Rotating-Seal Axial Guide Bearing for Low-Distortion Loudspeakers

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Solution Overview

Problem

Existing axial guidance systems in loudspeakers, such as those using spiders, suffer from imperfect guidance, allowing angular movement and introducing non-linear restoring forces that distort sound quality and increase friction, making it difficult to control the membrane effectively.

Innovation Solution

An axial guide bearing with a rotatable seal and asynchronous motor, featuring smooth cylindrical surfaces and fluid or ferromagnetic lubricant-filled plain bearings, minimizes friction and ensures precise axial guidance by rotating the seal relative to the casing and shaft, using an asynchronous motor with a magnetic circuit and windings to create a rotating magnetic field.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a spider is used for axial guidance of the diaphragm, then the diaphragm can be guided axially, but the guidance is imperfect allowing angular displacement and introduces non-linear restoring forces that distort sound quality

Engineering Contradiction:
Improveaxial guidance precisionVSAvoidangular displacement and non-linear restoring forces
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention removes the spider component entirely from the loudspeaker system and replaces it with an axial guide bearing assembly consisting of a shaft, outer casing, and seal. This extraction eliminates the harmful non-linear restoring forces and angular displacements generated by the spider while maintaining axial guidance functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical spider structure with a fluid film bearing system where a fluid layer is introduced between the seal and the shaft. This substitution transforms the mechanical contact-based guidance into a fluid-based guidance system that provides linear restoring forces and eliminates angular displacement.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If a spider is used for axial guidance, then the diaphragm movement is constrained, but the elastic component adds friction and makes control difficult

Engineering Contradiction:
Improvediaphragm controlVSAvoidfriction from elastic component
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

The invention replaces the elastic spider component with a fluid film bearing system where a fluid layer is introduced between the seal and the shaft. This substitution eliminates the friction generated by the elastic component while maintaining axial constraint, thereby improving diaphragm control and reducing energy loss.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If a traditional seal is used between the shaft and casing, then axial guidance is provided, but friction is high and precision is limited

Engineering Contradiction:
Improveaxial guidance precisionVSAvoidfriction between seal and shaft
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

The invention introduces a fluid layer as an intermediary substance between the seal and the shaft. This fluid intermediary reduces direct contact and friction between the seal and shaft surfaces while providing precise axial guidance through the fluid film, thereby improving measurement precision and reducing energy loss.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention employs a fluid film (liquid or gas) between the seal and shaft to create a hydrodynamic or aerodynamic bearing. This pneumatic/hydraulic approach replaces traditional mechanical contact with fluid-based support, significantly reducing friction and improving axial guidance precision.

Inventive Principle:
Principle #29Pneumatics and hydraulics

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 provides high-precision, low-friction axial guidance, reducing distortion and improving sound quality by minimizing angular errors and energy consumption, while maintaining silent operation and efficient magnetic performance.

Implementation Method 1

the means for setting it in rotation comprise an asynchronous motor with, on the one hand, a magnetic circuit and a set of windings attached to the casing, and on the other hand, a magnetized structure attached to the lining

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The plain bearing(s) comprise a fluid interposed between the facing surfaces

Methodology Applied
Scientific EffectFluid lubrication: Lubrication

Implementation Method 3

The plain bearing(s) comprise a ferromagnetic lubricant film interposed between the facing surfaces

Methodology Applied
Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentEP4098895B1Axial guide bearing, especially for loudspeaker
Publication Date: 2024.11.20 DEVIALET
  • EP4098895B1 patent drawingFigure 1
  • EP4098895B1 patent drawingFigure 2
  • EP4098895B1 patent drawingFigure 3

AI summary

The bearing (40) for linearly guiding a shaft (42) along axis XX comprises: - a shaft (42) with axis XX; - an outer casing (46) in which the shaft (42) is received sliding along axis XX by means of a linearly guiding bearing; and - an annular seal (50) interposed between the casing (46) and the shaft (42), the seal (50) having a smooth and continuous cylindrical inner surface with axis XX complementary to the outer surface of the shaft (42) to cooperate with the outer surface of the shaft (42) to form an internal plain bearing (54). The seal (50) is rotatably mounted relative to the outer casing (46) about axis XX, and the bearing includes drive means (60) for rotating the seal (50) relative to the outer casing (46) on the one hand and the shaft (42) on the other hand about axis XX. Application to a loudspeaker