Patent ID: 6119450
Filing Date: 2000-09-19
Classification: F01N,F02B

Abstract:
A process for purifying exhaust gases of an internal-combustion engine having an engine control system that permits a change between a lean operation and a rich operation, and having an exhaust gas purification system, wherein a .lambda.-probe, an SO.sub.x storage catalyst and an NO.sub.x storage catalyst are successively arranged in an exhaust gas line behind the engine, said process comprising:measuring a SO.sub.x storage capacity of the SO.sub.x storage catalyst;starting desulfurization of the SO.sub.x storage catalyst when the SO.sub.x storage capacity decreases below a preset value by changing the engine from lean operation to rich operation;feeding secondary air into the exhaust gas line in front of the .lambda.-probe;detecting a combustion air ratio of exhaust gases from the engine mixed with the secondary air by the .lambda.-probe;setting the combustion air ratio to a predetermined value;measuring a temperature existing in the SO.sub.x storage catalyst;setting the temperature existing in the SO.sub.x storage catalyst to a predetermined value; andwhen a predetermined threshold value for the SO.sub.x storage capacity is reached, terminating the desulfurization by changing the engine from rich operation to lean operation.