| 摘要 |
PROBLEM TO BE SOLVED: To provide a two-stroke engine with which the blow-by of scavenging from an exhaust port can be suppressed effectively, and with which an engine output can be improved and pollution can be lessened.SOLUTION: A two-stroke engine 1 is equipped with: a cylinder 5, which is formed in a substantially cylindrical shape and has an exhaust port 27a capable of discharging exhaust, and a scavenging port 25b capable of feeding scavenging of fuel and air in the direction substantially opposite to the exhaust direction of the exhaust; and a piston 21 capable of moving reciprocally between a top dead center position and a bottom dead center position within the cylinder 5. A piston-side recess 21b which is recessed downward in the shape of a substantially spherical surface is formed in a portion of the top surface 21a of the piston 21. The piston-side recess 21b has a sharply sloping surface part 21b-1, the overall shape of which is that of a substantially spherical surface, and which slopes sharply from the outer edge on the exhaust-direction side toward a deepest part 21b-3, and a gently sloping surface part 21b-2, which slopes more gently than the sharply sloping surface part 21b-1, and slopes toward the deepest part 21-b from the outer edge on the side opposite the exhaust-direction side. |
