Patent ID: 8677974

Claim:
A piston for a direct injection engine, the piston comprising a bowl at an upper end, the bowl forming a portion of a combustion chamber, wherein the bowl has an inner surface that defines a volume configured to receive a fuel-air mixture, the inner surface of the bowl including a flat bottom portion surrounding a central protruding dome, the flat bottom portion having a radius of curvature of equal to or greater than 1.0 meter, wherein the flat bottom portion is bounded by two radial concave surface portions which are disposed below two convex separation features for an injected fuel spray, wherein one of said two convex separation features protrudes inwardly into the bowl, wherein said one of said two convex separation features that protrudes inwardly from a circumferential wall of the bowl is arranged to separate the injected fuel spray into an upper and a lower region in the combustion chamber, and wherein the piston has an upper peripheral face which is completely outboard of said one of said two convex separation features that protrudes inwardly from a circumferential wall of the bowl.