lubrication system having a forced oil flow arriving at least at a first entry point (H1) on the casing (CR1) of the first reducer, the lubrication system including oil passages and / or channels to convey the forced oil flow to the differential mechanism (DF), the oil path passing through a central passage (75) of the first intermediate shaft (A1).

2. Electromotor unit according to claim 1, wherein the reducer is a gear cascade reducer, preferably with coaxial input and output.

3. Electromotor unit according to any one of claims 1 to 2, wherein the differential mechanism (DF) comprises a cross-shaped planet carrier element (2) with four arms, each being received in a bearing (5) housed in a housing (18) of the rotor shaft (1), the planet carrier element being driven by the rotor shaft, four planet gears (23,24,25,26) carried on the planet carrier element, two planetary gears (21,22) meshing in the planet gears, the oil conveying passages and / or channels bringing the forced oil flow to a central orifice (2H) of the planet carrier element.

4. Electromotor unit according to claim 3, wherein the satellite carrier element (2) includes internal channels (28) for bringing oil to the bearings (5).

5. Electromotor unit according to any one of claims 1 to 4, in which the oil path arrives on the shaft (Y1) in a blind hole (68) of a pinion (61) driven by the output of the first reducer (R1), via radial bores (F11).

6. Electromotor unit according to any one of claims 1 to 5, wherein the first input point (H1) is at a distance (EY) from the axis, with an input channel (F10) preferably extending radially.

7. Electromotor unit according to claims 5 and 6, in which there is provided an annular seal with axial double lip (11) which delimits an intermediate buffer volume (G4) between the inlet channel (F10) and the radial bores (F11) and a conveying cannula (17) which extends axially through the hub of the slow gear (42) of the reducer and the first intermediate shaft.

8. Electromotor unit according to any one of claims 1 to 7, further comprising a second gearbox (R2), a second intermediate shaft (A2), solid in rotation with the other of the planetary gears of the differential mechanism, the oil conveying passages and / or channels bring part of the forced oil flow to the second reducer (R2) via a central passage (76) of the second intermediate shaft (A2).

9. Electromotor unit according to claim 8, wherein a second entry point (H2) is provided on the housing of the second reducer (R2).

10. Motor vehicle, preferably electric or hybrid, comprising an electric motor unit (EMU) according to any one of claims 1 to 9.

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