机械专业论文Gearbox Noise.docx
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机械专业论文Gearbox Noise.docx
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机械专业论文GearboxNoise
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
Experiencehasshownth
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