Service Tube Locking Assembly for Vibration-Resistant Threaded Joints
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Solution Overview
Problem
Threaded connections in turbine engines are prone to loosening due to vibrations, impacts, and thermal loads, leading to potential oil leakage and mechanical instability.
Innovation Solution
A service tube assembly with a locking assembly that includes a locking member and a mechanical fastener to prevent rotational loosening, ensuring secure engagement between the service tube and the mating part, even under thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If threaded connections are used between service tubes and engine components, then assembly and installation are simplified, but the connections are susceptible to loosening due to vibrations, impacts, and thermal loads
Solution Approach 1:
The locking assembly is divided into distinct functional components: a locking member with engagement features, a fastening mechanism, and a biasing element. This segmentation allows each component to perform its specific function while maintaining overall system reliability and ease of assembly.
Solution Approach 2:
The locking assembly is pre-configured with engagement features and biasing elements that automatically engage with the threaded connection before operational stresses occur. This preliminary preparation ensures that the connection is locked and secured against loosening from vibrations, impacts, and thermal loads before these forces are applied.
2Reliability
If a locking assembly is added to prevent loosening, then connection stability is improved, but device complexity increases
Solution Approach 1:
The locking assembly integrates multiple functions into a single unified structure: the locking member combines engagement features with the fastening mechanism, while the biasing element is incorporated directly into the assembly. This merging reduces the number of separate components and simplifies the overall structure while maintaining connection stability.
Solution Approach 2:
The locking assembly incorporates a biasing element that automatically maintains engagement pressure on the threaded connection without requiring external adjustment or monitoring. The assembly self-regulates to prevent loosening from vibrations and thermal loads, eliminating the need for additional complex control systems or maintenance interventions.
3Object-affected harmful factors
If the locking assembly uses a biasing element to maintain engagement pressure, then resistance to vibrations and thermal loads is improved, but manufacturing complexity increases
Solution Approach 1:
The biasing element is designed to operate within specific force and displacement parameters that are optimized for the expected vibration and thermal load conditions. By carefully selecting the spring rate, preload force, and engagement geometry, the assembly achieves effective resistance to harmful factors while using standard manufacturing processes and off-the-shelf components.
Data Source
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AI summary
A service tube assembly (30) for an aircraft engine (10), comprising: a service tube (32) having a threaded end portion (32b), an opposed end portion (32") and an annular tube surface (32d) proximate to the threaded end portion (32b); a housing (34) having an outer surface (34b) defining a tube socket (34a) extending in the outer surface (34b), and a ramp (R) extending toward the tube socket (34a) so as to define an engagement direction (E), the tube socket (34a) engaged with the threaded end portion (32b) of the service tube (32); a locking member (50) having a bottom surface (50b) disposed against the ramp (R) and an engagement surface (52) facing toward the service tube (32), the locking member (50) slidable along the ramp (R) in the engagement direction (E) between a first member position in which the engagement surface (52) is spaced from the annular tube surface (32d) and a second member position in which the engagement surface (52) contacts the annular tube surface (32d); and a fastener (60) releasably holding the locking member (50) against the ramp (R).