Tethered Plastic Cap Torsion-Bar Structure for Stable Open Retention

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Solution Overview

Problem

Existing plastic caps for bottles lack stability and ease of use, particularly in maintaining a secure open position, and do not comply with environmental regulations requiring caps to remain attached to containers throughout their use.

Innovation Solution

A cap design featuring a retaining ring and tethers that anchor to the container neck, with tethers acting as torsion bars to maintain the cap in an open position, and a fixator with a tongue for enhanced stability and ease of use, manufactured through injection molding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional cap with tear line and security ring is used, then the cap can be opened and closed, but the cap becomes loose and detached during use, violating environmental regulations

Engineering Contradiction:
Improvecap attachment reliabilityVSAvoidcap opening and closing ease
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The cap is divided into two functional parts: a removable closing element for opening/closing operations and a retaining ring that remains attached to the container. The separation line allows the closing element to be removed while the retaining ring with tether remains anchored, solving the contradiction between ease of operation and attachment reliability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The tether acts as an intermediary element connecting the closing element to the retaining ring. This tether with breakable bridges allows controlled separation while maintaining connection, enabling easy cap opening while preventing complete detachment and ensuring regulatory compliance.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If the fixator is made long enough to ensure stable fixation in open position, then the fixation stability improves, but the fixator deforms and breaks under substantial load during cap opening

Engineering Contradiction:
Improvefixation stability in open positionVSAvoidfixator strength during opening
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The fixator is positioned on the container neck rather than extending vertically downward, changing its spatial orientation. This dimensional repositioning allows the fixator to engage with the neck structure more effectively, providing stable fixation without requiring excessive length that would cause deformation during opening.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The fixator is pre-positioned on the container neck before cap opening, establishing a stable anchor point. This preliminary positioning ensures the fixator is ready to maintain open position stability without bearing excessive loads during the opening process itself.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If multiple tethers and tethering areas are added to improve cap retention, then the attachment reliability improves, but the device complexity increases

Engineering Contradiction:
Improvecap retention reliabilityVSAvoidcap structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The tether serves multiple functions: it connects the closing element to the retaining ring, provides controlled separation through breakable bridges, and maintains connection during use. This multi-functionality reduces the need for additional separate components, maintaining reliability while controlling complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The tether integrates the closing element and retaining ring into a single functional assembly. By merging these components through the tether connection, the design achieves reliable retention without requiring multiple separate attachment mechanisms, thus controlling overall structural complexity.

Inventive Principle:
Principle #5Merging (Combining)

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 ensures stable and secure attachment of the cap in the open position, enhancing user convenience and compliance with environmental regulations, while allowing easy removal and reattachment, suitable for mass production without additional finishing steps.

Implementation Method 1

tethers acting as torsion bars to maintain the cap in an open position

Methodology Applied
Scientific EffectTorsion: Torsion Spring

Implementation Method 2

tethers acting as torsion bars to maintain the cap in an open position

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 3

manufactured through injection molding

Methodology Applied
Scientific EffectInjection molding:

Data Source

PatentEP4650296A1A plastic tethered cap for a container and production method
Publication Date: 2025.11.19 UAB PLASTIKSE
  • EP4650296A1 patent drawingFigure 1~2
  • EP4650296A1 patent drawingFigure 3~4
  • EP4650296A1 patent drawingFigure 5~6

AI summary

The invention introduces a plastic container cap featuring a cylindrical cap base, a retention ring connected by a rupture bridge, and a fixator. The tethers, incorporating rupture lines at their bottoms, enable the cap's detachment while remaining linked to the retention ring. Upon full opening, the tethers function as a torsion bar, allowing the fixator to exert force, ensuring stable retention in the open position. A key innovation is the fixator's tongue with curved rupture line according to the shape of the tongue. This unique design not only facilitates easy cap opening and closing on a container by reducing resistance but also ensures stable locking after the container is opened.