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 部署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 货品
styling 样式assembly 总成,装配
suspension 悬挂,悬置shock 打击
steering 转向,利用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 交换发电机
ReviewQuestions
1.Listthemainpartsofanautomobile?
2.Whatarethecommontypesofavehicleaccordingtobodystyling?
3.Whichsystemsdoesachassisincludeandwhatarethemainfunctionsofthechassis?
4.Whyaresuspensionsystemsusedonvehicles?
CHAPTER2INTERNALCOMBUSTIONENGINE
2.1principleofoperation
Engineandpower
Engineisusedtoproducepower.Thechemicalenergyinfuelisconvertedtoheatbytheburningofthefuelatacontrolledrate.Thisprocessiscalledcombustion.Ifenginecombustionoccurswiththepowerchamber.,theengineiscalledinternalcombustionengine.Ifcombustiontakesplaceoutsidethecylinder,theengineiscalledanexternalcombustionengine.
Engineusedinautomobilesareinternalcombustionheatengines.Heatenergyreleasedinthecombustionchamberraisesthetemperatureofthecombustiongaseswiththechamber.Theincreaseingastemperaturecausesthepressureofthegasestoincrease.Thepressuredevelopedwithinthecombustionchamberisappliedtotheheadofapistontoproduceausablemechanicalforce,whichisthenconvertedintousefulmechanicalpower.
EngineTerms
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..
TheFour-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.
EngineOverallMechanics
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漫衍,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
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 OilPanorSump
Theoilpanisusuallyformedofpres