Vehicle Brake Pressure Control for Wheel Lock Prevention
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Solution Overview
Problem
Conventional vehicle brake systems face challenges in managing high brake pressures during emergency braking, leading to wheel lock and increased NVH (Noise, Vibration, Harshness) on low traction surfaces, and fail to effectively convert brake force into vehicle deceleration due to varying road conditions.
Innovation Solution
A method that estimates the maximum brake pressure for each wheel to prevent lockup, maintains a constant hydraulic brake pressure margin above this limit, and reduces pressure if it exceeds this limit to prevent wheel lock and maintain traction, using ABS data and control units to adjust brake pressure dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high brake pressure is applied during emergency braking, then braking force is improved, but wheel lock occurs and NVH increases
Solution Approach 1:
The system performs preliminary estimation of the brake pressure that would cause wheel lock (μ-step prediction) before actual wheel lock occurs. By calculating the estimated brake pressure for each wheel based on current driving conditions, the system proactively limits brake pressure to prevent wheel lock and NVH issues before they happen, rather than reacting after wheel lock occurs
Solution Approach 2:
The system continuously monitors actual brake pressure and compares it against the estimated pressure limit. When the actual brake pressure approaches the estimated limit, the system provides feedback control to reduce brake pressure, maintaining a safe margin below the wheel lock threshold. This closed-loop feedback ensures braking force is optimized without causing wheel lock
2Reliability
If brake pressure is reduced to prevent wheel lock, then wheel lock is avoided, but braking effectiveness is reduced
Solution Approach 1:
The system applies partial action by maintaining brake pressure at a level that is sufficient for effective braking but deliberately stays below the maximum pressure that would cause wheel lock. By applying a safety margin (e.g., limiting to 90% of the estimated wheel lock pressure), the system achieves near-maximal braking effectiveness while preventing wheel lock and NVH issues
Solution Approach 2:
The system dynamically adjusts the brake pressure parameter based on changing road conditions and adhesion coefficients. By continuously updating the estimated brake pressure limit based on current μ conditions and adjusting the actual brake pressure accordingly, the system optimizes braking effectiveness while preventing wheel lock across varying driving conditions
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 method ensures stable braking by maintaining a safe brake pressure margin, reducing the likelihood of wheel lock and NVH issues, and improving traction on changing road surfaces by continuously adjusting brake pressure in a controlled manner.
Implementation Method 1
generating a hydraulic brake pressure
Data Source
AI summary
A method for operating a hydraulic motor vehicle brake system with an anti-lock brake system having a plurality of brake cylinders associated with the wheels to be braked. A central pressure generating device generates a hydraulic brake pressure, wherein the hydraulic brake pressure is distributed to the brake cylinders and may be selectively modified for individual brake cylinders or a group of brake cylinders. The hydraulic brake pressure maintained at a level exceeding an estimated brake pressure limit of each wheel.