Dual-Rotor Motor With Variable Magnetic Path for Higher Torque Density

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Solution Overview

Problem

Dual rotor motors face challenges in maximizing torque density due to fixed magnetic path lengths, which restricts their efficiency when both inner and outer rotors rotate at the same speed.

Innovation Solution

A dual rotor motor design incorporating a stator variable unit made of wave silicon steel plates and a pressing mechanism that adjusts the curvature of these plates to intermittently or continuously vary the magnetic path length between inner and outer teeth, allowing for reduced reluctance and increased torque density when both rotors rotate at the same speed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the magnetic path length is fixed in a dual rotor motor, then the structure is simple and reliable, but the torque density cannot be maximized when inner and outer rotors rotate at the same speed

Engineering Contradiction:

Improvetorque densityVSAvoidmagnetic path structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The magnetic path structure is made dynamically adjustable through wave silicon steel plates that can change their curvature state. By applying axial pressure to the wave silicon steel plates, the magnetic path length can be varied between connected and disconnected states, allowing the motor to optimize torque density when inner and outer rotors rotate at the same speed while maintaining structural simplicity during normal operation

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The physical state of the wave silicon steel plates is changed by applying axial pressure, transforming them from a curved state (magnetic path disconnected) to a flattened state (magnetic path connected). This parameter change allows the magnetic path length to be adjusted, thereby optimizing torque density without permanently complicating the structure

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If wave silicon steel plates are used to vary the magnetic path, then the magnetic path connection state can be adjusted, but the mechanical strength of the stator may be compromised

Engineering Contradiction:

Improvemagnetic path connection stateVSAvoidstator mechanical strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

Non-magnetic blocking blocks are strategically placed at specific locations within the stator to provide localized structural support. These blocking blocks reinforce the stator at critical points where mechanical strength is needed, while allowing the wave silicon steel plates to freely deform in other regions for magnetic path adjustment

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The stator employs a composite structure combining wave silicon steel plates with non-magnetic blocking blocks. The wave silicon steel plates provide magnetic path variability while the non-magnetic blocking blocks contribute mechanical strength, creating a composite system that achieves both adaptability and structural integrity

Inventive Principle:

Principle #40Composite materials

3Adaptability or versatility

If a pressing mechanism is added to adjust the wave silicon steel plates, then the magnetic path can be varied, but the device complexity increases

Engineering Contradiction:

Improvemagnetic path variabilityVSAvoidpressing mechanism structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The pressing mechanism replaces complex multi-component mechanical systems with a simplified axial pressure application system. By using a single-direction pressure source (such as a spring or actuator) applied to the wave silicon steel plates, the mechanism achieves magnetic path variation without requiring complex linkages, gears, or multiple actuators

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 adjustable magnetic path connection state enhances torque density by reducing reluctance and enabling stable independent driving of the inner and outer rotors, while maintaining mechanical strength through the use of non-magnetic blocking blocks.

Implementation Method 1

The stator variable unit may be deformed by the pressure in an axial direction provided by the pressing mechanism

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

a pressing mechanism provided to provide the pressure in the axial direction to the stator variable unit

Methodology Applied

Scientific EffectMechanical compression: Compression

Implementation Method 3

a return spring provided to provide an elastic force so that the piston returns when the piston releases the pressure applied to the wave silicon steel plates

Methodology Applied

Scientific EffectElastic recovery: Elasticity

Data Source

PatentUS12191724B2Dual rotor motor

Publication Date: 2025.01.07 HYUNDAI MOTOR CO LTD

AI summary

A dual rotor motor includes: an inner rotor and an outer rotor; a stator disposed between the inner rotor and the outer rotor; a stator variable unit provided inside the stator to intermit a magnetic path between an outside and an inside of the stator according to a pressure in an axial direction; and a pressing mechanism provided to provide the pressure in the axial direction to the stator variable unit.