Syringe Carrier Locking Mechanism for Injection Device
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Solution Overview
Problem
Existing injection devices face issues with maintaining syringe sterility and preventing accidental activation, particularly when using sealed hypodermic syringes, as the return spring's restoring force is insufficient to overcome the drive spring's force, leading to syringe ejection and potential needle damage or exposure.
Innovation Solution
A locking mechanism is implemented that secures the syringe carrier and syringe in place until the device is actuated, using a dual-port syringe lock protrusion that engages and disengages based on the release mechanism's position, preventing movement and accidental activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the return spring is made stronger to prevent syringe ejection, then the syringe can be retained in place, but the drive spring cannot effectively extend the syringe during injection
Solution Approach 1:
The patent divides the spring system into two distinct functional springs: a drive spring for extending the syringe and a return spring for retracting it. The locking mechanism segments the operational phases, allowing each spring to operate effectively in its designated phase without conflicting force requirements.
Solution Approach 2:
The locking mechanism is engaged in advance before injection to secure the syringe in the retracted position. This preliminary locking allows the drive spring to be pre-loaded and ensures the syringe remains stationary until the locking mechanism is deliberately disengaged, preventing premature ejection.
2Ease of operation
If the syringe is made moveable to allow boot removal, then the boot can be easily removed, but the syringe may be accidentally ejected or damaged
Solution Approach 1:
The locking mechanism transitions between locked and unlocked states based on operational needs. During boot removal, the mechanism remains locked to prevent accidental ejection. During intentional activation, the mechanism unlocks to allow syringe extension, providing dynamic control over syringe mobility.
Solution Approach 2:
The locking mechanism acts as an intermediary between the boot removal action and syringe movement. It mediates by remaining engaged during boot removal to prevent accidental ejection, and only disengaging when deliberately activated to allow controlled syringe extension.
3Reliability
If the locking mechanism is added to prevent accidental activation, then safety is improved, but the device complexity increases
Solution Approach 1:
The locking mechanism is merged with the existing trigger assembly and syringe carrier structure. The trigger serves dual functions: initiating injection and controlling the locking mechanism. This integration adds safety functionality without requiring a completely separate locking system.
Solution Approach 2:
The trigger mechanism serves multiple functions: it activates the drive spring for injection, controls the locking mechanism to prevent accidental activation, and maintains syringe retention. This multi-functionality reduces the need for additional separate 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 effectively maintains syringe sterility and prevents accidental ejection, ensuring safe handling and reliable operation by locking the syringe until intentional activation, reducing the risk of needle exposure and damage.
Implementation Method 1
a return spring (126) that is biased to move the syringe from its extended position to its retracted position
Implementation Method 2
a drive spring (130) which is biased to extend the syringe from its retracted position to its extended position
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
An injection device comprises a locking mechanism (171c) between a syringe carrier (127) and a release mechanism (102) to inhibit movement of the syringe carrier and syringe held by the syringe carrier towards an exit aperture of the injection device when the release mechanism is in its engaged position. The engaged position of the release mechanism is a position in which engagement of an actuator on the syringe is prevented. This assists in preventing damage to the syringe prior to actuation of the injection device.