Elastomeric Inner Ferrule for Shielded Cable Terminal Assembly
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Solution Overview
Problem
Existing terminal assemblies for shielded cables face challenges in accommodating different cable sizes due to the need for carefully matched inner and outer ferrule diameters, which can lead to manufacturing complexity and increased costs, as well as issues with ferrule rupture and electrical resistance.
Innovation Solution
A terminal assembly featuring a resiliently compressible inner ferrule made of elastomeric material with a Shore A durometer hardness between 50 and 80, which is molded to fit various cable sizes and includes features like circumferential grooves and ridges to enhance retention and reduce electrical resistance, paired with a conductive outer ferrule for secure crimping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thick inner ferrules are used, then the ferrule provides sufficient structural support, but the crimp strength is degraded and pull-off force is reduced
Solution Approach 1:
The patent changes the material parameter of the inner ferrule from rigid metal to elastomeric material with specific durometer hardness (40-90 Shore A), allowing the ferrule to be compressible rather than rigid. This parameter change enables the ferrule to deform during crimping, improving contact with the braided shield and maintaining crimp strength while providing sufficient structural support.
Solution Approach 2:
The patent uses composite material construction where the inner ferrule is made of elastomeric material and the outer ferrule is made of conductive material. This composite approach combines the advantages of both materials: the elastomeric inner ferrule provides compressibility and conformability to the braided shield, while the conductive outer ferrule provides electrical conductivity and structural integrity.
2Force
If thin inner ferrules are used, then the crimp strength is improved, but the ferrule can rupture during crimping causing electrical shorts
Solution Approach 1:
The patent changes the material parameter of the inner ferrule from rigid metal to elastomeric material with specific durometer hardness (40-90 Shore A), allowing the ferrule to be compressible rather than rigid. This parameter change enables the ferrule to deform during crimping, improving contact with the braided shield and maintaining crimp strength while providing sufficient structural support.
Solution Approach 2:
The elastomeric inner ferrule acts as a cushioning element between the outer ferrule and the braided shield. During crimping, the compressible inner ferrule absorbs the compression forces, preventing direct transmission of excessive force to the braided shield that could cause rupture or electrical shorts.
3Adaptability or versatility
If different sized inner and outer ferrules are used for different cable sizes, then the ferrule assembly accommodates various cable dimensions, but the manufacturing complexity and cost increase
Solution Approach 1:
The patent makes the inner ferrule universal by using elastomeric material that can be molded in various sizes and configurations. A single elastomeric inner ferrule design can accommodate different cable sizes by varying only the dimensions, not the material type. The outer ferrule is made conductive to provide the necessary electrical connection, while the elastomeric inner ferrule provides the adapting interface for different cable dimensions.
Solution Approach 2:
The patent changes the material parameter of the inner ferrule from rigid metal to elastomeric material with specific durometer hardness (40-90 Shore A), allowing the ferrule to be compressible rather than rigid. This parameter change enables the ferrule to deform during crimping, improving contact with the braided shield and maintaining crimp strength while providing sufficient structural support.
4Ease of operation
If markings such as color coding are applied to ferrules, then different ferrule sizes can be visually distinguished, but the manufacturing time and cost increase
Solution Approach 1:
The patent changes the material parameter of the inner ferrule from rigid metal to elastomeric material with specific durometer hardness (40-90 Shore A), allowing the ferrule to be compressible rather than rigid. This parameter change enables the ferrule to deform during crimping, improving contact with the braided shield and maintaining crimp strength while providing sufficient structural support.
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 improves the pull-off force and reduces electrical resistance, allowing for a cost-effective and versatile terminal assembly that can accommodate multiple cable sizes with reduced manufacturing complexity and risk of short circuits.
Implementation Method 1
a generally cylindrical inner ferrule that is formed of an elastomeric material having a Shore A durometer hardness between 50 and 80. The inner ferrule is resiliently compressible
Implementation Method 2
The outer ferrule is then crimped to retain the terminal assembly to the shielded cable, plastically deforming the outer ferrule
Implementation Method 3
The outer ferrule is then crimped to retain the terminal assembly to the shielded cable... reducing electrical resistance
Data Source
AI summary
A terminal assembly is configured to terminate a shielded cable having an inner conductor, an inner insulator surrounding the inner conductor, an outer conductor surrounding the inner insulator, and an outer insulator surrounding the outer conductor. This terminal assembly includes a generally cylindrical outer ferrule formed of a plastic conductive material, i.e. a material that is deformed after stress is removed, and a generally cylindrical inner ferrule formed of an elastic dielectric material i.e. a material that recovers after stress is removed, having a plurality of circumferential grooves defined in an outer surface thereof. At least a portion of the inner ferrule is disposed within the outer ferrule. A portion of the outer conductor is disposed intermediate the inner ferrule and the outer ferrule and is in intimate contact therewith.