Shielding Terminal Knurling for Vibration Resistance
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Solution Overview
Problem
Existing shielding electrical terminals face issues with mechanical vibration causing fretting and increased electrical resistance due to limited contact points and air gaps, which complicates manufacturing and increases costs.
Innovation Solution
A shielding electrical terminal with a knurled inner surface featuring non-uniform protrusions and recesses, arranged in a rhombus pattern, provides multiple contact points and minimizes air gaps, formed through a cost-effective manufacturing process that includes knurling and rolling of metal sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spring contact arms are used to provide contact force, then electrical contact is established, but the number of contact points is limited and fretting occurs under mechanical vibration
Solution Approach 1:
The inner surface of the mating portion is segmented into multiple protrusions distributed across the contact area, transforming a single contact interface into multiple discrete contact points. This segmentation increases the number of contact points from a few spring contact arms to numerous protrusions, distributing the mechanical load and electrical current across more points, thereby reducing fretting corrosion at each individual contact point while maintaining reliable electrical contact
Solution Approach 2:
The contact interface is extended from a one-dimensional line contact (spring arms) to a two-dimensional surface contact (knurled protrusions distributed across the inner surface). This dimensional expansion creates multiple contact points across the contact area, increasing redundancy and distributing mechanical stress and electrical current more evenly, which reduces fretting corrosion and improves contact reliability under vibration
2Reliability
If complex geometries are used to increase contact points, then fretting resistance improves, but manufacturing time and cost increase
Solution Approach 1:
The knurled surface geometry parameters (protrusion height, spacing, pattern) are optimized to achieve an effective balance between fretting resistance and manufacturability. The protrusions are designed with dimensions and distributions that provide sufficient contact points for vibration resistance while remaining compatible with standard knurling tooling and manufacturing processes, avoiding the need for complex custom geometries that would increase cost
3Reliability
If air gap between terminals is reduced, then shielding efficiency improves, but manufacturing precision requirements increase
Solution Approach 1:
The knurled protrusions create localized contact zones that concentrate the electrical and mechanical interface at specific points rather than requiring uniform contact across the entire surface. This local quality approach allows for effective electrical contact and reduced air gap effects at the protrusion contact points while being more tolerant of variations in overall assembly alignment, reducing the stringency of manufacturing precision requirements
Data Source
AI summary
A shielding electrical terminal is presented herein. The shielding electrical terminal includes a securing portion that is configured to attach to an outer shield conductor of a shielded cable and a cylindrical mating portion having an inner surface configured to make electrical contact with a corresponding cylindrical shield terminal inserted within the mating portion. The inner surface of the mating portion defines a plurality of protrusions that extend from the inner surface.