Wire Harness Waterproof Tube Structure for Sharp Bend Protection
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Solution Overview
Problem
Conventional grommets used in vehicles to protect electrical wires from water ingress can degrade when the tube portion is sharply bent and comes into contact with the attachment portion, leading to a reduction in waterproof performance.
Innovation Solution
A waterproof unit comprising a first waterproof tube attached to a vehicle body panel, a second waterproof tube spaced apart, and a first exterior tube with higher flexural rigidity than the first waterproof tube, positioned between them to prevent sharp bending and contact, thereby maintaining the waterproof performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the tube portion is sharply bent in the vicinity of the attachment portion, then the tube portion may come into contact with the attachment portion, but this causes damage to the tube portion and attachment portion leading to degradation in waterproof performance
Solution Approach 1:
The waterproof unit is divided into multiple segments: the first waterproof tube (attachment portion), the second waterproof tube (distal portion), and the first exterior tube (intermediate protective section). This segmentation allows the first exterior tube to bear the bending stress, protecting the first waterproof tube from damage while maintaining overall flexibility for installation.
Solution Approach 2:
The first exterior tube acts as an intermediary protective element between the first waterproof tube and the external environment. It has higher flexural rigidity than the first waterproof tube, serving as a mediator that prevents direct contact and damage between the attachment portion and the sharply bent tube portion.
2Reliability
If the first exterior tube has higher flexural rigidity than the first waterproof tube, then sharp bending and contact are prevented, but this increases structural complexity
Solution Approach 1:
The structure is segmented into functionally distinct parts: the first waterproof tube for sealing, the first exterior tube for mechanical protection with higher rigidity, and the second waterproof tube for distal protection. Each segment serves a specific function, and their combination resolves the contradiction by distributing structural requirements across multiple components.
Solution Approach 2:
Different parts of the waterproof unit have different local qualities: the first exterior tube has higher flexural rigidity than the first waterproof tube to prevent bending damage, while the waterproof tubes maintain their elastic properties for sealing. This local differentiation of mechanical properties allows the structure to meet both protection and sealing requirements without unnecessary overall complexity.
Data Source
AI summary
A waterproof unit including: a first waterproof tube that has a tubular shape and is to be attached to a through hole of a vehicle body panel disposed between a waterproof area that requires waterproofing and a non-waterproof area that does not require waterproofing; a second waterproof tube that has a tubular shape and is to be disposed in the non-waterproof area so as to be spaced apart from the first waterproof tube; and a first exterior tube that has a tubular shape, is disposed between the first waterproof tube and the second waterproof tube, and is coupled to the first waterproof tube and the second waterproof tube, wherein the first exterior tube has higher flexural rigidity than the first waterproof tube to be kept from coming into contact with the first waterproof tube when the waterproof unit is bent in the non-waterproof area.