| 摘要 |
PROBLEM TO BE SOLVED: To provide an exhaust gas cleaning apparatus for internal combustion engine for reducing a difference of the torque between a lean-burn mode and a rich-burn mode. SOLUTION: During the shifting from a lean-burn mode to a rich-burn mode, the weight of oxygen inside a cylinder is computed (S20), an excess air ratio is computed by using the weight of oxygen inside the cylinder (S30), and a rate of combustion is computed (S40). In the final fuel injection during the lean period, a torque value corresponding to the burning quantity of fuel is computed, and the obtained value is used as a target torque correspondent value in the rich period (S60). In the case wherein the excess air ratio is not less than 1, probability of danger in a torque shock is determined large, and the injection quantity for achieving a torque correspondent value the same as that of the lean period is computed based on the rate of combustion obtained in S40 and the injection quantity obtained in S60 (S80). In the case wherein the excess air ratio is less than 1, probability of danger in a torque shock is determined small, and the injection quantity is set at a preset rich-time target injection quantity (S90). COPYRIGHT: (C)2009,JPO&INPIT
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