Electric Junction Box Guide Portion Asymmetry Prevents Tape Slippage
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Solution Overview
Problem
Conventional electric junction boxes experience watertightness issues due to the adhesive tape used to fix electric wires slipping away from the guide portion, creating gaps that can allow water ingress when the vehicle vibrates.
Innovation Solution
The electric junction box features a tubular guide portion with an expanded section towards the tip and outward ribs to prevent the adhesive tape from slipping, ensuring a secure fit around the electric wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cylindrical guide portion with uniform diameter is used, then the manufacturing is simple and the structure is easy, but the adhesive tape slips during vehicle vibration causing water ingress
Solution Approach 1:
The guide portion transitions from a uniform cylindrical shape to an asymmetric tapered shape with larger diameter at the base and smaller diameter at the tip. This asymmetric geometry creates a mechanical interlock with the adhesive tape, preventing it from slipping during vehicle vibration while maintaining manufacturing feasibility through standard molding processes.
Solution Approach 2:
The guide portion employs varying diameter along its length, with the base having a larger diameter and the tip having a smaller diameter. This local variation in geometry creates different functional zones: the larger base provides stability and prevents tape displacement, while the narrower tip allows proper wire guidance, optimizing both security and functionality.
2Stability of the object's composition
If the adhesive tape is continuously wound from the guide portion to the electric wires, then the wires are secured, but the tape moves away during vibration creating gaps
Solution Approach 1:
The tapered geometry of the guide portion creates an asymmetric friction distribution along the adhesive tape. The larger diameter at the base generates greater normal force and friction, anchoring the tape firmly at this location. This prevents the tape from sliding toward the tip during vibration, maintaining continuous contact between the tape, guide portion, and wires without creating gaps.
3Reliability
If a uniform diameter guide portion is used, then the structure is simple, but gaps form between the guide portion and electric wires during vibration
Solution Approach 1:
The tapered guide portion with varying diameter can be manufactured using standard injection molding or extrusion processes. The asymmetric geometry is achieved through simple mold design without requiring complex multi-step fabrication, making the manufacturing process straightforward while effectively preventing gap formation during vehicle operation.
Data Source
AI summary
An electric junction box 1 includes: a box main body 2; and a tubular guide portion 6 projecting from the box main body 2 and guiding a plurality of electric wires 7 to an outside of the box main body 2. While the electric wires 7 are passed through the guide portion 6, a fixing member 8 is continuously wound from the guide portion 6 to the electric wires 7. The guide portion 6 is provided with an expanded portion 67 gradually expanded toward an outside of the guide portion 6 as the guide portion 6 is extended from the box main body 2 to an end portion away from the box main body 2.