WO2004033266A1 - System and method for controlling braking force for a motor vehicle - Google Patents

System and method for controlling braking force for a motor vehicle Download PDF

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Publication number
WO2004033266A1
WO2004033266A1 PCT/FR2003/002946 FR0302946W WO2004033266A1 WO 2004033266 A1 WO2004033266 A1 WO 2004033266A1 FR 0302946 W FR0302946 W FR 0302946W WO 2004033266 A1 WO2004033266 A1 WO 2004033266A1
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WO
WIPO (PCT)
Prior art keywords
vehicle
braking
correction
slope
driver
Prior art date
Application number
PCT/FR2003/002946
Other languages
French (fr)
Inventor
Michel Ferreira
Gérald Leminoux
Richard Pothin
Arnaud Richard
Géraldine Vourc'h
Original Assignee
Renault S.A.S.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Renault S.A.S. filed Critical Renault S.A.S.
Priority to JP2004542561A priority Critical patent/JP2006502041A/en
Priority to EP03807875A priority patent/EP1549537A1/en
Publication of WO2004033266A1 publication Critical patent/WO2004033266A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/18—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to vehicle weight or load, e.g. load distribution
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/17—Using electrical or electronic regulation means to control braking
    • B60T8/172—Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/17—Using electrical or electronic regulation means to control braking
    • B60T8/176—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS
    • B60T8/1766—Proportioning of brake forces according to vehicle axle loads, e.g. front to rear of vehicle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T2201/00—Particular use of vehicle brake systems; Special systems using also the brakes; Special software modules within the brake system controller
    • B60T2201/06—Hill holder; Start aid systems on inclined road
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T2250/00—Monitoring, detecting, estimating vehicle conditions
    • B60T2250/02—Vehicle mass

Definitions

  • the present invention relates to the control of the braking force applied to at least one wheel of a motor vehicle by a controllable braking device, in particular during the phases of holding or sliding the vehicle on a slope.
  • controllable braking devices require for their implementation a precise knowledge of the longitudinal force exerted on the vehicle due to the slope of the roadway.
  • this longitudinal force depends on variable parameters, such as the mass of the vehicle and the slope of the road.
  • a braking force for maintaining the vehicle or for controlled sliding is not correctly defined, so that the controllable braking device is not satisfactory, the vehicle remaining stationary then that the driver wishes to move it or, conversely, the vehicle does not move contrary to the driver's wish.
  • These malfunctions can be due to one of the following three causes.
  • the instantaneous mass of the vehicle may not have been properly determined.
  • the measurement of the slope of the roadway on which the vehicle is located may be incorrect.
  • the braking system of the vehicle may be defective or its efficiency reduced, so that the desired force is not effectively achieved by the braking system.
  • controllable braking device does not take account of this modification of the real mass of the vehicle, it is understood that the real longitudinal force F, becomes greater than the theoretical longitudinal force F t , so that the vehicle slides down the slope from of time t contrary to the driver's desire.
  • the braking force is overestimated by the device, since it is calculated from a mass of the vehicle greater than the actual mass of the vehicle. From t l 5 the braking force is on the contrary underestimated, because the theoretical mass of the vehicle used for the calculation is less than the real mass of the vehicle.
  • the vehicle is also stopped on a slope and is automatically held by the controllable braking device.
  • the longitudinal force F j is illustrated in solid lines and the theoretical longitudinal force F t is illustrated in dotted lines.
  • FIG. 2 also shows in dashed lines the actual longitudinal holding force F r . During the time between t 0 and t 1; the vehicle is maintained automatically.
  • the braking force which is equal to the theoretical longitudinal force F t is greater than the actual holding force F r which would be necessary, for example, due to an error in determining the actual slope of the roadway on which find the vehicle. Such an error can be due for example to a lack of precision of the slope sensor or to a pitching effect of the vehicle.
  • the driver wishes to slide his vehicle down the slope and orders a lower longitudinal force Fj for the braking system, this force being weaker than the theoretical force F t for maintaining the vehicle, as calculated by the braking device.
  • the value of the slope used by the system to calculate the theoretical force F t being overestimated, the braking force which becomes equal to the longitudinal force F 1? remains too large, that is to say still greater than the actual holding force F r of the vehicle. The vehicle therefore remains maintained and does not move after time t l 9 despite the contrary wish of the driver.
  • French patent application 2,746,357 has provided for a device acting on the braking system of a road vehicle equipped with an automatic transmission, comprising a stepwise increase of 5 bars in the pressure in the braking system. during a movement during a maintenance phase.
  • the pressure generated by the driver on the brake pedal is used to immobilize the vehicle, then, in all cases, 5 bars are added to keep the vehicle stationary. If the vehicle is still moving, 5 bars are added again, so as to maintain the immobility of the vehicle.
  • Such a device acting in stages does not make it possible to determine the minimum effective pressure which would allow the vehicle to be maintained.
  • the maintenance of the vehicle is obtained by constantly overestimating the necessary braking force, which implies unnecessary fatigue of the actuators.
  • the device takes into account an action of the driver on the accelerator which does not allow fine management of the sliding of the vehicle on the slope.
  • the object of the present invention is to solve the drawbacks of the prior device and to allow fine and precise control of the vehicle braking system during the sliding phases.
  • the invention also relates to a device and a method for optimizing the braking members of the vehicle and saving braking energy.
  • the system of the invention is suitable for controlling the braking force applied to at least one wheel of a motor vehicle by a controllable braking device, comprising various sensors of vehicle parameters as well as means for detecting an action of the driver for the purpose of moving or stopping the vehicle.
  • the system also includes a computer receiving information from the aforementioned sensors and means and capable of calculating a braking setpoint for the braking device.
  • the computer is adapted to receive signals from sensors of the vehicle mass and of the slope of the roadway on which the vehicle is located in order to determine the braking setpoint.
  • a device for correcting the braking setpoint is also provided.
  • a corrective function is thus inserted between the preparation by calculation of the braking setpoint from the signals supplied by the various sensors of the vehicle parameters and the actuation stage of the actual braking device. It is then possible, during the vehicle sliding phases, to finely and precisely manage the vehicle sliding on a slope, taking into account the effective mass of the vehicle at all times and the slope of the roadway.
  • the correction device is capable of calculating a variable correction factor, for example as a function of time and according to the nature of the action exerted by the driver.
  • a variable correction factor for example as a function of time and according to the nature of the action exerted by the driver.
  • the braking force is adjusted to the actual situation of the vehicle by progressive increase or decrease in the theoretical braking force calculated as a function of the mass of the vehicle and the slope of the roadway.
  • the correction factor can also take into account the movement of the vehicle.
  • the correction device can take account of the theoretical longitudinal force exerted on the vehicle due to the slope and the set value of the theoretical braking force.
  • the control method according to the invention of the braking force applied to at least one wheel of a motor vehicle comprises controlling the braking by detecting different parameters of the vehicle as well as actions of the driver with a view to moving or l stop the vehicle and calculate a braking setpoint.
  • the mass of the vehicle is taken into account as well as the slope of the roadway on which the vehicle is located in order to determine the braking setpoint value, then a correction is applied to the braking setpoint value thus determined. .
  • the correction applied is preferably variable, for example depending on the time and the nature of the action exerted by the driver. It can also take into account the movement of the vehicle.
  • the correction applied can take account of the theoretical longitudinal force exerted on the vehicle due to the slope and the set value of the theoretical braking force.
  • FIG. 3 is a schematic representation of the main elements of a control device according to the invention, in one embodiment
  • a control system allows the application of a braking force to the four wheels 1 of a motor vehicle 2, illustrated very schematically.
  • the control system comprises a controllable braking device 3, which is capable of applying, via the connections or lines 4, a signal to wheel braking actuators 1.
  • the controllable braking device can, as a variant, act only on one or some of the vehicle's wheels.
  • the actuators creating the effective braking force on the wheels 1 of the vehicle 2 are not shown in the figure and may be of the electric type, of the electrohydraulic type or of another suitable type, the invention being applicable whatever the braking device structure.
  • a sensor 3 also shows, by way of example, various sensors, such as the sensor 5 capable of detecting operating parameters of the vehicle, and in particular its speed or its displacement.
  • a sensor or a mass estimator 6 makes it possible to detect the instantaneous mass of the vehicle.
  • a sensor 7 is capable of determining a desire for action by the driver, whether it is an action on the accelerator pedal, the brake pedal, or even a manual action on a control device on which the driver can act.
  • the slope of the roadway on which the vehicle is located is also detected by a sensor 8.
  • a correction device 10 receives the value of the theoretical braking setpoint C t via the connection 11 from the computer 9.
  • the correction device 10 is capable of adjusting the theoretical braking setpoint C t by applying a correction, so to send a signal corresponding to the braking setpoint C f which is then applied to the controllable braking device 3.
  • the correction device 10 receives, via connection 12, a signal corresponding to the value of the theoretical longitudinal force exerted by the slope on the vehicle, noted F t .
  • the correction device 10 also receives, via the connection 13, a signal corresponding to the existence or not of a movement of the vehicle, referenced D.
  • FIG. 4 schematically illustrates the principle of embodiment of a control system according to the invention, allowing the correction of the theoretical braking setpoint C t .
  • FIG. 4 illustrates, more precisely, the structure of the correction device referenced 10 in FIG. 3.
  • the correction device 10 receives the signals D,
  • the correction device 10 comprises a first inverter 14 and a second inverter 15 which receive the value of the force theoretical longitudinal F t and apply a minus sign to it before transferring this signal thus inverted by the respective connections 16 and 17 to two comparison blocks 18 and 19 which also receive by the connections 20 and 21 the signal corresponding to the force setpoint of theoretical braking C t .
  • Block 18 compares the respective values of the theoretical braking force setpoint C t and the theoretical longitudinal force F t and emits on its output 22 a signal if C t is greater than or equal to F t , which corresponds to a will the driver to keep the vehicle stationary on a sloping road surface.
  • connection 22 The signal emitted by the connection 22 is applied to the input of an AND logic gate 23 which also receives a signal corresponding to the movement D of the vehicle by the connection 24. If two signals are applied simultaneously to the inputs 22 and 24 of the AND gate 23, it emits a signal on its output 25 which is applied to one of the inputs of a summing element 26.
  • connection 33 is then +1. It is therefore a situation in which the driver wishes to keep the vehicle stopped, while a movement of the vehicle is detected.
  • the comparison block 19 emits on its output 27 a signal when C t is less than F t , which corresponds to a desire of the driver to move the vehicle.
  • the signal thus emitted at the output 27 of the comparator 19 is applied to one of the inputs of an AND logic gate, referenced 28.
  • the AND gate 28 receives on its second input 29 a signal emitted by a NON gate which receives the signal corresponding to the movement of the vehicle D via the connection 31.
  • a signal is emitted at the output 32 of the AND gate 28 when the latter simultaneously receives a signal on its two inputs 27 and 29. This occurs when the driver wishes to set the vehicle in motion , when it is detected that the vehicle remains stationary. In such a situation, a signal is therefore applied to the second input 32 of the summing element 26.
  • the output signal of the summing 26 appearing on the connection 33 is then -1.
  • the output 33 of the summator 26 is connected to an amplifier 34 of a predetermined coefficient K which is assigned the sign + or the sign -.
  • the output signal 35 is applied to an integrator device 36 which, in the example illustrated, is saturated at the values 0 and 2 and initialized at the value 1.
  • the output signal from the integrator 36 corresponds to the corrective factor C applied to the theoretical braking force setpoint C t .
  • This corrective factor C is applied by the connection 37 to one of the inputs of a multiplier 38 which also receives on its second input 39 the value of the theoretical braking setpoint C t .
  • At the output 40 of the multiplier 38 is therefore emitted the corrected setpoint signal for the controllable braking device of the vehicle.
  • K a constant for adjusting the speed of change of the correction factor C.
  • K can be chosen by the skilled person as a function of the time of reaction, taking into account in particular passenger comfort and the inertia of the vehicle and the entire braking device.
  • FIG. 5 shows, as a function of time T, the displacements D of the vehicle, the variations in the malfunction d and finally the variations in the correction factor C.
  • the driver wishes to keep the vehicle stationary on the sloping roadway as was the case in the situation illustrated in FIG. 1.
  • the system of the invention however detects a movement of the vehicle not desired by the driver, and this from time tj.
  • the fault corresponding to non-fulfillment of the driver's wishes has a duration between t x and t 2 . This results in a movement D of the vehicle until it stops at time t 2 .
  • the correction coefficient C goes from a lower value to a higher value after time t 2 with a continuous increase between t x and t 2 , the slope of this increase depending on the value of the constant K.
  • the vehicle is immobilized, in accordance with the wishes of the driver after the expiration of a duration corresponding to t 2 -t ls duration which can be adapted at will by modifying the constant K.
  • the driver wishes to slide the vehicle down the slope from the instant t t .
  • the braking force F f is equal to the theoretical longitudinal force which is overestimated, so that the vehicle does not move.
  • the correction coefficient C is equal to 1. From time t 1; the driver expresses the wish to move the vehicle.
  • the corrective factor C decreases from time t x to time t 2 , from which the braking force F f ⁇ CxFj becomes less than the actual longitudinal force F lt From this moment t 2 , the vehicle moves and the distance traveled D increases progressively.
  • the duration of the fault is limited between times t ! and t 2 . This duration can be modified by acting on the constant K which allows adjustment of the rate of change of the correction factor C.
  • the present invention thus described allows the use of the minimum braking force by increasing the reliability of the value of this force, thus making unnecessary the systematic overestimation of the holding force of the vehicle. It becomes possible to finely control the vehicle's braking device during the sliding phases.
  • the invention it is possible to slide the vehicle while removing a small part of the longitudinal force. A more comfortable withdrawal of the holding force is also obtained during the starting phases by applying a minimum effort. Thanks to the invention, it is possible to optimize the braking members which no longer need to be oversized and whose wear is reduced.
  • the braking force applied is just necessary to push the vehicle by applying a small force to it if the driver wishes to move it during a sliding phase.
  • control system and the control method of the invention thus make it possible to overcome the variation in the instantaneous mass of the vehicle as errors in measuring the slope of the roadway as well as possible variations in the efficiency of the device.
  • controllable braking system in order to keep a vehicle on a slope with a minimum braking force or to obtain a desired displacement by a just sufficient reduction in the applied braking force.

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Regulating Braking Force (AREA)

Abstract

The invention concerns a system for controlling the braking force applied to at least one wheel of a motor vehicle by a controllable braking device, comprising various sensors (5) of the vehicle parameters as well as means for detecting an action of the driver for moving or stopping the vehicle and a calculator (9) receiving the data from the sensors and said means and capable of calculating a braking setpoint value for the braking device. The invention is characterized in that the calculator (9) is adapted to receive signals from sensors of the vehicle mass as well as the slope of the road surface whereon the vehicle is to determine the braking setpoint value Ct and in that a device (10) for correcting the braking setpoint value is further provided.

Description

Système et procédé de commande de la force de freinage pour un véhicule automobile.System and method for controlling the braking force for a motor vehicle.
La présente invention est relative à la commande de la force de freinage appliquée à au moins une roue d'un véhicule automobile par un dispositif de freinage pilotable, en particulier lors des phases de maintien ou de glissement du véhicule dans une pente.The present invention relates to the control of the braking force applied to at least one wheel of a motor vehicle by a controllable braking device, in particular during the phases of holding or sliding the vehicle on a slope.
Il peut être avantageux d' équiper un véhicule automobile d' un dispositif de freinage pilotable, qui permet la réalisation de différentes fonctions de freinage et en particulier le maintien automatique du véhicule dans une pente ou l' aide à la manœuvre par limitation de l' accélération du véhicule due à la pente de la chaussée, par exemple lors d'une manœuvre de parcage du véhicule.It may be advantageous to equip a motor vehicle with a controllable braking device, which allows the performance of different braking functions and in particular the automatic maintenance of the vehicle on a slope or the assistance to maneuver by limiting the vehicle acceleration due to the slope of the road, for example when parking the vehicle.
De tels dispositifs de freinage pilotables nécessitent pour leur mise en œuvre une connaissance précise de la force longitudinale exercée sur le véhicule en raison de la pente de la chaussée. Or, cette force longitudinale dépend de paramètres variables, tels que la masse du véhicule et la pente de la chaussée.Such controllable braking devices require for their implementation a precise knowledge of the longitudinal force exerted on the vehicle due to the slope of the roadway. However, this longitudinal force depends on variable parameters, such as the mass of the vehicle and the slope of the road.
Il peut se faire, dans la pratique, qu' un effort de freinage pour le maintien du véhicule ou pour un glissement contrôlé, ne soit pas correctement défini, de sorte que le dispositif de freinage pilotable ne donne pas satisfaction, le véhicule restant immobile alors que le conducteur souhaite le déplacer ou, à l'inverse, le véhicule ne se déplaçant pas contrairement au souhait du conducteur. Ces défauts de fonctionnement peuvent être dûs à l'une des trois causes suivantes. La masse instantanée du véhicule peut ne pas avoir été déterminée convenablement. La mesure de la pente de la chaussée sur laquelle se trouve le véhicule peut être erronée. Enfin, le système de freinage du véhicule peut être défectueux ou son efficacité diminuée, de telle sorte que la force souhaitée n' est pas effectivement réalisée par le système de freinage.In practice, it may happen that a braking force for maintaining the vehicle or for controlled sliding is not correctly defined, so that the controllable braking device is not satisfactory, the vehicle remaining stationary then that the driver wishes to move it or, conversely, the vehicle does not move contrary to the driver's wish. These malfunctions can be due to one of the following three causes. The instantaneous mass of the vehicle may not have been properly determined. The measurement of the slope of the roadway on which the vehicle is located may be incorrect. Finally, the braking system of the vehicle may be defective or its efficiency reduced, so that the desired force is not effectively achieved by the braking system.
Les figures annexées 1 et 2 illustrent, à titre d' exemple, deux situations de ce type, dans lesquelles l' effort de freinage appliqué n'est pas satisfaisant. Sur ces deux figures, on a représenté en ordonnées les forces intervenant dans un tel système, à savoir la force de freinage et la force longitudinale appliquée au véhicule immobile dans une pente. On rappellera à cet égard que la force longitudinale ¥λ est donnée par la relation :The appended figures 1 and 2 illustrate, by way of example, two situations of this type, in which the braking force applied is not satisfactory. In these two figures, there is shown in ordered the forces involved in such a system, namely the braking force and the longitudinal force applied to the stationary vehicle on a slope. It will be recalled in this regard that the longitudinal force ¥ λ is given by the relation:
F, = P x g x MF, = P x g x M
où P est la valeur de la pente sur laquelle le véhicule est arrêté exprimée en pourcentage ; g l' accélération de la pesanteur (égale à environ 9,81 m/s2) ; et M est la masse du véhicule exprimée en kg. Sur la figure 1 , la force longitudinale Ft est représentée en traits pleins, tandis que la force longitudinale théorique Ft est représentée en pointillés. En abscisses, on a fait figurer le temps T.where P is the value of the slope on which the vehicle is stopped expressed as a percentage; g the acceleration of gravity (equal to approximately 9.81 m / s 2 ); and M is the mass of the vehicle expressed in kg. In FIG. 1, the longitudinal force F t is shown in solid lines, while the theoretical longitudinal force F t is shown in dotted lines. On the abscissa, we have shown the time T.
Dans le cas de la figure 1, le véhicule se trouve arrêté et maintenu automatiquement dans une pente par le dispositif de freinage pilotable dont il est équipé. Tant que la masse réelle du véhicule est inférieure à la masse utilisée pour le calcul de la force longitudinale théorique Ft, le véhicule est maintenu arrêté sur la pente. Cette situation se poursuit, du temps t0 au temps tx . Au temps tl 5 on imagine que la charge du véhicule est augmentée, par exemple par l' ajout de passagers ou de bagages. Il en résulte une modification de la masse réelle instantanée du véhicule. Si le dispositif de freinage pilotable ne tient pas compte de cette modification de la masse réelle du véhicule, on comprend que la force longitudinale réelle F, devient supérieure à la force longitudinale théorique Ft, de sorte que le véhicule glisse dans la pente à partir du temps t contrairement au désir du conducteur.In the case of Figure 1, the vehicle is stopped and automatically maintained on a slope by the controllable braking device with which it is equipped. As long as the actual mass of the vehicle is less than the mass used for calculating the theoretical longitudinal force F t , the vehicle is kept stationary on the slope. This situation continues, from time t 0 to time t x . At time t l 5 we imagine that the vehicle load is increased, for example by adding passengers or luggage. This results in a modification of the instantaneous real mass of the vehicle. If the controllable braking device does not take account of this modification of the real mass of the vehicle, it is understood that the real longitudinal force F, becomes greater than the theoretical longitudinal force F t , so that the vehicle slides down the slope from of time t contrary to the driver's desire.
Entre les temps t0 et tx, la force de freinage est surestimée par le dispositif, car elle est calculée à partir d' une masse du véhicule supérieure à la masse réelle du véhicule. A partir de tl 5 la force de freinage est au contraire sous-estimée, car la masse théorique du véhicule utilisée pour le calcul est inférieure à la masse réelle du véhicule. Dans une autre situation illustrée sur la figure 2, le véhicule est également arrêté dans une pente et est maintenu automatiquement par le dispositif de freinage pilotable. Comme sur la figure précédente, la force longitudinale Fj est illustrée en traits pleins et la force longitudinale théorique Ft est illustrée en pointillés. On a également fait figurer sur la figure 2, en tirets, la force longitudinale de maintien réelle Fr. Pendant le temps compris entre t0 et t1 ; le véhicule est maintenu automatiquement. La force de freinage qui est égale à la force longitudinale théorique Ft est supérieure à la force de maintien réelle Fr qui serait nécessaire, par exemple, en raison d' une erreur sur la détermination de la pente réelle de la chaussée sur laquelle se trouve le véhicule. Une telle erreur peut être due par exemple à un défaut de précision du capteur de pente ou à un effet de tangage du véhicule. A l'instant T, le conducteur souhaite faire glisser son véhicule dans la pente et commande une force longitudinale Fj inférieure pour le système de freinage, cette force étant plus faible que la force théorique Ft pour le maintien du véhicule, telle que calculée par le dispositif de freinage. Toutefois, la valeur de la pente utilisée par le système pour calculer la force théorique Ft étant surestimée, la force de freinage qui devient égale à la force longitudinale F1? reste trop importante, c' est-à-dire encore supérieure à la force de maintien réelle Fr du véhicule. Le véhicule reste donc maintenu et ne se déplace pas après le temps tl 9 malgré le souhait contraire du conducteur.Between times t 0 and t x , the braking force is overestimated by the device, since it is calculated from a mass of the vehicle greater than the actual mass of the vehicle. From t l 5 the braking force is on the contrary underestimated, because the theoretical mass of the vehicle used for the calculation is less than the real mass of the vehicle. In another situation illustrated in FIG. 2, the vehicle is also stopped on a slope and is automatically held by the controllable braking device. As in the previous figure, the longitudinal force F j is illustrated in solid lines and the theoretical longitudinal force F t is illustrated in dotted lines. FIG. 2 also shows in dashed lines the actual longitudinal holding force F r . During the time between t 0 and t 1; the vehicle is maintained automatically. The braking force which is equal to the theoretical longitudinal force F t is greater than the actual holding force F r which would be necessary, for example, due to an error in determining the actual slope of the roadway on which find the vehicle. Such an error can be due for example to a lack of precision of the slope sensor or to a pitching effect of the vehicle. At the instant T, the driver wishes to slide his vehicle down the slope and orders a lower longitudinal force Fj for the braking system, this force being weaker than the theoretical force F t for maintaining the vehicle, as calculated by the braking device. However, the value of the slope used by the system to calculate the theoretical force F t being overestimated, the braking force which becomes equal to the longitudinal force F 1? remains too large, that is to say still greater than the actual holding force F r of the vehicle. The vehicle therefore remains maintained and does not move after time t l 9 despite the contrary wish of the driver.
On a prévu, dans la demande de brevet français 2 746 357, un dispositif agissant sur le système de freinage d'un véhicule routier équipé d'une boîte automatique, comportant une augmentation par palier de 5 bars de la pression dans le système de freinage lors d' un déplacement pendant une phase de maintien. Dans cette demande de brevet antérieure, on utilise la pression générée par le conducteur sur la pédale de frein, pour immobiliser le véhicule, puis, dans tous les cas, on ajoute 5 bars pour assurer le maintien du véhicule immobile. Si le véhicule se déplace encore, 5 bars sont à nouveau ajoutés, de façon à obtenir le maintien de l' immobilité du véhicule. Un tel dispositif agissant par paliers ne permet pas de déterminer la pression minimum effective qui permettrait le maintien du véhicule. Au contraire, le maintien du véhicule est obtenu en surestimant constamment la force de freinage nécessaire, ce qui implique une fatigue inutile des actionneurs. De plus, lorsque le conducteur souhaite laisser glisser le véhicule, le dispositif tient compte d' une action du conducteur sur l' accélérateur qui ne permet pas une gestion fine du glissement du véhicule dans la pente. En aucun cas, il n' est prévu, en outre, de tenir compte de la masse effective instantanée du véhicule et de la pente réelle de la chaussée sur laquelle se trouve le véhicule.French patent application 2,746,357 has provided for a device acting on the braking system of a road vehicle equipped with an automatic transmission, comprising a stepwise increase of 5 bars in the pressure in the braking system. during a movement during a maintenance phase. In this prior patent application, the pressure generated by the driver on the brake pedal is used to immobilize the vehicle, then, in all cases, 5 bars are added to keep the vehicle stationary. If the vehicle is still moving, 5 bars are added again, so as to maintain the immobility of the vehicle. Such a device acting in stages does not make it possible to determine the minimum effective pressure which would allow the vehicle to be maintained. On the contrary, the maintenance of the vehicle is obtained by constantly overestimating the necessary braking force, which implies unnecessary fatigue of the actuators. In addition, when the driver wishes to let the vehicle slide, the device takes into account an action of the driver on the accelerator which does not allow fine management of the sliding of the vehicle on the slope. In any case, provision is also made to take account of the instantaneous effective mass of the vehicle and of the actual slope of the roadway on which the vehicle is located.
La présente invention a pour objet de résoudre les inconvénients du dispositif antérieur et de permettre un pilotage fin et précis du système de freinage du véhicule pendant les phases de glissement.The object of the present invention is to solve the drawbacks of the prior device and to allow fine and precise control of the vehicle braking system during the sliding phases.
L'invention a également pour objet un dispositif et un procédé permettant l' optimisation des organes de freinage du véhicule et une économie d' énergie de freinage.The invention also relates to a device and a method for optimizing the braking members of the vehicle and saving braking energy.
Le système de l'invention est adapté à la commande de la force de freinage appliquée à au moins une roue d' un véhicule automobile par un dispositif de freinage pilotable, comprenant différents capteurs de paramètres du véhicule ainsi que des moyens pour détecter une action du conducteur en vue du déplacement ou de l' arrêt du véhicule. Le système comprend également un calculateur recevant les informations des capteurs et moyens précités et capable de calculer une valeur de consigne de freinage pour le dispositif de freinage. Le calculateur est adapté pour recevoir des signaux provenant de capteurs de la masse du véhicule ainsi que de la pente de la chaussée sur laquelle se trouve le véhicule afin de déterminer la valeur de consigne de freinage. Un dispositif de correction de la valeur de consigne de freinage est en outre prévu.The system of the invention is suitable for controlling the braking force applied to at least one wheel of a motor vehicle by a controllable braking device, comprising various sensors of vehicle parameters as well as means for detecting an action of the driver for the purpose of moving or stopping the vehicle. The system also includes a computer receiving information from the aforementioned sensors and means and capable of calculating a braking setpoint for the braking device. The computer is adapted to receive signals from sensors of the vehicle mass and of the slope of the roadway on which the vehicle is located in order to determine the braking setpoint. A device for correcting the braking setpoint is also provided.
Une fonction correctrice se trouve ainsi intercalée entre l' élaboration par calcul de la consigne de freinage à partir des signaux fournis par les différents capteurs des paramètres du véhicule et l' étage d' actionnement du dispositif de freinage proprement dit. Il est alors possible, pendant les phases de glissement du véhicule, de gérer finement et précisément le glissement du véhicule dans une pente en tenant compte de la masse effective du véhicule à chaque instant et de la pente de la chaussée.A corrective function is thus inserted between the preparation by calculation of the braking setpoint from the signals supplied by the various sensors of the vehicle parameters and the actuation stage of the actual braking device. It is then possible, during the vehicle sliding phases, to finely and precisely manage the vehicle sliding on a slope, taking into account the effective mass of the vehicle at all times and the slope of the roadway.
De préférence, le dispositif de correction est capable de calculer un facteur de correction variable, par exemple en fonction du temps et selon la nature de l' action exercée par le conducteur. De cette manière, la force de freinage est ajustée à la situation réelle du véhicule par augmentation ou diminution progressive de la force de freinage théorique calculée en fonction de la masse du véhicule et de la pente de la chaussée.Preferably, the correction device is capable of calculating a variable correction factor, for example as a function of time and according to the nature of the action exerted by the driver. In this way, the braking force is adjusted to the actual situation of the vehicle by progressive increase or decrease in the theoretical braking force calculated as a function of the mass of the vehicle and the slope of the roadway.
Le facteur de correction peut également tenir compte du déplacement du véhicule. Dans un mode de réalisation préféré, le facteur de correction est de la forme C = 1 ± Kt où K est une constante et t le temps écoulé depuis l' action du conducteur.The correction factor can also take into account the movement of the vehicle. In a preferred embodiment, the correction factor is of the form C = 1 ± Kt where K is a constant and t is the time elapsed since the action of the conductor.
Avantageusement, le dispositif de correction peut tenir compte de la force longitudinale théorique exercée sur le véhicule en raison de la pente et de la valeur de consigne de la force de freinage théorique.Advantageously, the correction device can take account of the theoretical longitudinal force exerted on the vehicle due to the slope and the set value of the theoretical braking force.
Le procédé de commande selon l'invention de la force de freinage appliquée à au moins une roue d'un véhicule automobile, comprend le pilotage du freinage par détection de différents paramètres du véhicule ainsi que des actions du conducteur en vue du déplacement ou de l' arrêt du véhicule et le calcul d'une valeur de consigne de freinage. Selon l'invention, on prend en compte la masse du véhicule ainsi que la pente de la chaussée sur laquelle se trouve le véhicule afin de déterminer la valeur de consigne de freinage, puis on applique une correction à la valeur de consigne de freinage ainsi déterminée.The control method according to the invention of the braking force applied to at least one wheel of a motor vehicle, comprises controlling the braking by detecting different parameters of the vehicle as well as actions of the driver with a view to moving or l stop the vehicle and calculate a braking setpoint. According to the invention, the mass of the vehicle is taken into account as well as the slope of the roadway on which the vehicle is located in order to determine the braking setpoint value, then a correction is applied to the braking setpoint value thus determined. .
La correction appliquée est de préférence variable, par exemple fonction du temps et de la nature de l' action exercée par le conducteur. Elle peut également tenir compte du déplacement du véhicule. De préférence, la correction appliquée est de la forme C = 1 ± Kt où K est une constante et t le temps écoulé depuis l' action du conducteur.The correction applied is preferably variable, for example depending on the time and the nature of the action exerted by the driver. It can also take into account the movement of the vehicle. Preferably, the correction applied is of the form C = 1 ± Kt where K is a constant and t the time elapsed since the action of the conductor.
Enfin, la correction appliquée peut tenir compte de la force longitudinale théorique exercée sur le véhicule en raison de la pente et de la valeur de consigne de la force de freinage théorique.Finally, the correction applied can take account of the theoretical longitudinal force exerted on the vehicle due to the slope and the set value of the theoretical braking force.
L'invention sera mieux comprise à l'étude de la description détaillée d'un mode de réalisation pris à titre d' exemple nullement limitatif et illustré par les dessins annexés, sur lesquels : - les figures 1 et 2 sont des courbes illustrant les variations des forces lors de la phase de freinage dans un dispositif de l' art antérieur ;The invention will be better understood on studying the detailed description of an embodiment taken by way of nonlimiting example and illustrated by the appended drawings, in which: - Figures 1 and 2 are curves illustrating the variations forces during the braking phase in a device of the prior art;
- la figure 3 est une représentation schématique des principaux éléments d'un dispositif de commande, selon l'invention, dans un mode de réalisation ;- Figure 3 is a schematic representation of the main elements of a control device according to the invention, in one embodiment;
- la figure 4 illustre une réalisation pratique du dispositif de correction de l'invention ; et- Figure 4 illustrates a practical embodiment of the correction device of the invention; and
- les figures 5 et 6 montrent des courbes d' évolution de la force de freinage du déplacement du véhicule et du facteur de correction de la force de freinage dans deux situations particulières, lors de l'utilisation d'un dispositif selon l'invention.- Figures 5 and 6 show curves of evolution of the braking force of the movement of the vehicle and the correction factor of the braking force in two particular situations, when using a device according to the invention.
Tel qu'il est illustré sur la figure 3, un système de commande, selon l' invention, permet l' application d' une force de freinage aux quatre roues 1 d'un véhicule automobile 2, illustré très schématiquement. Le système de commande comprend un dispositif de freinage pilotable 3, qui est capable d' appliquer, par les connexions ou conduites 4, un signal à des actionneurs de freinage des roues 1. On notera que le dispositif de freinage pilotable peut, en variante, n' agir que sur l'une des roues du véhicule ou sur quelques-unes d'entre elles. Les actionneurs créant l' effort de freinage effectif sur les roues 1 du véhicule 2 ne sont pas représentés sur la figure et peuvent être du type électrique, du type électrohydraulique ou d'un autre type approprié, l'invention étant applicable quelle que soit la structure du dispositif de freinage. La figure 3 montre également, à titre d' exemple, différents capteurs, tels que le capteur 5 capable de détecter des paramètres de fonctionnement du véhicule, et en particulier sa vitesse ou son déplacement. Un capteur ou un estimateur de masse 6 permet de détecter la masse instantanée du véhicule. Un capteur 7 est capable de déterminer une volonté d' action du conducteur, qu'il s' agisse d'une action sur la pédale d' accélérateur, la pédale de frein, ou encore d' une action manuelle sur un dispositif de commande sur lequel le conducteur peut agir. La pente de la chaussée sur laquelle se trouve le véhicule est également détectée par un capteur 8.As illustrated in FIG. 3, a control system according to the invention allows the application of a braking force to the four wheels 1 of a motor vehicle 2, illustrated very schematically. The control system comprises a controllable braking device 3, which is capable of applying, via the connections or lines 4, a signal to wheel braking actuators 1. It will be noted that the controllable braking device can, as a variant, act only on one or some of the vehicle's wheels. The actuators creating the effective braking force on the wheels 1 of the vehicle 2 are not shown in the figure and may be of the electric type, of the electrohydraulic type or of another suitable type, the invention being applicable whatever the braking device structure. FIG. 3 also shows, by way of example, various sensors, such as the sensor 5 capable of detecting operating parameters of the vehicle, and in particular its speed or its displacement. A sensor or a mass estimator 6 makes it possible to detect the instantaneous mass of the vehicle. A sensor 7 is capable of determining a desire for action by the driver, whether it is an action on the accelerator pedal, the brake pedal, or even a manual action on a control device on which the driver can act. The slope of the roadway on which the vehicle is located is also detected by a sensor 8.
Tous les signaux provenant des différents capteurs 5 à 8 sont amenés à l' entrée d'un calculateur 9, qui est capable de calculer une valeur de consigne et de freinage théorique Ct. Un dispositif de correction 10 reçoit la valeur de la consigne de freinage théorique Ct par la connexion 11 en provenance du calculateur 9. Le dispositif de correction 10 est capable d' ajuster la consigne de freinage théorique Ct en appliquant une correction, de façon à émettre un signal correspondant à la consigne de freinage Cf qui est alors appliquée au dispositif de freinage pilotable 3. En plus de la consigne de force de freinage théorique Ct, le dispositif de correction 10 reçoit, par la connexion 12, un signal correspondant à la valeur de la force longitudinale théorique exercée par la pente sur le véhicule, notée Ft. Le dispositif de correction 10 reçoit également, par la connexion 13, un signal correspondant à l' existence ou non d' un déplacement du véhicule, référencé D.All the signals coming from the various sensors 5 to 8 are brought to the input of a computer 9, which is capable of calculating a setpoint and theoretical braking value C t . A correction device 10 receives the value of the theoretical braking setpoint C t via the connection 11 from the computer 9. The correction device 10 is capable of adjusting the theoretical braking setpoint C t by applying a correction, so to send a signal corresponding to the braking setpoint C f which is then applied to the controllable braking device 3. In addition to the theoretical braking force setpoint C t , the correction device 10 receives, via connection 12, a signal corresponding to the value of the theoretical longitudinal force exerted by the slope on the vehicle, noted F t . The correction device 10 also receives, via the connection 13, a signal corresponding to the existence or not of a movement of the vehicle, referenced D.
La figure 4 illustre schématiquement le principe de réalisation d'un système de commande, selon l'invention, permettant la correction de la consigne de freinage théorique Ct. La figure 4 illustre, de manière plus précise, la structure du dispositif de correction référencé 10 sur la figure 3. Le dispositif de correction 10 reçoit les signaux D,FIG. 4 schematically illustrates the principle of embodiment of a control system according to the invention, allowing the correction of the theoretical braking setpoint C t . FIG. 4 illustrates, more precisely, the structure of the correction device referenced 10 in FIG. 3. The correction device 10 receives the signals D,
Ct et Ft élaborés par le calculateur 9 à partir des informations provenant des différents capteurs 5 à 8.C t and F t produced by the computer 9 from information coming from the various sensors 5 to 8.
Le dispositif de correction 10 comprend un premier inverseur 14 et un deuxième inverseur 15 qui reçoivent la valeur de la force longitudinale théorique Ft et lui appliquent un signe moins avant de transférer ce signal ainsi inversé par les connexions respectives 16 et 17 à deux blocs de comparaison 18 et 19 qui reçoivent également par les connexions 20 et 21 le signal correspondant à la consigne de force de freinage théorique Ct. Le bloc 18 compare les valeurs respectives de la consigne de force de freinage théorique Ct et de la force longitudinale théorique Ft et émet sur sa sortie 22 un signal si Ct est supérieur ou égal à Ft, ce qui correspond à une volonté du conducteur de maintenir le véhicule immobile sur la chaussée en pente. Le signal émis par la connexion 22 est appliqué à l' entrée d'une porte logique ET 23 qui reçoit en outre un signal correspondant au déplacement D du véhicule par la connexion 24. Si deux signaux sont appliqués simultanément aux entrées 22 et 24 de la porte ET 23 , celle-ci émet un signal sur sa sortie 25 qui est appliqué à l'une des entrées d'un élément sommateur 26. Le signal de sortie du sommateurThe correction device 10 comprises a first inverter 14 and a second inverter 15 which receive the value of the force theoretical longitudinal F t and apply a minus sign to it before transferring this signal thus inverted by the respective connections 16 and 17 to two comparison blocks 18 and 19 which also receive by the connections 20 and 21 the signal corresponding to the force setpoint of theoretical braking C t . Block 18 compares the respective values of the theoretical braking force setpoint C t and the theoretical longitudinal force F t and emits on its output 22 a signal if C t is greater than or equal to F t , which corresponds to a will the driver to keep the vehicle stationary on a sloping road surface. The signal emitted by the connection 22 is applied to the input of an AND logic gate 23 which also receives a signal corresponding to the movement D of the vehicle by the connection 24. If two signals are applied simultaneously to the inputs 22 and 24 of the AND gate 23, it emits a signal on its output 25 which is applied to one of the inputs of a summing element 26. The output signal of the summing
26 apparaissant sur la connexion 33 est alors +1. Il s' agit donc d'une situation dans laquelle le conducteur souhaite maintenir le véhicule arrêté, alors que l'on détecte un déplacement du véhicule.26 appearing on connection 33 is then +1. It is therefore a situation in which the driver wishes to keep the vehicle stopped, while a movement of the vehicle is detected.
De la même manière, le bloc de comparaison 19 émet sur sa sortie 27 un signal lorsque Ct est inférieur à Ft, ce qui correspond à une volonté du conducteur de procéder à un déplacement du véhicule. Le signal ainsi émis à la sortie 27 du comparateur 19 est appliqué à l'une des entrées d'une porte logique ET, référencée 28. La porte ET 28 reçoit sur sa deuxième entrée 29 un signal émis par une porte NON 30 qui reçoit le signal correspondant au déplacement du véhicule D par la connexion 31.In the same way, the comparison block 19 emits on its output 27 a signal when C t is less than F t , which corresponds to a desire of the driver to move the vehicle. The signal thus emitted at the output 27 of the comparator 19 is applied to one of the inputs of an AND logic gate, referenced 28. The AND gate 28 receives on its second input 29 a signal emitted by a NON gate which receives the signal corresponding to the movement of the vehicle D via the connection 31.
On comprend, dans ces conditions, qu'un signal est émis à la sortie 32 de la porte ET 28 lorsque celle-ci reçoit simultanément un signal sur ses deux entrées 27 et 29. Cela se produit lorsque le conducteur souhaite mettre le véhicule en mouvement, alors que l' on détecte que le véhicule reste immobile. Dans une telle situation, un signal est donc appliqué sur la deuxième entrée 32 de l' élément sommateur 26. Le signal de sortie du sommateur 26 apparaissant sur la connexion 33 est alors -1. La sortie 33 du sommateur 26 est reliée à un amplificateur 34 d'un coefficient prédéterminé K qui se trouve affecté du signe + ou du signe -. Le signal de sortie 35 est appliqué à un dispositif intégrateur 36 qui, dans l' exemple illustré, est saturé aux valeurs 0 et 2 et initialisé à la valeur 1. Le signal de sortie de l' intégrateur 36 correspond au facteur correctif C appliqué à la consigne de force de freinage théorique Ct. Ce facteur correctif C est appliqué par la connexion 37 à l'une des entrées d' un multiplicateur 38 qui reçoit par ailleurs sur sa deuxième entrée 39 la valeur de la consigne de freinage théorique Ct. A la sortie 40 du multiplicateur 38 se trouve donc émis le signal de consigne corrigé pour le dispositif de freinage pilotable du véhicule.It is understood, under these conditions, that a signal is emitted at the output 32 of the AND gate 28 when the latter simultaneously receives a signal on its two inputs 27 and 29. This occurs when the driver wishes to set the vehicle in motion , when it is detected that the vehicle remains stationary. In such a situation, a signal is therefore applied to the second input 32 of the summing element 26. The output signal of the summing 26 appearing on the connection 33 is then -1. The output 33 of the summator 26 is connected to an amplifier 34 of a predetermined coefficient K which is assigned the sign + or the sign -. The output signal 35 is applied to an integrator device 36 which, in the example illustrated, is saturated at the values 0 and 2 and initialized at the value 1. The output signal from the integrator 36 corresponds to the corrective factor C applied to the theoretical braking force setpoint C t . This corrective factor C is applied by the connection 37 to one of the inputs of a multiplier 38 which also receives on its second input 39 the value of the theoretical braking setpoint C t . At the output 40 of the multiplier 38 is therefore emitted the corrected setpoint signal for the controllable braking device of the vehicle.
Dans l' exemple illustré sur la figure 4, le facteur correctif C est donc égal à C = 1 ± K x tIn the example illustrated in FIG. 4, the corrective factor C is therefore equal to C = 1 ± K x t
où t est le temps écoulé depuis l' action du conducteur et K une constante de réglage de la vitesse d'évolution du facteur de correction C. La valeur de la constante K peut être choisie par l'homme du métier en fonction du temps de réaction, en tenant compte en particulier du confort des passagers et de l'inertie du véhicule et de l' ensemble du dispositif de freinage.where t is the time elapsed since the driver's action and K a constant for adjusting the speed of change of the correction factor C. The value of the constant K can be chosen by the skilled person as a function of the time of reaction, taking into account in particular passenger comfort and the inertia of the vehicle and the entire braking device.
On va maintenant décrire le fonctionnement du dispositif qui vient d' être décrit dans deux situations spécifiques, correspondant respectivement aux situations déj à explicitées en référence aux figuresWe will now describe the operation of the device which has just been described in two specific situations, corresponding respectively to the situations already explained with reference to the figures.
1 et 2.1 and 2.
Dans la situation correspondant aux courbes de la figure 5, on a représenté tout d' abord, comme sur la figure 1, les variations des forces F en fonction du temps T. La force longitudinale réelle Fx est représentée en traits pleins. On a également représenté en pointillés la force de freinage Ff qui, selon l'invention, est égale à la force longitudinale théorique Ft affectée du coefficient de correction C. On a donc Ff = C x Ft. On a également représenté sur la figure 5, en fonction du temps T, les déplacements D du véhicule, les variations du défaut de fonctionnement d et enfin les variations du facteur de correction C.In the situation corresponding to the curves of FIG. 5, the variations of the forces F as a function of time T are represented first of all, as in FIG. 1. The real longitudinal force F x is shown in solid lines. The braking force F f which, according to the invention, is equal to the theoretical longitudinal force F t affected by the correction coefficient C, is also shown in dotted lines. We therefore have F f = C x F t . FIG. 5 also shows, as a function of time T, the displacements D of the vehicle, the variations in the malfunction d and finally the variations in the correction factor C.
Dans l'exemple illustré sur la figure 5, le conducteur souhaite maintenir le véhicule à l' arrêt sur la chaussée en pente comme c' était le cas dans la situation illustrée sur la figure 1. Le système de l'invention détecte cependant un déplacement du véhicule non souhaité par le conducteur, et ce, à compter de l'instant tj. Le dispositif de correction 10 détermine, à partir du temps t , un facteur de correction C = 1 + K x t. Il en résulte, à partir du temps t1 ; une augmentation progressive de la force de freinage Ff qui, au bout du temps t2, devient égale à la force longitudinale F1; ce qui provoque le maintien du véhicule à l' arrêt.In the example illustrated in FIG. 5, the driver wishes to keep the vehicle stationary on the sloping roadway as was the case in the situation illustrated in FIG. 1. The system of the invention however detects a movement of the vehicle not desired by the driver, and this from time tj. The correction device 10 determines, from time t, a correction factor C = 1 + K x t. It follows, from time t 1; a progressive increase in the braking force F f which, at the end of time t 2 , becomes equal to the longitudinal force F 1; which keeps the vehicle stationary.
Le défaut correspondant à une non-exécution des souhaits du conducteur a une durée comprise entre tx et t2. Il en résulte un déplacement D du véhicule jusqu' à l'immobilisation au temps t2. Le coefficient de correction C passe, quant à lui, d'une valeur inférieure à une valeur supérieure après le temps t2 avec une augmentation continue entre tx et t2, la pente de cette augmentation dépendant de la valeur de la constante K.The fault corresponding to non-fulfillment of the driver's wishes has a duration between t x and t 2 . This results in a movement D of the vehicle until it stops at time t 2 . The correction coefficient C goes from a lower value to a higher value after time t 2 with a continuous increase between t x and t 2 , the slope of this increase depending on the value of the constant K.
Il en résulte que le véhicule se trouve immobilisé, conformément au souhait du conducteur après l' écoulement d'une durée correspondant à t2-tl s durée qui peut être adaptée à volonté en modifiant la constante K. Dans l'exemple illustré sur la figure 6, qui correspond à la situation illustrée sur la figure 2, le conducteur souhaite faire glisser le véhicule dans la pente à partir de l'instant tt. Entre t0 et t1 } la force de freinage Ff est égale à la force longitudinale théorique qui est surestimée, de sorte que le véhicule ne se déplace pas. Le coefficient de correction C est égal à 1. A partir de l'instant t1 ; le conducteur exprime le souhait de déplacer le véhicule. Le dispositif de l' invention applique alors un facteur correctif C=l-Kxt. Le facteur correctif C diminue depuis le temps tx jusqu' au temps t2, à partir duquel la force de freinage Ff≈CxFj devient inférieure à la force longitudinale réelle Flt A partir de ce moment t2, le véhicule se déplace et la distance parcourue D augmente progressivement. La durée du défaut est limitée entre les temps t! et t2. Cette durée peut être modifiée en agissant sur la constante K qui permet un réglage de la vitesse d' évolution du facteur de correction C.It follows that the vehicle is immobilized, in accordance with the wishes of the driver after the expiration of a duration corresponding to t 2 -t ls duration which can be adapted at will by modifying the constant K. In the example illustrated on the FIG. 6, which corresponds to the situation illustrated in FIG. 2, the driver wishes to slide the vehicle down the slope from the instant t t . Between t 0 and t 1} the braking force F f is equal to the theoretical longitudinal force which is overestimated, so that the vehicle does not move. The correction coefficient C is equal to 1. From time t 1; the driver expresses the wish to move the vehicle. The device of the invention then applies a corrective factor C = l-Kxt. The corrective factor C decreases from time t x to time t 2 , from which the braking force F f ≈CxFj becomes less than the actual longitudinal force F lt From this moment t 2 , the vehicle moves and the distance traveled D increases progressively. The duration of the fault is limited between times t ! and t 2 . This duration can be modified by acting on the constant K which allows adjustment of the rate of change of the correction factor C.
La présente invention ainsi décrite permet l'utilisation de la force de freinage minimum en fiabilisant la valeur de cette force, rendant ainsi inutile la surestimation systématique de la force de maintien du véhicule. Il devient possible de piloter finement le dispositif de freinage du véhicule pendant les phases de glissement.The present invention thus described allows the use of the minimum braking force by increasing the reliability of the value of this force, thus making unnecessary the systematic overestimation of the holding force of the vehicle. It becomes possible to finely control the vehicle's braking device during the sliding phases.
Grâce à l'invention, il est possible de faire glisser le véhicule en supprimant une faible partie de la force longitudinale. On obtient également un retrait plus confortable de la force de maintien pendant les phases de démarrage par application d'un effort minimum. Grâce à l' invention, il est possible d' optimiser les organes de freinage qui n' ont plus besoin d' être surdimensionnés et dont l' usure est réduite.Thanks to the invention, it is possible to slide the vehicle while removing a small part of the longitudinal force. A more comfortable withdrawal of the holding force is also obtained during the starting phases by applying a minimum effort. Thanks to the invention, it is possible to optimize the braking members which no longer need to be oversized and whose wear is reduced.
Grâce à l'invention, la force de freinage appliquée est juste nécessaire pour pousser le véhicule en lui appliquant une faible force si le conducteur souhaite le déplacer pendant une phase de glissement.Thanks to the invention, the braking force applied is just necessary to push the vehicle by applying a small force to it if the driver wishes to move it during a sliding phase.
Il en résulte également une économie d' énergie, l' effort de freinage appliqué étant minimal.This also results in energy saving, the braking force applied being minimal.
Le système de commande et le procédé de commande de l'invention permettent ainsi de s' affranchir de la variation de la masse instantanée du véhicule comme des erreurs de mesure de la pente de la chaussée ainsi que d' éventuelles variations d' efficacité du dispositif de freinage pilotable, afin de maintenir un véhicule en pente avec une force de freinage minimale ou d' obtenir un déplacement souhaité par une diminution juste suffisante de la force de freinage appliquée. The control system and the control method of the invention thus make it possible to overcome the variation in the instantaneous mass of the vehicle as errors in measuring the slope of the roadway as well as possible variations in the efficiency of the device. controllable braking system, in order to keep a vehicle on a slope with a minimum braking force or to obtain a desired displacement by a just sufficient reduction in the applied braking force.

Claims

REVENDICATIONS
1-Système de commande de la force de freinage appliquée à au moins une roue d'un véhicule automobile par un dispositif de freinage pilotable, comprenant différents capteurs (5) de paramètres du véhicule ainsi que des moyens pour détecter une action du conducteur en vue du déplacement ou de l' arrêt du véhicule et un calculateur (9) recevant les informations des capteurs et moyens précités et capable de calculer une valeur de consigne de freinage pour le dispositif de freinage, caractérisé par le fait que le calculateur (9) est adapté pour recevoir des signaux provenant de capteurs de la masse du véhicule ainsi que de la pente de la chaussée sur laquelle se trouve le véhicule afin de déterminer la valeur de consigne de freinage (Ct) et qu' un dispositif (10) de correction de la valeur de consigne de freinage est en outre prévu. 2-Système selon la revendication 1, caractérisé par le fait que le dispositif de correction est capable de calculer un facteur de correction (C) variable en fonction du temps et selon la nature de l' action exercée par le conducteur.1-System for controlling the braking force applied to at least one wheel of a motor vehicle by a controllable braking device, comprising various sensors (5) of vehicle parameters as well as means for detecting an action of the driver in view movement or stopping of the vehicle and a computer (9) receiving the information from the aforementioned sensors and means and capable of calculating a braking setpoint for the braking device, characterized in that the computer (9) is adapted to receive signals from sensors of the vehicle mass and of the slope of the roadway on which the vehicle is located in order to determine the braking setpoint (C t ) and that a correction device (10) the braking setpoint is also provided. 2-System according to claim 1, characterized in that the correction device is capable of calculating a correction factor (C) variable as a function of time and according to the nature of the action exerted by the driver.
3-Système selon la revendication 2, caractérisé par le fait que le facteur de correction tient compte du déplacement du véhicule.3-System according to claim 2, characterized in that the correction factor takes into account the movement of the vehicle.
4-Système selon l'une des revendications 2 ou 3, caractérisé par le fait que le facteur de correction est de la forme C=l±Kt où K est une constante et t le temps écoulé depuis l' action du conducteur.4-System according to one of claims 2 or 3, characterized in that the correction factor is of the form C = l ± Kt where K is a constant and t the time elapsed since the action of the driver.
5-Système selon l'une quelconque des revendications 2 à 4, caractérisé par le fait que le dispositif de correction tient compte de la force longitudinale théorique exercée sur le véhicule en raison de la pente et de la valeur de consigne de la force de freinage théorique.5-System according to any one of claims 2 to 4, characterized in that the correction device takes into account the theoretical longitudinal force exerted on the vehicle due to the slope and the set value of the braking force theoretical.
6-Procédé de commande de la force de freinage appliquée à au moins une roue d'un véhicule automobile, dans lequel le freinage est piloté par détection de différents paramètres du véhicule ainsi que des actions du conducteur en vue du déplacement ou de l' arrêt du véhicule et calcul d' une valeur de consigne de freinage, caractérisé par le fait que l' on prend en compte la masse du véhicule ainsi que la pente de la chaussée sur laquelle se trouve le véhicule afin de déterminer la valeur de consigne de freinage, puis que l'on applique une correction à la valeur de consigne de freinage ainsi déterminée.6-Method for controlling the braking force applied to at least one wheel of a motor vehicle, in which the braking is controlled by detection of various parameters of the vehicle as well as actions of the driver with a view to moving or stopping the vehicle and calculation of a braking setpoint, characterized in that the mass of the vehicle as well as the slope of the roadway on which the vehicle is located in order to determine the braking setpoint value, then applying a correction to the braking setpoint value thus determined.
7-Procédé de commande selon la revendication 6, caractérisé par le fait que la correction appliquée est fonction du temps et de la nature de l' action exercée par le conducteur.7-A control method according to claim 6, characterized in that the correction applied is a function of time and the nature of the action exerted by the driver.
8-Procédé de commande selon la revendication 7, caractérisé par le fait que la correction appliquée tient compte du déplacement du véhicule.8-A control method according to claim 7, characterized in that the correction applied takes into account the movement of the vehicle.
9-Procédé de commande selon l'une des revendications 7 ou 8, caractérisé par le fait que la correction appliquée est de la forme9-control method according to one of claims 7 or 8, characterized in that the correction applied is of the form
C=l ±Kt où K est une constante et t le temps écoulé depuis l' action du conducteur.C = l ± Kt where K is a constant and t the time elapsed since the action of the conductor.
10-Procédé de commande selon l'une quelconque des revendications 7 à 9, caractérisé par le fait que la correction appliquée tient compte de la force longitudinale théorique exercée sur le véhicule en raison de la pente et de la valeur de consigne de la force de freinage théorique. 10-control method according to any one of claims 7 to 9, characterized in that the correction applied takes into account the theoretical longitudinal force exerted on the vehicle due to the slope and the setpoint of the force of theoretical braking.
PCT/FR2003/002946 2002-10-10 2003-10-07 System and method for controlling braking force for a motor vehicle WO2004033266A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2004542561A JP2006502041A (en) 2002-10-10 2003-10-07 Braking force control device and control method for automobile
EP03807875A EP1549537A1 (en) 2002-10-10 2003-10-07 System and method for controlling braking force for a motor vehicle

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0212604A FR2845654B1 (en) 2002-10-10 2002-10-10 BRAKE FORCE CONTROL SYSTEM AND METHOD FOR A MOTOR VEHICLE
FR02/12604 2002-10-10

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JP (1) JP2006502041A (en)
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015128147A1 (en) * 2014-02-28 2015-09-03 Siemens Aktiengesellschaft Vehicle, in particular rail vehicle, having a braking capability-calculating facility and method for operating same

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0149137A2 (en) * 1983-12-20 1985-07-24 Robert Bosch Gmbh Brake force-regulating arrangement
DE19637297A1 (en) * 1996-09-13 1998-03-19 Wabco Gmbh Vehicle with braking force control on a downhill gradient

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0149137A2 (en) * 1983-12-20 1985-07-24 Robert Bosch Gmbh Brake force-regulating arrangement
DE19637297A1 (en) * 1996-09-13 1998-03-19 Wabco Gmbh Vehicle with braking force control on a downhill gradient

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015128147A1 (en) * 2014-02-28 2015-09-03 Siemens Aktiengesellschaft Vehicle, in particular rail vehicle, having a braking capability-calculating facility and method for operating same

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EP1549537A1 (en) 2005-07-06
FR2845654B1 (en) 2004-12-24
JP2006502041A (en) 2006-01-19
FR2845654A1 (en) 2004-04-16

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