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外文翻译--润滑和摩擦学在海水水力活塞泵中的应用.doc

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外文翻译--润滑和摩擦学在海水水力活塞泵中的应用.doc

附录二外文翻译英文文献lubricationandtribologyinseawaterhydraulicpistonpumpAbstractWaterhydraulicsystemshaveprovokedmajorinterestbecauseofthehumanfriendlyandenvironmentalsafetyaspects.Pistonpumpisoneofthemostfrequentlyusedhydraulicunitsinrecentengineeringtechnique.Inwaterhydraulicpistonpump,poorlubricationismorelikelytohappenthaninoilhydrauliconebecauseofdifferenceinpropertiesbetweenwaterandoil.Sotherearesomekeyproblemssuchascorrosivewearanderosion,whichareinvestigatedbriefly.Manynewmaterialshavebeendeveloped,whichgivelongerlifeexpectancieswithwaterwithoutcorrosionanderosion.AnewtypeofseawaterhydraulicpistonpumpswithbettersuctioncharacteristicshadbeendevelopedatHUST.Muchofthisresearchhasconcentratedonnewmaterials,structureandexperiments,whicharealsospeciallyintroduced.KeywordswaterhydraulicspistonpumplubricationtestmaterialINTRODUCTIONTheearliesthydraulicsystemsusedwaterasthehydraulicfluid.Thisrestrictedtheworkingtemperaturerangeandcausedcorrosionaswellaslubricatingproblems.Itwasnotuntilthelate1920sthatmineralhydraulicoilswereintroduced.Consequently,theoilbecamethemainpressuremediumofhydraulicapplications.Recently,thedemandforusingpuretapwaterexcludingseawaterasapressuremediuminhydraulicapplicationshasincreasedduetoitsavailability,easymaintenance,itslowcostandhighsafetylevelsagainstpollutionandfirehazard.So,waterhydraulicscanbeusedinnewapplicationareassuchasfoodprocessing,pulpandpaperindustry,medicine,glassmaking,coalminingandnuclearindustry.Waterischaracterizedbyverylowviscosityincomparisonwithmineralhydraulicoils.Forexample,thekinematicsviscosityofwaterat40isabout0.72m/sandoftypicalmineraloilis322m/s.Keyproblemsshouldbeconsideredinwaterhydraulicsystem.Firstly,theverylowviscositymustincreasethedifficultyofdevelopinghydrodynamicfilmbetweenfrictionalpairs,andtheverysmallchangeofwatersviscositywithpressuremeansthatelastohydrodynamiclubricationwithhardmaterialsisunlikelytooccur.So,thelowviscosityisaccompaniedwithpoorlubricityofwater.Poorlubricitycancausecorrosivewearanderosionproblems.Secondly,itistobenotedthatwaterespeciallyseawateriselectricallyconductiveandmayactasanelectrolytewhenimpuritiesorcertainadditivesarepresent.Insuchcasestheelectrolyticcorrosionmayoccur.Thereforemetallicmaterialstobeusedinconnectionwiththewaterpressuremediumshouldcomplywiththeelectrochemicalseries.Fromthepresentpointofview,oilhasanadvantageagainstwaterintheaspectoflubricationbuttherecenttechnologyofmaterials,designsandtribologyhasbroughtthepossibilityofusingwaterasapressuremediumagain.Anumberofnewmaterials,suchasstainlesssteel,corrosionresistantalloy,ceramics,polymers,bronze,brass,anodizedaluminaandcomposites,etc.,havegoodcompatibilitywithwater,alongwithmoderndesignandmanufacturingtechniques,waterhydraulicsbecomemoreandmorepractical.Modernscienceandtechnologiescanprovideessentialtechnicalguaranteeforthereemergenceanddevelopmentofwaterhydraulics.Pistonpumpisoneofthemostfrequentlyusedhydraulicunitsinrecentengineeringtechniques.Inwaterhydraulicpistonpump,poorlubricationismorelikelytohappenthanthatinoilhydrauliconeInwaterhydraulicsystem,thefirstobjectiveistodeveloppistonpumpandmotorusingrawwateraspressuremedium.Todealwithproblemsofusingrawwateraslubricant,threecriticalslidingpairs,suchasthecylinderblock/portplate,piston/cylinderbore,swashplate/slipperpadhavebeenfocused.Waterpistonpumpmotorhasbeendevelopedinsomedevelopedcountries,suchasUSA,UK,Japan,Denmark,GermanyandFinland,etc.Pumpsandmotorsarevirtuallyidentical.TheFennercompanyintheUnitedKingdomhasdevelopedanaxialpumpforrawwaterwithfixeddisplacement.Thepumpsandmotorsareoftheswashplatetype.Bearingcentersaredesignedtobeinlinewiththetorquecentersoftheunitsinordertominimizetiltforcesonthevalveplate.Allrubbingsurfacesusepolymerstainlessinterfaces.Anadaptationofthepumpusingceramicpistonshasoperatedsuccessfullyupto14MPa.Thecasingaremadeofstainlesssteel.TheHauhincoradialpistonpumpinGermanyhasfixeddisplacement.Thepumpdesignisbaseduponusingnewandnontraditionalmaterialssothataseparatelubricationsystemisavoided.Themedium,industrialwater,tobepumpedalsoactsasalubricant.Typicallypumpratingsareflowrateupto242L/min,pressureupto32MPa.TheDanfossNessiepumpoftypePHApumpaxialhighpressureinDenmarkisdesignedasanintegralunitbasedupontheswashplateprinciple.Allfrictionsurfaces,suchascylinders,thrustplateandpistonshoes,aremadesolelyofreinforcedplasticorovermoldedstainlesssteel.Theouterhousingandendflangesaremadeofchronitecastedspecialbrassinordertopreventcorrosion.Thepumpisdesignedsothatthelubricationofthemovingpartsinthepumpismaintainedbythewateritself.Allthepartsinthepumparemadeofnoncorrosivematerials,ensuringalonglifeofthepump.Thepressurelevelofthepumpis16MPa.TheaxialpistonpumpintheFinnishcompanyHytarcanalsoactasamotoranditcanbeoperatedinnormaltapwaterandseawater.Thepressurelevelofthepumpis21Mpaandthelifespanisabout8000hAftertenyearsofresearchanddevelopmentonhighwaterbasedfluidhydraulics,anewresearchanddevelopmentprogramfortapwaterandseawaterhydraulicssupportedbyNationalScienceFoundationofChinawerecarriedoutatHuazhongUniversityofScienceTechnologyHUSTfrom1990totoday.Recently,anewtypeofseawaterhydraulicpistonpumpswithbettersuctioncharacteristicshadbeendevelopedatHUST4.Muchofthisresearchhasconcentratedonnewmaterials,structureandexperiments,whicharespeciallyintroducedinthispaper.Meanwhile,theapplicationsonsomeaspectsforwaterhydraulicsarealsodescribed.1SEAWATERHYDRAULICAXIALPISTONPUMPATHUSTFigure1showstheschematicdiagramoftheseawaterhydraulicaxialpistonpumpatHUST.Itisaswashplateaxialsevenpistonpumpwithfixeddisplacement,whichcanworkwitheitherseawaterorrawwater.Thispumpsratingsareflowrateupto40L/min,pressureupto14MPa.Thespecifiedpressureis10MPa.Theinletandoutletcheckvalveswithsoftsealsarerespectivelyassociatedwitheachpiston,onthepistonsuctionstroke,waterisdrawnbyvacuumfromtheinletportthroughtheinletcheckvalves,fillingthespaceattheleftsideofthepistons.Onthepistondischargestroke,thewaterisforcedtotheoutletportthroughtheoutletvalves.Togetbetterlubricationforthebearings,thedrivemechanismofthepumpislubricatedwithoilandtheoilchamberattherightsideofthepistonsiskeptseparatefromthedisplacementsidebyusingdoublepackingsealsaroundeachofthesevenpistons.Therefore,bearingsandtheswashplate/slipperpadfrictionpairsarelubricatedwithoil.Thepiston/cylinderborefrictionpairsarelubricatedwithrawwater.Fig.1SchematicDiagramoftheSeawaterAxialPistonPumpWhenusingrawwateraslubricant,duetorawwaterschemicallyactivenature,lowviscosity,poorlubricationandhighvaporpressure,theselectionofmaterialsused,playakeyroleindetermininglonglifespanforawaterhydraulicpump.Thefrontandrearcasings,cylinderblockaremadeofaluminumalloywithanodizingtreatment,pistonsandcylinderlinersaremadeofstainlesssteel1Cr18Ni9TiandreinforcedpolymerorreinforcedpolymereterketonPEEK,respectively.ThesealsofinletandoutletvalvesaremadeofpolytetrafluoroethylenePTEFandthepoppetswithsoftsealsaremadeofbronzedstainlesssteel.Inordertoreducethewearonasurface,materialswithlowfrictioncoefficientmustbeused.relativelynewpolymer,PEEKshowsaverylowfrictioncoefficient,about0.02,incontacttosteelwithawaterfilm4.Thisfrictioncoefficientiscomparablewith0.050.07forsteeltosteelwithmineraloil.Recently,PEEK,hasturnedtobecommonlyusedforslidingpartsinwaterhydraulicpumpandmotor.Inordertoreducethewearonasurface,materialswithlowfrictioncoefficientmustbeused.Arelativelynewpolymer,PEEKshowsaverylowfrictioncoefficient,about0.02,incontacttosteelwithawaterfilm4.Thisfrictioncoefficientiscomparablewith0.050.07forsteeltosteelwithmineraloil.Recently,PEEK,hasturnedtobecommonlyusedforslidingpartsinwaterhydraulicpumpandmotor.1EXPERIMENTAL2.1TestapparatusInordertoexaminethefunctionsofthispump,anexperimentalstudyisinprogress.Thetestpumpisdrivenbyanelectricmotor.Tostudythefunctionsofthispumpatdifferentpumprotation,whichwascontrolledbyadjustmentsinelectriccabinet.Thereliefvalvecanbeusedtoprotectthesystem.Thethrottleisusedasloadingunitforthetestpump.Thecoolercontrolsthetemperatureofthesystem.Allhydrauliccomponentsweredesignedbyourselves.2.2ExperimentalmethodThetestmethodisdescribedasfollows.Eitherrawwaterpuretapwaterorseawaterimitationseawatercanbeusedaspressuremedium.TheimitationseawatercanbemadeupaccordingtothestandardASTMD21142252oftheUnitedStatesofAmericaThatthemainfeaturesofthetestsweredecidedasfollowsaTheloadingpressureshouldbeadjustedupto14MPa.bThespeedofrotationshouldbefullyvariableupto1000r/min.cAfterspeedreachesasteadystate,waterpressureandtheflowrateshouldberecorded.dThetemperatureoffluidmediumiscontrolledintherangeof2040e.2.3TestprocedureTheaimofthetestwastodeterminethevariationofvolumetricefficiency,forthepump,withpressureandspeed,aswellasthecurvesofthepumpinletvacuumversusflowrate.UsuallyVolumetricefficiencycanbeusedtodescribetheperformancesofapump.Itisdefinedas0QQ100℅WhereisvolumetricdfficiencyQisthedffective,averagedpumpdeliveryperunittime,L/minQ0isthetheoretical,averagedpumpdeliveryperunit

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