Provided are a segment, a combination oil ring, and a manufacturing method for a segment, which are capable of preventing independent rotation of the segment while dealing with reduction in tension of the combination oil ring. Specifically, provided is a segment being slidable in an axial direction of a cylinder under a state in which an inner peripheral surface of the segment is pressed by ear portions formed in an expander spacer in a circumferential direction and an outer periphery side of the segment is pressed against an inner wall of the cylinder, in which the inner peripheral surface of the segment has at least two or more dross-projecting portions in the circumferential direction, and the dross-projecting portions have a projection height of from 4 m to 25 m.

A piston for an internal combustion engine including a piston crown and a combustion chamber recess recessed therein, the combustion chamber recess including a recess edge. The piston may also include a ring groove for receiving a piston ring. The piston may further include a cooling duct having a smaller spacing from the piston crown than that of a flank of the ring groove, the cooling duct defining a minimum spacing from the piston crown at a first location, and a minimum spacing from the combustion chamber recess at a second location. The cooling duct may have a rounded portion between the first location and the second location. The cooling duct may have a maximum spacing from the recess edge at a third location. The rounded portion may have a rounding radius defined at least at the third location that is greater than 4% of a piston diameter.

A piston for an internal combustion engine including a piston crown and a combustion chamber recess recessed therein, the combustion chamber recess including a recess edge. The piston may also include a ring groove for receiving a piston ring. The piston may further include a cooling duct having a smaller spacing from the piston crown than that of a flank of the ring groove, the cooling duct defining a minimum spacing from the piston crown at a first location, and a minimum spacing from the combustion chamber recess at a second location. The cooling duct may have a rounded portion between the first location and the second location. The cooling duct may have a maximum spacing from the recess edge at a third location. The rounded portion may have a rounding radius defined at least at the third location that is greater than 4% of a piston diameter.

A sliding element, for example a piston ring for an internal combustion engine, may include a sliding face, an adhesive layer disposed on the sliding face, and a coating disposed over the adhesive layer. The coating may be composed of an amorphous carbon material. The coating may have a ratio between sp.sup.3 bonds and sp.sup.2 bonds that indicates a predominance of sp.sup.2 bonds. The coating may have a roughness profile including a value of Rpk of 0.15 m and a value of Rz of 0.7Rz1.5 m.

A sliding element, for example a piston ring for an internal combustion engine, may include a sliding face, an adhesive layer disposed on the sliding face, and a coating disposed over the adhesive layer. The coating may be composed of an amorphous carbon material. The coating may have a ratio between sp.sup.3 bonds and sp.sup.2 bonds that indicates a predominance of sp.sup.2 bonds. The coating may have a roughness profile including a value of Rpk of 0.15 m and a value of Rz of 0.7Rz1.5 m.

The present disclosure provides a sealing ring assembly with one or more piston-integrated gap cover features, configured to seal a high-pressure region from a relatively lower pressure region of a piston and cylinder device. The sealing ring assembly may include two rings which each may include one or more ring segments. The one or more gap-cover features, which may be in the form of protrusions in the piston ring groove, may engage with corresponding flat sections of the ring segments. As the sealing ring wears, the gap-cover features may stay engaged with the ring segments, thereby maintaining a seal.

The present disclosure provides a sealing ring assembly with one or more piston-integrated gap cover features, configured to seal a high-pressure region from a relatively lower pressure region of a piston and cylinder device. The sealing ring assembly may include two rings which each may include one or more ring segments. The one or more gap-cover features, which may be in the form of protrusions in the piston ring groove, may engage with corresponding flat sections of the ring segments. As the sealing ring wears, the gap-cover features may stay engaged with the ring segments, thereby maintaining a seal.

A side rail (1) is formed in a sprit ring shape with an opening (10) and to be mounted on a space expander (2) in an annular shape to constitute, together with the space expander (2), a multi-piece oil ring (3) used in an internal combustion engine. The side rail (1) includes an outer peripheral surface (14) facing radially outward, an inner peripheral surface (13) facing radially inward, a first axial surface (11) facing a crankcase, a second axial surface (12) facing a combustion chamber and parallel to the first axial surface (11), and a protrusion (20) formed on the outer peripheral surface (14) in a position offset from an intermediate position between the first axial surface (11) and the second axial surface (12) toward the first axial surface (11) and protruding radially outward from the outer peripheral surface (14).

A side rail (1) is formed in a sprit ring shape with an opening (10) and to be mounted on a space expander (2) in an annular shape to constitute, together with the space expander (2), a multi-piece oil ring (3) used in an internal combustion engine. The side rail (1) includes an outer peripheral surface (14) facing radially outward, an inner peripheral surface (13) facing radially inward, a first axial surface (11) facing a crankcase, a second axial surface (12) facing a combustion chamber and parallel to the first axial surface (11), and a protrusion (20) formed on the outer peripheral surface (14) in a position offset from an intermediate position between the first axial surface (11) and the second axial surface (12) toward the first axial surface (11) and protruding radially outward from the outer peripheral surface (14).

An arrangement may include one of a cylinder liner or a cylinder bore formed in a crankcase of an internal combustion engine, a piston having a peripheral top land and being accommodated in the cylinder liner or cylinder bore, and an annular insert accommodated in the cylinder liner or cylinder bore and extending axially parallel to the piston top land. The cylinder liner or cylinder bore may have a radially inwardly-directed shoulder at an upper free end of the cylinder liner or cylinder bore. The annular insert may have along an upper peripheral free edge of the annular insert, distributed around a circumference of the annular insert, at least two beads or embossments located opposite one another and resting on the radially inwardly-directed shoulder.