机械专业毕业设计外文翻译相关外文文献

机械设计制造及其自动化专业毕业设计外文翻译相关外文文献

SensorsandActuatorsA103(2003)291±300

Review

Miniaturepiezoelectricmotors

TakeshiMorita*

CeramicsLaboratory,DepartmentofMaterial,SwissFederalInstituteofTechnology,Lausanne,

EPFL,CH-1015Lausanne,SwitzerlandReceived12July2002;receivedinrevisedform01August2002;accepted12August2002

Abstract

Thereisgreatdemandformicro-orminiaturizedactuatorsforpracticalapplication.However,magneticcoilsofelectromagneticmotorsareanobstacletosuchminiaturizationbecauseoftheircomplicatedconstruction.Furthermore,electrostaticmicro-motorsfabricatedbyIC-processingcannotgeneratesuf®cientoutputpower.Piezoelectricmotorsarepromisingbecauseoftheirsimpleconstructionandhighpower

Idensity.nfact,somepiezoelectricactuatorshavebeenorareclosetobeinglaunchedinthemarket.Fortheirminiaturization,proper

fabricationprocessesincludingthickdepositionmethodsareimportant.nthisreview,variousprinciplesofpiezoelectricmotorsareintroducedinadditiontosuitablefabricationprocesses.#2002ElsevierScienceB.V.Allrightsreserved.

Keywords:Actuator;Micro-motor;Ultrasonicmotor;Ferroelectric®lm

1.Introduction

Thedemonstrationsofmicro-electrostaticmotorsinthelater1980sareworthytonote[1±4].Byutilizingthesiliconmicro-processingtechnique,electrostaticmotorsweremin-iaturizedtoacoupleofhundredmicrometerindiameterandtheadvantageofanelectrostaticforceinthemicro-®eldisemphasizedbyPaschen'sLaw[5].ThesedemonstrationsledtoarapidexpansionofresearchinMEMSseekingthepracticalapplicationofmicro-actuatorsinmedical,military,outerspaceandindustrial®elds.

AlthoughelectrostaticmotorsplayedanimportantroleinstimulatingMEMSresearch,theirsmalldimensionsand¯atshapemadeitimpossibletogeneratesuf®cientoutputforce.Theoutputtorqueofvariablecapacitiveelectrostaticmicro-motorswerearoundonly10pNm[6,7].Fujimotoetal.[8]studiedalargersizedelectrostaticmotorwhosediameterwas5.5mm,althoughthegeneratingtorquewasonly10nNm.Forpracticalapplications,millimeterorsub-millimetersizedmotorsmightbeattractive.Forexample,inmicro-surgery,insectscaledrobotsormicro-positioningstages,actuatorslessthan1mm3mightnotberequired.Insteadofsmalldimensions,higheroutputpowerisacriticalpara-Presentaddress:PhononDeviceLaboratory,ResearchInstituteofElectricalCommunication,TohokuUniversity,2-1-1Katahira,Aoba-ku,Sendai980-8577,Japan.Tel.: 81-22-217-5527;fax: 81-22-217-5527.E-mailaddress:tmorita@http://www.77cn.com.cn(T.Morita).

*meterandsomeminiatureelectromagneticmotorshavebeenstudiedfromthisperspective[9±11].TheiroutputtorquelevelsweremNmwithafewmillimetersindiameter,howevertheconstructionswererathercomplicatedbecauseoftheirmagneticcoils,andtheirlowtorquewithhighspeedrequiredareductiongearbox.

Abbasetal.[12]triedto®ndasuitablerotationalmotorforinstallationintomedicalcatheters.Thetargetdiameterwasbetween1and2mm,howeverelectrostaticandelec-tromagneticmotorswererejectedduetotheirdrawbacksandunfortunately,piezoelectricmotorswerenottakenintoconsiderationintheirinvestigation.

Piezoelectricmotors,suchasultrasonicmotors,cangen-eratealargeoutputtorquewithverysimpleconstructions.Adirectdriveandaholdingtorquecontributeasmartsystemthathasnoreductiongearboxandnobrakemechanism.However,ofcourse,piezoelectricmotoralsohaveproblems.Forminiaturization,toovercomethefragilityofpiezoelec-tricceramics,specialfabricationprocesses,includingathick®lmdepositionprocess,arerequired.Moreover,http://www.77cn.com.cningtheseintelligentprinciples,themotorshavebeenoperatedsuccessfullywithasmallamplitudeordisplacement.

Thispaperreviewsvariousfabricationprocessesforpiezoelectricmaterialandminiaturepiezoelectric

motors.

0924-4247/02/$±seefrontmatter#2002ElsevierScienceB.V.Allrightsreserved.PII:S0924-4247(02)00405-3

机械设计制造及其自动化专业毕业设计外文翻译相关外文文献

292T.Morita/SensorsandActuatorsA103(2003)291±300

2.Piezoelectricmaterials

energyAnadvantagesizeddominantmotorsdensitycanofof4electromagneticactuatorsistheirhighbeÂ105J/m3with1T,m 1.Centimeter-atactuatorinconventionalfabricatedwithoutuseisthedif®cultymagneticsomotortheresultpresent.disadvantage.

intheHowever,complicatedinsmallerstructuresizedwhichmotors,canmagneticbeaseriouscoilsElectrostaticenergydensityisquitesmall(4Â10J/m3withenergy3Âadensity.106V/m,Although,E 1)acomparedmaximumtoelectromagneticexample,smallerangapelectricalisincreased®elddueofto1:7Paschen'selectrical®eldÂ108Law.withFor122:5mV/mwithatheÂ10m8energyV/mgapdensitywaswaseasilyreported[13]andusingSiO2®lm,iscalculatedrealized[5]to.Withbe2theseÂvalues,motorisoneofthereasonswhytheelectrostatic105J/m3Paschen'sLaw.advantageisadaptiveingtoofmicro-electrostaticasamicro-motor,motorisalthoughitssuperiorthemainmotor)Betweenasiliconfabricationprocesses.

match-motor),andtheascaleofcentimeter-size(electromagneticelectricthemotorsthereisfewaredemandhundredformicrometer-sizepowerfulmotors(electrostaticandpiezo-propertiesfabricationofpiezoelectricprocesspromisingcandidates.andmaterialspresentingmotorBeforedescribingarebrie¯yexamples,theleadAtacceptorzirconatepresent,thetitanate,http://www.77cn.com.cnedWithpiezoelectricexplained.additivesmaterialisPZT.

ions,PZTcanbemodi®edtosoft-typeofordopingorhard-typelargeSoft-typecoef®cient.stroke,piezoelectricTheinotherenergywordsmaterialdensityithasisisexpressedautilizedlargedtogenerateaas

piezoelectricUpiezo k233E33E0E

2

(1)

wherepermittivityEisanelectrical®eld(1:8compared:5Â103J/m(1700),3forPZT-5Ak5Â106V/m),E33the33the[14]couplingfactor.Thisvalueis(0.71),isappliedEnergyfortodensityresonance-typeanelectromagneticforthistypeactuatorsvalue.notaslargeis

likeHard-typeultrasonicmotors.PZTisUpiezo Q2k233E33E0E

2

(2)

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