Patent ID: 7946216

Claim:
A two-part piston for an internal combustion engine comprising: (a) an upper piston part forming a piston crown; (b) a lower piston part connected with the upper piston part; (c) a piston skirt disposed on a side of the lower piston part facing away from the piston crown; (d) two pin bosses lying opposite one another disposed on a side of the lower piston part facing away from the piston crown, each pin boss having a pin bore; (e) a solid cylindrical formed-on part lying coaxial to a piston axis disposed on a side of the upper piston part facing away from the piston crown, said solid cylindrical formed-on part having two projections lying opposite one another and directed radially outward, said projections being disposed at an end of the solid cylindrical formed-on part so as to form a T-shape with the solid cylindrical formed-on part; wherein the lower piston part is delimited on a side of the piston crown by a partition connected with the piston skirt and with the pin bosses, the partition having an opening coaxial to a piston axis, a radial diameter of the opening being less than a radial length of the projections, wherein the partition has two recesses that lie radially opposite one another, and have radial dimensions that are greater than radial dimensions of the projections; wherein the solid cylindrical formed-on part is dimensioned such that during assembly of the upper piston part onto the lower piston part and rotation of the upper piston part, the projections enter the recesses and engage behind edges of the opening; wherein the partition has an elastically resilient region lying coaxial to the piston axis on a radially inner side of the partition, said opening being disposed in said region, said region delimiting an inner cooling channel formed by the upper piston part and a side of the lower piston part; wherein respective edges of the opening facing away from the piston crown has have surfaces with catch noses on both sides of the recesses, and contact areas on sides of the catch noses facing away from the recesses, such that a thickness of each contact area is less than a maximal axial dimension of the catch noses; and wherein the projections are formed by a fitted stud disposed on an end of the cylindrical formed-on part facing away from the piston crown, the stud projecting radially beyond an end of the formed-on part on both sides.