Relay Debris Suction Unit for Contact Resistance Control
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Solution Overview
Problem
In relays equipped with magnets for arc extinguishing, wear debris generated due to friction between the movable contact piece and the contact piece holding unit can be attracted to the magnet, leading to increased contact resistance and deteriorated energization performance.
Innovation Solution
A relay design incorporating a debris suction unit with a stronger magnetic force than the magnet for arc extinguishing, positioned to attract and remove wear debris away from the contact points, thereby preventing it from being caught between the movable and fixed contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a magnet is arranged laterally to the movable contact piece for arc extinguishing, then the arc can be quickly extinguished, but wear debris is attracted to the magnet and may be caught between the contacts, increasing contact resistance and deteriorating energization performance
Solution Approach 1:
The harmful function of the magnet (attracting wear debris to contacts) is extracted and separated from its original position. A debris suction unit is introduced to selectively attract wear debris away from the contact area, while the arc extinguishing magnet retains its arc-extinguishing function. This separation resolves the contradiction by removing the harmful effect while preserving the beneficial arc extinguishing capability.
Solution Approach 2:
The debris suction unit acts as an intermediary element between the wear debris and the arc extinguishing magnet. It intercepts the wear debris that would otherwise be attracted to the magnet and transported to the contact area, redirecting it to a safe location. This intermediary component resolves the contradiction by mediating the magnetic field's interaction with wear debris.
2Force
If the magnet exerts strong magnetic force for effective arc extinguishing, then arc extinction is improved, but wear debris is more strongly attracted toward the contact area, increasing contact resistance
Solution Approach 1:
The harmful effect of the magnet's strong magnetic force (attracting wear debris to contacts) is converted into a beneficial effect by introducing the debris suction unit. The same strong magnetic force that causes wear debris to move is harnessed to transport debris away from the contact area toward the debris suction unit, transforming a harmful phenomenon into a useful debris removal mechanism.
Solution Approach 2:
The debris suction unit serves as an intermediary that captures wear debris attracted by the magnet's strong magnetic force. It intercepts debris before it reaches the contacts and redirects it to a collection area, resolving the contradiction between needing strong magnetic force for arc extinguishing and preventing wear debris from increasing contact resistance.
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 extinguishes arcs and reduces the risk of wear debris causing contact resistance issues, maintaining optimal energization performance by ensuring wear debris is not trapped between contacts.
Implementation Method 1
When an arc is generated between the contact points, a Lorentz force acts on the arc due to the magnetic force of the magnets. Thereby, the arc is extinguished quickly as a result of the arc being stretched.
Implementation Method 2
The debris suction unit exerts a magnetic force so as to suck debris generated in the contact piece holding unit.
Data Source
AI summary
A relay, including a first fixed contact, a second fixed contact, a movable contact piece having first and second movable contacts, a contact piece holding unit configured to hold the movable contact piece, a magnet for arc extinguishing, and a debris suction unit configured to exert a magnetic force to suck debris, is disclosed. A first contact position between the first fixed contact and the first movable contact is located between the magnet for arc extinguishing and the contact piece holding unit in a longitudinal direction of the movable contact piece. The debris suction unit is disposed so that the first contact position does not overlap a region between the debris suction unit and the contact piece holding unit. A magnet force exerted by the debris suction unit in the contact piece holding unit is larger than a magnetic force exerted by the magnet in the contact piece holding unit.