| 摘要 |
In an internal combustion engine, a hydrocarbon feed valve (15) and an exhaust purification catalyst (13) are arranged in an engine exhaust passage. As rich control for making the air-fuel ratio of the exhaust gas which flows into the exhaust purification catalyst (13) rich, cylinder rich control for generating rich air-fuel ratio combustion gas in the cylinder and exhaust rich control for feeding hydrocarbons from the hydrocarbon feed valve (15) to make air-fuel ratio of the exhaust gas rich are used. When the air-fuel ratio of the exhaust gas which flows into the exhaust purification catalyst should be made rich, if the speed of the vehicle is lower than a predetermined speed and the gear position of the transmission is at a predetermined low speed gear position, exhaust rich control is used instead of cylinder rich control. |
