A four-stroke diesel engine is an internal combustion engine that operates on the four-stroke cycle principle, also known as the Otto cycle. These engines are commonly used in a variety of applications, including automobiles, trucks, buses, ships, locomotives, and industrial equipment. Here's how a four-stroke diesel engine works:
1. Intake Stroke:
- During the intake stroke, the intake valve opens, and the piston moves downward, creating a vacuum in the cylinder.
- Air is drawn into the cylinder through the intake valve, filling the combustion chamber with fresh air.
2. Compression Stroke:
- Once the intake stroke is complete, the intake valve closes, and the piston begins to move upward, compressing the air within the cylinder.
- As the piston moves upward, the air is compressed, increasing its temperature and pressure. This compression raises the air temperature to the point where diesel fuel injected into the combustion chamber will ignite spontaneously.
3. Power Stroke:
- When the piston reaches the top of its stroke, diesel fuel is injected into the combustion chamber at high pressure by the fuel injector.
- The fuel mixes with the highly compressed air, and the heat of compression ignites the fuel spontaneously, causing it to combust rapidly.
- The combustion of the fuel-air mixture generates a high-pressure, high-temperature gas that exerts force on the piston, driving it downward. This is the power stroke, where the engine produces mechanical work.
4. Exhaust Stroke:
- After the power stroke, the exhaust valve opens, and the piston moves upward again, pushing the exhaust gases out of the cylinder.
- The expelled exhaust gases are routed through the exhaust system to the atmosphere, completing the four-stroke cycle.
Key Components of a Four-Stroke Diesel Engine:
Cylinder: The combustion chamber where the fuel-air mixture is ignited and the power stroke occurs.
Piston: Moves up and down within the cylinder to compress the air-fuel mixture, absorb the force of combustion, and expel exhaust gases during the exhaust stroke.
Crankshaft: Converts the linear motion of the piston into rotational motion, transferring power from the engine to the transmission and ultimately to the wheels or driven equipment.
Camshaft: Controls the opening and closing of the intake and exhaust valves, synchronizing their operation with the movement of the piston.
Fuel Injector: Delivers a precise amount of diesel fuel into the combustion chamber at the correct time and under high pressure, ensuring efficient combustion and power generation.
Four-stroke diesel engines are known for their durability, fuel efficiency, and torque output, making them suitable for heavy-duty applications and long-distance transportation. They are widely used in the automotive industry and various industrial sectors due to their reliability and versatility.
