Wideband oxygen sensing method and apparatus

摘要

A method of determining an air:fuel ratio based on information from an oxygen sensor exposed to exhaust gases of a combustion process, and related systems. A constant current is supplied to an oxygen sensor that has both an n-type sensing circuit and a p-type sensing circuit that share a common electrode. The currents in the respective sensing circuits is determined and a temperature value representative of a temperature of the oxygen sensor is determined. Then, an air:fuel ratio is determined based on the determined currents and the temperature value. The combustion process may then be controlled based on the air:fuel ratio. The air:fuel ratio may be determined, using the same oxygen sensor, across a range of air:fuel values in both the rich and lean regions; as such, the oxygen sensor may act as a wideband oxygen sensor.

主权项

1. A method of determining an air:fuel ratio of a combustion process, the method comprising:
supplying, from a constant current source, a constant total sensing current to an oxygen sensing portion of an oxygen sensor, the oxygen sensing portion exposed to exhaust gases from the combustion process, wherein the oxygen sensor has an n-type sensing circuit and a p-type sensing circuit that share a common electrode, the sensing current being a sum of a first current in the n-type sensing circuit and a second current in the p-type sensing circuit; wherein the n-type sensing circuit comprises an n-type semiconducting layer; wherein the p-type sensing circuit comprises a p-type semiconducting layer; wherein the n-type semiconducting layer and the p-type semiconducting layer are disposed on the common electrode with a lateral gap between the n-type semiconducting layer and the p-type semiconducting layer; determining the first current in the n-type sensing circuit; determining the second current in the p-type sensing circuit; determining a temperature value representative of a temperature of the oxygen sensor; determining a first value representative of the air:fuel ratio of the combustion process based on the first current in the n-type sensing circuit, the second current in the p-type sensing circuit, and the temperature value.