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文献翻译英文原文：NOVELMETHODOFREALIZINGTHEOPTIMALTRANSMISSIONOFTHECRANK-AND-ROCKERMECHANISMDESIGNAbstract:Anovelmethodofrealizingtheoptimaltransmissionofthecrank-and-rockermechanismispresented.Theoptimalcombinationdesignismadebyfindingtherelatedoptimaltransmissionparameters.Thediagramoftheoptimaltransmissionisdrawn.Inthediagram,therelationamongminimumtransmissionangle,thecoefficientoftravelspeedvariation,theoscillatingangleoftherockerandthelengthofthebarsisshown,concisely,convenientlyanddirectly.Themethodpossessesthemaincharacteristic.Thatitistoachievetheoptimaltransmissionparametersunderthetransmissionanglebydirectlychoosinginthediagram,accordingtothegivenrequirements.Thecharacteristicsofthemechanicaltransmissioncanbeimprovedtogaintheoptimaltransmissioneffectbythemethod.Especially,themethodissimpleandconvenientinpracticaluse.Keywords：Crank-and-rockermechanism,Optimaltransmissionangle,CoefficientoftravelspeedvariationINTRODUCTIONByconventionalmethodofthecrank-and-rockerdesign,itisverydifficulttorealizetheoptimalcombinationbetweenthevariousparametersforoptimaltransmission.Thefigure-tabledesignmethodintroducedinthispapercanhelpachievethisgoal.Withgivenconditions,wecan,byonlyconsultingthedesigningfiguresandtables,gettherelationsbetweeneveryparameterandanotherofthedesignedcrank-and-rockermechanism.Thustheoptimaltransmissioncanberealized.Theconcerneddesigningtheoryandmethod,aswellastherealcasesofitsapplicationwillbeintroducedlaterrespectively.1ESTABLISHMENTOFDIAGRAMFOROPTIMALTRANSMISSIONDESIGNItisalwaysoneofthemostimportantindexesthatdesignerspursuetoimprovetheefficiencyandpropertyofthetransmission.Thecrank-and-rockermechanismiswidelyusedinthemechanicaltransmission.Howtoimproveworkabilityandreduceunnecessarypowerlossesisdirectlyrelatedtothecoefficientoftravelspeedvariation,theoscillatingangleoftherockerandtheratioofthecrankandrocker.Thereasonablecombinationoftheseparameterstakesanimportanteffectontheefficiencyandpropertyofthemechanism,whichmainlyindicatesintheevaluationoftheminimumtransmissionangle.Theaimrealizingtheoptimaltransmissionofthemechanismishowtofindthemaximumoftheminimumtransmissionangle.Thedesignparametersarereasonablycombinedbythemethodoflesseningconstraintsgraduallyandoptimizingseparately.Consequently,thecompleteconstraintfieldrealizingtheoptimaltransmissionisestablished.Thefollowingstepsaretakenintheusualdesignmethod.Firstly,theinitialvaluesofthelengthofrocker3landtheoscillatingangleofrockeraregiven.ThenthevalueofthecoefficientoftravelspeedvariationKischoseninthepermittedrange.Meanwhile,thecoordinateofthefixedhingeofcrankApossiblyrealizediscalculatedcorrespondingtovalueK.1.1LengthofbarsofcrankandrockermechanismAsshowninFig.1,leftarcGC2isthepermittedfieldofpointA.ThecoordinatesofpointAarechosenbysmallstepfrompoint2CtopointG.ThecoordinatesofpointAare02hyycA(1)22AAyRx(2)where0h,thestep,isincreasedbysmallincrementwithinrange(0,H).Ifthesmallerthechosenstepis,thehigherthecomputationalprecisionwillbe.Ristheradiusofthedesigncircle.disthedistancefrom2CtoG.2cos)2cos(22cos33lRld(3)Calculatingthelengthofarc1ACand2AC,thelengthofthebarsofthemechanismcorrespondingtopointAisobtained[1,2].1.2MinimumtransmissionangleminMinimumtransmissionanglemin(seeFig.2)isdeterminedbytheequations[3]322142322min2)(cosllllll(4)322142322max2)(cosllllll(5)maxmin180(6)where1l——Lengthofcrank(mm)2l——Lengthofconnectingbar(mm)3l——Lengthofrocker(mm)4l——Lengthofmachineframe(mm)Firstly,wechooseminimumcomparingminwithmin.Andthenwerecordallvaluesofmingreaterthanorequalto40andchoosethemaximumofthem.Secondly,wefindthemaximumofmincorrespondingtoanyoscillatinganglewhichischosenbysmallstepinthepermittedrange(maximumofminisdifferentoscillatingangleandthecoefficientoftravelspeedvariationK).Finally,wechangethelengthofrocker3lbysmallstepsimilarly.Thuswemayobtainthemaximumofmincorrespondingtothedifferentlengthofbars,differentoscillatingangleandthecoefficientoftravelspeedvariationK.Fig.3isaccomplishedfromTableforthepurposeofdiagramdesign.Itisworthpointingoutthatwhateverthelengthofrocker3lisevaluated,thelocationthatthemaximumofminarisesisonlyrelatedtotheratioofthelengthofrockerandthelengthofmachineframe3l/4l,whileindependentof3l.2DESIGNMETHOD2.1RealizingtheoptimaltransmissiondesigngiventhecoefficientoftravelspeedvariationandthemaximumoscillatingangleoftherockerThedesignprocedureisasfollows.(1)AccordingtogivenKand,takenaccounttotheformulatheextremeincludedangleisfound.Thecorrespondingratioofthelengthofbars3l/4lisobtainedconsultingFig.3.18011KK(7)(2)Choosethelengthofrocker3laccordingtotheworkrequirement,thelengthofthemachineframeisobtainedfromtheratio3l/4l.(3)ChoosethecentreoffixedhingeDasthevertexarbitrarily,andplotanisoscelestriangle,thesideofwhichisequaltothelengthofrocker3l(seeFig.4),and21DCC.Thenplot212CCMC,drawNC1,andmakeangle9012NCC.ThusthepointofintersectionofMC2andNC1isgained.Finally,drawthecircumcircleoftriangle21CPC.(4)PlotanarcwithpointDasthecentreofthecircle,4lastheradius.Thearcintersec