To compatibly achieve in high-dimensional improvement of fuel economy by EGR and improvement of fuel economy by pumping loss reduction in an internal combustion engine with a supercharger including an EGR system.
This control device is for a diesel engine including a turbocharger 24, an EGR means executing EGR by using pressure difference between an exhaust gas passage 18 and an intake air passage 28, and a back pressure variable means variably setting a back pressure. The device includes a means acquiring an index value (first index value) of improvement of a fuel consumption rate by change of pumping loss when the back pressure is changed, a means acquiring an index value (second index value) of improvement of the fuel consumption rate accompanying a recirculation rate of exhaust gas recirculated by the EGR means when the back pressure is changed, a means acquiring a total of the first index value and the second index value, and a means controlling the back pressure variable means to maximize the total index value. Preferably, the back pressure is controlled by variably setting an opening of the WGV48.
Mamoru Takada
Hidekazu Onishi