It has long been recognized that internal combustion engines do not operate regularly or repeatably from cycle to cycle. This cyclic variability is caused by fueling differences, hydrodynamics and ignition characteristics and many other causes, and the presence of significant cyclic variability can have adverse effects on emissions quality, fuel economy and driveability (in the case of vehicles).
Most early statistical studies suggested that cyclic variability is random, that is, that each cycle's combustion performance is independent of previous cycles. Recently, several studies have shown deterministic coupling or chaotic dynamics to govern cyclic engine performance. The existence of determinism has important implications on the ability to control combustion performance, with subsequent benefits on emissions and fuel economy, from cycle to cycle.
The CRG has studied internal combustion engines since 1992. Current areas of interest are signal-processing methods, modelling and control. Signal processing includes quantification of cyclic variability, state-space classification and dynamical prediction. The CRG is collaborating with industrial, government and academic partners to implement chaos control techniques on production spark-ignition engines.
(1999-08-31) On 1999-07-13, a patent was awarded for Stuart Daw's work with the Ford Motor Company on a "Method of controlling cyclic variation in engine combustion". You may view the patent at the United States Patent and Trademark Office or download a PDF file from our site at this link (1133367 bytes).
We have compiled a "Bibliography of chaos and internal combustion engines" to assist in further research.
Primary contacts for this research area are: C.S. Daw, J.B. Green Jr., R.M. Wagner and C.E.A. Finney.
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Updated: 2001-12-27 ceaf