Sealed Cable Passage Structure for Controlled Membrane Tearing

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Solution Overview

Problem

Conventional cable glands for electrical boxes often result in uneven tearing of the membrane, leading to irregular openings and compromised watertight seals when inserting electrical cables or conduits.

Innovation Solution

A cable pass-through fitting with a support plate and flexible, perforable sealing membrane, featuring rigid elements that guide the cable insertion to ensure a controlled and regular orifice, minimizing membrane stretching and irregular tearing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a flexible and perforable sealing membrane is used to close the opening in the cable gland, then the membrane can be easily pierced by the electrical cable, but the membrane may tear unevenly and irregularly when the cable is inserted

Engineering Contradiction:
Improveease of cable insertionVSAvoidregularity of the opening contour
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

A rigid element is introduced as an intermediary between the electrical cable and the sealing membrane. This rigid element guides the cable during insertion and controls the tearing process, ensuring the membrane tears along a predetermined regular path rather than irregularly when directly pierced by the cable

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The rigid element is positioned in advance within the opening to define a predetermined tearing path. This preliminary arrangement ensures that when the cable is inserted, the membrane will tear along the controlled path defined by the rigid element's position and shape

Inventive Principle:
Principle #10Preliminary action

2Adaptability or versatility

If the membrane is made flexible to allow cable passage, then the cable can be inserted through the membrane, but the membrane may stretch excessively and compromise the watertight seal

Engineering Contradiction:
Improveability to accommodate cable insertionVSAvoidwatertightness of the seal
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The rigid element acts as a mediator that limits and controls the deformation of the flexible membrane during cable insertion. By guiding the cable along a predetermined path, the rigid element prevents excessive stretching of the membrane while still allowing the cable to pass through, thereby maintaining the watertight seal

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The membrane is designed with different properties in different areas: it is flexible in the regions where cable passage is needed, but reinforced or constrained near the rigid element to prevent excessive stretching. This local differentiation allows the membrane to accommodate cable insertion while maintaining overall seal integrity

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3840150B1Sealed cable passage, electrical box comprising such a cable passage and electrical apparatus comprising an apparatus mechanism mounted in such an electrical box
Publication Date: 2026.01.28 LEGRAND FRANCE SA
  • EP3840150B1 patent drawingFigure 1~3A
  • EP3840150B1 patent drawingFigure 2
  • EP3840150B1 patent drawingFigure 3B

AI summary

The invention relates to a watertight cable gland (50) comprising an entry face for the insertion of an electrical cable into an electrical box for electrical equipment, including: a support plate having an internal peripheral edge that defines an opening for the passage of the electrical cable; at least one rigid element extending into a zone of said opening between said internal peripheral edge of the support plate and the center of said opening; and a flexible, perforable sealing membrane, at least partially overmolded onto said support plate, which closes said opening and is adapted to allow the passage of the electrical cable. According to the invention, each rigid element has a portion not covered by said membrane so as to be directly accessible to said electrical cable from the side of the entry face of the gland.