Attachment for an oral care device handle and oral care device comprising the attachment

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Solution Overview

Problem

Existing magnetic couplings between the drive shaft of an oral care device handle and the motion transmitter in oral care device attachments are expensive due to the use of magnets, necessitating a less costly yet effective alternative that maintains a small circumferential gap.

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 arrangement, combined with a spring biasing mechanism, to securely attach the attachment to the handle without magnets.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetic coupling components (magnets) are used to couple the drive shaft to the motion transmitter, then the coupling is wear-free and low-noise, but the manufacturing cost increases significantly

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

Solution Approach 1:

The patent extracts and removes the expensive magnetic coupling components from the system. Instead of using magnets in the drive shaft coupling end, the invention employs a purely mechanical coupling structure where the motion transmitter is directly coupled to the drive shaft through mechanical features such as recesses, protrusions, or friction surfaces, eliminating the need for magnets and their associated costs while maintaining wear-free operation

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs inexpensive mechanical coupling components such as plastic or metal friction surfaces, recesses, and protrusions that can be easily manufactured through standard molding or machining processes. These components are designed to be cost-effective while providing sufficient durability for the application, replacing expensive magnetic assemblies with affordable mechanical alternatives

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

2Volume of moving object

If the circumferential gap between the drive shaft coupling end and handle housing is reduced to less than 1mm, then the coupling area becomes more compact, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvecoupling area sizeVSAvoidgap tolerance
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The patent introduces dynamic elements into the coupling system, such as elastic friction surfaces that can deform and adapt to dimensional variations. The motion transmitter or drive shaft coupling end incorporates compliant features that allow for slight misalignments and gap variations, enabling the system to maintain compact dimensions while accommodating normal manufacturing tolerances without requiring ultra-precise fits

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the physical parameters of the coupling surfaces, such as using elastic or deformable materials that can compensate for dimensional variations. By altering the material properties or geometric parameters (e.g., adding compliance features, friction surfaces with controlled coefficients), the system achieves compact coupling dimensions while being tolerant of normal manufacturing variations

Inventive Principle:
Principle #35Parameter changes

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

Provides a cost-effective coupling solution that maintains a small gap and ensures stable transmission of linear vibration from the drive shaft to the motion transmitter, reducing wear and noise while allowing for easy detachment and replacement.

Implementation Method 1

at least one essentially cylindrical wall element (220) which is deformable or elastic

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

securely attach the attachment to the handle without magnets

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 3

combined with a spring biasing mechanism

Methodology Applied
Scientific EffectSpring force: Spring

Data Source

PatentEP4218666B1Attachment for an oral care device handle and oral care device comprising the attachment
Publication Date: 2025.07.02 BRAUN GMBH
  • EP4218666B1 patent drawingFigure 1
  • EP4218666B1 patent drawingFigure 2
  • EP4218666B1 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 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, where each of the elastic or deflectable wall elements extends over a portion of a virtual receiver cylinder so that an essentially cylindrical receiver receptacle is defined by the top plate and the one at least partly deformable essentially cylindrical wall element or by the top plate and the at least two elastic or deflectable wall elements.