| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce the number of fuel addition valves and to bring the mounting positions of the fuel addition valves close to an engine and moreover to positively eject NOx from an NOx absorbent disposed in a first exhaust passage. <P>SOLUTION: This exhaust emission control device for the internal combustion engine is provided with the first exhaust passage and a second exhaust passage branched from an exhaust passage of the internal combustion engine. NOx absorbents are arranged in the respective exhaust passages and arranged in series to each other. When NOx is to be ejected from the NOx absorbent in the first exhaust passage, for instance, the second exhaust passage is closed while opening the first exhaust passage, and then after the lapse of a first time Δt1a, fuel is added from the fuel addition valve and led into the first passage, and upon the lapse of a second time Δt2a from the fuel addition, the first exhaust passage is closed to keep the air-fuel ratio of exhaust gas in the first exhaust passage rich with fuel. Further, the first time Δt1a and the second time Δt2a when NOx is to be ejected from the NOx absorbent in the first exhaust passage, and a first time Δt1b and a second time Δt2b when NOx is to be ejected from the NOx absorbent in the second exhaust passage are set different from each other. <P>COPYRIGHT: (C)2007,JPO&INPIT |
