Detachable Cartridge Coupling With U-Shaped Spring Retention

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Solution Overview

Problem

Existing skin treatment devices with detachable cartridges face issues of increased production and assembly costs, bulkier designs, and limited flexibility due to the use of numerous parts for attachment and retention, leading to a less modern and less dynamic appearance.

Innovation Solution

A coupling unit featuring a U-shaped spring with parallel arms and a connecting bar, which provides a retention force without exceeding typical operation forces, ensuring proper interconnection while minimizing installation space and using fewer parts, allowing for easy assembly and detachment of cartridges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If numerous parts are used for attachment and retention, then the retention force and connection reliability are improved, but the device complexity and production costs increase

Engineering Contradiction:
Improveconnection reliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple retention functions into a single U-shaped spring component that integrates both attachment and retention capabilities. The spring's first arm engages with the drive pin while the second arm engages with the second pin, allowing one component to perform what previously required multiple separate parts, thereby reducing device complexity while maintaining connection reliability

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The U-shaped spring serves multiple functions simultaneously: it provides retention force, enables easy attachment and detachment, and maintains connection reliability. This multi-functional design eliminates the need for separate retention mechanisms, reducing the number of parts while ensuring reliable cartridge-to-handle connection

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Force

If numerous parts and larger installation space are used, then the retention force is improved, but the device size increases and appearance becomes less modern

Engineering Contradiction:
Improveretention forceVSAvoiddevice size
Core Design Contradiction:
ForceVSVolume of moving object

Solution Approach 1:

The U-shaped spring utilizes the third dimension (depth) by extending arms in opposite directions perpendicular to the cartridge's main axis. This spatial arrangement allows the spring to generate sufficient retention force through lever action while maintaining a compact overall footprint, avoiding the need for a bulkier design that would compromise the modern appearance

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Device complexity

If a simple design with fewer parts is used, then the device appearance is more modern and production costs are reduced, but the retention force and connection reliability may be compromised

Engineering Contradiction:
Improvedevice complexityVSAvoidconnection reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The U-shaped spring's curved geometry provides mechanical advantage, allowing it to generate sufficient retention force through its arc shape. The curvature enables the spring to distribute forces effectively across both engagement points, maintaining connection reliability while using a simple, elegant design that reduces part count and production costs

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 U-shaped spring design achieves a flat spring ratio with increased spring length, providing sufficient retention force with minimal parts and space, facilitating easy attachment and detachment while maintaining a sleek device design and ensuring proper cartridge connection.

Implementation Method 1

a U-shaped spring (9) provided in the coupling unit (1), having two arms (11, 12) extending at least substantially parallel to each other in a first direction (x) and a connecting bar (13) connecting the arms and extending in a second direction (y) which is at least substantially perpendicular to the first direction (x)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3546770B1Electric skin treatment device and coupling unit for a skin treatment device
Publication Date: 2021.01.20 BRAUN GMBH
  • EP3546770B1 patent drawingFigure 1~2
  • EP3546770B1 patent drawingFigure 3~4
  • EP3546770B1 patent drawingFigure 5~6

AI summary

The present invention is related with a coupling unit (1) for connecting a detachable cartridge (2) containing at least one skin treatment unit (3) to a handle component (4) of an electric skin treatment device (5). The coupling unit (1) comprises a frame (6), wherein the frame (6) comprises at least two opposing notches (7, 8) that are each adapted to receive a respective engagement element (21, 22) of the cartridge (2), and wherein the frame (6) is provided with a U-shaped spring (9) having two arms (11, 12) extending at least substantially parallel to each other in a first direction (x) and a connecting bar (13) connecting the arms (11, 12) and extending in a second direction (y) which is at least substantially perpendicular to the first direction (x), wherein the respective free end (10, 18) of each arm (11, 12) of the U-shaped spring (9) resides in a recess (16, 17) respectively providing support to the spring (9). Each of the two arms (11) of the U-shaped spring (9) extends across one of the notches (7, 8) respectively, wherein the recesses (16,17) and the U-shaped spring (9) are configured such that the two arms (11, 12) are elastically deflected together into the second direction (y) when the engagement elements (21, 22) are inserted into the at least two opposing notches (7, 8). The present invention is further related with an electric skin treatment device (5) comprising a handle component (4) with a motor, a coupling unit (1) and a detachable cartridge (2) containing at least one skin treatment unit (3) which is releasably coupled to the handle component (4) by means of the coupling unit (1).