Axial Case Ring for Variable Vane Thrust Bushing Contact
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In turbofan gas turbine engines, the reduction in bushing contact area due to increased vane counts and diminishing radii in compressor stages leads to increased friction and potential engine stall, as the variable vane system's movement is hindered by reduced circumferential spacing, making it difficult to maintain efficient and stable operation across the full speed range.
Innovation Solution
The introduction of an integral tab in the compressor case to increase the contact area between the thrust bushing and the casing, achieved by modifying the bore configuration to include a penny bore, bushing bore, and spindle bore with shared axes, and using a thrust bushing with an inner diameter equal or greater than the spindle bore, allowing for enhanced rotatability of the vane assemblies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the vane count is increased to improve compressor performance, then the compressor efficiency is improved, but the bushing contact area is reduced leading to increased friction
Solution Approach 1:
The patent introduces an axial dimension to the bushing contact area by creating a stepped bore structure with multiple axial positions. Instead of relying solely on circumferential contact area, the thrust bushing now contacts the casing at multiple axial levels (first axial position and second axial position), effectively adding a dimensional approach to increase contact area in a space-constrained environment.
2Quantity of substance
If the radius is diminished to accommodate more vanes, then the vane count is increased, but the circumferential spacing is reduced causing increased friction
Solution Approach 1:
The patent compensates for reduced circumferential spacing by utilizing the axial dimension. The stepped bore structure allows the thrust bushing to engage the casing at different axial positions, effectively increasing the contact area without requiring additional circumferential space. This enables higher vane counts while maintaining adequate friction characteristics.
3Device complexity
If the contact area is reduced to accommodate space constraints, then the device complexity is reduced, but the friction increases preventing vane movement
Solution Approach 1:
The patent segments the bore structure into multiple distinct sections (first bore section and second bore section) at different axial positions. Each section provides a contact surface for the thrust bushing, distributing the load and reducing friction across multiple segmented contact zones rather than a single large contact area.
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 reduces frictional forces required for vane rotation, thereby preventing engine stall and ensuring stable operation by increasing the contact area and minimizing wear, even in space-constrained environments.
Implementation Method 1
low friction material thrust bushings are placed between the vane outer penny and the compressor case penny bore
Data Source
AI summary
The bearing surface between a thrust bushing and a boss/or face is increased with the addition of a ring or tab that extends radially into a casing bore configured to receive a bushing and cooperating spindle of a variable stator/guide vane. The addition of the ring adds additional bearing surface area without increasing the size of the vane penny, reducing spindle diameter or reducing the bushing bore diameter.