Injection Device Locking Mechanism Prevents Syringe Damage
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Solution Overview
Problem
Existing injection devices face issues with syringe ejection force requirements exceeding the restoring force of the return spring, leading to potential syringe damage and accidental activation, especially when used with sealed hypodermic syringes, and there is a risk of unintentional ejection and needle exposure.
Innovation Solution
The integration of a locking mechanism within the drive system prevents syringe carrier movement unless actuated, ensuring synchronized movement with the drive, and a flexible locking mechanism that allows the drive to be inserted while preventing unintended ejection, combined with a cap design to manage needle shields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the return spring is made strong enough to overcome the boot removal force, then the syringe can be retracted reliably, but the drive spring cannot do work on the syringe components during injection
Solution Approach 1:
The invention separates the locking function from the return spring function by introducing a dedicated locking mechanism with locking arms and locking surfaces. The return spring only needs to overcome friction and minor resistance, not the full boot removal force, while the locking mechanism handles the primary constraint of syringe movement.
Solution Approach 2:
The locking arms act as an intermediary mechanism between the syringe carrier and the drive assembly. They provide a mechanical interface that prevents syringe movement without requiring the return spring to generate excessive force, thereby resolving the force conflict between retraction and injection functions.
2Ease of operation
If the syringe is allowed to move freely out of the injection device, then boot removal is easy, but accidental activation and needle exposure risk increase
Solution Approach 1:
The locking mechanism transitions from a locked state during normal operation to an unlocked state during intentional activation. The locking arms can disengage from the locking surfaces when the drive assembly moves, allowing controlled syringe movement only during the intended injection sequence, not during accidental drops or handling.
Solution Approach 2:
The locking mechanism proactively prevents syringe movement before accidental activation can occur. By maintaining engagement between locking arms and locking surfaces, it counteracts unintended forces that might otherwise cause the syringe to move and the needle to be exposed.
3Reliability
If a separate independent locking mechanism is added to prevent syringe movement, then safety improves, but device complexity increases
Solution Approach 1:
The locking mechanism is merged with the drive assembly by integrating locking arms onto the syringe carrier and locking surfaces onto the drive components. This combination eliminates the need for a completely separate locking system, reducing overall device complexity while maintaining safety functionality.
Solution Approach 2:
The drive assembly serves multiple functions: it provides the driving force for injection, controls the timing of syringe movement, and incorporates the locking mechanism to prevent accidental activation. This multi-functionality reduces the need for separate dedicated components.
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
This solution prevents syringe damage, maintains sterility, and reduces the risk of accidental activation, ensuring controlled and safe operation of the injection device.
Implementation Method 1
These devices employ a drive spring and some form of release mechanism that releases the syringe from the influence of the drive spring
Implementation Method 2
to allow it to be retracted by a return spring
Implementation Method 3
The locking mechanism comprises at least one arm fixed relative the syringe carrier, wherein the arm is engageable with a corresponding locking surface on the drive
Data Source
Figure 1a~1c
Figure 2a
Figure 2b
AI summary
An injection device (110) comprises a locking mechanism (170) between a syringe carrier (127) and a drive mechanism (129) of the injection device. The drive is formed in such a^ way to inhibit movement of the syringe carrier (127) and syringe (114) held by the syringe carrier (127) towards an exit aperture (128) of the injection device when the drive is not itself being forced into a direction towards the exit aperture. This assists in preventing damage to the syringe prior to actuation of the injection device.