Prestressed Insert Element for Electric Motor Groove Fixation
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Solution Overview
Problem
Existing methods for fixing conductor bars in electrical machines and generators face challenges such as high assembly time and costs due to excessive friction, and the impossibility of re-tensioning prestressed groove locking parts, leading to potential safety issues during operation.
Innovation Solution
A method involving a prestressed insert element that is relaxed using heat, mechanical, or chemical means, allowing for partial bridging of gaps and subsequent adjustment of tension using clamping elements like threaded bolts, eccentrics, or clamping wedges, enabling re-tensioning without replacing wedges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If prestressed groove locking parts are used to fix conductor bars, then the fixation reliability is improved, but the assembly time and costs increase due to excessive friction
Solution Approach 1:
The groove locking part is pre-prestressed before assembly to generate initial clamping force on the conductor bars. This preliminary action ensures reliable fixation from the start, reducing the need for excessive friction during assembly and thereby decreasing assembly time while maintaining high fixation reliability.
Solution Approach 2:
The groove locking part incorporates a mechanism to dynamically adjust and re-tension the prestress force during operation. This allows the system to adapt to wear and thermal expansion, maintaining reliable fixation without requiring complete disassembly and reassembly, thus improving both reliability and productivity.
2Reliability
If prestressed groove locking parts are used to fix conductor bars, then the fixation reliability is improved, but the maintenance complexity increases due to impossibility of re-tensioning
Solution Approach 1:
The groove locking part includes a built-in mechanism that allows operators to re-tension the prestress force in situ during maintenance. This dynamic adjustment capability eliminates the need to replace entire wedge assemblies, significantly reducing maintenance complexity while preserving fixation reliability over extended service intervals.
Solution Approach 2:
The groove locking part is designed with self-adjustment features that enable maintenance personnel to re-tension the connection without requiring specialized tools or extensive disassembly. This self-service capability simplifies maintenance procedures and reduces the need for expert intervention, lowering maintenance complexity while ensuring continued reliable fixation.
3Ease of manufacture
If short wedge parts are used to reduce friction, then the ease of manufacture is improved, but the assembly time increases due to multiple assembly steps
Solution Approach 1:
The groove locking part is divided into modular segments that can be manufactured separately with simpler processes and then assembled. This segmentation maintains ease of manufacture for each component while the modular design allows for faster overall assembly compared to manufacturing one large complex wedge, thereby reducing total assembly time.
Solution Approach 2:
The segmented groove locking parts are pre-assembled and pre-prestressed as modules before installation into the final position. This preliminary assembly reduces the complexity and time of the final installation step, reconciling the ease of manufacture of short components with reduced total assembly time through efficient modular integration.
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 reduces assembly time and costs, extends service intervals by allowing re-tensioning of conductor bars, and maintains secure fixation without the need for frequent wedge replacement.
Implementation Method 1
The insert element is then exposed to heat (mechanical vibrations and/or shock waves and/or electromagnetic waves, for example microwaves, UV, VIS or IR radiation, and/or a chemical reaction, for example by adding water or a solvent, are also possible).
Implementation Method 2
The insert element is then exposed to heat... so partially relaxed or is released so that any free space between the conductor bars and the wedge is at least partially bridged by the partially relaxed insert element
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
The invention relates to a method for securing conductor bars (4) in a groove (2) in a stator (1) or rotor of an electric motor or generator. One or more conductor bars (4) are placed in the groove (2), then at least one pre-tensioned insert element (6), which extends in the direction of the groove (2) is introduced into the groove (2) and the latter (2) is sealed by wedges (3) positioned in the vicinity of the groove opening. The insert element (6) is then released by the action of heat and/or mechanical vibration and/or shock waves and/or electromagnetic waves and/or a chemical reaction in such a way that a gap (5) that optionally exists between the conductor bars (4) and wedge (3) is at least partially bridged by the released insert element (6) and/or the conductor bars (4) are pressed into the groove (2) by the wedge (3) via the relaxed insert element (6). In an additional step, a tensioning element (12-14) is then, (or subsequently in the case of maintenance) pushed and/or rotated in or on the wedge (3) and/or in or on the insert element (6) in such a way that either the distance (11) that optionally exists between the wedge (3) and the insert element (6) is bridged by said tensioning element and/or the tension of the insert element (6) is increased.