Rotating Membrane Cable Bushing for Smoke Gas Tightness

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Solution Overview

Problem

Existing fire protection cable bushings face challenges in achieving reliable smoke gas tightness and preventing misuse, with issues such as resistance during cable insertion, poor sealing, and the risk of incorrect sealing in mechanically closed systems.

Innovation Solution

A sleeve-like housing with a rectangular or hexagonal cross-section and an airtight elastic membrane that twists to create a secure, airtight seal, preventing misuse and ensuring smoke and gas tightness, with the membrane spanning the passage channel and being secured by a fitting frame that can be rotated to enclose the lines.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a sealing system yields to resistance during cable insertion, then cables can be inserted, but sealing quality and smoke tightness deteriorate

Engineering Contradiction:
Improvecable insertionVSAvoidsealing quality
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The membrane is pre-stressed during installation to create an airtight seal before cables are inserted. The membrane is tensioned between the fitting frame and housing end face, establishing the seal in advance rather than during cable insertion, thus maintaining both ease of cable insertion and high sealing quality

Inventive Principle:
Principle #10Preliminary action

2Reliability

If a mechanical closing system is used, then airtightness is improved, but the risk of misuse and forgetting to close increases

Engineering Contradiction:
ImproveairtightnessVSAvoidmisuse prevention
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The membrane sealing system is self-activating through the rotation of the fitting frame. As the fitting frame is rotated to its final position, the membrane automatically tensions and seals the passage. The system serves itself by converting the installation action (rotation) directly into the sealing action, eliminating the need for separate closing steps that could be forgotten

Inventive Principle:
Principle #25Self-service

3Reliability

If the fitting frame is rotated to create a seal, then smoke tightness is improved, but device complexity increases

Engineering Contradiction:
Improvesmoke tightnessVSAvoidsealing mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sealing mechanism uses dynamic rotation of the fitting frame to transform the membrane from a loose state to a tensioned sealing state. The membrane transitions from an initial configuration where it hangs loosely to a final configuration where it is stretched taut between the rotated fitting frame and the housing, creating the seal through motion rather than complex static structures

Inventive Principle:
Principle #15Dynamics

4Area of stationary object

If a rectangular cross-section is used, then space utilization is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improvespace utilizationVSAvoidrectangular geometry
Core Design Contradiction:
Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent employs a rectangular cross-section for the housing and fitting frame, utilizing the asymmetric geometry to prevent rotational misalignment during installation. The rectangular shape provides distinct orientation references that guide proper positioning, and when combined with the membrane tensioning mechanism, creates a seal that is tolerant of minor dimensional variations while maximizing space utilization

Inventive Principle:
Principle #4Asymmetry

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 provides reliable smoke and gas tightness while preventing incorrect use, allowing for easy cable routing and subsequent installation without additional locking, ensuring the seal remains secure and airtight.

Implementation Method 1

An airtight elastic membrane is arranged in the passageway, extending from end face to end face and attached at one end to the fitting frame and at the other end to the second end face of the housing

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4113766A1Device and method for sealing a cable bushing
Publication Date: 2023.01.04 HILTI AG
  • EP4113766A1 patent drawingFigure 1~2
  • EP4113766A1 patent drawingFigure 3
  • EP4113766A1 patent drawing

AI summary

The invention relates to a device (1) for sealing a pipe penetration, comprising: - a sleeve-like housing (2) having an axial passage channel with a rectangular or hexagonal cross-section and two open end faces (3, 4); - a rectangular or hexagonal fitting frame (5) that can be inserted or permanently attached to a first end face (3) of the housing (2); and - an airtight elastic membrane (7) stretched in the passage channel from the first end face (3) to the second end face (4), the first edge of which is attached to the fitting frame (5) along its entire circumference and the opposite second edge of which is attached to the second end face (4) of the housing (2);- wherein the membrane (7) seals the passage channel airtight around a centrally located conductor entry point (8) by or when the fitting frame (5) fixed to the first end face (3) of the housing (2) together with the membrane (7) attached thereto is arranged rotated by a predetermined angle of rotation with respect to the second end face (4) of the housing (2) and the membrane (7) is thereby tensioned.