Strain Relief Elements for Electrical Wire Axial Movement

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Solution Overview

Problem

Existing electrical connectors for safety restraint systems, such as those used in automotive applications, fail to effectively restrict axial movement of ultra-thin isolation electrical wires without damaging their insulation jackets, leading to potential humidity exposure and connection failure.

Innovation Solution

The introduction of a strain relief member with axially spaced sawtooth-shaped strain relief elements in the connector housing, which engage with the insulating jacket of the electrical wire to restrict axial movement by increasing friction without damaging the insulation, by deforming the jacket material to fill recesses between the elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If strain relief elements are provided to restrict axial movement of electrical wires, then the axial movement is restricted, but the insulation jacket is damaged

Engineering Contradiction:
Improveaxial movement restrictionVSAvoidinsulation jacket damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The strain relief elements are designed with differentiated local properties: the contact surface has a smoother finish to engage with the insulation jacket without causing damage, while the rear portion provides the necessary friction to restrict axial movement. This local quality differentiation allows the same component to perform both functions effectively.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The strain relief elements feature a gradual change in surface roughness and geometry along their length. The contact surface has a finer surface finish that transitions to a rougher texture toward the rear, creating a progressive engagement that secures the wire without damaging the insulation jacket.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If compressive force is applied by strain relief elements on the side of the electrical wire, then axial movement is restricted, but the insulation jacket is damaged exposing the electrical conductor to humidity

Engineering Contradiction:
Improveaxial movement restrictionVSAvoidhumidity exposure due to insulation damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The strain relief elements apply force through a localized contact surface that is specifically designed to distribute the compressive force evenly across the insulation jacket. This prevents stress concentration that would otherwise lead to jacket damage and subsequent humidity exposure of the conductor.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The strain relief elements are positioned and designed to provide gradual engagement with the electrical wire, cushioning the transition from free movement to restricted movement. This progressive engagement prevents sudden force application that could damage the insulation jacket.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If strain relief elements contact only a limited portion of the electrical wire, then the structure is simple, but the axial movement restriction is insufficient

Engineering Contradiction:
Improvestrain relief structure simplicityVSAvoidaxial movement restriction effectiveness
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The strain relief elements are designed with a three-dimensional geometry that engages the electrical wire at multiple points along its circumference. This dimensional approach allows a single simple component to effectively contact and restrict movement of the entire wire without increasing structural complexity.

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

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 solution effectively restricts axial movement of electrical wires while maintaining the integrity of the insulation jacket, preventing damage and ensuring reliable connections even with ultra-thin isolation wires, through increased friction and even distribution of strain relief elements.

Implementation Method 1

each strain relief element comprising a contact surface configured to engage, when the portion of the electrical wire is positioned into the channel, with the insulating jacket causing the insulating jacket material to deform and at least partially fill respective recesses defined between adjacent strain relief elements

Methodology Applied
Scientific EffectDeformation: Deformation

Implementation Method 2

The strain relief elements may be provided with a sawtooth profile having a contract surface comprising a tip with a generally flat contact region and a tooth face protruding at an upright angle from the inner surface of the channel to a tip, e.g. zero rake angle. The contact of the tip of the strain relief element with the insulating jacket causes the insulating material to deform and at least partially fill recesses defined between adjacent strain relief elements.

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP4125161A1Electrical connector with improved strain relief for electrical wires
Publication Date: 2023.02.01 APTIV TECHNOLOGIES AG
  • EP4125161A1 patent drawingFigure 1
  • EP4125161A1 patent drawingFigure 1A
  • EP4125161A1 patent drawingFigure 2

AI summary

The present disclosure provides an connector housing (110) for an electrical connector (100) assembly. The connector housing (110) comprises a strain relief member (150) comprising at least one channel (152) configured for receiving a portion of the electrical wire (140). The strain relief member (150) comprises a plurality of axially spaced strain relief elements (153) protruding from an inner surface (155) of the channel (152) over a strain relief region (157). Each strain relief element (153) comprising a contact surface (153a) configured to engage, when the portion of the electrical wire (140) is positioned into the channel (152), with the insulating jacket (140b) of the electrical wire (140) causing the insulating jacket (140) material to deform and at least partially fill respective recesses (153b) defined between adjacent strain relief elements (153) so as to restrict axial movement of the electrical wire (140) with respect to the first connector housing (110).