msbte.engg-info.website fldr3_0/17619... · created date: 12/3/2019 8:42:39 am

MAHARASHTRASTATEBOARDOFTECHNICALEDUCATION(Autonomous)

(ISO/IEC-27001-2013Certified)__________________________________________________________________________________________________

Page1/1

WINTER–19EXAMINATIONSubjectName:Autotronics ModelAnswer SubjectCode:

ImportantInstructionstoexaminers:1)Theanswersshouldbeexaminedbykeywordsandnotasword-to-wordasgiveninthemodelanswer

scheme.2)Themodelanswerandtheanswerwrittenbycandidatemayvarybuttheexaminermaytrytoassessthe

understandinglevelofthecandidate.3)Thelanguageerrorssuchasgrammatical,spellingerrorsshouldnotbegivenmoreImportance(Not

applicableforsubjectEnglishandCommunicationSkills.4)Whileassessingfigures,examinermaygivecreditforprincipalcomponentsindicatedinthefigure.The

figuresdrawnbycandidateandmodelanswermayvary.Theexaminermaygivecreditforanyequivalentfiguredrawn.

5)Creditsmaybegivenstepwisefornumericalproblems.Insomecases,theassumedconstantvaluesmayvaryandtheremaybesomedifferenceinthecandidate’sanswersandmodelanswer.

6)Incaseofsomequestionscreditmaybegivenbyjudgementonpartofexaminerofrelevantanswerbasedoncandidate’sunderstanding.

7)Forprogramminglanguagepapers,creditmaybegiventoanyotherprogram basedonequivalentconcept.

Q.No.

SubQ.N.

Answer MarkingScheme

1(a) AttemptanyTHREEofthefollowing: 12i Withneatsketchdescribetheworkingofoxygensensor. 04

Ans

Figure:OxygenSensor

Theoxygensensoroperatesonthebasisofadifferencebetweentheoxygenpartialpressureofatmosphericairandthepartialpressureofoxygenintheexhaustgas.Figureshowsthatthesensorelementisessentiallyacell(battery).Theplatesaremadefrom platinum whichhavealayerofceramiczirconiabetweenthem whichactsasanelectrolyte. Theplatinum platesactsasacatalystsfortheoxygenwhichmakescontactwiththem,andtheyarealsousedtoconductelectricityawayfrom thesensor.Thecatalyzingactionthattakesplacewhenoxygencontactstheplatinum platescausesthetransportofoxygenionsthroughtheelectrolyteandthiscreatestheelectriccurrentthatgivesriseto

Sketch02

Marks&

Explain02

Marks

17619



Page2/2

thee.m.f(voltage)ofthesensorii Explaincollisionavoidancesystem. 04

Ans

Figure:CollisionAvoidanceSystem inAutomobiles.A collisionavoidancesystem isanautomobilesafetysystem designed to

reducetheseverityofacollision.Itisalsoknownasapre-crashsystem,forwardcollision warning system,orcollision mitigating system.Itusesradar(all-weather) and sometimes laser (LIDAR) and camera (employing imagerecognition)todetectanimminentcrash.GPSsensorscandetectfixeddangerssuchasapproachingstopsignsthroughalocationdatabase.Oncethedetectionisdone,thesesystemseitherprovideawarningtothedriverwhenthereisanimminentcollisionortakeactionautonomouslywithoutanydriverinput(bybrakingorsteeringorboth).Collisionavoidancebybrakingisappropriateatlowvehiclespeeds(e.g.below 50km/h),whilecollisionavoidancebysteeringisappropriateathighervehiclespeeds.Carswithcollisionavoidancemayalsobeequipped with adaptive cruise control,and use the same forward-lookingsensors.

OR

Collision avoiding Systems:Collision avoiding systems place smallradardetectorsup nearthefrontofthecar,usuallywithin thegrill,wheretheyconstantlysendoutquickburstsofhigh-frequencyradarwaves.Thesewaveswillbounceoffthenearestobjectsandreturntothesensor,whereaseparateunitconnectedtothesensorcalculateshowlongittookforthesignaltoleaveandbounceback.Withthisinformation,aPCSunitcandetermineanothercar'sposition,distance,speedandrelativevelocityalmostimmediately,andifanysuddenchangesinthosefactorscouldpotentiallycauseacollision,thesystem

Sketch02

Marks&

Explain02

Marks



Page3/3

canprovideinformationorassistthedriverinavoidingapotentialaccident.

iii Explain how to perform testto judge the condition ofgiven diode usingmultimeter.

04

Ans Testingofdiodewithadigitalmultimeter:i.From themultimeterconnecttheBLACK testconnectortotheRED wirecomingfrom theregulatorrectifier.ii.Thenfrom themultimeterconnecttheRED testconnectortoONEoftheYELLOW wirescomingfrom theregulatorrectifier.iii.Thereadoutshouldshow between0.400-0.600alongwithasingleaudiblebeepiv.ContinuebytestingtheremainingYELLOW wiresfollowingthesametestprocedure.

01Markfor

EachStep

iv Listtheadvantagesofelectronicsuspensionsystem. 04Ans AdvantagesofElectronicSuspensionSystem:

1)increasedefficiency;2)improveddynamicbehavior;3)stabilityimprovement;4)accurateforcecontrol;5)dualoperationoftheactuator

01MarkEach

1(b) AttemptanyONEofthefollowing: 06I Describe with a neatsketch use ofpowerdiodes in charging system of

alternator.06

Ans PowerDiode:Thepowersemiconductordiode,knownsimplyasthePowerDiode,hasamuchlargerPNjunctionareacomparedtoitssmallersignaldiodecousin,resultinginahighforwardcurrentcapabilityofuptoseveralhundredamps(KA)andareverseblockingvoltageofuptoseveralthousandvolts(KV).

Powerdiodeusedasregulatorinchargingsystem-Thealternatorisavariablespeedmachine.Asthevehiclespeedraisesthegeneratedvoltagerisesandifitisrunwithoutloadtheoutputvoltagecouldreach140volts.Thereforesomecontrolisrequiredanditisprovidebythemodernelectronicregulator.Theregulatormaintain constantaverage currentin the rotorfield winding byswitchingcurrentONandOFFandtheresultwillbeanalternatoroutputvoltageofabout14.2volts.Themaincomponentoftheelectronicvoltageregulatoristhezenerdiode.Itactsasasensingelementinanelectronicregulator.Figurer

02Marks

02Marks



Page4/4

shows a simplified diagram ofelectronic voltage regulator.This regulatoroperatesasfollows:-1.Whenthealternatorfirstincreaseisspeedtheoutputwillbebelow theprescribesetlevel2.UndertheseconditionstransistorT2willbeswitchedonbyafeedtoitsbasethroughresistorR3.3.Thisallowsfullfieldcurrenttoflowthusincreasingvoltageoutput4.Whentheprescribedsetvoltageisreachedthezenerdiodewillconduct.5.ResistorR1andR2areasimpleseriescircuittosetthevoltageappropriatetothevalueoftheZDsays14.2V.6.OnceZDconductstransistorT1willswitchonandpullthebaseofT2downtoground.7.ThisswitchesT2offandsothefieldcurrentisinterruptedcausingoutputvoltagetofall.8.ThiswillcauseZDtostopconductingT1willswitchoffallowingT2toswitchbackonandsothecyclewillcontinue.

Powerdiodesaredifferentfrom normalP-N junctiondiodes.Ithasalargecurrentcarryingcapacityi.e.itcanhandlelargepower.Powerdiodesarecapableofpassingasmuchasseveralhundredamperesofforwardcurrent.Thismakesitsuitableforapplicationswherelargercurrentandhighervoltagesarerequired.Anexampleofuseofpowerdiodesinthechargingsystem isshowninthefigure:Wemakeuseofsixdiodeswhichareusedtosupplythecurrenttothefielddiodesrequiredfortheexcitationofthefieldwindings.Thusthecurrentform thestatorisusedtoexcitethefieldwindingswiththehelpofpowerdiodes.

02Marks

ii Explainanalogtodigitalanddigitaltoanalogsignalconversion. 06Ans AnalogtoDigitalConversion:Analogtodigitalconversionisnecessarybecause

manysensorsignalsareofanalog(varyingvoltage)form.Inorderforthecontrolcomputer(ECU)tofunctiontheseanalogsignalsmustbeconvertedtobinarycodes(digitalsignals).Conversionfrom ananalogvoltagetoadigitalcodecan

03Marks



Page5/5

bedoneinanumberofways.FigureshowsonetypeofA/Dconverterthatisknownasa‘flash’converter.Theflashconverterconsistsoffourcomparatorsandanencodercircuitwhichtakesthecomparatoroutputsandconvertsthemintoabinarycode.Anelectroniccomparatorisacircuitwhichcontinuouslycomparestwosignals.Oneoftheinputs,ateachcomparatorisareferencevoltage.Whentheinputvoltagematchesthereferencevoltagethecomparatoroutputslogic1.Thereferencevoltagesshowninthefigureare1Vupto4V.Tableshowstheinput/outputperformanceoftheconverter.

ADigitaltoAnalogConverter(DAC)convertsadigitalinputsignalintoananalogoutputsignal.Thedigitalsignalisrepresentedwithabinarycode,whichisacombinationofbits0and1.ThischapterdealswithDigitaltoAnalogConvertersindetail.Theblockdiagram ofDACisshowninthefollowingfigure−

ADigitaltoAnalogConverter(DAC)consistsofanumberofbinaryinputsandasingleoutput.Ingeneral,thenumberofbinaryinputsofaDACwillbeapoweroftwo.TherearetwotypesofDACs

WeightedResistorDAC R-2RLadderDAC

03Marks

2 AttemptanyFOURofthefollowing: 16A Explaintheworkingofaenginecoolanttemperaturesensor. 04

Ans WorkingofCoolantTemperatureSensor: Sketch02

Marks&

Explain02

Marks



Page6/6

Figure:SemiconductorResistorSensor.Acommonlyuseddeviceforsensingtemperatureisthermistor.Athermistorutilizestheconceptofnegativetemperaturecoefficienti.e.itsresistancegetslowerasitstemperatureincreasesandthisisacharacteristicofsemiconductormaterial.Working:Thesensorworksbymeasuringthetemperaturethat’sbeinggivenoffbythethermostatand/orthecoolantitself.Thetemperatureisthensenttotheon-board controlsystem.From there,yourvehicle’scomputerwillusethistemperatureinformationtoeithercontinueoperatingoradjustcertainenginefunctions,alwaysworkingtokeeptheenginetemperatureatanideallevel.Asthecontrolsystem receivesthetemperaturefrom theCTS,itmaytriggerthecoolingfantoeithershutofforturnon.Additionally,itmaysignaltheneedforaricherfuelmixtureoropentheexhaustgasrecirculation.Forexampleat-400C atypicalcoolantsensorhasaresistanceof1,00,000ohms.Theresistancedecreasestoabout70,000ohmsat1300C.Thechangeincurrentisthesensorsignals.

B Enlistthedifferenttypesofcommunicationsystem usedinautomobile.StatethefunctionofBluetoothtechnology.

04

Ans Typesofcommunicationsystem usedinautomobile1.Bluetooth2.Wi-Fi3.CANBus4.LINBus5.GSM Network6.Opticfibers.7.EthernetFunctionofBluetoothTechnology:Bluetoothisdesignedtosupportpersonalareanetwork(PAN)toreplacewiredcablebetweennearbydevices.Bluetoothisausedtopairmobilephonestovehicles.Suchpairingenablehandsfreecallingfrom thevehicle.Itallowsavehicleembeddeddisplayunittobeusedtocontrolmobilesphonesandallowsamobilesphonetousethevehicleembeddedsoundsystems.Italsoenablesmakingemergencycallsduringaccidents,downloadingdigitalcontacts,travelinformation orsoftware updates,and to access tointernet.

AnyFour-1/2mark

each

02Marks

C Differentiatebetweendigitalvisualdisplayandanalogvisualdisplay. 04



Page7/7

Ans

AnyFourPoint

01MarkEach

D ExplainGPSNavigationsystem usedinautomobile. 04Ans

Figure:GPSSystemGlobalPositioningSystem (GPS):TheGlobalPositioningSystem (GPS)isaspace-basednavigationsystem Thatprovideslocationandtimeinformationinallweatherconditions,anywhereonorneartheEarthwherethereisanunobstructedlineofsighttofourormoreGPSsatellites.GPSsystemsaremadeupof3segments:-1.SpaceSegment(SS)2.ControlSegment(CS)3.UserSegment(US)1.SpaceSegment:GPSsatellitesflyincircularorbitsatanaltitudeof20,200kmandwithaperiodof12hours.Poweredbysolarcells,thesatellitescontinuouslyorientthemselvestopointtheirsolarpanelstowardthesunandtheirantennatowardtheearth.OrbitalplanesarecenteredontheEarth.Eachplanehasabout550 tiltrelativetoEarth'sequatorinordertocoverthepolarregions.Eachsatellitemakestwocompleteorbitseachsiderealday.Sidereal-TimeittakesfortheEarthtoturn360degreesinitsrotation.ItpassesoverthesamelocationonEarthonceeachday.2.ControlSegment:TheCSconsistsof3entities:(i)MasterControlStation:-Themastercontrolstation,locatedatFalconAirForce Base in Colorado Springs, Colorado, is responsible for overallmanagementoftheremotemonitoringandtransmissionsites.(ii)Monitorstation:-Eachofthemonitorstationscheckstheexactaltitude,position,speed,andoverallhealthoftheorbitingsatellites.Thecontrolsegmentusesmeasurementscollectedbythemonitorstationstopredictthebehaviorofeachsatellite'sorbitandclock.Thepredictiondataisuplinked,ortransmitted,tothesatellitesfortransmissionbacktotheusers.(iii)GroundAntennas:-Groundantennasmonitorandtrackthesatellites.They

01Mark

03Mark



Page8/8

alsotransmitcorrectioninformationtoindividualsatellites.3.UserSegment:Theuser'sGPSreceiveristheUSoftheGPSsystem.GPSreceiversaregenerallycomposed ofan antenna,tuned to thefrequenciestransmittedbythesatellites,receiver-processors,andahighly–stableclock,commonlyacrystaloscillator.Theycanalsoincludeadisplayforshowinglocationandspeedinformationtotheuser.

E Describeworkingofunitinjectoractuator. 04Ans ElectronicFuelInjector(UnitInjector):

Avacuum –poweredfuelpressureregulatorattheendofthefuelrailensuresthatthefuelpressureintherailremainsconstantrelativetotheintakepressure.Foragasolineengine,fuelpressureisusuallyontheorderof35-50psi.Fuelinjectorsconnecttotherail,buttheirvalvesremaincloseduntiltheECUdecidestosendfuelintothecylinders.Usually,theinjectorshavetwopins.OnepinisconnectedtothebatterythroughtheignitionrelayandtheotherpingoestotheECU.TheECUsendsapulsinggroundtotheinjector,whichclosesthecircuit,providingtheinjectorssolenoidwithcurrent.Themagnetontopoftheplungerisattractedtothesolenoidsmagneticfield,openingthevalve.Sincethereisahighpressureintherail,openingthevalvesendsfuelatahighvelocitythroughtheinjectorsspraytip.Thedurationthatthevalveisopenandconsequentlytheamountoffuelsentintothecylinderdependsonthepulsewidth(i.e.howlongtheECU sendsthegroundsignaltotheinjector).Whentheplungerrises,itopensavalveandtheinjectorsendsfuelthroughthespraytipandintoeithertheintakemanifold,justupstream oftheintakevalve,ordirectlyintothecylinder.

Sketch02

Marks

&

Explain02

Marks

F Describetheprocedureofconversionofsignalsfrom analogtodigital. 04Ans AnalogtoDigitalConversion:Analogtodigitalconversionisnecessarybecause

manysensorsignalsareofanalog(varyingvoltage)form.Inorderforthecontrolcomputer(ECU)tofunctiontheseanalogsignalsmustbeconvertedtobinarycodes(digitalsignals).Conversionfrom ananalogvoltagetoadigitalcodecanbedoneinanumberofways.FigureshowsonetypeofA/Dconverterthatisknownasa‘flash’converter.Theflashconverterconsistsoffourcomparatorsandanencodercircuitwhichtakesthecomparatoroutputsandconvertsthemintoabinarycode.Anelectroniccomparatorisacircuitwhichcontinuouslycomparestwosignals.Oneoftheinputs,ateachcomparatorisareferencevoltage.Whentheinputvoltagematchesthereferencevoltagethecomparatoroutputslogic1.Thereferencevoltagesshowninthefigureare1Vupto4V.Tableshowstheinput/outputperformanceoftheconverter.

Sketch02

Marks&

Explain02

Marks



Page9/9

3 AttemptanyFOURofthefollowing: 16A Prove that561(10) = 1000110001(2) are equivalentby stepwise converting

decimaltobinaryandbinarytodecimal.04

Ans GivenData,IllustrationforDecimalToBinary:561(10)=1000110001

2 561 12 280 02 140 02 70 02 35 12 17 12 8 02 4 02 2 0

1 1

IllustrationforBinarytoDecimal:=(1x20)+(0x21)+(0x22)+(0x23)+(1x24)+(1x25)+(0x26)+(0x27)+(0x28)+(1x29)=1+0+0+0+16+32+0+0+0+512=561

02Marks

ForDecimal

toBinary

&

02Marks

ForBinarytoDecimal

B DifferentiatebetweenCANBusandLINBuscommunicationsystem. 04Ans CAN Bus System:CAN (ControllerArea Network)is an example ofan

automotivedigitaldatasystem.ItwasdevelopedbytheRobertBoschCompanyinGermany.CANisaserialsynchronouscommunicationprotocolthatconnectselectroniccontrolmodules,sensorsandactuators.The twisted pairofthe CAN bus system minimizes electrically initiatedinterference and virtuallyeliminates the possibilityofmessages becomingcorrupted.ThemajorfeatureoftheCANbussystem are:

i. Prioritycontrolledmessagetransmission.ii. Low cotsthroughtheuseofalow costtwistedtwowirecableand

useofsimpleprotocolwithlowpowerdemand.iii. Adatatransferrateupto1MBPSforthehighspeedCAN(CAN-C)and

AnyFourPoints

01MarkEach



Page10/10

upto125KBPSforthelowspeedCAN(CAN-B)iv. Highreliabilityofdatatransfer

LINBusSystem:TheroleoftheLINbusistocomplementtheCANbus,notreplaceit.Itisaninexpensiveserialcommunicationsprotocolthatsupportsremoteandnon-criticalapplicationsinacar’snetwork.UnlikeCAN,LINworksonamaster-slavetopology.Typicallythenetworkcomprisesonemasterandupto16slaves.Allcommunicationisinitiatedbythemasternode.Becauseallthenodesareclockedbythemaster,aprecisionclockisrequiredonlyinthemasternode.ThisisoneofthereasonsthatLINislessexpensivethanCANFeaturesandbenefitsofLINi.Complementaryrole–AsalreadystatedtheroleofLINisnottoreplaceCANbuttocomplementit.ThisfeaturehelpsCANtoextendtoremotehierarchicalsub-networkswithinapplications.ii.Single-wire implementation – LIN’s low-cost,single-wire implementation(contrarytoCAN’stwistedpairimplantation)reducescostconsiderably.iii.Datarate–Dataratesarelimitedto20Kbps(forEMIcontrolreasons).Thishelpsmaintainthereliabilityofthenetwork.iv.Broadcastserialnetwork-TheLINnetworkcanhaveonemasterandupto16slavenodes.Allmessagesoriginateatthemasterand atmostoneslaveresponds,basedonthemessageidentifier.v.Self-synchronization -No crystalorresonatoris required,thus loweringimplementationcostsignificantly.vi.Latencytime-LIN networksprovideguaranteedlatencytimes,makingitamorepredictablenetwork

C Describeconstructionandworkingofanyonetypeofsensorwhichisusedtodeterminequantityofairenteringtheengine.

04

Ans WorkingofAirflowSensor:

Figure:AirFlowSensorThevanetypeairflowmeasurementconsistsoflightlyspringloadedvalvethatmovesasideasairflow increases.Thevalveistiedtoarheostat,atypeofvariableresistor.Thechangeincurrentintheresistorcircuitisthesensorsignal.Alsousedisacarbonfilm resistorwithvariableareaconnectedtotheairflowmeterplate.Itgivesasignalthatvariesair/fuelratiowithdemand.

Sketch02

Marks&

Explain02

Marks

D Explaindifferenttypesoferrorsinthemeasurement. 04Ans Typesoferror:-

1)Grosserror2)Systematicerror3)Random error1.Gross error:The class oferrors covers human mistakes in readinginstruments and recording and calculating measurement results. Theresponsibilityofthemistakesnormallylieswiththeexperimenter.2.Systematicerror:Systematicerrorresultfrom knownvariationininstrumentperformance,forwhichcorrectionscanbemadeifdesired.Therearemanysourcesofsystematicerrors,including temperaturevariation in calibration,loadinganddynamicresponse.a.Systematicloadingerrors-Thiserrorareduetoenergyextractedbythe

AnyTwo02

MarkEach



Page11/11

instrumentswhenmakingmeasurements.Whenevertheenergyextractedfromasystem undermeasurementisnotnegligible,theextractedenergycausesachangeinthequantitybeingmeasured.Wheneverpossible,aninstrumentisdesignedtominimizesuchloadingeffects.b.DynamicResponse-ThisaretheanothersourceofSystematicerror.Anyinstrumentshaslimitedresponseratetoveryrapidlychanginginput.Inmanyautomotiveinstrumentationapplicationsthebandwidthispurposelyreducedtoavoidrapidfluctuationinreading.3.Random Error:Random errorsareessentiallyrandom fluctuationsinindicatedvalueforthemeasurement.Mostrandom measurementerrorresultsfromnoise.

E Describediagnosismethodsforfuelinjector. 04Ans 1.SoundTest:

a.Theinjectorsoundtestisamethodofquicklycheckingtheoperationofthepintleonenginewheretheinjectorsareaccessible.

b.Aportinjectorthatisnotfunctioningmaycauseacylindermisfireatlowenginespeed.

c.Withtheengineidlingastethoscopepickupmaybeplacedonthesideoftheinjectorbody.

d.EachinjectordoesnotproduceanyclickingnoisetheinjectorconnectingwiresorPCM maybedefective.

e.When theinjectorclicking noiseiserratictheinjectorplungermaybesticking.

f. Ifthereisnoinjectorclickingnoise,proceedwiththeinjectorohmstesttolocatethecauseoftheproblem.

2.OhmmeterTest:a.Anohmmetermaybeconnectedacrosstheinjectorterminalstocheckthe

injector’swindingaftertheinjectorwirearedisconnected.b.Iftheohmmeterreadingisinfinitetheinjectorwindingisopen.c.Anohmmeterreadingbelow thespecifiedvalveindicatesthattheinjector

windingisshortedd.Asatisfiedinjectorwindingshouldhaveresultbetween0.3to0.4ohms.e.Replacetheinjectoriftheresultsdonothavethespecifiedresistance.

02Marks

02Marks

4(a) AttemptanyTHREEofthefollowing: 12I ExplainuseofLEDinautomotivedisplay. 04

Ans LightEmittingDiode(LED):Alightemittingdiode(LED)issimilarinoperationtothediode,excepttheLEDemitslightwhenitisforwardbiased.Ithasasmalllensbuiltintoitsolightcanbeseenwhencurrentflowsthroughthediode.WhentheLEDisforwardbiased,theholesandelectronscombineandcurrentisallowedtoflowthroughit.Theenergyisgeneratedisreleasedintheform oflight.NormallyLEDrequires1.5to2.2voltstolight.

02Marks



Page12/12

Figure:SymbolandSketchofLEDUsesofLED:-i.Itisusedinheadlampsandtaillampssystem ofvehicles.ii.Itisusedinlightcontrolpanel.iii.Itisusedininteriorlightsystem ofthecar.iv.Itisusedinindicatorlightsofacar.

AnyTwo01

markeach

ii Draw blockdiagram ofautomotivecomputer.Statethefunctionofanyfourcomponents.

04

Ans

Figure:BlockDiagram ofAutomotiveComputer.OR

Sketch02

Marks

&



Page13/13

Figure:BlockDiagram ofAutomotiveComputer.

1.InputUnit:Dataandinstructionsmustenterthecomputersystem beforeanycomputationcanbeperformedonthesupplieddata.Theinputunitthatlinkstheexternalenvironmentwiththecomputersystem performsthistask.Dataandinstructionsenterinputunitsinformsthatdependupon the particulardevice used.Itaccepts (orreads)the listofinstructions and data from the outside world.Itconverts theseinstructionsanddataincomputeracceptableformat.Itsuppliestheconverted instructionsand datato theComputersystem forfurtherprocessing.

2.OutputUnit:Thejobofanoutputunitisjustthereverseofthatofaninputunit.Itsuppliedinformationandresultsofcomputationtotheoutsideworld.Thus itlinks the computerwith the externalenvironment.Itacceptstheresultsproducedbythecomputerwhichareincodedformandhencecannotbeeasilyunderstoodbyus.Itconvertsthesecodedresultstohumanacceptable(readable)form.Itsuppliedtheconvertedresultstotheoutsideworld.

3.Storage Unit:The data and instructions thatare entered into thecomputersystem through inputunits have to be stored inside thecomputerbeforetheactualprocessingstarts.TheStorageUnitortheprimary/mainstorageofacomputersystem isdesignedtodoallthesethings.Itprovidesspaceforstoringdataandinstructions,spaceforintermediateresultsandalsospaceforthefinalresults.Allthedatatobeprocessed and theinstructionrequired for processing.Intermediateresultsofprocessing.Finalresults ofprocessingbeforetheseresultsarereleasedtoanoutputdevice.

4.CentralProcessingUnit:ThemainunitinsidethecomputeristheCPU.Thisunitisresponsibleforalleventsinsidethecomputer.Itcontrolsallinternal and external devices, performs" Arithmetic and Logicaloperations".The operations a Microprocessorperforms are called"instructionset"ofthisprocessor.ThecontrolUnitandtheArithmeticandLogic unitofa computersystem are jointlyknown as the CentralProcessingUnit(CPU).TheCPUisthebrainofanycomputersystem.Inacomputersystem,allmajorcalculationsand comparisonsaremadeinside the CPU and the CPU is also responsible foractivating and

FunctionofanyFour

½MarkEach



Page14/14

controllingtheoperationsofotherunitsofacomputersystem.5.ArithmeticandLogicUnit(ALU):Thearithmeticandlogicunit(ALU)ofa

computersystem is the place where the actualexecution oftheinstructions takes place during the processing operations. Allcalculationsareperformedandallcomparisons(decisions)aremadeintheALU.Thearithmeticandlogicunit(ALU)isthepartwhereactualcomputationstakeplace.Itconsistsofcircuitsthatperform arithmeticoperations(e.g.addition,subtraction,multiplication,divisionoverdatareceivedfrom memoryandcapabletocomparenumbers(lessthan,equalto,orgreaterthan).

iii Describeworkingofpurgecontrolactuator. 04Ans

Figure:PurgeControlActuator.OR

Figure:PurgeControlActuator.ThepurgevalveisthepartofthevehicleEvaporativeEmissionControl(EVAP)system.TheEVAPsystem preventsfuelvaporsinthefueltankfromescapingintotheatmosphere.TheEVAPsystem trapsfuelvaporsfrom thefueltankand temporarilystoresthem inthecharcoalcanister,seethediagram.Whentheengineisrunningundercertainconditions,thefuelvaporsarepurgedfrom thecanisterandburnedinsidetheengine.Thepurgevalvepreciselycontrolstheamountoffuelvaporthatispurgedfrom thecharcoalcanister.Inmoderncars,thepurgevalveisanelectrically-operatedsolenoidthatiscontrolledbytheenginecomputer.Whentheengineisoff,thepurgevalveisclosed.Whentheengineisrunningandfullywarmedup,theenginecomputergraduallyopensthepurgevalvetoallow someamountoffuel

Sketch02

Marks

&

Desc.02

Marks



Page15/15

vaportobemovedfrom thecharcoalcanistertobeburnedintheengine.Thepurgeflowismonitoredbyanumberofsensors.Ifthepurgeflowislessormorethanisexpectedundertheconditions,thecomputerilluminatesthe"CheckEngine"light.

iv ExplainAntilockBrakingSystem(ABS) 04Ans

Figure:ABSSystemTherearefourmaincomponentstoanABSsystem:i.SpeedSensors:Theanti-lockbrakingsystem needssomewayofknowingwhenawheelisabouttolockup.Thespeedsensors,whicharelocatedateachwheel,orinsomecasesinthedifferential,providethisinformation.ii.Valves:ThereisavalveinthebrakelineofeachbrakecontrolledbytheABS.Onsomesystems,thevalvehasthreepositions.iii.Pump:Sincethevalveisabletoreleasepressurefrom thebrakes,therehastobesomewaytoputthatpressureback.Thatiswhatthepumpdoes;whenavalvereducesthepressureinaline,thepumpistheretogetthepressurebackup.iv.Controller:Thecontrollerisacomputerinthecar.Itwatchesthespeedsensorsandcontrolsthevalves.Thecontrollermonitorsthespeedsensorsatalltimes.Itislookingfordecelerationsinthewheelthatareoutoftheordinary.Rightbeforewheellocksup,itwillexperiencea rapid deceleration.Ifleftunchecked,thewheelwouldstopmuchmorequicklythananycarcould.Itmighttakeacarfivesecondstostopfrom 60mph(96.6kph)underidealconditions,butawheelthatlocksupcouldstopspinninginlessthanasecond.TheABScontrollerknowsthatsucharapiddecelerationisimpossible,soitreducesthepressuretothatbrakeuntilitseesacceleration,thenitincreasesthepressureuntilitseesthedeceleration again.Itcan do thisveryquickly,beforethetirecan actuallysignificantlychangespeed.Theresultisthatthetireslowsdownatthesamerateasthecar,withthebrakeskeepingthetiresverynearthepointatwhichtheywillstarttolockup.Thisgivesthesystem maximum brakingpower.

Sketch02

Marks

&

Expl.02

Marks

4(b) AttemptanyONEofthefollowing: 06I Withthehelpofneatsketchexplainelectroniccontrolsystem usedinCRDI. 06

Ans ElectronicControlSystem usedinCRDI:InaCRDIsystem,themicroprocessorworkswithinputfrom multiplesensors.Basedontheinputfrom thesesensors,themicroprocessorcancalculatethepreciseamountofthedieselandthetimingwhenthedieselshouldbeinjected



Page16/16

insidethecylinder.Usingthesecalculations,theCRDIcontrolsystem deliverstherightamountofdieselattherighttimetoallow bestpossibleoutputwithleastemissionsandleastpossiblewastageoffuel.TheinputsensorsincludeAcceleratorPedalPosition (APP)sensor,crank position sensor,pressuresensor,lambdasensoretc.Theuseofsensorsandmicroprocessortocontroltheenginemakesmostefficientuseofthefuelandalsoimprovedthepower,fuel-economyandperformanceoftheenginebymanagingitinamuchbetterway.

Figure:BlockDiagram ofElectronicControlSystem usedinCRDI.

Sketch03

Marks

&

Explain03

Marks

ii Describethesixstepapproachforcomponenttesting. 06Ans Sixstepapproachforcomponentstesting:-

1.Collectevidence.2.Analyzeevidence.3.Locatethefault.4.Findthecauseofthefaultandremedyit.5.Rectifythefault(ifdifferentfrom 4).6.Testthesystem toverifythatrepairiscorrect.Sixstepapproachforcomponentstesting:-1.CollectEvidence-Collectingevidencemeanslookingforallthesymptomsthatrelatetothefaultandnotjumpingtoconclusions,e.g.becausethesystemiscontrolledbyanECUitmustbetheECUthatisatfault.Inordertocollecttheevidenceitisnecessarytoknowwhichcomponentsonthevehicleactuallyformthepartofthefaultysystem.Thisiswheresoundbasicskillscomein.Ifanengine controlsystem is malfunctioning because one cylinderhas poorcompressionitisimportanttodiscoverthisatanearlystageofthediagnosticprocess.

Six-½

markeach

&



Page17/17

2.AnalyzeEvidence-Inthecaseofpoorcompressionononecylinder,givenaboveasanexample,theanalysiswouldtaketheform ofteststodeterminethecauseoflowcompression,E.g.burntvalve,blownheadgasketetc.Theanalysisofevidence thatis performed willvary according to the system underinvestigation.Butthesestepsareobviouslyimportant.3.Locatethefault-TheProcedurefordoingthisonanelectronicssystem variesaccordingtothetypeoftestequipmentavailable.Itmaybethecasethatthesystem hassomeself-diagnosticswhichwillreadyoutotheareaofthesystemwhichisdefectiveLetusassumethatthisisthecaseandtheself-diagnosticsreportthatanenginecoolanttemperaturesensorisdefective.Howdoyouknowwhetheritisthesensor,orthewiringbetweenitandtheremainderofthesystem?Againthisiswhereagoodbasicknowledgeofthemake-upofthesystem isinvaluable.4.Findthecauseofthefaultandremedyit-Withelectronicsystem repairitisoftenthecasethatareplacementunitmustbefitted.However,thismaynotbetheendofthematter.Iftheunithasfailedbecauseofsomefaultexternaltoit,itisimportantthatthiscauseoffailureisfoundandremediedbeforefittingthenewunit.Itisoftennotjustamatteroffittinganewunit.5.Givethesystem athoroughtest-Testingafterrepairisanimportantaspectofvehicleworkand especiallyso whereelectronicallycontrolled systemsareconcerned.Inthecaseofintermittentfaults,suchtesting’smayneedtobeextendedbecausethefaultmayonlyoccurwhentheengineishotandthevehicleisbeingusedinaparticularway.6.Testthesystem toverifythatrepairiscorrect-Itismandatorytotestthesystem sothatitwillverifythatthestepsfollowedduringthetestingarecorrect.Howeverwecancomeacrossanyfaultthenwehavetofollow thestepwiseprocedureoftesting.

Explanation

AnyThree

01markEach

5 AttemptanyFOURofthefollowing: 16A Explainapplicationofdiodeasvoltageregulator. 04

Ans Voltageregulatorofchargingsystem:

Thealternatorisavariablespeedmachine.Asthevehiclespeedraisesthegeneratedvoltagerisesandifitisrunwithoutloadtheoutputvoltagecouldreach140volts.Thereforesomecontrolisrequiredanditisprovidebythemodernelectronicregulator.TheregulatormaintainconstantaveragecurrentintherotorfieldwindingbyswitchingcurrentONandOFFandtheresultwillbeanalternatoroutputvoltageofabout14.2 volts.Themain componentofthe

Sketch02

Marks

Desc.



Page18/18

electronicvoltageregulatoristhezenerdiode.Itactsasasensingelementinanelectronicregulator.Figurershowsasimplifieddiagram ofelectronicvoltageregulator.Thisregulatoroperatesasfollows:-1.Whenthealternatorfirstincreaseisspeedtheoutputwillbebelow the

prescribesetlevel2.UndertheseconditionstransistorT2willbeswitchedonbyafeedtoitsbasethroughresistorR3.

3.Thisallowsfullfieldcurrenttoflowthusincreasingvoltageoutput4.Whentheprescribedsetvoltageisreachedthezenerdiodewillconduct.5.ResistorR1andR2areasimpleseriescircuittosetthevoltageappropriatetothevalueoftheZDsays14.2V.6.OnceZDconductstransistorT1willswitchonandpullthebaseofT2downtoground7.ThisswitchesT2offandsothefieldcurrentisinterruptedcausingoutputvoltagetofall.8.ThiswillcauseZDtostopconductingT1willswitchoffallowingT2toswitchbackonandsothecyclewillcontinue.

02marks

B Statedifferenttypesofcomputermemories.EnlistthefunctionofReadOnlyMemory.

04

Ans TypesofComputerMemories:1.Readonlymemory(ROM)2.PROM:(ProgrammableReadonlyMemory)3.EPROM:ErasableProgrammablereadonlymemory4.EEPROM:ElectricallyErasableProgrammablereadonlymemory5.RAM:Random accessmemory6.KeepAlivememory(KAM)FunctionofReadonlymemory(ROM):

i. Itcontainsafixedpatternof1sand0sthatrepresentpermanentstoredinformation.

ii. ROM containsthebasicoperatingparametersforthevehicle.Thisinformation is used to instructthe computeron whatto do inresponsetoinputdata.TheCPUreadstheinformationcontainedintheROM,butitcannotwritetoitorchangeit.

iii. ROM memoryisnotlostwhenpowertothecomputerislost

AnyFour1/2

MarkEach

&

02Marks

C Describeworkingofidlespeedactuator. 04



Page19/19

Ans

Figure:IdleSpeedActuator.WorkingofIdleSpeedActuator:Inthrottlebodyandportfuelinjectionsystems,engineidlespeediscontrolledbypassingacertainamountofairflowpastthethrottlevalveinthethrottlebodyhousing.TheIAC system consistsofanelectricallycontrolledsteppermotororactuatoroperatedbytheECM.TheECMcontrolstheidlespeedbyopeningandclosingtheairpassageintotheintake.TheECM/PCM calculatestheamountofairrequiredforsmoothidlingbasedoninputdatasuchascoolanttemperature,engineload,andenginespeedandbatteryvoltage.TheECM /PCM thesignalstheIACmotortoextendorretracttheidleaircontrolvalveintheairbypasschannel.

Sketch02

Marks

&

Desc.02

Marks

D Drawaneatblockdiagram,toindicatemeasurementoftemperatureinvehicleinstrumentation.

04

Ans

Figure:TemperatureMeasuringInstruments.

NeatLabeledSketch

04Marks

e WritediagnosisprocedureforThrottlePositionSensor. 04Ans TestingofThrottleposition(TP)sensor:-Followingprocedureisfollowedto

diagnoseaTPsensor:Anyfour

Points



Page20/20

1.WiththeignitionswitchintheRUNposition,connectavoltmeterfrom thesensorsignalwiretoground.

2.Slowlyopenthethrottleandobservethevoltmeter.3.Thevoltmeterreadingshouldincreasesmoothlyandgradually.4.TypicalTPSvoltagereadingsare0.5Vto1Vwiththethrottleintheidle

positions,and3.5Vto4.5Vatwideopenthrottle.5.Alwaysrefertothevehiclemanufacturer’sspecifications.6.IftheTPSdoesnothavethespecifiedvoltageorifthevoltagesignalsis

erratic,replacethesensor.

01MarkEach

6 AttemptanyFOURofthefollowing: 16a Describediagnosisuseofbatterytesterandluxmeter. 04

Ans Batterytestersusedfortestingthevariousparameters& conditionsofthebatterywhilecheckingsignalforsystem diagnosisasfollows:a.Voltagemeasurement.b.Resistancemeasurement.c.CCAvalueMeasurement.d.Batterycondition.e.BatteryloadtestetcUsesofLuxMeter:a.Usedtomeasurelightintensity.b.Itisusedinphotographyandvideofilming.c.CheckintensityoflightsintheautomaticON/OFFheadlightsystem andautomaticheadlightdimmingsystem.

AnyTwoUses

ofEach

01MarkEach

b Explainworkingofcrankshaftpositionsensorwithaneatsketch. 04Ans

WorkingofCrankshaftPositionSensor:Theprincipleelementsofthesensorare:1.Anironrotorwithlobesonit2.Apermanentmagnet3.Ametallicpath(thepolepiece)forcarryingthemagneticflux4.Acoil,woundaroundthemetallicpath,inwhichavoltageisinduced.Itconsistsofapermanentmagnetwithacoilsurroundingit.A metaltabpassingclosetothemagnetfluxesthemagneticfieldacrossthecoil,whichinturncausesachangeinthereluctanceofthecoil.Acurrentbeingsentthroughthecoilwouldchange.Themomentarychangeinthecurrentistheoutputsignalofthesensor.Theoutputvoltageisshownbelow:Itshouldbeintherangeof0Vto5V.

Sketch02

Marks

&

Explain.02

Marks



Page21/21

c Compareopenloopandcloseloopcontrolsystem. 04Ans

OpenLoopControlSystem CloseLoopControlSystem

Automaticcorrectioninitsoutput,isnotpossible,itiscalledanopenloopcontrolsystem.

Automaticcorrectioninitsoutput,ispossible,itiscalled an closeloopcontrolsystem.

Thereisnoautomaticcorrectionofthevariationinitsoutput,itiscalled anopenloopcontrolsystem.

Thisfeedbackautomaticallymakesthesuitablechangesintheoutputduetoexternaldisturbance.

Comparing of output (throughfeedback)withthedesiredinputdoesnottakeplaceonitsown

Feedbackistakenfrom outputandfedintoinput.

Gain is uncontrolled in open loopsystem

Gaincanbecontrolledincloseloopsystem.

Moreerrors MoreAccurateOutputmaybeoscillatory/damped OutputismorestableLessExpensive MoreExpensiveSimpleinConstruction Complicatedinconstruction.

AnyFour

Points01

MarkEach

d DescribeEGRvalveactuator. 04Ans

Figure:EGRValveActuatorEXHAUSTGASRECIRCULATION(EGR)CONTROL:TheECM controlsavacuumsolenoidvalvethatisusedtoopenclosethevacuum circuittoEGRvalve.Whensolenoidisenergized,itshutsoffvacuum toEGRvalve.Whensolenoidisde-energized,itallowsvacuum topassthroughthesolenoidtotheEGRsystem.



Page22/22

Thesolenoidvalveisenergizedwhencoolanttemperatureisbelow 60°C,atspeedbelow 1200rpm,underheavyloadoratwideopenthrottle.Duringallotherengineoperatingi.e.partthrottleconditionswithcoolanttemperatureabove65°CtheECM de-energizesthesolenoidvalveandallowsthevacuum toopentheEGRvalve..

e Drawblockdiagram ofelectronicpowersteeringsystem. 04Ans

Figure:BlockDiagram ofElectronicPowerSteeringUnitAnElectronicPowerSteering(EPS)system’sadvantageoverahydraulicsystemisiftheenginestalls,youwillstillhavesteeringassist.Thisadvantagecanalsobeadisadvantageifthesystem shouldshutdownwhiletheengineisrunningyoulosesteeringassist.Electronicpowersteeringsystemseliminatetheneedforapump,hosesandadrivebeltconnectedtotheengineusingvariableamountsofpower.TheconfigurationofanEPSsystem canallow theentirepowerassistsystem tobepackagedontherackandpinionsteeringgearorinthesteeringcolumn.Thesystem doesnotdragontheenginefrom eitherapowersteering pump oralternatorbecause itwillnotprovide assistuntilrequiredbydriverinput.Also,thereisnohydraulicfluid.TherotordirectionisdeterminedbythesequenceinwhichvoltageisappliedtocoilA,BorCandreturnedtogroundthroughanattachedpair.ThesequenceforclockwiseisABCandforcounter-clockwiseitisCBA(showninfigure).TheprimarypurposeoftheEPScontrolleristoprovidemotorcontrol.Theprocessoristheheartofthecontrollerforinputand output.Processoroutputdrivesthethreepairsoftransistorsthatcontroltherotationofthemotor.Primaryinputtotheprocessorcomesfrom thetorquesensorandhandwheelspeedandpositionsensor.Theprocessoralsoisanintegralpartofthecontrolledareanetwork(CAN)andvehicledatabussforchassisandpowertraincommunications.Thisdatabusssuppliesvehiclespeed,enginespeed,ABSandESCinformation.Thecontrollerhasadaptivememoryanddiagnostics.

msbte.engg-info.website fldr3_0/17619... · created date: 12/3/2019 8:42:39 am

Documents