汽车构造英文版.docx

汽车构造英文版.docx

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汽车构造英文版

CHAPTER1AUTOMOTIVEBASICS

1.1 PrincipalComponents

Today'saveragecarcontainsmorethan15,000separate,individualpartsthatmustworktogether.Thesepartscangroupedintofourmajorcategories:

engine,body,chassisandelectricalequipment.

1.2 Engine

Theengineactsasthepowerunit.Theinternalcombustionengineismostcommon:

thisobtainsitspowerbyburningaliquidfuelinsidetheenginecylinder.Therearetwotypesofengine:

gasoline（alsocalledaspark-ignitionengine）anddiesel（alsocalledacompression-ignitionengine）.Bothenginesarecalledheatengines;theburningfuelgeneratesheatwhichcausesthegasinsidethecylindertoincreaseitspressureandsupplypowertorotateashaftconnectedtothetransmission.

1.3 Body

Anautomobilebodyisasheetmetalshellwithwindows,doors,ahood,andatrunkdeckbuiltintoit.Itprovidesaprotectivecoveringfortheengine,passengers,andcargo.Thebodyisdesignedtokeeppassengerssafeandcomfortable.Thebodystylingprovidesanattractive,colorful,modernappearanceforthevehicle.

1.4 Chassis

Thechassisisanassemblyofthosesystemsthatarethemajoroperatingpartofavehicle.Thechassisincludesthetransmission,suspension,steering,andbrakesystems.

Transmissionsystems―conveysthedrivetothewheels.Themaincomponentsareclutch,gearbox,driveshaft,finaldrive,anddifferential.

Suspension―absorbstheroadshocks.

Steering―controlsthedirectionofthemovement.

Brake―slowsdownthevehicle.

1.5 Electrical Equipment

Theelectricalsystemsupplieselectricityfortheignition,horn,lights,heater,andstarter.Theelectricitylevelismaintainedbyachargingcircuit.Thiscircuitconsistsofthebattery,alternator（orgenerator）.Thebatterystoreselectricity.Thealternatorchangestheengine'smechanicalenergyintoelectricalenergyandrechargesthebattery.

NewWords

Principalcomponent 主要部件category 种类，类型

body 车身chassis 底盘

layout 布置powerunit 动力装置

internalcombustionengine 内燃机cylinder 汽缸

gasoline 汽油spark 火

ignition 点燃，点火diesel 柴油机

compression 压缩shaft 轴

transmission 传动系sheetmetal 金属板

shell 外壳hood （发动机）罩

trunkdeck 行李舱盖cargo 货物

styling 样式assembly 总成，装配

suspension 悬挂，悬置shock 冲击

steering 转向，操纵brake 刹车，制动器

clutch离合器gearbox 变速器

driveshaft 传动轴finaldrive 主减速器，后桥

differential 差速器slowdown（使）慢下来，减速

horn喇叭starter起动机

charge 充电alternator 交流发电机

ReviewQuestions

1.Listthemainpartsofanautomobile?

2.Whatarethecommontypesofavehicleaccordingtobodystyling?

3.Whichsystemsdoesachassisincludeandwhatarethemainfunctionsofthechassis?

4.Whyaresuspensionsystemsusedonvehicles?

CHAPTER2INTERNALCOMBUSTIONENGINE

2.1principleofoperation

2.1.1Engineandpower

Engineisusedtoproducepower.Thechemicalenergyinfuelisconvertedtoheatbytheburningofthefuelatacontrolledrate.Thisprocessiscalledcombustion.Ifenginecombustionoccurswiththepowerchamber.,theengineiscalledinternalcombustionengine.Ifcombustiontakesplaceoutsidethecylinder,theengineiscalledanexternalcombustionengine.

Engineusedinautomobilesareinternalcombustionheatengines.Heatenergyreleasedinthecombustionchamberraisesthetemperatureofthecombustiongaseswiththechamber.Theincreaseingastemperaturecausesthepressureofthegasestoincrease.Thepressuredevelopedwithinthecombustionchamberisappliedtotheheadofapistontoproduceausablemechanicalforce,whichisthenconvertedintousefulmechanicalpower.

2.1.2EngineTerms

Linkingthepistonbyaconnectingrodtoacrankshaftcausesthegastorotatetheshaftthroughhalfaturn.Thepowerstroke“usesup”thegas,someansmustbeprovidedtoexpeltheburntgasandrechargethecylinderwithafreshpetrol-airmixture:

thiscontrolofgasmovementisthedutyofthevalves;aninletvalveallowsthenewmixturetoenterattherighttimeandanexhaustvalveletsouttheburntgasafterthegashasdoneitsjob.Enginetermsare:

TDC（TopDeadCenter）:

thepositionofthecrankandpistonwhenthepistonisfartherawayfromthecrankshaft.

BDC（BottomDeadCenter）:

thepositionofthecrankandpistonwhenthepistonisnearesttothecrankshaft.

Stroke:

thedistancebetweenBDCandTDC;strokeiscontrolledbythecrankshaft.

Bore:

theinternaldiameterofthecylinder.

Sweptvolume:

thevolumebetweenTDCandBDC.

Enginecapacity:

thisisthesweptvolumeofallthecylindere.g.afour-strokehavingacapacityoftwoliters（2000cm）hasacylindersweptvolumeof50cm.

Clearancevolume:

thevolumeofthespaceabovethepistonwhenitisatTDC.

Compressionratio=（sweptvol+clearancevol）\（clearancevol）

Two-stroke:

apowerstrokeeveryrevolutionofthecrank.

Four-stroke:

apowerstrokeeveryotherrevolutionofthecrank..

2.1.3TheFour-strokeSpark-ignitionEngineCycle

Thespark-ignitionengineisaninternal-combustionenginewithexternallysuppliedinignition,whichconvertstheenergycontainedinthefueltokineticenergy.

Thecycleofoperationsisspreadoverfourpistonstrokes.Tocompletethefullcycleittakestworevolutionsofthecrankshaft.

Theoperatingstrokesare:

Thisstrokeintroducesamixtureofatomizedgasolineandairintothecylinder.Thestrokestartswhenthepistonmovesdownwardfromapositionnearthetopofthecylinder.Asthepistonmovesdownward,avacuum,orlow-pressurearea,iscreated.

Duringtheintakestroke,oneoftheportsisopenedbymovingtheinletvalve.Theexhaustvalveremainstightlyclosed.

Compressionstroke

Asthepistonmovesupwardtocompressthefuelmixturetrappedinthecylinder,thevalvesareclosedtightly.Thiscompressionactionheatstheair/fuelmixtureslightlyandconfinesitwithinasmallareacalledthecombustionchamber.

Powerstroke

Justbeforethepistonreachesthetopofitscompressionstroke,anelectricalsparkisintroducedfromasparkplugscrewedintothecylinderhead.

Thesparkignitesthecompressed,heatedmixtureoffuelandairinthecombustionchambertocauserapidburning.Theburningfuelproducesintenseheatthatcausesrapidexpansionofthegasescompressedwithinthecylinder.Thispressureforcesthepistondownward.Thedownwardstroketurnsthecrankshaftwithgreatforce.

Exhauststroke

Justbeforethebottomofthepowerstroke,theexhaustvalveopens.Thisallowsthepiston,asitmovesupward,topushthehot,burnedgasesoutthroughtheopenexhaustvalve.

Then,justbeforethepistonreachesitshighestpoint,theexhaustvalveclosesandtheinletvalveopens.Asthepistonreachesthehighestpointinthecylinder,knownasTDC,itstartsbackdownagain.Thus,onecycleendsandanotherbeginsimmediately.

2.1.4EngineOverallMechanics

Theenginehashundredsofotherparts.Themajorpartsofengineareengineblock,engineheads,pistons,connectingrods,crankshaftandvalves.Theotherpartsarejoinedtomakesystems.Thesesystemsarethefuelsystem,intakesystem,ignitionsystem,coolingsystem,lubricationsystemandexhaustsystem.Eachofthesesystemshasadefinitefunction.Thesesystemswilldiscussedindetaillater.

NEWWORD

Piston活塞Connectingrod连杆

Crankshaft曲轴Powerstoke活塞行程

Expel排出Valve气阀

inlet（intake）valve进气阀exhaustvalve排气阀

term术语TDC上止点

BDC下止点Bore缸径

sweptvolume有效容积enginecapacity发动机排量

clearancevolume余隙容积,燃烧室容积compressionratio压缩比

revolution旋转,转数everyother每隔一个

cycle循环spreadover分布,遍及

intakestroke进气行程compressionstroke压缩行程

knock敲缸,敲打exhauststroke排气行程

engineblock发动机缸体lubrication润滑

2.2EngineBlockandCylinderHead

2.2.1 EngineBlock

Theengineblockisthebasicframeoftheengine.Allotherenginepartseitherfitinsideitorfastentoit.Itholdsthecylinders,waterjackets,andoilgalleries.Theengineblockalsoholdsthecrankshaft,whichfastenstothebottomoftheblock.Thecamshaftalsofitsinsidetheblock,exceptonoverhead-camengines（OHC）.Inmostcars,thisblockismadeofgrayiron,oranalloy（mixture）ofgrayironandothermetals,suchasnickelorchromium.Engineblocksarecastings.

Someengineblocks,especiallythoseinsmallercars,aremadeofcastaluminum.Thismetalismuchlighterthaniron.However,ironwearsbetterthanaluminum.Therefore,thecylindersinmostaluminumenginesarelinedwithironorsteelsleeves.Thesesleevesarecalledcylindersleeves.Someengineblocksaremadeentirelyofaluminum.

2.2.2 CylinderHead

Thecylinderheadfastenstothetopoftheblock,justasarooffitsoverahouse.Theundersideformsthecombustionchamberwiththetopofthepiston.Themostcommoncylinderheadtypesarethehemi,wedge,andsemi-hemi.Allthreeofthesetermsrefertotheshapeoftheengine'scombustionchamber.Thecylinderheadcarriesthevalves,valvespringsandtherockersontherockershaft,thispartofthevalvegearbeingworkedbythepush-rods.Sometimesthecamshaftisfitteddirectlyintothecylinderheadandoperatesonthevalveswithoutrockers.Thisiscalledanoverheadcamshaftarrangement.Likethecylinderblock,theheadismadefromeithercastironoraluminumalloy.

2.2.3 Gasket

Thecylinderheadisattachedtotheblockwithhigh-tensilesteelstuds.Thejointbetweentheblockandtheheadmustbegas-tightsothatnoneoftheburningmixturecanescape.Thisisachievedbyusingcylinderheadgasket.Thisisasandwichgasket,i.e.asheetofasbestosbetweentwosheetsofcopper,boththesematerialsbeingabletowithstandthehightemperatureandpressureswithintheengine.

2.2.4 OilPan