Optimal A/F Ratio Estimation Model (Synthetic UEGO) for SI Engine Cold Transient AFR Feedback Control 980798
A new method to estimate instantaneous A/F ratio and use the estimation as a feedback signal to control AFR during cold transients, before the oxygen sensor is functional, has been realized by a on-board PCM for a vehicle with a 4.6L, V8, PFI engine [4, 6]. Different AFRs cause variations in flame propagation, causing fluctuations in the effective torque. When a known AFR disturbance is induced into an engine system, a corresponding crankshaft angular velocity fluctuation can be detected. A variable derived from this physical phenomenon can be used to characterize the problem. The optimal fuel perturbation signal is designed by a relaxation concept, and the system model is determined by employing a dual-direction screening multivariate stepwise regression analysis. The estimated AFR is used by the PCM in a closed loop control to correct the fuel during cold transients.
Citation: Tang, X., Asik, J., Meyer, G., and Samson, R., "Optimal A/F Ratio Estimation Model (Synthetic UEGO) for SI Engine Cold Transient AFR Feedback Control," SAE Technical Paper 980798, 1998, https://doi.org/10.4271/980798. Download Citation
Xiaoguo Tang, Joseph R. Asik, Garth M. Meyer, Rogelio G. Samson
Ford Motor Co.
International Congress & Exposition
Electronic Engine Control Technologies-PT-73, Electronic Engine Controls 1998: Diagnostics and Controls-SP-1357, SAE 1998 Transactions - Journal of Engines-V107-3