Research Papers

Automotive Three-Way Catalyst Diagnostics with Experimental Results

[+] Author and Article Information
Brandon M. Dawson, Matthew A. Franchek, Karolos Grigoriadis

Department of Mechanical Engineering,  University of Houston, Houston, TX 77204

Robert W. McCabe, Mike Uhrich, Steve Smith

 Ford Motor Company, Dearborn, MI 48124

J. Dyn. Sys., Meas., Control 133(5), 051008 (Aug 05, 2011) (7 pages) doi:10.1115/1.4004041 History: Received November 24, 2008; Revised February 19, 2011; Published August 05, 2011; Online August 05, 2011

Presented is the model based diagnostics of a three-way catalyst (TWC). The proposed TWC model relates measurable engine inputs (engine air mass (AM) and catalyst temperature) to a metric that quantifies TWC oxygen storage capacity. The TWC model structure is based on the dynamics of the TWC and identified using orthogonal least squares (OLS). The model coefficients are estimated using an instrumental variables four step (IV4) approach. TWC diagnostics is realized by means of an information synthesis (IS) technique where changes in the adapted TWC model coefficients are utilized to estimate TWC health. The approach is experimentally validated on a federal test procedure (FTP) drive cycle for healthy (full useful life, FUL) and failed (threshold) TWCs. The results will show that a 100% accurate classification in TWC health estimation (FUL or threshold) is produced for the catalysts tested.

Copyright © 2011 by American Society of Mechanical Engineers
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Figure 1

KTWC estimates for differently conditioned TWCs: (a) green TWC, (b) aged TWC, and (c) damaged TWC

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Figure 2

Example of information synthesis fault space projections

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Figure 3

Actual KTWC vs. model KTWC for one 300 s window

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Figure 4

Model coefficients in the coefficient space for healthy, FUL, and threshold TWCs

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Figure 5

Reduced model normalized error vector coefficients shown with direction of fault



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