System and method for estimating and controlling cylinder air charge in a direct injection internal combustion engine

A method for controlling cylinder charge in a direct-injection, spark-ignition engine, such engine including an intake manifold and an electronically controlled throttle (ETC) valve for controlling air flow from the atmosphere to the intake manifold of said engine, such method comprising:

• parameterizing air flow through the ETC valve as:
• Wthr=βthr0+βthr1{overscore (W)}thr
• where:
• βthr0 and βthr1 are estimator parameters;
• {overscore (W)}thr is a nominal predicted flow through the ETC valve, such predicted flow being a function of measured ETC valve position and measured intake manifold pressure;
• determining differences between the measured flow through the ETC valve and the predicted flow through the ETC valve;
• modifying the estimator parameters in accordance with the determined differences;
• and
• providing a desired air flow through the ETC valve by adjusting the ETC valve position, Uthr, in accordance with the parameterized air flow, such parameterized air flow being a function of the estimator parameters.

A method for controlling air charge in a direct-injection, spark-ignition engine, such engine having an exhaust gas recirculation (EGR) valve connecting the exhaust manifold and intake manifold of the engine and an electronically controlled throttle (ETC) valve controlling air flow from the atmosphere to the intake manifold of said engine, such method comprising:

• (A) providing an estimator for estimating flow through the EGR valve;
• (B) during a calibration mode:
• (i) applying a step function to the estimator, such estimator having a dynamic response characteristic to the applied step function, such dynamic response characteristic being a function of a parameter in such estimator;
• (ii) comparing the dynamic response characteristic of the estimator to the step function to the dynamic response characteristic provided in accordance with the orifice equation applied to the intake throttle and the EGR valve;
• and
• (iii) adjusting the parameter of the estimator to a value where the dynamic response characteristic provided by the estimator to the dynamic response characteristic provided by the estimator are substantially match to a predetermined response;
• and
• (C) during a subsequent normal operating mode:
• (i) removing the step function;
• and
• (ii) using the estimator value to estimate flow through the EGR valve.

A method for controlling air charge in a direct-injection, spark-ignition engine, such engine having an exhaust gas recirculation (EGR) valve connecting the exhaust manifold and intake manifold of the engine and an electronically controlled throttle (ETC) valve controlling air flow from the atmosphere to the intake manifold of said engine, such method comprising:

• (A) measuring an intake manifold pressure value which is indicative of measured intake manifold pressure;
• (B) estimating flow into the cylinder as a function of the measured intake manifold pressure;
• (C) modifying the estimated flow into the cylinder with a time varying multiplier;
• and
• (D) determining, when the EGR valve is opened, the time varying multiplier as a function of the difference between measured flow through the ETC and the modified estimated flow into the cylinder with a previously determined multiplier.