汽車專業(yè)英語(yǔ)讀譯教程 第3版 教案 UNIT 3 FUEL INJECTION SYSTEMS

授課題目UNIT3

FUELINJECTIONSYSTEMS

TEXTA

ElectronicFuelInjectionSystems授課類型理論課首次授課時(shí)間學(xué)時(shí)2學(xué)時(shí)教學(xué)目標(biāo)1、汽油直噴系統(tǒng)作用原理、組成；2、電子油門系統(tǒng)作用原理、組成。重點(diǎn)與難點(diǎn)重點(diǎn)：汽油直噴系統(tǒng)作用原理、組成；難點(diǎn)：電子油門系統(tǒng)作用原理、組成；教學(xué)手段與方法多媒體教學(xué)教學(xué)過(guò)程：（包括授課思路、過(guò)程設(shè)計(jì)、講解要點(diǎn)及各部分具體內(nèi)容、時(shí)間分配等）1.授課思路在學(xué)習(xí)了前置課程之后，通過(guò)專業(yè)英語(yǔ)的學(xué)習(xí)，進(jìn)行與汽車相關(guān)技術(shù)結(jié)構(gòu)原理的中文英文對(duì)接，培養(yǎng)和提高英文專業(yè)資料（信息）的閱讀能力，從而為與專業(yè)英語(yǔ)密切相關(guān)的后續(xù)課程奠定了必要的基礎(chǔ)。2.過(guò)程設(shè)計(jì)：（1）課程內(nèi)容簡(jiǎn)介（5分鐘）（2）導(dǎo)入新課（15分鐘）。（3）新課內(nèi)容（75分鐘）教師根據(jù)學(xué)生學(xué)習(xí)的情況，對(duì)課程內(nèi)容的重點(diǎn)和難點(diǎn)進(jìn)行講解。（4）課程小結(jié)（5分鐘）3.授課內(nèi)容：Fuelinjectionsystemsdeliverfuelbyforcingitintotheincomingairstream（Fig.3-1）.Fuelinjectionsystemsactuallymeasuretheincomingairandpressurizethefueltodeliveritinpreciseamountsbaseddirectlyonthatmeasurement.Becausefuelisdeliveredtothemanifoldunderpressure,thequantityoffueldeliveredcanbemorepositivelycontrolled.Withthismorepositivecontrol,fueldeliverycanbemoreeasilymanipulatedtomeettheuniquedemandsofextremeoperatingconditions.Thisresultsingreaterefficiencyoverawiderrangeofoperation.1.PulseFuelInjectionInpulseinjectionsystems,therateoffuelflowthroughtheinjectorsremainsconstant.Thetotalamountoffueldeliveredisdeterminedbythelengthoftimetheinjectorsareheldopen.Systemsareclassifiedbythetypeoftimingsequenceusedandthelocationoftheinjectors.TypesofPulseFuelInjectionSystemsThenextsectionwilldiscusscommonfuelinjectionsystemswhicharetypicalofthepulsesystemsnowinuse.Thepulseinjectionsystemisusuallyelectronicallycontrolled.Althoughthereareanumberofdesigndifferencesbetweenvariouspulsefuelinjectionsystems,theoperatingprinciplesareverysimilar.PulseFuelInjectionSystemComponentsThetypicalpulsesystemcanbebrokenintothreebasicparts:·Airinductionsystem.·Fueldeliverysystem.·Electroniccontrolsystem(includingenginecontrolcomputerandelectronicsensors).AirinductionsystemTheairinductionsystemconsistsofanaircleanerassembly,throttlebody,andintakemanifold.Thethrottlebodysectioncontainsthethrottlevalve,whichisopenedandclosedbythedrivertocontroltheamountofairenteringtheintakemanifold.FueldeliverysystemThefueldeliverysystem（Fig.3-2）providesthefuelwhichmixeswiththeair.Pressureisprovidedbyanelectricfuelpump.Somesystemsusetwopumps:alow-pressurefuelpumpthatdeliversfueltoanotherpump,whichdevelopsthepressure.EnginecontrolcomputerEnginecontrolcomputersareconstructedusingmanydifferentelectroniccircuitsandcomponents.Sizeandcomplexityvariesdependinguponthesystem.Moderncomputerscontrolmanyotherenginesystemsinadditiontothefuelinjectors.ElectronicSensorsTheelectronicsensorsmonitor(check)variousenginefunctionsandfeedthisinformationtothecomputer.Thenumberandtypesofsensorsvarywiththesystem.OxygenSensorTheoxygensensormonitorstheamountofoxygenintheengine'sexhaustgases.Astheoxygencontentintheexhaustgaseschanges,thevoltagesignalproducedbythesensoralsochanges.Thecomputerusessignalsfromtheoxygensensortocontroltheair-fuelmixture.2.ContinuousInjectionSystems(CIS)Thecontinuoussystemsaresometimesreferredtoasmechanicalorhydro-mechanical,becausefuelmeteringisdeterminedbythemechanicalrelationshipbetweenanair-flowsensorandafueldistributor.ThefirstcontinuoussystemsweredistinctlydifferentfromEFIsystems,sincetherewasnoelectroniccontrolofbasicfueldelivery.T