Segmented Thrust Foil Bearing for Uniform Lubrication 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 insertion holes and support surfaces that have inclined surfaces with shallower angles towards the outside in the radial direction, and the back foil is divided into regions supported by these surfaces, with a step and slit configuration to ensure even load distribution and gap maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single inclined surface is used to support the back foil, then the structure is simple, but the gap between the top foil and thrust collar becomes large on the outer peripheral side, reducing load capacity
Solution Approach 1:
The support surface is divided into multiple inclined surfaces (first, second, third inclined surfaces) with different inclination angles. Each inclined surface supports a specific radial region of the back foil, allowing precise control of the gap between top foil and thrust collar in different areas. This segmentation resolves the contradiction by maintaining simple individual surface structures while achieving complex overall gap control for improved load capacity.
Solution Approach 2:
Different regions of the support surface are given different inclination angles tailored to local requirements. The first inclined surface (larger angle) addresses the inner radial region, the second inclined surface (intermediate angle) addresses the middle radial region, and the third inclined surface (smaller angle) addresses the outer radial region. This local differentiation ensures optimal gap control in each region, resolving the contradiction between structural simplicity and load capacity.
2Reliability
If the inclination angle is increased to reduce the gap, then the load capacity improves, but the gap on the outer peripheral side becomes excessively large
Solution Approach 1:
The support surface is divided into multiple inclined surfaces (first, second, third inclined surfaces) with different inclination angles. Each inclined surface supports a specific radial region of the back foil, allowing precise control of the gap between top foil and thrust collar in different areas. This segmentation resolves the contradiction by maintaining simple individual surface structures while achieving complex overall gap control for improved load capacity.
Solution Approach 2:
Different regions of the support surface are given different inclination angles tailored to local requirements. The first inclined surface (larger angle) addresses the inner radial region, the second inclined surface (intermediate angle) addresses the middle radial region, and the third inclined surface (smaller angle) addresses the outer radial region. This local differentiation ensures optimal gap control in each region, resolving the contradiction between structural simplicity and load capacity.
3Ease of manufacture
If the back foil is made as one piece, then the manufacturing is simple, but the load distribution becomes uneven due to height differences
Solution Approach 1:
The back foil is divided into multiple sections (first back foil section, second back foil section, third back foil section) that can be independently manufactured and then assembled. Each section corresponds to a specific radial region and can be tailored to the local inclination requirements. This segmentation enables even load distribution across different radial positions while maintaining manufacturing feasibility through modular production and assembly.
Solution Approach 2:
The divided back foil sections are designed to flexibly adapt to the different inclination angles of the support surfaces. Each section can independently deform to match its corresponding inclined surface, ensuring optimal contact and load distribution. This dynamic adaptability resolves the contradiction by allowing simple manufacturing of individual sections while achieving uniform load distribution through their flexible assembly.
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, even on the outer peripheral side, thereby 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 bearing surface is formed of a flexible foil (thin metal plate) to absorb a movement (axial displacement and inclination of the thrust collar) of the rotating shaft generated by vibration or impact
Data Source
AI summary
A thrust foil bearing includes a base plate including an insertion hole through which a rotating shaft is inserted and a support surface disposed around the insertion hole on one side of the insertion hole in an axial direction, and a back foil disposed on the support surface, in which the support surface has a plurality of inclined surfaces of which inclination angles inclined toward the other side of the base plate in the axial direction become shallower in order toward an outside of the insertion hole in a radial direction, and the back foil is divided into a plurality of divided regions in the radial direction by a slit, and the plurality of divided regions are supported by the plurality of inclined surfaces.