UNIT-1-VEHICLE STRUCTURE AND ENGINES.ppt

Types of automobiles, vehicle construction and different layouts, chassis, frame and body, resistances to vehicle aerodynamics (various resistances and moments involved), IC engines-components functions and materials, variable valve timing (VVT).

1. KONGUNADU COLLEGE OF ENGINEERING AND TECHNOLOGY
(AUTONOMOUS)
NAMAKKAL -TRICHYMAIN ROAD, THOTTIAM, TRICHY
DEPARTMENT OF MECHANICAL ENGINEERING
20ME603PE -AUTOMOBILE ENGINEERING
SIXTH SEMESTER
PRESENTED BY
M.DINESHKUMAR,
ASSISTANT PROFESSOR,
DEPARTMENT OF MECHANICAL ENGINEERING,
KONGUNADU COLLEGE OF ENGINEERING AND TECHNOLOGY.

2. UNIT I
VEHICLE STRUCTURE
AND ENGINES

3. TYPES OF AUTOMOBILES
(i)with respect to the purpose
(a) Passenger vehicles. Ex. Car, bus, jeep, scooter, mopeds
and motor cycles
(b) Goods carriers: ex. Trucks and lorries
(ii) weight of the vehicles:
-Heavy weight vehicle-buses, trucks and trailers
-Light weight vehicles -cars, jeeps
-Medium weigh vehicles –minibus and station wagon
(iii) With respect to the fuel:
-Petrol vehicles –scooters, cars motors cycles
-Diesel vehicles -Buses , trucks
Gas vehicles –Coal gas, LPG, CNG vehicles
Electric vehicle –Heavy cranes, battery truck, cars and fork lifts
Solar vehicles.

4. •(iv) with respect to capacity:
•Heavy transport vehicles –Bus lorries, trucks, tractors
•Light transport vehicles _ Car, scooter, mopeds, motor
cycles, jeeps
•(v) with respect to number of wheels:
•Two wheelers –Scooters, mopeds
•Four wheelers –car, jeep, buses, truckes
•Three wheelers –Auto, tempos
•Six wheelers -heavy trucks
•(vi) With respect to side of driver seat
•-Left hand drive-American, European and UAE
•-Right hand drive –Indian vehicles

5. A bullock cart consists of the following main parts.
i) Frame.
ii) Wheels and axle.
iii) Yoke.
iv) Body or superstructure and platform
These parts can be divided into the following two main
portions .
(i) Machine portion.
(ii) Carriage portion.

6. LAYOUT OF A CAR

7. Four-wheel drive

9. CHASSIS
Toconstructanyautomobile,chassisis
thebasicrequirement.
ChassisisaFrenchtermanditwas
initiallyusedtodenotetheframeor
mainstructureofavehicle.
Itisextensivelyusedincomplexvehicles
exceptthebody.Avehiclewithoutbody
iscalledchassis.

10. Basic Construction of Chassis
Chassis is the back bone of the vehicle.
The components of the vehicle such as power
plants, transmission system, axles, wheels and
tyres, suspension, controlling systems such as
braking, steering etc., and also electrical
system parts are mounted on the chassis
frame.
It is the main mounting of all components
including the body. So, it is also called carrying
unit.

11. MAIN COMPONENTS OF CHASSIS
•1. Frame.
•2. Front suspension.
•3. Steering mechanism.
•4. Engine, clutch and gear
box.
•5. Radiator.
•6. Propeller shaft.
•7. Wheels.
•8. Rear and front springs
and shock absorber.
•9. Differential unit.
•10. Universal joint.
•11. Brakes and braking
systems.
•12. Storage battery.
•13. Fuel tank.
•14. Electrical systems.
•15. Silencer.

12. •Classification of chassis:
According to the fitting of engine:
-Full-forward –ex cars, mahindra jeeps
-semi-forward –Tata Se series of vehicles
-Bus chassis –Busses and trucks
-Engine at back-Volkswagen cars, Leyland bus of
England.
-Engine at centre-Royal tiger world master buses of
Delhi transport.
According to the number of wheels fitted in the vehicles
and number of driving wheels:

13. CHARACTERISTICS OF A GOOD CHASSIS:
Fast pickup, strength, safety, durability,
dependability, ease of control, quietness, speed,
power accessibility, economy of operation low
centreof gravity stability load clearance, braking
ability, simplicity of lubrication.
Chassis Components: Frame, suspension
systems, steering system, braking system,
internal combustion engine, clutch, gear box ,
propeller shaft, universal joint ,differential,
springs

18. VEHICLE AERODYNAMICS:
Resistance to vehicle motion:
1.Air resistance or aerodynamic drag:
A vehicle travelling at a particular speed in air encounters a
force resisting its motion.
A) Size of the vehicle (b) shape of the vehicle
C) Speed of the vehicle (d) wind velocity
2. Gradient resistance: component of the vehicle weight
which is parallel to the plane of the road.
3. Rolling resistance: of tyreson hard surfaces is due to
hysteresis in the tyrematerial.
Tyrerolling resistance
Road rolling resistance
Resistance due to tyreslip angle
Resistance due to bearing friction and residual braking

19. Aerodynamics of Automobile body:
Various aerodynamic force acting on the vehicle.
(i) Drag force (Fx): Force of air drag is acting in the
direction of vehicle motion with the wind acting along
the longitudinal direction axis.
The main causes (i) shape drag (ii)Skin friction drag.
(ii) Lift force(Fz):Aerodynamics lift force is the vertical
component of the resultant force caused by the pressure
distribution on the body.
(iii) Cross wind force (Fy):It is acting in the lateral direction
on the side of the vehicle.
These forces acting at the centre of pressure instead of
centre of gravity & various cause of moments

20. •(i)Pitching moment (My): is caused by the drag
force Fx or lift force Fz about Y axis. This
moment makes the rear wheels lift off from the
ground and further it reduces the available
traction.
•(ii) Yawing moment(Mz): Cross wind force Fy
about Z axis
•(iii) Rolling moment(Mx): Cross wind force Fy
about X axis
•

23. CYLINDER BLOCK

24. CYLINDER BLOCK
Itisthemainbodyofanenginewhichcontains
cylinders.
Thepistonreciprocatesinsidethecylinderto
developpower.Thecylindersareaccurately
finishedtoaccommodatepistons.
Thecylinderblockalsohousescrank,
crankshaft,pistonandotherengineparts.
Duringcombustion,highpressureand
temperaturewillbedevelopedinsidethecylinder.
Therefore,itshouldbemadeofamaterialwhich
canresisthightemperatureandpressure.
Itismadeofgreycastironoraluminiumwith
steelsleeves.

25. CYLINDER HEAD
•Thecylinderheadisboltedatthetopofthe
cylinderblock.
•Ithousestheinletandexhaustvalvesthrough
whichthechargeistakeninsidethecylinder
andburntgasesareexhaustedtothe
atmospherefromthecylinder.
•Italsocontainsasparkplugholeorinjector
holeandcoolingwaterjacket.
•Thematerialsusedforcylinderheadsarecast
iron,aluminiumalloyetc.

26. CRANKCASE
•Itmaybecastintegrallywiththecylinder
block.Sometimes,itisseparatelycast
andboltedtothecylinderblock.
•Itsupportscrankshaftandcamshaftwith
thehelpofbearings.Sometimes,the
bottomofcrankcasemaybeusedasoil
sump.
•Itismadeofcastiron,aluminiumalloys
oralloysteels.

27. OIL SUMP OR OIL PAN
•Oil sump is fitted at the bottom of
crankcase by using a gasket.
•It contains lubricating oil.
•A drain plug is provided at the
bottom of the oil sump to drain out
the oil when needed.
•It is made of pressed steel sheet.

29. CYLINDER LINERS
Insidethecylinder,thepistonconstantly
movesupanddownwhichcauseswearin
cylinders.
Whenthecylinderdiameterisincreased
beyondacertainlimit,theentirecylinder
blockshouldbediscardedanditiscostly.
Toavoidcylinderwear,aseparateliner
whichisintheformofthesleeveisinserted
intothecylinderbore.Hence,theweartakes
placeinthelineronlywhichcanbereplaced
easilywhenwornout.

30. 1. Wet liner:
The liners are surrounded by cooling water .
It provides a wear resisting surface for the
piston to reciprocate.
It also acts as a seal for the water jacket.
2. Dry liner:
•Dry liners have metal-to-metal contact with
the cylinder block.
•They are not directly in contact with cooling
water. Liner material should withstand
abrasive wear and corrosive wear.
•Chromium plated mild steel tubes are used as
liners.

31. Piston
Thepistonismadeofcastiron,aluminiumalloy,
chrome-nickelalloy,nickel-ironalloyandcaststeel.
Theyaremanufacturedbycastingorforgingmethod.

32. Piston
Itisacylindricalshapedmasswhichreciprocatesinsidethe
cylinder.
Thepistonservesthefollowingpurposes.
Itactsasamovablegas-tightsealtokeepgasesinsidethe
cylinder.
Ittransmitstheforceofexplosioninthecylindertothe
crankshaftthroughconnectingrod.
Thetopofthepistoniscalledcrownandsidesarecalled
skirt.
Ithasgroovestoholdpistonringsandoilring.Itis
openedatthebottomendandclosedatthetop.
Sometimes,Tslotsareprovidedintheskirttoallow
expansion

33. CONNECTING ROD

35. CONNECTING ROD
Itisusedtoconnectthepistonand
crankshaftwiththehelpofbearings.
Itisusuallysteelforgingofcircular,
rectangular,I,TorHcross-sections.
Itssmallendisconnectedtothepiston
bythepistonpinanditsbigendis
connectedtothecrankbythecrankpin.
Ithasapassageforthetransferof
lubricatingoilfrombigendbearingto
smallendbearing.

36. Connectingrodmustwithstandheavythrust.
So,itmusthavegreatstrengthandrigidity
Theyaregenerallymadeofplaincarbonsteel,
aluminiumalloyandnickelalloysteels.

37. GUDGEON PIN OR PISTON PIN
The gudgeonpin or piston pin of the IC engine
connects the piston to the connecting rod
It provides a bearing for the connecting rod to
pivot upon as the piston moves.
As the piston pins carry high loads imposed
upon them due to gas pressure on the piston,
they are made of steel alloyed with 3-4% of
nickel to increase toughness and then case-
hardened to obtain wear resistance surface.

38. PISTON RINGS
Theyareusedtomaintainair-tight
sealingbetweenpistonandcylinderto
preventgasleakages.
Pistonringsarefittedintogrooveswhich
areprovidedforthematthetopportionof
thepistonskirt.
Twotypesofpistonringsareusedina
piston

40. (a) Compression rings:
Theseringsprovideaneffectivesealforhigh-pressure
gasesinsidethecylinder.
Eachpistonisprovidedwithatleasttwocompression
rings
(b) Oil rings:
These rings wipe off the excess oil from cylinder walls.
It also returns excess oil to the oil sump through slots
provided in rings.
The materials used for piston rings are cast iron, alloy
cast iron containing silicon and manganese, alloy steels
etc.
Piston rings are generally coated with chromium or
cadmium.

42. CRANKSHAFT
Thecrankshaftisusedtoconvertthereciprocating
motionofthepistonintorotarymotion.
Thebigendoftheconnectingrodisconnectedtothe
crankshaft.
Itcanbeasinglecranktypeforsinglecylinder
enginesandamultiplecranktypeformulti-cylinder
engines.
Thecrankshaftisheldinpositionbymainbearings.
Thereareminimumtwobearingsprovidedtosupport
thecrankshaft.

43. Theflywheelismountedattherearendofthe
crankshaft.
Thematerialofthecrankshaftshouldbe
strongenoughtoresistheavyimpactforceof
thepiston.
Theyaremadefromahotbilletsteel,carbon
steel,nickel-chromiumandotherheat-treated
alloysteels.

44. FLYWHEEL
Theflywheelisheavyandperfectly
balancedwheelusuallyconnectedtothe
rearendofthecrankshaft.
Flywheelservesasanenergyreservoir.
Itstoresenergyduringpowerstrokeand
releasesenergyduringotherstrokes.
Thus,itgivesaconstantoutputtorque.
Itisusuallymadeofcastironorcast
steel.

46. CAMSHAFT
Itisusedtoconverttherotarymotionofthecamshaftinto
linearmotionofthefollowerorlifter.
Thus,itoperatestheinletandexhaustvalvesthrough
rockerarms.
Ithasasmanycamsasthenumberofvalvesinanengine.
Anadditionalcamisalsoprovidedtodrivethefuelpump.
Thecamshaftrotatesinsidetheplainbearings.
Itisdrivenbycrankshaftthroughchainorgeartrain.Itis
rotatedathalfofthespeedofthecrankshaft.
Thecamshaftisusuallymadeofchilledcastironandbillet
steel;howeverforgedsteel,greycastironornickelsteel
maybeuseddependingupontheapplication

47. SPARK PLUG
Thefunctionofthesparkplugistoignite
theair-fuelmixtureaftercompletingthe
compressionstrokeinthepetrolengine.
Itisusuallymountedinthecylinderhead.
Itisonlyusedinpetrolengines.

48. VALVES
Valvesareusedforclosingandopeningthe
passageofacylinder.
Therearetwovalvesinanenginecylinder
suchasinletandexhaustvalves.
Afreshair-fuelmixtureorairaloneentersinto
thecylinderthroughtheinletvalve.
Exhaustgasesareforcedoutthroughthe
exhaustvalves.
Valvesareoperatedbycamandrockerarm
mechanisms

50. •Therearethreetypesofvalvessuchassleeve
valve,rotaryvalveandpoppetvalve.
•Thepoppetvalve(alsocalledmushroom
valve)valvesaremostcommonlyused.Figure
showsapoppetvalve.
•Normally,thisvalvecontainsheadorpoppet
(angularfaceground30°to45°),face,stem
andspringretainerlockgroove.
•Theheadoftheinletvalveisbiggerthanthe
headoftheexhaustvalve.
•Theinletvalveismadeofplainnickel,nickel-
chromeorchrome-molybdenum

51. VALVE MECHANISMS
The valves are actuated by cams mounted on a
cam shaft. The different types of valve operating
mechanisms are as follows.
(a) side valve mechanism
(b) overhead valve mechanism
(c) overhead inlet and side exhaust
valve mechanisms.

53. SIDE VALVE MECHANISM
•Thecammountedonthecamshaftoperatesthe
valvetappetduringitsrotation.
•Thevalvetappetispushedup.
•Thevalvetappetpushesthevalvefromits
sheetagainstthespringforce.
•Thus,thevalveisopened.
•Whenthecamisnotinaction,thevalve
returnstoitsseatbythevalvespringand
springretainer.

55. OVERHEAD VALVE MECHANISM
•Here,thevalvesarelocatedinthecylinder
head.Whenthecamrotates,thevalvelifter
pushesthepushrodupwards.
•Thepushrodmovestherockerarm.
•Sincetherockerarmispivotedatitscentre,it
pushesthevalveoffitsseatagainstthespring
force.
•Thus,thevalveisopened.Whenthecamis
notinaction,thevalvereturnstoitsseatby
thevalvespringandspringretainer.

56. Overhead inlet and side
exhaust valve mechanism
•Inthissystem,inletvalveislocatedinthe
cylinderheadwhereastheexhaustvalve
islocatedinthecylinderblock.
•Theinletvalveisactuatedbyoverhead
valvemechanism.
•Theexhaustvalveisactuatedbyaside
valvemechanism.

57. LUBRICATION PUMP
The lubricating oil pump is used to pressurize
the oil and circulate it to different engine parts.
It is generally driven by a spiral or warm gear on
the cam shaft. The different types of oil pumps
in use are
1. Gear pump.
2. Eccentric rotor pump.
3. Eccentric vane pump.
4. Plunger pump.

58. Variable valve timing for four-
cylinder engine

59. VARIABLE VALVE TIMING
(VVT)
Fixedvalvetiminghasbeenastandardfeature
ofallenginesuntilrelativelyrecenttimes.
Thevalvesopenedandclosedatafixedperiod
inrelationtocrankshaftrotationatallengine
speedsandloads.
Whentheinletandexhaustvalvetimingis
fixed,thetimingisnotsuitableforallengine
operatingspeedsandloads.So,thereis
increaseinuseofmechanismstoprovide
variablevalvetiming(VVT).

60. •Thevariablevalvetimingsystemsalterthevalve
timingtosuitenginespeedandloadconditions.
•Althoughsystemsarepurelymechanicalbased
systems,mostmodernsystemsmakeuseofthe
electronicenginemanagementsystemtoregulatethe
mechanicalactuationofchangestothevalvetiming.
•Practically,VVTsystemsareusedtoenablegood
powerortorquetobeachievedoverthewholeengine
speedrangebuttheaddedbenefitofvalveoverlapis
tofacilitatethemixingofsomeexhaustgaswiththe
freshchargeofair.
•Therefore,thecombustiontemperatureandNOx
emissionarereduced.

61. Types of Variable Valve Timing
There are three types of variable valve timing
such as
cam-changing VVT
cam-phasing VVT and
combined cam-changing and cam-
phasing VVT.

62. Advantage:
•Itisverymuchpowerfulattopend.
Disadvantages:
•1.Stage2orstage3isnon-continuous
andnotmuchimprovementtotorque.
•2.Itisalsocomplexinnature.
Applications:
•ThistypeofVVTtechnologyisusedin
variousenginessuchasHondaVTEC,
MitsubishiMIVEC,NissanNeoVVL