Generator Wedge Curved Interface Reduces Stress Lever Arm
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Solution Overview
Problem
High-speed rotation of generators/motors induces centrifugal forces, causing the wedge and coil to shift and resulting in undesired contact with pole tips, leading to increased stress lever arm due to non-linear contact surfaces.
Innovation Solution
A wedge design with a central leg and circumferentially extending arms featuring a curved outer surface and flat inner surface, allowing contact along curved surfaces to maintain a shorter stress lever arm even under deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a straight surface interface is used between the pole tip and the wedge, then the manufacturing is simpler, but under centrifugal forces the contact point shifts to create a long stress lever arm
Solution Approach 1:
The wedge interface surface is designed with a curved surface that conforms to the pole tip geometry, transforming the straight surface interface into a curved one. This curvature ensures that the contact point remains optimally positioned under centrifugal forces, maintaining a short stress lever arm while supporting the wedge and coils during high-speed rotation
2Adaptability or versatility
If the wedge and coil are allowed to move under centrifugal forces, then the operational flexibility is improved, but the contact location becomes undesired and creates increased stress
Solution Approach 1:
The curved interface surface is designed to accommodate the movement of the wedge and coil under centrifugal forces while maintaining proper contact geometry. The curvature allows the components to shift position during operation without creating a long stress lever arm, as the contact point naturally follows the curved surface to remain close to the desired location
3Strength
If a curved surface is used for the wedge interface, then the stress lever arm is reduced under centrifugal forces, but the manufacturing complexity increases
Solution Approach 1:
The curved interface surface is formed as an integral part of the wedge structure, allowing the curvature to be achieved through standard forming or machining operations. The curved surface can be created using conventional manufacturing methods such as CNC machining or molding, balancing the stress reduction benefit with reasonable manufacturing 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
The wedge design ensures a consistent contact point along curved surfaces, reducing the stress lever arm and maintaining stability under centrifugal forces, thereby minimizing mechanical stress on the pole tips.
Implementation Method 1
During operation, the generator/motor rotor may rotate at very high speeds, and thus there are centrifugal forces placed on the pole tips, the coils and the wedges
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A wedge, 32, for use in an electric machine has a central leg, 38, extending in a direction that will be radially inward when the wedge is mounted on a lamination stack. The wedge, 32, has arms, 36, extending in both circumferential directions from the central leg, 38, with a circumferentially outermost part of the arms having a curved surface that will be radially outward, and a flat inner surface, 100, that will be radially inward when the wedge, 32, in mounted in the lamination stack, 28. A generator/motor rotor and a generator/motor are also disclosed.