Simulation of Emission Related Faults on a Diesel Engine
Today's legislation on exhaust gas emissions for heavy
duty diesel (HDD) vehicles is more stringent than ever and will be
even more tough in the future. More over, in a few years HDD
vehicles have to be equipped with OBD (On-Board Diagnostics). This
place very high demands on the manufacturers to develop better
engines and strategies for OBD. As an aid in the process models can be used.
This thesis presents extensions of an existing diesel
engine model in Matlab/Simulink to be able to simulate emissions
during standardized european test cycles. Faults in the sensor and
actuator signals are implemented into the model to find out if
there is an increase or decrease in the emissions. This is used to
create a fault tree where it can be seen why predefined emission
thresholds are exceeded. The tree is an aid when
developing OBD.
The results from the simulations showed that almost no
faults made the emissions cross the thresholds. The only
interesting faults were faults in the ambient temperature sensor
and the injection angle actuator. This means that the OBD-system
only needs to monitor a few components which implies a smaller
system and less work
Magnus Adolfsson
2002
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