Electrical Junction Box Cover Interlock for Live-Part Access Control
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Solution Overview
Problem
Electrical junction boxes face a challenge in balancing the prevention of erroneous touch on live parts and maintainability, as firmly fixing covers to prevent touch impairs the ability to open them during maintenance.
Innovation Solution
The design incorporates a first cover with an interfering portion that moves around a pivot shaft and a second cover with an interfered portion that is arranged on the movement locus of the first cover's interfering portion when closed, ensuring the first cover cannot be opened unless the second cover is opened first, allowing for secure closure during use and easy opening during maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cover is fixed too firmly to the body of the electrical junction box, then the prevention of erroneous touch on the live part is improved, but the maintainability of the electrical junction box deteriorates
Solution Approach 1:
The first cover is designed to be pivotably attached to the body around a pivot shaft, allowing it to dynamically change between a closed state (covering the live part for safety) and an open state (allowing access for maintenance). This dynamic attachment resolves the contradiction by enabling the cover to provide firm protection when closed while still allowing easy opening when needed for maintenance.
2Ease of repair
If the first cover is made openable for maintenance access, then the maintainability is improved, but the prevention of erroneous touch on the live part deteriorates
Solution Approach 1:
The second cover acts as an intermediary element that must be opened first before the first cover can be opened. This intermediate step ensures that the live part remains protected by the first cover during normal operation, preventing erroneous touch, while still allowing maintenance access when the second cover is intentionally opened first.
3Reliability
If the second cover is positioned to interfere with the first cover's movement, then the prevention of erroneous touch is improved, but the device complexity increases
Solution Approach 1:
The cover system is segmented into two separate covers (first cover and second cover) with distinct functions. The first cover provides protection and can be opened for maintenance, while the second cover controls access to the first cover through its interfered portion. This segmentation allows each cover to have a specific role, resolving the contradiction by providing simple, dedicated functions for each cover rather than a single complex cover mechanism.
Data Source
AI summary
An electrical junction box includes a body having an accommodation space, a first cover attached around a pivot shaft of the body to cover a part of the accommodation space, a second cover attached to the body to cover another part of the accommodation space and a conductor portion to transmit electric power. The first cover includes an interfering portion to move around the pivot shaft in accordance with pivoting of the first cover when the first cover is being opened or closed. The second cover includes an interfered portion to be arranged on a movement locus of the interfering portion when the second cover is closed, and not arranged on the movement locus when the second cover is opened. The conductor portion includes a portion arranged in the part of the accommodation space and to be isolated from the outside by the first cover.