Patent ID: 7946268

Claim:
Two-part piston ( 1 , 1 ″) for an internal combustion engine, having an upper part ( 2 , 2 ″) that forms a piston crown ( 4 , 4 ′), whereby a cylindrical pin ( 31 ) having an outside thread ( 32 ) and lying coaxial to the piston axis ( 12 ) is formed onto the underside of the upper part ( 2 , 2 ″), on the side facing away from the piston crown ( 4 , 4 ″), and having a lower part ( 3 , 3 ″), on the underside of which pin bosses ( 9 , 9 ′) having pin bores ( 10 , 10 ′) and skirt elements ( 13 ) that connected the pin bosses ( 9 , 9 ′) with one another are disposed, whereby the lower part ( 3 , 3 ′, 3 ″) has an upper crown part ( 25 , 25 ′) with an opening ( 27 , 27 ′) that lies coaxial to the piston axis ( 12 ), into which opening the pin ( 31 ) is introduced, by way of which pin the upper part ( 2 , 2 ″) is screwed to the lower part ( 3 , 3 ″) by means of a hexagonal nut ( 29 ) screwed onto the pin ( 31 ), wherein the radial inside of the opening ( 27 ) has a ring-shaped surface ( 21 ) disposed on the skirt side, which lies further removed from the piston crown ( 4 ) than the upper face surface ( 23 ) of the hexagonal nut ( 29 ), and that an expansion sleeve ( 26 ) is disposed between the face surface ( 23 ) and the surface ( 21 ), which sleeve, for one thing, has a collar ( 28 ) directed radially inward, disposed on its side facing the piston crown, this collar having a radially oriented inside surface ( 20 ) on its side facing away from the piston crown, against which surface the face surface ( 23 ) of the hexagonal nut ( 29 ) rests, and, for another thing, has a contact surface ( 19 ) that faces the piston crown in its region that faces away from the piston crown, which surface rests against the surface ( 21 ).