Rail Brake Friction Estimation for Stable Braking Distance
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Solution Overview
Problem
Existing brake systems for rail vehicles face significant variations in braking distances due to fluctuating coefficients of friction influenced by factors like brake disc temperature, friction speed, clamping force, and external conditions, leading to inaccuracies in deceleration and braking distance predictions.
Innovation Solution
A method for estimating the coefficient of friction using linear functions of brake disc temperature, friction speed, and clamping force, allowing for simplified and accurate compensation of friction variations, independent of other influencing factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant reference coefficient of friction is used for brake control calculations, then the control system is simple to implement, but the braking distance varies significantly due to friction fluctuations caused by temperature, speed, and clamping force changes
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant reference coefficient of friction to a dynamic estimation approach. The coefficient of friction is continuously estimated based on real-time operating conditions (brake disc temperature, friction speed, clamping force) using linear functions. This allows the brake control system to adapt to changing friction conditions while maintaining reasonable system complexity, resolving the contradiction between simplicity and accuracy.
2Reliability
If train-wide average deceleration control is implemented, then the overall braking performance is improved, but individual wheelsets may experience varying traction levels that risk exceeding adhesion limits
Solution Approach 1:
The patent applies local quality by enabling individual coefficient of friction estimation for each wheelset or bogie based on its specific operating conditions. This allows the brake control system to adapt braking forces to local friction characteristics at each wheelset, preventing adhesion limit exceedances while maintaining reliable overall braking performance. Each wheelset receives tailored control based on its unique temperature, speed, and clamping force conditions.
3Measurement precision
If complex test bench parameters are used to determine characteristic curves for coefficient of friction, then the friction estimation accuracy is improved, but the system complexity and calibration effort increase significantly
Solution Approach 1:
The patent applies parameter changes by simplifying the characteristic curve determination process. Instead of using complex multi-parameter test bench procedures, the invention uses linear functions with fewer parameters (temperature, speed, clamping force) to estimate the coefficient of friction. This reduces calibration complexity and system complexity while maintaining sufficient estimation accuracy for practical brake control applications.
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 enables precise braking control by minimizing deviations from desired frictional values, reducing braking distance variations, and ensuring safe and efficient train deceleration.
Implementation Method 1
the coefficient of friction between the pad and disc is not constant as desired, but is influenced by various system parameters and conditions such as the clamping force, the brake disc temperature, and the friction speed
Data Source
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AI summary
The invention relates to a method for estimating a coefficient of friction (µ) for a brake pad-brake disk pairing, the coefficient of friction (µ) being estimated depending on a reference coefficient of friction (µref) via at least one linear function of the brake disk temperature (T) and/or of the frictional speed (v) and/or of the clamping force (Fb).