Shielded Cable Ferrule Clamping for EMI Leakage Reduction
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Solution Overview
Problem
Braided shields in electrical cables flare when entering a backshell, creating gaps that reduce optical coverage and cause leakage, leading to interference and noise issues.
Innovation Solution
A connection system for shielded cables that includes a ferrule positioned between the inner and outer braided shields, a backshell with a cylindrical channel to clamp the ferrule and shields, and solder and epoxy wells for additional sealing, ensuring a 360-degree circumferential connection and reducing leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a braided shield is used to encase the cable, then optical coverage and interference reduction are improved, but the shield flares when entering the backshell creating gaps that cause leakage
Solution Approach 1:
A ferrule is introduced as an intermediary component between the braided shield and the backshell. The ferrule receives the braided shield in a flared state and provides a rigid structure that maintains the shield's position without requiring the shield itself to maintain its shape, thus preventing gaps while allowing natural flaring.
Solution Approach 2:
The backshell includes a channel with a tapered or flared geometry that matches and accommodates the natural flaring of the braided shield. By changing the geometric parameters of the channel to align with the shield's flared shape, the system eliminates gaps without constraining the shield's natural deformation.
2Ease of operation
If the braided shield flares at the backshell, then insertion into the backshell is easier, but gaps are created that reduce optical coverage and cause leakage
Solution Approach 1:
The ferrule acts as a mediator that accepts the flared shield during insertion and then provides a rigid structure that maintains continuous coverage. This allows the shield to flare during insertion for ease of operation while the ferrule ensures optical coverage is maintained in the final assembled state.
Solution Approach 2:
The backshell channel is pre-formed with a flared geometry that anticipates and accommodates the shield's natural flaring during insertion. This preliminary geometric preparation allows smooth insertion while ensuring the shield maintains contact with the channel walls to prevent gaps.
3Reliability
If a ferrule is added to clamp the shields, then leakage is reduced, but device complexity increases
Solution Approach 1:
The ferrule serves multiple functions simultaneously: it provides a clamping structure to hold the braided shield, provides a rigid support to maintain shield position and prevent gaps, and serves as a mechanical interface between the shield assembly and the backshell. By combining these functions into a single component, the complexity increase is minimized while achieving reliable leakage prevention.
Data Source
AI summary
A connection system for a cable includes a shielded cable that is inserted into a backshell. Among other elements, the shielded cable might include a ferrule that is crimped between shields near an end of the cable. In addition, the backshell includes a channel that clamps around the ferrule, as well as various solder wells.