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 )
Textbook Module4 EPB (Electronic Parking Brake) Module4 EPB (Electronic Parking Brake) 4.1 O nl y LESSON Overview .99 4.1.1 Introduction 99 4.1.2 Comparison of EPB Type 100 4.2 Layout .101 Components .105 EPB Switch 105 AVH Switch 107 Clutch Sensor (M/T Vehicle) 108 Neutral Switch (M/T Vehicle) 109 lU 4.3.1 4.3.2 4.3.3 4.3.4 na 4.3 se 4.2.1 Caliper Type 101 4.2.2 Cable Type 103 4.3.5 EPB ECU (Caliper Type) 110 4.3.6 EPB Actuator (Caliper Type) 111 tio 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 Function 115 uc a 4.4 4.4.1 EPB Functions 115 4.4.2 AVH (Automatic Vehicle Hold) 116 4.5 Maintenance .117 Brake Pad Change (Caliper Type) 117 BED-IN (Cable Type) 118 Post-Actuator Assembly Replacement Measures (Cable Type) 119 Troubleshooting when the EPB Cannot Be Released in Normal Procedures 120 Fo r Ed 4.5.1 4.5.2 4.5.3 4.5.4 [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 Basic Chassis Technology 97 Textbook Fo r Ed uc a tio na lU se O nl y Module4 EPB (Electronic Parking Brake) 98 Basic Chassis Technology Textbook Module4 EPB (Electronic Parking Brake) Overview 4.1.1 Introduction O nl y 4.1 lU se 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 parking brakes in rear both drums are engaged electrically na Interfacing with ESC control module via CAN, EPB controls not only parking brake but also hydraulic foot brake 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’) tio Comparing with the conventional mechanical type parking brake system, EPB has several benefits as follows ▪ More space and higher degree of design uc a Due to the eliminated lever or pedal, possible to get more space for the passenger and to design with various layout for the interior convenience device and can have more clean image as shown in the picture ▪ Automatic operation Ed Without switch input, EPB engages the parking brake automatically as soon as the ignition off In addition, it is released automatically upon vehicle starting without switch input ▪ AVH function Fo r 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 to communicate 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 mechanical parking system ▪ Safety concept in emergency situation In case of mechanical braking system, the parking brake cannot guarantee stable vehicle stop if foot brake is failed However, EPB offers much more stability for vehicle stop by controlling the cable electronically (like ABS) Basic Chassis Technology 99 Module4 EPB (Electronic Parking Brake) 4.1.2 Textbook Comparison of EPB Type EPB System is mainly divided into Caliper Type and Cable Type Caliper Type: Electric motor integrated with 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 Cable Type Caliper Type O nl y Category The system cost is high, noise is low Left & right disc brake The electric motor integrated into the caliper pushes the caliper piston for operation Competitive in cost and installation convenience Fo r Ed uc a tio Advantages The parking cable is pulled by the electric motor for operation na Operation lU On the rear chassis module sub frame se Actuator 100 Basic Chassis Technology Textbook Module4 EPB (Electronic Parking Brake) 4.2 Layout 4.2.1 Caliper Type uc a tio na lU se O nl y 1) Overview Fo r Ed 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/disengage brake (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 Basic Chassis Technology 101 Module4 EPB (Electronic Parking Brake) Textbook lU se O nl y 2) In / Output Elements na Configuration Function EPB switch gets driver’s intention And it is connected to EPB ECU via hard wire AVH Switch Receives AVH activation signals (intention) 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 uc a Clutch Sensor (M/T) tio EPB Switch Neutral Switch (M/T) EPB ECU Ed EPB Actuator Receives various data and runs the EPB actuator Engages rear wheel brake 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 Fo r ESC Cluster 102 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 Dibased splays the EPB indicator and warning lamp; performs auto-adjust on traveled distance data Basic Chassis Technology Textbook 4.2.2 Module4 EPB (Electronic Parking Brake) Cable Type tio na lU se O nl y 1) Overview Fo r Ed uc a 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/disengage brake (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 Basic Chassis Technology 103 Module4 EPB (Electronic Parking Brake) Textbook lU se O nl y 2) In / Output Elements na Configuration Function EPB switch gets driver’s intention And it is connected to EPB ECU via hard wire AVH Switch Receives AVH activation signals (intention) 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 uc a Clutch Sensor (M/T) tio EPB Switch 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 and EPB actuator are integrated Ed EPB Unit ESC ▪ EPB Actuator: Pulls the parking cable to generate brake force Receives elevation data from the acceleration sensor and functions in conjunction with EPB for automatic AVH 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 Fo r ECM Cluster 104 ▪ EPB ECU: Receives various data and runs the EPB actuator Displays the EPB indicator and warning lamp; performs auto-adjust based on traveled distance data Basic Chassis Technology Textbook Module4 EPB (Electronic Parking Brake) Components 4.3.1 EPB Switch lU se O nl y 4.3 Switch operation is as follows na The EPB switch receives the driver's intention to park It is located on the floor console as shown in the picture in the slide Turning on the switch sends signals to EPB ECU EPB Switch is connected via dual circuit for enhanced system reliability EPB actuator activates only when contact signals are received tio Pull switch within seconds: Engages EPB with normal braking force Pull switch for more than seconds: Engages EPB with maximum braking force In some 2012 and earlier models, EPB is engaged when the switch is pressed (like the foot pedal), and EPB is released when the switch is pulled Fo r Ed NOTE uc a Press switch once: Releases EPB Basic Chassis Technology 105 Textbook O nl y Module4 EPB (Electronic Parking Brake) Figure 4-1 EPB Switch Circuit (left) / EPB Switch Otput (right) se ▪ EPB State lU The time is a neutral state that a driver doesn’t operate EPB switch If a driver pulls EPB switch to drive, EPB switch enters apply state Or if the driver pushes EPB switch to stop the vehicle, the state changes to release state ▪ EPB Switch Circuit ▪ EPB Switch Output tio na EPB switch is composed of pins In ignition on, each switch pin receives voltage from EPB ECU at an interval of 10ms pulse in every 40ms The reason of using this kind of switch is to preventing sudden operation And when the driver operate the switch, the switch circuit is changed And then the diode direction is changed Fo r Ed uc a As shown in the above diagram, the switch output voltage is dependent on diode direction, which is set by the EPB switch state Specifically, EPB ECU sends currents to the switch and switch output is received for state recognition 106 Basic Chassis Technology Textbook 4.3.2 Module4 EPB (Electronic Parking Brake) AVH Switch O nl y AVH maintains ESC hydraulic pressure when the vehicle is parked Releasing the brake pedal keeps the vehicle stationary AVH switch is a self-return type switch used to engage and disengage the feature ▪ Press switch once: AVH on Fo r Ed uc a tio na lU se ▪ Press switch once: AVH off Basic Chassis Technology 107 Module4 EPB (Electronic Parking Brake) 4.3.3 Textbook Clutch Sensor (M/T Vehicle) The clutch sensor is applied on models with manual transmission and detects when the clutch pedal is actuated 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 lU se O nl y ▪ For the drive away release function Fo r Ed uc a tio na The clutch sensor contains two potentiometers Both potentiometers receive power and ground from the electronic parking brake control unit When the clutch pedal is pressed, the lever mechanism is pushed downward and rotates on the axis connected to the potentiometer The corresponding signal is fed back to the EPB control unit 108 Basic Chassis Technology Textbook Neutral Switch (M/T Vehicle) O nl y 4.3.4 Module4 EPB (Electronic Parking Brake) Fo r Ed uc a tio na lU se The neutral switch identifies the current gear position For the drive away release function, the neutral switch is mounted on the transmission The neutral switch has two pins Pin number is ground and is voltage in from ECM In gear engagement switch open Basic Chassis Technology 109 Module4 EPB (Electronic Parking Brake) EPB ECU (Caliper Type) O nl y 4.3.5 Textbook Fo r Ed uc a tio na lU se EPB ECU activates the EPB actuator after receiving signal from the EPB Switch, then enters various data and engages additional functions, and controls the indication/warning lamp 110 Basic Chassis Technology Textbook EPB Actuator (Caliper Type) O nl y 4.3.6 Module4 EPB (Electronic Parking Brake) EPB actuator signifies the DC motor and the gear box installed in rear wheel caliper The EPB caliper is made up of a hydraulic device and motor The hydraulic device is used for normal braking, while the motor is used for parking Fo r Ed uc a tio na lU se First, DC motor can be rotated by DC power from EPB ECU And then gears, spindle are rotated And nut spindle goes ahead with piston As a result brake pad can compress disc brake Basic Chassis Technology 111 Module4 EPB (Electronic Parking Brake) EPB Unit (Cable Type) Figure 4-2 Rear Suspension Frame O nl y 4.3.7 Textbook EPB Unit signifies the entire module integrated with EPB ECU and EPB actuator so that it must be replaced with assembly se EPB ECU activates the EPB actuator after receiving signal from the EPB Switch, then enters various data and engages additional functions, and controls the indication/warning lamp na lU 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 gear box No position sensor is applied in the motor tio When DC motor activates by EPB signal, the gear rotates and spins the bolt screw This spins the connected nut screw, and activates the parking brake in DIH Fo r Ed uc a Due to the independent battery power supply to EPB control module, it is possible to engage in IG off condition 112 Figure 4-3 Actuator Structure Basic Chassis Technology Textbook Module4 EPB (Electronic Parking Brake) EPB Lamp & AVH Lamp O nl y 4.3.8 lU se ESC ECU engages Indicator Lamp/Warning Lamp control to check operation status of EPB systems and alerts the driver in case of malfunction All the Indicator Lamps/Warning Lamps are turned ON for seconds when switched to IG ON Mode or when the engine is started This is a self-diagnosis process If all the system is normal, the warning lamps turn OFF If any of the lamps remain turned ON, it signifies failure of the corresponding system 1) EPB Lamp EPB Failure na EPB Switch Active uc a EPB Warning Lamp EPB Switch Inactive tio Category Ed If EPB Switch is pulled while the vehicle is stopped, the EPB brake is engaged and brake warning lamp is turned 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 changes color (from green to white) when the switch is released If the brake warning lamp remains ON even after EPB is completely released, then it is due to EPB system malfunction In such a case, yellow EPB warning lamp is turned ON Fo r 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 brake pedal is released When the function is in standby mode while driving, the AVH lamp is white When it is active, 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 Basic Chassis Technology 113 Module4 EPB (Electronic Parking Brake) 4.3.9 Textbook Cluster Message according to EPB, AVH EPB and AVH system status and data are displayed on the cluster LCD Displayed items are as follows Image Category Warning Sound Meaning If the AVH is turned OFF by using the AVH switch, the message is indicated to inform the driver that the Auto Hold is disengaged only by pressing the brake pedal for safety reason O nl y Press the brake pedal to disengage the Auto Hold None se When the activation condition for DAR (Drive Away Release) for the parking brake force is met EPB Auto Release Not Possible lU ▪ Activation Conditions • IG ON Warning alert sounds time na • Safety belt fastened Fo r uc a Ed Parking brake is automatically engaged tio • Door, trunk, and hood are closed Press the brake pedal to disengage the Auto Hold 114 When the auto-switch conditions from AVH to EPB are met ▪ Conditions for Lamp ON • When the AVH has been activated for more than 10 minutes Warning alert sounds time • When the AVH is activated on the gradient of 25% or more • When the AVH malfunctions When the auto-switch conditions from AVH to EPB arise ▪ Conditions for Lamp ON • After the AVH is released due to the EPB failure while the AVH is activated, the EPB activation linkage is broken so the system alerts the driver to use the brake Warning alert sounds continuously Basic Chassis Technology Textbook Module4 EPB (Electronic Parking Brake) 4.4 Function 4.4.1 EPB Functions EPB System includes various auxiliary functions for enhanced driver convenience, and improved safety during emergency situation by incorporating ESC functions Static Apply Function While stationary, manually control (pull) the EPB switch to engage the parking brake While stationary, manually control (press) the EPB switch to release the parking brake Auto Apply Automatically engages parking brake without switch control Drive Away Release Automatically releases parking brake without switch control lU se Static Release Controls the parking brake force corresponding to the incline of the road Electric Controlled Deceleration Hydraulic brake is applied for the duration of holding down the EPB switch in an emergency situation (linked with ESC) tio In case of vehicles without ESC, or in case of ESC failure, deceleration is achieved by activating the actuator when EPB switch is pulled If vehicle speed data is not available due to system failure, the vehicle stopped state is determined through acceleration sensor signal and EPB is activated uc a Dynamic Standstill Detection na Reduced Clamp Force on Flat Rear Wheel Unlocker Remarks O nl y Item Roll Away Reclamp If vehicle slide is detected while EPB is engaged, EPB is activated again for increased brake force 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 Ed P to X, N to X Releases EPB by system request CALIPER TYPE Auto Adjust Increases EPB engagement time to compensate for worn-out brake pads CALIPER TYPE High Temperature Reclamp Re-engages EPB after a set time to address reduced brake force caused by overheating CALIPER TYPE Pad Change Mode Moves the caliper piston backwards to facilitate changing of rear wheel brake pad CALIPER TYPE Regular inspection (brake force inspection) performed on a roller bench CALIPER TYPE Fo r External Release HU Function Basic Chassis Technology 115 Module4 EPB (Electronic Parking Brake) 4.4.2 Textbook AVH (Automatic Vehicle Hold) ② Vehicle is maintained in stopped position ③ Accel pedal is engage ④ Vehicle starts to move se ① Brake pedal is released after coming to full stop O nl y 1) Overview lU Automatic Vehicle Hold (AVH) is a feature that maintains the vehicle at stopped state even when the driver releases the brake pedal after coming to a stop when in D/R/N or in Sports Mode Brake is automatically released when taking off by pressing the accel pedal while in D/R or in Sport Mode na 2) Mechanism Fo r Ed uc a tio With the AVH switch on stand-by, press the brake pedal to keep the vehicle stationary Cut off the brake fluid in which the N/O solenoid valve inside HCU is restored when the brake pedal is released to keep the brakes applied 116 Basic Chassis Technology Textbook Module4 EPB (Electronic Parking Brake) 4.5 Maintenance 4.5.1 Brake Pad Change (Caliper Type) O nl y 1) Purpose se Brake pad change is required when a worn-out brake pad in a caliper-type EPB requires changing lU Use GDS to create space for a new pad uc a ① Worn-out pad tio na 2) Procedure ② Retracts the nut spindle ③ Replace with a new pad (using GDS) Ed 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 In this situation, to arrange new pad’s installation space, this mode should be performed to back nut spindle Fo r And after separating the caliper from the rear wheel, push the piston into caliper Then you can change brake pads 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 and ensure the hand is not between the pad and disk before exiting pad change mode Failing to follow the above safety precaution may lead to an injury In addition, if the brake pedal is pressed while the brake pad is removed, or Lining Change mode is selected with the diagnostic device (after pad replacement), the spindle may move forward since the caliper piston might be pushed outside or the EPB is engaged Basic Chassis Technology 117 Module4 EPB (Electronic Parking Brake) 4.5.2 Textbook BED-IN (Cable Type) O nl y 1) Purpose se The gap between the brake drum and lining is very important in the cable type EPB System If this gap is excessively wide, then that much more cable needs to be pulled when the EPB is engaged, and may result in the damage of the cable inside the actuator lU After the gap adjustment, in order to increase the friction forces in the drum and the lining, the BED-IN work should be performed 2) Procedure Entering BED-IN Mode na ● tio a After the engine starts while holding down the brake pedal when the vehicle is stopped, operate the brake 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 times in a row (activation direction), and right in succession press times in a row uc a 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 ● Ed 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 BED-IN Procedures Fo r a In BED-IN mode, keep a speed of 30-35km/h and pull the EPB switch and keep it activated until the speed reaches 0km/h b Drive 500m (at lower than 50km/h) without activating the EPB switch or cool down for minute while stationary c Repeat to five times d End BED-IN mode by turning the engine off 118 Basic Chassis Technology Textbook 4.5.3 Module4 EPB (Electronic Parking Brake) Post-Actuator Assembly Replacement Measures (Cable Type) Fo r Ed uc a tio na lU se O nl y A new replacement EPB actuator assembly manufactured by Hyundai Mobis comes with the parking cable maximally released Install the assembly on the member, connect the end of the parking cable to the lining hook on DIH and activate the EPB switch to adjust the cable tension (no other adjustment is required) Basic Chassis Technology 119 Module4 EPB (Electronic Parking Brake) Troubleshooting when the EPB Cannot Be Released in Normal Procedures na lU se O nl y 4.5.4 Textbook In case of battery discharge, jump-charge the battery then release the EPB via EPB Switch tio For the cable-type, if the cable has been chewed, use the switch and diagnostic equipment to release EPB and have the drum-lining clearance inspected and adjusted at a repair shop Towing is required if ECU, motor or cable fault occurs with the parking brake engaged Fo r Ed uc a For the cable-type, having the actuator replaced requires cable removal/replacement after DIH clearance adjustment For the caliper-type, activate and disable the actuator by force using a hex key before repairs 120 Basic Chassis Technology ... na lU se O nl y Module4 EPB (Electronic Parking Brake) 98 Basic Chassis Technology Textbook Module4 EPB (Electronic Parking Brake) Overview 4. 1.1 Introduction O nl y 4. 1 lU se EPB is an abbreviation... switch once: Releases EPB Basic Chassis Technology 105 Textbook O nl y Module4 EPB (Electronic Parking Brake) Figure 4- 1 EPB Switch Circuit (left) / EPB Switch Otput (right) se ▪ EPB State lU The... Technology 109 Module4 EPB (Electronic Parking Brake) EPB ECU (Caliper Type) O nl y 4. 3.5 Textbook Fo r Ed uc a tio na lU se EPB ECU activates the EPB actuator after receiving signal from the EPB Switch,