James Sinnamon

A New Technique for Residual Gas Estimation and Modeling in Engines

This paper addresses the longstanding problems of residual gas measurement during engine dynamometer testing, and of real-time residual modeling for engine control applications. A new method is described which is simple to apply, requiring only currently standard calibration test cell instrumentation. Experimental validation against measurements using direct in-cylinder CO2 sampling is presented, and a comprehensive error sensitivity analysis is included. A real-time capable, controls-oriented model is also described. Its accuracy is assessed by comparison to engine-simulation-generated residual values after using these values to determine the model parameters.

Co-Simulation Analysis of Transient Response and Control for Engines with Variable Valvetrains

Modern engines are becoming highly complex, with several strongly interactive subsystems variable cam phasers on both intake and exhaust, along with various kinds of variable valve lift mechanisms. Isolated component models may not yield adequate information to deal with system-level interactive issues, especially when it comes to transient behavior. In addition, massive amounts of expensive experimental work will be required for optimization. Recent computing speed improvements are beginning to permit the use of cosimulation to couple highly detailed and accurate submodels of the various engine components, each created using the most appropriate available simulation package. This paper describes such a system model using GT-Power to model the engine, AMESim to model cam phasers and the engine lubrication system, and Matlab/Simulink to model the engine controllers and the vehicle. The simulation has been applied to examine fast transient response to throttle tip-in and tip-out maneuvers. After verifying the accuracy of the simulation against measured vehicle responses, various cam phaser control strategies were examined for their response to demand for engine torque and residual gas dilution. It was found that simple, conventional phaser control strategies such as position command using steady-state-based tables and phase-rate-limiting cannot provide sufficiently accurate dilution control. In order to extract the full fuel economy and emissions benefit from variable valvetrain systems, more accurate model-based control of residual gas fraction that is effective during fast transients is required. An approach to model-based dilution control is described and demonstrated.

Development of a Practical Tool for Residual Gas Estimation in IC Engines

ABSTRACT 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-