Module 4 EPB PHANH TAY ĐIỆN TỬ ) (BẢN TIẾNG ANH)

EPB là viết tắt của hệ thống Phanh đỗ xe điện tử. Nhận tín hiệu đầu vào (hoặc tại thời điểm IG OFF tự động kéo) từ trình điều khiển, môđun điều khiển EPB sẽ kích hoạt động cơ cấu phanh đỗ ở phía sau cả hai trống phanh được nối bằng điện. Giao diện với môđun điều khiển ESC qua CAN, EPB điều khiển không chỉ phanh đỗ mà còn ph anh chân thủy lực để thực hiện các chức năng và tính năng an toàn khác nhau như AVH, DAR và DBF (nó sẽ được giải thích chi tiết hơn trong phần Chức năng chính )

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Brake)

LESSON

4.1 Overview 99

4.1.1 Introduction 99

4.1.2 Comparison of EPB Type 100

4.2 Layout 101

4.2.1 Caliper Type 101

4.2.2 Cable Type 103

4.3 Components 105

4.3.1 EPB Switch 105

4.3.2 AVH Switch 107

4.3.3 Clutch Sensor (M/T Vehicle) 108

4.3.4 Neutral Switch (M/T Vehicle) 109

4.3.5 EPB ECU (Caliper Type) 110

4.3.6 EPB Actuator (Caliper Type) 111

4.3.7 EPB Unit (Cable Type) 112

4.3.8 EPB Lamp & AVH Lamp 113

4.3.9 Cluster Message according to EPB, AVH 114

4.4 Function 115

4.4.1 EPB Functions 115

4.4.2 AVH (Automatic Vehicle Hold) 116

4.5 Maintenance 117

4.5.1 Brake Pad Change (Caliper Type) 117

4.5.2 BED-IN (Cable Type) 118

4.5.3 Post-Actuator Assembly Replacement Measures (Cable Type) 119

4.5.4 Troubleshooting when the EPB Cannot Be Released in Normal Procedures 120

[Learning Objectives]

▪ Explain the difference between the two types of EPB

▪ Describe the system layout and list the locations, mechanisms and functions of components

▪ Describe EPB's secondary functions and the purpose of AVH

▪ Take the necessary measures after changing parts

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EPB is an abbreviation of ‘Electronic Parking Brake’ system Receiving the input signal (or at the time of

IG OFF automatically) from driver, the EPB control module will actuate the motor in order that the parkingbrakes in rear both drums are engaged electrically

Interfacing with ESC control module via CAN, EPB controls not only parking brake but also hydraulic footbrake in order to implement various functions and safety features such as AVH, DAR and DBF., etc (it will

be explained more detail in the section of ‘Main function’)

Comparing with the conventional mechanical type parking brake system, EPB has several benefits asfollows

▪ More space and higher degree of design

Due to the eliminated lever or pedal, possible to get more space for the passenger and to design withvarious layout for the interior convenience device and can have more clean image as shown in thepicture

▪ Automatic operation

Without switch input, EPB engages the parking brake automatically as soon as the ignition off Inaddition, it is released automatically upon vehicle starting without switch input

▪ AVH function

Interfacing with ESC, the vehicle will not move backward when starts at the uphill road

▪ Self diagnosis function

Due to the electronic control module and the interface with other control module via CAN, possible tocommunicate with the scanner so that the system fault can be monitored in advance

▪ Lowest braking effort

Using the electrical motor and cable, the minimum braking effort is required The maximum pulling force

by motor is around 120kgf so that it is much more strong than the manual pulling force in the mechanicalparking system

▪ Safety concept in emergency situation

In case of mechanical braking system, the parking brake cannot guarantee stable vehicle stop if footbrake is failed However, EPB offers much more stability for vehicle stop by controlling the cableelectronically (like ABS)

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4.1.2 Comparison of EPB Type

EPB System is mainly divided into Caliper Type and Cable Type Caliper Type: Electric motor integratedwith caliper pushes the caliper piston and engages the parking brake; Cable Type: Electric motor mounted

on the EPB actuator pulls on the parking cable and engages the parking brake

Category Cable Type Caliper Type

Actuator

On the rear chassis module sub frame Left & right disc brake

Operation The parking cable is pulled by the electric

motor for operation

The electric motor integrated into thecaliper pushes the caliper piston foroperation

Advantages The system cost is high, noise is low Competitive in cost and installation

convenience

AVH Switch Receives AVH activation signals (intention).

Clutch Sensor (M/T) To perform drive away release function in a MT vehicle, clutch sensor input

is required Clutch sensor is connected to EPB ECU via hard wire

Neutral Switch (M/T) To perform drive away release function in a MT vehicle, neutral sensor input

is required neutral sensor is connected to EPB ECU via hard wire

EPB ECU Receives various data and runs the EPB actuator

EPB Actuator Engages rear wheel brake

ESC Receives elevation data from the acceleration sensor and functions in

conjunction with EPB for automatic AVH

ECM Identifies engine RPM for reduced clamp force on flat and auto-apply when

engine turns off while AVH is on

TCM Supports drive away release and P/N to X based on gear shift data

Cluster Dibased splays the EPB indicator and warning lamp; performs auto-adjust on

traveled distance data

Caliper type engages/releases parking brake by activating the EPB actuator by EPB ECU when signal

is received through the EPB Switch The system is linked with ESC to automatically engage/disengagebrake (AVH) when a vehicle comes to a stop (traffic light) It prevents the vehicle from sliding backwards.EPB also engages in an emergency situation for added safety

AVH Switch Receives AVH activation signals (intention).

Clutch Sensor (M/T) To perform drive away release function in a MT vehicle, clutch sensor input

is required Clutch sensor is connected to EPB ECU via hard wire

Neutral Switch (M/T) To perform drive away release function in a MT vehicle, neutral sensor input

is required neutral sensor is connected to EPB ECU via hard wire

EPB Unit

EPB ECU and EPB actuator are integrated

▪ EPB ECU: Receives various data and runs the EPB actuator

▪ EPB Actuator: Pulls the parking cable to generate brake forceESC Receives elevation data from the acceleration sensor and functions in

conjunction with EPB for automatic AVH

ECM Identifies engine RPM for reduced clamp force on flat and auto-apply when

engine turns off while AVH is on

TCM Supports drive away release and P/N to X based on gear shift data

Cluster Displays the EPB indicator and warning lamp; performs auto-adjust based on

traveled distance data

1 Pull switch within 3 seconds: Engages EPB with normal braking force

2 Pull switch for more than 3 seconds: Engages EPB with maximum braking force

3 Press switch once: Releases EPB

NOTE In some 2012 and earlier models, EPB is engaged when the switch is pressed (likethe foot pedal), and EPB is released when the switch is pulled.

▪ EPB Switch Circuit

EPB switch is composed of 4 pins In ignition on, each switch pin receives voltage from EPB ECU at aninterval of 10ms pulse in every 40ms The reason of using this kind of switch is to preventing suddenoperation And when the driver operate the switch, the switch circuit is changed And then the diodedirection is changed

▪ EPB Switch Output

As shown in the above diagram, the switch output voltage is dependent on diode direction, which isset by the EPB switch state Specifically, EPB ECU sends currents to the switch and switch output isreceived for state recognition

▪ Press switch once: AVH on

▪ Press switch once: AVH off

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4.3.3 Clutch Sensor (M/T Vehicle)

The clutch sensor is applied on models with manual transmission and detects when the clutch pedal isactuated The signal is used for:

▪ Engine start (on models with smart key system)

▪ To switch off the cruise control system

▪ Reduce injection volume briefly for preventing engine jerk during shifting

▪ For the drive away release function

The clutch sensor contains two potentiometers Both potentiometers receive power and ground from theelectronic parking brake control unit When the clutch pedal is pressed, the lever mechanism is pusheddownward and rotates on the axis connected to the potentiometer The corresponding signal is fed back

to the EPB control unit

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4.3.4 Neutral Switch (M/T Vehicle)

The neutral switch identifies the current gear position For the drive away release function, the neutralswitch is mounted on the transmission The neutral switch has two pins Pin number 1 is ground and 2 isvoltage in from ECM In gear engagement switch open

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4.3.5 EPB ECU (Caliper Type)

EPB ECU activates the EPB actuator after receiving signal from the EPB Switch, then enters various dataand engages additional functions, and controls the indication/warning lamp

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4.3.6 EPB Actuator (Caliper Type)

EPB actuator signifies the DC motor and the gear box installed in rear wheel caliper The EPB caliper ismade up of a hydraulic device and motor The hydraulic device is used for normal braking, while the motor

is used for parking

First, DC motor can be rotated by DC power from EPB ECU And then gears, spindle are rotated And nutspindle goes ahead with piston As a result brake pad can compress disc brake

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4.3.7 EPB Unit (Cable Type)

Figure 4-2 Rear Suspension Frame

EPB Unit signifies the entire module integrated with EPB ECU and EPB actuator so that it must be replacedwith assembly

EPB ECU activates the EPB actuator after receiving signal from the EPB Switch, then enters various dataand engages additional functions, and controls the indication/warning lamp

The EPB actuator is made up of a weight sensor, parking cable, DC motor and gearbox (deceleration gear).The force sensor that using piezo effect is built in the assembly to measure the tension force directly acting

on the cable In order to minimize the operating noise, the plastic helical gear has been applied in the gearbox No position sensor is applied in the motor

When DC motor activates by EPB signal, the gear rotates and spins the bolt screw This spins theconnected nut screw, and activates the parking brake in DIH

Due to the independent battery power supply to EPB control module, it is possible to engage in IG offcondition

Figure 4-3 Actuator Structure

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4.3.8 EPB Lamp & AVH Lamp

ESC ECU engages Indicator Lamp/Warning Lamp control to check operation status of EPB systems andalerts the driver in case of malfunction All the Indicator Lamps/Warning Lamps are turned ON for 3 secondswhen switched to IG ON Mode or when the engine is started This is a self-diagnosis process If all thesystem is normal, the warning lamps turn OFF If any of the lamps remain turned ON, it signifies failure ofthe corresponding system

1) EPB Lamp

Category EPB Switch Inactive EPB Switch Active EPB Failure

EPB Warning Lamp

If EPB Switch is pulled while the vehicle is stopped, the EPB brake is engaged and brake warning lamp isturned ON Then if EPB Switch is pressed, the EPB is released and the brake warning lamp is turned OFF.EPB warning lamp comes ON (green) only while EPB Switch is engaged, and EPB warning lamp changescolor (from green to white) when the switch is released If the brake warning lamp remains ON even afterEPB is completely released, then it is due to EPB system malfunction In such a case, yellow EPB warninglamp is turned ON

2) AVH Lamp

Category AVH Standby AVH Active AVH Failure

AVH Warning Lamp

AVH is the function that holds the vehicle with hydraulic brake after coming to a stop even when the brakepedal is released When the function is in standby mode while driving, the AVH lamp is white When it isactive, it is green, and in case of failure, yellow AVH lamp is turned ON When AVH function is disabled,the AVH warning lamp is turned OFF

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4.3.9 Cluster Message according to EPB, AVH

EPB and AVH system status and data are displayed on the cluster LCD Displayed items are as follows

Category Image Meaning Warning

by pressing the brake pedal forsafety reason

▪ Activation Conditions

• IG ON

• Safety belt fastened

• Door, trunk, and hood areclosed

Warning alertsounds 1 time

▪ Conditions for Lamp ON

• When the AVH has beenactivated for more than 10minutes

• When the AVH is activated onthe gradient of 25% or more

• When the AVH malfunctions

Warning alertsounds 1 time

▪ Conditions for Lamp ON

• After the AVH is released due

to the EPB failure while theAVH is activated, the EPB

Warningalert soundscontinuously

Item Function Remarks

Static Apply While stationary, manually control (pull) the EPB

switch to engage the parking brake

Static Release While stationary, manually control (press) the EPB

switch to release the parking brake

Auto Apply Automatically engages parking brake without switch

Rear Wheel Unlocker

In case of vehicles without ESC, or in case of ESCfailure, deceleration is achieved by activating theactuator when EPB switch is pulled

Dynamic Standstill

Detection

If vehicle speed data is not available due to systemfailure, the vehicle stopped state is determined throughacceleration sensor signal and EPB is activated

Roll Away Reclamp If vehicle slide is detected while EPB is engaged, EPB

is activated again for increased brake force

P to X, N to X Shifting the gear from P or N to D or R automatically

releases parking brake force

External Apply ESC command automatically converts AVH to EPB

Auto Adjust Increases EPB engagement time to compensate for

High Temperature

Reclamp

Re-engages EPB after a set time to address reduced

Pad Change Mode Moves the caliper piston backwards to facilitate

HU Function Regular inspection (brake force inspection) performed

④ Vehicle starts tomove

Automatic Vehicle Hold (AVH) is a feature that maintains the vehicle at stopped state even when the driverreleases the brake pedal after coming to a stop when in D/R/N or in Sports Mode Brake is automaticallyreleased when taking off by pressing the accel pedal while in D/R or in Sport Mode

2) Mechanism

With the AVH switch on stand-by, press the brake pedal to keep the vehicle stationary Cut off the brakefluid in which the N/O solenoid valve inside HCU is restored when the brake pedal is released to keep thebrakes applied

1 When the brake pads are worn out, the piston in caliper moved to front brake pad To change worn

brake pads, you should be performed brake pad change mode in GDS

2 In this situation, to arrange new pad’s installation space, this mode should be performed to back

nut spindle

3 And after separating the caliper from the rear wheel, push the piston into caliper.

4 Then you can change brake pads.

5 Repeat apply/release three times after a pad change.

3) Precautions

When changing brake pads in pad change mode, assemble the EPB caliper in the correct location andensure the hand is not between the pad and disk before exiting pad change mode Failing to follow theabove safety precaution may lead to an injury In addition, if the brake pedal is pressed while the brakepad is removed, or Lining Change mode is selected with the diagnostic device (after pad replacement), thespindle may move forward since the caliper piston might be pushed outside or the EPB is engaged

in the damage of the cable inside the actuator.

After the gap adjustment, in order to increase the friction forces in the drum and the lining, the BED-INwork should be performed

2) Procedure

● Entering BED-IN Mode

a After the engine starts while holding down the brake pedal when the vehicle is stopped, operate thebrake pedal twice within 10 seconds; for the second time, keep the pedal pushed down (activate

→ release → maintain activation)

b Within 10 sec with the pedal held down, pull the EPB switch 4 times in a row (activation direction),

and right in succession press 3 times in a row

c Vehicle enters the BED-IN Mode when the above procedure is complete

d To return to Normal Mode from the BED-IN Mode, drive the vehicle at speed over 50km/h or

turn the engine OFF

e To check if the vehicle has entered BED-IN mode, drive at a speed less than 50km/h and activate(pull) the EPB switch BED-IN mode is enabled if the parking brake lamp blinks on the cluster