Generator Pole-to-Pole Connection Expansion Joint
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Solution Overview
Problem
Traditional manufacturing methods for pole-to-pole connections in electric generators are time-consuming and induce high residual stresses, leading to reduced mechanical properties and lifetime, especially in large machines.
Innovation Solution
The method involves cutting U-shaped expansion joints from a single plate and connecting them directly to curved bars without bending, using overlapping bars for symmetry, and incorporating an insulating layer with a cooling hole to minimize stress and manufacturing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional manufacturing methods (brazing copper blocks or overlaying lamellas) are used for expansion joints, then the pole-to-pole connections can be manufactured, but the manufacturing time is very long and high residual stresses are induced reducing lifetime
Solution Approach 1:
The expansion joint is divided into a U-shaped element and separate curved bars, allowing independent manufacturing and assembly. This segmentation enables the U-shaped element to be cut from a single plate without bending operations, reducing manufacturing time and residual stresses while maintaining the required flexibility and mechanical properties
Solution Approach 2:
The harmful bending operation is extracted and eliminated from the manufacturing process. Instead of bending a plate to form the U-shaped element, the element is cut directly from a single plate in its final shape, removing the source of high residual stresses and manufacturing time consumption
2Ease of manufacture
If U-shaped elements are bent from plates to form expansion joints, then the expansion joints can be manufactured, but high residual stresses are induced that reduce the element lifetime
Solution Approach 1:
The harmful bending operation is extracted and eliminated from the manufacturing process. The U-shaped element is cut directly from a single plate in its final shape, removing the source of high residual stresses that would otherwise reduce element lifetime
Solution Approach 2:
Instead of forming the U-shape by bending a flat plate (which induces stresses), the element is cut directly into the U-shape from the plate. This inverts the manufacturing approach, achieving the same geometric result without the harmful intermediate bending step
3Adaptability or versatility
If many overlaying copper lamellas are used in expansion joints for large machines, then the required flexibility can be achieved, but the stiffness increases and lifetime is reduced
Solution Approach 1:
The design parameters of the U-shaped element (dimensions, thickness, geometry) are optimized to provide the required flexibility for all generator sizes without needing multiple lamellas. This single-element approach maintains flexibility while avoiding the increased stiffness and reduced lifetime associated with multiple overlaying lamellas
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 allows for rapid manufacturing with minimal residual stress induction, enhancing the mechanical properties and lifetime of pole-to-pole connections, particularly for large generators.
Implementation Method 1
incorporating an insulating layer with a cooling hole to minimize stress and manufacturing time
Implementation Method 2
cooling hole to minimize stress
Data Source
Figure 1~2
Figure 3~4
AI summary
The pole-to-pole connection (3, 4, 5) of an electric generator comprises two curved bars (11) connecting the poles (2a, 2b, 2c, 2d) of an electric generator and an expansion joint in-between. The expansion joint comprises a U-shaped element (12) cut out from a single plate and connected to the curved bars (11). The present invention also refers to a method for manufacturing the pole-to-pole connection.