Piston ring for internal combustion engines with increased fatigue strength, and method for producing same
AssigneeFederal-Mogul Burscheid GmbH
InventorsNigel Gray, Stephan Machliner
Life of this patent
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Abstract
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.
Claims17
A piston ring (2) having increased fatigue resistance, comprising a ductile, plastically deformable material, the piston ring (2) having 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),
- characterised in that
- compressive stresses are introduced into the upper running face edge (3) and/or into the lower running face edge (1) at least along a part of a circumference of the piston ring.
The piston ring (2) according to any one of the preceding claims,
- wherein each running face edge (1, 3) into which compressive stresses are introduced by roller burnishing is provided with a bevel by the roller burnishing process.
The piston ring (2) according to any one of the preceding claims,
- wherein each running face edge (1, 3) into which compressive stresses are introduced by roller burnishing is rounded off by the roller burnishing process, wherein the rounded portion has a radius of curvature of 20 μm to 100 μm, preferably between 30 μm and 80 μm, and further preferably between 40 μm and 60 μm.
The piston ring (2) according to any one of the preceding claims,
- wherein the running face (4) is further provided with at least one wear protection coating or a running-in coating.
The piston ring (2) according to any one of the preceding claims,
- wherein the piston ring comprises an iron or steel material or consists substantially or entirely of an iron or steel material.
The piston ring (2) according to any one of the preceding claims,
- wherein the piston ring is formed as a compression ring, rectangular ring, tapered compression ring, piston ring with inner bevel, piston ring with inner angle, tapered compression ring with inner bevel, tapered compression ring with inner angle, double-sided trapezium ring, single-sided trapezium ring or L-shaped compression ring.
The piston ring (2) according to any one of the preceding claims,
- wherein the piston ring is formed as a scraper ring or tapered scraper ring, wherein compressive stresses are introduced into an outer edge (1) of a lower piston ring flank (8) of the piston ring (2) by roller burnishing.
The piston ring (2) according to any one of the preceding claims,
- wherein the compressive stresses are introduced only into a part of the piston ring that has an angular distance from a piston ring gap of at least 45°, preferably 90°, further preferably 135°.
The piston ring (2) according to any one of the preceding claims,
- wherein the compressive stresses are introduced along the entire upper and/or lower running face edge (3, 1) of the piston ring (2).
A method for increasing the fatigue resistance of a piston ring (2) that comprises a ductile, plastically deformable material, the piston ring (2) having 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),
- wherein the method is characterised by
- the introduction of compressive stresses into at least one part of the circumference of the piston ring (2), into the upper running face edge (3) and/or into the lower running face edge (1), wherein the compressive stresses are introduced by roller burnishing.
Dependencies are inferred from the claim text.