Water-Stopping Insulated Wire Structure for Bending Durability
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Solution Overview
Problem
Existing insulated electric wires with water-stopping portions suffer from reduced mechanical strength and water-stopping performance when subjected to mechanical loads, such as bending, due to the discontinuous nature of the water-stopping resin application.
Innovation Solution
An insulated electric wire design featuring a conductor with twisted elemental wires and an insulation covering, where the wire includes exposed and covered portions with a continuous water-stopping portion that fills gaps between elemental wires and covers the outer circumference, maintaining uniform outer diameter and high mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the water-stopping portion is formed only at portions where the stranded conductor is exposed (discontinuous application), then the water-stopping resin can be applied efficiently, but the mechanical strength of the water-stopping portion weakens and water-stopping performance cannot be maintained under mechanical loads
Solution Approach 1:
The patent applies water-stopping resin continuously over the exposed portion of the conductor, extending onto the insulation covering at both ends of the exposed portion. This continuous application eliminates gaps in the water-stopping barrier, ensuring that the resin forms an unbroken protective layer that maintains both water-stopping performance and mechanical strength under bending loads.
Solution Approach 2:
The water-stopping resin application is segmented into three distinct functional areas: (1) filling gaps between elemental wires in the exposed portion, (2) covering the outer circumference of the exposed conductor, and (3) adhering to the insulation covering at both ends. This segmentation ensures comprehensive protection while maintaining structural integrity.
2Strength
If the water-stopping portion is formed over a longer region to improve mechanical strength, then the durability under mechanical load increases, but the likelihood that portions in the longer region are influenced by mechanical load increases
Solution Approach 1:
The patent applies different functions to different parts of the water-stopping resin: the central portion fills gaps between elemental wires for water blocking, while the portions at the ends adhere to the insulation covering for mechanical strength. This local differentiation optimizes both water-stopping performance and mechanical durability without requiring excessive resin application length.
3Device complexity
If the water-stopping resin adheres only to cross sections of the insulation covering, then the application process is simplified, but damage such as crack or breakage occurs near the adhesion interface when the electric wire is bent
Solution Approach 1:
The water-stopping resin is applied to extend onto the insulation covering at both ends of the exposed portion before any bending or mechanical stress occurs. This preliminary extension creates a gradual transition zone that distributes mechanical stress, preventing crack initiation at the adhesion interface while maintaining a relatively simple application process.
Data Source
AI summary
An insulated electric wire includes: an exposed portion and a covered portion including the insulation covering, and further includes a water-stopping portion wherein a water-stopping agent is placed over the exposed portion, and part of the covered portion and is adjacent to the exposed portion. The water-stopping portion continuously has: an inter-elemental-wire filling area filled with the water-stopping agent in gaps between conductor elemental wires; an exposed-portion-outer-circumferential area wherein the water-stopping agent covers an outer circumference of the conductor; and a covered-portion-outer-circumferential area wherein the water-stopping agent covers an outer circumference of the insulation covering. In a subject region that is a part of the exposed-portion-outer-circumferential area and is other than a region closer to the covered-portion-outer-circumferential area with a larger outer diameter due to a thickness of the insulation covering, a difference between a maximum and minimum outer diameter is not greater than 12% of the minimum outer diameter.