Explosion-Proof Cable Connection Using Radial Crimping

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Solution Overview

Problem

Existing explosion-proof cable connection methods often result in material deformation, leading to gap formation and potential ignition risks due to settlement effects, necessitating separate and costly connections for each core.

Innovation Solution

A cable connection device with a crimping section made of plastically deformable material and an inner sleeve of elastically deformable material, where the crimping section is deformed to ensure a gap-free, explosion-proof seal without material flow, using a crimping tool to radially deform both the inner sleeve and cable sheathing, ensuring a tight fit around the wires.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If screw connections are used to connect cable connection devices to cables, then the connection can be established easily, but material deformation occurs at small points leading to gap formation and potential ignition risks

Engineering Contradiction:
Improveconnection establishmentVSAvoidignition protection
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent replaces the screw connection mechanical system with a crimping mechanical system. The crimping tool applies radial force to deform the crimping section, creating a secure mechanical interlock between the cable connection device and cable without the settlement issues of screw connections. This substitution maintains ease of operation while eliminating the gap formation problem.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the connection parameter from threaded engagement to radial compression. By applying radial force through the crimping tool, the crimping section deforms radially inward to create friction and mechanical interlock. This parameter change eliminates the small-point deformation and gap formation associated with screw connections while maintaining reliable ignition protection.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If each core of a cable is connected separately in an explosion-proof manner, then long-term protection against ignition breakdown is ensured, but the effort and cost become very great

Engineering Contradiction:
Improveignition protectionVSAvoidconnection structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple individual core connections into a single unified crimping operation. The crimping section radially deforms to simultaneously secure all cores within the cable sheathing through one mechanical action. This merging maintains explosion-proof reliability by ensuring all cores are firmly held without gaps, while dramatically reducing device complexity and installation effort compared to separate connections for each core.

Inventive Principle:
Principle #5Merging (Combining)

3Strength

If plastically deformable material is used for the crimping section, then a tight fit is achieved, but material flow could potentially create ignition gaps

Engineering Contradiction:
Improveconnection tightnessVSAvoidignition protection
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent changes the deformation mode from plastic flow to elastic recovery. The crimping section is designed to deform elastically under radial compression, storing mechanical energy that creates continuous outward pressure on the cable sheathing and cores. This elastic deformation achieves tight connection strength while avoiding the material flow and settlement that create ignition gaps in plastically deformable materials.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite structure where the crimping section (plastically deformable) works in conjunction with the inner sleeve (elastically deformable). The plastic deformation of the crimping section provides initial tightness, while the elastic inner sleeve maintains continuous pressure and compensates for any settling, preventing ignition gap formation despite the plastic material flow.

Inventive Principle:
Principle #40Composite materials

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

This method provides a reliable, cost-effective, and gap-free explosion-proof connection for cables with multiple cores, eliminating ignition risks and simplifying the connection process by avoiding separate connections for each wire.

Implementation Method 1

Radial plastic deformation of the crimping section 23 brings about an elastic deformation of the inner sleeve 19 and of the cable sheathing 13

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

Any gaps 40 present within the cable sheathing 13 are closed due to the radial forces in the crimping section 23

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP2923421B1Explosion-proof assembly having a cable-connecting device and a cable
Publication Date: 2017.08.23 R STAHL SCHALTGERATE GMBH
  • EP2923421B1 patent drawingFigure 1~2
  • EP2923421B1 patent drawingFigure 3~4
  • EP2923421B1 patent drawingFigure 5~6

AI summary

The invention relates to an assembly (14) of a cable-connecting device (10) and a multi-core cable (11), which form a mechanical, explosion-proof connection to each other. For this purpose, the cable-connecting device (10) has a plastically deformable outer sleeve (18) having a crimping section (23). A hollow cylindrical inner sleeve (19) made of elastically deformable material is arranged between a cable sheath (13) made of elastomer and the crimping section (23). An elastic deformation of the inner sleeve (19) and of the cable sheath (13) is caused by radially plastically deforming the crimping section (23). Any gaps (40) present within the cable sheath (13) are closed due to the radial forces in the crimping section (23) such that spark-gap-free contact between the cable sheath (13) and the cores (12) of the cable (11) and between the cable sheath (13) and the inner sleeve (19) is ensured.