Patent ID: 8424506

Claim:
A direct-injection type engine comprising: a combustion chamber defined and formed by at least a cylinder head portion and a top portion of a piston; and a fuel injector for injecting fuel directly into said combustion chamber; wherein a cavity recessed downwards is formed in said top portion of said piston, coaxially with said piston, a land portion protruded upwards is formed on a central portion of a bottom surface of said cavity, coaxially with said piston such that said land portion has a conical side surface approaching to a central axis of said piston at the upper side of said conical side surface, and a plurality of convex portions radially extending from said central axis of said piston when viewing from the top, are formed on said side surface of said land portion; wherein said fuel injector has a plurality of injection bores positioned at the upper side of said combustion chamber and said injection bores are positioned such that the axes of fuel sprays having the same number as that of the injection bores and diffused from said injection bores follow said side surface of said land portion toward said cavity from said corresponding injection bore and spread radially about said central axis of said piston when viewing from the top; and wherein the number of said convex portions are the same as that of said fuel sprays and the extending direction of each convex portion is aligned with the direction of the central axis of said corresponding fuel spray when viewing from the top.