Barrel Nut Retainer With Spring Clip for Fastener Alignment

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Solution Overview

Problem

Barrel nuts in aerospace applications are difficult to align with fasteners due to unrestricted rotation and translation when not attached, leading to time-consuming assembly processes and risks of misalignment and loss.

Innovation Solution

A barrel nut retainer that securely fits within a component's bore, providing an interference fit with the barrel nut, a head portion for alignment, and a spring clip mechanism for easy installation and retention, allowing pre-installation of barrel nuts in components before assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If barrel nuts are installed freely in bores without retainers, then installation is simple and quick, but alignment with fasteners becomes difficult and time-consuming due to unrestricted rotation and translation

Engineering Contradiction:
Improveease of barrel nut installationVSAvoidalignment time
Core Design Contradiction:
Ease of operationVSLoss of time

Solution Approach 1:

The retainer is pre-installed in the bore with the barrel nut secured in a predetermined aligned position before the fastener is inserted. This preliminary positioning eliminates the need for time-consuming alignment operations during final assembly, as the barrel nut is already oriented correctly to receive the fastener.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The retainer acts as an intermediary device between the bore and the barrel nut. It provides a mounting structure that holds the barrel nut in the correct position and orientation within the bore, mediating the connection between the stationary bore and the movable barrel nut to ensure proper alignment.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If barrel nuts are restricted from rotating and translating, then alignment with fasteners is improved, but the barrel nut cannot be easily installed or removed

Engineering Contradiction:
Improvealignment precisionVSAvoidease of installation and removal
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The retainer employs a spring clip mechanism that is flexible during installation but provides rigid constraint during operation. The spring clip can be compressed to allow the retainer to be inserted into the bore with the barrel nut, then springs back to secure the barrel nut in place, providing dynamic adaptability that facilitates both installation and secure retention.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The retainer is designed as a separate component from both the bore and the barrel nut. This segmentation allows the retainer to be independently manufactured and installed, providing the alignment function without requiring modification of the barrel nut or the bore, thus maintaining ease of manufacture while achieving precision alignment.

Inventive Principle:
Principle #1Segmentation

3Reliability

If retainers are used to secure barrel nuts, then alignment and retention are improved, but the number of parts and assembly complexity increases

Engineering Contradiction:
Improvebarrel nut retentionVSAvoidnumber of parts
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The retainer combines multiple functions into a single component: it provides alignment features to ensure proper orientation of the barrel nut, retention features (spring clip) to secure the barrel nut in place, and installation features that allow easy mounting. This merging of functions reduces the need for multiple separate components while maintaining reliability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The retainer is designed as a universal component that can be applied to various bore and barrel nut configurations. The standardized retainer design provides alignment, retention, and installation capabilities across different applications, reducing overall system complexity by using a common solution rather than custom-designed components for each specific case.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Productivity

If barrel nuts are pre-installed in components, then final assembly time is reduced, but the risk of foreign object ingress into the bore increases

Engineering Contradiction:
Improveassembly speedVSAvoidforeign object ingress
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The barrel nut and retainer are pre-assembled as a unit before insertion into the bore. This preliminary assembly allows the barrel nut to be positioned and secured in the correct orientation in advance, enabling faster final assembly while the retainer simultaneously provides protection against foreign object ingress during the pre-installation and final assembly processes.

Inventive Principle:
Principle #10Preliminary action

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 simplifies the assembly process by ensuring barrel nuts are pre-installed in the correct position, reducing assembly time, preventing foreign object ingress, and minimizing the risk of barrel nut loss, while allowing the use of off-the-shelf barrel nuts without modifying existing designs.

Implementation Method 1

the aperture has dimensions configured to form an interference fit with the barrel nut

Methodology Applied
Scientific EffectInterference fit: Friction

Data Source

PatentEP3889450B1A barrel nut retainer
Publication Date: 2024.05.01 AIRBUS OPERATIONS LTD
  • EP3889450B1 patent drawingFigure 1
  • EP3889450B1 patent drawingFigure 2A~2B
  • EP3889450B1 patent drawingFigure 3A~3B

AI summary

A barrel nut retainer for retaining a barrel nut in a bore of a component, the retainer comprising: a body adapted to fit within a bore and extending between a first end and a second end, and wherein the body has an aperture between the first end and second end configured to receive a barrel nut, and a head portion at the first end of the body, the head portion adapted to sit over an open end of the bore.