Wire Harness Seal Thin Portion for Heat Degradation
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Solution Overview
Problem
The sealing performance of wire harnesses in automobiles deteriorates due to heat-generated degradation of the sealing member, leading to a decrease in surface pressure and potential gaps between the sealing member and the covering material, compromising the water-tight seal.
Innovation Solution
Incorporating a thin portion in the covering material, thinner than the rest, at the radial overlap with the seal, reduces deformation and maintains sealing performance even as the sealing member deteriorates, with the thin portion formed by compressing the material inward in the radial direction and positioned away from the end, facilitating easy positioning and formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing member is provided between the connector housing and the covering material to prevent liquid entry, then sealing performance is initially achieved, but deterioration of the sealing member due to heat causes surface pressure decrease and potential gap formation, compromising long-term sealing reliability
Solution Approach 1:
The patent creates a thin portion in the covering material at the seal contact position before the sealing member deteriorates. This pre-formed thin section ensures that even when the sealing member loses surface pressure due to heat deterioration, there is minimal material to deform, thereby preventing gap formation and maintaining sealing performance throughout the service life.
Solution Approach 2:
The covering material is designed with non-uniform thickness, featuring a localized thin portion at the radial overlap position with the seal while maintaining normal thickness elsewhere. This local quality change concentrates the sealing function at the critical interface, reducing deformation potential at the seal contact point without compromising the overall structural integrity of the covering material.
2Reliability
If the covering material is deformed by surface pressure from the sealing member to achieve sealing, then initial sealing is achieved, but as the sealing member deteriorates and surface pressure decreases, gaps form between the seal and covering material, reducing sealing effectiveness
Solution Approach 1:
The thin portion is formed in advance in the covering material at the seal interface position. This preliminary structural modification ensures that when surface pressure is applied (either initially or during service), the deformation amount is inherently limited, preventing gap formation even as surface pressure decreases over time due to sealing member deterioration.
Solution Approach 2:
The patent changes the physical parameter of the covering material thickness at the seal contact position, creating a thin portion with reduced radial thickness. This parameter change directly reduces the deformation capacity of the covering material at the critical sealing interface, ensuring maintained contact pressure and sealing effectiveness throughout the component's service life.
3Ease of manufacture
If the thin portion is formed by compressing the covering material inward in the radial direction, then the thin portion can be easily formed after extrusion-molding, but this requires an additional forming step
Solution Approach 1:
The thin portion is formed as a preliminary feature during or after the extrusion-molding process of the covering material. By performing this compression step at an early stage in the manufacturing sequence, the thin portion is established before final assembly, simplifying the overall production process and avoiding the need for complex post-assembly operations.
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 configuration minimizes gap generation between the seal and the thin portion, maintaining sealing performance and allowing for easy formation and positioning of the seal, ensuring the wire harness remains water-tight despite heat-induced deterioration.
Implementation Method 1
a predetermined surface pressure is generated between the sealing member and the covering material of the electric wire that is provided inside the sealing member, thereby sealing (water sealing) between the sealing member and the covering material of the electric wire is performed
Implementation Method 2
deterioration of the seal progresses due to heat generated in the connector, and the surface pressure between the seal and the covering material of the electric wire may decrease
Data Source
AI summary
A wire harness including: an electric wire that includes a core wire and a covering material that covers the core wire; a connector that is attached to an end of the electric wire; and a seal that is interposed between the electric wire and the connector, wherein: the covering material includes a thin portion, which is thinner than other portions of the covering material, at a portion overlapping the seal in a radial direction, the covering material includes a distal-end non-thin portion and a proximal-end non-thin portion on two sides of the thin portion in a longitudinal direction, a first annular stepped surface is formed between the thin portion and the distal-end non-thin portion, and a second annular stepped surface is formed between the thin portion and the proximal-end non-thin portion.