Trimming two-point exhaust gas sensor indication, to compensate behavioral shift due to aging and poisoning

摘要

Amperometric sensor (1) comprises solid electrolyte (2) and measurement cell (4) determining oxygen concentration from the Nernst potential (V0) between its internal electrode (5) and a reference electrode (11) in ambient air. This is controlled by the oxygen ion pumping current (Ip0) between first electrode (5) and an outer electrode (6). A second measurement cell (8) connected to the first measures oxygen concentration as a second Nernst potential (V1) between a second electrode (9) and reference electrode (11). The two cells described are connected in series. The potential between outer (6) and reference (11) electrodes is sensed. This is used as the two-point signal for exhaust gas composition trimming. Preferred features: The further sensor is an amperometric, wide-band lambda sensor. The two-point characteristic signal is corrected as a function of the first oxygen ion pumping current (Ip0). The error voltage across the resistance (R0) passing the first oxygen ion pumping current (Ip0) is balanced out. The two-point characteristic signal dependent on oxygen concentration is also corrected for sensor (1) temperature.