Principle of Operation of an Engine

Automobile engine refers to a fuel-consuming machine or device that is used for propelling automobiles, airplanes, tractors, buses, two wheelers, cars etc. Engine forms an integral component of a vehicle that transforms chemical energy in fuel into mechanical energy for power. Usually, automobile engines make use of four strokes to turn chemical energy into mechanical energy with the help of combustion of gases or hydrocarbon fuel.

Principle of Operation-

In the spark ignition engine an Air/Fuel mixture is formed outside the combustion chamber. This mixture is generated in a Carburetor or by means of Fuel Injection, but in either case the final Air/Fuel mixture is fed into the Cylinder, through the Intake, past the Inlet Valve. The mixture is then Compressed and subsequently Ignited by the Spark Plug. The combustion of ignitable Air/Fuel mixture is initiated (Ignited) by an Electric Spark and burnt inside a working Cylinder.

The combustion Heat given off increases the pressure of the pre-compressed gasses. This after-combustion pressure is typically 400 to 700 PSI, which is much higher than the pre-combustion pressure of 95 to 155 PSI. (PSI = Pounds per Square Inch)

This high pressure produces mechanical work by forcing the Piston down and via Pin and Con Rod causes the Crankshaft to turn.

After each Power Stroke the burnt gases are expelled by the Piston's upward motion and discharged into the atmosphere past the Outlet Valve through Exhaust tract.