Electric Connection Box Fastening Hole Entry Prevention
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Solution Overview
Problem
In electric connection boxes, the recessed portions around the through holes on the attachment surface can cause fastening members to be erroneously inserted, making it difficult to attach the box to a vehicle due to sink marks prevention during resin molding.
Innovation Solution
The attachment surface features a through hole with recessed portions around its edge, equipped with protruding portions that prevent fastening members from entering these recessed areas, ensuring correct insertion and secure attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple recessed portions are provided on the attachment surface to prevent sink marks during resin molding, then manufacturing quality is improved, but fastening members may be erroneously inserted into these recessed portions, worsening attachment reliability
Solution Approach 1:
The recessed portions are segmented into two functional zones: a first recessed portion for preventing sink marks and a second recessed portion with an entry prevention portion that blocks fastening members. This segmentation allows each zone to serve its specific purpose without interfering with the other.
Solution Approach 2:
The entry prevention portion acts as an intermediary element between the fastening member and the recessed portions. It selectively allows the fastening member to pass through the first recessed portion while blocking entry into the second recessed portion, thereby preventing erroneous insertion.
2Ease of manufacture
If the attachment surface is designed with multiple recessed portions for resin molding quality, then manufacturing process is improved, but ease of operation deteriorates due to difficulty in correct fastening member insertion
Solution Approach 1:
Different regions of the attachment surface are given different local qualities: the first recessed portion has an open structure for manufacturing quality, while the second recessed portion has an entry prevention portion for operational guidance. This local differentiation ensures both manufacturing ease and operational simplicity.
Solution Approach 2:
The entry prevention portion creates a visual and tactile distinction between correct and incorrect insertion locations. The presence of the entry prevention portion in the second recessed portion provides clear feedback to the operator, guiding correct fastening member insertion without requiring additional instructions.
Data Source
AI summary
An electric connection box includes a housing configured to accommodate at least one electronic component and an attachment portion provided on the housing, the attachment portion including a through hole through which a fastening member is to be inserted and an attachment surface configured, when the housing is attached to an object, to face the object, the housing being to be attached to the object at the attachment portion by the fastening member. A plurality of recessed portions are provided around an edge portion defining the through hole, the plurality of recessed portions being provided on the attachment surface. At least one of the plurality of recessed portions is provided with an entry prevention portion configured to prevent the fastening member from entering the recessed portion.