Cupped Bonding Lug Washer Rim Angle for Connection Stability
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Solution Overview
Problem
Conventional bonding lug washers lack an effective design that securely fastens a compression lug to a grounding busbar, leading to potential loosening of nuts due to inadequate force distribution and retention.
Innovation Solution
A cupped bonding lug washer with a rim portion forming an angle between 6 and 20 degrees with the support edge, featuring integrally formed apertures and a planar contact surface, which provides a reactionary force to compress the mating threads and prevent nut loosening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional flat washer design is used, then the structure is simple, but the force distribution is inadequate leading to nut loosening
Solution Approach 1:
The washer employs a curved rim portion that forms an angle between 6 and 20 degrees with the support edge, creating a cupped geometry. This curvature transforms the force distribution pattern, allowing the rim to engage the compression lug more effectively and prevent rotation, thereby solving the nut loosening problem while maintaining structural simplicity
Solution Approach 2:
The invention transitions from a conventional flat two-dimensional washer to a three-dimensional cupped structure with a raised rim portion. This dimensional change adds vertical engagement capability, allowing the washer to compress the lug against the busbar more effectively and prevent lateral movement, thus improving connection stability
2Force
If the rim portion forms a larger angle with the support edge, then the compression force is increased, but the contact surface area with the busbar is reduced
Solution Approach 1:
The invention optimizes the rim angle parameter to a specific range of 6 to 20 degrees. This parameter optimization balances the compression force generation (which increases with angle) against the contact surface area (which decreases with angle), achieving the optimal force distribution that prevents nut loosening while maintaining adequate bearing surface
Data Source
AI summary
A washer includes a perimeter portion, a support edge adjoining the perimeter portion and defining a first plane, and a contact portion having a generally planar contact surface. The contact surface defines a second plane parallel to and spaced from the first plane. The contact portion further includes at least two apertures extending therethrough. The washer further includes a rim portion extending between the perimeter portion and the contact portion. The rim portion surrounds the contact portion and forms an angle with the first plane of between 6 and 20 degrees. The contact portion and the rim portion are integrally formed as one-piece.