Electromagnetic Relay With Magnetic Return Spring
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Solution Overview
Problem
Conventional electromagnetic relays face challenges in setting a small air gap between the stationary and movable cores while ensuring a sufficient gap for operation, which restricts the electromagnetic attractive force at the start of energization and requires a complex configuration for the return spring to perform both magnetic circuit and separation functions.
Innovation Solution
The electromagnetic relay includes a coil, a stationary core, a yoke, a movable core, and a return spring made of magnetic material, with specific gap configurations and spring placements to enhance the attractive force at the start of energization and simplify the spring configuration, allowing for increased magnetic flux and improved attractive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a small air gap is set between the stationary core and movable core, then the electromagnetic attractive force is improved, but the gap for operation becomes insufficient
Solution Approach 1:
The air gap is divided into two segments: a first air gap between the stationary core and movable core for magnetic flux, and a second air gap between the movable core and yoke for operational movement. This segmentation allows the first gap to be small for strong attraction while the second gap provides sufficient operational clearance.
Solution Approach 2:
Different regions of the magnetic circuit are assigned different gap characteristics: the region between stationary core and movable core has a small gap for high magnetic flux density, while the region between movable core and yoke has a larger gap for mechanical operation. This local differentiation resolves the contradiction between magnetic force and operational clearance.
2Device complexity
If the return spring is configured to perform both magnetic circuit and separation functions, then the device complexity is reduced, but the manufacturing precision becomes difficult to control
Solution Approach 1:
The return spring is designed to perform dual functions: it provides the separating force to open contacts and simultaneously serves as a magnetic flux conductor in the magnetic circuit. This multi-functionality reduces the number of separate components needed while maintaining precise operational characteristics through proper spring positioning.
3Force
If a small air gap is set between the stationary core and movable core, then the electromagnetic attractive force is improved, but the relay requires a complex return spring configuration
Solution Approach 1:
The return spring serves dual purposes as both a mechanical separator and a magnetic flux conductor, eliminating the need for separate magnetic circuit components. This multi-functionality simplifies the overall configuration while enabling the small air gap needed for strong electromagnetic attraction.
Solution Approach 2:
The return spring is merged with the magnetic circuit by positioning it to conduct magnetic flux between the movable core and yoke. This combination of mechanical and magnetic functions in a single component reduces device complexity while maintaining the small air gap for strong attraction force.
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 increases the attractive force at the start of energization, improving the relay's operational efficiency and reducing the complexity of the return spring design, enabling effective on/off control of electric circuits.
Implementation Method 1
attraction force caused by energization of the coil
Implementation Method 2
The movable core is attracted toward the stationary core on energization of the coil
Data Source
AI summary
A stationary core is in an exciting coil. A yoke covers an outer periphery and an axial end of the exciting coil to form a magnetic circuit and has an opening portion. The movable core faces the stationary core through the opening portion and is attracted toward the stationary core on energization of the exciting coil. A return spring urges the movable core against the attraction direction. A first gap is formed between the stationary core and the movable core on deenergization of the exciting coil. A second gap is formed between the yoke and the movable core on deenergization of the exciting coil. The second gap allows the yoke and the movable core to generate an attractive force therebetween on energization of the exciting coil. The return spring is made of a magnetic material to magnetically bridge the first gap or the second gap.