温度传感器概述.docx
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温度传感器概述.docx
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温度传感器概述
OverviewofTemperatureSensor
Temperatureisafundamentalphysicalquantity,natureandtemperatureofalltheprocessesareallcloselyrelated.Temperaturesensoristhefirstdevelopmentofaclassofthemostwidelyusedsensors.Temperaturesensorofthemarketmuchhigherthantheothersensors.Fromtheearly17thcenturypeoplestartedtousethetemperaturemeasurement.Insemiconductortechnology,supportedthiscenturyhavedevelopedasemiconductorthermocouplesensor,PNjunctiontemperaturesensorandanintegratedtemperaturesensor.Accordingly,underthelawsofinteractionbetweenwavesandmatter,havedevelopedtheacoustictemperaturesensor,infraredsensorsandmicrowavesensors.
Conductorsoftwodifferentmaterials,suchasconnectedwitheachotheratsomepoint,theconnectionpointonheating,noheatingintheirpartofthepotentialdifferencewillappear.Thepotentialdifferencevaluesandnon-heatedpartsofthetemperaturemeasuringpoints,andthetwoconductormaterials.Thisphenomenoncanbeverywidetemperaturerangethere,ifaccuratemeasurementofthispotentialdifference,andthenmeasuretheambienttemperatureisnotheatingparts,wecanaccuratelyknowthetemperatureofhotspotsincrease.Becauseitmusthavetwoconductorsofdifferentmaterials,socalled"thermocouple."Thermocouplemadeofdifferentmaterialsusedindifferenttemperatureranges,
Theirsensitivityisalsodifferent.Thesensitivityofthethermocoupleishottemperatureincreases1℃,theoutputpotentialdifferenceofthevariation.Formostmetallicmaterialsintermsofsupportingthethermocouple,thevalueofabout5to40microV/℃between.
Thermocouplesensorhasitsownadvantagesanddisadvantages,itisrelativelylowsensitivity,susceptibletotheimpactofenvironmentalinterferencesignalisalsovulnerabletotheimpactofpre-amplifiertemperaturedrift,thereforenotsuitableformeasuringsmalltemperaturechanges.Sincethesensitivityofthethermocoupletemperaturesensorhasnothingtodowiththematerialthickness,withverythinmaterialmadeofthetemperaturesensorcan.Becauseofthethermocouplealsohasgoodductilityofmetalmaterials,suchdetailedtemperaturemeasurementdevicehashighresponsespeed,theprocessofrapidchangecanbemeasured.
Temperaturesensoristhemostdiversevarietyofsensorscommonlyusedinamodernformoftemperaturesensoristoosmall,soitismorewidelyusedpracticeinallareasofproduction,butalsoforourlivestoprovidethefacilitiesandfeaturesnumerous.
Therearefourmaintypesoftemperaturesensors:
thermocouples,thermistors,resistancetemperaturedetector(RTD)andICtemperaturesensors.ICtemperaturesensor,italsoincludesanalogoutputsanddigitaloutputoftwotypes.
Contacttemperaturesensorandmeasuredobjectdetectionpartofthegoodcontact,alsoknownasthermometer.
Thermometerthroughconductionorconvectionthermalequilibrium,sothatadirectindicationofthethermometerthatthetemperatureofthemeasuredobject.Generallyhighermeasurementaccuracy.Withinacertaintemperature,thethermometerisalsomeasurabletemperaturedistributionwithintheobject.Butforsports,smallobjectsorverysmallheatcapacity,theobjectwillhaveagreatermeasurementerror,commonlyusedinthermometersarebimetalthermometers,glassliquidthermometer,pressurethermometer,resistancethermometer,thermistor,andthermocoupleandsoon.Theyarewidelyusedinindustry,agriculture,commerceandotherdepartments.Indailylifepeopleoftenusethethermometer.
Oflowtemperaturetechnologyinnationaldefenseengineering,spacetechnology,metallurgy,electronics,food,medicineandoilandchemicalsectorandthewideruseofsuperconductingtechnologystudies,measuringthetemperatureof120Kthefollowinglow-temperaturethermometerhavebeendeveloped,suchaslowtemperaturegasthermometer,steampressurethermometer,acousticthermometer,paramagneticsaltthermometer,quantumthermometers,low-temperatureheatresistanceandlowtemperaturethermocoupleandsoon.Low-temperaturethermometerrequiredtemperaturesensingsmallsize,highaccuracy,reproducibilityandstability.Poroushighsilicaglasssinteredcarburizingcarburizingheatresistanceofglassisalow-temperaturethermometertemperaturesensingdevicescanbeusedtomeasuretherangeof1.6~300Ktemperature.
Non-contacttemperaturesensorsensitivecomponentsandthemeasuredobjectdoesnottoucheachother,alsoknownasnon-contactThermometer.Thisinstrumentcanbeusedtomeasuremovingobjects,smalltargetandheatcapacityofsmallorrapidtemperaturechanges(transient)objectsurfacetemperaturecanalsobeusedtomeasurethetemperatureofthetemperaturedistribution.Themostcommonformofnon-contactthermometerbasedonthebasiclawofblackbodyradiation,knownastheRadiationThermometer.Includingthebrightnessofradiationtemperaturemeasurementmethod(seeopticalpyrometer),radiation(seeRadiationPyrometer)andcolorimetry(seecolorimetricthermometer).
Varioustypesofradiationthermometrymethodcanonlydetectthecorrespondingbrightnesstemperature,radianttemperatureortheratioofcolortemperature.Onlyontheblackbody(donotabsorballtheradiationreflectedlightoftheobject)themeasuredtemperatureisthetruetemperature.Fordeterminationofthetruetemperatureoftheobject,itmustbemodifiedsurfaceemissivity.Thesurfaceemissivitydependsnotonlyontemperatureandwavelength,butalsowiththesurfacestate,suchasthecoatingandmicrostructure,itisdifficulttoaccuratelymeasure.Inautomatedproductionoftenrequirestheuseofradiationthermometrytomeasureorcontrolthesurfacetemperatureofcertainobjects,suchasthemetallurgyofthesteelrollingtemperature,rolltemperature,forging
Temperatureandavarietyofmoltenmetalinthesmeltingfurnaceorcrucibleinthetemperature.Inthesespecificcases,themeasurementofsurfaceemissivityisverydifficult.Thesolidsurfacetemperaturemeasurementandautomaticcontrol,canbeusedtomakeadditionalmirrorsurfacetobemeasuredtogetherwiththecompositionoftheblackbodycavity.Additionalradiationcanincreasetheeffectivesurfaceradiationmeasuredandtheeffectiveemissioncoefficient.Throughtheinstrumentusingtheeffectiveemissioncoefficientcorrespondingtothemeasuredtemperatureoftheamendment,eventuallygettherealmeasuredsurfacetemperature.Themosttypicalisthehemispheremirrorattachedmirror.Thesurfaceoftheballnearthecenterofdiffuseradiationmeasuredbythehemispheremirror
Reflectedbacktothesurfaceoftheformationofadditionalradiation,therebyenhancingtheeffectiveemissioncoefficient:
theformulaforthesurfaceemissivityε,ρforthemirrorreflectivity.Asfortherealgasandliquidmediumtemperatureradiationmeasurement,thetubecanbeinsertedtoacertaindepthofheat-resistantmaterialtoformablackbodycavitymethod.Calculatedbycalculatingthethermalequilibriumwiththemediaaftertheeffectiveemissioncoefficientofcylindricalcavity.Intheautomaticmeasurementandcontrolcanusethisvaluetotheendofthetestchambertemperature(mediumtemperature)toamendandgettherealtemperatureofthemedium.
Advantagesofnon-contacttemperaturemeasurement:
measuringtemperaturesensingtemperaturelimittheextentnotsubjecttotherestrictions,andthusthemaximumtemperaturecanbemeasuredinprinciple,nolimit.Fortemperaturesabove1800℃,mainlynon-contacttemperaturemeasurement.Withinfraredtechnology,radiationtemperaturegraduallyextendedfromthevisibletoinfrared,700℃ambienttemperatureuntilthefollowinghavebeenadopted,andhighresolution.
RTDtemperaturesensorclassification
1.Conductorthermalresistance
Platinumresistancetemperaturesensor
Copperresistancetemperaturesensor
Indiumresistancetemperaturesensor
Rh-Feresistancetemperaturesensor
Cobaltplatinumresistancetemperaturesensor
2.Semiconductorthermalresistance
Germaniumresistancetemperaturesensor
Carbonresistortemperaturesensors
Carbonglassresistortemperaturesensor
NTCthermistortemperaturesensor
Sensorstaticcharacteristics
Staticcharacteristicsofthesensorisonthestaticinputsignal,thesensoroutputandinputbetweenarelationship.Sincethenbothinputandoutput,andtime-independent,sotherelationshipbetweenthem,thatthesensorcanbeastaticcharacteristicofthealgebraicequationwithoutthetimevariable,orinputforthehorizontal,toitscorrespondingoutputforverticalaxisanddrawthecharacteristiccurve.Characterizationofthestaticsensors,themainparametersare:
linearity,sensitivity,hysteresis,repeatability,drift,etc..
(1)linearity:
thatsensoroutputandtheinputoftheactualrelationshipbetweenthedegreecurvedeviatedfromthefittedline.Definedasthefullscalerangeoftheactualperformancecurvewiththemaximumdeviationbetweenthefittedlineandthefullscaleoutputvalueoftheratio.
(2)Sensitivity:
Sensitivityisthestaticcharacteristicsofsensorsisanimportantindicator.Definedastheincrementaloutputandleadtothecorrespondinginputoftheincrementalratioofincrement.Ssaidwithsensitivity.
(3)hysteresis:
sensorinputfromsmalltolarge(positivestroke),andinputfrombigtosmall(anti-stroke)duringchangesinitsinput-outputcharacteristiccurvedoesnotcoincidewithahysteresisphenomenon.Forthesamesizeoftheinputsignal,sensoroutputsignalofthepositiveandnegativetravelsizearenotequal,thisdifferenceiscalledhysteresismargin.
(4)Repeatability:
Repeatabilityisthesensorintheinputdirectionbythe
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