Bearing Flexure Mounted Thrust Bearings for Radial Load Decoupling
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Solution Overview
Problem
Thrust bearings in rotorcraft gear systems face challenges in decoupling radial loads and managing heat dissipation during high-speed operations, leading to potential adverse bearing performance.
Innovation Solution
A gear system design featuring a thrust bearing with a bearing flexure that has greater axial stiffness than radial stiffness, allowing radial loads to be decoupled and facilitating thermal communication with the housing for effective heat dissipation, thereby maintaining thrust bearing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thrust bearings are directly mounted on the shaft, then the structure is simple, but radial loads cannot be decoupled and bearing temperature increases during high-speed operations
Solution Approach 1:
A bearing flexure is introduced as an intermediary component between the thrust bearing and the shaft. This flexure includes a cylindrical cage with radially extending struts that provide mechanical flexibility while thermally coupling the thrust bearing to the housing, enabling heat dissipation without direct rigid mounting to the shaft.
Solution Approach 2:
The bearing support structure is segmented into separate functional components: the bearing flexure (with cage and struts) handles radial load decoupling and thermal management, while the thrust bearing focuses solely on axial load support. This segmentation allows each component to optimize its specific function.
2Reliability
If thrust bearings are directly mounted on the shaft, then installation is simple, but radial loads interfere with thrust bearing operation
Solution Approach 1:
The bearing flexure acts as a mediator that absorbs and isolates radial loads through its flexible strut structure, preventing these loads from being transmitted to the thrust bearing while maintaining the thrust bearing's connection to the rotating assembly.
Solution Approach 2:
The bearing flexure utilizes a flexible cylindrical cage structure with thin radially extending struts that can deform to accommodate radial displacements, effectively isolating the thrust bearing from radial load variations while maintaining structural integrity.
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
The design effectively decouples radial loads and enhances heat dissipation, ensuring reliable thrust bearing performance even during high-speed operations.
Implementation Method 1
The outer race of the thrust bearing is in thermal communication with the housing
Implementation Method 2
The bearing flexure has an axial stiffness that is greater than its radial stiffness
Data Source
AI summary
A gear system includes a gear assembly having a shaft that is at least partially disposed within a housing of the gear system. A thrust bearing has inner and outer races with the outer race coupled to the housing. A bearing flexure is disposed between the inner race of the thrust bearing and the shaft. The bearing flexure includes a cylindrical cage having at least one shaft journal ring and a plurality of circumferentially distributed axially extending fingers coupled thereto with the shaft journal ring coupled to the shaft. A cylindrical bearing journal has inner and outer surfaces with the outer surface coupled to the inner race of the thrust bearing. Each of a plurality of circumferentially distributed radially extending struts extends between one of the fingers and the inner surface of the cylindrical bearing journal. The bearing flexure has an axial stiffness that is greater than its radial stiffness.