Conductive Bushing Assembly for Fuel Tank Grounding
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Solution Overview
Problem
In the aerospace industry, existing bushing technologies require tight tolerances to ensure proper grounding of components in fuel tanks, leading to increased manufacturing costs due to the need for precise engagement between bushings and fuel tank walls, especially when dealing with carbon fiber reinforced polymers.
Innovation Solution
The development of an electrically conductive bushing assembly with a middle tubular portion having a lower longitudinal compressive strength than the end portions, which compresses between the end portions to create a through-bore for receiving a fastener, ensuring adequate grounding and reducing manufacturing costs by allowing for more flexible installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing bushing technology is used to ensure proper grounding of components in fuel tanks, then electrical grounding reliability is improved, but manufacturing precision requirements increase and manufacturing costs increase
Solution Approach 1:
The bushing material's physical properties are changed by selecting a material with a coefficient of thermal expansion greater than that of the carbon fiber reinforced polymer fuel tank wall. This parameter change allows the bushing to expand and contract with temperature variations, maintaining consistent engagement and electrical grounding reliability without requiring tight manufacturing tolerances.
Solution Approach 2:
The invention uses composite material selection where the bushing is made from a material that combines electrical conductivity with a specific coefficient of thermal expansion. This composite material property enables the bushing to function both as an electrical ground path and as a component that adapts to thermal cycling in the fuel tank environment, resolving the contradiction between reliability and manufacturing precision.
2Reliability
If existing bushing technology is used to ensure proper grounding of components in fuel tanks, then electrical grounding reliability is improved, but manufacturing costs increase
Solution Approach 1:
By changing the material parameter (coefficient of thermal expansion) of the bushing, the invention eliminates the need for costly tight tolerance manufacturing processes. The bushing naturally compensates for dimensional variations through thermal expansion, allowing for more relaxed and cost-effective manufacturing while maintaining grounding reliability.
Solution Approach 2:
The bushing material's thermal expansion properties enable it to self-adjust its dimensions in response to temperature changes within the fuel tank. This self-service mechanism maintains reliable electrical grounding without requiring precision manufacturing or additional adjustment mechanisms, thereby reducing manufacturing costs.
3Reliability
If tight tolerances are required for bushing engagement with fuel tank wall, then electrical grounding reliability is improved, but device complexity increases
Solution Approach 1:
The invention changes the material parameter (coefficient of thermal expansion) to create a self-compensating system. This eliminates the need for complex tolerance control mechanisms and procedures, simplifying the overall device while maintaining grounding reliability through the material's inherent thermal response.
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 assembly effectively ensures electrical grounding of components to fuel tanks while reducing manufacturing costs by allowing for more flexible installation and reduced tolerance requirements, preventing sparking and ensuring a secure, conductive interface.
Implementation Method 1
the middle tubular portion is configured to be compressed longitudinally between the end portions when the bushing assembly is utilized to mount a component to an object
Implementation Method 2
When the feedthrough is compressively secured to the structure, the bushing expands radially between the first diameter and the second diameter to maintain at least one contact point between the fastener and the structure
Implementation Method 3
ensuring that components that extend through the wall of a fuel tank are sufficiently grounded electrically to the wall of the fuel tank, so as to avoid sparking
Data Source
Figure 1~2
Figure 3~4
Figure 5~8
AI summary
Bushing assemblies 16 include a first tubular end portion 50, a second tubular end portion 52, and a middle tubular portion 54. The middle tubular portion has a longitudinal compressive strength that is less than that of the end portions. In some embodiments, the middle tubular portion is constructed of braided sleeving. Also disclosed are bushing assembly kits, apparatuses that include bushing assemblies, such as aircraft, and associated methods of utilizing bushing assemblies.