SSANGYONG KORANDO 2013 Service Manual

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KAMM circle
Before we go into the Kamm circle, you should
know that a tire offers a maximum of 100 %
transmissibility. It is all the same for the tire
whether we require 100 % in the direction of
braking or in the direction of the acting lateral
force, e.g. when driving round curves. If we drive
into a curve too fast and the tire requires 100 %
transmissibility as cornering force, the tire cannot
transmit any additional brake force. In spite of the
ABS the car is carried out of the curve. The
relationship between brake force B and cornering
force S is shown very clearly in the Kamm circle. I
f
we put a vehicle wheel in this circle, the
relationship becomes even clearer. In this
relationship: as long as the acting forces and the
resulting force remain within the circle, the vehicle
is stable to drive. If a force exceeds the circle, the
vehicle leaves the road.
Brake force
When depressing the brake pedal the brake force
increases to the maximum, then the brake force
decreases until the wheel locks.
Cornering force
The cornering force is a maximum when the
wheel is turning freely with zero slip. When
braking the cornering force falls to zero if the
wheel locks (slip 100 %).
ABS operating range
The operating range starts just before the
maximum brake force and ends in maximum, for
the unstable range then begins, in which no
further modulation is possible. The ABS controls
the regulation of the brake pressure so that the
brake force only becomes great enough for a
sufficient proportion of cornering force to remain.
With ABS we remain in the Kamm circle as long
as the car is driving sensibly. We will leave driving
physics with these statements and turn to the
braking systems with and without ABS. -
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- Brake and cornering force

3) Basic ABS Control
Operation of ABS control unit
Applications of the ABS control unit The signals
produced by the wheel sensors are evaluated in
the electronic control unit. From the information
received, the control unit must first compute the
following variables:
Wheel speed
Reference speed
Deceleration
Slip -
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-
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Reference speed
The reference speed is the mean, I.e. average speed of all wheel speeds determined by simple
approximation.
Simplified ABS control
If, during braking, one wheel speed deviates from the reference speed, the ABS control unit attempts to
correct that wheel speed by modulating the brake pressure until it again matches the reference speed.
When all four wheels tend to lock, all four wheels speeds suddenly deviate from the previously
determined reference speed. In that case, the control cycle is initiated again in order to again correct the
wheel speed by modulating the brake pressure.

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4) ABS Control Pattern
The ABS control is performed by comparing the reference speed with each wheel speed. Firstly, it is
determined whether the vehicle is in the deceleration or acceleration state using the wheel speed
change ratio. Then, a signal is transmitted to the valve.
Finally, the brake pressure is adjusted via the signal.

5) EBD (Electronic Brake Force Distribution) System
System description
As an add-on logic to the ABS base algorithm, EBD works in a range in which the intervention
thresholds for ABS control are not reached yet.
EBD ensures that the rear wheels are sensitively monitored for slip with respect to the front axle. If slip is
detected, the inlet valves for the rear wheels are switched to pressure hold to prevent a further increase
in pressure at the rear-wheel breaks, thus electronically reproducing
a pressure-reduction function at the rear-wheel brakes.
ABS features an enhanced algorithm which includes control of the brake force distribution between the
front and rear axles. This is called Electronic Brake Distribution. In an unloading car condition the brake
efficiency is comparable to the conventional system but for a fully loaded vehicle the efficiency of the
EBD system is higher due to the better use of rear axle braking capability.
Advantages
Elimination of conventional proportioning valve
EBD utilizes the existing rear axle wheel speed
sensor to monitor rear wheel slip.
Based on many variables in algorithm a
pressure hold, increase and/or decrease
pulsetrain may be triggered at the rear wheels
insuring vehicle stability.
Vehicle approaches the ideal brake force
distribution (front to rear).
Constant brake force distribution during vehicle
lifetime.
EBD function is monitored via ABS safety logic
(conventional proportioning valves are not
monitorable). -
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-
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6. HYDRAULIC CIRCUIT OF ABS
1) Normal Brake Operation (ABS is not working) Mode
If the driver depress the brake pedal so that the ABS does not operate, the hydraulic pressure in the
master cylinder increases through the vacuum booster and it is delivered to the wheel via the normal
open inlet valve. At this moment, the normally-closed outlet valve is closed The speed of the wheel that
hydraulic pressure is delivered reduces gradually.
Solenoid valve Valve Open/Close Pump motor
Inlet valve - Normal open (NO) valve Open
OFF
Outlet valve - Normal close (NC) valve Close

2) DUMP (ABS is working) Mode
Even when the hydraulic pressure on each circuit is constant, the wheel can be locked as the wheel
speed decreases. This is when the ABS HECU detects the wheel speed and the vehicle speed and
gives the optimized braking without locking the wheels. In order to prevent the hydraulic pressure from
increasing, the inlet valve will be closed, the outlet valve will be opened and the oil will flow into the low
pressure chamber. In addition, the ABS HECU operates the pump to circulate the oil in the low pressure
chamber to the master cylinder. This may make the driver to feel the brake pedal vibration and some
noises.
Solenoid valve Valve Open/Close Pump motor
Inlet valve - Normal open (NO) valve Close
ON
Outlet valve - Normal close (NC) valve Open

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3) HOLD (ABS is working) Mode
As hydraulic pressure on each wheel increases, the wheel tends to lock. In order to prevent the wheel
from locking, the hydraulic valve modulator operates the inlet valve control solenoid to stop increasing
the hydraulic pressure by closing the inlet valve. At this moment, the outlet valve is closed. This
procedure helps the wheel to maintain a constant hydraulic pressure.
Solenoid valve Valve Open/Close Pump motor
Inlet valve - Normal open (NO) valve Close
OFF
Outlet valve - Normal close (NC) valve Close

4) RISE (ABS is working) Mode
As the wheel speed increases, the inlet valve opens and the wheel's pressure increases due to the
master cylinder pressure. In addition, the pump circulates the oil in the low pressure chamber to the
wheel. As the hydraulic pressure to the wheel increases, the wheel speed will reduce. This operation
continues repetitively until there are no signs that the ABS HECU tends to lock the wheels. Since the
ABS hydraulic pressure control process takes place repeatedly for a short time, there may be some
vibration and noises at the brake pedal.
Solenoid valve Valve Open/Close Pump motor
Inlet valve - Normal open (NO) valve Open
ON
Outlet valve - Normal close (NC) valve Close

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7. CIRCUIT DIAGRAM

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1. SPECIFICATION
1) Specification of Active Wheel Sensor
Description Specification
Supplying voltage DC 12 V
Output current (at 2.75 km/h of vehicle speed) 7 mA (Lo) ~ 14 mA (Hi) +20%/-16%
Tightening torque Front: 7.8 to 11.8 Nm
Rear: 7.8 to 11.8 Nm
Operating temperature
Operating frequency 1 ~ 2,500 Hz
UnitDescription
ABS ESP
HECU Clock frequency: 32 MHz Clock frequency: 50 MHz
Memory: 128 KB Memory: 512 KB
Switch orifice Switch orifice
Wheel speed sensor Active type Active type
Steering wheel angle
sensorNone Max. detection angle speed:
Operating voltage: 9 to 12 V
Sensor cluster None Yaw rate sensor + lateral G sensor +
longitudinal G sensor (4WD)
Longitudinal G sensor 4WD only None
Pressure sensor None HECU integrated