An oil ring to be attached to a ring groove of a piston for an engine is provided. The oil ring includes two annular ring bodies having a common axis and arranged in tandem, and an expander for biasing the ring bodies radially outward. A sliding surface is formed at an outer circumference of each ring body to bulge radially outward and slides on a cylinder inner circumferential surface. The sliding surface of one of the ring bodies has a tip portion and first and second curved surfaces. In cross sections of the first and second curved surfaces, the first and second curved surfaces are connected while tangent lines to the cross sections at the tip portion align with each other, and when positional change rates are compared between points on the first and second curved surfaces, a change rate of the first curved surface is lower.

A three-piece oil ring for an internal combustion engine may include an expanding element defining at least a first side and a second side opposite the first side. A first upper annular segment may be associated with the first side of the expanding element. A second lower annular segment may be associated with the second side of the expanding element. The first annular segment and the second annular segment may each include a first internal side surface and a second external side surface. A metallic tungsten matrix coating may be disposed on at least one of the expanding element, the first annular segment and the second annular segment via chemical vapor deposition. The coating may contain a tungsten nanocarbide that may include at least one of WC, W2C, W3C and W12C. The coating may include a thickness between 5 μm and 150 μm and a hardness between 1000HV and 3500HV.

Provided is a combined oil ring that further reduces engine oil consumption.

A combined oil ring attached to an oil ring groove of a piston includes: a pair of upper and lower side rails each formed into a flat annular shape, and having a slide contact part that comes into sliding contact with a cylinder; and a spacer expander arranged between the pair of upper and lower side rails. In at least the upper side rail of the pair of upper and lower side rails, a cross-sectional shape of the slide contact part along an axial direction of the piston is a tapered shape linearly spreading from upper to lower parts of the piston; the tapered shape is at an angle of 5 to 30 degrees with respect to a central axis of the spacer expander, and has a vertex of the tapered shape within 0.15 mm from a lower end of the side rail; and a part closer to the lower end than the vertex is formed into a curved shape having a curvature of R0.01 to 0.5.

Provided is a combined oil ring that further reduces engine oil consumption.

A combined oil ring attached to an oil ring groove of a piston includes: a pair of upper and lower side rails each formed into a flat annular shape, and having a slide contact part that comes into sliding contact with a cylinder; and a spacer expander arranged between the pair of upper and lower side rails. In at least the upper side rail of the pair of upper and lower side rails, a cross-sectional shape of the slide contact part along an axial direction of the piston is a tapered shape linearly spreading from upper to lower parts of the piston; the tapered shape is at an angle of 5 to 30 degrees with respect to a central axis of the spacer expander, and has a vertex of the tapered shape within 0.15 mm from a lower end of the side rail; and a part closer to the lower end than the vertex is formed into a curved shape having a curvature of R0.01 to 0.5.

The oil control ring (2) extends in a circumferential direction (2x) about a center (2l) and has a longitudinal axis (2m) that passes through the center (2l), wherein the oil control ring (2) has an end face (2d) that faces the center (2l), and wherein the oil control ring (2) has a first lateral surface (2s), a second lateral surface (2t), and an outer surface (2u) facing away from the center (2l), wherein the oil control ring (2) has a plurality of channels (2c) extending toward the center (2l) on the first lateral surface (2s), said channels being arranged at mutual distances in the circumferential direction (2x) and extending over the entire width of the first lateral surface (2s) in the radial direction and thereby forming a fluid-conducting connection between the end face (2d) and the outer surface (2u), and wherein crown parts (2i) extending in the circumferential direction (2x) are arranged between pairs of channels (2c), wherein each crown part (2i) protrudes beyond the respective channel (2c) in the direction of extent of the longitudinal axis (2m) and forms a lateral channel surface (2w) for the channel (2c), wherein at least one of the crown parts (5i) is designed as a long crown part (2p) and extends over an angular range (α) between 60 degrees and 350 degrees in the circumferential direction (2x). 212×2121.

The present disclosure provides a sealing ring assembly having a ring and one or more gap cover elements, configured to seal a high-pressure region from a lower pressure region of a piston and cylinder device. The ring may be segmented, and the gap cover elements may engage with interfaces between the ring segments. The gap cover elements are configured to move radially outward and wear as the ring wears. The gap cover elements may include, for example, wedge-shaped features that engage with corresponding wedge recesses in the interfaces. The sealing ring assembly may include a high-pressure boundary and a low-pressure boundary. As the sealing ring wears, the gap cover elements stay engaged with the interfaces, so that ring gaps do not form on the low pressure boundary.

The present disclosure provides a sealing ring assembly having a ring and one or more gap cover elements, configured to seal a high-pressure region from a lower pressure region of a piston and cylinder device. The ring may be segmented, and the gap cover elements may engage with interfaces between the ring segments. The gap cover elements are configured to move radially outward and wear as the ring wears. The gap cover elements may include, for example, wedge-shaped features that engage with corresponding wedge recesses in the interfaces. The sealing ring assembly may include a high-pressure boundary and a low-pressure boundary. As the sealing ring wears, the gap cover elements stay engaged with the interfaces, so that ring gaps do not form on the low pressure boundary.

A play-free oil scraper ring has a cross section with a running surface leg having at least one scraper web that is situated on a running surface, an upper piston ring flank leg that is connected to the running surface leg, and the upper surface of which forms an upper piston ring flank. A lower piston ring flank leg is likewise connected to the running surface leg, the lower surface of which forms a lower piston ring flank. The upper and/or the lower piston ring flank leg are/is elastic, taper(s) inwardly in the radial direction, and their/its piston ring flank(s) essentially form(s) a conical surface in an uninstalled state. The uninstalled piston ring has an axial height that exceeds a width of a piston ring groove for which the piston ring is intended.

A cylinder of an internal combustion engine, having a cylinder liner and a cylinder piston guided in the cylinder liner The cylinder piston has multiple ring grooves delimited by ring webs and are separated by the ring webs. Each ring grooves receives a compression ring or an oil scraping ring. Each ring groove is delimited by an upper groove flank, a lower groove flank and a groove base, and each piston ring has a lower ring flank, an upper ring flank a ring back and a section which rests against a radially inner running surface of the cylinder liner. A depression is introduced into the lower groove flank of the at least one ring groove or each ring groove which receives a compression ring and/or into the lower ring flank of the piston ring designed as a compression ring.

A cylinder of an internal combustion engine, having a cylinder liner and a cylinder piston guided in the cylinder liner The cylinder piston has multiple ring grooves delimited by ring webs and are separated by the ring webs. Each ring grooves receives a compression ring or an oil scraping ring. Each ring groove is delimited by an upper groove flank, a lower groove flank and a groove base, and each piston ring has a lower ring flank, an upper ring flank a ring back and a section which rests against a radially inner running surface of the cylinder liner. A depression is introduced into the lower groove flank of the at least one ring groove or each ring groove which receives a compression ring and/or into the lower ring flank of the piston ring designed as a compression ring.