The main purpose and meaning of evolution of human beings is the advancement in all fields. The growth and progress are always aimed in the upward direction and the field of automation is the best example to prove the latter statement.
Technology has developed in various areas and when it comes to improvement of speed and power, engines are perhaps the first machinery that comes to our mind. But as engines continue to evolve, they produce astonishing amounts of power and emissions that take an expense on the environment and off late, mechanical advancements merely cannot do the job of keeping the engine in good health all the time. There has to be a dominant system which controls everything from emissions and Air/Fuel ratio to power and torque. The Engine/Electronic Control Unit (ECU) plays a very important role in controlling these actions.
NECESSITY OF AN ECU
An ECU controls an engine in its better state by wielding the sensors and actuators which cause the in changes of the air-fuel mixture, ignition timing, and idle speed. The engine breathes in oxygen rich air mixed with fuel through the intake system. The air and fuel mix is employed to produce power and to do useful work. This system is made up of the air filter and intake valves and breathes out CO, NOx and HCs through the exhaust valves and catalytic converter and then exits through the tail pipe. In order to perform these processes efficiently and consistently, an ECU is required.
FUNCTIONS OF AN ECU
IGNITION TIMING CONTROL: A certain crank angle in the compression stroke gives maximum torque output if the air/fuel mix is ignited at that particular point. The ECU decides this position and accordingly fires the spark plugs.It determines the amount of air and fuel entering into the engine and accordingly plans the combustion process by varying the amount of fuel delivered through the Fuel Injectors.
AIR/FUEL MIXTURE CONTROL: The amount of air and fuel entering into the engine is determined and accordingly the ECU plans the combustion process by changing the amount of fuel delivered through the Fuel Injectors.
IDLE SPEED CONTROL: It keeps the idle speed in check of the engine based on the ambient temperature, engine oil temperature and coolant temperature of an engine. This is the reason that when starting the engine for the first time in the morning, the RPM is more compared to normal idle RPM. This is action is governed by the ECU.
ELECTRONIC VALVE CONTROL: Experimental engines have been made and tested that have full electronic control of the intake and exhaust valve opening, valve closing, and area of the valve opening. Such engines can be started and run without a starter motor for specific multi-cylinder engines armed with precision timed electronic ignition and fuel injection. At steady load conditions, the valve opens, fuel is injected, and the valve closes. Under a sudden increase in throttle, the valve opens in the same intake stroke and a greater amount of fuel is injected. This allows immediate acceleration. For the next stroke, the ECU measures the engine load at the new, higher RPM, and decides how to open the valve(early or late, wide-open or half-open). Once it is fully developed the electronic valve control will yield higher results and can be put to better use.
Although it is expensive and difficult to work on, it provides a precise monitoring of fuel for better mileage and lesser emissions and also better throttle response for a higher responsive engine performance.