CAP 2 PISTON ENGINE PRICIPLES Flashcards
POWER
TORQUE X RPM
TORQUE?
THE CAPACITY TO DO WORK ( LEVERAGE) ,MEASURED IN POUNDS /FOOT OR NEWTON METRES
T= FORCE X DISTANCE
THE TORQUE COLD /WARM AIR?
IS MUCH HIGHER IN COLD WEATHER THAN WARMER .
AND IS INDICATION OF HOW MUCH POWER IS PRODUCING
F=pressure x area changing and variable
AREA IS FIXED IN FORCE FORMULA SO WE CAN CHANGE ONLY THE PRESSURE MOVING THE ENGINE LEVER
Torque and speed?
Torque and speed are inversely proportional
Most used engine configuration
Horizontally configuration engines
How many revolution for a full stroke cycle
For a four stroke engine, two revolution of the crank shaft needed
STAGES OF ENERGY IN FOUR STROKE
1) chemical nergy
2) HEAT
3) PRESSURE
4) MECHANICAL ENERGY
THE CHARGE
FUEL AIR MIXTURE IS CALLED “THE CHARGE”
TDC
TOP DEAD CENTRE WHEN IS AT THE TOP OF THE EXTENTION
BDC
BOTTOM DEAD CENTRE ,WHEN IS AT THE BOTTOM OF THE EXTENTION PHASE.
DIFFERENCE BETWEEN TDC AND BTC
STROKE
Diesel and petrol difference in strokes and bore
PETROL ENGINE HAS SMALL STROKE BUT GREAT PISTON BORE( AREA OF THE PISTON).
Diesel engines has large stroke but small piston bore.
Diesel has more torque
Stroke and degrees in
1 stroke = 180 degrees
4 stroke = 720
What is used to connect the piaston to the crankshaft
Connecting rod
Crankshaft/camshaft
Crankshaft need do two revolution to have 1 revolution of the camshaft
Theoretical cycle
Induction
Compression
Power
Exhaust
Practical 4 stroke-cycle
The ineffective crank angle
Smaller linear movement of piston compared to angular rotation of crankshaft at TDC and BDC
Practical inlet opening
Inlet valve still open as compression stroke begins.
Because the angular rotaion of thecrankshaft is higher than lettle movemnt of the volume .so we keep the inlet valve open lit bit longer
Valve over lap ( both valves open)
Inlet vale lead
During the exhaust stroke we open the inlet earlier to get some of new fresh air
Exhaust valve lead
Exhaust valve is open before the end of the power stroke
Exhaust valve lag
The exhaust valve remains opne until slighlty after tdc .
Exhaust gas exits under its own momentum
Flame rate
60 to 80 ft/sec
Advance ignition
Because not enough time to burn all the mixture
Ignition timing
Just before TDC ,TDC, and just after TDC
