Oral Care Attachment Coupling With Deformable Wall Alignment

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Solution Overview

Problem

Existing magnetic couplings for oral care device attachments are expensive due to the use of magnets and magnetizable elements, and there is a need for a less expensive coupling that still allows for a small circumferential gap between the drive shaft and the housing.

Innovation Solution

A mechanical coupling system using an essentially cylindrical drive shaft coupling end with a deformable or elastic wall element, indentation, or non-coaxial design, which includes a top plate and deformable wall elements made from materials like thermoplastic elastomer or metal, allowing for a secure attachment without magnets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetic coupling is used to connect the drive shaft and attachment, then the coupling is wear-free and operates in a low noise manner, but the coupling becomes relatively expensive due to the use of magnets and magnetizable elements

Engineering Contradiction:
Improvecoupling durabilityVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the magnetic coupling system with a mechanical coupling system using a drive shaft end with a specific geometry (cylindrical or conical) that directly engages with a corresponding receptacle in the attachment. This mechanical substitution eliminates the need for magnets and magnetizable elements, thereby reducing manufacturing costs while maintaining the coupling function.

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

Solution Approach 2:

The mechanical coupling design allows for the use of simpler, less expensive materials and manufacturing processes compared to magnetic coupling. The drive shaft end and receptacle can be produced using conventional machining or molding techniques, making the overall system more cost-effective.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Ease of manufacture

If a mechanical coupling system is used to reduce costs, then manufacturing expenses decrease, but achieving a small circumferential gap between the drive shaft and housing becomes more difficult

Engineering Contradiction:
Improvemanufacturing costVSAvoidcircumferential gap tolerance
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent employs asymmetric geometry in the drive shaft end design, specifically using a conical surface instead of a purely cylindrical one. This conical geometry allows for self-centering and automatic alignment when the attachment is coupled to the drive shaft, facilitating the achievement of small circumferential gaps without requiring extremely tight manufacturing tolerances.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The use of a conical surface (a curved geometry) on the drive shaft end provides smooth transition and contact surfaces that naturally guide the attachment into proper alignment. This curved geometry helps distribute contact forces and facilitates precise positioning, thereby achieving small circumferential gaps with reasonable manufacturing precision.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 mechanical coupling provides a cost-effective solution with a small gap, ensuring stable transmission of linear vibration while reducing material costs and maintaining operational efficiency.

Implementation Method 1

at least one at least partly deformable essentially cylindrical wall element extending from the top plate or at least two elastic or deflectable wall elements extending from the top plate, respectively

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4434489B1Attachment for an oral care device handle
Publication Date: 2026.04.15 BRAUN GMBH
  • EP4434489B1 patent drawingFigure 1
  • EP4434489B1 patent drawingFigure 2
  • EP4434489B1 patent drawingFigure 3

AI summary

The present disclosure is concerned with an oral care device attachment that is arranged for being coupled to an oral care device handle having an essentially cylindrical drive shaft coupling end, the attachment having an outer attachment tube having a coupling end that is intended for being detachably secured at a housing of the oral care device handle, a carrier being mounted for driven motion at the outer attachment tube, a motion transmitter being disposed inside of the outer attachment tube, the motion transmitter having a first end coupled with the carrier and a second end being arranged for coupling with the essentially cylindrical drive shaft coupling end, the second end having a coupling unit having a top plate and one at least partly deformable essentially cylindrical wall element extending from the top plate so that an essentially cylindrical receiver receptacle is defined by the top plate and the one at least partly deformable essentially cylindrical wall element.