zf as tronic系列-适用于各种商用车辆的自动变速器-毕业论文外文翻译

THEZFASTRONICFAMILYAUTOMOTIVETRANSMISSIONSFORALLCOMMERCIALVEHICLECLASSES1REQUIREMENTSFORCOMMERCIALVEHICLETRANSMISSIONSCUSTOMERSDEMANDHIGHEFFICIENCYALONGWITHINCREASINGVEHICLECOMFORTANDSAFETYASANINDEPENDENTTRANSMISSIONMANUFACTURER,ZFCUSTOMERNEEDSINCLUDETHENEEDSOFDRIVERS,FORWARDINGCOMPANIES,ANDVEHICLEMANUFACTURERSTHEREFORE,ZFCONSIDERSTHEMANYREQUIREMENTSTHATANEWTRANSMISSIONCONCEPTMUSTFULFILLWHENDEVELOPINGATRANSMISSION,FIGURE1KEEPINGCOSTSLOWISACONSIDERABLECHALLENGE,INITIALLYINTERMSOFACQUISITIONANDLATERDURINGOPERATIONTHATISWHYFUELCONSUMPTIONISINCREASINGLYONEOFTHEDECISIVEVEHICLEFEATURESTHATSEPARATETHECOMPETITIONAMODERNTRANSMISSIONCANMAKEANIMPORTANTCONTRIBUTIONHEREONTHEONEHANDBYIMPROVINGEFFICIENCYANDONTHEOTHERHANDINAUTOMATICTRANSMISSIONSBYTHEOPTIMALSELECTIONOFTHEGEARRATIODEPENDENTONTHEDRIVINGSITUATIONREDUCINGTHETRANSMISSION,SWEIGHTALSOLEADSTOREDUCEDCOSTSUSINGLESSMATERIALREDUCESACQUISITIONCOSTSANDENABLINGAHIGHERPAYLOADREDUCESOPERATINGCOSTSONTHEONEHAND,DECREASEDOILCONSUMPTIONCONTRIBUTESTOENVIRONMENTALPROTECTIONADDITIONALLY,ITHASANIMMEDIATEINFLUENCEONTHECOSTS,HOWEVER,THATACCRUETHROUGHOUTTHEVEHICLESSERVICELIFETHEDEMANDFORSYSTEMCOMFORTINCREASINGLYAPPROACHESTHESTANDARDSETBYCARTECHNOLOGY,WHEREASINTHISCASELIMITSARESETBYMASSRATIOSANDCOSTCONSTRAINTS图1商用车辆的需求FIG1REQUIREMENTSFORCOMMERCIALVEHICLESLOWNOISEEMISSIONSAREARESULTOFLEGALREGULATIONSONTHEONEHANDBUTALSOCONTRIBUTETOMORECOMFORTABLEDRIVERWORKPLACESWHENMETFURTHERMORE,ELECTRONICSYSTEMSINCREASINGLYSUPPORTTHEDRIVERANDRELIEVEHIM/HERFROMROUTINETASKSTHISBENEFITSSAFETYINTRAFFIC2ADVANCESWITHAUTOMATICTRANSMISSIONSAUTOMATICTRANSMISSIONSCANSATISFYMANYOFTHEDEMANDSTHATCUSTOMERSMAKEONCOMMERCIALVEHICLESCONSIDERABLYBETTERTHANMANUALTRANSMISSIONSDESPITETHEFACTTHATAUTOMATICTRANSMISSIONSAREGENERALLYMOREEXPENSIVE,IFONETAKESTHECOMPLETEINSTALLEDMANUALTRANSMISSIONSYSTEMINCLUDINGTHEGEARSHIFTSYSTEMINTOACCOUNT,THEDIFFERENCEINACQUISITIONCOSTSISNOLONGERASGREATMOREOVER,THEGOALOFFUTUREDEVELOPMENTSISTOFURTHERREDUCETHECOSTSFORAUTOMATICTRANSMISSIONSEVENTODAYTHEHIGHERACQUISITIONCOSTSAREALREADYPAYINGFORTHEMSELVESRELATIVELYQUICKLYDUETOLOWEROPERATINGCOSTSSOTHATAUTOMATICTRANSMISSIONSAREECONOMICALLYADVANTAGEOUSINTHELONGRUNTHEEFFICIENCYOFTHEASTRONICFAMILYOFTRANSMISSIONSISCOMPARABLETOAMANUALTRANSITIONHOWEVER,ASARULE,THESHIFTINGPOINTSELECTIONISBETTERDUETOTHEAPPLICATIONOFANAUTOMATICDRIVINGSTRATEGY,WHICHPOSITIVELYAFFECTSFUELCONSUMPTIONALONGTERMSTUDYCONDUCTEDBYZFANDDEKRAFOUNDTHATTHEAUTOMATICSHIFTINGPOINTSELECTIONREPRESENTSTHECONSUMPTIONPERFORMANCEOFAVERYGOOD,CONCENTRATEDDRIVERTHUS,AVERAGINGALLDRIVERSANDDRIVINGSITUATIONSINACOMMERCIALFLEET,CONSUMPTIONISREDUCEDONTHEORDEROF3PERCENTSINCETHEENGINEOPERATESRELIABLYINTHEOPTIMUMSPEEDRANGEWITHREGARDTOFUELCONSUMPTIONAPROCESSTHATISCONTROLLEDINDEPENDENTLYOFTHEDRIVER,SQUALIFICATIONANADDITIONALADVANTAGEINTERMSOFOPERATINGCOSTSISREDUCEDCLUTCHWEARREDUCEDDIFFERENTIALSPEEDSDURINGSTARTINGANDSHIFTINGOPERATIONSLENGTHENTHESERVICELIFEOFTHECLUTCH,WHICHHASALSOBEENPROVENINLONGTERMTESTSMANYVEHICLEMANUFACTURERSTAKETHISINTOACCOUNTANDOFFERASIGNIFICANTLYLONGERWARRANTYCOVERONTHECLUTCHINASTRONICTRANSMISSIONSBYAUTOMATINGTHECLUTCH,THECLUTCHPEDALISNOLONGERNEEDED,WHICHCLEARLYSIMPLIFIESOPERATIONFORTHEDRIVER,PARTICULARLYINSTOPANDGOTRAFFICORWHENMANEUVERINGTHEAUTOMATICGEARSELECTIONRELIEVESTHEDRIVERFROMSHIFTINGASWELL,WHEREBYHE/SHECANCONCENTRATEBETTERONROADTRAFFICHOWEVER,ATTHESAMETIME,THEDRIVERCANENGAGEMANUALLYATANYTIME,FORINSTANCEINDRIVINGSITUATIONSWHERETHEDRIVERSFORWARDFIELDOFVISIONISINQUESTIONTHISTAKESPLACEACCORDINGTOSHIFTBYWIREVIAANELECTROMECHANICALCONTROLSWITCHSOTHATONLYVERYLITTLEACTUATINGFORCESAREAPPLIEDWHENMANUALLYSELECTINGGEARSTHERAPIDAUTOMATICSHIFTINGANDTHEPROTECTIONAGAINSTOPERATINGERRORALSOCONTRIBUTETOTHEINCREASEINDRIVERCOMFORTWHILEATTHESAMETIMEPROTECTINGTHETRANSMISSIONANDDRIVELINEINADDITION,THEABSENCEOFAMECHANICALLINKBETWEENSHIFTLEVERANDTRANSMISSIONREDUCESCABINNOISEUSINGANAUTOMATICTRANSMISSIONALSOHASADVANTAGESFORVEHICLEMANUFACTURERSLIKETHECLUTCHCONTROL,THECOMPLETESHIFTLINKAGEISNOLONGERNEEDED,WHICHMAKESBOTHLEFTANDRIGHTHANDSTEERINGVEHICLESEASYTOMANUFACTUREWHENDESIGNINGTHEDRIVERWORKPLACE,ANYTHINGISPOSSIBLEINTERMSOFOPERATINGTHETRANSMISSION3THEZFASTRONICFAMILYZFBEGANDEVELOPINGAUTOMATEDMANUALTRANSMISSIONSFORCOMMERCIALVEHICLESEARLYTHEFIRSTPRODUCTWASAPARTIALLYAUTOMATEDTRANSMISSIONWITHAUTOMATICPRESELECTION,WHICHWASINTRODUCEDINTOTHEMARKETIN1984TENYEARSLATER,ANAUTOMATEDTRANSMISSIONFOLLOWEDWITHTHEINTRODUCTIONOFTHEFIRSTASTRONICHOWEVER,THEDRIVERSTILLHADTOSELECTGEARSITSSUCCESSORMODELWASFIRSTEQUIPPEDWITHANINTELLIGENTSHIFTPROGRAM,WHICHHASBEENINPRODUCTIONSINCE1998THUS,AFULLYAUTOMATICSOLUTIONWASOFFEREDINAHEAVYCOMMERCIALVEHICLEFORTHEFIRSTTIMETHECHOSENTRANSMISSIONCONCEPTFORASTRONICRESULTEDINTHEMOSTEFFICIENTSOLUTIONPOSSIBLEFORLARGERVOLUMESEXTENSIVEINTEGRATIONANDREMOVALOFUNNECESSARYCOMPONENTSOPENEDUPPOTENTIALCOSTSAVINGSASAGROUPDRIVE,ASTRONICISDESIGNEDWITHANUNSYNCHRONIZEDBASICTRANSMISSIONANDSYNCHRONIZEDSPLITTERANDRANGECHANGEGROUP,FIGURE2INORDERTOREDUCETHEWEIGHTOFTHETRANSMISSION,ADESIGNWITHTWOCOUNTERSHAFTSWAS图2ZFASTRONIC的3D剖示图FIG2ZFASTRONIC3DSECTIONCUTCHOSEN,WHICHISOPTIMALINTHISPERFORMANCECLASSINTERMSOFWEIGHTDUETOAMODULARDESIGNANDABASICTRANSMISSIONWITH3OR4SPEEDS,L6PEED,12SPEED,AND10SPEEDVARIANTSCOULDBEREPRESENTEDINTHEBASICTRANSMISSION,THESYNCHRONIZATIONSWEREREPLACEDWITHSHIFTDOGS,BECAUSETHESYNCHRONIZATIONCANTAKEPLACEBYCONTROLLINGTHEINTERNALCOMBUSTIONENGINEINMODERNEDCENGINESANADDITIONALTRANSMISSIONBRAKEISTHENREQUIREDFORUPSHIFTS,WHICHISLOCATEDONONEOFTHETWOCOUNTERSHAFTSASTANDARDDRYCLUTCHISUSEDITISFULLYAUTOMATICSOTHATACLUTCHPEDALISNOLONGERNECESSARYALLAUTOMATEDCOMPONENTSAREPNEUMATICALLYOPERATEDANDARECOMBINEDWITHINMODULESTHATAREINTEGRATEDINTOTHETRANSMISSIONHOUSINGTHECOORDINATEDOPERATIONOFTRANSMISSION,CLUTCH,ANDENGINETAKESPLACEBYELECTRONICCONTROL,WHICHISLOCATEDINTHESHIFTMODULETHEINTERFACESTOTHEOUTSIDEWEREMINIMIZEDASTRONICWASINITIALLYLIMITEDTOTORQUESOF2,300NM12SPEEDAND2,600NM16SPEEDAFTERWARD,VARIANTSWEREINTRODUCEDINATWOSTEPDEVELOPMENT,WHICHEXPANDTHETORQUERANGESOF12SPEEDTRANSMISSIONSUPWARDSASTRONICISOFFEREDINDIRECTDRIVEANDOVERDRIVEDESIGNSANDISGENERALLYAVAILABLEWITHANINTEGRATEDSECONDARYRETARDER“INTARDERAUTOMATICTRANSMISSIONSHAVEFOUNDINCREASINGACCEPTANCEINHEAVYCOMMERCIALVEHICLESINTHEPASTFEWYEARSANDENJOYENORMOUSPOPULARITYAMONGCUSTOMERSHOWEVER,THEADVANTAGESOFTHESETRANSMISSIONSAREALSODEMONSTRATEDESPECIALLYINLIGHTANDMEDIUMDUTYCOMMERCIALVEHICLESVEHICLESINTHESECLASSESAREPRIMARILYUSEDINCITYANDREGIONALTRAFFICRELIEFFROMOPERATINGTHETRANSMISSIONANDTHECLUTCHISESPECIALLYIMPORTANTINTHISCASEBECAUSETHETRAFFICENVIRONMENTREQUIRESTHEDRIVERSFULLATTENTIONFURTHERMORE,THISSECTORISMARKEDBYAHIGHNUMBEROFUNTRAINEDDRIVERSANDFREQUENTDRIVERTURNOVERTHEREFORE,REDUCINGTHEDRIVERSINFLUENCEONFUELCONSUMPTIONANDCLUTCHWEARISANUNMISTAKABLEADVANTAGE,NOTTOMENTIONSAFEGUARDINGAGAINSTTRANSMISSIONANDCLUTCHDAMAGECAUSEDBYTHEDRIVERFORTHESEREASONSZFDECIDEDTOEXPANDTHEPRODUCTPORTFOLIOFORAUTOMATICTRANSMISSIONSSYSTEMATICALLYINTOTHEAREAOFLOWTORQUES,FIGURE3图3变速器型谱ZFASTRONIC的转矩范围FIG3TRANSMISSIONPORTFOLIOTHEZFASTRONICPRODUCTSWITHTORQUERANGESSTARTINGFROMTHETECHNICALFUNDAMENTALPRINCIPLETWOPEDALSOLUTIONSWITHAUTOMATICSHIFTINGANDACUSTOMERBENEFITTHATISCOMMENSURATEWITHTHEASTRONICSMALLERASTRONICTRANSMISSIONWILLBEDEVELOPEDASWELLTHEYRECEIVEADDITIONALCODINGTOTHEIRGENUINEDESIGNATIONINORDERTOMARKTHEIRASSOCIATIONTOTHERESPECTIVEVEHICLEAPPLICATIONSASTRONICMIDWILLBEUSEDFORAPPLICATIONSFROM800NMTO1,600NM；ASTRONICLITEWILLCOVERTRUCKSINTHELOWERTORQUERANGEUPTO1,050NMWITH6SPEEDTRANSMISSIONS4ZFASTRONICMIDTHEVEHICLESECTORWHERETHEASTRONICMIDSERIESWILLBEUSEDISVERYSENSITIVETOPRICEANDHIGHLYDIFFERENTIATEDINTERMSOFAPPLICATIONTYPESTHUS,MIDRANGEVEHICLESWILLSERVICEBOTHDISTRIBUTORANDLONGDISTANCETRANSPORTASWELLASCONSTRUCTIONSITESTHEREFORE,ONEOFTHEFOCALPOINTSOFDEVELOPMENTLIESINACOSTEFFECTIVEDESIGNTHATWILLFULFILLTHEMANYANDDIVERSECUSTOMERREQUIREMENTSEASILYANDALSOCOVERTHEWIDETORQUERANGECONSISTENTPRODUCTPLANNINGLEDTOTHEDEVELOPMENTOFANUNCOMPROMISINGMIDRANGETRANSMISSIONSERIESDESIGNEDFORAUTOMATIONITENCOMPASSESSEVENTRANSMISSIONTYPESCOMBINEDINTOONEMODULARDESIGNWITH840MMSHORTAND900MMLONGTRANSMISSIONVARIANTS,THEMODULARDESIGNCONCEPTISPRIMARILYBASEDONTHEVARIATIONOFTHEWHEELWIDTHSINORDERTOCOVERTHETORQUERANGESUPTO1,200NMAND1，600NMRESPECTIVELYBOTHTRANSMISSIONLENGTHSWILLBEOFFEREDINDIRECTANDOVERDRIVEDESIGNSCOMPAREDTOTHEASTRONIC,THEASTRONICMIDTRANSMISSIONSAREAPPROX50TO65KGLIGHTERINORDERTOOPTIMIZECOSTS,ACONSISTENTCOMPLEXITYMANAGEMENTSYSTEMWASPURSUEDAPPROXIMATELY40OFTHECOMPONENTSWERETAKENFROMEXISTINGTRANSMISSIONSINPRODUCTIONATZFINORDERTOOFFERUNIFORMAUTOMATIONTECHNOLOGYFORALLCOMMERCIALVEHICLESINTHEMIDRANGEANDHEAVYDUTYSECTORS,THEPROVENASTRONICCOMPONENTSSUCHASTRANSMISSION/CLUTCHACTUATORS,ELECTRONICS,ANDSOFTWAREWEREUSEDDUETOTHEINTERFACEEQUALITYTHISACHIEVED,THEVEHICLEMANUFACTURERCANOFFERBOTHASTRONICANDASTRONICMIDSERIESINALMOSTIDENTICALVEHICLESWITHVARIOUSDRIVELINEVARIANTSATMINIMALEXPENSEINAPRELIMINARYCONCEPTSTUDY,VARIOUSGEARSETCONCEPTSWERECONSIDEREDEIGHTGEARSETFORMULASWERECOMPAREDUSINGELEVENSELECTEDEVALUATIONCRITERIAINTERMSOFFUNCTION,COSTS,ANDDEADLINEINORDERTOPROVIDETHISCOMPLEXDECISIONMATRIXWITHTHENECESSARYTRANSPARENCY,ADECISIONMAKINGSOFTWARETOOLWASUSEDTHECHOICEWASMADEFORA12SPEEDGEARSET2X3X2,WHICHISCOMPARABLETOACONVENTIONAL9SPEEDGEARSETINTERMSOFDESIGNSPACEANDWEIGHTANDEVENHASADVANTAGESCOMPAREDTOA10SPEEDGEARSET,FIGURE4图4ZFASTRONICMID变速器剖示图FIG4ZFASTRONICMIDINCOMPLETEVIEWITCONSISTSOFENGAGINGANDDISENGAGINGINPUTCONSTANTSSPLITTERGROUP,3SPEEDMAINTRANSMISSION,ANDANOUTPUTENDPLANETARYDRIVESTAGERANGECHANGEGROUPSYNCHRONIZATIONSAREUSEDINTHESPLITTERANDRANGECHANGEGROUPTHEMAINTRANSMISSIONSHIFTINGELEMENTSAREDESIGNEDASDOGSTHEGEARSTEPSHASASLIGHTLYPROGRESSIVEGEARINTERVALDUETOASMALLINCREASEINTHEGEARRATIOTHUS,ATATOTALGEARSPREADOFAPPROX128,THEGEARRATIOOF238FROM11THTO12THSPEEDISONPARWITHACOMPARABLE16SPEEDTRANSMISSIONFORTHEFIRSTTIME,THEGEARRATIOOFTHEREVERSEGEARWASDESIGNED131,IESLOWERTHAN1STGEARONARANGECHANGEGROUPTRANSMISSIONBYANOFFSETENGAGEMENTOVERTHEREVERSEIDLERGEARINCLOSECOOPERATIONWITHTHECUSTOMERS,HIGHDRIVABILITYWASALREADYEMPHASIZEDINTHESPECIFICATIONPHASEUPONCOMPLETIONOFTHEROUGHDESIGN,THEDRIVABILITYRELEASECRITERIAOFONECUSTOMERWEREALREADYPROVENINSIMULATIONSADETAILEDCOSTANALYSISOFTHEGEARUNITSINZFTRANSMISSIONSLEDTOTHEDESIGNOFTHEPLANETARYREARMOUNTEDRANGECHANGEGROUPINTHEASTRONICMID，INWHICHTHEMOSTCOSTEFFECTIVESOLUTIONSWEREADOPTEDINEACHCASETHUS,THEDESIGNOFTHENEWGEARUNITISMARKEDBYTHESYNCHRONIZATIONOFTHEASTRONICANDTHEGEARSETDESIGNOFTHEECOSPLITFIGURE5THEBEARINGSOFTHESWINGFORKINTHERANGECHANGEGROUPAREREALIZEDBETWEENTHETWO图5ZFASTRONICMID行星齿轮传动FIG5ZFASTRONICMIDPLANETARYDRIVEDETAILHOUSINGPARTS,WHICHMINIMIZESSEALPOINTSTOTHEOUTSIDEANDPOSSIBLECORROSIONWEAKPOINTSTHECLUTCHACTUATINGCYLINDERWASTURNEDINDRIVINGDIRECTIONFROMTHE6OCLOCKPOSITIONFORASTRONICTOTHE8OCLOCKPOSITIONFORASTRONICMIDTHISNOTONLYINCREASESVEHICLEROADCLEARANCEANDBRINGSTHEACTUATINGCYLINDEROUTOFTHEDANGERZONE,ITALSOOFFERSTHEFLEXIBILITYTOREACTTOPOTENTIALREQUIREMENTSPUSHEDCLUTCHRELEASEUNDERCOMPRESSIONDIFFERENTFROMTHEASTRONIC,THEASTRONICMIDGEARSETWILLONLYBEDESIGNEDWITHONECOUNTERSHAFTTHESOLUTIONWASTHEBESTINAPARAMETERSTUDYFORTHETORQUERANGECONSIDERED,WHICHTAKESINTOACCOUNTBOTHTHEMODULARDESIGNASPECTSASREGARDSOPTIMALGEARSETLENGTHVARIATIONASWELLASTHELEGALLYPERMITTEDNOISEREQUIREMENTSASARESULT,THEDEVELOPERFACEDANADDITIONALCHALLENGEIFTHEOILPUMPANDTRANSMISSIONBRAKEAREEACHDRIVENBYONECOUNTERSHAFTINTHEASTRONIC,THENBOTHCOMPONENTSNOWMUSTBECOMBINEDINAJOINT,COSTEFFECTIVEBRAKEPUMPMODULEMAXIMIZINGTRANSMISSIONEFFICIENCYINORDERTOREDUCEFUELCONSUMPTIONATTRACTEDMUCHINTERESTDURINGDEVELOPMENTBYCONSISTENTLYCHANGINGSPLASHLUBRICATIONTOINJECTIONLUBRICATION,QUASIDRYSUMPLUBRICATIONWASACHIEVEDSOTHATDIVINGLOSSESDONOTOCCURINORDERTOOPTIMIZETHELUBRICATIONSYSTEM,OILFLOWCALCULATIONSWERECONDUCTEDTHEOILITSELFWASHANDLEDLIKEASTRUCTURAL/DESIGNELEMENTZFHASWORKEDINTENSIVELYFORYEARSWITHLUBRICANTMANUFACTURERSINORDERTODEVELOPSYNTHETICOILSSUCHASTHEZFECOFLUIDM,WHICHISUSEDINTHESETRANSMISSIONSTHISOILHASLOWVISCOSITYANDTHEREFORECONTRIBUTESLOWINTERNALLOSSESHOWEVER,ATTHESAMETIMEITOFFERSSUFFICIENTLUBRICATINGFILMTOGUARANTEETHESERVICELIFEOFGEARS,BEARINGS,ANDSYNCHRONIZATIONSANADDITIONALADVANTAGEOFECOFLUIDMISHIGHSTABILITY,WHICHMAKESCLEARLYLONGEROILCHANGEINTERVALSPOSSIBLEANDGREATLYREDUCESOILCONSUMPTIONSHIFTDOGSINTHEMAINTRANSMISSIONANDACOMPACTTRANSMISSIONDESIGNWITHSMALLCENTERDISTANCEALSOCONTRIBUTETOLOSSREDUCTIONALLTHESEMEASURESTOGETHERINCREASEDTHEEFFICIENCYINTHEDIRECTGEARFROM992TO996UNDERCOMPARABLEOPERATINGCONDITIONSACTIVEHEATMANAGEMENTENABLEDADDITIONALFUELSAVINGSIFTHETRANSMISSIONRUNSATAPPROX60OILSUMPTEMPERATUREONROAD,THEOILVISCOSITYCANBEFURTHERREDUCEDBYADDITIONALLYHEATINGTO80INTHISCASE,ASTRONICMIDISOPTIONALLYAVAILABLEFORTHEADDITIONOFAHIGHLYINTEGRATEDHEATEXCHANGERSHORTPAYBACKPERIODSOFAPPROX,ONEYEARAREENSUREDBYCOSTEFFECTIVELYINTEGRATINGTHEHEATEXCHANGERCARTRIDGEWITHTHEINTEGRATEDBYPASSVALVEINTHEOILCIRCULATIONONTHEINTAKESIDEZFASTRONIC系列适用于各种商用车辆的自动变速器1商用车辆变速器的需求客户的要求是在提高车辆舒适性和安全性的同时也提高效率。作为一个独立的变速器制造商，ZF公司的客户还包括驾驶人员、运输公司和车辆制造商。因此，ZF认为在开发变速器时就必须考虑到应满足各种需求，（图1。继续降低制造和使用成本是一个很大的挑战。这就是燃油经济性为什么正成为车辆竞争的决定性因素之一的缘故。一个现代化的变速器具有以下贡献一方面通过优化速比改进效率、实现自动化、降低变速器重量以减少成本、减少金属材料用量降低制造成本、提供更大的有效载荷降低使用成本等。另一方面，减少燃油消耗还有助于环境保护，它直接影响到使用成本，因而可提高车辆的服务寿命。对系统舒适性需求的增加已成为车辆技术的标准配置，尽管这受制于档位数量和成本限制。低噪声一方面是由于法规要求，同时也提高了驾驶员工作环境的舒适程度。进一步而言，为驾驶员提供支持的电子系统减轻了他们的工作任务。这有益于交通安全。2自动变速器的优点自动变速器比手动变速器更能满足客户对商用车辆的需求。除了自动变速器成本较高的事实外，但如果考虑到手动变速器及相应的换档操纵系统的话，两者成本的差距并不太大。因此进一步发展的目标是降低自动变速器的成本。图1商用车辆的需求FIG1REQUIREMENTSFORCOMMERCIALVEHICLES在今天，较高的制造成本由于更低的使用成本而迅速补偿，因此自动变速器最终具有经济性方面的优势。将ZFASTRONIC系列变速器与手动变速器相比，由于采用了自动驾驶模式其换档点的选择更具优势，这有助于燃油经济性。一项由ZF和DEKRA公司的长期研究发现换档点的自动确定相当于一个具有高超技术驾驶员集中精力的驾驶。因而一个具有平均驾驶水平的车队燃油消耗可降低3，因为发动机能可靠地工作在最佳速度区域，而整个过程与驾驶员的素质无关。另一个优点是可降低离合器的磨损。在起步和换档过程中减少滑差可增加离合器的使用寿命，这己被长期试验所证明。许多车辆制造商为配置ASTRONIC变速器的车辆提供更长的离合器保修期限。采用自动离合器后，离合器踏板己不再需要，简化了驾驶员的工作，特别是在频繁起步、停车工况下。档位自动选择解放了驾驶员的换档动作，驾驶员的注意力可集中在道路交通上。同时,驾驶员仍可在任何时候切换为手动模式，例如当驾驶员视野出现问题时。这些都根据线控换档系统和机电一体化的控制开关完成，因此在手动换档时仅需很小的操纵力。迅速地自动换档和防止操纵失误增加了驾驶舒适性，同时也保护了变速器和传动系。另外变速器和换档操纵杆之间无机械联接可降低驾驶室的噪声。使用自动变速器对车辆制造商也有好处。像离合器控制和换档操纵装置己不再需要，方便制造转向盘左置和右置的车辆。在设计驾驶员工作区域时更能随心所欲。3ZFASTRONIC系列ZF早就开始开发适用于商用车辆的机械自动变速器。第一个产品是带自动预选档位的半自动变速器，在1984年投入市场。十年后，推出的是ASTRONIC的第一代产品，但是驾驶员仍需要选择换档。在1998年，其后续产品采用了智能化的换档程序，而全自动化的产品则首先用于重型商用车辆。选择ZFASTRONIC变速器将具有更好大批量装车的可能性。高度集成和省略不必要的元件使得在降低成本方面仍具潜力。作为一组合式变速器，ASTRONIC被设计成由不带同步器的主变速器、前置同步分流的副变速器和扩展速比的后置副变速器组成，图2。图2ZFASTRONIC的3D剖示图FIG2ZFASTRONIC3DSECTIONCUT为减轻主变速器的重量，采用了双副轴结构。由于主变速器是3或4档，因此可构成16、12和10档的变速器。在主变速器，同步器被换档档块所替换，因为同步过程可由现代化的EDC发动机完成。一个附加的变速器制动装置用于升档，它位于两副轴之一上。采用标准的干式离合器。由于是全自动变速器故无需离合器踏板。所有的换档元件由气压操纵并被以模块形式集成在变速器壳体上。利用电控系统控制变速器、离合器及发动机，该装置安装在换档模块上。外部界面做成最小。ASTRONIC的输入转矩为2300NM12速）和2600NM16速）。副变速器具有2档速比，它能扩大12速变速器的转矩。ASTRONIC提供直接传动和超速，通常集成一个第二缓速器“INTARDER”。在过去几年里，自动变速器在商用车辆上的应用正在增加并赢得了消费者的巨大信任。然而，变速器的优点主要体现在轻型和中型商用车辆上。这些车辆主要行驶在城市和近郊交通繁忙的区域。这时减轻变速器和离合器的操作特别重要，因为交通情况需要驾驶员集中全部精力。另外，车辆是由大量非专业人员驾驶而且频繁更换驾驶员。因此减少驾驶员对燃油消耗和离合器磨损的影响是一个显著的优点，同时也减少了驾驶员对变速器和离合器的伤害。为此ZF决定系统地扩展自动变速器的产品型谱，如图3。从技术基本原则开始，即采用两个踏板的ASTRONIC是解决自动换档和方便驾驶的方法，因此也将开发较小的ASTRONIC变速器。对应于实际产品它们都有图3变速器型谱ZFASTRONIC的转矩范围FIG3TRANSMISSIONPORTFOLIOTHEZFASTRONICPRODUCTSWITHTORQUERANGES附加的代码以表示其各种的车辆应用场合。ASTRONICMID适用于800NM到1600NMASTRONICLITE是适用于卡车的6档变