Patch Ring Assembly for Turbomachine Shaft Interference Fit
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Solution Overview
Problem
Turbomachine components, particularly compressor and turbine shafts, experience wear and tear leading to damage and reduced operational life, with existing repair methods like post-operational machining affecting the desired contact interference between shafts.
Innovation Solution
A patch ring is introduced between the rabbet joints of the compressor and turbine shafts, comprising a main body and arms that provide design-required interference and prevent axial movement, allowing for thermal expansion and cooling air flow, thereby maintaining alignment and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If post-operational machining is performed on the rabbet joint to restore design interference, then the contact interference between shafts is restored, but the desired contact interference deteriorates over multiple service intervals
Solution Approach 1:
The patch ring is divided into a main body portion and arm portions that can be selectively positioned and adjusted. This segmentation allows the repair system to be customized for different wear patterns and service intervals, maintaining precise contact interference over extended periods without requiring repeated machining operations
Solution Approach 2:
The patch ring is pre-configured with specific geometric features and interference characteristics before installation. This preliminary preparation ensures that the design-intended contact interference is restored immediately upon installation and maintained throughout the service life, eliminating the need for multiple post-operational machining cycles
2Reliability
If the rabbet joint is machined repeatedly to restore interference, then the contact between shafts is maintained, but the operational life of the shafts is reduced
Solution Approach 1:
The patch ring serves as an intermediary component between the compressor shaft and turbine shaft, absorbing wear and maintaining contact interference without requiring repeated machining of the shafts themselves. This mediator approach preserves the original shaft geometry while ensuring reliable contact over extended operational periods
Solution Approach 2:
Instead of repeatedly machining the valuable shaft components, the wear is transferred to the disposable patch ring which can be easily replaced. This allows the expensive shafts to be recovered and reused multiple times while the cheaper patch ring is discarded after a single service interval
3Stability of the object's composition
If a rigid connection is made between shafts to maintain alignment, then axial movement is prevented, but thermal expansion is restricted
Solution Approach 1:
The patch ring incorporates dynamic characteristics that allow it to adapt to thermal conditions. The arm portions can flex and the main body can expand/contract with temperature changes, maintaining alignment stability while accommodating thermal expansion through controlled deformation rather than rigid constraint
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
The patch ring effectively maintains the design-intended interference between the shafts, reduces wear, and extends the operational life of turbomachine components by preventing axial movement and accommodating thermal expansion.
Implementation Method 1
allowing for thermal expansion
Data Source
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AI summary
Shaft assemblies, turbomachines, and methods of servicing a turbomachine are provided. A shaft assembly includes a first shaft having a first rabbet annularly defined therein. The first rabbet includes a first axially extending face and a first radially extending face. A second shaft coupled to the first shaft. The second shaft includes a second rabbet annularly defined therein and positioned opposite the first rabbet. The second rabbet includes a second axially extending face and a second radially extending face. A patch ring is mounted between the first rabbet and the second rabbet. The patch ring includes a main body positioned between and in contact with the first axially extending face and the second axially extending face. A first arm extends radially outward from the main body, and a second arm extends radially inward from the main body.