Dual-Machine Drive Shaft Layout With Planetary Torque Summing
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Solution Overview
Problem
Existing drive devices for electric vehicles struggle to provide a high mechanical torque while maintaining a compact and reliable architecture, often requiring more powerful rotating machines to overcome obstacles like slopes, and fail to efficiently distribute torque to the wheels when one machine is damaged.
Innovation Solution
A drive device comprising two rotating machines with a first planetary gear train and a differential that transmits the combined torques from both machines to a drive shaft, ensuring reliability and increased torque by controlling each machine for optimal efficiency, with the rotating parts of the machines positioned coaxially and the differential radially inside the gear train.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single rotating machine is used to drive the wheels, then the device complexity is reduced, but the reliability decreases because the drive shaft cannot be driven if the machine is damaged
Solution Approach 1:
The drive system is segmented into two independent rotating machines (first and second rotating machines) that can operate independently. Each machine can drive the drive shaft separately, ensuring that if one machine fails, the other can still provide drive capability, thus improving reliability while maintaining manageable system complexity through modular design
2Force
If a more powerful rotating machine is used to increase mechanical torque, then the torque capability is improved, but the device complexity and size increase
Solution Approach 1:
Two rotating machines are merged into a single drive system where their torques are combined through a differential mechanism. The first rotating machine connects through a planetary gear train to the differential, while the second rotating machine connects directly to the differential. This combination allows the system to achieve higher total torque output without requiring a single excessively powerful machine, thereby reducing complexity and size
3Force
If a planetary gear train is used to increase mechanical torque, then the torque multiplication is improved, but the adaptability to distribute torque to wheels at different speeds decreases
Solution Approach 1:
The planetary gear train is nested within the overall drive system that includes the differential. The planetary gear train provides torque multiplication from the first rotating machine, while the differential receives torque from both the planetary gear train and the second rotating machine, then distributes it to the drive shaft. This nested configuration allows both torque multiplication and flexible torque distribution to wheels at different speeds to coexist
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 drive device achieves higher resultant mechanical torque and improved reliability by summing torques from two machines, maintaining compactness and extending the service life of the drive shaft through efficient torque distribution, even in the event of machine failure.
Implementation Method 1
a first planetary gear train comprising a first ring gear fixed with the frame, a sun gear mobile in rotation with respect to the ring gear and a planet carrier mobile in rotation with respect to the ring gear, the rotating part of the first rotating machine being integral in rotation with the planet carrier of the planetary gear train
Implementation Method 2
a differential arranged between the first planetary gear train and the drive shaft in the sense of torque transmission, comprising a second ring gear rotationally fixed to the sun gear of the first planetary gear train, the differential being configured to transmit a resultant torque to the drive shaft
Data Source
AI summary
A drive device includes a frame, a first rotating machine including a fixed part and a rotating part, and a second machine including a fixed part and a rotating part configured to transmit a second torque. A planetary gear train includes a first ring gear, a sun gear and a planet carrier which can rotate with respect to the first ring gear, the rotating part of the first rotating machine being fixed with the planet carrier. Also included is a drive shaft, a differential configured to transmit a resulting torque to the drive shaft. The rotating part of the second machine transmits the second torque to the differential.