EXHAUST EMISSION CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To supply an appropriate amount of a reducing agent in accordance with a NOx amount trapped upon the regeneration of NOx trap ability of a NOx trap catalyst.

SOLUTION: In an exhaust passage of an engine, the NOx trap catalyst 17 is provided which traps NOx when an inflow exhaust air-fuel ratio is lean and which performs the desorption and reduction of NOx trapped when the inflow exhaust air-fuel ratio is stoichiometric or rich. A NOx sensor 19 is arranged to the downstream of the NOx trap catalyst 17. When a combustion air-fuel mixture of the engine is temporarily made rich and NOx desorption and reduction processing in the NOx trap catalyst 17 is performed, a rich control amount is varied depending on an output of the NOx sensor 19.

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