ELECTRONICALLY CONTROLLED BRAKE SYSTEM SYSTEM DESCRIPTION


  1. FUNCTION DESCRIPTION


    1. Electronically Controlled Brake System


      1. The electronically controlled brake system detects the amount that the brake pedal is depressed based on signals from the brake pedal stroke sensor assembly. The system uses the skid control ECU assembly to adjust the pressure supplied from the hydraulic pressure source for each wheel, generating optimal braking force.

    2. Regenerative Braking Cooperative Control


      1. This control performs cooperative control with regenerative braking that is specific to hybrid vehicles to efficiently charge the HV battery.

    3. VSC+/VSC and Cooperative Control with EPS


      1. Effects cooperative control with the power steering ECU assembly in order to provide steering assist in accordance with the operating conditions of the vehicle.

    4. Anti-lock Brake System (ABS)


      1. The ABS helps prevent the wheels from locking when the brakes are applied firmly or when braking on a slippery surface.

    5. Electronic Brake Force Distribution (EBD)


      1. The EBD utilizes ABS, achieving proper brake force distribution between the front and rear wheels in accordance with the driving conditions. In addition, during braking while cornering, the EBD also controls the brake forces of the right and left wheels, helping maintain vehicle behavior.

    6. Brake Assist (BA)


      1. The primary purpose of brake assist is to provide an auxiliary brake force to assist a driver who cannot generate a large brake force during emergency braking, thus helping ensure the vehicle's braking performance.

    7. Traction Control (TRC)


      1. The TRC helps restrain the slippage of the drive wheels if the driver depresses the accelerator pedal excessively when starting off or while accelerating on a slippery surface.

    8. Vehicle Stability Control (VSC)


      1. The VSC helps restrain sideways slippage of the vehicle during a strong front wheel skid or strong rear wheel skid, which may occur while cornering.

    9. Hill-start Assist Control


      1. When starting uphill, this control maintains the brake hydraulic pressure to the 4 wheels, in order to momentarily prevent the vehicle from descending backward.

    10. Emergency Brake Signal


      1. In the case of emergency braking, emergency stop light control flashes the stop lights to alert the drivers in following vehicles.

  2. FUNCTION OF COMPONENTS

    Component Function
    Skid Control ECU Assembly Monitors the driving conditions of the vehicle in accordance with the signals received from the sensors, and through cooperative control with each ECU, calculates the required amount of braking force, and controls the brake actuator assembly.
    Brake Actuator Assembly Controls the wheel cylinder pressure of each wheel according to a signal from the skid control ECU assembly.
    Brake Actuator Assembly Master Cylinder Pressure Sensor The master cylinder pressure sensor converts the fluid pressure generated by the master cylinder into electrical signals and transmits them to the skid control ECU assembly. Accordingly, the skid control ECU assembly determines the braking force required by the driver.
    Wheel Cylinder Pressure Sensor This sensor detects the fluid pressure that acts on their respective wheel cylinders and transmits the pressure to the skid control ECU assembly to provide feedback. Accordingly, the skid control ECU assembly can monitor the fluid pressure of the wheel cylinders and control the pressure application solenoid valves and the pressure reduction solenoid valves, in order to achieve the optimal wheel cylinder pressures.
    Accumulator Pressure Sensor This sensor constantly monitors the brake fluid pressure in the accumulator and transmits a signal to the skid control ECU assembly. Accordingly, the skid control ECU assembly controls the pump motor.
    Relief Valve This valve returns the brake fluid to the brake master cylinder reservoir assembly to prevent excessive pressure if the pump motor operates continuously due to a malfunction of the accumulator pressure sensor.

    Switching Solenoid Valve

    (Master Cut Solenoid Valve)

    • When the brake pedal is depressed, this valve cuts the hydraulic passage between the brake master cylinder sub-assembly and the wheel cylinder.

    • When the brake pedal is not depressed or a failure occurs in the hydraulic power source portion, the valves open to maintain the hydraulic passage to the front wheel cylinders and ensure braking.

    • When a failure occurs, a greater effort than normal is required to depress the brake pedal.

    Linear Solenoid Valve

    (Pressure Application Solenoid Valve)

    		 This valve is controlled by the skid control ECU assembly, regulating the fluid pressure from the accumulator in order to amplify the fluid pressure to the wheel cylinders.

    Linear Solenoid Valve

    (Pressure Reduction Solenoid Valve)

    		 This valve is controlled by the skid control ECU assembly, regulating the fluid pressure in order to reduce the fluid pressure to the wheel cylinders.
    Pump and Pump Motor Draw up the brake fluid from the brake master cylinder reservoir assembly and provides high hydraulic pressure to the accumulator.
    Accumulator Stores the hydraulic pressure that was generated by the pump. The accumulator is filled with high pressure nitrogen gas.
    ABS Motor Relay (ABS MOTOR NO. 1 Relay and ABS MOTOR NO. 2 Relay) By controlled by the skid control ECU assembly, supply power to the pump motor. Under the normal condition, the ABS MOTOR NO. 1 relay is used. When a malfunction is detected in the ABS MOTOR NO. 1 relay, the ABS MOTOR NO. 2 relay is used instead.
    Brake Master Cylinder Sub-assembly Master Cylinder Generates hydraulic pressure in accordance with the brake pedal depression force.
    Brake Stroke Simulator Cylinder Sub-assembly Provides a pedal stroke during braking in accordance with the driver's pedal effort.
    Brake Master Cylinder Reservoir Assembly Stores brake fluid for master cylinder control and brake actuator control.
    Brake Master Cylinder Reservoir Assembly Brake Fluid Level Warning Switch Detects a low brake fluid level.
    Speed Sensor Detects the wheel speed of each of the 4 wheels.
    Brake Pedal Stroke Sensor Assembly Directly detects the extent of the brake pedal stroke operated by the driver.
    Steering Angle Sensor Detects the direction and angle of the steering wheel.
    Yaw Rate and Acceleration Sensor

    • Detects the vehicle's longitudinal and lateral acceleration.

    • Detects the vehicle's yaw rate.
    Combination Switch Assembly VSC OFF Switch Enables the driver to select normal mode, TRC off mode, or VSC off mode.
    Brake Control Power Supply Assembly

    • An auxiliary power supply to provide stable electrical power to the brake system.

    • When the voltage of the auxiliary battery is low, the brake control power supply assembly supplements the supply of power to the brake system by providing the electric charge that is stored in the unit.
    Parking Brake Switch Assembly Detects the parking brake pedal status.
    Stop Light Switch Assembly Detects the brake pedal depressing signal.
    Front Door Courtesy Light Switch Assembly (for Driver Side) Detects whether the door is open or closed, sends the information to the skid control ECU assembly and activates the electrically controlled brake system when the door is opened while the power switch is off.
    Semiconductor PWR Integration ECU Illuminates or flashes the stop lights in accordance with the signals from the stop light switch assembly and skid control ECU assembly.
    Power Steering ECU Assembly Controls the steering assist torque based on the signals received from the skid control ECU assembly.
    Hybrid Vehicle Control ECU Assembly

    • Actuates regenerative braking upon receiving a signal from the skid control ECU assembly.

    • Sends the actual regenerative braking control value to the skid control ECU assembly.

    • Controls the drive force based on an output control request signal received from the skid control ECU assembly while the VSC or TRC is operating.
    Main Body ECU (Multiplex Network Body ECU) Detects the parking brake signal and outputs it to the skid control ECU assembly via CAN communication.
    Combination Meter Assembly ABS Warning Light Illuminates to alert the driver when the skid control ECU assembly detects a malfunction in the ABS.
    Brake Warning Light / Red (Malfunction)

    • Illuminates to alert the driver that the skid control ECU assembly detects the malfunction in the apportioning of the brake force.

    • Illuminates to inform the driver when the brake fluid is low.
    Brake Warning Light / Yellow (Minor Malfunction) Illuminates to alert the driver that a minor malfunction which does not affect the braking force has occurred in the brake system.
    Slip Indicator Light

    • Blinks to inform the driver when the TRC, VSC or ABS is operational.

    • Illuminates to alert the driver when the skid control ECU assembly detects a malfunction in the TRC or VSC.
    VSC OFF Indicator Light Illuminates to inform the driver when VSC off mode is selected.
    Multi-information Display (TRC OFF Message) Displays the information message when TRC off mode is selected.