Electric Fuse Torque-Restricting Terminals
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Solution Overview
Problem
Electrical fuses used in high voltage electric vehicle systems face challenges in handling high currents and voltages, and the bolted connection method can cause mechanical damage to the fragile fuse elements due to torque forces, making it difficult to predict and detect damage during installation.
Innovation Solution
The use of terminal elements that are movable relative to the fuse element ends, which restricts torsional forces from reaching the delicate fuse element portion, thereby preventing mechanical damage during bolted connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the fuse is bolted directly to circuit conductors, then the connection provides good heat dissipation, but the bolt torque can damage the fragile fuse element
Solution Approach 1:
The fuse assembly is segmented into distinct functional components: the fuse element (with tab) and the terminal element. This segmentation allows the terminal element to bear the mechanical torque from bolting while the fuse element remains protected, resolving the contradiction between heat dissipation needs and mechanical protection.
Solution Approach 2:
The terminal element acts as an intermediary between the circuit conductor and the fuse element. It provides the mechanical connection interface for bolting while isolating the fragile fuse element from direct mechanical stress, thus protecting the fuse element while maintaining good thermal contact through the conductor.
2Reliability
If the fuse element is made with reduced cross-sectional areas for current limiting, then the fuse can reliably open at overcurrent conditions, but the fuse element becomes more susceptible to mechanical damage during installation
Solution Approach 1:
The vulnerable portions (reduced cross-sectional areas) are extracted from the terminal connection region and placed only in the fusible portion of the fuse element. The terminal element and tab are made with uniform cross-sections that can withstand mechanical stresses, thus taking the weakness out of the mechanical connection path while preserving it in the fusible path.
Solution Approach 2:
Different parts of the fuse assembly have different structural qualities optimized for their specific functions. The fuse element has reduced cross-sectional areas localized to the fusible portion for reliable opening, while the tab and terminal element have uniform cross-sections for mechanical strength during installation and operation.
3Strength
If terminal elements are made movable relative to fuse element ends, then torque forces are restricted from reaching the fuse element, but the connection complexity increases
Solution Approach 1:
The terminal element is designed with rotational freedom relative to the fuse element tab, allowing it to move dynamically during the bolting process to absorb torque. This dynamic capability protects the fuse element while maintaining a relatively simple overall structure without complex mechanical constraints.
Data Source
AI summary
Electrical fuses include slip fit terminal elements coupled to the ends of a fuse element. The terminal elements may rotate relative to the fuse element ends as the fuses are bolted to circuit conductors and protect the fuse element from being damaged.