Thrust Bearing Top Foil Segmentation for Load Capability
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Solution Overview
Problem
The load capability of thrust foil bearings deteriorates due to increased flexure at intermediate portions between the inner and outer circumferential edges of the top foil piece, leading to reduced pressure and clearance, which is exacerbated by the need to maintain inclination flexibility for maximum load capability.
Innovation Solution
A thrust bearing design featuring a top foil with thin parts extending from the outer to the inner circumferential edge, allowing easy bending in the circumferential direction while maintaining radial rigidity, and a bump foil piece with alternating peak and valley parts to support the top foil and adjust inclination angles for optimal load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the top foil piece is made thinner to increase inclination flexibility, then the load capability increases, but the flexure at intermediate portions increases causing reduced fluid lubrication film pressure
Solution Approach 1:
The top foil piece is designed with non-uniform thickness, having a first thickness in the radial direction and a second thickness smaller than the first at the intermediate portion. This local variation in thickness allows the intermediate portion to have different mechanical properties (more flexible) compared to the edge portions, enabling it to accommodate flexure without compromising overall structural integrity or fluid pressure maintenance
Solution Approach 2:
The top foil piece is segmented into different thickness zones (first thickness region and second thickness region) to provide different functional characteristics in different areas, allowing the intermediate portion to flex independently while maintaining load-bearing capability at the edges
2Reliability
If the top foil piece is made thicker to reduce flexure at intermediate portions, then the fluid lubrication film pressure is maintained, but the inclination flexibility is reduced decreasing load capability
Solution Approach 1:
Instead of uniformly increasing thickness, the invention applies local thickness variation where only the intermediate portion has reduced thickness (second thickness) while other regions maintain greater thickness (first thickness), providing localized flexibility without compromising overall rigidity or fluid pressure
3Ease of operation
If the top foil piece is made thinner to reduce starting torque, then the ease of operation improves, but the structural integrity and load-bearing capacity are compromised
Solution Approach 1:
The non-uniform thickness design allows the intermediate portion to be thinner (reducing starting torque) while other portions maintain sufficient thickness for structural integrity, achieving both ease of operation and strength simultaneously through spatially differentiated properties
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 enhances load capability by limiting flexure at intermediate portions, reducing starting torque, and maintaining optimal inclination angles, thereby improving the bearing's load-carrying capacity and fluid lubrication film pressure.
Implementation Method 1
a flexible foil (thin metal sheet) in order to accept movement of the rotary shaft (movement in the axial direction of or inclination of the thrust collar) which occurs due to vibration or to impact, and the thrust foil bearing includes a foil structure which is provided under the bearing surface and flexibly supports the bearing surface
Implementation Method 2
the bearing clearance is formed so as to gradually decrease from the leading side toward the trailing side in the rotation direction of the thrust collar (the rotary shaft). Thus, when the thrust collar rotates from the large side (the leading side) toward the small side (the trailing side) of the bearing clearance, a lubricating fluid flows into a narrow part of the wedge-shaped bearing clearance, and the load capability of the thrust bearing is obtained
Data Source
Figure 1~2
Figure 3A~3B
Figure 3C~3D
AI summary
A thrust bearing (3, 3A, 3B) is a thrust bearing disposed facing a thrust collar (4) provided on a rotary shaft (1) and includes a top foil (10), a back foil (20) and a base plate (30). The back foil includes a plurality of back foil pieces (21). The top foil includes a plurality of top foil pieces (11, 50, 60). In addition, a leading side of the top foil piece in the rotation direction of the rotary shaft is provided with a fixed part (13) fixed to the base plate, the top foil piece is provided with a thin part (14, 16) in which a part is removed from the surface of the top foil piece facing the back foil piece, and the thin part extends from an outer circumferential edge to an inner circumferential edge or to a side edge of the top foil piece.