| 摘要 |
PROBLEM TO BE SOLVED: To sufficiently reduce a stuffy noise generated when operating an exhaust brake while an output performance of engine in operating EGR is ensured. SOLUTION: A main valve 5a closed and operated at the time of operation of exhaust brake and an auxiliary valve 5b closed and operated when operating EGR are disposed at a suction passage 3 in series. A bottle neck degree of the suction passage 3 accompanying with a closing of the auxiliary valve 5b is lower than that of the suction passage 3 caused by a closing of the main valve 5a. Thereby, the bottle neck degree of the suction passage 3 at the time of operation of the exhaust brake and the bottleneck degree of the suction passage 3 at the time of operation of the EGR are made different.
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