Medical Needle Cover Seal Arrangement
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Solution Overview
Problem
The manufacturing process for single-use syringes faces challenges with needle cover displacement ('pop-off') during sterilization and packaging due to pressure changes, compromising the sterile condition and requiring mechanical interlocks for secure attachment, which limits the internal dimensions of needle safety devices.
Innovation Solution
A medical needle cover arrangement featuring a syringe with a soft needle cover and a needle shield that forms a seal through complementary engaging surfaces, eliminating the need for mechanical interlocks and ensuring the cover remains attached during manufacturing, sterilization, and storage, with the shield blocking forward movement to prevent displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical interlocks (rib and flange) are used to secure the needle cover to the syringe hub, then the cover attachment reliability is improved, but the internal dimensions of the needle safety device are reduced
Solution Approach 1:
The patent removes the mechanical interlock structures (rib and flange) from the syringe hub and needle cover assembly. Instead of using these protruding mechanical features, the invention uses a sealing surface arrangement where the shield engages the cover to prevent displacement, thereby extracting the harmful mechanical interlocks while maintaining attachment reliability through a different mechanism.
2Reliability
If the needle cover is securely attached during manufacturing, then the sterile condition is maintained, but the cover becomes difficult to remove for injection preparation
Solution Approach 1:
The patent applies different functional qualities to different regions of the needle cover. The rear end of the cover has a sealing surface that engages with the shield to prevent displacement during manufacturing and storage. The forward end of the cover, however, is designed to be easily removable by the user during injection preparation, as the shield blocks forward movement only when in the correct position, allowing easy removal when needed.
3Stability of the object's composition
If venting is provided in the needle cover to prevent pop-off, then the attachment stability is improved, but the sterile condition of the needle may be compromised
Solution Approach 1:
The patent introduces the shield as an intermediary component between the needle cover and the syringe hub. The shield engages the cover to prevent displacement during manufacturing and storage, eliminating the need for venting holes in the cover. This intermediary mechanism maintains both attachment stability and sterile condition without requiring compromises.
Data Source
AI summary
A medical needle cover arrangement for a single-use syringe having a medical needle with a sharp tip, the needle being mounted on the syringe to project forwardly from a needle hub. A sleeve forming a part of a safety device is mounted on the syringe. The sleeve is arranged for axial movement with respect to the needle from an initial shielding position to a non-shielding position, the sleeve being blocked against forward movement with respect to the syringe from its initial shielding position. A soft needle cover overlies the needle with the sharp tip of the needle sealed by the cover. The rear end of the soft needle cover and the forward end of the syringe hub are profiled with complementary engaging surfaces. The cover has a step part-way between its ends, the step being engaged by an internal abutment at the forward end of the sleeve, to resist movement of the cover forwardly away from the syringe hub and so maintain a seal between the cover and hub. The part of the cover between the hub and the step may be subjected to compression to enhance the sealing effect.