Injection Needle Safety Device Axial Slots Reduce Activation Force
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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 needle cover that includes axial slots and bumps to reduce the activation force and its variability, allowing the needle cover to move smoothly from the retracted to the extended position with a lower force requirement, using chamfers and flexible design elements to ease the passage over the bumps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional active safety devices are used, then the needle cover can be moved from retracted to extended position, but the activation force required is high and variable
Solution Approach 1:
The patent modifies the physical parameters of the body by introducing axial slots that change the structural rigidity and flexibility characteristics. This allows the body to deform more easily during activation, reducing the force required to move the needle cover from retracted to extended position.
Solution Approach 2:
The patent transforms the static rigid body structure into a dynamic structure with controlled flexibility through the axial slots. The body can adapt its rigidity during operation, being rigid enough to maintain position but flexible enough to reduce activation force variability.
2Reliability
If high activation force is used, then inadvertent triggering is prevented, but user activation becomes difficult
Solution Approach 1:
The axial slots create a controlled flexibility parameter that allows the body to yield under intentional activation force while maintaining sufficient rigidity to prevent inadvertent triggering. The slots are positioned and dimensioned to provide this balanced response.
Solution Approach 2:
The bumps with chamfers create a curved engagement surface that provides progressive resistance during activation. The chamfered surfaces allow controlled deformation and force distribution, enabling reliable activation with reduced force variability.
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. The body has a first axial slot and a second axial slot, the first axial slot and the second axial slot extending on both sides of the bump.