| 摘要 |
PROBLEM TO BE SOLVED: To prevent the torque shock or deterioration of fuel consumption by injecting fuel directly into a combustion chamber during compression stroke so that the air-fuel ratio of an engine is close to a theoretical air-fuel ratio to execute a stratified combustion in the release of the occluded NOX from a NOX occlusion type catalytic device. SOLUTION: It is judged in an ECU 40 whether NOX is leaked or not from an exhaust emission purifying catalytic device 30 on the basis of the output of a NOX sensor 32. When the NOX to be occluded in an occlusion type NOX catalyst 30a is leaked, and the output from the NOX sensor 32 reaches a judgment threshold X1, resulting the judgment of YES, NOX purge is executed. Namely, the fuel regulated so that the air-fuel ratio of the engine is close to the theoretical air-fuel ratio is injected into a combustion chamber 8 through a fuel injection valve 6 in compression stroke to perform a stratified combustion. According to this, at the time of executing the stratified combustion in an extremely lean air-fuel ratio, this stratified combustion is kept to prevent a torque shock caused by the change of combustion form. |
