Double Box Stiffness Normalization for Vertical Electric Machines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vertical electric machines experience excessive vibration due to differing reed critical frequencies in lateral 'X' and 'Y' directions, requiring larger operational blockout ranges to avoid resonant conditions, limiting the ability to vary speed over large ranges.
Innovation Solution
A double box construction with rotated stiffness member side walls is used to create equal stiffness in both lateral directions, normalizing the reed critical frequencies to occur at the same frequency, reducing the blockout range by eliminating non-symmetry between 'X' and 'Y' directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a traditional single box structure is used, then the structure is simple and easy to manufacture, but the reed critical frequencies in lateral X and Y directions differ, requiring larger blockout ranges to avoid resonant conditions
Solution Approach 1:
The single box structure is divided into two separate box structures (first box structure and second box structure) with different orientations. The first box structure provides stiffness in one lateral direction while the second box structure provides stiffness in the perpendicular lateral direction. This segmentation allows each box to be optimized for its specific direction, achieving equal stiffness in both lateral directions and normalizing the reed critical frequencies.
Solution Approach 2:
The two box structures are designed with asymmetric orientations relative to each other (typically at 45 degrees or perpendicular to each other). This asymmetric arrangement ensures that the combined stiffness properties in the X and Y lateral directions are equalized, thereby normalizing the reed critical frequencies and reducing the required blockout ranges.
2Strength
If different stiffness members are used in lateral X and Y directions, then the structural strength is optimized for each direction, but the reed critical frequencies occur at different frequencies, causing excessive vibration
Solution Approach 1:
Different box structures are positioned to provide localized stiffness in specific directions. The first box structure is oriented to maximize stiffness in one lateral direction, while the second box structure is oriented to maximize stiffness in the perpendicular lateral direction. This local optimization of stiffness distribution ensures that both lateral directions achieve equal and adequate stiffness, normalizing the reed critical frequencies and preventing excessive vibration.
3Adaptability or versatility
If the machine structure is normalized to achieve equal reed critical frequencies, then the blockout range is reduced and speed variation is improved, but the structure becomes more complex with double box construction
Solution Approach 1:
Each box structure serves multiple functions: it provides structural support, contributes to the overall stiffness in a specific direction, and helps normalize the reed critical frequencies. The dual-box construction achieves the multi-function of providing equal stiffness in both lateral directions while maintaining a relatively compact and integrated structure, reducing blockout ranges and enabling broader speed variation.
Data Source
AI summary
A vertical electric machine comprises a specific structure that defines a double box construction for normalizing the vertical electric machine structure such that its two reed critical frequencies occur at a same frequency. The double box construction includes a first stiffness member having a first side wall in a lateral “X” direction and a second stiffness member having a second side wall in a lateral “Y” direction such that the second side wall is rotated 90 degrees relative to the first side wall. The first stiffness member and the second stiffness member are configured to produce equal stiffness in both lateral directions “X” and “Y”.