Patent ID: 8434296

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, 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 operating state detection means for detecting an operating state of the internal combustion engine; an exhaust recirculation ratio estimation means for estimating an exhaust recirculation ratio of the internal combustion engine; and an electronic control unit configured to enrich the exhaust air/fuel ratio by selectively executing i) H 2 enrichment control that enriches the exhaust air/fuel ratio while supplying reducing gas from the fuel reformer into the exhaust channel, and ii) normal enrichment control that enriches the exhaust air/fuel ratio without supplying reducing gas from the fuel reformer into the exhaust channel, wherein the electronic control unit is configured to execute the H 2 enrichment control, in a case of an operating state detected by the operating state detection means being a high-load operating state or in a case of the exhaust recirculation ratio estimated by the exhaust recirculation ratio estimation means being smaller than a predetermined judgment value, and to execute the normal enrichment control, in a case of the detected operating state not being the high-load operating state and the estimated exhaust recirculation ratio being at least the predetermined judgment value.