车辆制动装置VehicleBrakingDevice46课

车辆制动装置VehicleBrakingDevice120型控制阀MODEL120CONTROLVALVE主讲人李西安ZHENGZHOURAILWAYVOCATIONAL&TECHNICALCOLLEGESpeakerLiXi’an紧急制动位（六）司机将自动制动阀手把移到紧急制动位，制动管压缩空气迅速排入大气，主阀各部分的动作，除紧急二段阀外，均与常用制动一样。Thedrivermovesthehandleoftheautomaticbrakingvalvetotheemergencybrakingposition,andthecompressedairinthebrakepipeisquicklydischargedintotheatmosphere.Theactionsofallpartsofthemainvalve,exceptfortheemergencysecondaryvalve,arethesameasthoseofservicebraking.主活塞上移，先后产生第一、第二个阶段的局减作用及制动作用，只是动作更加迅速，且制动缸一直充到与副风缸压力相平衡的最高压力。Themainpistonmovesup,producingthefirstandsecondstagesoflocalpressurereductionandbrakingeffects,buttheactionisfaster,andthebrakecylinderiscontinuouslychargedtothehighestpressurethatequalstotheauxiliaryaircylinderpressure.紧急二段阀动作，制动缸压力分二个阶段上升，紧急阀动作，形成紧急放风作用。Theemergencytwo-stagevalveacts,causingthebrakecylinderpressuretoriseintwostages.Theemergencyvalveacts,creatinganemergencyventilationeffect.紧急制动位（六）紧急制动位（六）在紧急阀中，紧急室压缩空气先是经紧急活塞上腔J1、紧急活塞杆的限孔Ⅳ、Ⅲ向制动管逆流，制动管急剧减压，紧急活塞稍稍压缩安定弹簧下移，紧急活塞杆顶面密封圈离开紧急阀盖，紧急室压缩空气经紧急活塞杆轴向孔顶端孔口及限孔Ⅲ，向紧急活塞下侧的制动管L12逆流。Intheemergencyvalve,thecompressedairintheemergencychamberfirstflowsbackthroughtheupperchamberJ1oftheemergencypistonandthelimitholesIVandIIIoftheemergencypistonrodtowardsthebrakepipe.Thebrakepipedepressurizesrapidly,andtheemergencypistonslightlycompressesthestabilizerspringandmovesdownwards.Thetopsealingringoftheemergencypistonrodleavestheemergencyvalvecover.ThecompressedairintheemergencychamberflowsbackthroughthetopholeandlimitholeIIIoftheaxialholeoftheemergencypistonrodtowardsthebrakepipeL12onthelowersideoftheemergencypiston.01紧急阀放风作用Emergencyvalveventilationfunction该逆流速度受限孔Ⅲ的限制，远远小于制动管的减压速度，紧急活塞两侧迅速形成压力差，紧急活塞压缩安定弹簧下移3mm，紧急活塞杆的下端面与先导阀顶杆接触，紧急活塞杆下端面孔口被堵，紧急室压力空气通过限孔Ⅲ、限孔V（φ1.1mm）向制动管逆流，紧急活塞两侧的压力差进一步增大，紧急活塞继续下移推先导阀顶杆，克服先导阀弹簧的阻力，顶开先导阀。ThecountercurrentspeedislimitedbythelimitholeIII,whichismuchlowerthanthedecompressionspeedofthebrakepipe.Thepressuredifferencequicklyformsonbothsidesoftheemergencypiston,andtheemergencypistoncompressesthestabilizerspringtomovedownby3mm.Thelowerendfaceoftheemergencypistonrodcontactsthepilotvalvetoprod,andtheholeonthelowerendfaceoftheemergencypistonrodisblocked.ThepressureairintheemergencychamberpassesthroughthelimitholeIIIandlimitholeV（diameter1.1mm)flowsbacktowardsthebrakepipe,furtherincreasingthepressuredifferenceonbothsidesoftheemergencypiston.Theemergencypistoncontinuestomovedownandpushthepilotvalvetoprod,overcomingtheresistanceofthepilotvalvespringandpushingopenthepilotvalve.于是，放风阀杆下腔L13的制动管压缩空气经开启的先导阀口、放风阀杆中部的4个径向小孔d2、放风阀杆外侧空腔、紧急阀排气口（喇叭口）D2排入大气。So,thecompressedairfromthebrakepipeofthelowerchamberL13oftheventvalvestemisdischargedintotheatmospherethroughtheopenpilotvalveport,thefourradialsmallholesd2inthemiddleoftheventvalvestem,theouterchamberoftheventvalvestem,andtheemergencyvalveexhaustport(bellmouth)D2.紧急制动位（六）受缩孔堵Ⅳ的限制，紧急活塞下腔L12的制动管压缩空气不能更多地流向放风阀导向杆下腔L13，放风阀的背压急剧下降。DuetothelimitationofshrinkageblockageIV,thecompressedairinthebrakepipeoftheemergencypistonlowerchamberL12cannotflowmoretothelowerchamberL13oftheventvalveguiderod,andthebackpressureoftheventvalvedropssharply.紧急活塞迅速下移（下移超过1mm）压缩放风阀弹簧顶开放风阀，制动管压缩空气→开启的放风阀口→紧急阀排气口（喇叭口）D2迅速排人大气，形成紧急制动放风（局减）作用，确保紧急制动产生，提高紧急制动波速，缓和列车纵向冲动。Theemergencypistonquicklymovesdown(morethan1mm)tocompresstheairreleasevalvespringandopentheairvalve.Thebrakepipecompressesair→theopenairreleasevalveport→theemergencyvalveexhaustport(bellmouth)D2isquicklydischargedintotheatmosphere,forminganemergencybrakingairrelease(localreduction)effect,ensuringtheoccurrenceofemergencybraking,increasingtheemergencybrakingwavespeed,andeasingthelongitudinalimpulseofthetrain.放风阀被压开以后，紧急室压力空气仍只能经限孔V逆流到紧急活塞下腔L12，然后排入大气。Aftertheventvalveispressedopen,thepressureairintheemergencychambercanonlyflowbackthroughthelimitingholeVtothelowerchamberL12oftheemergencypiston,andthenbedischargedintotheatmosphere.由于限孔V的限制，紧急室压力空气需15s左右才能排完。DuetothelimitationoflimitholeV,ittakesabout15secondsforpressureairoftheemergencychambertobedischargedcompletely.在紧急室压力空气未排尽时，放风阀一直处于开启状态，若在此时向制动管充气，制动机不能缓解。Whenthepressureairintheemergencychamberisnotexhaustedcompletely,theventvalveremainsopen.Ifthebrakepipeisinflatedatthistime,thebrakecannotbereleased.紧急室排气时间设计为15s左右，是为了使列车发生紧急制动后，必需在列车停车以后，才可以进行充气缓解，防止列车产生剧烈纵向冲动，甚至造成断钩事故。Thereasonwhytheexhausttimeoftheemergencychamberisdesignedtobe15secondsistoensurethatafterthetrainundergoesemergencybraking,inflationreliefcanonlybecarriedoutafterthetrainhasstopped,topreventseverelongitudinalimpulseofthetrainandevencausehookbreakageaccidents.紧急制动位（六）紧急制动时，制动管迅速减压，制动刚开始，由滑阀座来的副风缸压力空气，经紧急二段阀与套之间的大通路及紧急二段阀下部两个直径3毫米径向孔、轴向孔、上部直径3毫米径向孔流向制动缸，制动缸压力上升较快。Duringemergencybraking,thebrakepipequicklydepressurizes.Atthebeginningofbraking,theauxiliaryaircylinderpressureairfromtheslidevalveseatpassesthroughthelargepassagebetweentheemergencytwo-stagevalveandthesleeve,aswellasthelowertwo3mmdiameterradialholeoftheemergencytwo-stagevalve,axialhole,upperpart3mmdiameterradialhole,flowstowardsthebrakecylinder,andthepressureofthebrakecylinderincreasesrapidly.02紧急二段阀的作用Functionofemergencytwo-stagevalve制动缸压力跃升到120—160kPa时，制动缸推紧急二段阀克服紧急二段阀弹簧弹力、列车管剩余的压力以及紧急二段阀自重，压缩紧急二段阀弹簧上移到关闭位，切断紧急二段阀与套之间的大通路，副风缸压力空气只能经紧急二段阀轴向孔或缩孔、上部直径3毫米径向孔流到紧急二段阀套外围空腔Z6，充入制动缸，限制了制动缸的充气速度，使制动缸的压力上升变慢。Whenthepressureofthebrakecylinderrisesto120-160kPa(asspecifiedfortheconstantpressureofthetrainpipeonthetestbenchat600kPa),thebrakecylinderpushestheemergencytwo-stagevalvetoovercomethespringforceoftheemergencytwo-stagevalve,theremainingpressureofthetrainpipe,andtheweightoftheemergencytwo-stagevalveitself.Theemergencytwo-stagevalvespringiscompressedandmoveduptotheclosedposition,cuttingoffthelargepassagebetweentheemergencytwo-stagevalveandthesleeve,ThepressureairoftheauxiliaryaircylindercanonlypassthroughtheaxialholeorshrinkageholeⅧoftheemergencytwo-stagevalve(equippedwitha254mmdiameterbrakecylinder)andtheupperpart3mmdiameterradialholeflowstotheoutercavityZ6oftheemergencytwo-stagevalvesleeveandfillsthebrakecylinder,limitingtheinflationspeedofthebrakecylinderandslowingdownthepressureriseofthebrakecylinder.制动缸压力先快后慢，分两个阶段上升，减小长大货物列车在紧急制动时的纵向冲动。Thepressureofthebrakecylinderincreasesfirstfastandthenslow,andisdividedintotwostages(Figure6-33),abletoreducethelongitudinalimpulseoflargeandmedium-sizedtrainsduringemergencybraking.紧急制动位（六）120型控制阀专门设有紧急阀，当在常用制动后转紧急制动时，仍能通过每辆车的紧急阀把制动管的压缩空气直接排人大气，使制动波速加快，使全列车在短时间内发挥出最大制动力，缩短制动距离。Thetype120controlvalveisspeciallyequippedwithanemergencyvalve,whichcanstilldirectlyexhaustthecompressedairfromthebrakepipeintotheatmospherethroughtheemergencyvalveofeachvehiclewhenturningtoemergencybrakingafterservicebraking,acceleratingthebrakingwavespeed,allowingtheentiretraintoexertmaximumbrakingforceinashortperiod