A three-part oil scraper ring includes an expander spring and two scraper rings, comprising a ring body (4) having an upper flank (6), a lower flank (8), a ring inner surface (10) and a ring outer surface (12) which has a ring outer contour (14) in cross-section in axial direction (A). The ring body (4) has a height H which corresponds to the greatest distance of the upper flank (6) to the lower flank (8). The ring outer contour (14) forms a running surface (16) which has a radius of curvature R which is smaller than the height H of the scraper ring (2) by a factor between 1.5 to 6, preferably between 3 to 5 and further preferably between 3.5 to 4.5.

An oil scraper ring is provided for pistons (2) of an internal combustion engine having an oil scraper piston ring groove (4) formed without at least one oil drain bore. The scraper ring includes a ring body (6) comprising an upper ring flank (8), a lower ring flank (10), a ring inner side (12), a ring outer side (14) and two abutting surfaces (16, 18). An upper oil scraper rail (20) and a lower oil scraper rail (22) extend in the circumferential direction in spaced apart relation from one another in the axial direction and extend radially to the outside from the ring outer side (14) are arranged on the ring outer side (14). Oil passages (24) running in the radial direction are arranged in a region between the upper scraper rail (20) and the lower scraper rail (22), and at least one groove (26) extends in the radial direction on the lower ring flank (10).

A piston ring includes a body portion presenting a running surface, and a spring member disposed between the body portion and a ring groove of a piston. A running surface of the piston ring presents an upper rail, a lower rail, and a fulcrum disposed between the rails and each extending radially outwardly. An outermost tip of the fulcrum is disposed radially outwardly relative to an outermost surface of the rails, and the running surface presents a convex shape along the fulcrum. The fulcrum contacts an oil film applied to a cylinder wall as the piston reciprocates along the cylinder wall. The spring member presses the body portion of the piston ring toward the cylinder wall and causes the body portion to pivot about the fulcrum to provide for improved control of the oil film, less friction, and reduced oil consumption.

A piston for an internal combustion engine includes a cylindrical piston body defining a longitudinal axis and having a top end and an outer cylindrical surface. A first piston ring groove is formed in the outer cylindrical surface and includes a groove root, an upper surface and a lower surface. The groove root has a variable depth about a circumference of the cylindrical piston body.

A piston assembly for an internal combustion engine includes a cylinder bore and a piston having a plurality of ring grooves, and a ring positioned within a ring groove. The ring includes a cross-section having a lower surface and an outer radial surface that form a scraping corner, an inner radial surface, and an upper surface. The upper surface and the lower surface are generally parallel with one another, and both upper and lower surfaces form a positive first angle with respect to a radial axis, and the outer radial surface forms a second positive angle with respect to a central axis. A constant twist occurs in the ring about a rotational center of the cross-section, the constant twist occurring at each cross-sectional location of the ring about the circumference of the ring and between adjacent free ends of the ring.

A piston ring (2) having increased fatigue resistance includes a plastically deformable material. The piston ring (2) has a running face (4), which is delimited at the top by an upper running face edge (3) and at the bottom by a lower running face edge (1). Compressive stresses are introduced into the upper running face edge (3) and/or into the lower running face edge (1) along at least one part of the circumference, the compressive stresses having been produced by roller burnishing.

Improved liquid lubricated piston ring gas seals with reduced friction and wear compared to prior art rings are disclosed for use in internal combustion engines, gas pumps, and gas compressors. These improved rings allow independent adjustment of the parameters controlling friction and wear, and eliminate the tradeoff between friction and wear typical of prior art rings.

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.

A piston ring may include a metallic base, an outer slide layer and an intermediate layer disposed between the base and the outer slide layer. The base may extend between at least two end regions. The outer slide layer and the intermediate layer may be disposed on an outer radial face of each end region of the base.

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.