Classification, working principals and construction of IC Engine.pdf

Classification, working principals and construction of IC Engine

1. Dr.JayantaKr.Mahato
AssistantProfessor
MechanicalEngineeringDept.
ShobhitDeemedto-beUniversity
Contact:[email protected]
Unit -1 Lecture –3-6

2. Introduction of an Engine
Dr. Jayanta Kr. Mahato, Asst. Prof., Mechanical Engineering
“Engineisadevicewhichconvertchemicalenergyto
mechanicalenergy”
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3. HeatEngine
Isamachine forconvertingheat,developedbyburningfuelintousefulwork.
Itcan besaidthatheatengineisequipmentwhichgeneratesthermalenergyand
transformsitintomechanicalenergy.

4. CLASSIFICATIONOFHEATENGINES
Basedoncombustionoffuel:
1.Externalcombustionengine
2.Internalcombustionengine.
Basedonfuelused
1.Dieselengine
2.Petrolengine
3.Gasengine
Basedignitionoffuel
1.Sparkignitionengine(Carburetortype engines)
2.Compressionignitionengine(injectortypeengines)

5. ExternalCombustionEngine
Here, the working medium, the steam, is generated in a boiler, located outside
theengineandallowedintothecylindertooperatethepistontodomechanical
work.

6. InternalCombustionEngine
Ininternalcombustionengine,thecombustionoffueltakesplaceinsidethe
enginecylinderandheatisgeneratedwithinthecylinder.
Thisheatisaddedtotheairinsidethecylinderandthusthepressureof theairis
increasedtremendously.
Thishighpressureairmoves thepistonwhichrotatesthecrankshaftandthus
mechanicalworkisdone

7. Classification of IC Engine
BasicEngineDesign
ReciprocatingEngine
In-LineEngine
V-Engine
OppositePistonEngine
RadialEngine
RotaryEngine
WankelEngine
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Dr. Jayanta Kr. Mahato, Asst. Prof., Mechanical Engineering
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8. Classification of Automobile Engine
Dr. Jayanta Kr. Mahato, Asst. Prof., Mechanical Engineering
WorkingCycle
2StrokeCycleEngine
4StrokeCycleEngine
MethodofIgnition
SI(SparkIgnition)Engine
CI(CompressionIgnition)Engine
MethodofCooling
AirCooledEngine
WaterCooledEngine
FuelUsed
Gasoline(Petrol)Engine
DieselEngine
Gas(LNG,CNG,LPG)Engine
DualFuelEngine
HydrogenEngine
Hybrid
FuelCell

9. Classification of Automobile Engine
Dr. Jayanta Kr. Mahato, Asst. Prof., Mechanical Engineering
Application
Motorcycles:0.75–70kW,SI,2and4-stroke,air-cooled
Outboardmotor:0.75–50kW,SI,2-stroke,water-
cooled
Passengercars:15–200kW,SIandCI,4-stroke,water-
cooled
Lightcommercialvehicles:35–150kW,SIandCI,4-
stroke,watercooled
Heavycommercialvehicles:120–400kW,CI,4-stroke,
water-cooled
Locomotives:400–3000kW,CI,4-stroke,water-cooled
Ships:3500–22000kW,CI,2-and4-stroke,WC.
Airplanes:45–3000kW,SI,4-stroke,air-cooled
Stationaryengines:10–20000kW,CI,2-and4-stroke,
water-cooled

10. In-Line Engine
Dr. Jayanta Kr. Mahato, Asst. Prof., Mechanical Engineering
Cylindersaremountedinastraightline
orplanealongthecrankcase.
Types
1.In-line3Cylinders
2.In-line4Cylinders
3.In-line6Cylinders
4.In-line8Cylinders
Morethenumberofcylindermorethe
smootherandbalancedoftheengine.
Most ofthe high performance
automobilecarsusedIn-line4Cylinder
engine.
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11. In-Line Three Cylinder (I-3) Engine
Dr. Jayanta Kr. Mahato, Asst. Prof., Mechanical Engineering
Firing Order: 1 –3 –2
InI-3enginesaregenerallyemploy
acrankangleof120°.
Ithasperfectfirstandsecondorder
balanceonreciprocatingmass,buthas
anend-to-endrockingmotionbecause
thereisnosymmetry inthepiston
velocitiesaboutthemiddlepiston.
Theuseofabalanceshaftreduces
thisundesirableeffect.
Advantages
BetterFuelEfficiency
LowerCosts
BiggerInteriors
LowerFrictionalLosses
Disadvantages
LessResponsiveEngine
NotRefined

12. In-Line Four Cylinder (I-4) Engine
Dr. Jayanta Kr. Mahato, Asst. Prof., Mechanical Engineering
Firing Order: 1 –2 –4 -3
Another order: 1-3-4-2,
1-3-2-4 and 1-4-3-2
Morebalancedenginebecausethe
pistonsaremovinginpairs,andone
pairofpistonsisalwaysmovingupat
thesametimeastheotherpairis
movingdown.
Nonoverlappingpowerstroke:
Advantages
Usuallysmall,compactandlightweight
Equitablepowerdistribution
MoreResponsive
RefinedEngine
Disadvantages
Expensive
HighFuelConsumption

13. In-Line Six Cylinder (I-6) Engine
Dr. Jayanta Kr. Mahato, Asst. Prof., Mechanical Engineering
Firing Order: 1-5-3-6-2-4
Toattainperfectbalance,most
inline-sixenginesusea1-5-3-6-2-4
firingorder.
Largeinsize.MainlyusedinSports
Cars.BMWisstillusingI-6engine.
I-6engineissortofliketwoI-3
engines puttogether inarow,
mirroringeachother.
Advantages
SimpleDesign
LessVibration
UniqueEngineSound
Disadvantages
Large,AwkwardSize
HigherCenterofGravity
Two I-3 Engine

14. Working Principle of I.C. Engine
Amixtureoffuelwithcorrectamountofairisexplodedinan
enginecylinderwhichisclosedatoneend.
Asaresultofthisexplosion,heatisreleasedandthisheatcausesthe
pressureoftheburninggasestoincrease.
Thispressureforcesaclosefittingpistontomovedownthecylinder.
Themovementofpistonistransmittedtoacrankshaftbya
connectingrodsothatthecrankshaftrotatesandturnsa
flywheelconnectedtoit.
Intake/
Suctionstroke
Compression
stroke
Exhaust
stroke
Power
stroke

15. Poweristakenfromtherotatingcrankshafttodomechanicalwork.
Toobtaincontinuousrotationofthecrankshafttheexplosionhasto
berepeatedcontinuously.
Beforetheexplosiontotakeplace,theusedgasesareexpelledfrom
thecylinder,freshchargeoffuelandairareadmittedintothe
cylinderandthepistonmovedbacktoitsstartingposition.
Thesequencesofeventstakingplaceinanengineiscalledthe
workingcycleoftheengine.
Thesequenceofeventstakingplaceinsidetheengineareasfollows

16. Two Stroke Engine (Petrol Engine)
Dr. Jayanta Kr. Mahato, Asst. Prof., Mechanical Engineering
Thewholesequenceofeventsi.e.,
suction,compression, powerand
exhaust arecompleted intwo
strokesofthepistoni.e.one
revolutionofthecrankshaft.
1
st
Stroke:Upwardstrokeofthe
piston(Suction+Compression)
2
nd
Stroke:Downward stroke
(Power+Exhaust)
Two-strokeengines
donothavevalves.
Crankcase isfully
closedandairtight.
Fuelisnotfully
consumed.
Thermalefficiencyis
comparativelylow.

17. Four Stroke Engine (Diesel/Petrol Engine)
Dr. Jayanta Kr. Mahato, Asst. Prof., Mechanical Engineering
Thefourevents namely suction,
compression, powerandexhausttake
placeinsidetheenginecylinder.
Thefoureventsarecompletedinfour
strokesofthepiston(tworevolutionsof
thecrankshaft)
Thisengine hasgotvalvesfor
controllingtheinletofchargeandoutlet
ofexhaustgases.
Theopeningandclosingofthevalveis
controlledbycams,fittedoncamshaft.
Thecamshaftisdrivenbycrankshaft
withthehelpofsuitablegearsorchains.
FourStrokesinCIengineare:
1.Suctionstroke
2.Compressionstroke
3.Powerstrokeand
4.Exhauststroke
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18. FOUR STROKE CYCLE ENGINE ( DIESEL/ PETROL ENGINE)
Infourstrokecycleenginesthefoureventsnamelysuction,compression,power
andexhausttakeplaceinsidetheenginecylinder.
Thefoureventsarecompletedinfourstrokesofthepiston(tworevolutionsofthe
crankshaft).

19. FOUR STROKE CYCLE ENGINE ( DIESEL/ PETROL ENGINE)
Thisenginehasvalvesforcontrollingtheinletofchargeandoutletofexhaust
Theopeningandclosingofthevalveiscontrolledbycams,fittedoncamshaft.
Thecamshaftisdrivenbycrankshaftwiththehelp ofsuitablegearsorchains.
Thecamshaft runsathalfthespeedofthecrankshaft.

20. TWO STROKE CYCLE ENGINE (PETROL ENGINE)
Intwostrokecycleengines,thewholesequenceofeventsi.e.,suction,
compression,powerandexhaustarecompletedintwostrokesofthe
pistoni.e.onerevolutionofthecrankshaft.
Thereisnovalveinthistypeofengine.
Gasmovementtakesplacethroughholescalledportsinthecylinder.
Thecrankcaseoftheengineisairtightinwhichthecrankshaftrotates.

21. Upwardstrokeof thepiston(Suction+Compression)
Whenthepistonmoves upwarditcoverstwooftheports.
Thistrapsthechargeofair-fuelmixturedrawnalreadyintothecylinder.
Thepistoncompressesthechargeandalsouncoversthesuctionport.
Nowfreshmixtureisdrawnthroughthisportintothecrankcase.
Justbeforetheend ofthisstroke,themixtureinthecylinderisignited.
Thus,duringthisstrokebothsuctionandcompressioneventsarecompleted.

22. Downward stroke (Power + Exhaust)
Burningofthefuelrisesthetemperatureandpressureofthegases.
Whenthepistonmoves down,itclosesthesuctionport.
Furtherpistonuncoversfirsttheexhaustportandthenthetransferport.
Nowfreshchargeinthecrankcasemoves intothecylinderthroughthetransfer
port During the downward stroke of the piston power and exhaust events are
completed.

23. Comparison: Two Stroke and Four Stroke Engine
Dr. Jayanta Kr. Mahato, Asst. Prof., Mechanical Engineering

24. CI (Compression Ignition) Engine
CIenginehasnocarburetorandspark
plug,buthasafuelinjector.
Thisengineworkontheprincipleof
dieselcycle.
SimilartoSIengineCIenginealsohas
thefourstrokeinonecompleteburning
cycle.
FourStrokesinICengineare:
1.IntakeorSuctionstroke
2.Compressionstroke
3.Powerstrokeand
4.Exhauststroke

25. SI (Spark Ignition) Engine
Spark
Fuelandairaremixedtogetherinthe
intakesystem,inductedthroughthe
intakevalveintothecylinder,followed
bycompression.
Combustion isinitiatedtowardsthe
endofcompression strokeatthespark
plugbyanelectricdischarge.
Followinginflammation,aturbulent
flamedevelops,propagatesthroughthe
premixedair-fuelmixture.
FourStrokesinSIengineare:
1.IntakeorSuctionstroke
2.Compressionstroke
3.Ignitionstrokeand
4.Exhauststroke

26. Petrol Engine Vs. Diesel Engine
Dr. Jayanta Kr. Mahato, Asst. Prof., Mechanical Engineering

27. CONSTRUCTION OF AN IC ENGINE
I.C.engineconvertsthe reciprocatingmotionofpistonintorotarymotion
Thepistonwhichreciprocatinginthecylinderisveryclose fitinthe
cylinder.

28. CONSTRUCTION OF AN IC ENGINE
Ringsareinsertedinthecircumferentialgroovesofthepistontoprevent
leakageofgasesfromsidesofthepiston.

29. CONSTRUCTION OF AN IC ENGINE
Usuallyacylinderisboredinacylinderblockandagasket,madeof
coppersheetorasbestosisinsertedbetweenthecylinderandthecylinder
headtoavoidantleakage.
Thecombustionspaceisprovidedatthetopofthecylinderhead
wherecombustiontakesplace.

30. Theendoftheconnectingrod
connectingthepistoniscalled
smallend.
Apincalledgudgeonpinorwristpin
isprovidedforconnectingthepiston
andtheconnectingrodatthesmall
end.
Theotherendoftheconnectingrod
connectingthecrankshaftiscalledbig
end.
Whenpistonismovedupanddown,
themotionistransmittedtothecrank
shaftbytheconnectingrodandthe
crankshaftmakesrotarymotion.
CONSTRUCTION OF AN IC ENGINE

31. Thecrankshaftrotatesinmainbearingwhicharefittedthecrankcase.
Aflywheelisprovidedatoneendofthecrankshaftforsmoothingthe
uneven
torqueproducedbytheengine.
Thereisanoilsumpatthebottomoftheenginewhichcontainslubricating
oilforlubricatingdifferentpartsoftheengine.
CONSTRUCTION OF AN IC ENGINE