Bosch_Oxygen_Sensor.pdf

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1、ThefirstoxygensensordevelopedbyBoschwasFigure1.Boschoxygensensor.installedinaVolvo240/260seriesvehicle25yearsago.oschdelivered10millionoxygensensorstotheU.S.Bmarketin1976andby1983thenumberhadrisento50lcontrolrange(catalystwindow)million.Today,Boschproduc

2、es33millionoxygensensorsperyear.1In1982BoschlaunchedtheheatedoxygensensorwhichNOxreachesfulloperabilityin30secondsafteracoldengineisEnginestarted.Thesensorisheatedto400oCandhasaservicelifeofemissionsHC160,000km,twiceaslongasthepreviousunheatedsensor.COIn

3、1994Boschdevelopedanoxygensensorwithaplanarceramicstructurethatisfullyfunctioning10secondsafterthevehicleisstarted.2COToday’soxygensensorNOEnginexOxygensensors(seeFigure1)arerequiredtodayduetotheHCemissionsincreasinglytoughexhaustemissionsandgohand-in-ha

4、ndwiththecatalyticconverters.Oneoxygensensorisusedintheexhaustbranchrightbeforethecatalyticconverter.Sometimesasecondoxygensensorisplacedintheexhaustsystemafterthe3catalyticconverterofaspark-ignitionenginetopermitopti-mumperformanceofthethree-waycatalyti

5、cconverters.l-sensorTheinformationobtainedfromthesensorsindicateshowvoltagecompletethecombustionprocessisinthecombustioncham-ber.Theoptimumreadingsareobtainedwhentheairtofuelratiois14.7toone.Thestoichiometricair/fuelratioisthemass0.9751.01.0251.05of14.7k

6、gofairto1kgofgasolinetheoreticallynecessaryforrichExcess-airfactorlleancompletecombustion.Theexcessairfactororairratio(l)indicatesthedeviationoftheactualair/fuelratiofromtheFigure2.Controlrangeandreductionsinexhaustunderthreetheoreticallyrequiredratio.l=

7、(actualinducedairmass)/scenarios.Number1iswithoutacatalyticconverter.Number2iswith(theoreticalairrequirement).acatalyticconverter.Number3istheloxygensensorvoltagecurve.ServiceTechMagazine/May2001131.Ceramiccoating2.Electrodes3.Contacts4.Housingcontacts1.

8、Porousprotectivelayer2.Externalelectrode5.Exhaustpipe6.Ceramicsupportshield(porous)3.Sensorlaminate4.Internalelectrode5.Referenceairlaminate7.Exhaustgas8.Ambientair6.Insulationlayer7.Heater8.Heaterlaminate9.Connectionconta