Axial Air Gap Generator With Rolling Supports
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Solution Overview
Problem
Direct drive generators with radial air gaps face challenges in maintaining a uniform air gap due to their large diameter, which complicates the generation of adequate electricity at slower rotation speeds without the use of a gearbox.
Innovation Solution
The implementation of a rotor ring with a peripheral channel and a stator ring with axial air gaps, maintained by sets of rolling gap supports that can be horizontal or inclined up to 45°, to ensure consistent air gap distances between magnetic elements and stator teeth, facilitating efficient energy generation in wind turbines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a radial air gap is used in a direct drive generator with large diameter, then the generator can operate at slower rotation speeds without a gearbox, but maintaining a uniform air gap becomes difficult
Solution Approach 1:
The patent inverts the traditional radial air gap configuration to an axial air gap configuration. Instead of having the air gap extend radially from the rotor to stator, the air gap now extends axially between the rotor and stator faces. This inversion allows the use of rolling support elements that can maintain the axial gap uniformly across the large diameter of the generator, solving the air gap uniformity problem while preserving the direct drive capability for slower rotation speeds
Solution Approach 2:
The patent introduces rolling support elements as intermediary components between the rotor and stator. These rolling supports act as mediators that maintain the prescribed axial air gap distance while allowing for thermal expansion, manufacturing tolerances, and operational variations. The rolling elements provide a mechanism to preserve air gap uniformity across the large generator diameter without requiring extremely precise manufacturing
2Power
If the diameter of the rotor is increased to generate adequate electricity at slower speeds, then power generation capability is improved, but maintaining a uniform air gap becomes more difficult
Solution Approach 1:
The patent inverts the traditional radial air gap configuration to an axial air gap configuration. Instead of having the air gap extend radially from the rotor to stator, the air gap now extends axially between the rotor and stator faces. This inversion allows the use of rolling support elements that can maintain the axial gap uniformly across the large diameter of the generator, solving the air gap uniformity problem while preserving the direct drive capability for slower rotation speeds
Solution Approach 2:
The patent changes the dimensionality of the air gap from radial (extending outward from the center) to axial (extending along the axis of rotation). This dimensional change allows the air gap to be maintained by rolling supports that operate in the axial direction, enabling uniform gap maintenance across large rotor diameters while maintaining the direct drive configuration for adequate power generation at slower speeds
3Speed
If a gearbox is used to increase angular velocity, then rotation speed is improved, but mechanical complexity and stress are increased
Solution Approach 1:
The patent extracts and removes the gearbox from the wind turbine drivetrain by implementing a direct drive generator configuration. The generator is directly coupled to the rotor without any intermediate gear transmission mechanisms. This elimination of the gearbox reduces mechanical complexity, removes a source of mechanical stress and failure, while the axial air gap design with rolling supports enables the generator to operate efficiently at the slower rotation speeds produced by the wind turbine
Solution Approach 2:
The axial air gap configuration with rolling support elements serves multiple functions simultaneously: it maintains the air gap uniformity across large diameters, accommodates thermal expansion and manufacturing tolerances, and enables direct drive operation at slower speeds. This multi-functional design eliminates the need for separate speed-increasing mechanisms like gearboxes, 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
This configuration allows for effective maintenance of axial air gaps, enhancing the robustness and efficiency of direct drive generators, particularly in wind turbine applications by reducing mechanical stresses and improving power generation at slower rotation speeds without the need for a gearbox.
Implementation Method 1
One or more sets of rolling gap supports bears between the stator ring and the rotor ring so as to maintain the first and second axial air gaps
Implementation Method 2
a rotor ring has a peripheral channel with left and right sidewall portions and a central web portion. Opposite faces of the central web portion carry first and second sets of magnetic elements. A stator ring has a peripheral portion that is sized and adapted to be at least partially received in the peripheral channel of the rotor ring between the left and right sidewalls
Data Source
AI summary
Direct drive rotating electrical machines with axial air gaps are disclosed. In these machines, a rotor ring and stator ring define an axial air gap between them. Sets of gap-maintaining rolling supports bear between the rotor ring and the stator ring at their peripheries to maintain the axial air gap. Also disclosed are wind turbines using these generators, and structures and methods for mounting direct drive rotating electrical generators to the hubs of wind turbines. In particular, the rotor ring of the generator may be carried directly by the hub of a wind turbine to rotate relative to a shaft without being mounted directly to the shaft.