A new methodology for use in engine diagnostics and control, utilizing "synthetic" engine variables: Theoretical and experimental results

This paper describes new methodologies and algorithms for use in engine dia gnostics that, simplify and improve combustion quality monitoring and close d-loop engine control in order to meet stringent emission standards. The "s ynthetic" variables these algorithms produce can be used to indicate the wo rk produced by each cylinder combustion event at all engine speeds, and cal l be effectively used for on-board combustion quality measurements, engine diagnostics, and closed-loop control. The algorithms are very simple in for m, run in real time, and the methodologies call be applied to compression i gnition or spark, ignition, 2-stroke or 4-stroke gasoline or diesel engines . Both simulation and experimental results are given for a two-stroke, two- cylinder in-line engine. The rotational dynamics and firing sequence of thi s configuration of engine is very similar to a four-stroke, four cylinder i n-line engine, and nearly identical results will be seen with these two des igns. Even more dramatic improvements call be seen with engines of fewer cy linders because of greater variations in their inertial forces. The algorit hms can be successfully applied to many other engine configurations as well . Therefore, benefits call be derived from the application of these algorit hms and their "synthetic" variables to control strategies for almost all mo dern small and medium size automotive and marine engines, as well as utilit y engines used for lawn care, snow removal, and other similar applications.