Autoinjector Needle-Shield Cap With Anti-Creep Plug
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Solution Overview
Problem
Existing autoinjector designs face issues with the creep effect of clamping means for needle shields, leading to unreliable engagement during removal, and require a time-consuming push-back step that is confusing for non-skilled users.
Innovation Solution
A cap design with a tubular body, inner sleeve, and a movable plug that pushes the needle shield back in the proximal direction, ensuring the clamping means return to their rest position, preventing creep and enabling reliable engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clamping means are deflected by the syringe barrel during insertion, then the needle shield is secured in place, but the clamping means may creep over time and fail to properly engage the needle shield during removal
Solution Approach 1:
The plug applies a preliminary pushing force in the proximal direction to counteract the deflection of the clamping means caused by syringe barrel insertion. This preliminary anti-action prevents the clamping means from creeping over time and ensures they remain in the correct position for reliable engagement with the needle shield during removal.
2Reliability
If a machine-operated push-back step is used to return the clamping means to rest position, then engagement reliability is improved, but assembly time increases
Solution Approach 1:
The plug is designed to automatically push the clamping means back to their rest position through its own structural configuration. When the syringe barrel is inserted, the plug's geometry causes it to move in the proximal direction, self-service returning the clamping means to engagement-ready position without requiring external machine intervention or additional assembly steps.
3Ease of operation
If the central hole of the cap is used for machine engagement, then the push-back operation is enabled, but the needle shield becomes visible to the end user causing confusion
Solution Approach 1:
The invention extracts the machine engagement interface from the cap body and relocates it to the plug component. The plug contains the engagement protrusion that interfaces with the machine, while the cap's distal opening remains closed or obscured. This separation allows the push-back operation to be enabled through the plug without exposing the needle shield through the cap, eliminating user confusion.
Data Source
AI summary
The cap includes a tubular body extending along a longitudinal axis A. The tubular body has a distal end and an opposite proximal end for attachment to a bottom housing of an autoinjector. An inner sleeve proximally extends inside the tubular body from said distal end, the inner sleeve defining an inner cavity for receiving the needle shield. The cap has clamping means for clamping the needle shield when the needle shield is inserted inside the inner cavity, the clamping means including an axial abutment surface for abutting against a proximal end of the needle shield, and a plug at least partially extending inside the inner cavity, the plug having a distal end portion, a proximal end portion and an intermediate portion extending between the distal end portion and the proximal end portion. At least the proximal end portion of the plug is movable between a first position, in which the proximal end portion allows the proximal end of the needle shield to distally pass the axial abutment surface of the clamping means, and a second position, in which the proximal end portion of the plug moves in the proximal direction to push the needle shield back towards the axial abutment surface.