To highly precisely calculate the amount of PM deposited on the upstream side of a NOx storage catalyst in a diesel engine.
An ECU executes a step S130 of calculating the exhaust amount of PM in accordance with an engine revolution speed NE and a fuel injection amount Q and correcting the exhaust amount of the PM with the amount of air, a step S140 of detecting the addition amount of fuel in fuel addition control, a step S150 of calculating a NSR clogging rate r in accordance with the exhaust amount of the PM and the addition amount of the fuel, a step S160 of calculating the corrected NSR clogging rate r' by using a correction efficient which is greater when an incoming gas temperature in the NSR catalyst is lower than when it is higher, and a step S165 of integrating the NSR clogging rate r' to calculate an integrated NSR clogging rate R'. When the integrated NSR clogging rate R' is a determined threshold value or greater (YES in S170), burn-up processing is executed.
YAMAMOTO YUKIHISA
HIRAI TARO
TOYOTA IND CORP
DENSO CORP
Toshio Morita
Tadashi Muto