2 Stroke and 4 Stroke Engine

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PRESENTED BY:-

BINAY PRASAD SONI MER072AMULYA KUMAR PANDA MER073

DEBASIS BISOY MER074RAJAN KUMAR GUPTA MER075


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WHAT IS 2S & 4S ?A two-stroke petrol engineis an internal

combustion engine that completes the process cycle inone revolution of the crankshaft. Thus, one powerstroke is obtained in each revolution of the crankshaft.

A four stroke diesel engineis an internal

combustion engine that completes the process cycle intwo revolution of the crank shaft. Thus, one powerstroke is obtained in each two revolutions of the crankshaft.


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Basic Parts of the 2 stroke petrol

engine Cylinder block

Piston

Piston rings

Spark plug Connecting rod

Crankshaft


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Spark Plug

Electric match used tobegin the combustionprocess of burning air

and petrol to createheat. It provides the means

of ignition when thepetrol engines piston is

at the end ofcompression stroke,close to Top DeadCenter(TDC)


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Connecting Rod

Connects the pistonand piston pin to the

crankshaft.


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Piston

A sliding plug thatharnesses the force of

the burning gases inthe cylinder.


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Crankshaft

Along the the pistonpin and connecting

rod it converts the upand down motion(reciprocating) of theengine to spinning

(rotary) motion.


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WORKING PRINCIPLE OF 2S 1.Here suction and exhaust strokes are eliminated.

Instead of valves, ports are used.

2.The exhaust gases are driven out of the cylinder by

the fresh charge entering the cylinder. 3. The intake & exhaust are controlled by movement

of piston.

4. The fresh charge enter to cylinder due todifference of pressure.

5.The charge is compressed by the pumping actionof the piston due to the design of crankcase.


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8. As the piston continues to move upward, exhaustand transfer port get closed and the compression is

continued. 9. In the end of compression the spark is created

which ignites the charge and the products ofcombustion thrust the piston from TDC to BDC.

10. This cycle is repeated continousely.


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Advantages of 2S-petrol engine The power developed will be nearly twice that of four-

stroke engine of same dimension and operating at thesame speed.

The work required to overcome the friction of theexhaust and suction strokes is saved.

Low weight.

Construction is simple.


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Disadvantages of 2S-petrol engineAs working on Otto-cycle, a part of the fresh mixture is

lost through exhaust port.

Part of the piston stroke is lost. Heavy consumption of lubricating oil.


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Basic Parts of the 4S Diesel Engine Cylinder block

Piston

Piston pin

Connecting rod Crankshaft

Cylinder head

Intake valve

Exhaust valve

Camshaft Timing gears

Fuel injector


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The Fuel Injector is connected to

a high pressure pump that is notillustrated.

It sprays a small amount of dieselfuel into the Cylinder at the endof the Compression Stroke and

beginning of the Power Stroke.

The fuel is sprayed throughseveral very small holes at veryhigh pressure in order to form a

fine mist of droplets of fuel thatwill ignite easily and burn quicklyin the hot air.

Nozzle tip with severalsmall holes for fuel spray

INJECTOR


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Working of 4S-Diesel engine


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Comparison of 4S-2S cycle engineFour stroke engine Two stroke engine

Cycle is completed in fourstrokes of piston & in tworevolution of crankshaft.

Heavier flywheel is needed.

Power produced for same sizeof engine is less.

Volumetric efficiency is moredue to more time forinduction.

Cycle is completed in twostrokes of piston & in onerevolution of crankshaft.

Lighter flywheel can be used.

Power produced for same sizeof engine is twice.

Volumetric efficiency is lowdue to lesser time forinduction.


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2 Stroke and 4 Stroke Engine

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