Three-piece oil-control ring for an internal combustion engine

A three-piece oil control ring is provided for use in a piston groove of an internal combustion engine. The ring comprises a first annular segment and a second annular segment, associated to an expanding element. The expander has a substantially annular shape and comprises a first end facing the internal wall of the groove when the ring is mounted on the piston and a second opposite end. The ring further comprises an intermediate portion having at least one protrusion for association with the segments. Still further, the first end exhibits first thickness value (E1), the second end exhibits second thickness value (E2) and the substantially intermediate portion exhibits third thickness value (E3), wherein the value of (E1) is substantially lower than the value of (E3) and lower or similar to the value of (E2), the difference between (E1) and (E3) being substantially higher than that between (E1) and (E2).