文章编号：1006—8244(2006)03—03—10TheZF··ASTronicFamily·-AutomotiveTransmissionsforAIICommercialVehicleClassesDr．Frank-DetlefSpeck，MarcusRaeder，Dr．ChristophRiichardt，[Abstract]ZFdevelopedanewautomatictransmission--ASTronicFamily，whichcanfulfillthecustomersrequirements．TheASTronicFamilycoverstrucksinthelowertorquerangeupto2600Nmandhas6、10、12and16speed．TheASTroniccanmakeanimportantcontributioninruelconsumption．10wnoiseemissions，morecomfortabledrivingandsafelytraffic．1RequirementsforCommercialVehicleTransmissionsCustomersdemandhighefficiencyalongwithin—creasingvehiclecomfortandsafety．Asaninderpendenttransmissionmanufacturer，ZFcustomerneedsincludetheneedsofdrivers，forwardingcompaniis，andvehiclemanufacturers．Therefore，ZFconsidersthemanyrequirementsthatanewtransmissionconceptmustfulfillwhendevelopingatransmission，Figure1．Keepingcostslowisaconsiderablechallenge，initiallyintermsofacquisitionandlaterduringoperation．Thatiswhyfuelconsumptionisincreasinglyoneofthedecisivevehiclefeaturesthatseparatethepetition．Amoderntransmissioncanmakeanimportantcontributionhere：Ontheonehandbyimprovingefficiencyandontheotherhandinautomatictransmissionsbytheoptimalselectionofthegearratiodependentonthedrivingsituation．Redueingthetransmissionweightalsoleadstoreduedcosts：Usinglessmaterialreducesacquisitioncostsandenablingahigherpayloadreducesoperatingcosts．Ontheonehand。decreasedoilconsumptioncontributestoenvironmentalprotection：additionally，ithasanimmediateinfluenceonthecosts，however，thataccruethroughoutthevehicleservice1ife．Thedemandforsystemcomfortincreasinglyapproachesthestandardsetbycartechnology，whereasinthiseaselimitsaresetbymassratiosandcostconstraints．LOWnoiseemissionsareare—suitoflegalregulationsontheonehandbutalsocontributetomorecomfortabledriverworkplaceswhenmet．Furthermore，electronicsystemsincreasinglysupportthedriverandrelievehim／herfromroutinetasks．Thisbenefitssafetyintraffic．2AdvanceswithAutomaticTransmissionsAutomatictransmissionscansatisfymanyofthedemandsthatcustomersmakeoncommereivehicleconsiderablybetterthanmanualtransmissions．Despitethefactthatautomatictransmissionaregenerallymoreexpensive，ifonetakesthetompleteinstalledmanualtransmissionsystemincludingthegearshiftsystemintoaccount，thedifferenceinacquisitioncostsisnolongerasgreat．Moreover，thegoaloffuturedevelopmentsistofurtherreducethecostsforautomatictransmissions．EventodaythehigheracquisitioncostsarealreadypayingforthemselvesrelativelyquicklyduetoloweroperatingcostSOthatautomatictransmissionsareeconomicallyadvantageousintherun．TheefficiencyoftheASTronicfamilyoftransmissionsiscomparabletoamanualtransition；however，asarule，theshiftingpointselectionisbetterduetotheapplicationofanautomaticdrivingstrategy，whichpositivelyaffectsfuelconsumption．AlongtermstudyconductedbyZFandDEKRAfoundthattheautomaticshiftingpointse—lectionrepresentstheconsumptionperformanceofverygood，concentrateddriver．Thus，averagingalldriversanddrivingsituationsinacommercialfleet，consumptionisreducedontheorderof3per—centsincetheengineoperatesreliablyintheopti—mumspeedrangewithregardtofuelconsumption；aprocessthatiscontrolledindependentlyofthedriver’Squalification．AnadditionaladvantageintermsofoperatingcostsISreducedclutchwear．Reduceddifferentialspeedsduringstartingandshiftingoperationslengthentheservice...