| 摘要 |
PURPOSE:To prevent knocking and improve an output in an intermediate load range, by forming the opening area of an intermediate load intake port smaller than the opening area of a low load intake port and increasing a flow speed of a mixture supplied via the intermediate load intake port. CONSTITUTION:A primary intake passage 12 independently formed to an intake manifold 11 is connected to a low load intake port 10, and a primary throttle valve 14 of a duplex carburetor 13 is arranged in the passage 12. A common secondary intake passage 17 is connected and a secondary throttle valve 18 is arranged to intermediate and high load intake ports 15, 16. In a low load range, the valve 18 is closed while a control valve 21 performs closing operation to close the port 16, and a mixture is supplied through the port 10 to an operating chamber 4 from the passage 12 of relatively small area, then a flow speed of the mixture is increased to fully pulverize fuel and obtain good mixing. |
