| 摘要 |
In an exhaust emission control system for an internal combustion engine (E), an exhaust gas recirculation device that operates so as to partially open an exhaust valve (17e) to introduce exhaust gas into a cylinder in an intake stroke is provided; a secondary air passage (71) capable of supplying secondary air to an exhaust passage is connected to the exhaust passage; and a one-way valve (73) opened by negative pressure applied from the cylinder to the exhaust passage following an operation of the exhaust gas recirculation device in the intake stroke is provided in the secondary air passage (70). Accordingly, it is possible to provide an exhaust emission control system for an internal combustion engine that allows secondary air to be supplied into an exhaust passage to reduce HC and CO concentrations and also a NOx concentration in an exhaust gas without using an air pump regardless of an exhaust system structure of the internal combustion engine. |
