Limited-Slip Differential Torque Control for Vehicle Stability
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Solution Overview
Problem
Existing control systems for limited-slip differentials in AWD vehicles face challenges in balancing the tight corner braking phenomenon and slip phenomenon, particularly in varying road surface conditions, as they struggle to instantaneously adjust LSD torque based on vehicle speed and steering angle to maintain proper balance.
Innovation Solution
A control apparatus that calculates a basic LSD torque, subtracts a torque based on vehicle speed and steering angle, sets a minimum LSD torque, and adjusts the clutch engaging force to limit differential between front and rear wheels, ensuring appropriate LSD torque distribution through a target LSD torque setting module and clutch control module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the LSD torque is weakened to curb the tight corner braking phenomenon, then the steering characteristics are improved, but the slip phenomenon occurs on slippery road surfaces
Solution Approach 1:
The LSD torque is made dynamically adjustable based on vehicle speed and steering angle. The control apparatus calculates a basic LSD torque and subtracts a correction torque that varies with operating conditions, enabling the system to adapt the torque level to current driving circumstances rather than using a fixed torque value
Solution Approach 2:
The system changes the LSD torque parameter according to vehicle speed and steering angle parameters. By monitoring these parameters and adjusting the LSD torque accordingly, the system optimizes performance for different operating conditions - reducing torque during tight cornering while maintaining adequate torque for slip prevention
2Reliability
If the LSD torque is strengthened to curb the slip phenomenon, then the traction is improved, but the tight corner braking phenomenon occurs
Solution Approach 1:
The system dynamically adjusts LSD torque based on real-time vehicle speed and steering angle measurements. During tight cornering maneuvers, the control apparatus reduces the LSD torque to prevent braking phenomena, while under normal conditions it maintains higher torque for slip prevention
Solution Approach 2:
The LSD torque parameter is modified based on changes in vehicle speed and steering angle. The control apparatus calculates appropriate torque levels by considering these parameter variations, reducing torque when steering angle is large and speed is low, and maintaining higher torque when conditions allow
3Speed
If the LSD torque is reduced at low vehicle speeds to improve steering, then the steering responsiveness is improved, but the driving force transfer to road surface is insufficient
Solution Approach 1:
The control apparatus adjusts LSD torque based on vehicle speed parameter. At very low speeds, the system reduces torque to improve steering responsiveness, but maintains a minimum torque level to ensure adequate driving force transfer. The torque calculation incorporates speed-dependent scaling to balance these competing requirements
Data Source
AI summary
A control apparatus for a limited-slip differential for front and rear wheels of a vehicle, the control apparatus includes: a basic LSD torque calculation module configured to calculate a basic LSD torque at least on the basis of a transfer input torque; a subtraction LSD torque calculation module configured to calculate a subtraction LSD torque that is subtracted from the basic LSD torque at least on the basis of a vehicle speed and a steering angle; a minimum LSD torque calculation module configured to calculate a minimum LSD torque on the basis of the transfer input torque; a target LSD torque setting module configured to set a target LSD torque at least on the basis of the basic, subtraction, and minimum LSD torques; and a clutch control module configured to control an engaging force of a clutch.