外文翻譯--旋轉泵.doc

外文資料翻譯-1-Rotarypumps旋轉泵Thesearebuiltinmanydifferentdesignsandareextremelypopularinmodernfluid-powersystem.Themostcommonrotary-pumpdesignsusedtodayarespur-gear,generated-rotary,sliding-vane,andscrewpump,eachtypehasadvantagesthatmakeitthemostsuitableforagivenapplication.旋轉泵應用于不同的設計中，在流體動力系統(tǒng)中極其常用。今天最常用的旋轉泵是外齒輪泵、內齒輪泵、擺線轉子泵、滑動葉片泵和螺旋泵。每種類型的泵都有優(yōu)點，適合于特定場合的應用。Spur-gearpumps.thesepumpshavetwomatinggearsareturnedinacloselyfittedcasing.Rotationofonegear,thedrivercausesthesecond,orfollowergear,toturn.thedrivingshaftisusuallyconnectedtotheuppergearofthepump.直齒齒輪泵，這種泵有兩個嚙合的齒輪在密封殼體內轉動。第一個齒輪即主動輪的回轉引起第二個齒輪即從動輪的回轉。驅動軸通常連接到泵上面的齒輪上。Whenthepumpisfirststarted,rotationofgearsforcesairoutthecasingandintothedischargepipe.thisremovalofairfromthepumpcasingproducesapartialvacuumonthepumpinlet,herethefluidistrappedbetweentheteethoftheupperandlowergearsandthepumpcasing.continuedrotationofthegearsforcesthefluidoutofthepumpdischarge.當泵首次啟動時，齒輪的旋轉迫使空氣離開殼體進入排油管。這種泵內空氣運動使泵吸入口處形成了真空，于是外部油箱的液體在大氣壓的作用下，由泵的入口進入，聚集在上下齒輪和泵殼體之間，齒輪連續(xù)的旋轉使液體流出泵的出口。Pressureriseinaspur-gearpumpisproducedbythesqueezingactiononthefluidaditisexpelledfrombetweenthemeshinggearteethandcasing,.avacuumisformedinthecavitybetweentheteethadunmesh,causingmorefluidtobedrawnintothepump,aspur-gearpumpisaconstant-displacementunit,itsdischargeisconstantatagivenshaftspeed.theonlywaythequantityoffluiddischargebyaspur-gearpumpoftypeinfigurecanberegulatedisbyvaryingtheshaftspeed.moderngearpumpsusedinfluid-powersystemsdeveloppressuresuptoabout3000psi.外文資料翻譯-2-直齒齒輪泵的壓力的升高是由擠壓嚙合齒輪和腔體內的液體產(chǎn)生的。當齒輪脫開嚙合時，腔內形成真空，使更多的液體被吸入泵內。直齒齒輪泵是定排量的元件，當軸轉速不變時，輸出流量恒定。只有一種方法即改變輸入軸的轉速，能調節(jié)這種直齒齒輪泵的排量?，F(xiàn)代應用在流體動力系統(tǒng)的齒輪泵的壓力可達3000psi。Figureshowsthetypicalcharacteristiccurvesofaspur-gearrotarypump.Thesecurvesshowthecapacityandpowerinputforaspur-gearpumpatvariousspeeds.Atanygivenspeedthecapacitycharacteristicisnearlyaflatlinetheslightdecreaseincapacitywithriseindischargepressureiscausedbyincreasedleakageacrossthegearsfromthedischargetothesuctionsideofthepump.leakageingearpumpsissometimestermedslip.Slipalsoincreasewitharisepumpdischargepressure.thecurveshowingtherelationbetweenpumpdischargepressureandpumpcapacityisoftentermedthehead-capacityorHQcurve.therelationbetweenpowerinputandpumpcapacityisthepower-capacityorPQcurve.圖示為直齒齒輪泵的典型特性曲線。這些曲線表明了泵在不同速度下的流量和輸入功率。當速度給定時，流量曲線接近于一條水平的直線。泵的流量隨出口壓力的升高而稍有降低，這是由于泵的出油口到吸油口的齒輪徑向泄漏所增加而造成的。滲漏有時定義為泄漏，泵出口壓力的增加也會使泄漏增加。表征泵的出口壓力和流量之間關系曲線常叫做水頭流量曲線或泵的HQ曲線；泵的輸入功率和泵流量關系曲線叫做功率流量特性曲線或PQ曲線。Powerinputtoasqur-gearpumpincreaseswithboththeoperatingspeedanddischargepressure.asthespeedofagearpumpisincreased.Itsdischargerateingallonsperminutealsorise.thusthehorsepowerinputatadischargepressureof120psiis5hpat200rpmandabout13hpat600rpm.thecorrespondingcapacitiesatthesespeedandpressureare40and95gpmrespectively,readonthe120psiordinatewhereitcrossesthe200-and600-rpmHQcurves.直齒齒輪泵的輸入功率隨輸入速度和出口壓力的增加而增加。隨著齒輪泵速度的增加，流量（加侖/分）也增加。于是在出口壓力為120psi，轉速為200rpm時，輸入功率是5馬力。在轉速為600rpm時，輸入功率是13馬力。縱坐標壓力是120psi，橫坐標是200rpm和600rpm時，在HQ曲線上可以讀出相應的流量分別為40gpm和95gpm。外文資料翻譯-3-Figureisbasedonspur-gearhandingafluidofconstantviscosity,astheviscosityofthefluidhandleincreases(i.e.,thefluidbecomesthickerandhasmoreresistancetoflow),thecapacityofagearpumpdecreases,thick,viscousfluidsmaylimitpumpcapacitythigherspeedsbecausethefluidcannotintothecasingrapidlyenoughfillitcompletely.figureshowstheeffectlfincreasedfluidbiscosityontheperformanceofrotarypumpinfluid-powersystem.at80-psidischargepressurethepphasacapacitylf220gpmwhenhandlingfluidof100SSUviscositylf500SSU.thepowerinputtothepumpalsorises,asshownbythepowercharacteristics.圖示是直齒齒輪泵在粘度不變時的情況。隨著流體粘度的增加（即流體變稠，不易流動），齒輪泵的流量降低。粘稠的流體在油泵高速運轉時，因為這種流體在油泵中不能迅速進入泵體完全充滿真空區(qū)，所以油流量受到限制。圖示為在流體動力系統(tǒng)中流體粘度的增大對旋轉泵工作情況的影響。當流體的粘度值為100SSU，出口壓力為80psi時，泵流量為220gpm。當流體的粘度值為500SSU時，泵流量減少到150gpm。由功率特性曲線可知，泵輸入功率也會增加。Capacitylfrotarypumpisoftenexpressedingallonsperrevolutionofthegearorotherinternalelement.iftheoutletofapositive-displacementrotarypumpiscompletelyclosed,thedischargepressurewillincreasetothepointwherethepumpdrivingmotorstallsorsomepartofthepumpcasingordischargepiperuptures.becausethisdangerofruptureexistssystemsarefilledwithapressurereliefvalve.Thisreliefvalvemaybebuiltasofthepumporitmaybemountedinthedischargepiping.可以用齒輪或其他內部元件每轉一圈輸出多少加侖來表示泵的流量。如果封閉定量泵的出口，則出口壓力將會增加，直至驅動馬達停止或泵內其他部分或排油管破裂。由于存在著破裂的危險，幾乎所有的流體動力系統(tǒng)都安裝壓力溢流閥。這種溢流閥可安裝在泵內，也可安裝在排油管路。Sliding-VanePumps滑動式葉片泵Thesepumpshaveanumberofvaneswhicharefreetoslideintooroutofslotsinthepuprotor.whentherotoristurnedbythepumpdriver,centrifugalforce,springs,orpressurizedfluidcausesthevanestomoveoutwardintheirslotsandbearagainsttheinnerboreofthepumpcasingoragainstacamring.astherotorrevolves,外文資料翻譯-4-fluidflowsinbetweenthevaneswhentheypassthesuctionport.Thisfluidiscarriedaroundthepumpcasinguntilthedischargeportisreached.Herethefluidisforcedoutofthecasingandintothedischargepipe.這些泵有大量的葉片，葉片能在轉子的槽內自由的滑進滑出。當驅動轉子時，離心力，彈簧或壓力油使葉片伸出槽子，頂在泵殼體的內腔或凸輪環(huán)上。隨著轉子的旋轉，葉片之間的流體經(jīng)過吸油口時，完成吸油。流體順著泵殼體到達排出口。在排出口，流體被排出，進入排油管。Inthesliding-vanepumpinFigurethevanesinanoval-shapedbore.Centrifugalforcestartsthevanesoutoftheirslotswhentherotorbeginsturning.Thevanesareheldoutbypressurewhichisbledintothecavitiesbehindthevanesfromadistributingringattheendofthevaneslots.SuctionisthroughtwoportsAandAI,placeddiametricallyoppositeeachother.Twodischargeportsaresimilarlyplaced.Thisarrangementofportskeepstherotorinhydraulicbalance,relivingthebearingofheavyloads.Whentherotorturnscounterclockwise,fluidfromthesuctionpipecomesintoportsAandAIistrappedbetweenthevanes,andiscarriedaroundanddischargedthroughportsBandBI.Pumpsofthisdesignarebuiltforpressuresupto2500psi.earliermodelsrequiredstagingtoattainpressu