FR3025458A1 - DIFFERENTIAL CROWN GEARBOX COUPLED TO A REDUCTION GEAR ASSEMBLY DRIVEN BY AN ELECTRIC MACHINE FOR A VEHICLE - Google Patents

Abstract

A gearbox (BV) equips a vehicle and includes input (AE) and output (AS) shafts comprising gear ratios (P11-P26) defining ratios, a differential (DF) comprising a gear (EC) ) meshing with a coupling pinion (PC) firmly fixed to the output shaft (AS), an assembly (EP) of at least two reduction gears (PR1-PR2) meshing between a pinion gear (PL) and the ring (CE) of the differential (DF), and an electric machine (ME) comprising an output shaft (A1) to which the connection pinion (PL) is fixedly fixed and able to rotate the latter (PL) so as to provide a selected torque to the differential (DF) via the pinion gear (PL), the set (EP) of reduction gears (PR1-PR2) and the ring gear (CE).

Description

The invention relates to gearboxes which are coupled to a differential and intended to be fitted to vehicles, possibly of the automotive type, in a gearbox that is coupled to a reduction gear unit driven by an electric machine. , and more specifically the supply of torque by the differentials of such gearboxes. In what follows, the term "gearbox" means a gearbox of the mechanical type, that is to say whose gear changes are controlled by the driver of the vehicle by means of a gearbox. control, an automatic type gearbox. Due to the limited nature of the earth's hydrocarbon stockpiles and the need to reduce man-made pollution, many avenues are being explored to reduce the fuel consumption of motor vehicles. One of these tracks is to improve the energy efficiency of the vehicle powertrain. To do this, one can for example use at least one machine (or motor), electric or hydraulic 20 or compressed air, in the transmission chain of the vehicle to increase the torque provided by the engine. Such a machine may, for example, be additional and dedicated to the supply of torque, and in this case it must be associated with energy storage means. Unfortunately, the addition of electric machine (s) increases the complexity, the size and the cost of the powertrain and the transmission chain. Alternatively, the machine may be a member already present in the vehicle, and which is adapted to provide at least two functions including the additional torque supply. Unfortunately, this machine which is nothing other than the alternator is relatively inefficient in terms of traction or propulsion capability.

The object of the invention is therefore notably to propose an alternative solution offering a good traction or propulsion capacity while being simple, compact and inexpensive, and if possible inducing only slight modifications of the box. gear or member (s) 5 secured to the latter. It proposes for this purpose a gearbox intended to equip a vehicle and comprising an input shaft and at least one output shaft each comprising gear ratios for defining different selectable ratios, and a differential comprising a crown meshing a coupling pinion fixedly secured to one end of the output shaft. This gearbox is characterized by the fact that it also comprises: a set of at least two reduction gears (or reducers) ensuring a meshing between a pinion of connection and the ring gear of the differential, and an electric machine comprising an output shaft which is fixedly secured to the connecting pinion and adapted to rotate the latter to provide a torque selected at the differential via the pinion, the set of reduction gears and the differential ring. Thanks to the invention, one obtains a simple and inexpensive "electric hybridization" of the powertrain of a vehicle via the differential ring. The gearbox according to the invention may comprise other characteristics that can be taken separately or in combination, and in particular: its assembly may comprise a first reduction gear meshing with the connecting pinion, and a second reduction gear meshing with the first reduction gear and the differential crown; it may comprise a casing at least partially housing the input and output shafts with their ratio gears, the set of reduction gears, a part of the differential comprising the crown, and the connecting pinion; it may comprise another housing housing a complementary part of the differential and constituting a closing interface for the gearbox, on the side of the end of the output shaft, and for a clutch of the vehicle which provides a coupling between the input shaft and a drive shaft of a vehicle engine. The invention also proposes a vehicle, possibly of automobile type, and comprising a gearbox of the type of that presented above.

Other features and advantages of the invention will become apparent upon examination of the following detailed description, and the accompanying drawings, in which: FIG. 1 schematically and functionally illustrates an embodiment of a gearbox according to the invention, coupled to a thermal motor via a clutch, and to a differential, Figure 2 schematically and functionally illustrates, in a front view (on the clutch side), an example of positioning of the reduction gears, differential and input and output shafts of the gearbox of FIG. 1, with respect to the electric motor, and FIG. 3 schematically and functionally illustrates, in a view from above, an example of positioning of the reduction gears, differential and input and output shafts of the gearbox of Figure 1, relative to the electric motor. The invention aims in particular to provide a gearbox 25 BV coupled to a differential DF and intended to equip a motor vehicle (s) thermal (s) MT. In what follows, it is considered, by way of non-limiting example, that the vehicle is automotive type. This is for example a car. But the invention is not limited to this type of vehicle. It concerns indeed any vehicle comprising at least one clean engine to provide torque to a gearbox. Therefore, the invention relates to land vehicles, river or sea vehicles, and aircraft.

Furthermore, it will be considered in the following, by way of non-limiting example, that the gearbox BV is manual manual. But the invention is not limited to this type of gearbox. It relates in fact to gearboxes of the mechanical type (as for example those called manual 5 conventional, so-called robotics and those called dual clutch (or DCT)), and gearboxes type automatic (ie ie having internal hydraulic management of multiple hydraulic clutches). FIG. 1 shows schematically an exemplary embodiment of a gearbox BV according to the invention, coupled to a thermal engine MT of a vehicle, here via an EM clutch, and to a differential DF. The thermal engine MT comprises a crankshaft (not shown) which defines an engine shaft AM coupled to the clutch EM to provide torque for the driving wheels of the vehicle.

For example, the clutch EM comprises in particular a flywheel securely fixed to the drive shaft AM and a clutch disc fixedly secured to the input shaft AE of the gearbox BV. In what follows, by way of non-limiting example, the clutch EM is of the conventional type, and therefore is directly controlled by the driver of the vehicle via a control member (such as, for example, the pedal clutch). But the clutch could be "hybrid" control, that is to say, coupled to its control member via an electrical actuation module. As illustrated in FIG. 1, a gearbox BV, according to the invention, comprises at least one input shaft AE, at least one output shaft AS, a coupling gear PC, an assembly EP of at least two reduction gears (or reducers) PRk, an electric machine ME and a pinion connection PL. The gearbox BV comprises at least one input (or primary) shaft AE and at least one output (or secondary) shaft AS intended to be coupled to each other. The input shaft AE is intended to receive the torque of the heat engine MT via the clutch EM. The output shaft AS is intended to receive the torque of the heat engine MT via the input shaft AE in order to communicate it to a differential DF which is coupled to two transmission shafts ATn (n = 1 or 2). to which are coupled driving wheels of the vehicle. The input shaft AE and the output shaft AS each comprise gear wheels Pij which are intended to participate together selectively in the definition of different selectable ratios (or speeds) of the gear box. BV speeds, including N forward gears. The index i denotes here the ratio gears borne by the input shaft AE (i = 1) and the ratio gears carried by the output shaft AS (i = 2). The index j here denotes the different forward gears. Therefore, j = 1 to N.

It will be noted that in the exemplary embodiment illustrated in a non-limiting manner in the single figure, the gearbox BV comprises six (N = 6) forward gears. But it could have a number N more or less important forward gears, and for example four, five or seven.

The AE input and AS output shafts and their Pij ratio gears are housed in a space which is defined by at least one casing C1, and preferably two (C1 and C1 ') as illustrated in a non-limiting manner on the single Fig. In the example illustrated, the housing C1 partially houses the AE input and output shafts AS with their gear Pij.

The coupling between the output shaft AS and the differential DF is via a PC coupling pinion. The latter (PC) is more precisely secured to an end EA of the output shaft AS and meshes a CE ring of the differential DF. This differential DF is for example housed at least partially in the casing Cl of the gearbox BV, as shown in non-limiting manner in FIG. 1. It will be noted that in the nonlimiting example of FIG. 1 a part of the differential DF, including the crown CE, is housed in the housing C1, while the complementary portion of the differential DF is housed in a housing C2 which serves, here, closing interface for the gearbox BV, on the side of the EA end of its output shaft AS, and for the clutch EM. This makes it possible to minimize the size and reduce the number of parts secured to the casings of the BV gearbox.

For example, this differential DF may comprise a differential case fixedly secured to its crown CE, a satellite carrier pin secured to the differential housing to be rotated by the EC ring and to which are secured at least two pinions satellites 5 which meshes two planetary gears secured to the two shafts AT1 and AT2 which are responsible for driving the drive wheels of the vehicle. As it appears better in FIGS. 2 and 3, the assembly EP comprises at least two reduction gears (or reducers) PRk loaded 10 to ensure a meshing between a pinion PL connected to an output axis Al and the crown CE differential DF. This EP assembly is intended to achieve a predefined gear ratio of the torque between the pinion PL and differential DF. Moreover, it induces a reduction in speed between the electric motor ME and the differential DF, in a way that is less expensive than an epicyclic gear train. It will be noted that in the embodiment illustrated in non-limiting manner in FIGS. 1 to 3, the assembly EP comprises first PR1 and second PR2 reduction gears (k = 1 or 2). The first reduction gear PR1 meshes with the link gear PL, and the second reduction gear PR2 meshes with the first reduction gear PR1 and the ring gear CE with the differential DF. But the number of reduction gears PRk of the set EP can take any value greater than or equal to two. Thus, this number can be equal to three or four or more. It will be noted that this number depends on the capacities of the electric motor ME in terms of the maximum permissible speed and the traction / propulsion performance expected with this electric motor ME. A significant gearing will allow low revs of the electric motor ME but modest performance in terms of traction / propulsion. For example, the first PR1 and second PR2 reduction gears 30 can advantageously be housed in the casing C1 of the gearbox BV, in particular when the ring CE of the differential DF is also housed in this casing C1. For example, the rotation first PR1 and second PR2 reduction gears in the housing C2 can be done by bearings bearing 3025458 7. This arrangement makes it possible to minimize the bulk and to reduce the number of parts secured to the casings of the gearbox BV. Indeed, it does not require additional casing or additional holding parts, and all machining maintenance and attachment of the electric motor ME and all bearings bearing bearings are axial, and therefore machinable on common means to AE input shaft and AS output shaft bearings. Note that this arrangement also brings a gain in terms of mounting components in the gearbox BV with unified means.

The electric machine ME has an output axis A1 to which the link gear PL is fixedly secured. It is furthermore arranged in such a way as to rotate the link pinion PL in order to provide a selected torque to the differential DF via this pinion PL, the set EP of reduction gears PRk and the ring CE.

It will be understood that when the electric machine ME is used, it drives in rotation the output axis A1, which induces a rotational drive of the pinion PL. The rotation of the connecting pinion PL is then transmitted to the assembly EP which transmits it by meshing with the ring CE of the differential DF. The torque produced by the electric machine ME is thus transferred to the differential DF where it completes the "main" torque supplied by the thermal engine MT via the input AE and output AS shafts. It will be noted that in one option it is possible to have an "all electric" operating mode in which only the electric machine ME supplies torque to the differential DF. But this option requires the EM clutch to be hybrid controlled (and thus coupled to its control member (such as the clutch pedal) via an electric actuation module), so that the motor shaft AM can be temporarily decoupled from the input shaft AE by EM clutch. In this case, the differential DF may receive the torque of the heat engine MT 30 and / or the torque of the electric machine ME simultaneously or independently of one another. It should also be noted that the gear ratio offered by the EP assembly complements that offered by the electric machine ME.

The electric machine ME may, for example, be fixedly secured to the casing Cl of the gearbox BV. In this case, the pinion PL that carries the output axis Al is preferably housed in the housing C1 substantially in the plane where the assembly EP and the ring 5 CE are installed. Note that in an alternative embodiment not shown the pinion connection PL, the EP assembly and the DF differential could be housed in an additional housing secured to the casing C1 of the gearbox BV or the housing C2 serving as interface of closing between the clutch EM and gearbox BV. The invention is advantageous because it allows "electric hybridization" of the powertrain of a vehicle via the differential ring, simple, inexpensive and offering good traction or propulsion, without significantly increasing the complexity of the 15 powertrain.

Claims (6)

REVENDICATIONS1. Gearbox (BV) adapted to equip a vehicle and comprising an input shaft (AE) and at least one output shaft (AS) each comprising gear ratios (Pij) for defining different selectable ratios, and a differential (DF) comprising a ring (CE) meshing with a coupling pinion (PC) fixedly fixed to one end (EA) of said output shaft (AS), characterized in that it further comprises i) a set (EP) of at least two reduction gears (PRk) providing a meshing between a connecting pinion (PL) and said ring (CE) of the differential (DF), and ii) an electric machine (ME) comprising an output axis (A1) which is fixedly secured to said pinion gear (PL) and adapted to rotate the latter (PL) to provide a selected torque to said differential (DF) via said pinion connection (PL), said set (EP) of reduction gears (PRk) and said ring (CE). 2. Gearbox according to claim 1, characterized in that said assembly (EP) comprises a first reduction gear (PR1) meshing said connecting gear (PL), and a second reduction gear (PR2) meshing said first gear of reduction (PR1) and said ring (CE). 3. Gearbox according to one of claims 1 and 2, characterized in that it comprises a housing (C1) at least partially housing said input shafts (AE) and output (AS) with their gears report (Pij), said set (EP) reduction gears (PRk), a part of the differential (DF) comprising said ring (CE), and said pinion connection (PL). 4. Gearbox according to claim 3, characterized in that it comprises another housing (C2) housing a complementary portion of said differential (DF) and constituting a closing interface for said gearbox (BV), on the side of said end (EA) of said output shaft (AS), and for a clutch (EM) of said vehicle coupling between said input shaft (AE) and a drive shaft (AM) of a heat engine (MT) of said vehicle. 3025458 10 5. Vehicle, characterized in that it comprises a gearbox (BV) according to one of the preceding claims. 6. Vehicle according to claim 5, characterized in that it is automotive type.