Double Stator Machine Asymmetric Gap Radial Force Compensation
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Solution Overview
Problem
Asymmetries in the gap distances between the rotor and stators in rotating electrical machines lead to amplified radial forces, causing damage and increased component dimensions and costs due to manufacturing inaccuracies or wear.
Innovation Solution
A multi-stator rotating electrical machine design with an inner gap distance averaging between 75 and 80 percent of the outer gap distance, which compensates for asymmetries by opposing forces from both gaps, reducing detrimental radial forces and dimensioning requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the gap distances between rotor and stators are made equal, then the machine structure is simplified and easier to manufacture, but radial forces are greatly amplified due to asymmetries from manufacturing inaccuracies or wear
Solution Approach 1:
The patent applies asymmetry by deliberately setting different average gap distances between the rotor and inner stator versus outer stator. Specifically, the inner gap distance is set to 0.75-0.85 times the outer gap distance. This asymmetric configuration creates opposing radial forces that cancel each other out, compensating for asymmetries caused by manufacturing inaccuracies or bearing wear, thereby reducing net radial forces on the rotor.
2Object-affected harmful factors
If the inner gap distance is reduced to 75-80 percent of outer gap distance, then radial forces are compensated and reduced, but the machine requires more precise gap control and complex design
Solution Approach 1:
The patent applies parameter changes by optimizing the inner gap distance to be 0.75-0.85 times the outer gap distance. This specific parameter range was determined to provide optimal compensation for radial forces while maintaining practical manufacturability. By carefully selecting this parameter range, the patent achieves force compensation without requiring excessively complex design or control mechanisms.
3Shape
If equal gap distances are used, then the design is simpler and more symmetric, but manufacturing inaccuracies and bearing wear cause force amplification that requires over-dimensioning of components
Solution Approach 1:
The patent deliberately breaks the symmetry of equal gap distances by setting the inner gap to 0.75-0.85 times the outer gap. This asymmetric design creates opposing radial forces that compensate for each other, reducing the net forces that would otherwise require over-dimensioning of components. The asymmetric configuration thus allows for more efficient component sizing while accounting for manufacturing tolerances and wear.
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 reduces radial forces on the rotor, minimizing mechanical stress and component costs while maintaining output power and efficiency, with reduced magnet weight and potential for redundant operation.
Implementation Method 1
In rotating electrical machines, when there is any asymmetry in the gap (such as air gap) between rotor and stator, forces are greatly amplified along a radial direction of the machine
Data Source
AI summary
It is provided a multi-stator rotating electrical machine including: an inner stator; an outer stator; a rotor provided radially between inner stator and the outer stator; an inner gap distance between the rotor and the inner stator; and an outer gap distance between the rotor and the outer stator. An average of the inner gap distance is between 75 and 80 percent of an average of the outer gap distance.