Disc Rotor Generator with Spacers for Airgap Stability
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Solution Overview
Problem
Larger axial permanent magnet rotary generators face challenges in maintaining a stable airgap due to mechanical forces, leading to potential catastrophic failure, and require efficient use of materials while minimizing weight and cost, especially in applications like wind turbines.
Innovation Solution
The generator design incorporates a stack of disc-like annular rotors with spacers to maintain orthogonality and stability, using tubular members to brace the rotors and reduce the radial width, allowing for a reduced stator diameter and enhanced rigidity, while mounting the rotors on a cylindrical central member to decrease overall weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If rotors are mounted on a single central axle, then the generator structure is simple, but the rotors cannot maintain adequate stiffness and the airgap becomes unstable
Solution Approach 1:
The generator is divided into multiple independent rotor assemblies, each mounted on its own bearing support. This segmentation allows each rotor to be independently braced and positioned, maintaining stable airgap clearance without requiring a single complex central axle structure.
Solution Approach 2:
Bearing supports act as intermediary elements between the rotors and the frame. These intermediaries provide the necessary mechanical support and positioning to maintain airgap stability, eliminating the need for a single central axle while ensuring reliable rotor positioning.
2Reliability
If rotor axial width is increased to improve rigidity, then airgap stability improves, but the use of magnetic and copper materials becomes less efficient
Solution Approach 1:
Rigidity is provided locally at critical positions where rotors interface with bearing supports, rather than increasing the axial width of the entire rotor. This localized bracing approach maintains airgap stability without unnecessarily increasing the volume of magnetic and copper materials in the rotor structure.
Solution Approach 2:
Instead of increasing rigidity in the axial dimension by widening rotors, the solution provides structural support in the radial dimension through bearing supports. This dimensional shift allows thin rotors to maintain stability without excessive material usage.
3Quantity of substance
If rotor axial width is decreased to improve material efficiency, then material usage improves, but rotor stiffness becomes insufficient and airgap stability deteriorates
Solution Approach 1:
Bearing supports serve as intermediary structural elements that compensate for the reduced stiffness of thin rotors. These intermediaries provide the necessary mechanical strength and positioning stability that would otherwise require increased rotor axial width, enabling material-efficient design without sacrificing structural integrity.
4Strength
If stator inner diameter is reduced to enhance rigidity, then stator strength improves, but the spacer design becomes more constrained
Solution Approach 1:
The spacer features a stepped cross-section with different diameters at different longitudinal positions. The larger diameter portion provides the necessary clearance for the rigid stator, while the reduced diameter portion allows the spacer to fit within the stator's inner diameter, resolving the conflict between stator rigidity and spacer accommodation.
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 effectively maintains a stable airgap, enhances the rigidity and strength of the stator, and significantly reduces the weight of the generator, making it more cost-efficient and suitable for large-scale applications like wind turbines by optimizing the distribution of magnetic and copper materials.
Implementation Method 1
one or more spacers being coaxially mounted around the central member in between the inner annular portions of each rotor and abutting against them in such manner such as to brace them to remain orthogonal to the longitudinal axis of the assembly as well as providing the required spacing therebetween
Implementation Method 2
The rotors bear permanent magnets and electricity is generated as the magnetic fields provided by the turning rotors cut the turns of the coils embedded within the stators
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A generator comprises as a first part a stack of disc-like annular rotors spaced one from the other and coaxially located upon and rotating with an elongate central member each rotor having an inner annular portion and an outer annular portion, the outer annular portion bearing and/or comprising a magnetic annul us, one or more spacers being coaxially mounted around the central member in between the inner annular portions of each rotor and abutting against them in such manner such as to brace them to remain orthogonal to the longitudinal axis of the assembly as well as providing the required spacing therebetween, and as a second part, a stack of annular stators interposed between the rotors and mounted over the spacers but having an inner clearance diameter greater than that of the outer diameter of the portion of spacer over which they are located.