Patent ID: 8403334

Claim:
A piston, comprising: a piston body defining an outer circumferentially disposed groove; and a piston ring assembly, including: an oil control rail disposed within said piston groove and including a seal surface configured to seal against a piston bore surface of an engine, said seal surface defining a radially outer periphery; a coil expander disposed in said groove, a radially innermost portion of said coil expander spaced radially outwardly from a radially inner surface of said outer circumferentially disposed groove, said coil expander configured to push said oil control rail radially outward to contact the piston bore surface when the piston is received within the piston bore surface; and two positioning rings, a first one of said positioning rings disposed axially above said oil control rail, a second one of said positioning rings disposed axially below said oil control rail, each of said positioning rings defining an outermost periphery of the positioning rings, said outermost peripheries disposed radially inward in relation to said seal surface; wherein said positioning rings each include a radially inward surface directly engaging said coil expander.