Working Principle of an Internal Combustion (IC) Engine,
The Spark Ignition (SI) engines work on the principle of cycle of operations invented by Nicolaus A. Otto in the year 1876. The Compression Ignition (CI) engines work on the principle founded by Rudolf Diesel in the year 1892.
The principle of working of both SI and CI engines are almost the same, except the process of the fuel combustion that occurs in both engines. In SI engines, the burning of fuel occurs by the spark generated by the spark plug located in the cylinder head. The fuel is compressed to high pressures and its combustion takes place at a constant volume. In CI engines the burning of the fuel occurs due to compression of the fuel to excessively high pressures which does not require any spark to initiate the ignition of fuel. In this case the combustion of fuel occurs at constant pressure.
This video describes the working principle of an Internal Combustion (IC) Engine. Animation by OcS (www.octavesim.com)