A positive ignition engine is a type of heat engine. This type of engine works following the Otto cycle and can be two and four-stroke. For this reason, these kinds of internal combustion engines are also called Otto engines or ignition gasoline engines.
In this type of engine, an element appears, the spark plug, which is capable of causing a spark when it receives electrical energy. In this way, the spark plug can transform the electrical energy that comes from the battery into a spark.
How does a positive ignition engine work?
Around the spark caused by the spark plug, the so-called initial ignition source is created. In the initial ignition source, the combustion of the fuel spreads, forming a flame front.
When the flame ignites the fuel, the pressure increases. Due to this pressure, the piston will begin to move. The speed with which the fuel ignites is determined by the air/gasoline ratio.
If there is no normal combustion inside the engine cylinder, two things can happen:
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A detonation phenomenon: In detonation, everything typically happens until a quantity of fuel/air mixture that has not yet burned explodes. This explosion causes premature combustion and unnecessary pressure on the piston. As a result, the temperature rises, and the possibility of a car ignition also increases.
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An ignition phenomenon: Self-ignition consists of the ignition of the mixture due to a scorching spot in the combustion chamber. Later, in addition, the spark jumps, so we find two flame fronts increasing the pressure and the temperature.
Self-ignition and detonation are two different phenomena, but one can give rise to the other, causing the engine to stall.
How is the fuel mixture in positive ignition?
The richness of the mix is often talked about. The mixture is rich when it suffers from excess gasoline. If the fuel mixture is very rich in gasoline, there is not enough air, and that all the fuel cannot be burned. In this way, a great deal of fuel would be wasted.