Patent ID: 7159392

Claim:
An estimation device which estimates a particulate matter deposit amount in a diesel particulate filter provided in an exhaust passage of a diesel engine for a vehicle, comprising: a differential pressure sensor means which detects a differential pressure between an exhaust gas pressure in the exhaust passage upstream of the filter and an exhaust gas pressure in the exhaust passage downstream of the filter; a sensor means which detects a running condition of the diesel engine; a sensor means which detects a parameter associated with an exhaust gas flow rate in the filter; and a programmable controller programmed to: estimate the particulate matter deposit amount in the filter by applying a first estimation method in which the particulate matter deposit amount is estimated on the basis of the differential pressure, and a second estimation method in which a periodical increment in the particulate matter deposit amount is calculated on the basis of the running condition and the particulate matter deposit amount is calculated by accumulating the increment, selectively in accordance with the parameter; and set the particulate matter deposit amount estimated in the first estimation method as an initial value for starting accumulation when applying the second estimation method.