Patent ID: 7308850

Claim:
Piston ( 1 ) for an internal combustion engine, having an essentially cylindrical basic body ( 2 ) made of aluminum, whose one face forms a piston head ( 3 ), having pin bosses ( 8 ) with pin bores ( 6 ) disposed on the underside of the basic body ( 2 ) that faces away from the piston head ( 3 ), having skirt elements ( 9 ) that connect the pin bosses ( 8 ) with one another, having a ring element ( 4 ) of Ni resist disposed in the radially outer edge region of the piston head ( 3 ), which forms a ring-shaped cooling channel ( 22 ) with the basic body ( 2 ), and that is attached to the basic body ( 2 ) by way of a screw connection that consists of an inside thread ( 25 ) lying between the cooling channel ( 22 ) and the lower face ( 12 ) of the ring element ( 4 ), on its side that lies radially on the inside, and a matching outside thread ( 26 ) disposed on the mantle surface ( 14 ) of the basic body ( 2 ), below the cooling channel ( 22 ), the ring element ( 4 ) is configured in two steps, in cross-section, whereby the first step, on the piston head side, is formed in that a collar ( 16 ), step-shaped in cross-section, radially directed inward, is molded onto the region of the ring element ( 4 ) on the piston head side, followed by the cooling channel ( 22 ) on the pin boss side, and whereby the second step is formed in that the ring element ( 4 ) has a ring-shaped contact surface ( 27 ) that lies parallel to the piston head ( 3 ), between the cooling channel ( 22 ) and the inside thread ( 25 ), proceeding from the cooling channel ( 22 ) and pointing radially outward, which comes to rest on a contact surface ( 28 ) when the ring element ( 4 ) is screwed onto the basic body ( 2 ), which surface is molded into the basic body ( 2 ) on the piston head side, between cooling channel ( 22 ) and outside thread ( 26 ), and that the ring element ( 4 ) has a wall region ( 29 ) between the contact surface ( 27 ) and the inside thread ( 25 ), which lies axially and is thinned to such an extent that it can be stretched in the axial direction when the ring element ( 4 ) is screwed onto the basic body ( 2 ).