Patent ID: 7272926

Claim:
An exhaust emission control device for an internal combustion engine, the exhaust emission control device comprising: a particulate filter that traps exhaust particulates contained in exhaust gas discharged from an internal combustion engine body; and a sediment amount calculation means that calculates a sediment amount of exhaust particulates, which are trapped and accumulated by the particulate filter, for evaluating necessity of regeneration of the particulate filter in accordance with the sediment amount, wherein the sediment amount calculation means includes a first sediment calculation means and a second sediment amount calculation means, the first sediment calculation means calculates a first sediment amount in accordance with differential pressure between a front side of the particulate filter and a rear side of the particulate filter, and the second sediment amount calculation means calculates an amount of exhaust particulates discharged from the internal combustion engine body per unit of time in accordance with an operating state of the internal combustion engine body, the second sediment amount calculation means integrating the amount of exhaust particulates to calculate a second sediment amount, the exhaust emission control device further comprising: an abnormality evaluating means that evaluates presence and absence of an abnormality in flow of exhaust gas, which flows through the particulate filter, in accordance with a correspondence between the first sediment amount and the second sediment amount; a selection means that selects from the first sediment calculation means and the second sediment calculation means in accordance with the operating state of the internal combustion engine body for evaluating necessity of regeneration of the particulate filter, wherein the second sediment amount calculation means calculates the second sediment amount by integrating the amount of exhaust particulates, which are discharged from the internal combustion engine body, with the first sediment amount, which is calculated immediately before the sediment amount calculation means is switched from the first sediment calculation means, the abnormality evaluating means expresses the correspondence between the first sediment amount and the second sediment amount using a difference between the sediment amount calculated immediately before switchover, which is from the second sediment amount calculation means to the first sediment calculation means, and the sediment amount calculated immediately after the switchover from the second sediment amount calculation means to the first sediment calculation means, and when the difference between the first sediment amount and the second sediment amount is out of a predetermined reference range, the abnormality evaluating means determines the correspondence is not coordinated, and the abnormality evaluating means determines the particulate filter to be abnormal.