Method of controlling a combustion engine from estimation of the burnt gas mass fraction in the intake manifold

A method of controlling the combustion of a combustion engine comprising at least one cylinder, an intake circuit including an intake manifold and a burnt gas recirculation circuit including an EGR valve, characterized in that it comprises the following stages:

• performing a measurement relative to a gas, fresh air or burnt gas, flow rate, upstream from a mixing space Vbp wherein fresh air and burnt gas mix,
• estimating a burnt gas mass fraction BGRbp present in said mixing space, from said measurement and a model of the mixing dynamics in said space,
• estimating a transport delay from said space to said intake manifold,
• estimating in real time a burnt gas mass fraction BGR(t) in the intake manifold from said estimation of the burnt gas mass fraction present in the mixing space and said transport delay,
• controlling the combustion from said burnt gas mass fraction BGR(t) in the intake manifold.