| 摘要 |
<P>PROBLEM TO BE SOLVED: To accurately control temperature of a catalyst while keeping back pressure of an engine low. <P>SOLUTION: A first exhaust passage 13a connected to a first cylinder group 1a is connected to a common exhaust passage 24 via a first exhaust branch channel 21a and a second exhaust branch channel 22a mutually connected in parallel, and a second exhaust passage 13b connected to a second cylinder group is connected to the common exhaust passage 24 via a first exhaust branch channel 21b and a second exhaust branch channel 22b mutually connected in parallel. NOx storage reduction catalyst 26 is arranged in the common exhaust passage 24. The exhaust control valve 28 is opened to make exhaust gas reaches the NOx storage reduction catalyst 26 via the first exhaust branch channels 21a, 21b and the second exhaust branch channels 22a, 22b during normal operation and the exhaust control valve 28 is closed to make exhaust gas reache the NOx storage reduction catalyst 26 via the first exhaust branch channels 21a, 21b when temperature of the NOx storage reduction catalyst 26 need to be raised. <P>COPYRIGHT: (C)2007,JPO&INPIT |
