Patent ID: 6153071
Filing Date: 2000-11-28
Classification: G01N

Abstract:
An oxygen sensor, for mounting in a stream of a gaseous medium capable of switching between rich and lean air/fuel ratios, the oxygen sensor comprising:an oxygen-ion conducting solid electrolyte body;a first electrode assembly including a first electrode, having a porosity to gases within the gaseous medium, in contact with the electrolyte body, and a first layer, having a porosity to gases within the gaseous medium, enclosing the first electrode to the electrolyte body;a second electrode assembly including a second electrode, having a porosity to gases within the gaseous medium, in contact with the electrolyte body and spaced from the first electrode, and a second layer, having a porosity to gases within the gaseous medium, enclosing the second electrode to the electrolyte body, with the second electrode assembly having a gas transmission time characteristic different from the first electrode assembly;a first lead electrically connected to the first electrode and extending therefrom;a second lead electrically connected to the second electrode and extending therefrom; andmeans, coupled between the first and second leads and forcing no current therebetween, for detecting a transient, oxygen-induced emf between the first and the second lead in response to the air/fuel ratio in the gaseous medium switching between the rich and lean air-fuel ratios, wherein the means further includes a latch, connected between the first lead and the second lead, for changing to and maintaining a positive signal after a switch from the lean to the rich air/fuel ratio has been sensed in the gaseous medium, and for changing to and maintaining a zero signal after a switch from the rich to the lean air/fuel ratio has been sensed.