A four-stroke engine is a type of internal combustion engine that completes four distinct processes—intake, compression, power, and exhaust—during two crankshaft revolutions. Here’s a brief overview of how a four-stroke engine operates:
1. **Intake Stroke:**
– The first stroke begins with the intake valve opening, allowing a mixture of air and fuel to enter the combustion chamber as the piston moves downward. This process is driven by the rotating crankshaft.
2. **Compression Stroke:**
– The intake valve closes, and the piston moves upward, compressing the air-fuel mixture within the combustion chamber. This compression increases the mixture’s temperature and pressure.
3. **Power Stroke:**
– Once the air-fuel mixture is compressed, a spark plug ignites it. The resulting combustion produces a rapid expansion of gases, forcing the piston downward. This movement is the power stroke, and it provides the mechanical energy to turn the crankshaft.
4. **Exhaust Stroke:**
– As the piston reaches the bottom of the power stroke, the exhaust valve opens, and the piston moves upward, pushing the burned gases out of the combustion chamber and into the exhaust system.
These four strokes—intake, compression, power, and exhaust—constitute one complete cycle. The engine then repeats this cycle to continuously generate power.
Four-stroke engines are commonly used in cars, motorcycles, and many other types of vehicles. They are known for their efficiency, smoother operation, and better fuel economy compared to two-stroke engines.