Piston Ring Sliding Pair With Controlled Diamond Abrasive Ratio
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Solution Overview
Problem
The existing sliding mechanisms in internal combustion engines face issues with wear resistance, particularly due to diamond abrasive grains embedded in the thermally sprayed coating, which affect the piston ring's wear resistance, especially in variable compression ratio engines where lubricating oil supply is limited.
Innovation Solution
Controlling the area ratio of diamond abrasive grains in the thermally sprayed iron-based coating within a predetermined range of 0.3 to 1.8% and optimizing the honing process to reduce embedding of abrasive grains in the cylinder bore's end parts, while maintaining surface finish and roundness, improves wear resistance of the piston ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If diamond abrasive grains are embedded in the thermally sprayed coating during honing, then surface finish and roundness of the cylinder bore are improved, but wear resistance of the piston ring deteriorates due to abrasive grains acting on the hard coating
Solution Approach 1:
The invention changes the physical-chemical parameters of the thermally sprayed coating by controlling carbon content (2.0-10.0 mass%) and hardness (200-400 HV). This parameter optimization allows the coating to achieve the right balance: soft enough to prevent excessive embedding of diamond abrasive grains during honing, yet hard enough to maintain wear resistance and protect the piston ring throughout the engine's service life
Solution Approach 2:
The thermally sprayed coating acts as a cushioning layer between the diamond abrasive grains and the piston ring. By pre-establishing this coating with optimized carbon content and hardness, the invention prevents the harmful direct contact between abrasive grains and the piston ring's hard coating, thereby cushioning the wear damage before it occurs
2Reliability
If the thermally sprayed coating is hardened to increase wear resistance, then protection against wear improves, but embedding of diamond abrasive grains increases causing piston ring wear
Solution Approach 1:
The invention optimizes the hardness parameter of the thermally sprayed coating to a specific range (200-400 HV) rather than maximizing it. This parameter change creates an optimal balance: the coating is hard enough to resist wear and deformation, yet soft enough to allow diamond abrasive grains to be removed during honing without excessive embedding, thereby eliminating the harmful effect while maintaining protection
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 controlled area ratio of diamond abrasive grains in the thermally sprayed coating enhances the wear resistance of the piston ring, reducing wear and improving the overall sliding mechanism's performance, especially in engines with variable compression ratios.
Implementation Method 1
The thermally sprayed coating is formed by spraying droplets of an iron-based metal material on a pretreated surface of a bore of a cylinder block that is preheated
Implementation Method 2
Honing of the thermally sprayed coating uses a honing stone containing diamond abrasive grains
Data Source
AI summary
A sliding mechanism of the present invention includes a cylinder bore having a thermally sprayed iron-based coating and includes a piston with a piston ring covered with a hard coating composed mainly of carbon.The thermally sprayed coating has diamond abrasive grains.An area ratio of the diamond abrasive grains to a surface of the thermally sprayed coating is 0.3 to 1.8%, which enables suppressing wear of the piston ring having the hard coating composed mainly of carbon.