Engine air/fuel control system with catalytic converter monitoring

U.S. Patent Number: 5381656

Abstract: A control system which controls engine air/fuel ratio and provides a measurement of efficiency in the catalytic converter coupled to the engine exhaust. Fuel delivered to the engine is adjusted by a feedback variable which is generated by integrating an output of an upstream exhaust gas oxygen sensor and trimmed by the output of a downstream exhaust gas oxygen sensor. For each cycle of the feedback variable, peak amplitude of the downstream sensor output is determined and squared. Similarly, the peak amplitude of the feedback variable for each of its cycles is squared. An indicating ratio of the square of the sum of the squares derived from the downstream sensor to the square of the sum of the squares derived from the feedback variable indicates converter efficiency.

Inventors: Orzel; Daniel V. (Westland, MI), Zimlich; Glenn A. (Dearborn Heights, MI), Truong; Tri T. (Inkster, MI)

Assignee: Ford Motor Company (Dearborn, MI)

Application Number: 08/127,153

Issued: 1995-01-17

Expired: 2007-01-17

Classes: 60/274 ; 123/674; 123/703; 60/276; 60/285

Field of search: 60/274,276,285,277 123/672,674,703

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