Thrust Foil Bearing Base Plate for Consistent Wedge Gap
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Solution Overview
Problem
The existing thrust foil bearings face a challenge in maintaining a consistent gap between the top foil and the thrust collar, leading to reduced load capacity due to differences in height between the inner and outer circumferences of the base plate, which affects the formation of a wedge-shaped fluid lubricating film.
Innovation Solution
The thrust foil bearing features a base plate with inclined surfaces that become shallower radially outward, supporting divided regions of the back foil through slits, and a method for manufacturing this base plate using press working with dies to form the inclined surfaces, ensuring a consistent support for the back foil pieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a back foil having a certain height is installed on an inclined surface inclined with respect to a flat surface extending in a direction orthogonal to an axial direction of a base plate, then a wedge-shaped gap between the top foil and the thrust collar is formed, but a difference in height between inner and outer circumferences of the base plate occurs, causing the gap to become large on the outer peripheral side
Solution Approach 1:
The back foil is divided into multiple back foil pieces arranged circumferentially, with each piece having a different height corresponding to its radial position. This segmentation allows each piece to be optimized for its specific location, maintaining consistent gap dimensions across the entire bearing surface while still forming the wedge-shaped lubricating film.
Solution Approach 2:
Different portions of the back foil are given different heights based on their radial positions. The back foil pieces at the outer circumference are made shorter than those at the inner circumference, creating a locally optimized structure that compensates for the base plate's height difference and maintains uniform gap spacing throughout the bearing.
2Shape
If the gap between the top foil and the thrust collar becomes large on the outer peripheral side, then the wedge-shaped gap formation is achieved, but the load capacity of the thrust foil bearing is affected
Solution Approach 1:
By dividing the back foil into multiple pieces with radially varying heights, the structure enables consistent gap formation across different radial positions. This ensures that the wedge-shaped lubricating film can be properly formed at all locations, maintaining adequate load capacity throughout the bearing surface including the outer peripheral regions.
Solution Approach 2:
The height parameter of the back foil pieces is varied according to radial position, with outer circumference pieces being shorter. This parameter change compensates for the increasing gap tendency at the outer radius, ensuring that the effective lubricating film thickness and load-bearing capability remain consistent across the entire bearing surface.
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 configuration enhances the load capacity of the thrust foil bearing by maintaining a consistent gap and facilitating the formation of a fluid lubricating film, improving the bearing's performance.
Implementation Method 1
a lubricating fluid is introduced between the top foil piece and the thrust collar. This lubricating fluid forms a wedge-shaped fluid lubricating film between the top foil piece and the thrust collar
Implementation Method 2
a method for manufacturing a base plate of a thrust foil bearing... forming the plurality of inclined surfaces by press working
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A thrust foil bearing (3) includes a base plate (30) including an insertion hole (30a) through which a rotating shaft is inserted and a support surface (31) disposed around the insertion hole (30a) on one side of the insertion hole (30a) in an axial direction, and a back foil (20) disposed on the support surface (31), in which the support surface (31) has a plurality of inclined surfaces (31a to 31d) of which inclination angles inclined toward the other side of the base plate (30) in the axial direction become shallower in order toward an outside of the insertion hole (30a) in a radial direction, and the back foil (20) is divided into a plurality of divided regions (25) in the radial direction by a slit (24), and the plurality of divided regions (25) are supported by the plurality of inclined surfaces (31a to 31d).