Brake Pressure Ratio Control to Prevent Front-Rear Wheel Locking
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Solution Overview
Problem
Modern brake systems face challenges in maintaining an ideal pressure distribution ratio between the front and rear axles of a motor vehicle, leading to differential slip and potential wheel locking, which affects driving stability and triggers unwanted anti-lock braking system interventions.
Innovation Solution
A method where the brake control unit determines a pressure distribution ratio starting value in normal braking mode, accounting for load states, and uses this value in pressure control mode to adjust brake pressures, ensuring an ideal pressure distribution ratio is maintained, thereby minimizing differential slip and preventing unnecessary anti-lock interventions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the brake pressure is adjusted directly by the driver in normal braking mode, then the ease of operation is improved, but the stability of the pressure distribution ratio between front and rear axles deteriorates
Solution Approach 1:
The system determines and stores a pressure distribution ratio starting value during normal braking mode before switching to pressure control mode. This preliminary action ensures that when the brake control unit takes over, it has a pre-established reference value to maintain stable pressure distribution, avoiding sudden changes that would occur without this preparatory step.
Solution Approach 2:
The system continuously monitors the actual pressure distribution ratio and compares it with the ideal ratio (controlling for front axle to rear axle pressure). The brake control unit uses this feedback to dynamically adjust brake pressures, ensuring the pressure distribution remains stable during pressure control mode operations.
2Reliability
If the brake control unit takes over pressure adjustment in pressure control mode, then the reliability of drive stability functions is improved, but the response time for pressure adjustment deteriorates
Solution Approach 1:
The pressure distribution ratio starting value is determined and stored during normal braking mode before the system needs to switch to pressure control mode. This preliminary preparation eliminates the need for complex calculations when switching modes, allowing the brake control unit to immediately implement reliable drive stability functions with minimal delay.
Solution Approach 2:
The system dynamically switches between normal braking mode and pressure control mode based on driving conditions. During the transition, the stored starting value is maintained and adapted, allowing the system to maintain both reliability and responsive adjustment time by flexibly adapting the control strategy to current conditions.
3Stability of the object's composition
If the ideal pressure distribution ratio is controlled during external braking demands, then the stability of the motor vehicle is improved, but the complexity of the control system increases
Solution Approach 1:
The system pre-determines and stores the pressure distribution ratio starting value during normal braking operations. This preliminary action provides a ready-reference value that simplifies the control calculations during external braking demands, maintaining vehicle stability without requiring complex real-time computations that would increase system complexity.
Solution Approach 2:
The system changes the control parameter from calculating ideal pressure distribution from first principles to using a pre-stored starting value that is maintained and adapted. This parameter change simplifies the control algorithm while still achieving the goal of maintaining ideal pressure distribution ratio for vehicle stability.
Data Source
AI summary
A method for adjusting brake pressures on wheel brakes of a motor vehicle includes adjusting, in a normal braking mode as a function of a driver's braking demand determined by a driver of the motor vehicle, the brake pressures on the wheel brakes. The method further includes carrying out, by a brake control unit in a pressure control mode, adjustment of the brake pressures on the wheel brakes to implement at least a drive stability function and/or external braking demands. Furthermore, the method includes determining, by the brake control unit, the brake pressures on the wheel brakes at least when implementing external braking demands while controlling an ideal pressure distribution ratio of the brake pressures at wheel brakes of the front axle to the brake pressures at wheel brakes of a rear axle of the motor vehicle, wherein the control function takes into account a pressure distribution ratio.