Alternating Bump Foil Segmentation for Load Distribution
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Solution Overview
Problem
Foil bearings with dual rate spring structures face reliability issues due to increased load, as the number of support portions contacting the outer and inner surfaces simultaneously increases, leading to stress concentration and potential damage.
Innovation Solution
The foil bearing incorporates bump foils with first and second support portions that are alternately disposed in the rotation direction, allowing the number of support portions to increase sequentially with load, reducing stress concentration by utilizing additional support sections only when necessary, thereby enhancing the reliability of the foil bearing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the number of first support portions and second support portions simultaneously increases to support increased load, then the load bearing capacity is improved, but the stress concentration and reliability of each support portion deteriorates
Solution Approach 1:
The bump foil is segmented into multiple first support portions and second support portions that are alternately arranged in the rotation direction. This segmentation allows the load to be distributed across multiple discrete contact points rather than concentrating stress in a single continuous region, thereby maintaining reliability while increasing load bearing capacity.
Solution Approach 2:
The support portions are designed to dynamically engage based on load conditions. When load increases, additional first and second support portions sequentially contact the top foil and housing respectively, allowing the system to adapt its load distribution pattern dynamically rather than relying on a fixed static structure.
2Strength
If the number of support portions increases simultaneously in both directions, then the elastic support function is improved, but the stress distribution and reliability of individual portions deteriorates
Solution Approach 1:
The bump foil structure is divided into alternating first support portions (contacting top foil) and second support portions (contacting housing), creating discrete load transfer paths. This segmentation enables the elastic support function to be distributed across multiple independent contact regions, reducing stress concentration at any single location.
Solution Approach 2:
Different portions of the bump foil are designed with localized functions: first support portions are optimized for contacting the top foil while second support portions are optimized for contacting the housing. This local differentiation allows each support portion to be tailored for its specific contact interface, improving overall elastic support while maintaining individual portion reliability.
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 design effectively distributes the load by increasing the number of support portions in a controlled manner, reducing the risk of damage and maintaining reliability under increased load conditions, while suppressing self-excited vibrations and stress concentration.
Implementation Method 1
The bump foil is configured to elastically support the top foil by extending the first support portions and the second support portions in the rotation direction
Data Source
AI summary
The foil bearing includes a housing, a top foil, and bump foils. The bump foil includes first support portions that contact an outer circumferential surface of the top foil, second support portions that contact an inner circumferential surface of the housing, and coupling portions that couple the first support portions and the second support portions together such that the first support portions and the second support portions are disposed alternately in a rotation direction of a rotating body. When a load input from the rotating body increases, the bump foil is deformed to increase one of the number of the first support portions that contact the outer circumferential surface of the top foil and the number of the second support portions that contact the inner circumferential surface of the housing before increasing the other one of the numbers.