Air Foil Bearing with Variable Top Foil Thickness for Load Stability
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Solution Overview
Problem
Traditional air foil bearings face challenges in enhancing load bearing capacity and stability, particularly at high rotational speeds, due to limited air pressure and susceptibility to vibration and impact, which leads to unstable behavior and increased friction-generated heat.
Innovation Solution
The air foil bearing design incorporates a cylindrical bearing housing with a first foil of bump foils and a second foil of top foils, where at least one top foil is thicker than the others, configured as leaf springs with varying thickness regions to provide enhanced load support and vibration absorption, and the bump foils are arranged to correspond with the top foils to maintain uniform pressure and reduce friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the total pressure of air is increased to improve load bearing capacity, then the load bearing capacity is improved, but the device complexity increases due to the need for additional pressure increase structures
Solution Approach 1:
The top foils are designed with non-uniform thickness, where specific portions have greater thickness than others. This local variation in thickness creates differential elastic deformation and pressure distribution among the top foils, effectively increasing the total air pressure and load bearing capacity without requiring additional external pressure increase structures.
Solution Approach 2:
The invention changes the geometric parameter of the top foils by varying their thickness. This parameter change directly affects the elastic properties and pressure generation capability of the foils, enabling the system to achieve higher load bearing capacity through structural modification rather than adding complex pressure control mechanisms.
2Productivity
If the rotational speed of the rotating member is increased beyond critical speed, then the productivity is improved, but severe vibration and impact are generated that prevent proper support of rotation
Solution Approach 1:
By making specific portions of the top foils thicker than others, the invention creates non-uniform elastic characteristics that help distribute and dampen vibrational forces. This local variation in foil properties enhances the system's ability to absorb and dissipate vibration and impact energies, maintaining stability at high rotational speeds.
Solution Approach 2:
The thicker portions of the top foils act as pre-configured cushioning elements that are specifically positioned to absorb and dampen vibrations and impacts before they can cause severe instability. This beforehand cushioning capability allows the bearing to maintain proper support function even when operating beyond traditional critical speeds.
3Force
If sliding friction is generated between the top foil and bump foil to damp the radial load, then the load damping is improved, but the amount of heat generated by friction increases
Solution Approach 1:
The invention changes the thickness parameter of the top foils to create optimal elastic deformation characteristics. This parameter optimization allows the foils to provide sufficient load damping through controlled sliding friction while minimizing excessive frictional heat generation by preventing overly rigid or overly flexible conditions.
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 improves the load bearing capacity and stability of the rotating member, effectively absorbs vibration and impact, and minimizes heat generation from friction during rotation by maintaining uniform pressure and support.
Implementation Method 1
a high-pressure air layer may be formed between the rotating member and the top foil
Implementation Method 2
an air foil bearing is a bearing that supports a shaft by forming a high-pressure air layer between a top foil and the shaft
Implementation Method 3
sliding friction may be generated between the top foil and the bump foil. Due to the sliding friction, the load applied in the radial direction of the rotating member may be damped
Implementation Method 4
a portion of at least one of the plurality of top foils of the second foil is thicker than the other top foils of the plurality of top foils
Data Source
AI summary
An air foil bearing includes a bearing housing having a cylindrical shape that forms an accommodation space in a middle thereof for a rotating shaft, rotor, or journal; a first foil including a plurality of bump foils, which are arranged along an inner wall surface of the accommodation space of the bearing housing; and a second foil including a plurality of top foils, which are arranged in a circumferential direction along an inner circumference of the bearing housing to correspond to the plurality of bump foils and to support the rotating shaft, rotor, or journal. A portion of at least one of the plurality of top foils of the second foil is thicker than the other top foils of the plurality of top foils.