Patent ID: 6883418

Claim:
A piston for an internal combustion engine, which comprises carbon having a piston crown, a top land axially adjoining the piston crown, a ring portion and a piston skirt having a boss bore for receiving a piston pin, wherein the piston skirt wall has increased-thickness portions in mutually opposite relationship on the inside of the piston skirt to form the boss and which extend into the underside of the piston crown with a rounded configuration, wherein in the region between the increased-thickness boss portions independently of the surface configuration of the top side of the piston crown the underside of the piston crown forms a curved surface with a curvature which is directed transversely with respect to the axis of the boss bore, wherein the underside of the piston crown is in a form selected from the group consisting of a dome surface in the form of a part-spherical surface, a toric surface whose axis is parallel to the axis of the boss bore, a partial surface of an ellipsoid of revolution whose large major axis is at a right angle to the axis of the piston and whose axis of revolution coincides with the axis of the piston, and a partial surface of an ellipsoid of revolution whose large major axis is at a right angle to the axis of the piston, and to the axis of the boss bore and forms the axis of revolution.