車輛制動裝置VehicleBrakingDevice任務(wù)五F8型分配閥TypeF8distributionvalve主講人李西安ZHENGZHOURAILWAYVOCATIONAL&TECHNICALCOLLEGESpeakerLiXi’anF8型分配閥的作用（EffectsofF8typedistributingvalve）三2．常用制動作用及穩(wěn)定性和安定性servicebrakingandstabilityF8型分配閥的作用（EffectsofF8typedistributingvalve）三主控部處于制動位置。

Thecontrolunitisinthebrakingposition.此時(shí)，由于緩解柱塞向上移動，切斷壓力風(fēng)缸壓縮空氣向制動管逆流的通路，使主活塞上下兩側(cè)的壓力差進(jìn)一步增大，主活塞迅速向上移動。

Atthispoint,asthereleaseplungermovesupward,itcutsoffthepathforcompressedairinthepressurechambertoflowbacktothebrakepipe,furtherincreasingthepressuredifferencebetweentheupperandlowersidesofthemainpiston.Themainpistonmovesrapidlyupward.緩解閥在彈簧的作用下，關(guān)閉制動缸與大氣的通路。

Undertheactionofthereleasevalvespring,thecommunicationbetweenthebrakecylinderandtheatmosphereisclosed.當(dāng)制動管以常用制動減壓時(shí)，主控部的主活塞上方的空氣壓力下降，而主活塞下方壓力風(fēng)缸壓縮空氣，開始向制動管逆流，

Whenthebrakepipeisdepressurizedinservicebrakeapplication,theairpressureabovethemaincontrolpistoninthecontrolunitdecreases,whilethecompressedairbelowthemainpistoninthecontrolunitstartstoflowbacktothebrakepipe.但由于受縮堵Ⅰ的限制，其逆流速度較慢，

However,duetotherestrictionofrestrictorI,theflowrateintheoppositedirectionisslow.隨之主活塞上下形成一定的壓力差，同時(shí)又有制動彈簧的預(yù)緊力作用，推動主活塞并帶動緩解柱塞、主閥桿等向上移動。Asaresult,apressuredifferenceisformedbetweentheupperandlowersidesofthemainpistonandthepre-tensionforceofthebrakespringpushesthemainpiston,alongwiththereleaseplungerandthemainvalvestem,upwards.F8型分配閥的作用（EffectsofF8typedistributingvalve）三第一階段局減作用First-stagelocalreduction：

主活塞上方的壓縮空氣經(jīng)a3→緩解柱塞中心孔a4→緩解柱塞徑向孔→緩解柱塞與局減閥套的溝槽→e5→局減閥中的縮堵Ⅳ→e4→e3→e2→e1→e→局減室，同時(shí)經(jīng)通路e3→充氣閥排氣口排人大氣，形成第一階段局減作用

Thecompressedairabovethemainpistongoesthrougha3→thecenterholea4ofthereleaseplunger→theradialholeofthereleaseplunger→thegroovebetweenthereleaseplungerandthelocalreductionvalveseat→e5→therestrictorIVinthelocalreductionvalve→e4→e3→e2→e1→e→thelocalreductionchamber.Atthesametime,itventstotheatmospherethroughthepathe3→theexhaustportofthechargingvalve,formingthefirst-stagelocalreductioneffect.F8型分配閥的作用（EffectsofF8typedistributingvalve）三副風(fēng)缸壓縮空氣→b→b1→b2→打開的平衡閥口→b3→d8→限壓閥套和限壓閥→d7→d6→d1→d→制動缸。

Compressedairintheauxiliarycylinder→b→b1→b2→openbalancevalveport→b3→d8→theguidesleeveandtheguidevalveofthelimitingvalve→d7→d6→d1→d→thebrakecylinder.同時(shí)制動缸壓縮空氣又經(jīng)d7→大縮堵Ⅱ→d5→主閥小活塞上方，又經(jīng)d9→d10→充氣閥活塞的上側(cè)，壓縮充氣閥彈簧，使充氣閥向下移動，充氣閥桿上的橡膠密封圈切斷局減閥通大氣的通路，第一階段局減作用結(jié)束。

Atthesametime,thecompressedairinthebrakecylinderpassesthroughd7→thelargerestrictorII→d5→theuppersideofthesmallpistonofthemainvalve,thenthroughd9→d10→theuppersideofthechargingvalvepiston,compressingthechargingvalvespring,causingthechargingvalvetomovedownward.Therubbersealingringonthechargingvalvestemcutsoffthecommunicationbetweenthelocalreductionvalveandtheatmosphere,endingthefirst-stagelocalreductioneffect.但制動管壓縮空氣向局減室充氣的通路并沒有切斷，局減室空氣壓力將繼續(xù)增加，一直到局減室空氣壓力與制動管空氣壓力平衡為止，即第二階段局減結(jié)束。

However,thepathforthecompressedairinthebrakepipetochargethelocalreductionchamberisnotcutoffandtheairpressureinthelocalreductionchambercontinuestoincreaseuntilitbalanceswiththeairpressureinthebrakepipe,whichmarkstheendofthesecond-stagelocalreduction.常用制動初期，輔助室的空氣壓力幾乎不變，

Intheearlystageofregularbraking,theairpressureintheauxiliarychamberremainsrelativelyconstant.

制動管減壓后，作用在輔助閥活塞上下側(cè)壓力失去平衡，

Afterthepressurereductioninthebrakepipe,thepressurebalanceontheupperandlowersidesoftheauxiliaryvalvepistonislost.

當(dāng)其壓力差大于輔助閥的動作壓差時(shí)，輔助閥活塞與輔助閥桿一起向下移動，Whenthepressuredifferenceexceedstheactuationpressuredifferentialoftheauxiliaryvalve,theauxiliaryvalvepistonmovesdownwardtogetherwiththeauxiliaryvalvestem.

先遮斷壓力風(fēng)缸與輔助室的空氣通路（c5與f1間聯(lián)絡(luò)），然后開啟輔助室與常用排氣堵的空氣通路，

Firstly,itblockstheairpassagebetweenthepressurecylinderandtheauxiliarychamber(connectedbetweenc5andf1),thenitopenstheairpassagebetweentheauxiliarychamberandtheregularexhaustplug.

使輔助室的壓縮空氣從常用制動排風(fēng)堵Ⅴ排人大氣，輔助閥處于常用制動位置。

ThisallowsthecompressedairintheauxiliarychambertobeexhaustedtotheatmospherethroughtheregularbrakingexhaustplugⅤandtheauxiliaryvalveisintheregularbrakingposition.F8型分配閥的作用（EffectsofF8typedistributingvalve）三制動機(jī)的穩(wěn)定性，即指在列車管緩慢減壓速度（如列車管漏泄等）下不發(fā)生制動作用的性能。Insensitivitybrakereferstoitsabilitytonotapplybrakeswhenbrakepipeisgraduallydepressurized(suchasduetoleakage).列車正常運(yùn)行過程，分配閥呈緩解作用位。Duringnormaltrainoperation,thedistributingvalveisinthereleaseposition.此時(shí)若列車管緩慢減壓（如漏泄），此漏泄速度小于制動管最小減壓速度，Ifthebrakepipegraduallydepressurizes(e.g.,duetoleakage)ataratelowerthantheminimumpressurereductionspeedofthebrakepipe,則壓力風(fēng)缸壓縮空氣經(jīng)壓力風(fēng)缸限制堵向制動管逆流，制動管壓力下降的同時(shí)也補(bǔ)償了制動管壓力，thecompressedairinthepressurechamberflowsbacktothebrakepipeagainsttherestrictorofthepressurechamber,compensatingforthepressuredecreaseinthebrakepipe.使壓力風(fēng)缸與制動管壓力同步下降，在主活塞兩側(cè)不能形成壓力差，主活塞不會上移而產(chǎn)生制動作用，保證了制動機(jī)的穩(wěn)定性。Thissynchronouslyreducestheairpressureinthepressurechamberandthebrakepipe,preventingtheformationofapressuredifferenceonbothsidesofthemainpistonandensuringthatthemainpistondoesnotmoveupwardtoapplybrakes,thusensuringthestabilityofthebrakesystem.(2)制動機(jī)的穩(wěn)定性InsensitivitybrakeF8型分配閥的作用（EffectsofF8typedistributingvalve）三

(3)制動機(jī)的安定性Servicestabilitybrake制動機(jī)的安定性是指制動機(jī)在常用制動減壓時(shí)不發(fā)生緊急制動作用的性能。

Servicestabilitybrakereferstoitsabilitytonotengageinanemergencybrakingactionduringregularbrakingandpressurereductionoperations.

制動管常用制動減壓，輔助閥活塞下方的空氣壓力下降，輔助閥活塞的上下兩側(cè)形成常用制動壓力差，

Duringservicebrakeapplicationpressurereduction,theairpressurebelowtheauxiliaryvalvepistondecreases,creatingapressuredifferenceonbothsidesoftheauxiliaryvalvepiston.

輔助閥活塞稍向下移動，輔助閥桿露出常用制動排風(fēng)堵，

Asaresult,theauxiliaryvalvepistonmovesslightlydownward,exposingtheventoftheregularbrakingexhaustplug.

輔助室的壓縮空氣除經(jīng)常用制動排風(fēng)堵排向大氣（輔助室壓縮空氣→f3→f2→f1→f4→縮堵Ⅴ→大氣），

hecompressedairintheauxiliarychamberisexhaustedthroughtheregularbrakingexhaustplugtowardstheatmosphere(compressedairintheauxiliarychamber→f3→f2→f1→f4→exhaustplugⅤ→atmosphere).

輔助室排氣速度不小于制動管常用制動最大減壓速度，

Theexhaustspeedoftheauxiliarychambershouldnotbelessthanthemaximumpressurereductionspeeddur