Aircraft Engine Wire Harness Shield Segmentation
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Solution Overview
Problem
Electrical wire harnesses in gas turbine engines face issues with current flow due to the conductivity of metallic fibers in protective sleeves, leading to potential electrical interference and safety concerns from relative movement and thermal expansion.
Innovation Solution
Incorporating breaks in the metal shield sleeve of the wire harness and establishing conductive contacts between the sleeve segments and engine case flanges to create electrically insulated sections, which divert current away from the harness and onto the engine structure, thereby grounding the system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous metal shield sleeve is used to protect the wire harness, then the protective coverage and shielding effectiveness are improved, but current flow along the harness increases causing electrical interference and safety concerns
Solution Approach 1:
The continuous metal shield sleeve is divided into multiple discrete segments spaced along the longitudinal direction of the wire harness. This segmentation breaks the continuous conductive path, preventing current from flowing along the entire length of the harness while maintaining protective shielding at each segment location. The segments are positioned to provide adequate coverage without creating continuous electrical conductivity along the harness.
2Object-generated harmful factors
If breaks are introduced in the metal shield sleeve to stop current flow, then electrical interference is reduced, but the protective coverage and continuous shielding are compromised
Solution Approach 1:
The shield is segmented into discrete sections that provide localized shielding protection. Each segment acts as an independent shielding element, and their collective arrangement along the harness provides comprehensive protection without requiring continuous connectivity. The spacing and positioning of segments are optimized to maintain overall shielding effectiveness while breaking current paths.
Solution Approach 2:
Non-conductive spacers or insulating materials are introduced between the metal shield segments to prevent electrical contact between adjacent segments. These intermediaries maintain the physical structure and spacing of the segments while ensuring electrical isolation, thereby preventing current flow between segments while preserving the protective function of each segment.
3Reliability
If multiple metal shield sleeves are used to enhance protection, then the shielding capability is improved, but the complexity of electrical insulation between sleeves increases
Solution Approach 1:
Multiple metal shield sleeves are arranged in a nested configuration where one shield is positioned inside another, sharing a common longitudinal axis. This nested arrangement provides enhanced protective coverage through multiple layers of shielding while minimizing the lateral space required. The concentric positioning simplifies the insulation requirements compared to side-by-side arrangements, as insulation is primarily needed in the radial direction between nested layers rather than laterally between multiple separate shields.
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 configuration effectively reduces electrical interference by redirecting current flow onto the engine structure, minimizing the risk of electrical issues and enhancing safety by ensuring current is directed away from the wire harness.
Implementation Method 1
a conductive contact between the at least one flange and at least one of the sleeve segments
Data Source
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AI summary
An aircraft engine (10) comprises an engine case (20) having at least one engine case flange (22). A harness of wires (30) extends in proximity to the engine case (20). The harness of wires (30) includes two or more metal shield sleeves (32) externally covering a bundle of wires (31) in a longitudinal direction, the metal shield sleeves (32) being at least partially electrically insulated from one another. A conductive contact (35) is between the at least one flange (22) and at least one of the metal shield sleeve (32).