The working principles of an internal combustion engine (ICE) involve converting chemical energy from fuel into mechanical energy through a controlled combustion process.
The most common type of ICE is the four-stroke engine, which operates through four distinct strokes in a cycle.
Here’s a detailed explanation of the four-stroke engine working principles:
Four-Stroke Cycle
1.Intake Stroke:Process: The intake valve opens, and the piston moves down from the top dead center (TDC) to the bottom dead center (BDC).
Purpose: This downward movement creates a vacuum that draws a mixture of air and fuel (or air alone in diesel engines) into the combustion chamber from the intake manifold.
2.Compression Stroke:Process: The intake valve closes, and the piston moves up from BDC to TDC, compressing the air-fuel mixture (or just air in diesel engines).
Purpose: Compressing the mixture increases its pressure and temperature, making it more volatile and ready for ignition. In diesel engines, this stroke only compresses the air, significantly raising its temperature.
3.Power Stroke (Combustion Stroke):Process: Just before the piston reaches TDC at the end of the compression stroke, a spark plug ignites the air-fuel mixture (in gasoline engines) or fuel is injected into the hot, compressed air (in diesel engines), causing combustion.
Purpose: The combustion process rapidly increases the pressure within the cylinder, forcing the piston down from TDC to BDC. This downward motion converts the chemical energy of the fuel into mechanical energy, which is then transmitted to the crankshaft.
4.Exhaust Stroke:Process: The exhaust valve opens, and the piston moves up from BDC to TDC.Purpose: This upward movement expels the burned gases from the combustion chamber through the exhaust valve and out of the engine, preparing the cylinder for the next intake stroke.
Two-Stroke Cycle (Alternative)In a two-stroke engine, the cycle is completed in just two movements (one revolution of the crankshaft)
1.Compression and Power:As the piston moves up, it compresses the air-fuel mixture. Near the top, a spark plug ignites the mixture, and combustion drives the piston down.
2.Exhaust and Intake:As the piston moves down, it uncovers exhaust ports, allowing exhaust gases to escape. Simultaneously, fresh air-fuel mixture enters the chamber through intake ports, which are then compressed as the piston moves up again.
Key Components and Their Functions
1.Piston: Moves up and down within the cylinder, driven by combustion.
2.Cylinder: The chamber where the fuel is burned.Crankshaft: Converts the piston's linear motion into rotational motion.
3.Connecting Rod: Connects the piston to the crankshaft.
4.Valves: Control the intake of the air-fuel mixture and exhaust of burned gases (present in four-stroke engines).
5.Spark Plug: Ignites the air-fuel mixture in gasoline engines.
6.Fuel Injector: Injects fuel into the combustion chamber in diesel engines.
Overall Principle. In essence, internal combustion engines operate by Drawing in a fuel-air mixture (or air alone in diesels).Compressing it to increase potential energy.Igniting the mixture to create an explosive force.Using the resulting pressure to produce mechanical work.
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