汽车专业英语课件-与汽车专业英语读译教程课件、参考译文9-U5TA

UNIT5DIESELFUELINJECTIONTEXTAOverviewofConventionalDieselFuelInjectionandCommonRailInjectionSystems,PROFESSIONALENGLISH,ConventionalDieselFuelInjectionSystemcomponentsCommonRailInjectionSystemsSystemcomponentsInjectoroperation,本次课学习内容,本次课学习目标,掌握柴油机喷油系统的组成掌握主要部件的型式及原理掌握有关的专业名词与术语了解翻译技巧省略,NEWWORDS,particlep:tikln.微粒，颗粒clogklgv.&n.阻塞，堵塞nozzlenzln.喷嘴traptrpn.圈套，陷阱，捕集器plungerplnn.柱塞，活塞variationverieinn.变化，变更，变种，变调protrudeprtru:dv.突出，伸入solenoidsulinidn.螺线管，电磁线圈铁，阀，开关energizeendaizv.供给能量，通电，励磁depressiondiprenn.消沉，萧条；低气压，凹陷，凹坑stackstkn.堆,一堆；v.堆叠piezoelectricpaii:zuilektrika.压电的,fuelpump燃油泵fuelfilter燃油滤清器injectionpump喷油泵fuelline燃油管lighttruck轻型货车inlineinjectionpump直列式喷油泵distributorinjectionpump分配式喷油泵deliveryvalve出油阀spraypattern喷注形状glowplug预热塞intakeairheater进气加热器precombustionchamber预燃室fuelrail油轨pressureshoulder承压锥面，solenoid-typeinjector电磁式喷油器piezoelectricinjector压电式喷油器,PHRASESANDEXPRESSIONS,ConventionalFuelInjectionSystemTypicaldieselfuelinjectionsystemcomponentsincludethefueltank,fuelpump,fuelfilter,injectionpump,injectors,andthenecessaryfuellines(Fig.5-1).,Fig5-1Aconventionaldieselfuelinjectionsystem,FuelFilter.Dieselfuelmustbekeptcleantoavoidinjectorsystemtrouble.Verysmallparticlesareenoughtocloginjectornozzles.Dieselfuelsystemstypicallyuseoneormorefilterstotrapdirtandotherdeposits.InjectionPump.Duetothehighcompression(around22:1)usedindieselengines,thedieselinjectionpumpmustbecapableofproducinghighpressures.Thereareanumberofinjectionpumpdesigns.Themostcommonlyusedautomobileandlighttruckdieselinjectionpumpsareclassifiedasinlineordistributor.Theinlineinjectionpumpusesaseparatecylinder-plunger-camunitforeachcylinder.Theseunitsarecontainedinastraightrowinacommonhousing.Inthedistributorinjectionpump,asingledouble-plungertypepumpservesallinjectoroutlets.Asingledeliveryvalveislocatedintherotor.,Injector.Therearemanydifferentinjectordesigns,butallareavariationoftwobasictypes-inwardopeningandoutwardopening.Dieselspraypatternswillvarydependinguponenginedesign.GlowPlugandIntakeAirHeaters.Toaidinignitingthecompressedair-fuelmixtureduringcoldstarting,dieselenginesuseglowplugsandintakeairheaters.Theglowplugisanelectricallyoperateddevicethatprotrudesintotheprecombustionchamber.Onlaterengines,theglowplugsareturnedonandoffautomatically.Intakeairheaterswarmtheairasitpassesthroughonitswaytotheintakemanifold.Theheaterelementisawiremeshthatiselectricallyheated.Thecomputerenergizestheheaterelementbeforecranking.,CommonRailInjectionSystemNewerdieselenginesareequippedwithcommonrailinjectionsystems(Fig.5-2andFig.5-3).Commonrailsystemsaredirectinjection(DI)systems.Theinjectorsnozzlesareplacedinsidethecombustionchamber.Thepistontophasadepressionwhereinitialcombustiontakesplace.Theinjectormustbeabletowithstandthetemperatureandpressureinsidethecylinderandmustbeabletodeliverafinesprayoffuelintothoseconditions.Thesesystemshaveahighpressurefuelrailconnectedtoindividualinjectors.Theinjectorsarecontrolledbyacomputerthatattemptstomatchinjectoroperationtotheoperatingconditionsoftheengine.,Fig.5-2Commonrail(CR)system,Fig.5-3Boschthird-generationcommonrailsystemwithpiezoelectricinjectors,Theinjectorfacilitatesprecisecontrolofthestartofinjectionandinjectedfuelquantityaswellaspre-andpost-injection.Injectorclosed(reststate).Thefuelflowsthroughthefuel-inletpassageintothevalvecontrolchamberandtotheinjection-nozzlepressureshoulder.Thedischargethrottleisclosedbythevalveball.Thepressureabovethevalvecontrolplungerinthevalvecontrolchambergeneratesaforcewhichisgreaterthantheopposingforcewhichactsonthenozzle-needlepressureshoulder1.Thenozzleneedlethusremainsclosed,regardlessoftherailpressureappliedattheinjector(seeFig.5-4).Injectoropens(startofinjection).WhenthesolenoidvalveisactuatedbytheECU,thearmatureisattracted,asaresultofwhichthevalveballopensthedischargethrottle.Nowmorefuelflowsthroughthedischargethrottlethanthroughtheinletthrottle.Thiscausesadropinpressureinthevalvecontrolchamber.Nowthenozzleneedleisraisedbytheforceacting,onitspressureshoulder.Thenozzleneedleopensandfuelisinjected,seeFig.5-4.Injectorcloses(endofinjection).WhenthesolenoidvalveisnolongersuppliedwithpowerbytheFCU,thevalvespringforcesthevalveballontoitsseat.Asaresult,thedischargethrottleisclosedandthefuelpressurebuildsupagainabruptlyinthevalvecontrolchamber.Theforceactingonthevalvecontrolplungerandtheforceofthenozzlespringactingfromaboveexceedtheforceonthenozzle-needlepressureshoulderactingfrombelow.Thenozzleneedlecloses.Pre-andpost-injection(Fig.5-5).Thesolenoidvalveisonlysuppliedwithpowerforabriefperiodinordertoinjectsmallquantitiesoffuel.Thenozzleneedleisraisedslightly.Thefuelinjectoropensbrieflyandintheprocessdoesnotopentheentireopeningcross-section.,Injectoractivation.Rapidlyswitchingsolenoidvalvesarerequiredinordertobeabletosubdividefuelinjectionintouptothreesequences(pre-,mainandpost-injection).Thiscanonlybeachievedwithhighcurrentsofapprox.20Aandvoltagesofapprox.100V.Thisso-calledboostervoltageisgeneratedwiththeaidofinductionwhenthesolenoidvalvesaresuppliedwithpowerandisstoredinacapacitorintheECU.,Fig.5-4solenoid-typeinjector,Fig.5-5Rate-of-dischargecurve,Newerdieselfuelinjectorsrelyonstackedpiezoelectriccrystalsratherthansolenoids.Inthefuture,thesolenoidvalveswillbereplacedbyfasterpiezoactuators.Thispiezoelectricinjectorwillallowmoreinjectionoperationsperpowerstrokewithsimultaneouslylowenergyconsumption.Inthepiezoelectricinjector,Piezoelectric-crystalsquicklyexpandwhenelectricalcurrentisappli