Patent ID: 7934482

Claim:
Liquid-cooled composite piston ( 1 ) having an upper part ( 2 ) that has a piston crown ( 4 ) and a ring wall ( 5 ) having a top land ( 6 ) and having a ring belt ( 7 ), and having a lower part ( 3 ) that has pin bosses ( 8 , 8 ′) having pin bores ( 9 , 9 ′) and skirt elements ( 10 , 10 ′), whereby the upper part ( 2 ) and the lower part ( 3 ) stand in connection with one another by way of a radially outer ring-shaped contact surface ( 12 ) and by way of a radially inner ring-shaped contact surface ( 11 ), whereby an outer cooling channel ( 13 ) is disposed between the outer contact surface ( 12 ) and the inner contact surface ( 11 ), and an inner cooling channel ( 18 ) is disposed radially within the inner contact surface ( 11 ), whereby the piston interior ( 28 ) is connected with the outer cooling channel ( 13 ) by way of at least one oil feed channel ( 16 ), and the outer cooling channel ( 13 ) is connected with the inner cooling channel ( 18 ) by way of at least one overflow channel ( 22 , 22 ′), wherein a pin ( 20 ) having an outside thread ( 23 ) is disposed on the underside of the piston crown ( 4 ), facing away from the piston crown, coaxial to the piston axis ( 17 ), the upper part ( 2 ) and the lower part ( 3 ) of the piston ( 1 ) are screwed together by means of a hexagonal nut ( 19 ) that can be screwed onto the outside thread ( 23 ) of the pin ( 20 ), and the hexagonal nut ( 19 ) has a collar ( 25 ) on the piston crown side, having at least one radially disposed bore or milling ( 26 , 27 ), which connects the inner cooling channel ( 18 ) with the piston interior ( 28 ).