Application of Electronic Control Technology in Automobile Engines

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Application of Electronic Control Technology in Automobile Engines [Copy link]

1. Introduction
1) Basic principles and structure of automobile engines
The working process of automobile engines in the world today is basically composed of four strokes, namely intake, compression, expansion and exhaust. The engine uses the expansion of high-temperature and high-pressure gas generated by the combustion of the mixture of fuel and air in the cylinder to output torque to the outside through the crankshaft with the help of the crank-connecting rod mechanism to work. According to the fuel used, the engine can be divided into gasoline engine, diesel engine and gas engine; according to the ignition method, it can be divided into spark ignition and compression ignition; according to the ratio of air and fuel, the gasoline engine can be divided into theoretical equivalent combustion and lean combustion; according to the location of gasoline injection, it can be divided into central injection, intake port injection and cylinder injection.
According to their functions, the various parts of the engine can be divided into fuel supply system, intake and exhaust system, ignition system, crank-connecting rod transmission mechanism, lubrication system, cooling system and auxiliary systems such as generator, starter, air conditioning compressor and various pumps.
The engine working conditions can be divided into cold start, after starting, warm-up, idling, partial load, full load, acceleration, deceleration and reverse coasting. These operating conditions are mainly distinguished based on load and speed, combined with engine temperature (i.e. coolant temperature).
2) The importance of electronic control in engines
Automotive electronic control began with engine electronic control. The introduction of electronic control into engines in 1957 and its commercialization in 1967 were originally intended to meet increasingly stringent emission regulations and improve the power, fuel economy and comfort of automobiles. Modern automobile and engine technology is unthinkable without electronic control. The proportion of electronic products in the entire automobile increases with the improvement of automobile grade, reaching more than 30%.
3) The core issues of engine electronic control
The core issues of gasoline engine electronic control are fuel dosing and ignition timing. The core issues of diesel engine electronic control are fuel dosing and injection timing.

2. Composition of automotive and engine electronic control systems
Automotive and engine electronic control systems, like other electronic control systems, are also composed of sensors, electronic control units (ECUs) and actuators.
1) Sensors
(1) The sensors commonly used in gasoline engine electronic control systems are:
l Intake manifold absolute pressure sensor (provides intake manifold absolute pressure information for load calculation, etc.)
l Fuel pressure sensor (provides fuel rail fuel pressure information)
l Fuel tank pressure sensor (provides fuel tank pressure information)
l Oil pressure sensor (provides oil pressure information)
l Coolant temperature sensor (provides engine temperature information)
l Intake air temperature sensor (provides intake air temperature information for air density calculation, etc.)
l Air conditioning evaporator temperature sensor (provides air conditioning evaporator temperature information)
l Air conditioning condenser temperature sensor (provides air conditioning condenser temperature information)
l Air flow sensor (provides air flow information for load calculation, etc.)
l Throttle position sensor (provides load information, load range information, acceleration and deceleration information)
l Accelerator pedal position sensor (provides load information, load range information, acceleration and deceleration information, etc.)
l Hall sensor (provides speed information, crankshaft position and phase information)
l Inductive speed sensor (provides speed information and crankshaft position information)
l Fuel tank level sensor (provides fuel tank level information)
l Knock sensor (provides vibration information received by the engine body)
l Exhaust gas recirculation valve stem displacement sensor (provides exhaust gas recirculation valve opening information)
l Oxygen sensor (provides information on whether the excess air coefficient l is greater than 1 or less than 1)
(2) The sensors commonly used in diesel engine electronic control systems are:
l Boost pressure sensor (provides boost pressure information)
l Fuel pressure sensor (provides common rail fuel pressure information)
l Oil pressure sensor (provides oil pressure information)
l Coolant temperature sensor (provides engine temperature information)
l Fuel temperature sensor (provides fuel temperature information)
l Intake air temperature sensor (provides intake air temperature information)
l Exhaust temperature sensor (provides exhaust port and exhaust pipe temperature information)
l Air conditioning evaporator temperature sensor (provides air conditioning evaporator temperature information)
l Air conditioning condenser temperature sensor (provides air conditioning condenser temperature information)
l Air flow sensor (provides air flow information)
l Throttle position sensor (provides throttle position information for exhaust gas recirculation control)
l Angle sensor (provides distribution pump shaft angle information)
l Accelerator pedal position sensor (provides load information, load range information, acceleration and deceleration information)
l Hall sensor (provides speed and crankshaft phase information)
l Altitude sensor (provides altitude information)
l Vehicle speed sensor (provides vehicle speed information)
l Inductive speed sensor (provides speed information and crankshaft position information)
l Fuel tank level position sensor (provides fuel tank level position information)
l Exhaust gas recirculation valve stem displacement sensor (provides exhaust gas recirculation valve opening information)
l Oxygen sensor (provides specific value of excess air coefficient l)
l Pressure difference sensor (provides pressure difference information of particulate matter trap)
l NOX sensor (provides NOX concentration information of exhaust aftertreatment system)
2) Electronic control unit
The electronic control unit (ECU) receives various information provided by the sensor and processes it, and sends instructions to the actuator based on the processing to control the engine. The electronic control unit consists of a microcomputer and an analog circuit. With the continuous development of engine technology, the amount of information processed by the electronic control unit is increasing. The chips used now have reached 32 bits, the number of transistors can exceed 7 million, the matching parameters can exceed 6,000, and the number of pins can exceed 150.
3) Actuator
(1) The commonly used actuators in the electronic control system of gasoline engines are:
l Electric fuel pump
l Solenoid injector
l Ignition coil
l Various idle actuators
l Carbon canister control valve
l Exhaust gas recirculation control valve
l Electric throttle (also known as electronic throttle)
l Hydraulic circuit solenoid valve (for variable valve timing control, etc.)
l Pneumatic circuit solenoid valve (for variable intake pipe length control, etc.)
l Fully variable valve electronic control actuator
l Turbocharger exhaust gas release control valve
l Electric secondary air pump
l Three-way catalytic converter heating actuator
l Cooling fan
l Air conditioning compressor electromagnetic clutch
l Other auxiliary equipment on the engine
(2) The actuators commonly used in diesel engine electronic control systems are:
l Electric fuel delivery pump
l Various fuel injection pumps
l Fuel injection quantity actuator (integrated in the fuel injection pump)
l Fuel injection advance angle actuator (integrated in the fuel injection pump)
l Fuel cut-off valve (integrated in the fuel injection pump)
l Common rail high-pressure pump
l Common rail pressure control valve
l Various common rail injectors
l High-pressure fuel solenoid valves for unit nozzle system and unit pump system
l Glow plug
l Exhaust gas recirculation control valve
l Electric throttle (also known as electronic throttle)
l Variable valve control actuator
l Variable intake pipe length actuator
l Turbocharger exhaust gas vent control valve
l Cooling fan
l Air conditioning compressor electromagnetic clutch
l Other auxiliary equipment on the engine
Some diesel engine sensors and actuators are integrated into the fuel injection equipment, which varies depending on the diesel injection equipment used.

3. Basic electronic control items of gasoline engines
1) Fuel quantitative. This is the most important electronic control item of gasoline engines. The control object is the mass ratio of air and fuel entering the engine, which is determined by the ECU based on parameters such as engine load, speed and coolant temperature. The load is the driver's torque requirement for the engine, which is transmitted to the ECU through the amount of inhaled air or the position of the accelerator pedal. The actuators are electric fuel pumps and electromagnetic fuel injectors. Fuel quantitative affects the power, fuel economy, comfort, emissions and safety of components of the car.
2) Ignition timing. Ignition timing is usually characterized by the crankshaft angle of the piston before the top dead center of the compression stroke when ignition occurs, that is, the ignition advance angle. It is also determined according to the operating parameters such as the engine load, speed and coolant temperature. The actuator is the ignition coil. Ignition timing also affects the power, fuel economy, comfort, emissions and safety of components of the car.
3) Knock control. Gasoline engine knock will damage the engine and worsen emissions and fuel economy. The main way to avoid knock through electronic control is to reduce the ignition advance angle. Therefore, knock control is implemented through ignition timing control. However, too small an ignition advance angle will affect fuel economy. The purpose of knock control is to keep the ignition advance angle at the critical point where knock does not occur.
4) Fuel tank evaporative emissions control. Fuel tank evaporative emissions are all hydrocarbons, which are harmful substances. They must be adsorbed by activated carbon canisters and cleaned with fresh air at appropriate times. The cleaning airflow is sent to the cylinder through the intake pipe for combustion. Cleaning is not possible under all working conditions, so the canister control valve must be used to control the cleaning airflow.

4. Basic electronic control items of diesel engines
Basic electronic control items of diesel engines are fuel metering and injection timing. Both of these are controlled by the injection equipment according to information such as speed, load and coolant temperature. Here, the load information is provided by the accelerator pedal sensor. If the gasoline engine can use or not use the accelerator pedal position sensor, then the diesel engine must use it.

5. Extended electronic control items of the engine
1) Extended electronic control items of gasoline engines
l Electronic control of variable intake pipe length. Used to improve engine power.
l Electronic control of variable valves. Used to improve engine power, economy and comfort, and reduce harmful emissions.
l Electronic control of boost pressure. Used to improve engine power and economy, and reduce harmful emissions.
l Electronic control of exhaust gas recirculation. Used to reduce engine nitrogen oxide emissions.
l Electronic control of secondary air. Used to meet the requirements of Euro 4 and above regulations on hydrocarbon and carbon monoxide emissions.
l Electronic control of three-way catalytic converter fuel heating or electric heating. Used to meet the emission requirements of Euro 4 and above regulations.
l Electronic control of stop-start operation. Used to improve engine economy and meet the emission requirements of Euro 4 and above regulations.
l Electronic control of cylinder closure and valve closure. Used to improve engine economy and reduce harmful emissions.
l Injection pressure and injection timing control. Used for gasoline direct injection, improve power and economy, and reduce harmful emissions.
2) Extended diesel engine electronic control items
l Electronic control of injection pressure. Used to improve engine power and economy, and reduce harmful emissions.
l Electronic control of injection pattern. Used to improve engine power and economy, and reduce harmful emissions and noise.
l Electronic control of multiple injections. Used to improve engine power and economy, and reduce harmful emissions and noise.
l Electronic control of variable intake pipe length. Used to improve engine power.
l Electronic control of variable valves. Used to improve engine power, economy and comfort, and reduce harmful emissions.
l Electronic control of boost pressure. Used to improve engine power and economy, and reduce harmful emissions.
l Electronic control of exhaust gas recirculation. Used to reduce engine nitrogen oxide emissions.
l Electronic control of stop-start operation. Used to improve engine economy and meet the emission requirements of Euro 4 and above regulations.
l Electronic control of cylinder closure and valve closure. Used to improve engine economy and reduce harmful emissions.
l Electronic control of particulate matter trap regeneration. Used to reduce engine particulate matter emissions.

6. Outlook and conclusion
1) Engine electronic control system is a very potential market. With the gradual tightening of emission regulations and the gradual improvement of fuel economy requirements, engine technology is developing rapidly, and new electronic control technologies are constantly emerging.
2) It is said that the focus of the world's manufacturing industry is shifting to China. The automotive industry, including the automotive electronics industry, has also shown this trend to a certain extent. However, at present, the original supporting products of China's engine electronic control system are basically produced by foreign-funded enterprises. The components used by these enterprises to assemble products are almost not produced in China. As a result, China has lost a lot of GDP and jobs. State-owned and private enterprises have low technical levels and can only imitate the products of foreign-funded enterprises and follow foreign-funded enterprises to get a little scraps from the spare parts market. Some even secretly use the name of foreign-funded enterprises to produce counterfeit and shoddy products. This situation should be reversed. The government should see that the development of this industry will bring huge GDP growth and create a large number of employment opportunities. Therefore, the government should make plans to support and rectify this industry.
3) If we want to revitalize China's own engine electronic control industry, we must first meet a prerequisite: automobile factories and engine factories must work together with engine electronic control parts manufacturers, share risks, and promise: once practice proves that domestic engine electronic control systems can meet the requirements, they will use domestic products on their own engines.
4) The vitality of an enterprise lies in the development of new products. Engine electronic control technology develops along with engine technology. China's car industry has always given up independent development of engine technology, and they have no way of knowing what the next generation of engines will look like. The parts industry, including the engine electronic control industry, has no way of developing its own new products, so it will always lag behind its foreign counterparts and always rely on imported technology. If we want to change this situation, first of all, engine factories must abandon the so-called "take-it-and-use-it" approach, gradually transition from imported technology to self-development, and absorb parts manufacturers to participate in the system development and synchronous development of products, so that we can innovate together. There is no other way to follow. The government should provide guidance and formulate encouraging policies.