Dual-Motor Planetary EV Powertrain for Smooth Multi-Ratio Shifting
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Solution Overview
Problem
Electric vehicles face challenges in achieving maximum gradeability and speed while minimizing motor capacity, requiring improved power transfer efficiency and reduced weight to enhance driving range and prevent torque interruption and shift shock.
Innovation Solution
A powertrain design for electric vehicles incorporating a planetary gear with three rotating elements, multiple shift ratios, and dual motors for power transfer, along with a shift assembly configuration that includes external engagement gear trains and a friction clutch for smooth gear shifting, ensuring high power transfer efficiency and minimizing motor capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transmission with multiple gear ratios is added to an electric vehicle, then maximum gradeability and maximum speed are improved, but device complexity increases
Solution Approach 1:
The patent combines two motors with a single planetary gear system to achieve multiple gear ratios. The first motor connects to the sun gear while the second motor connects to the ring gear, and both can simultaneously drive the carrier. This merging approach enables the system to provide multiple gear ratios without requiring separate transmission systems for each motor, thus improving adaptability while controlling device complexity.
2Use of energy by moving object
If motor capacity is reduced to improve driving range, then electrical efficiency is improved, but maximum gradeability and maximum speed deteriorate
Solution Approach 1:
The planetary gear system acts as an intermediary between the two motors and the driving wheels. By using the planetary gear's three rotating elements (sun gear, ring gear, and carrier), the system can provide multiple gear ratios that allow a smaller motor to deliver the necessary torque and speed for maximum gradeability and maximum speed, thus maintaining electrical efficiency while meeting performance requirements.
3Device complexity
If a simple transmission configuration is used, then device complexity is reduced, but torque interruption and gear shifting shock occur
Solution Approach 1:
The patent employs a dynamic control strategy where the two motors can independently adjust their torque output. During gear shifting, one motor can maintain torque delivery while the other motor transitions, ensuring continuous torque transmission to the driving wheels. This dynamic coordination between the two motors through the planetary gear system prevents torque interruption and reduces gear shifting shock, maintaining reliability while using a relatively simple configuration.
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 solution enables electric vehicles to achieve maximum gradeability and speed while reducing motor capacity, improving electrical efficiency, and preventing torque interruption and shift shock, thereby enhancing driving range and fuel efficiency.
Implementation Method 1
a first shift assembly configured to transfer power of the first motor to the first shaft through one of two or more external engagement gear trains having different gear ratios
Implementation Method 2
a shift assembly configuration that includes external engagement gear trains and a friction clutch for smooth gear shifting
Data Source
AI summary
A powertrain for an electric vehicle includes: a planetary gear having a first rotating element, a second rotating element, and a third rotating element, wherein a first rotating element is connected to a first shaft and the second rotating element is connected to a second shaft; a first motor configured to selectively supply power to the first shaft at two or more gear ratios; a first shift assembly configured to transfer power of the first motor to the first shaft through one of two or more external engagement gear trains having different gear ratios; and a second motor configured to selectively supply power to the first shaft and the second shaft. The third shaft is fixedly disposed on a transmission housing, and any two shafts among the first, second and third shafts restrain each other.