外文翻译--液压系统的控制元件隔振 英文版.pdf

ARCHIVESOFCIVILANDMECHANICALENGINEERINGVol.XI2011No.1VibrationinsulationofhydraulicsystemcontrolcomponentsM.STOSIAKWrocg225awUniversityofTechnology,Wybrzeg298eWyspiag276skiego25,50-370Wrocg225aw,Poland.Thispaperdealswiththeeffectsofexternalmechanicalvibrationsonhydraulicvalves.Atheoreticalanaly-sisofthecontributionofselectedvibrationinsulatorstoareductioninhydraulicvalvehousingvibrationswascarriedout.Theresultsofpreliminaryexperimentaltestsofsimplevibrationinsulatorsarereported.Keywords:mechanicalvibrations,pressurefluctuations,hydraulicvalve1.IntroductionMajorfeaturesofhydraulicsystemsareperiodicchangesofpressurearoundanaver-agevalue,commonlyreferredtoaspressurefluctuations.Theirconsequencesaredefi-nitelynegative.Thecyclicoperationofthepumpsdisplacementcomponents1ortheself-excitationofthecontrolcomponentsinhydraulicvalves2duetotheactionoftheflowingliquid4ortoexternalmechanicalvibrations3,5,6areamongthecausesofpressurefluctuations.Pressurefluctuationscausetheindividualsystemcomponentstovibrate.Thishasanadverseeffect,particularlyontheprecisionofpositioningof,forex-ample,thecuttingtoolinamachinetool.Thisalsoapplies(althoughtoasmallerdegree)tomobilemachineswhicharethesourceofvibrationsaffectingtherigidlyfixedhydraulicvalves.Generally,thecomplexproblemofthetransmissionofvibrationsbyamachineorapieceofequipmentcanbedividedintothreeinterconnectedcategories:g120vibrationsources,g120vibrationtransmissionpaths,g120effects.Themostfrequentcauseofvibrationsaredisturbancesconnectedwiththemotionoroperationofthemachine,forexamplewhenamobilemachinemovesonanunevensurfaceorwhentherotatingpartsareunbalancedduringmaterialmachining.Anothermajorvibrationsourcearedriveunits,forexampleacombustionengineperformingaperiodicvariable-characteristicworkcycle7,8.Anoperatinghydraulicsystemisalsoasourceofmechanicalvibrationscausedmainlybypressuresurgesandtheperi-odicoperationofthedisplacementpump.Sincethegeneratedvibrationshavedifferentfrequenciesthepathsoftheirtransmissionarealsodifferent.Theirregularitiesofthesurfaceonwhichamobilemachinemovescauseexcitationsinafrequencyrangeof0.5250Hz911.Thelatterincludesexcitationsgeneratedbythedriving(combus-tion)engineandthedisplacementpumpkinematics,manifestingthemselvesinpres-M.STOSIAK238surefluctuationsinthemachineshydraulicsystem.Thevibrationsduetotheresis-tanceofflowingairareinafrequencyrangeof25016000Hzandtheyarecausedbyairflowseparationfromthemachinescomponents.Alsotheflowoftheworkingme-diuminthehydraulicsystemcausesvibrationandnoise.Sometimescavitationoccurs,generatinghigh-frequencynoise.Thevibrationsgeneratedandtransmittedbyama-chineproducevariouseffects.Mechanicalvibrationsaffectthemachineoperator.Thecomponentsofthesystemswithwhichthemachineisequipped,particularlyhydrauliccomponentsandsystemsarealsosubjecttomechanicalvibrations.Suchcomponentsarerequiredtohavegooddynamicpropertiesandtobecharacterizedbystability,positioningprecision,operatingreliabilityandcertaintyandlittlenoisiness.Modernproportionalhydraulicvalvesorhydraulicmicrovalvesareparticularlyexposedtoexternalmechanicalvibrationssincethedisturbingforcesinthemcanamounttothecontrollingforces,whichmayleadtomanyadverseeffects,suchasstabilityloss,po-sitioninginaccuracy,damagetosealsandincreasednoisiness12.2.FlexiblefixingofhydraulicvalveAsmentionedabove,inordertominimizethevibrationofthehydraulicvalvescontrolelementitseemssensibletoisolatethevalvehousingfromtheexternalme-chanicalvibrationsofthebase(forexamplethevibratingframeofamobilemachineoramachinetool).Fortheanalysisoftheeffectoftheflexiblefixingofahydraulicvalveonthevibrationofitshousingaspecialclampingholderforthehydraulicdis-tributorwasdesigned.Thelatterisonitstwosidessupportedbyasystemofspringswithaknownlinearcharacteristicandaknownpre-deflection(Figure1).Fig.1.Valveholder:1hydraulicvalve(distributor),2holderbase,3springpre-deflectionbolts,4springs,5securingcatchesThedesignoftheholderissuchthatthevalvemountedinitisconstrainedbysprings(withanequivalentstiffness)anditmovesontheholderbase(2inFigure1)rubbingagainstitinaccordancewiththedryfrictionmodel.OnitstwosidesthevalveVibrationinsulationofhydraulicsystemcontrolcomponents239issupportedbysprings.Aschemeofthehydraulicsysteminwhichtheproportionaldistributortype4WRE6E08-12/24Z4/MoperatesisshowninFigure2.TPAB413w=w0sin(2g83ft)Fig.2.Schemeofhydraulicsystemincorporatinginvestigatedcomponent:1feedpump,2reliefvalve,3investigatedcomponent,4adjustablethrottlevalveForatwo-masssystemthemodeloftheproportionaldistributoroperatinginthehydraulicsystemshowninFigure2canberepresentedbythefollowingsystemoffourequations:g11g12g11g12g11g12g11g12g11g12g11g12g11g12g11g12g11g12g11g12g11g12g11g12g11g12g176g176g176g176g176g176g176g176g175g176g176g176g176g176g176g176g176g174g173g32g152g152g152g16g14g14g16g152g16g16g16g152g152g152g14g14g16g152g14g16g152g14g16g152g14g152g32g152g152g152g16g152g16g152g16g152g16g32g152g16g152g16g16g152g152g16g152g152g16g32g16g152g14g14g16g152g16g152g152g152g152g14g16g152g152g152g152g14g152.01,02,025.1,2172.02222022212112122212211111111212121121212111gimwXsingwXsingwXlHgmwXcXXkXXcXmpACpcpcpaQpcpappxxXsQFXXcppxxXsXXhldXmzaqkkppkpmpspMmpstg80g80g85g85g91g80g83g5g5g5g5g5g5g5g5g5g5g5g5g5g5g5(1)M.STOSIAK240Thefourthequationdescribestheforcesactingonthevalvehousingintheconsid-eredcase.Furtheronthisequationwillbemodifiedtodescribethecharacteristicsoftheproposedvibrationinsulationelements.SomesimplifyingassumptionstoEqua-tions(1):g120workingliquiddoesnotchangeitsproperties,g120Coulombfrictionisneglectedinpair:spool-muffinsidedirectionalcontrolvalve,g120Coulombfrictionrepresentscooperationbetweenvalvebodyandvalveholder,g120afterplay(betweenvalvebodyandsecuringcatches)iscancelledCoulombfrictionrepresentscooperationbetweenvalvebodyandsecuringcatches,g120springscharacteristicsarelinearanddescribedbystiffnesscoefficientc,g120descriptionofhydraulicsystemisbasedonconcentratedparametermodel,g120themodeldoesnotrepresentinfluencepipesonvalvebodyvibrations.Listofmajorsymbols:SymbolParameterDimensioninSIap1leakagecoefficientm4s/kgAathrottlevalvegapaream2c1equivalentstiffnessofvalvecentringspringsN/mczequivalentstiffnessofspringsfixingvalveinholderN/mCq1throttlevalveflowratiodtpistondiametermffrequencyHzgEarthsaccelerationm/s2hvalve-sleevepair