Air leakage diagnosis in heavy duty truck engines with EGR and VGT
Scania CV AB is a leading company within development and production of
buses, trucks as well as industrial and marine engines.
New environmental and safety legislations continuously demand higher
quality from the products. An upcoming European legislation, Euro 6,
implies that gas leakages from truck engines should be detected while
driving. If the source of the leakage is not only detected, but also
isolated, that is separated from other faults, the adjustments in the
workshop goes faster since there is no need for leakage
localisation. A faster reparation increases the up-time, i.e. the
amount of time that the truck can be used.
This master thesis work uses current methods developed at Scania for
residual generation to perform model-based leakage diagnosis. In this
work, measurements are gathered for different sensor faults and two
leakages. The measurements are used to evaluate the actual performance
of the resulting diagnosis system.
The result, based on the residuals generated by the method, shows that
leakages on the boost-side and the exhaust-side can be detected, and
isolated from faults in the pressure sensors on the boost-side and the
exhaust-side. The isolation of these four faults is considered the
hardest to achieve among sensor faults and leakages why the full
isolation performance is promising. Further measurements are needed to
determine the full isolation performance of the diagnosis system.
The resulting system is reasoned to be suitable for execution in real
time on-board the truck.
Josef Dagsson and Samuel Källström
2009
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