Bistable Electromagnetic Actuator with Lateral Spacing Flux Deflection
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Solution Overview
Problem
Existing electromagnetic actuators for electrical contactors have variable switching times, making it difficult to anticipate contactor closure and minimize stress on loads, and are sensitive to supply voltage and temperature variations, leading to increased costs and size due to the need for control electronics.
Innovation Solution
A bistable electromagnetic actuator with a magnetic core, an electromagnetic coil, and a permanent magnet, where the magnet is movable between two positions, and lateral spacings deflect both magnet and coil fluxes towards air gaps, reducing dependence on coil flux for driving and holding forces, thus stabilizing switching times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control electronics with a regulator are used to control the supply current of the coil, then stable switching times are achieved, but additional costs are generated and the size of the actuator increases
Solution Approach 1:
The actuator uses a permanent magnet to generate a magnetic field that automatically compensates for variations in coil flux, eliminating the need for external control electronics. The permanent magnet's field interacts with the coil flux to maintain stable switching times regardless of supply voltage or temperature changes, making the system self-regulating.
Solution Approach 2:
The invention changes the magnetic field parameters by introducing a permanent magnet with specific magnetic moment orientation. This permanent magnet field superimposes on the coil flux, creating a combined magnetic field whose characteristics remain stable despite variations in coil current, thereby stabilizing switching times without electronic control.
2Force
If high values of magnetic field are used to drive the actuator, then switching force is improved, but the bell phenomenon produces a torque opposite to that sought
Solution Approach 1:
The permanent magnet is positioned asymmetrically relative to the coil, with its magnetic moment oriented at a specific angle (e.g., 45 degrees) to the coil axis. This asymmetric configuration creates an uneven distribution of magnetic flux that counteracts the bell phenomenon's opposing torque while maintaining strong switching force.
Solution Approach 2:
The permanent magnet acts as an intermediary that modifies the interaction between the coil flux and the armature. By introducing this intermediate magnetic field, the system achieves strong switching force while the permanent magnet's field distribution prevents the buildup of opposing magnetic feedback torque that occurs with high coil flux alone.
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 actuator achieves consistent switching times within a millisecond range, facilitating synchronous switching and reducing stress on electrical contacts, without the need for complex control electronics, thereby reducing costs and size.
Implementation Method 1
an electromagnetic coil wound around the central branch of the core and able to generate a magnetic flux, called coil flux, through the core
Implementation Method 2
a magnetized member comprising a permanent magnet and at least one metal part, the magnetized member being capable of generating a magnetic flux, called magnet flux
Implementation Method 3
the magnet flux generates a force for maintaining the stable positions and a motor force for switching
Data Source
Figure 1
Figure 2~3
Figure 4~9
AI summary
This electromagnetic actuator (3) for an electrical contactor (2) comprises a magnetic core (4) having first and second stop surfaces (422A, 422B) and two lateral arms (42A, 42B); a coil (6) generating a coil flux through the core; and a magnetized element (8) generating a magnet flux and having first and second contact surfaces (802A, 802B). The magnetized element is movable relative to the core between first and second positions. The gap (32A) between the first contact surface and the first stop surface forms a first air gap, and the gap (32B) between the second contact surface and the second stop surface forms a second air gap, the magnetized element being in one of the first and second positions when there is no coil flux. The magnetized element is, apart from the contact and stop surfaces, separated from each lateral branch by a respective lateral spacing (34A, 34B).