Wiper Arm Head Coupling Bore Corrosion Resistance
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Solution Overview
Problem
The existing wiper arm designs suffer from premature corrosion and appearance deterioration due to the formation of corrosion products within the coupling bore, which are not adequately coated, leading to coating separation and adverse effects on the outer appearance.
Innovation Solution
The arm head incorporates a coupling bore with annular recesses and a radial outer surface, featuring first and second surfaces that intersect at an angle less than 180°, providing a thickened coating area to resist corrosion product growth and separation, while the coupling bore is anodized to prevent corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the coupling bore wall is left uncoated to allow shaft insertion, then the shaft can be properly fitted, but corrosion products form inside the coating near the open end and expand/separate the coating, causing premature appearance deterioration
Solution Approach 1:
The patent applies different surface treatments to different regions of the coupling bore. The inner wall surface receives an anti-glare and rust resistant coating for corrosion protection, while the open end portion remains uncoated to facilitate shaft insertion and allow drainage of corrosion products. This local differentiation resolves the contradiction between coating durability and ease of operation.
Solution Approach 2:
The patent extracts the coating from the open end portion of the coupling bore, creating a coating-free zone where the shaft is inserted. This removal of coating from the critical insertion area prevents corrosion products from forming within the coating and separating it, thereby maintaining coating durability in the coated regions while enabling proper shaft operation.
2Reliability
If the open end of the coupling bore is coated to prevent corrosion, then corrosion resistance improves, but the coating separates due to expansion of corrosion products, adversely affecting outer appearance
Solution Approach 1:
The patent removes the coating from the open end portion of the coupling bore, creating a coating-free drainage zone. This extraction prevents corrosion products from forming within the coating matrix, eliminating the root cause of coating separation and appearance deterioration while maintaining corrosion resistance in the coated inner wall regions.
Solution Approach 2:
The patent converts the potential harm of an uncoated surface (corrosion) into a benefit by designing the open end as a drainage path. Corrosion products that would otherwise accumulate and separate the coating are instead allowed to drain out through the uncoated open end, protecting the overall appearance while maintaining functional corrosion resistance.
3Reliability
If conventional coating methods are used on the arm head, then the outer surface is protected, but the coupling bore wall cannot be adequately coated, leading to corrosion product formation and coating separation
Solution Approach 1:
The patent implements selective coating where the outer surface and inner wall of the coupling bore receive anti-glare and rust resistant coating, while the open end portion remains uncoated. This local quality differentiation achieves adequate coating coverage in critical areas while intentionally leaving the open end uncoated to prevent corrosion product accumulation and coating separation.
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 design effectively suppresses corrosion product growth and retards coating separation, maintaining the outer appearance and reducing premature deterioration, while also simplifying the manufacturing process by reducing the number of molds required.
Implementation Method 1
the coupling bore is anodized to prevent corrosion
Data Source
AI summary
An arm head includes an end portion to which a retainer is pivotally coupled and a surface covered by a coating. The end portion includes a coupling bore. The coupling bore includes an open end. First and second surfaces of the arm head form an annular recess around the open end that extends continuously from the open end. The radial outer surface extends outward in a radial direction from the annular recess. The first surface extends outward in the radial direction from the open end. The first surface is located inward in an axial direction of the coupling bore from the radial outer surface. The second surface extends from the first surface to the radial outer surface at an angle less than 180° with respect to the first surface.