COMBUSTION CHAMBER STRUCTURE FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide a combustion chamber structure for an internal combustion engine capable of improving suppression efficiency of knocking generation. SOLUTION: A whole periphery of a circular outer peripheral end surface 16 of a top surface of a piston is formed on a plane crossing with respect to a center axis of the piston at right angles, and a protuberant part protruding to the cylinder head direction is formed on the whole periphery of the end surface near the center. A pair of valve recesses 18 and 19 is formed respectively on the protuberant part. A plane inclined surface is formed on a top surface between the pair of the valve recesses. On the top surface near the respective valve recesses, a conical inclined surface connecting to the plane inclined surface and the circular outer peripheral end surface 16 is formed. A first squish area is formed with the plane inclined surface and the circular outer peripheral end surface 16. A second squish area is formed on the conical inclined surface. At least a part of a squish flow generated in the first squish area is introduced into the second squish area.