ELECTRONICALLY CONTROLLED BRAKE SYSTEM SYSTEM DESCRIPTION


  1. FUNCTION DESCRIPTION


    1. Electronically Controlled Brake System


      1. Upon receiving signals from the skid control ECU, this system effects hydraulic pressure control at the 4 wheels.

    2. Regenerative Brake Cooperative Control


      1. Controls hydraulic braking in order to recover electrical energy by utilizing the regenerative braking of the hybrid system as much as possible.

    3. Enhanced-VSC (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 control utilizes ABS, realizing proper brake force distribution between the front and rear wheels in accordance with the driving conditions. In addition, during braking while cornering, it 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 draw the vehicle's braking performance.

    7. Traction Control (TR(A)C)


      1. The TR(A)C helps restrain the slippage of the drive wheels if the driver depresses the accelerator pedal excessively when starting off or 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, during 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.

  2. FUNCTION OF COMPONENTS

    Component Function
    Brake Booster with Master Cylinder Assembly Brake Actuator

    • Consists of 4 switching solenoid valves, 2 pressure control solenoid valves, 8 control solenoid valves.

    • Changes the brake fluid path based on the signals from the skid control ECU during the operations of the ABS with EBD, brake assist, TR(A)C, VSC and hill-start assist control in order to control the fluid pressure that is applied to the wheel cylinders.
    Hydraulic Brake Booster

    • Generates hydraulic pressure in accordance with the amount of effort applied to the brake pedal by the driver.

    • When a malfunction occurs in the brake system, the hydraulic brake booster supplies the fluid pressure (which is generated by the brake pedal effort) directly to the wheel cylinders.
    Stroke Simulator Generates a pedal stroke during braking in accordance with the driver's pedal effort.
    Brake Actuator Skid Control ECU

    • Monitors the driving conditions of the vehicle in accordance with the signals received from the sensors and through cooperative control with the power management control ECU and power steering ECU assembly calculates the required amount of braking force, and controls the brake actuator.

    • Judges the vehicle driving condition based on signals from each sensor, and controls ABS with EBD, brake assist, TR(A)C, VSC and hill-start assist control.

    • Operates the brake booster pump assembly to control accumulator pressure based on accumulator pressure sensor signal.
    Skid Control ECU Solenoid Relay Supply or cuts off power to solenoid valves in the brake actuator.
    Motor Relay Normally supplies power to the pump motor using 2 out of 3 relays. Ensures power to the pump motor by using the other relay if the skid control ECU detects a malfunction.
    Relief Valve Returns the brake fluid to the reservoir tank to prevent excessive pressure if the pump operates continuously due to a malfunction of the accumulator pressure sensor.
    Linear Solenoid Valve Controls the wheel cylinder pressure to generate a braking force responsive to the braking force requirement when the brake pedal is depressed normally.
    Switching Solenoid Valve Switches the brake hydraulic path when the brake control system is activated.
    Control Solenoid Valve Controls the wheel cylinder pressure when the ABS with EBD, brake assist, TR(A)C, VSC and hill-start assist control are activated.
    Regulator Pressure Sensor The regulator pressure sensor converts the fluid pressure generated by the hydraulic brake booster into electrical signals and transmits them to the skid control ECU. Accordingly, the skid control ECU determines the braking force required by the driver.
    Wheel Cylinder Pressure Sensor This sensor detects the fluid pressure that acts on the respective wheel cylinders and transmits them to the skid control ECU in the form of feedback. Accordingly, the skid control ECU monitors the fluid pressure of the wheel cylinders and controls the control solenoid valve, in order to achieve the optimal wheel cylinder pressures.
    Accumulator Pressure Sensor The accumulator pressure sensor constantly detects the brake fluid pressure in the accumulator and transmits the signals to the skid control ECU. Accordingly, the skid control ECU controls the pump motor.
    Brake Booster Pump Assembly Consisting of a pump, pump motor and accumulator, the hydraulic power source portion generates and stores the hydraulic pressure, which the skid control ECU uses for controlling braking.
    Speed Sensor Detects the wheel speed of each of 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 steering direction and angle of the steering wheel.
    Airbag Sensor Assembly Yaw Rate and Acceleration Sensor

    • The airbag sensor assembly incorporates the acceleration sensor and yaw rate sensor.

    • The yaw rate sensor detects the vehicle's yaw rate.

    • The acceleration sensor detects the vehicle's longitudinal and lateral acceleration.

    • The airbag sensor assembly sends the detection signals from the yaw rate sensor and acceleration sensor to the skid control ECU via CAN communication.
    Brake Master Cylinder Reservoir Assembly Brake Fluid Level Warning Switch Detects the low brake fluid level.
    Parking Brake Switch Assembly Detects the parking brake operating signal.
    VSC OFF Switch Enables the driver to select normal mode, TR(A)C off mode, or VSC off mode.
    Stop Light Switch Assembly Detects the brake pedal depressing signal.
    Power Steering ECU Assembly Operates cooperatively with the skid control ECU to control the steering assist torque.
    Main Body ECU (Multiplex Network Body ECU) Detects the parking brake signal and outputs it to the skid control ECU via CAN communication.
    Power Management Control ECU

    • Actuates the regenerative braking on receiving signal from the skid control ECU.

    • Sends the actual regenerative brake control value to the skid control ECU.

    • Controls the motive force based on an output control request signal received from the skid control ECU while the VSC or TR(A)C is operating.
    Combination Meter Assembly ABS Warning Light Lights up to alert the driver when the skid control ECU detects the malfunction in the ABS, EBD or brake assist.
    Brake Warning Light / Red (Malfunction)

    • Lights up to alert the driver when the skid control ECU detects the malfunction in the apportioning of the brake.

    • Lights up to inform the driver when the parking brake is on or the brake fluid level is low.
    Brake Warning Light / Yellow (Minor Malfunction) Lights up to alert the driver when a minor malfunction occurs in the brake system, which does not affect the braking force (such as a malfunction in the regenerative braking).
    TR(A)C OFF Indicator Light Illuminates to inform the driver when TR(A)C off mode or VSC off mode is selected.
    VSC OFF Indicator Light Illuminates to inform the driver when VSC off mode is selected.
    Slip Indicator Light

    • Blinks to inform the driver when the TR(A)C, the VSC or the hill-start assist control is operated.

    • Lights up to alert the driver in the event of malfunction of the TR(A)C or VSC.
    Meter Buzzer

    • Emits a warning sound to inform the driver when hill-start assist control operation is started or finished.

    • This buzzer sounds continuously to inform the driver when there is a malfunction in the hydraulic pressure or a failure in the power supply.