Multilayered PTC Polymer Over-Current Protection Device
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Solution Overview
Problem
Conventional over-current protection devices using PTC polymer materials have limited operating temperature and voltage ranges, necessitating improvements to enhance their performance.
Innovation Solution
The device incorporates a multilayered structure with two PTC polymer material layers, one containing polyvinylidene fluoride and polyolefin, and the other containing polyolefin or polyvinylidene fluoride, with specific weight ratios and particulate conductive fillers, to achieve higher trip surface temperatures and breakdown voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the polymer matrix is made from polyolefin to achieve ease of manufacture, then the operating temperature can only reach a value within a range of from about -40°C to about 85°C
Solution Approach 1:
The patent uses a composite polymer matrix made from polyvinylidene fluoride (PVDF) and polyolefin in specific weight ratios (PVDF: 10-60 wt%, polyolefin: 40-90 wt%). This composite structure combines the high temperature resistance of PVDF with the ease of manufacture and flexibility of polyolefin, achieving both high operating temperature (up to 125°C) and manufacturability
Solution Approach 2:
The patent changes the compositional parameters of the polymer matrix by introducing PVDF content control (10-60 wt%) and adjusting the polyolefin/PVDF weight ratio. This parameter optimization allows the material to achieve higher melting points and operating temperatures while maintaining processability and ease of manufacture
2Temperature
If the polymer matrix is made from polyvinylidene fluoride to achieve higher operating temperature, then the operating voltage or breakdown voltage can only reach 30 Vdc
Solution Approach 1:
The patent creates a composite polymer matrix combining PVDF and polyolefin, where the polyolefin component enhances the breakdown voltage and electrical insulation properties while PVDF provides high temperature resistance. This synergistic composite structure achieves both high operating temperature (up to 125°C) and high breakdown voltage (30-100 Vdc)
Solution Approach 2:
The patent optimizes the local composition by controlling the distribution and ratio of PVDF (10-60 wt%) and polyolefin (40-90 wt%) phases within the matrix. This local quality control ensures that regions with higher polyolefin content provide electrical insulation and high breakdown voltage, while PVDF-rich regions provide thermal stability
3Temperature
If a single PTC polymer material layer is used to simplify the device structure, then both operating temperature and operating voltage cannot be improved simultaneously
Solution Approach 1:
The patent divides the PTC polymer material into multiple layers (first PTC polymer material layer and second PTC polymer material layer), each with potentially different polymer compositions optimized for specific functions. This segmentation allows one layer to optimize for temperature response while another layer optimizes for voltage resistance, achieving both high trip surface temperature (110-150°C) and high breakdown voltage (30-100 Vdc)
Solution Approach 2:
The multilayered structure serves multiple functions simultaneously: different layers can be optimized for different trip temperatures, voltage resistance, response times, or mechanical properties. This multi-functionality allows the device to achieve high operating temperature (110-150°C), high operating voltage (30-100 Vdc), and tailored performance characteristics without requiring separate devices
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 enables the over-current protection device to operate within a broader temperature range of 110 to 150°C and withstand breakdown voltages from 30 to 100 Vdc, significantly improving upon existing technologies.
Implementation Method 1
A positive temperature coefficient (PTC) material exhibits a positive temperature coefficient effect that renders the same to be useful as a protecting device, such as a fuse
Implementation Method 2
a conductive particulate filler (not shown) that is dispersed in the non-crystalline region of the polymer matrix and that is formed into a continuous conductive path for electrical conduction between the first and second electrodes 82, 83
Implementation Method 3
when the temperature of the polymer matrix is raised to its melting point, crystals in the crystalline region start melting, which results in generation of a new non-crystalline region
Data Source
AI summary
An over-current protection device includes first and second electrodes and a multilayered structure including first and second PTC polymer material layers that are stacked one above the other and that are bonded to each other. The first PTC polymer material layer includes a first polymer matrix and a particulate conductive filler. The second PTC polymer material layer includes a second polymer matrix and a particulate conductive filler. The second polymer matrix is made from a second polymer composition that contains. One of the first and second polymer compositions contains polyvinylidene fluoride and polyolefin and the other of the first and second polymer compositions contains polyolefin or polyvinylidene fluoride.