Syringe Plunger Stopper Cavity for Aligned Vent-Tube Stoppering

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Solution Overview

Problem

Existing stopper designs in syringes fail to maintain consistent alignment and isostatism during manufacturing and vent tube stoppering, leading to manufacturing defects and improper sealing with the syringe barrel.

Innovation Solution

A stopper design with a dual-purpose cavity featuring a threaded and rear cavity portion that provides multiple contact points with tools, ensuring alignment and isostatism during post-molding treatment and vent tube stoppering, using a plunger rod with a threaded extension member for secure attachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a simple cavity is used in the stopper, then the manufacturing process is simple, but the alignment and isostatism of the stopper cannot be maintained during manufacturing and vent tube stoppering

Engineering Contradiction:

Improvealignment and isostatism of stopperVSAvoidcavity structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The cavity is segmented into two distinct portions: a threaded cavity portion for receiving the plunger rod and a rear cavity portion for receiving tools during manufacturing and stoppering. This segmentation allows each portion to serve its specific function optimally, with the rear cavity portion providing alignment and isostatism while the threaded portion provides secure attachment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The rear cavity portion serves multiple functions: it maintains alignment during post-molding surface treatment, maintains isostatism during vent tube stoppering, and provides a reference for tool positioning. This multi-functionality resolves the contradiction by making the cavity structure more capable without proportionally increasing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Manufacturing precision

If a stabilizing tool is inserted into the cavity for surface treatment, then alignment is maintained during treatment, but the cavity structure must accommodate the tool which complicates the design

Engineering Contradiction:

Improvealignment during surface treatmentVSAvoidcavity structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The cavity is divided so that the rear cavity portion specifically accommodates the stabilizing tool during surface treatment. This dedicated space allows the tool to be inserted and maintained in position without interfering with other stopper features, providing alignment during treatment while keeping the overall design manageable through clear functional zones.

Inventive Principle:

Principle #1Segmentation

3Manufacturing precision

If an installation rod is advanced into the cavity for vent tube stoppering, then the stopper can be pushed into the syringe barrel, but maintaining consistent alignment and isostatism is difficult with existing cavity designs

Engineering Contradiction:

Improveisostatism during stopperingVSAvoidcavity structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The rear cavity portion is specifically designed to receive the installation rod during vent tube stoppering. This segmented structure provides a dedicated receptacle that maintains isostatism as the rod advances, ensuring the stopper is pushed consistently into the syringe barrel without tilting or misalignment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The rear cavity portion acts as an intermediary between the installation rod and the stopper body, transmitting the pushing force while maintaining alignment. This intermediary structure ensures that the force is applied centrally and consistently, resolving the isostatism issue during stoppering.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Manufacturing precision

If the cavity is shallow, then the stopper structure is simpler, but it cannot adequately retain tools or maintain alignment during processing

Engineering Contradiction:

Improvetool retention and alignmentVSAvoidcavity depth

Core Design Contradiction:

Manufacturing precisionVSLength of moving object

Solution Approach 1:

The cavity depth is optimized through segmentation into a threaded cavity portion and a rear cavity portion. The rear cavity portion has sufficient depth to adequately retain tools and maintain alignment during processing, while the overall cavity length is managed by having the threaded portion extend toward the plunger rod attachment point, distributing the functional requirements along the cavity length.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentEP4628125A1Syringe plunger stopper with guidance-enabling internal cavity

Publication Date: 2025.10.08 BECTON DICKINSON & CO

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AI summary

Provided herein is a stopper including a main body portion defining an open proximal end and a closed distal end, a plurality of ribs each extending from an outer surface of the main body portion and around an outer circumference of the main body portion, and a cavity formed within the main body, with the cavity extending from the open proximal end distally into the main body. The cavity comprises a threaded cavity portion defined by a threaded inner surface of the main body portion and a rear cavity portion positioned distally from the threaded cavity portion and opposite the open proximal end of the main body portion. The rear cavity portion has a depth of 0.5 mm or greater, such that the rear cavity portion is configured to receive and retain tools therein used for post-manufacturing processing of the stopper and positioning of the stopper within the syringe barrel.