Brake Pressure Distribution Control for Faster Wheel Lock Prevention

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Solution Overview

Problem

Existing electronic brake systems for motor vehicles take a significant amount of time to achieve optimal brake pressure distribution, leading to a high probability of wheel lock during the adaptation phase, especially under varying load conditions.

Innovation Solution

A method where a starting value for the pressure distribution ratio is determined in driver braking mode, taking into account the vehicle's loading conditions, allowing for quick adjustment of brake pressures by regulating differential slip between axles, using speed measurements from wheel sensors and a reference value from a separate motion sensor to calculate the ideal pressure distribution ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the brake control unit regulates the pressure distribution ratio between front and rear axles to achieve optimal brake pressure distribution, then the braking stability is improved, but the adjustment time is extended leading to wheel lock during the adaptation phase

Engineering Contradiction:
Improvebraking stabilityVSAvoidadjustment time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by determining and storing a starting value for the pressure distribution ratio in driver braking mode before external braking requests occur. This pre-determined value reflects the current vehicle loading conditions, so when external braking requests are received, the system already has an optimized starting point, significantly reducing the adaptation time and minimizing the risk of wheel lock during pressure regulation.

Inventive Principle:
Principle #10Preliminary action

2Stability of the object's composition

If the brake control unit maintains a stable pressure distribution ratio, then the driving behavior is stabilized, but the system cannot adapt quickly to varying load conditions

Engineering Contradiction:
Improvedriving behavior stabilityVSAvoidload condition adaptability
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by making the pressure distribution ratio adaptive rather than fixed. The system dynamically determines the pressure distribution ratio based on actual vehicle loading conditions detected through wheel speed measurements and differential slip evaluation. This allows the system to maintain stability within each loading condition while adapting to different loading scenarios, resolving the contradiction between stability and adaptability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by continuously monitoring wheel speeds and calculating differential slip between axles. This feedback mechanism allows the brake control unit to evaluate the current pressure distribution effectiveness and adjust the pressure distribution ratio accordingly, ensuring both stability during braking and adaptability to varying load conditions through real-time condition assessment.

Inventive Principle:
Principle #23Feedback

3Reliability

If the system uses differential slip control to regulate brake pressure distribution, then the adhesion optimization is improved, but the control complexity increases

Engineering Contradiction:
Improveadhesion optimizationVSAvoidcontrol complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies self-service by enabling the braking system to automatically evaluate and adjust its own pressure distribution ratio based on measured wheel speeds and differential slip. The system uses its own operational data (wheel speeds, slip measurements) to self-optimize the brake pressure distribution, eliminating the need for external intervention or complex additional sensors, thus improving adhesion while keeping control complexity manageable.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3500460B1Method for adjusting brake pressures, brake system of a motor vehicle for carrying out the method, and motor vehicle comprising such a brake system
Publication Date: 2023.09.20 ZF CV SYST EURO BV
  • EP3500460B1 patent drawingFigure 1
  • EP3500460B1 patent drawingFigure 2
  • EP3500460B1 patent drawing

AI summary

The invention relates to an electronic brake system, to a method for operating such a brake system, and to a motor vehicle comprising said brake system. A brake control unit determines the respective brake pressure P acting on wheel brakes by regulating (27) a pressure distribution ratio (45) of the brake pressures P acting on the wheel brakes of the front axle to the brake pressures P acting on the wheel brakes of a rear axle of the motor vehicle. The brake control unit (17) receives driver brake requests (32) determined by the driver of the motor vehicle and/or external brake requests (26) and determines corresponding brake pressures. The aim of the invention is to allow the ideal pressure distribution to be set as quickly as possible by a brake control unit (17). This is achieved in that the regulation (27) takes into consideration a pressure distribution ratio starting value (28) of the pressure distribution ratio, said value being ascertained in a driver braking mode (29) or pressure control mode (18) and being kept ready to be taken into consideration later.