Wind Turbine Main Bearing Preload Ring for In-Service Adjustment
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Solution Overview
Problem
The extended service life of modern wind turbines poses challenges for the main bearing unit, as the initial bearing preload levels, suitable for shorter service lives, cannot be decreased without leading to premature fatigue damage, and increasing the bearing size is costly.
Innovation Solution
The main bearing unit incorporates a preload ring that can be displaced axially during a bearing preload reinstatement procedure, allowing for the reinstatement of preload force in an operational drivetrain, thereby extending the service life without excessive initial preload or increased bearing size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the initial bearing preload level is decreased to reduce fatigue damage, then the service life of the bearing is extended, but insufficient preload leads to other types of wear that result in premature fatigue damage
Solution Approach 1:
The bearing preload is made dynamically adjustable through a preload ring that can be repositioned axially during operation. The preload force can be modified by changing the position of the preload ring along the bearing axis, allowing optimization of preload levels at different service stages to balance fatigue reduction and wear prevention
Solution Approach 2:
The preload force parameter is made variable through the preload ring mechanism. By changing the axial position of the preload ring, the preload force applied to the bearing can be adjusted, enabling optimization of the bearing operating conditions throughout its service life to extend fatigue life while maintaining sufficient preload
2Duration of action of stationary object
If the bearing size is increased to extend service life, then the fatigue resistance is improved, but the cost of the wind turbine increases significantly
Solution Approach 1:
Instead of increasing bearing dimensions, the invention changes the operational parameters of the existing bearing by implementing an adjustable preload mechanism. The preload ring allows modification of the preload force to optimize fatigue life, achieving extended service life through parameter optimization rather than scaling up component size
Solution Approach 2:
The bearing system is made dynamically adjustable with the preload ring that can be repositioned during operation. This dynamic adjustment capability allows optimization of bearing performance and fatigue life without requiring larger bearing dimensions, thereby avoiding increased manufacturing costs
3Reliability
If the bearing preload is set to high levels during assembly to cover margins for tolerance and wear, then the bearing reliability is improved, but the fatigue damage from preload increases significantly
Solution Approach 1:
The static preload configuration is transformed into a dynamic system where the preload ring can be repositioned axially during service. This allows the preload force to be adjusted from high initial levels to optimized lower levels, maintaining bearing reliability while reducing fatigue damage accumulation over time
Solution Approach 2:
The preload ring is pre-configured with adjustment capability during assembly, allowing for preliminary high preload to ensure reliability, with the option to later adjust the preload level as the bearing settles and wears, optimizing the balance between reliability and fatigue life
Data Source
Figure 1
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AI summary
The invention describes a main bearing unit (1) of a wind turbine drivetrain (2), comprising a number of bearings (12) arranged about a low-speed shaft (10) of the drivetrain (2); a housing (18) arranged to enclose the bearings (12); a preload ring (14) arranged between an inner surface of the housing (18) and the outer race (121) of a bearing (12), which preload ring (14) is adapted to facilitate its axial displacement during a bearing preload reinstatement procedure; and a means (14F, 14N) of fixing the position of the preload ring (14) to the housing (18) following a bearing preload reinstatement procedure. The invention further describes a bearing preloading arrangement (3) for use in reinstating preload in a bearing of such a main bearing unit; and a method of reinstating a preload force (Fpreload) in a bearing of such a main bearing unit (1).