EBD (Electronic Brake-Force Distribution)
EBD (ELECTRONIC BRAKE-FORCE DISTRIBUTION)DESCRIPTION
The EBD system (Electronic Brake force Distribution) as a sub-system of the ABS system is to control the effective adhesion utilization by the rear wheels.
It further utilizes the efficiency of highly developed ABS equipment by controlling the slip of the rear wheels in the partial braking range.
The brake force is moved even closer to the optimum and controlled electronically, thus dispensing with the need for the proportioning valve.
The proportioning valve, because of a mechanical device, has limitations to achieve an ideal brake force distribution to the rear wheels as well as to carry out the flexible brake force distribution proportioning to the vehicle load or weight increasing. And in the event of malfunctioning, driver cannot notice whether it fails or not.
EBD controlled by the ABS Control Module, calculates the slip ratio of each wheel at all times and controls the brake pressure of the rear wheels not to exceed that of the front wheels.
If the EBD fails, the EBD warning lamp (Parking brake lamp) lights up.
ADVANTAGES
^ Function improvement of the base-brake system.
^ Compensation for the different friction coefficients.
^ Elimination of the proportioning valve.
^ Failure recognition by the warning lamp.
COMPARISON BETWEEN PROPORTIONING VALVE AND EBD:
ESC (ELECTRONIC STABILITY CONTROL) SYSTEM
DESCRIPTION OF ESC
Optimum driving safety now has a name: ESC, the Electronic Stability Control.
ESC recognizes critical driving conditions, such as panic reactions in dangerous situations, and stabilizes the vehicle by wheel-individual braking and engine control intervention with no need for actuating the brake or the gas pedal.
ESC adds a further function known as Active Yaw Control (AYC) to the ABS, TCS, EBD and ESC functions. Whereas the ABS/TCS function controls wheel slip during braking and acceleration and, thus, mainly intervenes in the longitudinal dynamics of the vehicle, active yaw control stabilizes the vehicle about its vertical axis.
This is achieved by wheel individual brake intervention and adaptation of the momentary engine torque with no need for any action to be taken by the driver.
ESC essentially consists of three assemblies: the sensors, the electronic control unit and the actuators.
Of course, the stability control feature works under all driving and operating conditions. Under certain driving conditions, the ABS/TCS function can be activated simultaneously with the ESC function in response to a command by the driver.
In the event of a failure of the stability control function, the basic safety function, ABS, is still maintained.
DESCRIPTION OF ESC CONTROL
ESC system includes ABS/EBD, TCS and AYC function.
ABS/EBD function the ECU changes the active sensor signal (current shift) coming from the four wheel sensors to the square wave. By using the input of above signals, the ECU calculates the vehicle speed and the acceleration & deceleration of the four wheels. And, the ECU judges whether the ABS/EBD should be actuated or not.
TCS function prevents the wheel slip of drive direction by adding the brake pressure and engine torque reduction via CAN communication.TCS function uses the wheel speed sensor signal to determine the wheel slip as far as ABS function.
AYC function prevents unstable maneuver of the vehicle. To determine the vehicle maneuver, AYC function uses the maneuver sensor signals(Yaw Rate Sensor, Lateral Acceleration Sensor, Steering Wheel Angle Sensor). If vehicle maneuver is unstable (Over Steer or Under Steer), AYC function applies the brake pressure on certain wheel, and sends engine torque reduction signal by CAN.
After the key-on, the ECU continually diagnoses the system failure. (self-diagnosis) If the system failure is detected, the ECU informs driver of the system failure through the BRAKE/ABS/ESC warning lamp. (fail-safe warning)
VARIANT CODING
A hardware difference of ECU does not exist according to the specification of the vehicle, but a software changes according to difference of vehicle parameter. The ESC stores variant code (data of engine, displacement volume, T/M) at the ECU memory. Since then an ESC uses the stored data.
PROCEDURE
1. Install a EMS/TCU/ESC normally.
2. Connect the Hi-scan (pro) to the data link connector located underneath the dash panel.
3. Select vehicle name.
4. Select ANTI-LOCK BRAKE SYSTEM.
5. Select the variant coding.
6. Follow the next procedure according to the comment
7. Confirm the condition, and then push the "REST".
8. It the procedure is finished, the below screen is displayed.
9. IGN off.
10. IGN on.
11. The variant coding is completed.
CAUTION: If the warning lamp (ESC, EBD, ABS) is lighted up, follow the "Variant coding" again.
INPUT AND OUTPUT DIAGRAM:
ESC OPERATION MODE
1. STEP 1
The ESC analyzes the intention of the driver.
Position of steering wheel
+Vehicle speed
+Acceleration pedal
ECU decides the intention of the driver.
2. STEP 2
It analyzes the movement of the ESC vehicle.
Vehicle rotation speed
+ Operated power to the side
ECU decides movement of the ESC vehicle.
3. STEP 3
It controls a vehicle posture control through the ESC braking power.
^ The ECU calculates the needed countermeasure.
^ The hydraulic unit controls independently the braking power of each wheel.
^ The ESC adjusts engine output through an engine and communication line to be connected.
ESC OPERATION MODE
ESC Non-operation-Normal braking:
ESC INCREASE MODE:
ESC HOLD MODE ( FR is only controlled.):
ESC DECREASE MODE (FR is only controlled):
ABS WARNING LAMP MODULE
The active ABS warning lamp module indicates the self test and failure status of the ABS The ABS warning lamp shall be on:
^ During the initialization phase after IGN ON. (continuously 3 seconds).
^ In the event of inhibition of ABS functions by failure.
^ During diagnostic mode.
^ When the ECU Connector is separated from ECU.
EBD/PARKING BRAKE WARNING LAMP MODULE
The active EBD warning lamp module indicates the self test and failure status of the EBD. However, in case the Parking Brake Switch is turned on, the EBD warning lamp is always turned on regardless of EBD functions. The EBD warning lamp shall be on:
^ During the initialization phase after IGN ON. (continuously 3 seconds).
^ When the Parking Brake Switch is ON or brake fluid level is low.
^ When the EBD function is out of order.
^ During diagnostic mode.
^ When the ECU Connector is separated from ECU.
ESC WARNING LAMP (ESC SYSTEM)
The ESC warning lamp indicates the self-test and failure status of the ESC.
The ESC warning lamp is turned on under the following conditions:
^ During the initialization phase after IGN ON. (continuously 3 seconds).
^ In the event of inhibition of ESC functions by failure.
^ When driver turn off the ESC function by on/off switch.
^ During diagnostic mode.
ESC FUNCTION LAMP (ESC SYSTEM)
The ESC function lamp indicates the self-test and operating status of the ESC.
The ESC Function lamp operates under the following conditions:
^ During the initialization phase after IGN ON. (continuously 3 seconds).
^ When the ESC control is operating. (Blinking-2Hz)
ESC ON/OFF SWITCH (ESC SYSTEM)
The ESC On/Off Switch shall be used to toggle the ESC function between On/Off states based upon driver input. The On/Off switch shall be a normally open, momentary contact switch. Closed contacts switch the circuit to ignition.
Initial status of the ESC function is on and switch toggle the state.