Coupling Recess Sloped Surface for Attachment Retention
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Solution Overview
Problem
Existing personal care devices with releasable attachments, such as shavers and trimmers, face issues where the attachment can be unintentionally released due to off-center pulling forces, leading to inadequate retention and potential damage from overloading forces.
Innovation Solution
The design incorporates a shaft-like element with a convex circumferential surface featuring coupling recesses with a sloped surface inclined towards the central axis, where the side portions are recessed relative to the sloped surface, enhancing retention by ensuring the sloped surface plays a dominant role in engagement with the spring element, thus providing increased resistance against unintentional release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the attachment is firmly mounted to prevent unintentional release, then retention reliability is improved, but the attachment may be damaged in case of overloading force
Solution Approach 1:
The patent changes the geometric parameters of the coupling recess, specifically creating a convex circumferential surface with a central portion that has a larger radius of curvature than the side portions. This parameter change allows the coupling to maintain high retention force through the sloped surface geometry while providing a release mechanism when excessive force is applied, thus resolving the contradiction between retention reliability and damage resistance
2Ease of operation
If the attachment is loosely mounted to allow easy removal, then ease of operation is improved, but the attachment can be unintentionally released during use
Solution Approach 1:
The patent applies local quality by creating different geometric characteristics in different portions of the coupling recess. The central portion has a larger radius of curvature and provides the primary retention through its sloped surface, while the side portions have smaller radii and provide secondary engagement. This local differentiation ensures easy intentional removal while preventing unintentional release during normal use
3Ease of manufacture
If the coupling recess has uniform depth, then manufacturing simplicity is improved, but off-center pulling forces cause uneven gliding and unintended release
Solution Approach 1:
The patent introduces asymmetry in the coupling recess design by creating a convex circumferential surface where the central portion has a larger radius of curvature than the side portions. This asymmetric geometry ensures that when off-center pulling forces are applied, the spring element glides smoothly along the sloped surface from the side portions toward the central portion, maintaining engagement and preventing unintended release while still allowing easy intentional removal
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 ensures a higher retaining force and reduced risk of unintended release, while allowing for easy intended removal by central pulling force, thereby improving the stability and usability of the attachment during normal use and protecting against overloading.
Implementation Method 1
a spring element for engagement with the sloped surface of the at least one coupling recess to establish a releasable coupling
Data Source
AI summary
An attachment for a personal care device, such as a shaving or trimming device, is configured to be releasably coupled to a coupling structure of the personal care device by a coupler. The coupler includes a shaft having at least one coupling recess on the circumferential surface thereof. The coupling recess has a central portion and first and second side portions arranged on opposite sides of the central portion. The coupling recess also includes a sloped surface arranged in at least the central portion. When the attachment is coupled to the coupling structure, the sloped surface is engaged by a spring of the coupling structure. At least one of the first and second side portions of the coupling recess is recessed relative to the sloped surface, seen in a direction parallel to the central axis of the shaft.