Autoinjector Needle Cover Lock With Tangential Deflection Control
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Solution Overview
Problem
Existing autoinjector needle cover locking mechanisms are prone to faulty unlocking, particularly when the deflectable locking elements stick to the housing or if the cap is not correctly released, leading to potential unintentional activation.
Innovation Solution
A needle cover lock mechanism with a flexible locking member that deflects tangentially to the outer surface of the cover sleeve, using a stop surface and blocking surface interaction, ensuring reliable locking and unlocking by preventing deflection until the device cap is removed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If deflectable locking elements are used in the needle cover lock mechanism, then the locking and unlocking function is achieved, but the locking elements may stick to the housing or fail to unlock reliably, leading to potential unintentional activation
Solution Approach 1:
Instead of using deflectable locking elements that may stick or fail to unlock, the patent inverts the approach by using a blocking element that actively prevents unintended movement. The blocking element on the cover sleeve interacts with a blocking surface on the housing to prevent the cover sleeve from moving to the retracted position until the cap is removed, ensuring reliable locking without the sticking problems of deflectable elements.
Solution Approach 2:
The cap serves as an intermediary element that controls the blocking element. When the cap is attached, it maintains the blocking element in the blocked position, preventing accidental unlocking. When the cap is removed, the blocking element is released, allowing intentional unlocking. This intermediary mechanism ensures reliable operation by mediating between the locked and unlocked states.
2Object-affected harmful factors
If the needle cover is kept in the extended position for safety, then needle protection is maintained, but the autoinjector cannot be activated until the cap is removed
Solution Approach 1:
The blocking element is pre-positioned to prevent the cover sleeve from moving to the retracted position until the cap is removed. This preliminary blocking action ensures that the needle remains protected during storage and transport, while the removal of the cap serves as the preliminary action that enables intentional activation by releasing the blocking element.
3Reliability
If the blocking element prevents cover sleeve movement, then unintentional activation is prevented, but the mechanism complexity increases
Solution Approach 1:
The blocking function is extracted from a complex deflectable locking mechanism and implemented as a simple blocking element that interacts with a blocking surface. This extraction simplifies the overall mechanism by removing the need for complex deflectable elements while maintaining the reliability of preventing unintentional activation.
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
Ensures secure locking and reliable unlocking of the needle cover, preventing unintentional activation by allowing deflection only when the cap is removed, thus ensuring safe and controlled operation of the autoinjector.
Implementation Method 1
a flexible locking member that is deflectable in a plane tangent to an outer surface of the cover sleeve
Data Source
AI summary
A needle cover lock for an autoinjector includes a prefilled syringe with a needle. When a device cap is attached to the autoinjector, a deflection of a locking member of the autoinjector is prevented by a stop surface and by a blocking surface of the cap, and thereby the cover sleeve is prevented to exit an extended position. When the device cap with its blocking surface is removed from the autoinjector, the locking member is allowed to deflect, thereby allowing the needle cover sleeve to exit the extended position and to move towards a retracted position. The locking member is deflectable in a plane tangent to a circumferential outer surface of the cover sleeve when the device cap is removed.