Syringe Cap Sealing with Raised Thread Elements

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Solution Overview

Problem

Existing syringe caps with Luer-lock connectors fail to provide sufficient sealing and anti-unscrewing properties, leading to air leakage and contamination risks, especially during sterilization, and are difficult to assemble and costly to produce.

Innovation Solution

A syringe cap with a main body featuring raised elements on its external threading and a rubber component that compresses against the syringe tip, enhancing frictional contact and elastic reaction for improved sealing and anti-unscrewing, while facilitating easy assembly and reducing production costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a soft rubber portion is used to wrap around the frusto-conical tip for sealing, then sealing is provided, but the contact force is distributed over a large surface area resulting in insufficient sealing pressure and reduced anti-unscrewing effect

Engineering Contradiction:
Improvesealing effectivenessVSAvoidcontact pressure
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The patent introduces a hardened rubber coating layer on the inner surface of the cap that locally concentrates the sealing force on a specific portion of the frusto-conical tip, rather than distributing it over the entire surface. This localized hard surface provides both sealing effectiveness and sufficient contact pressure to prevent unintentional unscrewing during storage and thermal cycles

Inventive Principle:
Principle #3Local quality

2Reliability

If a hardened rubber coating is applied to the inner surface of the cap, then sealing and anti-unscrewing properties are improved, but manufacturing complexity and production cost increase

Engineering Contradiction:
Improvesealing and anti-unscrewing propertiesVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the physical-chemical parameters of the rubber material by applying a hardened coating layer, transforming it from a soft, compliant material to a hard, durable sealing surface. This parameter change enables the rubber to maintain its elastic sealing properties while providing the hardness needed for reliable anti-unscrewing protection during sterilization and storage

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If the cap structure is simplified to reduce production costs, then manufacturing becomes easier, but sealing reliability and anti-unscrewing protection during sterilization are compromised

Engineering Contradiction:
Improveproduction costVSAvoidsealing during sterilization
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent creates a composite structure by combining soft rubber material with a hardened coating layer. This composite approach integrates the cost-effective rubber base material with a thinner, hardened protective layer that provides enhanced sealing and anti-unscrewing properties during sterilization, achieving both economic and performance goals

Inventive Principle:
Principle #40Composite materials

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 cap ensures long-term air-tight and unintentional anti-unscrewing closure, preventing product deterioration and contamination, while simplifying assembly and reducing production costs.

Implementation Method 1

a rubber (20) housed within the axial cylindrical cavity (11) of the main body (10), having a surface (22) facing the aperture (11a) of the axial cavity (11) and designed to abut, in use, against a free end (4a) of a tip (4) of the syringe, in order to air-tightly close the free end (4a)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

raised elements (30) are formed, in the external threading (17) of the second coupling portion (15), at respective crests of the threads and are dimensioned so as to frictionally couple with a bottom (8) of respective threads of an internal threading (6) of the Luer-lock connector (5)

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4291270B1Cap for a syringe with luer-lock connector
Publication Date: 2024.12.11 PLATINUM PHARMA SERVICE SRLS
  • EP4291270B1 patent drawingFigure 1~2
  • EP4291270B1 patent drawingFigure 3~4
  • EP4291270B1 patent drawingFigure 5~6

AI summary

The invention relates to a cap (100) for a syringe (1) with Luer-lock connector (5) comprising: a main body (10) provided with a first handle portion (14) and a second portion (15) having an external threading (17) for coupling with a corresponding internal threading (6) of the Luer-lock connector (5) of the syringe (1), an axial cavity (11) having an aperture (11a) at the second coupling portion (15) being formed in the main body (10); and a rubber (20) housed in the axial cavity (11) of the main body (10). The rubber (20) has a surface (22) facing the aperture (11a) of the axial cavity (11) and designed to abut against an open free end (4a) of a tip (4) of the syringe (1) for air-tightly closing the open free end (4a) and raised elements (30) are formed at the external threading (17) of the second coupling portion (15).