Movable Contactor Assembly for Current Limiting Circuit Breakers
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Solution Overview
Problem
Current movable contactor assemblies for current limiting circuit breakers have complex structures with many components, leading to reduced assembly productivity and increased fabricating costs, along with issues such as torsion and separation errors due to air gaps among components.
Innovation Solution
A movable contactor assembly with a pair of curved protrusions on the movable contactor, a shaft with spring receiving recesses, and contact levers that apply elastic forces to maintain contact and separate the movable contactor from the stationary contactor using a simplified configuration with reduced number of springs and spring supporting pins, preventing rotation center movement and interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex structure with many components (rollers, cam plates, links, multiple springs) is used in the movable contactor assembly, then smooth operation and contact maintenance are achieved, but assembly productivity decreases and fabricating costs increase
Solution Approach 1:
The patent merges multiple separate components (rollers, cam plates, links, and multiple springs) into a single integrated movable contactor body. The contactor body directly incorporates the cam profile surfaces and spring mounting features, eliminating the need for separate roller and cam plate assemblies. This consolidation maintains smooth operation through the integrated cam profiles while dramatically improving assembly productivity by reducing the number of parts to be assembled.
Solution Approach 2:
The movable contactor body serves multiple functions simultaneously: it provides the moving contact element, incorporates the cam profile for guiding motion, integrates spring mounting features for contact pressure maintenance, and eliminates the need for separate roller and link mechanisms. This multi-functionality reduces the overall component count while maintaining all necessary operational characteristics.
2Reliability
If a complex structure with many components is used in the movable contactor assembly, then contact maintenance is achieved, but fabricating costs increase
Solution Approach 1:
The patent combines multiple manufacturing operations into a single contactor body production process. Instead of separately manufacturing rollers, cam plates, links, and multiple springs, the invention integrates all these functions into one molded or machined contactor body with embedded spring features. This reduces fabricating costs by eliminating multiple discrete manufacturing processes, tooling requirements, and quality inspection steps while maintaining reliable contact maintenance through the integrated design.
3Adaptability or versatility
If many components are assembled in the movable contactor assembly, then functional requirements are met, but assembly errors (torsion, separation) occur due to accumulation of air gaps
Solution Approach 1:
The patent eliminates assembly errors by merging multiple separate components into a single integrated contactor body. The integrated design removes all air gaps and potential misalignment issues that would accumulate from assembling multiple separate parts. The cam profiles and spring mounting features are precisely formed as part of the single contactor manufacturing process, ensuring consistent geometric relationships without the tolerance stack-up inherent in multi-component assemblies.
Solution Approach 2:
The invention extracts and eliminates the problematic intermediate components (rollers, cam plates, links) that caused assembly precision issues. By removing these separate elements and their associated mounting features, the patent eliminates the sources of torsion and separation errors while directly providing the necessary functional characteristics through the integrated contactor body design.
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 fast current limiting, maintains the separated state of the movable contactor until a trip operation, and improves assembly productivity and reduces fabricating costs by simplifying the structure and reducing the number of components.
Implementation Method 1
a pair of springs each having corresponding end portions supported by the spring supporting recess portions of both contact levers, received in the spring receiving recess portions of the shaft, and provided respectively at both plate surfaces of the movable contactor, the pair of springs applying elastic force as contact pressure for maintaining a contact state between the movable contactor and the current limiting type stationary contactor when the movable contactor is located at the first position, and applying the elastic force in a direction to separate the movable contactor from the current limiting type stationary contactor when the movable contactor is moved over a dead point while rotating toward the second position
Implementation Method 2
the movable contactor being rotatable to a first position contacting the current limiting type stationary contactor, and a second position separated from the current limiting type stationary contactor by an electromagnetic repulsive force upon occurrence of a large fault current on a circuit
Data Source
Figure 1~2
Figure 3~4
AI summary
A movable contactor assembly for a current limiting type circuit breaker comprises a movable contactor having a pair of curved protrusions having cam profiles, a shaft to rotatably support the movable contactor located therein, a pair of contact levers each having a contact surface contactable with the curved protrusion of the movable contactor and a pair of spring supporting recess portions and a pair of springs each having both end portions supported by the spring supporting recess portions, the pair of springs applying an elastic force as contact pressure for maintaining a contact state between the movable contactor and the stationary contactor when the movable contactor is located at the first position, and applying the elastic force in a direction to separate the movable contactor from the stationary contactor when the movable contactor is moved over a dead point while rotating toward the second position.