| 摘要 |
PROBLEM TO BE SOLVED: To improve fuel economy and avoid torque shock during NOx reduction of NOx adsorption catalyst. SOLUTION: When NOx reduction control conditions are established during combustion in a lean state (S1, S2), the concentration of HC upstream of the NOx adsorption catalyst is detected, and purge flow rate of the evaporated fuel is controlled (S3, S4) based on the detected HC concentration such that the air/fuel ratio of the exhaust gas is adapted to the NOx reduction process by driving the pump disposed in a purge passage connecting a canister and an exhaust passage. After a predetermined elapse of time, the pump operation is stopped to stop purging.
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