Injection Needle Safety Device Ramp Mechanism
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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 increase the risk of needle stick injuries.
Innovation Solution
A safety device with a tubular body and a needle cover that includes a ramp portion on the bump, which decreases in slope towards the first end, reducing the activation force and its variability, along with chamfers and a locking ring to ease passage and secure the needle cover in the extended position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high activation force is used to move the needle cover from retracted to extended position, then the safety mechanism is reliably activated, but the ease of operation deteriorates and needle stick injuries increase
Solution Approach 1:
The ramp portion is designed with a varying slope that changes dynamically during the activation process. The slope transitions from steeper at the proximal end to shallower at the distal end, allowing the activation force to decrease progressively as the needle cover moves from retracted to extended position, thus maintaining reliable activation while improving ease of operation
Solution Approach 2:
The geometric parameter of the ramp portion (slope angle) is varied along its length to optimize the activation force profile. By changing the slope parameter from proximal to distal, the system achieves a gradual reduction in required activation force, resolving the contradiction between reliable activation and ease of operation
2Force
If a high and variable activation force is required, then the needle cover can be moved to extended position, but the variability increases the risk of needle stick injuries
Solution Approach 1:
The slope parameter of the ramp portion is systematically varied along its axial length, creating a gradient that transforms the activation force from high and variable to low and consistent. This parameter optimization ensures uniform activation force distribution throughout the needle cover movement cycle
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 bump has a first end and an opposite second end, and the proximal abutment surface of said bump has a ramp portion, said ramp portion having a decreasing slope towards the first end of said bump.