| 摘要 |
PURPOSE:To make stabilized lean mixture combustion operation possible by arranging a bulged wall portion in one of branched suction ports to divide a herical passage from a bypass passage and arranging a suction control valve at an end of the bulged wall portion extending toward a suction inlet part. CONSTITUTION:A Siamese type suction port 14 has one suction inlet part 16 for each cylinder 12 and is branched from the middle into two suction ports 18 and 20, with respective open ends 24 and 26 toward a combustion chamber 22 being opened or closed by respective suction valves 28 and 30. In this case, a bulged wall portion 38 is suspended from the upper wall 32 of the port in the suction port 18 to divide a herical passage 40 spiraling around the axial line of the open end 24 from a straight line-shaped bypass passage 42 communicating with the spiral end of the herical passage 40. The bulged wall portion 38 is arranged to extend from the top end of a bulkhead 36, namely the branched suction ports 18 and 20 toward the suction inlet part 16. A suction control valve 46 is arranged on the suction port 20 side of the end part 39 of the bulged wall portion 38. |
