| 摘要 |
PROBLEM TO BE SOLVED: To prevent the temperature of the most downstream side hydrocarbon adsorbing catalyst of a plurality of catalysts arranged in series from early exceeding the temperature of hydrocarbon desorption during ignition timing delay angle control for early activating the catalyst by rising exhaust gas temperature, and to improve exhaust emission properties by sufficiently exercising hydrocarbon adsorbing capability of the hydrocarbon adsorbing catalyst. SOLUTION: When the catalyst is not activated during idling operation after the starting of an engine, it is checked whether or not the temperature of the most downstream-side catalyst exceeds a value TD equivalent to the HC desorption temperature (S204). In the case of TC≤TD, an ignition delay angle amount RIG is increased by each setting valueΔIGB until a delay angle limit value RIGLIMIT is reached (S205 to S207). In the case of TC>TD, the ignition delay angle amount RIG is decreased by each setting valueΔIGB (S208, S209). Thus, the HC adsorbing catalyst can be prevented from early having a temperature beyond the HC desorption temperature to improve the exhaust emission properties by sufficiently exercising the hydrocarbon adsorbing capability. COPYRIGHT: (C)2004,JPO
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