《汽車專業(yè)英語(yǔ)》課件第4章

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

4.5FutureCarPART?ⅣAUTOELECTRICPARTS學(xué)習(xí)目標(biāo)通過(guò)本章的學(xué)習(xí)，你應(yīng)當(dāng)能夠：掌握與汽車電器有關(guān)的專業(yè)術(shù)語(yǔ)、專業(yè)詞匯和縮略語(yǔ)。掌握汽車電器英語(yǔ)的習(xí)慣表達(dá)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(dú)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(dòng)器，繼電器；傳達(dá)，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(jī)】小齒輪

plungern.柱塞

brushn.;vt.刷子，電刷；刷，擦

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

terminaladj.;n.末端的；端子

stationaryadj.不動(dòng)的，靜止的PhrasesandExpressions

startingsystem 啟動(dòng)系統(tǒng)

keyswitch 鑰匙開(kāi)關(guān)

batterycable 蓄電池導(dǎo)線

magneticswitch 電磁開(kāi)關(guān)

startermotor 啟動(dòng)機(jī)

startingsafetyswitch 安全啟動(dòng)開(kāi)關(guān)NotesontheText

1．Thestartermotorthenconvertsthisenergyintomechanicalenergy,whichittransmitsthroughthedrivemechanismtotheengine’sfly-wheel.接著啟動(dòng)機(jī)將這部分電能轉(zhuǎn)化成機(jī)械能，通過(guò)驅(qū)動(dòng)機(jī)構(gòu)傳到發(fā)動(dòng)機(jī)曲軸飛輪上。

2．However,ifthecableswereroutedfromthebatterytothestartingswitchandthenontothestartermotor,thevoltagedropcausedbyresistanceinthecableswouldbetoogreat.如果導(dǎo)線從蓄電池經(jīng)過(guò)啟動(dòng)開(kāi)關(guān)連接到啟動(dòng)機(jī)上，在導(dǎo)線上會(huì)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(chǎng)，吸引銜鐵并閉合觸點(diǎn)。

4．Iftheconductorisplacedinanothermagneticfield,thetwofieldswillbeweakenedatonesideandstrengthenedattheotherside.當(dāng)這樣的導(dǎo)體被放置到另一個(gè)磁場(chǎng)中時(shí)，兩個(gè)磁場(chǎng)將有一側(cè)被加強(qiáng)而另一側(cè)被減弱。

5．Themotorhousingenclosesthearmatureandpolepieces,holdsthebearingsthatsupportthearmatureshaft,andprovidestheterminalsforconnectingthemotortotherestofthestartingsystem.啟動(dòng)機(jī)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(dòng)機(jī)與啟動(dòng)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(dòng)機(jī)

2．電磁開(kāi)關(guān)

3．鑰匙開(kāi)關(guān)

4．電磁互感原理

5．電樞轉(zhuǎn)軸

Ⅲ.?TranslatefollowingsentencesintoEnglish.

1．啟動(dòng)系統(tǒng)具有5個(gè)基本零件和兩套不同的電路。

2．安全啟動(dòng)開(kāi)關(guān)用來(lái)防止在汽車掛擋后再啟動(dòng)發(fā)動(dòng)機(jī)。

3．啟動(dòng)系統(tǒng)的電磁開(kāi)關(guān)用于控制電路斷開(kāi)或接通。

4．啟動(dòng)機(jī)是利用電磁互感的原理制成的。

5．啟動(dòng)機(jī)的磁極產(chǎn)生穩(wěn)定磁場(chǎng)。

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(diǎn)火

spark n. 火花

arc n. 電弧

gap n. 間隙

battery n. 蓄電池

alternator n. 發(fā)電機(jī)

winding n. 卷繞著的線，線圈

pickup n. 拾波線圈，感應(yīng)線圈

pulsating adj. 脈動(dòng)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(lì)，促使PhrasesandExpressions

dependon 取決于

centerelectrode 中心電極

groundelectrode 旁電極

bedividedinto (被)分為

primarycircuit 初級(jí)回路

secondarycircuit 次級(jí)回路

ignitioncoil 點(diǎn)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(diǎn)火應(yīng)該有合適的順序和精確的時(shí)間，這取決于發(fā)動(dòng)機(jī)的轉(zhuǎn)速、負(fù)荷和溫度。

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

3．Eachtriggeringvoltagepulseactuatestheelectroniccontrolmoduletoopenthecircuittotheignitioncoilprimarywinding,causingthemagneticfieldtocollapsequicklyandinduceahighvoltageinthesecondarywinding.每個(gè)觸發(fā)電壓脈沖促使電子控制單元斷開(kāi)點(diǎn)火線圈初級(jí)繞組的電流，使得電磁場(chǎng)迅速消失，在次級(jí)繞組中產(chǎn)生一個(gè)高電壓。

4．Thehighsecondaryvoltagetravelsfromthecoilwiretothedistributorrotorandcapandthenontofirethesparkplugofthecylinderthatisontheproperstrokeforignitingtheair/fuelmixture.次級(jí)的高電壓從線圈里，經(jīng)過(guò)分火頭和分電器蓋，到達(dá)處于合適行程的氣缸的火花塞，點(diǎn)火，點(diǎn)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(jī)

3．點(diǎn)火開(kāi)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(diǎn)火系統(tǒng)的作用是在正確的時(shí)刻把電火花提供給氣缸，點(diǎn)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(guò)線圈，產(chǎn)生一個(gè)電磁場(chǎng)，用來(lái)在次級(jí)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(diǎn)火火花的產(chǎn)生提供信號(hào)。

5．火花塞提供空氣間隙，保證高電壓的電弧通過(guò)，以點(diǎn)燃混合氣。

6．分火頭作用是把高電壓從點(diǎn)火線圈分配到需要點(diǎn)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(kāi)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(xì))絲，(細(xì))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(jìn)出車門照明燈

mainlightingswitch 燈光總開(kāi)關(guān)

sidemarkerlights 輪廓燈

licenseplatelight 牌照燈

instrumentpanellights 儀表板燈

lowbeam 近光

highbeam 遠(yuǎn)光

dimmerswitch 變光開(kāi)關(guān)

polarizedheadlight 偏振光前照燈

cutdown 減少

steeringwheel 轉(zhuǎn)向柱

lanechangeswitch 變換開(kāi)關(guān)

hazardwarningflasher (燈光)危急報(bào)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(dāng)燈光總開(kāi)關(guān)接通前照燈線路的時(shí)候,近光燈絲點(diǎn)亮,為在城市道路駕駛和在高速公路上兩車交會(huì)時(shí)提供照明。

2．Also,anybenefitswouldonlybemarginalbecauseglareitselfisnotafrequentcauseofaccidents.這些益處只是次要的,因?yàn)檠Ｄ勘旧聿⒉皇且馔馐录l(fā)生的常見(jiàn)因素。

3．Thisfeatureprovidesthedrivertheopportunitytosignalalanechangebyholdingtheturnleveragainstadetent,thenreleasingittocancelthesignalimmediatelyafterthemaneuveriscompleted.該特征提供給駕駛員一個(gè)機(jī)會(huì)來(lái)握住轉(zhuǎn)向桿,靠向一個(gè)爪來(lái)表示一個(gè)變換信號(hào),在操縱完之后,釋放它就可以立刻取消該信號(hào)。

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

Ⅰ.?AnswerthefollowingquestionsinEnglish.

1．Howmanylightsarementionedintheparagraphtwo?

2．Whenshouldthedrivechangethehighbeamtolowbeam?

3．Whythepolarizedheadlightsystemisnotpopularyet?

4．Whereisthedirectionalsignalswitch?

5．Howthecruiseco