Permanent Magnet Rotor Retention via Threaded Hub and Containment Band
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Solution Overview
Problem
In high-speed and high-vibration applications, such as aircraft, permanent magnet rotors on generator shafts tend to become loose and misaligned due to inadequate locking mechanisms, leading to increased complexity, cost, and weight in existing solutions like locking tabs and threaded nuts.
Innovation Solution
A hub with a screw-threaded inner peripheral bore and a containment band is used to securely position and lock the permanent magnet rotor on the rotor shaft, utilizing self-locking threads and an interference fit to ensure precise alignment and retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If locking tabs and threaded locking nuts are used to hold the permanent magnet rotor on the rotor shaft, then the rotor retention is improved, but the device complexity and weight increase
Solution Approach 1:
The hub integrates multiple functions into a single component: the interference fit provides retention, the screw threads provide locking, and the piloting surfaces provide alignment. This eliminates the need for separate locking tabs and locking nuts, reducing assembly complexity while maintaining reliable rotor retention.
2Reliability
If locking tabs and threaded locking nuts are used to hold the permanent magnet rotor on the rotor shaft, then the rotor retention is improved, but the weight increases
Solution Approach 1:
The hub combines retention, locking, and alignment functions into one integrated component, eliminating the additional weight of separate locking tabs and locking nuts while maintaining secure rotor retention through the combined interference fit and screw thread mechanism.
3Ease of manufacture
If interference fit is used to mount the permanent magnet rotor on the rotor shaft, then the assembly is simple, but the rotor becomes loose and misaligned under high speed and vibration
Solution Approach 1:
The hub's inner peripheral bore is segmented into three functional zones: a piloting section with larger diameter for alignment, a threaded section for locking, and an interference fit section for retention. This segmentation allows each zone to perform its specific function effectively, maintaining simple assembly while ensuring reliable rotor alignment under high speed and vibration.
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 solution effectively prevents loosening of the permanent magnet rotor during operation, maintaining precise alignment and reducing assembly complexity and weight by using a hub with a screw-threaded bore and a containment band to securely fasten the rotor to the shaft.
Implementation Method 1
The inner peripheral bore is provided with a screw thread at least over a portion of an axial dimension. The rotor shaft has threads received on the threads on the inner peripheral bore.
Implementation Method 2
The piloting diameter on the inner peripheral bore is larger than a diameter to a tip of the screw thread. The piloting diameter is for piloting on a shaft that is to receive the hub.
Data Source
AI summary
A permanent magnet rotor for use on an electrical generator comprises a hub having an outer peripheral surface and an inner peripheral bore centered on an axis. The inner peripheral bore is provided with a screw thread at least over a portion of an axial dimension. Permanent magnets are mounted on the outer peripheral surface of the hub. A containment band is positioned radially outwardly of the magnets, holding the magnets and the hub together. The hub, a generator rotor incorporating the permanent magnet rotor, and a generator incorporating the permanent magnet rotor are also disclosed and claimed in this application.