Gas Turbine Generator Mounting for Stable Rotor-Stator Clearance
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Solution Overview
Problem
The increasing size of electric machines in aircraft gas turbine engines due to rising power demands poses packaging challenges within the limited space available, and existing arrangements are heavy, complex, and inefficient.
Innovation Solution
The solution involves a bearing arrangement with a damper comprising a static and a moveable element, where the electric machine stator is mounted to the moveable element, allowing for relative movement that maintains a consistent running clearance between the rotor and stator, reducing the risk of contact and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the electric machine size is increased to meet rising power demands, then power output is improved, but packaging space availability deteriorates
Solution Approach 1:
The electric machine is nested within the annular space radially inward of the compressor, utilizing otherwise wasted space. The stator is positioned within the compressor's annular region, allowing the electric machine to be embedded in the existing engine structure rather than adding external bulk.
Solution Approach 2:
The invention transitions from conventional axial or external mounting to radial embedding within the compressor annulus. This dimensional repositioning allows the electric machine to occupy a previously unused spatial dimension, achieving compact integration without increasing overall engine envelope.
2Manufacturing precision
If the stator is rigidly mounted to maintain fixed clearance, then manufacturing precision is improved, but reliability deteriorates due to rotor-stator contact risk
Solution Approach 1:
The stator mounting system transitions from rigid to dynamic through the damper assembly. The moveable element allows the stator to float and adjust its position dynamically, accommodating shaft movements while maintaining optimal air gap clearance. This dynamic mounting eliminates the risk of contact despite variations in manufacturing tolerances or operational deflections.
Solution Approach 2:
The damper assembly acts as an intermediary between the rigid engine structure and the electric machine stator. It provides a compliant mounting interface that absorbs discrepancies and maintains consistent air gap clearance, mediating between the need for precision and the need for reliability.
3Speed
If conventional gear-driven arrangements are used, then speed reduction is achieved, but device complexity and weight increase
Solution Approach 1:
The invention extracts and eliminates the gear train from the power transmission system. By directly coupling the electric machine rotor to the compressor shaft, it removes the intermediate gearing components entirely, achieving simplified architecture while maintaining the required speed relationship through direct electromagnetic coupling rather than mechanical gears.
Solution Approach 2:
The electric machine and compressor shaft are merged into a single integrated assembly. The rotor is directly coupled to the compressor shaft, combining the functions of the electric machine drive and compressor drive into one unified power transmission path, eliminating the need for separate gear-driven speed reduction mechanisms.
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 configuration reduces the risk of rotor-stator contact, increases packaging efficiency, and allows for higher power density and efficiency, particularly in permanent magnet electric machines, by maintaining a small consistent air gap and enabling reduced weight and size.
Implementation Method 1
the bearing arrangement comprising a damper comprising a static element and a moveable element
Data Source
AI summary
An aircraft gas turbine engine (10) comprises a main engine spool (22) and a bearing arrangement (36) configured to rotatably support the main engine spool (22). The bearing arrangement (36) includes a damper (41) comprising a static element (42) and a moveable element (39). The gas turbine engine further comprises an electric machine (30) comprising a rotor (34) and a stator (32). The rotor (34) is mounted to the main engine spool (22), and the stator (32) is mounted to the moveable element (39) of the damper to be moveable with the moveable element (39).