Vehicle Torque Control for Stable Low-Friction Starts
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Solution Overview
Problem
Anti-slip control systems face challenges in stabilizing vehicle starting on low friction surfaces like snow or ice, as the target slip at standstill tends to infinity, leading to instability and potential inability to start, especially on inclines.
Innovation Solution
A method to limit the increase in actual drive torque from an internal combustion or electric motor to a maximum value, ensuring stable starting by restricting torque growth only when exceeding a calculated maximum, dependent on road gradient, temperature, and driver settings, allowing safe acceleration without driver intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drive torque is increased to accelerate the vehicle from standstill, then the productivity is improved, but the stability deteriorates due to wheel spinning on low friction surfaces
Solution Approach 1:
The patent applies dynamics by continuously adapting the torque increase rate (delta Mmax) based on real-time vehicle conditions including slip detection, road gradient, and ambient temperature. The system transitions from a static torque control approach to a dynamic one where the torque increase is adjusted moment-by-moment to maintain stability while enabling acceleration.
Solution Approach 2:
The patent changes the parameter of torque increase rate (delta Mmax) based on multiple conditions: reducing it when slip is detected, lowering it on inclined roads, and adjusting it according to ambient temperature. This parameter adaptation allows the system to optimize the trade-off between acceleration performance and starting stability under varying conditions.
2Reliability
If the target slip is set to prevent engine stalling, then the reliability is improved, but the stability deteriorates as wheels enter the unstable area of the friction-slip curve
Solution Approach 1:
The patent applies preliminary action by detecting road gradient and environmental conditions before the vehicle starts moving, and pre-calculating the appropriate torque increase rate (delta Mmax) to prevent instability. The system prepares the optimal torque profile in advance based on predicted conditions, rather than reacting after instability occurs.
Solution Approach 2:
The patent implements feedback by continuously monitoring wheel slip during the starting process and adjusting the torque increase rate accordingly. When slip exceeds a threshold, the system reduces delta Mmax to bring the operation back into the stable friction area, creating a closed-loop control that maintains both engine reliability and starting stability.
3Stability of the object's composition
If the drive torque is limited to prevent wheel spinning, then the stability is improved, but the productivity deteriorates due to reduced acceleration capability
Solution Approach 1:
The patent applies partial action by limiting only the rate of torque increase (delta Mmax) rather than capping the absolute torque value. This allows the torque to eventually reach the driver's requested level for full acceleration capability, while the controlled increase rate prevents wheel spinning during the transient phase, achieving both stability and productivity.
Data Source
Figure 1~2
AI summary
In a method for adjusting the starting torque during the starting process in a vehicle, the increase (d?dr) of the effectively acting actual driving torque (Mist) is limited to a maximum (d?max) increase.