US Patent 7946216 Two-part piston for an internal combustion engine

The invention relates to a two-piece piston (1) for an internal combustion engine, comprising a piston upper piece (2) and a piston lower piece (2). A cylindrical molding (24) is arranged on the underside of the piston upper piece (2), facing away from the piston crown, lying coaxial to the piston axis (15), with two radial outward-facing hooked projections (27) on the end thereof facing away from the piston crown. The piston lower piece (6) has an opening (16) on the piston crown side, in which the cylindrical molding (24) with the projections (27) is introduced and rotated on assembly of the piston upper piece (2) on the piston lower piece (6), such that the projections (27) engage behind the edge of the opening (16).