Regeneration process for catalysts placed in a multiflow internal combustion engine exhaust and accumulating nitrogen oxides, involves running the cylinder bank with a rich fuel/air mixture

摘要

Each catalyst is regenerated by running the respective cylinder bank with a rich fuel/air mixture to transform the accumulated NOx (nitrogen oxides) in a catalytic manner. In the collective exhaust pipe and each of the other (n-1) branches, the component concentration is raised to ensure regeneration is complete. The regeneration of one branch is finished before another is started. The exhaust has n branches each fed by a bank of cylinders containing at least one cylinder. Each bank has a catalyst accumulating NOx and the branches join downstream of the catalysts to form a collective exhaust pipe. The fuel/air mixture in the branch being regenerated is higher than that in the other branches and the rich mixture is stopped when the regeneration is complete. The concentration of NOx is raised in the collective exhaust and the O2 concentration is raised in the branches not being regenerated. The fuel/air mixture is made richer by the addition of extra fuel until a detector upstream of the catalyst indicates a corresponding lambda value for that bank of cylinders.