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 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 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.
• 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 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)

Applications Claiming Priority (3)

Publications (1)

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Family Applications (1)

Country Status (4)

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Family Cites Families (2)

• 2002
  • 2002-10-10 FR FR0212604A patent/FR2845654B1/fr not_active Expired - Fee Related
• 2003
  • 2003-10-07 EP EP03807875A patent/EP1549537A1/de not_active Withdrawn
  • 2003-10-07 JP JP2004542561A patent/JP2006502041A/ja active Pending
  • 2003-10-07 WO PCT/FR2003/002946 patent/WO2004033266A1/fr active Application Filing

Non-Patent Citations (1)

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