Radially Offset Engine Bearings to Prevent Skid and Fatigue
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Solution Overview
Problem
Bearing skid conditions in gas turbine engines occur due to inadequate load application, leading to either reduced performance or premature wear, as the load is either insufficient to prevent skid or excessive, causing fatigue.
Innovation Solution
The solution involves offsetting the bearing centerlines relative to the shaft centerline to redistribute the load, ensuring that the load applied to the bearings is above the threshold necessary to prevent skid, while avoiding excessive loads that could lead to fatigue, by adjusting the radial positions of the bearing races and rolling elements based on the stiffness of the engine components and operational parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the load applied to the bearing is increased to prevent skid, then the bearing stability is improved, but the bearing lifetime is reduced due to high fatigue and torque levels
Solution Approach 1:
The patent applies radial offset to the bearing centerline relative to the shaft centerline, changing the geometric parameter of the bearing position. This offset creates a preload force that optimizes the load distribution on the bearing, preventing skid while controlling fatigue levels to extend bearing lifetime.
2Duration of action of stationary object
If the load applied to the bearing is decreased to extend lifetime, then the bearing fatigue is reduced, but the bearing experiences skid condition
Solution Approach 1:
The patent modifies the bearing position by applying a radial offset to the bearing centerline relative to the shaft centerline. This geometric parameter change generates an optimal preload that prevents skid conditions while maintaining acceptable fatigue levels for extended bearing lifetime.
3Reliability
If the bearing centerline is offset from the shaft centerline to optimize load distribution, then the bearing skid is reduced, but the system complexity increases
Solution Approach 1:
The patent introduces asymmetry by offsetting the bearing centerline radially from the shaft centerline. This asymmetric positioning creates a preload force that optimizes load distribution on the bearing, preventing skid and improving operational reliability without requiring complex additional components.
Data Source
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AI summary
Aspects of the disclosure are directed to a rotatable shaft (202'), and a plurality of bearings (236', 246', 256') coupled to the rotatable shaft (202'), where the plurality of bearings (236', 246', 256') include a first bearing (236'), a second bearing (246'), and a third bearing (256'), where the first bearing (236') defines an axial first bearing centerline (Ab1'), where the second bearing (246') defines an axial second bearing centerline (Ab2'), where the third bearing (256') defines an axial third bearing centerline (Ab3'), and where the axial second bearing centerline (Ab2') is radially offset from the axial first bearing centerline (Ab1') and the axial third bearing centerline (Ab3').