| 摘要 |
PURPOSE:To suppress the exhaust gas recirculation in a low rotation frequency and a high load operation condition in particular and to improve the combustion efficiency by providing two lines of suction passages whose suction and exhaust overlap periods are different each other, and using these suction passages selectively responding to the engine operation condition. CONSTITUTION:In a diesel engine of 2-intake valve, 1-exhaust valve type engine, branch passages provided to the other ends of the first and the second suction passages 5 and 6, whose one ends are connected to air cleaners, are connected to combustion chambers 1 to which swirl chambers 2 are linked and connected, and the first and second intake valves 7 and 8 are provided at the openings of the branch passages at the combustion chamber side. The opening timing of the second intake valves 8 is set earlier than that of the first intake valves 7, and the suction and exhaust overlap time of the second intake valves 8 side is set longer than that of the first intake valves 7 side. In the branch passages of the second suction passage 6, control valves 11 to close at least in a low rotation and a high load condition are provided, and an exhaust passage 9 and the downstream side from the control valves 11 of the branch passages of the second suction passage 6 are connected through an EGR passage 15.
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