1. Intake Stroke: The piston moves downwards, creating a vacuum in the cylinder. This vacuum draws a mixture of air and fuel (or just air in the case of a diesel engine) into the cylinder through the intake valve.
2. Compression Stroke: The piston moves upwards, compressing the air-fuel mixture. This increases the pressure and temperature of the mixture.
3. Power Stroke: The spark plug ignites the compressed fuel-air mixture, causing a rapid expansion of gases that pushes the piston downwards. This is the stroke that produces power to rotate the crankshaft.
4. Exhaust Stroke: The piston moves upwards again, pushing the burnt exhaust gases out of the cylinder through the exhaust valve.
This cycle repeats itself continuously as long as the engine is running. Each cycle corresponds to two revolutions of the crankshaft.
Key points to remember:
* Valve timing: The intake and exhaust valves open and close at specific times during the cycle to control the flow of air and fuel.
* Fuel ignition: In gasoline engines, the spark plug ignites the fuel-air mixture. In diesel engines, the compression itself ignites the fuel.
* Work and energy: The power stroke is where the engine does useful work. The other three strokes are necessary to prepare for and complete the power stroke.
