INTERNAL COMBUSTION ENGINE EXHAUST GAS SYSTEM AND CONTROL METHOD OF THE SAME

摘要

An internal combustion engine exhaust gas system includes a filter (13) arranged in an exhaust passage (5) of the internal combustion engine (1), a fuel adding valve (14) which is arranged upstream of the filter (13) and supplies fuel into the exhaust passage (5), and a low-pressure exhaust gas recirculation apparatus that removes some of the exhaust gas from downstream of the filter (13) as EGR gas. An EGR rate is controlled taking into account the amount of fuel supplied by the fuel adding valve (14) such that an oxygen concentration of intake gas, which is drawn into a cylinder of the internal combustion engine in a state in which the EGR gas that is introduced by the low-pressure exhaust gas recirculation apparatus (15) is mixed with air introduced into an intake passage (4), is constant before and after fuel is supplied by the fuel adding valve (14).