AWD Drive Control for Stable Torque Distribution Switching
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Solution Overview
Problem
The existing drive apparatus for vehicles experiences deterioration in running stability when switching between drive modes due to changes in torque distribution ratios between front and rear wheels during power source switching.
Innovation Solution
The drive apparatus includes a control device that manages torque distribution by switching the power source from one power source to another while adjusting the engagement states of the differential device, keeping the second engagement device engaged to maintain a fixed torque distribution ratio, thereby preventing changes in torque distribution ratios during mode switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the power source is switched from the second power source to the first power source during drive mode switching, then the drive mode can be changed, but the torque distribution ratio between front and rear wheels changes, causing deterioration in running stability
Solution Approach 1:
The control device switches the first engagement device from slip state to engaged state before switching the power source from the second power source to the first power source. This preliminary action ensures that the torque distribution ratio is fixed before the power source transition occurs, preventing changes in torque distribution during switching and maintaining running stability.
Solution Approach 2:
By engaging the first engagement device beforehand, the system prepares the torque distribution mechanism to resist changes during power source switching. The engaged first engagement device acts as a cushioning element that prevents abrupt torque distribution changes, thereby protecting the running stability during the transition.
2Ease of operation
If the first engagement device is kept in slip state during power source switching, then the torque distribution ratio can be controlled, but the running stability deteriorates due to torque distribution changes
Solution Approach 1:
The control device switches the first engagement device from slip state to engaged state before switching the power source. This preliminary engagement action fixes the torque distribution ratio beforehand, ensuring that subsequent power source switching does not cause torque distribution changes that would affect running stability.
Solution Approach 2:
The system dynamically adjusts the state of the first engagement device based on the switching timing. By transitioning the first engagement device from slip state to engaged state at the appropriate moment before power source switching, the system optimizes both torque distribution control and running stability during the transition process.
Data Source
AI summary
A drive apparatus for vehicle comprising a first power source, a first output rotating member, a second output rotating member, a second power source, a differential device, a first engagement device, a second engagement device, and a control device. The control device establishes, as drive modes driving a vehicle, a first drive mode controlling a torque distribution ratio between front wheels and rear wheels by putting the vehicle in all-wheel drive state by power from the second power source while controlling the first engagement device to be in slip state with the second engagement device kept in engaged state, and a second drive mode putting the vehicle in all-wheel drive state by power from the first power source while fixing the torque distribution ratio with both the first engagement device and the second engagement device kept in engaged state.