2.1PrincipleofOperation2.2EngineBlockandCylinderHead2.3Piston,ConnectingRodandCrankshaft2.4EngineandTransmissionMounting2.5ValveSystem2.1工作原理2.2發動機體和氣缸蓋2.3活塞、連桿和曲軸2.4發動機和變速器組件2.5氣門系統Chapter2InternalCombustionEngine2.6GasolineFuelSystem2.7DieselEngine2.8EngineCooling2.9EngineLubrication2.10Emission2.6汽油燃料系統2.7柴油發動機2.8發動機的冷卻2.9發動機的潤滑2.10排放第二章內燃機Chapter2InternalCombustionEngine2.1PrincipleofOperation2.1.1Energyandpower:

Energyisusedtoproducepower.Thechemicalenergyinfuelisconvertedtoheatbytheburningofthefuelatacontrolledrate.Thisprocessiscalledcombustion.2．1工作原理2．1．1能源和動力能源用于產生動力。燃料以控制的速率燃燒，燃料中的化學能轉換為熱能。這個過程叫做燃燒。Chapter2InternalCombustionEngineIfenginecombustionoccurswithinthepowerchamber,theengineiscalledanInternalcombustionEngine.Ifenginetakesplaceoutsidethecylinder,theengineiscalledanexternalcombustionengine.如果發動機燃燒發生在動力室內，這種發動機叫做內燃機。如果燃燒發生在氣缸外，這樣的發動機叫做外燃發動機。Chapter2InternalCombustionEngine

Enginesusedinautomobilesareinternalcombustionheatengines.Heatenergyreleasedinthecombustionchamberraisesthetemperatureofthecombustiongaseswithinthechamber.

汽車使用的發動機是內燃熱發動機。在燃燒室內釋放的熱能提高了室內燃燒氣體的溫度。Chapter2InternalCombustionEngineTheincreaseingastemperaturecausesthepressureofthegasestoincrease.Thepressuredeveloped

withinthecombustionchamberisappliedtotheheadofapistontoproduceausablemechanicalforce,whichisthenconvertedintousefulmechanicalpower.氣體溫度的增加使氣體的壓力增加。在燃燒室內產生的壓力作用于活塞的頂部，產生機械力，這個力轉換成有用的機械動力。Chapter2InternalCombustionEngine2.1.2Engineterms

Linkingthepistonbyaconnectingrodtoacrankshaftcausesthegastorotatetheshaftthroughhalfaturn.Thepowerstroke"usesup"thegas,someansmustbeprovidedtoexpeltheburntgasandrechargethecylinderwithafreshpetrol-airmixture:thiscontrolofgasmovementisthedutyofthevalves;活塞通過連桿和曲軸連接，使得氣體帶動曲軸旋轉半圈。作功沖程耗盡了所有的氣體，這樣就必須采取相應的措施排出廢氣以及向氣缸內充入新鮮的可燃混合氣：氣體的運動由氣門來控制.Chapter2InternalCombustionEngine2.1.2:

EngineTerms

TDC（topdeadcenter）:

thepositionofthecrankandpiston whenthepistonisfartherawayfrom thecrankshaft.

BDC（bottomdeadcenter）:

thepositionofthecrankandpiston whenthepistonisnearestawayfrom thecrankshaft.Chapter2InternalCombustionEngineChapter2InternalCombustionEngine

sweptvolume:

thevolumebetweenTDC andBDC.Clearancevolume:

thevolumeofspaceabovethepistonwhenitisatTDC.

Enginecapacity:

thisisthesweptvolumeof allcylinders.Chapter2InternalCombustionEngine2.1.3:ThefourstrokesSpark-ignitionEnginecycleIntake(induction)strokeCompressionstrokePowerstrokeExhauststrokeChapter2InternalCombustionEngineChapter2InternalCombustionEngine

2.1.4:EngineOverallMechanics

Crankshaftandconnecting rodssystem

Valvesystem

Fuelsystem

Ignitionsystem

Coolingsystem

Lubricationsystem

Startingsystem2.2：Engineblockandcylinderhead

Chapter2InternalCombustionEngine2.2.1:Engineblock:Theengineblockisthebasicframeoftheengine.Allotherenginepartseitherfitinsideitorfastentoit.Itholdsthecylinders,waterjackets,andoilgalleries.Theengineblockalsoholdsthecrankshaft,whichfastenstothebottomoftheblock.氣缸體是發動機的基體。發動機其它的部件都安裝在缸體內或固定在缸體上，它包容了氣缸、水套和油道，以及固定在缸體底部的曲軸等。

Chapter2InternalCombustionEngine2.2.1:Engineblock:Thecamshaftalsofitsinsidetheblock,exceptonoverhead-camengine(OHC).Inmostcars,thisblockismadeofgrayiron,oranalloy(mixture)ofgrayironandothermetals,suchasnickelorchromium.Engineblocksarecasting.Chapter2InternalCombustionEngine2.2.1:Engineblock:Someengineblock,especiallythoseinsmallercars,aremadeofcastaluminum.Thismetalismuchlighterthaniron.However,ironwearsbetterthanaluminum.Therefore,thecylindersinmostaluminumenginearelinedwithironorsteelsleeves.Thesesleevesarecalledcylindersleeves.Someengineblocksaremadeentirelyofaluminum.Chapter2InternalCombustionEngine2.2.1:Engineblock:

Chapter2InternalCombustionEngine2.2.2:

Cylindersleeve:

Thedrysleevecanbecastinorpressedintoanewblockorusedtoreconditionbadlywornordamagedcylindersthatcannoteasilyberebored.干式缸套可以鑄進或壓入新氣缸體中，或者用于嚴重磨損或損壞而又不易重鏜的缸體的修復。Chapter2InternalCombustionEngine2.2.3:Cylinderhead:

Thecylinderheadfastenstothetopoftheblock,justasarooffitsoverahouse.Theundersideformsthecombustionchamberwiththetopofthepiston.In-lineenginesoflightvehicleshavejustonecylinderheadforallcylinders;largerin-lineenginescanhavetwoormore.氣缸蓋扣在缸體的頂部，就像屋頂安在房子上一樣。缸蓋的下方和活塞頂部形成燃燒室。輕型車的直列發動機所有缸僅有一個氣缸蓋，較大的直列發動機有兩個或更多缸蓋。

Chapter2InternalCombustionEngineThecylinderheadcarriesthevalves,valvespringsandtherockersontherockershaft,thispartofthevalvegearbeingworkedbypush-rods.缸蓋上有氣門、氣門彈簧和搖臂軸上的搖臂，推桿推動這部分氣門傳動機構工作。

Chapter2InternalCombustionEngineChapter2InternalCombustionEngine2.2.4:Gasket

Chapter2InternalCombustionEngine2.2.5:OilpanorSump:

Theoilpumpinthelubricatingsystemdrawsoilfromtheoilpanandsendsittoallworkingpartsintheengine.The oildrainsoffandrunsdownintothepan.Thus,thereisconstantcirculationofoilbetweenthepanandtheworkingpartsoftheengine.潤滑系的機油泵從油底殼抽出機油，并把機油輸送給發動機的所有工作部件。機油從油底殼流進流出。因而在油底殼和發動機的工作部件之間有機油定向循環流動。Chapter2InternalCombustionEngine2.3:Piston,connectingRodandCrankshaft

Chapter2InternalCombustionEngine2.3.2:Pistonassembly

Mostpistonsaremadefromcastaluminum.Thepiston,throughtheconnectingrod,transferstothecrankshafttheforcecreatedbytheburningfuelmixture.Thisforceturnsthecrankshaft.大多數活塞由鋁鑄造而成。通過連桿，活塞把可燃混合氣燃燒所產生的力傳遞給曲軸，并帶動曲軸旋轉。Chapter2InternalCombustionEngine1.Piston

Chapter2InternalCombustionEngine2.PistonRings

Inmodernengines,eachpistonhasthreerings.(Pistoninolderenginessometimeshadfourrings,orevenfive.)TheinsidesurfaceoftheringfitsinthegrooveonthepistonThering'soutsidesurfacepressesagainstthecylinderwalls.在新型發動機上，每個活塞有三個活塞環。（在老式發動機上，每個活塞有四個甚至五個活塞環。）環的內邊面緊貼在活塞的環槽里，環的外表面緊壓在氣缸壁上。Chapter2InternalCombustionEngine3.PistonPin

Chapter2InternalCombustionEngine2.3.3ConnectingRod

Theconnectingrodlittleendisconnectedtothepistonpin.A

bushmadefromasoftmetal,suchasbronze,isusedforthisjoint.Thelowerendoftheconnectingrodfitthe

crankshaftjournal.Thisiscalledthebigend.連桿小頭與活塞銷連接，小頭孔處壓有諸如青銅這種較軟材料所制成的襯套，連桿下端連接在曲軸的連桿軸徑處，稱為連桿大頭。Chapter2InternalCombustionEngineConnectingRodChapter2InternalCombustionEngineConnectingRod

Chapter2InternalCombustionEngine2.3.4Crankshaft

Chapter2InternalCombustionEngine2.3.5Cylindernumberandfiringorder:

Crankarrangementofengines:

fourcylinderssixcylindersChapter2InternalCombustionEngineCylindernumberandfiringorder:

No.4pistonisalwaysperformingthe companionstroketoNo.1:whentheinletvalveinNo.4cylinderisfullyopen,No.1cylinderinlet valveisfullyclosed---thisfeatureisusefultorememberwhencheckingvalveclearances.注意4號活塞和1號活塞總是成對運行：4號氣缸進氣門全閉時，1號氣缸進氣門全開—這個特點在檢查氣門間隙時是很有用的。

Chapter2InternalCombustionEngine2.3.6Flywheel

Chapter2InternalCombustionEngine2.3.7Torsionalvibrationbalancer:

Aseachcylinderfires,itcausesthecrankthrowtospeedup.Theinertiaoftherestofshaftcauseitto stayslightlybehind,resultinginatwistingactiononthecrankshaft.當一缸點火時，使曲軸擺幅的速度提高，而其它軸的慣性阻礙它，使其滯后，從而導致曲軸扭轉。

Chapter2InternalCombustionEngineTheinertiaringisbondedtothehubthroughaflexibleelastomer

(rubbercompound)insert.Theinertialringmovesslightlyinrelationtocrankshaftrotationaseachcylinderfires,therebydampeningthetorsionalvibrationofthecrankshaftoverawiderangeofenginespeed.慣性盤通過一層由橡膠合成的可變形人造橡膠層與減振器圓盤相連．在每個汽缸點火時，慣性盤相對于曲軸運動做微小轉動，用以削減發動機較大速度范圍.Chapter2InternalCombustionEngine

Chapter2InternalCombustionEnginehubInertialringelastomer

汽車英語專業詞組2.1chemicalenergy化學能internalcombustionengine內燃機inletvalve進氣閥exhaustvalve排氣閥TDC上止點BDC下止點sweptvolume有效/工作容積enginecapacity發動機排量clearancevolume燃燒室容積compressionratio壓縮比Chapter2InternalCombustionEngine

汽車英語專業詞組2.1

kineticenergy動能induction/intakestroke進氣行程compressionstroke壓縮行程powerstroke做功行程exhauststroke排氣行程engineblock發動機缸體Chapter2InternalCombustionEngine

汽車英語專業詞組2.2

cylinderhead氣缸蓋waterjackets水套oilgallery油道grayiron灰鑄鐵cylindersleeve氣缸套headcover氣缸蓋罩intakemanifold進氣總管oilpan油底殼

waterpump水泵

pistonring活塞環Chapter2InternalCombustionEngine

汽車英語專業詞組2.2

dry/wetsleeve干式/濕式缸套push-ro