PURPOSE: To stably perform exhaust gas recircultion(EGR) by simplified constitution even in a high intake air amount region.
CONSTITUTION: Only a main supercharger 10 is supercharge-actuated in a low intake air amount region, and both the main/subsuperchargers 10, 11 are supercharge-actuated in a high intake air amount region. A negative pressure passage 89, for taking out an intake negative pressure in the downstream of a throttle valve 4 introduced as a working pressure to a diaphragm chamber of an EGR valve 84, is provided. A pressure passage 102, for taking out an outlet pressure of the subsupercharger 11 introduced as a working pressure to a diaphragm lower chamber of the EGR valve 84, is provided. In the low intake air amount region, the intake negative pressure in the downstream of the throttle valve 4 is introduced to the EGR valve 84, and it is actuated opened in proportion to the intake negative pressure to perform EGR. On the other hand in the high intake air amount region, the outlet pressure of the subsupercharger 11 is generated positive, connected to the pressure passage 102 and introduced to the EGR valve 84, and it is open-actuated to perform the EGR.
YOSHIOKA MAMORU
SUGIYAMA TOSHIHISA
KANTO YUJI
KIDOKORO TORU
