Abstract: A method for determining cylinder air charge and/or cylinder burned gas for an internal combustion engine system. The engine system includes cylinders, each one of such cylinders having at least one intake valve and at least one exhaust valve in communication with such cylinder. The method determines one of a plurality of different scenarios, each one of the scenarios representing a geometrical relationship between opening and closing of the intake valve relative to closing of the exhaust valve. The cylinder air charge and/or cylinder burned gas is calculated in accordance with the determined one of the plurality of scenarios. In one embodiment, the engine system stores a plurality of different software modules. The method selects one of the plurality of software modules in accordance with the determined one of the plurality of scenarios. The cylinder air charge and/or cylinder burned gas calculation comprises executing the selected one of the modules.

Abstract: A method and system for controlling an engine having a turbocharger with at least two discrete positions and exhaust gas recirculation (EGR). The method includes producing a control signal to the turbocharger. The signal has two discrete levels. One of such levels is selected to provide a proper flow of air through the turbocharger to an intake of the engine and such selected level is modulated between such two levels over time to provide, over time, a proper pressure at an input of the EGR to enable a proper flow of exhaust gases from the exhaust of the engine through the EGR back to the intake of the engine. With such method, while there is relatively instantaneous control of the exhaust pressure at the input of the EGR, and hence proper instantaneous control of EGR flow through the EGR.

Abstract: A method and apparatus of controlling the airflow into a compression ignition engine having an exhaust gas recirculation (EGR) system and a variable geometry turbocharger (VGT). The control strategy includes the steps of measuring the intake manifold pressure and exhaust manifold pressure, and using these values, estimating the EGR flow fraction. The EGR flow fraction is then used in a proportional plus integral feedback control loop to generate position commands for the EGR valve. Similarly, the intake manifold pressure signal is used in a proportional plus integral feedback control loop to generate position commands for the VGT. In this way, the EGR valve is used to regulate the EGR flow fraction to a desired value and the VGT turbine is used to regulate the intake manifold pressure to a desired value.

Abstract: A method of controlling the airflow into a compression ignition engine having an EGR and a VGT is disclosed. The control strategy includes the steps of determining the engine speed and fueling rate and, retrieving desired values for the intake manifold pressure (P.sub.1 *) and compressor mass flow rate (W.sub.a *) as a function of the engine speed and fueling rate wherein the desired values P.sub.1 * and W.sub.a * correspond to desired values for the air-fuel ratio and burnt gas fraction at each engine operating point. The desired values are then compared against measured values for the intake pressure (P.sub.1) and mass airflow (W.sub.a) to generate an EGR valve position command and VGT guide vane position command as a function of the weighted sum of the differences between P.sub.1 and P.sub.1 *, and W.sub.a and W.sub.a *. These position commands are then applied to the EGR valve and turbocharger turbine guide vanes, respectively, to drive the EGR valve and VGT vanes to the respective desired positions.