Compound Main Bearing Assembly for Wind Turbine Bending Loads
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Solution Overview
Problem
Conventional roller element bearings in wind turbines have limited operating life due to surface fatigue and wear, leading to high maintenance and replacement costs, and are insufficient to handle large bending loads from varying wind conditions.
Innovation Solution
A compound main bearing arrangement featuring a main bearing housing with at least two axial thrust bearings and a radial bearing, which can include journal and rolling element bearings, designed to support both radial and axial loads, and optionally uses tilting pad journal bearings with low-friction coatings and elastic support to manage load distribution and reduce friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If roller element bearings are used in wind turbines, then they can support radial and axial loads, but their operating life is limited due to surface fatigue and wear
Solution Approach 1:
The patent replaces roller element bearings with a journal bearing system that uses a fluid film (oil) to separate bearing surfaces, eliminating direct metal-to-metal contact and the associated surface fatigue and wear mechanisms that limit roller bearing life
Solution Approach 2:
The patent employs hydrodynamic lubrication using oil to create a fluid film between the journal bearing surfaces, which supports the wind turbine rotor shaft loads while preventing surface fatigue and wear, thereby extending bearing operating life
2Duration of action of moving object
If journal bearings are used to extend operating life, then surface fatigue and wear are eliminated, but they may be insufficient for large bending loads from varying wind conditions
Solution Approach 1:
The patent combines journal bearing and roller bearing technologies into a hybrid system where the journal bearing handles radial loads through fluid film lubrication while roller elements provide additional support for axial and bending loads, achieving both extended life and high load capacity
3Ease of manufacture
If axial spacing between bearings is increased to reduce loading, then bearing costs decrease, but a longer and more expensive main shaft is required
Solution Approach 1:
The patent changes the bearing type from roller to journal, which alters the load distribution characteristics and allows for reduced axial spacing between bearings while maintaining adequate load capacity, thereby shortening the main shaft length
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 compound bearing design extends the operating life of wind turbine bearings, reduces maintenance and replacement costs, and effectively handles varying loads, improving the efficiency and reliability of wind turbine operations.
Implementation Method 1
journal bearings do not have any structural element disposed between the two relative moving components, but instead have only a fluid film disposed therebetween
Implementation Method 2
low-friction coatings and elastic support to manage load distribution and reduce friction
Data Source
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AI summary
A drive train of a wind turbine 10 is disclosed as having a rotatable hub 20, a gearbox 36, a rotatable rotor shaft 32 extending between the rotatable hub 20 and the gearbox 36, and a main bearing assembly 48 supporting the rotatable rotor shaft 32, the main bearing assembly 48 having a main bearing housing 46 enclosing one or more compound bearings 60, each of the one or more compound bearings 60 having at least two axial thrust bearings 52, 54 and a radial bearing 58.