EBD CONTROL OPERATION

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• Electronic brakeforce distribution (EBD) control detects the slip ratio between the estimated vehicle speed and rear wheels from the antilock brake system (ABS) wheel-speed sensor signals. If the slip ratio of the rear wheels as compared to the front wheels is larger than the fixed limit, the dynamic stability control (DSC)/roll stability control (RSC) hydraulic unit (HU)/control module (CM) reduces brake pressure being distributed to the rear wheels. Due to this, brake pressure distribution is constantly controlled in the proper proportion and in relation to vehicle load, road surface conditions, and vehicle speed.
• Determination of the rear wheel slip ratio, based on a comparison of the lowest front wheel speed and the estimated vehicle speed with the rear wheel speeds, is divided into conditions 0-3 shown in the table below.
• The DSC/RSC HU outlet and inlet solenoid valves are operated and the brake fluid pressure controlled according to these conditions.
• If ABS control conditions are met during EBD control, EBD control is stopped and ABS control is given priority.

Condition | Rear wheel slip ratio determination | EBD control | Solenoid valve | Comment
--- | --- | --- | --- | ---
0 | No slip | No control | Pressure increase | —
1 | α%—β% | Control | Pressure maintained | —
2 | After EBD control, slip ratio is Γ% | Control | Pressure increase/maintained | —
3 | wheel slip ratio is Δ% or more | Control | Pressure reduction/maintained/ increase | ABS control operates

α—Δ :Specified value

Operating Condition Transition Diagram

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