Piston Ring Hard Carbon Coating Tungsten Abrasion
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Solution Overview
Problem
Conventional piston rings face challenges with abrasion resistance and aluminum adhesion when used with aluminum alloy cylinder liners, leading to increased friction loss and reduced engine efficiency.
Innovation Solution
A piston ring with a hard carbon coating containing 0.5 to 5 atom% of tungsten, formed on both the outer peripheral surface and side surfaces, which improves abrasion resistance and prevents aluminum adhesion by optimizing the tungsten content, hydrogen percentage, and carbon crystal structure bonding ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard coating such as a nitride layer or Cr plated layer is formed on a piston ring, then abrasion resistance of the piston ring sliding face is improved, but the cylinder liner is significantly abraded and hard Si particles drop off to induce further abrasion and scuffing
Solution Approach 1:
The patent changes the material composition parameters of the hard carbon coating by controlling the content of one or more elements (Si, Ti, W, Cr, Mo, Nb, or V) within specific ranges (5-40 atom%). This parameter optimization ensures the coating provides sufficient hardness and abrasion resistance while maintaining compatibility with aluminum alloy cylinder liners, preventing the excessive abrasion and Si particle detachment caused by conventional coatings.
Solution Approach 2:
The patent creates a composite hard carbon coating by incorporating specific elements into the carbon matrix. This composite structure combines the low friction and good adhesion properties of carbon with the hardness and abrasion resistance of the added elements, achieving a balance between protecting the piston ring and preventing damage to the cylinder liner.
2Power
If combustion temperature is increased to improve fuel consumption efficiency, then engine performance is improved, but aluminum is easily adhered to the piston ring sliding face
Solution Approach 1:
The patent modifies the chemical composition parameters of the hard carbon coating by incorporating specific elements in controlled amounts. This composition optimization creates a coating that maintains low surface energy and chemical inertness at high temperatures, preventing aluminum adhesion even under elevated combustion conditions while preserving engine performance.
3Object-affected harmful factors
If a resin film containing solid lubricant material is deposited on the piston ring to prevent aluminum adhesion, then initial aluminum adhesion is prevented, but the coating has low abrasion resistance and cannot prevent adhesion for sustained period
Solution Approach 1:
The patent creates a composite hard carbon coating that integrates the adhesion-prevention properties of carbon-based materials with the abrasion resistance of incorporated elements. The resulting coating simultaneously provides sustained aluminum adhesion prevention and high abrasion resistance, overcoming the limitations of pure resin or lubricant-based coatings.
Solution Approach 2:
The patent optimizes the compositional parameters of the coating by controlling the content of specific elements within defined ranges. This parameter control ensures the coating maintains appropriate hardness and wear resistance while preserving the adhesion-prevention characteristics necessary for sustained performance.
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 abrasion of the aluminum alloy cylinder liner and prevents aluminum adhesion, enhancing the piston ring's durability and engine performance by maintaining a low friction coefficient and improved thermal resistance.
Implementation Method 1
A friction loss is generated upon sliding a piston ring with a cylinder liner. It is estimated that the friction loss reduces efficiency by 20 to 30 percent in a whole internal engine.
Implementation Method 2
When aluminum is adhered to side surfaces (upper and lower faces), a groove of the piston is increasingly abraded with the adhered part as a base point, and aluminum is increasingly adhered.
Data Source
AI summary
The present invention provides a piston ring having excellent abrasion resistance to an aluminum alloy cylinder or cylinder liner formed of a mating material and is therefore capable of decreasing abrasion of the mating material. An exemplary piston ring has a hard carbon coating formed on an outer peripheral surface, and the hard carbon coating contains 0.5 atom % or more to less than 5 atom % of tungsten (W).