Rotor Core Distribution Plate for Balanced Magnetic-Polymer Filling

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Solution Overview

Problem

The existing methods for filling rotor cavities in polymer-filled permanent magnet motors often result in unbalanced filling, leading to defects such as incomplete or uneven packing, which can cause rotor deformation and high scrap rates.

Innovation Solution

A rotor core mold assembly is introduced, comprising a rotor stack with cavities and a distribution plate. The distribution plate features a flow channel, an injection gate, and secondary flow channels that are in fluid communication with the rotor stack cavities, allowing for balanced injection filling patterns by optimizing the cross-sectional area and aspect ratio of each cavity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional injection molding process is used to fill rotor cavities, then the manufacturing process is simple, but the filling is unbalanced leading to defects and high scrap rates

Engineering Contradiction:
Improvefilling balanceVSAvoidmolding system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The injection system is segmented into multiple injection gates distributed across the mold, allowing independent control of material flow to different rotor cavity regions. This segmentation enables balanced filling by directing material to specific cavities at controlled rates, preventing defects while maintaining manufacturing precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the mold are provided with locally optimized injection gates and flow channels tailored to the specific geometry and volume requirements of each rotor cavity group. This local quality approach ensures that each region receives material at the optimal rate and pressure, achieving uniform filling balance across all cavities.

Inventive Principle:
Principle #3Local quality

2Productivity

If material is injected quickly to improve productivity, then production speed increases, but filling becomes unbalanced causing defects

Engineering Contradiction:
Improveproduction speedVSAvoidfilling uniformity
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The injection molding system employs dynamic control of material flow through multiple gates, adjusting flow rates and timing in real-time based on cavity filling status. This dynamic approach allows high-speed injection while maintaining balanced filling by continuously adapting material distribution to prevent defects.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

Multiple injection gates enable continuous material flow into rotor cavities simultaneously, eliminating idle time between cavity fillings. This continuous action maintains high productivity while ensuring each cavity receives material at the optimal rate for uniform filling, preventing defects even at high production speeds.

Inventive Principle:
Principle #20Continuity of useful action

3Adaptability or versatility

If rotor cavities have different aspect ratios, then design flexibility is improved, but filling balance becomes difficult to achieve

Engineering Contradiction:
Improvecavity design flexibilityVSAvoidfilling balance
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

Injection gates and flow channels are locally optimized for each rotor cavity group, with gate size, shape, and positioning tailored to the specific aspect ratio and volume of each cavity. This local customization enables the system to handle diverse cavity geometries while maintaining balanced filling across all cavities regardless of their different aspect ratios.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The injection molding parameters (pressure, temperature, flow rate, timing) are adjusted for each cavity group based on their aspect ratios and geometric characteristics. This parameter optimization allows cavities with different aspect ratios to be filled uniformly, achieving both design flexibility and filling balance.

Inventive Principle:
Principle #35Parameter changes

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 ensures that rotor stack cavities are filled at a substantially equal rate, reducing defects and improving the uniformity of mass distribution in the molded rotors, thereby enhancing manufacturing efficiency and reducing scrap rates.

Implementation Method 1

The distribution plate includes a flow channel positioned on the top surface of the distribution plate and extending through the distribution plate, an injection gate positioned proximate the bottom surface of the distribution plate in fluid communication with the flow channel, and a plurality of secondary flow channels coupled between the injection gate and the bottom surface of the distribution plate in fluid communication with the injection gate

Methodology Applied
Scientific EffectFluid flow:

Data Source

PatentEP4496187A1Systems and methods for providing a balanced supply of magnetic-polymer melts in permanent magnet rotors
Publication Date: 2025.01.22 ABB (SCHWEIZ) AG
  • EP4496187A1 patent drawingFigure 1
  • EP4496187A1 patent drawingFigure 2
  • EP4496187A1 patent drawingFigure 3A~3B

AI summary

A rotor core mold assembly including a rotor stack and a distribution plate. The rotor stack has a top surface and at least one rotor pole defined by a plurality of rotor stack cavities. Each of the plurality of rotor stack cavities has an aspect ratio defined by a width of a respective rotor stack cavity and a longitudinal length of the rotor stack. The distribution plate has a top surface and a bottom surface removably locatable on the top surface of the rotor stack to thereby form a fluid seal. The distribution plate includes a flow channel positioned on the top surface of the distribution plate and extending through the distribution plate, an injection gate in fluid communication with the flow channel, and a plurality of secondary flow channels coupled between the injection gate and the bottom surface of the distribution plate in fluid communication with the injection gate.