Lock Washer Sliding Ring Surface for Soft Contact Rails

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Solution Overview

Problem

In high-voltage electrical connections, screw connections on soft surfaces like copper or aluminum can experience preload force losses due to setting and creeping processes, leading to potential arcing and increased transmission resistance, and existing solutions like flat washers may not adequately prevent damage to the contact rail surfaces.

Innovation Solution

A locking washer with a flat sliding ring surface and rounded transitions, produced by embossing, that slides over the contact rail without damaging it, providing good locking properties and resilience to maintain contact pressure and prevent material abrasion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a locking washer is pressed and rotated against a soft contact rail surface, then the locking washer achieves proper seating and locking function, but the edges of the washer may damage the contact rail surface causing chip formation or protrusions

Engineering Contradiction:
Improvelocking functionVSAvoiddamage to contact rail surface
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies curvature by rounding the edges of the locking washer that contact the soft mating surface. This rounded geometry allows the washer to slide and seat properly during tightening without concentrating stress at sharp edges, thereby preventing chip formation and surface damage while maintaining effective locking function.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent applies different geometric properties to different parts of the washer: the edges contacting the soft surface are rounded to prevent damage, while the inner locking surfaces maintain their functional geometry for effective locking. This localized differentiation of geometric quality resolves the contradiction between seating function and surface protection.

Inventive Principle:
Principle #3Local quality

2Reliability

If the outer annular section surface forms a specific angle with the inner annular section surface, then good spring and locking properties are achieved, but complete contact of the washer underside with the contact rail must be ensured to maintain low surface pressure

Engineering Contradiction:
Improvespring and locking propertiesVSAvoidsurface pressure
Core Design Contradiction:
ReliabilityVSStress or pressure

Solution Approach 1:

The patent optimizes the angle parameter between the outer and inner annular section surfaces to achieve the desired balance. By carefully selecting this geometric parameter, the washer maintains adequate spring and locking properties while ensuring sufficient contact area to keep surface pressure within acceptable limits.

Inventive Principle:
Principle #35Parameter changes

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 locking washer effectively prevents damage to the contact rail, maintains continuous contact pressure, and reduces the risk of arcing by sliding smoothly over the contact rail, ensuring reliable electrical conductivity with reduced surface pressure and increased springback force.

Implementation Method 1

the sliding ring surface 4 is rounded on both sides... which facilitates sliding of the locking washer edge in the contact area when the locking washer is pressed onto the contact rail

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

the sliding ring surface is produced by embossing. This results in a significantly smoother sliding ring surface, which is also additionally hardened. This improves... the sliding of the retaining washer edge in the contact area with the contact rail. Secondly, the hardened structure of the sliding ring surface counteracts material abrasion in the contact area.

Methodology Applied
Scientific EffectHardening: Heat Treatment

Data Source

PatentEP3296578B1Lock washer for electrically conductive connections
Publication Date: 2020.04.08 VOLBORTH THOMAS
  • EP3296578B1 patent drawingFigure 1~3
  • EP3296578B1 patent drawingFigure 4~5

AI summary

The invention relates to a retaining washer for electrically conductive connections for arrangement on a flat electrical contact rail (7), comprising an annular disc body (1) on the underside (12) of which, facing the contact rail (7), an outer annular section surface (3) and an inner annular section surface (2) are arranged at an angle to each other. The outer annular section surface (3) transitions into a flat sliding ring surface (4) which is designed to bear in planar contact with the contact rail (7).