| 摘要 |
PURPOSE:To reduce the pumping loss of resting cylinders by dividing multiple cylinders into 2 groups, providing suction/exhaust cutoff valves in suction/ exhaust passages of one cylinder proup, and controlling to open or close individual valves at respective speeds in response to the engine load. CONSTITUTION:In a 4-cylinder internal-combustion engine with the first cylinder group A of cylinders 2b, 2c and the second cylinder group B of cylinders 2a, 2d; suction cutoff valves 17, 18 driven by a drive unit 20 via a valve shaft 19 are provided at the outlet portion of surge tank branch pipes 7b, 7c of the first cylinder group A. In addition, exhaust cutoff valves 26, 27 driven by negative pressure actuators 30, 31 are provided at the inlet portion of exhaust manifold branch pipes 11b, 11c of the same first cylinder group A. When the engine load becomes a predetermined value or lower, the suction cutoff valves 17, 18 are closed at a slow speed, then the exhaust cutoff valves 26, 27 are closed at a high speed. When the engine load becomes a predetermind value or higher, the exhaust cutoff valves 26, 27 are opened at a high speed, then the suction cutoff valves 17, 18 are opened at a low speed. |
