Multi-Rotor Drive Assembly for Independent Wheel Torque Control

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Solution Overview

Problem

Existing four-wheel independent drive systems in electric vehicles are large, heavy, and costly, failing to meet the requirements of high power density and adaptability.

Innovation Solution

A drive assembly comprising an electric motor with an outer rotor and two independent inner rotors, coupled with a clutch-transmission group, allows for independent control of wheel torques and speeds, eliminating the need for a traditional differential and enabling compact structure and higher power density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a traditional four-wheel independent drive system is used, then each wheel can be independently controlled, but the system becomes large, heavy, and costly

Engineering Contradiction:
Improveindependent wheel controlVSAvoidsystem weight
Core Design Contradiction:
Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent merges two independent drive systems into one integrated unit. The electric motor assembly includes a stator with inner and outer coils, an outer rotor, and two inner rotors that share common structural components. The clutch-transmission group combines two clutch assemblies and two transmission assemblies into a single integrated transmission system, reducing the total number of independent components while maintaining four-wheel independent control capability

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated electric motor assembly serves multiple functions simultaneously. The outer rotor and first inner rotor together drive the left wheel through the first clutch-transmission group, while the second inner rotor drives the right wheel through the second clutch-transmission group. This multi-functional design eliminates the need for separate drive systems for each wheel, reducing overall system weight and complexity

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If a traditional four-wheel independent drive system is used, then wheel control is achieved, but the system complexity and cost increase

Engineering Contradiction:
Improvewheel torque controlVSAvoidsystem complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The clutch-transmission group integrates two clutch assemblies and two transmission assemblies into a unified structure. The first and second clutch assemblies share common mounting structures and control mechanisms, as do the first and second transmission assemblies. This merging reduces the number of independent control systems needed while maintaining the ability to independently control torque to each wheel

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system is segmented into modular functional units: the electric motor assembly with its stator, outer rotor, and two inner rotors; the clutch-transmission group with its two clutch assemblies and two transmission assemblies; and the differential assembly. This segmentation allows for standardized components that can be manufactured and assembled efficiently, reducing overall system complexity

Inventive Principle:
Principle #1Segmentation

3Adaptability or versatility

If four separate electric motors are used for each wheel, then independent control is achieved, but power density decreases

Engineering Contradiction:
Improveindependent drive controlVSAvoidpower density
Core Design Contradiction:
Adaptability or versatilityVSPower

Solution Approach 1:

The patent combines the functions of four separate electric motors into a single integrated electric motor assembly. The stator with inner and outer coils generates magnetic fields that independently control the outer rotor and two inner rotors. This unified motor assembly delivers the combined power output of four separate motors while occupying less space, thereby increasing power density

Inventive Principle:
Principle #5Merging (Combining)

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 system achieves a compact structure and higher power density, allowing for precise control of wheel speeds and torques, enhancing vehicle performance and reducing size and weight.

Implementation Method 1

an electric motor with an outer rotor and two independent inner rotors

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP4696533A1Drive assembly, vehicle, and control method
Publication Date: 2026.02.18 DONGFENG MOTOR GRP
  • EP4696533A1 patent drawingFigure 1
  • EP4696533A1 patent drawingFigure 2
  • EP4696533A1 patent drawingFigure 3

AI summary

A drive assembly, comprising an electric motor (1) and a clutch-transmission group, wherein the electric motor (1) comprises a stator (11), which is provided with an inner coil and an outer coil, an outer rotor (12) rotatably arranged outside the stator (11), and a first inner rotor (13) and a second inner rotor (14) rotatably arranged inside the stator (11), the first inner rotor (13) and the second inner rotor (14) being independently arranged relative to each other; the outer rotor (12) serves as a first mechanical-power output end of the electric motor (1), and the first inner rotor (13) and the second inner rotor (14) serve as a second mechanical-power output end of the electric motor (1). The clutch-transmission group comprises a first input end, a second input end, a first output end and a second output end; the outer rotor (12) and the first inner rotor (13) are each in transmission connection with the first input end. The outer rotor (12) and the second inner rotor (14) are each in transmission connection with the second input end. The first input end is in transmission coupling with the first output end, and the second input end is in transmission coupling with the second output end. The first output end is configured to be in transmission connection with a left wheel (6), and the second output end is configured to be in transmission connection with a right wheel (7).