Electromagnetic Contactor Fixed Contact Deformation Prevention
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Solution Overview
Problem
The existing electromagnetic contactors with C-shaped fixed contacts face deformation issues due to repeated contact pressure, leading to potential contact failure, especially when the fixed contacts are brazed and subsequently heated, causing blunting.
Innovation Solution
The electromagnetic contactor design includes contact bearing portions in the housing case to absorb stress from the movable contact, arc extinguishing portions, and an insulating cover to prevent arc contact with metal, ensuring reliable contact and preventing deformation of the fixed contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the movable contact repeatedly contacts the fixed contacts at predetermined contact pressure, then the contact mechanism achieves reliable current path opening and closing, but the fixed contacts become deformed causing contact failure
Solution Approach 1:
The fixed contact is divided into two functional parts: the C-shaped contact portion that interfaces with the movable contact, and the support conductor portion that provides structural stability. This segmentation allows the contact portion to perform its function while the support portion maintains shape stability during repeated contact operations.
Solution Approach 2:
The support conductor portion acts as an intermediary between the C-shaped contact portion and the contact housing case. It transmits and distributes the contact pressure from the movable contact, preventing direct stress concentration on the C-shaped portion and thereby preventing deformation.
2Strength
If the fixed contacts are fixed by brazing in the contact housing case, then the fixed contacts are securely mounted, but the fixed contacts are blunted by heating during brazing
Solution Approach 1:
By separating the fixed contact into C-shaped contact portions and support conductor portions, the design allows the support portions to be positioned away from the brazing zone. This enables secure mounting through brazing while minimizing thermal exposure to the precision C-shaped contact geometry.
Solution Approach 2:
The support conductor portions serve as intermediaries that can be brazed to the housing case, providing secure mounting while being positioned to absorb or shield the C-shaped contact portions from excessive heat during the brazing process.
3Device complexity
If the C-shaped fixed contacts are used without additional support structures, then the device complexity is reduced, but the fixed contacts deform under repeated contact pressure
Solution Approach 1:
The support conductor portions are merged with the C-shaped contact portions to form integrated fixed contact assemblies. This combining provides the necessary structural support within the fixed contact itself, eliminating the need for separate external support structures and maintaining low device complexity.
Solution Approach 2:
The support conductor portions serve multiple functions: providing structural support, distributing contact pressure, and maintaining the geometric stability of the C-shaped contact portions. This multi-functionality achieves shape stability without adding separate dedicated support components.
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 configuration effectively prevents deformation of the fixed contacts and enhances arc extinguishing performance, maintaining reliable contact and preventing short-circuiting by distributing contact pressure and containing arcs within insulating spaces.
Implementation Method 1
contact bearing portions bearing a side of the lower plate portions of the pair of fixed contacts opposite to that contacting the movable contact
Implementation Method 2
a Lorentz force is generated opposing an electromagnetic repulsion force generated in the contact opening direction between the fixed contact and movable contact when energizing
Implementation Method 3
two sides of the projecting portion are formed with arc extinguishing portions lower than the contact bearing surface
Data Source
AI summary
An electromagnetic contactor includes a contact device including a pair of fixed contacts and a movable contact contacting to and separating from the pair of fixed contacts. The pair of fixed contacts includes support conductor portions supported with an upper surface of a contact housing case, and C-shaped portions each including an upper plate portion linked to an end portion of the support conductor portion, an intermediate plate portion extending downward from a side of the upper plate portion opposite to that of the other support conductor portion, and a lower plate portion extending from a lower end of the intermediate plate portion toward a side of the other support conductor portion and formed with a contact portion on an upper surface thereof. The contact housing case includes contact bearing portions bearing a side of the lower plate portions of the pair of fixed contacts opposite to the movable contact.