Piston Engine Operation Flashcards
How do Piston Engines produce power
Converting chemical energy to mechanical energy.
mixture is
exhaust gas is
Charge is
Atmospheric air
Gas produced from burning mixture
Total amount of mixture
Function of Crankshaft
Converts linear motion of piston into rotary motion
4 stroke cycle
Induction, Compression,
Power,
Exhaust
What does stroke mean
Distance between the Top dead centre TDC
and Bottom dead centre BDC
4 stroke is equal to
720* rotation of crankshaft.
1 stroke=180* rotation.
What happens in to combustion in the theoretical cycle
Occurs spontaneously
What is RPM
Revolutions per minute is the number of times the crankshaft rotates in a minute.
What is the ineffective crank angle
Very little linear piston movement for angular rotation speed of crankshaft.
What is Valve lead/Valve Lag
Valve Lead- Inlet valve opened before piston reaches TDC in exhaust stroke.
Valve Lag- Inlet valve left open beyond BDC.
Both help to maximise amount of mixture in cylinder.
What is Exhaust Valve lead/Lag
Exhaust valve opened just before end of power stroke.
Lag is when the exhaust valve is left open just have TDC. Allows remaining exhaust gas to exit under its own momentum.
What is Ignition Timing
Precise time at which spark is delivered to the cylinder must be carefully timed. Finite time for mixture to combust and reach peak pressure. Ignition occurs just before piston reaches TDC to maximise pressure. Ignition is said to be ADVANCED.
What determines valve timing
Camshaft operating on the valve rockers via push rods,
What happens at valve overlap
Both inlet and exhaust valves are open at end end of exhaust stroke. Action of exhaust gases flowing out helps to draw in fresh mixture. This is called scavenging.
