Abstract: A piston for an internal combustion engine includes a piston body having an outer cylindrical surface defining a longitudinal piston axis, a combustion face defining a compound combustion bowl, and a compound rim extending radially outward from the compound combustion bowl to the outer cylindrical surface. The compound combustion bowl includes a convex inner bowl surface defining a conical projection and a concave outer bowl surface. The compound rim includes a flat outer rim surface adjoining the outer cylindrical surface, and a convex inner rim surface adjoining the compound combustion bowl. The convex inner bowl surface transitions smoothly to the concave outer bowl surface, and the convex inner rim surface transitions abruptly to the concave outer bowl surface at an edge of the compound combustion bowl.

Abstract: A piston for an internal combustion engine includes a piston body having an outer cylindrical surface defining a longitudinal piston axis, a combustion face defining a compound combustion bowl, and a compound rim extending radially outward from the compound combustion bowl to the outer cylindrical surface. The compound combustion bowl includes a convex inner bowl surface defining a conical projection and a concave outer bowl surface. The compound rim includes a flat outer rim surface adjoining the outer cylindrical surface, and a convex inner rim surface adjoining the compound combustion bowl. The convex inner bowl surface transitions smoothly to the concave outer bowl surface, and the convex inner rim surface transitions abruptly to the concave outer bowl surface at an edge of the compound combustion bowl.

Abstract: A piston for a compression ignition internal combustion engine includes a piston body having a combustion face defining a combustion bowl, and the combustion face including a compound bowl surface and a compound rim surface. The combustion face is profiled to balance a combustion efficiency property of the piston with emissions properties of the piston, and includes a profile of rotation defining a convex curve segment bisected by the longitudinal axis, and a plurality of concave curve segments outboard of the convex curve segment. The profile of rotation further includes a compound rim profile defining a plurality of convex curve segments corresponding to an inner rim surface. The convex curve segment of the compound bowl profile defines a relatively small radius of curvature, and the plurality of convex curve segments corresponding to the inner rim surface define a relatively large radius of curvature.

Abstract: A piston for a compression ignition internal combustion engine includes a piston body having a combustion face defining a combustion bowl, and the combustion face including a compound bowl surface and a compound rim surface. The combustion face is profiled to balance a combustion efficiency property of the piston with emissions properties of the piston, and includes a profile of rotation defining a convex curve segment bisected by the longitudinal axis, and a plurality of concave curve segments outboard of the convex curve segment. The profile of rotation further includes a compound rim profile defining a plurality of convex curve segments corresponding to an inner rim surface. The convex curve segment of the compound bowl profile defines a relatively small radius of curvature, and the plurality of convex curve segments corresponding to the inner rim surface define a relatively large radius of curvature.