Abstract: In a method of controlling the combustion of a combustion engine from an estimation of the burnt gas mass fraction in the intake manifold, a measurement relative to a fresh air flow rate or to a burnt gas flow rate is performed upstream from the mixing space where fresh air and burnt gas mix. The burnt gas mass fraction present in the mixing space is then estimated from the measurement and from a model of the mixing dynamics in this space. A transport delay between the space and the intake manifold is estimated. The mass fraction of burnt gas in the intake manifold is then deduced in real time. Finally, combustion is controlled from the burnt gas mass fraction in the intake manifold.

Abstract: The invention relates to a method of controlling a combustion engine (1) comprising at least one cylinder (2) and a manifold (3) and an exhaust gas recirculation (EGR) circuit including an EGR valve. The EGR valve (6) is controlled by carrying out the following stages: a) measuring a pressure difference ?P in a portion of the exhaust gas recirculation circuit including the EGR valve; b) selecting a burnt gas fraction set point BGRsp in the intake manifold (3); c) calculating an opening set point for the EGR valve (6) from a pressure drop relation applied in a portion of the exhaust gas recirculation circuit including the EGR valve, depending on difference ?P at the EGR valve and on the burnt gas fraction set point BGRsp in the intake manifold; and d) controlling the EGR valve (6) as a function of the opening set point of EGR valve (6).