Vehicle Brake Pressure Control via Switchover Valve Modulation
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Solution Overview
Problem
Existing vehicle braking systems face challenges in achieving precise pressure setting and axle-specific modulation of brake pressures, leading to undesirable vehicle pitch during braking torque distribution between axles, which affects driver experience and energy efficiency.
Innovation Solution
The solution involves using components of an ESP system to accurately set and modulate brake pressures through a control device that utilizes switchover valves and wheel inlet valves for Δp control, allowing for independent master brake cylinder pressure management and accounting for generator braking torque, ensuring precise brake force distribution and minimizing deceleration fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional hydraulic braking system is used, then basic braking function is provided, but pressure setting accuracy is insufficient and axle-specific modulation is not achieved
Solution Approach 1:
The braking system is segmented into independent brake circuits for front and rear axles, with separate pressure control for each axle. This segmentation enables axle-specific modulation of brake pressures while maintaining overall system functionality, resolving the contradiction between pressure setting accuracy and device complexity by dividing the control function into manageable independent units.
Solution Approach 2:
The control device integrates multiple functions including pressure setting, modulation, and monitoring within a single unit. It can operate in different modes (normal braking, ABS, ESP) and control different brake circuits, achieving high pressure setting accuracy without proportionally increasing device complexity through multi-functional integration.
2Ease of operation
If brake pressures are not accurately modulated, then simpler control is used, but undesirable vehicle pitch occurs due to interference in braking torque distribution
Solution Approach 1:
The control device continuously monitors actual brake pressures and compares them with target pressures, automatically adjusting valve positions to maintain accurate pressure modulation. This feedback mechanism eliminates undesirable vehicle pitch by ensuring proper braking torque distribution without requiring complex manual intervention, resolving the contradiction between ease of operation and harmful effects.
3Use of energy by moving object
If regenerative braking is used, then energy efficiency is improved, but fluctuations in deceleration occur affecting driver experience
Solution Approach 1:
The control device dynamically adjusts the distribution of braking torque between regenerative braking and friction braking based on real-time conditions. It modulates brake pressures to compensate for fluctuations in regenerative braking force, maintaining stable deceleration and improving driver experience while preserving energy efficiency benefits.
4Ease of manufacture
If existing ESP system components are utilized, then manufacturing costs and installation space are reduced, but pressure setting accuracy may be compromised
Solution Approach 1:
The control device optimizes the operating parameters of existing ESP components, such as valve opening times, pressure differential settings, and activation sequences. By precisely controlling these parameters, the system achieves high pressure setting accuracy using conventional components, resolving the contradiction between manufacturing cost and measurement precision.
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 ensures high pressure setting accuracy, reduces undesirable vehicle pitch, and maintains constant brake force distribution, enhancing driver experience and energy efficiency by optimizing braking system operation, including during regenerative braking.
Implementation Method 1
a hydraulic braking system may include a master brake cylinder (32) having a master brake cylinder pressure pHZ
Implementation Method 2
a Δp control of the first actual brake pressure to be reduced through the first switchover valve (26) and/or a Δp control of the second actual brake pressure to be reduced through the second switchover valve (26)
Data Source
AI summary
A method for operating a braking system of a vehicle includes: establishing a first setpoint brake pressure to be set in a first wheel brake cylinder of a first brake circuit and a second setpoint brake pressure to be set in a second wheel brake cylinder of a second brake circuit; reducing first and second actual brake pressures by setting a master brake cylinder pressure to be no greater than a minimum of the first and second setpoint brake pressures, and controlling a first switchover valve of the first brake circuit and/or of the second brake circuit; and/or increasing the first and second actual brake pressures by setting the master brake cylinder pressure to be no smaller than a maximum of the first and second setpoint brake pressures, and activating a first wheel inlet valve of the first brake circuit and/or of the second brake circuit.