Conductive Spring Fuse for Varistor Fire Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electric devices, such as metal oxide varistors, can catch fire under abnormal overvoltage conditions, and existing thermal fuse varistors with complex structures are not adequately effective in preventing such fires.
Innovation Solution
An electric device with a conductive spring connected to a terminal via a fusible joint, where the spring is deflected and fixed to a housing, allowing it to disconnect from the terminal when the joint melts, creating an open-circuit failure mode that prevents current flow and potential fires, featuring a compact and reliable design suitable for both AC and DC applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal fuse structure is added to protect against overvoltage conditions, then fire prevention capability is improved, but device structure becomes more complicated
Solution Approach 1:
The patent combines the fuse function and spring function into a single integrated component. The spring serves dual purposes: as an electrical conductor connecting the terminals to the varistor, and as a mechanical element that provides thermal protection through elastic deformation and separation when heated by overvoltage conditions. This merging eliminates the need for separate fuse and spring components, thereby preventing fire while maintaining structural simplicity.
Solution Approach 2:
The spring is designed to perform multiple functions simultaneously: electrical conduction, mechanical connection, thermal response, and safety separation. By making the spring multi-functional, the patent achieves fire prevention capability without adding extra components that would complicate the device structure.
2Reliability
If a conductive spring with fusible joint is used to enable automatic disconnection, then safety under overvoltage conditions is improved, but manufacturing complexity increases
Solution Approach 1:
The fusible joint integrates the electrical connection function and the thermal protection function into a single solder joint. This joint connects the spring to the varistor terminal and serves as the thermal weak point that melts under overvoltage heating, causing automatic disconnection. By merging these functions, the patent improves safety without requiring separate fuse mechanisms that would complicate manufacturing.
3Reliability
If the spring is fixed to the housing with deflection capability, then automatic disconnection function is improved, but device structure becomes more complex
Solution Approach 1:
The spring's mechanical connection to the housing serves dual purposes: providing structural support and enabling the thermal protection function. The spring is anchored to the housing in a way that allows it to deform elastically and separate from the terminal when heated, automatically disconnecting the circuit. This integrated approach achieves automatic disconnection without adding complex mechanical mechanisms.
4Volume of moving object
If the terminal is bent to run adjacent to the body, then space utilization is improved, but assembly precision requirements increase
Solution Approach 1:
The spring is designed with elastic deformation capability, allowing it to dynamically adjust its position and accommodate variations in assembly precision. The bent terminal configuration combined with the spring's flexibility enables the device to achieve compact space utilization while tolerating reasonable manufacturing variations through the spring's ability to deform and self-adjust during assembly and operation.
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 device effectively interrupts current flow during abnormal overvoltage conditions, preventing the electric device from catching fire and ensuring high reliability with a simple structure and easy assembly, while the spring's movement extinguishes sparks and the low-melting-point solder ensures safe operation.
Implementation Method 1
a fusible joint, where the spring and the terminal are electrically disconnected if the joint fuses
Implementation Method 2
temperature rise caused by abnormal voltage conditions
Implementation Method 3
The spring is fixed to the housing so that the spring is deflected. A part of the spring that is connected to the terminal will move away from the terminal when the joint fuses
Implementation Method 4
The movement of the spring causes a gap between the terminal and the spring, the gap extinguishing sparks
Data Source
Figure 1
Figure 2~3
Figure 4A~4C
AI summary
An electric device (15) comprising: an electric element (1) comprising a body (13) and a terminal (5), and a conductive spring (17) being deflected, the spring (17) being electrically connected to the terminal (5) by a fusible joint (19), where the spring (17) and the terminal (5) are electrically disconnected if the joint (19) fuses.