Injection Device Locking Sleeve for Needle-Shield Dose Confirmation
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Solution Overview
Problem
Existing automatic injection devices with moveable needle shields can produce an audible sound during priming that is misinterpreted as medicament delivery, leading to users removing the device without completing the dose.
Innovation Solution
An injection device with a locking mechanism that prevents the needle shield from moving to the exposing position until medicament delivery is confirmed, using a locking sleeve and biasing means to ensure the needle remains covered until the dose is completed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a moveable needle shield is used to cover the needle, then the risk of needle injury is reduced, but an audible sound during priming may be misinterpreted as medicament delivery, leading to premature device removal
Solution Approach 1:
The locking mechanism is pre-configured to automatically engage when the needle shield moves to the exposing position, preventing premature disengagement. The shunt arms are positioned to be engaged by the plunger rod only after the needle shield has been properly exposed, ensuring the lock cannot be released before medicament delivery begins.
Solution Approach 2:
The shunt arms act as an intermediary component between the plunger rod and the locking sleeve. They transfer the mechanical motion from the plunger rod to the locking sleeve, controlling when the lock engages and disengages based on the needle shield's position and plunger rod's movement.
2Reliability
If a locking mechanism is added to prevent premature needle shield movement, then dose delivery completion is ensured, but device complexity increases
Solution Approach 1:
The locking mechanism is merged with the existing needle shield and plunger rod components. The shunt arms are integrated into the needle shield assembly, and the locking sleeve is positioned to interact with existing structural elements, reducing the need for separate, additional components.
Solution Approach 2:
The locking mechanism operates automatically based on the mechanical interactions between existing components. The shunt arms are engaged by the plunger rod's movement and automatically control the locking sleeve's engagement and disengagement, eliminating the need for separate control systems or additional user actions.
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
Prevents premature removal of the device by ensuring the needle shield remains locked until the dose is delivered, providing a clear audible and tactile indication of medicament delivery.
Implementation Method 1
a biasing means for biasing the needle shield axially forwardly toward the needle covering position
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
An injection device comprising an outer housing configured to receive a syringe, the syringe having a barrel for containing medicament, a stopper that is axially moveable in the barrel, and a needle in fluid communication with the barrel. A plunger rod is axially moveable within the outer housing and configured for axially moving the stopper of the syringe when received in the outer housing. A needle shield is axially moveable relative to the outer housing between a needle covering position and a needle exposing position to selectively provide a needle enclosure, the needle exposing position being axially rearward of the needle covering position. A biasing means for biasing the needle shield axially forwardly toward the needle covering position is provided. A locking member is axially moveable in the outer housing from a first axial position to a second axial position in response to forward axial movement of the plunger rod. A locking sleeve is axially movable relative to the outer housing between a non-locking position and a locking position, the locking position being axially rearward of the non-locking position, in which axial movement of the locking sleeve is selectively limited by the locking member when in the second axial position. In a first configuration the needle shield is in the needle covering position and the locking sleeve is in the non-locking position so that at least a portion of the needle shield is axially slideable within the locking sleeve to permit rearward axial movement of the needle shield from the needle covering position to the needle exposing position. In a subsequent configuration the needle shield is in the needle covering position and the locking sleeve is in the locking position so that the needle shield is prevented from moving axially rearwardly by interference with the locking sleeve.