Piston Top Ring Groove Anodizing for Lower Blow-By and PN
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Solution Overview
Problem
Existing piston designs for internal combustion engines face challenges in reducing the flow rate of blow-by gas and particle number due to limitations in surface roughness of the anodized film on the top ring groove, which is difficult to achieve with conventional anodizing treatments.
Innovation Solution
The use of an AC/DC superimposition electrolytic process to form an anodized film on the top ring groove, followed by blasting with a specific pressure and particle diameter of the blasting material, results in a surface roughness of less than 1.0 µm, enhancing the film's smoothness and reducing blow-by gas flow and particle emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anodizing treatment is executed on the top ring groove, then wear resistance and aluminum adhesion resistance are improved, but the surface roughness of the anodized film becomes too high (Ra ≥ 1.1 μm), resulting in increased blow-by gas flow rate
Solution Approach 1:
The patent applies preliminary action by performing blasting treatment on the aluminum alloy piston surface before executing the anodizing treatment. This pre-treatment removes silicon particles and creates a smooth base surface, ensuring that the subsequently formed anodized film achieves the required low surface roughness (Ra < 1.1 μm) while maintaining wear resistance and adhesion properties.
2Reliability
If conventional anodizing treatment is executed on the top ring groove, then aluminum adhesion resistance is improved, but the surface roughness of the anodized film becomes too high (Ra ≥ 1.1 μm), resulting in increased particle number PN
Solution Approach 1:
The patent applies preliminary action by performing blasting treatment on the aluminum alloy piston surface before executing the anodizing treatment. This pre-treatment removes silicon particles and creates a smooth base surface, ensuring that the subsequently formed anodized film achieves the required low surface roughness (Ra < 1.1 μm) while maintaining wear resistance and adhesion properties.
3Object-affected harmful factors
If the anodized film surface is made smoother to reduce blow-by gas flow, then gas-tight sealing is improved, but conventional anodizing processes cannot achieve surface roughness Ra < 1.1 μm due to Si particles
Solution Approach 1:
The patent applies preliminary action by performing blasting treatment on the aluminum alloy piston surface before executing the anodizing treatment. This pre-treatment removes silicon particles and creates a smooth base surface, ensuring that the subsequently formed anodized film achieves the required low surface roughness (Ra < 1.1 μm) while maintaining wear resistance and adhesion properties.
Solution Approach 2:
The patent applies the extraction principle by removing silicon particles from the aluminum alloy surface through blasting treatment before anodizing. This extraction of harmful silicon particles eliminates the cause of surface roughness formation during conventional anodizing, enabling the formation of a smooth anodized film with Ra < 1.1 μm that provides effective gas-tight sealing.
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 significantly reduces the flow rate of blow-by gas and particle number by creating a smoother anodized film with improved wear resistance and gas-tight sealing properties, effectively addressing the limitations of previous technologies.
Implementation Method 1
a step of forming an anodized film on an inner surface of a top ring groove of a piston for an internal combustion engine by an AC/DC superimposition electrolytic process
Implementation Method 2
a step of blasting the anodized film at a shooting pressure ranging between greater than 0.01 MPa and less than 0.05 MPa by using a blasting material having a median particle diameter ranging between greater than 20 μm and less than 50 μm
Data Source
Figure 1~2
Figure 3(a)~3(b)
Figure 4(a)~4(b)
AI summary
[Problem to be Solved] To provide a piston for an internal combustion engine, having a top ring groove provided with an anodized film for reducing the flow rate of blow-by gas and the particle number PN, and a manufacturing method for the same. [Solution] An inner surface 15 of the top ring groove of the piston for an internal combustion engine is anodically oxidized through the AC/DC superimposition electrolytic process to form an anodized film 23a having cells extending in random directions and enclosing a periphery of silicon 16 in a branched structure in the random direction. A blasting process is applied to the anodized film at a shooting pressure ranging between greater than 0.01 MPa and less than 0.05 MPa using a blasting material 50 having a median particle diameter ranging between greater than 20 µm and less than 50 µm to obtain the anodized film 23b having surface roughnesses Rpk and Ra, each of which is less than 1.0 µm.