Front Rear Wheel Drive Force Distribution Control
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Solution Overview
Problem
In front and rear wheel drive vehicles, existing technologies can exacerbate understeer when the rotational speed difference between main and auxiliary drive wheels is small, leading to excessive differential limiting force and further understeer during turning.
Innovation Solution
A method and device that reduces drive force distribution to the auxiliary drive wheels when the rotational speed difference is smaller than a predetermined threshold, using a control unit to adjust drive force distribution based on wheel speed and yaw rate data to minimize further understeer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If drive force distributed to rear wheels is increased when rotational speed difference is small, then vehicle stability is improved, but excessive differential limiting force generates reverse moment that further understeers the vehicle
Solution Approach 1:
The control device changes the parameter of drive force distribution ratio based on the rotational speed difference threshold. When the rotational speed difference is smaller than the threshold, the drive force distribution ratio to rear wheels is reduced, preventing excessive differential limiting force and reverse moment generation, thus resolving the contradiction between vehicle stability and understeer prevention
2Speed
If drive force distributed to rear wheels is increased during understeer, then turning performance is improved, but excessive differential limiting force generates reverse moment that further understeers the vehicle
Solution Approach 1:
The system dynamically adjusts the drive force distribution ratio parameter based on real-time rotational speed difference measurements. By reducing the distribution ratio to rear wheels when rotational speed difference is small, the system prevents reverse moment generation while maintaining adequate turning performance
3Reliability
If differential limiting force is increased to prevent wheel slip, then traction is improved, but reverse moment is generated that further understeers the vehicle
Solution Approach 1:
The control device adjusts the differential limiting force parameter by modifying the drive force distribution ratio to rear wheels based on rotational speed difference. When rotational speed difference is small, reducing the distribution ratio prevents excessive differential limiting force and reverse moment, maintaining traction reliability while preventing understeer
Data Source
AI summary
A drive force distribution method and a drive force distribution control device is provided for a front and rear wheel drive vehicle provided with a drive force distribution device that controls a distribution of a drive force generated by a drive force source to main drive wheels and auxiliary drive wheels. A present distribution of the drive force to an auxiliary drive wheel side is increased by a first predetermined amount upon determining the rotational speed difference between the rotational speeds of the main drive wheels and the auxiliary drive wheels has been determined to not be smaller than a predetermined rotational speed difference. The present distribution of the drive force to the auxiliary drive wheel side is reduced by a second predetermined amount when the rotational speed difference has been determined to be smaller than the predetermined rotational speed difference.