Wire Harness Grommet Rib Structure for Low-Force Stable Assembly
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Solution Overview
Problem
Conventional grommets require high insertion force during assembly into a through hole in a wall body, and there is a need to maintain the assembled state effectively while reducing frictional resistance.
Innovation Solution
A grommet design featuring a fitting body with a cylindrical portion that gradually reduces in diameter, equipped with ribs that allow elastic deformation and supported by first and second support portions to suppress deformation, along with a locked portion to enhance rigidity and maintain the assembled state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If ribs are provided on the fitting body to reduce frictional resistance, then insertion force is reduced, but the ribs may undergo excessive elastic deformation affecting assembly stability
Solution Approach 1:
The patent applies local quality by providing support portions at specific locations on the ribs - specifically at the base and at intermediate positions - to create localized areas of enhanced rigidity while maintaining the overall elastic deformability of the rib structure. This allows the ribs to deform elastically for reduced insertion force while the support portions prevent excessive deformation and maintain assembly stability.
Solution Approach 2:
The patent creates a composite structural system combining the elastic rib material with the rigid support portions (which may be reinforced or structurally differentiated). This composite approach allows the ribs to exhibit both elastic deformability for easy insertion and structural rigidity through the support portions to maintain assembled state stability.
2Stability of the object's composition
If the fitting body is made more rigid to maintain assembled state, then assembly stability is improved, but insertion force increases
Solution Approach 1:
The patent segments the fitting body into distinct functional zones: the ribs provide elastic deformability for easy insertion, while the support portions provide localized rigidity for maintaining assembled state. This segmentation allows different parts of the same structure to have different mechanical properties, resolving the contradiction between rigidity and ease of insertion.
Solution Approach 2:
The patent creates a dynamic structure where the ribs can deform elastically during the insertion process to reduce insertion force, but the support portions ensure that once assembled, the structure maintains its stability. The structure transitions from a deformable state during insertion to a stable locked state after assembly.
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 design reduces insertion force by minimizing frictional resistance and maintains the assembled state through effective suppression of elastic deformation, ensuring easy assembly and secure fit.
Implementation Method 1
the rib is shaped to enable elastic deformation in the circumferential direction
Implementation Method 2
the first support portion and the second support portion project from the outer circumferential wall surface to be high enough to suppress elastic deformation of the rib in the circumferential direction toward the outer circumferential wall surface
Data Source
AI summary
A grommet includes a fitting body causing a circumferential edge portion of a through hole provided in a wall body to be fitted into a fitting groove provided in an outer wall, and a first cylinder and a second cylinder causing a harness body to be extracted through the cylinder. The fitting body includes a cylindrical portion, a plurality of ribs rising from an outer circumferential wall surface of the cylindrical portion and disposed on the outer circumferential wall surface at equal intervals in a circumferential direction, and a first support portion and a second support portion provided for each of the ribs. The first support portion and the second support portion project from the outer circumferential wall surface to be high enough to suppress elastic deformation of the rib in the circumferential direction toward the outer circumferential wall surface.