Power plants – Internal combustion engine with treatment or handling of... – Having means analyzing composition of exhaust gas
Reexamination Certificate
1999-11-23
2001-05-22
Argenbright, Tony M. (Department: 3747)
Power plants
Internal combustion engine with treatment or handling of...
Having means analyzing composition of exhaust gas
C060S285000, C123S674000, C123S696000, C701S109000
Reexamination Certificate
active
06233922
ABSTRACT:
TECHNICAL FIELD
This invention relates to closed-loop fuel control for an internal combustion engine, and more particularly to a control based on a system model and air/fuel (A/F) ratio error estimator.
BACKGROUND OF THE INVENTION
The need for precise control of A/F ratio in motor vehicles has let to the development of controllers in which all or a portion of the engine air flow and exhaust system dynamics are mathematically modeled to estimate the sensed A/F ratio, and to adaptively adjust both the model and the base fuel control based on deviations of the estimated A/F ratio from the sensed A/F ratio. See, for example, SAE Paper N. 950846, by Fekete, Guden and Powell, entitled Model-Based Air-Fuel Ratio Control of a Lean Multi-Cylinder Engine. However, such controls tend to be complex, and when updated in time with the engine firing events, present excessive computational throughput requirements at higher engine speeds. Accordingly, such control strategies tend to be cost-prohibitive for most applications.
SUMMARY OF THE INVENTION
The present invention is directed to an improved closed-loop feedback fuel control with a model-based A/F ratio estimator, wherein the estimator, controller and portions of the model are updated on a fixed time interval basis, thereby minimizing the impact of the control on event-based throughput. Engine transport delays and oxygen sensor dynamics are modeled to estimate the sensed A/F ratio, and the estimate is compared with the sensed A/F ratio to adaptively adjust the model and to develop a closed-loop adjustment of the commanded fuel amount. The engine transport delay model is carried out on an engine event basis, but the sensor dynamics model is carried out on a time basis to accurately reflect the analog nature of the sensor. The estimator and the controller are also carried out on a time basis to reduce throughput requirements. at higher engine speeds, and the control gain is scheduled to account for differences between the exhaust gas measurements, which occur at the engine event frequency, and the controller time update frequency.
The subject control strategy enables numerous control enhancements, including flexibility to topology variations (such as sensor placement, sensor type and sensor characteristics), ease of calibration, and the ability to easily calibrate and schedule A/F ratio perturbations for catalytic conversion efficiency optimization.
REFERENCES:
patent: 5390489 (1995-02-01), Kawai et al.
patent: 5524598 (1996-06-01), Hasegawa et al.
SAE Technical Paper 940972, “Model-Based Air-Fuel Ratio Control in Sl Engines with a Switch-Type EGO Sensor”, Alois Amstutz, et al.
SAE Technical Paper 950846, “Model-Based Air-Fuel Ratio Control of A Lean Multi-Cylinder Engine”, N. P. Fekete, et al.
Argenbright Tony M.
Cichosz Vincent A.
Delphi Technologies Inc.
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