Piston Ring Scraping Edge Chipping Resistance via Local Quality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing piston ring designs with PVD coatings are prone to chipping at the scraping edge, reducing their effectiveness and durability, especially in the region of the edge where the hard coating can chip during operation.
Innovation Solution
The method involves nitriding sub-regions of the running surface and recess, followed by applying a PVD topcoat or multi-layer system, and introducing a non-cylindrical contour at the bottom of the recess to create a self-sharpening scraping edge with improved chipping resistance and wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a PVD coating layer is applied to the running surface including the edge region, then wear resistance is improved, but the scraping edge becomes prone to chipping
Solution Approach 1:
The patent applies different surface treatments to different regions of the piston ring: the running surface receives a PVD coating for wear resistance, while the scraping edge region is left uncoated or receives a different treatment to maintain chip resistance. This spatial differentiation of material properties resolves the contradiction between wear resistance and chipping resistance.
Solution Approach 2:
The running surface is segmented into distinct functional zones: a coated region for wear protection and an uncoated or differently treated scraping edge region for maintaining sharpness and resistance to chipping. This segmentation allows each zone to optimize its specific function without compromising the other.
2Productivity
If the scraping edge is made sharp for improved scraping action, then scraping performance is enhanced, but the edge becomes more susceptible to chipping
Solution Approach 1:
The scraping edge is given a locally distinct property by excluding the hard PVD coating from this region, allowing it to remain sharp and effective for scraping while avoiding the brittleness and chipping susceptibility that would result from applying the hard coating to this high-stress area.
3Duration of action of stationary object
If a hard PVD layer is applied to improve wear resistance, then durability is enhanced, but the scraping action is reduced due to chipping
Solution Approach 1:
The PVD coating is selectively applied to the running surface while excluding the scraping edge region, creating a local quality difference that preserves the sharp scraping edge necessary for effective compression while providing wear protection on the bulk of the running surface to ensure long-term durability.
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
This approach enhances the scraping action and reduces the risk of chipping by forming a self-sharpening edge that maintains its sharpness without wear-resistant material, ensuring prolonged performance and reliability.
Implementation Method 1
nitriding at least sub-regions of the running surface and/or a recess
Implementation Method 2
at least one PVD (physical vapor deposition) coating layer is applied to the running surface
Data Source
AI summary
A piston ring, is produced by providing, on the radially outer circumferential surface of a ring-shaped metallic main body, a recess, the metallic main body having a radially outer circumferential surface, a radially inner circumferential surface, and flank surfaces interposed therebetween providing the recess with a contour that deviates from a cylindrical shape at least on the bottom of the recess, providing at least one wear-resistant layer on the outer circumferential surface, including the recess, and at least partially removing an area of the at least one wear-resistant layer on the outer circumferential surface and including an area corresponding to a scraping edge, thereby forming a land having a predefinable width.