EXHAUST EMISSION CONTROL DEVICE FOR ENGINE, AND PARTICULATE ACCUMULATION STATE DETERMINATION METHOD FOR PARTICULATE COLLECTION FILTER

摘要

PROBLEM TO BE SOLVED: To correctly estimate a particulate accumulation amount in a particulate collection filter of a diesel engine in view of combustion of particulates by NOx.

SOLUTION: An exhaust particulate emission amount per unit time of an engine is acquired in reference to a map (S203) from output of an engine (S202) and an exhaust air-fuel ratio (S203). A basic value of a combustion speed of exhaust particulates by NOx is acquired in reference to a map (S206). A NOx adsorption rate in a NOx trap catalyst is acquired (S211 to S216), and a correction coefficient is acquired in reference to a map (S217) from the NOx adsorption rate and the exhaust air-fuel ratio, and the basic value of the combustion speed is multiplied by the correction coefficient (S207). The corrected combustion speed is subtracted from the exhaust particulate emission amount to calculate exhaust particulate increase/decrease amounts per unit time, and the exhaust particulate increase/decrease amounts are sequentially integrated (S224) to calculate the exhaust particulate accumulation amount (S227).

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