杨四军武科大教授单元五汽车电气设备(课件)-《汽车专用英语 第三版》同步教学 （人交版）

汽车商标汽车及其历史汽车发动机汽车底盘单元一单元二单元三单元四汽车电气设备汽车车身汽车使用说明书及维修手册汽车检测与维修设备单元五单元六单元七单元八汽车维护汽车检测与维修新能源汽车概述汽车商务接待单元九单元十单元十一单元十二

单元五

活塞连杆组故障诊断与修复汽车电气设备

学习目标

完成本学习任务后，你应该能：1.了解汽车电气设备的基本结构及其工作原理；2.掌握汽车电气设备术语的英语表达；3.对相关内容进行阅读和翻译；4.对汽车电气设备上英文单词或词汇进行辨认；5.正确完成课后练习。建议学时6

学时Text

Theelectricalsystemisoneofthebasicpartsofanautomobile.Itcangenerate,store,anddistributealltheelectricitythatautomobileneeds.Theelectricalsystemofamodernautomobileiscomposedoftwomajorparts:thepowersupplyandthecurrentconsumers.TheformerincludesthestoragebatteryandalternatorThelatterincludestheenginestartingsystem,thegasolineengineignitionsystemandotherelectricinstallments.Thustheautomobileelectricalsystemcanbedividedintofourmajorcomponents：startingsystem,chargingsystem,ignitionsystemandaccessorysystem.AutomobileElectricalSystemText

StartingSystemThevehicle'sstartingsystem(Fig.5-1)isdesignedtoturnor“crank”theengineoveruntilitcanoperateunderitsownpower.Todothis,thestartermotorreceiveselectricalpowerfromthestoragebattery.Andthenthestartermotorconvertsthisenergyintomechanicalenergy,whichistransmittedthroughthedrivemechanismtotheengine'sflywheel.AutomobileElectricalSystemText

StartingSystem

AutomobileElectricalSystemFig.5-1StartingSystemText

StartingSystemAtypicalstartingsystemhasfivebasiccomponentsandtwodistinctelectricalcircuits.Thecomponentsareasfollowing:1.Battery(Fig.5-2)2.Batterycables3.Keyswitch(ofstartingswitch)4.Startermotor(Fig.5-3)5.MagneticswitchAutomobileElectricalSystemFig.5-2BatteryFig.5-3StarterMotorText

StartingSystemAbatteryisanelectrochemicaldevice.Carbatteriesareofthe12Vtype.Thebatterysuppliescurrenttoenergizethemagneticfieldofthealternatorinitially.Duringcharging,thebatterychangeselectricalenergyfromthealternatorintochemicalenergytomaintainitsstateofcharge.Whenoverloaded,thebatteryandthegeneratorworktogethertopowerthevehicle.Thebatteryalsoactsasa“shockabsorber”absorbingtheoverloadvoltagetostabilizealternatorvoltageoutput.Itisusedtosupplycurrentforstartingthecar.Uponstarting,thegeneratorwillrechargethebattery.AutomobileElectricalSystemText

StartingSystemTheelectromagnaticswitchofthestartingsystemisusedtocontrolthestartingcircuittomakeitswitchofforon.Theswitchcanbeasfollowing:1.Relaywhichusestheelectromagneticfieldofacoiltoattractanarmatureandclosethecontactpoints.2.Solenoidwhichusestheelectromagneticfieldofacoiltopullaplungerintothecoilandclosethecontactpoints.AutomobileElectricalSystemText

StartingSystemThestartermotordrawsagreatdealofelectricalcurrentfromthebattery.Alargestartermotormightrequire300to400amperesofcurrent.Thiscurrentflowsthroughtheheavy-gaugecableswhichconnectthebatterytothestarter.Thedrivercontrolstheflowofthiscurrentbyusingthestartingswitch.However,ifthewireswereroutedfromthebatterytothestartingswitchandthenontothestartermotor,thevoltagedropcausedbyresistanceinthewireswouldbetoogreat.Toavoidthisproblem,thesystemisdesignedwithtwoconnectedcircuits:thestatercircuitandthecontrolcircuit.AutomobileElectricalSystemText

StartingSystemThestartermotorconvertselectricalenergyfromthebatteryintomechanicalenergytoturntheengine.Itdoesthisthroughtheinteractionofmagneticfields.Whencurrentflowsthroughstatorwinding,amagneticfieldisformedaroundtheconductor.Alargequantityofcurrentgoesthroughthestarterrotorandgeneratesenoughtorquetoturntheenginecrankshaft.AutomobileElectricalSystemText

ChargingSystemThechargingsystemusestherotationoftheenginetocreateelectricity.Theelectricityrechargesthebatteryandprovidespowertooperatethevariousvehicleelectricalsystems.ThemodernchargingsystemconsistsoftheACgeneratorandvoltageregulator.TheACalternator(Fig.5-4),knownasgenerator,isabelt-drivenelectromagneticdivice,whichconvertstheengine'smechanicalenergyintoelectricalenergyandrechargesthebattery.Aftertheengineisstarted,thealternatorproduceselectricitytomeettheneedsofthevehicleandtokeepthebatterycharged.Thisistheprimaryjobofthealternator.AutomobileElectricalSystemText

ChargingSystem

AutomobileElectricalSystemFig.5-4ACAlternatorText

ChargingSystemInordertoreducethealternatoroutputvoltage,avoltageregulator(Fig.5-5)mustbeused.Itcontrolstheoutputvoltageofgeneratorbyadjustingthesizeofthegeneratorexcitationcurrent.Thiscontrolsthestrengthbyreadingvoltageoutputfromthealternator.Iftheoutputvoltagebecomestoohigh,theregulatorreducesfieldstrength.Iftheoutputvoltagedrops,theregulatorincreasesfieldstrength.Moreover,theregulatorcanbemainlydevidedintotwokinds:theelectromechanicalvoltageregulatorandtheelectronicvoltageregulator.AutomobileElectricalSystemText

ChargingSystem

AutomobileElectricalSystemFig.5-5VoltageRegulatorText

ChargingSystemOldervoltageregulatorsusecontactpointsthatareoperatedbyelectromagneticcoils.Theywerecalledelectromechanicalvoltageregulators.However,allvehiclesmadewithinthelast15yearsuseanelectronicregulator.Theelectronicvoltageregulatorusespowertransistors,integratedcircuits,diodes,andothersolidstatepartstocontrolalternatoroutputvoltage.Itcanavoidcontactstuck,rustorwear,withhighregulationaccuracyandlonglife,lightinweightandarewidelyusedtoday.AutomobileElectricalSystemText

IgnitionSystemThepurposeoftheignitionsystem(Fig.5-6)istoprovideanelectricsparktothecorrectcylinderattherighttimetoignitethefuel-airmixture.Mixedgasburnsandproducestremendousenergy,promotesdownwardmotionofthepistonandrotatestheenginecrankshaft.Theignitionsystemhastwotaskstoperform.First,itmustcreateavoltagehighenough(20,000V)toarcacrossthegapofasparkplug,thuscreatingasparkstrongenoughtoignitethefuel-airmixtureforcombustion.Second,itmustcontrolthetimingofthesparksothatitoccursattheexactrighttimeandignitedcombustiblemixtureaccordingtothefiringorderincylinder.AutomobileElectricalSystemText

IgnitionSystem

AutomobileElectricalSystemFig.5-6IgnitionSystemText

IgnitionSystemTheignitionsystemisdividedintotwosections：theprimarycircuitandthesecondarycircuit.Theprimarycircuit,thelow-voltagesideofthesystemcontrolsthesecondarycircuit,whichisthehigh-voltagesideofthesystem.Thefollowingarethebasicpartsoftheprimaryignitioncircuit:1.Batteryandalternator.Theysupplythelowvoltage(12V)usedtooperatetheprimarycircuit.2.Ignitionswitch.Key-operatedswitchisusedtofeedbatteryvoltagetotheprimarycircuit.3.Primarywires.Low-voltagewiresareusedtoconnecttheelectricalcomponentsoftheprimarycircuit.AutomobileElectricalSystemText

IgnitionSystem4.Ignitioncoilprimarywinding.Currentflowthroughthecoilproducesanelectromagneticfield,whichisusedtoinduceahighvoltageinthesecondarycoil.5.Breakerpoint.Itisusedtoopenandclosetheprimarycircuit.Thefollowingarethebasicpartsofasecondaryignitioncircuit:1.Ignitioncoilsecondarywinding.Ithasahighvoltage(40,000Vormore)inducediniteachtimetheprimarymagneticfieldcollapses.2.Coilwire.Itisaheavilyinsulatedwirethatfeedshighvoltagefromtheignitioncoiltodistributorcap.3.Distributorrotor.Itoperatesinconjunctionwiththedistributorcaptodistributethehighvoltagefromtheignitioncoiltotheindividualsparkplugwiresinthefiringorder.AutomobileElectricalSystemText

IgnitionSystem4.Distributorcap.Itisaninsulatedcapthattransfershighvoltagefromthedistributorrotortosparkplugwires.5.Sparkplugwire.Itisaheavilyinsulatedwirethatcarrieshighvoltagefromthedistributortothesparkplugs.6.Sparkplug.Itprovidestheairgapwithinthecombustionchamberforthehighvoltagetoarcacross,thusignitingthefuel-airmixture.AutomobileElectricalSystemText

IgnitionSystemAtpresent,therearethreedistincttypesofignitionsystems.Themechanical(conventional)ignitionsystemwasusedpriorto1975.Itwasmechanicalandelectricalandusednoelectronics.Theelectronicignitionsystemstartedfindingitswaytovehiclesproducedduringthemid-1970s.Theninordertoimprovetheignitioncontrolandreliability,andreduceengineemissions,tothemid-1980swithoutdistributorignitionsystemstartsapplyingtoautomobile.Thissystemwasalwayscomputorcontrolledandcontainednomovingparts,soreliabilitywasgreatlyimproved.AutomobileElectricalSystemText

AccessorySystemItisuniversallyknownthattheelectricalsystemsupplieslightinganddrivingpowerfortheautomobile.Therefore,lighting,horns,instrumentalpanelandwarningsystemsareincludedintheaccessorysystem.Herewewillattachgreatsignificancetothelightingsystemandwarningdevices.Thelightingsystemcomprisesofvariouslightingandsignalingdevicesorcomponentsfixedtothefront,sidesandrearofthevehicle,whichhasmultipleusesandfunctions.Firstandforemost,itprovidesilluminationforthedriverofavehicletodrivesafelyindark.Secondly,automobilelightsenhancethevisibilityofanautomobile.Atlast,automobilelightsactasthewarningsignals.Theyshowcaseinformationaboutthepresence,position,size,speedanddirectionofanautomobile.What'smore,auxiliarylights,headlights,taillights,sidelights,interiorlight,lightaccessoriesarecomponentsoftheautomobilelightingsystem.AutomobileElectricalSystemText

AccessorySystemAwarningdeviceisanalarmsystemremindingthedriverafuturedanger.Itspurposeistoremindthedriverofthewarningsystemtoprepareforthedangerandactaccordinglytomitigateagainstoravoidit.Thevehiclewarningsystemfurthercomprisesawarningunitwhichcontainsareceiver,asoundgenerator,andwarninglights.Whenadriverisfacedwithapotentiallydangeroussituationandinstinctivelygripsthesteeringwheelharder,thiscausesthevehiclewarningsystemtotransmitsignalstothereceiverinthewarningunitoftheinitiatingvehicleaswellasthereceiversinthewarningunitsofothervehicleswithinapredetermineddistance.Thetransmittedsignalcausesthewarninglighttoflashandgivethewarningsound，whichisgeneratedfromthewarningunitineachofthevehiclesreceivingthetransmittedsignal.AutomobileElectricalSystemText

AccessorySystemInshort,inrecentyears,automotiveelectricalsystemhaschangedalot.Variousauxiliaryelectricaldevicesareusedinmoderncars,suchasair-conditioningsystem,phones,televisions,radios,CDandDVDplayerswithsurroundingsoundsystem,electricdoorlocksandsoon.AutomobileElectricalSystem参考译文电气系统是汽车最主要的部分之一。它可以发电、蓄电，并为汽车电气设备提供所需电能。电气设备由电源和用电设备两大部分组成。前者包括蓄电池和发电机，后者包括发动机的起动系统、汽油机的点火系统和其他用电装置。因而，汽车电气系统可以分为四大主要组成部分：起动系统、充电系统、点火系统和辅助系统。起动系统汽车的起动系统（图5-1）用于转动发动机曲轴直到发动机能依靠自身动力进行工作。为了做到这一点，起动机必须从蓄电池得到足够的电能。起动机从蓄电池得到电能，再将这部分电能转化成机械能通过驱动机构传到发动机曲轴飞轮上。汽车电气系统参考译文起动系统

汽车电气系统图5-1起动系统参考译文起动系统一般的起动系统具体以下5个基本部件和两套不同的电路，这些部件是：1.蓄电池（图5-2）；2.蓄电池导线；3.起动开关；4.起动机（图5-3）；5.电磁开关。汽车电气系统图5-2蓄电池图5-3起动机参考译文起动系统蓄电池是一种电化学设备。汽车使用的蓄电池的电压为12V。蓄电池为交流发电机最初的励磁提供电流。在充电时，蓄电池将发电机输出的电能转化为化学能储存在蓄电池中。当过载时，蓄电池与发电机共同为车辆提供电能。蓄电池还起到“减振器”（吸收过载电压）的作用，使发电机的输出电压稳定。蓄电池只为汽车起动提供电能，起动后发电机就为蓄电池充电。起动系统的电磁开关用于控制起动电路断开或接通。开关形式如下：1.继电器：利用线圈产生磁场吸引衔铁并闭合触点。2.电磁线圈：利用线圈产生磁场拉动柱塞进入线圈并闭合触点。起动机需要蓄电池提供强大的电流。一台大型的起动机需要300~400A的电流。电流通过大容量电缆，将蓄电池连接到起动机上。驾驶员通过起动开关来控制起动电流。但如果用导线将蓄电池电流通过起动开关直接连接到起动机上，那么在导线上产生的电压降就会过大。为了避免这种情况，起动系统就设计了两套电路：起动电路与控制电路。汽车电气系统参考译文起动系统起动机将蓄电池的电能转化为发动机起动的机械能。它是利用电磁互感的原理制成的。当电流通过定子绕组，在其周围就会产生磁场。大量电流通过起动机的转子，就会产生足以让发动机曲轴转动的力矩。

充电系统充电系统通过发动机的转动来发电。所发的电用来为蓄电池充电并为各种电气设备的运行提供电能。现代充电系统包含交流发电机和电压调节器。交流发电机（如图5-4所示），简称为发电机，是一个用皮带传动的电磁装置，它将发动机的机械能转化为电能为蓄电池充电。当发动机起动，发电机就发电来满足车辆的行驶需要并保持为蓄电池充电。这就是发电机的主要工作。汽车电气系统参考译文

充电系统

汽车电气系统图5-4交流发电机参考译文

充电系统为了降低发电机的输出电压，就需要用到电压调节器（图5-5）。它通过调节发电机励磁电流的大小来控制发电机的输出电压。如果输出电压过高，调节器就减小励磁电流。如果输出电压过低，调节器就增加磁场强度。此外，调节器主要分为两种：电磁电压调节器和电子电压调节器。汽车电气系统图5-5电压调节器参考译文

充电系统老式电压调节器是利用电磁线圈来控制的触点式电压调节器，它们被称为电磁电压调节器。但是，最近15年制造的汽车上使用的都是电子电压调节器。电子电压调节器通过控制晶体三极管、集成电路、二极管和其他固体部件来控制发电机的输出电压。它能避免触点卡住、生锈或磨损；调节精度高、重量轻、寿命长，因而被广泛使用。汽车电气系统参考译文

点火系统点火系统（图5-6）的作用是在适当的时刻把电火花提供给汽缸，点燃空气燃油混合气。混合气燃烧能产生巨大能量，推动活塞向下运动并带动曲轴旋转。点火系统要满足两个基本要求：首先，点火系统必须产生足够高（20000V以上）的点火电压击穿火花塞间隙，从而使火花塞处的电火花强劲有力去点燃混合气体；其次，它必须控制点火时机，使其发生在恰当的时候，并按汽缸的点火顺序点燃可燃混合气。汽车电气系统图5-6点火系统参考译文

点火系统点火系统分为两条回路：初级和次级。初级回路是系统的低压端，并控制着次级回路，而次级回路是系统的高压端。以下是初级回路的基本组成部分：1.蓄电池和发电机。它们提供低电压（12V）让低压电路正常工作。2.点火开关。通过点火开关的控制，将蓄电池电压提供给初级电路。3.初级导线。初级导线为低压导线，用来连接初级回路的各个部件。4.点火线圈初级绕组。电流通过线圈时产生一个电磁场，用来在次级线圈中产生高电压。5.断电器触点。用来断开或接通初级电路。汽车电气系统参考译文

点火系统以下是次级回路的基本组成部分：1.点火线圈次级绕组。当初级回路的电磁场消失时，产生一个高电压（40000V或更高）。2.中央高压线。采用绝缘性能很好的导线。将高电压从点火线圈分配到需要点火的火花塞导线上。3.分电器分火头。它的作用是与分电器盖相连，将高电压从点火线圈分配到需要点火的火花塞导线上。4.分电器盖。此盖为绝缘性的，确保高压电从分火头传输到火花塞导线上。5.火花塞导线（分缸高压线）。采用绝缘性能很好的导线，将高电压从分电器传输到火花塞。6.火花塞。在燃烧室里提供空气间隙，确保高电压形成电弧，从而点燃混合气。汽车电气系统参考译文

辅助系统众所周知，电气系统还要为汽车辅助用电设备供电。辅助系统包括照明、喇叭、仪表盘和警告系统等。这部分将着重讲解照明系和报警装置。照明系统是一个包括了各种固定在汽车前部、侧部和后部的用于照明和信号的装置或部件，它具有多种用途和功能。首先，它为汽车驾驶员在夜间安全行车提供照明。其次，汽车车灯提高了汽车前进时前方的能见度。最后，汽车车灯还能担任警告信号。它们展示了汽车的存在、位置、大小、速度和方向等信息。其中，汽车照明系统包含辅助光、头灯、尾灯、侧记、室内装饰灯和光配件等零部件。汽车电气系统参考译文

辅助系统报警装置是一种用于提醒驾驶员防范危险的报警系统。它的作用是通过报警装置提醒驾驶员对危险提早做准备并因此减缓或避免危险带来的伤害。汽车报警装置包括一整套警告部件，主要有一个接收装置，发声器和警告灯。当驾驶员面对一种潜在的危险状况时，他会本能地握紧转向盘，这种反应会导致汽车警告系统将信号传递给起动的汽车的警告装置的接收器，以及传递给在一定距离内其他车辆的接收器。传递的信号转变为报警灯的闪烁并给予警告响声，这些是由警告装置接收到警告信号产生的反应。总之，最近几年，汽车电气系统变化很大。在现代新型汽车中还使用了其他各种电气辅助部件，如空调系统、电话、电视、收音机、带有环绕声音响的CD和DVD机、电控门锁等。汽车电气系统ReadingMaterialAlmosteveryautomobilemanufacturerisusedtotestingthesystem'soperationofthecarwhenitleavestheassemblyline.Specialautomotivediagnosticscannersareavailableforaccessinginformationfromcomputerizedvehiclesthroughconnectionstothisserialdatalink.Informationoninputsandoutputstothecomputer,suchasfaultcodes,coolanttemperature,RPM,timingretard/advance,vacuum,manifoldabsolutepressure,andoxygensensoroutputcanberetrievedusingthesedevices.Thesekindsofinformationcanbedisplayedonascreen,shownasadigitalreadout,orprintedonapieceofpaperandusedfortroubleshootingthesystem.

SystemDiagnosisReadingMaterialMostcomputerizedautomotivecontrolsystemsareequippedwithbuiltinself-diagnosticsystemswhichconductamultitudeoftestsofthesystem.Thebasicmicrocomputerself-diagnosissystemisdesignedtomonitortheinputandoutputsignalsofthesensorsandactuators,andtostoreanymalfunctionsinitsmemoryasatroublecode.Generally,checksaremadeforopen,shortcircuitsandillogicalsensorreadings.

SystemDiagnosisReadingMaterialTheelectroniccontrolsystemisbasicallycomposedofthecomputerorelectroniccontrolmodule,enginewiringh