WO2007138222A1

WO2007138222A1 - System for steering a hybrid vehicle comprising four driving wheels

Info

Publication number: WO2007138222A1
Application number: PCT/FR2007/051337
Authority: WO
Inventors: Xavier Claeys; Philippe Pognant-Gros; Richard Pothin
Original assignee: Renault S.A.S.
Priority date: 2006-05-31
Filing date: 2007-05-29
Publication date: 2007-12-06
Also published as: FR2901747B1; FR2901747A1

Abstract

The invention relates to a system (10) for steering a vehicle comprising four driving wheels and two trains, a front train (20) and a rear train (18), each train being driven by an actuator. The system especially comprises a means for converting the torques (Cav, Car) applied to the trains (18, 20) into set torque values (Cm, Cel, Xemb) for controlling the actuators, and is characterised in that it comprises a regulation means for regulating the set torque values on the basis of a dynamic behaviour model of the vehicle, created by a means for modelling the dynamic behaviour of the vehicle, said regulation means controlling a means for limiting the mechanical shock effects and/or a means for ensuring a stable behaviour of the vehicle during a change in the driving situation.

Description

"Control device for a hybrid four-wheel drive vehicle"

The invention relates to a control device for a hybrid four-wheel drive vehicle. This device is more particularly applicable to a four-wheel drive hybrid vehicle comprising a heat engine driving one of the trains of the vehicle, and at least one electric actuator which is a machine or electric motor, driving the other train of the vehicle, powered by a battery and operating alone or simultaneously with the engine.

Such a device generally comprises:

- means for raising control signals;

means for calculating the static limitations of the forces or torques applied to the trains; and

means for converting the torques applied to the trains into torque setpoints for controlling the actuators.

Hybrid four-wheel-drive vehicles are typically equipped with an independent mechanical power source on each train. The front end of the vehicle is driven either by a conventional power train with an explosion engine and a manual gearbox, robot or automatic, or concurrently by a combustion engine and an electric motor. The rear axle is driven by an electric motor which is an electric machine capable of operating as a generator or motor to provide torque and power to the rear wheels via a differential. The energy storage element comprises a battery for supplying or receiving energy from one of the electrical machines operating either as a motor or as a current generator. Thus, an electric machine operating as a motor is capable of providing or absorbing a torque and a power required to the wheels of a given train. The engine associated with an electric motor in this type of hybrid vehicle can either provide additional power for road trips, or recharge the battery using a current generator or using of an electric motor when it is reversible and that it operates as a current generator.

Such a hybrid vehicle is designed, like all motor vehicles, so as to adopt the most stable behavior possible regardless of the load imposed by the driver or the condition of the road. However, some stresses can cause a loss of control of the vehicle. These are often due to an inadequate response of the vehicle because too bright and / or not enough damped and / or unpredictable, which may surprise the driver.

However, the benefits related to a hybrid vehicle, especially four-wheel drive, such as energy recovery phases or the compensation of a torque hole during a gear change can generate critical situations of this type.

In the case of four-wheel-drive hybrid vehicles, a compromise between the services of the hybrid vehicle and the services of ground connections is necessary to carry out a provision of comfort and / or safety.

An example of such a control device and control is the subject of FR-2.799.41 document 7. This document describes and represents a control device of a four-wheel drive hybrid vehicle managing the wheel distribution of the wheels. driving forces or couples depending on the conditions of the driving situation. More specifically, the management of the distribution of the driving forces is calculated from the differences in the sliding speeds between the front and rear wheels, that is to say the difference in the speeds of the wheels taken independently. Such a state of the art is based on a kinematic model of the vehicle which is insufficient to take into account the safety aspects of the vehicle during transitions of driving or braking modes in particular.

In addition, this document does not mention a method or device for managing or mitigating the mechanical shocks felt by passengers during a gear change or in energy recovery.

To reduce the unwanted behavior of a hybrid vehicle, the present invention provides a driving device of the type described above characterized in that it comprises a means for regulating the torque setpoints on the basis of a model of dynamic behavior of the vehicle performed by a means of modeling the dynamic behavior of the vehicle, said regulating means controlling a means for limiting the effects of mechanical shock and / or a means for ensuring a stable behavior of the vehicle during a change of driving situation. According to other features of the invention:

- The regulating means comprises means for determining a driving situation and a regulating means adapted to perform a regulation correction on the calculated forces or torques to limit the effects of mechanical shocks;

the means for defining a driving situation comprises:

means for detecting the sign of the torques applied to the front and rear trains of the vehicle;

- Means for detecting a shift gear ratio; and

means for determining a driving situation from the two preceding means; - The regulating means for correcting the torque setpoint comprises means for calculating longitudinal forces corrected according to the driving situation;

- The means for calculating corrected forces comprises means for imposing a control command which provides a performance during a transition phase from corrected longitudinal forces said service comprises: the scrub a torque hole; the attitude correction; the transition between modes of propulsion; and / or the transition between propulsion mode and braking mode, in particular;

the regulation correction is applied to combiners, interposed between the means for calculating the static limitations and the means for converting the torques, which are controlled by the means to limit the effects of mechanical shocks during a change of driving situation and also by the means for improving the transitions between the vehicle propulsion modes;

the vehicle comprises at least one controlled clutch interposed between an actuator and at least one train and / or a wheel and the means for converting the torques applied to the trains into actuator torque setpoints comprises means for actuating the clutch according to the type transition produced by the regulation control of the control block;

the combiners comprise means able to compare and / or combine the longitudinal forces calculated by the static limit calculation means and the corrected longitudinal forces, calculated by the dynamic transition control means; the means for converting the torques comprises means for executing a complementary torque setpoint which imposes a maintenance of the torque at a value substantially equal to zero for a predetermined time, then a progressive return to a torque setpoint emanating from the driver so as to limit the effects of mechanical shocks;

the means for calculating the static limitations of the forces or torques applied to the trains comprises means for calculating a longitudinal force value for the rear axle and a longitudinal force value for the front axle, such that they comply with a force instruction total defined by the will of the driver, which requires that the sum of the forces applied to the two trains is equal to the total effort and which is also such that a potential of adhesion to the rear train, is never higher, in absolute value at an adhesion potential on the front axle so as to satisfy a group of equations (1) which follows:

Fxtotale - Fxav + Fxar

- The control device applies to a hybrid four-wheel drive vehicle whose front end is driven by a heat engine and whose rear gear is driven by an electric machine operating either as a motor or generator-brake.

Other features and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

- Figure 1 is a general diagram illustrating the implementation of the device of the invention in a hybrid vehicle;

- Figure 2 is a block diagram showing the control device according to a particular embodiment; FIG. 3 is a graph illustrating an example of regulation according to the invention;

- Figure 4 is a block diagram showing a portion of the control device of the invention.

In the following description, we will use the longitudinal, vertical and transverse (or lateral) terminology and the indices x, y and z with reference to the trihedron L, V, T shown in FIG.

In the following description, identical, analogous or similar elements will be designated by the same reference numerals.

A hybrid vehicle, shown in a particular embodiment of the invention in FIG. 1, comprises a heat engine 12 mechanically coupled to the driving wheels of a front axle 20 of the vehicle by means of a clutch 26. - even coupled to a gearbox 28.

The vehicle also comprises an electric machine 14 which can operate as a motor or a current generator and driving the rear axle 18 of the hybrid vehicle to propel the vehicle in four-wheel drive mode.

An energy storage element 16 comprises a battery and control members so as to respect safety conditions and to avoid excessive charging or discharging of the battery.

The storage element 16 supplies the electric machine 14 with energy.

The heat engine 1 2 thus makes it possible to drive the hybrid vehicle in the case where the state of charge of the storage element 1 6 is weak, or to recharge the battery by making the electric machine 14 work in the generator mode. current. The hybrid vehicle according to the invention comprises a control device 1 0 for controlling the heat engines 12 and electrical 14 and the actuation of the clutch 26 from particular efforts or torques applied to the front and rear 20 trains 1 8 of the vehicle.

The control device 1 0 makes it possible to limit the torque setpoints Cm, CeI to be applied to the thermal motors 1 2 and the electric motor 14, as well as the Xemb actuation setpoint, of the clutch 26, so as to ensure comfort or during a transition phase.

The control device 10, shown in more detail in FIG. 2, comprises a signal detection block 40 for detecting in particular signals characteristic of the vehicle operating state, the vehicle dynamics and the driving situation.

The signal detection unit 40 comprises means for detecting, measuring or estimating the Cav and Car couples applied to the front and rear gear trains 18 and the longitudinal and vertical forces respectively denoted by Fxav, Fxar, Fzav and Fzar applied to the front and rear trains. and rear 18 of the hybrid vehicle so as to define static limitations to prevent possible locking of the wheels.

The detection unit 40 also comprises means for detecting dynamic parameters of the hybrid vehicle, such as, in particular, the steering angle of the alpha steering wheel, the longitudinal speed of the vehicle V, the yaw rate v 1, etc.

The parameters for calculating the static limitations, detected by the detection block 40, are transmitted to a block 42 for calculating static limitations which comprises means for calculating the longitudinal forces of the front axle 20, Fxav, and rear 18, Fxar, which meet the conditions of limitations static to prevent possible locking of the wheels of the hybrid vehicle.

The calculation block 42 more precisely makes it possible to saturate the longitudinal forces of the rear axle 18 by a value Fxar sat and longitudinal forces of the front axle 20 by a value Fxav sat such that they satisfy two criteria:

the first criterion is that the value of the longitudinal force Fxar must respect the fact that the sum of the longitudinal forces on the front 20 and rear 1 8 trains does not exceed a longitudinal force command, Fxtotale, imposed by the driver .

the second criterion is that a bonding potential μ of the rear axle 18, defined as being the ratio of the longitudinal force of the rear axle 18 to the vertical force of the rear axle 18, is never greater (in absolute value ) at an adhesion potential of the front axle 20, defined in the same way.

The calculation block 42 therefore comprises means for determining a saturated value of longitudinal force Fxar_sat at the rear end 1 8 and a saturated value at the front end 20 Fxav sat, starting from the total torque setpoint requested by the driver of the to satisfy the following group of equations (1):

Fxtotale - Fxav + Fxar

where Mu represents the adhesion potential defined above.

The longitudinal forces to the front 20 and rear 18 trains are transmitted via combiners 50, 52 (hereinafter described) to a converter 44 which comprises means for converting the longitudinal force instructions FZ ^nsιgne and FZ ^nsιgne into instructions to impose on the actuators of the hybrid vehicle, in particular a torque setpoint Cm for the heat engine 12, a torque setpoint CeI for the electric motor 14 and an opening setpoint Xemb of the clutch 26.

The control device 10 comprises a regulation means 54 established on a model of dynamic behavior of the vehicle so as to limit the effects of mechanical shocks during a change of driving situation and which acts on the means 42 to calculate the static limitations. and on the means 44 for converting couples.

The regulating means 54 comprises a driving situation detection block 48 transmitted to a dynamic control block 46 to provide a comfort or safety benefit when a dynamic transition phase is detected by the block 48.

The driving situation detection block 48 comprises means for analyzing the signals from the signal detection block 40, such as the alpha steering angle, the overall vehicle speed V, the torques to the front and rear trains Cav , Car, so as to determine a driving situation.

According to one embodiment of the invention, the driving situation detection unit 48 comprises means for detecting a transition between different driving modes.

The driving situation detection block 48 is shown in more detail in FIG. 4.

The block 48 comprises a first sub-block 60 which receives the values of the applied torques Cav and Car of the detection block 40 and which comprises sensors making it possible to determine the sign of the applied torques Cav, Car, to the front 20 and rear 18 trains of the hybrid vehicle to identify a type of transition.

The information on the type of transition is then transmitted to a block 64 for determining a driving situation which will be described later. Block 48 also comprises a second sub-block 62 for determining the actuation of the clutch which is connected to position sensors of the clutch pedal (not shown).

The second sub-block 62 makes it possible to determine whether the driver imposes a gearshift command.

The signals from the blocks 60 and 62 are transmitted to a block 64 which includes means for determining a given driving situation from the information collected by the previous blocks.

The information signal on the driving situation is then transmitted to the control block 46 so as to calculate corrected longitudinal forces for the front and has AR I r I i I è Crl e C, 1 π x ^c a ^o v ^rn ^e , J ψ x ^c a ^o r ^mge

The dynamic transition control unit 46 receives information on the driving situation of the hybrid vehicle of the previous block 48, and transmits longitudinal forces, F ^nge , FZr ^nge , corrected as well as information concerning the type of dynamic transition of the hybrid vehicle.

The dynamic control unit 46 comprises means for calculating corrected longitudinal forces, F ^ v ^nge and F ™ f ^n8e , the front 20 and rear 18 trains to satisfy a driving situation and provide a comfort or safety benefit.

Block 46 more specifically comprises several regulators which each perform a comfort or safety benefit. There are as many regulators as there are different driving situations.

Each regulator of the dynamic control unit 46 calculates corrected longitudinal forces F £ ^8e and FZ ^mge to the front 20 and rear 18 trains corresponding to a complementary torque setpoint DeltaCe, to be applied to the actuators of the hybrid vehicle, including 1 2 and 14 electric motors, so as to provide a performance during a dynamic transition phase.

The corrected values of longitudinal forces F ^ ^nge and

Fχar ^nge are then transmitted to combiners 50, 52.

The combiners 50 and 52 receive both the longitudinal forces values Fxav sat, Fxar sat, trains front 20 and rear August 1 calculated by the calculation block 42 and the corrected values of the longitudinal forces F and F ™ 7 ^ιge ™ _r ^mge calculated by a control block of the dynamic transition 46 so as to limit the effects of mechanical shocks during a change of driving situation.

The combiners 50 and 52 comprise means for comparing and combining the values of longitudinal forces Fxav sat, Fxar sat to the forward and backward trains 18 calculated by the calculation block of the static limitations 42 and the corrected forces.

Fχav ^nge and FZ7 ^ιge, calculated by the dynamic control block 46, so that determine setpoint efforts, F ^ v ^sιgne and P ^nominal _^ ^ P _Res _ec _t t both under static limitations and conditions of dynamic regulation in phase of change of driving situation.

An exemplary embodiment of such a control according to the invention consists for example in calculating control commands for controlling the torques applied to the motors or actuators so as to avoid the effects of mechanical shocks during a gear change or when from the transition from acceleration to braking.

An example of regulation is illustrated by the graph of FIG. 3. The graph represents the command torque Ce, imposed by the driver, as a function of time T as well as the complementary torque setpoint deltaCe added by the block. dynamic transition control system 46 which makes it possible to perform a service.

This example illustrates a change of traction mode and the corrective action applied to the control torque Ce during a sign reversal, for example, during a transition from acceleration to braking, represented by a change of sign. of the command order Ce.

The regulation block 46 also makes it possible to provide a performance during other phases of transitions such as for example:

- the exfoliation of a couple's hole;

- the attitude correction;

- the transition between modes of propulsion; and or

- the transition between propulsion mode and braking mode, etc.

During the transition from acceleration to braking (inversion of the sign of Ce), the complementary torque setpoint deltaCe imposes a maintenance of the torque at a value substantially equal to zero for a predetermined time, then a progressive return to the torque setpoint Ce .

The predetermined delay time makes it possible to modify the torque rocker in four-wheel drive mode in order to make the vehicle more stable, or to facilitate the detection of dangerous situations.

In this case, the additional control setpoint deltaCe, added by the regulator, makes it possible to "soften" the transition from acceleration to braking and thus avoid the effects of mechanical shocks felt by the passengers and which can disturb the stability of the vehicle. on the road.

Another example of control not shown is for example to delay the release of torque to the rear train Car during the foot lift of the accelerator for a period given to allow a better detection of risk situations during a change of driving situation, such as a change of propulsion mode.

Claims

REVEN DICATIONS

1. A device (1 0) for driving a four-wheel drive vehicle comprising two trains, a front axle (20) and a rear axle (18) and each train of which is driven by an actuator, the device comprises:

means (40) for picking up control signals and producing load indications (Fxav, Fxar) for each of the trains;

means (44) for converting the force instructions (Fxav, Fxar) for each of the trains (1 8, 20) into torque setpoints (Cm, CeI, Xemb) for controlling the actuators of the front axle and the rear axle , characterized in that it comprises means (54) for dynamically correcting the force references (Fxav, Fxar) so as to limit the effects of mechanical shock and / or in such a way as to ensure a stable behavior of the vehicle when a change of driving situation.

2. Control device (1 0) according to claim 1, characterized in that the means (54) for dynamic correction comprises means (48) for determining a driving situation whose output is connected to a control means (46). ) able to execute a dynamic correction of the effort instructions (Fxav, Fxar).

3. Control device (1 0) according to claim 2, characterized in that the means (48) for defining a driving situation comprises:

means (60) for detecting the sign of the pairs (Cav, Car) applied to the front (20) and rear (18) trains of the vehicle;

- means (62) for detecting a shift gear ratio; and

means (64) for determining a driving situation from the two preceding means (60, 62).

4. Piloting device (1 0) according to claim 2, characterized in that the means (46) for dynamic correction of the force references (Fxav, Fxar) comprises means for calculating longitudinal corrected forces {FZv ^nge , FZ7 ^age ) according to the driving situation.

5. Control device (1 0) according to claim 4, characterized in that the means (46) for calculating corrected forces {FZ ^mge , F ™ 7 ^ιge ) comprises means for imposing a command setpoint (deltaCe) which allows to provide a service during a transition phase from corrected longitudinal forces {FZ ^mge , FZ ^mge ), said service includes:

- the exfoliation of a couple's hole;

- the attitude correction;

- the transition between modes of propulsion; and or

- the transition between propulsion mode and braking mode, in particular.

6. Control device (10) according to any one of claims 1 to 5, characterized in that it also comprises a means (42) for calculating the static limitations of the effort guidelines (Fxav_sat, Fxar_sat) for each of trains (1 8, 20) and in that the regulation correction produced by said dynamic force setting correction means (54) (Fxav, Fxar) is applied to combiners (50, 52) interposed between the means (42) to calculate the static limitations and the means (44) for converting the torques (Cav, Car) so as to limit the effects of mechanical shocks during a change of driving situation and also in order to improve the transitions between the modes of vehicle propulsion.

7. Control device (1 0) according to claim 6, characterized in that the vehicle comprises at least one controlled clutch interposed between an actuator and at least one train and / or a wheel and in that the means (44) for converting the torques applied to the trains (18, 20) into actuator torque setpoints comprises means for actuating the clutch (26) according to the type of transition produced by the regulating control of the regulating block (46).

8. Control device (1 0) according to claim 6, characterized in that the combiners (50, 52) comprise means adapted to compare and / or combine the longitudinal forces (Fxav sat, Fxar sat) calculated by the means of calculation of static limitations (42) and corrected longitudinal forces

{FZ ^rnge , FZ ^rnge ), calculated by the dynamic transition control means (46).

9. Control device (10) according to any one of claims 6 to 8, characterized in that the means (44) for converting couples comprises means for executing a complementary torque setpoint (deltaCe) which imposes a maintenance of torque to a value substantially equal to zero for a predetermined time, then a progressive return to a torque setpoint (Ce) emanating from the driver so as to limit the effects of mechanical shocks.

10. Control device (10) according to any one of claims 6 to 9, characterized in that the means (42) for calculating the static limitations of the forces or torques (Cav, Car) applied to the trains (18, 20 ) comprises means for calculating a longitudinal force value for the rear axle (Fxar) and a longitudinal force value for the front axle (Fxav) such that they respect a total effort setpoint (Fxtotale) defined by the will of the driver, which imposes that the sum of the forces applied to the two trains (20) and (18) is equal to the total effort (Fxtotale) and which is also such that a potential of adhesion (μ) to the rear axle (18) ), never be higher, in value absolute, at an adhesion potential on the front axle (20) so as to satisfy a group of equations (1) which follows:

Fxtotale - Fxav + Fxar

11. Control device (10) according to any one of the preceding claims, characterized in that it applies to a four-wheel drive hybrid vehicle whose front axle (20) is driven by a heat engine (12) and whose rear axle (18) is driven by an electric machine (14) operating either as a motor or a brake generator.