STOCHASTIC MODELLING AND ESTIMATION FOR CYCLIC PRESSURE VARIATIONS IN SPARK IGNITION ENGINES

✍ Scribed by J.B. ROBERTS; J.C. PEYTON JONES; K.J. LANDSBOROUGH

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 407 KB
• Volume: 15
• Category: Article
• ISSN: 0888-3270
• DOI: 10.1006/mssp.2000.1374

✦ Synopsis

A new method of "tting linearised, parametric stochastic models of cycle-by-cycle variations of pressure, during the combustion region of a spark ignition petrol engine, is described. The technique is based on stochastically "tting the combustion models to the covariance function of the measured pressure #uctuations, obtained by averaging over the entire ensemble of measured cycles. Comparisons, for two speci"c combustion models, with corresponding results obtained by deterministic "tting on a cycle-by-cycle basis, show that the new method gives a similar degree of "t, but with much improved computational e$ciency. It is also demonstrated that the degree of "t to the data can be further improved by modelling the residual error between the data and the combustion models in terms of Chebyshev polynomials: the parameters in these polynomials may be determined by stochastic "tting. The technique has wider applications in the condition monitoring of rotating machinery.