Molded Electric Wire Insulator Surface Roughness for Airtight Sealing
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Solution Overview
Problem
Molded electric wires used in applications like automobiles and electronic devices face challenges in achieving high airtightness between the molded resin part and the cable, with existing solutions failing to maintain reliability and waterproofing effectively.
Innovation Solution
A molded electric wire design featuring a conductor wire coated with a thermoplastic polyurethane insulating member having an arithmetic average surface roughness of 5 μm to 100 μm, and a molded resin part directly coating the terminal of the insulating member, which enhances adhesion and maintains airtightness through the use of polyamide or polybutylene terephthalate and optional matting agents like inorganic compound powders or crosslinked polymer particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the molded resin part is coated to the sheath terminal to increase airtightness, then the adhesion between sheath and molded resin part must be enhanced, but this increases the size of the molded resin part and complicates the cable routing
Solution Approach 1:
The invention extracts the coating target from the sheath terminal to the insulator terminal. By removing the sheath coating requirement and only coating the insulator terminal with the molded resin part, the solution reduces the size of the molded resin part while maintaining airtightness through direct coating on the smaller insulator surface.
Solution Approach 2:
The invention segments the coating function by having the insulator provide the primary coating surface for the molded resin part, while the sheath serves a different protective function. This segmentation allows the molded resin part to be smaller since it only needs to coat the insulator terminal rather than the entire sheath terminal.
2Reliability
If the molded resin part is coated to the sheath terminal to enhance airtightness, then the adhesion between sheath and molded resin part must be enhanced, but this increases the bending radius of the cable
Solution Approach 1:
The invention extracts the coating function from the sheath to the insulator. By coating only the insulator terminal with the molded resin part rather than the sheath terminal, the cable achieves adequate airtightness with a smaller molded resin part, thereby reducing the bending radius and improving cable flexibility and routing ease.
3Reliability
If the surface roughness of the insulating member is increased to enhance adhesion with the molded resin part, then the airtightness is improved, but the surface finish of the insulator deteriorates
Solution Approach 1:
The invention applies local quality by creating surface roughness only at the terminal portion of the insulator where the molded resin part makes contact. The main body of the insulator maintains a smooth surface finish, while the terminal area has increased roughness to enhance adhesion with the molded resin part, thus resolving the contradiction between adhesion and overall surface finish.
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 solution ensures excellent airtightness and improved handleability of the electrically insulated wires, maintaining airtightness even after 1000 cycles of heat shock testing, while reducing the size of the molded resin part and enhancing cable routing.
Implementation Method 1
enhancing the adhesion between the insulator and the molded resin part
Data Source
AI summary
A molded electric wire is composed of a conductor wire, an insulating member coating a circumference of the conductor wire, including a thermoplastic polyurethane, and having an arithmetic average surface roughness of not smaller than 5 μm and not greater than 100 μm, and a molded resin part directly coating a terminal of the insulating member.