Wire Harness Tapered Transition Reduces Stress Concentration
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Solution Overview
Problem
Existing wire harnesses are prone to cracks and breakage due to stress concentration at the continuous portions between flexible and straight tube parts, especially during vehicle vibrations and transportation.
Innovation Solution
A wire harness design featuring a tube-shaped exterior member with a flexible bellows tube part and a straight non-bellows tube part, where the continuous portion includes a tapered section with sloping surfaces to reduce stress concentration, and the tapered portion's thickness is uniform with the surrounding parts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the flexible tube part and straight tube part are formed continuously with each other, then the wire harness can be arranged straight and protected, but stress concentration occurs at the continuous portion causing cracks and breakage
Solution Approach 1:
The patent applies local quality by creating a tapered portion at the continuous portion between the flexible tube part and straight tube part. This tapered portion has a different cross-sectional area compared to the adjacent sections, with the area gradually changing from the flexible tube part to the straight tube part. This localized structural modification redistributes stress away from the continuous portion, preventing stress concentration while maintaining the overall continuous structure for structural integrity.
2Adaptability or versatility
If the flexible tube part is bent during transportation and route wiring, then the wire harness can be adapted to vehicle underfloor routing, but stress concentration occurs at the continuous portion
Solution Approach 1:
The tapered portion is strategically positioned at the continuous portion where stress concentration is most likely to occur during bending and routing operations. This localized geometric modification ensures that when the flexible tube part is bent for adaptation to vehicle underfloor routing, the stress is distributed more evenly through the transition zone, preventing cracks while maintaining routing flexibility.
Solution Approach 2:
The tapered portion is pre-formed during the molding process before the wire harness is installed or bent during routing. This preliminary structural preparation ensures that when the flexible tube part is subsequently bent during transportation or route wiring, the stress concentration is already mitigated by the pre-existing tapered geometry, preventing cracks and breakage.
3Shape
If the straight tube part is formed with a non-bellows tube shape, then the conductive path can be arranged straight, but the transition from flexible to straight tube creates stress concentration
Solution Approach 1:
The tapered portion creates a gradual transition in cross-sectional area between the bellows-shaped flexible tube part and the non-bellows straight tube part. This localized geometric variation allows the straight tube part to maintain its straight arrangement capability while the tapered transition zone prevents stress concentration by distributing mechanical stresses evenly across the shape change.
Data Source
AI summary
A wire harness includes an exterior member having a tube shape. The exterior member includes a flexible tube part formed in a flexible bellows tube shape and a straight tube part. The straight tube part is formed continuously with the flexible tube part so as to arrange the conductive path straight and has a non-bellows tube shape. A continuous portion between the flexible tube part and the straight tube part includes a tapered portion formed in a whole peripheral direction of the exterior member so as to reduce stress concentration in the continuous portion. An inner peripheral surface and an outer peripheral surface of the tapered portion include slopes connecting a top of a bellows projection of the flexible tube part and the straight tube part, or connecting a groove bottom of a bellows recess of the flexible tube part and the straight tube part.