| 摘要 |
The invention relates to a method and a circuit for operating a nitrogen oxide sensor, for determining the nitrogen oxide (NOx) concentration in a gaseous mixture, in particular in the exhaust gas treatment of a motor vehicle. An electric pump voltage (U_APE,IPE), producing a pump current (I_Pump), is applied between an inner pump electrode (IPE) and an outer pump electrode (APE) of a pump cell. By means of said pump voltage, a constant oxygen partial pressure is set in a first measuring gas chamber by the pumping in or out of oxygen. Said pump voltage (U_APE,IPE) is regulated, such that a constant voltage value occurs on electrodes of a concentration cell. A third NOx-sensitive electrode, arranged in a second measuring gas chamber, is operated as a second pump cell, in which a limiting pump current, indicating the NOx concentration, occurs. In order to minimize the oxygen influence on the measured NOx signal, the pump current (I_Pump) is switched off or limited in a controlled manner within a measuring time window (T_Mess) and the NOx concentration is recorded within said measuring time window (T_Mess). |
