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Development

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DevelopmentDevelo

    Development

    1552Xiangetal/JZhejiangUnivSciA20089(11):1552-1559 ;JournalofZhejiangUniversitySCIENCEA

    ;ISSN1673-565X(Print);ISSN18621775(Online)

    ;wwwzjueducn~zus;wwwspringerlinkcom

    ;Email:jZUS@zjueducn

    ;Developmentofan-typeactuatorforenhancing

    ;high--speedelectro--pneumaticejectorvalveperformance ;ZhongXIANG

    ;,

    ;HaoLIU

    ;,

    ;Guo.LiangTAO,JunMAN,WeiZHONG

    ;(StateKeyLaborato~ofFluidPowerTransmissionandControl,ZhejiangUniversity,Han

    gzhou310027,China)

    ;E-mail:zju_xiang@hotmailcorn;hliu2000@zju.edu.cn ;ReceivedMay6,2008;revisionacceptedAug.25,2008

    ;Abstract:Anovele-typesolenoidactuatorisproposedtoimprovethedynamicresponseofe

    lectropneumaticejectorvalvesby

    ;reducingmovingmassweight.Afiniteelementanalysis(FEA)modelhasbeendevelopedt

    odescribethestaticanddynamic

    ;operationsofthevalves.ComparedwithaconventionalEtypeactuator,theproposed8-typeactuatorreducedthemovingmass

    ;weightbyalmost65%withoutsignificantlossofsolenoidforce,andreducedtheresponseti

    me(RT)typicallyby20%.Prototype

    ;valvesweredesignedandfabricatedbasedontheproposedg-typeactuatormode1.Anexpe

    rimentalsetupwasalsoestablishedto

    ;investigatethedynamiccharacteristicsofvalves.Theexperimentalresultsofthedynamics

    ofvalvesagreedwellwithsimulations,

    ;indicatingthevalidityoftheFEAmode1.

    ;Keywords:,一

    typeactuator,Highspeedelectropneumaticejectorvalve,Finiteelementmethod,Dynamicsimulationandcx

    ;periment

    ;doi:10.1631/jzus.A0820350Documentcode:ACLCnumber:TM15;TH138 ;INTR0DUCTION

    ;Withadvantagesoflowcost.antipollution

    ;ability,highflowrategain,smallsizeandsimple

    ;structure(Topqueta1.,2006;Khaneta1.,2007),

    ;high..speedelectro..pneumaticejectorvalveshave

    ;attractedconsiderableattentioninseveralareasof ;modemindustry.Theyhavebeenusedinsorting ;parts,flappingcontrolsystemsandothersystemsfor ;gluing,dosingandpackagingwherediscretecyclic, ;linearorrotatingmotionsandaverylonglifetimeare

    pneumatic ;required.Thesemodemhigh-speedelectro

    ;valveapplicationsneedfurtherimprovementsin-

     ;cludinghigheroperatingspeed,improvedrepro

    ;ducibilityoftheopeningandclosingphase,and ;weight,volumeandcostreduction(Ertleta1.,2003). ;Therehavebeenmanydevelopmentsinfast

    ;responseactuatorsoverthepasttwodecades.First, ;Correspondingauthor

    ;ProjectsupposedbytheDoctoralFundofMinistryofEducationof ;China(No.20070335133)andtheEducationalCommissionof ;Zh@angProvinceNo.20070057),China

    ;Seillyr1979;19811studiedtwokindsofsolenoid ;actuators,calledHelenoidandColenoid.Further ;researchthenfollowed.aimedatimprovingthedy

    ;namicresponseofactuatorsbydevelopingnewkind ;ofsolenoidsorireprovingtheoldones.Schechter ;fl982)developedakindoffastresponsemultipole ;solenoidactuatorwitha2.msresponsetimefRT1. ;Kushidar1985)developedadisktypesolenoidac

    ;tuator(calledDISOLE)withanRToflessthan1ms. ;Recently,piezOtranslatorshavealsobeendeveloped ;foruseasactuatorsofejectors.ZhaoandJones(1991) ;developedafastresponseelectropneumaticpower

    ;converterbycombiningastackedDiezotranslator ;flapperasadrivestageandabackpressurestagefor ;generatingtheoutput.Lee(1999)designedfastac

    ;tuatorsusingmultilayerstackedalkalihalideelec

    ;trostrictivematerialsforfuelinjection.Although ;theseproposedactuatorshavefairlygoodperforlTl

    ;ancestheyarenotpopularinthedesignof

    ;high..speedelectro..pneumaticejectorvalvesbecause ;oftheirlargesize,highcostorcomplexstructure. ;Theyarenotwel1suitedtosomeofthecharacteris

    ;Xiangetal/JZhejiangUnivSciA20089(11):1552-1559 ;ticsinherentinhigh-?speedelectro--pneumaticejector ;valves,includingsmallstrokelength(O.05-0.10inin) ;andlowworkingpressure(1essthan1.O×10.Pa). ;Neitheraretheywellsuitedtotheneedsofindustrial ;applicationsincludingsmallsize,lowcost,large

    ;forceproduction,lackofoperationmaintenance ;undercontinuousdutycyclesat150-300Hzand ;multibillioncycleoperation(inexcessoffivebillion ;cycles)(Khaneta1.,2007).

    ;Onthecontrary,classicalC-typeandE-type ;actuatorsarestillfavoredforuseasejectorvalve ;actuatorsbecauseoftheirsimplicityandhighholding ;forcecapability.Forexample,Fig.1showsasche

    ;maticcrosssectionthroughatypicalactuatorthathas ;beenusedinanejectorvalve.Thesymbols(e…g,

    ;n)usedinFig.1andFig.2(seeinnextsection)for ;dimensionalparametersnormallyconsistofaprefix ;character.,f0rlengthanddfordiameter.andasub

    ;scripttodifferentiatefromeachother.Itisobvious ;thattheactuatorshowedinFig.1isessentiallyan ;E.tVpeactuatorthatconsistsofanexcitationcoil ;woundaroundamagneticEcorestatorandadisk

    ;steelarmature(movingmass).Thearmaturewil1be ;caughtorreleasedbyenergizingordeenergizingthe

    ;woundcoil.Thesolenoidforceproducedbytheac

    ;tIlatorisneededtoovercomethereactionforceto ;whichthearmatureissubjectedasaresultof ;highpressureairflowingthroughthevalve.As ;provedbySchechter(1982)andSeilly(1979;1981), ;withanE-type(orCtype)actuator,thelargerthe

    ;solenoidforcerequired.the1owertheaccelerationof ;thearmature(movingmass).Thispresentsasub

    ;stantialchallengetoobtainingfurtherimprovementin ;thevalvedynamicswithinitscompactpackaging ;size.

    ;MagneticEcoreCoilArmature

    ;Fig.1Definitionsofdimensionalparametersforacon- ;ventionalE.corestatoranddiskarmature

    ;1553

    ;ThisPaDerdescribesthedevelopmentofan

    ;e-typeactuator(incrosssection,theshapeofthe ;actuatorlooksIikethecharacter1tobalancethe

    ;increasedsolenoidforceandthedecreasedarmature ;accelerationinherentinE.typeactuatorstoenhance ;theperformanceofelectropneumaticejectorvalves.

    ;Thefiniteelementanalysis(FEA)methodisusedto ;modelandsimulatetheactuatorandthefabricated ;ejectorvalve.Steadystateanddynamicresponse ;characteristicsofE.typeande-typeactuatorsare

    ;thoroughlycompared.Finally,simulateddynamic ;displacementandcurrentresultsoftheactuatorare ;contrastedwiththeexperimentalresults.respectively ;Asanexampleofapplication,thenewlydeveloped ;high-speedpneumaticejectorvalvesareusedinthe ;ejectionsystemsofhigh?speedopticalfoodsorting ;machines.

    ;FINITELEMENTANALYSISMODELLING

    ;Descriptionofthe,一typeactuatoranddesignof

    ;theprototypevalve

    ;Fig.2aillustratestheschematicstructureofthe ;proposede-typeactuator.ComparedwiththeE-type ;actuator(Fig.11.a’coreshoulder’isintroducedinto

    ;the,一typeactuatorstructure.Thestructuraldimen

    ;sionsofbothactuatorsarealmostthesamewhilethe ;armature(movingmass)weightofthee-typeactua- ;torisreducedconsiderably.Asprovedbelow.the ;solenoidforceproducedbyane-typeactuatoris ;almostthesameasthatproducedbyanE..typeac.. ;tuator.butthedynamicresponseperformanceofthe ;e-typeactuatorismuchimproved.

    ;Fig.2bshowsaschematiccrosssectionofthe ;fabricatedprototypevalve.Thevalvecanbedivided ;intothreemajorbodies(bodiesI.II.III).BodyI ;consistsofamagnetic.core.awoundcoilanda

    ;plasticring,andprovidesanairinletport.Awire ;tunnelisalsodrilledinit.BodyIIhasacircular ;chamberinthecentertohousethearmature.The ;diameterofthechamberisdesignedtobeslightly ;biggerthanthatofthearmaturetoensurethatthe ;armaturecanmovefreely.Foursemicircularslotsare ;distributedevenlyalongtheinnercircumferenceof ;bodyIItoimprovetheflowrateofthevalve.Body ;IIIprovidesanairoutletport.shownindetailin ;Fig.2c(topview).Thecoi1consistsof150turnsof ;1554Xiangotal/dZhejiangUnivSciA20089(11):15521559

    ;isolatedcopperwirewitharesistanceof3.2Q.ItiS ;directlywoundonthemagneticcoretoimprovethe ;heat.sinkingcapacityofthevalve.A1lthreebodies ;aremadeofhardaluminumandareioinedtogether ;withfourhexagonalsocketcountersunkheadscrews. ;ThevalveiSsealedwithOringsorrubbersheet.

    ;Contactfaces.suchasthelowerfaceofthearmature ;MagneticE-coreCoilCoreshoulderArmature

    ;(a) ;

    ;l_f}.\lI

    ;\

    ;,

    ;××\,,,,,,

    -?二 ;U-1

    ;l,Il\

    ;__j-, ;\

    ;t

    ;()

    ;(c) ;.

    ;(a) ;,(b)

    ;()

    ;,

    ;.i

    ;.1

    ;.il ;1i. ;11

    ;.1ll

    ;1.1 ;.1l ;??

    ;l

    ;bOthtV’. ;

    ;-

    ;()

    ;() ;(Q) ;()

    ;(N’)

    ;()

    ;8.I2 ;×6

    ;3.2 ;.10 ;1.8×1O

    ;1.× ;Xiangeta1./JZhejiangUnivSciA20089(11):1552-1559

;Magneticfields~ength(xl0A/m)

    ;Fig.3InitialmagnetizationcurveforEtypeand-type

    ;actuators

    ;simulatebothactuators(Figs.1and21.Assumingthat ;thematerialusedfortheactuatorisisotropicandits ;hysteresiscanbeneglected,electromagneticfields ;aregovernedby.Maxwellequations(Eqs.(1)(4))

    ;withdisplacementcurrentsignored(quasistationary ;limit)whiletheconstitutiveequationisexpressedas ;Eq.(5)(Nannapaneni,2004):

    ;×H(r,,)=J(r,,),

    ;V?B(r,)=0,

    ;v×(r,f):OB

    ;_

    ;(r,t)

    ;,

    ;r

    ;.

    ;E():,

    ;=vB.J=E.

    ;(1)

    ;(2)

    ;(3)

    ;(4)

    ;(5)

    ;whereisthemagneticfieldintensity,istheradial ;coordinateinthecylindricalcoordinatesystem.Bis ;themagneticfluxdensity.Jisthecurrentdensity,E ;istheelectric.fieldintensity.Pisthevolumetric ;chargedensity,40istheelectricpermittivityoffree ;space.1,isthematerialreluctivity,andoistheelec

    ;tricalconductivity.

    ;ByintroducingmagneticvectorpotentialAand ;electricalscalarpotential,andcombiningwith ;CoulombgaugeconditionandDirichletboundary ;condition.Maxwellequationscanbeexpressedas ;(PawlakandNehl,1988;Khaneta1.,2007): ;B=VxA,(6)

    ;V?

    ;(8tVI/..

    ;×(vVxA)=l,0.4+dfi×(×)

    ;,(8)

    ;fdf

    ;1555

;whereisthearmaturedisplacement.

    ;Inthetransientcasewithmotionanadditional ;circuitequationshouldbesimultaneouslysolved ;withthepartialdifierentia1equationofthemagnetic ;field.Thefollowingvoltageequationisusedto ;coupletheelectricandmagneticmodels:

    +dd0L(6,I), ;)=/R+

    ;whereU,j,R,Laretheexternalenergizingvoltage, ;coilcurrent.coilresistanceandwoundcoilreluc

    ;tance,respectively.

    ;ThetotalsolenoidforceFmagproducedbythe ;actuatorcanbederivedbyintegratingtheMaxwell ;stresstensorToverthesurfaceSsurroundingthe ;armatureasEq.r101:

    ;Fm=TndS(10)

    ;Mechanicalsub-model

    ;Takingsolenoidforce,movingmass,viscous ;dampingandpressureforceintoaccountandapply

    ;ingNewton’s2ndlaw,thegoverningequationforthe

    ;armaturecanbeexpressedas

    ;Fmag=m

    ;(+g

    ;m:PmV,(12)

    ;wheregisthegravity,bistheviscousdampingco- ;efficientoftheair,isthepressureforceactingon ;thearmature,andm,PmandVarethemass,material ;densityandvolumeofthearmature,respectively. ;ReferringtoFig.2bandFig.2c,Eq.(13)canbe ;usedtoestimatethestaticpressureforce,Fsp,acting ;onthearmaturewhenitisreleasedbythemagnetic ;core(closedstate):

    ;()()?()(一只),(13)

    ;wherePsandPaarethepressuresatthevalveinlet ;andoutletports,respectively.

    ;Theflowstatusatthetimewhenthearmatureis ;caughtwiththemagneticcore(Fig.4)takesintoac

    ;countthattherearegroovesinthelowersurfaceofthe ;(_)IlI10II

    ;1556Xiangeta1./JZhejiangUnivSciA20089(11):1552-1559 ;magneticflameandthattheheightofthemagnetic ;coreisalittleleSSthanthatoftheflame.Following ;KaridisandTumsfl982).weassumedthateven ;whenthevalvewasfullyopened.therewasstil1some ;clearance(about0.0l-0.02ram)betweentheupper

;faceofthearmatureandthelowerfaceofthemag

    ;neticcoreshoulder.Owingtothefactthattheclear

    ;ancehasthesamemagnitudeasthesmal1airgap ;lengthf0.050.10mm),itcanbeassumedthatthe

    ;flowstatusduringthearmaturemovementfmoving ;state)wasthesameasthatwhenthearmaturewas ;caughtbythemagneticcore(openedstate).Therefore, ;thegoverningequationforstaticpressureforceacting ;onthearmatureattheopenedstatehasthesameex. ;pressionasthatusedforthedynamicpressureforce ;actingonthearmature.Thispressureforcecanbe ;obtainedfromtheNavier.Stokesequationsas ;(

    ;41n(1+d4/41(一只)

    ;ut

    ;Fig.4Flowstatuswhenvalveisfullyopened ;SIMULATIONANDEXPERlMENTALANALY.

    ;SIS

    ;Staticsimulationandcomparison

    ;Forthesteadystateforceconstantcurrentwas

    ;adoptedtoexcitethecoil.Thesimulatedstatic ;force..displacementandarmatureacceleration.. ;displacementcharacteristicsofthetwoactuatorsare ;plottedjnFig.5aslinesofconstantmagnetomotive ;force(MMF)valuesupto1000A(magneticsatura. ;tion).Theaccelerationswereobtainedbydividing ;thesimulatedsolenoidforcesbyarmatureweight. ;Whentheairgaplengthissmall,thesteady ;staticsolenoidforcesproducedbythe,一typeactuator

    ;l0O

    ;80

    ;40

    ;2O

    ;O

    ;0O.040.080.120.16

    ;Displacement(xl0m,

    ;(a)

    ;Displacement(xl0m,

    ;(b)

    ;Fig.5Simulatedforcedisplacement(a)andaccelera

    ;tion-displacement(b)characteristicsforthe,一type

    ;(solidlines)andE-type(dashedlines)actuatorsde- ;scribedinTable1

    ;arelargerthanthoseproducedbytheE.typeactuator

    ;(Fig.5a).However,astheairgaplengthincreases, ;thesteadystaticsolenoidforcesproducedbythe ;E-typeactuatortendtobelower.Actuatorsforejector ;valvestypicallyoperateatsaturationconditionsand ;theirstrokelengthsareleSSthan0.1mmfKhaneta1..

     ;2007).Thesteadystaticsolenoidforcesofbothac

    ;tuatorsarealmostthesameinthesesituations ;(Fig.5a).BecausethearmatureweightiSconsidera. ;blyreducedbytheE-typeactuator(by65%here),the ;steadystatearmatureaccelerationoftheE-typeac. ;tuatorisobviouslylargerthanthatoftheE.type ;actuator.Forexample,whentheairgaphasatypical ;lengthof0.08mmandunderanexcitationof1000A. ;thesolenoidforceandarmatureaccelerationpro. ;ducedbytheE-typeactuatorare66Nand5.8×l0 ;m/s’comparedwiththoseof70Nand2.2×l0m/s.

    ;producedbytheE-typeactuator,respectively.This ;featureoftheE-typeactuatorwillenableittorespond ;fasterthantheEtypeactuator.

    ;Z0uoJp10c010?一?\g0×=00I.00

    ;Xiangeta1./JZhejiangUnivSciA20089(11):1552-1559 ;Experimentalsetup

    ;Astheactuatorstrokelengthistypicallyinthe ;rangeOf0.050.10rnlT1.itisdifficultandexpensive ;toestablishanexperimentalsetuptoaccuratelyob. ;taintheactuatorforcedisplacementcharacteristics. ;Therefore,onlyadynamicmeasurementsetupwas ;manufacturedtovalidatetheFEAmode1.Fig.6a ;showstheexperimentalsetupusedtodetectthe ;prototypevalvedynamics.Alasersensorplacedatits ;referencedistancerl50ram)isusedtodetectthe ;displacementofthearmature.Theholeinthebottom ;faceofbodyIIIistumed1argeenoughtoensurethat ;the1aseremittingfromthesensorcanpassthroughit ;andthroughtheventilatedholefreely.Differentwork ;conditionscanbeeasilyrealizedbyadjustingthe ;regulatorandtheadjustablepowersupply.Toavoid ;overheatingthecoil,asophisticatedenergizing ;method(Seilly,1979),integratedintheamplifier ;circuit(Fig.6b),isadoptedtocontroltheprototype ;valve.Anadiustableparameter10kHzpulsewidth

    ;modulation(PWM)signalgeneratedbvNI/PCI625l

    ;multifunctionalacquisitioncardisusedtoswitchthe ;powerelectronics.

;+

    ;

    ;?

    ;?

    ;0

    ;

    ;(a)

    ;Fig.6Experimentalsetup(a)anddrivingcircuit(b) ;forprototypevalvedynamics

    ;Dynamicsimulationandexperiment

    ;Thedynamiccharacteristicsofthe8-typeac

    ;tuatorandtheEtypeactuatorwerecomparedwith

    ;simulationresults.Foreaseofcomparison,constant ;1557

    ;excitingvoltageisappliedtothecoildirectlywith

    ;outanycontrolstrategytomakesurethatthear. ;maturecanbecaughtbythemagneticcore.Initial ;conditionssuchaspreloadforce,dampingcoeffi

    ;cient,etc.,werealIsettobethesameforeachac. ;tuator.Theclearancebetweenthecontactedfaceof ;thearmatureandthemagneticcorewasexperi

    ;mentallysetto0.015mm.

    ;Fig.7showstypicalsimulatedsetsofdis. ;placementcurvesforan8-typeactuator(solidlines) ;andaconventionalE.typeactuator(dashedlines).In ;particular.Fig.7acomparestheeffectofairgap ;lengthontheactuatormovementwhenunifoHnex. ;citingvoltage(24V)andpreloadforce(13N)are ;appliedtobothactuators.Itclearlyshowsthatthe ;proposed8-typeactuatorrespondsfastertotheex- ;citingsignalthantheEtypeactuator.Quantitatively, ;RTsofthe8-typeactuatoratairgaplengthsof0.05 ;mm,0.08mmand0.1mmaredecreasedbv22%, ;l2%and11%.respectively.Fig.7bcomparesthe ;effectofextemalexcitingvoltageontheactuator ;movementwhenthesamepreloadforceisappliedto ;bothactuators.RTsofthe8-typeactuatorunderex

    ;citingvoltagesof24V.18Vandl2VatO.05mmair ;gaplengtharedecreasedby19%,18%and19%, ;respectively.Fig.7ccomparestheeffectofpreload ;?

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