Dual-Ceramic Disc Varistor for High-Energy Surge Absorption
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Solution Overview
Problem
Conventional disc varistors with a single ceramic body are inadequate in absorbing high-energy surges, particularly during car motor starting, and struggle with electromagnetic compatibility (EMC) requirements due to miniaturization and integration of electronic circuits.
Innovation Solution
A disc varistor design featuring two ceramic bodies connected in parallel using lead wires, where the second lead wire is bent to create extensions that connect to both ceramic bodies, allowing for equal voltage distribution and enhanced surge absorption capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single ceramic body is used in a conventional disc varistor, then the device complexity is low and manufacturing is simple, but the surge absorption capability is insufficient for high-energy surges in automotive applications
Solution Approach 1:
The varistor is divided into multiple ceramic bodies (first ceramic body and second ceramic body) connected in parallel. Each ceramic body has its own electrodes and lead wire connections, creating modular segments that collectively provide enhanced surge absorption capability while maintaining manageable structural complexity through standardized connection patterns.
2Area of moving object
If the operating voltage is reduced for miniaturized electronic equipments, then the device size is reduced and integration is improved, but the energy carrying capacity decreases making the device more susceptible to surge damage
Solution Approach 1:
Multiple ceramic bodies are connected in parallel to combine their surge absorption capabilities. The parallel connection merges the current handling capacity of individual ceramic bodies while maintaining the low operating voltage requirement, thus achieving both miniaturization and enhanced surge resistance for modern low-voltage electronic systems.
3Reliability
If two ceramic bodies are connected in parallel to double the surge absorption capability, then the energy carrying capacity increases, but the manufacturing precision and assembly complexity increase due to multiple lead wire connections
Solution Approach 1:
The lead wires are configured to create equipotential connections between the ceramic bodies. The first lead wire connects the second electrode to the third electrode, and the second lead wire provides parallel connection paths, ensuring equal voltage distribution across all ceramic bodies. This equipotential configuration simplifies the manufacturing process by providing clear connection targets and reducing assembly variability.
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 dual-ceramic body configuration doubles the surge absorption capability and effectively addresses EMC issues in electronic devices, particularly in vehicles, by ensuring efficient suppression of load dumps during motor start-up.
Implementation Method 1
a first lead wire interposed between the second and third electrodes, and electrically connected to the second and third electrodes; and a second lead wire including a body portion electrically connected to the first electrode of the first ceramic body
Implementation Method 2
The nonlinear characteristic of the varistor has very large electric resistances at low voltages. The resistance has a grain boundary phenomenon showing the nonlinear characteristic. That is, when the voltage exceeds a predetermined threshold voltage depending on the microstructure and size of the device, the electric resistance is abruptly reduced.
Implementation Method 3
The nonlinear resistance characteristic is controlled by a process that occurs at the grain boundary. The nonlinear resistance characteristic is similar to a breakdown observed at a back-to-back Zener diode, but has larger energy absorbing capability.
Data Source
AI summary
Disclosed herein are a disc varistor having a capability to absorb a double amount of surge and a method of manufacturing the varistor. The varistor includes a disc-shaped first ceramic body having first and second electrodes on opposite surfaces thereof, and a disc-shaped second ceramic body having third and fourth electrodes on opposite surfaces thereof. A first lead wire is in interposed between the second and third electrodes and electrically connected to the second and third electrodes. The varistor also includes a second lead wire. The second lead wire has a body portion electrically connected to the first electrode of the first ceramic body, a first extension extending from the body portion to the second ceramic body, and a second extension extending from the first extension to the fourth electrode.