Piston ring for an internal combustion engine

A power cylinder assembly, comprising:

• a cylinder liner having a channel on an inside wall thereof having upper and lower surfaces of the channel that are axially spaced to define a first height, said channel extending circumferentially around said inside wall;
• a piston body having a plurality of ring grooves and a plurality of piston rings disposed in said ring grooves of said piston body with one piston ring being disposed in each of said ring grooves;
• a piston ring assembly disposed in said channel of said cylinder liner;
• said piston ring assembly having a plurality of split rings stacked in face-to-face contact with one another in an axial direction, said plurality of split rings including a top split ring and a bottom split ring, said split rings providing said piston ring assembly with a second height that is less than said first height of said channel when said piston ring assembly is installed in said channel of said cylinder liner, each of said split rings having an inner face with a rounded edge and an outer face with a rounded edge, and each of said split rings having a generally constant cross-sectional shape in a circumferential direction;
• each of said split rings having a flat top face and a flat bottom face extending between said rounded edges of said inner and outer faces;
• adjacent ones of said flat top and bottom faces of said split rings being in direct contact with one another along their respective full lengths;
• said flat top face of said top split ring directly facing and being able to contact said upper surface of the channel, and said flat bottom face of said bottom split ring directly facing and being able to contact said lower surface of the channel;
• said piston ring assembly further including a single spring substantially circumferentially surrounding said split rings and abutting said outer faces and biasing said split rings in a radially inward direction to seal all of said inner faces of said split rings against a circumferentially continuous portion of said skirt of said piston body;
• and
• wherein said spring has a generally serpentine shape which extends through a plurality of peaks and a plurality of valleys.