Latchable Inner Cartridge Design for Refillable Applicator Units

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing cosmetic application units, such as mascara containers, are not sustainable due to the disposal of the entire unit when the mass is used up, which is inconvenient and costly, and refilling or replacing the container is cumbersome and risks contamination or unauthorized products.

Innovation Solution

A modular design with a latching device that allows easy separation and replacement of the inner container part, which holds the mass, from a reusable outer container part, without the need for tools, using a latching element that protrudes into the outer container part and engages with a counter latching element on the inner part.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the entire application unit is disposed of when the mass is used up, then the user obtains a new complete unit, but this leads to increased waste and higher costs

Engineering Contradiction:
Improveproduct functionalityVSAvoidwaste
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The application unit is divided into separable components: a reusable outer unit (container with applicator) and a replaceable inner container (cartridge). This segmentation allows the inner container to be exchanged when empty while the outer unit remains in use, reducing waste and enabling sustainable reuse of the applicator and outer container structure.

Inventive Principle:
Principle #1Segmentation

2Loss of substance

If manual refilling of the mass container is attempted, then the user can reuse the container, but this requires additional aids and risks contamination or use of unauthorized products

Engineering Contradiction:
Improvewaste reductionVSAvoidrefilling convenience
Core Design Contradiction:
Loss of substanceVSEase of operation

Solution Approach 1:

The inner container is pre-filled with mass at the factory in a sealed state. The user simply needs to remove the exhausted inner container and insert a new pre-filled one, eliminating the need for manual refilling operations while ensuring product authenticity and preventing contamination.

Inventive Principle:
Principle #10Preliminary action

3Device complexity

If the mass container is designed as one piece, then the structure is simple, but replacement becomes cumbersome and requires disposal of functional parts

Engineering Contradiction:
Improvecontainer structureVSAvoidreplacement ease
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The container is segmented into an outer container and an inner container that can be independently removed and replaced. The latching device provides simple connection and separation mechanisms that maintain structural integrity during use while enabling easy replacement when the inner container is empty.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The latching device is localized at specific positions on the inner container (opening end and/or bottom), providing targeted connection points without complicating the overall simple cylindrical structure. This allows easy separation at the latching points while maintaining the simplicity of the main container bodies.

Inventive Principle:
Principle #3Local quality

4Adaptability or versatility

If a latching device is added to enable inner container replacement, then sustainability is improved, but the device complexity increases

Engineering Contradiction:
Improvereplacement capabilityVSAvoidlatching mechanism
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The latching device is designed to be automatically engaged when the inner container is inserted into the outer container, and can be easily released by simple pulling or twisting motions. The latching elements (protrusions and recesses) self-align and lock into place without requiring tools or complex operations, maintaining ease of use while enabling secure replacement capability.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4085791B1Application unit with at least one latching device
Publication Date: 2026.02.18 GEKA
  • EP4085791B1 patent drawingFigure 1~2
  • EP4085791B1 patent drawingFigure 3~4
  • EP4085791B1 patent drawingFigure 5

AI summary

The invention relates to an application unit (1) with a mass container (2) for storing mass to be applied, which comprises a cap (3) carrying an applicator (18), by means of which the mass container (2) can be opened and preferably closed again, with at least one inner container part (4) and at least one outer container part (5) accommodating the latter completely or partially, wherein the respective outer container part (5) is closed at its one end face by a continuous end surface (6) and is open at its opposite end face, wherein a latching device (8) is provided by means of which the respective inner container part (4) is latched to the outer container part (5) in a form-fitting manner, characterized in that the latching device (8) has a latching element carrier (9) which is firmly connected on the inside to the said continuous end face (6) of the outer container part (5) by gluing or welding and from which a latching element (10) protrudes into the interior of the respective outer container part (5).