A petrol car engine, also known as a gasoline engine, operates based on the principle of internal combustion. Here's a simplified explanation of how it works:
1. Intake Stroke:
- The engine cycle begins with the intake stroke. The piston moves downward in the cylinder, creating a low-pressure area.
- A mixture of air and fuel, prepared in the carburetor or fuel injector, is drawn into the cylinder through the open intake valve.
2. Compression Stroke:
- The piston then moves back up in the cylinder, compressing the air-fuel mixture significantly. This increases its pressure and temperature.
3. Combustion Stroke:
- At the top of the compression stroke, a spark plug generates a high-voltage spark, igniting the compressed air-fuel mixture.
- The ignited mixture undergoes rapid combustion, causing a significant increase in pressure and temperature.
4. Exhaust Stroke:
- The force created by the expanding gases pushes the piston down in the cylinder, generating power.
- Near the bottom of the power stroke, the exhaust valve opens, and the piston moves up again, pushing the burned gases out of the cylinder through the exhaust valve.
5. Repeat:
- The cycle repeats itself continuously with coordinated timing of the valves, spark plug, and piston movement.
Diesel Car Engine:
A diesel car engine also operates based on internal combustion, but it has some key differences compared to a petrol engine:
1. Compression Ignition:
- Diesel engines do not have spark plugs. Instead, they rely on compression alone to ignite the fuel.
- The compression ratio in diesel engines is much higher compared to petrol engines, leading to much higher pressure and temperature during the compression stroke.
2. Fuel Injection:
- In diesel engines, fuel is injected directly into the cylinder just before the compression stroke.
- This allows for more precise control of fuel delivery and timing.
3. Auto-Ignition:
- As the air is highly compressed and heated during the compression stroke, it reaches a point where it causes the diesel fuel to spontaneously ignite. This is known as auto-ignition.
4. Power and Efficiency:
- Diesel engines typically provide better fuel efficiency and produce more torque compared to petrol engines of similar size.
- They are often preferred for heavier vehicles and long-distance driving due to their durability and fuel efficiency.
Both petrol and diesel engines convert the energy released by burning fuel into mechanical energy that powers the vehicle. However, diesel engines operate with higher compression ratios, enabling more efficient combustion and providing better fuel economy.
