Combustion chamber
Otto cilco thermal engine

Ignition By Spark

Ignition by spark

We call it by spark to the one of the forms in which it ignites a thermal engine. The engines starting with spark ignition are Otto cycle gasoline engines.

In this type of engines there is an element, the spark plug, which is capable of causing a spark when it receives electric energy. In this way, the spark plug is capable of transforming the electrical energy coming from the battery into a spark.

Around the spark causing the spark plug creates the so-called initial ignition source. In the initial ignition focus fuel combustion is spread forming a flame front.

As the flame goes on the fuel increases the pressure. Thanks to this pressure will begin to move in piston. The rate at which fuel is ignited is determined by the air / gasoline ratio.

Richness of the mixture in the spark ignition

We often talk about the richness of the mix. The mixture is rich when it suffers an excess of gasoline. If the mixture of fuel is very rich in gasoline it means that there is not enough air and that you will not be able to burn all the fuel. This would waste a lot of fuel.

On the other hand, there is the poor mix. The lean mixture is that mixture having an excess of air. Excess air causes fuel combustion to be too slow, the engine heats up and engine performance is lower.

Detonation and ignition

If conditions do not produce normal combustion two things happen: a detonation phenomenon or a phenomenon of ignition.

In detonation everything happens in a normal way, until a quantity of fuel / air mixture that has not yet burned explodes. This explosion causes an anticipation in the combustion and an unnecessary pressure in the piston. The temperature increases and the possibility of self-ignition increases.

Self-ignition consists of the ignition of the mixture due to a too hot spot in the combustion chamber. Later, in addition, the spark jumps, so we do not encounter two flame fronts. This situation causes both pressure and temperature to increase.

Self-ignition and detonation are two distinct phenomena, but one can give rise to the other, causing the engine to chop.

Both the shape of the chamber and the location of the spark plug influence combustion. This is always placed in the butt, regardless of the type of camera it is.

A camera should remove as much of the risk of chopping as possible, so the shape should allow most of the mixture to ignite with the jump of the spark. This is why the spark plug is placed in the highest volume.


Published: March 12, 2017
Last review: March 12, 2017