Cylinder Liner Surface Finish for Friction Reduction
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Solution Overview
Problem
Rigid honing tools used in cylinder liners for internal combustion engines often embed abrasive particles into the surface, leading to increased friction, premature wear, and emission issues due to the formation of deep peaks and valleys, which can break off and cause 'blow by', resulting in poor engine efficiency and environmental problems.
Innovation Solution
A cylinder liner with an internal surface featuring a reduced peak height (Rpk) of ≤0.25 μm, core roughness (Rk) of about 0.2 μm to 0.6 μm, reduced valley depth (Rvk) of about 1.2 μm to 2.5 μm, and specific material ratios (Mr1 and Mr2) is achieved through a four-step honing process that includes rough and finish honing with progressively finer abrasive grits, reducing peak heights and improving surface smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rigid honing tools with coarse abrasive grit are used to form cross-hatch pattern, then oil retention capability is improved, but deep peaks and valleys are created that can break off and cause wear
Solution Approach 1:
The honing process is divided into multiple sequential steps with progressively finer abrasive grits. Each step removes material at a different rate and creates different surface features, allowing the deep peaks from rough honing to be removed by subsequent finish honing steps while retaining the beneficial cross-hatch oil retention pattern.
Solution Approach 2:
The abrasive grit size parameter is changed progressively from coarse to fine across multiple honing steps. This parameter change allows the surface to be shaped first for oil retention (coarse grit creating cross-hatch) and then smoothed to remove harmful peaks (fine grit reducing peak height) without compromising the underlying oil retention structure.
2Manufacturing precision
If finish honing is performed to smooth peaks and valleys, then surface smoothness is improved, but rigid tools embed abrasive particles into the surface
Solution Approach 1:
The patent employs disposable abrasive elements that are consumed during the honing process rather than rigid reusable tools. These abrasive elements fracture and wear away during use, preventing the embedding of hard particles into the surface while still achieving the desired smoothing effect.
Solution Approach 2:
The rigid mechanical honing tool is replaced with a more compliant abrasive system that can deform and fracture during the honing process. This substitution eliminates the hard-on-hard contact that causes particle embedding, replacing it with a more controlled material removal mechanism.
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 process results in a cylinder liner with reduced friction, improved fuel consumption, and lower emissions by minimizing asperity peaks and enhancing oil film uniformity and adhesion, leading to lower hydrodynamic drag and boundary friction, thus reducing wear and improving engine performance.
Implementation Method 1
rough honing the internal surface of the cylinder liner so that the internal surface has a roughness less than the roughness of the formed cylinder liner; finish honing the internal surface of the cylinder liner so that the internal surface has a roughness less than the roughness of the rough honed cylinder liner
Data Source
AI summary
A cylinder liner is disclosed, the cylinder liner having a smoother internal surface of an internal side than known cylinder liners. The internal surface having at least one of a reduced peak height of (Rpk) of ≤0.25 μm, a core roughness (Rk) of about 0.2 μm to about 0.6 μm, a reduced valley depth (Rvk) of about 1.2 μm to about 2.5 μm, a material ratio (Mr1) of ≤10%, and a material ratio (Mr2) of about 70% to about 90%.