Patent ID: 8453433

Claim:
An exhaust purification device of an internal combustion engine including a NOx purification catalyst that is provided in an exhaust channel of the internal combustion engine and that, with an air/fuel ratio of exhaust flowing in the exhaust channel as an exhaust air/fuel ratio, adsorbs or occludes NOx in exhaust when the exhaust air/fuel ratio is made lean, and reduces the NOx adsorbed or occluded when the exhaust air/fuel ratio is made rich, the exhaust purification device comprising: a catalytic converter that is provided in the exhaust channel on an upstream side from the NOx purification catalyst, and continuously reduces NOx in exhaust using a reducing gas; a fuel reformer that is provided separately from the exhaust channel, produces a reducing gas containing hydrogen and carbon monoxide by reforming fuel, and supplies the reducing gas from an inlet provided in the exhaust channel upstream of the NOx purification catalyst and the catalytic converter into the exhaust channel; an intake amount control valve that is provided to an intake channel of the internal combustion engine; an exhaust recirculation amount control valve that is provided to an exhaust recirculation channel in which a portion of exhaust flowing through the exhaust channel is recirculated to the intake channel; a turbocharger that compresses intake air flowing through the intake channel; and an electronic control unit configured to adjust, while the exhaust air/fuel ratio is set to lean, an exhaust flow rate of exhaust flowing through the exhaust channel by supplying reducing gas from the fuel reformer and controlling at least one among the intake amount control valve, the exhaust recirculation amount control valve, and the turbocharger; a first temperature estimation means for estimating or detecting, with a temperature of the catalytic converter as a first catalyst temperature, the first catalyst temperature; and a second temperature estimation means for estimating or detecting, with a temperature of the NOx purification catalyst as a second catalyst temperature, the second catalyst temperature, wherein the electronic control unit includes: a first activation control that supplies reducing gas from the fuel reformer into the exhaust channel, in a case in which the estimated or detected first catalyst temperature is lower than a predetermined first judgment temperature, until the first catalyst temperature reaches the first judgment temperature, and a second activation control that supplies reducing gas from the fuel reformer into the exhaust channel, in a case in which, after the estimated or detected first catalyst temperature has reached the first judgment temperature, the estimated or detected second catalyst temperature is lower than a predetermined second judgment temperature, until the second catalyst temperature reaches the second judgment temperature.