Control Oriented Modeling of the Gas Exchange Process in Variable Cam Timing Engines
Variable cam timing engines pose new questions for engine
control system designers. The cam timing directly influences
cylinder air charge and residual mass fraction. Three
models that predict residual mass fraction are investigated
for a turbocharged dual independent Variable Cam Timing
(VCT) engine. The three models (Fox et. al. 1993, Ponti
et. al. 2002, and Mladek et. al. 2000) that all have real
time capabilities are evaluated and validated against data
from a crank angle based reference model. None of these
models have previously been validated to cover this engine
type.
It is shown that all three models can be extended to dual
independent VCT engines and that they also give a good
description of the residual gas fraction. However, it is
shown that the two most advanced models, based on a thermodynamic
energy balance, are very sensitive to the model
inputs and proper care must therefore be taken when these
models are used.
Per Öberg and Lars Eriksson
2006
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Last updated: 2021-11-10
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