Grommet Rib Design Reduces Insertion Force
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Solution Overview
Problem
Conventional grommets require high insertion force during assembly and may not maintain a stable assembled state due to frictional resistance, which hinders efficient assembly and protection of wire harnesses in vehicle body panels.
Innovation Solution
A grommet design featuring a tubular portion with ribs and locked portions that allow elastic deformation and reduced friction, combined with projection groups for improved rigidity, enabling lower insertion force and maintaining the assembled state by reducing contact area and frictional resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional grommet design is used with a fitting body inserted into a through hole, then the electric wire is protected from the circumferential edge, but high insertion force is required and frictional resistance is large
Solution Approach 1:
The fitting body is segmented into multiple functional portions: a fitting groove for initial insertion, a tubular portion with gradually reducing diameter for guiding, and ribs for friction reduction. This segmentation allows each portion to perform its specific function optimally, reducing overall insertion force while maintaining protection capability
Solution Approach 2:
Different portions of the fitting body have different local properties: the fitting groove provides initial engagement, the tubular portion provides gradual guidance with reducing diameter, and the ribs provide localized friction reduction. This local quality differentiation resolves the contradiction between protection and ease of insertion
2Reliability
If the fitting body is deformed to guide the circumferential edge into the fitting groove, then assembly is achieved, but the assembled state may not be stable due to elastic deformation
Solution Approach 1:
The fitting groove is designed to receive the circumferential edge before the tubular portion is fully inserted. This preliminary action ensures proper positioning and alignment, preventing unstable assembly while minimizing unnecessary elastic deformation during the insertion process
Solution Approach 2:
The tubular portion has a gradually reducing diameter that changes the geometric parameters during insertion. This parameter change provides a guiding action that stabilizes the assembly process and ensures the circumferential edge is properly seated in the fitting groove, improving assembled state stability
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 design significantly reduces the insertion force required for assembly and maintains a stable assembled state by minimizing frictional resistance and elastic deformation, enhancing the assembly workability and protection of wire harnesses.
Implementation Method 1
the rib is shaped to enable elastic deformation of the rib in the circumferential direction of the outer circumferential wall surface
Implementation Method 2
configured to be locked to an outer circumferential surface of the first tubular body when the first tubular body is shifted relatively to the fitting body along the cylinder axis toward the second tubular body, to suppress elastic deformation of the tubular portion
Data Source
AI summary
A grommet includes a fitting body causing a fitting groove to be fitted to a circumferential edge of a through hole, and a first tubular body and a second tubular body. The fitting body includes a tubular portion, a rib rising from an outer circumferential wall surface of the tubular portion, and a locked portion disposed radially inside the rib, rising from the outer circumferential wall surface, and configured to be locked to an outer circumferential surface of the first tubular body, to suppress elastic deformation of the tubular portion or reduce elastic deformation amount. The rib is elastically deformable in a circumferential direction, and the outer circumferential wall surface has a plurality of projection groups constituted by the locked portion and a plurality of ribs disposed radially outside the locked portion.