Medicament Cap Assembly Locking Mechanism for Accidental Activation Prevention

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Solution Overview

Problem

Medicament delivery devices are prone to accidental activation of the power pack and medicament ejection due to external forces during transportation, leading to unintended retraction of the needle cover in the proximal direction.

Innovation Solution

A cap assembly for a medicament delivery device featuring a locking member with a flexible first engagement member that interacts with the needle cover and housing to limit its movement towards the inside of the housing, and a cap that engages the locking member to prevent accidental activation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the needle cover is made movable to activate the power pack, then the medicament injection function is enabled, but the device becomes susceptible to accidental activation during transportation

Engineering Contradiction:
Improveneedle cover movability for injection activationVSAvoidprotection against accidental activation
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent applies preliminary anti-action by introducing a cap assembly with a locking member that preemptively counteracts external forces before they can cause accidental needle cover retraction. The locking member engages with the needle cover and housing to prevent unintended movement, while still allowing user-initiated activation when needed.

Inventive Principle:
Principle #9Preliminary anti-action

Solution Approach 2:

The locking member serves as an intermediary element between the needle cover and the housing. It mediates the interaction by providing a controlled engagement mechanism that allows normal operation while blocking accidental activation forces during transportation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a locking mechanism is added to prevent accidental activation, then reliability against accidental activation is improved, but device complexity increases

Engineering Contradiction:
Improveprotection against accidental activationVSAvoidcap assembly with locking member
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking mechanism is designed with dynamic characteristics, allowing it to transition between locked and unlocked states. The flexible engagement member can deform elastically to engage or disengage from the needle cover, providing a simple yet effective locking action without complex mechanical structures.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The locking member incorporates a flexible first engagement member that utilizes elastic deformation to achieve locking and unlocking functions. This flexible element replaces complex rigid mechanical locking structures, reducing overall device complexity while maintaining reliability.

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 cap assembly effectively prevents accidental activation of the power pack by ensuring the needle cover can only be retracted by user-applied force, thus maintaining device integrity during transportation and use.

Implementation Method 1

a flexible first engagement member configured to interact with the needle cover and the housing to limit a movement of the needle cover toward an inside of the housing

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3893969B1Activation prevention cap assembly
Publication Date: 2025.05.28 SHL MEDICAL AG
  • EP3893969B1 patent drawingFigure 1
  • EP3893969B1 patent drawingFigure 2
  • EP3893969B1 patent drawingFigure 3

AI summary

A cap assembly for a medicament delivery device, wherein the medicament delivery device has a housing and a needle cover movable in relation to the housing. The cap assembly comprises a locking member and a cap. The locking member includes a flexible first engagement member configured to interact with the needle cover and the housing to limit a movement of the needle cover toward an inside of the housing. The cap is configured to engage the locking member and movably arranged in relation to the housing and the locking member between a first position in which the cap is engaged to the housing and a second position in which the cap disengages the housing.