Patent ID: 6767449
Filing Date: 2004-07-27
Classification: G01N

Abstract:
A method for operating a sensor for determining the concentration of oxidizing gases in gas mixtures and especially for determining the nitrogen oxide concentration in exhaust gases of an internal combustion engine, the sensor including: a first chamber disposed in a solid state electrolyte, the chamber being connected to the gas mixture via a first diffusion barrier; a second chamber arranged in the solid state electrolyte and said second chamber having a pregivable constant oxygen partial pressure; an oxygen pump electrode subjected to the exhaust gas on the solid state electrolyte; a further oxygen pump electrode and a nitrogen oxide pump electrode in said first chamber; and, an oxygen reference electrode arranged said second chamber; the method comprising the steps of:applying voltages (U-IPE; U-O2; U-NO) to the oxygen pump electrode, further oxygen pump electrode and nitrogen oxide pump electrode, respectively, thereby generating respective pump currents; measuring one of said pump currents and outputting said one pump current as a measurement signal; and, changing said voltages (U-IPE, U-O2; U-NO), which are applied to the pump electrodes, in dependence upon factors which correspond to the characteristic resistances or conductivities between said electrodes, during operation of the sensor in such a manner that the voltages correspond to predetermined desired values in the interior of said sensor.