Printed Power Fuse Layout to Prevent Cyclic Fatigue Failure
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Solution Overview
Problem
Existing high voltage power fuses for electric vehicles are large, heavy, and prone to premature failure due to thermal-mechanical fatigue from cyclic current loads, which is exacerbated by the manufacturing process of stamped weak spots leading to mechanical strain and nuisance operations.
Innovation Solution
The development of a power fuse with fusible weak spots formed directly on a planar substrate without mechanical micro tears, connected by a solid elongated conductor with coplanar and oblique sections, and an arc extinguishing filler to manage arcing, avoiding thermal-mechanical fatigue and enabling effective arc extinguishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If stamped weak spot openings are used in the conductor, then the fuse can be manufactured with traditional stamping processes, but thermal-mechanical fatigue strain occurs leading to premature failure
Solution Approach 1:
The conductor is divided into multiple sections with varying cross-sectional areas. The first section has a larger cross-sectional area while the second section has a smaller cross-sectional area, creating intentional weak spots without mechanical stamping. This segmentation allows the fuse to have predetermined failure points that are free from stamping-induced micro tears and thermal-mechanical fatigue strain.
Solution Approach 2:
The cross-sectional area parameter of the conductor is varied along its length to create different sections with different electrical and thermal properties. The first section has a larger cross-sectional area for lower resistance, while the second section has a smaller cross-sectional area for higher resistance and intended fusibility. This parameter change eliminates the need for stamped weak spots while maintaining manufacturing feasibility.
2Reliability
If the fuse design includes oblique sections extending above the substrate, then arc extinguishing is improved, but the device complexity increases
Solution Approach 1:
The conductor transitions from a purely planar configuration to a three-dimensional structure by adding oblique sections that extend above the substrate plane. These oblique sections provide an additional spatial dimension for arc management, allowing the arc to be directed and extinguished more effectively while the coplanar sections maintain the electrical connection. This dimensional change improves arc extinguishing performance without significantly increasing overall device complexity.
3Reliability
If the conductor has varying cross-sectional areas, then the weak spots are formed without stamped openings, but the manufacturing precision requirements increase
Solution Approach 1:
The cross-sectional area of the conductor is varied along its length to create sections with different properties. The first section has a larger cross-sectional area while the second section has a smaller cross-sectional area. This parameter change allows weak spots to be formed through controlled material deposition or extrusion processes rather than mechanical stamping, eliminating stamping-induced fatigue while managing manufacturing precision through process control.
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
The solution provides smaller, lighter, and cost-effective high voltage power fuses with improved fatigue resistance and reduced nuisance operations, capable of handling high current and voltage fluctuations while maintaining circuit protection performance.
Implementation Method 1
when electrical current flowing through the fuse exceeds a predetermined limit, the fusible elements melt and open one or more circuits
Implementation Method 2
an arc extinguishing filler to manage arcing
Data Source
AI summary
A power fuse for protecting an electrical load subject to transient load current cycling events in a direct current electrical power system is provided. The power fuse includes at least one fuse element assembly that includes an elongated planar substrate, a plurality of fusible weak spots, and a conductor. The weak spots are formed on the substrate and are longitudinally spaced from one another on the substrate. The conductor is separately provided from the substrate and the weak spots. The conductor includes a solid elongated strip of metal having no stamped weak spot openings therein and therefore avoiding thermal-mechanical fatigue strain in the conductor when subjected to the transient load current cycling events. The solid elongated strip of metal includes coplanar connector sections that are mounted to respective ones of the weak spots and obliquely extending sections bent out of plane of the connector sections to extend above the substrate.