In-Hub Generator Using Gear Assembly for Propeller Power
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Solution Overview
Problem
Existing electric generator systems in turbo-prop engines face issues with maintenance requirements, weight, and complexity due to wear-prone brushes and slip-rings, and reliance on large magnets and auxiliary power units for power generation and engine restarting.
Innovation Solution
A compact electric power generation system is integrated within the propeller hub, utilizing a gear assembly to allow relative rotation between generator parts, enabling power generation during propeller rotation and providing power for blade pitch adjustment and engine restarting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If brushes and slip-rings are used to transfer power to the rotating propeller assembly, then electric power can be provided to the motor, but maintenance requirements increase due to wear
Solution Approach 1:
The patent replaces the mechanical brush and slip-ring contact system with an inductive coupling system using electromagnetic fields. The stator winding on the stationary side generates a magnetic field that induces current in the rotor winding on the rotating side, eliminating mechanical contact and associated wear, thereby improving reliability while maintaining power transfer capability.
2Power
If large magnets and windings are used to generate power at hub rotational speed, then sufficient electric power can be provided, but device complexity and size increase
Solution Approach 1:
The patent employs a gear assembly that dynamically adjusts the rotational speed relationship between the propeller hub and the generator rotor. The gear ratio allows the generator to operate at an optimized speed different from the hub speed, enabling smaller magnets and windings to produce the required power, thereby reducing overall system complexity and size.
Solution Approach 2:
The gear assembly acts as an intermediary mechanism between the propeller hub and the generator rotor. It transmits and modifies the rotational motion, allowing the generator to operate at optimal speeds for efficient power generation with reduced component sizes, thus resolving the contradiction between power output and system complexity.
3Adaptability or versatility
If auxiliary power units or large battery systems are used for engine restarting, then engine can be restarted during flight, but weight and system complexity increase
Solution Approach 1:
The in-hub generator system serves multiple functions: it provides electrical power for normal propeller blade pitch actuation, generates power for engine restarting during flight, and supplies emergency electrical power during engine failures. This multi-functionality eliminates the need for separate auxiliary power units or large battery systems, reducing aircraft weight while maintaining adaptability for various operational scenarios.
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 solution reduces maintenance needs, minimizes weight, and enhances reliability by providing a self-contained, efficient power source for both normal operation and emergency situations, such as engine failures, while eliminating the need for auxiliary systems.
Implementation Method 1
generating electric power by rotating the propeller hub about the axis such that the plurality of first generator parts rotate relative to the plurality of second generator parts
Data Source
Figure 1
Figure 2
AI summary
A power generation unit for generating electric power within a rotating reference frame includes a generator 58 and a gear assembly 63. The generator has a plurality of first generator parts 64 disposed concentrically with and radially outward from a plurality of second generator parts 66. The gear assembly is rotatably attached to the second generator parts and configured to allow relative rotation between the first and second generator parts caused by a single rotating component. The generator and the gear assembly are axially disposed along a common rotational axis.