液压专业英语教程6.docx

《液压专业英语教程6.docx》由会员上传分享，免费在线阅读，更多相关内容在工程资料-天天文库。

1、Unit6DirectionalcontrolvalvesThefunctionofadirectionalcontrolistodirectoilorairtovariousplacesIthesystem.thedirectionalcontroldirectsthemovementofthefluidsothatitcandowork.Thedirectionalcontrolisavalue・threedifferentclassesofdirectionalcontrolvalvesareuse

2、dinfluidsystems.Theymaybelistedas(1)two-way(twoportsandtwointernalpassages);(2)three-way(threeportsandthreeinternalpassages);and(3)four一way(fourportsandfourinternalpassages)・Eachvalvemaybeoperatedmanually,mechanically,electrically,orbyapilotarrangement.In

3、thischapter,thefunction.installation.andmaintenanceofdirectionalcontrolvalvesaretobestudied•Theimportanceofproperoperationofdirectionalcontrolvalvesistobestudied・Theimportanceofproperoperationofdirectionalcontrolscannotbeoveremphasized.Howwellasystemfunct

4、ionsoftendependsontheselectionofthepropercontrol.Thetwo-wayvalveisdiscussedfirst,andthenthethrcc-wayandfour-wayvalvesarcdiscussedinorder.Two-WAYvalvesAtwo-wayvalveconsistsoftwoports一aport,whichletsthefluidcomein(inletport),andaportwhichletsthefluidcomeout

5、(outletport).Eachportisconnectedtoaninternalpassage・Atsomepointintheoperationofthesevalves4hetwopassagesareconnected;atanotherpoint,theyarcdisconnected.Two-wayvalvesarceither"normallyopen"or"normallyclosed."Thismeansthatinthenormally-closedvalue,whentheac

6、tuator(themechanismwhichmodesthevalvefunction)isinitsnormalposition,theinletportandpassageareshutofffromtheoutletportandpassage.Toconnectthetwopassages,thevalveoperatormustfunction・Inanormally-openvalve,theinletpassageandtheFig.LANSGraphicsymbolforatwo-wa

7、ycontrolvalue.o31504LOWERPLUNGER82506SPRING31503UPPERPLUNGER2709-6••O11RING31504NUT3150-6SPRING8250-7WASHER3150-7WASHER315卜5WASHER8936-4WASHER8936-8LEVER•8936-9SCREW893640SL£EVE3257-6NUTCourtesyScovillFluidPowerDivision,ScovillMfg.Co.Fig・2・Apoppet-type伽o・

8、h®valve.Outletpassageareconnectedwhentheactuatingmechanismisinnormalposition.Thevalveactuatormustfunctiontoseparatethepassages.Two-wayvalveshavemanyuses.Someoftheseare:toshutoffairoroilflow,tobleedoffpressures、andto