第一章发动机的工作原理和总体构造

第一章发动机的工作原理和总体构造内燃机的工作原理与总体构造OperationandBasicSystems主要内容Contents发动机的定义及分类Definition&Classifications四冲程发动机及二冲程发动机的工作原理Operation发动机的基本工作系统BasicSystems发动机的产品名称和型号编制规则ProductNamesandTypeEstablishmentRules有关概念和排量的计算Terminology&Concept1.1IntroductionTheinternalcombustion(IC)engineisaheatenginethatconvertschemicalenergyinafuelintomechanicalenergy,usuallymadeavailableonarotatingoutputshaft.内燃机是将热能（来自于燃料化学能）转变为机械能的一种热机。Versussteamenginesandgasturbineenginesareexternalcombustionengines(i.e.，combustiontakesplaceoutsidethemechanicalenginesystem)外燃机

1.1发动机的定义发动机将某一种形式的能量转化为机械能的机器。热机（热能机械能）外燃机内燃机燃气轮机活塞式往复活塞式reciprocatingengines旋转活塞式rotaryengines1.2HistoricalBackgroundForcenturies,manwalkedorusedanimalsfortransportation.After

theinventionofmechanicalpropulsionsystems,peopleusedself-

propelledvehicles,whichmoveundertheirownpower.

Majormilestonesinvehicledevelopmentinclude:

ThefirstfairlypracticalenginewasinventedbyJ.J.E.Lenoir(1822-1900)andappearedonthesceneabout1860.1876Ottowasgivencreditwhenhisprototypeenginewasbuiltin1876.1892By1892,RudolfDiesel(1858-1913)hadperfectedhiscompressionignitionen­gineintobasicallythesamedieselengineknowntoday.1.2EarlyHistory2techno­logicaloccurrencesduringlatterhalfofthe1800sstimulatedtheemergenceoftheICEIn1859,thediscoveryofcrudeoilinPennsylvaniaThepneumaticrubbertirefirstmarketedbyJohnB.Dunlopin1888.1912

ElectricstarterinventedbyCharlesF.Kettering.

FirstusedonaCadillac,thestarterwasproduced

byDaytonElectricLaboratoriesCompany

1.2EarlyHistoryThesteamengineworkingprinciple内燃机发展简史内燃机是在蒸汽机的基础上发明创制的：1700年，英国人钮卡姆制成了直立汽缸，密封式活塞、缸内喷水冷却的蒸汽机；后由瓦特改良；1814——1829年，英国人史蒂芬森制成蒸汽机车，建成世界上第一段铁路；1860年，法国人勒纳（lenoir）仿蒸汽机制成世界上第一台商用煤气机（ŋ=4%）；内燃机发展简史内燃机是在蒸汽机的基础上发明创制的：1876年，德国人奥托制成四冲程火花点火内燃机（ŋ=16%）；1883年，英国人司派尔仿奥托四冲程煤气机创制汽油机；1886年，德国人奔茨制成用汽油机做动力的汽车；1892年，德国人狄塞尔创制柴油机成功，1898年，柴油机作为商品出售，热效率为29%。1.3EngineOperationFour-StrokeSIEngineCycleIntakeorInductionStrokePowerorExpansionStrokeCompressionStrokeExhaustStroke1.3EngineOperationindicatordiagram1.3EngineOperation1、Piston-EngineConstructionPistonsmoveupanddown(orbackandforth)incylindersReciprocatingmotionischangedtorotarymotionbyconnectingrodandacrankpinonthecrankshaft2、OperationApistonstrokeisthemovementofthepistoninthecylinderfromtoptobottom,orbottomtotopFourpistonstrokes-----------intake,compression,powerandexhaust.Takestworevolutionsofthecrankshaft.Four-stroke-cycleengine1.3EngineOperationFour-StrokeCIEngineCycleIntakeorInductionStrokePowerorExpansionStrokeCompressionStroke1.3EngineOperation四冲程柴油机工作原理（seeanimation）/diesel1.htm1.3EngineOperation四冲程柴油机与汽油机比较同：四个冲程—进气、压缩、膨胀和排气异：燃油，可燃混合气形成，着火方式汽油易蒸发，柴油不易挥发混合气形成：高压柴油从喷油器中直接喷入气缸，形成时间很短（燃烧室形状，组织进气涡流）着火方式：自燃温度约600K（320℃）压缩比较大。1.3EngineOperationQuestions:Whatmakestheairorair-fuelmixtureenterintothecylinder?Whatmakesthepistonsmoveupanddowninthecylinders?Whatisthepurposeofthevalves？Whatisthepropertimingofthevalves?Howdothecrankshaftandconnectingrodchangethereciprocatingmotionintorotarymotion？1.3EngineOperationAsinglecylinderfour-stroke-cycleenginehasonlyonepowerimpulseforeverytwocrankshaftrevolutions.Thepistondeliverspoweronlyone-fourthofthetime.四个冲程，只有一个行程做功，运转不平稳；Foramoreevenflowofthepower,mostautomotiveengineshavefourormorecylinders.Thecylindersfireoneafteranothertoprovideasteadypowerflow.常采用多缸的方式;缸数曲轴做功间隔12周21周4半周8¼周1.3EngineOperation1.3EngineOperationAcarengineusesafour-strokecycle--howcantwostrokesaccomplishthesametasks?想一想，两冲程发动机怎么工作？怎样在活塞的两个冲程完成一个（进气、压缩、膨胀和排气）完整的循环？结构特点示功图1.3EngineOperationYoucanseethattwo-strokeenginesareingeniouslittledevicesthatoverlapoperationsinordertoreducethepartcount.1.3EngineOperationTwo-StrokeSIEnginescheduleSpecialDesignofTwo-StrokeEnginesOnonesideofthepistonisthecombustionchamber,wherethepistoniscompressingtheair/fuelmixtureandcapturingtheenergyreleasedbytheignitionofthefuel.Ontheothersideofthepistonisthecrankcase,wherethepistoniscreatingavacuumtosuckinair/fuelfromthecarburetorthroughthereedvalveandthenpressurizingthecrankcasesothatair/fuelisforcedintothecombustionchamber.Meanwhile,thesidesofthepistonareactinglikevalves,coveringanduncoveringtheintakeandexhaustportsdrilledintothesideofthecylinderwall.1.3EngineOperation两冲程汽油机在两个活塞行程内完成进气、压缩、膨胀和排气的工作循环。1、结构三个口：进气口、排气口和扫气口2、工作过程活塞上行：压缩、进气、点燃活塞下行：做功、结束进气、排气、扫气3、总结由于特殊结构，方使得进气、压缩、做功和排气得以在两个冲程中完成；有效行程的大小与孔的位置有关。1.3EngineOperationTwo-StrokeSIEngineCycle1.3EngineOperationTwo-StrokeCIEngineCycle1.3EngineOperationTwo-StrokeoverFourStrokeSIEngineAdvantage优点：PowerStrokeeveryrevolution一周有一个做功行程，运转均匀平稳；SimpleStructure无专门的换气机构，使用方便。Disadvantage缺点：RemainingofExhaustGases不易将废气排除干净；LessEfficientStroke有效行程小于上下止点间距离；BlowoutofAir-FuelMixture扫气时有燃油损失。1.3EngineOperationTwo-StrokeCIEngine1、overtwo-strokeSIengine与二冲程汽油机比较，不同之处：exhaustvalves采用排气门排气；moreinletports进气口不止一个，环布在气缸周围，且经气泵加压；Scavengingwithpureair采用纯空气扫气，没有燃油损失；separatecrankcase不用曲轴箱贮存可燃混合气及空气。2、工作原理Upwardstroke:scavenge,compression,spray,self-ignition活塞上行冲程：换气、压缩、喷油着火；Downwardstroke:expansion,exhaust,intakeandscavenge活塞下行冲程：膨胀做功、排气换气。1.3EngineOperation柴油机与汽油机的特点比较柴油机压缩比大，燃气膨胀充分，膨胀终了燃气温度较低，热量利用程度较好，比汽油机省燃料。柴油机气缸压力较高，机件受力较大，刚度和强度要求较高，与相同功率的汽油机相比，其体积较大，重量也较大，但坚固耐用，运转时噪声也较大。柴油机中喷油泵和喷油气的精密度高，加工比较困难，制造成本也较高。柴油机借助于压缩终了空气的高温使柴油着火，所以较难起动。汽油机转速较高，柴油机转速较低。柴油机广泛用在农用动力、拖拉机、载重汽车、工程机械、机车、船舶等方面。汽油机则由于结构轻巧、制造方便、工作平稳、起动容易等优点，常用在小客车、轻型载货汽车及小型农用动力上。1.4Terminology术语及概念Top-Dead-Center上止点（TDC)BottomDead-Center下止点(BDC)Stroke活塞行程(S)DisplacementorDisplacementVolume排量（发动机工作容积或发动机排量）Compressionratio压缩比Knock爆震1.4术语及概念演示1.5EngineClassificationTypesofIgnitionSparkIgnitionCompressionIgnitionEngineCyclesFour-strokecycleTwo-strokecycleAirIntakeProcessFuelUsedTypeofCooling1.5发动机的分类往复活塞式发动机两种基本类型汽油机柴油机所用燃料着火方式混合气准备方式发动机的其他分类按每循环冲程数/按进气方式/按燃料/按冷却方式按气缸数目/按气缸排列方式/按气门数1.6BasicEngineSystems发动机的总体构造按照功能解体为下面几个部分：FuelSystem燃油供给系统（）Intakesystem进气系统（）IgnitionSystem点火系统CoolingSystem冷却系统（）LubricatingSystem润滑系统（）StartingSystem起动系统EmissionControlSystem排放控制系统1.6BasicEngineSystems发动机的总体构造FuelSystem燃油供给系（）Thefuelsystemsuppliesgasolineordieselfueltotheengine.Thefuelismixedwithairtomakeacombustiblemixture.Eachcylinderisrepeatedlyfilledwiththemixture.Then,themixtureisignitedandburned,producinghighpressure.Thehighpressuremakesthepistonsmove.Thisturnsshaftsthatrotatethewheels,causingthevehiclestomove.1.6BasicEngineSystems发动机的总体构造AirIntake/ExhaustSystem

进排气系统

（）Allenginesdrawairfromtheatmosphere.AirIntake/ExhaustSystembringscleanairintotheenginefromoutsideandpushesexhaustgasestooutside.1.6BasicEngineSystems发动机的总体构造IgnitionSystem点火系统Deliveranelectricsparktoignitetheair-fuelmixture.Theactionisrepeatedmanytimeseachsecondwhiletheengineisrunning.Theignitionsystemtakesthelowvoltageofthebatteryandbuildsituptoaveryhighvoltage---ashighas47,000voltsinsomesystems.Thishighvoltagejumpsthegapsinthesparkplugs,producingthesparks.1.6BasicEngineSystems发动机的总体构造CoolingSystem冷却系统（）Coolingsystemgivetheenginebetterheatcontrolbyremovalofthesurplusheatorwarminguptheenginequicklyatthecoldstart.1.6BasicEngineSystems发动机的总体构造LubricatingSystem润滑系统（）Theenginehasmanymovingmetalparts.Ifmetalpartsrubagainsteachother,theywillwearrapidly.Topreventthis,engineshavelubricatingsystemsthatfloodallmovingpartswithacoatingoflubricatingoil.Theoilgetsbetweenthemetalpartssotheyslideonoilandnotoneachother.1.6BasicEngineSystems发动机的总体构造StartingSystem起动系统Thestartingsystemisneededtocranktheengine.Abatteryprovidestheelectricpowertooperatethestaringmotorandtheignitionsystemduringcranking1.6BasicEngineSystems发动机的总体构造EmissionControlSystem

Controlofvehicleemissionsincludescontrollinggasolinevaporsreleasedintotheatmosphereinadditiontoreducingexhaustemissions.发动机参数承载车辆BETA发动机DELTA发动机发动机型号伊兰特索纳塔1.6LGAS1.8LGAS2.0LGAS2.7LGAS发动机形式1-4(4缸)V-6(6缸)BORE×STROKE77.4×8582×8582×93.566.7×75排气量(CC)1.5991.7951.9752.656最大功率(PS/rpm)112/6,000132/6,000140/6,000178/6,000缸心距9196最大扭矩(Kg.m/rpm)14.6/4,50017.1/4,50018.6/4,50025.0/4,000Engine基本组成(Assembly)AirCleanerExhaustManifoldIntakeManifoldCatalystCylinderHeadWaterPumpAirCleanerAirCleanerElementFuelRailInjectorCatalystIntakeManifoldExhaustManifoldThrottleBody进排气系统Intake/ExhaustSystemValveTrainTimingBeltCamshaftIntake&ExhaustValveCamshaftSprocketCrankshaftSprocketValveSpringIdler配气系统CoolingWaterCircuitThermostatThermostatHousingWaterPumpToRadiator冷却系统曲柄连杆机构

MovingPart（主运动系统）PistonPistonRingFlywheelConnecting-RodCrankshaftMainBearingDamperPulleySIMK43PCU

O₂SENSOR

3-CATALYST碳罐清污阀CKPSKNOCKSENSORTPSIGNITIONCOILFUELPUMPWTS

INJECTORCMPSISASENSORSACTUATORS新世代

A/T▣β-2.0DENGINEAirMAPSSPARKPLUGCMPS:CamshaftPositionSensorCKPS:CrankshaftPositionSensorTPS:ThrottlePositionSensorWTS:WaterTemperatureSensorISA:IdleSpeedActuatorEFCENGMANAGEMENTSYSTEM构成图ProductNames&TypeEstablishmentRules

内燃机产品名称和型号编制规则GB/T725-1991规定；内燃机按所用燃料命名；型号由阿拉伯数码和汉语拼音字母组成；内燃机型号由下列四部分组成首部：产品系列符号或换代标志符号；中部：缸数符号、冲程符号、汽缸排列符号和缸径符号；后部：结构特征、用途符号尾部：区分符号TrendGDIHCCIProblems:1.1ListfivedifferencesbetweenSIenginesandCIengines.1.2Afour-strokecycleenginemay