Medicament Delivery Sub-assembly Locking Mechanism
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Solution Overview
Problem
Existing medicament delivery devices, such as auto-injectors, require an additional operational step to remove a safety clip, which can lead to unintentional medicament release due to device shaking or dropping.
Innovation Solution
A sub-assembly for a medicament delivery device is designed with a radially flexible tab that holds the rear wall member in a lock position, eliminating the need for a safety clip. The release member, typically a needle cover, axially moves to contact the flexible tab, radially deflecting it and allowing the rear wall member to move to a release position, thereby releasing the plunger rod to expel the medicament.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety clip is used to prevent unintentional release of the plunger rod, then the reliability of the medicament delivery device is improved, but the device complexity increases and an additional operational step is required
Solution Approach 1:
The patent removes the safety clip component from the device by integrating its locking function into the rear wall member structure. The rear wall member's inner wall radially encloses the arm to provide the locking function, eliminating the need for a separate safety clip component while maintaining the prevention of unintentional plunger rod release.
Solution Approach 2:
The patent merges the locking function previously performed by a separate safety clip with the rear wall member structure. The rear wall member's inner wall encloses the arm to provide the locking mechanism, combining multiple functions into a single integrated component and reducing overall device complexity.
2Reliability
If a safety clip is used to prevent unintentional release of the plunger rod, then the reliability is improved, but the ease of operation deteriorates due to an additional operational step
Solution Approach 1:
The patent eliminates the operational step of removing a safety clip by integrating the locking function into the rear wall member. The rear wall member's inner wall radially encloses the arm to provide automatic locking, removing the need for users to perform an additional operational step while maintaining protection against unintentional release.
3Reliability
If the rear wall member radially encloses the arm to lock it, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The rear wall member serves multiple functions: it provides structural support for the housing, contains the spring mechanism, and incorporates the locking function through its inner wall enclosing the arm. This multi-functionality reduces the need for additional separate components, thereby reducing overall device complexity while maintaining locking reliability.
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 solution eliminates the need for a safety clip, simplifying the user interface and reducing the risk of accidental medicament release, while maintaining the reliability of the medicament delivery process.
Implementation Method 1
a radially flexible tab, an arm, and a release member; the release member is configured to be axially moved into contact with a radial protrusion of the flexible tab to radially deflect the flexible tab
Implementation Method 2
a plunger rod, a spring, a rear wall member; the plunger rod is configured to be moved by the spring inside the housing to expel a medicament of the medicament delivery device
Data Source
AI summary
The present disclosure relates to a sub-assembly of a medicament delivery device comprising a plunger rod configured to be moveable inside the medicament delivery device, a spring abutting the plunger rod in one end and abutting an inner wall of the sub-assembly in another end to compress the spring upon the plunger rod being moved towards a distal end of the medicament delivery device, an arm extending axially and being immovable with respect to a housing, the arm having a radially extending end section, an inner surface of which end section pressing radially against the spring-loaded plunger rod to axially fix the spring-loaded plunger rod relative to the arm, a rear wall member axially movable from a lock position where an inner wall of the rear wall member radially encloses an outer surface of the arm to a release position where the rear wall member is radially offset relative to the outer surface of arm, a radially flexible tab having an axially directed surface adjacent to a counter surface of an engagement member to form an axial abutment preventing the rear wall member from moving into the release position, and a release member configured to be axially moved into contact with a radial protrusion of the flexible tab to radially deflect the flexible tab, thereby radially offsetting the axially directed surface from the counter surface of the engagement member.