玉柴CNG单燃料发动机系统组成及工作原理CHN-ENG

玉柴机器股份有限公司YuchaiMachineryCo.Ltd.http：高压的压缩天然气从储气钢瓶出来，经过天然气滤清器过滤后，经高压电磁阀进入高压减压器，高压减压器的作用是将高压的压缩天然气（工作压力200bar-30bar）经过减压加热将压力调整至7bar-9bar。高压天然气在减压过程中由于减压膨胀，需要吸收大量的热量，为防止减压器结冰，须用发动机冷却液在减压器里对燃气进行加热。HighlycompressednaturalgasfromtheNGtankentersthroughthehigh-pressurelockoffvalveintothehighpressureregulatorafterbeingfilteredinthenaturalgasfilter.Theopening/closingofthehigh-pressurelockoffvalveiscontrolledbytheECM.Thehighpressureregulatorisusedtodecompressandheattheinitialhighlycompressednaturalgas(workingpressure30~200bar)intothepressurerangeof7~9bar.High-pressurenaturalgasabsorbsalargeamountofheatduringthedecompressionprocessduetopressurereliefandexpansion.Inordertopreventthehighpressureregulatorfrombeingfrozen,theenginecoolantisdeliveredtothehighpressureregulatorandusedtoheatthenaturalgas.CNG发动机的工作原理CNGEngineWorkingTheory经减压后的天然气进入电控调压器(EPR)，电控调压器的作用是根据发动机运行工况精确控制天然气供给量。天然气与空气在混合器内充分混合，进入发动机缸内，经火花塞点燃进行燃烧，火花塞的点火时刻由ECM控制，氧传感器即时监控燃烧后的尾气的氧浓度，计算出空燃比，ECM根据氧传感器的反馈信号及时修正天然气供给量。Decompressednaturalgasgoesintotheelectronicpressureregulator,whichisusedtopreciselycontrolthenaturalgasinjectionamountaccordingtotheactualengineworkingconditions.Naturalgasissufficientlymixedwithairinthemixerandthenentersintotheengine'scylindersforsparkignition.Thespark'signitiontimingiscontrolledbytheECM.Theoxygensensormonitorstheoxygenconcentrationoftheexhaustproducedaftercombustioninstantaneouslyandcalculatestheair-fuelratioandthentheECMcorrectsthenaturalgasinjectionamountintimeaccordingtothefeedbacksignalsfromtheoxygensensor.增压器提供一个和发动机负荷相应的可变的进气增压压力,而增压器的废气旁通阀可以通过释放涡轮处的排气压力来减小增压压力。这通过一个膜片推动杠杆来完成。当压力提供给膜片时,杠杆移动去打开废气旁通阀。ECI系统利用废气旁通控制阀来控制到废气旁通阀执行器的压力。Theturbo-chargerprovidesanintakeairpressurechangecorrelatingwiththeloadoftheengine.Thewastegateontheturbochargerisdesignedtodumpexhaustpressurearoundtheturbinetoreduceboost.Thisisdonewithadiaphragmoperatedlever.Whenpressureisappliedtothediaphragm,thelevermovestoopenthewastegate.TheECIsystemisdesignedtocontrolthepressuretothewastegateactuatorwiththeWasteGatePressurecontrolvalve.增压压力的控制Turbo-ChargerControl废气旁通控制阀的安装用来阻止压力到废气旁通阀执行器。提供给废气旁通控制阀的压力应该在22～25psig之间。废气旁通控制阀有一个压力传感器监控着到执行器的压力，它根据ECM计算出来的WGP命令大小，或者释放或者把压力送到执行器。TheWasteGatecontrolvalveisinstalledsothatitinterruptsthepressuretothewastegateactuator.Thesupplypressureshouldbebetween22and25psig.IthasapressuresensorthatmonitorsthepressuretotheactuatorandeitherreleasesorsendspressuretoactuatordependingonwhattheWGPcommandcalculatedbytheECMis.增压压力的控制Turbo-ChargerControlECM接收到一个带有IVS的油门踏板传来的代表负载命令的可变电压信号,它然后将这个位置命令其转换成一个负荷百分比命令。因为ECM使用负载命令,然后计算出要达到此负荷需要的MAP目标和TIP目标。TheECMreceivesitsloadcommandfromavariablevoltagesignalthroughafootpedalsensorwithIVS.Itthentranslatesthispositioncommandintoaloadpercentagecommand.BecausetheECMusesloadcommand,itcalculatestwotargetstoachievethisobjective;aMAPtargetandaTIPtarget.负荷的控制LoadControl当发动机的负载朝MAP目标升高时,电子节气门开度和废气旁通阀开度不断调整使MAP压力值达到MAP目标。然后电子节气门再进行调整，使电子节气门前后的压差达到目标值，在调整节气门的过程中不断调整废气旁通阀的开度，保持MAP压力值和目标值一致。AstheengineincreasesinloadtowardstheMAPtarget,thethrottleandWGPcontrolvalveadjustsothattheMAPpressuremeetstheMAPtarget.Thethrottlethenadjustsagainsothatthepressuredropacrossthethrottle(deltaPcommand)ismet,whilemaintainingtheMAPtarget(adjustingboostthroughtheWGP).负荷的控制LoadControl电控调压器(EPR)是通过一个微处理器控制的高速大马力电机驱动的压力调节器。EPR里的微处理器通过CAN通讯接收到从ECM传来的燃料压力指令（EPR燃料出口压力和混合器入口处的空气压力之差），并将EPR内的信息传回给ECM。TheElectronicPressureRegulator(EPR)isapressureregulatorthatisdrivenbyamicroprocessor-controlledhighpowered/fastactingactuator.ThemicroprocessorintheEPRreceivespressurecommandsfromtheECMoveraCANnetworklinkandrelaysinformationaboutthestateoftheEPRbacktotheECM.燃料的控制FuelControl然后EPR内的电机驱动调压器内膜片来调整EPR出口压差值，使这个压差满足ECM指令要求。TheactuatoroftheEPRwillthendrivethediaphragmoftheregulatortoadjustthefuelpressuretothemixersothattheactualdeltaPmatchesthedeltaPcommandfromtheECM.燃料的控制FuelControlCNG发动机燃气系统组成TheComposingofElectronicControlFuelingSystemofYuchaiCNGEngine第二部分SectionTwo高压燃料切断阀：•工作原理：由线圈驱动阀芯，由ECM控制其开合，停机状态下处于常闭状态。•作用：及时切断或恢复燃料供给。•安装要求：为有效防止高压燃料切断阀的进气接头与高压燃料切断阀结合部位漏气，安装该接头时，必须使用螺纹密封胶，并且锁紧接头使铜垫略有变形，有效密封。HighPressureLockoffValve：•Operatingprinciple:ThecoreoftheHighPressureLockoffValveisdrivenbythecoilandthevalve’sopening/closingiscontroledbytheECM.TheHighPressureLockoffValveisalwaysintheclosedpositionintheun-workingconditionoftheengine.•Purpose:Timelycutofforresumefuelsupply.•Installationrequirements:Inordertoeffectivelypreventthenaturalgasleakagefromthejointbetweenthehigh-pressurelockoffvalveanditsintakepipeend,useascrewsealantforpipeendinstallationandtightenthepipeendsoastoslightlydeformthecopperwasherforeffectiveseal.Theinletandoutletshouldbedifferentiatedduringinstallation.高压减压器:•工作原理：通过压力膜片克服弹簧阻力，带动杠杆，调整节流孔的流通面积，从而控制减压后的天然气压力。•作用：通过节流和加热，使高压的压缩天然气减压至7bar-9bar的低压天然气。HighPressureRegulator:•Operatingprinciple:EmploysthePressurediaphragmtoovercomthesprin