Liquid Crystal Polymer Circuit Interrupter Case
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Solution Overview
Problem
Current circuit interrupters, particularly in aerospace applications, face challenges with moisture resistance, mechanical robustness, and efficient packaging due to the use of thermoset compounds and conventional over-molding techniques, which can lead to premature failures and increased component count.
Innovation Solution
A circuit interrupter design featuring a molded case made of liquid crystal polymer (LCP) with a rigid, conductive base insert molded into the case, incorporating printed circuit boards within a cavity and encapsulated by low-pressure molding material, providing mechanical interlocking and enhanced moisture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermoset compounds are used for the molded circuit breaker case, then moisture resistance is improved, but manufacturing complexity and component count increase due to separate molding processes
Solution Approach 1:
The patent combines the molded case and base into a single integrated component made from LCP material, eliminating the need for separate thermoset compound molding and reducing assembly steps while maintaining moisture resistance properties
Solution Approach 2:
The LCP molded case serves multiple functions simultaneously: it provides structural housing, moisture resistance, electrical insulation, and mechanical support for the base and PCB, replacing multiple separate components that would be needed with traditional thermoset materials
2Reliability
If conventional over-molding techniques are used, then packaging is improved, but mechanical robustness decreases and production efficiency is reduced
Solution Approach 1:
The base is pre-positioned and mechanically interlocked with the molded case through insert molding, ensuring proper alignment and structural integrity before final assembly, which eliminates the need for complex post-assembly adjustments and rework
Solution Approach 2:
The patent replaces conventional mechanical assembly methods (screws, clips, separate fastening operations) with insert molding technology that creates permanent mechanical interlocking between the base and case during a single molding cycle, improving both robustness and production efficiency
3Ease of manufacture
If the molded case absorbs moisture from the molding process, then production is simplified, but reliability deteriorates due to arcing and dielectric breakdown
Solution Approach 1:
The patent changes the material parameter from traditional thermoset compounds to liquid crystal polymer (LCP), which has inherently lower moisture absorption characteristics, thereby maintaining production simplicity while significantly improving arc resistance and dielectric breakdown performance
Solution Approach 2:
The use of LCP material provides a composite structure with superior moisture barrier properties and dielectric strength, combining the benefits of ease of manufacture with enhanced reliability against arcing and moisture-related failures
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
This design enhances moisture resistance, mechanical strength, and reduces component count while automating production, offering superior packaging and reliability compared to traditional methods.
Implementation Method 1
a molded case made of liquid crystal polymer
Implementation Method 2
Mechanical bonding can take place in two ways, by the shrinking of the encapsulating resin around the insert as the resin cools
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A circuit interrupter includes a housing having a molded case made of liquid crystal polymer. Separable contacts are disposed within the housing. An operating mechanism is disposed within the housing and is structured to open and close the separable contacts. A trip mechanism is disposed within the housing and is structured to cooperate with the operating mechanism to trip open the separable contacts. The trip mechanism includes an electronic trip circuit and a rigid, conductive base providing a ground to the electronic trip circuit. The rigid, conductive base is insert molded to a portion of the molded case.