Radially Offset Engine Bearings to Prevent Skid
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Solution Overview
Problem
Bearings in engines, such as those powering aircraft and industrial equipment, face challenges in maintaining optimal load to prevent skid conditions due to misalignment caused by wear, thermal expansion, or component tolerances, where insufficient load leads to sliding and excessive load results in shortened bearing lifetime.
Innovation Solution
A system where bearings are radially offset relative to the shaft and other bearings to apply a load that reduces the propensity for skid, with the offset amount determined by factors like stiffness, temperature range, and component tolerances, ensuring a preload greater than a threshold is applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the load applied to a bearing is low, then the bearing experiences skid condition where rolling elements slide against the races, but if the load applied to a bearing is high, then the bearing experiences shortened lifetime due to high level of fatigue and increased torque levels
Solution Approach 1:
The patent applies radial offset to the bearing centerline relative to the shaft centerline, which changes the geometric parameters of the bearing-shaft system. This offset creates a predetermined load on the bearing that maintains rolling element contact with the races without causing excessive fatigue, thereby resolving the contradiction between preventing skid and extending bearing lifetime
Solution Approach 2:
The bearing is pre-loaded through radial offset during the design and assembly phase, before the bearing enters service. This preliminary action ensures that the bearing operates with optimal load conditions from the start, preventing skid conditions while avoiding excessive loads that would reduce lifetime
2Ease of manufacture
If bearings are aligned with the shaft centerline, then the structure is simple and manufacturing is easier, but misalignment caused by wear, thermal expansion, or component tolerances leads to skid conditions
Solution Approach 1:
The patent deliberately introduces asymmetry by offsetting the bearing centerline radially from the shaft centerline. This asymmetric configuration compensates for misalignment issues caused by wear, thermal expansion, and component tolerances, ensuring reliable bearing operation while maintaining manufacturability through a straightforward offset design
Data Source
AI summary
Aspects of the disclosure are directed to a rotatable shaft, and a plurality of bearings coupled to the rotatable shaft, where the plurality of bearings include a first bearing, a second bearing, and a third bearing, where the first bearing defines an axial first bearing centerline, where the second bearing defines an axial second bearing centerline, where the third bearing defines an axial third bearing centerline, and where the axial second bearing centerline is radially offset from the axial first bearing centerline and the axial third bearing centerline.