Dual-Motor EV Drivetrain with Split Gear Ratios for Torque Efficiency
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Solution Overview
Problem
Conventional electric vehicle drive systems with identical front and rear wheel electric motors and reducers result in inefficient torque utilization during acceleration, leading to wasted torque output from the front wheels due to differing contact friction and efficiency characteristics at different rotating speeds.
Innovation Solution
A drive system with front and rear wheel electric motors of the same specification but with different transmission ratios for their respective reducers, allowing dynamic torque distribution to maximize efficiency, and a method to control the motors based on accelerator and brake pedal input to optimize torque application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If identical transmission ratios are used for front and rear wheel reducers, then manufacturing cost is reduced and device complexity is lowered, but torque utilization efficiency deteriorates and energy waste increases
Solution Approach 1:
The patent applies different transmission ratios to the front and rear wheel reducers based on their specific operational requirements. The front wheel reducer uses a first transmission ratio optimized for front wheel characteristics, while the rear wheel reducer uses a second transmission ratio optimized for rear wheel characteristics. This local differentiation allows each wheel to operate at its optimal efficiency point, resolving the contradiction between manufacturing simplicity and torque utilization efficiency.
Solution Approach 2:
The patent changes the transmission ratio parameter differently for front and rear wheel reducers. By setting the first transmission ratio for the front wheel reducer and the second transmission ratio for the rear wheel reducer, the system optimizes torque distribution according to the different friction characteristics and efficiency curves of front and rear wheels, thereby improving overall energy utilization without significantly increasing manufacturing complexity.
2Loss of energy
If different transmission ratios are used for front and rear wheel reducers, then torque utilization efficiency is improved and energy waste is reduced, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent implements local quality by tailoring the transmission ratio of each reducer to the specific characteristics of its corresponding wheel. The front wheel reducer is designed with a first transmission ratio that matches front wheel friction characteristics, while the rear wheel reducer uses a second transmission ratio suited for rear wheel characteristics. This targeted approach improves torque utilization efficiency without requiring complete system redesign.
Solution Approach 2:
The patent introduces asymmetry by using different transmission ratios for the front and rear wheel reducers rather than a symmetric identical configuration. This asymmetric design allows the system to exploit the different friction and efficiency characteristics of front and rear wheels, optimizing overall performance while maintaining a relatively simple structural implementation.
3Force
If peak torque is applied to front wheels during acceleration, then acceleration force is maximized, but torque waste occurs due to insufficient contact friction
Solution Approach 1:
The patent changes the transmission ratio parameter for the front wheel reducer to a first transmission ratio that is optimized for the front wheel's friction characteristics. This parameter adjustment ensures that the torque delivered to the front wheels matches their actual traction capacity, preventing torque waste while maintaining effective acceleration force. The different transmission ratio for the rear wheel further optimizes the overall torque distribution during acceleration.
Data Source
AI summary
A drive system for an electric vehicle and a method for controlling the same. The drive system includes: a front wheel electric motor and a rear wheel electric motor of the same specification; a front wheel reducer whose output shaft is operatively coupled to a front wheel drive axle of the electric vehicle via the front wheel electric motor; and a rear wheel reducer whose output shaft is operatively coupled to a rear wheel drive axle of the electric vehicle via the rear wheel electric motor, wherein the front wheel reducer has a transmission ratio different than that of the rear wheel electric motor.