Piston Ring Width Layout for Low Blow-By and Friction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In spark ignition engines, reducing blow-by gas while minimizing friction and piston weight is challenging, especially with increasing engine output and high cylinder pressure, as adding more compression rings increases friction and weight.
Innovation Solution
A configuration of three compression rings and one oil ring is used, with the third compression ring having a reduced width and specific axial width distribution, and a tapered shape to maintain strength and reduce blow-by gas, while the oil ring is designed with segments and a spacer expander to enhance sealing, allowing for a balanced axial length and volume distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of compression rings is increased to reduce blow-by gas, then gas seal performance is improved, but friction and piston weight increase
Solution Approach 1:
The patent applies local quality by giving each compression ring different axial widths tailored to their specific positions and functions. The first compression ring has width h1(1), the second has h1(2), and the third has h1(3), with h1(1) ≥ h1(2) and h1(1) ≥ h1(3). This non-uniform distribution optimizes gas sealing at each location while minimizing unnecessary material, thereby reducing overall piston weight while maintaining effective blow-by gas prevention.
2Reliability
If the number of compression rings is increased to reduce blow-by gas, then gas seal performance is improved, but friction increases
Solution Approach 1:
The patent employs parameter changes by precisely controlling the axial widths of compression rings and the total axial length of the ring assembly (h1(TOTAL) ≥ 3.1 mm). By optimizing these dimensional parameters and the distribution of tensions (Ft(1) > Ft(3)), the patent achieves effective gas sealing with only three compression rings, thereby avoiding the increased friction that would result from using more rings.
3Object-affected harmful factors
If the axial width of compression rings is reduced to suppress friction and piston weight, then friction and weight are reduced, but ring strength may be compromised
Solution Approach 1:
The patent applies local quality by distributing axial widths non-uniformly across the three compression rings, with the first ring (h1(1)) having the greatest width to bear the highest loads near the combustion chamber, while the second and third rings have reduced widths where less strength is required. This localized optimization maintains necessary strength at critical positions while minimizing overall material and friction.
Solution Approach 2:
The patent employs asymmetry in the axial width distribution of compression rings, where h1(1) ≥ h1(2) and h1(1) ≥ h1(3), creating an asymmetric profile that matches the non-uniform stress distribution along the piston. The first compression ring near the combustion chamber receives the highest mechanical stress and requires greater width for strength, while rings further down the piston can be narrower, achieving an asymmetric optimization that balances strength requirements with friction and weight reduction.
Data Source
AI summary
A combination of piston rings assembled to a piston includes a first compression ring, a second compression ring, a third compression ring and an oil ring. When an axial width of the first compression ring is h1(1), an axial width of the second compression ring is h1(2), an axial width of the third compression ring is h1(3) and an axial width of the oil ring is h1(4), h1(1)≥h1(2) and h1(1)≥h1(3), and when h1(TOTAL)=h1(1)+h1(2)+h1(3)+h1(4), h1(TOTAL)≥3.1 mm.