Collapsible Grommet Tube for Wire Harness Sealing
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Solution Overview
Problem
Conventional grommets used in vehicles face challenges in maintaining effective water stopping performance while maintaining workability during assembly, as extending the part to cover the wire harness can make it difficult to pass a leading member through and deteriorate assembly workability.
Innovation Solution
A grommet design featuring a main body part and a tubular part with a halved shape, an open part, and an open/close part that can be rotated to shorten or lengthen the tubular section, allowing for easier assembly and enhanced water stopping by adjusting the tubular shape to cover the wire harness effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tubular part is extended long to cover the wire harness effectively, then water stopping performance is improved, but it becomes difficult to pass a leading member through and assembly workability deteriorates
Solution Approach 1:
The tubular part is designed with a collapsible structure that can dynamically change its length. During assembly, the tubular part is in a collapsed state with short length to facilitate insertion of the leading member and wire harness. After assembly, the tubular part expands to its full length to provide effective water stopping coverage. This dynamic transformation resolves the contradiction between long coverage and easy assembly.
Solution Approach 2:
The tubular part is configured to nest within itself or collapse into a compact form during assembly, similar to nested dolls. This nesting capability allows the long tubular structure to be reduced to a compact size for easy insertion, then expanded afterward to achieve the required coverage length for water stopping, thus resolving the contradiction between length and assembly ease.
2Reliability
If the grommet is designed with a long tubular part to ensure effective sealing, then water stopping performance is improved, but the complexity of the structure increases
Solution Approach 1:
The collapsible tubular structure uses simple dynamic mechanisms such as accordion folds or telescopic sections that can transform between compact and extended states. This dynamic design achieves long effective length when needed for sealing, while maintaining relatively simple construction through repetitive geometric patterns, thus resolving the contradiction between sealing effectiveness and structural complexity.
Solution Approach 2:
The tubular part is constructed from flexible materials that can be formed into collapsible configurations using simple geometric patterns such as accordion folds or telescopic sections. These flexible shell structures achieve long effective length for sealing while maintaining simple construction through repetitive geometric patterns, resolving the contradiction between sealing effectiveness and structural complexity.
Data Source
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AI summary
A grommet (1) includes: a main body part (10) fitted to a penetration hole (101) penetrating an attachment panel (100) along an axial direction (X), stops water at the penetration hole (101). A tubular part is (20) unified with the main body part (10) so as to have a tubular shape, and has the wiring material (W) inserted thereinto. The tubular part (20) includes a halved part (50) formed to have a shape of a part of the tubular part (20) in a circumferential direction, an open part (51) where an inside of the tubular part (20) is open at a position except a position where the halved part (50) is formed in the circumferential direction, and an open/close part (60) formed continuing from the halved part (50) and is able to open and close the open part (51).