Textured Piston Ring Coating to Prevent Flaking and Crazing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Piston ring coatings in internal combustion engines are prone to flaking and crazing due to harsh engine conditions, which reduces their performance and longevity.
Innovation Solution
A piston ring with a rough outer surface texture and a coating of chromium nitride (CrN) or diamond-like carbon (DLC) is used, where the coating is applied only to the textured end sections of the outer surface, distributing stress and retaining oil effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating is applied to the piston ring to improve performance and reduce wear, then the piston ring durability is improved, but the coating becomes prone to flaking and crazing under harsh engine conditions
Solution Approach 1:
The patent applies a rough texture treatment specifically to the end sections of the piston ring's outer surface, creating local variation in surface properties. This textured region is then selectively coated, concentrating the coating application where it is most needed for wear protection while avoiding uniform coating across the entire surface, thereby reducing stress-related coating failure.
Solution Approach 2:
The rough texture is created on the piston ring surface before the coating is applied. This preliminary surface preparation creates a profile that enhances coating adhesion and distributes stress more effectively, preventing the coating from flaking and crazing during engine operation.
2Reliability
If the outer surface is made rough to improve coating adhesion, then the coating retention is improved, but the surface finish deviates from conventional smooth surfaces
Solution Approach 1:
The rough texture is applied only to specific end sections of the piston ring's outer surface rather than the entire surface. This localized texturing maintains conventional smooth surface finish in the middle sections while providing enhanced coating adhesion where it is most critical at the ends.
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 textured surface coating significantly reduces flaking and crazing, enhancing the durability and performance of the piston ring by distributing stress and maintaining an effective oil film.
Implementation Method 1
the end sections of the outer surface are rough... distributing stress and retaining oil effectively... maintaining an effective oil film
Implementation Method 2
the coating includes chromium nitride (CrN) or diamond-like carbon (DLC)
Data Source
AI summary
A piston ring with a coated outer surface is provided. The coating is disposed on end sections of the outer surface adjacent a gap. Typically, a middle section of the outer surface located between the end sections is not coated. The coating can be formed of CrN or DLC, and the CrN coating can be applied by physical vapor deposition (PVD). The end sections of the outer surface, upon which the coating is applied, are rough. For example, the outer surface can be blasted or otherwise textured to achieve the rough surface. The rough surface retains oil and distributes stress better than a smooth surface, and thus reduces crazing and flaking of the coating.