Hydrogenerator Rotor Rim Support Repair Using Thrust Plates
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Solution Overview
Problem
Hydrogenerators experience wear and fatigue at the rim support ledges due to friction and operational forces, leading to damage such as fracture, which is costly and time-consuming to repair, with existing methods either being expensive or providing inadequate support.
Innovation Solution
The method involves attaching thrust plates to the top of spider posts to support the rim, reducing stress concentration and friction, and using sleeve bolts for periodic tightening to compensate for wear, effectively replacing the rim ledge with a stronger, more ductile material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rim is supported on the rim support ledges, then the structure is simple, but wear and fracture occur due to friction and stress concentration
Solution Approach 1:
Thrust plates are introduced as intermediary components between the rim and spider posts. These plates distribute the rim weight over a larger area and redirect forces to the stronger spider posts, eliminating direct contact between the rim and vulnerable ledges. The thrust plates act as mediators that transfer loads through more durable pathways, preventing ledge fracture while maintaining structural simplicity.
Solution Approach 2:
Instead of supporting the rim from below on ledges (original approach), the invention inverts the support direction by placing thrust plates on top of spider posts to support the rim from above. This inversion redirects gravitational and operational forces through the stronger spider posts rather than through the weaker ledges, fundamentally changing the load path to eliminate wear and fracture problems.
2Strength
If stronger materials are used at the rim support ledges, then fracture resistance improves, but manufacturing cost and complexity increase
Solution Approach 1:
The invention extracts the rim support function from the ledges themselves and relocates it to separate thrust plates mounted on spider posts. This separation allows the ledges to be simple, easy-to-manufacture components while the thrust plates handle the strength and durability requirements. The support function is taken out of the original location and implemented elsewhere with more suitable components.
3Ease of manufacture
If the rim support structure is simplified, then manufacturing is easier, but friction and wear at contact points increase
Solution Approach 1:
The invention transitions from a one-dimensional point contact (rim on ledge) to a two-dimensional distributed contact area through the thrust plates. By spreading the contact over the larger surface area of the thrust plates, friction and wear are distributed across a greater area, reducing stress concentration and material loss while maintaining manufacturing simplicity.
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 approach extends the lifespan of the rotor rim and spider by redistributing weight, reducing friction, and controlling fatigue cycles, providing a cost-effective and durable repair solution for hydrogenerators.
Implementation Method 1
The weight of the rim and the poles are supported on the vertical posts of the spider arms
Implementation Method 2
The rim is supported on the rim support ledges, and is mounted on the spider arms by a friction fit
Data Source
AI summary
A method for repairing an electric generator having a rotor that rotates about a vertical axis, the rotor including a spider having a number of spider arms extending radially away from the axis, and a rim surrounding the spider. The weight of the rim is normally carried at least in part by rim support ledges of the spider arms. The method for repair includes supporting the rim from the top of the spider and thereby relieving some or all of the weight of the rim being supported by the rim support ledges.