Hybrid AWD Torque Control for Bump-Climbing Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In all-wheel-drive vehicles equipped with torque-sensitive limited slip differentials, rough accelerator operations during bump climbing can lead to increased input torque, resulting in differential limitation between wheels and deterioration of straight traveling stability.
Innovation Solution
A hybrid all-wheel-drive vehicle with a torque-sensitive limited slip differential system, including front, center, and rear limited slip differentials, an accelerator-operation detection unit, and a control unit that adjusts the engagement force of the center limited slip differential mechanism to reduce input torque during bump climbing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the torque of the motor that rotationally drives the rear wheels is increased to climb over a bump, then the climbing performance is improved, but the input torque of the limited slip differential increases causing differential limitation and deteriorating straight traveling stability
Solution Approach 1:
The control unit dynamically adjusts the engagement force of the center limited slip differential mechanism based on real-time detection of bump conditions and accelerator operation. By making the differential limitation force variable rather than fixed, the system can adapt to changing road conditions and driver inputs, allowing high torque transmission for climbing while preventing excessive differential limitation that would cause yaw moments
Solution Approach 2:
The system uses feedback from the bump detection unit and accelerator-operation detection unit to continuously monitor road conditions and driver intent. Based on this feedback, the control unit adjusts the engagement force of the center limited slip differential mechanism to optimize both climbing performance and straight traveling stability, preventing differential limitation when bump climbing is not required
2Force
If a torque-sensitive limited slip differential is used to limit differential between wheels, then traction is improved, but rough accelerator operation during bump climbing causes excessive differential limitation and generates yaw moments
Solution Approach 1:
The system performs preliminary detection of bump conditions and rough accelerator operations before excessive differential limitation occurs. By detecting these conditions in advance using the bump detection unit and accelerator-operation detection unit, the control unit can pre-adjust the engagement force of the center limited slip differential mechanism to prevent the generation of harmful yaw moments while maintaining necessary traction
Data Source
AI summary
When the operation amount of an accelerator exceeds a predetermined value at a time of climbing over a bump with either one of right and left front wheels, a HEV-CU increases the regenerative torque of a first motor generator, reduces the output torque of a second motor generator, and increases the engagement force of a LSD clutch of a center differential unit so as to reduce the input torque of a front LSD. When the operation amount of the accelerator exceeds the predetermined value at a time of climbing over a bump with either one of left and right rear wheels, the HEV-CU increases the regenerative torque of the first motor generator, reduces the output torque of the second motor generator, and reduces the engagement force of the LSD clutch so as to reduce the input torque of the rear LSD.