Thrust Foil Bearing Stepped Support for Stable Load Capacity
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Solution Overview
Problem
The load capacity of thrust foil bearings is compromised due to processing errors in the inclined surface of the base plate, leading to an unintended configuration of the wedge-shaped gap, which affects the morphology of the fluid lubrication film and subsequently the bearing's performance.
Innovation Solution
The thrust foil bearing incorporates a stepped member as a separate body from the base plate, with stepped support portions and shims to reduce deviations in step dimensions, forming a virtual incline that supports the bump foil pieces and maintains a desired load capacity, even with variations in step dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the inclined surface is formed by cutting on the base plate, then the wedge-shaped gap can be formed, but processing errors cause deviations in step dimensions leading to unintended configuration
Solution Approach 1:
The base plate is divided into two separate components: the base plate itself and a stepped member. The stepped member is a separate component that can be precisely manufactured with the required step dimensions and then assembled to the base plate. This segmentation allows each component to be manufactured independently with high precision, avoiding the cumulative errors that occur when forming inclined surfaces directly on the base plate through cutting operations.
Solution Approach 2:
The stepped member acts as an intermediary component between the base plate and the bump foil pieces. Instead of forming the wedge-shaped gap directly on the base plate through cutting (which causes processing errors), the stepped member is introduced as a separate precision component that defines the gap geometry. This intermediary element transfers the load while maintaining precise dimensional control, resolving the contradiction between ease of manufacture and manufacturing precision.
2Reliability
If the inclined surface configuration deviates from intended design, then the wedge-shaped gap morphology is affected, but the load capacity decreases
Solution Approach 1:
By segmenting the base plate and stepped member into separate components, the gap configuration precision is ensured through precise manufacturing of the stepped member. This segmentation allows the stepped member to be manufactured with tight tolerances to ensure the wedge-shaped gap maintains the intended morphology, thereby ensuring reliable load capacity through consistent fluid lubrication film formation.
3Manufacturing precision
If a separate stepped member is introduced, then deviations in step dimensions are reduced, but the device complexity increases
Solution Approach 1:
The base plate is divided into two separate components: the base plate itself and a stepped member. The stepped member is a separate component that can be precisely manufactured with the required step dimensions and then assembled to the base plate. This segmentation allows each component to be manufactured independently with high precision, avoiding the cumulative errors that occur when forming inclined surfaces directly on the base plate through cutting operations.
Solution Approach 2:
The stepped member serves multiple functions: it defines the wedge-shaped gap geometry, supports the bump foil pieces, and transfers the axial load from the thrust collar to the base plate. By consolidating these functions into a single component, the overall device complexity is minimized while achieving the desired manufacturing precision.
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 ensures a consistent and desired load capacity by reducing deviations in step dimensions and maintaining the intended shape of the fluid lubrication film, enhancing the thrust foil bearing's performance.
Implementation Method 1
As the thrust collar rotates, a lubricating fluid is introduced between the top foil piece and the thrust collar. The lubricating fluid forms a wedge-shaped fluid lubrication film between the top foil piece and the thrust collar. As a result of the formation of the fluid lubrication film, a load capacity of the thrust foil bearing is exhibited.
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; a plurality of top foil pieces supported by the support surface; a stepped member that is placed on the support surface, is formed as a separate body from the base plate, and includes a plurality of stepped support portions including a plurality of stepped surfaces; and a plurality of bump foil pieces that are disposed between the top foil pieces and the base plate, are respectively disposed on the plurality of stepped support portions, and include valley portions in contact with the stepped surfaces.