2 汽车专业英语课件-汽车维护修理部分修改后-section 2Chapter 7-1 12

复习,提问（教师说发动机汉语部件名称，同学回答英文名称）用英语说明内燃机分类方式和类别,Section2AutomotiveMaintenanceandRepair,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments7.2OperationofOTCEnhancedMonitorscantoolChapter8ReadingRepairManuel8.1DiagnosingAutomaticTransaxle（A541E）8.2HowtoReadandUseWiringDiagrams8.3HowtoReadTechnicalServiceBulletin,学习内容,本章学习内容、目标和重点难点,学习目标,难点重点,Chapter7CommonSpecialServiceToolsandEquipmentsFunctionsofDiagnosticEquipments：Non-PoweredTestLights，DigitalVolt-Ohmmeters（DVOM）,Oscilloscopes,1.掌握无源试灯、数字式万用表的功能；掌握使用方法2.了解有关故障术语,1.重点为数字式万用表的使用方法2.难点需要记忆的专业词组过多,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,7.1.1NewWordsandPhrases,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,1.Non-PoweredTestLightspurposeNon-poweredtestlights(Figure71)continuetohaveaplaceinyourtoolboxforcertainquickchecks.However,manytechnicianscontinuetousethesedevicesincircuitswheretheycanbeverydangerous;therefore,itisimportanttounderstandafewfactsaboutthem.Thetestlightsonlypurposeistoserveasaquick-checktooltoshowifavoltageispresent.,7.1.2Text,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,1.Non-PoweredTestLightspurposeFunctionalProcedureBeginbyconnectingthetestlightacrossthebatterysterminalstoverifytheintegrityofthetestlight.Then,whileitisgrounded,touchthecircuitinquestionandnotethelight.Atestlightmakesagreattoolfortestingallofthevehiclesfusesinashortamountoftime.Itcanalsobeusedtotestswitchingofcircuitssuchasignitioncoilsandfuelinjectorsaslongastheresistanceofthetestlightequalsorexceedstheresistanceoftheintendedload.,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,Agroundedtestlightcanalsobeusedtoprovideapathoflowresistanceforidentifyingpoorinsulationinsecondaryignitionwiring.Secondaryignitionwiringthatisarcingtogroundcanbedifficulttoidentifyintheshopwhencylinderpressuresarelowandresistanceacrossthepluggapisalsolow.Butmanytimes,evenwiththeengineidling,asecondarywirewillarctoagroundedtestlighttohelpidentifythespecificinsulationbreakdown.Forthistest,passthetipofthegroundedtestlightalongeachofthesecondarywireswiththeenginerunning.7.1.2DigitalVolt-Ohmmeters（DVOM）PurposeADVOMisusedbymosttechnicianstomakepinpointtestsofthecomputeranditsassociatedcircuitsandcomponents.Atypicalautomatic-scalingDVOMisshowninFigure72.ADVOMisgenerallythetoolofchoiceformakingaccuratepinpointtestsoftheelectricalcharacteristicsofacircuit.,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,Figure71Atypicalnon-poweredtestlight,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,Figure72Atypicalautomatic-scalingDVOM,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,FunctionalProcedureConnecttheblackleadtothejackmarked“Common”andtheredleadtothejackmarkedforthetypeofmeasurementneeded.BearinmindthatleadsconnectedintotheampjackseffectivelyturntheDVOMintoajumperwire.Nowsetthedialtothescaleneeded.Connecttheredandblackleadstothecircuitorcomponentthatyouneedtotest,accordingtothetypeofmeasurementbeingmade(voltage,voltagedrop,amperage,orresistance).Theredleadshouldconnecttothepointthatismostpositiveinthecircuitandtheblackleadtothepointthatismostnegative.,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,TestingAvailableVoltagewithaDVOM：ThistestingisshowninFigure73.Voltage-DropTestingwithaDVOM:Toperformavoltage-droptestofacircuit,theDVOMmustbeconnectedinparalleltothecircuitry.Thisparallelconnectioncomparesthedifferencebetweenthetwovoltagevaluesanddisplaystheresults(Figure74).ThisdifferenceistheamountofvoltagedropthathasoccurredbetweenthetwopointswheretheDVOMsleadsareconnected.,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,Figure73Availablevoltagetest,Figure74Positive-sidevoltage-droptest.A0.042-Vreadingindicatesthatinsulatedcircuitresistanceisacceptable.,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,UsingVoltage-DropTeststoIdentifyIntermittentProblemswithintheCircuitry:Itshouldbenotedthatvoltage-droptestingcanbeusedtoidentifyexcessiveunwantedresistanceincircuitsthatareexperiencingintermittentsymptoms,evenwhenthesymptomsdonotappeartobepresent.Thisisbecauseascircuitconditionschange(coolingoff,forexample),thesymptommayseemtodisappear,butinfacttheexcessiveresistancedoesnottotallydisappear.Itonlydecreasestoavaluethatallowsthecircuittobeginoperatingagain.Asaresult,theexcessiveresistancecanstillbeidentifiedbyavoltage-droptest,evenwithnoapparentsymptompresent.Themeasuredvoltagedropwillnotbeasexcessiveaswhenthesymptomispresent,butitwilllikelystillbeabovethemaximumspecificationsallowed.,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,MeasuringAmperage:Anammeterisusedtomeasurethecurrentflowinginacircuit.Therearetwotypes:theconventionaltypeandtheinductivetype.Theconventionaltypemustbeputinseriesaspartofthecircuit(Figure75).Theinductivetypehasaninductiveclampthatclampsaroundaconductorinthecircuittobetested(Figure76).,Chapter7CommonSpecialServiceToolsandEquipments7.1FunctionsofDiagnosticEquipments,Figure75Ammeterconnectedinseriesaspartofacircuit.,Figure76DVOMusedwithanampclamptoperformanon-intrusivecurrentdrawtest.Iftheoutputoftheampclampislabeledas“1mV/amp