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
EBD CONTROL
1. EBD operation-Hold mode
The ABS/EBD controller should defect the rear wheels tending to lock, so the inlet valves to the rear brakes are activated to prevent further pressure increase.
2. EBD operation-Dump mode
The deceleration should increase and also the locking tendency, so the ABS outlet valves are activated to reduce the pressure in the rear brakes. This pressure is released (as in an ABS stop) to the low pressure accumulators.
The accumulators are emptied after each braking action during the vehicle acceleration phase. This is achieved by switching the pump on.
This means that the driver of the vehicle is not aware of the pump operation noise.
