Piston Ring Hard Film Segmentation for Cylinder Scratch Prevention
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Solution Overview
Problem
Conventional piston rings face challenges in simultaneously achieving wear resistance, gas sealing performance, and oil scraping performance without causing scratches or damage to the cylinder's inner peripheral surface due to differences in hardness between the piston ring base material and the hard film on the sliding surface.
Innovation Solution
A piston ring design featuring a sliding surface with a first section formed of hard film and a second section without hard film, where the second section is positioned inwardly deviated from the first, allowing for wear resistance, gas sealing, and oil scraping performance while preventing scratches on the cylinder surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hard film is formed on the sliding surface of the piston ring to enhance wear resistance, then wear resistance is improved, but the edge portion easily becomes chipped and oil scraping performance deteriorates
Solution Approach 1:
The patent applies local quality by forming a hard film only on specific regions of the piston ring sliding surface (first and second sliding surfaces) while leaving the edge portion (third sliding surface) without hard film. This localized treatment provides wear resistance where needed while maintaining edge sharpness for oil scraping performance, resolving the contradiction between hard film benefits and edge chipping risks.
2Object-generated harmful factors
If the hard film is partially formed to expose the piston ring base material in the edge portion for sharp shape, then oil scraping performance is improved, but sliding surfaces with different hardness come into contact with the cylinder and generate scratches
Solution Approach 1:
The patent implements local quality by creating distinct regions with different properties: hard film-covered regions (first and second sliding surfaces) for wear resistance and soft base material region (third sliding surface at edge) for sharp oil scraping edge. This spatial differentiation allows each region to perform its specific function without causing harmful interactions.
Solution Approach 2:
The sliding surface is segmented into multiple functional zones: the first sliding surface with hard film for main wear resistance, the second sliding surface with hard film for additional protection, and the third sliding surface without hard film for sharp edge oil scraping. This segmentation allows simultaneous optimization of wear resistance and oil scraping while preventing scratch generation through proper material distribution.
3Ease of manufacture
If the second sliding surface is positioned at the same radial position as the first sliding surface, then manufacturing is simplified, but both hard film surfaces contact the cylinder simultaneously causing scratches
Solution Approach 1:
The patent applies asymmetry by positioning the second sliding surface at a different radial position than the first sliding surface. The second sliding surface is offset radially inward relative to the first sliding surface, creating an asymmetric configuration that prevents simultaneous contact of both hard film surfaces with the cylinder, thereby eliminating scratch generation while maintaining manufacturing feasibility.
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 design enhances wear resistance, prevents abnormal wear of the piston ring and cylinder, reduces the risk of scratches, and maintains effective oil scraping performance, thereby improving the overall durability and functionality of the piston ring.
Implementation Method 1
a hard film is formed by a PVD method on a sliding surface of an outer periphery of the piston ring
Data Source
AI summary
A method for producing a piston ring for a cylinder that moves in a sliding direction includes providing a piston ring base material having an upper surface, a lower surface and an outer circumferential surface having a first recess between the upper surface and the lower surface, forming a hard film in the first recess and on a cylindrical surface at a predetermined thickness, and removing, by performing a polishing process on the sliding surface, the hard film formed on the cylindrical surface and a part of the piston ring base material disposed adjacent to the removed hard film, to form a second recess. The second recess is formed by removing an area of the removed part of the piston ring base material as a result of polishing the sliding surface due to a difference in the hardness of the hard film and the piston ring base material.