2013 SSANGYONG TURISMO brake sensor

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2. 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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1. ESP (Electronic Stability Program)
As the single-track vehicle model used for the calculations is only valid for a vehicle moving forward,
ESP intervention never takes place during backup.
The ESP system includes the ABS/EBD and ASR systems allowing the system to be able to operate
depending to the vehicle driving conditions.
1) Overview
For example, when the brakes are applied during cornering at the speed of 100 km/h, the ABS will
operate at the same time the ASR or ABD systems operate to reduce the power from the slipping
wheel. And when yaw rate sensor detects the rate exceeding 4 degree/seconds, the ESP system
is activated to apply the brake force to the corresponding wheel to compensate the yaw moment
with the vehicle stability control function. This may cause a problem in vehicle control system due
to multi-operation of systems, thus there is a priority as below:
TCS (ASR or ABD) ＞ ESP ＞ ABS (This is subject to the driving and vehicle conditions.)

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(2) Interior Components
ESP Indicator
Sensor Cluster
ESP OFF Switch
Steering Wheel Angle
SensorWarning buzzer
(ESP, PAS buzzer)
Located in ICM box
ESP warning and indicator lamp
ESP OFF indicator lamp
ABS warning lamp
Parking brake operating indicator (EBD warning lamp:
both parking brake operating indicator and ABS warning
lamp come on at the same time) 1.
2.
3.
4.
ESP buzzer

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3) HBA (Hydraulic Brake Assist System)
(1) Purpose
HBA (Hydraulic Brake Assist) system helps in an emergency braking situation when the driver applies
the brake fast, but not with sufficient pressure, which leads to dangerously long braking distance. ECU
recognizes the attempt at full braking and transmits the signal calling for full brake pressure from the
hydraulic booster. An inexperienced, elderly or physically weak driver may suffer from the accident by
not fully pressing the brake pedal when hard braking is required
under emergency. The HBA System increases the braking force under urgent situations to enhance
the inputted braking force from the driver.
Based on the fact that some drivers depress the brake pedal too soft even under when hard braking is
necessary, the HECU system is a safety supplementary system that builds high braking force during
initial braking according to pressure value of the brake pressure sensor and the pressure changes of
the pressure sensor intervals.
When the system is designed to apply high braking force when brake pedal is depressed softly by an
elderly or physically weak driver, the vehicle will make abrupt stopping under normal braking situation
due to high braking pressure at each wheels.

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(2) Operation
The brake pressure value and the changed value of the pressure sensor are the conditions in which
the HBA System operates. There are 2 pressure sensors under the master cylinder. When the ESP
ECU system determines that emergency braking is present, the pump operates, the brake fluid in the
master cylinder is sent to the pump and the braking pressure is delivered to the wheels via the inlet
valves.
If the drive depress the brake pedal slowly, the pressure change is not high. In this case, only the
conventional brake system with booster is activated.

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4) ARP (Active Roll-Over Protection)
The ARP (Active Roll-over Protection) system is a safety assistant device that minimizes, by controlling
brakes and the engine, the physical tendency of the vehicle rollover during sharp lane changes or U-
turns. For the system, software is added to the existing ESP system and no additional device or switch
is needed. One must note that the ARP system, just as general assistant devices including the ABS, is
only a safety assistant device using the ESP system and its function is useless when the situation
overcomes the physical power. Following picture shows how the ARP compensates the vehicle
position by varying each wheel's braking power to overcome the physical tendency of the vehicle
rollover during sharp turns.
The vehicle driving condition is controlled by the internally programmed logic according to the input
signals from wheel speed sensor, steering angle sensor and lateral sensor.

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4. SCHEMATIC DIAGRAM
When equipped with ABS, the braking force at each wheel will be controlled with 3-channel 4-sensor
method. And when equipped with ESP, 4 wheels will be controlled independently with 4-channel
method. (When controlling ABS system only, it will be operated with 3-channel method.) When
compared to the vehicle equipped with ABS/EBD only, the internal hydraulic circuit has a normally-open
separation valve and a shuttle valve in primary circuit and in secondary circuit. When the vehicle brakes
are not applied during engine running or when applying the non-ABS operating brakes, the normally-
open separation valve and the inlet valve are open, whereas the normally-closed shuttle valve and the
outlet valve are closed. When the ESP system is operating, the normally-open separation valve will be
closed by the solenoid valve operation and the hydraulic circuit will be established by the shuttle valve.
Then, the inlet and outlet valves will be
closed or open depending on the braking pressure increase, decrease or unchanged conditions.
▶The warning lamp comes on and warning beep sounds when the ESP is operating
Driving feeling when the ESP is operating ▶
▶Noise and vibration that driver senses when the ESP is operating
1) Hydraulic Circuit Diagram
When the ESP operates during vehicle movement, the ESP warning lamp on the instrument panel
flickers and beep comes on every 0.1 second. The ESP operation shows that the vehicle stability is
extremely unstable and it is used to warn the driver. The ESP system is just a supplementary system
for the vehicle motion and it cannot control the vehicle when it exceeds the physical limits. Do not
solely rely on the system but be advised to drive the vehicle safely.
When the ESP system activates, the driving feeling can be different depending on vehicle driving
conditions. For example, you will feel differently when the ESP system is activated during when ABS
is operating with the brakes applied and when brakes are not applied on a curve. Thus, the ESP
system would make the driver feel more abruptly when the brakes are applied during the ESP
system activation.
The ESP system may transfer noise and vibration to the driver due to the pressure changes caused
by the motor and valve operations in a very short period of time. Extreme cornering will trigger the
ESP operation and this will make the driver feel noise and vibration due to sudden brake application.
Also, the ESP system controls the engine output. So, the driver may notice the engine output
decrease even when the accelerator pedal is being applied.

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(2) Hydraulic Circuit of HBA
The above figure shows one front and one rear wheel and the same hydraulic circuit forms as in the
ESP operation. When HECU recognizes that it is an emergency and it is required for hard braking,
depending on the pressure value of the brake pressure sensor and pressure changes caused by the
pressure sensor timing, it operates the pump immediately to apply the brake pressure at the wheels.
Then, the pressure in the pump increases until just before the corresponding wheel gets locked. The
motor still keeps rotating and the outlet valve and the separation valve will stay closed. When the wheel
starts to lock, the HBA function cancels and switches to ABS operation.