Vehicle Junction Box Bus Bar Width Reduction via Fuse Positioning
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Solution Overview
Problem
Conventional electrical junction boxes for vehicles are large due to the need for wide bus bars to manage high electric currents, which increases the overall size of the junction box.
Innovation Solution
The electrical junction box design includes a fuse that connects the bus bars near the power source connections, reducing the length of high current flow and allowing for smaller bus bar widths, with a fuse receiving chamber and inspection hole for easy visibility and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the bus bar width is increased through the full length to prevent heating from high current, then the heating prevention is improved, but the junction box size becomes larger
Solution Approach 1:
The bus bar is designed with varying width along its length: wider at the power source connection end where current enters, and narrower at the fuse connection end. This local quality variation optimizes heat dissipation where needed while reducing overall material usage and junction box size.
Solution Approach 2:
The fuse connection is positioned in the longitudinal direction of the bus bar rather than perpendicular to it. This dimensional arrangement allows the fuse to connect at a point rather than requiring the entire bus bar width, enabling the bus bar to be narrower overall while still handling high current effectively.
2Reliability
If the fuse connection is positioned away from the power source connection, then the current distribution is improved, but the bus bar width must be large throughout the full length
Solution Approach 1:
The fuse connection is arranged in the longitudinal direction of the bus bar, allowing it to connect at a specific point along the length rather than requiring a perpendicular connection that would necessitate full bus bar width throughout.
Solution Approach 2:
The bus bar width is optimized locally: sufficient width at the power source connection to handle high current, and reduced width toward the fuse connection where the current path is already established, minimizing unnecessary material while maintaining reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design allows for a compact electrical junction box by minimizing the width of the bus bars and utilizing space efficiently, while enabling easy inspection of the fuse for operational status.
Implementation Method 1
a large electric current flows through an almost full length of each bus bar. Therefore, for preventing the bus bars from heating
Data Source
AI summary
An electrical junction box including a box main body and a wiring block. The box main body includes a cassette block. The wiring block includes a first bus bar, a second bus bar, and a fuse. Each bus bar includes an electric parts connecting part and the power source connecting part. The electric parts connecting part is connected to electric parts attached to the cassette block. The power source connecting part includes a fuse connecting piece and a connecting piece. A terminal fitting connected to a power source is connected to the connecting piece. The fuse connects the fuse connecting pieces of the bus bars.