Optimized traction chain for a motor vehicle comprising two rotating electrical machines

Abstract

The invention relates mainly to a traction chain (10) for a motor vehicle, characterised in that the traction chain comprises: a first rotating electric machine (13.1) permanently coupled to a wheel (12) of an axle (11) of the motor vehicle, the first rotating electric machine (13.1) being intended to operate in motor mode and in generator mode, in particular in generator mode during a recuperation braking phase, for recharging at least one battery; a second rotating electric machine (13.2) being intended to operate only in motor mode to ensure traction of the motor vehicle; a reducer (16) interposed between the rotating electric machines (13.1, 13.2) and a differential (17) of the motor vehicle; and a flywheel coupling device (24) associated with the second rotating electric machine (13.2) so that the second rotating electric machine (13.2) can transmit its torque to the wheel (12).

Description

Technical Field

[0001] The invention relates to an optimized traction chain for a motor vehicle comprising two rotating electrical machines. Background Art

[0002] In a manner known per se, a rotating electrical machine can be placed on the front axle or on the rear axle of a motor vehicle in the context of electric or hybrid applications.

[0003] The electric machine is connected to the wheel axle via a coupling device. Usually, the reduction ratio of the coupling device is selected to be large enough to allow electric starting and electric driving of the motor vehicle. The machine is dimensioned for use in generator mode to supply energy to the vehicle battery and also operates in motor mode to ensure traction of the vehicle alone or in combination with a heat engine in the case of hybrid applications. However, such a machine has poor energy efficiency, since in propulsion mode it operates at low load levels, resulting in significant losses. Summary of the invention

[0004] The present invention is particularly intended to effectively remedy this drawback by proposing a traction chain for a motor vehicle, the traction chain being characterized in that it comprises:

[0005] a first rotating electric machine permanently coupled to a wheel of an axle of the motor vehicle, said first rotating electric machine being intended to operate in motor mode and in generator mode, in particular in generator mode during a regenerative braking phase, for recharging at least one battery,

[0006] a second rotating electrical machine designed to operate only in motor mode to ensure traction of the motor vehicle,

[0007] - a speed reducer interposed between the rotating electrical machine and the differential of the motor vehicle, and

[0008] - a flywheel coupling device associated with the second rotating electrical machine so that it can transmit its torque to the wheel.

[0009] The invention thus allows to dimension one of the two electric machines used so that it operates in traction mode with its best energy efficiency. The architecture according to the invention also has economic characteristics, since it can be implemented using 48 volt applications and requires only the integration of an inexpensive flywheel device. Furthermore, during its repeated use, the flywheel allows the torque to be transmitted to the wheels more quickly than a coupling system controlled by electronic technology. It should also be noted that the invention makes it possible to meet the redundancy criteria imposed by an autonomous motor vehicle by using two electric machines in combination.

[0010] According to one embodiment, a flywheel coupling device is provided between the shaft of the second rotating electrical machine and the input shaft of the speed reducer.

[0011] According to one embodiment, the flywheel coupling device is integrated in the second rotating electrical machine.

[0012] According to one embodiment, the flywheel coupling device is integrated in the reducer.

[0013] According to one embodiment, the flywheel coupling device is a separate element arranged between the second rotating electrical machine and the reducer.

[0014] According to one embodiment, the speed reducer comprises a first speed ratio associated with the first rotating electrical machine and a second speed ratio associated with the second rotating electrical machine.

[0015] According to one embodiment, the flywheel coupling device is associated with the intermediate gear.

[0016] According to one embodiment, the speed reducer and the flywheel device are configured such that the flywheel device rotates slower than the second rotating electrical machine.

[0017] According to one embodiment, the reducer comprises at least one reduction stage kinematically arranged between the second rotating electrical machine and a differential of the motor vehicle, and the flywheel coupling device is kinematically arranged between the reduction stage of the reducer and the differential.

[0018] According to one embodiment, the reducer comprises a first speed ratio R1 associated with the first motor and a second speed ratio R2 associated with the second motor, the first ratio R1 being obtained by a first part of the reducer comprising a gear coupled to the output shaft of the first motor and an intermediate gear mounted on an intermediate shaft, the second ratio R2 being obtained by a second part of the reducer comprising a gear coupled to the output shaft of the second motor and an intermediate gear mounted on an intermediate shaft, the intermediate shaft also carrying a gear meshing with a differential, a flywheel coupling device being arranged between the intermediate gear and the gear of the intermediate shaft meshing with the differential.

[0019] According to one embodiment, the gear coupled to the output shaft of the first motor meshes with the intermediate gear mounted on the intermediate shaft of the first part of the reducer and / or the gear coupled to the output shaft of the second motor meshes with the intermediate gear mounted on the intermediate shaft of the second part of the reducer.

[0020] According to one embodiment, the traction chain further comprises a torque distribution function for distributing torque between the first rotating electrical machine and the second rotating electrical machine.

[0021] According to one embodiment, the torque distribution function uses an efficiency map to distribute the setpoint torque between the two rotating electrical machines in order to obtain the best possible operating efficiency for the rotating electrical machines.

[0022] According to one embodiment, the torque distribution function is integrated in the motor computer.

[0023] According to one embodiment, the torque distribution function is integrated in a main inverter of one of the rotating electrical machines.

[0024] According to one embodiment, the flywheel coupling can be locked in both directions, in particular at low speeds.

[0025] According to one embodiment, the locking of the flywheel coupling is controlled by an electronic system via a mechanical or hydraulic connection.

[0026] According to one embodiment, the first and second rotating electrical machines are of the synchronous type, in particular with permanent magnet or rotor excitation, or of the asynchronous type.

[0027] The invention also relates to a motor vehicle comprising a traction chain as described above.

[0028] According to one embodiment, the traction chain is mounted on the front axle of the motor vehicle.

[0029] According to one embodiment, the traction chain is mounted on the rear axle of the motor vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be better understood by reading the following description and examining the accompanying drawings. These drawings are provided to illustrate rather than limit the present invention. In the drawings:

[0031] Figure 1a is a schematic diagram of a first embodiment of a traction architecture for a motor vehicle according to the present invention;

[0032] Figure 1b is a schematic diagram of a second embodiment of a traction structure for a motor vehicle according to the present invention;

[0033] Figure 2 is a schematic diagram of an interface grid implemented in the traction architecture of the present invention. DETAILED DESCRIPTION

[0034] Identical, similar or like elements retain the same reference from one figure to another.

[0035] Figure 1a A traction chain 10 for a motor vehicle is shown. The traction chain 10 is mounted on an axle 11 of the motor vehicle carrying wheels 12. The axle 11 can be a front axle or a rear axle. The vehicle can be of electric or hybrid type. In this case, it also includes a traction heat engine (not shown).

[0036] More precisely, the traction chain 10 comprises a first rotary motor 13.1 and a second rotary motor 13.2. Each motor 13.1, 13.2 is provided with a corresponding inverter 14.1, 14.2, which can be fixed to the rear of the machine or separated from the machine.

[0037] The reducer 16 is interposed between the electric machines 13.1, 13.2 and the differential 17 of the motor vehicle, which is connected to the vehicle's wheels 12. The reducer 16 comprises a single ratio formed by a gear 19 mounted on the input shaft of the reducer 16 and meshing with an intermediate gear 20 mounted on an intermediate shaft 21, which also carries a second intermediate gear 22 meshing with the differential 17.

[0038] Advantageously, the first electric machine 13.1 is permanently coupled to the motor vehicle's wheels 12. The first electric machine 13.1 is intended to operate in motor mode to ensure traction of the vehicle and in generator mode, in particular during regenerative braking phases, to recharge at least one battery of the vehicle.

[0039] The second electric machine 13.2 is intended to operate only in motor mode to ensure traction of the motor vehicle. A flywheel coupling device 24 is associated with the second electric machine 13.2. This device 24 makes it possible to connect the second electric machine 13.2 to the wheel 12 so that the second electric machine 13.2 can transmit its torque to the wheel 12 and to decouple the second electric machine 13.2 relative to the wheel 12 when the rotation speed of the wheel 12 becomes greater than the rotation speed of the second electric machine 13.2 by a difference in the reduction ratio.

[0040] This flywheel coupling 24 may for example take the form of a roller or friction disk flywheel, in particular having a conical shape, in order to optimize the transmission of torque from the electric motor 13 . 2 towards the wheel 12 .

[0041] The flywheel coupling device 24 is arranged between the output shaft of the second rotary electric machine 13 . 2 and the input shaft of the reducer 16 .

[0042] The freewheel coupling device 24 can be integrated in the electric machine 13.2 or in the reducer 16. Alternatively, the flywheel coupling device 24 is a separate element arranged between the second rotating electric machine 13.2 and the reducer 16.

[0043] exist Figure 1b In the embodiment of the invention, the reducer 16 comprises a first speed ratio R1 associated with the first rotary motor 13.1 and a second speed ratio R2 associated with the second rotary motor 13.2. The ratio R1 is formed by a gear 27 coupled to the output shaft of the first motor 13.1, which meshes with an intermediate gear 28 mounted on an intermediate shaft 29.

[0044] The ratio R2 is formed by a gear 30 coupled to the output shaft of the second electric machine 13 . 2 , which meshes with an intermediate gear 31 mounted on the intermediate shaft 29 . The intermediate shaft 29 also carries a gear 33 which meshes with the differential 17 .

[0045] Advantageously, the reducer 16 and the flywheel device 24 are configured such that the flywheel device 24 rotates slower than the second rotary electric machine 13 . 2 .

[0046] In this embodiment, the reducer comprises at least one reduction stage 30, 31 which is kinematically arranged between the second rotating electrical machine 13.2 of the motor vehicle and the differential 17. The flywheel coupling device 24 is kinematically arranged between this reduction stage 30, 31 of the reducer 16 and the differential 17. The flywheel coupling device 24 thus rotates at a lower speed than the second rotating electrical machine 13.2, which simplifies its design since it is subject to much smaller centrifugal forces.

[0047] The flywheel coupling device 24 is associated with the intermediate gear 31 of the second speed ratio R2. The device 24 is arranged, for example, between the intermediate gear 31 and a gear 33 of the intermediate shaft 29 meshing with the differential 17.

[0048] The flywheel coupling 24 is kinematically arranged between an intermediate gear 31 of the reduction gear 16 and a gear 33 of the intermediate shaft 29 meshing with the differential 17 .

[0049] Advantageously, a torque distribution function F is provided for distributing torque between the first rotating electrical machine 13.1 and the second rotating electrical machine 13.2. The distribution function F receives as input a set torque Tcons corresponding to the acceleration intention on the part of the driver. The function F uses an efficiency map Cart_rend to distribute the set torque Tcons between the two electrical machines 13.1 and 13.2 in order to obtain the best possible operating efficiency for the electrical machines 13.1 and 13.2. Thus, the first electrical machine 13.1 applies a torque T1, the second electrical machine 13.2 applies a torque T2, the sum of T1 and T2 being equal to Tcons. In some cases, one of the two torques T1 or T2 may be zero in order to optimize the efficiency of the traction electrical machine 13.2. The torque distribution function F is integrated in the main inverter 14.1 or 14.2 of one of the rotating electrical machines 13.1 and 13.2. Alternatively, the torque distribution function F is integrated in the motor calculator.

[0050] According to a specific embodiment, the flywheel coupling 24 can be locked in both directions, in particular at low speeds, i.e. at speeds less than 20 km / h. Thus, it is possible to enable the motor vehicle to be reversed with more torque, for example to perform an ascent of a slope or a sidewalk. The locking of the flywheel coupling can be controlled by an electronic system via a mechanical or hydraulic connection.

[0051] from Figure 2 As can be seen in the figure, the two rotating electrical machines 13.1, 13.2 are connected to a first electrical network 35, to which two batteries 36, 37 for redundancy functions, integrated or not integrated in the same housing, are also connected. The electrical network 35 has an operating voltage of less than 60 V. Advantageously, the operating voltage of the electrical network 35 is 48 V. Other electrical loads 38 can also be connected to the electrical network 35.

[0052] Each electric machine 13.1, 13.2 can have a power of 10 kW to 35 kW and in particular provide a torque of 20 Nm to 300 Nm, depending on its length. The electrical network 35 is connected to a second low-voltage electrical network 40 via a DC / DC converter 41. An optional starter 42, which ensures a possible cold start of the heat engine (in the case of a hybrid configuration), as well as electrical consumers 43 of the lighting type vehicle, window or seat actuators and motor control are connected to the electrical network 40. This electrical network 40, which is associated with a battery 44, has an operating voltage lower than the operating voltage of the first electrical network 35. The operating voltage of the electrical network 40 is preferably about 12 volts.

[0053] In certain embodiments, the inverters 14.1, 14.2 of the motors 13.1, 13.2 and the converter 41 may also be integrated in the same housing.

[0054] The electric machines 13.1, 13.2 may be in the form of rotor excited machines or synchronous machines or asynchronous machines with permanent magnets. The electric machines 13.1, 13.2 may be of the same type or of different types. The cooling circuit of the electric machines 13.1, 13.2 may be based on water or oil. The cooling circuit may or may not be common to the electric machines 13.1, 13.2.

[0055] According to a specific hybrid configuration, the two electric machines 13 . 1 , 13 . 2 and the flywheel coupling 24 are placed on the rear axle 11 of a motor vehicle which also comprises a heat engine ensuring traction of the front axle 11 .

[0056] Alternatively, the electric machines 13 . 1 , 13 . 2 can have a power of more than 25 kW and can reach 150 kW if they are connected to a voltage network greater than 48 V.

[0057] Of course, the preceding description is given only as an example and does not limit the scope of the present invention, which cannot be exceeded by replacing different elements with any other equivalent ones.

[0058] Furthermore, the different features, variants and embodiments of the invention can be associated with one another in various combinations, as long as they are not incompatible or mutually exclusive.

Claims

1. A traction chain (10) for a motor vehicle, characterized in that: The traction chain comprises: a first rotating electrical machine (13.1) permanently coupled to a wheel (12) of an axle (11) of the motor vehicle, the first rotating electrical machine (13.1) being adapted to operate in a motor mode and in a generator mode, a second rotating electrical machine (13.2) for operating only in motor mode to ensure traction of the motor vehicle, a speed reducer (16) interposed between the first rotating electrical machine (13.1) and the second rotating electrical machine (13.2) and a differential (17) of the motor vehicle, and a flywheel coupling device (24) associated with the second rotating electrical machine (13.2) so as to enable the second rotating electrical machine (13.2) to transmit its torque to the wheel (12); The reducer (16) comprises a first speed ratio R1 associated with the first rotating motor (13.1) and a second speed ratio R2 associated with the second rotating motor (13.2), the first speed ratio R1 being obtained by a first part of the reducer (16), the first part comprising a gear (27) connected to the output shaft of the first rotating motor (13.1) and a first intermediate gear (28) mounted on an intermediate shaft (29), the second speed ratio R2 being obtained by a second part of the reducer (16), the second part comprising a gear connected to the output shaft of the second rotating motor (13.2) and a second intermediate gear (31) mounted on the intermediate shaft (29), the intermediate shaft (29) also carrying a gear meshing with the differential (17), the flywheel coupling device (24) being arranged between the second intermediate gear (31) and a gear (33) of the intermediate shaft (29) meshing with the differential (17).

2. The traction chain (10) according to claim 1, characterized in that: The flywheel coupling device (24) is arranged between the shaft of the second rotating electric machine (13.2) and the input shaft of the reducer (16), and the flywheel coupling device (24) is integrated in the second rotating electric machine (13.2).

3. The drag chain (10) according to claim 1, characterized in that: The flywheel coupling device (24) is integrated into the reducer (16).

4. The drag chain (10) according to claim 1, characterized in that: The speed reducer (16) and the flywheel coupling device (24) are configured such that the flywheel coupling device (24) rotates slower than the second rotating electrical machine (13.2).

5. The drag chain (10) according to claim 3 or 4, characterized in that: The reducer comprises at least one reduction stage, which is kinematically arranged between the second rotating electrical machine (13.2) and the differential (17) of the motor vehicle, and the flywheel coupling device (24) is kinematically arranged between this reduction stage of the reducer (16) and the differential (17).

6. The drag chain (10) according to any one of claims 1 to 4, characterized in that The gear (27) connected to the output shaft of the first rotating electric machine (13.1) meshes with the first intermediate gear (28) of the first part of the reducer (16) mounted on the intermediate shaft (29) and / or the gear (30) connected to the output shaft of the second rotating electric machine (13.2) meshes with the second intermediate gear (31) of the second part of the reducer (16) mounted on the intermediate shaft (29).

7. The drag chain (10) according to any one of claims 1 to 4, characterized in that The traction chain further comprises a torque distribution function (F) for distributing torque between the first rotating electrical machine (13.1) and the second rotating electrical machine (13.2).

8. The drag chain (10) according to claim 7, characterized in that The torque distribution function (F) distributes the set torque (Tcons) between the first rotating electrical machine (13.1) and the second rotating electrical machine (13.2) using an efficiency map (Cart_rend) so as to obtain the best possible operating efficiency for the first rotating electrical machine (13.1) and the second rotating electrical machine (13.2).

9. The drag chain (10) according to claim 7, characterized in that: The torque distribution function (F) is integrated in the motor calculator.

10. The drag chain (10) according to claim 7, characterized in that The torque distribution function (F) is integrated in a main inverter (14.1, 14.2) of one of the first rotating electrical machine (13.1) and the second rotating electrical machine (13.2).

11. The drag chain according to any one of claims 1 to 4, characterized in that: The flywheel coupling (24) is lockable in two directions.

12. The drag chain according to claim 11, characterized in that: The locking of the flywheel coupling device (24) is controlled by an electronic system via a mechanical or hydraulic connection.

13. The drag chain (10) according to any one of claims 1 to 4, characterized in that The first rotating electrical machine (13.1) and the second rotating electrical machine (13.2) are of the synchronous type with permanent magnets or of the rotor excited synchronous type or of the asynchronous type.

14. The drag chain according to claim 1, wherein: The first rotating electrical machine is operated in generator mode during the regenerative braking phases for recharging at least one battery.

15. The drag chain according to claim 11, wherein: The flywheel coupling device (24) is lockable in both directions at low speeds.

16. A motor vehicle comprising a traction chain (10) according to any one of claims 1 to 15.

17. A motor vehicle according to claim 16, characterised in that The traction chain (10) is mounted on the front wheel axle (11) or the rear wheel axle (11) of the motor vehicle.

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