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机械专业论文中英文对照
GearboxNoise
CorrelationwithTransmissionErrorandInfluenceofBearingPreload
DoctoralThesisinMachineDesign
TRITA-MMK2008:
19
ISSN1400—1179
ISRN/KTH/MMK/R-08/19-SE
DepartmentofMachineDesign
RoyalinstituteofTechnology
SE−10044Stockholm,Sweeden
©MatsÅkerblom2008
ABSTRACT
Thefiveappendedpapersalldealwithgearboxnoiseandvibration。
Thefirstpaperpresentsareviewofpreviouslypublishedliteratureongearboxnoiseandvibration。
Thesecondpaperdescribesatestrigthatwasspeciallydesignedandbuiltfornoisetestingofgears。
Finiteelementanalysiswasusedtopredictthedynamicpropertiesofthetestrig,andexperimentalmodalanalysisofthegearboxhousingwasusedtoverifythetheoreticalpredictionsofnaturalfrequencies.Inthethirdpaper,theinfluenceofgearfinishingmethodandgeardeviationsongearboxnoiseisinvestigatedinwhatisprimarilyanexperimentalstudy.Eleventestgearpairsweremanufacturedusingthreedifferentfinishingmethods。
Transmissionerror,whichisconsideredtobeanimportantexcitationmechanismforgearnoise,wasmeasuredaswellaspredicted。
Thetestrigwasusedtomeasuregearboxnoiseandvibrationforthedifferenttestgearpairs.Themeasurednoiseandvibrationlevelswerecomparedwiththepredictedandmeasuredtransmissionerror.Mostoftheexperimentalresultscanbeinterpretedintermsofmeasuredandpredictedtransmissionerror.However,itdoesnotseempossibletoidentifyonesingleparameter,suchasmeasuredpeak—to—peaktransmissionerror,thatcanbedirectlyrelatedtomeasurednoiseandvibration.Themeasurementsalsoshowthatdisassemblyandreassemblyofthegearboxwiththesamegearpaircanchangethelevelsofmeasurednoiseandvibrationconsiderably。
Thisfindingindicatesthatotherfactorsbesidesthegearsaffectgearnoise。
Inthefourthpaper,theinfluenceofbearingendplayorpreloadongearboxnoiseandvibrationisinvestigated。
Vibrationmeasurementswerecarriedoutattorquelevelsof140Nmand400Nm,with0。
15mmand0mmbearingendplay,andwith0。
15mmbearingpreload.Theresultsshowthatthebearingendplayandpreloadinfluencethegearboxvibrations。
Withpreloadedbearings,thevibrationsincreaseatspeedsover2000rpmanddecreaseatspeedsbelow2000rpm,comparedwithbearingswithendplay。
Finiteelementsimulationsshowthesametendenciesasthemeasurements.Thefifthpaperdescribeshowgearboxnoiseisreducedbyoptimizingthegeargeometryfordecreasedtransmissionerror。
Robustnesswithrespecttogeardeviationsandvaryingtorqueisconsideredinordertofindageargeometrygivinglownoiseinanappropriatetorquerangedespitedeviationsfromthenominalgeometryduetomanufacturingtolerances.Staticanddynamictransmissionerror,noise,andhousingvibrationsweremeasured。
Thecorrelationbetweendynamictransmissionerror,housingvibrationsandnoisewasinvestigatedinspeedsweepsfrom500to2500rpmatconstanttorque。
Nocorrelationwasfoundbetweendynamictransmissionerrorandnoise。
Staticloadedtransmissionerrorseemstobecorrelatedwiththeabilityofthegearpairtoexcitevibrationinthegearboxdynamicsystem.
Keywords:
gear,gearbox,noise,vibration,transmissionerror,bearingpreload.
ACKNOWLEDGEMENTS
ThisworkwascarriedoutatVolvoConstructionEquipmentinEskilstunaandattheDepartmentofMachineDesignattheRoyalInstituteofTechnology(KTH)inStockholm。
TheworkwasinitiatedbyProfessorJackSamuelsson(VolvoandKTH),ProfessorSörenAndersson(KTH),andDr。
LarsBråthe(Volvo).ThefinancialsupportoftheSwedishFoundationforStrategicResearchandtheSwedishAgencyforInnovationSystems–VINNOVA–isgratefullyacknowledged.VolvoConstructionEquipmentisacknowledgedforgivingmetheopportunitytodevotetimetothiswork。
ProfessorSörenAnderssonisgratefullyacknowledgedforexcellentguidanceandencouragement。
IalsowishtoexpressmyappreciationtomycolleaguesattheDepartmentofMachineDesign,andespeciallytoDr.UlfSellgrenforperformingsimulationsandcontributingtothewritingofPaperD,andDr.StefanBjörklundforperformingsurfacefinishmeasurements。
ThecontributionstoPaperCbyDr.MikaelPärssinenarehighlyappreciated.AllcontributionstothisworkbycolleaguesatVolvoaregratefullyappreciated。
1INTRODUCTION
1。
1Background
Noiseisincreasinglyconsideredanenvironmentalissue.Thisbeliefisreflectedindemandsforlowernoiselevelsinmanyareasofsociety,includingtheworkingenvironment。
Employeesspendalotoftimeinthisenvironmentandnoisecanleadnotonlytohearingimpairmentbutalsotodecreasedabilitytoconcentrate,resultingindecreasedproductivityandanincreasedriskofaccidents.Quality,too,hasbecomeincreasinglyimportant。
Thequalityofaproductcanbedefinedasitsabilitytofulfillcustomers’demands。
Thesedemandsoftenchangeovertime,andthebestcompetitorsinthemarketwillsetthestandard.Noiseconcernsarealsoexpressedinrelationtoconstructionmachinerysuchaswheelloadersandarticulatedhaulers。
Thegearboxissometimesthedominantsourceofnoiseinthesemachines。
Evenifthegearnoiseisnottheloudestsource,itspurehighfrequencytoneiseasilydistinguishedfromothernoisesourcesandisoftenperceivedasunpleasant。
Thenoisecreatesanimpressionofpoorquality.Inordernottobeheard,gearnoisemustbeatleast15dBlowerthanothernoisesources,suchasenginenoise。
1.2Gearnoise
Thisdissertationdealswiththekindofgearboxnoisethatisgeneratedbygearsunderload.Thisnoiseisoftenreferredtoas“gearwhine"andconsistsmainlyofpuretonesathighfrequenciescorrespondingtothegearmeshfrequencyandmultiplesthereof,whichareknownasharmonics。
Atonewiththesamefrequencyasthegearmeshfrequencyisdesignatedthegearmeshharmonic,atonewithafrequencytwicethegearmeshfrequencyisdesignatedthesecondharmonic,andsoon。
Theterm“gearmeshharmonics”referstoallmultiplesofthegearmeshfrequency.Transmissionerror(TE)isconsideredanimportantexcitationmechanismforgearwhine。
Welbourn[1]definestransmissionerroras“thedifferencebetweentheactualpositionoftheoutputgearandthepositionitwouldoccupyifthegeardrivewereperfectlyconjugate.”Transmissionerrormaybeexpressedasangulardisplacementoraslineardisplacementatthepitchpoint。
Transmissionerroriscausedbydeflections,geometricerrors,andgeometricmodifications。
Inadditiontogearwhine,otherpossiblenoise-generatingmechanismsingearboxesincludegearrattlefromgearsrunningagainsteachotherwithoutload,andnoisegeneratedbybearings.Inthecaseofautomaticgearboxes,noisecanalsobegeneratedbyinternaloilpumpsandbyclutches.Noneofthesemechanismsaredealtwithinthiswork,andfromnowon“gearnoise"or“gearboxnoise”refersto“gearwhine"。
MackAldener[2]describesthenoisegenerationprocessfromagearboxasconsistingofthreeparts:
excitation,transmission,andradiation.Theoriginofthenoiseisthegearmesh,inwhichvibrationsarecreated(excitation),mainlyduetotransmissionerror。
Thevibrationsaretransmittedviathegears,shafts,andbearingstothehousing(transmission)。
Thehousingvibrates,creatingpressurevariationsinthesurroundingairthatareperceivedasnoise(radiation)。
Gearnoisecanbeaffectedbychanginganyoneofthesethreemechanisms。
Thisdissertationdealsmainlywithexcitation,buttransmissionisalsodiscussedinthesectionoftheliteraturesurveyconcerningdynamicmodels,andinthemodalanalysisofthetestgearboxinPaperB.TransmissionofvibrationsisalsoinvestigatedinPaperD,whichdealswiththeinfluenceofbearingendplayorpreloadongearboxnoise.Differencesinbearingpreloadinfluenceabearing'sdynamicpropertieslikestiffnessanddamping.Thesepropertiesalsoaffectthevibrationofthegearboxhousing。
1。
3Objective
Theobjectiveofthisdissertationistocontributetoknowledgeaboutgearboxnoise.Thefollowingspecificareaswillbethefocusofthisstudy:
1.Theinfluenceofgearfinishingmethodandgearmodificationsanderrorsonnoiseandvibrationfromagearbox。
2。
Thecorrelationbetweengeardeviations,predictedtransmissionerror,measuredtransmissionerror,andgearboxnoise.
3.Theinfluenceofbearingpreloadongearboxnoise。
4.Optimizationofgeargeometryforlowtransmissionerror,takingintoconsiderationrobustnesswithrespecttotorqueandmanufacturingtolerances。
2ANINDUSTRIALAPPLICATION−TRANSMISSIONNOISEREDUCTION
2.1Introduction
Thissectionbrieflydescribestheactivitiesinvolvedinreducinggearnoisefromawheelloadertransmission。
TheaimistoshowhowtheoptimizationofthegeargeometrydescribedinPaperEisusedinanindustrialapplication.Theauthorwasprojectmanagerforthe“noiseworkteam”andperformedthegearoptimization。
Oneoftherequirementswhendevelopinganewautomaticpowertransmissionforawheelloaderwasimprovingthetransmissiongearnoise.Theexistingpowertransmissionwasknowntobenoisy。
Whendrivingathighspeedinfourthgear,ahighfrequencygear—whinecouldbeheard。
Thustherewerenowdemandsforimprovedsoundquality。
Thetransmissionisatypicalwheelloaderpowertransmission,consistingofatorqueconverter,agearboxwithfourforwardspeedsandfourreversespeeds,andadropboxpartlyintegratedwiththegearbox。
Thedropboxisachainoffourgearstransferringthepowertotheoutputshaft。
Thegearsareengagedbywetmulti—discclutchesactuatedbythetransmissionhydraulicandcontrolsystem。
2。
2Gearnoisetargetforthenewtransmission
Experiencehasshownthattheh