Patent ID: 8869515

Claim:
A method for controlling the treatment of NOx present in the exhaust line of an internal combustion engine, said system comprising an injector for introducing a reducing agent in the exhaust line upstream of the NOx reduction catalyst, the method comprising: estimating a treatment efficiency relative to a maximum conversion potential obtained if the ratio between the quantity of injected reducing agent and the NOx quantity in the exhaust gas meets a given ratio set point and if the mass of reducing agent stored in the reduction catalyst meets a given storage set point; estimating a mass of reducing agent is stored in the catalyst by integrating, as a function of time, the storage rate of the ammonia injected in the line and the depletion rate of the ammonia through NOx reaction; and wherein the depletion rate of the ammonia through the NOx reaction is estimated based on the NO 2 /NO ratio of the NOx as follows: If R NO2/NO <0.50, then R NH3/NOx =1; Otherwise, R NH ⁢ ⁢ 3 / NOx = 1 + 8 ⁢ ( R NO ⁢ ⁢ 2 / NO - 0.50 ) 1 + 6 ⁢ ( R NO ⁢ ⁢ 2 / NO - 0.50 ) , and adjusting the amount of reducing agent injected into the exhaust line based on the estimated efficiency.