車輛制動裝置VehicleBrakingDevice120型控制閥MODEL120CONTROLVALVE主講人李西安ZHENGZHOURAILWAYVOCATIONAL&TECHNICALCOLLEGESpeakerLiXi’an制動保壓位BrakingPressureMaintainingPosition（五）司機施行制動管常用制動減壓，當制動管減壓量達到要求時，將自動制動閥手把移到保壓位，制動管停止減壓呈保壓狀態(tài)。Driverusuallyreducespressurebyapplyingthebrakespipes.Whenthebraketubepressurereductionreachestherequirements,itwillmovetheautomaticbrakevalvehandtothepressureprotectionlevelandthebraketubestoppressurereductionisinthepressureprotectionstate.制動管剛停止減壓時，作用部的主活塞、節(jié)制閥和滑閥仍處于制動位，副風缸壓縮空氣繼續(xù)向制動缸充氣使其壓力降低。

Whenthebrakepipejuststopsdecompression,themainpiston,controlvalveandslidevalveoftheactingpartarestillinthebrakepositionandtheauxiliaryaircylindercompressedaircontinuestoinflatethebrakecylindertoreducethepressure.當副風缸壓力下降到接近制動管壓力（實際上是副風缸壓力稍低于制動管壓力）時，主活塞在被壓縮的穩(wěn)定彈簧的彈力及自重作用下，主活塞帶動節(jié)制閥下移6mm(滑閥不動)，至主活塞桿的上肩接觸到滑閥上端面時為止，節(jié)制閥開放了滑閥背面的f1和f2孔，蓋住滑閥背面的f3孔，形成了制動保壓位。Whenthesecondaryaircylinderpressuredropstoclosetothebrakepipepressure(actuallythesecondaryaircylinderpressureslightlybelowthebrakepipepressure),themainpistoninthecompressionofthestablespringelasticityandweightandthemainpistondrivecontrolvalvedown6mm(slidevalve)tothemainpistonrodshouldercontacttheupperendoftheslidevalveandthecontrolvalveopenthebackoftheslideofthef1andf2holes,coverthef3holeonthebackofthespoolvalveandformthebrakepressurelevel.節(jié)制閥蓋住滑閥背面的f3孔，切斷了副風缸壓力空氣向制動缸的充氣通路，副風缸停止降壓，制動缸停止升壓，滑閥仍處于制動位，實現(xiàn)制動保壓作用。Thecontrolvalvecoversthef3holeonthebackoftheslidevalve,cuttingofftheairpressureofthesecondaryaircylindertothebrakecylinder.Thesecondaryaircylinderstopsthepressureandthebrakecylinderstopstheboostandtheslidevalveisstillinthebrakingpositiontorealizingthepressureprotectioneffectofthebrake.制動保壓位BrakingPressureMaintainingPosition（五）圖7—30120閥制動保壓位緊急制動位Emergencybrakingposition（六）節(jié)制閥開放了滑閥背面的fi和f2孔。Thecontrolvalveopensthef1andf2holesonthebackofthespoolvalve.01適應機車壓力保持操縱Locomotivepressuremaintenanceadaptiveoperationfi孔與滑閥底面的l3、l4孔為貫通孔，l3.l4孔在滑閥座上是封住的，節(jié)制閥開啟f1孔沒有什么意義。Thef3andf4holesofthef1holeandthebottomsurfaceoftheslidevalvearethroughholesandtheholel3andl4aresealedontheslidevalveseat.Itismeaninglesstoopenthef1holeofthecontrolvalve.f2孔在滑閥內(nèi)與滑閥底面的眼淚孔f4相通，在制動位時，眼淚孔f4與滑閥座的制動管孔l1連通，這樣就形成了：副風缸→滑閥室F1→f2孔→l1孔→制動管，即在制動保壓位時，副風缸通過眼淚孔f4與制動管相通。Thef2holeisintheslidevalvewiththetearholef4atthebottomoftheslidevalve.Atthebrakeposition,thetearholef4isconnectedwiththebrakepipeholel1oftheslidingvalveseat,thusformingthef1,f2andl1holebrakepipeoftheauxiliaryaircylinder,thatis,atthebrakingPressureMaintainingPositionlevel,thesecondaryaircylindercommunicateswiththebrakepipethroughthetearholef4.這樣在制動保壓位，無論制動管或副風缸有輕微的壓力波動，它們相互產(chǎn)生壓力互補作用，主活塞兩側(cè)不能形成動作壓力差，確保了制動機處于制動保壓位。Inthisway,inthebrakepressureholdinglevel,nomatterthebrakepipeortheauxiliaryaircylinderhasslightpressurefluctuations,theyproducepressurecomplementaryeffectwitheachotherandtheactionpressuredifferencecannotbeformedonbothsidesofthemainpiston,ensuringthatthebrakeisinthebrakepressureholdinglevel.于是，當制動管輕微漏泄時，副風缸壓力空氣通過f4孔向制動管逆流，防止制動保壓位制動機產(chǎn)生再制動作用；當副風缸及其管系輕微漏泄時，制動管壓力空氣通過f4孔向副風缸補風，保證制動機在制動保壓位不發(fā)生自然緩解。Therefore,whenthebrakepipeleaksslightly,theauxiliaryaircylinderpressureairflowsagainstthebrakepipethroughthef4holetopreventthebrakepressureholdinglevelmotorfromproducingrebrakingeffect;Whentheauxiliaryaircylinderanditspipesystemleakslightly,thepressureairofthebrakepipewillreplenishtheairtotheauxiliaryaircylinderthroughthef4holetoensurethatthemotordoesnotrelievenaturallyatthebrakingPressureMaintainingPositionlevel.緊急制動位Emergencybrakingposition（六）當機車制動機使用壓力保持功能時，制動管的漏泄可通過機車制動機補足，因而副風缸的漏泄導致自然緩解的可能性更大，有了眼淚孔f4后，有效地防止了自然緩解的發(fā)生。Whenthelocomotivebrakeusesthepressurekeepingfunction,theleakageofthebrakepipecanbemadeupbythelocomotivebrake,sotheleakageofthesecondaryaircylinderismorelikelytoleadtonaturalrelief.Withthetearholef4,theoccurrenceofnaturalreliefiseffectivelyprevented.02階段制動作用Stagebrakingaction在制動管最大有效減壓量范圍內(nèi)，反復操縱制動管減壓、保壓，實現(xiàn)制動缸反復地增壓、保壓的過程為階段制動。Withintherangeofthemaximumeffectivepressurereductionofthebrakepipe,theprocessofrepeatedlyoperatingthepressureandmaintainingthepressureofthebrakecylinderarethestagebraking.階段制動便于機車司機根據(jù)需要調(diào)整制動力，改善列車的運行品質(zhì)。Stagebrakingi