Chapter10AirSupplyDevicesand

PneumaticComponents

Apneumaticsystemincorporatesthefollowingcomponentsanddevices:(1)Airsupplydevices(2)Actuators(3)Controlelements(4)PneumaticattachmentsSimilartohydraulictransmission,pneumatictransmissionperformsthefunctionofenergytransferandcontrolbythemediumofflow.Theyhaveagreatdealincommonintheaspectsofworkingprinciple,components’structure,systemcompositionandgraphicsymbol.Thereadersshouldnoticetheirdifferences.

10.1AirSupplyDevices10.2PneumaticPneumaticAttachments10.3PneumaticActuators10.4PneumaticRegulatingValvesChapterlist10.1AirSupplyDevices

10.1.1Pressuregenerationdevices10.1.2Purificationandstoringdevicesandequipmentscompressedair

10.1.3F.R.LCombination

Airsupplydevicesareusedtoprovidecompressedair(withacertainleverofpressure,flowrateandpurification)forpneumaticsystem.

Anairsupplydeviceincorporatesfourparts:(1)pressuregenerationdevices;(2)airregeneration;(3)storingdevices;(4)airlinesandF.R.Lcombination.

Normallythefirsttwopartsarelocatedincompressedairstationasacentertosupplygasinindustryorworkshop,seeFig.10-1.

Fig.10-1Schematicviewofairsupplysystem

1-Aircompressor2-Cooler3-Oilandwaterseparator4、7-Receiver5-Airdryer6-Airfilter10.1.1Pressuregenerationdevices1.CompressorclassificationAccordingtoworkingprinciples:displacementanddynamic;Accordingtostructures:seeFig.10-2;Accordingtooutputpressures:lowpressure(0.2~1.0MPa),mediumpressure(1.0~10MPa),highpressure(10~100MPa),superhighpressure(>100MPa).Accordingtooutputflowrates(delivery):mini(<1m3/min),small(1~10m3/min),medium(10~100m3/min),large(>100m3/min).Fig.10-2Basiccompressortype2.Workingprinciplesofcompressors

Takeapistoncompressorforexample

Fig.10-3Pistontypecompressoroperation1-Exhaustvalve2-Cylinder3-Piston4-Pistonrod5-Slidingblock6-Connectingrod7-Crank8-Exhalevalve9-Spring10.1.2Purificationandstoringdevicesandequipmentscompressedair

1.Demandsforbetterqualityofcompressedair

2.Purificationandstoringequipmentsforcompressedair

(1)Cooler

Coolerscanbefurtherclassifiedbasedontheirarrangement:coiltubulartype(seeFig.10-4a),seriestubulartype(seeFig.10-4b),thermosyphonsystemandtubedrivetype.Therearetwotypesofcooling:watercoolingandaircooling.

a)Coiltubulartypeb)SeriestubulartypeFig.10-4CoolerFig.10-5Strikeandreturnwithringrevolvingtypemoistureseparator(2)MoistureseparatorFig.10-6Receiver

(3)ReceiverFig.10-7Heatlessregenerationdryer

(4)Airdryer10.1.3F.R.LCombinationF.R.LCombinationisshortforthecombinationofanairfilter,apressurereducingvalveandanoilmistlubricator.TheirinstallationorderisshowninFig10-8.Fig.10-8F.R.LCombination

1-Airfilter2-Pressurereducingvalve3-Pressuregauge4-Oilmistlubricator1.Airfilter(1)OperationFig.10-9Airfilter1-Whirlwindleaf2-Filterelement3-Bowl4-Baffle5-Drainvalve(2)Performance1)Filterrating(μm)

（10-1）2)Watertrapefficiency:capacitytoseparatewater,usuallydenotedbysymbolη,3)Dustremovalefficiency

4)Flowratecharacteristics:thedifferenceofinputandoutputpressuresmustbelessthan5%ataratingflowrate.2.Oilmistlubricator(1)OperationandconstructionClassification:Fig.10-10Oilmistlubricator

enlarge1-Spring2-Gas-guidepulverizingtube3,7-Steelball4-Valveseat5-Bowl6-Syphontube8-Throttlevalve9-Lid10-Sealgasket11-Oilpluga,b-Smallorifice

a)Atrestb)Atworkingc)AddingoilFig.10-11Threeoperationstatesofthespecialcheckvalve

1-Spring2-Gas-guidepulverizingtube3-Steelball4-Valveseat(2)Mainperformanceandindices1)Flowcharacteristics

2)Foggingoilflowrate

Otherperformancesofoilmistlubricatorincorporateareoildripregulation,fogsize,fluctuationcharacteristics,lowestpressureforaddingoilwithoutgasceasing.3.Pressurereducingvalve(1)OperationandstructureFig.10-12Pressurereducingvalve1-Handle2,3-Regulatingspring4-Springseat5-Diaphragm6-Feedbacktube7-Valverod8-Valvecore9-Returnspringenlarge（2）Mainperformance1)Pressurecharacteristics:describesthefluctuationofoutputpressurep2withtheinputpressurep1underagivenoutputflowrateq.Fig.10-13ashowsitscharacteristiccurves.2)Flowratecharacteristics:describesthefluctuationoftheoutputpressurep2withoutputflowratequnderagiveninputpressurep1.Fig.10-13bshowsitscharacteristiccurves.

a)Pressurecharacteristicsb)Flowratecharacteristics

Fig.10-13Performancecurvesofpneumaticpressurereducingvalves

10.2PneumaticAttachments10.2.1Mufflers10.2.2Pipelineconnectors10.2.1Mufflers

Threetypesofmufflerareavailable:absorptivemufflers,expansivemufflers,expansiveandabsorptivemufflers.Fig.10-14Absorptivemuffler

1-Connectingscrew2-Mufflerbody10.2.2Pipelineconnectors

Pipelineconnectorsincorporatetubesandpipefittings.Therearerigidtubesandhosetubes.Pipecouplingsincludebitetypetubefittings,flaredtypetubefittings,corplingofborsingandquickreleasefittings.10.3PneumaticActuators10.3.1Pneumaticcylinders10.3.2Airmotors10.3.1Pneumaticcylinders1.operationsandfunctions(1)Diaphragmcylinders(2)Air-hydrauliccylinders

Hydro-pneumaticworkingisachievedbymechanicallycouplingapneumaticcylinderandalow-pressurehydrauliccylindersothattheyhaveacommonmovementnormallyinitiatedbycompressedairappliedtotheaircylinder.Liquidshavebutslightcompressibilityandairflowiseasytocontrol,whichleadtoastablemovementandanadjustablespeed.Asshowinfig.10-16

a)Single-acting

b)Double-acting

Fig.10-15Diaphragmcylinder

1-Diaphragmplate2-Diaphragm3-Pistonrod4-Cylinderbodya,b-Inlet/Outletport

Fig.10-16Air-hydrauliccylinders

1-Pneumaticcylinder2-Hydrauliccylinder3-Checkvalve4-Throttlevalve5-Make-upoiltank

(3)Rodlesscylinders

Fig.10-17RodlesscylinderRodlesscylinderconstructionb)Cylindertubegroovedsealarrangement1,4-Dustslotseals2-Carriage3-Drivetongue5-Rodlesspiston6-Cylinderbarrelenlarge

(4)Impactcylinders

Animpactcylinderisonearrangedsothatthespeeddevelopedishighenoughforimpactwork,suchasforging,piercing,etc.Itconvertsthepressureenergyofthecompressedairintopiston’shighspeed(morethantenmeterspersecond)motionenergyinaveryshorttime.Fig.10-18showsanimpactcylinderdesign.Comparedwithcommoncylinders,thereisanextramiddlelid3(fittedwiththecylinderbody)withnozzleDandexhaustingsmallorificeE.Thecylinderisdividedintothreechambersbythismiddlelidandpiston2.Forthesakeofanalysis,theworkingprocesscanbesimplydividedintothreesteps.1)Reset2)Energystorage3)Impacting

Fig.10-18a)Impactcylinder-Reset

b)

Impactcylinder-Energystorage

c)

Impactcylinder-Impacting

A-PistonrodchamberB-Non-rodchamberC-EnergystoringchamberD-NozzleE-Exhaustingport1-Cylindertube2-Piston3-Middlecover4-Controlvalve5-Pistonrod10.3.2Airmotors1.operationandcharacteristicsofairmotors(1)VanemotorsFig.10-19ashowsasimplevanemotoroperation.Fig.10-20showsthesoftcharacteristicsofvanemotorunderacertainworkingpressure.(2)Radialpistonmotors

SeeFig.10-19bandFig.10-21.(3)Diaphragmmotors

Diaphragmmotorsarebasicallyanapplicationofdiaphragmcylinders.AsisshowninFig.10-19c

Fig.10-19a)Vanemotorsoperationb)Pistonmotorsoperationc)Diaphragmmotorsoperation1-Vane

2-Stator3-Rotor

4-Airinletport5-DistributionvalveFig.10-20CharacteristicsofavanemotorFig.10-21Workcharacteristiccurveofpistonpneumaticmotora)Power-speedcurveb)Torque-speedcurve2.Selectionandapplicationofairmotors1)Airmotors’selection2)Airmotors’application3)Airmotors’lubricating10.4PneumaticRegulatingValves

Tab.10-1PneumaticregulatingvalvesTab.10-1showsthethreetypesofregulatingvalves,withtheircharacteristicsTypeNameGraphicSymbolCharacteristicsPressurecontrolvalvesPressurereducingvalvesAvalvehavingitsoutletportconnectedtothesystemsothatwithvaryinginletpressureoroutletflow,theoutletpressureremainssubstantiallyconstant.InletpressuremustremainsubstantiallyhigherthantheselectedoutletpressurePressurereliefvalves(safetyvalves)Avalvehavingitsinletportconnectedtothesystemwhichlimitsthemaximumpressurebyexhaustingfluidwhenthesystempressureexceedsthepresetpressureofthevalve.Undernormaloperatingconditionsthevalveremainsclosed,onlyoperatingwhenunusualsystemconditionsprevailSequencevalvesAvalvewithitsinletportconnectedtoonepartofthesystemanditsoutletportconnectedtoanotherpartofthesystemandsetsothatuntiltheinletpressurerisesabovethepresetopeningpressurethefluidmediumispreventedfromflowingtotheoutletportTab.10-1PneumaticregulatingvalvesFlowcontrolvalvesThrottlevalvesAvalvewhereanorificesizeissettocontroltheflowratethroughthevalveExhaustmufflerthrottlevalvesAvalvesituatedatexhaustportandsettocontrolexhaustingflowrate,movingspeedofactuatorandthusreduceexhaustnoiseDirectio-nalControlvalvesShiftdirecti-onalvalvesPneumaticpressureAshiftdirectionalvalvedrivenbypneumaticpressure.Safeandreliableinoperation,availableforpoorconditions.a)Controlledbypressureorpressure-reliefb)ControlledbydifferentialpressureElectrica-llyAshiftdirectionalvalvedrivenbysolenoid,includingspringloadedtypeandpilotoperatedtype.a)Directair-operatedtypeb)Pilotoperatedtypecontrolledbypneumaticpressurec)Pilotoperatedtypecontrolledbypneumaticpressure-reliefDirectio-nalControlvalvesShiftdirecti-onalvalvesMechanic-allyAshiftdirectionalvalvedrivenbycam,blockorothermechanism,commonlyusedassignalvalveinstrokecontrolsystem(strokevalve).a)Directair-operatedtypeb)Roller-typec)PassabletypeManuallyByhandorpedaletc.a)Buttonb)Leverc)PedalDirectio-nalControlvalvesOne-waycontrolvalvesCheckvalvesAvalveallowsflowoftheairinonedirectiononly,theotherdirectionthroughthevalvebeingatalltimesblockedtotheairflowShuttlevalvesAcombinationoftwoone-wayvalves,givinganoutletfromeitheroneoftwopressurizedinlets(whicheveristhegreatervalue).ItisthusmoreofaspecialvalvethanatrueshiftdirectionalvalveandisbasicallyusedforlogicORswitchingBi-directionalvalvesAcombinationoftwoone-wayvalvestoperformthefunctionof‘AND’gateQuickexhaustvalvesAquickexhaustvalveisdesignedtoincreasethespeedofmovementofacylinderbyallowingtheexhaustairtoventdirectlytoatmosphereyoursuggestions

arewelcome!TheEnd

Inapistoncompressor,thepistonmovesreciprocatinglyforairsuctionandcompression(toincreasetheairpressure)throughacrankandconnectingrodmechanism.Fig.10-3showsitsoperation,whichissimilartothatofthesinglepistonpumpoperation(seeFig.3-1inchapter3).Thecrankslidermechanismisdrivenbythemotortodevelopthereciprocatingmotionofpiston3,i.e.,therotationofcrank7isconvertedintothereciprocatingmotionofslider5andpiston3.Mostaircompressorsarethecombinationofmulti-cylinderandmulti-piston.Fig.10-4Coolera)CoiltubulartypeFig.10-4Coolerb)Seriestubulartype

Fig.10-5Strikeandreturnwithringrevolvingtypemoistureseparator

Fig.10-9Airfilter

Fig.10-10OilmistlubricatorFig.10-18Impactcylinder-Reset

Fig.10-18Impactcylinder-EnergystorageFig.10-18Impactcylinder-Impacting

Fig.10-19aVanemotorsoperationChapter11BasicPneumaticCircuits

andTheirApplication

Allpneumaticsystemsarecomposedofsomebasiccircuitswithdifferentfunction,familiarizingandmasteringthesebasiccircuitsarenecessaryfoundationforanalyzinganddesigningpneumaticsystems.Thebasiccircuitmaybeclassifiedbasedonfunction:pressureandforcecontrol,directioncontrol,speedcontrol,etc.One-stagepressurecontrolcircuit1-Pressuremeter2-Pressureswitch3-reliefvalve

Two-stagepressurecontrolcircuita）Highandlowpressureschangeovercircuit

Pressuredifferencecircuit

a)b)

Pressurecontrolsequencecircuit

Over-loadprotectioncircuitForceincreasedcircuitbymultiple(threehere)in-linecylindersForceincreasedcircuitby

anair-hydraulicintensifierImpactcylindercircuitCylinderextendingandretractingcircuitCylinderextending,retractingandstopcircuit

Cylinderextendingandretractingcircuit

a)b)Cylinderextending,retractingandstopcircuit

Single-actingcylinderone-directionspeedcontrolcircuit

a)Inletone-directionthrottlingspeedcontrolcircuit

b)Exhaustone-directionthrottlingspeedcontrolcircuit

a)Double-directionthrottlingspeedcontrolcircuit

b)Exhaustthrottlingspeedcontrolcircuit

Rapidreciprocatingmovementcircuit

Speedexchangingcircuit

Cushioningcircuits

Air-hydraulicspeedchangingcontrolcircuitSpeedchangingcircuit

yoursuggestions

arewelcome!TheEndOne-stagepressurecontrolcircuitTwo-stagepressurecontrolcircuitHighandlowpressureschangeovercircuit

Over-loadprotectioncircuit

Forceincreasedcircuitbymultiple

(threehere)in-linecylinders

Forceincreasedcircuitbyanair-hydraulicintensifier

Impactcylindercircuit

Chapter12ExamplesofPneumatics

TransmissionSystem12.1PneumaticTransmiss