文献翻译采用表面微加工技术制造微型行星齿轮减速器.docx

文献翻译采用表面微加工技术制造微型行星齿轮减速器.docx

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文献翻译采用表面微加工技术制造微型行星齿轮减速器

翻译部分

英文原文

MICROPLANETARYREDUCTIONGEARUSINGSURFACE-MICROMACHINING

Abstract

Amicroplanetarygearmechanismfeaturingahighgearreductionratiowithcompactnessinsizeispresentedinthispaper.SUMMiTVisemployedforthefabricationmethodsothattheredundancyofassemblingpartsiseliminated.Thedesignrulesofwhichhasalsobeenchecked.Tomakefulluseofthebenefitsofthesurface-micro-machining,theplanetaryreductiongearisdesignedtowardusingtheon-chipmicro-engine.Theexpectedgearreductionratioiscalculatedandcomparedwiththeconventionalchaingearmechanism.Themicroplanetarygearmechanismpresentedinthispaperisexpectedtohave162:

1reductionratioutilizinglessspaceconsumption.Thisisanorderofmagnitudehigherthanthepreviouslyreporteddesigninasinglereductiongeartrain.

Keywords:

MEMS,planetarygear,reductiongearsurface-micromachining,SUMMiTVprocess

Nomenclature

asungear

bplanetgears

cinternalgear（fixed）

dinternalgear（rotary）

nthenumberofunitsofgeartrain

Ddiameterofthepitchcircle

Nnumberofteeth

Pnumberofplanets

angularvelocity

Introduction

Thegearmechanismsinmicroelectromechanicalsystems（MEMS）arecommonlyexpectedtogeneratehightorqueintheconfinedmicro-sizesystems.However,itisgenerallydifficultforthemicro-scalesystemstohavesuchahightorquewithouthavingmultiplereductionsystems.

Thedesignofthereductiongeardrivebasedonaplanetaryparadoxgearmechanismcanincreasethetorquewithinacompactarea,sincethemicroplanetarygearsystemhasanadvantageofhighreductionratioperunitvolume[1].Howeveritsmechanismissocomplicatedthatrelativelyfewattemptshavebeenmadetominiaturizethegearsystems[2-3].Suzumorietal.[2]usedthemechanicalparadoxplanetarygearmechanismtodrivearobotfor1-inpipesforwardorbackward.Theyemployedasinglemotortodrivethegearmechanismswithhighreductionratio.Precisegearfabricationwasenabledbymicrowireelectricaldischargemachining（micro-EDM）.Theseparts,however,shouldbeassembledbeforethedrivemotorisattachedtothegearbox.Takeuchiet.al.[3]alsousedmicro-EDMtofabricatethemicroplanetarygears.TheysuggestedspecialcermetsorHighCarbonSteelforpossiblematerials.Whilethedesigncanachieveareductionratioof200,thegearsshouldalsobeassembledandmotordriven.Toenablethedrivingoftheplanetarygearbyonchipmeans,SandiaUltra-planarMulti-levelMEMSTechnology（SUMMiT-V）process[4]forplanetarygearfabricationisadoptedinthisstudy.TheSUMMiT-Vprocessistheonlyfoundryprocessavailablewhichutilizesfourlayersofreleasablepolysilicon,foratotaloffivelayers（includingagroundplane）[5].Duetothisfact,itisfrequentlyusedincomplicatedgearmechanismsbeingdrivenbyon-chipelectrostaticactuators[5].However,inmanycases,themicroenginesmaynotproduceenoughtorquetodrivethedesiredmechanicalload,sincetheirelectrostaticcombdrivestypicallyonlygenerateafewtensofmicronewtonsofforce.Fortunately,theseenginescaneasilybedrivenattensofthousandsofrevolutionsperminutes.Thismakesitveryfeasibletotradespeedfortorque[7].Rodgersetal.[7]proposedtwoduallevelgearswithanoverallgearreductionratioof12:

1.Thussixofthesemodulartransmissionassembliescanhavea2,985,984:

1reductionratioatthecostofthehugespace.

Withthedesireforsizecompactnessandatthesametime,highreductionratios,theplanetarygearsystemispresentedinthispaper.Itwillbethefirstplanetarygearmechanismusingsurfacemicromachining,totheauthorsknowledge.Theprinciplesofoperationsoftheplanetarygearmechanism,fabrication,andtheexpectedperformanceoftheplanetarygearsystemsaredescribedinthispaper.

Principlesofoperation

Analternativewayofusinggearstotransmittorqueistomakeoneormoregears,i.e.,planetarygears,rotateoutsideofonegear,i.e.sungear.Mostplanetaryreductiongears,atconventionalsize,areusedaswell-knowncompactmechanicalpowertransmissionsystems[1].TheschematicoftheplanetarygearsystememployedisshowninFigure

SinceSUMMiTVdesignsarelaidoutusingAutoCAD2000,theFigure1isgeneratedautomaticallyfromthelayoutmasks（Appendix[1]）.Oneunitoftheplanetarygearsystemiscomposedofsixgears:

onesungear,a,threeplanetarygears,b,onefixedringgear,c,onerotatingringgear,d,andoneoutputgear.Thenumberofteethforeachgearisdifferentfromoneanotherexceptamongtheplanetarygears.Aninputgearisthesungear,a,drivenbythearmconnectedtothemicro-engine.Therotatingringgear,d,isservedasanoutputgear.Forexample,ifthearmdrivesthesungearintheclockwisedirection,theplanetarygears,b,willrotatecoun