机械专业论文中英文对照_Word文档格式.doc

机械专业论文中英文对照_Word文档格式.doc

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19

ISSN1400-1179

ISRN/KTH/MMK/R-08/19-SE

DepartmentofMachineDesign

RoyalinstituteofTechnology

SE−10044Stockholm,Sweeden

©

MatsÅ

kerblom2008

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）,ProfessorSö

renAndersson（KTH）,andDr.LarsBrå

the（Volvo）.ThefinancialsupportoftheSwedishFoundationforStrategicResearchandtheSwedishAgencyforInnovationSystems–VINNOVA–isgratefullyacknowledged.VolvoConstructionEquipmentisacknowledgedforgivingmetheopportunitytodevotetimetothiswork.ProfessorSö

renAnderssonisgratefullyacknowledgedforexcellentguidanceandencouragement.IalsowishtoexpressmyappreciationtomycolleaguesattheDepartmentofMachineDesign,andespeciallytoDr.UlfSellgrenforperformingsimulationsandcontributingtothewritingofPaperD,andDr.StefanBjö

rklundforperformingsurfacefinishmeasurements.ThecontributionstoPaperCbyDr.MikaelPä

rssinenarehighlyappreciated.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

Experiencehasshownthatthehighfrequ