"An engine is the heart of any automobile. It is the powerhouse and the prime mover due to which a vehicle moves. An engine converts heat energy obtained by combustion of the fuel into mechanical work."

construction and working of four stroke engine

Engines are classified into numerous ways. However engines are classified on the basis of :
  1. Fuel used in combustion (either petrol or desiel)
  2. Working cycle (either 4 stroke engine or 2 stroke engine)
Now let us first know what is meant by stroke. Stroke is the distance covered by the piston from one of its dead center position to the other dead center position.

In 4 stroke engine, in every 2 complete revolution of the crankshaft 4 strokes of the piston is completed.Out of which one stroke is power stroke. The 4 strokes are :
  1. Suction stroke.
  2. Compression stroke.
  3. Combustion stroke.
  4. Exhaust stroke.

working of the four stroke engine

Working of 4 sroke engine.

The working cycle of an engine starts with the suction strokes. As shown in the above fig. in the suction stroke the piston goes downwards, creating vaccum . Simultaneously, the inlet valve opens up and the fuel and air mixture is injected into the cylinder. Then comes the compression stroke. In this stroke the piston moves upwards, thus compressing the air and fuel mixture. Due to compression the air and fuel mixture is heated. Now comes the combussion stroke, in which the compressed air and fuel mixture is ignited using the spark plug. This causes the fuel to burn and expand which in turn pushes the piston downwards. The last stroke is the exhaust stroke in which the piston moves uopwards once again compressing the gases, however at this very time the outlet wire of the engine opens up. Thus the piston ends up removing the waste gases out from the cylinder.

So this is in short ”What is 4 Stroke engine?’