All About Internal Combustion Engine

The development of an IC (Internal Combustion) Engine made a profound impact on the lives of everyone. Automobiles like scooters, motorbikes, cars, trucks, etc are powered by IC Engine. Diesel engines and even Jet engines are also powered by the principle of internal combustion.

Working of an IC Engine:

In a 4-stroke IC engine, one complete cycle of a piston is completed in 4 strokes. In the 1st stroke (intake stroke) the piston moves from the cylinder head to the bottom of the cylinder. The downward movement of the piston creates a vacuum inside the cylinder. This vacuum helps to draw the air and fuel mixture into the cylinder with the help of an intake valve, this intake valve closes when the piston touches the bottom of the cylinder.

The next stroke is the compression stroke. In this stroke, the piston is pushed upwards resulting in the compression of the air and fuel mixture making it easier to ignite. Also, the compressed air and fuel mixture when ignited results in the more powerful explosion.

The compression stroke is followed by the power stroke. In this stroke, the compressed air and fuel mixture is ignited with the help of an electric spark from the spark plug, resulting in the explosion of the air and fuel mixture. This explosion inside the cylinder pushes the piston downwards. The power generated in this stroke is utilized to turn the crankshaft.

In the final stroke (exhaust stroke) the piston moves upward and reaches the intake stroke position and thus the entire process is repeated again. In this stroke, an exhaust valve is utilized to expel all the exhaust gases generated by the explosion of air and fuel mixture out from the engine cylinder.

Advancement of an IC Engine:

In a 2-stroke IC Engine, the exhaust and intake strokes are eliminated and combined with the power and compression strokes. Hence, a 2-stroke IC Engine has a less complex design and are comparatively lighter, powerful and smaller in size. However, these engines are quite inefficient in burning fuel. A residual of unburned fuel is left behind that hinders the process of combustion. Also, the fuel is ignited twice in comparison to the 4-stroke IC Engine increasing the chances of wear and tear of the engine parts. Therefore, 2-stroke IC Engines are utilized in small and lightweight applications (motorbikes, chainsaw, scooters, lawn mower, etc). The automobiles normally have 4,  6, or 8 cylinder engines, all operating together in a precisely defined sequence to drive the crankshaft. There are several advantages of having more number of cylinders as they assist the combustion process by burning more fuel which in turn enhances the energy production necessary to drive the crankshaft.

The spark plugs of an IC Engine with multiple cylinders must be timed accurately so that the constant force is exerted on the crankshaft, allowing the smooth running of the engine. An appropriate firing order helps to minimize the engine vibration, improves the engine balance, facilitates the smooth running and also improves the engine fatigue life. In a petrol engine, the proper firing sequence is achieved by the correct arrangement of the spark plug wires on the distributor. Modern-day engines are generally equipped with ECU (Engine Control Unit) or EMS (Engine Management System) that takes care of a proper firing sequence.

This is a brief explanation of working and principle of Internal Combustion Engine. In addition to the gas-powered piston-driven IC Engines, several other types of IC Engines have been developed, like gas turbine engines, Wankel engines, etc. For a better understanding and visual analysis of engine thermodynamics in a 2 Stroke or 4 Stroke diesel and petrol engines, subscribe to our Byju’s YouTube Video channel-