Low-Pressure Shaft Generator Layout Without Rotor Support
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Solution Overview
Problem
The increasing demand for electric power in aircraft requires electric generators with higher output, leading to larger and heavier rotors that need support, which can interfere with the operation of finely balanced low-pressure shafts in multi-shaft gas turbine engines, necessitating a mechanism for expansion and contraction without disrupting the shaft's rotation.
Innovation Solution
An electric generator design where the rotor is attached to the low-pressure shaft without additional support structures, allowing for axial displacement due to shaft warpage, using a direct connection with magnets and a multilayer coil stator separated by a distance to prevent interference, eliminating the need for spline couplings or constant speed-drive units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the electric generator output is increased to meet growing power demand, then the power generation capability is improved, but the rotor size and weight increase, requiring additional support structures that interfere with the low-pressure shaft operation
Solution Approach 1:
The invention extracts the support function from the electric generator itself and assigns it to the low-pressure shaft bearing. By removing the need for additional support structures within the generator, the design allows the shaft bearing to handle the support load, thus avoiding interference with shaft operation while maintaining high power output capability
Solution Approach 2:
The low-pressure shaft bearing is designed to perform multiple functions: supporting the shaft rotation and simultaneously supporting the electric generator rotor. This multi-functionality eliminates the need for separate support structures, resolving the contradiction between high power output and device complexity
2Stability of the object's composition
If additional support structures are added to the electric generator, then the rotor stability is improved, but the mechanism complexity increases and interference with low-pressure shaft rotation occurs
Solution Approach 1:
The support function is extracted from the generator's internal structure and relocated to the shaft bearing system. This extraction eliminates complex internal support mechanisms while maintaining rotor stability through the bearing's support capability
Solution Approach 2:
The low-pressure shaft bearing serves itself by simultaneously supporting both the shaft and the generator rotor. This self-service approach eliminates the need for additional dedicated support structures, reducing complexity while maintaining stability
3Adaptability or versatility
If spline couplings or constant speed-drive units are used to accommodate shaft expansion, then the shaft thermal expansion is managed, but the device complexity and potential interference with shaft rotation increase
Solution Approach 1:
The function of accommodating shaft expansion is extracted from complex coupling mechanisms and assigned to the bearing system. The bearing naturally accommodates thermal expansion through its design, eliminating the need for additional coupling devices
Solution Approach 2:
The bearing acts as an intermediary that naturally handles shaft expansion without requiring complex coupling mechanisms. It mediates between the shaft's thermal expansion needs and the generator's rotational requirements, simplifying the overall design
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 the integration of electric generators with low-pressure shafts without interfering with their operation, ensuring reliability and power generation efficiency while avoiding excessive engine length and weight increases, and maintaining rotational balance.
Implementation Method 1
the rotor may include magnets arranged in a circumferential direction of the rotor, and the stator may include a multilayer coil formed of a belt-like electric wire
Data Source
AI summary
An electric generator equipped in a multi-shaft gas turbine engine for aircraft, includes: a rotor attached to the rear end portion of a low-pressure shaft rotatably supported by a bearing in the gas turbine engine; a stator provided around the rotor; wherein the electric generator has no structure to support the low-pressure shaft and the rotor.