Patent ID: 6550237
Filing Date: 2003-04-22
Classification: F01N,F02D,Y02T

Abstract:
A system for monitoring exhaust gas conversion efficiency of a catalytic converter during operation of an internal combustion engine coupled to the catalytic converter, the system comprising:an upstream exhaust gas sensor interposed the engine and the catalytic converter for generating a first signal based on the exhaust gas upstream of the converter; a downstream exhaust gas sensor interposed the catalytic converter and atmosphere for generating a second signal based on the exhaust gas downstream of the converter; a phase shift detector for estimating a phase shift between the first and second signals; and a processor, for aligning the first and second signals such that the resulting phase shift between the first and second signals is substantially an integer multiple of &pgr; radians and for determining conversion efficiency of the catalytic converter based such phase aligned first and second signals.