| 摘要 |
<P>PROBLEM TO BE SOLVED: To carry out exhaust gas recirculation (EGR) by effectively utilizing an exhaust turbo type supercharger for intake super charging even in a state that the pressure in an intake passage is made high because of the burning of deposit on an EGR cooler using a high temperature EGR gas. <P>SOLUTION: A turbine 23b of a second supercharger 23 is arranged in the upstream side of a turbine 22b of a first supercharger 22. An exhaust gas takeoff connection of the EGR passage 50 arranged in the EGR cooler 51 exists in the upstream side of the turbine 23b. When a revolution speed is equal to or above a first predetermined revolution speed R1 in which a waste gate valve 36 provided in the first supercharger 22 is opened, the waste gate valve 36 is temporarily closed to increase the internal pressure of the exhaust passage to permit the EGR. When the revolution speed is equal to or above a second predetermined revolution speed R2 (<R1), a bypass passage 33 bypassing the turbine 23b which is once opened is temporarily closed to increase the exhaust passage internal pressure to permit the EGR. <P>COPYRIGHT: (C)2012,JPO&INPIT |
