AWD Clutch Control for Smooth Mode Switching
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Solution Overview
Problem
All-wheel drive vehicles face energy efficiency losses and discomfort due to poor rotational synchronization during mode-switching between two-wheel drive and all-wheel drive modes, causing vibrations and torque changes that affect occupants.
Innovation Solution
A control system with a first clutch connecting the propeller shaft and sub-shaft, and a second clutch connecting the sub-shaft to the front axle, utilizing a synchrony determination unit and control units to apply synchronous torque until the second clutch is connected, ensuring smooth and quick transitions between modes without significant torque changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rotation synchronization control is performed quickly during mode-switching, then switching speed is improved, but impact or vibration changes occur in transmission torque causing occupant discomfort
Solution Approach 1:
The system performs preliminary rotation synchronization control by rotating the front axle at a predetermined speed before engaging the non-slip clutch. This preliminary action ensures that the rotational speeds are matched in advance, allowing for quick clutch engagement without causing impact or vibration changes during the switching process.
Solution Approach 2:
The control system dynamically adjusts the rotational speed of the front axle to match the propeller shaft speed before clutch engagement. By continuously monitoring and adjusting speeds in real-time, the system achieves smooth mode-switching without torque fluctuations or vibrations that would affect occupant comfort.
2Reliability
If all wheels are used as drive wheels, then road travel performance is improved, but energy efficiency is reduced
Solution Approach 1:
The system dynamically switches between two-wheel drive and all-wheel drive modes based on road conditions. The non-slip clutch is engaged only when front axle rotation synchronizes with the propeller shaft, enabling temporary four-wheel drive operation for improved road travel performance while maintaining two-wheel drive for normal conditions to preserve energy efficiency.
Solution Approach 2:
The system changes the operational state of the drivetrain by engaging or disengaging the non-slip clutch based on synchronization conditions. This parameter change allows the vehicle to transition between different drive modes, optimizing the balance between road travel performance and energy efficiency according to actual driving needs.
Data Source
AI summary
A vehicle includes a first axle temporary driven by a motor, a second axle permanently connected to the motor via a propeller shaft, and a sub-shaft that connects the propeller shaft and the first axle. A control system for a connection between the motor and the first axle includes a first clutch between the propeller shaft and the sub-shaft, a second clutch between the sub-shaft and the first axle. The first clutch is controlled to continue applying a synchronous torque until the second clutch is determined to be connected. The second clutch is controlled to be connected in response to a determination that the second clutch is connectable.