Plastic Piloting Ring Interference Fit for Motor Rotor Alignment
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Solution Overview
Problem
The high cost of precision machining in traditional metal end caps for rotary dynamoelectric machines due to tight tolerances required for proper centering and alignment of the rotor within the stator.
Innovation Solution
The use of plastic piloting rings in a plastic-to-plastic interference fit with a plastic winding frame to center and align the rotor, allowing for relaxed tolerances and reduced manufacturing costs, as the flexibility of plastic ensures concentricity without compromising motor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional metal end caps with precision machining are used, then proper centering and alignment of the rotor within the stator is achieved, but manufacturing cost increases due to tight tolerances
Solution Approach 1:
The patent changes the material parameter from metal to plastic for the piloting ring, which fundamentally alters the manufacturing approach. Plastic injection molding inherently provides sufficient concentricity (run-out less than 0.05 inches) without requiring tight tolerance machining, thus resolving the contradiction between achieving proper centering and reducing manufacturing cost
Solution Approach 2:
The plastic piloting ring serves as a cost-effective alternative to expensive precision-machined metal rings. The plastic component achieves the necessary alignment function at a fraction of the cost, making it an economical solution for establishing rotor-stator concentricity
2Manufacturing precision
If tight tolerances are applied to piloting ring diameters, then proper bearing centering is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
By changing from metal to plastic material, the patent eliminates the need for complex precision machining operations. The plastic injection molding process naturally produces parts with sufficient concentricity, reducing both tolerance requirements and machining complexity simultaneously
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 significantly reduces manufacturing costs by allowing tolerances up to five to ten times larger than traditional metal piloting rings while maintaining precise centering and alignment of the rotor within the stator, enhancing the efficiency and cost-effectiveness of the assembly process.
Implementation Method 1
plastic piloting rings of respective first and second end caps engaging in a plastic-to-plastic interference fit with a plastic winding frame of a stator
Data Source
AI summary
A rotary machine (e.g., motor or generator) has end caps with plastic piloting rings that engage a stator's plastic winding frame in an interference fit, so that a rotor seated by bearings in the end caps is properly aligned with the stator. The flexibility of the plastic-to-plastic fit allows looser tolerances in comparison to machining of all-metal end caps, while the average circle of the piloting ring's outer diameter still assures proper concentricity of rotor shaft, bearings, piloting rings and stator.