Barrel-Faced Compression Ring for Low-Temperature Friction Control
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Solution Overview
Problem
In internal combustion engines, especially those operating in high oil viscosity states due to low oil temperature, reducing friction between the cylinder inner wall and piston rings is challenging, as reducing the curvature radius of the top ring's outer peripheral surface can increase surface pressure and lead to unnecessary oil scraping and solid contact, potentially increasing friction.
Innovation Solution
A compression ring with a symmetric barrel-shaped outer peripheral surface, featuring a maximum diameter peak and specific curvature radii in different regions to maintain contact area and reduce shear resistance, ensuring a condition where the drop from the peak to adjacent points is less in the boundary lubricating region and greater in the fluid lubricating region, thereby minimizing friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the curvature radius of the outer peripheral surface is reduced to reduce contact area and shear resistance, then friction in the fluid lubricating region is reduced, but surface pressure increases causing unnecessary oil scraping and solid contact, which increases friction in the boundary lubricating region
Solution Approach 1:
The outer peripheral surface is designed with different curvature radii in different regions: a first curvature radius in the boundary lubricating region (near top and bottom dead centers) to maintain oil film stability, and a second curvature radius in the fluid lubricating region (mid-stroke area) to reduce shear resistance. This local differentiation allows each region to have optimal friction characteristics for its operating conditions.
Solution Approach 2:
The outer peripheral surface is segmented into multiple regions with different curvature characteristics. The surface is divided into a boundary lubricating region portion and a fluid lubricating region portion, each with specifically optimized curvature radii to address the distinct lubrication requirements of each zone during piston operation.
2Ease of operation
If the curvature radius of the outer peripheral surface is reduced to reduce friction in the fluid lubricating region, then shear resistance decreases, but the contact area with the cylinder inner wall is reduced, causing runout of the oil film in the boundary lubricating region
Solution Approach 1:
Different regions of the outer peripheral surface are assigned different curvature radii tailored to their specific lubrication needs. The boundary lubricating region maintains a larger first curvature radius to preserve contact area and prevent oil film runout, while the fluid lubricating region uses a smaller second curvature radius to reduce shear resistance and friction.
Solution Approach 2:
The curvature radius parameter is varied across different regions of the outer peripheral surface. By changing the curvature radius from the first value (in boundary lubricating region) to the second value (in fluid lubricating region), the patent optimizes both oil film stability and friction characteristics across the entire operating range.
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
This configuration reduces friction in both the fluid and boundary lubricating regions, preventing oil film runout and maintaining airtightness, thus enhancing the engine's efficiency and reducing oil consumption.
Implementation Method 1
reduce shear resistance of an oil film to reduce friction in a fluid lubricating region with a relatively thick oil film between the cylinder inner wall and the outer peripheral surface of the ring
Implementation Method 2
boundary lubricating region where the oil film is thin and the cylinder inner wall is in solid contact with the outer peripheral surface
Data Source
AI summary
An outer peripheral surface of a compression ring includes a barrel curved surface, in a case where a width of the outer peripheral surface in an axial direction of the compression ring is set as L1, a condition of 0.2 mm≤½×L1 is satisfied, and in a case where a distance in a radial direction of the compression ring between an outer peripheral peak and each of two points on the barrel curved surface separate from the outer peripheral peak by 0.1 mm in the axial direction of the compression ring is set as d1, and a distance in the radial direction of the compression ring between the outer peripheral peak and each of two points on the barrel curved surface separate from the outer peripheral peak by ¼×L1 in the axial direction of the compression ring is set as d2, a condition of d1<d2 is satisfied.