Method to determine the oxygen storage capacity of a catalytic converter of an exhaust gas system of an internal combustion engine

A method to determine an oxygen storage capacity (OSC) of a catalytic converter of an exhaust gas system of an internal combustion engine;

• wherein the exhaust gas system comprises:
• an exhaust duct, along which the catalytic converter is housed;
• a lambda sensor housed along the exhaust duct downstream of the catalytic converter to detect a concentration of oxygen in exhaust gases;
• and
• an exhaust gas after-treatment system having a burner that introduces exhaust gases into the exhaust duct, wherein inside the burner there is defined a combustion chamber, which receives fresh air through a first supply circuit and fuel from a second supply circuit;
• the method comprises the steps of:
• a) determining whether the internal combustion engine is in a stop phase;
• b) controlling the first and the second supply circuit to the burner so as to obtain an objective lambda value (λOBJ), other than one;
• c) determining a delay with which the lambda sensor detects a change in the objective lambda value (λOBJ);
• d) calculating the oxygen storage capacity (OSC) of the catalytic converter using said delay using formula:
• O
• ⁢
• S
• ⁢
• C
• =
• M
• A
• ⁢
• F
• *
• 0.23
• *
• |
• 1
• -
• λ
• A
• ⁢
• V
• ⁢
• G
• |
• λ
• A
• ⁢
• V
• ⁢
• G
• *
• D
• λ
• wherein:
• MAF represents the mass flow rate of exhaust gases in a precatalyst;
• λAVG is the average lambda value;
• 0.23 represents (23%) of oxygen in the air;
• and
• Dλ represents the delay of a lambda probe;
• and
• e) controlling the exhaust gas after-treatment system so as to adjust the amount of fresh air in the first supply circuit and the fuel in the second supply circuit so as to achieve the objective lambda value (λOBJ) based on the calculated oxygen storage capacity (OSC).