Piston for a cylinder injection engine

摘要

In a cylinder injection engine which includes an injection valve disposed in the vicinity of an intake port of the engine and adapted to inject fuel into the combustion chamber, a spark plug disposed closer to the center portion of the combustion chamber than the injection valve, and a piston having a cavity formed in the top face that substantially faces the injection valve and the spark plug, the cavity is formed by smoothly connecting a curved surface located below the spark plug and a curved surface located below the injection valve via a connection curved surface. The curvature kappa 1 of the curved surface located under the injection valve and the curvature kappa 2 of the curved surface located under the spark plug satisfy a relationship kappa 1< kappa 2.