利用被困体积提高轴向柱塞泵的容积效率

1、附件1:外文资料翻译译文利用被困体积提高轴向柱塞泵的容积效率研究分析结果显示，标准配流盘设计因为有不受控制地膨胀和压缩的流体发生经过插槽本身而产生一种容积损失。通过去除这些插槽同时采用被困容积式，真正起到改善柱塞泵的容积效率的结果。虽然目的并不在于研究适合所有柱塞泵的理想配流盘设计，但是该报告的确在被困容积的应用方面提供了理论依据，并且也对解决配流盘的整体设计中的问题进行了进一步的探索。柱塞泵的工作和受力在这一节中，推导出了和轴向柱塞泵操纵效率有尖的方程。注意：这里的效率在通篇中仅指和流体压缩损失有为的效率。这次分析由泵的单一柱塞的机械和液压力图表展开。利用该图表，分析计算了作用在柱塞上的机械

2、力和作用在泵排油区一液体单元的液压力。通过输出功率和输入功率的比值，推导出了泵的瞬时功率的表达式。该表达式表明，为了计算泵的效率，必须考虑到必须的动力学、柱塞腔内的压力和流入流出柱塞腔的体积。这些数值来源于本文接下来的章节中。N个柱塞X周正方向的力Fn。这个力是由于斜盘对滑靴的反作用力而使柱塞挤入。同理，在柱塞排油的一腔流体上也作用了一压力Pn。该压力驱使流体流出腔体或被认为是流体的排出力。把输入的机械力Fn转换为输出的液压力Pn,是该柱塞泵的工作的基础。液压力容积流量说明瞬时流线从第n个腔流出混入泵的排油腔。用Q0表示泵的众多容积流量网合成系统的排油。每个柱塞腔的压力是各不相同的，但是泵排油

3、区一条流线上的压力是一个常数Pd。液压系统排油区的压力为P0。在以下的分析中，我们来考虑一个流体单元遨个单元是封闭的从而可以代表第n个柱塞腔到系统排油区的流线。液压力(PnPo)An作用于此单元，这里Pn是第n个柱塞腔的压力，Po是系统排油腔的压力，An是代表着从第n个柱塞腔流出的流线的流体单元的瞬时横截面。曲&均怅潴展,胤藏姬里劈fl,施谄勒豌腐或和地位曲魁和荷槽。AZIntakePortDischargePortFig.5Trapped-volumevalveplatedesign（intakepom吸入口dischargepom排出口kidney-shapedflowpassag

4、efromasinglepistonchamber:从单个柱塞腔引出来的贤脏形状的流道）和图4同理，图5同样给出了从单个柱塞腔引出来的肾脏形状的流道配合着配流盘上的弓形门状几何体。当流道向07=72位置移动是，事实上流道逐渐被此区域内的门状几何体所阻断。当柱塞腔正好位于顶死点时，柱塞腔是尖闭的没有流体的流进和流出。如图5所示，当柱塞向配流盘吸油区移动时这种封闭的情况依然存在。在这种封闭的状况下，柱塞腔内的流体被困住，所以叫做被困容积泵的设计。封闭区域的角度尺寸用1表示。在这种设计中，压力的转变并不是靠配流盘上的卸荷槽来实现的，而是单独靠受控体积在柱塞腔内的体积膨胀来完成的。穿过封闭区时，柱塞腔

5、立刻与吸油区联通，流体从泵的吸油区流入柱塞腔。当&n=3/r/2柱塞腔靠近最底线时，也会有同样的状况。在此区域内柱塞从吸油区移动到排油区，其封闭的角度尺寸用£b表示。在这个位置压力的转变由柱塞腔内受控体积的压缩来完（图 6 piston pressures:活塞压强equation:方程式 angular position:有角的位置）471137114Angular Position. Q.628125125o.ooFig.7Pistondischargeflows（pistondischargeflows:活塞流体流动）图5也在事实上考虑了柱塞泵中单一个柱塞腔的四个不同的

6、区域的压力和流动分总结图6用这种泵的设计理论作为知道思想，把压力方程(27)和压力方程(36)做了比较。同样的道理，把流体流动方程(28)和(37)做对比，我们还能得到图7。如图6所示被困体积泵的设计中压力转变相对于标准柱塞泵的设计中的压力转变而言，有很大程度的滞后。从图7可以看出，在配流盘压力转变区域内，标准柱塞泵设计中的容积流动受到了很大的阻力。这种流体流动的阻力是由于在柱塞腔的最低点和最顶点流体受到了不受控制的膨胀和压缩而造成的。在最低点附近的不受控制的压缩对柱塞泵产生了很不利的功率损失。讨论因为以前的结果都是随时间变化的，为了出个方法解决这个问题，我们必须为每次压力转变的操作而设计一种

7、新的配流盘的设计理念。图8显示了随着压力操纵的改变，柱塞泵配流盘的设计也跟着改变，同时附表给出了基本柱塞泵参数的变化。方程(40)和方程(43)分别描述了普通柱塞泵设计和被困体积柱塞泵设计的功率损失。用附录中的参数，我们把这些方程描述在了图9中。就如图9所示，相对于被困体积泵设计的功率损失而言，普通泵设计的功率损失要人。这种结果可以用配流盘上的插槽来解释。读者也许会记得，这些插槽分担了部分流体容积的流动，用来协调在最底部和最顶部压力跃迁的变化的。在最底线那里，当柱塞进入排油口时，流体经过配流盘上的插槽进入柱塞腔内直到柱塞腔内的压力等于柱塞泵排油区的压力。为了使得这些压力相等，柱塞腔内的流体受到

8、了压缩，结果，一部分能量加到了柱塞腔的体积上。在最顶部，配流盘上的插槽是用来缓解在最底部被压缩的流体体积的。这种流体的缓解或者说是流体的膨胀导致通过插槽的流体流动释放了储存在流体中的能量。这些被释放出来的能量因为柱塞泵吸油口的压力是一个恒定的压力源而永远也不能收回。另一方面，被困体积柱塞泵的(PE 5U.2SUUU1OJB设计中不用为了在最底部和最顶部得到平稳的压力转变而开设插槽，所以流体中的能量不会以某种耗费能量的方式被储存和释放掉。（图8改变门状儿何面积作为压力转变的操作）OperatingPressure.V(MPagig.8Changingvalve-platedimensionsas

9、afunctionofoperatingpressureLOOOperatingPressure,APMPaFig.9Aplotofthepower-lossequations（图9功率损失方程式）在被困体积的情况下，在最底线部位能量由于柱塞腔体积自身的机械变化而自动的补充到流体上。同样的道理，从流体中释放出来的能量也因为柱塞腔容积体积的改变而被自OperatingPressure,APMPaFiq.10Aplotoftheefficiencyequations（图10容积效率方程式）但是，在这两种设计中能量都在柱塞泵的排油区和被考虑等于柱塞泵的吸油区的压力的液压系统的舱室的交界面上有了损失。

10、这中能量损失在方程（43）中被计算到了总的能量损失中，产生它的原因就在与当流体在经过柱塞泵排油区和液压系统舱室时，不受控制的膨胀造成的。方程(41)和方程(44)分别描述了普通柱塞泵设计和被困柱塞泵设计中的容积效率。利用附录中的参数，这两个方程被描述在了图10中。如图10所以，被困体积柱塞泵的设计比普通柱塞泵的设计更有效。造成这样的结果再一次说明了两种设计中不同的能量损失特征。按照柱塞泵的设计和操纵压力，这种效率的提高可以达到。从分析结果中可以得到N。提高了，使用被困体积设计柱塞泵的优势更加明显。结论这篇报告试图说明一台柱塞泵的功率损失和效率可以通过改变配流盘通道的几何尺寸来得到提高。特别是，

11、这次研究对比了具有恒定面积卸荷槽的配流盘设计和在卸荷槽位置改用被困体积的流体压缩的容积损失。在这次研究中，带有卸荷槽的配流盘因为流体通过最底部和最顶部是的不受控制的膨胀而产生了损失。另一方面，具有被困体积设计的配流盘设计可以吸收流体从压缩到释放时的能量。所以，被困体积柱塞泵设计比应用了卸荷槽的普通柱塞泵设计更为有效。附录4j=16.0E-06m2=789.2E-06m2Cd=0.62N=9=35.0E+06PaP/=5.0E+06Par=67.3E-03m14=43.6E-06ina=0.244rad3=1.2E+09Pap=850kg/m3CO=188.5rad/s专业名词和术语Ab,(配流

12、盘最顶部和最底部卸荷槽的恒定面积An包含第n个柱塞流线的流体单元的横截面积Ap单个柱塞的有效压力面积Cd柱塞腔外泄系数Fn作用在第n个柱塞x轴方向的机械力MP单个柱塞的质量N柱塞泵中的柱塞数目瞬时连接到泵的排油区的柱塞的数目n柱塞编号Pb单个柱塞腔外的界限压力Pd泵的排油压力Pt泵的吸入压力Pn第n个柱塞腔的流体压力Po液压系统排油区的流体压力Qn流出第n个柱塞腔容积流动速率Qo流入液压系统的容积流动速率r柱塞节圆半径sn沿着第n个柱塞腔流线的坐标t时间1/无标注尺寸的柱塞体积Vb,t顶部和底部的柱塞腔的体积Vn第n个柱塞腔的瞬时体积Vo单个柱塞腔的名义体积w一般意义上的功Xn第n个柱塞滑靴球

13、连接在x轴上的位置a旋转斜盘的角度B流体体积模数fbt配流盘底部顶部卸荷槽的弧度值柱塞泵的效率。第n个柱塞的角度位置Kgbt一般性的流动效率配流盘底部顶部被困体积的弧度值n一般性的功率代号p流体密度附件2:外文诂文肾型孔的角度尺寸F人泵的旋转角速度TheexploitationsurroundsaphysicalvolumeexaltationstalktofillthecapacityefficiencyofpumptowardthepillarIntheanalyticalresultofthispaper,itmaybeshownthatthestandardvalve-platedes

14、ignintroducesavolumetriclosswhichmaybeaccountedforbytheuncontrolledexpansionandcompressionofthefluidthatoccursthroughtheslotsthemselves.Byeliminatingtheseslots,andutilizingatrappedvolumedesign.itmaybeshownthatimprovementsintheoperatingefficiencycanbeachievedThoughthispaperdoesnotclaimtoprovidetheide

15、alvalve-platedesignforallpumpapplications,itdoesprovidethetheoreticalreasonforutilizingtrappedvolumesandlendsgeneralinsightintotheoverallproblemofvalve-platedesign.PumpWorkandPowerInthissection,theequationsthatgoverntheoperatingefficiencyoftheaxial-pistonpumparederivedNote:throughoutthisresearch,the

16、wordefficiencywillreferonlytotheefficiencythatisassociatedwiththecompressibilitylossesofthefluidThisanalysisbeginsbyexaminingadiagramofmechanicalandfluidconditionsthatexistwithinthepumpforasinglepiston.Usingthisdiagram,themechanicalworkthatisexertedonthepiston.andthehydraulicworkthatisexertedonaflui

17、dcolumnwithinthedischargechamberofthepump,areconsideredBytakingtheratioofoutputpowertoinputpower,aninstantaneousexpressionfortheefficiencyofthepumpisderivedFromthisexpression,itisshownthatthekinematicsofthepiston,thepressurewithinthepistonchamber,andthevolumetricflowinandoutofthepistonchambermustbed

18、eterminedforthepurposesofevaluatingtheefficiencyofthepumpThesequantitiesarederivedinsubsequentsectionsofthispaper.adiagramofmechanicalandfluidconditionsthatexistforasinglepistonasitoperateswithinthepump.Inthisfigurejtisshownthatthenthpistonisacteduponbyaforce,/v?5whichisshowntodrivethepistoninthepos

19、itivex-direction.ThisforceistheinputtothepistonwhichisgeneratedbytheslippeAsreactionagajnsttheswashplateSimilarly,thefluidatthedischargeofthepistonchamberisacteduponbythepressurewithinthenthpistonchamberitself,PnThispressuretendstoforcethefluidoutofthechamberandmaybeconsideredastheforcinginputtothef

20、luid.Theprocessofconvertingthemechanicalinput,/T74oahydraulicinput,Pn,sthefundamentaloperatingtaskofthepumpHydraulicPower.rhowever,thebottompistonisshowntobethenthpistonwhichimpliesthatthenumberofpistonswithinthepumpisgeneralized.thediagramofvolumetricflowillustratestheinstantaneousstreamlineofflowt

21、hatisejectedfromthenthpistonchamberintothedischargechamberofthepumpThenetvolumetricflowfromthepumpdischarge-chamberintothehydraulicsystemdischarge-chamberisgivenbyQothediagramoffluidpressureillustratesthatthepressurewithineachpistonchamberisgenerallydifferent;but,thatthefluidpressurealongthestreamli

22、neswithinthepumpdischarge-chamberisessentiallyaconstantwhichisgivenby,PdThepressurewithinthedischargechamberofthehydraulicsystemisgivenbytheconstantpressure,Pojntheanalysiswhichfollows,acolumnoffluidwithinthedischargechamberofthepumpwillbeconsideredThiscolumnoffluidwillbechosensothatitwillcontainthe

23、streamlinesofflowfromthenthpistonchambertothedischargechamberofthehydraulicsystemThehydraulicforceexertedonthiscolumnoffluidisgivenby,(Pn2Po)AntNexePnisthepressurewithinthenthpistonchamber,Poisthepressurewithinthedischargechamberofthehydraulicsystem,andAnistheinstantaneouscross-sectionalareaofthecol

24、umnoffluidwhichcontainsthestreamlinesofflowfromthenthpistonchamber.Trapped-VolumePumpDesign.Figure5showsaschematicofamodifiedvalve-platewhichhaseliminatedtheslotsneartopandbottomdead-centersSimilartoFig.4,Fig.5showsakidneyshapedflowpassagefromasinglepistonchamberwhichmatchesthearcuateportinggeometry

25、ofthevalveplateAsthisflowpassagemovestowardun5P%theactualflowpassageisgraduallycutoffduetotheterminatingport-geometryofthevalveplateinthisregionWhenthepistonreachesthispoint,thepistonchamberiscompletelyclosedoffandflowcannotbedischargedorreceivedbythepistonchamber.AsshowninFig.5/theclosedportingcond

26、itioncontinuestoexistasthepistonmovestowardtheintakeportofthevalveplateInthisclosed-portingcondition.thefluidwithinthepistonchamberistrappedandthusitiscalledatrapped-volumepumpdesignTheangulardistanceofthisclosedportingisgivenbythedimension,ztWiththisdesign,thepressuretransitionisaccomplished,notbyv

27、alve-plateslotting,butbythecontrolledvolumetricexpansionofthepistonchamberaloneOncethepistonchambercrossestheclosed-portingzone,itquicklyopensuptotheintakeportandbeginstoreceivefluidfromtheintakesideofthepumpAsimilarsetofconditionsexistswhenthepistonchamberisnearbottomdeadcenterwhenun53p/2.Inthisreg

28、ion,thepistonismovingfromtheintakeportintothedischargeportandtheangulardimensionoftheclosed-portingzoneisgivenby,zbInthislocation,thepressuretransitionisaccomplishedbythecontrolledvolumetriccompressionofthepistonchamber.Again,thevalveplateshowninFig.5provides,essentially,fourdifferentregionstobecons

29、ideredinthepressureandflowanalysisforasinglepiston-chamberwithinthepumpTable2Trapped-volumevalueslateregionsRegionAngularPositionPressureConditionsFlowConditionsThepressurewithinthepistonchamberisatdischargepressure.ThedischargeflowisequaltothedisplacementoftheThepressurewithinthepistonchamberisbetw

30、eenintakepressureanddischargepressure.Thevalve-plateportingisclosedoffandthedischargeflowiszeroThepressurewithinthepistonchamberisatintakepressure.Theintakeflowisequaltothedisplacementofthepiston.Thepressurewithinthepistonchamberisbetweenintakepressureanddischargepressure.Thevalve-plateportingisclos

31、edoffandtheintaketlowiszero.WithinRegions1and3,thepressureisapproximatedasaconstant.eitherPdorP/9andthevolumetricflowrateisgivenbythenegativeofthevolumetrictimerate-of-changeofthepistonchamberitself,2V9n5Aprtan(a)vcos(un).InRegions2and4,thepressureischangingasafunctionofu/7andthereforesomeanalysisis

32、requiredtoapproximatethepressurecharacteristicswithintheseregions.InRegion2ofthevalveplate,theportingisclosedoffandvolumetricflowinandoutofthepistonchamberisnolongerpossibleInthiscase,thetimerate-of-changeofthefluidpressurewithinthenthpistonchamberisgivenbydPndt52bVndVndt,(29)whereVnistheinstantaneo

33、usvolumeofthenihpistonchamber.Byeliminatingc/fromthedenominatorofbothsidesofthisequation,thefollowingseparabledifferential-equationwithitsappropriateboundsofintegrationmaybewrittenEPdPndPn52bEVtVn1VndVn,(30)whereVtisthevolumeinthenthpistonchamberwhenun5p/2ThesolutiontothisequationisgivenbyPn5Pd2bInS

34、VnVtD'Pd2bSVnVt2lD,(31)whereVnisgiveninEq.16!andVt5Vo2Aprtan(a)UsingtheseresultsyieldsthefollowingsimplifiedexpressionforthepressurewithinthenthpistonchamberasthepistonpassesthroughRegion2ofthevalveplate:Pn5Pd2bS12sinun!V2lD,(32)whereV-5VoZ4prtan(a).Note:isalwaysgreaterthanunity.WithinRegion2oft

35、hevalveplateQn50.Toinsurethattheclosed-portingzoneonthevalveplateisdesignedsufficiently,itisimportanttonotethatwhenun5p/2z(thepressurewithinthepistonchambershouldequaltheintakepressure,PLThismeansthattheclosed-portingzoneonthevalve-platehaseffectivelyfacilitatedafullpressuretransitionfromthedischarg

36、epressure,Pd,totheintakepressurePj-Bysetting丹equalto/A.andu77equaltop/21z&Eq32!maybesolvedtodeterminetheproperlengthoftheclosed-portingzoneonthevalve-plate.Thisresultisgivenbyzt5cos21S12Pd2Pib-V-2!D.(33)SimilaranalysiscanbedoneforRegion4wherethepressuretransitionbeingachievedisbetweentheintakepr

37、essure,/Aandthedischargepressure,Pdnthisregion,thepressurewithintenthpistonchamberisgivenbyPn5PilbSllsinu(34)Again,withinRegion4ofthevalveplate,Qn50.Itcanbeshownthattheappropriateclosed-portinglengthinRegion4isgivenbyzb5cos21S12Pd2Pib-V-1WD.(35)Tosummarizetheapproximatepressureresultsofthissection,t

38、hefollowingpiecewiseequationispresentedfortheinstantaneouspressurewithinthenthpistonchamber:Pn5!Pdzb2P2,un.p2Pd2bS12sinun!V21Dp2,unp21ztPip2zt,un,3p2PilbSllsinun!VHD3p2jun,3p21zb.(36)Theapproximatevolumetricflowresultsofthissectionmaybesummarizedusingthefollowingpiecewiseequationfortheinstantaneousd

39、ischarge-flowfromthenthpistonchamber:tana!vcosun!z6Aun»p20p2,un,p21ztAprXan-a!vcosun!p21zr,u/i,u/?,3p21z/?.(37)SummaryUsingthepumpdesigninformationintheAppendix,Fig6hasbeengeneratedforthepurposeofcomparingthepressureequations27!and36!.Similarly,Fig.7hasbeengeneratedforthepurposeofcomparingthefl

40、owequations28!and37!.AsshowninFig.6,thepressuretransitionofthetrappedvolumedesignsignificantlylagsthepressuretransitionofthestandarddesignFromFig.7,itcanbeseenthatthevolumetricflowofthestandarddesignexperiencessignificantspikesinthetransitionregionsofthevalveplateTheflowspikesofthestandarddesignresu

41、ltfromtheuncontrolledexpansionandcompressionofthefluidattopandbottomdeadcentersAtbottomdeadcenter,theuncontrolledcompressionofthefluidcausesanundesirablepowerlossforthepumpStandardPumpDesign.SubstitutingtheresultsofEqs13!,27!,and28!intoEqs.10!and12!yieldsthefollowingresultsfortheoutputandinputpowero

42、fthestandardpumpdesign:PoA/5Pidea/Hcos2SjD2DPbV11!4J,(38)P-/n5P/dea/H12cos-jt!jt2772cosjb/b22DPb-V21!4J.wheretheidealpowertransmissionofthepumpisgivenbyPidea/5NAprvtan-a!DPp.(39)lntheseequations,DP5Pd2PiSubtractingtheoutputpowerfromtheinputpoweryieldsthepowerlossofthestandardpumpdesign.Thisresultisg

43、ivenbyP-oss5Pidea/H!2cos八jt!jt212cos-Ajb!jb22cos2Sjb2DIDPbl2J.(40)Theefficiencyofthestandardpumpdesignisgivenbyh5P-oufP-in5Hcos2SjZ?2D2DPbv11!4JH12cosjt!j/2112cosjb攸22DPb-V21!4J(41)Trapped-VolumePumpDesign.SubstitutingtheresultsofEqs13!,36!,and、37!intoEqs10!and12!yieldsthefollowingresultsfortheoutpu

44、tandinputpowerofthetrapped-volumepumpdesign:P»out5PidealH12DPb-VI1!2J,P-in5Pidea!H2DPbV-2±(42)SubtractingtheoutputpowerfromtheinputpowerD.(44)J71an .74yieldsthepowerlossofthetrapped-volumepumpdesign.ThisresultisgivenbyP-loss5PidealHDPb12J.(43)Theefficiencyofthetrapped-volumepumpdesignisgiv

45、enbyh5P-outP-in5!21S2bDP2VFig. 6 Piston pressuresAngular Position,JournalofDynamicSystems,Measurement,andControlDiscussionTomakeplotsofthepreviousresultsastheyvarywithpressuresnewvalveplateneedstobedesignedforeachoperatingpressureFigure8illustratesthechangingvalve-platedesignsastheyvarywithoperating

46、pressureforthebasicpumpparametersgivenintheAppendixEquations40!and43!describethepowerlossesofthestandarddesignandthetrapped-volumedesignrespectively.TheseequationsareplottedinFig.9usingtheparametersgivenintheAppendixAsshowninFig9,tepowerlossesaregreaterforthestandarddesignascomparedtothetrapped-volu

47、medesign.1251144.711376281.00-0.75030-025-0.00-。2530,1250.00AngularPosition,Fig. 7 PistondischargeflowsThisfactmaybeexplainedbytheslotsonthevalveplateThereaderwillrecallthattheslotsareusedtoprovideaflowpassagewhichaccommodatesthepressuretransitionsattopandbottomdeadcentersAtbottomdeadcenter,whenthep

48、istonisenteringthedischargeport,fluidflowsthroughthevalve-plateslotintothepistonchamberuntilthefluidpressurewithinthepistonchamberisequaltothatofthefluidpressureinthedischargeportofthepumpInordertomakethesepressuresequaLthefluidinthepistonchamberneededtobecompressed;and,asaresult,energywasaddedtothe

49、piston-chambervolumeAttopdeadcenter,thevalve-plateslotisusedtodecompressthefluidthatwascompressedatbottomdeadcenter.Thisdecompressionorexpansionofthefluidresultsinaflowthroughtheslotwhichreleasesthestoredenergyinthefluid.Thisreleasedenergyisneverrecoveredsincetheintakeportofthepumpismodeledasaconsta

50、ntpressuresourceoffluidOntheotherhand,thetrapped-volumepumpdesigndoesnotutilizeslotsforachievingasmoothpressuretransitionattopandbottomdeadcenters;and,asaresult,theenergyinthefluidisnotaddedorreleasedinanuncontrollablefashionthatdissipatesenergy.Inthetrapped-volumecase,theenergyaddedtothefluidatbott

51、omdeadcenterisaddedmechanicallythroughthevolumechangeofthepistonchamberitselfSimilarly,attopdeadcenter,theenergyreleasedfromthefluidisrecoveredmechanicallysinceitisachievedthroughthevolumetricchangeofthepistonchamberaswellInbothdesigncases,however,energyislostattheinterfacebetweenthepumpdischargecha

52、mberandthehydraulicsystemchamberwhichisconsideredtobeatthesamepressureastheintakeportofthepumpThisenergylossamountstothetotalenergylossshowninEq.43!andisduetotheuncontrolledexpansionofthefluidasitcrossestheboundarybetweenthepumpdischarge-chamberandthehydraulicsystemchamber.Equations41!and44!describe

53、thevolumetricefficiencyofthestandarddesignandthetrapped-volumedesign,respectively.TheseequationsareplottedinFig.10usingtheparametersgivenintheAppendix.AsshowninFig.10,tetrapped-volumedesignismoreefficientthanthestandarddesign.Again,thisisduetothedifferencesinpower-losscharacteristicsofthesetwodesign

54、s.Thisefficiencyimprovementcanbeashighas5percentdependinguponthepumpdesignandtheoperatingpressureItcanbeshownfromtheanalyticalresultsofthisstudythat,asVoincreases,theadvantagesofusingatrapped-volumedesignbecomemoreapparent.ConclusionThispaperhasattemptedtoshowthatthepowerlossandefficiencyofapumpcanb

55、ealteredbychangingtheportinggeometryofthevalveplateInparticular,thisresearchhascomparedthevolumetriclossesduetofluidcompressionbetweenvalve-platedesignsthathaveconstantareaslotsandonesthatutilizetrappedvolumeregionsintheplaceofslotsInthisresearch,ithasbeenshownthatvalveplateswithslotsgeneratelossest

56、hatresultfromtheuncontrolledexpansionoffluidwhichoccursthroughtheslotsattopandbottomdeadcenters.Ontheotherhand,valveplatesthataredesignedwithtrapped-volumeregionscanmechanicallyrecovertheenergychangethatoccursfromcompressinganddecompressingthefluid.Asaresult,trapped-volumedesignsaremoreefficientthanthestandardpumpdesignswhichutilizeslotsonthevalveplate0.60OperatingPrewure,zAPMPa Q 75