Electromagnetic Contactor Rim for Voltage Dip Resistance
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Solution Overview
Problem
Electromagnetic contactors, especially smaller caliber devices, struggle to naturally withstand voltage dips or interruptions due to a low L/R ratio in the magnetic circuit/coil assembly, requiring complex and costly energy buffer systems or oversizing of the magnetic circuit.
Innovation Solution
Incorporating a rim around the opening of the magnetic circuit's axial passage outside the coil winding, which increases permeance without enlarging the winding zone, and using a phosphating treatment to enhance resistance to voltage dips and interruptions, allowing for a simple and cost-effective design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an energy buffer system is mounted at the terminals of the contactor coil to withstand voltage dips or interruptions, then the contactor can maintain circuit closure during voltage interruptions, but the complexity and cost of the contactor increase
Solution Approach 1:
The patent extracts the essential function of withstanding voltage dips from the complex energy buffer system and implements it through a simple geometric modification - adding a rim to the magnetic circuit. This rim structure increases permeance without requiring external energy storage components, thereby achieving the reliability improvement while avoiding the complexity and cost increase associated with traditional energy buffer systems
Solution Approach 2:
The patent changes the geometric parameters of the magnetic circuit by introducing a rim that increases the flow passage surface area. This parameter change (increased permeance) fundamentally alters the magnetic circuit's behavior during voltage dips, enabling it to maintain circuit closure without requiring additional energy storage components or complex control systems
2Reliability
If the magnetic circuit is oversized to increase permeance and withstand voltage dips, then the contactor can maintain circuit closure during interruptions, but the size of the contactor increases
Solution Approach 1:
Instead of uniformly oversizing the entire magnetic circuit, the patent applies a local quality enhancement by adding a rim specifically at the flow passage area. This localized modification concentrates the permeance increase where it is most needed, achieving the reliability improvement without proportionally increasing the overall contactor size
3Reliability
If the rim extends into the axial passage to increase permeance, then the permeance in the closed state is increased, but the winding zone is encroached upon and the winding height is reduced
Solution Approach 1:
The patent resolves the spatial conflict by changing the dimensional arrangement - the rim extends in a direction parallel to the coil winding rather than into the axial passage occupied by the winding. This dimensional repositioning allows the rim to increase permeance through the flow passage surface area without encroaching on the winding zone or reducing winding height
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 solution enables improved resistance to voltage dips and interruptions across various contactor sizes without increasing size or complexity, maintaining a simple structure and reducing costs.
Implementation Method 1
a coil for generating a magnetic field, a magnetic circuit comprising a fixed part with respect to the coil and a movable part with respect to the coil under the action of the magnetic field delivered by the latter
Implementation Method 2
the flow passage surface between the fixed part and the mobile part is increased at the level of the rim, the latter being facing the mobile part. Thus the permeance in the closed state of the magnetic circuit is increased
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The contactor has a magnetic circuit with a fixed part (3) fixed with respect to a magnetic field generating coil (2), and a mobile part (4) fixed with respect to the coil by using an action of magnetic field delivered by the coil. The coil forms a winding around an axial passage (12) in which the mobile part is displaced. A voltage interruption and dips holding unit has a flange (13) that is extended around an opening (7) from a wall towards an interior of a housing, so that the flange is exterior to the axial passage defined by the winding of the coil.