Rotor Winding Head Retention to Prevent Bolt Loosening
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing rotor designs for variable-speed hydroelectric power motor-generators face issues where winding elements are bent inward due to tightening forces, leading to potential loosening of tension bolts under operational vibrations.
Innovation Solution
The rotor design incorporates retaining elements with a stop surface that adjusts the radial length of tension bolts to prevent deformation of winding elements and ensures the screw connection remains tensioned, using a combination of tension bolts, support bodies, and optional elastic elements to maintain the position of winding elements without significant compressive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tension bolts are tightened to secure winding elements, then the winding elements are held firmly in position, but the winding elements are bent inward due to the tightening force
Solution Approach 1:
A support body is introduced as an intermediary component between the tension bolt and the winding element. The tension bolt acts on the support body, which in turn contacts the winding element, distributing the clamping force and preventing direct point-loading that causes bending. This mediator structure secures the winding element while avoiding deformation.
Solution Approach 2:
The support body is pre-positioned against the winding element before the tension bolt is fully tightened. This preliminary positioning ensures that the winding element is already supported at the correct location, preventing inward bending during the tightening process and eliminating the need for subsequent adjustments.
2Reliability
If tension bolts are tightened to hold winding elements, then the winding elements are secured, but the previously tightened tension bolts may loosen over time due to vibrations
Solution Approach 1:
The support body serves as a stable intermediary that distributes and stabilizes the tension force from multiple bolts. By acting on the support body rather than directly on the winding element, the system reduces stress concentration and vibration-induced loosening, maintaining stable tension over time.
Solution Approach 2:
The support body provides a cushioning effect by distributing the mechanical stresses and vibrations across a larger area. This beforehand cushioning protects the tension bolt connections from vibration-induced loosening, ensuring long-term stability during operation.
3Reliability
If support bodies are pressed against winding elements with significant force, then the winding elements are securely retained, but the winding elements are deformed
Solution Approach 1:
The support body is designed with a segmented or distributed contact structure that spreads the retention force across multiple contact points along the winding element. This segmentation reduces the pressure at any single point, preventing deformation while maintaining secure retention through cumulative distributed force.
Solution Approach 2:
The contact parameters between the support body and winding element are optimized to achieve retention without excessive force. By adjusting parameters such as contact area, pressure distribution, and material properties, the system secures the winding element while preserving its structural integrity and avoiding deformation.
Data Source
AI summary
A rotor for an electric machine includes: a rotor body; winding elements; and a winding head, which includes a winding head support and retaining elements, each of which includes a tension bolt and a support body, wherein the support bodies are arranged at least partially in a radial direction outside of the winding elements, wherein the tension bolt penetrates the support body associated therewith and is screwed into the winding head support by a thread, wherein each of the retaining elements includes a stop surface for coming into contact with the winding head support when screwing in the tension bolts in order thereby to adjust a radial length with which the tension bolts protrude from the winding head support to a predefined dimension, and wherein the predefined dimension is calculated so that the support bodies are not pressed against the winding elements in a resting position of the rotor.