A piston is used for an engine including: an ignition plug disposed in the vicinity of a central axis of a cylinder; intake and exhaust ports disposed at positions where the ignition plug is interposed therebetween; and an injector disposed at a position offset from the ignition plug toward the intake port to inject fuel sprays toward a crown surface of the piston. The piston includes: a recess formed by recessing the crown surface of the piston with respect to other portions of the crown surface, in which the recess includes a step on an outer peripheral edge over the entire circumference thereof with respect to the other portions, and a pair of lateral sides formed straightly so as to extend substantially in parallel to a straight line connecting the injector and the ignition plug when seen in a direction of the cylinder axis.

An internal combustion engine may include an engine block having a plurality of cylinders therein, with each cylinder being closed by a cylinder head. The internal combustion engine may also include a piston reciprocatingly mounted within each cylinder and defining a combustion chamber therebetween. The internal combustion engine may also include a fuel injector communicating fuel to the combustion chamber, the fuel creating a plurality of flames when ignited. The internal combustion engine may also include a piston crown extending from each piston and defining a piston bowl. The internal combustion engine may also include a rim depending from at least one of the cylinder head and piston and being provided radially inward from the piston crown. The internal combustion engine may also include a passageway configured within at least one of the piston crown and cylinder head and adapted to guide a squish flow between the piston crown, cylinder head and back toward the piston bowl to interact with the plurality of flames within the piston bowl for enhanced combustion.

A piston for an internal combustion engine includes a ring belt extending circumferentially about a longitudinal axis of the piston; a combustion bowl disposed between the longitudinal axis and the ring belt along a radial direction, the radial direction being perpendicular to the longitudinal axis; and a squish face disposed between the combustion bowl and the ring belt along the radial direction. The squish face includes a first textured surface disposed on the squish face, the first textured surface including a first plurality of concave surfaces.

A piston is used for an engine including: an ignition plug disposed in the vicinity of a central axis of a cylinder; intake and exhaust ports disposed at positions where the ignition plug is interposed therebetween; and an injector disposed at a position offset from the ignition plug toward the intake port to inject fuel sprays toward a crown surface of the piston. The piston includes: a recess formed by recessing the crown surface of the piston with respect to other portions of the crown surface, in which the recess includes a step on an outer peripheral edge over the entire circumference thereof with respect to the other portions, and a pair of lateral sides formed straightly so as to extend substantially in parallel to a straight line connecting the injector and the ignition plug when seen in a direction of the cylinder axis.

An internal combustion engine for gaseous fuel includes a cylinder and a piston for reciprocal movement in the cylinder along a reciprocal axis, whereby a combustion chamber is at least partially delimited by the cylinder and the piston. The piston includes a piston crown facing the combustion chamber, a piston crown projection of the piston crown in a direction parallel to the reciprocal axis and onto a piston crown plane extending transversally to the reciprocal axis having a piston crown center point, the piston crown comprising a piston bowl surface defining a piston bowl and a piston rim portion enclosing the piston bowl surface. A piston bowl opening is the intersection between the piston rim portion and the piston bowl surface. The piston bowl opening has an opening center of gravity in the piston crown plane. The opening center of gravity is offset from the piston crown center point.