Seal Retainer Lock Arm Flex Limiting Strap

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Solution Overview

Problem

Existing wire harness assemblies face issues with seal retainers that can be damaged during disassembly due to exceeding the elastic limit of lock arms, leading to ineffective retention and requiring significant rework for replacement.

Innovation Solution

A wire harness assembly design featuring a seal retainer with resilient lock arms and flex limiting straps that prevent over-flexing, allowing for secure installation and removal without exceeding the elastic limit, ensuring reliable retention and minimizing rework.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If lock arms are made flexible and resilient to allow lifting over lock protuberances during assembly and disassembly, then ease of operation is improved, but the lock arms may be displaced sufficiently far to exceed the elastic limit, preventing return to original position and rendering the seal retainer ineffective

Engineering Contradiction:
Improveease of assembly and disassemblyVSAvoidreliability of lock arm retention
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent changes the physical state of the lock arm from a purely elastic material to a shape memory alloy that undergoes phase transformation. This allows the lock arm to be deformed beyond its original elastic limit during installation, then automatically return to its original shape when the phase transformation condition (temperature or stress) is met, ensuring reliable retention without exceeding damage thresholds

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The shape memory alloy lock arm performs the retention function automatically through its inherent phase transformation properties. When deformed during assembly, it self-recovers its original shape without external intervention, ensuring consistent engagement with the lock protuberance and eliminating the need for manual adjustment or monitoring

Inventive Principle:
Principle #25Self-service

2Ease of operation

If significant forces are applied to lock arms to pry them free of lock protuberances during disassembly, then the seal retainer can be removed from the housing, but the lock arms may be damaged by exceeding their elastic limit, requiring significant rework to replace

Engineering Contradiction:
Improveease of disassemblyVSAvoidease of repair after damage
Core Design Contradiction:
Ease of operationVSEase of repair

Solution Approach 1:

The shape memory alloy lock arm utilizes phase transformation to withstand disassembly forces that would normally exceed the elastic limit of conventional materials. The material transforms phases under stress, allowing temporary deformation beyond the original elastic limit, then automatically recovers its shape, preventing permanent damage and eliminating the need for replacement or repair

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The shape memory alloy provides inherent cushioning against over-stress during disassembly. The material's phase transformation capability acts as a built-in protective mechanism that absorbs excessive forces during prying operations, preventing damage before it occurs and eliminating the need for subsequent repair work

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

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 design ensures reliable retention of the seal retainer to the housing, preventing damage and reducing the need for rework by limiting the extent of lock arm flexion, thus maintaining effective sealing and assembly integrity.

Implementation Method 1

the lock arm being resilient and compliant which allows the lock arm to flex away from the axis, thereby allowing the lock arm to lift over the retention protuberance when the seal retainer is being installed on the housing and when the seal retainer is being removed from the housing

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3419130B1Wire harness assembly and seal retainer therefore
Publication Date: 2020.09.09 APTIV TECHNOLOGIES LTD
  • EP3419130B1 patent drawingFigure 1
  • EP3419130B1 patent drawingFigure 2~3
  • EP3419130B1 patent drawingFigure 4~5

AI summary

A wire harness assembly (10) includes a housing (18) defining an interior volume (30) which extends into the housing (18) along an axis (32) and also defines an outer surface (38) having a retention protuberance (44) extending outward therefrom. A seal (20) is received within the interior volume (30) and a wire (12) extends through the seal (20) into the interior volume (30). A seal retainer (22) includes skirt segments (54a) which extend from the seal retainer wall (48) such that each of the skirt segments (54a) is positioned laterally to the outer surface (38) and such that one of the skirt segments (54a) is a lock arm (54a) having a lock aperture (56) which captures the retention protuberance (44) therein, thereby retaining the seal retainer (22) to the housing (18). A flex limiting strap (58) joins the lock arm (54a) to an adjacent one of the skirt segments (54a) and limits the extent to which the lock arm (54a) flexes away from the axis (32).