第4章-Introduction-to-Sensor-and-Actuator

§4IntroductiontoSensorandActuatorBuildingAutomationSystemLecturer:DouLiqianStructureofthecourse•4IntroductiontoSensorandActuator4.1Valves4.2controlvalvesanddampers4.3Actuators4.4SensorsIntroductiontoSensorandActuator4.1ValvesAvalveisadevicethatregulatestheflowofafluidbyopening,closing,orpartiallyobstructingvariouspassageways..1Conception4.1Valves(1)CutoutValve截断阀(2)CheckValve止回阀(3)Safetyvalve安全阀(4)Regulatevalve调节阀(5)Flowdividervalve分流阀(6)PressureReducingValve减压阀(7)Exhaustvalve排气阀(8)FilterValve除污阀2categoryofvalves(1)BallValve（球阀）foron/offcontrolwithoutpressuredropidealforquickshut-offsincea90ºturnmostmanualvalves.4.1Valves(2)PlugValve（旋塞阀）4.1Valvesrotatedinsidethevalvebodytocontrolflowthroughthevalveforon/offcontrolwithpressuredropsimpleandofteneconomical(3)ButterflyValve（蝶阀）forflowregulationinlargepipediameters.Theclosingmechanismtakestheformofadisk.forquickshutoffwithpressuredrop4.1Valves(4)GateValve（闸阀）opensbyliftingaroundorrectangulargateoutofthepathofthefluid.Thegatefacescanformawedgeshapeortheycanbeparallel.Typicalgatevalvesshouldneverbeusedforregulatingflow,unlesstheyarespecificallydesignedforthatpurpose.4.1Valves(5)DiaphragmValve（隔膜阀）Diaphragmconsistsofavalvebodywithtwoormoreports,adiaphragm,andasaddleorseatuponwhichthediaphragmclosesthevalve.Thevalveisconstructedfromeitherplasticorsteel.4.1Valves(6)CheckValve（止回阀）non-returnvalve,allowsthefluidtopassinonedirectiononly.Acheckvalveisamechanicaldevice,whichnormallyallowsfluidtoflowthroughitinonlyonedirection.Checkvalvesaretwo-portvalves,meaningtheyhavetwoopeningsinthebody,oneforfluidtoenterandtheotherforfluidtoleave.Therearevarioustypesofcheckvalvesusedinawidevarietyofapplications.checkvalvesgenerallyareverysmall,simple,and/orinexpensive.4.1Valves(7)GlobalValve（截止阀）goodforregulatingflow4.1Valvesglobalvalveisatypeofvalveusedforregulatingflowinapipeline,consistingofamovabledisk-typeelementandastationaryringseatinagenerallysphericalbody(8)SafetyValve（安全阀）operatesautomaticallyatasetdifferentialpressuretocorrectapotentiallydangeroussituation,typicallyover-pressure4.1Valves(9)Flowdividervalve（分流阀）Aflow-dividervalveisaformofpressure-compensatedflow-controlvalvethatreceivesoneinputflowandsplitsitintotwo（multiple）outputflows.4.1Valves(10)PressureReducingValve（减压阀）Apressureregulatorisavalvethatautomaticallycutsofftheflowofaliquidorgasatacertainpressure.Regulatorsareusedtoallowhigh-pressurefluidsupplylinesbereducedtosafepressures4.1Valves(11)FilterValve（除污阀）4.1Valves(12)ExhaustValve（排气阀）4.1ValvesStructureofthecourse•4IntroductiontoSensorandActuator4.1Valves4.2controlvalvesanddampers4.3Actuators4.4SensorsIntroductiontoSensorandActuator4.2ControlValvesandDampers1ControlValvesControlvalvesandcontroldampersarethetwoprimarymeanstocontroltheflowofwaterandairinHVACsystems.4.2ControlValvesandDampers1ControlValvescategoryofvalvesLineartypes：globevalves.Rotarytypes：includeballvalves,butterflyvalves,plugvalves.Port：two-portandthree-portvalves.4.2ControlValvesandDampers2TwoWayValves阀杆阀体阀帽4.2ControlValvesandDampers2TwoWayValvesThebody(阀体)，thebonnet(阀帽)，thevalveseat(阀座)andvalveplug(阀塞),ortrim(阀芯型面).thevalvespindle(阀杆)(whichconnectstotheactuator).thesealingarrangementbetweenthevalvestemandthebonnet.Flowthroughasingleseat,two-portglobevalve直通单座阀4.2ControlValvesandDampers2TwoWayValvestheforcerequiredfromtheactuatormaybedeterminedA=Valveseatingarea(m²)∆P=Differentialpressure(kPa)F=Closingforcerequired(kN)4.2ControlValvesandDampers2TwoWayValvesFlowthroughadoubleseat,two-portglobevalvetwoplugsandseatsarrangedfluiddifferentialpressureisbalancedandtheactuatordoesnothavetofightagainstdifferentialpressuretoclosethevalve.thevalvecannotprovidetightshut-off.ThisreducesitsapplicabilitytoHVACsystems,wheretightshut-offisusuallydesired,tominimizeenergycosts直通双座阀4.2ControlValvesandDampers2TwoWayValvesAsteamcontrolvalvewithpistonbalancing4.2ControlValvesandDampers2TwoWayValvesWedgegatevalveandparallelslidevalve(manualoperation)4.2ControlValvesandDampers2TwoWayValvesBallvalve(showninafullyopenposition)4.2ControlValvesandDampers2TwoWayValvesAsteamcontrolvalvewithpistonbalancing4.2ControlValvesandDampers2TwoWayValves4.2ControlValvesandDampers3ThreeWayValvesThree-portvalvescanbeusedforeithermixingordivertingservicedependingupontheplugandseatarrangementinsidethevalve.AsimpledefinitionofeachfunctionisshowninFigure4.2ControlValvesandDampers3ThreeWayValvesTherearethreebasictypesofthree-portvalve:Pistonvalvetype.Globeplugtype.RotatingshoetypeThistypeofvalvehasahollowpiston,whichismovedupanddownbytheactuator,coveringandcorrespondinglyuncoveringthetwo-portsAandB.PortAandportBhavethesameoverallfluidtransitareaand,atanytime,thecumulativecross-sectionalareaofbothisalwaysequal.Forinstance,ifportAis30%open,portBis70%open,andviceversa.Pistonvalvetype4.2ControlValvesandDampers3ThreeWayValvesHere,theactuatorpushesadiscorpairofvalveplugsbetweentwoseatsincreasingordecreasingtheflowthroughportsAandBinacorrespondingmanner.Globetypethree-portvalves4.2ControlValvesandDampers3ThreeWayValvesasingleseat,three-p