PVD-Coated Oil Ring Rail for Lower Sliding Resistance
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Solution Overview
Problem
Existing oil rings in internal combustion engines face challenges in further reducing sliding resistance and improving fuel consumption despite nitriding treatments and PVD coatings, as they do not adequately address friction and abrasion resistance.
Innovation Solution
A multi-piece-type oil ring with a rail structure featuring a chromium nitride-based alloy film or hard carbon film, where the outer peripheral face includes a strip-shaped actual land face and inclined faces formed by polishing or grinding, with specific surface texture parameters to enhance sliding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PVD treatment is applied to form a high hardness film on the sliding face, then abrasion resistance is improved, but sliding resistance is not sufficiently reduced
Solution Approach 1:
The invention applies different surface treatments to different regions of the oil ring. The sliding face receives a PVD treatment to form a high hardness film for abrasion resistance, while the inclined face is polished to a specific roughness (Ra: 0.03μm to 0.15μm) to reduce sliding resistance. This local differentiation of surface properties resolves the contradiction between needing high hardness for abrasion resistance and low friction for sliding performance.
2Manufacturing precision
If the outer peripheral face is formed with a stepped shape to reduce land width, then contact face pressure is improved, but sliding resistance increases due to high face pressure
Solution Approach 1:
The invention changes the surface roughness parameter of the inclined face to a specific range (Ra: 0.03μm to 0.15μm) through polishing. This parameter optimization allows the inclined face to maintain sufficient contact face pressure while reducing sliding resistance by creating an optimal surface texture that facilitates lubrication film formation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution significantly reduces sliding resistance and improves fuel consumption by optimizing the surface texture and structure of the oil ring, leading to enhanced engine efficiency.
Implementation Method 1
the rail of the ring body is provided with a film formed by means of a physical vapor deposition treatment
Data Source
AI summary
An oil ring is a multi-piece-type oil ring provided on a piston of an internal combustion engine including a ring body having a rail, and an expander. In the oil ring, the rail of the ring body is provided with a film formed by physical vapor deposition. An outer peripheral face of the rail formed by the film includes: an actual land face formed to have a strip shape extending in a circumferential direction and abutting against and sliding on an inner wall face of a cylinder of the internal combustion engine; and an inclined face continuing from an edge of the actual land face in an axial direction to an outside and having a larger distance from the inner wall face on a further outside in the axial direction. The inclined face includes a face obtained by polishing or grinding a surface of the film along the circumferential direction.