Thermoplastic Aircraft Conduit Joint With Flush Internal Radius

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Solution Overview

Problem

The assembly of thermoplastic piping with connectors in aircraft fluid conduits results in radial deformation of the connector, leading to internal protrusions that can trap liquids and residues, degrading maintenance conditions and health safety.

Innovation Solution

A connector design with a beveled free longitudinal end that allows radial deformation during assembly, ensuring a constant internal radius at the interface with the piping, using a translational movement and controlled deformation to prevent fluid retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the connector is made of thermoplastic material to match the piping, then the assembly is lightweight and robust, but radial deformation during cooling creates internal protrusions that trap fluids

Engineering Contradiction:

Improverobustness of connector-piping assemblyVSAvoidinternal protrusions trapping fluids

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The connector's free longitudinal end is pre-configured with a beveled shape before assembly. This preliminary geometric configuration enables the material to deform radially inward during cooling in a controlled manner, ensuring the deformed end remains flush with the piping internal surface rather than creating protrusions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention utilizes the temperature-dependent physical properties of thermoplastic materials. During assembly, the piping is heated to become malleable and expand radially, allowing easy insertion of the connector. During cooling, the material undergoes controlled radial contraction, and the beveled geometry ensures this contraction eliminates protrusions rather than creating them.

Inventive Principle:

Principle #35Parameter changes

2Object-generated harmful factors

If the connector rigidity is increased to limit radial deformation, then less fluid trapping occurs, but the connector cannot adapt to thermal expansion and contraction

Engineering Contradiction:

Improvefluid entrapment zonesVSAvoidthermal adaptation of connector

Core Design Contradiction:

Object-generated harmful factorsVSAdaptability or versatility

Solution Approach 1:

The connector is designed with non-uniform geometry: the free longitudinal end has a beveled configuration that allows controlled radial deformation, while the main body maintains sufficient rigidity for structural integrity. This local differentiation enables the specific region subject to thermal stress to adapt while the overall connector remains robust.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The connector design embraces dynamic adaptation to thermal conditions. The beveled free longitudinal end is intentionally configured to deform radially during cooling, transforming from a potential source of protrusions into a feature that ensures flush alignment. This dynamic geometric adaptation allows the connector to maintain optimal geometry across temperature variations.

Inventive Principle:

Principle #15Dynamics

3Weight of moving object

If the piping is made thin-walled to reduce mass, then aircraft weight decreases, but the connection end is more difficult to assemble with the connector

Engineering Contradiction:

Improveaircraft massVSAvoidassembly difficulty of thin-walled piping

Core Design Contradiction:

Weight of moving objectVSEase of manufacture

Solution Approach 1:

The assembly process utilizes phase transition of the thermoplastic piping material from solid to softened state through heating. The connection end is heated to become malleable, allowing radial expansion that facilitates easy insertion of the connector. After assembly, cooling returns the material to its rigid state, creating a tight, integral connection. This thermal phase transition enables assembly of thin-walled piping without requiring increased wall thickness.

Inventive Principle:

Principle #36Phase transitions

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 solution ensures a robust, tight connection without internal protrusions, enhancing health maintenance and reliability of the conduits by maintaining a constant internal radius and preventing fluid retention.

Implementation Method 1

the connection end 11 of thermoplastic material is heated to become malleable and expand radially

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

During cooling, the connection end 101 radially retracts around the connection portion 121 of the connector 102 so as to snugly fit its shape

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentUS12447669B2Aircraft fluid conduit comprising thermoplastic piping and connector

Publication Date: 2025.10.21 AIRBUS ATLANTIC (SAS)

AI summary

A fluid conduit for aircraft, the conduit having a pipe made from thermoplastic material having a connection end which extends along a pipe axis and a connector which is intended to be mounted in the connection end by a translational movement along the pipe axis in a downstream direction, the connector having a joining portion which extends longitudinally along the connector axis and which is configured to extend into the connection end, the joining portion having a free longitudinal end which is chamfered, the free longitudinal end being configured to be radially deformed after the connector is mounted in the connection end, which has been thermally expanded beforehand, so that the conduit has an internal surface which has an internal radius which is substantially constant at the interface between the connector and the pipe.