| 摘要 |
PURPOSE:To raise the combustion efficiency of an engine, by decreasing the volume of a combustion chamber without making it flat by shaping the combustion chamber in such a cup-like form that the center of curvature is located above the focal point of intake valves and exhaust valves on the axis of a cylinder and the radius at the lower end of the combustion chamber is smaller than the radius of the cylinder. CONSTITUTION:Two intake passages 12 and two exhaust passages 13 are formed to extend upwardly outwards from a combustion chamber 11, and intake valves 14 and exhaust valves 15 are provided respectively at the portions of the intake and exhaust passages 12, 13 opened in the combustion chamber 11 in the manner that they are located radially upwards around the focal point F2 on the axis (l) of a cylinder. Here, the combustion chamber 11 is shaped in such a cup-like form having a radius R2 that the center N of curvature is located on the axis (l) of the cylinder and above the focal point F2, and the radius D3 at the lower end of the cylinder head is made smaller than the radius D2 of the bore 18 of the cylinder. Further, the radius R2 is made smaller than the distance R1 between the focal point F2 and the intake and exhaust valves 14, 15. |
