Patent ID: 6103098
Filing Date: 2000-08-15
Classification: G01N

Abstract:
A method for detecting a change from lean to rich and rich to lean air/fuel ratio in the exhaust gas stream of an internal combustion engine comprising the steps of:positioning an oxygen sensor in the exhaust gas stream, the oxygen sensor being formed having an oxygen-ion conducting solid electrolyte body with a first electrode assembly and a second electrode assembly mounted thereon, wherein the second electrode assembly is arranged to have a predetermined time difference in a gas transmission characteristic from the first electrode assembly;periodically changing the air/fuel ratio of the exhaust gas stream from lean to rich and rich to lean;inducing emf output spikes by the electrode assemblies when the exhaust gas stream transitions between rich and lean air/fuel ratios;sensing the induced emf spikes output by the electrode assemblies;creating an output signal with a positive value when a positive emf spike is sensed;maintaining the output signal at the positive value until a negative emf spike is sensed;changing the output signal to a value of about zero when the negative emf spike is sensed; andmaintaining the output signal at the value of about zero until a positive emf spike is again sensed.