Slidable Collar Needle Assembly for Injection Pen Safety
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Solution Overview
Problem
The existing needle assemblies for injection pens pose a risk of needle stick injury during the unthreading process due to the accessibility of the non-injection end of the needle, making it difficult to safely remove the used needle without rotational unthreading, which can lead to accidental exposure.
Innovation Solution
A needle assembly with a radially deformable sleeve and a sliding collar that allows axial separation from the pen boss without rotational unthreading, enhancing protection by moving the non-injection end deeper into the sleeve and providing a shield to cover the injection end after use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the needle assembly is removed by rotational unthreading from the pen boss, then the needle assembly can be detached from the injection pen, but the user is exposed to risk of needle stick injury due to accessibility of the non-injection end
Solution Approach 1:
The removal operation is segmented into two distinct actions: first, the collar is pulled axially to disengage the sleeve segments from the pen boss threads, and second, the needle assembly is pulled axially away from the pen. This segmentation eliminates the need for rotational unthreading and reduces needle exposure risk.
Solution Approach 2:
The collar acts as an intermediary component that the user grips to initiate the removal process. By pulling the collar axially, the user indirectly actuates the sleeve segments to disengage from the threads, providing a safer interface that keeps fingers away from the needle while still enabling removal.
2Reliability
If the sleeve segments are radially engaged with the pen boss threads for secure connection, then the needle assembly is firmly attached to the injection pen, but the non-injection end of the needle remains accessible and vulnerable during unthreading
Solution Approach 1:
The removal mechanism inverts the traditional unthreading approach. Instead of rotating the needle assembly to unscrew it, the collar is pulled axially in the opposite direction of engagement, which triggers the sleeve segments to radially disengage from the threads through the inclined plane mechanism, thereby inverting the removal action to be safer.
Solution Approach 2:
The sleeve segments are designed with radial deformability, allowing them to dynamically adjust their engagement state. During normal use, they are radially engaged for secure connection; during removal, axial force on the collar causes them to radially disengage, providing a dynamic transition between engaged and disengaged states.
3Strength
If a traditional threaded connection is used between the needle assembly and pen boss, then the connection is secure, but the removal process requires rotation that increases the risk of accidental needle exposure
Solution Approach 1:
The threaded connection is segmented into multiple interaction points: the collar, the sleeve segments with internal threads, and the pen boss external threads. This segmentation allows the connection to maintain strength through radial engagement while enabling safe removal through axial pulling of the collar, separating the engagement and disengagement functions.
Solution Approach 2:
The collar is extracted as a separate, user-interfacing component that mediates the removal process. By taking out the collar as a distinct element, the design allows users to grip and pull without直接接触 the needle, extracting the hazardous element from the user interaction path while maintaining connection strength through the sleeve-segment-to-boss-thread engagement.
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
Facilitates safe and easy removal of the needle assembly from the injection pen by eliminating the need for rotational unthreading, reducing the risk of needle stick injuries and providing enhanced protection for the non-injection end of the needle.
Implementation Method 1
the sleeve having a radially deformable end provided with at least one internal profile for radial interengagement with the threads of the pen boss such that with full radial inter-engagement the sleeve is securely connected to the injection pen
Data Source
AI summary
A needle assembly for an injection pen (22) has a sleeve (21) supporting internally a double-ended needle having an injection end and a non-injection end (25). The end of the sleeve surrounding the non-injection end (25) of the needle is divided into deformable segments (28) and is internally threaded for interengagement with a threaded boss (23) of the injection pen (22). A collar (29) is mounted on the sleeve (21) for sliding movement between a first position where the collar (29) overlies the segmented end and maintains interengagement of the threads at that end with those of the injection pen boss (23) and a second position where the segments may expand radially to come free of the injection pen boss (23). The needle may be mounted on a carrier (68) slidable with respect to the sleeve (21), the carrier (68) being coupled to the sleeve (21) for movement thereby.