Adaptive Retarder Control for Vehicle Braking Stability
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Solution Overview
Problem
Existing methods for controlling permanent brakes in motor vehicles fail to adapt effectively to changing friction coefficients and axle loads, leading to potential anti-lock braking system (ABS) responses and increased wear on friction brakes, especially in low-friction conditions.
Innovation Solution
A method that calculates a predicted retarder slip and adjusts a force constant to match real conditions, allowing for controlled limitation of braking force to prevent ABS responses, while optimizing continuous braking force based on friction and axle load, and transmitting this information via a data bus for electronic control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the permanent brake is completely switched off to prevent ABS response, then the risk of ABS activation is eliminated, but the desired wear-free braking cannot be maintained and friction brake wear increases
Solution Approach 1:
The patent applies dynamics by continuously adapting the brake slip limit value based on real-time detection of friction coefficient changes. The system transitions from a static fixed limit approach to a dynamic adaptive approach, where the limit is automatically adjusted according to actual road conditions detected during vehicle operation, thereby optimizing both ABS stability and brake efficiency.
Solution Approach 2:
The patent changes the parameter of brake slip limit from a fixed value to a variable that adapts to friction coefficient conditions. By detecting friction coefficient changes and相应ly adjusting the brake slip limit parameter, the system resolves the contradiction between preventing ABS activation and maintaining effective wear-free braking across varying road conditions.
2Ease of operation
If a fixed brake slip limit is used for the permanent brake, then the control is simple, but it cannot adapt to changing friction coefficients and axle loads, leading to ABS responses in low-friction conditions
Solution Approach 1:
The patent implements feedback by continuously detecting friction coefficient changes during vehicle operation and using this information to adjust the brake slip limit. The system monitors actual braking conditions and road friction characteristics, then feeds this information back to automatically modify the permanent brake control parameters, achieving adaptability while maintaining operational simplicity.
Solution Approach 2:
The system performs self-service by automatically detecting friction coefficient changes and adjusting its own control parameters without requiring manual intervention. The permanent brake control system self-adapts to changing road conditions by detecting friction variations and相应ly modifying the brake slip limit, eliminating the need for complex external control systems.
3Reliability
If the permanent brake braking force is limited to prevent ABS response, then ABS stability is maintained, but the braking force is lower than what the road friction can transmit, reducing braking efficiency
Solution Approach 1:
The patent dynamically changes the brake slip limit parameter based on detected friction coefficient conditions. When high friction is detected, the system allows higher brake slip limits that enable greater braking force utilization up to the road friction capability. When low friction is detected, it reduces the limit to prevent ABS activation, thereby optimizing braking force across different conditions.
Solution Approach 2:
The system transitions from a static braking force limitation to a dynamic one that adapts to real-time friction conditions. By continuously adjusting the brake slip limit according to detected friction coefficients, the system maximizes braking force utilization when road conditions permit while maintaining ABS stability when friction is low, resolving the power versus reliability contradiction.
Data Source
Figure 1
AI summary
The invention relates to a method for controlling at least one retarder of a motor vehicle. According to said method, the braking torque generated by the retarder is limited to a retarder limit torque. The aim of the invention is to improve the method such that it enables a wider range of application. To this end, the retarder limit torque is determined using a force constant FK which is defined in a traction phase of the motor vehicle, using the driving torque of the vehicle motor and the traction slip SAntrieb. In a retarder phase wherein the friction brake is not activated, a comparison is carried out between a previously calculated retarder slip and an actual measured retarder slip. If there is a deviation between the previously calculated retarder slip and the measured retarder slip, the force constant FK is automatically modified such that the previously calculated retarder slip is aligned with the measured retarder slip.