Vehicle Start Torque Control for Low-Adhesion Wheel Slip
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Solution Overview
Problem
Existing drive slip control systems fail to address instabilities and reduced traction during vehicle starting processes on low adhesion surfaces, particularly in adverse weather conditions, leading to excessive slip and reduced adhesion due to rapid wheel speed changes.
Innovation Solution
A method and system that control the starting process by limiting engine torque, incorporating clutch control and brake pressure regulation to maintain optimal wheel slip and adhesion, using sensors to monitor wheel speeds and road conditions, and adjusting clutch-gearbox engagement duration to prevent excessive slip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If drive slip control systems are used to control wheel slip during starting processes, then wheel slip can be limited, but instabilities and reduced traction can still occur on low adhesion surfaces
Solution Approach 1:
The control sequence is activated before the starting process begins, setting a maximum engine drive torque limit in advance. This preliminary action prevents excessive wheel slip from occurring in the first place, rather than reacting after slip has already occurred. The system prepares the torque limitation before the driver requests acceleration, ensuring stable traction from the moment the vehicle starts moving on low adhesion surfaces.
Solution Approach 2:
The maximum engine drive torque is dynamically redefined during the starting process based on actual wheel slip and driving speed measurements. The control sequence continuously monitors wheel speeds and adjusts the torque limit accordingly, transitioning from a static torque limitation to a dynamic adaptation that optimizes traction while preventing instability. This dynamic adjustment allows the system to respond to changing road conditions and vehicle state in real-time.
2Speed
If wheel speed is increased rapidly during starting process, then vehicle acceleration is improved, but adhesion value is reduced due to melting of the driving surface
Solution Approach 1:
The control sequence applies a counteracting torque limitation before excessive wheel speed and surface melting can occur. By setting and enforcing a maximum engine drive torque during the critical starting phase, the system prevents the wheel speed from rising too rapidly, thereby avoiding the melting of snow or ice on the driving surface and maintaining optimal adhesion values throughout the acceleration process.
3Object-generated harmful factors
If engine torque is reduced to limit wheel slip, then excessive slip is prevented, but traction and vehicle acceleration are compromised
Solution Approach 1:
The system dynamically adjusts the maximum engine drive torque during the starting process rather than applying a fixed reduction. By continuously monitoring wheel slip and driving speed, the control sequence optimizes the torque limitation in real-time, allowing maximum power delivery when traction is sufficient while applying torque reduction only when needed to prevent excessive slip. This dynamic approach maintains optimal acceleration performance while preventing harmful wheel slip.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures a stable and traction-rich starting process by preventing excessive slip, maintaining optimal adhesion, and avoiding the transition from static to sliding friction, even on low adhesion surfaces like ice or snow.
Implementation Method 1
particularly on a road with a low coefficient of friction... increased slip on the wheels of the drive axle can occur... controlling wheel slip of driven wheels... maintaining optimal wheel slip and adhesion
Data Source
AI summary
A method for controlling a starting process of a vehicle includes activating a control sequence and setting a control sequence signal, defining a maximum engine drive torque, and detecting a drive request for a starting process. The method further includes, in response to the drive request, controlling a clutch-gearbox unit with an engagement process duration, controlling wheel slip of driven wheels by determining wheel speeds of the driven wheels and at least setting an output drive torque at the output shaft, and redefining the maximum engine drive torque depending on the wheel slip and a driving speed. The method also includes deactivating the control sequence and resetting the control sequence signal when limit values are reached.