Eccentric Bushing Anti-Rotation via Nickel-Diamond Coating

Solution Overview

Problem

Eccentric bushings used in bolted joints tend to rotate under shear loads due to their eccentricity, requiring splined teeth and lock plates for alignment, which increases manufacturing costs and installation time, especially in applications like aircraft assembly where many connections are needed.

Innovation Solution

The use of nickel-diamond coated friction washers between eccentric bushings and fittings to prevent rotation, eliminating the need for splined teeth and simplifying the installation process by providing a high friction interface that prohibits movement even with lubrication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If splined teeth and lock plates are used to prevent rotation of eccentric bushings, then the bushings remain aligned under shear loads, but manufacturing costs and installation time increase

Engineering Contradiction:

Improvealignment stabilityVSAvoidcomponent complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical splined teeth and lock plate system with a friction-based system using high-friction coating material applied to the bushing surface. The friction force generated between the coated bushing and the fitting hole prevents rotation without requiring complex mechanical interlocking components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and eliminates the lock plate component entirely, relying solely on the friction coating applied to the bushing to prevent rotation. This simplifies the overall assembly by removing the separate lock plate that would otherwise be required to engage with splined teeth.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If splined teeth are used on bushings and lock plates, then rotation is prevented, but installation time increases due to alignment requirements

Engineering Contradiction:

Improverotation preventionVSAvoidinstallation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces the mechanical splined teeth and lock plate system with a friction-based system using high-friction coating material applied to the bushing surface. The friction force generated between the coated bushing and the fitting hole prevents rotation without requiring complex mechanical interlocking components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If splined teeth and lock plates are used to prevent bushing rotation, then alignment is maintained, but manufacturing cost increases

Engineering Contradiction:

Improvealignment maintenanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical splined teeth and lock plate system with a friction-based system using high-friction coating material applied to the bushing surface. The friction force generated between the coated bushing and the fitting hole prevents rotation without requiring complex mechanical interlocking components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and eliminates the lock plate component entirely, relying solely on the friction coating applied to the bushing to prevent rotation. This simplifies the overall assembly by removing the separate lock plate that would otherwise be required to engage with splined teeth.

Inventive Principle:

Principle #2Taking out (Extraction)

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

This solution reduces the complexity and cost of installation by allowing for quicker and easier alignment of bolted joints without the need for intricate teeth, while maintaining a secure connection, thus reducing the time and expense associated with large-scale applications like aircraft assembly.

Implementation Method 1

The coating on the first friction washer prohibits rotation of the first eccentric bushing with respect to the first fitting... providing a high friction interface that prohibits movement even with lubrication

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS10001158B2Anti-rotation for eccentric bushings

Publication Date: 2018.06.19 THE BOEING CO

AI summary

An attachment system and method that includes first and second fittings, a first eccentric bushing positioned within the first fitting, and a second eccentric bushing positioned within the second fitting. The system may include a first friction washer positioned between the first bushing and first fitting and a second friction washer positioned between the second bushing and the second fitting. A coating on the exterior of the friction washers prohibits rotation of the bushings with respect to the fittings. The coating may be a nickel-diamond coating that prohibits rotation even in the presence of a lubricant. The first fitting may be a frame fitting connected to a fuselage of an aircraft and the second fitting may be a beam fitting connected to the floor of the aircraft. The system may include lock plates that engage lock stops to prohibit rotation of the bushings in combination with the coated friction washers.