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Methods for Cylinder Pressure Based Compression Ratio Estimation
Technical Paper
2006-01-0185
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Three methods for compression ratio estimation based on cylinder pressure traces are developed and evaluated for both motored and fired cycles. Two methods rely upon models of polytropic compression and expansion for the cylinder pressure. It is shown that they give a good estimate of the compression ratio, although the estimates are biased. A method based on a variable projection algorithm with a logarithmic norm of the cylinder pressure, which uses interpolation of polytropic models of the expansion and compression asymptotes, is recommended when computational time is an important issue. For motored cycles it yields the smallest bias and confidence intervals for these two methods. For firing cycles a user-specified weighting factor is needed during the combustion phase, which pays off in a smaller estimation bias but also a higher variance. The third method includes heat transfer, crevice effects, and a commonly used heat release model for firing cycles. This method estimates the compression ratio more accurately in terms of bias and variance. The method is more computationally demanding and thus recommended when estimation accuracy is the most important property. In order to estimate the compression ratio as accurately as possible, motored cycles with as high initial pressure as possible should be used.
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Citation
Klein, M. and Eriksson, L., "Methods for Cylinder Pressure Based Compression Ratio Estimation," SAE Technical Paper 2006-01-0185, 2006, https://doi.org/10.4271/2006-01-0185.Also In
References
- Drangel H. Olofsson E. Reinmann R. The variable compression (svc) and the combustion control (scc)-two ways to improve fuel economy and still comply with world-wide emission requirements 2002 SAE Technical Paper 2002-01-0996
- Amann C.A. Cylinder pressure measurement and its use in engine research 1985 SAE Technical Paper 852067
- Lancaster D. R. Krieger R. B. Lienesch J. H. Measurement and analysis of engine pressure data 1975 SAE Technical Paper 750026
- Björck Å. Numerical Methods for Least Squares Problems Siam 1996
- Klein M. Eriksson L. Å slund J. Compression ratio estimation based on cylinder pressure data Accepted for Control Engineering Practice 2005
- Gatowski J.A. Balles E.N. Chun K.M. Nelson F.E. Ekchian J.A. Heywood J.B. Heat release analysis of engine pressure data 1984 SAE Technical Paper 841359
- Gill P.E. Murray W. Wright M.H. Practical Optimization Academic Press 1981
- Heywood J. B. Internal Combustion Engine Fundamentals McGraw-Hill series in mechanical engineering McGraw-Hill 1988
- Eriksson L. Andersson I. An analytic model for cylinder pressure in a four stroke SI engine SAE Transactions, Journal of Engines, 2002-01-0371 111 3 September 2003
- Eriksson L. Nielsen L. Towards on-board engine calibration with feedback control incorporating combustion models and ion-sense at - Automatisierungstechnik 51 5 204 212 2003
- Vibe I.I. Brennverlauf und Kreisprocess von Verbennungsmotoren VEB Verlag Technik Berlin 1970
- Klein M. A specific heat ratio model and compression ratio estimation Vehicular Systems Linköping University 2004 http://www.fs.isy.liu.se/Publications
- Randolph A.L. Methods of processing cylinder-pressure transducer signals to maximize data accuracy 1990 SAE Technical Paper 900170
- Rassweiler G.M. Withrow L. Motion pictures of engine flames correlated with pressure cards SAE Technical Paper 800131 1938