| 摘要 |
PROBLEM TO BE SOLVED: To suppress the knocking of an internal combustion engine by a simple structure.SOLUTION: Oblong recesses 11 extending in a peripheral direction are formed at a peripheral edge of a piston 3. The recesses 11a are formed at one point of either of an exhaust side EX and an intake side IN, or two points of both the sides. In another way, the recesses are formed at one point of one of cylinder row directions that are adjacent cylinder sides, or two points of both the directions. The recesses are formed at an exhaust side which is liable to be high in temperature, an intake side toward which a high-temperature gas flows by a tumble, or a cylinder side that is a side at which cooling performance is lowered depending on a layout of a water jacket, the cooling performance is improved by an increase of a surface area, a high-temperature is caused before the arrival of a flame, and thus, the occurrence of knocking is suppressed.SELECTED DRAWING: Figure 1 |
