| 摘要 |
PROBLEM TO BE SOLVED: To secure exhaust gas reflux quantity at a stratified combustion region and expand the stratified combustion region. SOLUTION: Operating conditions are read, and either stratified combustion or homogeneous combustion is determined (S101, S102). In the case of the stratified combustion, a check is made to see if boost pressure P exceeds the set value Pmin or not. In the case of P<=Pmin, normal EGR control via a first EGR passage is exercised (S104); in the case of P>Pmin, a second EGR valve and a control valve are operated to open, and exhaust gas is forcedly refluxed from a second EGR passage to an intake line using a second turbo-supercharger (S105). Thereby EGR flow rate is secured and the stratified combustion region is extended by forcedly refluxing exhaust gas from the second EGR passage to the intake line using the second turbo-supercharger, although the limit of the stratified combustion region was up to a region where throttle opening is close to a full-throttle, in the EGR control relying on conventional negative pressures of an intake pipe. |
