已阅读5页,还剩1页未读, 继续免费阅读
版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
宁波大红鹰学院毕业设计(论文)外文翻译所在学院:机电学院班级:姓名:学号:指导教师:合作导师:2012年12月16日原文:题目CamprofileoptimizationforanewcamdriveAbstractAcomplexcamshapeoptimizationproblemisstudiedtooptimizeauniquecammechanismforanewcamdriveengine.First,theoptimizationproblemisdefinedthroughanalyzingtheuniquecammechanism.Multipledesignspecificationsareincludedintheoptimizationproblembydefiningtheoutputtorqueoftheengineastheobjectivefunctionandthecontactstress,radiusofcurvature,andpressureangleastheconstraints.Second,ananalyticalscenarioisdesignedtofindthebestevercamprofilesthroughmanipulatingthedifferentcombinationsofcamprofilerepresentationsandoptimizationmethods.Twotypesofcurverepresentations,includinggeneralpolynomialsplineandB-spline,areemployedincamprofilesynthesis.Inaddition,bothaclassicaloptimizationtechniqueandageneticalgorithm(GA)basedmethodareappliedtosolvethecomplexoptimizationproblem.Finally,comparativestudiesareperformedamongtheinitialprofileandtheoptimalprofilestodemonstratetheeffectivenessoftheseproposeddesignapproachesonsolvingthecamprofileoptimizationproblem.ResultsshowthatthebestprofilesareobtainedfromacombinationoftheB-splinerepresentationandtheGA-basedmethod.Inaddition,comparedtotheinitialdesign,theengineperformanceisimprovedgreatlybytheproposedoptimizationapproaches.Platecammechanismisawidelyusedmachinecomponentwiththecontinuouscontactmotionofcamandfollower,andcaneasilyproduceanyfunctionalmotionoffollowerduetotherotationofcam.Cammechanismhasthediversetypesbythecombinationofdifferentshapeofcamandmotionoffollower;plateorcylindricalcam,rollerorflat-facedfollower,andreciprocatingoroscillatingmotion.Inspiteoftheadvantagesofafewnumberoflinks,simplestructure,positivemotion,andcompactsize,cammechanismsrequiretheaccurateshapedesignandprecisemachiningproceduresforsatisfyingthemechanicalrequirements.Underthelowleveleddesignandmanufacturing,cammechanismsgivetheheavyeffectsonvibration,noise,separation,andoverloadingtoanoverallsystem.Toavoidtheseeffects,cammechanismmustbewelldesignedaccuratelyandmachinedprecisely.Actually,ahybridCAD/CAMapproachmaybethebestsolutionthattheshapedatafromthedesignprocessaredirectlycombinedtothemachiningdataforthemanufacturingprocessAsaninnovationofreplacingtheconventionalcrankshaft/connectingrodmechanismbycammechanisminenginedesign,anewtypeofenginecalledthecamdriveengineisbeingdevelopedinafewplacesintheworld.Thecamdriveenginehasuniquefeaturesovertheconventionalengines,amongwhichthecamdriveisthemostprominentone.Forcamdrive,thecamprofilescontroltheengineoperationstrokesbydeterminingthetimingofvariousintakeandexhaustevents.Moreover,theuseofcamdrivefacilitateshavingaseparatecompressionratioandexpansionratio,aseparationthatismuchmoredifficulttoaccomplishwiththeprevalentcrankshaft/connectingrodenginedesign.Thenewtypeofengineisbelievedtohavemajoradvantagesovertheconventionalengines,includinghigherpower,betterfueleconomy,smootheroperation,higherreliability,andlighterweight.Theapplicationofthecammechanismtocamdriveenginemakesthedesignofthecamprofilesessentialtotheoverallengineperformance.However,theinitialcamprofilesweredesignedusingatraditionalcamdesignapproach.Fortheso-calledtrialand-errorapproach,thecamprofilesarefirstgeneratedtomeetthegeometryspecificationssuchasthespecifiedvaluesofdisplacement,velocity,andaccelerationatdifferentengineevents,andthenthefeasibilityofthegeneratedcamprofilesischeckedtomeettheotherdesignspecifications,includingtheoutputtorqueoftheengine,radiusofcurvature,andpressureangle,etc.Althoughthisapproachissimpleinprinciple,itsdisadvantagesareobvious.First,thisap-proachisnotefficient.Ithastobeappliedmanytimesinordertoachieveasatisfactoryengineperformance.Therefore,itresultsinalaboriousandtimeconsumingdesignprocess.Moreover,sincethecamdesignprobleminvolvesthedeterminationoftheprofilesofbothintakecamandexhaustcam,theinterplaysofthetwoprofilesaddmorecomplexitytothetrial-and-errorapproach.Finally,althoughtheresultfoundbythisapproachisfeasible,itisveryunlikelytobeoptimal.Therefore,itisnecessarytouseanoptimaldesignapproach,inconjunctionwithanappropriatecamprofilerepresentation,todeterminethemostsuitablecamprofilesofbothintakecamandexhaustcaminordertomeetthemultipledesignspecifications.Thisisthemotivationoftheproposedresearch.Tothisend,wefirstreviewthepreviousresearchoncamdesignandoptimizationasfollows.Thecamdesignhaschangeddramaticallyoverthepastdecadesbytakingadvantageofthetremendousadvanceincomputingdevicesandmathematicstools,especiallythesplines.Theimpetusforthechangeisthedemandforcamswithhigherspeeds,smootheroperation,andbetterperformance.Theresearchactivitiesoncamdesigncanbeclassifiedintotwocategoriesaccordingtothecurverepresentationofcamprofile:polynomial-basedmethodsandspline-basedmethods.Inthereviewofthepaststudiesoncamdesignandoptimization,weaddressthefollowingthreeaspectsinthisresearch.First,themultipledesignspecificationsforthecamdriveengineareconsideredintheoptimizationproblem.Weselecttheoutputtorqueataspecifiedenginespeedastheobjectivefunction.Inaddition,theotherimportantdesignspecifications,includingcontactstress,radiusofcurvature,andpressureangle,areconsideredastheconstraintsintheoptimizationproblem.Themajordifferenceoftheproposedresearchfromtypicalcamprofileoptimizationisthattheoutputtorqueisselectedastheobjectivefunctioninsteadoftheresidualvibrations.Thereasonisthatthepresenceofresidualvibrationsisnotprominentbecausethefollower(SeeFig.1)isdesignedtohaveenoughrigidityinthecam-followermechanism.Incontrast,theoutputtorqueataspecifiedenginespeedisoneofthemajorconcernsfromtheenginedesignaspect.Thechoiceoftheoutputtorqueastheobjectivefunctionprovidesmultidisciplinaryaspectstotheproposedresearch,inwhichbothcamdesignandenginedesignareincluded.Second,insteadofstudyingonlyonecaminthepaststudies,theproposedresearchaimstooptimizeintakecamandexhaustcamsimultaneouslytomakethecam-followermechanismfulfillappropriatelythedifferentengineeventsduringthewholeenginecycle.Thecomplexityoftheoptimizationproblemincreasesaccordinglysincebothcamsaredesignedintheoptimizationproblem.Finally,tostudycomprehensivelytheoptimizationproblem,ananalyticalscenarioisdesignedtoinvestigatehowtheoptimizationresultsareaffectedbydifferentcombinationsofcamprofilerepresentationsandoptimizationmethods.Acomplexcamprofileoptimizationproblemhasbeeninvestigatedforauniquecammechanisminanewcamdriveengine.First,theoptimizationproblemhasbeendefinedbytakingintoaccountmultipledesignspecifications.Theoutputtorqueoftheengineisconsideredastheobjectivefunction.Inaddition,theotherdesignspecifications,includingthecontactstress,thepressureangle,andtheradiusofcurvature,areselectedastheconstraints.Second,ananalyticalscenariohasbeendesignedtoinvestigatehowtheoptimizationresultsareaffectedbydifferentcombinationsofcamprofilerepresentationsandoptimizationmethods.Tothisend,twotypesofcurverepresentations,i.e.,generalpolynomialsplineand
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 工信部披露一季度运营数据持续关注流量、算力基建产业链
- 家具卖场销售管理制度
- 家居建材营销活动策划方案
- 自动化生产线安装与调试(内蒙古机电职业技术学院)智慧树知到期末考试答案2024年
- 中医护理智慧树知到期末考试答案2024年
- 中式烹调技术智慧树知到期末考试答案2024年
- 大班幼儿消防安全常识
- 除夕辞旧迎新的作文(8篇)
- 胸腔闭式引流护理2023年指南解读
- 油品泄漏事故专项预案
- 物理实验单臂电桥实验报告
- 《飞夺泸定桥》课件
- 审计整改培训课件
- 如何上好一节数学课课件
- 2024年上海中煤有限物资公司招聘笔试参考题库含答案解析
- 女性健身养生小知识讲座
- 挂职证明模板
- 动脉夹层的护理课件
- 浙西南红军歌曲赏析智慧树知到课后章节答案2023年下丽水学院
- 英美国家概况智慧树知到课后章节答案2023年下成都文理学院
- 绿色建筑案例分析
评论
0/150
提交评论