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
  • B60T8/32—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 a speed condition, e.g. acceleration or deceleration
  • B60T8/34—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 a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
  • B60T8/48—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 a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition connecting the brake actuator to an alternative or additional source of fluid pressure, e.g. traction control systems
  • B60T8/4809—Traction control, stability control, using both the wheel brakes and other automatic braking systems
  • B60T8/4827—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems
  • B60T8/4863—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems closed systems
  • B60T8/4872—Traction control, stability control, using both the wheel brakes and other automatic braking systems in hydraulic brake systems closed systems pump-back systems
• • 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
  • B60T8/175—Brake regulation specially adapted to prevent excessive wheel spin during vehicle acceleration, e.g. for traction control
• • 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
  • B60T8/1761—Brake regulation specially adapted to prevent excessive wheel slip during vehicle deceleration, e.g. ABS responsive to wheel or brake dynamics, e.g. wheel slip, wheel acceleration or rate of change of brake fluid pressure
  • B60T8/17616—Microprocessor-based systems
• • 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
  • B60T8/32—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 a speed condition, e.g. acceleration or deceleration
  • B60T8/34—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 a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
  • B60T8/36—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 a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition including a pilot valve responding to an electromagnetic force
• • 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
  • B60T2270/00—Further aspects of brake control systems not otherwise provided for
  • B60T2270/20—ASR control systems
  • B60T2270/204—ASR control systems hydraulic model

Definitions

• the invention relates to a circuit arrangement for a brake system with electronic control, in particular with anti-lock control, traction control or driving stability control, with sensors for determining the wheel turning behavior and with an electronic circuit for evaluating the sensor signals and for generating brake pressure Control signals, which are supplied to electrically actuatable actuators, in particular hydraulic valves, and with which the brake pressure in the wheel brakes is controlled as a function of the wheel turning behavior.
• ABS Anti-lock braking systems
• ASR traction control
• BASR brake intervention
• driving stability control systems are becoming increasingly important.
• the brake pressure in the wheel brakes of the controlled wheels is known to be controlled by means of hydraulic valves which are inserted in the brake pressure lines and electrically controlled, modulated in such a way that there is no excessive wheel slip when braking, starting or accelerating.
• the brake pressure control depends on the turning behavior of the respective wheel.
• the valve actuation times are calculated by evaluating the sensor signals reflecting the wheel turning behavior, possibly including further information. From DE 38 09 100 AI it is also known to take into account a wheel pressure model which approximately reflects the pressure in the wheel brakes and which is formed by measuring and evaluating the variables determining the pressure, in particular the valve actuation times becomes.
• the pressure build-up and reduction characteristics of the wheel brakes or the entire brake system are also included in the pressure model.
• Numerous other influencing variables which determine the pressure in the wheel brake for example valve dead times, hydraulic storage effects, pump speed, mutual hydraulic influence of the wheel brakes connected to the same brake circuit, etc., can also be taken into account when forming the pressure model.
• the invention has for its object to achieve a more precise setting of the regulated pressure in the individual wheel brakes in a simple manner and thereby improve the control.
• the aim is to include the various influencing variables on the regulated pressure in the wheel brakes as far as possible without appreciably increasing the effort or the computing times. Hydraulic compensation processes, which can have a considerable influence on the regulated pressure in the wheel brakes in certain control phases, in particular in the case of traction control and in certain brake circuit divisions, should also be recorded. - 3 -
• circuits are provided which determine the target brake pressure in the wheel brakes of the controlled wheels as a function of the wheel turning behavior, and that in In a second, subordinate control circuit, the setpoint brake pressure is compared with the actual brake pressure or a value approximated to the actual brake pressure, the difference between the setpoint and the actual brake pressure or the value approximated to the actual brake pressure is determined, and the signals for controlling the actuators assigned to the regulated wheels , e.g. of the hydraulic valves are generated as a function of the brake pressure difference.
• the desired improvement in the pressure control in the wheel brakes is achieved in a very simple manner by inserting a subordinate control circuit which constantly includes the actual pressure in the wheel brakes or a value approximating the actual pressure in the control.
• the value approximating the actual pressure in the individual wheel brakes is determined by forming a wheel pressure model. This allows a good approximation to be achieved without measuring the pressure.
• the level of the actual pressure depends, among other things, on the valve actuation times of the respective wheel and also the valve actuation times of the other wheel brakes connected to the same brake circuit.
• Further pressure-determining variables that can additionally be used according to the invention to form the wheel pressure model are the brake pressure build-up and reduction characteristics of the wheel brakes and of the entire brake system, the initial pressure when the control system is started, brake actuation signals, control signals for a hydraulic pump in the auxiliary pressure supply system of the brake system etc.
• FIG. 1 shows a schematic representation of the essential hydraulic and electrical components of a brake system with anti-lock control and traction control, in which the invention is used,
• valve control signals and the pressure profile in the wheel brakes during a traction control process are described in the diagram.
• the braking system has two circuits. On one brake circuit I the two front wheels VL, VR, to the other brake circuit II the two rear wheels HL, HR an ⁇ connected. It is a so-called
• a pedal-operated tandem master cylinder 1 with an upstream vacuum booster 2.
• Each wheel is assigned an inlet valve 3 to 6, which is switched to passage in the rest position, and an outlet valve 7 to 10, which blocks in the rest position.
• a double-circuit hydraulic pump 12, driven by a common electric motor 11, is provided for returning the pressure medium flowing through the outlet valves 7 to 10.
• a separating valve 15 which is open in the rest position and can be switched to locks is inserted into the pressure medium path leading from the master cylinder 1 to the rear wheel brakes. Via a hydraulically actuated 2/2-way valve 16, which interrupts the pressure medium path when pressure is applied and consequently when the brakes are applied, pressure medium is subsequently supplied from master cylinder 1 in ASR operation.
• the rotational behavior of the individual wheels is determined in the brake system according to FIG. 1 with the aid of wheel sensors S1 to S4 and evaluated in the electronics of an electronic controller 17.
• E designates the inputs of controller 17, and
• A designates the outputs of controller 17.
• the outputs A are connected via signal lines, not shown, to the coils of the individual electrically actuable hydraulic valves 3 to 10 and 15 and to a control of the electric pump motor 11, also not shown.
• a pressure relief valve U is provided to limit the pressure in ASR operation to a predetermined maximum value.
• the brake pressure control signals are obtained from the information obtained with the aid of sensors S1 to S4.
• the brake pressure P S is calculated using the logic 19 and a subsequent circuit 20, which should prevail in the wheel brake of the respective wheel after evaluation of the input information.
• the associated inlet / outlet valve pair for example 3.7 or 4.8; 5.9; 6.10 is symbolized with 23 in FIG. 2.
• the actual brake pressure or the value PMOD approximated to the actual pressure is in the embodiment of the invention shown in FIG. 2 by forming a so-called.
• Wheel pressure model RDM derived using the circuit or the program part 24.
• the input control variables for forming the wheel pressure model RDM are primarily the valve control signals VS1 of the pair of intake / exhaust valves assigned to the respective wheel, but also the control signals (VS2) of other wheel valves and the isolating valve 15, via which pressure can also be reduced .
• VS2 control signals
• all the valves connected to a common brake circuit can make a contribution to the wheel pressure model RDM of a specific wheel. This becomes clear in the already mentioned example of a traction control system, in which a mutual hydraulic influence of the brake pressures on the controlled wheels can occur. 3 shows such an example.
• the pressure build-up and release curves of the wheel brakes When creating the wheel pressure model that corresponds to the actual pressure however, in addition to the valve control times, the pressure build-up and release curves of the wheel brakes, the characteristic curves of the entire brake system, the characteristics and switch-on times of the hydraulic pump, the initial pressure when the control is started, the control mode - ABS, TCS or stability control - and other influencing factors to be taken into account.
• the arrows VS1 (valve signal 1), VS2, pump signal HP etc. indicate that information or signals of the most varied types can be used to form the wheel pressure model.
• EVS1 is used to control valve 3 according to FIG. 1, EVS2 to control intake valve 4.
• RADI is the left rear wheel HL
• RAD2 is the right rear wheel HR.
• the inlet valve 3 is actuated for traction control for a certain period of time, and brake pressure is thereby built up in the rear wheel HL.
• the brake pressure is generated by the hydraulic pump 11, 12 which is switched on when the ASR operation is started, the isolating valve 15 interrupting the pressure medium path to the master cylinder 1.
• the pressure at the rear wheel HL is increased by a further pressure build-up pulse or by renewed activation of the inlet valve 3.
• the right rear wheel HR is initially depressurized;
• the inlet valve 4 was switched over.
• a similar drop in brake pressure is repeated in the example shown in FIG. 3 at time tg, again triggered by a valve control signal EVS2 and the resulting increase in brake pressure PRAD2 on the right rear wheel HR.
• valve signals EVS1 and EVS2 can assume three levels.
• a valve switching state or a switching position corresponds to each level.
• the constant maintenance by the simultaneous closing of the inlet and the outlet valve, pressure build-up by the illustrated basic position of the valves Pressure build-up achieved by the illustrated basic position of the valves and pressure reduction by opening the exhaust valve while simultaneously closing the intake valve.
• the desired brake pressure modulation could also be realized.

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Citations (5)

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• 1994
  • 1994-03-23 DE DE19944409909 patent/DE4409909C2/de not_active Expired - Lifetime
• 1995
  • 1995-03-11 WO PCT/EP1995/000909 patent/WO1995025652A1/de active Application Filing

Patent Citations (5)

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