atkinson循环对汽油机性能影响的试验分析

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1、Atkinson循环对汽油机性能影响的试验研究AbstractTheAtkinsoncyclewhichusingLateIntakeValveClosing(LIVC)strategythroughVVT(variablevalvetiming)mechanismwasachievedina1.6Lgasolineenginebyreplacingthepistonofhighergeometrycompressionratioandtheintakecamshaftoflongerintakeduration.Comparativinganalysisofexternalcharacte

2、risticanduniversalcharacteristichavebeenmadebetweenOttocycleandAtkinsoncycle.ThenwehavestudiedtheeffectsoftheexternalEGR(ExhaustGasRecirculation)onAtkinsoncycleenginewhichincludsfuelconsumption,combustioncharacteristicinthecylinderandemissioncharacteristics.WehavealsoexploredthestrategyoftheAtkinso

3、ncyclewhichcanfurtherreducethefuelconsumptionthroughusingexternalEGR.Finally,wehaveprovidedthedatasupportofsuperchargingminiaturizationthroughstudyingtheeffectsofthesimulatedsuperchargingonAtkinsoncycleengine,whichincludsdynamicperformance,fuelconsumptionandcombustioncharacteristicinthecylinder.Atf

4、ullloadspoints,AtkinsoncycleenginehasbetterfueleconomybutexcellentdynamicperformancewhichisalmostasthesameastheOttocycleenginethroughmoreintakevalvetimingadvance.TheBSFC(BrakeSpecificFuelConsumption)ofAtkinsoncycleengineislowerthantheOttocycleengineatalloperatingpoints,especiallyintheregionsofthelo

5、wloadatmediumspeed,mediumtohighloadatmediumtohighspeedandhighspeed,whichhavebeenimprovedobviously.Theareacoveredby250g/(kW•h)contourlineofAtkinsoncycleengineisalmosttwicebiggerthantheOttocycleengine.ThemainreasonswhyAtkinsoncycleenginehasbetterfueleconomyisthatthehighereffectivecompressionratioande

6、ffectiveexpansionratiowhichimprovethethermalefficiency.AmoderateamountofEGRcanimprovethefueleconomyofAtkinsoncycleengine.Threeloads(0.2MPa,0.4MPa,0.6MPa;BMEP)atthespeedof2200rpmhavebeenselected.TheoptimalEGRratiosofthesethreeoperatingpointsare5%,10%,15%andtheBSFCdeclines0.94%,1.34%and2.17%.Whenthec

7、ircumstanceofadoptingMBT(MinimumsparkadvanceforBestTorque),andtheloadincreases,thetoleranceforEGRofAtkinsoncycleenginegraduallyhavebeenenhanced.AhigherEGRratioresultsinahighermaximumcylinderpressure,butthep