Nomenklatur - im ZESS

Abstract
Abstract
The estimation of the air mass in the cylinder of a spark ignition (SI) engine is crucial in order
to regulate the exact air fuel (A/F) ratio for the catalyst and thus minimize the emissions. Conventional
algorithms for estimating the air mass are based on sensor information measured in
front of the throttle or in the manifold. Thus, the determination of cylinder individual sizes,
particularly the air mass, is impossible. In this work, new sensors, which provide cylinder individual
information are investigated and the air mass in each individual cylinder is calculated
with adaptive, model based algorithms.
Sensors within the combustion chamber of an SI engine enable a cylinder specific evaluation of
the thermodynamic work process. In particular, the combustion pressure sensor or ionisation
current sensing are two independent methods of measuring direct combustion information. In a
few cases such sensors are used in mass production cars.
The combustion pressure sensor exhibits two significant advantages when compared to ionisation
current. First, it provides information of the pressure in the cylinder during the complete
working cycle of the engine and this pressure information is a measure of the entire combustion
chamber. In contrast, the ionisation sensing represents a local measurement during the combustion
and part of the expansion phase and this measurement can only be seen as a part of the
information contained in the combustion pressure sensor signal.
Second, the determination of the air mass in the cylinder, the most significant process information,
can only be determined by cylinder pressure measurements and not by ionisation current.
Reducing costs by eliminating the mass air flow meter is a requirement for the implementation
of combustion pressure sensors in a mass production throttled SI engine. Thus, the cylinder
pressure sensor must be able to determine the air mass in the cylinder. However, the cylinder
pressure sensors will not be implemented in a mass production application based only on replacing
the mass air flow meter, but must in addition provide much more cylinder specific information.
This might change in future with new engine concepts.
Model based methods require an exact knowledge of the parameters of the physically based
model. For the estimation of states, based on these models, the accuracy of the estimated results
depends strongly on exact parameter determination. In contrast to an Extended Kalman-
VIII