4WD Torque Distribution Control During Gear Shifts
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Solution Overview
Problem
Existing control systems for four-wheel drive vehicles struggle to adapt torque distribution and shift time effectively between manual driving and autonomous driving modes, leading to inconsistent ride comfort and traction performance.
Innovation Solution
A control device that dynamically adjusts torque distribution and shift time based on the vehicle's driving mode, prioritizing ride comfort in autonomous driving and reducing shift shock in manual driving, while optimizing traction performance in both modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the torque distribution and shift time are optimized for manual driving (prioritizing acceleration response), then acceleration performance is improved, but ride comfort deteriorates
Solution Approach 1:
The control device dynamically adjusts torque distribution and shift time based on the detected driving mode (manual or autonomous). In manual driving mode, the system prioritizes acceleration response by allowing faster shifts and higher torque to drive wheels. In autonomous driving mode, the system prioritizes ride comfort by smoothing torque transitions and extending shift duration. This dynamic adaptation resolves the contradiction by making the system behavior context-dependent rather than fixed.
Solution Approach 2:
The control device changes key parameters (torque distribution ratio and shift time duration) based on the driving mode. When switching from manual to autonomous mode, the system increases shift time and modifies torque distribution characteristics to reduce shock. This parameter adjustment strategy allows the same transmission system to deliver different performance characteristics appropriate for each operating context, resolving the acceleration vs. comfort trade-off.
2Object-affected harmful factors
If the shift time is extended to reduce shift shock, then ride comfort is improved, but acceleration response deteriorates
Solution Approach 1:
The system dynamically adjusts shift time duration based on driving mode detection. In manual driving mode where acceleration response is critical, the shift time is kept short to maintain responsiveness. In autonomous driving mode where ride comfort is prioritized, the shift time is extended to reduce shock. This dynamic timing adjustment resolves the contradiction between comfort and performance.
Solution Approach 2:
The control device modifies the shift time parameter according to the operating mode. By increasing shift time in autonomous mode and maintaining shorter shifts in manual mode, the system achieves both long-term comfort (reduced shift shock) and short-term performance (acceleration response) as needed, resolving the time-duration contradiction.
3Strength
If the torque distribution is increased to the second drive wheel during gear ratio change, then four-wheel drive traction performance is improved, but shift shock increases
Solution Approach 1:
The torque distribution to the second drive wheel is dynamically adjusted based on whether the vehicle is in manual or autonomous driving mode. In autonomous mode, the system allows higher torque distribution during shifts to maintain four-wheel drive traction performance. In manual mode, torque distribution is reduced during shifts to minimize shock. This dynamic torque management resolves the contradiction between traction and comfort.
Solution Approach 2:
The control device changes the torque distribution parameter during gear ratio transitions based on driving mode. By permitting higher torque to the second drive wheel in autonomous mode during shifts, the system maintains four-wheel drive capability while accepting increased shock. In manual mode, torque is limited during shifts to reduce shock. This parameter modulation resolves the traction-performance vs. shift-shock contradiction.
Data Source
AI summary
The vehicle includes a prime mover, a propeller shaft that transmits a rotational output, a first drive wheel that transmits a rotational output without passing through the propeller shaft, a second drive wheel transmitted through the propeller shaft, a torque distribution unit, and a transmission device. The control device of the vehicle has an autonomous driving mode and a manual driving mode, when changing a gear ratio of the transmission device, the control device controls the torque distribution unit in such a manner that an amount of torque distribution transmitted to the second drive wheel becomes smaller than when the gear ratio of the transmission device is constant, and the amount of torque distribution transmitted to the second drive wheel when changing the gear ratio in the manual driving mode is smaller than the amount of torque distribution when changing the gear ratio in the autonomous driving mode.