We will discuss the full series of separate steps or events which follow each other while a diesel engine is in operation.
First Step:(INTAKE)
Air is introduced into the cylinder because
no fuel will burn without air. Burning or combustion is a process of uniting
fuel or combustible with the oxygen in the air. The process is a chemical reaction
which means that fuel & oxygen, in uniting, change into new substances.
Second Step:(COMPRESSION)
The air must be squeezed or compressed to high pressure. Two reasons for compressing the air are to get high temperature
and high pressure thereby higher power. In a diesel engine the air is
compressed so much that it becomes hot and in fact, it will be hot enough to
ignite oil that is sprayed into it.
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| VARIOUS CYCLES OF EVENTS DURING ENGINE OPERATION |
Third Step:(FUEL INJECTION)
The fuel is injected into the cylinder in
the form of fine spray after the air has been compressed and thus heated to a
high temperature. It must be in the form of fine spray so that a cloud of oil
droplets will spread through all the air in the cylinder.
Fourth Step:(COMBUSTION)
Combustion takes place after the oil is
sprayed in the cylinder. This will generate a large amount of heat. The gaseous
mixture gets hotter and grows larger or expands due to higher pressure.
It pushes on the piston, which in turn
transmits the force through the connecting rod to the crank of the crankshaft.
This will make the crankshaft revolve.
Fifth Step:(EXHAUST)
When the piston has finished its preceding
power stroke and the gases in the cylinder have lost their pressure, the spent
gases must be exhausted.
A cycle is a full series of separate steps
or events, which follow each other.
For a Four Stroke Cycle Engine, a
complete cycle requires four strokes of the piston.
For a Two-Stroke Cycle Engine, a
complete cycle requires two strokes of the piston.
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