Conductive Self-Lubricating Bushing for Aircraft Landing Gear
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing landing gear bushings for aerospace applications require periodic maintenance and sacrifice electrical conductivity for long service life, as they often use non-conductive materials like PTFE for self-lubrication, which impedes the conduction of electrical currents from lightning strikes or static electricity.
Innovation Solution
A bushing system with cylindrical and annular self-lubricating liners made from electrically conductive materials, such as aluminum-bronze alloy, infused with PTFE or PTFE fibers, that provides a maintenance-free, electrically conductive path through the bushing system, allowing for the dissipation of electromagnetic energy without the need for re-greasing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If self-lubricating liners made from non-conductive materials like PTFE are used, then maintenance-free operation is achieved, but electrical conductivity is lost
Solution Approach 1:
The bushing employs a composite structure combining a metal housing (aluminum or aluminum alloy) with self-lubricating liners (PTFE or PTFE-infused materials). The metal housing provides electrical conductivity while the PTFE liners provide self-lubrication, resolving the contradiction between maintenance-free operation and electrical conductivity through material composition.
Solution Approach 2:
The bushing is divided into distinct functional segments: the metal housing that conducts electricity and the self-lubricating liners that reduce friction. This segmentation allows each component to specialize in one function, with the conductive path through the housing maintaining electrical reliability while the liner interfaces provide maintenance-free lubrication.
2Reliability
If metal-to-metal contact is maintained for electrical conductivity, then electrical current conduction is achieved, but wear and maintenance requirements increase
Solution Approach 1:
The self-lubricating PTFE liners act as intermediary elements between the metal housing and the rotating shaft. These liners maintain electrical conductivity through the metal housing while providing a low-friction interface that reduces wear, thereby extending service life without requiring maintenance.
Solution Approach 2:
The combination of metal housing with PTFE liners creates a composite bushing that achieves both electrical conductivity (through the metal) and reduced wear (through the self-lubricating PTFE interface), resolving the contradiction between maintaining electrical contact and extending maintenance-free service life.
3Duration of action of moving object
If PTFE liners are used for self-lubrication, then wear is reduced, but electrical conductivity is impeded
Solution Approach 1:
The bushing separates the wear resistance function (handled by PTFE liners) from the electrical conductivity function (handled by metal housing). This segmentation allows PTFE to provide excellent wear resistance at the sliding interface while the metal housing maintains the electrical conductive path, resolving the contradiction between wear resistance and electrical conductivity.
Solution Approach 2:
The composite structure of metal housing with PTFE liners enables the system to simultaneously achieve wear resistance (from PTFE) and electrical conductivity (from metal), as each material performs its optimal function in the composite assembly.
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 bushing system effectively conducts electrical currents equivalent to lightning strikes while maintaining low wear and extended operational life, meeting the requirements for weight management, structural strength, and electrical isolation in aircraft systems.
Implementation Method 1
one or more cylindrical self-lubricating liners or arcuate segments thereof are disposed in one or more of the cylindrical recesses
Implementation Method 2
The bushing system has an electrically conductive path that is configured to conduct electrical current (e.g., electrical current has a voltage equivalent to that of a lightning strike) therethrough
Data Source
AI summary
A bushing for aircraft landing gear includes a cylindrical wall having an interior surface defining a bore extending between a first and second axial end thereof and a cylindrical recess extending into the interior surface. The bushing includes a cylindrical self-lubricating liner which is substantially flush with the interior surface is disposed in the recess. The cylindrical wall includes a flange that has an annular recess that receives an annular self-lubricating liner that has a planar axial bearing surface. The planar axial bearing surface is coplanar with an inboard axial surface of the flange. The bushing has an electrically conductive path that conducts electrical current and that extends around the cylindrical self-lubricating liner and the annular self-lubricating liner and through the cylindrical wall and the flange.