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1、内蒙古工业大学硕士学位论文基于振动分析的气门间隙异常故障诊断姓名：刘鹏申请学位级别：硕士专业：动力机械及工程指导教师：司景萍20060601AbstractAbnormalfaultofInternalCombustionEnginevalvesclearancehavetheverybigpercentinvarioustypeofInternalCombustionEnginefaults,soithasimportantmeaningtomakediagnosisofthiskindfault.ThispapertaketheDA462typeengineasresearchobj
2、ect,puttingforwarddiagnosismethodbasedonvibrationanalysisaccordingtoabnormalstateofvalvesclearance.Inthispaper,authortakeanalysissuchastheInternalCombustionEnginestructureandtheoperationcharacteristicasthefoundation,makingsurethatthecombustionexcitation,thepistonslapexcitation,theinertiaforceenco
3、urage,thevalvefallingimpactandthrottleimpactwhenvalveopensactasmainexcitationsource,andanalyzethepropagationpathofenginevibration.Combiningthissubjectstudy,chooseresponseofthecombustionexcitationandexhaustvalveexcitationasfaultcharacteristicsignal.Throughstudyingthemethodofanalyzingvibrationsigna
4、lindetails,adoptthemethodofsignalanalysiscombiningthetimedomainanalysistogetherwiththefrequencydomainanalysis.Basingontheanalysisofmodernvibratemeasuringandtestingtechniques,builtasetofpracticalvibrationsignalmeasuringandtestingsystemsuccessfully.Throughtheexperiment,verifythatthissystemcangetfau
5、ltcharacteristicsignalaccurately.Adoptthemethodof“shuangpaibujin”toadjustthevalveclearancedatawhichare0.15mm,0.25mm,0.35mmand0.45mm.Amongthosedata,normalclearanceis0.15mm,usingtheotherdatatosimulateabnormalstateofvalveclearance.Usingthemeasuringandtestingsystemthatwasbuiltformysubject,wecangetthe
6、vibrationsignalinconditionofdifferentrotationspeedandvalveclearance,makingconclusionthatdifferentrotationspeedandvalveclearanceinfluenceonthedegreeofthecharacteristicsignal.Thefrequencybandofthefaultcharacteristicsignalthroughthetheoriesanalysisistakencertainly,innextstepobservingrangeoffrequency
7、band’svariationwhenweadjustclearancedata,thenwecanjudgethesizeofthevalveclearanceinthelightoftimedomainandfrequencydomain’swavefigureoffaultcharacteristicsignal.ThroughtheexperimentverificationintheDA462engine,provetha
