| 摘要 |
PROBLEM TO BE SOLVED: To suppress decrease in capability of a ternary catalyst as much as possible during transition from a stoichiometric combustion mode to a lean combustion mode.SOLUTION: This engine combustion control system comprises: an air-fuel ratio adjusting means; a ternary catalyst; an oxygen concentration sensor; an excess air ratio estimation calculation part estimating an excess air ratio on the basis of a detection signal from the oxygen concentration sensor; and a fuel mode switching part switching a combustion mode of an engine between a stoichiometric combustion mode maintaining the excess air ratio in a stoichiometric range, a lean combustion mode maintaining the excess air ratio in a lean range, and a stoichiometric-lean combustion mode maintaining the excess air ratio in a stoichiometric-lean range causing the excess air ratio centering around a position shifted to a lean side and positioned at a stoichiometric side rather than the lean range. The combustion by the stoichiometric-lean combustion mode is performed before the transition from the stoichiometric combustion mode to the lean combustion mode. |
