Hydrogen Engine Piston Ring Coating for Corrosive Wear Resistance
Solution Overview
Problem
Piston rings in internal combustion engines using hydrogen gas fuel face significant corrosion and wear issues, leading to reduced strength and potential breakage due to the generation of H2O and NOx, resulting in corrosive wear on the upper and lower surfaces.
Innovation Solution
A piston ring designed for hydrogen gas fuel engines, ensuring a transverse rupture strength maintenance rate of 0.75 or more, with specific surface roughness and corrosion resistance coefficients (KDA and KDV) maintained through appropriate material selection and surface treatments like PVD or DLC coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a piston ring is used in a hydrogen gas fuel engine, then the engine can achieve cleaner combustion and reduced CO2 emissions, but the piston ring experiences corrosive wear from condensed water and H2O/NOx generation, leading to reduced strength and potential breakage
Solution Approach 1:
The patent establishes specific parameter thresholds (transverse rupture strength maintenance rate FPS≥0.75, arithmetic mean roughness Ra≤0.8μm, maximum valley depth Rv≤12μm) to ensure the piston ring maintains sufficient strength after corrosion exposure. These quantified parameters provide clear design targets for material selection and surface treatment processes.
Solution Approach 2:
The patent implements surface treatments (such as PVD, DLC, or nitriding) and material selections before the piston ring is installed in the engine. These preliminary actions create a corrosion-resistant surface layer that prevents corrosive wear from condensed water and combustion byproducts, thereby maintaining the piston ring's structural integrity throughout operation.
2Measurement precision
If the piston ring is subjected to corrosion testing in 1% aqueous nitric acid solution, then the transverse rupture strength maintenance rate can be evaluated, but the corrosion test itself causes surface roughening and pitting that reduce the piston ring strength
Solution Approach 1:
The patent applies surface treatments (PVD, DLC, nitriding, etc.) beforehand to create a protective layer that resists corrosion. When the piston ring is subsequently exposed to corrosive environments (condensed water or nitric acid testing), this pre-applied protective action prevents significant strength degradation, allowing the ring to maintain FPS≥0.75 even after corrosion exposure.
Solution Approach 2:
The patent employs composite structures consisting of a base material (such as cast iron or steel) combined with a surface treatment layer (such as DLC, PVD coating, or nitrided layer). This composite approach provides both the mechanical strength of the base material and the corrosion resistance of the surface layer, enabling the piston ring to withstand both corrosion testing and in-service conditions.
Data Source
AI summary
Provided is a piston ring that is used in an internal combustion engine that uses a hydrogen gas fuel. In the piston ring, the piston ring satisfies 0.75≤FPS in a case in which: the transverse rupture index of the piston ring in a case in which a transverse test is conducted under a predetermined condition is taken as FP1; the post-corrosion transverse rupture index of the piston ring in a case in which the transverse test is conducted after a corrosion test is conducted in which the piston ring is immersed in a 1% aqueous nitric acid solution for 30 minutes is taken as FP2; and the transverse rupture strength maintenance rate FPS of the piston ring is defined as FPS=FP2/FP1.