FR3077536A1 - TWO-SPEED TRANSMISSION DEVICE FOR ELECTRIC VEHICLE - Google Patents

Abstract

The invention relates to a two-speed transmission device (T) for an electric vehicle equipped with an electric machine (M) capable of operating alternately in a motor mode or in a generator mode, the transmission comprising: a primary shaft ( 1) adapted to be connected to the electric machine (M), - a secondary shaft (2) adapted to be connected to the wheels (R1, R2) of the vehicle, - a first gear (10) corresponding to the first gear and comprising a first driving gear (11) disposed on the primary shaft (2) and a first driven gear (12) disposed on the secondary shaft (2) and meshing permanently with the first driving gear (11), - a second gear ( 20) corresponding to the second speed and comprising a second driving gear (21) disposed on the primary shaft (1) and a second driven gear (22) disposed on the secondary shaft (2) and meshing permanently with the second gear leading (21), - a first neck device range (C1) associated with the first gear (4), - a second coupling device (C2) associated with the second gear (5), the first coupling device (C1) and the second coupling device (C2) are located at a different end of the secondary shaft (2) and / or the primary shaft (1).

Description

Two-speed transmission device for an electric vehicle

The present invention relates to the field of two-speed transmissions intended for use on electric motor vehicles. By electric motor vehicle is meant within the meaning of the invention all vehicles which use an electric machine as the main engine, the electric machine being the only driving machine (purely electric vehicles) or associated with an internal combustion engine (hybrid vehicles).

Transmissions at more than one speed, in particular two-speed transmissions, for use on electric vehicles are known and have the advantage, compared to single-speed transmissions, of allowing the electric machine to operate at a number optimum revolutions per minute, i.e. the number of revolutions per minute corresponding to the maximum output of the machine. This advantage applies both to the engine operating mode, in which the electric machine operates as an engine to generate the power required to move the vehicle, and to the generator operating mode, in which the electric machine operates as a generator to convert the kinetic energy of the vehicle into electrical energy.

In order to avoid an interruption in the transmission of the torque during the transition from first speed to second speed in a two-speed transmission, it is known in the prior art the use of at least one clutch associated with at least a pinion driven by a first gear (first speed) or a second gear (second speed). More specifically, the two-speed transmissions known from the prior art comprise a primary shaft, a secondary shaft, a first speed gear comprising a first driving pinion carried by the primary shaft and a first driven pinion carried by the secondary shaft and permanently meshing with the first driving pinion, a second speed gear comprising a second driving pinion carried by the primary shaft and a second driven pinion carried by the secondary shaft and permanently meshing with the second driving pinion. The clutch for selecting the first gear or the second gear is generally placed on the primary shaft in order to couple or uncoupled the first driving pinion or the second driving pinion. In addition to this clutch, a freewheel system is associated and is arranged on the secondary shaft between the first driven pinion and the second driven pinion. This architecture is not optimal in the case where the vehicle operates in reverse because the gear associated with the freewheel will not be able to transmit the torque. Likewise, when the engine operates as a generator, only a torque path passing through the first gear or the second gear is possible, which limits the vehicle's recharging capacities.

The invention aims to remedy the aforementioned problems by benefiting from a two-speed transmission device for an electric vehicle allowing full use of the two speeds, both in forward and reverse but also in engine operation and in operation generator.

The invention achieves this, according to one of its aspects, thanks to a two-speed transmission device for an electric vehicle equipped with an electric machine capable of operating alternately according to a motor mode or according to a generator mode, the transmission comprising :

- a primary shaft capable of being connected to the electric machine,

- a secondary shaft capable of being connected to the wheels of the vehicle,

a first gear corresponding to the first speed and comprising a first driving pinion disposed on the primary shaft and a first driven pinion disposed on the secondary shaft and permanently meshing with the first driving pinion,

a second gear corresponding to the second speed and comprising a second driving pinion arranged on the primary shaft and a second driven pinion arranged on the secondary shaft and permanently meshing with the second driving pinion,

- a first coupling device associated with the first gear,

- a second coupling device associated with the second gear, the first coupling device and the second coupling device are located at a different end from the secondary shaft and / or from the primary shaft.

This two-speed transmission device architecture for an electric vehicle also makes it easier to access the coupling devices and their actuators in the event of maintenance.

Within the meaning of the invention, driven pinions and driving pinions are understood in the direction of transmission from the electric machine to the wheels of the vehicles, that is to say when the electric machine is in engine operation.

According to one aspect of the invention, the first coupling device and the second coupling device are friction clutches.

Advantageously, the first coupling device and the second coupling device are wet multi-disc clutches. "Wet" means that the clutch discs are immersed in the oil of the transmission device which lubricates and cools all of the internal mechanical components.

Alternatively, the first coupling device and the second coupling device are dry single disc clutches.

According to an additional aspect of the invention, the first coupling device and the second coupling device are controlled in order to finely manage the torque transmitted by each of them. The coupling devices can be controlled for example as a function of parameters such as the internal temperature of the transmission device, the speed of rotation and / or the torque of the output shaft of the electric machine.

According to another characteristic of the invention, the device comprises a tertiary shaft connected to the secondary shaft by means of a third gear comprising a third driving pinion disposed on the secondary shaft and a third driven pinion disposed on the tertiary tree and permanently meshing with the third driving pinion.

According to a feature of the invention, the third driving pinion is arranged axially between the first driven pinion and the second driven pinion.

According to a characteristic of the invention, the first coupling device or the second coupling device is of the normally closed type. According to this characteristic, the primary shaft or the secondary shaft comprises a locking device in the parking position. Preferably, the locking device in the parking position is linked to the primary shaft so as to allow a more compact design of the locking device because the torque on the primary shaft is lower than on the secondary shaft.

In an alternative embodiment of the invention, the first coupling device and the second coupling device are of the normally closed type.

According to another alternative embodiment, the first coupling device and the second coupling device are of the normally open type. According to this variant, the secondary shaft comprises a locking device in the parking position.

According to another additional characteristic of the invention, a dog clutch or a synchronizer is linked to the first driving pinion or to the second driving pinion.

According to an additional feature of the invention, a support bearing is located at each end of the primary shaft and of the secondary shaft.

According to one aspect of the invention, the first coupling device and the second coupling device are located between the support bearing and the first gear or the second gear.

According to an additional aspect of the invention, a differential is connected to the secondary shaft or to the tertiary shaft by means of a differential gear, said differential being able to be connected to the wheels of the vehicle.

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

FIG. 1 is a schematic view of a two-speed transmission device according to a first embodiment of the invention,

FIG. 2 is a schematic view of a two-speed transmission device according to a second embodiment of the invention,

FIG. 3 is a schematic view of a two-speed transmission device according to a third embodiment of the invention,

- Figure 4 is a schematic view of a two-speed transmission device according to a fourth embodiment of the invention.

In all the figures, the elements having identical functions bear the same reference numbers.

The following embodiments are examples. Although the description refers to several embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the characteristics apply only to a single embodiment. Simple features of different embodiments can also be combined to provide other embodiments.

In relation to FIGS. 1 to 4, we observe the essential elements of a kinematic chain of a vehicle powered by an electric machine M connected to the wheels R1, R2 of the vehicle by means of a two-speed transmission device T. The two-speed transmission device T acts as a reducer between the electric machine M and the wheels R1, R2 of the vehicle, that is to say that it aims to modify the speed and / or torque ratio between the output shaft of the electric machine M and the wheels R1, R2 of the vehicle.

The electric machine M used can for example be a synchronous electric machine with permanent magnets operating at low voltage, that is to say 48 Volts.

The two-speed transmission device T in FIG. 1 comprises a primary shaft 1 which is coupled to the output shaft of the electric machine M. This coupling is constant velocity and can be any type of mechanical coupling between two shafts, such as for example a coupling with splines.

In a variant not shown, the primary shaft 1 can be the same shaft as the output shaft of the electric machine M.

The transmission device T also includes a secondary shaft 2 and a tertiary shaft 3. The tertiary shaft 3 is able to be connected to a differential D itself connected to the wheels R1, R2 of the vehicle. The differential D has the function of rotating the wheels R1, R2 of the vehicle at different speeds.

A first gear 10 corresponding to the first speed comprises a first driving pinion 11 arranged on the primary shaft 1 and a first driven pinion 12 arranged on the secondary shaft 2. The first driving pinion 11 and the first driven pinion 12 permanently mesh .

A second gear 20 corresponding to the second speed comprises a second driving pinion 21 disposed on the primary shaft 1 and a second driven pinion 22 disposed on the secondary shaft 2. The second driving pinion 21 and the second driven pinion 22 permanently mesh .

The first driving pinion 11 and the second driving pinion 21 are fixedly mounted on the primary shaft 1. The first driven pinion 12 and the second driven pinion 22 are idly mounted on the secondary shaft 2 by means of needle bearings, that is, they can rotate relative to the secondary shaft 2.

A third gear 30 comprises a third driving pinion 31 arranged on the secondary shaft 2 and a third driven pinion 32 arranged on the tertiary shaft 3. The third driving pinion 31 is fixedly mounted on the secondary shaft 2 and the third driven pinion 32 is fixedly mounted on the tertiary shaft 3. The third driving pinion 31 is disposed axially between the first driven pinion 12 and the second driven pinion 22. The third driving pinion 31 and the third driven pinion 32 permanently mesh.

A fourth gear corresponding to a gear 40 of differential D comprises a last driving pinion 41 disposed on the tertiary shaft 3 and a last driven pinion 42 corresponding to the input of the differential D. The last driving pinion 41 is mounted fixed on the tertiary tree

3. The last driving pinion 41 and the last driven pinion 42 permanently mesh.

The four gears 10, 20, 30, 40 are oriented in parallel. Similarly, the three shafts 1, 2, 3 are oriented in parallel. The different pinions 11, 12, 21, 22, 31, 32, 41, 42 have straight teeth. As a variant, these pinions can have oblique, helical or herringbone teeth.

Two torque paths are therefore possible between the output shaft of the electric machine M and the wheels R1, R2 of the vehicle. A first torque path passing through the first gear 10 then the third gear 30 and finally the differential gear 40. A second torque path passing through the second gear 20 then the third gear 30 and finally the differential gear 40 D.

In order to select the appropriate torque path according to the road conditions (ascent, descent, highway driving, city driving ...), two coupling devices C1, C2 are arranged in the transmission device T in order to select the suitable torque path passing either through the first gear 10 or through the second gear 20.

A first coupling device C1 is associated with the first gear 10, that is to say the first speed. In the case of FIG. 1, the first coupling device C1 is linked to the first driven pinion 12. The coupling device C1 is associated with the low speed, that is to say the speed making it possible to start the vehicle or to face the reliefs of the road like for example the climbs. The reduction ratio between the first driving pinion 11 and the first driven pinion 12 can for example be between 2 and 3.

A second coupling device C2 associated with the second gear 20, that is to say the second speed. In the case of FIG. 1, the second coupling device C2 is linked to the second driven pinion 22. The coupling device C2 is associated with the high speed, that is to say the speed allowing the vehicle to roll at a high speed in an optimal operating range of the electric machine M. The reduction ratio between the second driving pinion 21 and the second driven pinion 22 can for example be between 0.8 and 1.2.

For example, the vehicle will be able to operate at low speed over a speed range from 0 to 50 km / h and at high speed for speeds above 90 km / h. On the speed range between 50 and 90 km / h, a vehicle computer can select one or other of the coupling devices C1, C2 in order to operate the electric machine M of the vehicle at its operating point having the best possible return.

The first coupling device C1 and the second coupling device C2 are located at a different end of the secondary shaft 2. This positioning makes it easier to access the coupling devices C1, C2 during the manufacture of the transmission device T but also during maintenance operations.

When the vehicle is in motion, the transition from the first speed associated with the first gear 10 to the second speed associated with the second gear 20 takes place without torque breakdown. To do this, the first coupling device C1 and the second coupling device C2 are friction clutches. More precisely, the first coupling device C1 and the second coupling device C2 are wet multi-disc clutches. These types of clutches make it possible to pass a large torque in a small footprint while benefiting from lubrication and cooling of the different clutch discs.

When the vehicle is not in operation, one of the coupling devices C1, C2 is in the normally closed position and the other is in the normally open position.

In this case, a locking device 5 in the parking position is positioned on the primary shaft 1 or the secondary shaft 2.

In FIG. 1, the coupling device C1 is in the normally closed position and the coupling device C2 is in the normally open position. The reverse is also possible, that is to say that the coupling device C1 can be in the normally open position and the coupling device C2 can be in the normally closed position. Thus, on the primary shaft 1 is positioned the locking device 5. The purpose of this locking device 5 is to lock the transmission device T when the vehicle is stopped so that it is immobilized, for example when it is parked.

Alternatively, the first coupling device C1 and the second coupling device C2 may be in the normally closed position. Thus, as soon as the vehicle starts, one of the two coupling devices C1, C2 opens in order to transmit the torque from the electric machine M to the wheels R1, R2 of the vehicle (or vice versa) by only one path of couple. In this case, it is not necessary to have a locking device 5 in the parking position.

The first coupling device C1 and the second coupling device C2 are each controlled by an actuator (not shown) for controlling the clutches. The actuator can be of the electro-hydraulic or electro-hydrostatic type and is connected to the coupling device C1, C2 by a hydraulic circuit. The actuators are linked together and controlled by a control unit (not shown) making it possible to manage the open or closed positioning of each of the coupling devices C1, C2.

The first coupling device C1 and the second coupling device C2 are composed of the same elements, that is to say an input disc holder integral in rotation with the first driven pinion 12 and the second driven pinion 21 respectively, a disc holder output integral in rotation with the secondary shaft 2, a multi-disc assembly comprising at least one friction disc integral in rotation with one of the input and output disc carriers, at least two plates respectively arranged on the side and other of the friction disc, integral in rotation with the other of the entry and exit disc holder. The friction disc has friction linings on each of its sides. The linings are fixed to the friction discs by gluing, riveting or overmolding. Alternatively, the fittings can be fixed on the trays.

The first coupling device C1 and the second coupling device C2 describe a disengaged position corresponding to the open position and a engaged position corresponding to the closed position in which said plates pinch the friction disc so as to transmit a torque between the disc holder input and output disc holder.

Each input or output disc holder can synchronize in rotation all the plates or all the friction discs. The plates and the discs can cooperate with the entry and exit disc holders along one of their radial peripheries by complementarity of form, the plates and the friction discs can for example be grooved. The plates can be secured in rotation to the input disc holder and the friction discs can be secured to the outlet disc holder. As a variant, the plates can be fixed in rotation to the output disc holder and the friction discs can be fixed in rotation to the input disc holder. The friction plates and discs are located radially between the input disc holder and the output disc holder.

The elements of the transmission device T, i.e. the primary shaft 1, the secondary shaft 2, the tertiary shaft 3, the first gear 10, the second gear 20, the third gear 30, the gear 40 differential D, the first coupling device C1, the second coupling device C2, the locking device 5 and the differential D are arranged in a housing (not shown).

The electric machine M and is assembled on the housing of the transmission device T by any fixing means, for example screws, so that the output shaft of the electric machine M is coaxial with the primary shaft 1. The actuators of the coupling devices C1, C2 can also be fixed to the housing of the transmission device T.

The primary shaft 1, the secondary shaft 2 and the tertiary shaft 3 are each supported by a bearing located at each of their ends. The primary shaft 1 is supported by the bearings 1a and 1b, the secondary shaft 2 is supported by the bearings 2a and 2b, the tertiary shaft 3 is supported by the bearings 3a and 3b. Each of these bearings is in the form of ball bearings having an internal ring in contact with the shaft 1, 2, 3 and an external ring housed in the housing of the transmission device T.

In this way, the first coupling device C1 which is located on the secondary shaft 2 is located between the support bearing 2a and the first gear 10 and more precisely the first driven pinion 12. The second coupling device C2 which is located on the secondary shaft 2 is located between the support bearing 2b and the second gear 20 and more precisely the second driven pinion 22.

The locking device 5 is located between the second driving pinion 21 and the support bearing 1b.

In this first embodiment, the reduction ratio between the electric machine M and the wheels R1, R2 of the vehicle is 19: 1 for the first speed and 8: 1 for the second speed.

The transmission device T shown in FIG. 2 is almost identical to the transmission device T shown in FIG. 1, unlike the positioning of the second coupling device C2. In fact, in FIG. 2, the second coupling device C2 is linked to the second driving pinion 21. As a result, the second coupling device C2 is located at one end of the primary shaft 1 while the first coupling device C1 is always located at one end of the secondary shaft 2. This means that the second driving pinion 21 is mounted idly on the primary shaft 1 and that the second driven pinion 22 is fixedly mounted on the secondary shaft 2.

As shown in FIG. 2, the first coupling device C1 and the second coupling device C2 are located at a different end from the secondary shaft 2 and from the primary shaft 1. This positioning makes it easier to access the devices C1, C2 coupling during the manufacture of the transmission device T but also during maintenance operations.

In FIG. 2, the coupling device C1 is in the normally closed position and the coupling device C2 is in the normally open position. The reverse is also possible, that is to say that the coupling device C1 can be in the normally open position and the coupling device C2 can be in the normally closed position.

The locking device 5 in the parking position is positioned on the secondary shaft 2.

The operation of the transmission device T and of the coupling devices C1, C2 of FIG. 2 is identical to that of FIG. 1.

In a variant not shown, it is entirely possible that the first coupling device C1 is linked to the first driving pinion 11 and that the second coupling device C2 is linked to the second driven pinion 22, the first coupling device C1 and the second C2 coupling device being always located at a different end of the secondary shaft 2 and the primary shaft 1.

In this second embodiment, the reduction ratio between the electric machine M and the wheels R1, R2 of the vehicle is also 19: 1 for the first speed and 8: 1 for the second speed.

The transmission device T shown in Figure 3 is almost identical to the transmission device T shown in Figure 1 except that the transmission device T does not include a tertiary shaft, which eliminates the third gear and therefore to reduce the size of the transmission device T housing. Thus, the secondary shaft 2 is directly connected to the differential D via the gear 40 of differential D, the last driving pinion 41 is disposed on the shaft secondary 2 fixedly. The last driving pinion 41 is disposed axially between the first driven pinion 12 and the second driven pinion 22.

In this third embodiment, the first coupling device C1 and the second coupling device C2 are also located at a different end of the secondary shaft 2.

In this third embodiment, the reduction ratio between the electric machine M and the wheels R1, R2 of the vehicle is 12: 1 for the first speed and 7: 1 for the second speed.

In Figure 4 is shown a transmission device T according to a fourth embodiment. In this embodiment, the first coupling device C1 is linked to the first driving gear 11 and the second coupling device C2 is linked to the second driving gear 21. This means that the first driving gear 11 and the second driving gear 21 are mounted idlers on the primary shaft 1 and that the first driven pinion 12 and the second driven pinion 22 are fixedly mounted on the secondary shaft 2.

As shown in FIG. 4, the first coupling device C1 and the second coupling device C2 are also located at a different end of the primary shaft 1. This positioning makes it easier to access the coupling devices C1, C2 during the manufacture of the transmission device T but also during maintenance operations.

In this fourth embodiment and when the vehicle is not in operation, the first coupling device C1 and the second coupling device C2 are in the normally open position. As soon as the vehicle starts, one of the two coupling devices C1, C2 closes so as to transmit the torque from the electric machine M to the wheels R1, R2 of the vehicle (or vice versa) by only one torque path.

One of the features of the transmission device T of FIG. 4 is the presence of a dog clutch 6 or a synchronizer 6 'on the primary shaft 1. The dog clutch 6 or synchronizer 6' is positioned between the first driving pinion 11 and the second driving pinion 21 and makes it possible to lock either the first driving pinion 11 or the second driving pinion 21. The locking occurs when the speed of rotation of the first driving pinion 11 or of the second driving pinion 21 is equal to or close to the speed of rotation of the primary shaft 1. This configuration makes it possible to release the coupling device C1, C2, associated with the dog clutch 6 or the synchronizer 6 ', that is to say by positioning the coupling device C1, C2 in the open position . This architecture avoids maintaining the hydraulic circuit under pressure between the actuator and the coupling device C1, C2, energy savings are therefore achieved.

The locking device 5 in the parking position is positioned on the secondary shaft 2.

îo As an alternative, the transmission device T of FIG. 4 can comprise two dogs 6 or two synchronizers 6 ′ on the primary shaft 1. Thanks to this design, the first driving pinion 11 and the second driving pinion 21 are each associated to a dog clutch 6 or a 6 'synchronizer. This arrangement makes it possible to dispense with the locking device 5 in the parking position.

In this fourth embodiment, the reduction ratio between the electric machine M and the wheels R1, R2 of the vehicle is also 12: 1 for the first speed and 7: 1 for the second speed.

Claims (15)

1. Two-speed transmission device (T) for an electric vehicle equipped with an electric machine (M) capable of operating alternately according to an engine mode or according to a generator mode, the transmission comprising: - a primary shaft (1) capable of being connected to the electric machine (M), - a secondary shaft (2) capable of being connected to the wheels (R1, R2) of the vehicle, - A first gear (10) corresponding to the first speed and comprising a first driving pinion (11) disposed on the primary shaft (2) and a first driven pinion (12) disposed on the secondary shaft (2) and meshing in permanence with the first driving pinion (11), - a second gear (20) corresponding to the second speed and comprising a second driving pinion (21) disposed on the primary shaft (1) and a second driven pinion (22) disposed on the secondary shaft (2) and meshing in permanence with the second driving pinion (21), - a first coupling device (C1) associated with the first gear (4), - a second coupling device (C2) associated with the second gear (5), characterized in that the first coupling device (C1) and the second coupling device (C2) are located at a different end of the secondary shaft ( 2) and / or the primary shaft (1). 2. Transmission device (T) according to claim 1 characterized in that the first coupling device (C1) and the second coupling device (C2) are friction clutches. 3. Transmission device (T) according to claim 2 characterized in that the first coupling device (C1) and the second coupling device (C2) are wet multi-disc clutches. 4. Transmission device (T) according to one of the preceding claims, characterized in that the first coupling device (C1) and the second coupling device (C2) are controlled. 5. Transmission device (T) according to one of the preceding claims characterized in that the device comprises a tertiary shaft (3) connected to the secondary shaft (2) via a third gear (30) comprising a third driving pinion (31) disposed on the secondary shaft (2) and a third driven pinion (32) disposed on the tertiary shaft (3) and permanently meshing with the third driving pinion (31). 6. Transmission device (T) according to claim 5 characterized in that the third driving pinion (31) is arranged axially between the first driven pinion (12) and the second driven pinion (22). 7. Transmission device (T) according to one of the preceding claims, characterized in that the first coupling device (C1) or the second coupling device (C2) is of the normally closed type. 8. Transmission device (T) according to claim 7 characterized in that the primary shaft (1) or the secondary shaft (2) comprises a locking device (5) in the parking position. 9. Transmission device (T) according to one of claims 1 to 6 characterized in that the first coupling device (C1) and the second coupling device (C2) are of the normally closed type. 10. Transmission device (T) according to one of claims 1 to 6 characterized in that the first coupling device (C1) and the second coupling device (C2) are of the normally open type. 11. Transmission device (T) according to claim 10 characterized in that the secondary shaft (2) comprises a locking device (5) in the parking position. 12. Transmission device (T) according to one of claims 10 and 11 characterized in that a dog clutch (6) or a synchronizer (6 ') is linked to the first driving pinion (11) or to the second driving pinion (21 ). 13. Transmission device (T) according to one of the preceding claims characterized in that a support bearing (1a, 1b, 2a, 2b) is located at each end of the primary shaft (1) and the secondary shaft (2). 14. Transmission device (T) according to claim 13 characterized in that the first coupling device (C1) and the second coupling device (C2) are located between the support bearing (1a, 1b, 2a, 2b) and the first gear (10) or the second gear (20). 15. Transmission device (T) according to one of the preceding claims characterized in that a differential (D) is connected to the secondary shaft (2) or to the tertiary shaft (3) by means of a differential gear (40), said differential (D) being adapted to be connected to the wheels (R1, R2) of the vehicle.