力士乐M9多路换向阀ppt课件.ppt

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1、2-loopPositiveControlBlockM9-25HydraulicSystemsatBoschRexrothLUDVNegativeControlPositiveControlThrottle-ControlOpenCentersystemThepumpflowingoingtothetankwhenthemainspoolisinmiddleposition.Withmovingthemainspooltheflowgetsthrottleduntilthepressureraisestotheconsumerlevelandthec

2、ylindermoves.Thissystemwasoriginallydesignedforconstantpumps,butisusedtodaywithvariabledisplacementpumpstorunonaconstantpowercurve.LoadSensingSystemHereeachaxishasanindividualpressurecompensatorwhichislocatedbeforethemeter-inorifice.Thehighestconsumerpressureiscalledtothepumpwh

3、ichswivelsouttotherequestedflow.Incaseofundersaturationtheconsumerwiththehighestpressurestopsmoving.LoadSensingSystem4.Differentconsumerpressuresarelevelledbythecompensators.5.Theindividualflowtoeachcylinderisinstalledinthemeter-inorificeofthemainspool.6.Whenthedeltapofthecompe

4、natorspringissaturated,thecompensatorclosesandtherearenolossestothetank.FlowSharingSystemThedifferencetoLSsystemsarethecompensators.ThedeltapinLUDVisinstalledinthepumpregulatornotinthecompensators.Thesignalofthecylinderwiththehighestloadissendtoallcompensators.Incaseofundersatu

5、rationtheycloseandtheremainingflowwillbeproportionalreducedineachfunction.Noneoftheconsumerstops.RequirementsforControlofExcavatorGoodfinecontrolofconsumersSimultaneousmovementsControllabilityLowhydrauliclossesEfficientuseofpowerCompactdesignofcomponentsSpacesavingandservicefri

6、endlyinstallationPossibilityofaddingoptionsFastmovementsComparisonofExcavatorControlPrinciplesThreeDifferentSystemsFlowSharingSystems,LUDVitcanberealiseda1-loopsystemwithaloadindependentcontrol.Itisusedincrawlerexcavatorssmaller20tonandwheeledexcavatorsNegativeControlItisaOpenC

7、entresystemmainlyusedfromJapaneseandKoreancompanies.InneutralthepumpalwayssaturatestheNCorifices.Whenamainspoolgetsmovesoutofcentre,theneutralclosesandthepressureattheNCorificedrops.Thisswivelsoutthepump.ThreeDifferentSystemsPositivecontrolThisisalsoaOpenCentresystem,basedonthe

8、NCsystems.ThereisatendencyofJapanesecompaniesmovingtow