Grommet Assembly with Locking Shafts for Low Mold Load
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Solution Overview
Problem
Conventional grommets face challenges in maintaining the assembly of a base member and grommet body due to excessive mold load, especially when the base member is larger and more complex in shape, leading to potential deterioration of the flexible grommet body.
Innovation Solution
A grommet design featuring a cylindrical base member with an annular flange and cylindrical body, combined with an annular grommet body made of a softer, elastically deformable material, utilizing holding shafts and holding holes to securely assemble and lock the components, reducing mold load through strategic mold removal directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the base member and grommet body are integrally molded, then the assembly is strong and unified, but the mold load becomes excessive causing deterioration of the flexible grommet body
Solution Approach 1:
The grommet is divided into two separate components: a base member and a grommet body. These components are assembled together using holding shafts and holding holes with locking portions, rather than being integrally molded. This segmentation reduces the mold load on the flexible grommet body while maintaining assembly strength through the mechanical connection of the separate parts.
2Reliability
If the base member size is increased to accommodate wiring member passage, then the wiring protection is improved, but the mold load on the grommet body increases excessively
Solution Approach 1:
By separating the base member (which provides wiring protection and structural support) from the grommet body (which provides sealing), the patent allows the base member to be sized appropriately for wiring protection without increasing the mold load on the flexible grommet body. The holding shafts and locking portions ensure these separately sized components remain securely assembled.
3Object-affected harmful factors
If separate parts are used for base member and grommet body to reduce mold load, then the mold load is reduced, but the assembly may come apart from usage
Solution Approach 1:
The holding shafts are inserted into the holding holes during assembly, and the locking portions are positioned to engage with the chamfered edges of the holding holes. This preliminary positioning ensures that when the components are assembled, the locking portions automatically engage to prevent disassembly, maintaining assembly stability without requiring additional fastening steps.
Solution Approach 2:
The holding shafts act as intermediary elements that connect the base member and grommet body. The shafts pass through the holding holes and are locked by the locking portions, serving as a mechanical mediator that securely joins the two separate components while allowing them to remain distinct parts with optimized individual functions.
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 effectively maintains the assembly of the base member and grommet body, preventing liquid ingress while minimizing mold-induced stress on the grommet body, ensuring secure and durable attachment.
Implementation Method 1
an annular grommet body made of an elastically deformable synthetic resin material softer than the base member
Implementation Method 2
an annular locking portion in which an annular peripheral edge of the hole body on the second annular wall surface side is chamfered to fit and lock the locked portion
Data Source
AI summary
A hard resin base member includes an annular flange, an elastically deformable soft resin grommet body includes a plurality of shaft-shaped holding shafts protruding toward the flange, and the flange includes, for each of the holding shafts, a through hole-shaped holding hole that allows a first annular wall surface side with which the grommet body is brought into tight contact and a second annular wall surface side on a back side thereof to communicate with each other and allows the holding shaft to be inserted therethrough at an assembly completion position.