Electromagnetic Actuator With Variable Air Gaps For Custom Force-Stroke
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Solution Overview
Problem
Existing electromagnetic actuators lack the ability to provide unique force-stroke relationships depending on the stroke direction, which is essential for applications like vacuum circuit breakers, and they often require custom mechanical spring mechanisms that are costly and require maintenance.
Innovation Solution
The electromagnetic actuator incorporates multiple air gaps, including a variable air gap, and pole shaping to generate a magnetic field that adjusts based on the plunger's position, allowing for customizable force-stroke relationships by varying the air gap sizes as the plunger moves, facilitated by permanent magnets and strategically positioned coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single air gap is used in the electromagnetic actuator, then the structure is simple, but the force-stroke relationship cannot be customized for different directions
Solution Approach 1:
The single air gap is divided into two separate air gaps (first air gap and second air gap) positioned at different locations. This segmentation allows each air gap to be independently controlled, enabling different force-stroke relationships in different stroke directions while maintaining a manageable structural complexity
Solution Approach 2:
The air gaps are designed to be variable rather than fixed. The first air gap varies as the plunger moves between positions, and the second air gap varies in opposition. This dynamic variation allows the actuator to provide customized force-stroke relationships for both closing and opening operations
2Adaptability or versatility
If mechanical spring mechanisms are used to achieve custom force-stroke relationships, then the force-stroke curve requirements are met, but the cost increases and maintenance is required
Solution Approach 1:
The patent replaces mechanical spring mechanisms with an electromagnetic system. Instead of using physical springs to generate force-stroke characteristics, the invention uses controlled electromagnetic fields acting through variable air gaps to achieve the same functional result, eliminating the need for mechanical springs and their associated maintenance
Solution Approach 2:
The invention changes the physical parameters of the magnetic circuit (air gap sizes, plunger position) to control the force-stroke relationship. By varying the air gap dimensions through plunger movement, the system achieves customized force characteristics without requiring mechanical spring components
3Force
If the plunger moves closer to the coil, then the magnetic force increases, but the air gap reluctance increases causing force loss
Solution Approach 1:
The magnetic circuit is segmented into multiple paths with different air gaps. When the plunger moves closer to the coil, the first air gap decreases (increasing force) while the second air gap increases (maintaining flux path). This segmentation allows the system to overcome the reluctance problem by providing alternative flux paths
Solution Approach 2:
The air gap configuration is made dynamic rather than static. As the plunger position changes, the air gap sizes change in a controlled manner to maintain optimal magnetic flux distribution, preventing energy loss while maximizing magnetic force at different stroke positions
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 design achieves unique force-stroke relationships depending on the stroke direction, reduces the footprint and maintenance compared to mechanical spring mechanisms, and provides a cost-effective solution for applications like vacuum circuit breakers.
Implementation Method 1
The coil is proximally disposed with the first yoke portion and, when energized, is configured to generate a magnetic field. The magnetic field causes the plunger to move toward the first position by a magnetic flux through a magnetic circuit.
Implementation Method 2
generating an electromotive force corresponding to the first magnetic flux. The electromotive force is applied to the plunger, causing the plunger to travel toward the first yoke portion.
Implementation Method 3
The first air gap and variable air gap are at least partially defined by the first yoke portion and the plunger. The first air gap diminishes as the plunger moves toward the first position. The variable air gap enlarges as the plunger moves toward the first position.
Data Source
AI summary
An electromagnetic actuator includes a plunger, an armature, and a coil. The plunger is moveable between a first position and a second position. The armature includes a first armature portion proximally disposed about the first position, and a second armature portion proximally disposed about the second position. The coil is proximally disposed with the first armature portion and, when energized, is configured to generate a magnetic field. The magnetic field causes the plunger to move toward the first position by a magnetic flux through a magnetic circuit. The magnetic circuit includes the first armature portion, the plunger, a main air gap, and a variable air gap. The main air gap and variable air gap are between the first armature portion and the plunger. The main air gap diminishes as the plunger moves toward the first position. The variable air gap enlarges as the plunger moves toward the first position.