Electromagnetic Relay Arc Heat Management
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Solution Overview
Problem
Conventional electromagnetic relays suffer from damage due to heat generated by arcs between movable and fixed contacts, which can lead to a deterioration in contact performance and potential failure.
Innovation Solution
The design incorporates a nonmagnetic card that absorbs the heat of the arc, using a permanent magnet and yokes to direct the magnetic flux effectively, and a copper alloy movable spring with a copper bus bar terminal configuration to manage heat and improve arc extinguishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a card is used to contact the back of movable springs in conventional electromagnetic relays, then the structure is simple and easy to manufacture, but the card may damage due to heat from arcs generated between contacts
Solution Approach 1:
A nonmagnetic body is introduced as an intermediary component between the movable spring and the card. This nonmagnetic body absorbs arc heat and protects the card from thermal damage, while allowing the simple card-based structure to be maintained. The nonmagnetic body acts as a heat shield that mediates the thermal interaction between the arc and the card.
Solution Approach 2:
The harmful arc heat that previously damaged the card is now utilized beneficially by the nonmagnetic body, which absorbs the heat and redirects it away from critical components. The nonmagnetic body converts the harmful thermal energy into a protective mechanism that extends the life of the card and improves reliability.
2Force
If the card contacts movable springs directly, then the pressing force can be maintained, but the heat from arcs causes the card to dissolve and worsens contact state
Solution Approach 1:
The nonmagnetic body serves as a thermal intermediary that absorbs arc heat before it reaches the card and movable springs. This allows the card to maintain its mechanical properties and pressing force without undergoing thermal degradation, effectively decoupling the force transmission function from the heat exposure.
3Reliability
If permanent magnets are used to generate magnetic field for arc extinction, then arc-extinguishing performance is improved, but magnetic flux distribution may be uneven without proper yoke configuration
Solution Approach 1:
Yokes with different magnetic permeabilities are used to create localized magnetic flux paths. The first yoke and second yoke have different permeability characteristics that are optimized for their respective positions, ensuring uniform magnetic flux distribution across the contact region. This local optimization of magnetic properties achieves stable and effective arc extinction.
Solution Approach 2:
The magnetic circuit uses a composite structure combining permanent magnets with yokes of different materials and permeabilities. This composite magnetic system allows for fine-tuned control of flux distribution, combining the high field strength of permanent magnets with the flux-directing capabilities of differently-permeable yoke materials.
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 damage from arc heat and enhances arc extinguishing performance, ensuring reliable operation of the electromagnetic relay.
Implementation Method 1
a permanent magnet generates a magnetic field between contacts, and an arc that occurs between the contacts is extended by a Lorenz force and is extinguished
Implementation Method 2
a nonmagnetic body is arranged in a direction where an arc is extended by a permanent magnet
Implementation Method 3
an electromagnetic relay includes an electromagnet that generates a magnetic field when electric current is supplied thereto
Data Source
Figure 1
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Figure 3
AI summary
An electromagnetic relay including: an electromagnet (30); a movable spring (64) having a movable contact (69a, 69b); a first terminal (60) to which one end of the movable spring (64) is connected; a second terminal (70) having a fixed contact (73 a, 73b) opposite to the movable contact (69a, 69b); an actuator (80) that rotates by excitation of the electromagnet (30), rotates the movable spring (64), and causes the movable contact (69a, 69b) to come in contact with the fixed contact (73a, 73b) or to separate from the fixed contact (73a, 73b); a nonmagnetic card (100) to be attached to the actuator (80); a plurality of magnetic members (203, 204) that sandwich the movable contact (69a, 69b) and the fixed contact (73a, 73b), and apply a magnetic flux to the movable contact (69a, 69b) and the fixed contact (73a, 73b) to extend an arc; and a permanent magnet (205) attached between the magnetic members (203, 204).