Petrol Engine

SIMERNJEET KAUR (XB) SONIA (XB) JASPREET KAUR (XA) RACHANDEEP KAUR (XC)

MRS. RITU CHOPRA MRS. SUDHA VERMA

Petrol engine is an engine that uses petrol as a fuel. The working of an internal combustion engine is divided into four stages called four strokes of the engine and hence the engine is called a four stroke engine. The intake stroke: When the engine starts, the piston moves downwards in the cylinder, because of which a region of low pressure is created in the cylinder, above the piston. At this moment, the intake valve opens and the mixture of petrol vapour and air is sucked into the cylinder from the carburettor.

The compression stroke: When the sufficient amount of the fuel mixture has entered the cylinder, the intake valve gets closed. The piston is then forced to move upwards which compresses the fuel-mixture to about one-eighth of its original volume.

The power stroke: During the compression of the fuel mixture the spark plug produces the electric spark which sets fire to the petrol air mixture. With the little explosion large amount of gases and heat is produced. The hot gas pushes the piston and piston rod down ward. The piston rod pushes the crank shaft which is joined to the wheels of the car. When the crank shaft turns, the wheels rotate and move the car.

The exhaust stroke: With the upward movement of the piston the spent gases are expelled through the exhaust valve. The exhaust valve closes the intake valve opens up .The above four strokes of the engine are repeated again and again.