Spherical Journal Bearing With Hydrodynamic Load Support
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Solution Overview
Problem
Conventional rolling element and cylindrical tilting-pad journal bearings used in wind turbines face high wear and maintenance costs due to concentrated load pressures, making them unsuitable for low-speed/high-load applications in wind turbine main bearings.
Innovation Solution
A hydrodynamic spherical journal bearing with a semispherical convex surface on the shaft and static semispherical concave bearing surfaces in the housing, eliminating the need for separate thrust pads and reducing complexity by using a continuous, press-fitted ring-shaped journal and static bearing pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If rolling element bearings are used to support high loads in wind turbines, then load carrying capacity is improved, but contact pressure concentrates on line contacts causing high wear and surface damage
Solution Approach 1:
The patent applies hydrodynamic lubrication by introducing a fluid film between the bearing surfaces. The bearing housing contains a reservoir for bearing fluid that forms a continuous layer between the shaft and bearing pads, replacing solid-to-solid contact with fluid-mediated contact. This eliminates line contact concentration and distributes load across the entire bearing surface, resolving the wear problem while maintaining high load capacity.
2Ease of operation
If conventional cylindrical tilting-pad journal bearings are used for high-speed/low-load applications, then bearing operation is improved, but the bearing becomes complex and expensive to manufacture and maintain
Solution Approach 1:
The patent merges the journal bearing and thrust bearing functions into a single integrated spherical bearing structure. The semispherical convex surface on the shaft and corresponding concave surface in the housing simultaneously handle radial and axial loads, eliminating the need for separate thrust pads and tilt mechanisms. This consolidation reduces complexity while maintaining operational effectiveness in low-speed/high-load wind turbine applications.
Solution Approach 2:
The patent employs spherical geometry with a semispherical convex surface on the shaft and a matching concave surface in the bearing housing. This spherical configuration naturally accommodates misalignment and deflection without requiring complex tilt mechanisms, simplifying the bearing structure while improving adaptability to operational conditions.
3Force
If separate axial thrust pads are used to compensate for changing axial load, then thrust capability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The spherical bearing structure serves multiple functions simultaneously: the semispherical convex-concave interface provides both radial load support and axial thrust capability. The same bearing surfaces that accommodate radial shaft loads also handle changing axial loads through the spherical geometry, eliminating the need for separate thrust pads and reducing overall system complexity.
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 spherical journal bearing reduces wear and maintenance costs by accommodating misalignment and deflection, providing sufficient thrust capability without separate thrust pads, and simplifying the bearing system, making it commercially feasible for wind turbines.
Implementation Method 1
The bearing conceptually operates by supporting the load essentially entirely on a thin layer of liquid, usually oil, between the shaft and the pads
Data Source
AI summary
A hydrodynamic journal bearing assembly for a drivetrain of a wind turbine includes a shaft and a semispherical convex surface provided on an outer surface of the shaft, the convex surface extending circumferentially around the shaft and having a convex cross-sectional profile oriented along a longitudinal axis of the shaft. A bearing housing is arranged circumferentially around the semispherical convex surface, the bearing housing having s a reservoir in a bottom portion thereof for a bearing fluid. A static semispherical concave bearing surface in the bearing housing defines a bearing interface with the semispherical convex surface on the shaft, wherein a layer of the fluid is provided in the bearing interface as the shaft and rotates through the reservoir.