Crossing-Type Switch Contact Plating for Fusion Resistance
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Solution Overview
Problem
Crossing-type electrical switches face reliability issues due to material transition and fusion problems during arc contact, particularly with silver contacts, which are prone to abnormal contact and locking, and existing solutions like silver-oxide alloys are difficult to process in rivet form for these switches.
Innovation Solution
The use of different plating materials on each contact of a crossing-type switch, such as AgCu, AgNi, AgPd alloys for the first and second contacts, and a composite silver oxide for the third contact, attached to a phosphorous-bronze plate, optimized for specific characteristics like conductivity, hardness, and arc resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If silver plating is used on contacts to reduce fusion, then anti-fusion property is improved, but reliability deteriorates due to low anti-fusion property and abnormal contact
Solution Approach 1:
The patent applies different plating materials to different contacts based on their specific functional requirements. The first contact (negative electrode side) uses AgCu or AgNi alloy for high conductivity and abrasion resistance, the second contact (center bridge) uses AgPd alloy for excellent arc resistivity and anti-fusion properties, and the third contact (positive electrode side) uses AgSnInOx composite material for superior anti-fusion performance. This localized material optimization resolves the contradiction by matching each contact's material properties to its specific operational demands.
Solution Approach 2:
The patent employs composite plating materials, particularly AgSnInOx for the third contact and AgPd alloys for the second contact, which combine multiple elements to achieve synergistic effects. These composite materials provide both high anti-fusion properties and reliable electrical conductivity, eliminating the trade-off between fusion resistance and contact reliability that plagues pure silver plating.
2Object-affected harmful factors
If silver-oxide alloy is used to improve arc resistivity, then arc resistivity is improved, but ease of manufacture deteriorates due to difficulty in processing rivet form
Solution Approach 1:
The patent divides the switch into multiple contact segments (first, second, and third contacts), each with specialized plating materials. This segmentation allows the use of complex composite materials like AgSnInOx and AgPd alloys in specific locations where arc resistivity is critical, while maintaining manufacturing feasibility through selective application rather than requiring entire components to be made from difficult-to-process materials.
Solution Approach 2:
High-performance composite plating materials are applied only to specific contacts where arc resistivity is most needed (second and third contacts), rather than uniformly across all contacts. This localized application maintains manufacturing ease while achieving superior arc resistivity where required.
3Reliability
If different characteristics are required for each contact, then contact performance is improved, but device complexity increases making reliability assurance difficult
Solution Approach 1:
The patent implements local quality by assigning specific plating materials to specific contacts: AgCu or AgNi for the first contact, AgPd for the second contact, and AgSnInOx for the third contact. Each material selection addresses the specific functional requirements of that contact position, optimizing overall reliability while maintaining a systematic approach to material selection that prevents complexity from becoming unmanageable.
Solution Approach 2:
The patent systematically varies material parameters (composition, conductivity, hardness, arc resistivity) across different contacts to match functional requirements. This parameter optimization is achieved through a structured methodology that balances performance needs with manufacturing capabilities, preventing device complexity from escalating while ensuring each contact operates at optimal performance levels.
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 approach enhances the lifespan and reliability of the switch by reducing fusion occurrences and maintaining optimal contact characteristics, as demonstrated by increased durability tests and reduced fusion generations compared to comparative examples.
Implementation Method 1
a contact material having excellent arc resistivity, such as a silver-oxide alloy
Implementation Method 2
the center portion of the moving contact and an upper end of the wall in the seesaw structure continuously produce friction, and accordingly become weak to abrasion
Implementation Method 3
The fixed contact and the moving contact come into contact with each other by a physical force to open, close, or convert a circuit
Data Source
AI summary
An electrical contact material may include a first contact that contacts a negative electrode; a third contact that contacts a positive electrode; and a second contact that is provided between the first contact and the third contact, wherein different plating materials are respectively attached to the first contact, the second contact, and the third contact.