A piston ring assembly for an internal combustion engine is provided. The piston ring assembly includes a plurality of seal rings, i.e., a first seal ring and a second seal ring. The seal rings are positioned on at least a portion of a piston crown periphery axially and radially adjacent to each other...http://www.google.de/patents/US20090020958?utm_source=gb-gplus-sharePatent US20090020958 - METHODS AND APPARATUS FOR OPERATING AN INTERNAL COMBUSTION ENGINE
