Safety Syringe Barrel Folded Ring Assembly Mechanism

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Solution Overview

Problem

Conventional safety syringes require precise embedment of snap members into snap slots for positioning, leading to longer installation times and higher manufacturing costs due to complex mold requirements for the needle hub, plunger, and barrel.

Innovation Solution

A safety syringe design featuring a barrel with a first folded ring and a second tube portion, allowing for easy assembly by snapping the plunger's plug into the needle hub to spread open a flexible portion, simplifying the manufacturing process and reducing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If snap members are precisely embedded into snap slots for positioning, then positioning accuracy is improved, but installation time increases and manufacturing cost increases

Engineering Contradiction:
Improvepositioning accuracyVSAvoidinstallation time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent changes the geometric parameters of the positioning structure by replacing precise snap-fit embeddings with a conical surface and flat surface contact mechanism. This parameter change allows for tolerant alignment while maintaining positioning accuracy, thereby reducing installation time without sacrificing positioning precision

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

Instead of using discrete snap members that require precise embedding, the patent inverts the approach by using continuous conical and flat surfaces for positioning. The conical surface of the needle hub contacts the flat surface of the barrel, creating a self-aligning mechanism that eliminates the need for precise snap-fit alignment

Inventive Principle:
Principle #13The other way round (Inversion)

2Manufacturing precision

If protruding columns are added to needle hub for snap member embedding, then positioning effect is improved, but device complexity increases and manufacturing cost increases

Engineering Contradiction:
Improvepositioning effectVSAvoidneedle hub complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts the protruding columns and snap members from the needle hub design. By removing these complex features, the needle hub becomes simpler in structure while the positioning function is maintained through the conical surface contact with the barrel's flat surface

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies local quality by creating a specific conical surface on the needle hub and a corresponding flat surface on the barrel. This localized geometric feature provides the necessary positioning effect without requiring complex protruding columns throughout the needle hub structure

Inventive Principle:
Principle #3Local quality

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

The design facilitates convenient installation and reduces manufacturing costs by eliminating the need for precise alignment and complex molds, resulting in a more efficient and cost-effective assembly process.

Implementation Method 1

a first folded ring flexibly formed on an inner side of the first tube portion and disposed around the axis, and after the first folded ring is unfolded, the first folded ring is bounded and extended from the first tube portion towards the second tube portion

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the plug of the plunger can be snapped into the needle hub to spread open the first flexible portion, so that the first flexible portion can be separated from the needle hub

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Data Source

PatentEP2589400B1Safety syringe
Publication Date: 2018.12.05 FAN
  • EP2589400B1 patent drawingFigure 1
  • EP2589400B1 patent drawingFigure 2
  • EP2589400B1 patent drawingFigure 3

AI summary

A safety syringe includes a barrel 2, a plunger 3, and a needle hub 4. The barrel 2 is extended axially and includes a first tube portion 21, a second tube portion 22 extended from an end of the first tube portion 21, and a first folded ring 23 flexibly branched and formed on an inner side of the first tube portion 21 and disposed around the axis, such that after the first folded ring 23 is unfolded, the first folded ring 23 is bounded and extended from the first tube portion 21 towards the second tube portion 22, and includes a first ring base portion 231 disposed at the first tube portion 21 and a first flexible portion 232 movably disposed opposite to the first ring base portion 231. The plunger 3 includes a rod 31 and a plug 32 installed at an end of the rod 31. The needle hub 4 is detachably installed in the second tube portion 22. The plunger 3 can be moved to an injecting position, a limit position, and a disposal position with respect to the needle hub 4.