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System and method for diagnosing EGR performance using NOx sensor

United States Patent

6,666,201
December 23, 2003
View the Complete Patent at the US Patent & Trademark Office
A method and system for diagnosing a condition of an EGR valve used in an engine system. The EGR valve controls the portion exhaust gases produced by such engine system and fed back to an intake of such engine system. The engine system includes a NOx sensor for measuring NOx in such exhaust. The method includes: determining a time rate of change in NOx measured by the NOx sensor; comparing the determined time rate of change in the measured NOx with a predetermined expected time rate of change in measured NOx; and determining the condition of the EGR valve as a function of such comparison. The method also includes: determining from NOx measured by the NOx sensor and engine operating conditions indications of instances when samples of such measured NOx are greater than an expected maximum NOx level for such engine condition and less than an expected minimum NOx level for such engine condition; and determining the condition of the EGR valve as a function of a statistical analysis of such indications. The method includes determining whether the NOx sensor is faulty and wherein the EGR condition determining includes determining whether the NOx sensor is faulty.
Mazur; Christopher John (Canton, MI)
Ford Global Technologies, LLC (Dearborn, MI)
10/ 063,955
20030225503
May 29, 2002
This invention was made with Government support under Cooperative Agreement DE-FC26-01 NT41 103 awarded by the Department of Energy. The Government has certain rights in the invention.