Abd System Description - Daewoo KORANDO Service Manual

General:
The Automatic Brake Differential Lock (ABD) is a traction system by means of brake intervention only, available in
a low speed range (< 60kph).
It workes on m-split roads with sidewise different friction coefficients.
The spinning driven wheel is braked and the drive torque can be transferred to the wheel on the high- m side.
During ABD active, the ABD information lamp is blinking.
The temperature of the brakes is calculated by a mathematical model and ABD is switched passive if the calculated
temperature is greater than a threshold value(500° C).
ABD is permitted again, when the calculated temperature is less than 350° C.
Control Algorithm:
The input signals for the control algorithm are the filtered
wheel speed signals from the ABS speed processing.
With the speed difference of the driven wheels, the control
deviation is calculated.
If the control deviation exceeds a certain threshold value,
the wheel with the greater slip is braked actively.
The threshold value depends on the vehicle speed:
It is reduced with increasing vehicle speed down to a constant
value.
Pressure Modulation:
Depending on the control deviation and the wheel acceleration of the spinning wheel, pressure increase, hold and
decrease are made.
The pressure modulation is done with the conventional control with the valves. ASV, USV, EV and AV according
the the following table:
Increase
ASV Open
USV Closed
EV
Open
AV
Closed
Speed Range:
ABD is available in the speed range
Above 60 kph vehicle speed, ABD is passive.
It is possible to initiate ABD operation up to a vehicle speed of 55kph.

ABD SYSTEM DESCRIPTION

Hold
Open
Closed
Closed
Closed
£ 60 kph.
ANTILOCK BRAKE SYSTEM 4F-5
Speed difference driven wheels [kph]
18
6
Decrease
Open
Closed
Closed
Open
ABD operation
12
Vehicle
speed
60
[kph]