ANTILOCK BRAKE SYSTEM
04–13–8
EBD CONTROL OUTLINE
CHU041343750S07
• EBD control uses the ABS system to control brake fluid pressure distribution to the rear wheels so that they do
not lock-up prior to the front wheels during braking, thereby preventing the loss of handling stability.
Features
• EBD control has independent control systems for both the front and rear wheels.
• EBD control constantly and properly distributes brake fluid pressure regardless of vehicle weight.
Block Diagram
End Of Sie
EBD CONTROL OPERATION
CHU041343750S08
• EBD control detects the slip ratio between the front and rear wheels from the 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 ABS HU/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 0-4 shown in the table below.
• The ABS 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.
α—δ: Specified value
CPU
HU
ABS WHEEL-SPEED
SENSOR (LF)
CALIPER PISTON (LF)
CALIPER PISTON (LR)
CALIPER PISTON (RF)
CALIPER PISTON (RR)
CM
SOLENOID
VALVE
PUMP
MOTOR
ABS HU/CM
ABS WHEEL-SPEED
SENSOR (RF)
ABS WHEEL-SPEED
SENSOR (LR)
ABS WHEEL-SPEED
SENSOR (RR)
CHU0413S011
Conditi
on
Rear wheel slip ratio
determination
EBD control Solenoid valve Comment
0 No slip No control Pressure increase —
1 α%—β% Control Pressure maintained —
2 β% or more Control
Pressure reduction/
maintained
—
3 After EBD control, slip ratio is γ% Control
Pressure increase/
maintained
—
4 Front wheel slip ratio is δ% or more Control
Pressure reduction/
maintained/ increase
ABS control operates
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