Needle Shield Mechanism with Spring-Biased Locking for Auto-Injectors
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Solution Overview
Problem
Existing auto-injector needle shield mechanisms often fail to ensure user safety and needle protection, particularly when the device is accidentally lifted during dose administration, and may require excessive force due to spring-biased mechanisms.
Innovation Solution
A needle shield mechanism with a longitudinally elongated housing and a spring-biased, deflectable locking element that prevents accidental needle exposure by moving to a protected position when the device is lifted, using a container carrier assembly and intermediate drive member to control the needle shield's movement, ensuring safe and reliable operation without increased spring force as the injection progresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-biased needle protecting sleeve is used to provide automatic needle protection, then needle safety is improved, but the spring force increases during movement requiring excessive user force which is difficult for children or elderly people to handle
Solution Approach 1:
The needle shield mechanism transitions from a static spring-biased system to a dynamic system where the spring force is progressively released during the injection sequence. The flexible arms with retraction release rings allow the needle shield to remain protected during injection while automatically retracting when the injection is complete, eliminating the need for continuous user force to overcome increasing spring force.
Solution Approach 2:
The needle shield is pre-positioned in a protected state during the injection sequence through the flexible arms mechanism. The retraction release rings are pre-configured to disengage at the appropriate moment (when the plunger rod passes the outwardly directed protrusions), automatically initiating needle retraction without requiring the user to manually overcome spring force.
2Reliability
If the needle retraction is triggered only when the upper edge of the plunger rod passes the outwardly directed protrusions of the flexible arms, then the needle protection function is improved, but the user must handle an exposed and possibly contaminated needle until retraction is triggered
Solution Approach 1:
The needle shield is pre-positioned in a protected state during the injection sequence through the flexible arms mechanism. The retraction release rings are pre-configured to disengage at the appropriate moment (when the plunger rod passes the outwardly directed protrusions), automatically initiating needle retraction without requiring the user to manually overcome spring force.
Solution Approach 2:
The needle shield mechanism is self-regulating and automatically triggers retraction based on the injection sequence completion. The flexible arms and retraction release rings work together to automatically move the needle shield to the retracted position when the plunger rod passes the outwardly directed protrusions, eliminating the need for user intervention and preventing needle exposure.
3Adaptability or versatility
If a complex multi-function device with many interacting components is used to provide penetration, injection, and needle protection functions, then functionality is improved, but robustness and reliability become difficult to meet
Solution Approach 1:
The needle shield mechanism merges multiple functions (protection, retraction triggering, and sequencing) into an integrated system. The flexible arms simultaneously serve as structural support, retraction release mechanisms, and sequencing controls, reducing the number of separate interacting components while maintaining robustness and reliability.
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 mechanism effectively shields the needle and protects the user from accidental exposure, maintaining safety and reducing the force required for operation, while being cost-effective and reliable.
Implementation Method 1
a spring-biased container carrier assembly for accommodating a medicament container, wherein the container carrier assembly is movably arranged in the housing and is movable relative to the housing from an initial position to a penetrating position
Implementation Method 2
the container carrier assembly prevents the needle shield from moving to the extended position when the container carrier assembly is in the initial position, and wherein the container carrier assembly allows the needle shield to move to the extended position when the container carrier assembly is in the penetrating position
Data Source
AI summary
Needle shield mechanism for an auto-injector comprising, a tubular housing (10), a needle shield (12) movably arranged in the housing (10), between a retracted state and an extended position, a releasable spring-biased container carrier assembly movably arranged relative to the housing (10) from an initial position to a penetrating position, wherein the container carrier assembly prevents the needle shield (12) from moving to the extended position when the container carrier assembly is in the initial position, and wherein the container carrier assembly allows the needle shield (12) to move to the extended position when the container carrier assembly is in the penetrating position.