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.

To provide a combined oil control ring comprising a pair of upper and lower side rails and an axially corrugated spacer expander having upper and lower portions for automobile engines, which is capable of keeping an excellent oil-controlling function without sticking between a spacer expander and side rails even in a long period of engine operation, the upper and lower portions of the spacer expander have tabs pushing inner peripheral surfaces of the side rails, projections supporting the side rails, and intermediate portions between the tabs and the projections; and each intermediate portion opposing the side rail has a center-raised bottom having a center-raised shape when viewed along a substantially circumferential direction center-raised shape and a radial direction.

A combination of piston rings assembled to a piston of an internal combustion engine includes four compression rings. An outer peripheral surface of a first compression ring includes a barrel surface, an outer peripheral surface of a second compression ring includes an outer peripheral end portion and a taper surface, an outer peripheral surface of a third compression ring includes an outer peripheral end portion and a taper surface, and an outer peripheral surface of a fourth compression ring includes an outer peripheral end portion and a taper surface.

A combination of piston rings assembled to a piston of an internal combustion engine includes four compression rings. An outer peripheral surface of a first compression ring includes a barrel surface, an outer peripheral surface of a second compression ring includes an outer peripheral end portion and a taper surface, an outer peripheral surface of a third compression ring includes an outer peripheral end portion and a taper surface, and an outer peripheral surface of a fourth compression ring includes an outer peripheral end portion and a taper surface.

A combination oil ring includes a pair of upper and lower side rails and a spacer expander arranged there between, the spacer expander including a plurality of upper pieces and lower pieces alternately arranged in a circumferential direction with the pieces axially and circumferentially apart from each other, a coupling piece coupling pieces adjacent to each other, and flange portions formed standing at inner circumferential-side end portions of the upper pieces and the lower pieces so as to press the side rails, and a through hole being formed in the flange portions, wherein side rail support portions that project axially are formed at portions in the circumferential direction of outer circumferential-side end portions of the upper pieces and the lower pieces.

To provide a combined oil control ring comprising a pair of upper and lower side rails and an axially corrugated spacer expander having upper and lower portions for automobile engines, which is capable of keeping an excellent oil-controlling function without sticking between a spacer expander and side rails even in a long period of engine operation, the upper and lower portions of the spacer expander have tabs pushing inner peripheral surfaces of the side rails, projections supporting the side rails, and intermediate portions between the tabs and the projections; and each intermediate portion opposing the side rail has a center-raised bottom having a center-raised shape when viewed along a substantially circumferential direction center-raised shape and a radial direction.

To provide a combined oil control ring comprising a pair of upper and lower side rails and an axially corrugated spacer expander having upper and lower portions for automobile engines, which is capable of keeping an excellent oil-controlling function without sticking between a spacer expander and side rails even in a long period of engine operation, the upper and lower portions of the spacer expander have tabs pushing inner peripheral surfaces of the side rails, projections supporting the side rails, and intermediate portions between the tabs and the projections; each intermediate portion opposing the side rail has at least one groove extending in a substantially circumferential direction is recessed when viewed along a radial direction.

When an insertion groove, into which various parts are inserted, is formed on a sealing member, the present disclosure may maintain a width of an opening of the insertion groove greater than or equal to a predetermined width, facilitating the insertion. A sealing member 30 includes an insertion groove S opening toward an outside of a compartment. A protruding portion 36b is formed on a side face S1 of the insertion groove S, and protrudes toward another side face S2. The protruding portion 36b is connected to the other side face R2 via a connecting portion 36c smaller in strength.

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 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).