Temporary Fixation Boss for Electrical Junction Box Mounting
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Solution Overview
Problem
Conventional techniques for mounting electrical junction boxes on vehicles face difficulties due to variations in size and shape, leading to high insertion resistance or insufficient holding force, which complicates the mounting process and reduces workability.
Innovation Solution
A temporary fixation boss with a shaft portion, flared portion, and claw portions is designed, where the shaft diameter is smaller than the insertion hole, and the flared and claw portions are strategically positioned to facilitate easy insertion and secure locking, preventing the boss from being released.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the claw or ring is formed with a larger size to increase holding force, then the holding force is improved, but the insertion resistance becomes large and insertion becomes difficult
Solution Approach 1:
The fixation member is divided into multiple claw portions (typically three) distributed around the circumference, with each claw having a specific projection length. This segmentation allows the total holding force to be distributed across multiple contact points, reducing the insertion resistance at each individual claw while maintaining overall holding force.
Solution Approach 2:
Different portions of the fixation member have different properties: the shaft portion has a smaller diameter for easy insertion, while the claw portions have optimized projection lengths to provide sufficient holding force. The claw portions are positioned at specific locations around the circumference to distribute forces locally, allowing easy insertion while maintaining strong holding capability.
2Ease of operation
If the claw or ring is made too small to reduce insertion resistance, then insertion becomes easy, but the holding force becomes insufficient and the bracket may be uplifted
Solution Approach 1:
Instead of using a single large claw, the fixation member employs multiple smaller claws (typically three) arranged around the circumference. Each claw has an optimized projection length that is sufficient to engage the bracket, providing adequate holding force while keeping individual claw sizes small for easy insertion.
Solution Approach 2:
Multiple claw portions work together in combination to provide the total holding force needed. The cumulative effect of three or more claws, each with moderate projection length, achieves the required holding strength without requiring any single claw to be excessively large, thus maintaining ease of insertion.
3Reliability
If a conventional fixation structure is used, then the electrical junction box can be mounted, but the metallic plate bracket is hard to be uplifted and workability is reduced
Solution Approach 1:
The fixation member is designed to be self-fixing through its claw portions that automatically engage with the bracket structure upon insertion. The claws are positioned and sized to naturally lock into place without requiring additional tools or complex operations, making the bracket difficult to uplift while maintaining simple, fast installation procedures.
Data Source
AI summary
A temporary fixation boss includes: a shaft portion; a flared portion; and claw portions. The shaft portion has a diameter smaller than a diameter of an insertion hole. The flared portion is provided at one end of the shaft portion in a manner to be flared in multi steps from an outer periphery of the shaft portion throughout the whole circumference of the shaft portion. The claw portions are so formed that a distance from the shaft center of the shaft portion to a tip end of the claw portions in a radial direction of the shaft portion is larger than a distance from the shaft center to a tip end of the flared portion, and smaller than a distance from the shaft center to the inner edges of the insertion hole when the shaft center is aligned with the center axis of the insertion hole.