Self-Closing Cable Bushing for Gas-Tight Line Sealing

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Solution Overview

Problem

Existing cable bushings fail to reliably close the passage through the hose body, allowing gas leakage due to user error, especially after cables have been passed through.

Innovation Solution

A cable bushing design featuring a cladding tube, a fastening element, and a flexible hose body with a spring device that ensures the hose body automatically closes, preventing gas passage, and can be manually opened for cable insertion, using a torsion or tension spring and sealing elements to maintain tightness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the hose body is made rotatable to allow cable insertion, then the ease of operation is improved, but the reliability of sealing deteriorates due to potential user error leaving it open

Engineering Contradiction:
Improveease of cable insertionVSAvoidreliability of sealing
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The hose body is designed to automatically return to its closed sealing position through elastic recovery. Instead of requiring the user to manually close it, the system inverts the operation: opening is active (user pulls cable), but closing is passive (automatic elastic recovery), ensuring sealing reliability without compromising ease of operation.

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

Solution Approach 2:

The hose body performs self-closing through its elastic properties. After being opened for cable insertion, it automatically returns to the closed position without user intervention, making the system self-regulating and eliminating the risk of human error in maintaining the sealed state.

Inventive Principle:
Principle #25Self-service

2Ease of operation

If the hose body is kept in open position for cable passage, then the ease of operation is improved, but gas leakage occurs compromising the fire protection function

Engineering Contradiction:
Improveease of cable passageVSAvoidgas leakage
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The hose body is pre-configured in a closed sealed state before cable insertion. The elastic pre-tension ensures that the hose maintains its sealing position by default, and only temporarily opens during the brief moment of cable passage, then automatically returns to sealed position, preventing gas leakage.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system inverts the default state: instead of requiring active closing action, the hose body naturally remains closed and only opens when force is applied. This inversion ensures that the sealed state is maintained by default, preventing gas leakage while allowing easy cable passage when needed.

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

3Reliability

If a spring device is added to automatically close the hose body, then the reliability of sealing is improved, but the device complexity increases

Engineering Contradiction:
Improvereliability of sealingVSAvoidcomplexity of spring mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent utilizes the elastic parameter of the hose body material itself as the closing mechanism. By selecting materials with appropriate elastic properties, the hose body inherently provides the closing force without requiring separate spring components, thus improving sealing reliability while minimizing device complexity.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The closing function is merged into the hose body structure itself through elastic material properties. Rather than adding a separate spring device, the elastic recovery capability is integrated directly into the hose body, combining the sealing function with the structural element and avoiding additional 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 solution ensures the hose body remains closed in its basic state, preventing gas passage regardless of the number and size of cables, and can be easily opened for cable insertion, thereby preventing user errors and ensuring reliable sealing.

Implementation Method 1

a spring device (13) is provided which applies a force to the fastening element (9), which can be displaced in the axial direction relative to the cladding tube (2), which presses the hose body (8) in the direction of its closed position

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the spring device being designed as a torsion spring and the torsion spring converting an axial displacement of the fastening element into a rotation of the hose body

Methodology Applied
Scientific EffectTorsion spring mechanism: Torsion Spring

Data Source

PatentEP4045827B1Cable duct
Publication Date: 2023.11.15 HILTI AG
  • EP4045827B1 patent drawingFigure 1
  • EP4045827B1 patent drawingFigure 2
  • EP4045827B1 patent drawingFigure 3

AI summary

The invention relates to a line bushing (1) for guiding at least one line though a component, comprising a casing tube (2), a securing element (9) and at least one sealing element designed as a flexible sleeve body and arranged within the casing tube (2), wherein the sleeve body is connected to the securing element (9) in a first axial end region (5) and can be moved between a closed position in which the sleeve body at least partially closes a passage through the sleeve body, and an open position in which a passage through the sleeve body is at least partially released. A spring device (13) is also provided, which applies a force to the securing element (9) that can be moved in the longitudinal direction (L) relative to the casing tube (2), which presses the sleeve body in the direction of its closed position.