2013 SSANGYONG NEW ACTYON SPORTS lock

10-16
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.
If 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. -
-
- Brake and cornering force ▶

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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 -
-
-
-
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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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
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

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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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1. SPECIFICATION
1) Specification of Active Wheel Sensor
Description Specification Remark
Supplying voltage 4.5 ~ 16.0V
Output current (at 2.75 km/h of vehicle
speed)7mA(Lo) ~ 14mA(Hi)
Tightening torqueFront: 7.8 to 11.8 Nm
Rear: 7.8 to 11.8 Nm
Operating temperature-40 ~ 150℃
Operating frequency 1 ~ 2,500Hz
UnitDescription
Specification
ABS ESP
HECU Clock frequency: 32 MHz Clock frequency: 50 MHz
Memory: 128 KB Memory: 256 KB
Wheel speed
sensorActive type Active type Output: 7~14 mA
Steering wheel
angle sensorNone Max. detection angle speed:
1500 °/SecPulse duty:
50±10%
Operating voltage: 9 to 12 V
Sensor cluster None Yaw rate sensor + lateral G
sensor + longitudinal G sensor
(4WD)Mounting
direction should
be kept (CAN
communcation)
Longitudinal G
sensor4WD only None
Pressure sensor None HECU integrated

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3. FUNCTION
1) Term Definition
ABS: Anti-Lock Brake System ▶
When the brake pedal is abruptly depressed, the HECU calculates the slip ratio of each wheel based on
information received from the wheel speed sensors and controls the hydraulic module data quickly and
precisely in order to maintain the friction between the road surface and tire optimal (static friction).
Therefore, by keeping the friction between the road surface and tire optimal, it is possible to obtain
following effects: Enhanced steering stability, improved direction stability, reduced stopping distance and
etc.
EBD: Electronic brake-Force Distribution ▶
This is to detect the tire speed from the wheel speed sensor in order to supply the braking pressure to
the rear tires individually. In other words, the HECU measures the tire deceleration speed continuously
and controls the rear inlet valve on the hydraulic modulator to obtain optimal braking force as much as
possible. Thereby, stopping distance, braking effect and straight stability are improved.
ESP: Electronic Stability Program ▶
This is used to make the vehicle stabilized to recognize the emergency driving conditions, and to control
the brake for each wheels and the engine power when the brake system or acceleration will not work
any more in dangerous circumstances.
TCS: Traction Control System ▶
When the wheel is slipping due to an excessive engine torque while starting off or driving, this controls
the driving force (braking force + engine torque) in order to prevent the wheel from slipping through the
engine or brake control.
AYC: Active Yaw Control ▶
This has been developed to help a driver avoid danger of losing control of the vehicle stability due to
understeer or oversteer during cornering, which is a part of the ESP function.
HBA: Hydraulic Brake Assistant ▶
Developed based on the fact that elderly drivers depress the brake pedal too soft even when hard
braking is necessary, this an assist system to operate the HECU drive motor immediately and apply high
braking force to the wheels when the brake pedal is depressed softly and the vehicle should be braked
in emergency.
ARP: Active Rollover Protection ▶
This is a supplementary device for safety in ESP system and can help minimize the rollover accidents by
detecting a potential rollover situation through the brake and engine control when making sudden lane
change or turning sharply by adding only the software, without any separate device or switch.

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6. SYSTEM DESCRIPTION
1) Block Diagram of ESP HECU