FR2961754A1 - Device for transmitting power to propelling axle of motor vehicle i.e. urban type motor vehicle, has kinematic connection unit comprising distributor clutch and controlling unit for controlling couple transmitted by clutch - Google Patents

Abstract

The device has an engine (1) comprising a driving shaft (101) and a transmitting unit (10) to transmit power of the engine to a wheel (G) of a propelling axle. Another engine (2) comprises a driving shaft (201) and a transmitting unit (20) to transmit power of the latter engine to another wheel (D) of the axle. A kinematic connection unit placed between the engines comprises a distributor clutch (12) and a controlling unit for controlling couple transmitted by the clutch such that each engine drives the wheel at which it is independently or jointly with other engine. The first engine is an internal combustion engine, and the second engine is an electric motor. An independent claim is also included for a method for controlling a distributor clutch.

Description

The invention is in the field of propulsion units for motor vehicles. More particularly, the invention relates to a hybrid propulsion device preferably associating an internal combustion engine, or thermal, and an electric motor which can act jointly or individually to propel the vehicle in which they are installed. There are different hybrid drive architectures suitable for motor vehicles. The invention relates more particularly to so-called parallel architectures, in which the vehicle can be powered independently by one or the other of the motors, or even both at the same time. Hybrid propulsion offers advantages over the vehicle's fuel consumption and pollutant emissions. However, these advantages are not always sufficient to justify, in the eyes of the customer, the additional cost, overweight and increased complexity brought to the vehicle by this mode of propulsion. Thus, to develop the market for these vehicles, particularly for urban-type vehicles, there is a need to combine the purely economic and ecological advantages of hybrid vehicles with the advantages in terms of performance, handling or handling of such vehicles. Thus, as an exemplary embodiment, the electric motor can act on the rear wheels of the vehicle and the engine on the front wheels thereof. In doing so, besides the advantage of the hybrid transmission on the consumption of the vehicle, it offers an additional functionality equivalent to a full transmission. This technical advantage justifies, at least partially, the extra cost and overweight generated by the hybrid propulsion system. In the case of a two-wheel drive vehicle, the two engines generally act on the same train by parallel power transmissions without providing additional benefit. US Patent US6659910B2 or Japanese Patent JP4139542B are examples of such embodiments where the two motors act on the rear axle of the vehicle. In these two examples, the power is transmitted to the rear axle via a differential, the two motors acting upstream of this differential. The distribution of the driving contribution of each of the motors is obtained by a centrifugal clutch device in the first example, and by an additional differential placed between the two motors in the second embodiment. Thus, apart from the possibility of hybrid propulsion, these technical solutions do not add any additional functionality compared to a rear-wheel drive known from the prior art, but add, on the other hand, complexity in the kinematic chain, which which results in higher realization and maintenance costs. There is therefore a need for a simple and economical hybrid transmission device suitable in particular for small urban vehicles.

To this end, the invention proposes a device for transmitting power to a propulsion train comprising two parallel wheels of a motor vehicle which device comprises: a first motor comprising a motor shaft and first means able to transmit the power of said motor; at a first wheel 25 of the propulsion train; a second motor comprising a motor shaft and second means able to transmit the power of said second motor to a second wheel of the propulsion train; 2 - kinematic connection means between the two motors comprising a splitter clutch and means for controlling the torque transmitted by said clutch, so that each motor can drive the wheel to which it is linked independently or jointly with the other engine . Thus, the device simplifies the driveline by eliminating the differential and offers, on the one hand, the ability to control each wheel of the train independently of one another, for example by rotating the right wheel in one direction and the left wheel in the other direction. The device offers, on the other hand, the ability to finely control the distribution of the power transmitted by each of the motors, by controlling the distributor clutch. The combination of these functions provides advantages in terms of maneuverability and traction of the vehicle provided with such a transmission device.

The invention can advantageously be implemented in embodiments described below, which can be considered individually or in any technically operative combination. Although not exclusively reserved for hybrid propulsion, the invention will be more particularly advantageous when the first motor is an internal combustion engine, the second motor is an electric motor and the first transmission means comprise a clutch at the exit of the engine. motor shaft of the first motor. The clutch placed at the output of the engine shaft of the heat engine allows in particular to cancel the resistive torque thereof when not in use.

According to a particularly advantageous embodiment of this hybrid transmission, the first transmission means comprise a continuously variable transmission. Preferably, the continuously variable transmission comprises a variator comprising a driving pulley and a receiving pulley, both with movable frustoconical flanges, plated, by means producing a plating force on a trapezoidal transmission belt. In addition to the ease of use provided by the continuously variable transmission, the drive is advantageously used in combination with the engine speed control to adjust the torque transmitted by it. According to an advantageous embodiment, the device comprises means able to modify, during the operation of the variator, the plating force of the belt in the groove of the drive pulley. Thus, the transmission ratio of the drive can be adjusted according to driving situations. Advantageously, the first and second transmission means comprise a homokinetic transmission joint. This configuration avoids the disadvantages of the rigid axle and allows to independently suspend the two wheels thus improving the comfort and handling of the vehicle. According to a particularly advantageous embodiment, the device comprises kinematic connection means between the first and the second transmission means, which means comprise a link clutch. Thus, the combined control of the link clutch and the splitter clutch allows a fine control of the traction on each of the wheels. The invention also relates to control methods of the distributor clutch and the link clutch which methods allow fine adjustment of the driving conditions of the vehicle according to driving situations. Advantageously, the invention relates to a method for controlling the splitter clutch of such a transmission device integrated in a motor vehicle, which method comprises a control mode consisting in controlling the transmission of the torque by said clutch as a function of the speed of each of the wheels to make said speeds consistent with the trajectory of said vehicle. For vehicles equipped with a device further comprising a link clutch, the invention proposes a method for controlling the link clutch comprising a control mode consisting in controlling the torque transmission by said clutch to bring the vehicle back in a rectilinear trajectory at the exit of a curved trajectory, the splitter clutch being disengaged. Thus, the vehicle incorporating such a device has exceptional heading behavior.

The invention also relates to a method for controlling the means for modifying the plating force of the belt in the driving pulley of the variator of a device incorporating such a variator and integrated in a motor vehicle, which method comprises a step consisting of to increase the plating force of said pulley when suddenly urging the accelerator of said vehicle. The invention will now be more specifically described in the context of preferred embodiments, in no way limiting, and FIGS. 1 to 7, in which: FIG. 1 is a schematic sectional view of the propulsion train of FIG. a vehicle incorporating the device according to a first embodiment of the invention; - Figure 2 shows in the same view a second embodiment of the invention; FIG. 3 is a schematic cross-sectional view of the propulsion system of a vehicle according to a third embodiment of the invention; FIG. 4 shows according to this same view a fourth embodiment of the invention; FIG. 5 is a top view of the Jeantaud / Ackermann trunk of a vehicle turning to the left and integrating a device according to the third embodiment of the invention; - Figure 6 shows a top view and schematically a vehicle incorporating a device according to the third embodiment of the invention, which makes a left turn in a small radius of curvature and the corresponding Jeantaud / Ackermann epure; and FIG. 7 is a top view and schematically a vehicle with a single directional wheel, which vehicle incorporates a device according to the third embodiment of the invention and makes a right turn. In the rest of the document, a clutch is said to be "open" when it is disengaged and transmits no torque. It is said to be "engaged" when engaged and transmits a torque.

According to a preferred exemplary embodiment shown in FIG. 1, the transmission device 100 applies to the rear wheels of a motor vehicle. However, the invention is applicable to a front axle. According to a first embodiment, a first motor 1 drives a first wheel G of said train by means of transmission means 10. The second motor 2 drives the second wheel D of the train by transmission means 20. The motor shafts 101 , 201 are rotatably connected by a splitter clutch 12 advantageously of the "multi-disc" type and which makes it possible to control the engine torque passing from one engine to the other. Thus when the splitter clutch 12 is open, there is no power transfer between the two motors. In this configuration, one or other of the wheels G, D is driven by its respective motor 1, 2, or both wheels at the same time. The use of a differential is not necessary: either only one of the wheels G, D is driven by one of the motors 1, 2, or the drive speeds are adjusted according to the target trajectory. By engaging the splitter clutch 12, a portion of the torque of one of the motors is used to drive the other wheel and the other motor. According to this configuration, the two motors are supported by the rear axle and therefore constitute unsprung masses. According to a more advantageous embodiment shown in FIG. 2, the two motors are fixed to the frame 40 or to the structure of the vehicle. Said vehicle is a hybrid vehicle, the first engine 1 'being an internal combustion engine and the second 2' a motor or a reversible electric machine, that is to say that can be used both as engine and generator. The rear axle is formed of two half-shafts 13, 14 rotatably connected by the distributor clutch 12 and suspended relative to the frame 40, for example by suspension arms 400. The power is transmitted by each of the motors 1 ' , 2 'to a respective half-shaft 13, 14 via, for example, a gear train 112, 113, 212, 213, comprising drive or input pinions 113, 213, and wheels Receptor teeth 112, 212. Advantageously, the heat engine, 1 ', is connected in rotation to the gear train 112, 113 via a clutch 11. In this configuration, the motor shafts 101, 201 of the two motors must be coaxial with the axis 401 of the suspension arm joints 400. The two half-shafts 13, 14 must remain coaxial, they constitute a rigid axle. As shown in FIG. 3, in order to improve the suspension and obtain an independent suspension of the two wheels G, D, the power transmission can integrate homokinetic transmission joints 130, 140. Advantageously, the power transmission chain from the heat engine 1 comprises a pulley variator 110, 110 'and a trapezoidal belt 111. This type of variator consists of two pulleys 110, 110' comprising frustoconical flanges placed face to face by their small base and made movable relative to each other. on their common axis, a V-belt 111 passing through the groove thus formed. The displacement of the flanges varies the driving diameter of the pulleys and the belt being of fixed length, the ratio of the transmission between the driving pulley 110 and the driven pulley 110 '. The transmission ratio can thus vary continuously. Advantageously, according to this exemplary embodiment, the separation of the puddles of the receiving pulley 110 'is controlled by centrifugal weights (not shown), whereas on the driving pulley 110 the plating force is obtained by a spring , 120. Thus, the variator self-adapts its transmission ratio to keep the heat engine 1 'in a given rotational speed regime. For example, when the rotational speed of the input gear 113 of the transmission of the heat engine 1 'increases under the effect of a reduced rolling resistance torque wheels, the centrifugal weights cause a rapprochement of the flanges of the pulley receiving 110 'thus increasing the diameter of the groove of said pulley. The traction of the belt spreads the flanges of the drive pulley 110. The transmission ratio of the drive decreases. Conversely, if the speed of rotation of the input gear 113 of the transmission of the engine slows under the effect of an increase in the force opposing the progression of the vehicle, the action of the centrifugal weights tends to move away the flanges of the receiving pulley 110 'and the action of the plating spring 120 tends to bring the flanges closer to the driving pulley 110. The transmission ratio of the variator increases. The belt drive can therefore be advantageously used to maintain the engine at a speed corresponding to optimal operation depending on driving circumstances, for example, for minimum fuel consumption, maximum power or maximum torque. Advantageously, the adjustment of the plating force of the spring 120 can be controlled. For example, by moving a thrust bearing 121 by means of an electric actuator or cable (not shown). In this case, the sensitivity of the drive to the changes in the resistive torque changes, and the engine control speed can be moved. This function can be used in particular if there is a need for sudden acceleration of the vehicle, to overtake for example. In this case, a sensor detects a sudden action on the accelerator pedal and triggers the device for moving the thrust bearing 121 thus increasing the plating force on the drive pulley 110, which causes the flanges of said pulley and an increase in the transmission ratio. In this particular circumstance, the electric motor 2 'can also be used to increase the available power, which then acts either on a wheel D, the distributor clutch 12 being open, or on the two wheels G, D in parallel with the heat engine, the distributor clutch 12 being engaged. The three embodiments described above allow a compact installation of the transmission device, adapted to predominantly urban use vehicles. According to a fourth embodiment shown in FIG. 4, the splitter clutch 12 is completed by a linkage clutch 21 between the wheels of the axle placed between the receiving gears 112, 212. The two wheels of the axle are then systematically linked in rotation, the link clutch 21 being engaged when the vehicle is moving in a straight line. This configuration, which improves vehicle performance and heading capability, will be preferred for vehicles whose urban use must be complemented by higher performance in terms of road services. Thus, the link clutch 21 remains engaged as long as the vehicle is moving in a straight line, that is to say as long as the speeds of the two wheels G, D of the propulsion train are identical or differ only by a value less than a determined threshold, or as the steering angle given to the steering wheel G ', D' by the steering wheel is zero. When the linkage clutch 21 is engaged, the dispatcher clutch 12 is open. The losses are limited and the engine torque is transmitted to the two wheels of the propulsion train, and this that the propulsion mode is purely electric, purely thermal, or mixed, thus providing the vehicle with maximum traction. When the vehicle is traveling along a curved path, the linkage clutch 21 is open and the splitter clutch 12 controls the transmission of the torque between the left and right wheels D of the propulsion train, so as to register the vehicle in the requested trajectory . Said trajectory can be determined by the analysis of information such as the speed of the driving or steering wheels, the angle of the steering wheels and the angle of the steering wheel. The transition between the straight-line driving configuration and the curved trajectory configuration of the vehicle is done in a progressive manner by opening and engaging the coupling clutch 21 and distributor 12 devices. At the exit of the curved trajectory, by engaging the linkage clutch 21, the latter ensures the return in a straight line, always in a progressive manner, the difference in torque between the wheels G, D being controlled by the limitation of the torque passing through said clutch. The link clutch 21 being open in curved trajectory situations, the behavior of the transmission device during the course of such trajectories by the vehicle is described below in the case of its third embodiment. Those skilled in the art will easily deduce the behavior of the device in the other embodiments and in equivalent driving situations. As shown in FIG. 5, the behavior of the transmission device is a function of the radius of curvature of the trajectory. This one is given by the Jeantaud / Ackermann's sketch, which defines the position of the instantaneous center of rotation I of the vehicle. This point I is obtained by the intersection of the axes of rotation of the wheels G, G ', D, D' both driving and steering, the steering wheels being driven according to a kinematic known as Jeantaud, known from the prior art.

When the radius of curvature of the trajectory is sufficiently large and the speed of the vehicle is significant, the vehicle being in purely thermal propulsion mode, the propulsive force is distributed between the drive wheels G, D, so that their respective velocities VG, VD are compatible with Jeantaud's epure. The same situation is possible in purely electric propulsion mode, the clutch 11 of the heat engine 1 'then being open, so that said engine does not induce an additional resistive torque in the transmission. The splitter clutch 12 plays a role of differential and cash differences VG speeds, VD between the wheels, so that the smaller the radius of curvature of the trajectory, the lower the contact pressure of the discs of said clutch is high and therefore the torque passing through it is reduced. When the radius of curvature becomes too weak, the distributor clutch 12 is open and the motor, whatever the mode of propulsion, acts only on a single wheel. The splitter clutch 12 is open, it is possible to use jointly the two motors each acting on a single wheel. This configuration is advantageous especially in the case of a full load start when the steering wheels G ', D' are pointed. The control of the distributor clutch 12 of the engines 1 'and the electric motor 2', of the clutch of the heat engine 11, and the plating force of the drive pulley 110 of the variator, is preferably achieved by means of a calculator which takes into account the steering angles a, R of the front wheels G ', D', the speeds of the front and rear wheels, the steering angle of the steering wheel and the action of the driver on the accelerator, these parameters are considered both in their value and in their dynamics of evolution. As shown in FIG. 6, the vehicle being provided with a particular kinematic direction known from the prior art (not shown) and able to authorize this configuration, the transmission device according to the invention, applied to the propulsion train and not director of said vehicle, can be used for robberies with a small radius of curvature. In this case, the inner wheel at the turn G is temporarily locked by a brake (not shown) and the other wheel D ensures the propulsion curve of the vehicle, either by the electric motor 2 ', or by the heat engine 1', the splitter clutch 12 being open. Thus, the instantaneous center of rotation of the vehicle is placed on the locked wheel and the turning radius is less than the length of the vehicle, which is particularly advantageous for maneuvers in urban driving. As shown in FIG. 7, the transmission device according to the invention can be implemented in a vehicle with a single steering wheel C to obtain even shorter turning radii.

The splitter clutch 12 being open, the wheels G, D of the propulsion train are driven, one G by the heat engine 1 ', the other D by the electric motor 2' in opposite rotational directions, so that the traveling speeds VD, VG of said wheels are of opposite directions and that the instantaneous center of rotation I is between the wheels G, D of the propulsion train. The single steering wheel C being placed tangentially to the trajectory, the vehicle rotates around a point I located on the propulsive axle. The driving examples of the transmission device during curved paths have been presented above in a configuration where the propulsion train is placed at the rear of the vehicle and the steering gear at the front of the latter. Those skilled in the art will understand without difficulty that the power train can be placed at the front of the vehicle and the steering gear at the rear. This embodiment can be particularly advantageous in the case of a single steering wheel vehicle (see Figure 7), the power train is likely to provide better protection of the passenger in case of frontal impact.

Whatever the embodiment, the drive of the vehicle in reverse is preferably performed by the electric motor 2 ', the latter acting on one of the wheels of the power train or both, the clutch 11 of the engine thermal 1 'being then open. Alternatively, the engine can be used for moving the vehicle in reverse. In this case, it is necessary to add a reversing housing to the output of the motor shaft. The transmission device according to the invention can advantageously be used to recharge the electric accumulators of the hybrid vehicle, the invertible electric motor 2 'then being used in generator mode. According to a first configuration, the device can recover the deceleration energy. In this case, the clutch 11 of the heat engine being open, the distribution clutch 12 or the connecting clutch 21 are engaged, so that the braking induced by the kinetic energy sampling of the engine 2 'in Generator mode acts uniformly on both wheels. Thus, this energy recovery mode can be activated only during the evolution of the vehicle in a straight line or along curved paths with a large radius of curvature. The activation and deactivation of this mode of energy recovery are advantageously controlled by a computer scanning the speed and angle parameters mentioned above. According to another configuration, the electric accumulators can be recharged by taking part of the energy of the heat engine 1 ', the electric motor 2' acting in generator mode. The coupling between the heat engine 1 'and the electric motor 2' simply takes place by the distributor clutch 12 or the link clutch 21, according to the chosen embodiment. This charging mode of accumulators will therefore only be used when the vehicle is moving in a straight line or in curves with a large radius of curvature.

Other embodiments can be deduced from the description above without departing from the scope of the present invention. In particular, it is conceivable to insert an automatic gearbox, manual or manual driven between the heat engine and the pulley drive.

The above description clearly illustrates that by its different characteristics and advantages, the present invention achieves the objectives it has set for itself. In particular, it provides a vehicle incorporating such a transmission of specific features, advantageous for the maneuverability and traction of the latter.

Claims (10)

CLAIMS1 Device (100) for transmitting power to a propulsion train comprising two parallel wheels (G, D) of a motor vehicle, characterized in that it comprises: a first motor (1) comprising a driving shaft (101) ) and first means (10) adapted to transmit the power of said engine to a first wheel (G) of the propulsion train; a second motor (2) comprising a motor shaft (20), and second means (20) capable of transmitting the power of said second motor to a second wheel (D) of the propulsion train; - Kinematic connection means between the two motors (1, 2) comprising a distributor clutch (12) and means for controlling the torque transmitted by said clutch so that each motor can drive the wheel to which it is linked independently or in conjunction with the other motor. 2. Device according to claim 1, characterized in that the first motor is an internal combustion engine (1 '), the second motor is an electric motor (2'), and in that the first transmission means comprise an clutch (1) at the output of the motor shaft (101) of the first motor (1 '). 3. Device according to claim 2, characterized in that the first 25 transmission means comprise a continuously variable transmission (110, 110 ', 111, 120). 4. Device according to claim 3, characterized in that the continuously variable transmission comprises a variator comprising a driving pulley (110) and a receiving pulley (110 ') both with movable frustoconical flanges plated by means (120, 121) producing a plating force on a trapezoidal transmission belt (111). 5. Device according to claim 4, characterized in that it comprises means (121) adapted to modify during operation of the drive the plating force of the belt (111) in the groove of the drive pulley (110). 6. Device according to claim 1, characterized in that the first and the second transmission means comprise a homokinetic transmission joint (130, 140). 7. Device according to claim 1, characterized in that it comprises kinematic connecting means between the first and the second transmission means, which means comprise a connecting clutch (21). 8. A method for controlling the splitter clutch (12) of a device according to claim 1, integrated in a motor vehicle, characterized in that it comprises a control mode consisting in controlling the torque transmission by said clutch. according to the speed (VG, VD) of each of the wheels of the propulsion train in order to make said speeds consistent with the trajectory of said vehicle. 9. A method for controlling the link clutch (21) of a device according to claim 7, integrated in a motor vehicle, characterized in that it comprises a control mode consisting in controlling the torque transmission by said clutch (21) for returning the vehicle in a rectilinear path at the exit of a curved path, the splitter clutch (12) being disengaged. 10. A method for controlling the means (121) for modifying the plating force of the belt (111) in the drive pulley (110) of the drive of a device according to claim 5, integrated in a motor vehicle, characterized in that it comprises a step of increasing the plating force of said pulley in the event of sudden loading of the accelerator of said vehicle.