Fixed Claw Protective Cover for Syringe Cap Retention
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Solution Overview
Problem
Existing needle-protecting cap protective devices experience a decrease in retaining force over time due to material creep, particularly in plastics, leading to a risk of the protective cover being removed without the cap, which can stay on the needle.
Innovation Solution
A protective device with fixed claws arranged around a longitudinal axis, optimized with four claws and a specific diameter and angle distribution, that grip the needle-protecting cap without requiring excessive force for fitting or removal, reducing creep and enhancing the retention force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If tilting claws with articulation are used to hold the needle-protecting cap, then the cover can be fitted without pushing away the cap, but the retaining force decreases over time due to material creep
Solution Approach 1:
The claw is divided into two functional zones: a fixed base portion attached to the cover and a movable gripping portion that engages the cap. This segmentation allows the base to remain stationary (avoiding creep) while the gripping portion performs the holding function
Solution Approach 2:
Instead of making the entire claw articulated as in prior art, the invention inverts the approach by making the claw fixed and using a different mechanism (the sharp point penetrating the cap material) to achieve the gripping function without articulation
2Reliability
If fixed claws are used instead of articulated claws, then material creep is reduced, but stronger force is required for removing the cover with the cap
Solution Approach 1:
The claw concentrates its gripping action at a specific local point (the sharp point) rather than distributing force along an articulated structure. This localized quality allows the fixed claw to achieve effective gripping with reduced overall force requirements
Solution Approach 2:
The invention changes the geometric parameters of the claw, specifically creating a sharp point with a small radius of curvature. This parameter change enables the fixed claw to penetrate and grip the cap material effectively, reducing the force needed for cover removal
3Manufacturing precision
If the claw point is sharp with small radius of curvature, then the cap material is better penetrated, but the claw requires stronger strength to maintain the point shape
Solution Approach 1:
The claw has different structural qualities at different locations: a sharp point with small radius for penetration and a broader base with larger cross-section for structural strength. This local quality variation resolves the contradiction between penetration capability and structural strength
Data Source
Figure 1~2
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Figure 6~8
AI summary
The invention concerns a protective device (10) comprising a protective cover (12) intended to be gripped on a needle-protecting cap (8) of a syringe (2), said protective device having an internal surface (13) and comprising claws (20) protruding from this internal surface, said claws having a free end in the form of a point (22) arranged so as to stick into the needle-protecting cap (8), wherein the claws are integral with the protective cover and fixed in respect of said internal surface.