EV Planetary Powertrain Shifting Without Torque Interruption
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Solution Overview
Problem
Electric vehicles face challenges in achieving maximum gradeability and maximum speed while minimizing motor capacity, requiring improvements in power transfer efficiency and reducing torque interruption and shift shock.
Innovation Solution
A powertrain design incorporating a planetary gear with three rotating elements, a first motor capable of supplying power at multiple gear ratios, and a second motor for selective power distribution, along with shift assemblies to manage gear engagement and disengagement, ensuring high power transfer efficiency and preventing torque interruption and shift shock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a transmission is disposed in an electric vehicle to reduce motor capacity, then electrical efficiency is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent merges the functions of multiple rotating elements into a single integrated planetary gear structure. The first, second, and third rotating elements are combined in one planetary gear assembly, with the third element serving as a common connection point that can be selectively connected to either the transmission housing or the second shaft. This integration reduces the number of separate components while maintaining multiple gear ratio capabilities, thereby improving electrical efficiency without proportionally increasing device complexity.
Solution Approach 2:
The third rotating element serves multiple functions: it can be selectively connected to the transmission housing to provide gear reduction, or connected to the second shaft to enable direct power transmission. This multi-functional design allows the same component to serve different purposes based on operating conditions, reducing the need for additional specialized components and maintaining system simplicity while achieving multiple gear ratios for improved electrical efficiency.
2Power
If gear shifting is implemented to provide multiple ratios, then motor capacity is reduced, but torque interruption and shift shock occur
Solution Approach 1:
The patent maintains continuous power transmission through the planetary gear system during gear ratio changes. By using the third rotating element as a common connection that can be selectively engaged with different components, the system ensures that power flow is never completely interrupted during shifting operations. The planetary gear structure allows for smooth transition between different gear ratios while maintaining continuous torque transmission to the driving wheels, eliminating torque interruption and shift shock.
3Adaptability or versatility
If a planetary gear with three rotating elements is used, then multiple gear ratios are achieved, but device complexity increases
Solution Approach 1:
The patent implements a dynamic connection system where the third rotating element can be selectively connected to different components based on operating requirements. This dynamic reconfigurability allows the same planetary gear structure to provide multiple gear ratios without requiring separate fixed gear trains for each ratio. The selective connection mechanism enables the system to adapt its gear ratio capability while maintaining a relatively simple base structure, avoiding the complexity that would result from providing all gear ratios through fixed, separate gear trains.
Data Source
AI summary
A powertrain for an electric vehicle includes: a planetary gear including a first rotating element, a second rotating element, and a third rotating element, where the first rotating element is connected to a first shaft, the second rotating element is connected to a second shaft, and the third rotating element is connected to a third shaft; a first motor supplying power to the first shaft at all times; and a second motor selectively supplying power to the first shaft and the second shaft. The third shaft is fixedly connected to a transmission housing, and any two shafts among the first, second and third shafts restrain each other.