: Bộ điều khiển độ ổn định điện tử (ESC) làm tăng sự an toàn chủ động trong mọi điều kiện lái xe.Đặc biệt khi vào cua, hay nói cách khác, khi các lực li tâm đang hoạt động, ESC sẽ ổn định xe và giữ cho xe an toàn trên làn đường. ESC nhận biết các điều kiện lái xe quan trọng, chẳng hạn như phản ứng hoảng loạn trong các tình huống nguy hiểm, và ổn định xe bằng cách tự phân bổ lực phanh bánh xe và can thiệp vào hệ thống điều khiển động cơ mà không cần phải đạp phanh hoặc bàn đạp ga.ESC phản ứng xử lý nhanh vượt xa khả năng nhận biết nguy hiểm của người lái xe và tự động “điều khiển” chiếc xe trở lại đúng hướng bằng cách sử dụng phanh có chọn lọc. Nói cách khác, ESC đảm bảo rằng chiếc xe hoạt động, vận hành bình thường ngay cả trong những tình huống khắc nghiệt nhất.
Textbook Module3 ESC (Electronic Stability Control) Module3 ESC (Electronic Stability Control) 3.1 O nl y LESSON Overview .71 3.1.1 Introduction 71 3.1.2 History of ESC 72 3.1.3 ESC Logic 73 System Components 77 se Maintenance .91 tio 3.3 Main Components 77 Wheel Speed Sensor 78 Yaw-rate & G-Sensor 79 Steering Angle Sensor 80 ESC OFF Switch 82 Brake Switch 83 ESC HECU 84 Warning Lamp & Indicator Lamp 89 lU 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 3.2.6 3.2.7 3.2.8 na 3.2 uc a 3.3.1 Variant Coding 91 3.3.2 HECU Air Bleeding 92 3.3.3 Steering Angle Sensor Calibration 94 Ed 3.3.4 G-Sensor Calibration 95 [Learning Objective] Fo r ▪ Describe the history of ESC ▪ Describe the system layout and list the locations, mechanisms and functions of components ▪ Describe the valve operation that takes place in the oil pressure circuit during normal operation, ABS operation and ESC operation ▪ Take the necessary measures after changing parts Basic Chassis Technology 69 Textbook Fo r Ed uc a tio na lU se O nl y Module3 ESC (Electronic Stability Control) 70 Basic Chassis Technology Textbook Module3 ESC (Electronic Stability Control) Overview 3.1.1 Introduction lU se O nl y 3.1 uc a tio na The Electronic Stability Control (ESC) increases active safety under all driving conditions Particularly when cornering, or in other words, when lateral forces are at work, ESC stabilizes the vehicle and keeps it safely in lane ESC recognizes critical driving conditions, such as panic reaction in dangerous situations, and stabilizes the vehicle by individual wheel braking and engine control intervention with no need for actuating the brake or the gas pedal ESC reacts in a way which is far beyond the driver’s capabilities, and automatically “steers” the vehicle back in the correct direction by selective application of brakes In other words, ESC ensures that the vehicle behaves in the customary manner - even in the most extreme situations Instead of breaking away or starting to skid, the vehicle complies with the inputs from the steering wheel, and the driver remains in complete control ▪ Europe: ESP (Electronic Stability Program) ▪ North America/global: ESC (Electronic Stability Control) Ed NOTE Fo r ▪ Korea: VDC (Vehicle Dynamic Control) Basic Chassis Technology 71 Module3 ESC (Electronic Stability Control) History of ESC Anti-wheel lock Independent wheel control O nl y 3.1.2 Textbook Wheel/steering wheel control se ABS (Anti-lock Brake System) is designed to generate maximum brake force the driver can't with pedal work A vehicle skidding out of control can't be controlled ABS rapidly repeats the application/release of brakes when tires are skidding to restore a vehicle's pre-skid brake force na lU While ABS only adjusts a vehicle's brake force, TCS (Traction Control System) adjusts brake force as well as the power transmitted to the wheels from the engine TCS is designed for harsh driving conditions, such as snow or mud It applies the brakes only to a spinning wheel or redistributes power to be transmitted to a spinning wheel to other wheels for increased stability When functioning in conjunction with ABS, TCS control is executed through ABS, and when accelerating, TCS control is executed through engine output uc a tio ESC (Electronic Stability Control) detects a vehicle's skidding and controls brake pressure applied to individual wheels and the engine output Without the driver applying the brakes, ESC safely prevents a vehicle from skidding ESC's primary function is prevention of understeering and oversteering ABS, TCS and EBD all fall into the category of ESC Fo r Ed VSM (Vehicle Stability Management) maintains a stable vehicle position by applying ESC and MDPS (Motor Driven Power System) to braking and steering when a vehicle is spinning, understeered or oversteered 72 Basic Chassis Technology Textbook ESC Logic tio na lU se O nl y 3.1.3 Module3 ESC (Electronic Stability Control) 1) Driver Intension & Actual Vehicle Behavior uc a The driver's intention is measured by the steering wheel angle (e.g where does the driver wants to go) and the braking pressure (e.g is the driver applying the brake) To verify whether the vehicle is moving as the driver intends, actual vehicle behavior is measured by vehicle rotation angle (yaw angle) and vehicle speed Ed 2) Comparison between Driver Intension and Actual Vehicle Behavior (ESC control) Fo r As long as the actual vehicle behavior matches the drivers’ intention, the situation is judged as normal operation and ESC will not become active If there is a large difference between actual vehicle behavior and driver’s intention the situation is judged as unstable driving condition Basic Chassis Technology 73 Module3 ESC (Electronic Stability Control) Textbook O nl y 3) Oversteering & Understeering Left Understeer uc a tio na lU ● se With unstable driving conditions, understeering and oversteering can occur Understeering refers to a state in which the vehicle's turn angle is larger than the steering wheel angle, and the vehicle slides out when turning a corner Oversteering refers to a state in which the vehicle's turn angle is smaller than the steering wheel angle when turning a corner a An obstacle appears ahead on the right The driver turns the steering wheel to the left, but understeering occurs and the vehicle keeps moving forward toward the obstacle Ed b ESC HECU detects the understeer through the steering angle sensor and Yaw-rate sensor, and instantly brakes the rear left wheel Fo r c Consequently, the vehicle is guided into the driver's intended direction 74 Basic Chassis Technology Textbook Right Oversteer O nl y ● Module3 ESC (Electronic Stability Control) a After avoiding the obstacle, the driver of the vehicle turned the steering wheel to the right to remain in the left lane But the rear wheel lost grip and the rear of the vehicle started to oversteer towards left se b ESC HECU detects the oversteer through the steering angle sensor and Yaw-rate sensor, and instantly brakes the front left wheel lU c Consequently, the vehicle is guided into a straight line without skidding na TIP Vehicle without ESC Fo r Ed uc a tio If a driver suddenly turns the steering wheel to evade an object that suddenly appeared in front while driving on a highway in a vehicle without ESC, the action causes the vehicle to slide and becomes uncontrollable Basic Chassis Technology 75 Textbook Fo r Ed uc a tio na lU se O nl y Module3 ESC (Electronic Stability Control) 76 Basic Chassis Technology Textbook Module3 ESC (Electronic Stability Control) System Components 3.2.1 Main Components uc a tio na lU se O nl y 3.2 Configuration Wheel Speed Sensor Yaw Rate Sensor Ed Steering Angle Sensor Function Detects the speed of each wheel Measures the rotation angle of the vehicle via vertical axis Detects the driver's directional intention Pressure Sensor Measures brake pressure to identify the driver's braking intention ESC OFF Switch ESCcan be stopped at the driver's will This switch is mounted on the pedal assembly and is used to send the status of the brake pedal to the HECU ESC HECU Receives signal from each sensor and computes the signals and uses the data to engage brake for each wheel Fo r Brake Switch Warning Lamp Basic Chassis Technology ABS / EBD / ESC / DBC Notifies system trouble to the driver 77 Module3 ESC (Electronic Stability Control) 3.2.2 Textbook Wheel Speed Sensor se O nl y 1) Exploded View of Wheel Speed Sensor and Its Role na lU The wheel speed sensor detects the speed of each wheel, then transfers the information to the ESC HECU to calculate the vehicle speed and determine whether the wheel is locked or not It is located in the wheel hub area There are two types of WSS: Passive (Coil Type) and Active (Hall IC Type) Active WSS is not affected by air gaps and detections can be made from a speed of 0km/h; as such, active WSS is in wider use than passive WSS tio 2) Coil Type & Hall IC Type Ed Type Coil Type Hall IC Type uc a Category Hall IC Base Signal Voltage Current Power Supply Not required Required The magnetic flux may be alternated upon the rotating of tone wheel and it energizes the coil The internal resistance of Hall IC may be alternated upon the rotating of tone wheel and it generates the different current Fo r Coil Output Waveform Mechanism 78 Basic Chassis Technology Module3 ESC (Electronic Stability Control) 3.2.5 Textbook ESC OFF Switch O nl y 1) Exploded View of ESC OFF Switch and Its Role The ESC off switch allows the driver to stop ESC When the "off" signal is sent to HECU, the ESC OFF indicator comes on The ESC off switch is used in the following circumstances se ▪ Rocking to free the vehicle in deep snow or loose surface material ▪ Operation of the vehicle on a brake test bench na 2) ESC 2–Step OFF Switch lU ▪ Driving with snow chains ESC Step OFF Fo r ● Ed uc a tio Improving from the conventional ESC on/off switch, late-model vehicles have a 2-step ESC control switch Turning ESC off by one step (semi-ESC) only turns off engine control for sporty acceleration after making a turn and escaping puddles without reduced engine torque from spinning • Switch: Press ESC OFF for less than seconds • Indicator & buzzer: ESC OFF indicator on, no buzzer • Display: "Traction control off" displayed on dashboard • Control: Engine torque control (TCS) OFF, brake control on ● ESC Step OFF • Switch: Press and hold ESC OFF for more than seconds • Indicator & buzzer: ESC OFF indicator on, dashboard buzzer sounded once • Display: "VDC off" displayed on dashboard • Control: Engine torque control (TCS) off, brake control off 82 Basic Chassis Technology Textbook 3.2.6 Module3 ESC (Electronic Stability Control) Brake Switch O nl y 1) Exploded View of Brake Switch and Its Role lU se When the brake pedal is depressed, current is fed via the brake light switch to the control module The Brake Switch Signal is required for monitoring the Pressure Sensor Usually the Pressure Sensor should recognize an increase in pressure when the brake pedal is applied (Brake Switch Status ON) And The brake light switch indicates brake pedal status to the ABS control unit Fo r Ed uc a tio na The stop lamp switch signal is required for the hydraulic brake assist, electronic stability, downhill brake control and hill start assist function Furthermore the brake signal is required for the pump motor test which is performed at speeds above 30km/h every time the ignition is turned on Basic Chassis Technology 83 Module3 ESC (Electronic Stability Control) 3.2.7 Textbook ESC HECU 1) Overview ESC HECU is composed of HCU, which controls the hydraulic pressure, and ECU, which controls the HCU and electrical controls Both components are integrated as a single unit and is mounted in the engine compartment Control mechanism is as follows ▪ ECU identifies the driver's intention (steering wheel position + vehicle speed + accel pedal) O nl y ▪ ECU analyzes the vehicle's movement (vehicle turning speed + side pulling force) ▪ Significant inconsistency between the driver's intention and vehicle movement is recognized as a safety hazard and hydraulic control devices adjust the braking of individual wheels It also controls the engine output via communication line connected to the engine to safely control the vehicle out of a potentially dangerous situation The indicators and warning lamps are also controlled according to vehicle state Ed Configuration uc a tio na lU se 2) Components ECU Receives signals from input elements and produces control signals if a spin, understeer or oversteer is detected HCU Hydraulic regulator Motor Powers the pump with power supplied by ECU Pump Pump is engaged by motor during decompression and returns the oil back to the master cylinder Pressure Sensor Measures brake pressure to identify the driver's braking intention Detects sudden braking from pressure drops Solenoid Valve Receives Open and Close commands from ECU and opens/closes flows for individual wheel pressure control Fo r 84 Function Basic Chassis Technology Textbook Module3 ESC (Electronic Stability Control) ● se O nl y 3) Hydraulic Circuit Configuration lU • Inlet Solenoid Valve (ISV) • Outlet Solenoid Valve (OSV) na This valve connects or disconnects the hydraulic path between master cylinder and the wheel cylinders The valve remains normally open but it is closed when the dump and hold mode begins during ABS operation Purpose of the check valve is to help the brake fluid returning from the wheel cylinder to the master cylinder when the brake pedal is released tio The outlet solenoid valves are normally closed The valve is opened when the dump mode begins to release the wheel cylinder pressure uc a • Electric Shuttle Valve (ESV) The Electric Shuttle Valve is normally closed When ESC is in progress, the valve is opened and brake fluid is supplied to the pump elements • Traction Control Valve (TCV) Fo r Ed The Traction Control Valve is normally open and the brake pressure from the master cylinder is applied to the wheel cylinders While TCS or ESC is in progress, the TCV is closed and the generated pressure is applied to the front wheel cylinders without returning to the master cylinder The TCV includes a relief valve and a check valve When excessive pressure is supplied from the motor, the relief valve is opened and the pressure is relieved • Pressure Sensor (P/U) The Pressure Sensor monitors the pressure of the brake line This sensor signal is the basic data for hydraulic brake assistance control Additionally this sensor input is required when ESC is in progress Basic Chassis Technology 85 Module3 ESC (Electronic Stability Control) Normal Braking O nl y ● Textbook se During normal braking, brake pressure is applied to the wheel cylinder via the open Traction Control Valves (TCV) and Inlet Solenoid Valves (ISV) The Outlet Solenoid Valve remains closed lU This diagram is also showing the fail safe condition of the brake system, as none of the valves is electrically on under this condition na • Solenoid Valve Operation Valve Electrically Condition OFF closed OFF open OFF open OFF open OSV (LR) OFF closed OSV (RF) OFF closed TCV ISV (LR) Fo r Ed uc a ISV (RF) tio ESV 86 Basic Chassis Technology Textbook ABS Braking se O nl y ● Module3 ESC (Electronic Stability Control) • Solenoid Valve Operation Valve tio - Normal braking na lU During ABS operation brake pressure is applied from the master cylinder via the normally open Traction Control Valves (TCV) The Inlet Control Valves and Outlet Control Valves are driven in a pulsed cycle, creating the effect of „applying“ (Hold mode) and „releasing“ (Dump mode) the brake(s) of the appropriate wheel(s) The accumulators inside the Hydraulic Control Unit are damping the pulsation of the pressurized brake fluid when the Outlet Control Valve (OCV) is opened The pump draws the brake fluid out of the accumulators Electrically Condition OFF open ISV OFF open OSV OFF closed ESV OFF closed Valve Electrically Condition TCV OFF open ISV ON closed OSV OFF closed ESV OFF closed Valve Electrically Condition TCV OFF open ISV ON closed OSV ON open ESV OFF closed Ed uc a TCV Fo r - Hold mode - Dump mode Basic Chassis Technology 87 Module3 ESC (Electronic Stability Control) ESC Braking O nl y ● Textbook uc a - Primary circuit tio • Solenoid Valve Operation Valve Electrically Condition TCV ON closed ESV ON open ISV (LR) OFF open ISV (RF) ON closed OSV (LR) OFF closed OSV (RF) OFF closed Valve Electrically Condition TCV ON closed ESV ON open ISV (LR) OFF open ISV (RF) ON closed OSV (LR) OFF closed OSV (RF) OFF closed Ed Fo r na lU se In this position the Inlet Solenoid Valve(s) (ISV) of the appropriate wheel(s) is/are driven in a pulsed cycle The remaining ISV´s are electrically turned on (closed) The Traction Control Valve of the brake circuit is almost closed (PWM control) The Outlet Control Valves (OCV) remains closed The Electrical Shuttle Valve (ESV) is opened to allow the pump to draw brake fluid out of the master cylinder The pressurized fluid passes via the pulsed driven rear left Inlet Solenoid Valve (ISV) to the wheel brake cylinder The Inlet Solenoid valves of the remaining brake cylinders remain closed As you can see on the drawing, also the ESV and TCV of the second brake circuit are in the open position This is done to prevent an excessive pressure built up within the circuit The pump basically pumps the brake fluid through the pipes without creating pressure - Secondary circuit 88 Basic Chassis Technology Textbook Module3 ESC (Electronic Stability Control) 3.2.8 Warning Lamp & Indicator Lamp se O nl y 1) Overview na lU ESC HECU engages Indicator Lamp/Warning Lamp control to check operation status of ABS/EBD/ESC/DBC 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 Configuration tio 2) Indicator/Warning Lamp Function Function ESC indicator blinks when the ESC system is on ESC warning lamp switched on when the ESC system is faulty ESC OFF Warning Lamp The ESC off switch allows the driver to stop ESC When the "off" signal is sent to HECU, the ESC OFF indicator comes on ESC can be disabled for sporty driving and vehicle inspections uc a ESC Warning Lamp As the EBD system uses brake warning lamps, brake force is not distributed to front and rear wheels if the ABS warning lamp and brake warning lamp are on at the same time DBC Indicator Pressing DBC On turns on the indicator to show that DBC is ready for use (stand-by); the indicator blinks when DBC is on The indicator turns red if the DBC system is faulty ABS Warning Lamp The ABS warning lamp staying on while driving indicates an ABS fault However, the brakes continue to function normally Fo r Ed EBD Warning Lamp Basic Chassis Technology 89 Textbook Fo r Ed uc a tio na lU se O nl y Module3 ESC (Electronic Stability Control) 90 Basic Chassis Technology Textbook Maintenance se O nl y 3.3 Module3 ESC (Electronic Stability Control) tio na lU Figure 3-1 ESC S / W Management 3.3.1 uc a Figure 3-2 MDPS S / W Management Variant Coding Ed 1) Purpose Fo r The variant is written into the EEPROM of the ABS/ESCCM According to the vehicle parameter, the ABS / ESC software changes ABS / ESC receives data for variant coding such as engine type, engine displacement and AT type The ABS / ESCCM writes the proper variant code on to the EEPROM based on the received data 2) Advantages ▪ Creating one software for all variants of vehicle ▪ Every variant of a vehicle has its own application Software ▪ Differences may be small but a new application is needed for comfort ▪ Including all variants in one Software can be done by variant coding (max 30 variants per Software) ▪ Variant Coding helps avoiding additional costs Basic Chassis Technology 91 Module3 ESC (Electronic Stability Control) 3.3.2 Textbook HECU Air Bleeding O nl y 1) Purpose lU se HECU air bleeding prevents vapor lock (spongy brakes) Vapor lock can occur when bubbles form in brake fluid from heat or from an oil shortage HECU air bleeding is performed during brake lines maintenance or a part replacement due to brake fluid leakage 2) Procedure Working in a Pair (GDS X) na ● tio a Personnel uses a vacuum pump to drain the clutch fluid from the clutch master cylinder reservoir tank uc a If no vacuum pump is available, Personnel removes the air bleeding screws from the release cylinder and Personnel continuously applies the clutch pedal to discharge all the clutch fluid As the clutch master cylinder has no pressure at this time, the clutch pedal will not return to its original position when pressed down Hold the pedal in the hand and repeat pressing down and pulling up NOTE Ed b Personnel fully fills the master cylinder reservoir tank with clutch fluid c Repeat step and if clutch fluid change is the objective Fo r d Tighten the air bleeding screws in the clutch release cylinder if clean clutch fluid seeps through them e Repeat pressing down and pulling up the clutch pedal until sufficient pressure has formed, and then press down and hold the pedal f At this time, Personnel undoes the air bleeding screws in the clutch release cylinder, checks for air or clutch fluid leakage and immediately tightens them back up g Personnel pulls the clutch pedal up with the hand h Repeat step i Repeat step Stop repeating the steps if air-free clutch fluid comes out j Repeat step and once or twice if normal pressure can be felt when working the clutch pedal k Personnel fully tightens the air bleeding screws in the clutch release cylinder Personnel fills clutch reservoir tank with clutch fluid up to the maximum line l 92 Perform a test run, find a good clutching point and adjust the master cylinder push rod Basic Chassis Technology Textbook ● Module3 ESC (Electronic Stability Control) Using Equipment (GDS) a Prepare the necessary equipment Connect the power cord to a power socket and turn on the switch (electric motor-type) or connect the air hose (air-type) b Open the cap on the clutch master cylinder reservoir tank Install a clutch fluid pressurizing adaptor and connect the pressure hose Set the pressure to 2-3 kg/cm2 Excess pressure will cause the reservoir tank to rupture c Loosen the air bleeding screws in the clutch release cylinder by one turn Plug in the adapt of the equipment and insert the vacuum hose in the adaptor O nl y d Switch on the equipment If clean bubble-free clutch fluid comes out of the transparent vacuum hose line, tighten the air bleeding screws in the clutch release cylinder Fo r Ed uc a tio na lU se e Remove the vacuum hose (inserted in the adaptor) from the release cylinder air bleeding screws Switch off the equipment Wait five minutes and remove the adaptor and clutch fluid pressurizing hose from the master cylinder (not waiting for long enough will cause pressurized clutch fluid to spurt out) Basic Chassis Technology 93 Module3 ESC (Electronic Stability Control) 3.3.3 Textbook Steering Angle Sensor Calibration 1) Purpose When the Steering Wheel Sensor has been replaced, the new one must be calibrated This also applies if repair work has been carried out on the steering, or the Sensor has been removed se O nl y 2) Procedure lU Line up wheels a Form the wheel alignment b Line up the wheel in a straight na c Drive the vehicle ahead and back 2–3 times without holding steering wheel Go in ESC system tio Connect GDS to Data Link Connector (DLC) Perform steering angle sensor calibration uc a Click APS Calibration menu of the scan tool Check the condition of "Steering Angle Sensor Calibration" by operating the vehicle (turn right and left at least time) Ed 3) Effects when sensor is not calibrated Fo r A de-calibrated sensor is recognized immediately after turning the ignition on, the ESC warning lamp lit on (deviation more than 15°) and a fault code is registered in the CU If however a previously calibrated sensor is installed and a calibration is not carried out, the zero output will probably not corrESCond with the straight ahead position As long as the deviation does not exceed the 15° threshold, the system will try to adapt to that condition by using its long-term adjustment 94 Basic Chassis Technology Textbook 3.3.4 Module3 ESC (Electronic Stability Control) G-Sensor Calibration 1) Purpose In order to ensure the correct operation of hill start assist (HAC) and downhill brake control (DBC) the sensor needs to be calibrated after sensor or hydraulic electronic control unit (HECU) replacement or if the DTC C1285 (longitudinal G-sensor offset was not calibrated) is present in the system lU se O nl y 2) Procedure IG ON, ENG OFF na Stand the vehicle on a flat ground without any inclination Set the steering wheel at the center position tio Keep the vehicle under normal tire pressure condition and normal loading condition Connect GDS to Data Link Connector Fo r Ed uc a (DLC) Confirm that no DTC is present in the system Basic Chassis Technology 95 Textbook Fo r Ed uc a tio na lU se O nl y Module3 ESC (Electronic Stability Control) 96 Basic Chassis Technology ... se O nl y Module3 ESC (Electronic Stability Control) 90 Basic Chassis Technology Textbook Maintenance se O nl y 3. 3 Module3 ESC (Electronic Stability Control) tio na lU Figure 3- 1 ESC S / W Management... y Module3 ESC (Electronic Stability Control) 76 Basic Chassis Technology Textbook Module3 ESC (Electronic Stability Control) System Components 3. 2.1 Main Components uc a tio na lU se O nl y 3. 2... lU se O nl y Module3 ESC (Electronic Stability Control) 70 Basic Chassis Technology Textbook Module3 ESC (Electronic Stability Control) Overview 3. 1.1 Introduction lU se O nl y 3. 1 uc a tio na