| 摘要 |
PROBLEM TO BE SOLVED: To make compatible both restraint of worsening in drivability caused by excessive exhaust gas recirculation volume(EGR volume) and restraint of worsening in NOx emission caused by insufficient EGR volume, in switching from stratified charge lean combustion to homogeneous charge combustion. SOLUTION: When a combustion mode is required to be switched from the stratified charge lean combustion by fuel injection in a compression stroke to the homogeneous charge combustion by fuel injection in an intake stroke, stratified charge stoichiometric combustion by both the intake stroke injection and the compression stroke injection is executed for a prescribed time before the switching from the compression stroke injection to the intake stroke injection in a fuel injection mode. In the stratified stoichiometric combustion, the worsening in the drivability by misfire accompanied to the excessive EGr volume is restrained since fuel is collected around an ignition plug 41 by the compression stroke injection. The worsening in the emission is restrained in the stratified charge stoichiometric combustion from being generated in accompaniment to the insufficient EGR volume, since NOx displacement is not increased with an increased degree of the stratified charge lean combustion. |
