外文翻译--液压系统和气压系统.doc

HYDRAULICSYSTEMANDPEUMATICSYSTEMHUIXIONGWAN1,JUNFAN21SCHOOLOFMECHANICALSCIENCEANDENGINEENING,HUAZHONGUNIVOFSCIENCEANDTECHNOLOGY,WUHAN,430074,CHINA2SCHOOLOFLOGISTICSENGINEENING,WUHAN,UNIVOFSCIENCEANDTECHNOLOGY,WUHAN,430063,CHINAABSTRACTHYDRAULICSYSTEMISWIDELYUSEDININDUSTRY,SUCHASSTAMPING,GRINDINGOFSTEELTYPEWORKANDGENERALPROCESSINGINDUSTRIES,AGRICULTURE,MINING,SPACETECHNOLOGY,DEEPSEAEXPLORATION,TRANSPORTATION,MARINETECHNOLOGY,OFFSHOREGASANDOILEXPLORATIONINDUSTRIES,INSHORT,FEWPEOPLEINTHEIRDAILYLIVESDONOTGETCERTAINBENEFITSFROMTHEHYDRAULICTECHNOLOGYSUCCESSFULANDWIDELYUSEDINTHEHYDRAULICSYSTEMSSECRETLIESINITSVERSATILITYANDEASEOFMANEUVERABILITYHYDRAULICPOWERTRANSMISSIONMECHANICALSYSTEMSASBEINGNOTLIKETHEMACHINEGEOMETRYCONSTRAINTS,INADDITION,THEHYDRAULICSYSTEMDOESNOTLIKETHEELECTRICALSYSTEM,ASCONSTRAINEDBYTHEPHYSICALPROPERTIESOFMATERIALS,ITPASSEDALMOSTNOAMOUNTOFPOWERCONSTRAINTSKEYWORDSHYDRAULICSYSTEM,PRESSURESYSTEM,FLUIDTHEHISTORYOFHYDRAULICPOWERISALONGONE,DATINGFROMMAN’SPREHISTORICEFFORTSTOHARNESSTHEENERGYINTHEWORLDAROUNDHIMTHEONLYSOURCEREADILYAVAILABLEWERETHEWATERANDTHEWINDTWOFREEANDMOVINGSTREAMSTHEWATERMILL,THEFIRSTHYDRAULICMOTOR,WASANEARLYINVENTIONONEISPICTUREDONAMOSATICATTHEGREATPALACEINBYZANTIUM,DATINGFROMTHEEARLYFIFTHCENTURYTHEMILLHADBEENBUILTBYTHEROMANSBUTTHEFIRSTRECORDOFAWATERMILLGOESBACKEVENFURTHER,TOAROUND100BC,ANDTHEORIGINSMAYINDEEDHAVEBEENMUCHEARLIERTHEDOMESTICATIONOFGRAINBEGANSOME5000YEARSBEFOREANDSOMEENTERPRISINGFARMERISBOUNDTOHAVEBECOMETIREDOFPOUNDINGORGRINDINGTHEGRAINBYHANDPERHAPS,INFACT,THEINVENTORWERESOMEFARMER’SWIVESSINCETHEOFTENDREWTHEHEAVYJOBSFLUIDISASUBSTANCEWHICHMAYFLOW；THATIS,ITSCONSTITUENTPARTICLESMAYCONTINUOUSLYCHANGETHEIRPOSITIONSRELATIVETOONEANOTHERMOREOVER,ITOFFERSNOLASTINGRESISTANCETOTHEDISPLACEMENT,HOWEVERGREAT,OFONELAYEROVERANOTHERTHISMEANSTHAT,IFTHEFLUIDISATREST,NOSHEARFORCETHATISAFORCETANGENTIALTOTHESURFACEONWHICHITACTSCANEXISTINITFLUIDMAYBECLASSIFIEDASNEWTONIANORNONNEWTONIANINNEWTONIANFLUIDTHEREISALINEARRELATIONBETWEENTHEMAGNITUDEOFAPPLIEDSHEARSTRESSESANDTHERESULTINGRATEOFANGULARDEFORMATIONINNONNEWTONIANFLUIDTHEREISANONLINEARRELATIONBETWEENTHEMAGNITUDEOFAPPLIEDSHEARSTRESSANDTHERATEOFANGULARDEFORMATIONTHEFLOWOFFLUIDSMAYBECLASSIFIEDINMANYWAYS,SUCHASSTEADYORNONSTEADY,ROTATIONALORIRROTATIONAL,COMPRESSIBLEORINCOMPRESSIBLE,ANDVISCOUSORNOVISCOUSALLHYDRAULICSYSTEMSDEPENDONPASCAL’SLAW,SUCHASSTEADYORPIPEEXERTSEQUALFORCEONALLOFTHESURFACESOFTHECONTAINERINACTUALHYDRAULICSYSTEMS,PASCAL’SLAWDEFINESTHEBASISOFRESULTSWHICHAREOBTAINEDFROMTHESYSTEMTHUS,APUMPMOVESTHELIQUIDINTHESYSTEMTHEINTAKEOFTHEPUMPISCONNECTEDTOALIQUIDSOURCE,USUALLYCALLEDTHETANKORRESERVOIRATMOSPHERICPRESSURE,PRESSINGONTHELIQUIDINTHERESERVOIR,FORCESTHELIQUIDINTOTHEPUMPWHENTHEPUMPOPERATES,ITFORCESLIQUIDFROMTHETANKINTOTHEDISCHARGEPIPEATASUITABLEPRESSURETHEFLOWOFTHEPRESSURIZEDLIQUIDDISCHARGEDBYTHEPUMPISCONTROLLEDBYVALVESTHREECONTROLFUNCTIONSAREUSEDINMOSTHYDRAULICSYSTEMS1CONTROLOFTHELIQUIDPRESSURE,（2）CONTROLOFTHELIQUIDFLOWRATE,AND3CONTROLOFTHEDIRECTIONOFFLOWOFTHELIQUIDHYDRAULICDRIVESAREUSEDINPREFERENCETOMECHANICALSYSTEMSWHEN1POWERSISTOBETRANSMITTEDBETWEENPOINTTOOFARAPARTFORCHAINSORBELTS；2HIGHTORQUEATLOWSPEEDINREQUIRED；3AVERYCOMPACTUNITISNEEDED；4ASMOOTHTRANSMISSION,FREEOFVIBRATION,ISREQUIRED；5EASYCONTROLOFSPEEDANDDIRECTIONISNECESSARY；AND6OUTPUTSPEEDISVARIEDSTEPLESSLYFIG1GIVESADIAGRAMMATICPRESENTATIONOFTHECOMPONENTSOFAHYDRAULICINSTALLATIONELECTRICALLYDRIVENOILPRESSUREPUMPSESTABLISHANOILFLOWFORENERGYTRANSMISSION,WHICHISFEDTOHYDRAULICMOTORSORHYDRAULICCYLINDERS,CONVERTINGITINTOMECHANICALENERGYTHECONTROLOFTHEOILFLOWISBYMEANSOFVALVESTHEPRESSURIZEDOILFLOWPRODUCESLINEARORROTARYMECHANICALMOTIONTHEKINETICENERGYOFTHEOILFLOWISCOMPARATIVELYLOW,ANDTHEREFORETHETERMHYDROSTATICDRIVERISSOMETIMESUSEDTHEREISLITTLECONSTRUCTIONALDIFFERENCEBETWEENHYDRAULICMOTORSANDPUMPSANYPUMPMAYBEUSEDASAMOTORTHEQUANTITYOFOILFLOWINGATANYGIVENTIMEMAYBEVARIEDBYMEANSOFREGULATINGVALVESASSHOWNINFIG71ORTHEUSEOFVARIABLEDELIVERYPUMPSTHEAPPLICATIONOFHYDRAULICPOWERTOTHEOPERATIONOFMACHINETOOLSISBYNOMEANSNEW,THOUGHITSADOPTIONONSUCHAWIDESCALEASEXISTSATPRESENTISCOMPARATIVELYRECENTITWASINFACTINDEVELOPMENTOFTHEMODERNSELFCONTAINEDPUMPUNITTHATSTIMULATEDTHEGROWTHOFTHISFORMOFMACHINETOOLOPERATIONHYDRAULICMACHINETOOLDRIVEOFFERSAGREATMANYADVANTAGESONEOFTHEMISTHATITCANGIVEINFINITELYVARIABLESPEEDCONTROLOVERWIDERANGESINADDITION,THEYCANCHANGETHEDIRECTIONOFDRIVEASEASILYASTHEYCANVARYTHESPEEDASINMANYOTHERTYPESOFMACHINE,MANYCOMPLEXMECHANICALLINKAGESCANBESIMPLIFIEDOREVENWHOLLYELIMINATEDBYTHEUSEOFHYDRAULICSTHEFLEXIBILITYANDRESILIENCEOFHYDRAULICPOWERISANOTHERGREATVIRTUEOFTHISFORMOFDRIVEAPARTFROMTHESMOOTHNESSOFOPERATIONTHUSOBTAINED,AGREATIMPROVEMENTISUSUALLYFOUNDINTHESURFACEFINISHONTHEWORKANDTHETOOLCANMAKEHEAVIERCUTSWITHOUTDETRIMENTANDWILLLASTCONSIDERABLYLONGERWITHOUTREGRINDINGHYDRAULICANDPNEUMATICSYSTEMTHEREAREONLYTHREEBASICMETHODSOFTRANSMITTINGPOWERELECTRICAL,MECHANICAL,ANDFLUIDPOWERMOSTAPPLICATIONSACTUALLYUSEACOMBINATIONOFTHETHREEMETHODSTOOBTAINTHEMOSTEFFICIENTOVERALLSYSTEMTOPROPERLYDETERMINEWHICHPRINCIPLEMETHODTOUSE,ITISIMPORTANTTOKNOWTHESALIENTFEATURESOFEACHTYPEFOREXAMPLE,FLUIDSYSTEMSCANTRANSMITPOWERMOREECONOMICALLYOVERGREATERDISTANCESTHANCANMECHANICALTYPESHOWEVER,FLUIDSYSTEMSARERESTRICTEDTOSHORTERDISTANCESTHANAREELECTRICALSYSTEMSHYDRAULICPOWERTRANSMISSIONSYSTEMARECONCERNEDWITHTHEGENERATION,MODELATION,ANDCONTROLOFPRESSUREANDFLOW，ANDINGENERALSUCHSYSTEMSINCLUDE1PUMPSWHICHCONVERTAVAILABLEPOWERFROMTHEPRIMEMOVERTOHYDRAULICPOWERATTHEACTUATOR2VALVESWHICHCONTROLTHEDIRECTIONOFPUMPFLOW,THELEVELOFPOWERPRODUCED,ANDTHEAMOUNTOFFLUIDFLOWTOTHEACTUATORSTHEPOWERLEVELISDETERMINEDBYCONTROLLINGBOTHTHEFLOWANDPRESSURELEVEL3ACTCATORSWHICHCONVERTHYDTAULICPOWERTOUSABLEMECHANICALPOWEROUTPUTATTHEPOINTREQUIRED4THEMEDIUM,WHICHISALIQUID,PROVIDESRIGIDTRANSMISSIONANDCONTROLASWELLASLUBRICATIONOFCOMPONTS,SEALINGINVALVES,ANDCOOLINGOFTHESYSTEM5CONNCETOTSWHICHLINKTHEVARIOUSSYSTEMCOMPONENTS,PROVIDEPOWERCONDUCTORSFORTHEFLUIDUNDERPRESSURE,ANDFLUIDFLOWRETURNTOTANKRESERVOIR6FLUIDSTORAGEANDCONDITIONINGEQUIPMENTWHICHENSURESUFFICIENTQUALITYANDQUANTITYASWELLASCOOLINGOFTHEFLUIDHYDRAULICSYSTEMSAREUSEDININDUSTRIALAPPLICATIONSSUCHASSTAMPINGPRESSES,STEELMILLS,ANDGENERALMANUFACTURING,AGRICULTURALMACHINES,MININGINDUSTRY,AVIATION,SPACETECHNOLOGY,DEEPSEAEXPLORATION,TRANSPORTION,MARINETECHNOLOGY,ANDOFFSHOREGASANDPETROLEUMEXPLORATIONINSHORT,VERYFEWPEOPLEGETTHROUGHADAYOFTHEIRLIVESWITHOUTSOMEHOWBENEFITINGFROMTHETECHNOLOGYOFHYDRAULICKSTHESECRETOFHYDRAULICSYSTEM’SSUCCESSANDWIDESPREADUSEISITSVERSATILITYANDMANAGEABILITYFLUIDPOWERISNOTHINDEREDBYTHEGEOMETRYOFTHEMACHINEASISTHECASEINMECHANICALSYSTEMSALSO,POWERCANBETRANSMITTEDINALMOSTLIMITLESSQUANTITIESBECAUSEFLUIDSYSTEMSARENOTSOLIMITEDBYTHEPHYSICALLIMITATIONSOFMATERIALSASARETHEELECTRICALSYSTEMSFOREXAMPLE,THEPERFORMANCEOFANELECTROMANGNETISLIMITEDBYTHESATURATIONLIMITOFSTEELONTHEOTHERHAND,THEPOWERLIMITOFFLUIDSYSTEMSISLIMITEDONLYBYTHESTRENGTHCAPACITYOFTHEMATERIALINDUSTRYISGOINGTODEPENDMOREANDMOREONAUTOMATIONINORDERTOINCREASEPRODUCTIVITYTHISINCLUDESREMOTEANDDIRECTCONTROLOFPRODUCTIONOPERATIONS,MANUFACTURINGPROCESSES,ANDMATERIALSHANDLINGFLUIDPOWERISTHEMUSCLEOFAUTOMATIONBECAUSEOFADVANTAGESINTHEFOLLOWINGFOURMAJORCATEGORIES1EASEANDACCURACYOFCONTROLBYTHEUSEOFSIMPLELEVERSANDPUSHBUTTONS,THEOPERATOROFAFLUIDPOWERSYSTEMCANREADILYSTART,STOP,SPEEDUPORSLOWDOWN,ANDPOSITIONFORCESWHICHPROVIDEANYDESIREDHORSEPOWERWITHTOLERANCESASPRECISEASONETENTHOUSANDTHOFANINCH2MULTIPLICATIONOFFORCEAFLUIDPOWERSYSTEMWITHOUTUSINGCUMBERSOMEGEARS,PULLEYS,ANDLEVERSCANMULTIPLYFORCESSIMPLYANDEFFICIENTLYFROMAFRACTIONOFANOUNCETOSEVERALHUNDREDTONSOFOUTPUT3CONSTANTFORCEORTORQUEONLYFLUIDPOWERSYSTEMSARECAPABLEOFPROVIDINGCONTANTFORCEORTORQUEREGARDLESSOFSPEEDCHANGESTHISISACCOMPLISHEDWHETHERTHEWORKOUTPUTMOVESAFEWINCHESPERHOUR,SEVERALHUNDREDINCHESPERMINUTE,AFEWREVOLUTIONSPERHOUR,ORTHOUSANDSOFREVOLUTIONSPERMINUTE4SIMPLICITY,SAFELY,ECONOMYINGENERAL,FLUIDPOWERSYSTEMSUSEFEWERMOVINGPARTSTHANCOMPARABLEMECHANICALORELECTRICALSYSTEMSTHUS,THEYARESIMPLERTOMAINTAINANDOPERATETHIS,INTURN,MAXIMIZESSAFETY,COMPANCTNESS,ANDRELIABILITYFOREXAMPLE,ANEWPOWERSTEERINGCONTROLDESIGNEDHASMADEALLOTHER