Ceramic Fuse With Brazed Electrodes for High Voltage Durability
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Solution Overview
Problem
Conventional fuses have poor durability and insufficient time-lag characteristics due to the use of glass tubes and soldering, limiting their effectiveness at high voltages and restricting the length and number of turns of the fusible element.
Innovation Solution
A fuse design utilizing a ceramic tube with brazing rings to join sealing electrodes, where a fusible element is wound on the outer surface of a ceramic nonconductive member, and a plating layer is applied to enhance wetting properties and joining strength, allowing for improved durability and time-lag characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glass tube is used and soldering is performed for joining, then the manufacturing process is simple, but the durability and joining strength are poor
Solution Approach 1:
The patent changes the joining method from soldering to brazing, which involves changing the temperature parameter and the metallurgical process. Brazing operates at higher temperatures than soldering, enabling stronger joints between the ceramic tube and sealing electrodes, thereby improving durability while maintaining manufacturing feasibility through established brazing processes
Solution Approach 2:
The patent employs a composite structure combining ceramic tube with brazing rings and sealing electrodes. The ceramic tube provides electrical insulation and mechanical support, while the brazing rings (composed of copper, silver, and zinc alloys) provide strong metallurgical bonding to the electrodes, creating a composite system that achieves both high durability and reliable electrical connections
2Length of moving object
If the internal lead is inserted into the glass tube, then the assembly is simple, but the length of the fusible element is limited
Solution Approach 1:
The patent transitions from a linear internal lead configuration to a wound fusible element configuration that utilizes the outer circumferential surface of the ceramic tube. This dimensional change allows the fusible element to be arranged in multiple turns around the tube, significantly increasing its effective length and improving time-lag characteristics without complicating the overall structural assembly
3Reliability
If a short fusible element is used, then the device is compact, but sufficient time-lag for high voltage operation cannot be achieved
Solution Approach 1:
The patent utilizes the outer circumferential surface of the ceramic tube to wind the fusible element in multiple turns, effectively increasing its length in a compact space. This dimensional arrangement allows sufficient time-lag characteristics for high voltage operation while maintaining a compact overall device size, as the extended length is achieved through circumferential winding rather than linear extension
4Strength
If brazing rings are used to join ceramic tube and electrodes, then joining strength is improved, but wetting properties may be insufficient
Solution Approach 1:
The patent optimizes the compositional parameters of the brazing rings by specifying a copper-silver-zinc alloy system. This compositional change enhances wetting properties between the brazing material and both the ceramic tube and sealing electrodes, ensuring proper metallurgical bonding and joint formation during the brazing process while maintaining high joining strength
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 ceramic tube and brazing ring design enhances the durability and stability of the fuse at high voltages, improving time-lag characteristics and joining strength, enabling reliable operation at voltages of 250 V or higher.
Implementation Method 1
brazing rings sealing between the ceramic tube and each of the sealing electrodes. In this regard, the ceramic tube is joined to the sealing electrodes by melting of the brazing rings.
Implementation Method 2
a plating layer is applied to enhance wetting properties and joining strength
Data Source
AI summary
A fuse and a manufacturing method thereof are disclosed. Since a nonconductive member formed of a ceramic material with excellent mechanical strength and a ceramic tube are used and the ceramic tube is joined to sealing electrodes by use of brazing rings, durability of the fuse is considerably improved. The fuse may be stably used at a high voltage by improving time-lag characteristics.