Gm Global Technolgoy Operations, Inc.

Marco Petronzi

Igor Zanetti

Davide Francesco Mercuri

A method is provided to estimate NOconcentration in exhaust gas flowing through an exhaust pipe of an internal combustion engine. The exhaust pipe has a first section and a second section, and is equipped with an aftertreatment device located between the first section and the second section, and the method includes, but is not limited to determining a parameter related to a NOconcentration of exhaust gas flowing in the first section, determining an oxidization index expressive of a rate of NO contained in the exhaust gas which oxidizes into NOinside the aftertreatment device, and a reduction index expressive of a rate of NOcontained in the exhaust gas which is reduced into NO inside the aftertreatment device, and calculating a parameter related to a NOconcentration in the second section as a function of the parameter related to a NOconcentration in the first section and of the oxidization index and of the reduction index of the aftertreatment device.

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A method is provided for the determination of a NOx concentration value upstream of a Selective Catalytic Reduction (SCR) catalyst in a Diesel engine, the engine having an exhaust line, a Diesel Particulate Filter and a NOx concentration sensor downstream of the SCR catalyst, the method including, but is not limited to estimating the NOx concentration value upstream of the SCR catalyst as a function of at least two engine parameters, measuring the NOx concentration downstream of the SCR catalyst, calculating the difference Z(x, y) between the estimated NOx concentration value and the measured value and, in case the difference is higher than a predetermined threshold, correcting the estimated NOx concentration value with a NOx concentration correction value. The NOx concentration correction value is calculated using a correction map that correlates the at least two engine parameters and the difference Z(x, y) with the NOx concentration correction value.

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Turin, Italy

Marco Petronzi