Wind Turbine Pitch Bearing Drive for Constant Adjustment Torque
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Solution Overview
Problem
Existing actuating drives for wind turbine rotor blade pitch angle adjustments face issues with lubrication problems in electrical systems and non-constant adjustment torques in hydraulic systems, requiring complex and expensive pressure control to compensate for varying forces.
Innovation Solution
An actuating drive is integrated into the large roller bearing with a piston relocated inside one bearing ring, forming an annular groove cylinder, allowing the piston to travel along an arcuate trajectory and maintain constant torque without changing the lever arm, and featuring pistons with equal-sized surfaces for consistent actuating force in all directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a hydraulic cylinder is used for pitch angle adjustment, then the actuating drive can generate adjustment torque, but the lever arm varies with pivot angle causing non-constant adjustment torque
Solution Approach 1:
The patent applies curvature by forming the cylinder as an annular groove in the bearing ring rather than a straight cylindrical bore. This curved geometry allows the piston to move along an arcuate trajectory, maintaining a constant perpendicular distance (lever arm) between the piston rod force vector and the rotation axis, thereby generating constant adjustment torque regardless of the pivot angle.
2Force
If hydraulic pressure is controlled to compensate for varying piston forces in different directions, then constant adjustment torque can be achieved, but the control system becomes complex and expensive
Solution Approach 1:
The patent employs asymmetry in the piston design by providing different surface areas on the two sides of the piston. The first piston surface area is designed to be larger than the second piston surface area, creating an inherent mechanical compensation effect. This asymmetric geometry automatically balances the varying forces in different directions without requiring complex electronic pressure control systems.
3Ease of operation
If an electric motor with pinion and ring gear is used for pitch adjustment, then electrical control is achieved, but lubrication problems occur when the pinion remains stationary for long periods
Solution Approach 1:
The patent replaces the electric motor-driven pinion and ring gear mechanism with a direct hydraulic actuation system. The piston rod is directly connected to the second bearing ring, eliminating the intermediate pinion-rack transmission. This substitution removes the lubrication-dependent gear interface while maintaining precise electrical control capability through the hydraulic control system.
4Device complexity
If the piston surface areas are made equal to simplify the design, then the structure becomes simpler, but the actuating force varies with direction due to different piston rod surfaces
Solution Approach 1:
The patent deliberately introduces asymmetry in the piston design by providing different surface areas on the two sides of the piston. The first piston surface area is designed to be larger than the second piston surface area, creating an inherent mechanical compensation effect. This asymmetric geometry automatically balances the varying forces in different directions without requiring complex electronic pressure control systems.
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 achieves constant adjustment torques independently of direction without complex pressure control, enabling a low-maintenance, compact actuating drive with high actuating forces and reduced maintenance needs.
Implementation Method 1
the piston can be adjusted on an arcuate trajectory... If the piston in the annular groove cylinder is pressurized by pressure medium, the piston travels in the annular groove cylinder of the one bearing ring and in so doing takes along the other bearing ring via said drive-wise connection so that a rotation of the two bearing rings and thus an adjustment of the pitch angle occurs
Implementation Method 2
If the piston in the annular groove cylinder is pressurized by pressure medium, the piston travels in the annular groove cylinder... the same actuating force and thus the same adjustment torque is generated independently of the direction
Data Source
AI summary
In general, the invention relates to wind turbines, the rotor blades of which can be adjusted in terms of their pitch angle. The invention relates in particular to an actuating drive for adjusting the pitch angle of a rotor blade of a wind turbine, comprising a large rolling bearing which comprises two bearing rings that can be rotated relative to each other, and an actuator for rotating the two bearing rings relative to each other. According to the invention, the actuating drive comprises a ring channel cylinder, which is formed in one of the bearing rings, and at least one piston, which is received in the ring channel cylinder in a movable manner and is drivingly connected to the other bearing ring of the two bearing rings.