Patent ID: 8489308

Claim:
A method for estimating oxygen concentration downstream a diesel oxidation catalyst within a diesel engine system comprising at least an intake manifold, a combustion chamber, an exhaust manifold, an exhaust line for channeling the exhaust gases from exhaust manifold to atmosphere, and the diesel oxidation catalyst located in the exhaust line upstream a diesel particulate filter, the method comprising: determining an unburned fuel mass flow ({dot over (m)} P , {dot over (m)} ANotTorqFormDOC ) ejected from the combustion chamber, determining an air mass fraction (f air em ) in the exhaust manifold; estimating an air mass fraction (f airDPF ) downstream the diesel oxidation catalyst as a function of said unburned fuel mass flow ({dot over (m)} P , {dot over (m)} ANotTorqFormDOC ) and said air mass fraction (f air em ) in the exhaust manifold; and estimating oxygen concentration downstream the diesel oxidation catalyst as a function of the estimated air mass fraction (f air DPF ) downstream the diesel oxidation catalyst.