外文翻译--旋转泵.doc

外文资料翻译-1-Rotarypumps旋转泵Thesearebuiltinmanydifferentdesignsandareextremelypopularinmodernfluid-powersystem.Themostcommonrotary-pumpdesignsusedtodayarespur-gear,generated-rotary,sliding-vane,andscrewpump,eachtypehasadvantagesthatmakeitthemostsuitableforagivenapplication.旋转泵应用于不同的设计中，在流体动力系统中极其常用。今天最常用的旋转泵是外齿轮泵、内齿轮泵、摆线转子泵、滑动叶片泵和螺旋泵。每种类型的泵都有优点，适合于特定场合的应用。Spur-gearpumps.thesepumpshavetwomatinggearsareturnedinacloselyfittedcasing.Rotationofonegear,thedrivercausesthesecond,orfollowergear,toturn.thedrivingshaftisusuallyconnectedtotheuppergearofthepump.直齿齿轮泵，这种泵有两个啮合的齿轮在密封壳体内转动。第一个齿轮即主动轮的回转引起第二个齿轮即从动轮的回转。驱动轴通常连接到泵上面的齿轮上。Whenthepumpisfirststarted,rotationofgearsforcesairoutthecasingandintothedischargepipe.thisremovalofairfromthepumpcasingproducesapartialvacuumonthepumpinlet,herethefluidistrappedbetweentheteethoftheupperandlowergearsandthepumpcasing.continuedrotationofthegearsforcesthefluidoutofthepumpdischarge.当泵首次启动时，齿轮的旋转迫使空气离开壳体进入排油管。这种泵内空气运动使泵吸入口处形成了真空，于是外部油箱的液体在大气压的作用下，由泵的入口进入，聚集在上下齿轮和泵壳体之间，齿轮连续的旋转使液体流出泵的出口。Pressureriseinaspur-gearpumpisproducedbythesqueezingactiononthefluidaditisexpelledfrombetweenthemeshinggearteethandcasing,.avacuumisformedinthecavitybetweentheteethadunmesh,causingmorefluidtobedrawnintothepump,aspur-gearpumpisaconstant-displacementunit,itsdischargeisconstantatagivenshaftspeed.theonlywaythequantityoffluiddischargebyaspur-gearpumpoftypeinfigurecanberegulatedisbyvaryingtheshaftspeed.moderngearpumpsusedinfluid-powersystemsdeveloppressuresuptoabout3000psi.外文资料翻译-2-直齿齿轮泵的压力的升高是由挤压啮合齿轮和腔体内的液体产生的。当齿轮脱开啮合时，腔内形成真空，使更多的液体被吸入泵内。直齿齿轮泵是定排量的元件，当轴转速不变时，输出流量恒定。只有一种方法即改变输入轴的转速，能调节这种直齿齿轮泵的排量。现代应用在流体动力系统的齿轮泵的压力可达3000psi。Figureshowsthetypicalcharacteristiccurvesofaspur-gearrotarypump.Thesecurvesshowthecapacityandpowerinputforaspur-gearpumpatvariousspeeds.Atanygivenspeedthecapacitycharacteristicisnearlyaflatlinetheslightdecreaseincapacitywithriseindischargepressureiscausedbyincreasedleakageacrossthegearsfromthedischargetothesuctionsideofthepump.leakageingearpumpsissometimestermedslip.Slipalsoincreasewitharisepumpdischargepressure.thecurveshowingtherelationbetweenpumpdischargepressureandpumpcapacityisoftentermedthehead-capacityorHQcurve.therelationbetweenpowerinputandpumpcapacityisthepower-capacityorPQcurve.图示为直齿齿轮泵的典型特性曲线。这些曲线表明了泵在不同速度下的流量和输入功率。当速度给定时，流量曲线接近于一条水平的直线。泵的流量随出口压力的升高而稍有降低，这是由于泵的出油口到吸油口的齿轮径向泄漏所增加而造成的。渗漏有时定义为泄漏，泵出口压力的增加也会使泄漏增加。表征泵的出口压力和流量之间关系曲线常叫做水头流量曲线或泵的HQ曲线；泵的输入功率和泵流量关系曲线叫做功率流量特性曲线或PQ曲线。Powerinputtoasqur-gearpumpincreaseswithboththeoperatingspeedanddischargepressure.asthespeedofagearpumpisincreased.Itsdischargerateingallonsperminutealsorise.thusthehorsepowerinputatadischargepressureof120psiis5hpat200rpmandabout13hpat600rpm.thecorrespondingcapacitiesatthesespeedandpressureare40and95gpmrespectively,readonthe120psiordinatewhereitcrossesthe200-and600-rpmHQcurves.直齿齿轮泵的输入功率随输入速度和出口压力的增加而增加。随着齿轮泵速度的增加，流量（加仑/分）也增加。于是在出口压力为120psi，转速为200rpm时，输入功率是5马力。在转速为600rpm时，输入功率是13马力。纵坐标压力是120psi，横坐标是200rpm和600rpm时，在HQ曲线上可以读出相应的流量分别为40gpm和95gpm。外文资料翻译-3-Figureisbasedonspur-gearhandingafluidofconstantviscosity,astheviscosityofthefluidhandleincreases(i.e.,thefluidbecomesthickerandhasmoreresistancetoflow),thecapacityofagearpumpdecreases,thick,viscousfluidsmaylimitpumpcapacitythigherspeedsbecausethefluidcannotintothecasingrapidlyenoughfillitcompletely.figureshowstheeffectlfincreasedfluidbiscosityontheperformanceofrotarypumpinfluid-powersystem.at80-psidischargepressurethepphasacapacitylf220gpmwhenhandlingfluidof100SSUviscositylf500SSU.thepowerinputtothepumpalsorises,asshownbythepowercharacteristics.图示是直齿齿轮泵在粘度不变时的情况。随着流体粘度的增加（即流体变稠，不易流动），齿轮泵的流量降低。粘稠的流体在油泵高速运转时，因为这种流体在油泵中不能迅速进入泵体完全充满真空区，所以油流量受到限制。图示为在流体动力系统中流体粘度的增大对旋转泵工作情况的影响。当流体的粘度值为100SSU，出口压力为80psi时，泵流量为220gpm。当流体的粘度值为500SSU时，泵流量减少到150gpm。由功率特性曲线可知，泵输入功率也会增加。Capacitylfrotarypumpisoftenexpressedingallonsperrevolutionofthegearorotherinternalelement.iftheoutletofapositive-displacementrotarypumpiscompletelyclosed,thedischargepressurewillincreasetothepointwherethepumpdrivingmotorstallsorsomepartofthepumpcasingordischargepiperuptures.becausethisdangerofruptureexistssystemsarefilledwithapressurereliefvalve.Thisreliefvalvemaybebuiltasofthepumporitmaybemountedinthedischargepiping.可以用齿轮或其他内部元件每转一圈输出多少加仑来表示泵的流量。如果封闭定量泵的出口，则出口压力将会增加，直至驱动马达停止或泵内其他部分或排油管破裂。由于存在着破裂的危险，几乎所有的流体动力系统都安装压力溢流阀。这种溢流阀可安装在泵内，也可安装在排油管路。Sliding-VanePumps滑动式叶片泵Thesepumpshaveanumberofvaneswhicharefreetoslideintooroutofslotsinthepuprotor.whentherotoristurnedbythepumpdriver,centrifugalforce,springs,orpressurizedfluidcausesthevanestomoveoutwardintheirslotsandbearagainsttheinnerboreofthepumpcasingoragainstacamring.astherotorrevolves,外文资料翻译-4-fluidflowsinbetweenthevaneswhentheypassthesuctionport.Thisfluidiscarriedaroundthepumpcasinguntilthedischargeportisreached.Herethefluidisforcedoutofthecasingandintothedischargepipe.这些泵有大量的叶片，叶片能在转子的槽内自由的滑进滑出。当驱动转子时，离心力，弹簧或压力油使叶片伸出槽子，顶在泵壳体的内腔或凸轮环上。随着转子的旋转，叶片之间的流体经过吸油口时，完成吸油。流体顺着泵壳体到达排出口。在排出口，流体被排出，进入排油管。Inthesliding-vanepumpinFigurethevanesinanoval-shapedbore.Centrifugalforcestartsthevanesoutoftheirslotswhentherotorbeginsturning.Thevanesareheldoutbypressurewhichisbledintothecavitiesbehindthevanesfromadistributingringattheendofthevaneslots.SuctionisthroughtwoportsAandAI,placeddiametricallyoppositeeachother.Twodischargeportsaresimilarlyplaced.Thisarrangementofportskeepstherotorinhydraulicbalance,relivingthebearingofheavyloads.Whentherotorturnscounterclockwise,fluidfromthesuctionpipecomesintoportsAandAIistrappedbetweenthevanes,andiscarriedaroundanddischargedthroughportsBandBI.Pumpsofthisdesignarebuiltforpressuresupto2500psi.earliermodelsrequiredstagingtoattainpressu