615914925-Construction-of-Automotive-Engine.pdf

Construction of engine

1. ENGINECONSTRUCTION

2. What is Engine?
➢Anengineisa
machinethatconverts
heat energy into
mechanicalenergy.The
heatfromafuel
producespowerwhich
movesthevehicle.

3. Construction of Engine
a.Stationary Parts.
b.Moving parts.

5. Main components of IC engines

6. Cylinder Numbering
Thecylindersinenginesarenumbered.Inmostengines,theyare
numberedinthesequenceinwhichtheconnectingrodsattachalongthe
crankshaft.Cylindernumber1isusuallythefarthestfromtheoutput
endofthecrankshaft.
Invtypeoropposedcylinderengines,thecylindersmaybenumbered
insequenceofeachbank

8. Thefiringorderofaninternalcombustionengineisthesequenceof
ignitionforthecylinders.Inaspark-ignition(e.g.gasoline/petrol)
engine,thefiringordercorrespondstotheorderinwhichthespark
plugsareoperated.Firingorderaffectsthevibration,sound,and
evennessofpoweroutputfromtheengine
The firing order

9. Firingorderisthesequenceinwhichthecylindersdeliverstheir
powerstrokes.Itisdesignedintotheengine.Thecrankpinand
camshaftarrangementdeterminethefiringorder.Twofiringorder
forinlinefourcylinderenginesare:1-3-4-2and1-2-4-3.

10. •IN LINE 6 cylinder engines use 1-5-3-6-2-4
•Ford V-6 engines have fired 1-4-2-5-3-6 and 1-4-2-3-5-6.
•GM motor’s V-8 engine 1-8-4-3-6-5-7-2
•Ford V-8 engines use 1-5-4-2-6-3-7-8 and 1-3-7-2-6-5-4-8

11. V-8 engines by GM Motors
In line 6 cylinder engine

13. ➢Cylinder block.
➢Crankcase.
➢Cylinder head.
➢Gasket.
➢Exhaust and intake manifold etc.
Stationary Parts

14. Cylinder block
Thecylinderblockisthe
foundationoftheengine.The
cylinderblockprovidesthe
smoothcylindricalboresinwhich
thepistonmovestoandfroin
ordertodeveloppower.
Mostblocksarecastfromgrey
castironorironmixedwithother
metalssuchasnickel&
chromiumandaluminumalloy

15. Aluminumisusedwheneverweightisaconsideration.Itis
notaspracticaltouseforthefollowingreasons:
a.Aluminumismoreexpensivethancastiron.
b.Aluminumisnotasstrongascastiron.
c. Due to the softness, it cannot be used on
any surface of the block that is subjected to wear.
d.Aluminumhasamuchhigherexpansionrate
thancastironwhenheated.Thiscreatesproblems
withmaintainingtolerances.
Cylinder Block

16. It contains following:
Cylinders.
Water jacket.
Camshaft bearing.
Ports and guides.
ItsupportsthefollowingComps:
Crankshaft.
Camshaft.
Clutchhousing.
Crankcase.
Cylinder block

17. Cylinder
Itisaholeinsidethe
cylinderblockwhich
contains theliner
piston.

18. Cylinder Sleeve/Liner
Linerisusedinsidethe
cylinder to prevent
permanentwearofcylinder
bore.Cylinderlinersare
sleevesthatareeithercast
intotheblockorinstalled
later.

19. Threekindsoflinersarecommonlyusedas
follows:
a. DryLiner. Arepressedintoafull
cylinder.Theytouchthecylinderborealongtheir
fulllength.
b. WetLiner.Theytouchthecylinderblock
onlyatthetopandbottom.Therestoftheliner
touchesonlycoolant.WetLinersinteractwith
EnginecoolantdirectlytoprotectthePiston.Wet
Linershavebetterheatdissipationandcooling
thanDry-typeCylinderLiner
Cylinder Sleeve/Liner

21. c.Finnedliners:
Finnedlinersareusedinair-cooledengines.The
finsofthelinerareexposedtoopenair.Whenthe
airpassesthroughthefinsitincreasestheheat
transferrateandcoolstheenginebetter.
Thefincooledenginescanalsohaveawetliner
tofurtherincreasetheheattransferrate.These
linersaregenerallyusedinengineswherethe
engineisexposedtoopenair.

22. Itiscastintegralwiththe
cylinderblockorboltedtoit,
isusedtomountthemain-
enginebearings,andthus
supportthecrankshaft.It
hastwoparts
a.UpperCrankcase
b.LowerCrankcase.
Crankcase

23. Upper Crankcase
❑Itisanintegralpartof
thecylinderblockwhich
supportthecrankshaft.
❑Itistheextendedportion
ofthecylinderblocktothe
shortdistancebelowthe
crankshaft.

24. Lower Crankcase
►Itisusedforholdingtheengine
oil.
►Itisboltedatthebottomof
the
uppercrankcase.
►Adrainplugisprovidedwith
it
todrainoutthelubricatingoil.

25. Cylinder Head
Adetachableunitofanengine
boltedtothetopofthecylinder
block.Itcontains:
▪Waterjacket.
▪Valve,valveseats,valveguide,
spring.
▪Rockerarmandrockerarm
shaft.
▪Injectororsparkplug,pre-
combustionchamber.
▪Intakeandexhaustmanifold.

26. Cylinder Head

27. Gasket
Ahead-gasketsealsthe
jointbetweenthecylinder
headandthecylinderblock.
Headgasketinstallation
becomesextremelyimportant
insealingbetweenan
aluminumheadandacast
ironblock.

28. ►Acombustionchamberisthe
partofanengineinwhichfuelis
burned.
►Spacebetweencylinderand
cylinderheadwhenpistonatTDC.
► Sparkplugforpetrolengine
andinjectorfordieselenginelocat
thecombustionchamber.
Combustion Chamber

29. Pre-Combustion Chamber
Asmallcombustionchamberwhere
combustionbegin.Aprimaryintakevalve
opensintothemaincombustionchamber.
Anauxiliaryintakevalveopensintothepre-
combustionchamber.Boththeintake
valvesopenatthesametime.The
auxiliaryintakevalveadmitsarichmixture.
Theprimaryintakevalveadmitsalean
mixture.Thesparkpluginthepre-
combustionchamberignitestherich
mixture.Itstreamsoutandmixeswiththe
leanmixture.Thiscauseshighturbulence
andgoodcombustion.

30. Intake Manifold
IntakeManifoldsare
basicallypipesusedin
automobilefuelsupply
systemthatareusedfor
carryinganddistributingfuel
tointernalcombustion
enginecylinder.
➢In case of petrol engine, cylinder receive the air
fuel mixture through intake manifold during suction.

31. ➢Incaseofdieselenginecylinderreceiveair
throughtheintakemanifoldduringsuction
stroke.
➢IntakeManifoldisnormallymadeofCastIron.
Intake Manifold

32. Exhaust Manifold
Exhaustmanifoldconnects
allthe enginecylinder
togetherwiththeexhaust
system.
Thewasteproductsof
combustionareexpelledtothe
atmospherebytheexhaust
manifold.

33. ▪Itmustbefittedoppositetothefuelsupto
avoidthefirerisk.
▪Exhaustmanifoldshouldhavethesmoothwall
andwithoutsharpbendtoreducetheback
pressure.
▪Mufflerisusedtoreducetheprandnoise.
▪Itisnormallymadeofcastiron.
Exhaust Manifold

34. Moving Parts
❖Crankshaft.
❖Connecting rod.
❖Piston.
❖Piston Rings.
❖Piston Pin.
❖Cam and Camshaft.
❖Valve.
❖Fly Wheel etc.

35. Crank Shaft
Itisconsideredasthebackbone
ofanenginewhosefunctionis
tocovertthereciprocating
motionofthepistonintorotary
motionwiththehelpof
connectingrod.
Crankshaftcontainsoneor
moreeccentricportionscalled
cranks.Crankshaftsaremade
fromforgedorcaststeel.

36. Crank Shaft
 Itmustbestrongenoughtotakethe
downwardthrustsofthepistonsduringthepower
strokeswithoutexcessivedistortion.
 Itmustbewellbalancedtoeliminateundue
vibrationresultingfromtheweightoftheoffset
cranks.

37. Components of Crankshaft
a.Main bearing journal.
b.Crank pin.
c.Crank arm.
d.Counter weight.
e.Fly wheel flange.

38. Crankshaft Vibration
Crankshaftisverypronetovibrationbecauseofits
shapeandheavyweight.
Thefollowingarethreebasicareasthatareof
concernwhenconsideringvibrationincrankshaft
design:
a.Vibration due to imbalance.
b.Vibration due to deflection.
c.Torsion al Vibration.

39. Balancing of Crankshaft
a.Vibration Damper. Vibration Damper is used
at the end of the crankshaft opposite to the output
end to absorbed torsion al vibration.
b.Crankshaft Bearings. Crankshaft bearing is
named as crankshaft main bearing which is used to
support the crankshaft for its smooth rotation.
c.Connecting rod bearings. Connecting rod
bearing fits into the connecting rod.

40. d.Thrust Bearing.Limits crankshaft end play.
The thrust bearing is one of the main bearings that
has flanges on its two sides. This limits the forward
and rearward movement of the crankshaft.
Balancing of Crankshaft

41. Crank Shaft

42. Flywheel
Itisheavybigwheelandboltedto
therearendofthecrankshaft
betweentheengineandthe
transmission.Theflywheelusually
madeofcastiron.
❑Flywheelstoresenergyfromthe
powerstrokesandsmoothlydeliversit
tothedrivetrainofthevehandto
avoidtheroughrunningoftheengine.

43. ❑Duetoitsinertia,itresistanychangeofspeed
ordirectionofthemotion.
❑Ithelpstostarttheengine.
❑Italsoservesasadrivingmemberofthe
engineclutch.
Flywheel

44. PISTON
Thepistonisacylindrical
plugthatmovesupand
downintheenginecylinder
andreceivestheenergyor
forceofcombustionand
transmitsthatenergytothe
crankshaftthroughthe
connectingrod.Thepistons
aregenerallymadeof
aluminumalloys.

45. RequirementofPiston
 Duringthepowerstroke,thepistonis
subjectedtopressureonitsheadupto18000Nso
itmustbestrongtotakethesestress.
 Thepistonheadissubjectedtotempwellover
2204
0
Csoitmustbewithstandthesetemp.

46. Piston Ring
Thesearecircularringsand
madeofspecialsteelalloy/cast
iron.Thepistonringsarefittedin
thepistonringgrooves.The
pistonringsareofthefollowing
types:
a.CompressionRing.Seal
compressionandcombustion
pressuresinthecombustion
chamber.Compressionringsare
usuallymadeofcastiron.

47. b.OilControlRing.
Scrapsoilfromthe
cylinderwallandpreventthe
oilfromgettingintothe
combustionchamber.
Piston Ring

48. Ringsservethreeimportant
Purposes:
a.Provideasealbetweenthepistonand
cylinderwall.
b.Keepthelubricatingoilfrombypassingthe
pistonandgettingintocombustionchamberfrom
thecrankcase.
c.Provideasolidbridgetoconducttheheat
frompistontothecylinderwall.

50. CompressionRings:
Thecompressionringisthetopmostringinthepistonattachedtoits
outsidediameter.Themainfunctionofthecompressionringistoseal
thegapbetweenthepistonandthecylinderwalls.
Sealingthisgapwiththeouterdiameterofthepistonandthecylinder
wallsensurethattheair-fuelmixtureinthecombustionenginedoesnot
movedowntothecrankcaseandcauseslowcompressionandpower.
Inaddition,thissealingalsomakessurethattheengineoilinthe
crankcase,usedforlubrication,doesnotmoveupintothecombustion
chamberandgetsburnt.

51. OilControl/ScrapperRings
Theoilcontrolringscontroltheamountoflubricatingoilpassingupor
downthecylinderwalls.Theseringsarealsousedtospreadtheoil
evenlyaroundthecircumferenceoftheliner.
Theoilissplashedontothecylinderwalls.Theseringsarealsocalled
scraperringsastheyscraptheoiloffthecylinderwallsandsendback
tothecrankcase.
Theseringsdonotallowtheoiltopassfromthespacebetweentheface
oftheringandthecylinder

52. MAIN COMPONENTS OF
PISTON
❖ Piston head.
❖ Piston Pin.
❖ Lands.
❖ Ring grooves.
❖ Piston pin hole.
❖ Piston skirt.

54. Main Purpose of the Piston
❖To compress the air fuel mixture.
❖Transmitthecombustionpressuretothe
crankshaftthroughconnectingrod.
❖Forceoutthebruntgasesduringexhaust
stroke.
❖Producethevacuuminthecylindertodrawthe
airfuelmixtureduringsuctionstroke.

55. ExpansionControlinPiston
Tocontrolexpansion,pistonmaybedesignedwiththe
followingfeatures:
▪UseofverticalorTslotonthenonthrustsideoftheskirt.
▪Taperthepistonslightlyfrombottomtotopi.eheadis
smallerthantheskirt.
▪Camgroundpiston.
▪Usingsteelbracesorstrutscastintothepiston.
▪Wirewoundpiston.
▪Bi-metalpiston.

56. PistonClearance
PistonClearanceisthedistancebetweenthe
cylinderwallandtheskirt.PistonClearanceis
usuallybetween.025and0.12mm.
Ifpistonclearanceistoosmall,thereislossof
powerfromhigherfrictionandseverewear.
Excessivepistonclearancecausespistonslap.This
noiseiscausedbythepistonshiftingfromoneside
ofthecylindertotheother,whenthepowerstroke
begins.

57. Pistonslapisgenerallycausedwhenthecoldrunningclearance(piston-to-
wallclearance)islargeenoughthatwhenthepistonrocksfromsidetoside
intheboreit“slaps”thesideofthecylinderandcausesnoise.
Pistonslapisthemajorforcecontributingtonoiselevelsincombustion
engines.Thistypeofnoisedependsuponanumberoffactorssuchasthe
piston-linergap,typeoflubricantused,numberofpistonpinsaswellas
geometryofthepiston
Piston Slap

58. CAMGROUNDPISTON
Manypistonareslightly
ovaloregginshape,it
willabletofitthecylinder
betterthroughoutits
operationaltempsrange.
A pistonofthis
configurationiscalled
Camgroundpiston.

59. Camgroundpistonsaremachinedsothattheir
diameterissmallerparalleltothepistonpinaxis
thanitisperpendiculartoit.
Whenthepistoniscold,ithasnormalclearanceonly
intheareas90
0
fromthepinhole.
Asitwarmsup.Itwillexpandacrossitssmaller
diameteratmuchhigherratethanitslarger
diameter.Thiswilltendtomakethepistonroundat
operatingtemp.
CAMGROUNDPISTON

61. PistonPinOffset
Toeliminatetheslappingtendency
ofpistons,thepiston–pinholesare
offsettowardsthemajorthrustface.
Thisisthepistonfacethatbearmost
heavilyonthecylinderwallduringthe
powerstroke.
Theaxiallyoffsetshouldpre-shift
thetimeatwhichthepistonchanges
sidesbetweencompressionand
powerstrokeintotheareaoflower
pressure.Thus,noiseandwear
remainlow.

62. 1.Whenthepinisinthecenterofthepiston,nowthatthepiston
reachesTDCorBDC.Inthisposition,therodmovesstraightupand
down,placingaheavyloadontherod.Thecrankhastomovepast
TDCorBDCtomakethepistonmoveagain.Thisrodsprovidesboth
alotofpowerandRPMfromtheengine.
2.Withanoffsetpin,thepistonwristpinisslightlyoffsettooneside
ofthepistonsotheroddoesn’tmovestraightupanddownwhenthe
pistonisatTDCorBDC.Thisallowsthecranktorotatewithless
resistancegivingtheenginemorepowerandspeed.

64.  Ifthepiniscentered,theminorthrustfaceremainsin
contactwiththecylinderwalluntiltheendofthe
compressionstroke.Then,asthepowerstrokestarts,the
rodanglechangesfromlefttoright.Thiscausesthepiston
toshiftsuddenlytotheleft.Ifthereistoomuchclearance,
thepistonmovementcausespistonslap.
 Ifthepistonpinisoffsetslightlytowardthemajor
thrustface,combustionprcausesthepistontotiltasitnear
TDC.Thelowerendofthemajorthrustfacemakesfirst
contactwiththecylinderwall.Then,afterTDCthepistontilts.
Fullcontactofthemajorthrustfaceoccurs.Thisminimize
pistonslap.
PistonPinOffset

65. Connecting Rod
Connectingrodisusedtotransmit
themotionfromthepistontothe
crankshaft.
Theconnectingrodisusuallyof
I-section.

67. ❖Valveadmitsairfuel
mixtureintothecylinderduring
intakestrokeanddischarge
bruntgasesduringexhaust
stroke.
❖ Itremainsclosedduring
compressionandpowerstroke
tosealthecombustionchamber
tightly.
Valves

69. Valveareusuallymadeofspecialalloysteel.Cr-Ni-Mosteelusedfor
inletvalve.ExhaustvalvesrunathightemperaturemadeofSi-Cralloy
steelorAustenitic.AusteniticisbetterthatSi-Crsteelasfarasimpact
value,hothardness,andresistancetooxidationandcorrosionare
concerned.ItcontainshighpercentageofCrandNi

70. ❖Intakevalveisusuallylargerthantheexhaustvalve.The
reasonisthatwhenintakevalveisopen,theonlyforce
movingair-fuelmixtureintothecylinderisatmospheric
pressure.
❖Asmallerexhaustvalveprovidesenoughspaceforthehigh
pressureexhaustgasestogetoutofthecylinder.Some
enginehavethreevalvespercylinder,Twoareintakeand
oneisanexhaustvalve.
Why inlet valve is greater than the exhaust valve?

71. Intakevalverunsrelativelycool.Itpassesonlytheairfuel
mixture.Exhaustvalvepassestheveryhotexhaustgases.The
exhaustvalvemaybecomeredhotinoperationwithtemperature
upto871degC.Thevalvestemiscoolest.Theareabetweenthe
stemandthefaceisthehottest.Thevalvestemtransfersheatto
thevalveguidetohelpcoolthestem.Thevalvefacetransfers
heattothevalveseateachtimethevalveclose.Thishelpscool
theface
Valve Cooling

73. Thevalveseatandstemarecooledbytheenginecoolingsystem.
Coolantcirculatesthroughthewaterjacketsorcoolantpassages
aroundthevalveseatandvalveguideinthecylinderhead.
Someheadhasnozzlesthatforcecoolantaroundthevalveseats.
Othersusedeflectorsinthewaterjacketstoimprovecoolant
circulationaroundtheseats.
Tohelpcoolexhaustvalve.somehavehollowstemspartlyfilledwith
themetalsodium.Whenengineisrunning,thesodiumisaliquidand
circulationofsodiumtakesheatfromthevalveheadandcarriesitup
tothecoolerstem.Asodiumfilledexhaustvalverunsabout93.3deg
Ccoolerthananonfilledvalve.
Valve Cooling

75. Cams and Camshaft

76. Cams and Camshaft

77. Cams and Camshaft
❖Itisusedforchangingrotarymotionintolinearmotion.
❖Itcontrolstheopeningandclosingoftheintakeand
exhaustvalveasrequired.
❖Itisalsousedtooperatethefuelpump,oilpumpetc.
❖Therearetwocamsforeachcylinder,oneforintake
andanotherforexhaustvalve.
❖Fortwocompleterotationofthecrankshaft,camshaft
rotatesonce.

79. Ifinsufficientvalvelashissetwhentheengineiscoldthe
valveswillnotproperlyclosewhentheenginewarmsup.If
toomuchlashisprovided(additionalclearance)theneven
aftertheenginewarmsuptherewillbesomeclearancewhich
willresultinlostmotion.
Tappetclearanceisaspacebetweenthetopofthevalve
stemandtherockerarm.Itspurposeistoallowforsome
mechanicalexpansionandlengtheningofthevalvestemand
pushrodsastheenginewarmsup.Thisclearanceisalso
calledvalvelash.
Tappet clearance

80. Tappet clearance

81. Lostmotionmeanthatasthecamtriestoopenthevalvethe
pushrodandrockerarmmovestofirsttakeuptheclearance
beforetouchingthevalvetoopenthevalve.Theresultislate
openingofthevalve.
Excesslashcanbeheardinanidlingengineasaseriesof
tickingsoundsthatshoulddisappearastheenginewarmsup.
Overtimemechanicalwearcausesanincreaseinlash
usuallywiththesymptomatictickingsoundintheengine(one
ormorevalvescanproducethesound).Thefixwasto
removethevalvecoverandmechanicallyadjustthelashwith
anadjustmentscrewontherockerarm
Tappet clearance

82. Modernenginesnowoperatewithzerolashthroughtheuse
ofhydrauliclifters.Liftersuseengineoilpressureto
automaticallyremovethemechanicalclearanceofthevalve
operatingcomponents.
Intakeissetto.024"andexhaustissetto.030",
Tappet clearance