Variable Stator Vane Bearing Assembly Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Variable stator vane bushes in gas turbine engines experience wear due to bearing forces and rotation, necessitating an improved wear-resistant design that fits within the assembly constraints of the variable stator vane assembly.
Innovation Solution
A bearing arrangement featuring a shaft with a recess, an annular first bush with inner portions, and a second bush that engages the recess, allowing for two load paths to transmit loads from the shaft to the bearing housing, with the second bush extending the effective length of the bearing without requiring the shaft to extend along the entire length, and an inner shroud that is compressed and allowed to return to its original radius for assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single bush is used in the bearing arrangement, then the structure is simple, but the bearing length is limited and contact stress is high leading to wear
Solution Approach 1:
The bearing arrangement is divided into two separate bushes: a first bush that contacts the shaft and a second bush that contacts the bearing housing. This segmentation allows each bush to be optimized for its specific function and enables a longer effective bearing length without increasing the complexity of a single component
Solution Approach 2:
The bearing load path is extended in the axial dimension by introducing a second bush in series with the first bush. This dimensional extension increases the effective bearing length and distributes contact stress over a longer distance, reducing wear while maintaining structural simplicity
2Length of stationary object
If the shaft extends along the entire bearing length, then the bearing length can be increased, but the manufacturing complexity and assembly difficulty increase
Solution Approach 1:
The bearing length is segmented into two portions: one portion supported by the first bush and another portion supported by the second bush. This allows the shaft to maintain its standard length while achieving an extended effective bearing length through the series arrangement of the two bushes
Solution Approach 2:
The second bush acts as an intermediary element that extends the bearing length without requiring the shaft to extend. It mediates between the shaft and the bearing housing, providing additional bearing surface area and distributing loads over a longer effective length
3Ease of manufacture
If the inner shroud is highly compressed during assembly, then the bushes can be installed, but the assembly process becomes difficult and component damage risk increases
Solution Approach 1:
The first and second bushes are pre-installed into the bearing housing before the inner shroud is compressed into place. This preliminary action ensures proper bush positioning and reduces the compression force needed during assembly, as the bushes are already in their final positions and do not need to be forced into a compressed state
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A bearing arrangement comprising a shaft with a recess in its end, a bearing housing, an annular first bush comprising an inner first portion and an inner second portion and a second bush that engages the recess of the shaft. The first bush bears against the bearing housing. The shaft engages the inner first portion of the first bush. The second bush engages the inner second portion of the first bush.