Dual-Motor E-Axle Gear Shifting with Constant Torque Delivery
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Solution Overview
Problem
Commercial vehicles require efficient gear shifting to manage power distribution between multiple electric traction motors for smooth acceleration and high-speed operation, while existing systems often lose power during transitions and suffer from inefficiencies due to the need for traditional differentials and gear systems.
Innovation Solution
A method involving two electric traction motors operating in tandem, where one motor stops supplying power while the other doubles its output, and vice versa, allowing seamless gear shifts by disengaging and reengaging gear assemblies to maintain constant torque and power delivery, utilizing a drive differential to combine and split torque between axles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional single motor gear systems are used, then device complexity is reduced, but power loss during gear transitions occurs and acceleration smoothness deteriorates
Solution Approach 1:
The system divides the single motor-gear assembly into two independent motor-gear assemblies (first and second electric motors with respective gear assemblies). This segmentation allows one motor to maintain power delivery while the other undergoes gear transitions, preventing power loss during shifts and enabling smoother acceleration through coordinated operation of both assemblies
Solution Approach 2:
The system performs preliminary gear transitions by having one motor complete its gear shift before the other begins. The control system coordinates the timing so that gear transitions are staged sequentially rather than simultaneously, ensuring continuous power delivery and smooth acceleration without interrupting the vehicle's motion
2Productivity
If traditional differentials and gear systems are used, then device complexity is reduced, but acceleration smoothness and high-speed efficiency deteriorate
Solution Approach 1:
The system merges two independent motor-gear assemblies with a drive differential into a unified power delivery system. The differential combines the output from both motors while allowing them to operate independently, achieving smooth acceleration and high-speed efficiency through coordinated control of both assemblies without requiring complex traditional differential gear systems
Solution Approach 2:
The system implements dynamic control where the control system continuously adjusts the operation of both electric motors based on vehicle conditions. During acceleration, both motors can contribute power; during gear transitions, one motor maintains power while the other shifts. This dynamic coordination optimizes acceleration smoothness and high-speed efficiency while managing the complexity of the dual motor 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
Enables smooth and efficient gear shifting without power loss, improving acceleration and high-speed efficiency by maintaining constant torque and power distribution across multiple axles, reducing windage losses and enhancing overall vehicle performance.
Implementation Method 1
a drive differential configured to combine a first input torque from the first electric motor and a second input torque from the second electric motor and to drive an output shaft using the combined torque
Data Source
AI summary
A vehicle includes a chassis and an electric axle assembly coupled to the chassis. The electric axle assembly includes a first electric motor, a second electric motor, a drive differential configured to combine a first input torque from the first electric motor and a second input torque from the second electric motor and to drive an output shaft using the combined torque, and a first axle coupled to a first tractive element configured to be driven by the output shaft to propel the vehicle.