Asymmetric Piston Ring Geometry for Wear and Blow-By Reduction
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Solution Overview
Problem
Existing piston ring designs face challenges in wear resistance and reliability, particularly under high engine explosion pressures, leading to increased oil consumption and blow-by volume, which affects emissions and longevity.
Innovation Solution
A piston ring design with an upper side face and lower side face inclined at different angles relative to a reference plane, eliminating the need for a chamfer and optimizing the radial coverage of flat surfaces to reduce wear and enhance twist effect, thereby improving contact area and stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If symmetric upper and lower side faces with equal inclination angles are used, then the ring structure is simple and manufacturing is easier, but severe wear occurs on the lower side face and complex chamfer processing is required
Solution Approach 1:
The patent applies asymmetry by designing the upper side face with a larger inclination angle (α1 = 45°-60°) than the lower side face (α2 = 10°-20°). This asymmetric configuration optimizes the distribution of contact stresses, reduces wear on the lower side face, and eliminates the need for complex chamfer processing while maintaining structural simplicity
Solution Approach 2:
The patent applies local quality by creating different surface characteristics at different locations: the upper side face has a steeper inclination for positive twist effect, while the lower side face has a gentler inclination for reduced wear. The flat surfaces at the ends of both side faces provide additional local contact areas, optimizing stress distribution at critical locations
2Shape
If a large chamfer is provided at the inner side of the upper side face to ensure positive-twist shape, then the ring maintains proper shape during motion, but the manufacturing process becomes complex
Solution Approach 1:
The patent eliminates the need for chamfer processing by using asymmetric inclination angles where the upper side face has a larger angle (45°-60°) compared to the lower side face (10°-20°). This asymmetric design naturally produces the required positive-twist shape during ring motion, replacing complex chamfer operations with a simpler angular configuration
Solution Approach 2:
The patent changes the geometric parameters of the side faces by specifying precise inclination angle ranges (α1 = 45°-60°, α2 = 10°-20°) and flat surface width ratios (0.3-0.7). These parameter optimizations achieve the positive-twist effect and proper ring shape without requiring additional chamfer processing steps
3Reliability
If the lower side face is designed with high wear resistance for high explosion pressures, then the ring endurance improves, but the structure becomes more complex
Solution Approach 1:
The patent uses asymmetric inclination angles with the lower side face having a smaller angle (10°-20°) compared to the upper side face (45°-60°). This asymmetric design naturally directs stresses away from the lower side face, providing enhanced wear resistance and endurance for high explosion pressure applications while maintaining overall structural simplicity
Solution Approach 2:
The patent applies local quality by adding flat surfaces at the ends of both side faces, with the lower flat surface optimized for maximum wear resistance. The width of these flat surfaces is controlled within specific ratios (0.3-0.7 of total side face width), providing localized stress distribution optimization without requiring complex overall structural changes
Data Source
AI summary
A piston ring used for being arranged in a ring groove of a piston of an engine and comprises an upper side face, a lower side face, an upper plane and a lower plane, the upper side face and the lower side face both incline to a datum plane, the datum plane is a plane perpendicular to the reciprocating motion direction of the piston, and the piston ring further comprises the upper plane and the lower plane. The inclination angles of the upper side face and the lower side face relative to the reference plane are different, and the upper plane and the lower plane cover different ranges in the radial direction of the piston ring.