Autoinjector Lock Ring Release for Button-Free Activation
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Solution Overview
Problem
Existing autoinjectors require additional manual operations for activation and are susceptible to material creep over long storage periods, which complicates the injection process and may lead to inadvertent activation.
Innovation Solution
An autoinjector design featuring a needle cover that moves to a retracted position, automatically unlocking a slidable lock ring to initiate the injection mechanism, and incorporates a resilient blocking member to prevent material creep, eliminating the need for manual button pressing and ensuring reliable activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a push button is used for releasing the plunger rod, then the injection mechanism can be activated, but the end user must perform an additional manual operation which complicates the injection process
Solution Approach 1:
The needle cover is designed to automatically push the lock ring to the unlocking position when it moves from the extended to retracted position during normal injection procedure. This self-service mechanism eliminates the need for a separate push button operation, as the needle cover's movement during insertion automatically triggers the plunger release mechanism.
Solution Approach 2:
The functions of the needle cover (shielding the needle and guiding insertion) are merged with the function of triggering the injection mechanism. By integrating the lock ring interaction with the needle cover's movement, the patent combines multiple functions into a single component, eliminating the need for a separate push button.
2Reliability
If the retainer is used to maintain the plunger rod in initial position, then the plunger rod is axially blocked, but the retainer may creep over time under the stress of the compressed spring
Solution Approach 1:
The lock ring serves as an intermediary component between the needle cover and the resilient blocking member. It provides a stable, axially movable interface that translates the needle cover's movement into lock ring displacement, which then releases the blocking member. This intermediary mechanism distributes forces more evenly and prevents direct stress concentration on the retainer, reducing creep risk during long-term storage.
Solution Approach 2:
The lock ring is designed to be axially movable, transitioning from a locking position (where it maintains the blocking member in place) to an unlocking position (where it releases the blocking member). This dynamic element allows the system to adapt to force variations over time while maintaining reliable retention during storage and enabling controlled release during activation.
3Ease of operation
If the lock ring is made slidable to enable automatic unlocking, then additional user operations are eliminated, but the risk of inadvertent activation may increase
Solution Approach 1:
The lock ring is designed with maintaining means that create preliminary resistance to axial movement in the normal operating position. This preliminary anti-action prevents inadvertent activation by requiring a deliberate, forceful movement of the needle cover during proper insertion to overcome the maintaining means and move the lock ring to the unlocking position.
Solution Approach 2:
The maintaining means are localized to specific positions of the lock ring, providing strong resistance to movement during storage and handling, but allowing controlled movement when the needle cover is properly inserted and pushed. This local differentiation of mechanical properties ensures safety during storage while enabling reliable activation during use.
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 autoinjector allows for easier and reliable activation without additional user operations, reducing the risk of inadvertent activation and minimizing material creep issues, thereby enhancing user safety and operational reliability.
Implementation Method 1
the retainer including a resilient blocking member radially deformable between a blocking position, in which the resilient blocking member axially abuts against a distal abutment surface of the plunger rod
Implementation Method 2
an initially compressed spring for moving the plunger in the distal direction
Data Source
AI summary
This autoinjector includes a housing extending along longitudinal axis A and configured to receive a medical container having a barrel defining a reservoir for containing a medical product, said barrel having a distal end provided with an injection needle and an opened proximal end configured to receive a plunger rod for pushing a stopper arranged inside the barrel. A needle cover is coupled to and axially movable with respect to said housing between a first extended position, a retracted position and a second extended position. A plunger rod is axially movable inside the housing between an initial position and an injection end position, the plunger rod being configured to push the stopper in order to expel the medical product when moving from the initial position to the injection end position. The autoinjector further includes biasing member for biasing the plunger rod in a distal direction towards the injection end position, and a retainer for maintaining the plunger rod in the initial position against the action of the biasing member, the retainer including a resilient blocking member radially deformable between a blocking position for blocking the plunger rod in the initial position, and a release position allowing for movement of the plunger rod in the distal direction. A lock ring is coupled to and axially movable with respect to the resilient blocking member, between a locking position for maintaining the resilient blocking member in the blocking position, and an unlocking position, axial movement of the lock ring from the locking to the unlocking position being caused by the needle cover moving from the first extended position to the retracted position.