Dual-Motor Powertrain With Seamless Multi-Ratio Planetary Gearing
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Solution Overview
Problem
Existing hybrid electric powertrains for long-haul trucks face inefficiencies due to the need for multiple gear steps, large electric motors, and limited access to lowest gear ratios, leading to increased costs and decreased power efficiency.
Innovation Solution
A powertrain design incorporating two electric motors, a transmission assembly, and a planetary gear with clutch assemblies that allow seamless gear ratio changes without torque interruption, enabling at least three gear ratios and compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple gear steps are used to provide various gear ratios, then the electric motors can operate efficiently across different speeds, but the device complexity and build length increase
Solution Approach 1:
The planetary gear set is nested within the transmission assembly, with the sun gear, planet gears, and ring gear arranged concentrically. This compact nested configuration provides multiple gear ratios (including a lowest gear ratio) while minimizing build length and avoiding the need for multiple separate gear steps that would increase complexity.
Solution Approach 2:
The transmission assembly uses a two-dimensional planetary gear arrangement (sun gear at center, planet gears orbiting, ring gear outer boundary) to achieve multiple gear ratios in a compact footprint, rather than using sequential one-dimensional gear trains that would extend the build length.
2Force
If large electric motors are used to provide high drive torque for heavy vehicles, then sufficient gradeability is achieved, but the device complexity and space requirements increase
Solution Approach 1:
The planetary gear set uses a spherical/concentric arrangement where the sun gear, planet gears, and ring gear are arranged in a circular pattern. This curved geometry efficiently transmits high torque from the electric motors to the output while maintaining a compact motor size, as the torque is distributed through multiple planetary gear contact points rather than requiring a single large motor.
3Use of energy by moving object
If the combustion engine is used to operate at optimal specific fuel consumption, then energy efficiency is improved, but the adaptability to varying driving conditions decreases
Solution Approach 1:
The powertrain system dynamically switches between combustion engine operation and electric motor operation based on real-time driving conditions. The control system monitors parameters such as vehicle speed, acceleration demands, and battery state, then optimally engages the combustion engine for steady-state cruising (achieving optimal SFC) or uses electric motors for transient conditions, hill climbing, or acceleration, providing both efficiency and adaptability.
4Duration of action of moving object
If a large battery is used to ensure sufficient energy for pure electric operation, then the vehicle can run electric for extended periods, but the weight and cost increase significantly
Solution Approach 1:
The battery serves multiple functions: it powers the electric motors during pure electric operation, stores regenerative braking energy, and provides auxiliary power when the combustion engine is running. The hybrid architecture allows the battery to be smaller than a pure electric vehicle would require, as the combustion engine acts as a range extender and supplemental power source, reducing overall battery weight while maintaining extended electric operation capability.
Data Source
AI summary
The present invention provides a powertrain comprising a first electric motor (1), a second electric motor (2), a transmission assembly, a planetary gear (12) and an output shaft (120), wherein the transmission assembly comprises a first input (5) connected to the first electric motor (1), a second input (3) connected to the second electric motor, and at least a first output (23) to which the first electric motor (1) and the second electric motor (2) may provide torque, wherein the first input (5) is connectable to the first output (23) by a plurality of gear sets (7,10,8, 11) being selectable by a first clutch assembly (14), and the second input (3) is connectable to the first output (23) by a plurality of gear sets (7′,10,8′, 11) being selectable by a second clutch assembly (14′), to provide at least two gear ratios between the first output (23) and each of the first input (5) and the second input (3), wherein the gear sets and clutch assemblies are configured to allow a change between the two gear ratios without torque interrupt; and the planetary gear (12) comprises a sun gear (4), a ring gear (6) and a carrier (16), the carrier (16) is connected to the output shaft (120) and the planetary gear (12) is shiftable between a first gear state, a second gear state and a third gear state, in the first gear state the ring gear (6) is kept rotationally stationary to provide a highest possible inherent gear ratio between the carrier (16) and the sun gear (4), in the second gear state a rotational speed of the ring gear (6) depends on the rotation of both the sun gear (4) and the carrier (16), and in the third gear state any two of the ring gear (6), the sun gear (4) and the carrier are kept rotationally constant to each other to provide a 1:1 gear ratio between the sun gear (4) and the carrier (16); and the first output (23) of the transmission assembly is coupled to the sun gear (4).