Baja动力总成设计外文文献翻译、中英文翻译、外文翻译

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1、DesignofanSAEBajaRacingOff-RoadVehiclePowertrainIwasfortunateenoughtobeabletoleadpowertraindesignontheBajateamfortwoyearsinarow,whichallowedmetonotonlytesttheoriesandmodifythem,butalsotolearnfrommistakes.Abriefreviewofthe2014carpowertraindesignisinorder,asitinformsmanyofthedesigndecisionsmadeforthe2

2、015Bajacar.The2014AkronBajaCar(ZB14)usesaComet780seriesCVTcoupledtoatwostagechainreductiontocoupletheEnginetothe22inchdiametertires.Thelayoutofthischainreductionwasdesignedwithtwothingsinmind.First,therewasadesiretoseetheaccelerationbenefitsofraisingtheEnginehigherinthecar,thusraisingthecenterofmass

3、ofthecarandthesubsequentlongitudinalweighttransferduringacceleration.Thisincreaseinlongitudinalweighttransferwouldtheoreticallyprovidemoretractiveabilityforthereartiresduringanaccelerationrun.Thesecondobjectiveofthechainlayoutwastoreducethewheelbaseasmuchaspossible.Wefoundthattherewasnottoomuchbenef

4、itgainedbytheincreasedheightofthecenterofgravityduringacceleration.Inaddition,thenegativeeffectthishighercenterofgravityhadonlateralhandlingandrollovercompletelyoutweighsanypositiveaccelerationeffectsgainedbyaraisedengine.Ideally,thebottomoftheengineshouldbeplacedaslowaspossibleforthebesthandlingcar

5、.Theshorterwheelbaseaccomplishedwiththeuniquepackingofthedrivelinedidhelpwithnavigatingtightobstaclesinmaneuverability,asdemonstratedbyour22ndfinishinmaneuverabilityatthe2014competitioninIllinois(Seeresultscompilationinappendixforfullplacementdetails).Thiscarwasalsousedtoverifytheeffectivenessoftheg

6、earreductionratiocalculatedfromtheorythatwillpresentedlaterinthisreport.Fromthistestingitwasfoundthatonlyaslightmodificationtotheoriginallycalculatedgearratiowasnecessarytoreachawellperformingvehicle.ChainDriveversusSpurGearDriveBeforethedesignofthepowertrainforthe2015AkronZipsBajaRacecar(ZB15)could

7、begin,animportantdecisionneededtobemade.ThisdecisionwaswhethertouseanuncoveredchainreductionsimilartoZB14ortouseanenclosed,continuously-lubricatedspurgearbox.BothselectionshavestrengthsandweaknessesandeachaspectofwhatmakesasoundBajapowertrainmustbeexaminedtodeterminewhichtypeisbetter.Eachofthecatego

8、riesthatwillserveastheperformancemetricsbywhichtocomparethetransmissiontypeswillbemeasuredonascalefrom1to5.Ifatransmissiontypereceivesa5inanyparticularcategory,itwillmeanthatthatparticulartransmissiontypefulfillsthatperformancemetricbetterthananyothertransmissiontypeknowntothisapplication.Asweightis

9、ofoverwhelmingpertinenceinaracingapplication,itmustbethefirstmetricunderconsideration.Thedoublechainreductionhasbeenshowntobealightweightsetup,butrequiresmanyheavymountingtubesontheframeinitsoriginalconfiguration.Apreliminarysurveyofteamswithwell-testedsingle-speedgearboxesshowsthatanoptimizedweight

10、forgearsandgearcaseisaround12-15pounds.Combiningthiswith30poundsfortheCVT/beltand50poundsfortheengineyieldsanapproximatetransmissionweight(ignoringCVaxles)ofroughly92-95pounds.Thisisincomparisontothe109.46poundsthatthetransmissionontheAkronBaja2014carweighedinat.However,someconsiderationmustbemadeth

11、atthisgearboxwouldbeafirstiterationforourteam,sowemustaddatleast10to15poundsinordertobeconservativeuntilwelearnhowtomakegearswell.Evenwiththeextraconservatism,thegeardrivewillreceivearatingof4forweightwhilethechaindrivereceivesaratingof3forweight.CostChaindrivesareverycommonforthistypeofapplicationi