Wind Turbine Pitch Bearing Friction Interface Against Slippage
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Solution Overview
Problem
Conventional pitch bearings in wind turbines face issues with insufficient friction between annular parts, leading to slippage and fretting corrosion, which can result in bearing failure under high wind loading or relaxation of bolting forces.
Innovation Solution
A pitch bearing design featuring a split race configuration with a friction enhancing interface between the annular faces, utilizing a layer of friction enhancing material or a roughened surface to increase the coefficient of friction, such as a substrate with abrasive particles or a sprayed/coated layer, to minimize slippage between the ring components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional steel annular parts are used in pitch bearing, then the bearing structure is simple and easy to manufacture, but friction between parts is insufficient leading to slippage and fretting corrosion
Solution Approach 1:
The patent applies composite materials by combining steel annular parts with a friction enhancing layer made of particulate material (such as sintered metal or ceramic particles). This composite structure increases the coefficient of friction at the interface between annular parts, preventing slippage and fretting corrosion while maintaining the overall bearing structure.
Solution Approach 2:
The patent changes the physical parameters of the bearing interface by introducing a friction enhancing layer that modifies the coefficient of friction. This parameter change transforms the sliding interface into a high-friction interface, preventing relative motion between annular parts under high wind loading conditions.
2Reliability
If friction enhancing material is added to the pitch bearing, then slippage between annular parts is reduced, but the manufacturing complexity increases
Solution Approach 1:
The friction enhancing layer is applied in advance to the annular parts before final assembly. The particulate material is sintered or bonded to create a permanent friction-enhancing surface, so that when the bearing is assembled and subjected to load, the high-friction interface is already in place to prevent slippage.
Solution Approach 2:
The friction enhancing layer can be designed as a consumable or replaceable component. If the particulate material wears down over time, it can be replenished or the layer can be reapplied, extending the service life of the bearing without replacing the entire assembly.
3Reliability
If bolting forces are increased to prevent slippage, then friction at the interface is improved, but the risk of bearing failure under high wind loading increases
Solution Approach 1:
The patent changes the friction coefficient parameter by introducing the particulate friction enhancing layer. This allows the bearing to achieve sufficient frictional force at lower bolting forces, reducing the mechanical stress on the bearing components while maintaining interface stability.
Solution Approach 2:
The friction enhancing layer acts as an intermediary substance between the steel annular parts. This intermediate layer increases the effective friction coefficient, allowing the interface to transmit higher forces without requiring increased clamping pressure from the bolting system.
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 enhanced friction interface effectively reduces slippage and fretting corrosion, ensuring the integrity and longevity of the pitch bearing by maintaining proper alignment and reducing microscopic movements between the annular parts.
Implementation Method 1
a friction enhancing interface between the opposed annular faces that increases a coefficient of friction to minimize slippage between the first and second ring components
Implementation Method 2
a roughened surface defined into one or both of the opposed annular faces, the roughened surface comprising peaks and valleys (regular or irregular pattern) that provide the desired degree of increased coefficient of friction
Data Source
AI summary
A pitch bearing for coupling a rotor blade to a hub of a wind turbine includes an outer race mountable to the hub and an inner race rotatable relative to the outer race and mountable to the rotor blade. The inner race is formed by first and second ring components, each of the first and second ring components having an outer annular face and an inner annular face. The first and second ring components are joined together at the inner annular faces such that the inner annular faces are opposed and opposite each other. A layer of friction enhancing material is inserted/disposed between the opposed inner annular faces, the friction enhancing material including an abrasive particulate component that increases a coefficient of friction to minimize slippage between the first and second ring components.