Rear Drive Gear Control for 4WD Torque and Terrain Response
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Solution Overview
Problem
Four-wheel drive vehicles face challenges in dynamics, handling stability, and efficiency due to fixed transmission ratios and manual gear switching, which are inadequate for various terrain conditions and power requirements.
Innovation Solution
Implementing a control method that automatically adjusts the gear of the rear axle drive motor based on travel road information and driving mode, allowing different torque outputs in multiple gears to enhance dynamics and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual gear switching is used, then driver control is maintained, but driver distraction increases and response to terrain conditions is delayed
Solution Approach 1:
The system enables self-service by automatically detecting terrain conditions and selecting appropriate gears without driver intervention. The controller monitors wheel slip, vehicle speed, and acceleration to autonomously determine optimal gear selection, freeing the driver from manual gear switching while maintaining responsive terrain adaptation
Solution Approach 2:
The system implements feedback mechanisms by continuously monitoring vehicle operating parameters (wheel slip, speed, acceleration) and using this information to automatically adjust gear selection. The controller processes real-time sensor data to determine when terrain changes require gear adjustments, creating a closed-loop control system that responds dynamically to driving conditions
2Device complexity
If fixed transmission ratio is used, then system complexity is reduced, but adaptability to various terrain conditions deteriorates
Solution Approach 1:
The system transitions from static fixed transmission ratio to dynamic adjustable transmission ratios by incorporating multiple gears in the rear axle drive motor. The controller dynamically selects among first gear, second gear, and third gear based on real-time terrain detection, enabling the vehicle to adapt its transmission characteristics to match varying road conditions while maintaining manageable system complexity through electronic control
3Reliability
If rear axle drive motor operates continuously, then four-wheel drive capability is maintained, but energy loss increases
Solution Approach 1:
The system segments the drive motor operation into distinct gear modes (first gear, second gear, third gear) with different torque characteristics. By dividing the continuous operation into discrete operational segments, the controller can optimize energy efficiency by selecting the most appropriate gear for current conditions, reducing unnecessary energy consumption while maintaining four-wheel drive capability when needed
Solution Approach 2:
The system changes operational parameters by adjusting the transmission ratio through gear switching. The controller monitors operating conditions and changes the transmission parameter by selecting different gears, thereby optimizing the balance between maintaining four-wheel drive capability and minimizing energy losses. The first gear provides high torque for low-speed conditions, second gear for medium conditions, and third gear for high-speed conditions
Data Source
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AI summary
The present disclosure relates to a control method for a four-wheel drive vehicle, a vehicle, a controller, and a storage medium. The control method includes: travel road information and/or a driving mode of the four-wheel drive vehicle is obtained; and a gear of a rear drive of the four-wheel drive vehicle is controlled based on the travel road information and/or the driving mode, where in different gears, a rear axle drive motor of the four-wheel drive vehicle outputs different torques. According to the control method for a four-wheel drive vehicle, the vehicle, the controller, and the storage medium, automatic gear switching can be performed, to automatically control an output torque of the rear axle drive motor and improve dynamics and handling stability of a vehicle. In this way, the four-wheel drive vehicle can better respond to a driving requirement for a special travel road, and driving experience of the four-wheel drive vehicle is improved.