Andijon Machine building institute. Faculty machine building texnology Th 3rd year student 06-20 No'monova Ominaxon’s Independent work Andijon Machine building institute. Faculty machine building texnology Th 3rd year student 06-20 No'monova Ominaxon’s Independent work Engine Fundamentals
Chapter 11
The engine is the source of power for the vehicle.
Engine Operation
Engine Operation - Fuel is burned inside the engine’s combustion chamber to produce heat.
- Heat causes expansion of gases in the engine.
- Expansion in the combustion chamber produces pressure.
- Engine components convert pressure into rotating motion.
Engine Operation Piston Travel (TDC, BDC) - Top dead center (TDC)
- Bottom dead center (BDC)
- piston is at its lowest point in the cylinder
- Piston stroke
- distance the piston slides up or down from TDC to BDC
Four-Stroke Cycle - Requires four piston strokes to complete one cycle.
- Every four strokes, the engine produces one power stroke.
- Two complete crankshaft rotations are required to complete the four-stroke-cycle.
- Almost all automobiles use four-stroke-cycle engines.
Intake Stroke - Draws fuel and air into the engine.
- Intake valve is open.
- Exhaust valve is closed.
- Piston slides down and forms a low pressure area in the cylinder.
- Atmospheric pressure pushes the air-fuel mixture into the engine.
Compression Stroke - Compresses the air-fuel mixture, making it more combustible.
- Piston slides upward.
- Both valves are closed.
Power Stroke - Burns the air-fuel mixture and pushes the piston down with tremendous force.
- Both valves are closed.
- Spark plug fires, igniting the air-fuel mixture.
- Pressure forms on the top of the piston.
- Piston is forced down, rotating the crankshaft.
Exhaust Stroke - Removes the burned gases from the cylinder.
- Piston moves upward.
- Intake valve is closed.
- Exhaust valve is open.
- Burned gases are pushed out the exhaust port.
Four-Stroke Cycle
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