《汽車專業(yè)英語》課件第4章

PARTⅣAUTOELECTRICPARTS4.1StartingSysten4.2IgnitingSystem4.3LightingCircuit4.4TheAirConitioningandHeatingSystem

4.5FutureCarPART?ⅣAUTOELECTRICPARTS學習目標通過本章的學習，你應(yīng)當能夠：掌握與汽車電器有關(guān)的專業(yè)術(shù)語、專業(yè)詞匯和縮略語。掌握汽車電器英語的習慣表達方法。能查閱汽車電器的有關(guān)英文資料。能借助字典翻譯汽車電器方面的文章。4.1StartingSystem

Automobileenginesarenotself-starts.Inordertostartthem,theenginecrankshaftmustbeturnedover.Todothis,thestartermotorreceiveselectricalpowerformthestoragebattery.Thestartermotorthenconvertsthisenergyintomechanicalenergy,whichittransmitsthroughthedrivemechanismtotheengine’sfly-wheel.

Thestartermotordrawsagreatdealofelectricalcurrentfromthebattery.Alargestartermotormightrequire300to400amperesofcurrent.Thiscurrentflowsthroughtheheavy-gaugecablesthatconnectthebatterytothestarter.

Thedrivercontrolstheflowofthiscurrentusingthestartingswitch.However,ifthecableswereroutedfromthebatterytothestartingswitchandthenontothestartermotor,thevoltagedropcausedbyresistanceinthecableswouldbetoogreat.Toavoidthisproblem,thesystemisdesignedwithtwoconnectedcircuits:thestartercircuitandthecontrolcircuit.

Thestartingsafetyswitch

Thestartingsafetyswitchisalsocalledaneutralstartswitch.Itisanormallyopenswitchthatpreventsthestartingsystemfromoperatingwhentheautomobile’stransmissionisingear.Ifthecarhasnostartingsafetyswitch,itispossibletospintheenginewiththetransmissioningear.

Thiswillmakethecarlurchforwardorbackwardwhichcouldbedangerous.Safetyswitchesorinterlockdevicesareusedwithallautomatictransmissionsandonmanylate-modelcarswithmanualtransmissions.Thesafetyswitchcanbeanelectricalswitchthatopensthecontrolcircuitifthecarisingear.Itcanalsobeamechanicalinterlockdevicethatwillnotlettheignitionswitchturntostartifthecarisingear.

MagneticSwitch(RelaysandSolenoids)

Amagneticswitchinthestartingsystemallowsthecontrolcircuittoopenandclosethestartercircuit.Theswitchcanbea:

1.?Relaywhichusestheelectromagneticfieldofacoiltoattractanarmatureandclosethecontactpoints.

2.?Solenoidwhichusestheelectromagneticfieldofacoiltopullaplungerintothecoilandclosethecontactpoints.Theplunger’smovementcanalsobeusedtodoamechanicaljob,suchasshiftingthestartermotorgearinasolenoid-actuateddrive.

StarterMotor

Thestartermotorconvertselectricalenergyfromthebatteryintomechanicalenergytoturntheengine.Itdoesthisthroughtheinteractionofmagneticfields.Whencurrentflowsthroughaconductor,amagneticfieldisformedaroundtheconductor.Iftheconductorisplacedinanothermagneticfield,thetwofieldswillbeweakenedatonesideandstrengthenedattheotherside.Anautomotivestartermotorhasmanyconductorsandusesalotofcurrenttocreateenoughrotationalforcetocranktheengine.

Fig.4.1.1showsacutawayviewofastartermotor.Thearmatureisthecollectionofconductorsthatwillspintocranktheengine.Thestarterdrivegearismountedonthearmatureshaft.Thepolepiecesarethestationarymagneticfields.Themotorhousingenclosesthearmatureandpolepieces,holdsthebearingsthatsupportthearmatureshaft,andprovidestheterminalsforconnectingthemotortotherestofthestartingsystem.Fig.4.1.1StartermotorTechnicalWords

crankn.;vt.;adj. 曲柄；把……彎成曲柄狀； 不正常的

flywheeln. 飛輪

component

n.;adj. 組成部分，部件；組成的

distinctadj. 獨特的，明顯的

cablen. 電纜，鋼絲纜

amperen. 安培

spinv.;n. 使旋轉(zhuǎn)；旋轉(zhuǎn)，自旋

lurchvi.;n. 突然傾斜；側(cè)傾

interlockvi.;n. (使)聯(lián)鎖，聯(lián)鎖裝置

relayn.;vt.繼動器，繼電器；傳達，轉(zhuǎn)播

armaturen. 電樞，轉(zhuǎn)子，銜鐵

applicationn. 用法，用途，應(yīng)用

interactionn. 相互作用

pinion

n.

【機】小齒輪

plungern.柱塞

brushn.;vt.刷子，電刷；刷，擦

commutatorn. 轉(zhuǎn)換開關(guān)，轉(zhuǎn)換器，整流子

terminaladj.;n.末端的；端子

stationaryadj.不動的，靜止的PhrasesandExpressions

startingsystem 啟動系統(tǒng)

keyswitch 鑰匙開關(guān)

batterycable 蓄電池導(dǎo)線

magneticswitch 電磁開關(guān)

startermotor 啟動機

startingsafetyswitch 安全啟動開關(guān)NotesontheText

1．Thestartermotorthenconvertsthisenergyintomechanicalenergy,whichittransmitsthroughthedrivemechanismtotheengine’sfly-wheel.接著啟動機將這部分電能轉(zhuǎn)化成機械能，通過驅(qū)動機構(gòu)傳到發(fā)動機曲軸飛輪上。

2．However,ifthecableswereroutedfromthebatterytothestartingswitchandthenontothestartermotor,thevoltagedropcausedbyresistanceinthecableswouldbetoogreat.如果導(dǎo)線從蓄電池經(jīng)過啟動開關(guān)連接到啟動機上，在導(dǎo)線上會產(chǎn)生大量的電壓降。

3．Relaywhichusestheelectromagneticfieldofacoiltoattractanarmatureandclosethecontactpoints.繼電器：利用吸引線圈產(chǎn)生磁場，吸引銜鐵并閉合觸點。

4．Iftheconductorisplacedinanothermagneticfield,thetwofieldswillbeweakenedatonesideandstrengthenedattheotherside.當這樣的導(dǎo)體被放置到另一個磁場中時，兩個磁場將有一側(cè)被加強而另一側(cè)被減弱。

5．Themotorhousingenclosesthearmatureandpolepieces,holdsthebearingsthatsupportthearmatureshaft,andprovidestheterminalsforconnectingthemotortotherestofthestartingsystem.啟動機外殼內(nèi)裝入電樞與磁極，外殼兩端的軸承支撐電樞轉(zhuǎn)軸，并將啟動機與啟動系統(tǒng)支架相連。Exercises

Ⅰ.?AnswerthefollowingquestionsinEnglish.

1．Whatisthecomponentofatypicalstartingsystem?

2．Howmuchamperesdoesalargestartermotorrequire?

3．Whyisthesystemdesignwithtwoconnectedcircuits:thestartercircuitandthecontrolcircuit？

4．WhatistheactionoftheStartingSafetySwitch？

5．Whatisthestructureofstartermotor？

Ⅱ.?TranslatefollowingexpressionsintoEnglish.

1．啟動機

2．電磁開關(guān)

3．鑰匙開關(guān)

4．電磁互感原理

5．電樞轉(zhuǎn)軸

Ⅲ.?TranslatefollowingsentencesintoEnglish.

1．啟動系統(tǒng)具有5個基本零件和兩套不同的電路。

2．安全啟動開關(guān)用來防止在汽車掛擋后再啟動發(fā)動機。

3．啟動系統(tǒng)的電磁開關(guān)用于控制電路斷開或接通。

4．啟動機是利用電磁互感的原理制成的。

5．啟動機的磁極產(chǎn)生穩(wěn)定磁場。

Ⅳ.?Studythefollowinglistandname.

1．motor-alternator,motor-armature,actuatingmotor,asynchronousmotor,cagemotor,unitmotor

2．startingcrankjaw,startingcurrent,startingfluid,startinggear,startingignitionvoltageReadingMaterial

WhentoReplaceYourAutomobileStarterMotor

Ifyoutrytostartyourvehicleandtheengineturnstooslowly,ornotatall,thestarterorstartersolenoidmayneedtobereplaced.Beforeyougothroughthestepsofreplacingpartsalwaysdoafewtroubleshootingtechniquestomakesurethatthestarterorthesolenoidistheproblem.Becausethestarterandthesolenoidworktogetheritsalwaysbesttoreplacethemtogether.

StarterMotorTroubleshootingTips:

1．Checkthebatterycablesandterminalsforcorrosion.

2．Cleanthecorrosionandreplacethebatteryorcablesif

needed.

3．Checkthewirestothestarterandthesolenoidforcracks,corrosion,orbreakage.

Makesureyourbatteryischargedenoughtoperform

startingfunctions.Note:yourinstrumentlightsanddome

lightsmaycomeonbutyourbatterymaystillnothave

enoughpowertostartthecar.

Rememberelectricalpartsfailmostlyinparttotimeandusagenotbecauseofwearandtearlikemechanicalparts.Andthedamageismostlyintheinternalelectricalwiring,sosomefailurescannotbenoticedfromanoutsideinspection.Ifyouhavedonethetestslistedaboveandarestillhavingproblemsstartingyourvehicle,thenherearethestepstofollowforproperinstallationofyourautomobile'sstartermotor.

StarterMotorInstallationSteps:

Gatherthenecessarytoolsneededsuchaswrenches,sockets,screwdriverandpliers.

1．Placethevehicleonrampsorjackupthefrontandsupportwithjackstands.Itisveryimportanttoblocktherearwheelstokeepthecarstationaryduringthisprocedure.Neverworkunderavehiclenotsupportedproperly.

2．MakesureignitionisOFFandtheremovethenegative(ground)batterycablefromthebattery.

3．Notethelocationofallwiresbeforeremovaltomakeforeasierconnection.

4．Removethelargestartercablegoingtothebatteryatthestarterlocation.

5．Removeanyotherwiresattachedtothesolenoid.

6．Removethestarterattachingbolts(usuallytherearetwoorthree).

7．Removeanysupportingbracketsthatholdsthestarter.

8．

Dropthestarterdownawayfrom?the?car.?Onsomecarsyoumayhavetoturnthewheelstooneside,removetheidlerarm,removeorloosentransmissionoilcoolerlines,exhaustpipes,orgroundstrapstogiveyouenoughclearancetogetthestartermotorawayfromthecar.

9．Installthenewstarterinthereverseorderofremoval.

10．Reconnectbatterycablesandotherwirestosolenoid.

11．Placeoldstarterinthenewstarterboxforpropercorereturn.

Ifyouhavefollowedthesesimplestepsthenyoushouldhaveanewautomobilestartermotorinstalledonyourvehiclefortroublefreestarting.Ifyouhaveanyfurtherquestionsorarestillhavingadditionalproblemsfeelfreetocalloremailourfriendlytechnicalstaff.4.2IgnitingSystem

ReachHeatrangeThreadSeatAirgapFig.4.2.1SparkplugTheignitionsystemonaninternalcombustionengineprovidesthesparkthatignitesthecombustibleair/fuelmixtureinthecombustionchamber.Thesparkconsistsofanelectricarcproducedbyapplyingahighvoltageacrosstheelectrodesofasparkplug.Thissparkmustoccurneartheendofthecompressionstroke,asthepistonapproachestopdeadcenter(TDC).Thecylindersmustfireintheproperorderandatapreciseinstant,dependingonenginespeed,loadandtemperatureconditions.Fig.4.2.1Sparkplug

Asparkplugconsistsofapairofelectrodes(SeeFig.4.2.1),calledthecenterandgroundelectrodes,separatedbyagap.Asparkisproducedbyapplyingahighvoltage(fromapproximately6kVto40kV)betweenthecenterelectrodeandground.Oncethearcisstarted,amuchlowervoltageisrequiredtosustainthearctoignitetheair/fuelmixture.

Theignitionsystemisdividedintotwocircuits:theprimaryandthesecondary.Theprimarycircuitisthelow-voltagesideofthesystemandcontrolsthesecondarycircuit,whichisthehigh-voltagesideofthesystem.

Thefollowingarethebasicpartsoftheprimaryignitioncircuit:

1.Batteryand/oralternator.Suppliesthelowvoltage(12V)usedtooperatetheprimarycircuit.

2.?Ignitionswitch.Key-operatedswitchusedtofeedbatteryvoltagetotheprimarycircuit.

3.Primarywires.Low-voltagewiresusedtoconnecttheelectricalcomponentsoftheprimarycircuit.

4.Ignitioncoilprimarywinding.Currentflowthroughthecoilproducesanelectromagneticfield,whichisusedtoinduceahighvoltageinthesecondarycoil.

5.Electroniccontrolunit.Containsaswitchingtransistorcontrolledbyaspeedsensorandisusedtoopenandclosetheprimarycircuit.

6.Speedsensor,orpickup.Producesapulsatingvoltagethatsignalsthegenerationofanignitionspark.

Thefollowingarethebasicpartsofasecondaryignitioncircuit:

1.Ignitioncoilsecondarywinding.Hasahighvoltage(40,000?Vormore)inducediniteachtimetheprimarymagneticfieldcollapses.

2.Coilwire.Heavilyinsulatedwirethatfeedshighvoltagefromtheignitioncoiltodistributorcap.

3.Distributorrotor.Operatesinconjunctionwiththedistributorcaptodistributethehighvoltagefromtheignitioncoiltotheindividualsparkplugwiresinthefiringorder.

4.Distributorcap.Insulatedcapthattransfershighvoltagefromthedistributorrotortosparkplugwires.

5.Sparkplugwire.Heavilyinsulatedwirethatcarrieshighvoltagefromthedistributortothesparkplugs.

6.Sparkplug.Providestheairgapwithinthecombustionchamberforthehighvoltagetoarcacross,thusignitingtheair/fuelmixture.

Thebasicoperationoftheignitionsystemwiththeignitionswitchclosedandtheenginestarted,isasfollows:

1.ThetriggerwheelrotateswithengineRPMsandcausesthespeedsensor,orpickupcoil,toproducetriggeringvoltagepulsesthatcorrespondtoenginespeedandpistonposition.

2.Theelectroniccontrolunitallowscurrenttoflowthroughtheignitioncoilprimarywindinguntilitsensesatriggeringvoltagepulsefromthespeedsensor,orpickupcoil.

3.Eachtriggeringvoltagepulseactuatestheelectroniccontrolmoduletoopenthecircuittotheignitioncoilprimarywinding,causingthemagneticfieldtocollapsequicklyandinduceahighvoltageinthesecondarywinding.

4.Thehighsecondaryvoltagetravelsfromthecoilwiretothedistributorrotorandcapandthenontofirethesparkplugofthecylinderthatisontheproperstrokeforignitingtheair/fuelmixture.TechnicalWords

ignition n. 點火

spark n. 火花

arc n. 電弧

gap n. 間隙

battery n. 蓄電池

alternator n. 發(fā)電機

winding n. 卷繞著的線，線圈

pickup n. 拾波線圈，感應(yīng)線圈

pulsating adj. 脈動的，脈沖的

collapse vt. 倒塌，崩潰

distributor n. 分電器

rotor n. 轉(zhuǎn)子，(分電器的)分火頭

trigger vt. 觸發(fā)，引起

actuate v. 激勵，促使PhrasesandExpressions

dependon 取決于

centerelectrode 中心電極

groundelectrode 旁電極

bedividedinto (被)分為

primarycircuit 初級回路

secondarycircuit 次級回路

ignitioncoil 點火線圈

distributorcap 分電器蓋

sparkplug 火花塞

combustionchamber 燃燒室

triggerwheel 觸發(fā)葉輪

NotesontheText

1．Thecylindersmustfireintheproperorderandatapreciseinstant,dependingonenginespeed,loadandtemperatureconditions.各缸的點火應(yīng)該有合適的順序和精確的時間，這取決于發(fā)動機的轉(zhuǎn)速、負荷和溫度。

2．Theignitionsystemisdividedintotwocircuits:theprimaryandthesecondary.Theprimarycircuitisthelow-voltagesideofthesystemandcontrolsthesecondarycircuit,whichisthehigh-voltagesideofthesystem.點火系統(tǒng)分為兩條回路：初級和次級。初級回路是系統(tǒng)的低壓端，并控制著次級回路，而次級回路是系統(tǒng)的高壓端。

3．Eachtriggeringvoltagepulseactuatestheelectroniccontrolmoduletoopenthecircuittotheignitioncoilprimarywinding,causingthemagneticfieldtocollapsequicklyandinduceahighvoltageinthesecondarywinding.每個觸發(fā)電壓脈沖促使電子控制單元斷開點火線圈初級繞組的電流，使得電磁場迅速消失，在次級繞組中產(chǎn)生一個高電壓。

4．Thehighsecondaryvoltagetravelsfromthecoilwiretothedistributorrotorandcapandthenontofirethesparkplugofthecylinderthatisontheproperstrokeforignitingtheair/fuelmixture.次級的高電壓從線圈里，經(jīng)過分火頭和分電器蓋，到達處于合適行程的氣缸的火花塞，點火，點燃混合氣。Exercises

Ⅰ.?AnswerthefollowingquestionsinEnglish.

1．Whatisthepurposeoftheignitionsystem?

2．Whythereisalowervoltagerequiredtosustainthearc?

3．Whatisthefunctionoftheignitionswitch?

4．Whatdothevoltagepulseswhichproducedinthespeedsenorcorrespondto?

5．Whendoesahighvoltageinduce?

Ⅱ.?TranslatefollowingexpressionsintoEnglish.

1．火花塞

2．蓄電池和發(fā)電機

3．點火開關(guān)

4．轉(zhuǎn)速傳感器

5．分電器蓋

6．觸發(fā)電壓脈沖

Ⅲ.?TranslatefollowingsentencesintoEnglish.

1．點火系統(tǒng)的作用是在正確的時刻把電火花提供給氣缸，點燃混合氣。

2．火花由在中心電極和旁電極之間的高電壓產(chǎn)生。

3．電流通過線圈，產(chǎn)生一個電磁場，用來在次級線圈中產(chǎn)生高電壓。

4．轉(zhuǎn)速傳感器產(chǎn)生一組脈沖電壓，給點火火花的產(chǎn)生提供信號。

5．火花塞提供空氣間隙，保證高電壓的電弧通過，以點燃混合氣。

6．分火頭作用是把高電壓從點火線圈分配到需要點火的火花塞導(dǎo)線上。

Ⅳ.?Studythefollowinglistandname.

1．surfacedischargesparkplug,twin-sparkignition,spark-plugwrench,spark-plugwell,spark-plugpoints,spark-plugfouling,electronicsparkadvance,drawthespark

2．magnetoignitioncoil,high-tensionignitioncoil,distributorignitionwithignitioncoil,ballastedignitioncoil

3．dual-diaphragmvacuumadvancedistributor,distributortrack,distributorshaftadapter,distributorhousingReadingMaterialIgnitionTiming

Anoftenneglectedbutimportantareawhentuninganengineistheignitionsystem.NoIdon’tmeanharderplugs,competitioncoils,lumenitionetc.,whichonlyaffecttheefficiencyofthespark,buttheactualignitionadvancesuppliedbythedistributor.

Tunedandmodifiedengineshavedifferentadvancecharacteristicsandrequirementsfromanormalengine.Adaptingtheadvancecurvetomeettheserequirementsusingthestandardmechanicaldistributorisnotthatdifficultataskonceitisunderstood.Thisareaisoftenconsideredtobeablackart,butitisactuallyquitestraightforward.

Correctlysettingtheadvancecurveforamodifiedenginecanmakeaconsiderabledifferencetothetractabilityoftheengineaswellasensuringthattheengineisgivingofitsbestpowerwise.

Modifyingtheadvanceinthewaydescribedcanonlybedoneonanenginethatusesmechanicaladvance.Someenginesusemappedignitionwhichiselectronicallycontrolled,FordESC,EECIV,BoschK,LJetronic,Motronicareexamples.Thesearenotsuitableformodification.

Aquickandeasychecktoseeifyourdistributorhasanadvancemechanismistoremovethedistributorcap,grasptherotorarmfirmlyandtrytoturnitinaclockwisedirection.Ifitallows10orsodegreesofmovementandthenspringsback,thenitcontainsacentrifugaladvancemechanismandissuitableformodification,ifitisrocksolid,don’tmesswithit,itsmapped.

Therearetwobasicfactorsthatgovernignitiontiming:enginespeedandload.Allchangesintimingarerelatedtothesetwofactors.

Timingmustincrease,oradvance,asenginespeedincreases;itmustdecrease,orretard,asenginespeeddecreases.Timingmustdecrease,orretard,asloadincreases;itmustincrease,oradvance,asloaddecreases.

Optimumignitiontimingunderanygivencombinationofthesebasicfactorswillresultinmaximumcylinderpressure.Inturn,thisdeliversmaximumpowerwithaminimumofexhaustemissionsandthebestpossiblefueleconomy.

Whenignitiontakesplacetooearly,thecombustionpressureslowsdownthepiston.Iftimingistoofaradvanced,theincreasedcombustionpressurewillcauseanengineknock.

Whenignitiontakesplacetoolate,thepistonistoofardownonitspowerstroketobenefitfromthecombustionpressure,resultinginapowerloss.

Beforetheintroductionofcomputer-controlledtiming,mostautomotivedistributorshadtwosparkadvancemechanismstoreacttoengineoperatingchangesandalterignitiontiming:

1.Thecentrifugaladvancechangesignitiontimingtomatchenginespeedbyalteringthepositionofthedistributorcamortriggerwheelonthedistributorshaft.

2.Thevacuumadvancechangesignitiontimingtomatchengineloadbyalteringthepositionofthebreakerpointsorthemagneticpickupcoil(electronicsensor).

Thesechangesinpositionalterthetime,relativetocrankshaftposition,atwhichtheprimarycircuitisopened.

Astandardproductionenginehastorunacceptablywelloverawiderangeofoperatingconditions,poorfuel,towingoftrailers/caravansetc.andyetstilldelivergoodeconomyandflexibility.Consequentlytheengineistunedtogivegoodlowdownperformanceandwilluseconservativetimingandfuellingsettings.Italsohastocopewithpoorqualityfuelandchangesinaltitudethatcanseriouslyaffecttheenginesbehaviour.

Atunedenginegenerallyisnotdesignedtogivegoodperformancebelow2,500-3,000RPMandindeedbelowthislevel,thevolumetricefficiencyoftheengineisseriouslyaffected.Themoreextremethecamprofile,theworsethissituationbecomes.ThismeansthattheeffectivecylinderfillingatlowerRPMispoorerthanwithastandardengine.

Asexplainedearlier,intheseconditionsmoreignitionadvanceisrequiredtoovercometheslowburningofthemixture.Ifthisadvanceissuppliedbyretainingthestandarddistributorandsimplyincreasingthestatictiming,thentheoveralladvancewillbetoohighbythesamenumberofdegrees,thisisobviouslyundesirableandcanwreckyourcarefullymodifiedengine.NotincreasingthestaticadvancehoweverwillleadtoaverysluggishengineuntilquitehighRPMisreached.

Theenginespeedatwhichmaximumadvanceisreachedalsoneedstobeearlierforatunedengine,say3,500-3,800RPM,onastandardenginemaximumadvancemaynotbereacheduntilmuchlater,say4,500-5,000RPM.Thismeansthatboththeamountofadvance,andtherateatwhichitisappliedwillnotbesatisfactoryinamodifiedengineifthestandarddistributorisretainedisunmodifiedcondition.4.3LightingCircuit

Thelightingsysteminatypicalautomobileincludestheheadlight,parkinglights,direction-signallights,sidemarker,stoplights,backuplights,taillights,andinteriorlights.

MainLightingSwitch

Themainlightingswitch(sometimescalledtheheadlightswitch)istheheartofthelightingsystem.Itcontrolstheheadlights,parkinglights,sidemarkerlights,taillights,licenseplatelight,instrumentpanellights,andinteriorlights(SeeFig.4.3.1).Fig.4.3.1Themainlightingswitch

Individualswitchesareprovidedforspecialpurposelightssuchasdirectionalsignals,hazardwarningflashers,backuplights,andcourtesylights.Themainlightingswitchmaybeofeitherthe?“push-pull”or?“push-pullwithrotarycontact”?types.Atypicalswitchwillhavethreepositions:off,parking,andheadlamps.Someswitchesalsocontainarheostattocontrolthebrightnessoftheinstrumentpanellights.Therheostatisoperatedbyrotatingthecontrolknob,separatingitfromthepush-pullactionofthemainlightingswitch.

Whenthemainlightingswitchcompletesthecircuittotheheadlamps,thelowbeamlightsthewayforcitydrivingandforusewhenmeetingoncomingtrafficonthehighway.Whenthedimmerswitchisactuated,thesinglefilamentheadlampsgo?“on”，

alongwiththehighbeamofthetwofilamentheadlamps.Thenextactuationofthedimmerswitchreturnstheheadlightsystemtolowbeamsonlyonthetwofilamentlamps.

Somecarsareequippedwithanelectronicheadlightdimmingdevice,whichautomaticallyswitchestheheadlightsfromhighbeamtolowinresponsetolightfromanapproachingvehicleorlightfromthetaillightofavehiclebeingovertaken.Thedimmerswitchintheautomaticheadlampdimmingsystemisaspecialoverridetype.Itislocatedinthesteeringcolumnaspartofacombinationdimmer,horn,andturnsignalswitch.Theoverrideactionoccurswhenaslightpulltowardthedriverontheswitchleverprovideshighbeamheadlightsregardlessoftheamountoflightonthesensor-amplifier.

Forsomeyearstherehasbeendiscussionabouttheadvantagesofapolarizedheadlightsystem.Suchasystemcomprisesheadlightswhichproducepolarizedlightinaparticularplane.Thewindscreensofallcarswouldbefittedwithpolarizingglass,whichwouldbeorientedsothatglarefromanapproachingvehiclewouldbeessentiallyeliminated,whiletheforwardvisionwouldstillbekeptatthepresentlevels.

Theadvantagesthesystemappearattractive,butthepracticalproblemsofmakingthetransitionareverygreat,sinceitwouldnotbepracticaltoconvertallexistingvehiclestothistypeoflighting.Also,anybenefitswouldonlybemarginalbecauseglareitselfisnotafrequentcauseofaccidents.However,manycarsnowhaverefractingorcoloredglasstocutdownonglare.

DirectionalSignalSwitch

Thedirectionalsignalswitchisinstalledjustbelowthehubofthesteeringwheel.Amanuallycontrolledleverprojectingfromtheswitchpermitsthedrivertosignalthedirectioninwhichhewantstoturn.Movingtheswitchhandledownwilllightthe?“turnsignal”?lampsontheleftfrontandleftrearofthecar,signalingaleftturn.Movingtheswitchupwardwilllighttheturnsignallampsontheright(frontandrear),signalingarightturn.

Withtheswitchinapositiontosignalaturn,lightsarealternatelyturned?“on”?and?“off”?byaturnsignalflasher.Incorporatedinthedirectionalsignalswitchisa“l(fā)anechangeswitchmechanism”.Thisfeatureprovidesthedrivertheopportunitytosignalalanechangebyholdingtheturnleveragainstadetent,thenreleasingittocancelthesignalimmediatelyafterthemaneuveriscompleted.

StoplightSwitch

Inordertosignalastop,abrakepedaloperated?“stoplightswitch”?isprovidedtooperatethevehicle’sstoplamps.Inadditiontolightingtheconventionalrearlights,theswitchalsooperatesthecenterhigh-mountedstoplamp,whichbecamemandatoryonlatermodels.Cruisecontrolequippedvehiclesmayalsoutilizeavacuumreleasevalve.Inthiscase,boththevacuumreleasevalveandthestoplightswitchareactuatedbymovementofthebrakepedal.TechnicalWords

switch n. 開關(guān)

headlight n. 前照燈

beam n. 光束

taillight n. 尾燈

headlamp=headlight n. 前照燈

rheostat n. 變阻器，電阻箱

knob n. 鈕，按鈕，圓形把手

filament n. (細)絲，(細)線燈 絲，金屬絲

sensor n. 傳感器PhrasesandExpressions

parkinglights 停車燈

courtesylight 門控踏腳板照明燈， 禮貌燈，進出車門照明燈

mainlightingswitch 燈光總開關(guān)

sidemarkerlights 輪廓燈

licenseplatelight 牌照燈

instrumentpanellights 儀表板燈

lowbeam 近光

highbeam 遠光

dimmerswitch 變光開關(guān)

polarizedheadlight 偏振光前照燈

cutdown 減少

steeringwheel 轉(zhuǎn)向柱

lanechangeswitch 變換開關(guān)

hazardwarningflasher (燈光)危急報警閃燈器

inadditionto 除了，還有，加上

backuplight 倒車燈

fenderwell 翼子板凹坑(用于安裝前懸架 彈簧)

vacuumreleasevalve 真空釋放閥

NotesontheText

1．Whenthemainlightingswitchcompletesthecircuittotheheadlamps,thelowbeamlightsthewayforcitydrivingandforusewhenmeetingoncomingtrafficonthehighway.當燈光總開關(guān)接通前照燈線路的時候,近光燈絲點亮,為在城市道路駕駛和在高速公路上兩車交會時提供照明。

2．Also,anybenefitswouldonlybemarginalbecauseglareitselfisnotafrequentcauseofaccidents.這些益處只是次要的,因為眩目本身并不是意外事件發(fā)生的常見因素。

3．Thisfeatureprovidesthedrivertheopportunitytosignalalanechangebyholdingtheturnleveragainstadetent,thenreleasingittocancelthesignalimmediatelyafterthemaneuveriscompleted.該特征提供給駕駛員一個機會來握住轉(zhuǎn)向桿,靠向一個爪來表示一個變換信號,在操縱完之后,釋放它就可以立刻取消該信號。

4．Inordertosignalastop,abrakepedaloperated?“stoplightswitch”isprovidedtooperatethevehicle’sstoplamps.為了要表示停車,由剎車踏板操縱“制動燈開關(guān)”控制汽車的制動燈。Exercises

Ⅰ.?AnswerthefollowingquestionsinEnglish.

1．Howmanylightsarementionedintheparagraphtwo?

2．Whenshouldthedrivechangethehighbeamtolowbeam?

3．Whythepolarizedheadlightsystemisnotpopularyet?

4．Whereisthedirectionalsignalswitch?

5．Howthecruiseco