Voice Coil Arrays for Reduced Magnet Mass and Inductance
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Solution Overview
Problem
Conventional voice coil actuators require significant permanent magnet and flux conducting material, leading to high costs and limited frequency bandwidth due to high inductance, necessitating a design that minimizes these materials while maintaining force output performance.
Innovation Solution
The integration of a one-dimensional or two-dimensional voice coil array with a magnet assembly and suspension system, utilizing flux concentrators and shorting rings to reduce magnetic flux reliance and inductance, allowing for a more compact and efficient actuator with lower material usage and increased frequency bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a monolithic voice coil actuator design is used, then force output performance is achieved, but the amount of permanent magnet and flux conducting material is excessive
Solution Approach 1:
The patent divides the monolithic voice coil actuator into multiple smaller coil assemblies arranged in an array. Each coil assembly generates a portion of the total force, and the segmented structure allows for optimized magnetic flux paths that reduce the total amount of permanent magnet material required while maintaining the overall force output performance.
2Productivity
If conventional voice coil designs are used, then force generation is adequate, but coil inductance is high which limits frequency bandwidth
Solution Approach 1:
By segmenting the single large coil into multiple smaller coils in an array, the total inductance is reduced because each small coil has lower self-inductance and the magnetic flux paths are shorter and more direct. This segmentation enables higher frequency operation while maintaining force generation capability.
3Force
If more permanent magnet material is used, then magnetic flux is stronger, but cost and weight increase
Solution Approach 1:
The patent implements local quality optimization by positioning permanent magnets and flux conducting elements only where they are most effective in each segmented coil assembly. The magnetic flux paths are locally optimized to maximize flux density at the coil locations while minimizing the total volume of permanent magnet material required throughout the structure.
4Force
If flux conducting material is increased, then magnetic flux conduction is improved, but device weight and complexity increase
Solution Approach 1:
The patent extracts and removes unnecessary flux conducting material from the structure, retaining only the essential elements needed to guide magnetic flux through the segmented coil assemblies. This extraction reduces the total amount of flux conducting material and associated weight while maintaining adequate magnetic flux conduction for force generation.
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 solution achieves the same force output as monolithic actuators with reduced permanent magnet and flux conducting material, resulting in a lighter, more cost-effective design with enhanced frequency bandwidth.
Implementation Method 1
the magnet assembly comprises an array of lateral and vertical permanent magnets in contact with flux concentrators, wherein the flux concentrators correspond to and are aligned with the coils of the coil assembly, such that a concentrated uniform magnetic flux is directed laterally through the coils
Implementation Method 2
The interaction between the current passing through the coil and the magnetic field causes the coil to produce forces perpendicular to the current and the magnetic field, which drive an inertial mass to produce output force into the supporting structure
Implementation Method 3
Some devices use a conducting loop, called a shorting ring or Faraday ring, in the coil flux path. Current induced in this loop counteracts the coil flux, which raises the path reluctance and thereby the inductance
Data Source
AI summary
Inertial actuators are provided, which use a one-dimensional or a two-dimensional voice coil array to achieve the same force output performance as a monolithic actuator. The voice coil arrays use less permanent magnet and flux conducting material, and have a lower inductance, while achieving increased frequency bandwidth.