Active Wheel Slip Control via Electric Torque
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Solution Overview
Problem
Conventional anti-lock brake systems (ABS) rely on wheel friction for acceleration during excessive braking or changing road conditions, leading to inefficiencies and increased wear, as they wait for wheel lockage or rely on passive frictional forces for re-acceleration.
Innovation Solution
A brake device with an acceleration device, such as an electric machine, applies counter-rotational braking torque and rotational acceleration torque to actively manage wheel slip, allowing for immediate torque changes and reduced wear by using a combination of friction and electric braking, with a control system to maintain optimal slip values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional ABS waits for wheel lockage and relies on passive friction for re-acceleration, then the system structure remains simple, but braking efficiency is reduced and tire wear increases
Solution Approach 1:
The acceleration device (electric motor) is activated before the wheel fully locks to prevent lockage and maintain optimal slip ratio. This preliminary action allows active control of wheel acceleration, improving braking efficiency by keeping the tire in the optimal friction zone rather than waiting for passive friction to re-accelerate a locked wheel
Solution Approach 2:
The passive mechanical friction-based re-acceleration system is replaced with an active electric motor-driven acceleration system. This substitution enables precise control of wheel torque and slip ratio, significantly improving braking efficiency and reducing tire wear through active management of the wheel's rotational state
2Reliability
If the friction brake is continuously applied to maintain braking force, then braking effectiveness is maintained, but tire wear and energy loss increase
Solution Approach 1:
The brake control system implements periodic modulation of braking torque to maintain optimal slip ratio between 8-35%. By rhythmically adjusting brake application and release, the system maintains reliable braking effectiveness while minimizing tire wear through controlled slip cycles rather than continuous friction contact
Solution Approach 2:
The system dynamically changes the slip ratio parameter to optimal values (8-35%) during braking. By controlling the slip parameter rather than maintaining constant brake force, the system achieves reliable braking effectiveness while minimizing tire wear through optimized friction utilization
3Productivity
If the wheel rotational speed oscillates during ABS control, then optimal slip is maintained for braking efficiency, but vehicle stability may be compromised
Solution Approach 1:
The acceleration device control system uses feedback from wheel speed sensors to continuously monitor and adjust the acceleration torque. This closed-loop control maintains optimal slip ratio by adjusting motor torque in real-time, achieving efficient braking while stabilizing vehicle behavior through active compensation of oscillations
Solution Approach 2:
The electric acceleration device acts as an intermediary between the brake system and the wheel, mediating the interaction by providing compensating torque. This intermediary control smooths out rotational speed oscillations while maintaining optimal slip, thereby preserving vehicle stability during efficient braking operation
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
This approach reduces braking distance, minimizes tire wear, and enhances vehicle stability by actively controlling slip and lateral forces, preventing veering and maintaining optimal braking performance without relying on frictional forces, thus improving the overall braking efficiency and safety.
Implementation Method 1
An acceleration device, in particular an electric machine, is provided which is configured to apply the acceleration torque to the wheel
Implementation Method 2
In order to restore grip between the tread of the tire and the rolling surface of the roadway, the tread of the tire is to be accelerated again
Data Source
AI summary
In order to achieve a vehicle wheel (10) slip relative to a roadway (12) while braking the vehicle, said slip being as advantageous as possible, the rotational speed (w) of the wheel (10) can be actively reduced by an ABS by means of a braking intervention and passively allowed to accelerate again via the roadway (12) when the brake is released. The slip of the wheel (10) oscillates by an optimal slip value during the ABS regulating process. The aim of the invention is to improve an anti-lock braking system for a vehicle. In the method according to the invention, at least one wheel (10) of the vehicle is supplied with a braking torque (Mb) in order to temporarily reduce a travel speed (v) of the vehicle relative to a rolling surface (12), said braking torque acting against a rotating direction (14) of the wheel (10). Additionally, the wheel (10) is temporarily supplied with an acceleration torque (Ma) by means of an accelerating device of the vehicle during the reduction of the travel speed (v), said acceleration torque acting in the rotating direction (14).