Patent ID: 8413426

Claim:
A method of exhaust cleaning for an internal combustion engine which combusts a fuel which is periodically fed under a rich condition and a lean condition, the method comprising: a step for producing a reformed gas containing carbon monoxide by reforming the fuel of the internal combustion engine by a fuel reformer which is independently disposed from an exhaust flow path of the internal combustion engine; a step for adsorbing and reducing nitrogen oxides in an exhaust gas by supplying the reformed gas to the exhaust gas introduced into an exhaust converter which is disposed in the exhaust flow path and in which a catalyst for absorbing and reducing the nitrogen oxides is disposed; a step for setting an oxygen concentration in the exhaust gas in the exhaust flow part to be not more than 0.5% in a combustion under a rich condition and during a time of introducing the reformed gas; and a step for setting a temperature of the reformed gas introduced into the exhaust flow path to be higher than a temperature of the exhaust gas in the exhaust flow path into which the reformed gas is introduced, wherein the reformed gas is introduced into the exhaust flow path while an inlet temperature of the exhaust converter is not less than 200° C.