Short Answer

The working principle of a 4-stroke engine is based on four stages: intake, compression, power, and exhaust. In these four strokes, the engine completes one full cycle and produces power by burning fuel inside the cylinder.

During these strokes, the piston moves up and down inside the cylinder, and the crankshaft converts this motion into rotation. This process repeats continuously to keep the engine running and produce power efficiently.

Detailed Explanation:

Working principle of a 4-stroke engine

A 4-stroke engine is a type of internal combustion engine in which one complete cycle of operation is completed in four strokes of the piston. These strokes are intake stroke, compression stroke, power stroke, and exhaust stroke. The working principle of this engine is based on the conversion of chemical energy of fuel into mechanical energy through controlled combustion inside the cylinder.

In a 4-stroke engine, the piston moves up and down inside the cylinder, and this movement is connected to the crankshaft. The crankshaft converts the reciprocating motion of the piston into rotational motion, which is used to drive the wheels of a vehicle. Each stroke plays a specific role in the operation of the engine, and all four strokes must occur in sequence for proper functioning.

Intake stroke

The intake stroke is the first stage of the engine cycle. In this stroke, the piston moves downward from the top dead center to the bottom dead center. As the piston moves down, the intake valve opens, and a mixture of air and fuel enters the cylinder. This mixture is necessary for the combustion process.

Compression stroke

The compression stroke is the second stage. In this stroke, the piston moves upward from the bottom dead center to the top dead center. Both intake and exhaust valves remain closed during this stage. The air-fuel mixture is compressed, which increases its pressure and temperature. This compression makes the combustion process more efficient.

Power stroke

The power stroke is the third and most important stage. At the end of the compression stroke, the spark plug ignites the compressed air-fuel mixture in a petrol engine. In diesel engines, fuel is injected and ignites due to high temperature. The combustion produces high-pressure gases that push the piston downward. This downward movement generates power.

Exhaust stroke

The exhaust stroke is the final stage. In this stroke, the piston moves upward again from bottom dead center to top dead center. The exhaust valve opens, and the burnt gases are pushed out of the cylinder. This clears the cylinder for the next cycle.

Cycle repetition

After completing the exhaust stroke, the cycle starts again with the intake stroke. This continuous repetition of four strokes allows the engine to produce continuous power. The crankshaft completes two revolutions for one complete cycle of a 4-stroke engine.

Advantages of 4-stroke engine

4-stroke engines are more efficient and produce more power compared to 2-stroke engines. They consume less fuel and produce fewer emissions. They are widely used in cars, motorcycles, and other vehicles due to their reliability and smooth operation.

Conclusion

The working principle of a 4-stroke engine is based on four strokes: intake, compression, power, and exhaust. These strokes work together to convert fuel energy into mechanical energy. This type of engine is widely used due to its efficiency, smooth operation, and reliability.