Ebd Control Outline; Block Diagram; Ebd Control Operation - Mazda RX-8 2004 Service Highlights

EBD CONTROL OUTLINE

• 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

ABS WHEEL-SPEED
SENSOR (LF)
ABS WHEEL-SPEED
SENSOR (RF)
ABS WHEEL-SPEED
SENSOR (LR)
ABS WHEEL-SPEED
SENSOR (RR)
End Of Sie

EBD CONTROL OPERATION

• 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.
Conditi Rear wheel slip ratio
on determination
0 No slip
α%—β%
1
β% or more
2
After EBD control, slip ratio is γ%
3
Front wheel slip ratio is δ% or more
4
α—δ: Specified value
04–13–8
ANTILOCK BRAKE SYSTEM
ABS HU/CM
CM
SOLENOID
VALVE
CPU
EBD control
No control
Control
Control
Control
Control
HU
CALIPER PISTON (LF)
CALIPER PISTON (RF)
CALIPER PISTON (LR)
PUMP
MOTOR
CALIPER PISTON (RR)
Solenoid valve
Pressure increase
Pressure maintained
Pressure reduction/
maintained
Pressure increase/
maintained
Pressure reduction/
maintained/ increase
CHU041343750S07
CHU0413S011
CHU041343750S08
Comment
—
—
—
—
ABS control operates