Electric Machine J-strap Insulation for Stress Relief
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Solution Overview
Problem
The J-strap in electric generators experiences differential forces during operation, leading to potential failure, arcing, and damage due to uneven stress distribution, which existing solutions have not adequately addressed.
Innovation Solution
A robust electrically conductive member with a loop-shaped first end section, a solid intermediate section, and a second end section, coupled with an insulation assembly featuring gaps to accommodate radial and circumferential movement, reducing stress and preventing contact with other components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the J-strap is made rigid to maintain structural stability, then structural stability is improved, but the J-strap experiences higher stress from differential forces during rotor acceleration and deceleration
Solution Approach 1:
The J-strap is divided into multiple segments or sections with different structural characteristics. The first end section has a loop shape for flexibility, the intermediate section is solid for strength, and the second end section connects to rotor windings. This segmentation allows each portion to optimize for its specific functional requirements while reducing overall stress concentration.
Solution Approach 2:
The J-strap design incorporates dynamic characteristics by making the first end section flexible with a loop configuration, allowing it to accommodate radial and circumferential movement during rotor acceleration and deceleration. This dynamic flexibility reduces stress from differential forces while maintaining electrical conductivity.
2Stress or pressure
If the J-strap is made flexible to reduce stress from differential forces, then stress relief is improved, but structural stability and current carrying capability deteriorate
Solution Approach 1:
Different sections of the J-strap have different structural qualities optimized for their specific functions. The first end section has a loop shape providing flexibility for stress relief, while the intermediate section is solid providing structural strength and current carrying capability. This local differentiation resolves the contradiction between flexibility and strength.
Solution Approach 2:
The J-strap employs a composite structure combining different configurations (loop-shaped flexible portion and solid intermediate portion) within a single component. This composite approach allows the structure to simultaneously exhibit flexible stress-relief characteristics and rigid current-carrying capabilities.
3Stability of the object's composition
If the J-strap is constrained to prevent movement, then positional stability is improved, but the J-strap cannot accommodate radial and circumferential movement during operation
Solution Approach 1:
The J-strap design incorporates dynamic characteristics by making the first end section flexible with a loop configuration, allowing it to accommodate radial and circumferential movement during rotor acceleration and deceleration. This dynamic flexibility reduces stress from differential forces while maintaining electrical conductivity.
Solution Approach 2:
The loop-shaped first end section changes its geometric parameters (area, shape) in response to radial and circumferential movement during rotor operation. This parameter change allows the J-strap to adapt to varying operational conditions while maintaining electrical connectivity and reducing stress concentration.
Data Source
Figure 1
Figure 2~3
AI summary
An electric machine includes a shaft and a rotor carried by the shaft and having a rotor body, a plurality of rotor windings carried by the rotor body, and a retaining ring surrounding the rotor windings adjacent an end of the rotor body. An electrically conductive stud extends radially outwardly from the shaft adjacent the end of the rotor body. An electrically conductive member includes a first end section coupled to the electrically conductive stud and having a loop shape, a second end section coupled to a corresponding one of the rotor windings, and an intermediate section between the first and second end sections. An insulation assembly is between the shaft and the retaining ring and surrounding the intermediate section to define at least one gap with adjacent portions thereof