Electric Aircraft Proprotor Drive With Decoupled Mast Moment Loads
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Solution Overview
Problem
Electric motors in aircraft propulsion systems face catastrophic damage from large mast moment forces that eliminate the air gap between the motor rotor and stator, complicating direct drive powertrains and affecting motor efficiency and reliability.
Innovation Solution
The motor torque and mast moment forces are resolved through separate load paths, with the motor torque transferred to the proprotor primarily via a second load path and the mast moment reacted through the main aircraft structure, maintaining a small but stable air gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If direct drive powertrain is used with electric motor, then motor efficiency is improved by minimizing air gap, but motor reliability deteriorates due to catastrophic damage from large mast moment forces eliminating the air gap
Solution Approach 1:
The patent segments the load paths by introducing a separate mast moment reaction structure that is independent from the motor torque transmission path. This allows the motor to operate with a minimized air gap for efficiency while the separate structure handles mast moment forces, preventing them from eliminating the air gap and causing catastrophic damage.
Solution Approach 2:
The patent introduces an intermediary mast moment reaction structure (such as a mast moment beam or reaction arm) that mediates between the proprotor and the motor. This intermediary component absorbs and reacts mast moment forces before they can reach the motor, allowing the motor to maintain a stable, minimized air gap while still being connected to the proprotor through the direct drive system.
2Power
If air gap is minimized to optimize motor performance, then energy density is improved, but mechanical interference between rotor and stator occurs causing catastrophic effects
Solution Approach 1:
The patent segments the force transmission paths so that mast moment forces are handled by a separate reaction structure rather than being transmitted through the motor. This allows the motor air gap to be minimized for optimal energy density while the segmented load path prevents mast moment forces from causing mechanical interference between rotor and stator.
Solution Approach 2:
The patent provides beforehand cushioning by designing a mast moment reaction structure that preemptively absorbs and redirects large mast moment forces before they can reach the motor. This protective structure acts as a cushion, preventing the forces from eliminating the air gap and causing catastrophic mechanical interference, thus enabling the use of a minimized air gap for optimal performance.
3Device complexity
If large mast moment forces are transmitted through direct drive output shaft, then power transmission is simplified, but motor air gap is eliminated causing catastrophic damage
Solution Approach 1:
The patent segments the powertrain into two distinct load paths: one for motor torque transmission and another for mast moment reaction. This segmentation adds some structural complexity but prevents catastrophic motor failure by isolating the motor from large mast moment forces, thereby improving overall system reliability while maintaining relatively simple direct drive operation.
Solution Approach 2:
The patent introduces an intermediary mast moment reaction structure that stands between the proprotor and the motor. This intermediary component simplifies the overall powertrain design by providing a straightforward structural solution for handling mast moment forces, while simultaneously protecting the motor from catastrophic damage that would occur if these forces were transmitted directly through the output shaft.
Data Source
AI summary
In a first aspect, described herein is a direct drive electric aircraft propulsion wherein the propulsion rotor torque is decoupled from the primary proprotor mast moment forces. A hub shaft locates the propulsion proprotor assembly in space relative to the aircraft nacelle, while a motor torque coupler transfers torque from the electric motor to the propulsion rotor while resolving a negligible amount of mast moment through the electric motor.