Piston Ring Curvature for Lower Initial Friction Loss
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Solution Overview
Problem
Existing piston rings in internal combustion engines face challenges in reducing friction loss at the initial stage of use, which affects fuel efficiency.
Innovation Solution
A piston ring design featuring a minute wedge-shaped space formed between the piston ring and the cylinder, achieved by a specific shape of the outer peripheral surface with a convex first and second curved surface and an intermediate surface with a flat portion, promoting conformable sliding and reducing friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the outer peripheral surface of the piston ring is polished to reduce roughness, then oil consumption in initial operation is reduced, but friction loss at the initial stage cannot be sufficiently reduced
Solution Approach 1:
The piston ring outer peripheral surface is designed with a specific curved shape including a first curved surface, second curved surface, and intermediate surface with a flat portion. This curved geometry creates a wedge-shaped space between the piston ring and cylinder, generating hydrodynamic pressure that reduces friction during initial operation, while the polished surface maintains low oil consumption.
2Loss of substance
If the piston ring surface is made smooth through polishing, then oil consumption is reduced, but conformable sliding at the initial stage is insufficient
Solution Approach 1:
The curved outer peripheral surface geometry creates a wedge-shaped space that facilitates conformable sliding between the piston ring and cylinder during initial operation. The specific curvature radii (R1 for first curved surface, R2 for second curved surface) enable the ring to adapt to the cylinder bore while maintaining smooth operation and low oil consumption.
Solution Approach 2:
The intermediate surface with a flat portion acts as an intermediary element between the curved surfaces, providing a transition zone that enhances conformable sliding. This flat portion on the intermediate surface facilitates smooth contact and adaptation during initial operation, improving ease of operation without increasing oil consumption.
3Loss of energy
If a wedge-shaped space is formed between the piston ring and cylinder, then friction loss is reduced, but the device complexity increases
Solution Approach 1:
The wedge-shaped space is generated through the curved geometry of the outer peripheral surface itself, rather than adding separate components. The first curved surface with radius R1, second curved surface with radius R2, and intermediate surface with flat portion work together to create the wedge shape, reducing friction loss while maintaining a relatively simple single-piece ring structure.
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 design effectively reduces friction loss at the initial stage of starting use of the piston ring, leading to improved fuel efficiency and reduced oil consumption.
Implementation Method 1
a reduction in friction loss due to conformable sliding at the initial stage of starting use of the piston ring is promoted
Implementation Method 2
minute wedge-shaped spaces are respectively formed between the first curved surface near the intermediate surface in the piston ring and a cylinder and between the second curved surface near the intermediate surface in the piston ring and the cylinder
Data Source
AI summary
A piston ring includes an annular main body portion having an inner peripheral surface, an outer peripheral surface, and one side surface and the other side surface. The piston ring includes a first curved surface provided on the outer peripheral surface, being convexly curved outwards in a radial direction of the main body portion, a second curved surface provided on the outer peripheral surface, being convexly curved outwards in the radial direction of the main body portion, and an intermediate surface formed to extend in a direction connecting the one side surface to the other side surface connecting the first curved surface to the second curved surface. The intermediate surface has a flat portion formed in at least a part thereof. The width of the intermediate surface in the direction connecting the one side surface to the other side surface is 0.05 mm or more and 0.30 mm or less.