Wide-range temperature operating system for combustion gas oxygen sensor, and method

摘要

To compensate for temperature-dependent shift on the operating characteristics of an oxygen ion conductive sensor which tends to shift the operating characteristics towards the "lean" range (&lgr; 1) at low temperature, and towards the "rich" range (&lgr; 1) at high temperature, the pulses derived from the sensor are delayed or shifted such that the trailing edge of the pulses, representative of shift from lean to rich direction, is transmitted with delay; dependent on temperature, the shift from rich to lean is also transmitted with delay. The delays are obtained by timing circuits (9, 14) which have variable time delays, the time delay being controlled by a temperature signal (9a) derived by sensing a-c resistance of the sensor, split by a high-pass filter and rectified. The pulses are extended by extending the trailing edge of the pulse by a first timing stage (9) or foreshorten, thus delaying, the occurrence of the leading edge of the pulses by a second timing circuit (14), the respective pulses being logically combined in dependence on temperature determined by a comparator (18) with respect to a temperature level of, for example, 300° C.-400. degree. C. set point.