Electromagnetic Relay Tapered Movable Core Design
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Solution Overview
Problem
Conventional electromagnetic relays face difficulties in achieving sufficient electromagnetic attraction force due to the limited opposed areas between the movable and fixed cores, which restricts the increase in attraction force and leads to issues like inclination and reduced contact reliability.
Innovation Solution
The electromagnetic relay design includes a fixed core with a tapered portion and a circular portion, and a movable core with a tubular portion, allowing for increased opposed areas and a constant inner diameter, which enhances the electromagnetic attraction force while preventing side forces that cause inclination, and achieves linear or point contact to manage peak attraction forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the movable core and fixed core are formed as plates with inclined opposed surfaces, then the air gap is reduced and electromagnetic attraction force is increased immediately after energization, but the opposed areas are limited and sufficient electromagnetic attraction force cannot be obtained
Solution Approach 1:
The patent transitions from a two-dimensional plate structure to a three-dimensional structure where the movable core is formed as a tube with a hollow interior. This dimensional change allows the magnetic flux to pass through the hollow interior in addition to the lateral surfaces, effectively increasing the opposed area and the total electromagnetic attraction force without increasing the lateral dimensions of the core.
Solution Approach 2:
The movable core tube is positioned within the exciting coil such that the hollow interior of the tube is nested within the coil's magnetic field. This nesting arrangement allows the magnetic flux to penetrate through the hollow interior of the movable core, utilizing the internal space to enhance the magnetic circuit and increase the effective opposed area.
2Ease of operation
If the movable core is attracted toward the fixed core during energization, then the electromagnetic relay operates, but side forces cause inclination and reduce contact reliability
Solution Approach 1:
The movable core is designed with an asymmetric structure where one end is closed and the other end is open. This asymmetry, combined with the positioning of the movable core within the exciting coil, creates a stable magnetic circuit that prevents side forces and inclination during operation, thereby improving contact reliability.
Solution Approach 2:
The patent applies different geometric properties to different parts of the movable core. The lateral surface of the movable core tube is formed with a specific curvature or inclination that is optimized to reduce side forces, while the closed end and open end have different configurations that together ensure stable operation and prevent inclination.
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 significantly increases the electromagnetic attraction force, reduces air gap variation, and improves contact reliability by maintaining the inner diameter of the movable core cylindrical portion, allowing for efficient movement and reliable connection/disconnection of contacts.
Implementation Method 1
an exciting coil 12 having a cylindrical shape and generating a magnetic field during energization
Implementation Method 2
an electromagnetic attraction force is generated between opposed surfaces of a movable core formed of a plate and a fixed core formed of a plate due to the energization of an exciting coil
Data Source
AI summary
A fixed core includes: a fixed core tapered portion having a diameter increased in an attraction direction; and a fixed core circular portion having a fixed outer diameter and extending in the attraction direction from an end of the fixed core tapered portion. A movable core includes a movable core tubular portion in which a movable core hole is defined. The movable core hole is a space into which the fixed core tapered portion and the fixed core circular portion can enter. The movable core tubular portion includes: a movable core cylindrical portion having a constant inner diameter; and a movable core tapered tubular portion having an inner diameter decreased from an end of the movable core cylindrical portion in a non-attraction direction.