Electronic control systems (hereinafter referred to as electronic control systems) are widely used in modern automobile engines. The functions of system include fuel injection control, ignition control, idle control, EGR (exhaust gas recirculation control), valve timing control, variable air control and etc. The normal operation of electronic control system is directly related to normal operation of engine, so fault diagnosis and maintenance of electronic engine control system is an important part of engine maintenance work.
The study and research of function, principle of operation, structure and maintenance method of electronic control system of an automobile engine is of great importance for work in field of automotive industry. Although structure and performance of an automotive engine electronic control system is constantly changing with development of other technologies and changes in people's requirements, as long as you really master functions and basic working principles of an automotive engine electronic control system, you can keep up with various new technologies in automotive engines. Application dynamics in electronic control system must be able to adapt to requirements of vehicle development and truly support electronic control system of an automobile engine.
(1) Development of electronic engine control technology
Starting from 1960s, it has been divided into three stages.
The first stage: from mid-1960s to mid-1970s. Basically, this is a technical transformation of automotive electrical products to improve some characteristics, for example, installing a transistor radio on a car.
The second stage: from late 1970s to mid-1990s. To solve three major problems of automotive safety, environmental pollution and energy saving, an electronically controlled gasoline injection system, an electronically controlled anti-skid brake device, and an electronically controlled ignition system have been developed.
The third stage: after mid-1990s. Electronic technology is spreading from engine to chassis, body and diesel, various electronic control systems are becoming more advanced, and electronics of automobiles have reached a very high level. The electronic control systems currently applied in engine mainly include: EFI electronic fuel injection system, ESA electronic ignition system, ISC idle speed control system, emission control system, intake control system, boost control system, cruise control, warning prompts, self-diagnosis and alarm system, failure protection system, emergency backup system, other control systems, etc.
(2) Benefits of Electronic Engine Management
Ever since Bendix Corporation in United States began research into electronically controlled fuel injection systems in 1953, electronically controlled fuel injection technology has so far been quite advanced. Installing an electronically controlled petrol injection system on a vehicle and distributing spare parts. The widespread use of electronically controlled fuel injection systems in automobiles has led to an overall optimization of automobiles in terms of power, economy, emissions and comfort, and has also significantly promoted use of other electronic control systems in automobiles.
The main advantages of electronically controlled fuel injection system are as follows.
① Providing most suitable engine mixture concentration under various operating conditions, so that engine can maintain best power, economy and emissions performance under various operating conditions.
②It has function of decelerating and cutting off fuel supply, which can not only reduce emissions, but also save fuel.
③When vehicle travels through different areas, engine control unit (ECU) can timely and accurately compensate for changes in air density caused by changes in atmospheric pressure or outside ambient temperature.
④ During acceleration and deceleration transition phase, fuel management system can respond quickly to improve vehicle's acceleration and deceleration performance.
⑤The fuel injection pressure is increased, so atomization effect is better; since each cylinder is equipped with a fuel injector, distribution of fuel to each cylinder is improved; this is useful for improving stability of engine.
⑥In air intake system, since there is no throat part such as a carburetor, air intake resistance is reduced. Combined with reasonable intake pipe design, boost effect of inertia of inhaled air can be fully utilized, intake air volume can be increased, engine output can be improved, and power can be increased.
⑦When engine is started, engine control unit can be used to calculate fuel supply required for starting, and engine can smoothly go through warm-up operation so that engine can be easily started and warmed up. performance can be improved.
⑧After electronic fuel injection system is equipped with an emission control system, emission of three harmful gases HC, Co and No is greatly reduced. The electronically controlled fuel injection engine can adapt well to current use requirements of automobiles, that is, to reduce emissions, reduce fuel consumption, increase power output, and improve driving performance.
As a result, electronically controlled fuel injection engines have become mainstay of modern gasoline engines and have now replaced carbureted engines.