Abstract: A piston ring may include a spacer or expansion element and/or two segments. The segments may have a radial dimension between approximately 1.50 mm and approximately 1.90 mm and a height between approximately 0.30 mm and approximately 0.40 mm. The segments may have a concave profile with recesses between approximately 0.015 mm and approximately 0.030 mm and a clearance of approximately 0.150 mm. The segments may be wound via a matrix box device and a roller. The piston ring may have a circularity, expressed in the form of a decomposition as a Fourier series, with an amplitude for orders higher than 10 which is not greater than 0.10 ?m.

Abstract: A piston ring may have a base with a sliding external surface, an internal surface, an upper surface, and a lower surface, the external surface having chamfered edges. The external surface, the internal surface, the upper surface, the lower surface, and the chamfered edges may have a coating provided with a nitrided first layer having a thickness of up to 2% of a nominal axial thickness of the ring when applied to the upper surface and the lower surface, and a thickness of up to 10% in relation to the thickness of the first layer applied to the upper surface and the lower surfaces when applied to the external surface and to the chamfered edges. The external surface and the chamfered edges may include a sliding layer having one of a hard chromium or ceramic chromium plated coating, the sliding layer being applied on the first layer, the sliding layer having a thickness of between 80 and 175 microns.

Abstract: A piston ring may have a base with a sliding external surface, an internal surface, an upper surface, and a lower surface, the external surface having chamfered edges. The external surface, the internal surface, the upper surface, the lower surface, and the chamfered edges may have a coating provided with a nitrided first layer having a thickness of up to 2% of a nominal axial thickness of the ring when applied to the upper surface and the lower surface, and a thickness of up to 10% in relation to the thickness of the first layer applied to the upper surface and the lower surfaces when applied to the external surface and to the chamfered edges. The external surface and the chamfered edges may include a sliding layer having one of a hard chromium or ceramic chromium plated coating, the sliding layer being applied on the first layer, the sliding layer having a thickness of between 80 and 175 microns.

Abstract: 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).

Abstract: 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).