METHOD FOR UPGRADING EXHAUST GAS QUALITY DETERIORATED BY ADVERSE EFFECT OF SULFUR IN COMBUSTION PROCESS WITH HELP OF EXHAUST GAS CATALYST

摘要

PROBLEM TO BE SOLVED: To enable a catalyst to be regenerated without secondary adverse effects such as the generation of an obnoxious smell, an increase in fuel consumption and the worsening of a riding comfort by either increasing an exhaust gas temperature or generating an exhaust gas composition with a reduction action forward of the catalyst, when the oxygen storing capacity of the catalyst is below the threshold value. SOLUTION: An internal combustion engine 1 comprises a catalyst 2, a plurality of exhaust gas sensors 3, 4, a control device 5, a fuel supply means 6 and various kinds of sensor 7-9 which detect operating parameters such as a load L, a rotary velocity (n) and a temperature T. In addition, the catalyst 2 is structured of a first part 2a as an NOx storing catalyst and a second part 2b as a composite oxygen storing catalyst and the like. Further, the control of the NOx storing catalyst 2a is performed based on the degree of filling the catalyst with nitrogen at the time of calculation by the control device 5 according to the calculation. When the degree of filling the catalyst with nitrogen reaches a specified threshold value to the emission of NOx behind the catalyst, the storing process is terminated and at the same time, the exhaust gas composition is switched to an enriched gas mixture in order to regenerate the NOx storing catalyst.