DLC-Coated Piston Ring With Protective Deposits for High-Heat Wear
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Solution Overview
Problem
Piston rings in internal combustion engines face challenges in achieving long service life with low friction and wear, particularly in the compression ring area, which is exposed to high gas pressure and temperature stress, necessitating improved wear protection coatings that also optimize running-in behavior.
Innovation Solution
A piston ring design featuring a diamond-like carbon (DLC) functional layer with a protective layer applied using PVD methods, where the protective layer is composed of a material with higher temperature resistance, applied in superficial deposits within the DLC layer's depressions, and strategically distributed to minimize friction and wear, with specific roughness values and thicknesses optimized for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a DLC layer is applied to reduce friction and wear, then friction and wear are reduced, but temperature resistance is insufficient under high gas pressure and temperature stress
Solution Approach 1:
The patent applies a composite coating structure consisting of a DLC (diamond-like carbon) functional layer combined with a protective layer having higher temperature resistance. This composite structure allows the DLC layer to provide friction and wear reduction while the protective layer withstands high temperature stress, resolving the contradiction between low friction/wear performance and temperature resistance.
2Temperature
If a protective layer is applied over the entire running surface, then temperature resistance is improved, but running-in behavior deteriorates due to additional interaction of internal stresses
Solution Approach 1:
The patent applies the protective layer selectively only on partial surfaces of the piston ring running surface rather than the entire surface. This local application approach allows the protective layer to provide temperature resistance where most needed while avoiding excessive stress interaction in areas where it would harm running-in behavior, thus resolving the contradiction between temperature resistance and running-in performance.
3Temperature
If the protective layer thickness is increased to improve temperature resistance, then temperature resistance is improved, but the coating is more prone to premature damage
Solution Approach 1:
The patent optimizes the thickness parameter of the protective layer to a specific range that balances temperature resistance and durability. By carefully controlling the protective layer thickness, the coating achieves sufficient temperature resistance without becoming overly thick and prone to premature damage, thus resolving the contradiction between temperature resistance and coating strength.
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 significantly reduces wear and improves running-in behavior, with layer wear decreased by approximately 15% and gusset wear by 25% over 100 hours of engine testing, enhancing the overall durability and efficiency of the piston ring.
Implementation Method 1
The protective layer can be applied by a PVD method
Data Source
AI summary
The invention relates to a piston ring which is provided with a DLC (Diamond-like Carbon) layer as a functional/wear protection layer, wherein the DLC layer is covered by a protective layer, the material of which is different from that of the DLC layer and the material of which has a higher temperature resistance than the material of the DLC layer. In addition, the invention relates to a method for producing a piston ring having a DLC wear protection layer, the protective layer being provided in the surface thereof in the form of deposits in recesses present as a result of the surface roughness.