Stepped Top Foil Air Journal Bearing for High-Speed Vibration Stability
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Solution Overview
Problem
Existing air foil journal bearings face challenges in durability against vibration and dynamic performance during high-speed operations, as they are prone to damage from external vibrations and require secure fixation to improve durability.
Innovation Solution
The air foil journal bearing design includes a top foil with opposite ends disposed adjacent to each other, featuring top foil keys with a step difference in the radial direction, and additional fluid dynamic pressure is generated to enhance dynamic performance and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the top foil ends are securely fixed to the bearing housing using keys, then durability against vibration is improved, but dynamic performance and driving stability during high-speed operation deteriorate
Solution Approach 1:
The top foil is designed with a stepped configuration where one end is fixed to the bearing housing while the other end remains free to move axially. This dynamic design allows the fixed end to provide vibration resistance while the free end accommodates axial displacement during high-speed operation, preventing contact damage and maintaining dynamic performance
Solution Approach 2:
The top foil is divided into two distinct regions: a fixed end portion that is secured to the bearing housing for vibration resistance, and a free end portion that can move axially to maintain dynamic performance. This segmentation allows each portion to fulfill its specific function without compromising the other
2Ease of operation
If the top foil has a free end that is spaced apart from the bearing housing, then dynamic performance is maintained, but the bearing becomes vulnerable to damage from external vibration and impact
Solution Approach 1:
The top foil employs a dynamic configuration where one end is fixed and the other end is free to move axially. This allows the bearing to maintain good dynamic performance during high-speed operation while the fixed end provides anchorage against external vibrations and impacts
3Reliability
If two opposite ends of the top foil are fixed using keys, then durability against vibration is improved, but additional fluid dynamic pressure cannot be generated
Solution Approach 1:
By fixing only one end of the top foil and leaving the other end free, the design enables axial movement that generates additional fluid dynamic pressure during high-speed operation, while the fixed end maintains vibration resistance
Solution Approach 2:
The free movement of the top foil's unrestrained end creates pressure changes in the air film, generating additional fluid dynamic pressure that enhances bearing performance during high-speed rotation
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 design improves durability against vibration and enhances dynamic performance and driving stability during high-speed operations by securely fixing the top foil ends and generating additional fluid dynamic pressure.
Implementation Method 1
an air foil bearing refers to a bearing that supports a load by means of pressure generated as air, which is a fluid having a viscosity, is introduced between foils that adjoin a rotor
Implementation Method 2
the rotor floats from the lower side of the inner circumferential surface of the top foil and rotates
Implementation Method 3
one end and the other end of the top foil based on the circumferential direction are disposed with a step difference in the radial direction, in which additional fluid dynamic pressure is generated in the bearing
Data Source
AI summary
The present invention relates to an air foil journal bearing including a bump foil and a top foil, in which one end and the other end of the top foil based on a circumferential direction are disposed with a step difference in a radial direction, and one end of the top foil is disposed radially inward of the other end of the top foil on the assumption that a direction in which the top foil extends from one end to the other end is identical to a rotation direction of a rotor disposed inside the top foil and configured to rotate, such that an additional fluid dynamic pressure is generated in the bearing, and asynchronous vibration components, which affect noise, are suppressed during a high-speed operation, which may improve driving stability.