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外文翻译--液压系统的控制元件隔振 英文版.pdf外文翻译--液压系统的控制元件隔振 英文版.pdf -- 5 元

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ARCHIVESOFCIVILANDMECHANICALENGINEERINGVol.XI2011No.1VibrationinsulationofhydraulicsystemcontrolcomponentsM.STOSIAKWrocg225awUniversityofTechnology,Wybrzeg298eWyspiag276skiego25,50370Wrocg225aw,Poland.Thispaperdealswiththeeffectsofexternalmechanicalvibrationsonhydraulicvalves.Atheoreticalanalysisofthecontributionofselectedvibrationinsulatorstoareductioninhydraulicvalvehousingvibrationswascarriedout.Theresultsofpreliminaryexperimentaltestsofsimplevibrationinsulatorsarereported.Keywordsmechanicalvibrations,pressurefluctuations,hydraulicvalve1.IntroductionMajorfeaturesofhydraulicsystemsareperiodicchangesofpressurearoundanaveragevalue,commonlyreferredtoaspressurefluctuations.Theirconsequencesaredefinitelynegative.Thecyclicoperationofthepumpsdisplacementcomponents1ortheselfexcitationofthecontrolcomponentsinhydraulicvalves2duetotheactionoftheflowingliquid4ortoexternalmechanicalvibrations3,5,6areamongthecausesofpressurefluctuations.Pressurefluctuationscausetheindividualsystemcomponentstovibrate.Thishasanadverseeffect,particularlyontheprecisionofpositioningof,forexample,thecuttingtoolinamachinetool.Thisalsoappliesalthoughtoasmallerdegreetomobilemachineswhicharethesourceofvibrationsaffectingtherigidlyfixedhydraulicvalves.Generally,thecomplexproblemofthetransmissionofvibrationsbyamachineorapieceofequipmentcanbedividedintothreeinterconnectedcategoriesg120vibrationsources,g120vibrationtransmissionpaths,g120effects.Themostfrequentcauseofvibrationsaredisturbancesconnectedwiththemotionoroperationofthemachine,forexamplewhenamobilemachinemovesonanunevensurfaceorwhentherotatingpartsareunbalancedduringmaterialmachining.Anothermajorvibrationsourcearedriveunits,forexampleacombustionengineperformingaperiodicvariablecharacteristicworkcycle7,8.Anoperatinghydraulicsystemisalsoasourceofmechanicalvibrationscausedmainlybypressuresurgesandtheperiodicoperationofthedisplacementpump.Sincethegeneratedvibrationshavedifferentfrequenciesthepathsoftheirtransmissionarealsodifferent.Theirregularitiesofthesurfaceonwhichamobilemachinemovescauseexcitationsinafrequencyrangeof0.5–250Hz9–11.Thelatterincludesexcitationsgeneratedbythedrivingcombustionengineandthedisplacementpumpkinematics,manifestingthemselvesinpresM.STOSIAK238surefluctuationsinthemachineshydraulicsystem.Thevibrationsduetotheresistanceofflowingairareinafrequencyrangeof250–16000Hzandtheyarecausedbyairflowseparationfromthemachinescomponents.Alsotheflowoftheworkingmediuminthehydraulicsystemcausesvibrationandnoise.Sometimescavitationoccurs,generatinghighfrequencynoise.Thevibrationsgeneratedandtransmittedbyamachineproducevariouseffects.Mechanicalvibrationsaffectthemachineoperator.Thecomponentsofthesystemswithwhichthemachineisequipped,particularlyhydrauliccomponentsandsystemsarealsosubjecttomechanicalvibrations.Suchcomponentsarerequiredtohavegooddynamicpropertiesandtobecharacterizedbystability,positioningprecision,operatingreliabilityandcertaintyandlittlenoisiness.Modernproportionalhydraulicvalvesorhydraulicmicrovalvesareparticularlyexposedtoexternalmechanicalvibrationssincethedisturbingforcesinthemcanamounttothecontrollingforces,whichmayleadtomanyadverseeffects,suchasstabilityloss,positioninginaccuracy,damagetosealsandincreasednoisiness12.2.FlexiblefixingofhydraulicvalveAsmentionedabove,inordertominimizethevibrationofthehydraulicvalvescontrolelementitseemssensibletoisolatethevalvehousingfromtheexternalmechanicalvibrationsofthebaseforexamplethevibratingframeofamobilemachineoramachinetool.Fortheanalysisoftheeffectoftheflexiblefixingofahydraulicvalveonthevibrationofitshousingaspecialclampingholderforthehydraulicdistributorwasdesigned.ThelatterisonitstwosidessupportedbyasystemofspringswithaknownlinearcharacteristicandaknownpredeflectionFigure1.Fig.1.Valveholder1–hydraulicvalvedistributor,2–holderbase,3–springpredeflectionbolts,4–springs,5–securingcatchesThedesignoftheholderissuchthatthevalvemountedinitisconstrainedbyspringswithanequivalentstiffnessanditmovesontheholderbase2inFigure1rubbingagainstitinaccordancewiththedryfrictionmodel.OnitstwosidesthevalveVibrationinsulationofhydraulicsystemcontrolcomponents239issupportedbysprings.Aschemeofthehydraulicsysteminwhichtheproportionaldistributortype4WRE6E0812/24Z4/MoperatesisshowninFigure2.TPAB413ww0sin2g83ftFig.2.Schemeofhydraulicsystemincorporatinginvestigatedcomponent1–feedpump,2–reliefvalve,3–investigatedcomponent,4–adjustablethrottlevalveForatwomasssystemthemodeloftheproportionaldistributoroperatinginthehydraulicsystemshowninFigure2canberepresentedbythefollowingsystemoffourequationsg11g12g11g12g11g12g11g12g11g12g11g12g11g12g11g12g11g12g11g12g11g12g11g12g11g12g176g176g176g176g176g176g176g176g175g176g176g176g176g176g176g176g176g174g173g32g152g152g152g16g14g14g16g152g16g16g16g152g152g152g14g14g16g152g14g16g152g14g16g152g14g152g32g152g152g152g16g152g16g152g16g152g16g32g152g16g152g16g16g152g152g16g152g152g16g32g16g152g14g14g16g152g16g152g152g152g152g14g16g152g152g152g152g14g152.01,02,025.1,2172.02222022212112122212211111111212121121212111gimwXsingwXsingwXlHgmwXcXXkXXcXmpACpcpcpaQpcpappxxXsQFXXcppxxXsXXhldXmzaqkkppkpmpspMmpstg80g80g85g85g91g80g83g5g5g5g5g5g5g5g5g5g5g5g5g5g5g51M.STOSIAK240Thefourthequationdescribestheforcesactingonthevalvehousingintheconsideredcase.Furtheronthisequationwillbemodifiedtodescribethecharacteristicsoftheproposedvibrationinsulationelements.SomesimplifyingassumptionstoEquations1g120workingliquiddoesnotchangeitsproperties,g120Coulombfrictionisneglectedinpairspoolmuffinsidedirectionalcontrolvalve,g120Coulombfrictionrepresentscooperationbetweenvalvebodyandvalveholder,g120afterplaybetweenvalvebodyandsecuringcatchesiscancelledCoulombfrictionrepresentscooperationbetweenvalvebodyandsecuringcatches,g120springscharacteristicsarelinearanddescribedbystiffnesscoefficientc,g120descriptionofhydraulicsystemisbasedonconcentratedparametermodel,g120themodeldoesnotrepresentinfluencepipesonvalvebodyvibrations.ListofmajorsymbolsSymbolParameterDimensioninSIap1leakagecoefficientm4s/kgAathrottlevalvegapaream2c1equivalentstiffnessofvalvecentringspringsN/mczequivalentstiffnessofspringsfixingvalveinholderN/mCq1throttlevalveflowratio–dtpistondiametermffrequencyHzgEarthsaccelerationm/s2hvalvesleevepairgapthicknessmHHeavisidestepfunction–k1,k2dampinginrespectivelyvalvesleevepairandhousingholderpairNs/mlpistonlengthml0gapofvalvebodyandsecuringcatchesmm1massofpistonvalveand1/3ofspringmasskgm2massofdistributorhousingkgp1pressurebeforedistributorPap2pressureafterdistributorPapzsinklinepressurePag39p2throttlevalvepressuredropPassmaximumgapwidthmttimeswexcitationvibrationamplitudemQptheoreticalpumpdeliverym3/sxmgaplengthmxpmutualshiftofvalveandhousingedgesmX1displacementofpistonvalvemX2displacementofdistributorhousingmg802coefficientoffrictionofvalvehousingagainstsecuringcatches–g80icoefficientoffrictionofvalvehousingagainstholderbase–g85workingliquiddensitykg/m3g90angularfrequencyrad/s
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