Patent ID: 7341053

Claim:
A combustion chamber structure of an internal combustion engine comprising: a plane surface portion formed in at least either one of a region stretching from an intake-side edge of a top surface of a piston to the vicinity of a position corresponding to an intake port and a region stretching from an exhaust-side edge of said top surface of the piston to the vicinity of a position corresponding to an exhaust port so as to be orthogonal to an axis of the piston, said plane surface portion forming a squish area in consort with a flat portion formed in a lower surface of a cylinder head at around the compression top dead center of said piston so as to sandwich said squish area therebetween; a conical tapered portion formed in a rim of said top surface of the piston except for said plane surface portion, the conical tapered portion extending to an outer peripheral edge of the top surface of the piston; a ridge portion that is continuously ridged from said plane surface portion toward the vicinity of a spark plug disposed in a combustion chamber; and a recessed portion formed to be surrounded by said tapered portion and said ridge portion.