Coaxial Loudspeaker Magnet Segmentation for Flux Density
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Solution Overview
Problem
Coaxial loudspeakers face challenges in reducing weight and size while maintaining magnetic flux intensity, particularly in multi-way designs where ceramic ring magnets are inadequate for tweeters due to size and magnetic flux limitations, leading to the use of more expensive rare-earth magnets.
Innovation Solution
Incorporating a permanent magnet between the woofer and tweeter, aligned with similar or opposite magnetic poles, to enhance magnetic flux through the air gap, allowing for smaller and lighter magnets and a more compact design, with the option of using ceramic magnets for cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ceramic ring magnets are used in tweeters, then cost is reduced, but magnetic flux intensity in the air gap becomes insufficient
Solution Approach 1:
The magnetic system is segmented into multiple permanent magnets (first permanent magnet in the woofer, second permanent magnet in the tweeter, and third permanent magnet between them) that work together to generate the required magnetic flux, allowing each magnet to be smaller and use ceramic material while achieving sufficient total flux intensity
Solution Approach 2:
A third permanent magnet is introduced as an intermediary element between the woofer and tweeter magnets. This intermediate magnet enhances the magnetic flux in the air gap by providing additional magnetic field contribution, enabling the use of smaller ceramic magnets in both the woofer and tweeter while maintaining adequate flux intensity
2Reliability
If larger permanent magnets are used to increase magnetic flux, then magnetic flux intensity is improved, but weight and size of the loudspeaker increase
Solution Approach 1:
The magnetic flux generation is segmented across multiple smaller permanent magnets distributed throughout the loudspeaker structure (woofer magnet, tweeter magnet, and intermediate magnet), replacing what would otherwise require one or two large heavy magnets. This segmentation allows adequate total flux while reducing individual magnet sizes and overall weight
Solution Approach 2:
The magnetic flux path is extended into a third dimension by placing a permanent magnet between the woofer and tweeter. This intermediate magnet adds vertical dimension to the magnetic flux path, increasing flux intensity in the air gap without requiring larger horizontal magnet dimensions, thus maintaining compact size
3Reliability
If rare-earth magnets are used in tweeters, then magnetic flux intensity is sufficient, but cost increases
Solution Approach 1:
The magnetic system is divided into multiple segments that collectively provide sufficient flux, allowing each segment (magnet) to be smaller and use cost-effective ceramic material instead of expensive rare-earth magnets, while the combined effect of all magnets achieves the required flux intensity
Solution Approach 2:
The magnetic flux density parameter is enhanced not by using higher-grade (more expensive) magnet material, but by changing the system configuration to include multiple magnets with different polarities that constructively add their flux contributions, achieving high flux intensity with standard ceramic magnets
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 configuration increases magnetic flux density by up to 35% in the tweeter and 11% in the woofer, enabling smaller, lighter, and less costly rare-earth magnets, while maintaining performance comparable to conventional designs, and facilitates a more compact woofer motor geometry.
Implementation Method 1
a first permanent magnet disposed substantially within a center pole between a core cap and a bottom plate and generating a flux path through an air gap
Implementation Method 2
a voice coil at least partially positioned in the air gap
Data Source
AI summary
A loudspeaker includes a woofer having a first permanent magnet disposed substantially within a center pole having an associated magnetic polarity and generating a flux path through an air gap, a voice coil at least partially positioned in the air gap and having an inside diameter larger than an outside diameter of the first permanent magnet, a frame, a spider connecting the voice coil to the frame, and a diaphragm connected between the voice coil and the frame. A tweeter is generally coaxially positioned relative to the woofer and includes a second permanent magnet. A third permanent magnet is coaxially positioned between the woofer and the tweeter. A non-magnetic structure may encompass the third permanent magnet.