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Model Identification for the A/F Path of an SI Engine
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English
Abstract
Modern model-based control schemes and their application on different engines need mathematical models for the various dynamic subsystems of interest. Here, the fuel path of an SI engine is investigated. When the engine speed and the throttle angle are kept constant, the fuel path is excited only by the fuel injected. Taking the NO concentration of the exhaust gas as a measure for the air/fuel ratio, models are derived for the wall-wetting dynamics, the gas mixture, as well as for the air/fuel ratio sensor. When only the spark advance is excited, the gas flow dynamics can be studied.
A very fast NO measurement device is used as reference. Its time constant is below the segment time of one single cylinder (180° crank angle for a 4-cylinder engine), therefore its dynamics are much faster than the time constants of the systems investigated.
A model structure considering the muliplexing effects of the discrete operation of an engine is given for the fuel path of a BMW 1.8 liter engine. The exhaust system of this engine is specially designed such that all distances from each exhaust valve to the confluence point are equal.
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Onder, C., Roduner, C., and Geering, H., "Model Identification for the A/F Path of an SI Engine," SAE Technical Paper 970612, 1997, https://doi.org/10.4271/970612.Also In
References
- Baltisberger St. Ruhm K. Fast NO Measuring Device for Internal Combustion Engines SAE Paper 940962 (included in SAE special publication SP1014, New Technologies for Low Emissions Vehicle Testing) Detroit, MI 1994
- Pischinger R. et al. Springer-Verlag Wien 1989
- Kleinschmidt, W. 1974
- Turin R.C. Casartelli E.G.B. Geering H.P. A New Model for Fuel Supply Dynamics in an SI engine SAE Paper 940208 Detroit, MI 1994
- Onder Ch.H. Geering H.P. Measurement of the Wall-Wetting Dynamics of a Sequential Injection Spark Ignition Engine SAE Paper 940447 (included in SAE special publication SP-1015, Fuel Systems for Fuel Economy and Emissions) Detroit, MI 1994
- Onder Ch.H. Swiss Federal Institute of Technology (ETH) Zurich 1993
- Baltisberger Stephan Zürich 1996