Optimal A/F Ratio Estimation Model (Synthetic UEGO) for SI Engine Cold Transient AFR Feedback Control
980798
02/23/1998
- Event
- Content
- 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.
- Pages
- 11
- 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.