EXHAUST PURIFICATION DEVICE FOR INTERNAL COMBUSTION ENGINE

摘要

In the present invention, an exhaust purification catalyst (13) and a hydrocarbon supply valve (15) are arranged in the engine exhaust passage of an internal combustion engine, and a low-pressure exhaust gas recirculation device (LPL) that recirculates exhaust gas downstream from the exhaust purification catalyst (13) is provided. When hydrocarbons are injected from the hydrocarbon supply valve (15), carbon dioxide generated in the exhaust purification catalyst (13) is recirculated, and the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst (13) decreases temporarily. Hydrocarbons are injected from the hydrocarbon supply valve (15) in synchronization with this temporary decrease in the air-fuel ratio.