Spark Plugs
Chapter 1 Outline
Chapter 1
Study Tips
Let us study about the role of the ignition system,
its components parts, and its different types.
Outline
05
4-Stroke Engines
4-Stroke Engines
The 4-stroke engine was first invented by N. Otto in 1876. So it is also known as the
Otto Cycle.
The spark plugs ignite and the gasoline burns driving the piston downwards, creating
power.
Intake
Compression
Combustion
Intake and compression
Combustion and exhaust
Exhaust
Intake
Compression
Exhaust
These four strokes rotate the crankshaft twice and complete one cycle.
Operation of 4-stroke engines
Intake stroke
1
Takes the air-fuel
mixture into the
cylinder.
Compression stroke
2
Compresses the air-fuel
mixture to high
temperature and high
pressure.
Intake and compression stroke
1
When the piston rises and the cylinder side
compresses, the crank case side is a vacuum and
takes in the air-fuel mixture.
Combustion and exhaust stroke
2
When the piston is pushed down by the combustion,
the air-fuel mixture on the crank case side is sent to
the cylinder side where it pushes out the exhaust gas.
Combustion stroke
3
Ignites and combusts the gas
mixture and uses the resulting
high pressure to rotate the
crankshaft.
Exhaust stroke
4
Exhausts the exhaust
gas.
Combustion
These two strokes complete one cycle during one motion of the piston (one crankshaft rotation).
2-stroke engines do not require moving valves and have a simpler structure, but the compression ratio is low and they are only
appropriate for small displacements.
2-stroke engines
REFERENCE
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