EXHAUST GAS PURIFICATION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

摘要

An exhaust gas purification system is provided with a first fuel supply unit to supply fuel to exhaust gas flowing in an exhaust passage of the internal combustion engine by means of a supply valve arranged in the exhaust passage, and a second fuel supply unit to supply fuel to exhaust gas to be discharged to the exhaust passage by adjusting a fuel injection condition in the internal combustion engine, wherein in a temperature raising stage of the NOx selective catalytic reduction catalyst associated with the exhaust gas temperature raising processing, first control is performed in which fuel is supplied by the first fuel supply unit, and in a temperature holding stage of the NOx selective catalytic reduction catalyst associated with the exhaust gas temperature raising processing, at least second control is performed in which the ratio of an amount of fuel supply by the second fuel supply unit with respect to an amount of fuel supply by the first fuel supply unit becomes higher in comparison with that when performing the first control.