Adjustable Service Tube Joint for Gas Turbine Tolerance Stack-Up
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In gas turbine engines, tolerance stack-up leads to undesirable stresses in service tubes during cold assembly due to misalignment of tube ends with their points of attachment, necessitating the use of heavier, more ductile materials to accommodate deformation, which compromises the engine's weight and material choice.
Innovation Solution
A service tube assembly with an adjustable joint featuring a male/female connection and a threaded flange that allows for adjustable positioning and clamping of abutment surfaces, reducing stresses and accommodating tolerance stack-up and thermal expansion, enabling the use of lighter, stiffer materials like titanium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional fixed service tubes are used, then material strength and ductility are improved, but engine weight increases
Solution Approach 1:
The service tube assembly incorporates an adjustable joint that allows dynamic positioning of the tube ends relative to each other. The second tube can be positioned at different locations along the second fitting through the adjustable joint, enabling the system to adapt to tolerance variations without requiring overly ductile or heavy materials. This dynamic adjustability resolves the contradiction by eliminating the need for excessive material strength while maintaining proper alignment.
Solution Approach 2:
The invention changes the positional parameter of the service tube connection points through the adjustable joint mechanism. By allowing the second tube to be positioned at different locations along the fitting, the system compensates for tolerance stack-up and misalignment issues that would otherwise require heavier, more ductile materials. This parameter adjustment enables the use of lighter, stiffer materials like titanium.
2Weight of moving object
If service tubes are made stiffer to reduce weight, then weight decreases, but adaptability to tolerance variations worsens
Solution Approach 1:
The adjustable joint introduces dynamic positioning capability that compensates for the reduced adaptability of stiffer materials. The mechanism allows the second tube to be repositioned along the fitting to accommodate tolerance variations, enabling the use of stiffer, lighter materials without sacrificing the ability to adapt to manufacturing tolerances and thermal expansion.
Solution Approach 2:
The adjustable joint acts as an intermediary mechanism between the first and second tubes. It mediates the connection by providing an adjustable interface that absorbs tolerance variations and misalignment, allowing stiffer tube materials to be used while maintaining adaptability through the intermediary adjustment mechanism.
3Device complexity
If fixed tube connections are used, then device complexity is reduced, but installation stress increases
Solution Approach 1:
The adjustable joint provides dynamic positioning capability that eliminates installation stresses caused by misalignment. By allowing the second tube to be positioned at different locations along the fitting, the system accommodates tolerance stack-up without creating undesirable stresses in the tubes during cold assembly, while adding only minimal complexity to the connection mechanism.
Data Source
AI summary
A gas turbine engine has a service tube assembly including an adjustable joint having a flange axially movable along an end fitting having a male/female connection with a mating part. The flange is threadably engaged with the end fitting to provide for the adjustment of the position of the flange along the end fitting.