Auto-Injector Interlock Mechanism for Compact Syringe Carrier Design
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Solution Overview
Problem
Existing auto-injection devices face issues such as potential syringe damage during needle insertion due to excessive force and increased width due to components extending rearward from the syringe carrier to the delivery driving assembly.
Innovation Solution
An auto-injection apparatus with an interlock mechanism between the syringe carrier and housing, allowing the actuation to be located forward of the syringe carrier, which prevents forward motion until released, reducing the need for components to extend rearward and minimizing the device's diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the actuation mechanism is positioned rearward from the syringe carrier, then the delivery driving assembly can be located at the rear, but the device width increases and components must extend rearward
Solution Approach 1:
The actuation mechanism is repositioned from a rearward location to a forward location relative to the syringe carrier, utilizing the forward spatial dimension. This dimensional repositioning allows the actuation mechanism to be integrated within or adjacent to the syringe carrier structure, eliminating the need for components to extend rearward and thereby reducing the overall device width while maintaining functional complexity.
2Force
If the insertion spring exerts great force during needle insertion, then needle penetration is achieved, but the syringe may be damaged when it bottoms out against the housing
Solution Approach 1:
A velocity regulator mechanism is incorporated that activates before the syringe reaches its bottomed-out position. This preliminary action gradually reduces the velocity of the syringe as it approaches the end of its travel, preventing sudden impact and potential damage to the syringe while still allowing the insertion spring to exert the necessary force for needle penetration throughout the insertion stroke.
3Reliability
If a velocity regulator is incorporated to limit syringe velocity, then syringe damage is prevented, but the device complexity increases
Solution Approach 1:
The velocity regulator function is merged with the existing actuation mechanism and syringe carrier structure. Rather than adding a completely separate velocity regulation system, the patent integrates velocity control features into the existing components, such as using the interaction between the actuation mechanism and syringe carrier to provide velocity limitation, thereby reducing overall device complexity while maintaining syringe protection functionality.
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 design mitigates syringe damage and reduces the device's width by allowing the actuation mechanism to be positioned forward, enhancing the safety and compactness of the auto-injection apparatus.
Implementation Method 1
The actuation mechanism may comprise a delivery actuator (for example a compression spring) which is held in an energised (or primed position) prior to release
Implementation Method 2
the initial static friction or 'stiction' between the bung and syringe resists forward movement of the piston relative to the syringe
Data Source
AI summary
Disclosed is an auto-injection apparatus for receiving a syringe, including: an outer casing enclosing a drive assembly and a syringe carrier configured to hold a barrel of the syringe, the syringe carrier being forward of the drive assembly and having stowed and delivery positions; an interlock extending between the syringe carrier and a syringe carrier housing at least partially surrounding the syringe carrier, the interlock preventing forward motion of the syringe carrier under the influence of an insertion actuator whilst in the stowed position. The drive assembly includes the insertion actuator for inserting a needle of the syringe into an injection site and a delivery actuator for driving a plunger into a barrel of the syringe which contains a substance for injection. The syringe carrier includes an interlock release mechanism which is configured to release the interlock such that the insertion actuator drives the syringe carrier forward.