Piston ring for an internal combustion engine

1. A power cylinder assembly, comprising:

a cylinder wall having a channel formed therein, said channel extending substantially circumferentially around said cylinder wall, and said channel having a circumferentially constant and U-shaped cross-sectional shape which opens inwardly in a radial direction and is free of other openings;

a piston body having a skirt and wherein at least a portion of an outer surface of said skirt extends continuously around a circumference;

a piston ring disposed in said channel of said cylinder wall;

said piston ring having a ring body that is made of a monolithic piece of metal and that extends about an axis and has an inner face and an outer face, said inner face having only ridges that extend in the radial direction, said ridges being spaced from one another by a valley region, said outer face presenting a groove, and said ring body having a planar top surface and a planar bottom surface along a full distance between opposite gap faces that are separated from one another by a ring gap;

said piston ring further including a spring substantially circumferentially surrounding said ring body and seated in said groove on said outer face, said spring biasing said ring body inwardly in radial direction to seal said ridges against said circumferentially continuous portion of said skirt of said piston body, and said spring being a coil spring;

said ring body having at least one oil drainage port extending in the radial direction between said valley region of said inner face and said groove of said outer face for conveying oil from between said ridges to said groove;

wherein said ridges of said ring body have respective first surfaces that face away from said valley region, each first surface extending at a first angle relative to the radial direction; and

wherein said inner face of said ring body further includes second surfaces, wherein each second surface extends from one of said first surfaces to a respective one of said planar top and bottom surfaces, and wherein each second surface is angled relative to the radial direction at a second angle that is greater than zero degrees and is greater than said first angle and wherein said second angle is approximately eighty degrees.

2. The power cylinder assembly as set forth in claim 1 wherein said at least one oil drainage port in said ring body is further defined as a plurality of oil drainage ports spaced circumferentially from one another.

3. The power cylinder assembly as set forth in claim 1 wherein said ring body is uncoated.

4. The power cylinder assembly as set forth in claim 1 wherein said ring body is of cast iron or steel.