Diagnostic process for an exhaust gas catalytic converter of a heat engine and vehicle using this process
AssigneePeugeot Citroen Automobiles SA
InventorsArnaud Audoin, Alain Sassi
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Abstract
The present invention pertains to a process for diagnosing a catalytic converter processing the exhaust gases of a heat engine using a trap that stores and then reduces the nitrogen oxides (NOx) contained in these gases, these reductions being actuated as a function of the storage capacity of the trap. According to the present invention, such a process is characterized in that the oxygen ratio present in the exhaust gases downstream of the trap is measured by a sensor, and in that the storage capacity of the trap is determined by considering the time needed for the sensor to detect a threshold oxygen ratio in these gases during a reduction of the nitrogen oxides (NOx).
Claims8
A process for diagnosing the oxidation capacity of a catalytic converter processing exhaust gases of a heat engine by means of a trap which stores and then reduces the nitrogen oxides (NOx) contained in these gases, the process comprising the steps of:
- determining the oxygen (O2) content of the exhaust gases downstream of the trap by means of a sensor located downstream from the trap, and
- determining, from a level of a lambda ON/OFF signal emitted by the sensor, a decrease in the oxidation capacity of the trap,
- wherein the decrease in the oxidation capacity of the trap is determined by detecting a reduction of the hydrocarbon oxidation rate of the trap (i) during a regeneration phase in rich mode and (ii) after a phase of removal of nitrogen oxides (NOx) stored in the trap has substantially ended,
- wherein the reduction of the hydrocarbon oxidation rate is detected by detecting a decrease in a maximum voltage of a lambda ON/OFF signal provided by a sensor located downstream of the trap (i) during a regeneration phase in rich mode and (ii) after a phase of removal of nitrogen oxides (NOx) stored in the trap has substantially ended,
- this maximum voltage being dependent on a quantity of non-oxidized hydrocarbons present in the exhaust gases downstream of the trap, such that a decrease in the maximum voltage of the lambda ON/OFF signal indicates a reduction of the hydrocarbon oxidation rate of the trap.
Dependencies are inferred from the claim text.