Grommet Turning Portion Dynamics for Insertion Force Reduction
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Solution Overview
Problem
Existing grommets require significant inserting force to be mounted on a wire harness in a motor vehicle, and the extendable portion is difficult to extend, especially when a smaller diameter tubular section adheres to a metal pipe, leading to reduced workability and productivity.
Innovation Solution
A grommet design featuring a first diameter tubular section with an outer tubular section and a U-shaped turning portion that automatically extends when inserted into a through-hole, reducing the need for pre-extension and minimizing resistance, allowing for easier attachment to a vehicle body panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the grommet is pushed into the through-hole with the larger diameter tubular section, then the grommet can be mounted on the wire harness, but a relatively great inserting force is required which lowers workability and productivity
Solution Approach 1:
The turning portion is designed to dynamically change shape from a bent state to a straight state during insertion. This dynamic transformation allows the grommet to automatically adjust its geometry in response to the insertion process, reducing the force required to push the larger diameter tubular section through the hole while maintaining secure mounting capability.
2Force
If the turning portion is extended in one stroke before insertion, then the inserting force is decreased, but the turning portion is hard and difficult to extend at the starting time and extension is difficult if the amount of extension is small
Solution Approach 1:
The turning portion transforms dynamically during insertion rather than being pre-extended. The bent turning portion gradually straightens as the grommet is pushed into the through-hole, with the extension amount automatically adjusting to the insertion distance. This eliminates the difficulty of pre-extension while maintaining force reduction benefits.
Solution Approach 2:
The turning portion performs self-extension during the insertion process without requiring external assistance or pre-processing. As the grommet is pushed into the through-hole, the turning portion automatically transforms from bent to straight state, with the extension amount adapting to the specific insertion distance required.
3Reliability
If the smaller diameter tubular section adheres to the metal pipe, then the grommet can be securely mounted, but the smaller diameter tubular section is likely to pass over the given position before the vehicle body latch recess is engaged with the through-hole
Solution Approach 1:
The turning portion's dynamic transformation creates a mechanical interplay between adhesion and geometric change. As the turning portion straightens during insertion, it modulates the adhesion force between the smaller diameter tubular section and the metal pipe, preventing excessive advancement while maintaining secure mounting capability.
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 grommet can be smoothly inserted with reduced force, enhancing workability and eliminating the need for pre-extension of the turning portion, especially when used with pipe harnesses in hybrid or electric motor vehicles.
Implementation Method 1
The turning portion is displaced toward the first diameter tubular section in response to displacement of the first diameter tubular section upon inserting the grommet into a through-hole in a vehicle body panel so that the first diameter tubular section is elongated.
Data Source
AI summary
The grommet disclosed includes a first diameter tubular section that allows a wire harness to pass through, and a second diameter tubular section that is provided on the first diameter tubular section. The first diameter tubular section is provided with an outer tubular section that extends in the axial direction. A projecting end of the outer tubular section is connected to the second diameter tubular section. A vehicle body latch portion is provided on an outer periphery or a resin inner of the second diameter tubular section. A grommet-pushing side of the first diameter tubular section is not secured to a wire harness. A grommet-inserting side of the first diameter tubular section is secured to the wire harness. The turning portion is deformed when the grommet is inserted into a through-hole in a vehicle body panel so that the first diameter tubular section is elongated.