Permanent Magnet Rotor Assembly With Radial Biasing Retention
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Solution Overview
Problem
The manufacturing of permanent magnet electric motors is complex and labor-intensive due to the need for high tolerances, leading to increased costs and inefficiencies.
Innovation Solution
A rotor assembly with a radially biasing shaft structure that uses preloaded biasing members to securely position and retain a magnet member against a jacket member, allowing for efficient, accurate, and repeatable manufacturing, including features like contoured surfaces and reduced thickness dimensions to ensure precise alignment and retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high tolerances are required for motor parts, then manufacturing precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent changes the tolerance parameters by introducing a tolerance compensation mechanism through the interference fit between the shaft and hub. The shaft diameter is made slightly larger than the hub bore diameter (interference fit), allowing for tolerance accumulation without affecting final assembly precision. This resolves the contradiction by permitting looser individual part tolerances while maintaining overall assembly precision through the interference fit parameter.
Solution Approach 2:
The patent applies preliminary action by pre-assembling the shaft and hub through interference fit before final magnet assembly. The shaft and hub are prepared with specific dimensional relationships (shaft diameter slightly exceeding hub bore) in advance, creating a pre-loaded, precisely positioned foundation that simplifies subsequent assembly steps and reduces the need for tight tolerances on later components.
2Manufacturing precision
If high tolerances are required for motor parts, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The interference fit parameter (shaft diameter slightly larger than hub bore) fundamentally changes the tolerance regime, allowing mass production with standard tolerances rather than custom tight tolerances. This parameter change enables conventional manufacturing processes to achieve the required precision, significantly improving productivity while maintaining assembly quality.
Solution Approach 2:
The patent segments the motor into modular components (shaft, hub, magnets, housing) that can be manufactured independently with standard tolerances and then assembled through the interference fit mechanism. This segmentation allows parallel manufacturing of components, improving overall productivity while the interference fit ensures precise final assembly without requiring all components to have tight tolerances.
3Manufacturing precision
If complex manufacturing methods are used, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent uses a simple parameter change (interference fit with shaft diameter slightly exceeding hub bore diameter) to achieve precise assembly without complex manufacturing methods. This single parameter modification replaces complex multi-step alignment and fastening procedures with a simple press-fit operation, dramatically improving ease of manufacture while maintaining high assembly precision.
Solution Approach 2:
The patent merges the positioning and retention functions into a single interference fit relationship between the shaft and hub. Instead of requiring separate alignment features, fasteners, and retention mechanisms, the interference fit combines these functions into one simple assembly operation, simplifying the manufacturing process while ensuring precise component positioning.
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 approach simplifies and streamlines the manufacturing process, enhancing the efficiency and durability of the motor while maintaining high-quality performance.
Implementation Method 1
The shaft structure includes one or more biasing members which are resiliently flexed radially inward. The biasing members may be bent inward to apply a preload that, in turn, biases the magnet member outward radially.
Data Source
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AI summary
A rotor assembly for a permanent magnet electric motor defines an axis of rotation and includes a jacket member and a magnet member that is received within the jacket member. The magnet member defines a central aperture. The rotor assembly also includes a shaft structure with a base member and a biasing projection that projects from the base member. The biasing projection is received within the central aperture of the magnet member. The biasing projection biases the magnet member toward the jacket member in an outward radial direction away from the axis of rotation for retaining the magnet member and the jacket member together.