Bi-stable Relay With Rotating Coil Resists Magnetic Tampering
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Solution Overview
Problem
Conventional electromagnetic relays are susceptible to magnetic tampering due to their design, where permanent magnets are housed in a rotating plastic casing, making them vulnerable to external magnetic fields, which can cause mechanical motion and disrupt the switching state, especially under strong magnetic fields like 5000 Gauss.
Innovation Solution
A bi-stable electromagnetic relay assembly is designed with fixed permanent magnets inside a plastic casing and a rotatable coil assembly, where the coil itself rotates, creating a stronger magnetic field and minimizing displacements, ensuring the relay maintains its state even under external magnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If permanent magnets are housed in a rotating plastic casing, then the relay can achieve mechanical motion for switching, but the relay becomes susceptible to magnetic tampering from external magnetic fields
Solution Approach 1:
The patent inverts the conventional relay design by making the coil assembly rotatable instead of the permanent magnets. The coil assembly rotates between fixed permanent magnets, reversing which component moves and which remains stationary. This inversion protects the permanent magnets from external magnetic fields while maintaining switching capability through coil rotation.
Solution Approach 2:
The patent extracts the permanent magnets from the rotating assembly and fixes them in place within the plastic casing. Only the coil assembly rotates, separating the magnetic field generation function from the moving parts. This extraction eliminates the vulnerability of permanent magnets to external magnetic fields during rotation.
2Reliability
If the coil assembly rotates to create magnetic field, then the relay maintains state under external magnetic interference, but the manufacturing complexity increases
Solution Approach 1:
The rotatable coil assembly serves multiple functions: it generates the magnetic field for switching, acts as the rotating element that changes magnetic coupling, and provides the mechanical motion needed for contact switching. This multi-functionality reduces the need for separate components and simplifies the overall mechanism despite the rotation requirement.
Solution Approach 2:
The patent merges the coil, its magnetic field generation function, and the rotating mechanism into a single integrated coil assembly. The coil housing and rotation mechanism are combined, eliminating the need for separate drive mechanisms and reducing overall device complexity while achieving the desired rotational motion for magnetic field control.
3Force
If the coil assembly rotates about an orthogonal axis, then the magnetic field strength increases and displacements are minimized, but the device complexity increases
Solution Approach 1:
The patent changes the rotation axis from parallel to orthogonal relative to the coil axis, utilizing a different spatial dimension for rotation. This orthogonal rotation allows the coil to sweep through magnetic field lines more effectively, increasing magnetic field strength and improving coupling with the fixed permanent magnets while maintaining a compact structure.
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
The design enhances the relay's resistance to magnetic tampering, maintaining its operational state under strong external magnetic fields, ensuring reliable switching and preventing unauthorized tampering, such as turning electricity meters back on.
Implementation Method 1
the coil assembly creates a magnetic field directable through the core for imparting rotation about an axis of rotation orthogonal to coil assembly axis
Implementation Method 2
opposed pairs of attractive magnets respectively and fixedly positioned adjacent core termini
Data Source
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AI summary
An electromagnetic relay assembly comprises a rotatable electromagnetic coil assembly, first and second pairs of opposed permanent magnets, and a switch assembly. The coil assembly comprises a coil, a core, and a rotatable coil housing. The coil is wound around the core. The core comprises opposed core termini, and the coil housing has an axis of rotation orthogonal to the coil axis. The magnet pairs fixedly positioned adjacent the core termini such that the core termini are respectively displacable intermediate the magnet pairs. The coil operates to create a magnetic field directable through the core for imparting coil housing rotation about the axis of rotation via attraction to the positioned/anchored magnets. The core termini displace linkage arms, and the linkage arms actuate contact-spring assemblies of the switch assembly intermediate open and closed positions.