Abstract: A light-alloy piston for internal combustion engine, is formed in the piston head with a combustion chamber recess. The stresses which are induced at the rim of the combustion chamber recess by the ignition pressure are reduced by the provision of an inwardly extending blind hole in the portions between the ring groove for the lowermost compression ring and the top apex of the bores in the piston pin bosses.

Abstract: In expansion-controlled light alloy pistons for internal combustion engines, expansion control elements made of steel are bonded to the carrying portions of the cast skirt on the inside peripheral surface thereof and are embedded in the hubs of the piston pin bosses. To provide for an optimum expansion control action throughout the height of the piston skirt, the expansion control elements are provided on both sides of the plane of oscillation of the connecting rod with an aperture, which is open toward the end of the skirt and has a height amounting to at least 30% of the height of the expansion control elements. Said aperture has a peripheral dimension amounting to more than 10% of the piston diameter. Projections for supporting the expansion control element at its edges defining the aperture protrude into the latter.

Abstract: To provide for separate expansion control actions at the top and bottom edges of the skirt of an expansion-controlled light alloy piston, to prevent a direct propagation of deformation between the top and bottom edges of the skirt and to reduce the skirt area between the top and bottom edges of the skirt, the skirt of the piston is provided at its periphery with a transverse slot, which extends around the entire periphery of the skirt or part thereof and is disposed on the level of the piston pin boss.

Abstract: A light alloy piston for diesel engines includes a piston head coated with a hard annodized layer having a combustion chamber recess and/or a fuel-guiding channel provided adjacent to the edge of the combustion chamber recess and/or valve pockets. The piston head is free of a hard anodized layer in those regions which are highly stressed by gas and mass forces. Preferably those regions of the piston head adjacent to edge portions of the combustion chamber recess lying in the direction of the piston pin are free of a hard anodized layer.