文献翻译液压系统Word文档格式.docx
- 文档编号:21588041
- 上传时间:2023-01-31
- 格式:DOCX
- 页数:12
- 大小:31.97KB
文献翻译液压系统Word文档格式.docx
《文献翻译液压系统Word文档格式.docx》由会员分享,可在线阅读,更多相关《文献翻译液压系统Word文档格式.docx(12页珍藏版)》请在冰豆网上搜索。
HYDRAULICSYSTEM
Hydraulicsystemsarepower-transmittingassembliesemployingpressurizedliquidtotransmitenergyfromanenergy-generatingsourcetoanenergy-usearea.AllhydraulicsystemsdependonPascal’slaw,namedafterBlaisePascal,whodiscoveredthelaw.Thislawstatesthatpressurizedfluidwithinaclosedcontainer-suchascylinderorpipe-exertsequalforceonallofthesurfacesofthecontainer.
Inactualhydraulicsystems,Pascal’slawdefinesthebasisoftheresultswhichareobtainedfromthesystem.Thus,apumpmovestheliquidinthesystem.Theintakeofthepumpsconnectedtoaliquidsource,usuallycalledthetankorreservoir.Atmosphericpressure,pressingontheliquidinthereservoir,forcestheliquidintothepump.Whenthepumpoperates,itforcesliquidfromthetankintothedischargepipeatasuitablepressure.
Theflowofthepressurizedliquiddischargedbythepumpiscontrolledbyvalves.Threecontrolfunctionsareusedinmosthydraulicsystems:
(1)controloftheliquidpressure,
(2)controloftheliquidflowrate,and(3)controlofthedirectionofflowoftheliquid.
Theliquiddischargedbythepumpinafluid-powersystemisdirectedbyvalvestoahydraulicmotor.Ahydraulicmotordevelopsrotaryforceandmotion,usingthepressurizedliquidasitsenergysource.Manyhydraulicmotorsaresimilartopumps,exceptthatthemotoroperatesinareversemannerfromapump.
Wherelinearinsteadofrotarymotionisdesired,acylindricaltubefittedwithamovablepiston,calledahydrauliccylinder,isoftenused.Whenthepistonismovedbythepressurizedfluid,thepistonrodimpartsaforceormovesanobjectthroughadesireddistance.
Restrictingthemovementofthepistoninahydrauliccylinder,aswhenthepistoncarriesaload,createsaspecificpressurerelationshipwithinthecylinder.Thesurfaceareaofthepistonfaceissaidtocontainaspecificnumberofsquareinches.Thepressureofthepressurizedliquid,multipliedbythepitonarea,producesanoutputforce,measuredinpound,attheendofthepistonrod.
Thespeedofmovementofthepistonroddependsonhowfastthepressurizedfluidentersthecylinder.Flowintothecylindercanbedirectedtoeitherend,producingeitherapushingorpullingforceatthepistonrodend.Asealaroundtherodwhereitpassesthroughthecylinderendpreventsleakageoftheliquid.
Directionalcontrolofthepistondependsonwhichendofcylindertheliquidenters.Aspressurizedliquidentersoneendofthecylinder,liquidmustbedrainedfromtheotherend.Thedrainedliquidisledbacktothereservoir.Inapneumaticsystemusingair,theairintheexhaustingendofthecylinderisventedtotheatmosphere.
Directional-controlvalves,alsocalledtwo-way,three-way,four-way,etc.,arenamedinaccordancewiththeirbasicfunction.Pressure-controlandsimplerestrictorvalvesareusuallytwo-wayvalves.TheyprovideONorOFFservice.Athree-wayvalvesmayperformseveralfunctions,allassociatedwiththethree-portsinthevalve.Forexample,thepowerorpressurizedliquidfromapumpinatractormaybesenttothehydraulicsystemservingthetractor’sfront-endloader.Orthethree-wayvalvemaysendthepressurizedliquidtoahydraulicmotordrivingafeedconveyorwhilethefront-endloaderisnotbeingused.
Three-wayvalvesmayalsobeusedtodirectpressurizedfluidtoasingle-actinghydrauliccylinder.Asthethree-wayvalveisactuated(operated)itcanstopthepressurizedflowtothecylinder.Further,thesamevalvecandivertliquidfromthecylindertothereservoir,sothecylindercanretractbygravityorreturnspringsandassumeitsoriginalposition.
Afour-wayvalvehasfourportsoropenings.Thepressureportdirectsfluidflowtoanareawherepressurizedliquidisdesired.Oneoftheotherportscansimultaneouslydrainliquidfromapressurizedarea.Thedramliquidcanbedirectedtothereservoir.
Inafluid-powersystem,themovementofpressurizedfluidresemblestheactionofelectriccurrentinanelectricalsystem.Insuchasystem,electricalenergyiscontinuallymovingwhenworkisbeingdone.Thesameistrueofafluid-powersystem.
Inadirect-currentelectricalsystem,thespeedofadeviceisvariedbychangingtheflowofcurrenttothedevice.Alternating-currentsystem,usephaseshiftingtoattainsimilarspeedcontrol.Hydraulicsystemcanobtaininfinitespeedvariationsbyseveralmethodsofcontrol,Pneumaticsystems,becauseofthespringinessofthegas,haverelativelycrudespeedcontrol.
Influid-powersystems,thepumpcanbedesignedsothedischargeflowofthepressurizedliquidcanbevariedbymanipulatingthepumpmechanism,givingvaryingspeedsofthehydraulicmotororotheroutputdevice.Arestrictionunthepumpoutletcanlimitthefluidinamannersimilartothatusedinadirect-currentelectricalsystem.Wheredesired,hydraulicsystemscanbedesignedtousevalveswhichdivertflowtodifferentflowchannelstogivethedesiredspeedcontrol.
Thecompressibilityofhydraulicfluidisslight.But,ifdesired,thisslightcompressibilitycanbeusedtoabsorbsmall,erraticmachinemovementswhichcausepressurevariationsinafluid-powersystem.Pneumaticsystemshavethiscapabilityinherentlybecauseofthespringinessoftheairorgasusedinthesystem.Hydraulicsystemsmayuseoneormoreaccumulators-deviceswhichcontainpressurizedgaswhichcanaccommodaterapidpressurechangesinthefluidportionofthesystem.
Gravity,springsandcompressedgasesprovidepotentialenergyImanyhydraulicsystems.Thus,gravityassistisoftenusedtoreturnaparttoitsoriginalpositionwithouttheuseofpowerfromthehydraulicsystem.Thistypeofassistancealsosimplifiesthepartsinthehydraulicsystem.
PumpsMechanicalsealMeasures.Atpresentthemechanicalsealinpumpsinakindofproducttheapplicationextremelywidespread,butandwillsavetheenergyalongwiththeproducttechnicallevelenhancementtherequest,themechanicalsealapplicationprospectismorewidespread.Themechanicalsealsealeffectdirectlywillaffecttheentiremachinemovement,inparticularinpetroleumchemicalindustrydomain,becausewillexistflammable,explosive,iseasytovolatilize,tobeviolentlypoisonousandsoonthemedium.
Themechanicalsealappearswilldivulge,seriouslywillaffecttheproductionnormallytocarryon,isseriousalsoappearsthesignificantsecurityaccident.Peoplewhenanalysisqualitybreakdownreason,oftenisfamiliarwithinthemechanicalsealownaspectsearchesthereason,forexample:
Mechanicalsealshapingwhetherappropriate,choiceofmaterialwhethercorrect,thepackingsurfacecomparedtopresseswhethercorrectly,rubsthevice-choiceiswhetherreasonableandsoon.Butisshortverymuchinthemechanicalsealexternalconditionaspectsearchesthereason,forexample:
Pumpsforthemechanicalsealcreationconditionwhetherappropriate,theservosystemdispositioniswhetherappropriate,buttheseaspectsreasonsoftenarecountformuch.
Thisarticleauthorfrompumpedhasanalyzedthereasonablemeasurewiththemechanicalsealexternalconditionanglewhichtheinfluencesealeffectseveralkindoffactorsandshouldadopt.1Principleandrequestthatmachinerysealsoff:
ThemechanicalsealisdependsonapairofrelativemotionlinkendsurfaceA(fixed,anotherrevolvestogetherwithaxis)themutualfittingformsthesmallaxialplayplaysthesealrole,thiskindofequipmentiscalledthemechanicalseal.Themechanicalsealusuallybymovesthelink,thestaticlink,contractsthepartandthesealpartiscomposed.Movesthelinkandthestaticlinkendsurfacecomposesapairtorub,movesthelinktodependoninthesealedchambertheliquidpressuretocauseitsshoulderuponthestaticlinkendsurface,andproducesontwolinksendsurfacessuitablecomparedtopressesandmaintainsanextremelythinliquidmembranetoachievethesealthegoal.Contractsthepartpressurize,maycausetopumpundertheoperatingcondition,alsomaintainstheendsurfacefitting,guaranteedthesealmediumnothingmorethanleaks,andpreventedtheimpurityenterssealstheendsurface.SealstheparttoplaythesealtomovethelinkandaxisgapB,thestaticlinkandtheglandgapCrole,simultaneouslytothevibrationwhichpumps,attacksthecushioningeffect.Themechanicalsealintheactualmovementisnotanisolatedpart,itiswithothersparepartswhichpumpscombinesthemovementtogether,simultaneouslymayseethroughitsbasicprinciple,themechanicalsealnormaloperationhasthecondition,forinstance:
Otherwisefleeingmeasuresapumpspindle'
sbeingnotabletoverybig,frictionsubsidiaryendfacecannotformtheratiopressuredemandingregularly;
Thepumpspindlethatmachineryhermeticsealinggetsalongcannothaveboundaryverybigdeflection,endfacewaitsaminuteotherwisethanpressurewillbeuneven.Besidesonlywhensatisfyingsimilarsuchexternalcondition,finemachinerysealsoffoneselffunction,abilityreachesidealhermeticsealingeffect.2Analysisofcausesthatexternalconditionaffects:
Pumpspindleaxialtofleeingismeasuredbig:
Thehermeticsealingthatmachinerysealsoffneedstohavecertainratiopressurefacetoface,suchabilityplaysarriveathermeticsealingrole,berequiringthatspringthatmachinerysealsoffneedstohavecertaincompressionamountsrightnow,giveapropulsiveforcesealingoffendface,rotatingmakeshermeticsealingproducethepressuresealingoffthewhatbedemandedratiofacetoface.Forensuringthatthisoneiscomparedtopressure,theamountsmachineryissealedoffrequiringthatthepumpspindlecan
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 文献 翻译 液压 系统
![提示](https://static.bdocx.com/images/bang_tan.gif)