Bi-Stable Clutch Plate for Secure Auto-Injector Reset

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Solution Overview

Problem

Existing auto-injectors lack a robust and user-friendly mechanism for securely holding the spring force during cartridge insertion and injection, leading to potential unintentional release and complicating the reset process.

Innovation Solution

The use of a bi-stable clutch plate with a flexible ring part and retention arms that engage with the housing surface to maintain a stable position during injection, preventing unintended release and facilitating easy cartridge installation and reset.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional clutch mechanism is used to hold spring force during injection, then the device can deliver medicament, but the mechanism is prone to unintentional release and lacks user-friendliness

Engineering Contradiction:
Improvesecure holding of spring forceVSAvoiduser-friendliness during cartridge installation and reset
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The clutch plate is designed as a bi-stable dynamic component that can switch between two stable positions (engaged and disengaged states). This dynamic特性 allows the mechanism to automatically maintain spring force during injection while enabling easy reset when triggered, resolving the contradiction between reliable force holding and ease of operation

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The clutch plate utilizes changes in its physical state (bending direction) to switch between functional modes. By changing the parameter of the plate's curvature through user actuation, the system transitions from a locked state (holding spring force) to an unlocked state (allowing reset), achieving both reliability and ease of operation

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If the clutch plate automatically switches between positions, then the mechanism is simple, but unintentional release occurs during use

Engineering Contradiction:
Improveclutch mechanism simplicityVSAvoidprevention of unintentional reset
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The bi-stable clutch plate is designed with inherent stability in both positions, creating a preliminary barrier against unintended switching. The plate requires a deliberate user actuation force to transition between states, preventing automatic or accidental changes while maintaining mechanical simplicity

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The clutch mechanism is designed to be self-locking in both stable positions without requiring additional locking components. The plate's own elastic properties provide the locking mechanism, eliminating the need for complex external locking systems while ensuring reliable prevention of unintentional release

Inventive Principle:
Principle #25Self-service

3Reliability

If the clutch plate occupies more space to provide stable positions, then the gripping capability is improved, but the auto injector compactness is reduced

Engineering Contradiction:
Improvegripping capability during injectionVSAvoidauto injector compactness
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The clutch plate is integrated within the existing housing structure, nesting the bi-stable mechanism within the available internal volume. The plate utilizes the housing's structural features as reference points for its stable positions, achieving reliable gripping capability without adding external bulk to the device

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The clutch plate is designed as a thin, flexible component that can bend between two stable positions. This thin-film approach allows the mechanism to occupy minimal space while providing sufficient structural integrity for reliable gripping during injection, maintaining device compactness

Inventive Principle:
Principle #30Flexible shells and thin films

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 bi-stable clutch plate ensures secure holding of spring force during injection, allowing for easy and safe cartridge installation, reuse, and reset, while preventing unintentional reset, thus enhancing user-friendliness and reliability.

Implementation Method 1

a bi-stable clutch plate comprising a flexible ring part from where one or more retention arms extend, the flexible ring part being movable between: a first stable position where the one or more retention arms protrudes outwardly and engages with an inside surface of the housing

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3941552B1Auto injector with bi-stable clutch plate
Publication Date: 2025.10.29 PHILLIPS MEDISIZE AS
  • EP3941552B1 patent drawingFigure 1A
  • EP3941552B1 patent drawingFigure 1B~1E
  • EP3941552B1 patent drawingFigure 2

AI summary

Disclosed herein is an auto injector with a bi-stable clutch plate.