| 摘要 |
PURPOSE:To provide an exhaust emission control device for vehicle for sufficiently achieving the NOx reduction function of a lean NOx catalyst by making HC concentration in exhaust gas higher than NOx concentration. CONSTITUTION:A canister purge line 9 for communicating between an exhaust gas upstream part 4a, which is in the exhaust upstream part of a lean NOx catalyst 7 provided on the exhaust system of an engine 2 for lean combustion, for which fuel injection timing is controlled by an engine control unit 3, and a canister 6 via a pump 10, is provided, and an air fuel ratio sensor 11, an HC concentration sensor 12, and an NOx concentration sensor 13 are provided on the exhaust pipe upstream part 4a which is in the exhaust upstream part of the lean NOx catalyst 7. Fuel injection timing is delayed based on these detection signals by the engine control unit 3 as first step control when the HC concentration is lower than the NOx concentration in an air fuel ratio lean region, and the HC concentration is made to be higher than the NOx concentration by driving the pump 10 of the canister purge line 9 as second step control.
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