Compliant Foil Radial Bearing With Segmented Spring Retention
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Solution Overview
Problem
Existing fluid foil bearing designs for micro turbines suffer from excessive manufacturing complexity, poor performance at low revolutions per minute, and limited optimization of friction characteristics, making them impractical for high rotational speeds and temperatures.
Innovation Solution
A compliant foil radial bearing design featuring a spring foil with axially and radially extending retaining portions outside the bushing, which simplifies manufacturing and reduces performance dependence on manufacturing specifics, while providing improved stiffness and friction control through independent tunable strips and a hydrodynamic fluid layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a corrugated spring foil and fastening mechanism are employed between the spring foil and bushing, then the spring foil can be retained in the bushing, but manufacturing complexity increases excessively
Solution Approach 1:
The spring foil is divided into multiple circumferential strips that are independently retained by separate retaining portions in the bushing. This segmentation allows each strip to be retained independently through simple axial insertion, eliminating the need for complex corrugated structures and fastening mechanisms while maintaining reliable retention.
2Ease of operation
If existing spring foil designs are used, then the bearing can operate, but the performance is overly dependent upon manufacturing specifics associated with the spring foil
Solution Approach 1:
The spring foil is designed with inherent flexibility and compliance, allowing it to dynamically adapt to manufacturing tolerances and operating conditions. The multiple independent strips can flex and conform to the bushing geometry, reducing sensitivity to precise manufacturing dimensions while maintaining operational reliability.
3Object-generated harmful factors
If existing fluid foil bearing designs are used, then the bearing can reduce friction, but the scope for optimization of friction characteristics is limited
Solution Approach 1:
The bearing design allows independent optimization of multiple parameters: the spring foil compliance, fluid foil thickness and material properties, number and arrangement of circumferential strips, and retaining portion geometry. These parameter changes enable systematic optimization of friction characteristics across different operating conditions, significantly expanding the design space beyond existing fixed-geometry bearings.
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 bearing performance at low revolutions per minute and high temperatures, reducing friction and heat buildup, and simplifies manufacturing, making it suitable for micro turbines with improved control over stiffness and friction characteristics.
Implementation Method 1
Prior to spin-up, gravitational forces acting on the rotor compress the fluid foil and spring foil between the rotor and inner surface of the bushing
Implementation Method 2
Following spin-up, the creation of a thin layer of fluid between the non-rotating fluid foil and the rotating rotor results in the rotor, as it were, lifting off from the fluid foil, giving rise to a low friction hydrodynamic bearing
Implementation Method 3
additionally, the transfer of fluid facilitates heat transfer
Data Source
AI summary
A compliant foil radial bearing (100) comprising: a bushing (110) comprising a bore defined therethrough; a spring foil (120, 130) arranged to conform to a radially inner surface of the bore; a fluid foil (140, 150) arranged to conform to a radially inner surface of the spring foil for rotatably receiving a rotor, wherein: the spring foil comprises one or more retaining portions (160) arranged to extend axially and radially outside the radially inner surface of the bore.