Cast Iron Cylinder Liner Roughness for Low-Friction Seizing Resistance
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Solution Overview
Problem
Existing cast iron cylinder liners face challenges in simultaneously reducing friction and ensuring excellent seizing resistance, particularly when lubricating oil viscosity is lowered to reduce friction, leading to increased seizing between the piston ring and cylinder bore.
Innovation Solution
A cast iron cylinder liner with an inner peripheral sliding surface designed to meet specific roughness parameters (Rvk/Rk ≥ 1.0, 0.08 μm ≤ Rk ≤ 0.2 μm, Rk − Rpk > 0.02 μm, and Rk + Rpk < 0.6 μm) and featuring a cross-hatch pattern, achieved through a honing process using diamond honing stones and chemical conversion treatment, enhances lubricating oil retention and reduces friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If lubricating oil viscosity is reduced to decrease friction, then friction loss is reduced, but seizing resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling surface roughness parameters (Rvk/Rk ≥ 1.0, 0.08 μm ≤ Rk ≤ 0.2 μm) to optimize the balance between friction reduction and seizing resistance. This allows the system to maintain reliable seizure resistance even when using lower viscosity lubricating oil.
Solution Approach 2:
The patent utilizes a porous surface structure created through honing with diamond stones, where the surface contains controlled pores and valleys (indicated by Rvk parameter) that retain lubricating oil. This porous structure ensures oil availability at the contact interface, preventing seizing while allowing low-viscosity oil to reduce friction.
2Reliability
If surface roughness is increased to improve lubricating oil retention, then seizing resistance is improved, but friction increases
Solution Approach 1:
The patent resolves this contradiction by changing the surface roughness parameters to specific ranges: Rvk (peak-valley depth) ≥ 1.0 times Rk (core roughness depth), with Rk between 0.08-0.2 μm. This controlled parameter change creates optimal oil retention without excessive friction.
Solution Approach 2:
The patent applies local quality by creating a specific surface structure with cross-hatch patterns through honing, where localized peaks and valleys provide oil retention pockets. The surface has different functional zones: peaks for load bearing and valleys for oil storage, optimizing both friction and seizing resistance.
3Loss of energy
If surface roughness is decreased to reduce friction, then friction loss is reduced, but lubricating oil retention deteriorates
Solution Approach 1:
The patent changes surface roughness parameters to maintain Rk between 0.08-0.2 μm (not too smooth) while ensuring Rvk/Rk ≥ 1.0. This parameter combination preserves sufficient surface texture for oil retention while keeping overall roughness low enough to minimize friction.
Solution Approach 2:
The honed surface creates a controlled porous structure with micro-valleys that act as oil reservoirs. Even though the overall surface is relatively smooth (low Rk), the porous valleys (Rvk) retain lubricating oil, ensuring seizing resistance is not compromised.
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 and enhances seizing resistance by optimizing surface roughness and lubricating oil retention, addressing the limitations of existing technologies.
Implementation Method 1
the inner peripheral sliding surface includes a reduced valley depth Rvk and a core roughness depth Rk, and the reduced valley depth Rvk is equal to or higher than the core roughness depth Rk (Rvk/Rk ≥ 1.0)
Implementation Method 2
enhances lubricating oil retention and reduces friction
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
To reduce a friction, and to provide an excellent seizing resistance. Provided is a cast iron cylinder liner including an inner peripheral sliding surface made of cast iron, and an internal combustion engine including a cylinder bore including an inner peripheral sliding surface made of cast iron, wherein the inner peripheral sliding surface includes a region satisfying Expression (1) to Expression (3), Rvk/Rk≥1.0 0.08μm≤Rk≤0.3μm Rk−Rpk>0 [Rk is the core roughness depth based on JIS B0671-2:2002, Rpk is the reduced peak height based on JIS B0671-2:2002, and Rvk is the reduced valley depth based on JIS B0671-2:2002 in Expression (1) to Expression (3)].