/EngineeringScienceEngineers,PartC:JournalofMechanicalProceedingsoftheInstitutionofMechanical/content/219/7/687Theonlineversionofthisarticlecanbefoundat:DOI:10.1243/095440605X315086872005219:ProceedingsoftheInstitutionofMechanicalEngineers,PartC:JournalofMechanicalEngineeringScienceHaoWang,CeZhangandGuanlongChenKHVIndexingCamMechanism:ANewIntermittentMechanismPublishedby:Onbehalfof:InstitutionofMechanicalEngineerscanbefoundat:ScienceProceedingsoftheInstitutionofMechanicalEngineers,PartC:JournalofMechanicalEngineeringAdditionalservicesandinformationfor/cgi/alertsEmailAlerts:/subscriptionsSubscriptions:/journalsReprints.navReprints:/journalsPermissions.navPermissions:/content/219/7/687.refs.htmlCitations:WhatisThis?-Jul1,2005VersionofRecordatZHEJIANGUNIVERSITYonJanuary5,2013DownloadedfromKHVindexingcammechanism:anewintermittentmechanismHaoWang1C3,CeZhang2,andGuanlongChen11SchoolofMechanicalEngineering,ShanghaiJiaoTongUniversity,Shanghai,PeoplesRepublicofChina2SchoolofMechanicalEngineering,TianjinUniversity,Tianjin,PeoplesRepublicofChinaThemanuscriptwasreceivedon13September2004andwasacceptedafterrevisionforpublicationon5April2005.DOI:10.1243/095440605X31508Abstract:TheKHVindexingcammechanismisanewtypeintermittentmechanismthathasastructuresimilartotheKHVplanetarygeartransmission(onetypeoftheplanetarydrivewithsmallteethdifference,whereKindicatesthesungear,Hindicatesthepivotedarm,andVindicatestheoutputmechanism).Thispaperfocusesonthegenerationofapitchcurveandacamprofileinsuchanewmechanism.ThreetypesoftheKHVindexingcammechanismarecomparedanddiscussed,andtheequationsofcamspitchcurvesarederived.ThecamsprofileisgeneratedbyBooleanoperationsontheoffsetsofthecamspitchcurve.Afterthis,thecuspsonthecamprofileareeliminatedandreplacedbyaparticularHermitecurve.Theanimationsofallthreetypesareillustrated,andaprototypeofsuchmechanismisreported.Keywords:intermittentmechanism,indexingcammechanism,planetarytransmission1INTRODUCTIONIndexingcammechanismsarewidelyusedintheindustry.Threetypesofsuchmechanisms,theparal-lelindexingcammechanism,theFergusonindexingcammechanism,andthebarrelindexingcammechanism,arethetraditionaltypeswellknowntoday18.Inrecentyears,somenewtypesofindexingcammechanismshavealsobeenreported,e.g.thesynthesisofthesphericalindexingcammechanismwithdirectcontactbetweencamandfollowerwasreportedbyGonzalez-PalaciosandAngeles9.Theyextendedthisconcepttothesphericalindexingcammechanismincludingrollers10.Gonzalez-PalaciosandAngeles11alsopro-posedaunifiedapproachaimingatthesynthesisofindexingcammechanismswithdirectcontacttransmission.AnewtypeofparallelindexingcammechanismwithaninternalcamwasreportedbyNishiokaandNishimura12.Zhang13,14createdanewconceptofindexingcammechanismstheplanetaryindexingcammechanismandpresentedtwotypesofit.Inthispaper,theconceptisextendedtotheKHVindexingcammechanism,whichisanintermittentmechanismthathasalayoutofKHVplanetarygeartransmission.Thenewmechanismissuitablefortheworkingconditionswherealargenumberofstopsareneeded.Asmostoftherollerscanbeengagedwiththecaminthemechanism,ahigherstrengthandmorecompactdesigncanbeobtained.Thisnewmechanismcouldexpandtheapplicablerangesoftheindexingdriverstowiderindustryapplications.Thispaperfocusesonthegenerationofthepitchcurveandtheprofileofthecaminsuchamechan-ism.Thestructureofthispaperisasfollows.First,section2,discussesthreetypesoftheKHVindexingcammechanism,namely,typeI,typeII,andtheretrogressedmechanism；thenthegenerationofthecamspitchcurveandcamprofileareexplainedandtheanimationofthemechanism(typeIandtypeII)isillustratedinsections3,4,and5,respectively,afterabriefintroductionoftheretrogressedmechanisminsection6.Finallyaprototypeofthemechanismispresentedinsection7.C3Correspondingauthor:Auto-bodyManufacturingTechnologyCentre,SchoolofMechanicalEngineering,ShanghaiJiaoTongUniversity,Shanghai200030,PeoplesRepublicofChina.687C16204#IMechE2005Proc.IMechEVol.219PartC:J.MechanicalEngineeringScienceatZHEJIANGUNIVERSITYonJanuary5,2013Downloadedfrom2STRUCTUREOFTHEDEVICEThestructureofaKHVindexingcammechanismissimilartoacycloidspeedreducer,whoseschemeisdepictedinFig.1.Acycloidspeedreduceriscom-posedofanepitrochoidplanetgearg,aninputshaftH(pivotedarm)withaneccentricity,andanumberofrollersfixedinsungearb.ForpurerotationalmotionoftheoutputshaftV,theeccentricwobbleoftheplanetgeargisfilteredoutbydeviceW,whichisaparallelogrammechanism.AsthelayoutofaKHVindexingcammechanismissimilartothecycloidspeedreducer,Fig.1isalsousedastheschemeofthenewmechanism.Insuchamechanism,thepairofplanetgearsgandtheroll-ersinsungearbarereplacedbyacamrollerpairtoimplementtheintermittentmotion.Inthemotionprocess,theinputshaftHrotatesataconstantspeed,whiletherotationoftheplanetgeargisintermittent.TherotationalmotionoftheplanetgeargisalsofilteredoutbydeviceWtooutputshaftV.TheKHVindexingcammechanismcanbedesignedastwodifferenttypesaccordingtothelayoutofthecamrollerspair,namely,typeI,inwhichplanetgeargisacamandtherollersarefixedinsungearb,andtypeII,inwhichtherollersarefixedintheplanetgeargandthesungearbisaninternalcam.Whentheoutputshaftisthesungearb,andVisfixed,themechanismisnolongeraplanetarymechanism,butanordinarygeartrainretrogressedfromtheplanetarymechanism(Fig.2).Becausesucharetrogressedmechanismcouldalsofulfillthetaskofanintermittentmotion,itiscatalo-guedastheretrogressedtypeoftheKHVindexingmechanism.ResearchworkhasbeenreportedearlierontypeIIofthemechanismbyZhang13.Inthispaper,attentionisfocusedonthesynthesisofallthreetypes.3PITCHCURVEOFTHECAM3.1EquationofthepitchcurveOnthebasisofthelayoutofthemechanismmentionedearlierandtherelativemotionofitscom-ponents,thecoordinatesystemandtheparametersintypeIareconstructedasinFig.3.Considerthreebodies:g,playingtheroleoftheplanetcam,bbeingthesungearwithrollers,andHbeingtheinputshaftwithaneccentricity.ObandOgdenotethecentreofsungearbandplanetcamg,respect-ively.ThefixedcoordinatesystemObXbYbisrigidlyfixedonthesungearb,andtheinputshaftHrotatesaroundthepointObwithaconstantangularvelocity.ArelativecoordinatesystemOgXgYgrigidlycon-nectedtotheplanetcamgisalsosetup,andOgalsorepresentstherotationalcentreoftheplanetcamg.Weassumethaterepresentstheeccentricityintheinputshaft,andtheradiusofthesungearb(thedistancesbetweenObandthecentreofrollersMi)isRz.Thenumberofrollersinthesungearbisz.TheangulardisplacementoftheinputshaftHisuH,andthatoftheplanetcamgisug.LetMi(i1,.,z)representthecentreoftherollers,respectively.Threepositionvectors,Rzi,H,andRTi,arealsoshowninFig.3,whereRziisfixedonthesungearbandorientedtowardsthecentreoftherollerMiwiththeoriginOb,HisfixedontheinputshaftandorientedtowardsthecentreoftheplanetcamOgwiththeoriginObalso,andRTirepresentsthepositionofthecampitchcurvewiththeoriginOg.Fig.1SchemeofaKHVindexingcammechanism(typeIandtypeII)Fig.2SchemeofaKHVindexingcammechanism(theretrogressedmechanism)Fig.3CoordinatesystemoftypeI688HaoWang,CeZhang,andGuanlongChenProc.IMechEVol.219PartC:J.MechanicalEngineeringScienceC16204#IMechE2005atZHEJIANGUNIVERSITYonJanuary5,2013DownloadedfromTheirrelationshipyieldsRTi(t)RziHRzej(aiC0ug(t)C0eej(uH(t)C0ug(t)t0,TC138,i1,2,.,z(1)FortypeII,thecoordinatesystemandthepar-ametersareasconstructedinFig.4.Insuchtype,gplaystheroleoftheplanetrollergear,bisaninternalcam,andHistheinputshaftwithaneccentricity.ObandOgdenotethecentreofsungearbandrollergearg,respectively.ThefixedcoordinatesystemObXbYbisalsorigidlyconnectedtotheinternalcamb,andtheinputshaftHrotatesaboutthepointObwithaconstantangularvelocity.ThemovingcoordinatesystemOgXgYgisrigidlycon-nectedtotherollergearg,andOgistherotationcentreoftherollergearg.Also,erepresentstheeccentricity,andtheradiusoftherollergeargisRz.Thenumberofrollersinthesungearbisz.TheangulardisplacementoftheinputshaftHisuH,andthatoftheplanetcamgisug.LetMi(i1,.,z)representthecentreoftherollers,respectively.Threepositionvectors,Rzi,H,andRTi,arealsousedhereandhavethesamedenotionaswithtypeI.IntypeII,theyyieldadifferentrelationshipasRTi(t)HRzieejuH(t)Rzej(aiug(t)t0,TC138,i1,2,.,z(2)3.2RelationsbetweentheinputandtheoutputofthemechanismFromequations(1)and(2),itisseenthatthepitchcurveofeithertypeiscomposedofseveralcurvesthataredeterminedbyeveryequationinthesetcorrespondingly.Everycurvehastobeconnectedtoeachothertomakesurethatthepitchcurveofthecami