Injection Needle Safety Device Chamfered Abutment
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Solution Overview
Problem
Active safety devices for injection devices require a high and variable activation force to move the needle cover from the retracted to the extended position, which can be inconvenient and risky for users.
Innovation Solution
A safety device with a tubular body and a needle cover that includes a distal abutment surface and a bump with chamfers, allowing for a reduced activation force and variability by providing surface contact instead of line contact, and featuring a retainer to transmit the activation force, with design elements like reduced thickness portions and axial grooves to facilitate easier deformation and stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional active safety device uses point contact between the needle cover and the body, then the activation force is high, but this makes it difficult for users to activate and increases variability
Solution Approach 1:
The patent transitions from point contact (0D/1D) to surface contact (2D) between the needle cover's distal abutment surface and the body's proximal abutment surface. This dimensional change distributes the activation force over a larger area, reducing peak force requirements and making activation easier for users while decreasing variability.
Solution Approach 2:
The patent modifies the geometric parameters of the contact interface by introducing chamfers on both the distal abutment surface and the proximal abutment surface. These chamfered surfaces create a tapered contact geometry that facilitates smoother transition and reduces the force needed to overcome static friction and initiate movement.
2Ease of operation
If the activation force is reduced to make activation easier, then ease of operation improves, but reliability may decrease due to potential inadvertent triggering
Solution Approach 1:
The release element is pre-loaded in a compressed state during assembly, storing elastic potential energy. This preliminary action ensures that once activation begins, the stored energy provides a controlled, consistent force to complete the needle cover movement, preventing partial or inadvertent activation while maintaining ease of deliberate activation.
Solution Approach 2:
The release element acts as an intermediary mechanism between the user's activation force and the needle cover movement. It translates the user's input force into a controlled, reliable activation sequence, ensuring that the activation force remains below inadvertent triggering thresholds while still enabling deliberate activation.
Data Source
AI summary
The safety device includes a tubular body extending along a longitudinal axis. The tubular body is configured to receive the medical container, a needle cover movable relative to said body between a retracted position, and an extended position in which the needle cover distally extends from the retracted position in order to shield the injection needle after activation of the safety device, a release element configured to move the needle cover from the retracted to the extended position after activation of the safety device, and a retainer for maintaining the release element in a compressed condition when the needle cover is in the retracted position. The retainer is configured to transmit a user's activation force to the needle cover once the injection operation is completed. The needle cover includes a distal abutment surface, said distal abutment surface abutting against a proximal abutment surface of a bump protruding from the body in the retracted position of the needle cover. At least one of the proximal abutment surface and the distal abutment surface includes a chamfer configured to ease passage of the needle cover over the bump of the body when the needle cover moves distally to the extended position.