| abstract |
In an internal combustion engine of the present invention, an exhaust purification catalyst ( 13 ) and a hydrocarbon supply valve ( 15 ) are disposed in an engine exhaust path, and NO x contained in exhaust gas is purified by injecting hydrocarbon from the hydrocarbon supply valve ( 15 ) at a predetermined cycle. With respect to the injection amount per unit time of the hydrocarbon from the hydrocarbon supply valve ( 15 ), there is a difference provided between the first half and the second half of one injection time period, and in the first-half injection time period (Y), the injection amount per unit time of hydrocarbon is made to be less as compared to the second-half injection time period (X). |