Vehicle Resin Module Fixing Strength via Embedded Projection
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Solution Overview
Problem
Synthetic resin strength members in vehicle modules face challenges in maintaining sufficient fixing strength due to creep characteristics and thermal shrinkage, leading to reduced attachment member stability over time, especially when compared to metal components.
Innovation Solution
A vehicle-use resin module design featuring a strength member with a mounting hole and an attachment member having a tubular part with an outer circumferential projection embedded in the circumferential wall, secured with an adhesive, which enhances mechanical retention and durability by preventing gaps and improving resistance to dislodgement in various directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If press-fitting is used to attach the outer fitting to the mounting hole, then assembly is simple, but fixing strength decreases over time due to creep and thermal shrinkage
Solution Approach 1:
The attachment structure is divided into multiple functional elements: the outer circumferential projection for mechanical interlocking, the adhesive layer for chemical bonding, and the metal reinforcer for structural support. This segmentation allows each element to contribute differently to the overall fixing strength, preventing the time-dependent degradation seen in single-method press-fitting
Solution Approach 2:
The solution combines multiple materials and bonding methods: synthetic resin for the strength member, metal for the outer fitting and reinforcer, and adhesive as a bonding medium. This composite approach creates a multi-mechanism attachment system that resists creep and thermal shrinkage better than any single material or method alone
2Reliability
If component thickness of the circumferential wall is increased to improve fixing strength, then attachment stability improves, but manufacturing becomes more complicated
Solution Approach 1:
Instead of uniformly increasing the circumferential wall thickness throughout, the metal reinforcer is strategically placed only at the mounting hole location where attachment strength is needed. This localized reinforcement provides the necessary stability without adding unnecessary material or manufacturing complexity to other parts of the strength member
Solution Approach 2:
The outer circumferential projection is embedded within the circumferential wall, creating a nested structure where the projection fits into a recess or cavity in the wall. This nesting provides mechanical interlocking and distributes stress without requiring significant increases in overall wall thickness
3Strength
If adhesive is applied to the interface, then bonding strength improves, but manufacturing process becomes more complex
Solution Approach 1:
The adhesive is applied in advance to the outer circumferential projection and/or reinforcer before assembly with the strength member. This preliminary application ensures proper bonding coverage and allows the adhesive to begin curing before final assembly, improving bonding strength without requiring complex in-process application systems
Solution Approach 2:
The adhesive acts as an intermediary substance between the metal outer fitting components and the synthetic resin strength member, enabling strong bonding between dissimilar materials. The adhesive layer compensates for surface energy differences and creates a reliable interface that mechanical fastening alone cannot achieve
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 solution provides stable and reliable fixing strength in both axial and torsional directions, enhancing the durability and load-bearing capabilities of the resin module by embedding the outer fitting's projection within the circumferential wall and using a metal reinforcer for increased resistance to dislodgement.
Implementation Method 1
a surface of the tubular part of the outer fitting and a surface of the outer circumferential projection are each directly fixed to the strength member with an adhesive
Implementation Method 2
the outer circumferential projection of the outer fitting is embedded inside a circumferential wall of the mounting hole such that the outer circumferential projection is inserted inside the circumferential wall
Data Source
AI summary
A vehicle-use resin module including a strength member made of synthetic resin and including a mounting hole, and an attachment member attached to the mounting hole and configured to be subjected to an external force. The attachment member includes an outer fitting having a tubular part arranged in the mounting hole in an inserted state. The outer fitting includes an outer circumferential projection projecting to a radially outer side of the tubular part. The strength member is an insertion-molded component having a structure in which the outer circumferential projection of the outer fitting is embedded so as to be inserted inside a circumferential wall of the mounting hole. A surface of the tubular part of the outer fitting and a surface of the outer circumferential projection are each directly fixed to the strength member with an adhesive.