| 摘要 |
PURPOSE:To reduce the HC discharge amount by connecting the connection part between a pair of diffusion parts which use a valve recess in common, by a smooth curve, and specifying the ratio between the radius of the curve and the width of a trench part. CONSTITUTION:Positioned below a suction valve and an exhaust valve at the piston top-edge part 4, the diffusion parts 7A and 8A consisting of a pair of circular concaved parts having the diameter larger than that of the both valves are formed largely at the center. A groove-shaped trench part 10A which is contiguous to the both diffusion parts 7A and 8A and whose one edge extends to the undersurface of an injection port 21 communicating to an eddy-current chamber 20 is formed on the axis of symmetry to the diffusion parts 7A and 8A. The connection part 9A between a pair of diffusion parts 7A and 8A is connected through a smooth curve, and the ratio R/l between the radius R of the curve and the width l of the groove of the trench part 10A is set to 1 or less. Therefore, in the diffusion part, the superior mixing of flame with the air in the diffusion part is permitted, and HC and smoke can be reduced. |
