Electric Vehicle Powertrain Planetary Gear Torque Continuity
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Solution Overview
Problem
Electric vehicles face limitations in increasing their travel distance per charge while maintaining high power efficiency, hill-climbing ability, and speed performance, with existing transmissions often causing torque interruption and gear-shift shocks.
Innovation Solution
A power train configuration for electric vehicles utilizing a planetary gear set with three rotation elements, two motors, and multiple transmission devices to provide adjustable gear ratios and prevent torque interruption, featuring coaxial shafts and gear engagement mechanisms to ensure smooth power transfer and reduce weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a transmission is mounted to increase allowable travelling distance and reduce motor size, then power efficiency is improved and motor volume is reduced, but device complexity increases
Solution Approach 1:
The power train is segmented into two independent motor units (first motor with first transmission device, second motor with second transmission device) that can operate independently or in combination. This segmentation allows each motor-transmission pair to be optimized for specific functions while maintaining overall system efficiency without requiring a single complex transmission system.
Solution Approach 2:
The planetary gear set serves multiple functions: it acts as a gear train for the first motor, provides direct power transmission path, and can be selectively connected to either motor. This multi-functionality reduces the need for separate transmission components for each motor, thereby reducing overall device complexity while maintaining power efficiency.
2Volume of moving object
If existing transmissions are used to provide gear ratios, then motor size can be reduced, but torque interruption and gear-shift shocks occur
Solution Approach 1:
The system maintains continuous torque transmission to the driving wheel through dual motor configuration. When one motor is disengaged or during transmission switching, the second motor continues to supply torque, ensuring uninterrupted power delivery and eliminating torque interruption and gear-shift shocks.
Solution Approach 2:
Before disengaging a motor or switching transmission gears, the system prepares by having the second motor ready to immediately take over power supply. This preliminary preparation ensures seamless transition without torque interruption, maintaining reliable and smooth power transmission.
3Device complexity
If a simple transmission configuration is used, then device complexity is reduced, but power transmission efficiency decreases
Solution Approach 1:
The transmission system dynamically switches between different power transmission paths: direct connection mode (high efficiency, simple path) and planetary gear train mode (variable ratios, controlled power flow). This dynamic adaptability allows the system to maintain high power transmission efficiency while providing gear ratio variability when needed, without requiring a permanently complex configuration.
Data Source
AI summary
A power train for an electric vehicle may include a planetary gear set including three rotation elements having a first rotation element, a second rotation element and a third rotation element, wherein the first rotation element is connected to a first shaft, the second rotation element is connected to a second shaft, and the third rotation element is connected to a third shaft; a first motor mounted to selectively supply power to the first shaft in two or more gear ratios; and a second motor mounted to selectively supply power to the first shaft in two or more gear ratios. The third shaft is configured to be fixed to a transmission housing, and any two of the first shaft, the second shaft, and the third shaft are configured to be coupled to each other.