Floating Antifriction Disc Rim Wall for Circuit Breaker Drive Pin Protection
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Solution Overview
Problem
Molded case circuit breakers face issues with contaminants from arc interruption degrading dielectric strength between phases or poles due to conductive material infiltration at the drive pin and blade carrier interfaces, potentially causing cross-phase short circuits.
Innovation Solution
A new disc design with a partial rim wall that covers the blade carrier and acts as a deflector for contaminants during circuit interruption, maintaining contact with the cylindrical wall to protect the drive pins from gas and contaminant blasts, thereby reducing contaminant settling and dielectric strength reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional antifriction discs are used without rim walls, then the blade carrier can rotate freely with low friction, but contaminants from arc interruption can directly infiltrate the drive pin-to-blade carrier interface regions, reducing dielectric strength and potentially causing cross-phase short circuits
Solution Approach 1:
The patent applies a rim wall structure (a type of protective shell/film) that extends along the cylindrical wall of the blade carrier to cover the drive pin-to-blade carrier interface regions. This rim wall acts as a physical barrier that deflects arc gases and contaminants away from the interface, preventing contaminant infiltration while allowing the blade carrier to rotate freely. The rim wall is integrated into the antifriction disc structure, combining protective function with low-friction rotation.
2Reliability
If a continuous rim wall is used to fully protect the blade carrier, then drive pins are well protected from contaminants, but the device complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The patent applies local quality by providing rim walls only at specific locations where drive pins protrude through the blade carrier, rather than using a continuous rim wall around the entire blade carrier. The rim wall extends along the cylindrical wall at the sector containing the drive pin or pins, providing targeted protection exactly where contaminants would infiltrate the interface regions, while leaving other areas simpler in structure.
Solution Approach 2:
The rim wall structure is segmented to cover only the necessary interface regions where drive pins pass through the blade carrier. Rather than a complete continuous barrier, the rim wall is positioned at specific angular sectors corresponding to drive pin locations, dividing the protection function into discrete segments that match the actual contamination risk zones.
3Reliability
If the disc is designed to tightly fit as a cap to the blade carrier, then protection is improved, but the friction increases and the blade carrier rotation becomes less smooth
Solution Approach 1:
The rim wall is designed as a thin protective structure that extends along the cylindrical wall of the blade carrier but maintains a gap between the disc body and the blade carrier end surfaces. This allows the blade carrier to rotate freely with minimal friction while the rim wall provides protective coverage of the drive pin interface regions. The rim wall acts as a deflective barrier rather than a tight-fitting cap.
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 effectively protects the drive pins from contaminants, reducing the risk of cross-phase short circuits and maintaining dielectric strength between phases or poles, enhancing the reliability of molded case circuit breakers.
Implementation Method 1
the rim wall that at least partially covers the blade carrier and acts as a deflector of the contaminates driven by interruption gases around the drive pin-to-blade carrier interface regions
Implementation Method 2
bushings in the form of discs with low coefficient of friction placed between the blade carrier and the module sides
Data Source
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AI summary
An interrupter module for a molded case circuit breaker has a floating antifriction disc (23) between the module casings (12) and the blade carrier (15) which overlays the blade carrier with rim walls of the disc. The rim walls are located at segments of the disc containing the drive pins (13) of the module. If gases from circuit interruption expand the interrupter module sides and force the disc away from the blade carrier, the rim walls remain over the blade carrier and protect the drive pins from contaminants carried by the gases.