| 摘要 |
A system for estimating NOx content of exhaust gas produced by an internal combustion engine includes a control computer operable to estimate an exhaust temperature corresponding to temperature of exhaust gas produced by the engine, to determine an EGR fraction corresponding to a fractional amount of recirculated exhaust gas present in an air charge supplied to the engine, and to estimate an emissions index, corresponding to a fuel rate normalized, mass-based NOx concentration of the exhaust gas produced by the engine, as a function of the exhaust temperature and the EGR fraction. The control computer is further operable to determine a mass flow rate of fresh air entering the intake manifold and a fuel mass flow rate, and estimate the NOx content by volume of the exhaust gas produced by the engine as a function of charge mass flow value, the fuel mass flow value and the emissions index value.
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