Micro Switch With Permanent Magnet For Arc Extinction
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Solution Overview
Problem
Conventional micro switches have a short open distance between contacts, limiting their ability to effectively cut off direct current above 250V and 1.0A, and lack a mechanism to quickly extinguish arcs, making them unsuitable for controlling motors in electric power equipment.
Innovation Solution
A micro switch design featuring a permanent magnet positioned between the movable and stationary contacts, with a support member shaped like the letter 'E' or the number '3' to prevent magnet separation, increasing the open distance and using magnetic flux to rapidly extinguish arcs, thereby enhancing direct current cut-off capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the open distance between movable contact and stationary contact is increased, then the capability to cut off direct current is improved, but the device complexity increases
Solution Approach 1:
A permanent magnet is introduced as an intermediary component between the movable contact and stationary contact. The magnet serves dual purposes: it extends the effective open distance for current interruption and generates magnetic flux to extinguish arcs, thereby improving direct current cut-off capability without proportionally increasing device complexity
Solution Approach 2:
The permanent magnet performs multiple functions simultaneously: it acts as a spacer to increase open distance, generates magnetic flux for arc extinction, and provides mechanical support through the support member. This multi-functionality improves performance while minimizing the addition of separate components
2Reliability
If a permanent magnet is added to extinguish arcs, then the reliability of cutting off great direct current is improved, but the manufacturing complexity increases
Solution Approach 1:
The permanent magnet and its support structure are designed as an integrated assembly. The support member with positioning protrusions and grooves combines magnetic support, positioning, and retention functions into a single manufacturable component, reducing assembly steps and manufacturing complexity
Solution Approach 2:
The permanent magnet automatically generates the required magnetic flux for arc extinguishing without external control or additional power sources. The support member's positioning protrusions and grooves provide self-aligning features that facilitate easy installation and reduce precision requirements during manufacturing
3Reliability
If the open distance is increased from 1 millimeter, then the capability to handle direct current above 250V and 1.0A is improved, but the device dimensions increase
Solution Approach 1:
The permanent magnet's dimensions and magnetic strength are optimized to provide sufficient magnetic flux for arc extinction while maintaining a compact size. The support member is designed with minimal material usage while providing adequate structural support, thereby increasing open distance without proportionally increasing overall device volume
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 micro switch can cut off direct currents exceeding 250V and 1.0A, with a capability three times greater than conventional switches, and effectively prevent arc damage to motors and trip springs, ensuring operational reliability in electric power equipment.
Implementation Method 1
A micro switch design featuring a permanent magnet positioned between the movable and stationary contacts, with a support member shaped like the letter 'E' or the number '3' to prevent magnet separation, increasing the open distance and using magnetic flux to rapidly extinguish arcs
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Disclosed is a micro switch 20, 30 and 40 having a high capability of cutting off a direct current. In the micro switch including a stationary contact NCa or NOa, a movable contact 4a having a closed position where it contacts the stationary contact or an open position where it is separated from the stationary contact, a movable contact rod 4 for supporting the movable contact, a plunger 5 for pressurizing the movable contact rod upon being pressed, and a leaf spring 7 for supplying a driving force to the movable contact rod to convert a position of the contacts being contacted or separated, a permanent magnet 10 is installed at a position adjacent to the movable contact and the stationary contact, so as to extend an arc generated between the movable contact and the stationary contact upon separating the movable contact from the stationary contact, whereby the arc can be fast extinguished.