Stator Core Removal Using Horizontal Sliding and Frame Tilting
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Solution Overview
Problem
The existing methods for removing and replacing a stator core in electric generators are time-consuming, labor-intensive, and require extensive space and heavy lifting equipment, posing risks of damage to the core and frame during vertical lifting and necessitating piecewise disassembly and reassembly.
Innovation Solution
A method and apparatus for removing and replacing a wound stator core as a single unit in a horizontal orientation, using lifting trunnions, jacking tools, and specialized support structures like pilot shafts and lift blocks to minimize disassembly and avoid vertical lifting, allowing for the core to be extracted and reinstalled with minimal disruption and without the need for expansive crane rigging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the stator core is removed using conventional vertical lifting methods, then the core can be extracted from the generator frame, but extensive space and heavy crane rigging are required, and damage risk increases
Solution Approach 1:
Instead of vertically lifting the core upward through the frame, the patent inverts the approach by tilting the entire generator frame on its side and sliding the core horizontally outward. This inversion of the removal direction eliminates the need for overhead cranes and vertical lifting space, allowing core extraction using only horizontal sliding motion and minimal equipment.
Solution Approach 2:
The patent introduces tilt trunnions as intermediary support structures that enable the generator frame to be tilted at controlled angles. These trunnions act as mediators between the frame and the ground, allowing the frame to pivot from vertical to horizontal orientation without requiring direct vertical lifting of the entire assembly, thereby simplifying the equipment needed.
2Ease of manufacture
If the stator core is removed piecewise rather than as a single unit, then disassembly complexity is reduced, but time consumption and labor intensity increase
Solution Approach 1:
The patent segments the removal process into two distinct phases: Phase 1 involves tilting the frame and sliding the core horizontally outward as a complete assembly, while Phase 2 involves resetting the frame to vertical orientation. This segmentation allows the core to be removed intact without piecewise disassembly, maintaining structural integrity while reducing overall time and labor requirements.
Solution Approach 2:
The patent performs preliminary tilting of the generator frame before attempting core removal. By pre-positioning the frame in a tilted orientation, the core is already in the optimal position for horizontal extraction, eliminating the need for intermediate disassembly steps and reducing the total time required for the replacement operation.
3Ease of operation
If the generator frame is tilted for core removal, then horizontal sliding extraction is enabled, but additional support structures and adjustment mechanisms are required
Solution Approach 1:
The patent employs counterbalancing mechanisms including hydraulic jacks and tilt trunnions that support the generator frame's weight during the tilting process. These counterweight systems offset the heavy mass of the frame, allowing it to be tilted and positioned at precise angles without requiring excessively powerful lifting equipment, thereby managing the complexity of the tilting mechanism.
Solution Approach 2:
The patent utilizes hydraulic jacks as the actuating mechanism for tilting the generator frame. Hydraulic systems provide controlled, high-force actuation that can precisely position the frame at the required tilt angles. The hydraulic mechanism is more space-efficient and easier to control than alternative mechanical systems, managing the complexity while enabling the horizontal sliding extraction method.
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
Enables efficient and safe removal and replacement of the stator core with minimal disassembly, reducing the risk of damage and operational complexity, while allowing for servicing of internal generator frame components, and can be applied to other dynamoelectric machines.
Implementation Method 1
raising the frame with hydraulic jacks
Implementation Method 2
application of an axial force to the stator core with the cable to slide the core on the shaft and out from the frame
Implementation Method 3
A layer of lubricant is applied between an outer surface of the shaft and an inner surface of the core bore to reduce friction as the core is moved along the shaft
Implementation Method 4
as the core is moved along the shaft
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
Removing a generator core (10) from a frame (24) includes removing electrical and mechanical connections between the core and components external to the frame; installing a lift support assembly (34, 38, 42, 46) outboard of the core at each of an exciter end and a turbine end of the frame; installing a pilot shaft support assembly (50, 70, 73) between an inner surface of a core bore (10D) and an outer surface (40A) of a pilot shaft (40) at each of the exciter end and the turbine end of the frame; installing the pilot shaft through the first and second pilot shaft support assemblies and the core bore, the pilot shaft supported by the lift support assembly at the exciter end and the turbine end; decoupling the core and the frame; and activating a force-producing device (90) to slide the core out of the frame.