EXHAUST EMISSION CONTROL DEVICE OF INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide an exhaust emission control device properly switching between an exhaust fuel addition valve and an exhaust recirculation passage with respect to an internal combustion engine having a storage and reduction type NOx catalyst according to an operating condition and a deterioration condition of the catalyst.

SOLUTION: In an operation range where an ordinate axis represents an injection quantity or torque and an abscissa axis represents an engine rotation speed, a high load and high rotation speed side is set to be a range where the exhaust recirculation passage is worked and a low load and low rotation speed side is set to be a range where the exhaust fuel addition valve is worked. A boundary 101 between both ranges is shifted to the low load and low rotation speed side 102 according as a degree of deterioration of the catalyst increases.

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