Method and system for estimating cylinder air charge for an internal combustion engine
A method is provided for estimating cylinder air charge in an internal combustion engine, such engine having a mass airflow (MAF) sensor and a manifold absolute pressure(MAP) sensor. The method provides such cylinder air charge estimation from signals produced primarily by the manifold absolute pressure sensor during engine transient conditions. During a transition period between the transient condition and a steady-state engine condition the method combines signals primarily from both the mass airflow sensor and the manifold absolute pressure sensor to provide such cylinder air charge estimation. During the steady-state condition, the method uses primarily only the mass airflow sensor to provide such cylinder air charge estimation. With such method, the cylinder air charge estimation method utilizes the advantages of both measurement sensors. When transient situation occurs, the engine controller utilizes measurements from MAP sensors (together with measurements from other less significant sensors) to produce the cylinder air charge estimation. When it is determined that the transient situation is converging to a steady state operation, a smoothing algorithm is employed to combine the measurements from both MAF and MAP sensors to produce the cylinder air charge estimation. Finally, when the engine is operating in steady state, only the MAF sensor (together with other less significant sensors) is used to produce the cylinder air charge estimation.
Ford Global Technologies, LLC
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John Ottavio Yonghua
Michelini Li