Ask for a paper about 8000 words about "Automotive Electronic Control Technology".

Abstract: Energy and environmental protection are two hot issues related to automobiles in the world today. The development trend of modern automobile is good power, convenient operation, safe driving and comfortable riding, and more importantly, energy saving and environmental protection. The development of automobile manufacturing technology must adapt to this development direction. Automobile electronic control technology is the core of modern automobile new technology, which develops rapidly and presents the trend of computerization, intelligence and diversification. Modern cars are called "four-wheeled computers". As a service provider of automobile aftermarket, automobile maintenance enterprises should actively adapt to the development of automobile technology in order to maintain vigorous vitality in the fierce competition. Keywords: automobile; Electronic control; New technology; Chinese picture classification number of maintenance industry: document identification number: A document number:1672-545x (2007) 02-1. New technology of automobile electronic control Modern automobile is a typical product of mechanical, electrical and hydraulic integration. Among them, electronic control technology has become an important symbol to measure the development level of modern automobiles. The electronic control systems in automobiles mainly include electronic fuel injection system (EFI), electronic ignition device (ESA), exhaust gas recirculation control (EGR), idle speed control (ISC), anti-lock braking control system (ABS), anti-skid control system (ASR), electronically controlled suspension system (ASS), electronically controlled automatic transmission (AT), electronic power steering (EPS) and cruising. Automobile electronic control system is mainly composed of sensors, electronic control center (ECU), drivers and control program software, which can be roughly divided into four parts: engine electronic control system, chassis integrated control system, body electronic security systems and information communication system. (I) New Electronic Control Technology of Engine 1, Electronic Control Gasoline Injection System The electronic control fuel injection device of the engine adjusts the fuel supply in time according to the air flow, intake temperature, engine speed, working temperature and other parameters measured by various sensors to ensure that the engine is always in the best working state and improve the comprehensive performance of the engine. It is divided into three types: single-point injection (SPI), multi-point injection (MPI) and direct injection in cylinder. Direct injection in cylinder is the dominant technology of EFI at present. The fuel injector is installed on the cylinder head and directly injects gasoline into the cylinder for mixed combustion. The realization of direct injection technology greatly reduces the fuel consumption of gasoline engine and has superior power performance; Cooperate with other institutions to realize high air-fuel ratio lean combustion technology. 2. The electronic ignition control system consists of microprocessor, sensor, its interface and actuator. The device calculates, judges and adjusts the ignition time according to the engine parameters measured by the sensor, so that the engine can work under the optimal ignition advance angle (ESA), output the maximum power and torque, and reduce fuel consumption and emissions. At present, there is a distributor-less microcomputer-controlled ignition system (DLI), in which ECU controls the power distribution of each cylinder. The high-voltage electricity generated by the ignition coil is directly sent to the spark plug for ignition without being distributed by the distributor, which can eliminate the spark discharge phenomenon between the distributor head and the electrode on the distributor cover and reduce electromagnetic interference. 3. Poor idle performance of idle speed control system will lead to increased oil consumption and serious pollution discharge. Modern cars are generally equipped with idle speed control system. The main actuator is the idle speed control valve (ISC). The ECU compares the target rotational speed determined according to the input signals of various sensors with the actual rotational speed of the engine, determines the control amount equivalent to the target rotational speed according to the difference obtained from the comparison, and drives the actuator for controlling the air amount to keep the idle speed near the optimal state. Idle speed control valve, the executive mechanism of idle speed control system, has developed rapidly, including stepping motor, rotary solenoid valve, duty cycle and switch control. 4. The electronic control system of exhaust gas recirculation is an effective measure to reduce the emission of nitrogen oxides in exhaust gas. The main executive component is the numerical control EGR valve. ECU calculates the optimal recirculation exhaust volume according to the engine speed, throttle opening, cooling water temperature and other signals, and converts the electrical signal output by ECU into air pressure change through vacuum regulating valve to control the opening of EGR valve. Vacuum regulating valves are generally electromagnetic. The ECU also carries out feedback control by measuring the signal of the recirculation exhaust gas rate through a pressure sensor (usually an independent pressure or differential pressure sensor). Now there is an EGR position sensor with integrated EGR valve, which improves the control accuracy. 5. Turbocharging electronic control system The installation purpose of turbocharging system in the engine is to improve air intake efficiency. The development of electronically controlled supercharging system makes supercharging technology step up to a new level. At present, electronically controlled exhaust gas turbocharging system is widely used. One of the negative effects of supercharging technology is that the tendency of combustion knocking increases. Therefore, the knock sensor is specially used for feedback control (i.e. knock control) of the ignition system. 6. Fault self-diagnosis system The fault self-diagnosis system in ECU of modern automobile engine electronic control system can monitor and diagnose the faults of all parts of the engine control system by itself. When each control system fails, the failure indicator lamp on the instrument panel flashes to give an alarm, and at the same time, the failure information is stored in the memory of the microcomputer in the form of code, which can be displayed by intermittent flashing of the failure indicator lamp during maintenance, or by digital display of the failure code through special testing instruments, and the cause of the failure can be found through the manual. 7. Fault safety system and fault backup control system When the self-diagnosis system detects that the sensor and its circuit are out of order, the fault safety system in ECU is automatically started, and the data set by the program replaces the abnormal signal input by the fault part for direct control. When the microcomputer or the main sensor fails, the ECU immediately switches the main control right from the microcomputer to the fault standby system, and the fault standby system replaces the microcomputer to ensure the car to "go home slowly" for maintenance. 9. Intake vortex electronic control system The electronically controlled intake vortex technology is widely used in some cars (especially those with lean-burn technology). Its structure is to add a vortex control valve near the air inlet, and collect signals such as speed, throttle opening and cooling water temperature through ECU, and then control the rotation angle. The deflection of steering flow produces vortex, and the vortex ratio is adjusted to realize vortex control, which promotes gasoline evaporation and uniform mixing with air and improves combustion efficiency. 10, variable intake control system Variable intake control system improves the power and economy of the engine from the perspective of increasing intake air volume and improving intake efficiency. There are two kinds: the variable flow area control mode changes the intake flow cross section by controlling the rotation angle of the control valve installed in the intake pipeline by ECU to meet the demand for intake air volume under different working conditions; Variable flow length control mode ECU controls the control valve in the intake pipe to adjust the length of the intake pipe. 1 1. Intake air temperature preheating control system The intake air temperature preheating control system promotes gasoline evaporation and improves emission performance by adjusting the intake air temperature at low temperature starting. There are three preheating methods: exhaust pipe preheating, water temperature preheating and PTC preheating. 12, the fuel evaporation electronic control system is widely used in the evaporation electronic control device of activated carbon tank. When parking, use activated carbon canister to absorb gasoline vapor to prevent it from spreading into the atmosphere; After the engine is running, ECU controls the conduction between the activated carbon canister and the intake pipe, and uses the intake vacuum to suck the gasoline vapor adsorbed in the activated carbon canister into the intake pipe, which can effectively prevent the gasoline vapor from escaping and reduce the HC emission pollution. 13, electronic control system of positive crankcase ventilation electronic control system ECU controls the positive crankcase ventilation valve according to the throttle position signal and speed signal. So as to realize the communication between the gas in the crankcase and the air inlet pipe, recycle the gas that seeps into the crankcase through the piston ring gap into the air inlet pipe, and reduce the pollution caused by the direct discharge of this part of gas into the atmosphere. 14, secondary air injection system The secondary air injection is controlled by ECU, which introduces air into the catalytic converter to realize the conversion of nitrogen oxides, CO and HC. At present, it is used in conjunction with catalytic converter. With the deepening of research, many new technologies have emerged. For example, cylinder stop control can stop the fuel supply and ignition control of some cylinders according to different requirements of load, reduce waste and improve engine efficiency; Another example is the electronic control system of the accelerator pedal, which can avoid the error caused by the wear of the mechanical accelerator pedal and increase the control accuracy. (II) Development of Electronic Control Technology for Automobile Chassis and Body As an important part of automobile, the performance of automobile chassis directly affects the comprehensive performance of the whole vehicle. The integrated chassis control system includes electronic automatic transmission (ECAT), anti-lock braking system (ABS), driving acceleration slip adjustment (ASR), electronic steering assist system (EPS), adaptive suspension system (ASS) and cruise control system (CCS). 1, electronic control automatic transmission The electronic control automatic transmission can automatically change the position of the gear lever after calculation and judgment according to the load, speed, vehicle speed, braking working state and various parameters controlled by the driver, and accurately control the speed ratio according to the shift characteristics, thus realizing the optimal control of the transmission shift and obtaining the best gear position and shift time. Using electronic technology, especially microelectronics technology to control the transmission system has become the main method to realize the automatic transmission function of automobiles. 2. Anti-lock braking system and anti-lock braking system with driving acceleration and slip adjustment are the most valuable applications in automobile safety. By sensing the instantaneous motion state of the brake wheel, the locking of the wheel is controlled to prevent the automobile from braking, thus ensuring the directional stability of the automobile when braking, shortening the braking distance and improving the driving safety. Driving acceleration slip adjustment is the function improvement and expansion of automobile anti-lock braking system, and the two systems have many common components. Use the speed sensor on the driving wheel to feel whether the driving wheel slips. When it slips, the control element will slow down the speed by braking or throttle to stop it from slipping. 3. The electronic power steering system consists of torque sensor, electronic control unit, motor, reducer, mechanical steering gear and battery power supply. The motor and electronic control technology are used to control the steering, and the power generated by the motor is used to assist the driver in power steering. The system does not directly consume the power of the engine. The electronic power steering system improves the steering ability and steering response characteristics of the automobile, and increases the maneuverability of the automobile at low speed and the stability when driving. At present, there are many applications of power steering for medium and high-grade vehicles in China. 4. Adaptive suspension system The adaptive suspension system can automatically and timely adjust the damping characteristics of the suspension and the stiffness of the suspension spring according to the instantaneous load of the suspension device, so as to adapt to the instantaneous load and maintain the established height of the suspension, which greatly improves the stability, maneuverability and ride comfort of the vehicle. 5. Constant speed cruise control system Cruise control is a control system, which allows the driver to ensure that the car runs at a fixed preselected speed during long-distance driving without operating the accelerator pedal. The throttle opening will be automatically adjusted according to the driving resistance to adjust the vehicle speed to a constant speed. If the road conditions change, the engine power can be adjusted by adjusting the throttle opening to achieve the corresponding speed. The system can reduce the driver's fatigue during long-distance driving and obtain better fuel economy. (III) Development of Body Electronic Safety Technology Body electronic security systems includes adaptive headlamp system (AFS), night vision system (N VS), airbag (SRS), collision warning and prevention system (CWAS), tire pressure monitoring system (TPWS), automatic seat adjustment system (AA S) and seat belt control system. , improving the comfort and convenience of drivers and passengers. 1, adaptive headlight system The adaptive headlight system can calculate and judge the current driving state of the car according to the dynamic changes of the car body and the action characteristics of the steering mechanism within the headlight illumination range, adjust the headlight low beam, which can automatically turn on and off, prevent glare when passing, and effectively reduce the fatigue of drivers driving on detours at night. Some Japanese luxury cars (such as Toyota) have come standard with AFS system. 2. The night vision system of the car is an all-weather electronic eye. The heat of the object in front is detected by the camera, and then concentrated on detectors with various infrared wavelengths, and then the radiation is converted into electrical signals and digital signals in turn, which are converted into images to be displayed to the driver, so that the visual range of the driver can reach 3 to 5 times of the irradiation distance of the low beam lamp, which greatly improves the safety of the car. 3. Airbags are common passive safety devices. When a vehicle collides, the nitrides in the airbag placed in the center of the steering wheel (some of which are also installed behind the glove compartment) are detonated by the electric control elements with current, and rapidly burn to generate nitrogen, which instantly fills the airbag, forming a cushion between the driver and the steering wheel, and between the front seat occupant and the dashboard, so as to avoid being injured by hard impact. 4. Collision early warning and prevention system This system has many forms. When the distance between two cars is small enough to be safe, some of them will automatically give an alarm. If they continue to drive, they will automatically control the brakes to stop the car at the moment of collision. Some display the distance of obstacles behind the car when reversing, which effectively prevents reversing accidents. 5. Tire pressure monitoring system The tire pressure monitoring system automatically warns the driver by continuously monitoring the tire pressure, temperature and wheel speed, so as to maintain appropriate wheel pressure, reduce tire wear and fuel consumption, and ensure the stability and safety of automobile driving. 6. Automatic seat adjustment system This device senses the posture of the occupant through the sensor and adapts the seat state to meet the comfort requirements of the passengers. It is the product of the combination of human engineering technology and electronic control technology.

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