FR3097930A1 - Transmission device for electric or hybrid vehicle - Google Patents

Abstract

The invention relates to a transmission device (1,16,32) for a vehicle comprising an electric motor (2,17,33), the device comprising a casing (4,19,35) containing the electric motor, the electric motor being formed by a stator (5,20,36) fixed in rotation relative to the casing and a rotor (6,21,37) movable in rotation relative to the casing, a reduction gear (3,18,45) receiving the torque supplied by the rotor comprising a plurality of intermediate shafts (12,27,48), the device further comprising at least a first bearing (14,28,47) mounted on the rotor and on one of the intermediate shafts, the first bearing allowing relative rotation of the rotor and of one of the intermediate shafts relative to each other and vice versa, one of the intermediate shafts and the rotor rotating in the same direction of rotation. Figure for abstract: [Fig. 1]

Description

Transmission device for electric or hybrid vehicle

Technical field of the invention

The invention relates to a transmission device for a motor vehicle, in particular for a motor vehicle of the electric or hybrid type.

State of the prior art

A hybrid or electric vehicle comprises at least one electric motor which is formed by a stator and a rotor. The stator is mounted fixed in rotation on a casing while the rotor is mounted mobile in rotation relative to the stator. The rotor is mounted to move relative to the casing by a bearing and is connected to a reduction system so as to allow the speed of rotation and the torque of the electric propulsion machine to be adapted to the speed required for the vehicle. Indeed, the speeds of an electric motor can be high, greater than or equal to 15,000 revolutions per minute.

The bearings supporting the rotor are mounted directly in the housing. The size of the bearings can be large and can therefore limit the maximum speed of rotation. In addition, due to the connection of the rotor with the casing, the speed of rotation of the rotor is limited by the capacities of the bearing.

The object of the present invention is to provide a transmission device comprising an electric motor whose speed of rotation is not limited by its connection with the casing.

The invention achieves this, according to one of its aspects, by means of a transmission device for a vehicle comprising an electric motor, the device comprising

an electric motor, the device comprising

a casing containing the electric motor,

the electric motor being formed by a stator fixed in rotation relative to the casing and a rotor movable in rotation relative to the casing,

a reducer receiving the torque supplied by the rotor comprising a plurality of intermediate shafts including a main intermediate shaft, the device further comprising

at least a first bearing mounted on the rotor and on the main intermediate shaft, the first bearing allowing relative rotation of the rotor and of the main intermediate shaft relative to each other and vice versa, the main intermediate shaft and the rotor rotating in the same direction of rotation. Preferably, there are at least two first bearings mounted on the rotor and on the main intermediate shaft.

According to the invention, it is one of the shafts of the reducer which is used to support the rotor and which will be referred to below as the main intermediate shaft. Thus, by main intermediate shaft or support shaft is meant shaft which is intended to be linked to the rotor by the first bearing.

According to the invention, the rotor is no longer connected directly but indirectly to the casing via the main intermediate shaft. The rotational speed of the bearings is therefore no longer directly linked to the speed of the rotor. The speed of rotation of the rotor can thus be particularly increased.

By plurality of intermediate shafts is meant a main intermediate shaft and at least one secondary intermediate shaft, the main intermediate shaft being the one which is linked to the rotor by a first bearing. In one example, the reducer has a single secondary intermediate shaft but could have more.

In a preferred example, the rotor and the main intermediate shaft are coaxial. In particular, the rotor extends along a first axis and the main intermediate shaft extends along a second axis, the main intermediate shaft is chosen in such a way that the first axis coincides with the second axis.

The speed limitation of a bearing depends in part on the size of the bearing. The larger the bearing, the more its maximum speed of rotation will be limited.

The rotational speed of the support shaft (VS) depends on the rotational speed of the rotor (VE) and the reduction ratio (Ra) obtained by the gearbox. The rotational speed of the support shaft bearings is:

VS = VE / Ra.

The rotor speed (VE) is defined with respect to the stator which is fixed to the housing. The speed seen by the bearings supporting the rotor is a relative speed between the rotor and the main intermediate shaft. It is therefore possible to write the following equation:

VE/S = VE - VS

VE/S = VE – VE/Ra

VE/S = VE x (1-1/Ra)

The speeds of the rotor bearings (VE/S) and of the main intermediate shaft (VS) are therefore a function of the reduction ratio (Ra).

The position of the rotor bearing directly on the main intermediate shaft allows a reduction in the size of the latter favoring small bearing sizes and therefore with higher speed capacities.

In an example, for identical bearings that can withstand a maximum speed (Vmax) and with a ratio (Ra) of 2, it is possible to reach a rotor speed (VE) equal to 2xVmax.

According to the invention, any reducer can be used. The shaft (or main intermediate shaft) of one of the gearbox shafts must be coaxial with the motor, rotate in the same direction as the rotor and have a reduction ratio suitably chosen to distribute the speed according to the characteristics of the bearings.

According to one embodiment of the invention, the main intermediate shaft is connected to the housing by at least one second bearing.

According to one embodiment of the invention, the rotor extends along a first axis (X, X') and the main intermediate shaft extends along a second axis, the main intermediate shaft is chosen in such a way that the first axis coincides with the second axis.

According to one embodiment of the invention, the rotor forms a hollow shaft and the main intermediate shaft is mounted coaxially inside the rotor.

According to one embodiment of the invention, the first bearing is positioned inside the hollow shaft.

According to one embodiment of the invention, the main intermediate shaft is rotatably mounted on the housing via at least one second bearing. Preferably, at least two second bearings are provided.

According to one embodiment of the invention, the device is located between the electric motor and at least one wheel of the vehicle while being capable of connecting the electric motor to the wheel of the vehicle, the device further comprising a differential for varying the speed between two laterally opposite wheels.

The invention also relates to the use of one of the shafts of the reduction gear to support the rotor of a torque transmission device as described previously.

The invention will be better understood, and other aims, details, characteristics and advantages thereof will appear more clearly during the following description of several embodiments of the invention, given solely by way of illustration and not limitation, with reference to the appended figures.

represents a diagram of a transmission device, according to a first embodiment of the invention, and

represents a diagram of a transmission device, according to a second embodiment of the invention;

represents a diagram of a transmission device, according to a third embodiment of the invention.

The shows a diagram of a transmission device 1 comprising an electric motor 2. This transmission device 1 can also comprise a heat engine, not shown, and be part of an assembly for a hybrid vehicle.

The transmission device 1 also comprises a reduction gear 3 and a casing 4. The casing 4 envelops the electric motor 2 as well as the reduction gear 3. The electric motor 2 comprises a stator 5 and a rotor 6, the stator 5 and the rotor 6 being mounted coaxial with each other around an axis of elongation X. The stator 5 is fixed in rotation with respect to the casing 4 while the rotor 5 is mounted so as to be able to rotate with respect to the casing 4 by the intermediary of a main intermediate shaft 12.

The reducer 3 comprises in this example several pinions such as 7, 8, 9 and 113 meshing to transmit the torque supplied by the electric motor 2 to the wheels of the vehicle (not shown). The pinions of the reducer 3 are for example configured so that a single ratio is possible, or alternatively so that two distinct ratios or three distinct ratios are possible.

In this example, four sprockets such as 7, 8, 9, and 113 mesh with each other.

The rotor 6 comprises a hollow shaft 13 linked to the pinion 113 capable of cooperating with one of the other pinions 7 of the reducer 3.

The shaft 13 cooperates by gearing a first pinion 113 with a second pinion 7 connected in rotation with a first secondary intermediate shaft 10. This first secondary intermediate shaft 10 is connected to the housing 4 by two bearings such as 11 at its two ends . A third pinion 8 is also linked to this first secondary intermediate shaft 10 while being meshed with a fourth pinion 9. This fourth pinion 9 is linked in rotation to a main intermediate shaft 12. This main intermediate shaft 12 is housed inside of the rotor 6 passing through the shaft 13. The main intermediate shaft 12 is connected to the rotor 6 via two bearings such as 14 which are positioned between the hollow shaft 13 of the rotor 6 and the shaft main intermediary 12.

Two other bearings such as 15 are positioned between the main intermediate shaft 12 and the casing 4, shown here in an example at the two ends of this same main intermediate shaft 12. Other pinions as shown in dotted lines in FIG. can mesh with the fourth gear 9.

Thus, the torque is transmitted to the main intermediate shaft 12 from the rotor 6 via the shaft 13 through the various pinions 7, 8, 9 and 113 and the first secondary intermediate shaft 10 of the reducer 3.

The shows a diagram of a transmission device 32 according to a second embodiment of the invention. According to this second embodiment, the transmission device 32 represents comprises an electric motor 33. As for the device 1 of the previous example, this transmission device 32 can also comprise a heat engine, not shown, and be part of a set for a hybrid vehicle.

The transmission device 32 also comprises a reduction gear 34 and a casing 35. The casing 35 envelops the electric motor 33 as well as the reduction gear 34. The electric motor 33 comprises a stator 36 and a rotor 37, the stator 36 and the rotor 37 being mounted coaxial with each other around an axis of elongation X''. The stator 36 is fixed in rotation with respect to the casing 35 while the rotor 37 is mounted mobile in rotation with respect to the casing 35 via a main intermediate shaft 48.

A bearing such as 117 is positioned between the main intermediate shaft 48 and the casing 35, shown here in an example at one of the ends of this same main intermediate shaft 48.

The reduction gear 34 comprises in this example several pinions such as 38, 39, 40 and 44 meshing to transmit the torque supplied by the electric motor 33 to the wheels of the vehicle (not shown). As before, the pinions of the reducer 34 are for example configured so that a single ratio is possible, or alternatively so that two distinct ratios or three distinct ratios are possible.

In this example, four sprockets mesh with each other.

The rotor 37 comprises a hollow shaft 41 and which has a first wheel 38 capable of cooperating with one of the other pinions of the reduction system 34.

The hollow shaft 41 cooperates by gearing a first pinion 38 with a second pinion 39 which is connected in rotation with a first secondary intermediate shaft 42. This first secondary intermediate shaft 42 is connected to the housing 35 by two bearings such as 43 to its two ends. A third pinion 40 is also linked to this first secondary intermediate shaft 42 while being meshed with a fourth pinion 44. This fourth pinion 44 is linked in rotation to a differential 45. In particular, this fourth pinion 44 is linked to the shaft main intermediate 48 which is coaxial with the hollow shaft 41 of the rotor 37. The differential 45 is housed inside the casing 35.

The differential 44 is connected to the casing 35 via two bearings such as 46.

Two other bearings such as 47 are positioned between the main intermediate shaft 48 and the hollow shaft 41 of the rotor 37.

Thus, the torque is transmitted to the main intermediate shaft 48 from the rotor 37 via the shaft 41 through the various pinions 38,39,40 and 44 and the first secondary intermediate shaft 42 of the reduction system 3.

The shows a diagram of a transmission device 16 according to another embodiment of the invention. According to this other embodiment, the transmission device 16 represents comprises an electric motor 17. As for the device 1 of the previous example, this transmission device 16 can also comprise a heat engine, not shown, and be part of a set for a hybrid vehicle.

The transmission device 16 also comprises a reduction gear 18 and a casing 19. The casing 19 envelops the electric motor 17 as well as the reduction system 18. The electric motor 17 comprises a stator 20 and a rotor 21, the stator 20 and the rotor 21 being mounted coaxial with each other around an axis of elongation X'. The stator 20 is fixed in rotation with respect to the casing 19 while the rotor 21 is mounted so as to be able to rotate with respect to the casing 19 via a main intermediate shaft 27.

The reducer 18 comprises in this example several pinions such as 22, 23, 24 and 114 meshing to transmit the torque supplied by the electric motor 17 to the wheels of the vehicle (not shown). As before, the pinions of the reducer 18 are for example configured so that a single ratio is possible, or alternatively so that two distinct ratios or three distinct ratios are possible.

In this example, four sprockets mesh with each other.

The rotor 21 comprises a hollow shaft 31 capable of cooperating with one of the pinions of the reduction system 18, for example by means of a spline or by direct cutting of a wheel on the latter. Other assembly methods can be envisaged between the hollow shaft 31 and a first pinion of the reducer 18.

The hollow shaft 31 cooperates by gearing a first pinion 114 with a second pinion 22 linked in rotation with a first secondary intermediate shaft 25. This first secondary intermediate shaft 25 is linked to the housing 19 by two bearings such as 26 at its two ends. A second pinion 23 is also linked to this first secondary intermediate shaft 25 while being meshed with a fourth pinion 24. This fourth pinion 24 is linked in rotation to the main intermediate shaft 27 via a differential 30. This main intermediate shaft 27 is housed inside the rotor 21 passing through the secondary intermediate shaft 25. The main intermediate shaft 27 is connected to the rotor 21 via two bearings such as 28 which are positioned between the hollow shaft 31 of rotor 21 and the main intermediate shaft 27.

Two other bearings such as 29 are positioned between the main intermediate shaft 27 and the casing 19, shown here in an example at the two ends of this same main intermediate shaft 27. Thus, the torque is transmitted to the main intermediate shaft 27 from the rotor 21 via the hollow shaft 31 through the various pinions 22, 23, 24 and 114 and the first secondary intermediate shaft 25 of the reduction system 18.

According to this example, the torque at the output of the reducer 18 is distributed between different wheels (not shown) of this train by the differential 30. To do this, at the output of the differential 30, the torque is distributed between a first shaft or main intermediate shaft 27 and a second shaft or output shaft 115. Another bearing such as 116 is disposed between the housing 19 and the output shaft 115.

Claims (8)

Transmission device (1,16,32) for a vehicle comprising an electric motor (2,17,33), the device comprising
a housing (4,19,35) containing the electric motor,
the electric motor supplying a torque and being formed by a stator (5,20,36) fixed in rotation with respect to the casing and a rotor (6,21,37) movable in rotation with respect to the casing,
a reduction gear (3,18,45) receiving the torque supplied by the rotor comprising a plurality of intermediate shafts including a main intermediate shaft (12,27,48), the device further comprising
at least a first bearing (14,28,47) mounted on the rotor and on the main intermediate shaft, the first bearing allowing relative rotation of the rotor and the main intermediate shaft with respect to each other and conversely, the main intermediate shaft and the rotor rotating in the same direction of rotation. Device according to claim 1, wherein the main intermediate shaft is connected to the housing by at least one second bearing (117,29,15). Apparatus according to claim 1 or claim 2, wherein the rotor and the main intermediate shaft are coaxial. Device according to one of claims 1 to 3, wherein the rotor forms a hollow shaft (13,31,41) and the main intermediate shaft is mounted coaxially inside the rotor. Device according to claim 4, wherein the first bearing is positioned within the hollow shaft. Device according to one of claims 1 to 5, wherein the main intermediate shaft is rotatably mounted on the housing via at least one second bearing (15,29,117). Device according to one of claims 1 to 6, in which the device is located between the electric motor and at least one wheel of the vehicle while being able to connect the electric motor to the wheel of the vehicle, the device further comprising a differential (30) to vary the speed between two laterally opposed wheels. Use of one of the shafts of the reduction system to support the rotor of a device according to one of the preceding claims.