Asymmetric Taper Injection Needle Assembly for Reduced Attachment Force
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Solution Overview
Problem
Existing drug injection devices require a significant force to securely attach the injection needle assembly to the drug discharge tube to prevent leakage, which can be challenging and may lead to drug leakage if the force is not adequately applied.
Innovation Solution
The injection needle assembly features a fitting portion with a female taper shape having a larger taper ratio than the drug discharge tube's male taper shape, allowing for a secure attachment with reduced force through increased friction resistance and a guide wall for easier insertion, along with a lock mechanism for enhanced security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same taper ratio is used for both the male taper shape (drug discharge tube) and female taper shape (fitting portion), then the attachment structure is simple and compatible with ISO standards, but a significant force is required to securely attach the injection needle assembly to prevent leakage
Solution Approach 1:
The patent changes the taper ratio parameter of the female taper shape (fitting portion) to be larger than that of the male taper shape (drug discharge tube). Specifically, the female taper ratio is set to 8% while the male taper ratio remains at 6%, creating a parameter difference that enables secure attachment with reduced force while maintaining ISO compatibility
Solution Approach 2:
The patent introduces asymmetry in the taper ratios between the male and female connection parts. Instead of using identical taper ratios as in conventional ISO fittings, the female taper is made steeper (larger ratio) than the male taper, creating an asymmetric relationship that improves attachment security and reduces required force
2Force
If a larger taper ratio is used for the female taper shape, then the attachment can be secured with weaker force, but the manufacturing precision requirement increases
Solution Approach 1:
The patent specifies concrete parameter ranges to balance manufacturing feasibility with performance: the female taper ratio is set between 7-9% (preferably 8%) while the male taper ratio remains at 6%. These parameter specifications provide clear manufacturing targets that achieve the force reduction goal while maintaining practical manufacturability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables a reliable and leak-proof attachment of the injection needle assembly to the drug discharge tube using a weaker force, ensuring effective drug delivery without leakage, while maintaining compatibility with standard syringe designs.
Implementation Method 1
tapered surfaces rub against each other and are firmly fitted to each other, whereby they are liquid-tightly fixed to each other
Data Source
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AI summary
The present invention aims to provide an injection needle assembly that reduces force required for an attachment between the injection needle assembly and a drug discharge tube, and that can surely be attached even with weak force without causing a liquid leakage. An injection needle assembly 2 includes: an injection needle 11; a fitting portion 12 which is formed into a cylindrical shape and has one end serving as a fitting opening, the fitting portion having a female taper shape in which an inner diameter of a cylinder hole of the fitting portion becomes smaller toward the inner side from the fitting opening; and a hub 13 provided with the fitting portion 12 for holding the injection needle 11, the injection needle assembly 2 being used in such a manner that the female taper shape of the fitting portion 12 is fitted to a drug discharge tube 22, which has a male taper shape in which an outer diameter of a cylinder becomes smaller toward a tip, from the fitting opening, wherein when the male taper shape of the drug discharge tube 22 has a taper ratio of N/100, the female taper shape of the fitting portion 12 is formed to have a taper ratio of M/100, wherein M > N.