Dual-Motor Differential Drive Layout for Seamless Torque Vectoring
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Solution Overview
Problem
Existing electric drive systems for motor vehicles lack flexibility in propulsion modes, limiting efficiency and torque distribution between driven wheels.
Innovation Solution
The system incorporates two electric machines with switching elements for differential and transmission operations, allowing for single wheel drive, torque vectoring, and efficient mode switching without load interruption, with a compact design featuring an axially overlapping transmission stage and differential gear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single electric machine with differential gear is used, then the device complexity is reduced, but the adaptability and versatility of propulsion modes are limited
Solution Approach 1:
The first electric machine is designed to perform multiple functions by coupling with different components through switching elements. It can couple with the first differential output shaft for direct differential operation, or with the transmission input shaft for geared operation, enabling a single machine to provide multiple propulsion modes including normal differential drive, torque vectoring, and high-torque modes.
Solution Approach 2:
The system employs switching elements that dynamically reconfigure the coupling relationships between electric machines, differential gear, and transmission stage. These switching elements enable the first electric machine to be dynamically connected or disconnected from different components, allowing flexible transition between various propulsion modes without mechanical intervention during operation.
2Volume of moving object
If the transmission stage is arranged axially overlapping the differential gear, then the installation space is reduced, but the manufacturing and assembly complexity increases
Solution Approach 1:
The transmission stage is positioned to axially overlap with the differential gear, creating a nested spatial arrangement where one component occupies the same axial space as another. This nesting approach minimizes the overall axial length of the drive system, reducing installation space requirements while maintaining functional independence of both components.
3Adaptability or versatility
If mode switching between different electric machine configurations is enabled, then the adaptability improves, but the switching complexity and potential load interruption increases
Solution Approach 1:
The switching elements are designed to enable seamless transition between different propulsion modes without interrupting the power flow to the wheels. The system maintains continuous useful action by ensuring that at least one power transmission path remains active during mode transitions, preventing load interruption and maintaining reliable power delivery throughout the switching process.
Data Source
AI summary
A motor vehicle electric drive system includes first and second electric machines, arranged coaxial to each other and respectively having first and second rotors, a differential gear having a differential input shaft and a first and second differential output shafts arranged coaxially to the first rotor. A transmission stage has a transmission input shaft and a transmission output shaft. The transmission output shaft is connected in a rotationally fixed manner with the differential input shaft. A first switching element couples the first rotor in a rotationally fixed manner with the first differential output shaft. A second switching element couples the second rotor in a rotationally fixed manner with the second differential output shaft. A third switching element couples the first rotor in a rotationally fixed manner with the differential input shaft. A fourth switching element couples the second rotor in a rotationally fixed manner with the transmission input shaft.