| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust system of an internal combustion engine capable of suppressing deterioration in a purification rate of NOx while suppressing variation of an output torque of an internal combustion engine associated with rich spike. SOLUTION: The exhaust system of the internal combustion engine is applied to the internal combustion engine having an exhaust gas recirculation device 9 which takes out part of the exhaust gas from an exhaust passage 4 as an EGR gas to introduce it into an intake passage 3, a filter 17 for reducing stored nitrogen oxides in the presence of fuel, and a fuel adding valve 18 which is disposed at an upstream side more than the position for taking out the EGR gas by the exhaust gas recirculation device 9, and can inject the fuel toward the filter 17. The fuel is injected from the fuel adding means, and the target air-fuel ratio is set to the lean side when the EGR rate is high compared to the case when the EGR rate is low so that the air-fuel ratio of the exhaust gas becomes a target air-fuel ratio by temporarily changing the air-fuel ratio of the exhaust gas to a rich side. COPYRIGHT: (C)2008,JPO&INPIT
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