汽车自动变速外文翻译英文

汽车自动变速外文翻译英文
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文章编号：1006—8244(2006>03—03—10
The ZF··AS Tronic Family·-Automotive Transmissions
forAII Commercial Vehicle Classes
Dr．Frank-Detlef Speck，Marcus Raeder，Dr．Christoph
Riichardt，b5E2RGbCAP
[Abstract]ZF developed a new automatictransmission--AS Tronic Family，which can fulfill the customersrequirements．The AS Tronic Family covers trucks
in the lower torque range up to 2600Nm and has 6、10、12 and 16 speed．The AS Tronic can make an important contribution in ruel consumption．10w noise emissions，more comfortable driving and safely traffic．p1EanqFDPw
1 Requirements for Commercial VehicleTransmissions
Customers demand high efficiency along with in—creasing vehicle comfort and safety．As an inderpendent transmission manufacturer，ZF customerneeds include the needs of drivers，forwarding companiis，and vehicle manufacturers．Therefore，ZF considers the many requirements that a new transmission concept must
fulfillwhen developing a transmission，Figure 1．Keepingcosts low is a considerable challenge，initially interms of acquisition and later during operation．That is why fuel consumption is increasingly one ofthe decisive
vehicle features that separate the petition．A modern transmission can make an important contribution here：On the one hand by improvingefficiency and on the other hand
in automatic transmissions by the optimal selection of thegear ratio dependent on the driving situation．Redueing the transmission weight also leads to redued costs：Using less material reduces acquisitioncosts and enabling a higher payload reduces operating costs．On the one hand。

decreased oil consumption contributes to environmental protection：additionally，it has an immediate influence on the costs，however，that accrue throughout the vehicleservice 1ife．The demand for system comfort increasinglyapproaches the standard set by car technology，whereas in thisease limits are set by mass ratiosand cost constraints．LOW noise emissions are a re—suit of legal regulations on the one hand but alsocontribute to more comfortable driver workplaceswhen met．Furthermore，electronic systems increasinglysupport the driver and relieve him／herfrom routine tasks．This benefits safety in traffic．DXDiTa9E3d
2 Advances with Automatic Transmissions
Automatic transmissions can satisfy many ofthe demands that customers make on commereivehicleconsiderablybetterthanmanualtransmissions．D espite the fact that automatic transmissionare generally more expensive，if one takes the tomplete installed manual transmission system including the gearshift system into account，the difference in acquisition costs is no longer as great．Moreover，the goal of future developments is to further reduce the costs for automatic transmissions．Even today the higher acquisition costs arealready paying for themselves relatively quicklydue to lower operating cost SO that automatictransmissions are economically advantageous
in the run．The efficiency of the AS Tronic family oftransmissions is comparable to a manual transition；however，as a rule，the shifting point selection isbetter due to the application of an automatic drivingstrategy，which positively affects fuel consumption．A longterm study conducted by ZF andDEKRA found that the automatic shifting point se—lection represents the consumption performance of very good，concentrated driver．Thus，averagingall drivers and driving situations in a commercialfleet，consumption is reduced on the order of 3 per—cent since the engine
operates reliably in the opti—mum speed range with regard to fuel consumption；a process that is controlled independently of thedriver’S qualification．An additional advantage in terms of operatingRTCrpUDGiT
costs IS reduced clutch wear．Reduced differentialspeeds during starting and shifting operationslengthen the service life of the clutch，whichhas al—SO been proven in long—term tests．Many vehicleemanufacturers take this into account and offer a signfieantly longer warranty cover on the clutch in ASTronic transmissions．By automating the clutch，the clutch pedal isno longer needed，which clearly simplifies operationfor thedriverparticularlyin stop—and—go—traffic orwhenmaneuvering．The automatic gear selectionrelieves the driver from shifting as well，wherebyhe／she can concentrate better on road traffic．H OW—ever，at the same time，the driver can engage manually at any time，for instance in driving situationswhere the driver forward field of vision IS inquestion．This takes place according to Shift—by—Wire via an electromechanical contr01 switch SO thatonly very little actuating forces are applied whenmanually selecting gears．The rapid automaticshifting and the protection against operating
errorals0 contribute to the increase in driver comfortwhile at the same time protecting the transmissionand driveline．In addition，the absence of a mechanical link between shift lever and transmission red cabin noise．Using an automatic transmission also has ad—vantages for vehicle manufacturers．Like the clutchcontrol。

the complete shift linkage is no longer needed，which makes both left and
right hand steeringvehicles easy to manufacture．When designing thedriver workplace，anything is possible in terms ofoperating the transmission．5PCzVD7HxA
3 The ZF-AS Tronic Family
ZF began developing automated manual trans—missions for commercial vehicles early．The firstproduct was a partially automated transmissionwith automatic pre—selection，which was introducedinto the market in 1 984．Ten years later，an automatedtransmission followed with the introductionof the first AS Tronic；however，the driver stillhad to select gears．Its successor model was first e—quipped with an intelligent shift program，whichhas been in production since 1 998．Thus，a fullyautomatic solution was offered in a heavy commercial vehicle for the first time．jLBHrnAILg
The chosen transmission concept for AS Tronic resulted in the most efficient solution possible forlarger volumes．Extensive integration and remoralof unnecessary components opened up potential costsavings．As a group drive，AS Tronic is designedwith an unsynchronized basic transmission and synchronized splitter and range change group，Figure2．In order to reduce the weight of the transmission，a design with two countershafts was chosen，which is optimal in this performance class in termsof weight．Due to a modular design and a basictransmission with 3 or 4 speeds，1 6一speed，1 2一speed，and 1 0一speed variants could be represented．In the basic transmission，the synchronizationswere replaced with shift dogs，because the synchronization can take place by controlling the internalcombustion engine in modern EDC engines．An additional transmission brake is thenrequired for up—shifts，which is located on one of the two countershafts．A standard dry clutch is used．It is fully automatic SO that a clutch pedal is no longer neeessary．All automated components are pneumaticallyoperated and are combined
within modules that areintegrated into the transmission housing．The coordinated operation of transmission，
clutch，and enginetakes place by electronic control，which is located in the shift module．The interfaces to the outsidewere minimized．AS Tronic was initially limited to torques of 2，300 Nm(12一speed>and 2，600 Nm(16一speed>．Afterward，variants were introduced in a two—step development，which expand the torque ranges of 1 2一speed transmissions upwards．AS Tronic is offerin direct drive and overdrive designs and is generally available with an integrated secondary retarder“Intarder．’’Automatic transmissions have found increasingacceptance in heavy commercial vehicles in the pastfew years and enjoy enormous popularity amongcustomers．However，the advantages of thesetransmissions are also demonstrated especially inlight and medium—duty commercial vehicles．Vehicles in these classes are primarily used in city andregional traffic．Relief from operating the transmission and the clutch is especially important in thiscase because the traffic environment requires thedriver’S full attention．Furthermore，this sector ismarked by a high number of untrained drivers andfrequent driver turnover．Therefore，reducing thedriver’S influence On
fuel consumption and clutchwear is an unmistakable
advantage，not to mentionsafeguarding against transmission and clutch dam—age caused by the driver．For these reasons ZF decided to expand theproduct portfolio for automatic transmissions systematically into the area of low torques，Figure 3．Starting from the technical fundamental principle—two—pedal solutions with automatic shifting and acustomer benefit that is commensurate with the ASTronicsmaller AS Tronic transmission will be developed as well．They receive additional coding totheir genuine designation in order to mark their association to the respective vehicle applications．As Tronic mid will be used for applications from 800Nm to 1，600 Nm；AS Tronic liter will cover trucksin the lower torque range up to 1，050 Nm with 6一speed transmissions．xHAQX74J0X
4 ZF—AS Tronic mid
The vehicle sector where the AS Tronic midseries will be used is very sensitive to price andhighly differentiated in terms of application types．Thus，midrange vehicles will service both and long-distance transport as construction sites．Therefore，one of the focal points of developmentlies in fl cost—effective design that
willfulfill the many and diverse customer
requirementseasily and also cover the wide torque range．Consistent product planning led to the development of an uncompromising midrange transmissionseries designed for automation．It encompasses seven transmission types combined into one modulardesign．With 840 mm sh9rt and 900 mm long trans—mission variants，the modular design concept is primarily based on the variation of the wheel widths inorder to cover the torque ranges up to 1，200 Nmand 1，600 Nm respectively．Both transmissionlengths will be offered in direct and overdrive designs．Compared to the AS Tronic，the AS Tronicmid transmissions are approx．50 to 65 kg lighter．In order to optimize costs，a consistent complexitymanagement system was pursued。

Approximately40％of the components were taken from existingtransmissions in production at ZF．In order to offer uniform automation technology for all commercial vehicles in the midrange andheavy-duty sectors，the proven AS Tronic components such as transmission／clutch actuators，electronics，and software were used．Due to the interfacequality this achieved，the vehicle manufacturer can offer both AS Tronic and AS Tronic mid series in almost identical vehicles with various drivevariants at minimal expense．In a preliminary
concept study，various gearset concepts were considered．Eight gear set formulas were compared using eleven selected evaluationcriteria in terms of function，costs，and deadline．In order to provide this complex decision matrixwith the necessary transparency，a decision-makingsoftware tool was used．The choice was made for a1 2一speed gear set(2 x3 x2>，which is comparable toconventional 9一speed gear set in terms of designspace and weight and even has advantages comparedto a 10一speed gear set，Figure 4．It consists of engaging and disengaging input constants(splitegroup>，3一speed main transmission，and an output—end planetary drive stage(range changegroup>．Synchronizations are used in the splitter and rangechange group；the main transmission shifting elements are designed as dogs．The gear steps has aslightly progressive gear interval due to a smallincrease in the gear ratio．Thus，at a total gearspread of approx．12．8，the gear ratio of 23．8％from 11th to 12th speed is on par with a comparable1 6一speed transmission．For the first time，the gearratio of the reverse gear was designed 13．1，i．e．slower than 1 gear on a range change group trans—mission by an offset engagement over the reverse
idler gear．In close cooperation with the customers，high drivability was already emphasized in the spec—ifcation phase．Upon completion of the rough de—sign，the drivability release criteria of one customerLDAYtRyKfE were already proven in simulations．A detailed cost analysis of the gear units in ZFtransmissions led to the design of the planetanyrear-mounted range—change group in the AS Tronicmid，in which the most cost-effective solutionswere adopted in each case．Thus，the design of theZzz6ZB2Ltk
new gear unit is marked by the synchronization ofthe AS Tronic and the gear set design of the Eco—split，Figure 5．The bearings of the swing fork inthe range change group are realized between thetwo housing parts，which minimizes seal points tothe outside and possible corrosion weak points．The clutch actuating cylinder was turned in drivingdirection from the 6 clock position for AS Tronicto the 8 clock position for AS Tronic mid．Thisnot only increases vehicle road clearance and bringsthe actuating cylinder out of the danger zone，it al—so offers the flexibility to react to potential requirements pushed clutch release under compression．Different from the AS
Tronic，the AS Tronic mid gear set will only be designed with one counter—shaft．The solution was the best in a parameterstudy for the torque range considered，which takesinto account both the modular design aspects as regards optimal gear set length variation as well asthe legally permitted noise requirements．As a re一suit，the developer faced an additional challenge．Ifthe oil pump and transmission brake are each drivenby one countershaft in the AS Tronic，then bothcomponents now must be combined in a joint，cost—effective brake—pump module．Maximizing transmission efficiency in order toreduce fuel consumption attracted much interestduring development． By consistently changingsplash lubrication to injection lubrication．Quasidrysump 1ubrication was achieved SO that diving lossesdo not occur．In order to optimize the lubricationsystem，oil flow calculations were conducted．Theoil itself Was handled like a structural／design element，ZF has worked intensively for years with lubricant manufacturers in order to developsyntheticcoils such as the ZF-Ecofluid M．which is used Ithesetransmissions．This oil has low viscosity andtherefore contributes Winternol losses；however，at the
same time it offers sufficient lubricating guarantee the service life of gears，bearings，andsynchronizations． An additional advantage ofEcofluid M is high stability，which makes clearlylonger oil change intervals possible and greatly reduces oil consumption．Shift dogs in the main transmission and a corn—pact transmission design with small center distancealso contribute to 10SS reduction．A1l these measures together increased the efficiency in the directgear from 99．2 to 99．6％under comparable operatingconditions．Active heat management enabledadditional fuel savings．If the transmission runs atapprox．60。

C oil sump temperature on-road，the oilviscosity can be further reduced by additionallyheating to 80。

C．In this case，AS Tronic mid is optionally available for the addition of a highly integrated heat exchanger．Short payback periods ofapprox．one year are ensured by cost—effectively integratingthe heat exchanger cartridge with the integratedbypass valve in the oil circulation on theintake side．dvzfvkwMI1
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