Goetze Ag

Wolfgang Schmelter

Albin Mierbach

Gerhard Duck

Hans-Rainer Brillert

Heinrich-Christian Mader

A piston ring has a gap defined by ring gap faces oriented toward one another and a nominal outer radius assumed by the piston ring in a closed position in which the piston ring is in an installed state in an engine cylinder having a radius equalling the nominal outer radius of the piston ring. The piston ring has first length portions extending from both ring gap faces and having a central angle of at least 15.degree. and less than 25.degree. and second length portions immediately adjoining each respective first length portion and having a central angle of approximately 10.degree.. In the installed state the first length portions have a radius of curvature equalling the nominal outer radius and the radius of curvature of the second length portions is smaller than the nominal outer radius. By virtue of such a ring configuration, a radial pressure distribution of the piston ring in the installed state is substantially zero at the ring gap and increases in opposite directions from the ring gap to a maximum value in the second length portions. The maximum value is in excess of 200% of an average circumferential radial pressure distribution of the piston ring in the installed state.

Piston ring having a non-uniform radial pressure distribution

A piston-and-ring assembly includes a piston having a circumferential groove which has an upper side wall and an opposite lower side wall; and a piston ring received in the groove and having opposite radial faces extending obliquely with respect to the side walls. The piston ring engages, with an axial bias, the upper and lower side walls with an annular marginal surface portion forming part of each radial face of the piston ring and extending substantially parallel to the side wall with which it is in engagement.

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Leverkusen, Germany

Wolfgang Schmelter