Patent ID: 7493850

Claim:
An internal combustion engine, comprising: at least one wall defining a bore; and a piston disposed in the bore and coupled to a piston rod to pivot about a pivot axis, the piston comprising a substantially circumferential outer surface having a head portion and a skirt portion below the head portion, at least a portion of the outer surface bearing against the wall in a thrust plane when the piston is substantially at operating temperature and subject to a thrust force, the portion of the thrust force borne by the skirt portion in the thrust plane is definable by a skirt force centroid, the skirt force centroid being positioned at an axial height substantially at the pivot axis or below the pivot axis, wherein the skirt portion includes a skirt wall having a wall thickness in the thrust plane that varies relative to the axial height so that the skirt wall has greater radial rigidity above the pivot axis.