| 摘要 |
PURPOSE:To improve driving performance under low and intermediate loads for higher thermal efficiency in a dual suction system internal combustion engine by placing an EGR valve under control of both a negative pressure in a primary suction passage and a negative pressure in a secondary suction passage. CONSTITUTION:A passage 23 which is communicated with a primary negative pressure port 11 in the vicinity of a primary throttle valve 7 of a primary suction passage 1 for low load is connected to the first EGR valve 21. A passage 27 is connected to the second EGR valve 22, which is communicated by the passage 27 with a secondary negative pressure port 14 in the vicinity of a secondary throttle valve 8 of a secondary suction passage 2 for high load. A bypass 29 branches from the passage 23 and is communicated with the first case 31a of the first negative pressure control valve 31 which is made of VCV. A bypass 32 branches from the passage 27 and is communicated with the third case 31a of the third negative pressure control valve 33. The first water temperature sensing valve 28 is disposed on the way of the passage 27 and the fourth water temperature sensing valve is disposed on the way of the passage 23. By forming both the primary VC negative pressure and the secondary VC negative pressure and shifting them, a quantity of secondary air to be supplied, a timing thereof, an ignition timing and so forth are properly controlled. |
