PURPOSE: To always maintain the amount of EGR at an appropriate amount, by mainly using the so-called external recirculated exhaust gas which is a part of exhaust gas recirculated into an intake-air passage through an EGR passage, and by combining therewith the so-called internal recirculated exhaust gas having a characteristic such that it decreases when an waste gate valve is opened.
CONSTITUTION: Between an intake-air passage 2 and an exhaust passage 3 there is disposed a pressure wave supercharger 4 incorporating a rotor provided therein with a plurality of radial partition walls. The pressure wave supercharger 4 is arranged such that the pressure wave energy of exhaust gas is transmitted to intake-air in association with the rotation of the rotor by an engine 1 to supercharge intake-air. In this arrangement, the exhaust part of passage 3 upstream of the exhaust inlet port 8 of the supercharger 4 is communicated with the part of the same downstream of the outlet post 9 of the supercharger 4 through a bypass passage 20 bypassing the supercharger 4. Further, a waste gate valve 21 is incorporated in the bypass passage 20. Further, there is provided a recirculation passage 22 for recirculating a part of exhaust gas into the intake-air passage 2, in which is disposed an EGR valve 23 that is controlled in its closing direction when the amount of exhaust gas recirculation demand is large but in its opening direction when the amount of exhaust gas recirculation demand is small.
MATSUOKA TAKESHI
HAMADA SHIGEKI
HITASE FUMIO
