Elliptical Sleeve Fastener for Single-Sided Misalignment Assembly

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Solution Overview

Problem

Existing connection systems in the aeronautical sector struggle with misalignment issues, inability to control load transmission, and require access from both sides during assembly and dismantling, leading to complex and inefficient connections.

Innovation Solution

A connection system with a threaded bolt and a sleeve having a tapered outer surface transitioning from an elliptic to circular cross-section, allowing misaligned holes to be aligned and facilitating assembly and dismantling, while transferring loads through a fastening element.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a threaded bolt connection is used, then the connection can be dismantled, but the elements must be precisely aligned and both sides must be accessible

Engineering Contradiction:
Improvedismantling accessibilityVSAvoidalignment precision
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The sleeve's cross-sectional shape changes along its length, transitioning from elliptical at the rear to circular at the front. This parameter change allows the sleeve to be inserted through misaligned holes in elliptical form, then transform to a circular shape that aligns and centers the connected elements, resolving both the alignment precision and dismantling accessibility requirements

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The sleeve acts as an intermediary element between the threaded bolt and the elements to be connected. It receives the misaligned holes, transforms their relative positions through its shape transition, and outputs aligned holes, thereby mediating the alignment problem while allowing single-sided access for assembly and dismantling

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If a clearance fit connection is used, then assembly is simpler, but load transfer is poor due to loose fit

Engineering Contradiction:
Improveassembly simplicityVSAvoidload transfer capacity
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The sleeve performs preliminary alignment action during insertion, forcing the holes into correct relative positions before the threaded bolt is fully assembled. This preliminary alignment ensures that subsequent load transfer occurs through properly positioned elements, maintaining both assembly simplicity and load transfer strength

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The sleeve's cross-sectional geometry changes from elliptical to circular along its length, creating a progressive alignment effect that guides misaligned holes into proper registration, thereby enabling simple assembly while ensuring strong load transfer through accurate positioning

Inventive Principle:
Principle #35Parameter changes

3Productivity

If misaligned holes are connected directly, then assembly is faster, but alignment errors cause assembly difficulties

Engineering Contradiction:
Improveassembly speedVSAvoidassembly feasibility
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The sleeve's varying cross-sectional shape (elliptical to circular) accommodates misaligned holes during rapid insertion, then automatically corrects the alignment as it progresses, enabling both fast assembly and proper alignment without requiring pre-alignment operations

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The sleeve serves as a mediator that accepts misaligned input from the holes and produces aligned output, allowing rapid assembly of misaligned elements while automatically correcting alignment errors through its shape-transforming action

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4636265A1Connection system with an elliptical cross-section
Publication Date: 2025.10.22 AIRBUS OPERATIONS SL
  • EP4636265A1 patent drawingFigure 1
  • EP4636265A1 patent drawingFigure 2A~2D
  • EP4636265A1 patent drawingFigure 3A~3E

AI summary

The invention relates to a connection system for connection between a front element (1) and a rear element (2), comprising a threaded bolt (4) with a rear portion (4.1) and a front portion (4.2), a sleeve (5) concentrically around the threaded bolt (4) which is tapered towards the rear portion (4.1) of the threaded bolt, a housing (7) for the sleeve (5), and a fastening element (6) configured to be threaded with the threaded bolt (4), characterized in that the sleeve (5) has a generally elliptical rear cross-section (5.3).