Asymmetric Piston Ring Profile for Low-Friction Oil Sealing
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Solution Overview
Problem
Existing piston ring combinations in internal combustion engines face challenges in reducing friction loss while maintaining effective oil seal performance, with tapered shapes offering excellent oil sealing but increasing friction.
Innovation Solution
A piston ring combination featuring a top ring, a second ring, and an oil ring with convex-shaped outer peripheral surfaces, where the oil ring has segments with protruding surfaces that create a wedge effect to enhance oil sealing and reduce friction by adjusting the barrel width and peak positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tapered shape is used for the piston ring outer peripheral surface, then oil seal performance is improved, but friction loss increases
Solution Approach 1:
The invention applies asymmetry by making the piston ring outer peripheral surface asymmetric in the axial direction. The cross-section shows that the distance from the peak of the convex shape to the combustion chamber side end is different from the distance to the crankcase side end, creating an asymmetric profile that simultaneously achieves low friction and effective oil sealing
Solution Approach 2:
The invention uses curvature by forming the outer peripheral surface with a convex shape that curves outward in the radial direction. This curved profile, rather than a straight tapered shape, reduces the contact area and pressure with the cylinder wall, thereby reducing friction while maintaining oil sealing capability
2Loss of energy
If a barrel-shaped outer peripheral surface is used, then friction is reduced, but oil seal performance deteriorates
Solution Approach 1:
The asymmetric design allows the barrel-shaped convex profile to maintain reduced friction contact while creating an uneven distribution of contact pressure that enhances oil scraping effectiveness on the crankcase side
Solution Approach 2:
The invention applies local quality by concentrating the oil sealing function in specific regions of the outer peripheral surface. The asymmetric convex shape creates localized high-pressure zones that effectively scrape oil from the cylinder wall, while other regions maintain lower contact pressure to reduce overall friction
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 effectively reduces friction loss while maintaining or improving oil seal performance, preventing oil from flowing from the crankcase to the combustion chamber, thereby reducing fuel consumption.
Implementation Method 1
an expander-spacer that biases the pair of segments outward in a radial direction
Implementation Method 2
a piston ring combination featuring a top ring, a second ring, and an oil ring with convex-shaped outer peripheral surfaces, where the oil ring has segments with protruding surfaces that create a wedge effect to enhance oil sealing
Implementation Method 3
to reduce friction generated between an outer peripheral surface (a sliding surface) of each piston ring and a cylinder inner wall
Data Source
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AI summary
In this piston ring combination, a second outer peripheral surface, which is the outer peripheral surface of a second ring, has a second protruding surface curved into a convex shape, and a pair of third outer peripheral surfaces, which are the outer peripheral surfaces of a pair of segments, each have a third outer peripheral area in which a third protruding surface is formed, the third protruding surfaces being curved into convex shapes. In at least one of the pair of third outer peripheral surfaces, the peripheral edge on a crank-chamber side is positioned farther outward in the diametrical direction than the peripheral edge on a combustion-chamber side, and a peak of the third protruding surface is positioned nearer to the crank chamber than the center of the third outer peripheral surface.