温度传感器概述Word格式文档下载.docx

温度传感器概述Word格式文档下载.docx

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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