Junction Box Nut Retention and Bolt Tip Insulation Structure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrical junction boxes face issues with nut instability and insufficient insulation between bolt tips and peripheral components, leading to concerns about assemblability and insulating properties, especially when conductive housing components are nearby.
Innovation Solution
An electrical junction box design featuring a housing with a through hole and cap configuration, where the cap with insulating properties closes the second end side of the through hole, preventing nut dislodgment and ensuring insulation between the bolt tip and peripheral components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a through hole is adopted as a hole having a first end side opened in a bus bar placement surface, then the nut can be inserted and accommodated in the through hole, but the nut may unintentionally come off from the opening at the second end side of the through hole before the bolt is fastened
Solution Approach 1:
A guide member is introduced as an intermediary component between the nut and the through hole. The guide member has a guide hole that receives the nut and a protruding portion that engages with the housing to prevent the nut from coming off. This intermediary structure enables easy nut insertion while ensuring reliable retention without requiring complex through hole designs.
2Device complexity
If the through hole is used to accommodate the nut, then the structure is simple, but the tip end surface of the bolt leg portion is exposed to the outside via the opening at the second end side, compromising insulating properties when conductive housing is nearby
Solution Approach 1:
The guide member acts as an insulating intermediary between the conductive housing and the exposed bolt tip. The guide member includes an insulating portion that covers the opening at the second end side of the through hole, preventing direct contact between the bolt tip and conductive housing. This maintains structural simplicity while eliminating insulation failure risks.
Solution Approach 2:
The guide member incorporates an insulating portion that functions as a protective shell or covering over the exposed bolt tip area. This thin film-like insulating structure effectively isolates the conductive elements from the conductive housing without adding significant complexity to the overall design.
3Ease of operation
If the opening at the second end side of the through hole is left open for nut insertion, then assembly is simplified, but insulating properties between the bolt and peripheral components cannot be sufficiently ensured
Solution Approach 1:
The guide member is pre-installed on the housing before the nut assembly process. The guide member includes a guide hole that facilitates easy nut insertion while simultaneously providing insulating coverage. This preliminary action ensures both ease of operation during assembly and reliable insulation throughout the product lifecycle.
Solution Approach 2:
The guide member serves as a dual-function intermediary: it provides a guided path for easy nut insertion through its guide hole, and simultaneously ensures insulation reliability by covering the opening at the second end side with its insulating portion. This single intermediary component resolves both requirements effectively.
Data Source
AI summary
An electrical junction box includes a housing, a bus bar, a nut, and an insulating cap. A through hole of the housing has a first end side and a second end side, and the first end side is opened in a bus bar placement surface of the housing. The bus bar is placed on the bus bar placement surface and is fixed to the housing such that a first bolt hole of the bus bar and the through hole communicate with each other. The cap is attached to the housing. A terminal having a second bolt hole is fixed to the bus bar by fastening a bolt inserted into the second bolt hole and the first bolt hole in this order to the nut so as to sandwich the bus bar and the terminal.