Disclosure of Invention
The invention aims in particular to effectively remedy this drawback by proposing a traction chain for a motor vehicle, characterized in that it comprises:
A first rotating electrical machine permanently coupled with the wheel of the axle of the motor vehicle, said first rotating electrical machine being intended to operate in a motor mode and in a generator mode, in particular in a generator mode during a regenerative braking phase, for recharging at least one battery,
A second rotating electrical machine designed to operate only in motor mode to ensure traction of the motor vehicle,
A speed reducer interposed between the rotating electric machine and the differential of the motor vehicle, and
A flywheel coupling device associated with the second rotating electrical machine so that the second rotating electrical machine can transmit its torque to the wheel.
The invention thus allows to dimension one of the two motors used so that it operates in traction mode with its optimal energy efficiency. The architecture according to the invention also has economical characteristics, since it can be implemented using 48 volt applications and only requires the integration of inexpensive flywheel devices. Furthermore, the flywheel allows a faster transfer of torque to the wheel during its repeated use than a coupling system controlled by electronics. It should also be noted that the invention makes it possible to meet the redundancy standard imposed by autonomous motor vehicles by using two electric machines in combination.
According to one embodiment, the flywheel coupling is arranged between the shaft of the second rotating electrical machine and the input shaft of the reduction gear.
According to one embodiment, the flywheel coupling is integrated in the second rotating electrical machine.
According to one embodiment, the flywheel coupling is integrated in the reduction gear.
According to one embodiment, the flywheel coupling means is a separate element arranged between the second rotating electrical machine and the reduction gear.
According to one embodiment, the speed reducer includes a first speed ratio associated with the first rotating electrical machine and a second speed ratio associated with the second rotating electrical machine.
According to one embodiment, the flywheel coupling is associated with an intermediate gear.
According to one embodiment, the speed reducer and the flywheel arrangement are configured such that the flywheel arrangement rotates slower than the second rotary electric machine.
According to one embodiment, the reduction gear comprises at least one reduction stage which is arranged kinematically between the second rotating electrical machine and the differential of the motor vehicle, between which reduction stage the flywheel coupling is arranged kinematically.
According to one embodiment, the reducer comprises a first speed ratio R1 associated with the first electric machine and a second speed ratio R2 associated with the second electric machine, the first ratio R1 being obtained by a first part of the reducer comprising a gear coupled to the output shaft of the first electric machine and an intermediate gear mounted on the 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 electric machine and an intermediate gear mounted on the intermediate shaft, the intermediate shaft also carrying a gear meshing with the differential, the freewheel coupling being arranged between the intermediate gear and the gear of the intermediate shaft meshing with the differential.
According to one embodiment, the gear wheel coupled to the output shaft of the first motor meshes with an intermediate gear wheel of the first part of the reduction gear mounted on the intermediate shaft and/or the gear wheel coupled to the output shaft of the second motor meshes with an intermediate gear wheel of the second part of the reduction gear mounted on the intermediate shaft.
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.
According to one embodiment, the torque distribution function uses an efficiency map (cartographie DE RENDEMEN) to distribute a set torque between two rotating electrical machines in order to obtain the best possible operating efficiency for the rotating electrical machines.
According to one embodiment, the torque distribution function is integrated in the motor calculator.
According to one embodiment, the torque distribution function is integrated in a main inverter of one of the rotating electrical machines.
According to one embodiment, the flywheel coupling can be locked in both directions, in particular at low speeds.
According to one embodiment, the locking of the flywheel coupling is controlled by an electronic system via a mechanical or hydraulic connection.
According to one embodiment, the first rotating electrical machine and the second rotating electrical machine are in particular of the synchronous type with permanent magnet or rotor excitation, or of the asynchronous type.
The invention also relates to a motor vehicle comprising a traction chain as described above.
According to one embodiment, the traction chain is mounted on a front axle of said motor vehicle.
According to one embodiment, the traction chain is mounted on a rear axle of said motor vehicle.
Detailed Description
The same, similar or analogous elements maintain the same reference from one figure to another.
Fig. 1a shows a traction chain 10 for a motor vehicle. The traction chain 10 is mounted on an axle 11 of a motor vehicle carrying wheels 12. The axle 11 may be a front axle or a rear axle. The vehicle may be of the electric or hybrid type. In this case it also comprises a traction heat engine (not shown).
More precisely, the traction chain 10 comprises a first rotating electrical machine 13.1 and a second rotating electrical machine 13.2. Each motor 13.1, 13.2 is provided with a corresponding inverter 14.1, 14.2, which may be fixed to the rear of the machine or separate from the machine.
The speed reducer 16 is interposed between the electric machines 13.1, 13.2 and the differential 17 of the motor vehicle, which differential 17 is connected to the wheels 12 of the vehicle. The reducer 16 comprises a single ratio formed by a gear wheel 19, the gear wheel 19 being mounted on the input shaft of the reducer 16 and engaging an intermediate gear wheel 20 mounted on an intermediate shaft 21, the intermediate shaft 21 also carrying a second intermediate gear wheel 22 engaging the differential 17.
Advantageously, the first electric machine 13.1 is permanently coupled to the wheel 12 of the motor vehicle. 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 the regenerative braking phase, to recharge at least one battery of the vehicle.
The second electric machine 13.2 is intended to operate in motor mode only to ensure traction of the motor vehicle. The flywheel coupling 24 is associated with the second electric machine 13.2. The arrangement 24 makes it possible to connect the second electric machine 13.2 to the wheel 12 such that the second electric machine 13.2 can transfer its torque to the wheel 12 and decouple the second electric machine 13.2 relative to the wheel 12 when the rotational speed of the wheel 12 becomes greater than the rotational speed of the second electric machine 13.2 by a difference in reduction ratio.
The flywheel coupling 24 may for example take the form of a roller or friction disc flywheel, in particular having a conical shape, to optimise the torque transmission of the motor 13.2 towards the wheel 12.
The flywheel coupling 24 is arranged between the output shaft of the second rotating electrical machine 13.2 and the input shaft of the reducer 16.
The freewheel coupling device 24 can be integrated in the electric machine 13.2 or in the reduction gear 16. Alternatively, the flywheel coupling 24 is a separate element arranged between the second rotating electrical machine 13.2 and the reduction gear 16.
In the embodiment of fig. 1b, the speed reducer 16 comprises a first speed ratio R1 associated with the first rotating electrical machine 13.1 and a second speed ratio R2 associated with the second rotating electrical machine 13.2. The ratio R1 is formed by a gear wheel 27 coupled to the output shaft of the first motor 13.1, which gear wheel 27 meshes with an intermediate gear wheel 28 mounted on an intermediate shaft 29.
The ratio R2 is formed by a gear wheel 30 coupled to the output shaft of the second motor 13.2, which gear wheel 30 meshes with an intermediate gear wheel 31 mounted on the intermediate shaft 29. The intermediate shaft 29 also carries a gear 33 which meshes with the differential 17.
Advantageously, the speed reducer 16 and the flywheel arrangement 24 are configured such that the flywheel arrangement 24 rotates slower than the second rotary electric machine 13.2.
In this embodiment, the reduction gear comprises at least one reduction stage 30, 31, the reduction stage 30, 31 being arranged kinematically between the second rotating electrical machine 13.2 of the motor vehicle and the differential 17. The flywheel coupling 24 is arranged kinematically between this reduction stage 30, 31 of the reduction gear 16 and the differential 17. The flywheel coupling 24 thus rotates at a lower speed than the second rotating electrical machine 13.2, which simplifies its design, since it is subjected to much smaller centrifugal forces.
The flywheel coupling 24 is associated with an intermediate gear 31 of the second speed ratio R2. The device 24 is arranged, for example, between an intermediate gear 31 and a gear 33 of the intermediate shaft 29 which meshes with the differential 17.
The freewheel coupling device 24 is kinematically arranged between the intermediate gear 31 of the reduction gear 16 and the gear 33 of the intermediate shaft 29 that meshes with the differential 17.
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 willingness on the part of the driver. The function F uses the efficiency map cat_rend to divide the set torque Tcons between the two electric machines 13.1, 13.2 in order to obtain the best possible operating efficiency for the electric machines 13.1, 13.2. Thus, the first motor 13.1 applies a torque T1 and the second motor 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 motor 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, 13.2. Alternatively, the torque distribution function F is integrated in the motor calculator.
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, the motor vehicle can be caused to reverse with more torque, for example to perform an uphill slope of a slope or a sidewalk. The locking of the flywheel coupling device may be controlled by an electronic system via a mechanical or hydraulic connection.
As can be seen from fig. 2, the two rotating electrical machines 13.1, 13.2 are connected to a first electrical network 35, and the two batteries 36, 37, which are integrated or not integrated in the same housing, for redundancy function are also connected to the first electrical network 35. The grid 35 has an operating voltage of less than 60 volts. Advantageously, the operating voltage of the grid 35 is 48 volts. Other electrical loads 38 may also be connected to the grid 35.
Each motor 13.1, 13.2 may have a power of 10kW to 35kW and in particular provide a torque of 20Nm to 300Nm depending on its length. The grid 35 is connected to a second low voltage grid 40 via a dc/dc converter 41. An optional starter 42 ensuring a possible cold start of the heat engine (in case of a hybrid configuration), and an electrical consumer 43 of the illuminated vehicle, a window or seat actuator and a motor control are connected to the electric network 40. The grid 40 associated with the battery 44 has an operating voltage lower than the operating voltage of the first grid 35. The operating voltage of the grid 40 is preferably about 12 volts.
In a particular embodiment, it is also possible to integrate the inverters 14.1, 14.2 and the converters 41 of the motors 13.1, 13.2 in the same housing.
The electric machines 13.1, 13.2 may take the form of rotor-excited machines or synchronous machines with permanent magnets or asynchronous machines. The motors 13.1, 13.2 may be of the same type or of different types. The cooling circuit of the electric machine 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.
Depending on the particular hybrid configuration, the two electric machines 13.1, 13.2 and the flywheel coupling 24 are placed on the rear axle 11 of the motor vehicle, which also comprises a heat engine ensuring traction of the front axle 11.
Alternatively, the motors 13.1, 13.2 may have a power of more than 25kW and capable of up to 150kW if they are connected to a voltage network of more than 48V.
Of course, the foregoing description is given by way of example only and does not limit the scope of the invention, which may be beyond the scope of the present invention by substituting different elements with any other equivalent.
Furthermore, the different features, variations and embodiments of the invention may be associated with each other according to various combinations, provided that they are not incompatible or mutually exclusive.