Auto-Injector Needle Cover Locking Mechanism
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Solution Overview
Problem
Existing auto-injectors lack effective needle protection mechanisms that prevent user exposure to needles both before and after use, and may impede device operation or result in improper medicament administration due to inadequate cover deployment and locking mechanisms.
Innovation Solution
An auto-injector design featuring a needle cover mechanism that is locked in place prior to activation and remains locked after use, with a spring-biased locking assembly and secondary locking arms to prevent needle retraction, ensuring user safety and proper medicament delivery without interfering with the injection process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a needle cover mechanism is added to protect users from needle exposure, then user safety is improved, but device complexity increases
Solution Approach 1:
The needle cover is nested within the cartridge holder sleeve, sliding along its outer periphery. The cover contains an opening that receives the needle, and the entire assembly is integrated into the auto-injector housing. This nesting approach provides comprehensive needle protection while minimizing the addition of external components.
Solution Approach 2:
The needle cover is pre-positioned in a retracted position within the housing before use, with the opening aligned to allow needle extension. The locking mechanism is pre-configured to automatically lock the cover in place after needle deployment, ensuring protection is immediately available without requiring user intervention.
2Reliability
If a locking mechanism is implemented to secure the needle cover, then reliability of needle protection is improved, but device complexity increases
Solution Approach 1:
The locking mechanism is self-actuating through spring-loaded latches that automatically engage with slots in the cartridge holder sleeve when the cover is positioned correctly. The springs provide continuous biasing force to maintain the locked state without requiring additional actuators or complex control systems.
Solution Approach 2:
Spring-loaded latches serve as intermediaries between the cover and the cartridge holder sleeve. These latches translate the positional state of the cover into a locked or unlocked state through mechanical engagement with slots, providing reliable locking while isolating the cover from direct contact with the needle mechanism.
3Manufacturing precision
If the cover is secured to prevent premature deployment, then medicament administration accuracy is improved, but ease of operation deteriorates
Solution Approach 1:
The locking latches are pre-positioned to engage with the slots in the cartridge holder sleeve, creating a mechanical barrier that prevents premature cover deployment. The spring bias ensures the latches remain engaged unless sufficient force is applied to overcome the spring resistance, thereby preventing accidental medicament administration.
Solution Approach 2:
The cover and locking mechanism are pre-configured during manufacturing with precisely positioned slots and latches. This preliminary configuration ensures that during operation, the cover can only be deployed when the needle has been properly extended and the medicament is ready for administration, maintaining accuracy while simplifying the user action required.
4Reliability
If multiple locking mechanisms are used to secure the cover, then reliability of needle protection is improved, but device complexity increases
Solution Approach 1:
The locking mechanism is segmented into multiple identical latches distributed around the periphery of the cover. Each latch independently engages with a corresponding slot in the cartridge holder sleeve, providing redundant locking action. This segmentation allows the system to achieve high reliability through multiple simple, identical components rather than a single complex locking mechanism.
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 solution provides reliable needle protection and ensures accurate medicament administration by preventing needle exposure and maintaining device functionality, enhancing user safety and operational reliability.
Implementation Method 1
a spring-biased locking assembly
Data Source
Figure 1
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Figure 4
AI summary
An auto-injector automatically dispenses a predetermined dose of medicament upon activation. The auto-injector includes a needle cover (150) operative to engage an injection site and activate the injector. The needle cover is configured to move from a locked retracted position prior to a medicament dispensing operation to a locked extended position after the medicament dispensing operation. The non-removable needle cover prevents contact with the needle both before and after the medicament dispensing operation. Additional safety features include color coding of some injector parts and labeling on the needle cover.