Patent ID: 7794528

Claim:
An exhaust gas cleaning device for an internal combustion engine having a collector with porous partition walls in an exhaust system of the engine for collecting exhaust particulate matters contained in exhaust gas when the exhaust gas passes through pores in the partition walls of the collector, the exhaust gas cleaning device performing regeneration of the collector by causing combustion of the exhaust particulate matters deposited in the collector if a deposition amount of the exhaust particulate matters in the collector exceeds a predetermined value, the exhaust gas cleaning device comprising: sensors disposed to detect operating conditions of the collector and to provide corresponding output signals; an electronic control unit having at least one processor connected to receive said output signals and to control regeneration of the collector, said electronic control unit being configured to include: a first means that estimates a deposition amount of ash in the collector; a second means that estimates a deposition amount of exhaust particulate matters in the collector by using a pressure loss across the collector as an input for use with deposition characteristic data correlating exhaust particulate matter deposition amount with said pressure loss; and a third means that corrects the deposition characteristic data in accordance with the deposition amount of the ash such that the pressure loss increases in accordance with an increase of the deposition amount of the exhaust particulate matters in a first range extending from an initial point, at which the deposition amount of the exhaust particulate matters is zero, to a transitional point and such that the pressure loss increases more gradually in a second range, in which the deposition amount of the exhaust particulate matters is greater than the deposition amount at the transitional point than in the first range in accordance with the increase of the deposition amount of the exhaust particulate matters, and as the deposition amount of the ash increases, the transitional point is moved toward the initial point such that the pressure loss at the initial point increases as the deposition amount of the ash increases, and an increased ratio of pressure loss with respect to deposition amount of exhaust particulate matters in the second range increases as the deposition amount of ash increases.