Stacked-Laminate Rotor Structural Webs for Load Transfer
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Solution Overview
Problem
Stacked-laminate rotary-type permanent magnet motors face mechanical stress issues at high speeds due to material bridges between magnetic rotor barriers and empty cavities, which can diminish torque performance and saliency characteristics when thickening these bridges or using metallic reinforcements.
Innovation Solution
Incorporating geometric features such as structural webs, radially projecting protrusions, and varying slot sizes and locations in the rotor laminates to enhance load transfer between polymeric reinforcement inserts and individual laminates, while maintaining magnetic flux and torque output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If rotor material bridges are thickened to reduce mechanical stress, then mechanical strength is improved, but magnetic flux leakage increases and torque performance deteriorates
Solution Approach 1:
The patent applies composite materials by combining metallic rotor laminates with polymeric reinforcement inserts to create a hybrid structure. The polymeric material provides mechanical reinforcement to reduce stress at high speeds while the metallic laminates maintain magnetic flux paths, thus avoiding the flux leakage problem associated with thickening metallic bridges alone.
Solution Approach 2:
The patent implements local quality by strategically placing polymeric reinforcement inserts only in specific regions where mechanical stress is highest, rather than uniformly thickening all rotor bridges. This localized reinforcement approach maintains optimal magnetic flux paths in critical areas while providing structural support where needed.
2Strength
If polymeric reinforcement inserts are added to rotor laminates, then structural integrity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-forming the polymeric reinforcement inserts with geometric features (protrusions and recesses) before assembly. These pre-formed features facilitate automatic alignment and interlocking with the rotor laminates during stacking, reducing the complexity of the assembly process compared to creating complex features during final assembly.
Solution Approach 2:
The patent segments the rotor construction into separate components: metallic rotor laminates and polymeric reinforcement inserts. This segmentation allows each component to be manufactured independently using optimized processes, then assembled together, which can simplify overall manufacturing compared to creating a monolithic complex structure.
3Stress or pressure
If geometric features are added to enhance load transfer, then mechanical stress distribution is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses composite materials where the polymeric reinforcement inserts provide geometric features (protrusions and recesses) that enhance load transfer. The polymeric material is more tolerant of manufacturing variations than metallic materials, allowing these geometric features to be formed with standard manufacturing capabilities while still achieving effective mechanical coupling.
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 increases structural integrity, minimizes magnetic flux leakage, and enhances torque and power output of electric machines by effectively managing mechanical stress and reinforcing the rotor assembly.
Implementation Method 1
A PM motor is an electric machine that converts electrical energy into rotational mechanical energy using a stator with multiphase electromagnetic windings, and a rotatable rotor that bears an arrangement of permanent magnets
Implementation Method 2
Rotation of the rotor is effected by a magnetic field, produced by the flow of current through the stator windings, interacting with a magnetic field produced by the rotor's permanent magnets
Data Source
AI summary
An electric machine includes a stator with stator slots securing therein electrically conductive windings. A rotor is rotatably mounted adjacent the stator and includes a stack of rotor laminates. Each laminate includes circumferentially spaced poles, each of which includes a magnet slot spaced from an insert slot. These laminate magnet slots cooperatively define the rotor's magnet slots. Likewise, the laminates' insert slots cooperatively define the rotor's insert slots. Magnets are mounted inside the rotor's magnet slots, and non-magnetic inserts are mounted inside the rotor's insert slots. One or more poles of each laminate includes a structural web that extends radially through the magnet and insert slots of that pole. Multiple poles of each rotor laminate lack a radially extending structural web. Each rotor laminate is rotated with respect to a neighboring rotor laminate such that each pole with a structural web axially aligns with a pole without a structural web.