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As engines advance toward greater efficiency and lower emissions, there is increasing need for accurate real-time residual models for engine control. Both the formulation of real-time-capable models and the development of methods for measuring or estimating residuals during engine calibration have been difficult and longstanding problems. This paper describes development of a low-cost, easy-to-use tool for on-line residual estimation in all cylinders of an IC engine. The basic method, hardware required, and software structure are described. The residual estimation tool was applied to estimate residuals over the operating map in all cylinders of a six-cylinder direct-injection SI engine equipped with dual-independent phasers. The data was used to calibrate a real-time residual model integrated into the engine management system. Validation data confirming accuracy of the model are presented. INTRODUCTION Due to the urgent need to improve IC engine thermal efficiency, the control of internal residuals in engines has become increasingly important. For spark ignition engines at part load, it is desirable to operate at a total dilution (EGR + residual) level close to the combustion stability limit for optimum indicated efficiency, reduced pumping loss and reduced NOx emissions. For engines that rely on auto-ignition, such as diesel or HCCI, dilution needs to be controlled accurately to some desired level that balances efficiency, noise and emissions. Variable valve actuation, VVA, has become a common means to vary and control internal residuals. In recent years there has been significant effort toward the formulation of accurate real-time capable residual models for engine management systems (EMS)[1-14]. The physical process that determines residual in engines is a complex interaction between valve lift events and the pulsating pressures in both intake and exhaust manifolds. This complexity means that a real |
