Cable Braid Termination With Coil Spring for Repairable Shield Clamping
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Solution Overview
Problem
Current methods for terminating EMI braided shields in high-speed connectors using ferrules are not repairable, require expensive tooling, and often fail to provide sufficient tensile retention force, necessitating the replacement of entire connector assemblies.
Innovation Solution
A coil spring is used to securely terminate the EMI braided shield to the shell housing of a connector assembly, providing a repairable and mechanically robust connection without the need for additional tooling, by being circumferentially wrapped around the shield and recessed portion of the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ferrule is used to terminate the EMI braided shield with a crimp tool, then a tight electrical and mechanical interface is created, but the termination becomes non-repairable and requires expensive additional tooling
Solution Approach 1:
The solution divides the termination system into separate components: a removable coil spring and a shell housing with an integrated recessed portion. This segmentation allows the coil spring to be independently removed and replaced without affecting the shell housing or requiring specialized crimping tools, thereby enabling repairability while maintaining a reliable electrical and mechanical interface.
Solution Approach 2:
The coil spring acts as an intermediary component between the EMI braided shield and the shell housing. It provides the necessary clamping force to create a tight electrical and mechanical interface while being easily installable and removable without specialized tooling, thus resolving the contradiction between interface reliability and ease of repair.
2Reliability
If a ferrule is crimped to the EMI braided shield, then a tight interface is created, but the tensile retention force is insufficient to hold the insulator and contacts
Solution Approach 1:
The coil spring provides dynamic, elastic clamping force that continuously maintains contact pressure between the EMI braided shield and the shell housing. This elastic deformation allows the spring to exert sustained tensile retention force on the insulator and contacts, overcoming the insufficient static force of a crimped ferrule while maintaining interface tightness.
3Ease of repair
If a coil spring is used to terminate the EMI braided shield, then the termination becomes repairable and provides high tensile retention force, but the device complexity increases
Solution Approach 1:
The coil spring serves multiple functions simultaneously: it provides mechanical clamping force, electrical connection, and tensile retention for the insulator and contacts. This multi-functionality reduces the need for additional components and simplifies the overall device structure, offsetting the apparent complexity increase from adding the spring while enhancing repairability.
4Reliability
If a ferrule termination is performed, then the EMI braided shield is secured, but the entire connector assembly must be replaced if repair is needed
Solution Approach 1:
The coil spring is designed to be disposable and easily replaceable, while the shell housing and EMI braided shield termination remain intact. When repair is needed, only the coil spring is discarded and replaced, not the entire connector assembly. This selective replacement minimizes component waste and reduces loss of substance compared to replacing the entire assembly.
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 coil spring solution offers a high tensile retention force, enabling a secure and repairable electrical and mechanical connection, preventing detachment of the EMI braided shield and allowing for easy access to contacts for reworking, with clamping forces exceeding those of crimped ferrules.
Implementation Method 1
The constant force spring is circumferentially wrapped about the EMI braided shield to mechanically and electrically secure the EMI braided shield to the recessed portion of the shell housing
Implementation Method 2
A coil spring is used to securely terminate the EMI braided shield to the shell housing of a connector assembly, providing a repairable and mechanically robust connection
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
An assembly (10) for terminating a high speed cable (60) with an EMI braided shield (66). The assembly (10) comprises a shell housing (12), a crosstalk shield (14) and a constant force spring (70). The shell housing (12) has a mating end (20) and a conductor receiving end (22). A recessed portion (26) is provided proximate the conductor receiving end, the recessed portion (26) has an outer diameter (D2). The crosstalk shield (14) is provided in the shell housing (12). The constant force spring (70) is positioned in the recessed portion (26) of the shell housing (12). The constant force spring (70) has an opening (71) with an inner diameter (D3) which is less than the outer diameter (D2) of the recessed portion (26). The constant force spring (70) is circumferentially wrapped about the EMI braided shield (66) to mechanically and electrically secure the EMI braided shield (66) to the recessed portion (26) of the shell housing (12).