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.

The present invention relates to an oil scraper ring spring (1) for an oil scraper ring (3) comprising the oil scraper ring spring (1), an upper and a lower metal ring (21, 22) and provided for being mounted in an oil ring groove of a piston. The oil scraper ring spring (1) comprises a plurality of upper regions (5) and a plurality of lower regions (7) arranged in alternating manner in a circumferential direction so as to be spaced in an axial direction; connecting regions (9) each connecting the adjacent upper and lower regions (5, 7) to each other. Each of the upper and lower regions (5, 7) comprises: a nose section (13) disposed at the inner circumferential end and adapted to push the respectively abutting upper or lower metal ring (21, 22) radially outwardly, and having a through-opening (15); an abutment section (17) extending radially between the nose section (13) and the outer circumferential end and configured to have the respective upper metal ring (21) abutting thereon or the respective lower metal ring (22) abutting thereon; wherein the abutment section (17) has a recess (19) formed therein the depth of which, relative to the abutting area of the abutment section (17), increases in the radial direction towards the through-opening (15), and the width of which increases in the radial direction towards the through-opening (15); wherein the recess (19) in the abutment section (17) has substantially the shape of a half-funnel; wherein the half-funnel has an opening angle of 30 to 150, in particular of 30 to 60, or wherein the upper side edges of the recess (19) span an angular segment of 5-50, in particular 5-15; and wherein increasing the depth and width of the recess (19) radially inwardly together with the through-opening (15) serves to increase and accelerate the oil flow to the piston center.

A combined oil ring in which carbon sludge and the like are not deposited between side rails and a spacer expander even if an internal combustion engine is operated for a long period of time. The combined oil ring includes an outer circumferential end portion of a space forming part and a continuous part that are closed and not open toward the outer circumferential side, thereby reducing carbon sludge deposits.

A three-piece piston oil control ring 2 has an upper, disc-shaped scraping ring 4, a lower, disc-shaped stabilising ring 6, and a circular expander 8 which has projections 10 protruding in the axial direction on an inner face. The circular expander 8 is arranged between the upper scraping ring 4 and the lower stabilising ring 6, wherein the projections 10 each bear inwardly against an inner face 14 of the scraping ring 4 or against an inner face 16 of the stabilising ring 6. An outer radius 18 of the scraping ring 4 is greater than an outer radius 20 of the lower stabilising ring 6, so that there is a radius difference ? between the scraping ring 4 and the stabilising ring 6.

Exemplary oil control rings and methods are disclosed. An oil control ring may include an upper lamella having a first outer radial surface and a lower lamella having a second outer radial surface. An expander ring is in communication with the upper lamella and the lower lamella and generates an expander radial outward force on the lamellas. At least one of the first outer radial surface and the second outer radial surface is comprised of a first contact section and a first tapered section. The first tapered section is configured to generate a first radially inward force greater than or equal to the expander radial outward force when moved in a first direction and a second radially inward force less than the expander radial outward force when moved in a second direction.

Provided is an oil ring (13) for a piston assembly that can minimize the frictional resistance without impairing the oil control function such as the scraping of lubricating oil from the cylinder wall surface by the oil ring. The oil ring consists of an upper side rail (16), a lower side rail (17) and an annular expander (18) interposed between the two side rails, and is received in an oil ring groove (8) with a prescribed vertical clearance (20) that permits tilting of the side rails. An outer peripheral surface (16E, 17E) of each side rail is provided with a radially inward slant. Therefore, during the upward stroke of the piston, the upper side rail tilts in the radially outward direction so that the effective slant angle of the outer peripheral surface of the upper side ring is adjusted to an optimum value.

A combined oil ring in which carbon sludge and the like are not deposited between side rails and a spacer expander even if an internal combustion engine is operated for a long period of time. The combined oil ring includes an outer circumferential end portion of a space forming part and a continuous part that are closed and not open toward the outer circumferential side, thereby reducing carbon sludge deposits.

Provided is an oil ring (13) for a piston assembly that can minimize the frictional resistance without impairing the oil control function such as the scraping of lubricating oil from the cylinder wall surface by the oil ring. The oil ring consists of an upper side rail (16), a lower side rail (17) and an annular expander (18) interposed between the two side rails, and is received in an oil ring groove (8) with a prescribed vertical clearance (20) that permits tilting of the side rails. An outer peripheral surface (16E, 17E) of each side rail is provided with a radially inward slant. Therefore, during the upward stroke of the piston, the upper side rail tilts in the radially outward direction so that the effective slant angle of the outer peripheral surface of the upper side ring is adjusted to an optimum value.

A multi-piece oil scraper piston ring includes a slotted spring element and at least one lamella element which is operatively connected to the slotted spring element and provided with a joint, the spring element being designed as a meander spring that axially receives and radially supports the lamella element, the two end regions of the meander spring being provided with legs that extend approximately parallel to one another and the axial length of which is designed such that the legs at least partially engage in the joint of the lamella element.

In a combination oil ring, when a line passing through a center of a segment width is a first intermediate line, a length of a line segment between a position on an engine combustion chamber side and a position on a side distant from the engine combustion chamber on a contour curve at a position at a distance of 3 m from an outer peripheral vertex toward an inner peripheral side in a segment radial direction is L, and an intermediate line of the line segment L is a second intermediate line, the second intermediate line is located on the side more distant from the engine combustion chamber than the first intermediate line, and the outer periphery vertex of the segment is located on the second intermediate line or on the side more distant from the engine combustion chamber than the second intermediate line.