MOTOR VEHICLE EQUIPPED WITH WHEEL TRANSMISSIONS WITH RIGHT-LEFT IDENTIFICATION

Abstract

The invention relates to a motor vehicle equipped with an engine (6) configured to supply torque to the wheels of the motor vehicle, via a central transmission with a differential (4), and a set of transverse transmissions, the set of transverse transmissions comprising: - a left-hand transmission link (2) driven by a left-hand output of the differential, via a first splined coupling (C1), - an intermediate shaft (1) driven by a right-hand output of the differential via a second splined coupling (C2), and a right-hand transmission link (3) driven by the intermediate shaft, via a third splined coupling (C3), characterized in that the first splined coupling comprises a first number of splines, the third splined coupling comprises a third number of splines, and the third number of splines is different from the first number of splines. Figure 2

Description

Title of the invention: MOTOR VEHICLE EQUIPPED WITH WHEEL TRANSMISSIONS WITH RIGHT-LEFT FOOL-OFF

[0001] The invention relates to a motor vehicle provided with wheel transmissions, in particular a motor vehicle equipped with an engine configured to supply torque to the wheels of the vehicle via a central transmission with differential, and a set of transverse transmissions, i.e. a left transmission for driving the left wheel and a right transmission for driving the right wheel.

[0002] We are talking here about a vehicle train which is motorized, it is either a traction train for the front train, or a propulsion train for the rear train.

[0003] The train equipped with the traction / propulsion motor can be directional or non-directional.

[0004] When we look at the front axle, in a typical configuration, it is both motorized and steered. Since the wheels are suspended and steered, it is necessary to use transmission links interposed between the engine and each of the wheels, these transmission links comprising one, or most often two, homokinetic joint(s) allowing the necessary travel while maintaining the required rigidity in rotation around the wheel drive axis.

[0005] The focus here is on electric or hybrid vehicles, although the application of the present invention to conventional internal combustion engine vehicles is not excluded.

[0006] Furthermore, when the engine, whether electric or thermal, is arranged transversely relative to the vehicle, the differential of the central transmission is not in a median position between the left and the right of the vehicle, in other words, it is offset to the left or to the right relative to a longitudinal median plane of the vehicle.

[0007] From this point on, two solutions are used: the first consists of using a transmission link longer than the other, and the second consists of interposing an intermediate shaft to compensate for the offset, and thus using two transmission links of the same length.

[0008] When using the solution of an intermediate shaft to compensate for the offset, one of the transmission links (the left one according to the illustrated example) is engaged with an output of the differential via a first splined coupling and the other of the transmission links (the right one according to the illustrated example) is engaged with the intermediate shaft via another splined coupling. This other splined coupling must also be lubricated while it is located at a distance from the others components contained in the differential housing, which requires an oil supply to this location.

[0009] It turned out that it is necessary to install a sealing device for the lubrication function on the transmission connection engaged with the intermediate shaft, while this is not necessary on the one engaged directly in the differential.

[0010] Although the two transmission links are of the same length and the same general appearance, they still differ in the presence or absence of the sealing device in question.

[0011] It is therefore necessary to ensure that the operators who assemble the vehicle in the assembly plant do not make a mistake and take the correct transmission connection for each side.

[0012] The inventors therefore sought to avoid the risk of mounting a transmission link without a sealing device when the sealing device is required, and therefore to avoid a risk of oil leakage.

[0013] To this end, the present invention proposes a motor vehicle, equipped with an engine configured to supply torque to wheels of the motor vehicle, via a central transmission with differential, and a set of transverse transmissions, the set of transverse transmissions comprising: - a left transmission link driven by a left output of the differential, via a first splined coupling, - an intermediate shaft driven by a straight output of the differential via a second splined coupling, - and a straight transmission link driven by the intermediate shaft, via a third splined coupling, characterized in that the first spline coupling comprises a first number of splines, the third spline coupling comprises a third number of splines, and the third number of splines is different from the first number of splines.

[0014] Thanks to the above-promoted arrangements, it is impossible to couple the right transmission link directly into an output of the differential and it is also impossible to couple the left transmission link onto the intermediate shaft.

[0015] This has formed a keying or “poka-yoke” function, thus preventing any incorrect assembly concerning all the transverse transmissions.

[0016] It should be noted that the terms "left" and "right" have been used for the sake of brevity, but by a symmetry transformation with respect to the median longitudinal plane of the vehicle, we could very well have the opposite, and replace "left" with "right" and "right" with "left" in the solution promoted above.

[0017] It is noted that the transmission links are homokinetic transmission links, each typically comprising, as known per se, a short shaft, a homokinetic joint, a longer shaft, another homokinetic joint, and another short shaft, one of the homokinetic joints being of the sliding type to allow elongation according to the different possible breaking angles in the transmission link.

[0018] It should be noted that the term "driven" in the solution promoted above should be understood as "rotationally driven". The transmitted torque can go from the engine to the wheels, but also in certain circumstances, go back from the wheels to the engine (regenerative braking or engine braking). Locking the steering by the parking position can also induce a rotational torque on the transverse transmission links.

[0019] According to one embodiment, the straight transmission link comprises a specific seal.

[0020] As a result, the third coupling can be lubricated without oil leakage. Thanks to the lubrication and the presence of the seal, the occurrence of a possible phenomenon of stress corrosion ('fretting corrosion') at the location of the third coupling between the male splines and the female splines is thus avoided.

[0021] According to one embodiment, the first number of splines is between 20 and 30 and the third number of splines is between 20 and 30. Thus, the number of splines is within an optimum which combines a low tooth height with a significant capacity to transmit torque through the coupling between the male splines and the female splines. This provides good radial compactness while satisfying the requirements for transmitting rotational torque.

[0022] According to one embodiment, the second spline coupling comprises a second number of splines, the second number of splines being equal to the first number of splines.

[0023] As a result, the planetary bevel gear on which the intermediate shaft is engaged can be identical to the planetary bevel gear on which the left transmission link is engaged. This avoids industrial and after-sales network diversity for the bevel gears.

[0024] According to an alternative embodiment, the second number of splines may be different from the first number of splines.

[0025] According to one embodiment, the intermediate shaft comprises a first end with a male spline engaged in a satellite pinion of the differential (second coupling), and a second end with a female spline capable of receiving the male spline of the right transmission link (third coupling). The mounting of the right transmission link on the inside of the vehicle is therefore similar to what is known in a configuration without intermediate shaft. The straight drive link remains conventional from the point of view of the male splined rod, on the inner side. Note that the right output of the differential remains standard, i.e. similar to a configuration without intermediate shaft.

[0026] According to one embodiment, the first number of splines is greater than the third number of splines. Due to the position of the third coupling, the space constraints on the different diameters are a little lower than at the first coupling, the number of teeth greater than at the first coupling makes it possible to reduce the radial space requirement of the splines inside the differential, thus contributing to the general compactness of the electromotive group.

[0027] According to one embodiment, the third splined coupling is lubricated. This increases its service life.

[0028] According to one embodiment, the left transmission link and the right transmission link have identical stiffness and length characteristics. This provides balanced dynamic behavior of the vehicle; there is no left / right asymmetry from the point of view of the dynamic behavior of the vehicle. This refers to the torsional rigidity of the transmission link, including joints.

[0029] According to one embodiment, the motor is an electric motor and the central transmission comprises a reducer. The proposed configuration is well suited for a 100% electric vehicle, and makes it possible to obtain very good compactness of the electromotive group and a match of the respective rotation speeds.

[0030] According to one embodiment, each transmission link, right and left, comprises two homokinetic joints. It is thus possible to take into account significant angular movements and substantial misalignments, particularly in the case of a train with steered wheels.

[0031] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which: [Fig.l] is a schematic representation of an example of a vehicle seen from the side in which the present intervention can be implemented; [Fig.2] shows schematically an exploded diagram of the transverse transmission assembly; [Fig.3] is a more detailed view of the intermediate shaft and its interfaces with the left and right drive links; [Fig.4] it illustrates, in section view, a grooved interface with the male part on the left of the figure and the female part on the right of the figure.

[0032] In the example illustrated in the figures, we are interested in a motor vehicle electric 7, namely a vehicle equipped with an electric powertrain.

[0033] It is noted that even if the vehicle in question is an electric vehicle, the invention is applicable to a hybrid vehicle and also a vehicle with a conventional thermal engine.

[0034] More specifically, the vehicle 7 here comprises a front axle driven by an electric machine. The electric machine drives the front wheels 72 via a transmission equipped with a differential 4.

[0035] Furthermore, in the example illustrated, the front wheels 72 are steered, that is to say they are mounted on steering knuckles that can be steered along a substantially vertical axis in a manner known per se. Furthermore, the wheels are connected to the chassis of the vehicle by a suspension system that allows at least a fairly large vertical movement of the wheels relative to the rest of the vehicle. Thus, as is well known, the axis of the wheels undergoes, relative to the chassis of the vehicle, various misalignments and movements, and these are compensated by the presence of the transverse transmission links, at the heart of the present invention.

[0036] The vehicle 7 moves in a space identified by the following directions: the first direction X corresponding to a longitudinal axis of the vehicle, the second direction Y corresponding to a transverse axis of the vehicle, and the third direction Z corresponding to a vertical axis relative to the local ground.

[0037] We are particularly interested here in private vehicles, small utility vehicles such as vans, delivery vehicles, service vehicles. The constraints of integrating all the components are very significant in a complex and restrictive geometry of available volume.

[0038] As shown in [Fig.2], the solution of the central intermediate shaft is thus favored, which makes it possible to avoid using a long transmission link and to manage the large volume necessary for its travel.

[0039] The intermediate shaft is referenced 1 in this document.

[0040] More generally, the vehicle is equipped with a powertrain arranged transversely, its main axis being parallel to the transverse direction Y of the vehicle.

[0041] In the illustrated example of an electric traction case, that is to say mainly based on the presence of an electric machine, the motor is an electric machine belonging to a so-called electromotor group 8.

[0042] The electric machine 6 is therefore part of an 'electromotor group' assembly 8 which comprises, in addition to the electric machine, a transmission called here central transmission to distinguish it from the transverse transmissions, and accessories such as for example an air conditioning compressor, a motor control inverter, etc.

[0043] The central transmission comprises a reducer 5 and a differential marked 4. The The reducer may include one or more gear trains that reduce the rotational speed from a motor rotor rotational speed to a differential output rotational speed in a desired ratio.

[0044] In the case of a thermal engine, the central transmission may also include a gearbox.

[0045] The differential 4 is arranged in a rearward and lower position relative to the axis of the electric motor. As illustrated in [Fig.l], the axis of the output bevel gears of the differential is not too far from the axis of the front axle wheels in the rest position of the vehicle at half payload for example.

[0046] The transverse transmissions are also called "transmission links", respectively left and right, in this document.

[0047] The right transmission link 3 comprises, starting from the inner side and going towards the outer side, a splined rod 31, a short shaft 33, a first constant velocity joint 34, a longer shaft 35, another constant velocity joint 36, and another short shaft 37, and another splined rod 32 which comes to interface with the wheel hub.

[0048] The left transmission link 2 has the same composition, known per se and therefore not repeated here.

[0049] The straight transmission link 3 further comprises a sealing device 38, O-ring or other solution.

[0050] One of the homokinetic joints 34, 36 is of the sliding type to allow an elongation in the transmission link according to the different possible breaking angles and wheel travels.

[0051] CV joints can be of any type.

[0052] Here, the term “transverse transmission assembly” is defined as the transmission elements located downstream of the differential 4.

[0053] Thus, said transverse transmission assembly comprises: the left transmission link 2 driven by a left output of the differential, via a first spline coupling denoted C1, the aforementioned intermediate shaft 1 driven by a right output of the differential via a second spline coupling denoted C2, and the right transmission link 3 driven by the intermediate shaft, via a third spline coupling denoted C3.

[0054] The first spline coupling C1 comprises a first number of splines denoted NI.

[0055] The second spline coupling C2 comprises a second number of splines N2.

[0056] The third spline coupling C3 comprises a third number of splines N3.

[0057] Cleverly according to the present invention, the third number of splines N3 is different from the first number of splines NI.

[0058] This achieves the above-mentioned keying function, this function preventing the left and right transition links from being interchanged, this function making it possible to ensure that the correct part is fitted in the vehicle assembly plant.

[0059] The second number of splines N2 is equal to the first number of splines NI. The right and left output planetary gears are then identical.

[0060] According to a particular embodiment, it is possible to choose NI = 27, N2 = 27 and N3 = 25.

[0061] Each of the first, second and third number of splines N1, N2, N3 is between 20 and 30.

[0062] Of course, as symbolically illustrated in [Fig.4], for the same coupling, the number of notches 54 in the female part is equal to the number of ribs / teeth 52 in the male part. In the male part, in section, the teeth 52 extend radially outwards, whereas in the female part, the teeth 53 extend radially inwards.

[0063] The intermediate shaft 1 is assembled by translation along its axis and insertion into the central sleeve of the output bevel gear 41 of the differential. The intermediate shaft extends along an axis Y1 parallel to the transverse axis Y of the vehicle.

[0064] As illustrated in [Fig.3], the intermediate shaft 1 comprises a first end E1 with a male spline 11 engaged (once mounted) in the satellite bevel gear 41 of the differential (second coupling), and a second end E2 with a female spline 12 capable of receiving the male spline 31 of the right transmission link (third coupling.

[0065] Concerning the intermediate shaft, the length L1 of the male spline is between 25 mm and 40 mm. The length L2 of the female spline is between 25 mm and 40 mm. The length L3 of the central portion can be between 60 mm and 120 mm, knowing that the total length of the intermediate shaft 1 is chosen such that it compensates for the offset to the left of the differential relative to the median longitudinal axis of the vehicle, so that the left and right transmission links have substantially or strictly the same length.

[0066] Depending on the vehicle track, the length of the transverse transmission links can range from 60 cm to 90 cm.

[0067] To complete the assembly, the left transmission link 2, in particular its splined rod 22, is inserted into the central sleeve of the left bevel gear of the differential, and the right transmission link 3, in particular its splined rod 31, is inserted into the female spline 12 of the intermediate shaft 1.

[0068] Further, a bearing device 62, visible in [Fig.2], is provided for supporting the intermediate shaft 1 on the side of its second end E2. An oil supply system makes it possible to lubricate this area, knowing that the sealing device 38 already mentioned, for example a seal arranged on the right transmission link, completes the lubrication system of this area.

[0069] Thanks to the provisions concerning the third coupling, the three spline couplings C1, C2 and C3 are lubricated and protected from possible stress corrosion.

Claims

Claims

1. Motor vehicle (7), equipped with an engine (6) configured to supply torque to wheels of the motor vehicle, via a central transmission with differential (4), and a set of transverse transmissions, the set of transverse transmissions comprising: - a left transmission link (2) driven by a left output of the differential, via a first spline coupling (C1), - an intermediate shaft (1) driven by a right output of the differential via a second spline coupling (C2), - and a right transmission link (3) driven by the intermediate shaft, via a third spline coupling (C3), characterized in that the first spline coupling comprises a first number of splines, the third spline coupling comprises a third number of splines, and the third number of splines is different from the first number of splines.

2. Motor vehicle according to claim 1, characterized in that the straight transmission link (3) comprises a specific seal (38).

3. Motor vehicle according to any one of claims 1 to 2, characterized in that the first number of splines is between 20 and 30 and the third number of splines is between 20 and 30.

4. Motor vehicle according to any one of claims 1 to 3, characterized in that the second spline coupling (C2) comprises a second number of splines, the second number of splines being equal to the first number of splines.

5. Motor vehicle according to any one of claims 1 to 4, characterized in that the intermediate shaft (1) comprises a first end (El) with a male spline engaged in a satellite pinion (41) of the differential, and a second end (E2) with a female spline (12) capable of receiving the male spline (31) of the right transmission link.

6. Motor vehicle according to any one of claims 1 to 5, characterized in that the first number of splines is greater than the third number of splines.

7. Motor vehicle according to any one of claims 1 to 6, characterized in that the third splined coupling (C3) is lubricated.

8. Motor vehicle according to any one of claims 1 to 7, characterized in that the left transmission link (2) and the right transmission link (3) have identical rigidity and length characteristics.

9. Motor vehicle according to any one of claims 1 to 8, characterized in that the motor (6) is an electric motor and the central transmission comprises a reducer.

10. Motor vehicle according to any one of claims 1 to 9, characterized in that each transmission link, right and left, comprises two homokinetic joints (34, 36).

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