Redundant Electrohydraulic Brake System for Automated Driving
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Solution Overview
Problem
Existing electrohydraulic brake systems for vehicles are not suitable for highly automated or independent driving as they fail to ensure safe braking without driver intervention in case of system failures, as they lack redundancy for wheel-specific brake pressure control and ESP functions.
Innovation Solution
A redundant brake system is introduced with a second electrohydraulic brake control device and an electrically controllable brake booster, connected in series with the wheel brakes, allowing for independent wheel-specific brake control and ESP functions, ensuring safe braking even with single system errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single electrohydraulic brake control device is used, then the device complexity is reduced, but the reliability of the brake system for highly automated driving is insufficient
Solution Approach 1:
The brake control system is divided into two independent brake control devices (first and second), each capable of independently controlling brake pressures. This segmentation provides redundancy so that if one device fails, the other can take over, thereby improving reliability while managing complexity through functional division
Solution Approach 2:
The system incorporates a backup brake control device that stands ready to take over in case of failure. This preemptive redundancy ensures that brake system reliability is maintained even when failures occur, as the secondary device is already in place to compensate for the primary device's failure
2Adaptability or versatility
If wheel-specific brake pressure control is implemented, then the ESP function is enabled, but the device complexity increases due to additional pressure control valves
Solution Approach 1:
Each brake control device is designed to perform multiple functions: it can control brake pressures for normal braking operations and also provide wheel-specific pressure control for ESP functions. This multi-functionality allows the system to achieve adaptability without requiring separate dedicated components for each function, thereby managing complexity
3Extent of automation
If the brake system is designed for remote control without driver intervention, then the extent of automation is improved, but the reliability requirement becomes more stringent
Solution Approach 1:
The brake system incorporates redundant brake control devices and a backup vacuum brake booster that can take over in case of failure. This preemptive redundancy ensures that the brake function remains available even when automation operates without driver intervention, meeting the stringent reliability requirements for highly automated driving
Solution Approach 2:
The vacuum brake booster acts as an intermediary mechanical backup system that can provide brake pressure without electronic control. In case of electronic brake control device failure, this mechanical intermediary ensures that braking function remains available, thereby supporting remote control operation with high reliability
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
The system ensures continuous safe braking and redundant wheel-individual brake control, enabling highly automated driving by allowing the second brake control device to take over in case of failures, ensuring wheel-specific brake pressures are maintained without driver intervention.
Implementation Method 1
an electric motor (64) which is constructed to drive the hydraulic pump (63)
Implementation Method 2
a hydraulic pump (63) which is constructed as an electrically controllable pressure source for actively and remotely controllable build-up of brake pressure
Implementation Method 3
pressure control valves (62) and an electrically controllable pump (63) for adjusting wheel-specific brake pressures
Implementation Method 4
a vacuum brake booster (101) which is arranged upstream of the main brake cylinder (102)
Data Source
AI summary
A brake system for vehicles, in particular motor vehicles, including a master brake cylinder, in particular a tandem master brake cylinder, a brake booster which is connected upstream of the master brake cylinder, in particular at least four hydraulically actuatable wheel brakes, and a first electrohydraulic brake control device which includes a first pressure regulating valve arrangement for adjusting wheel-specific brake pressures, in particular an electrically actuatable pressure source, and a wheel-specific outlet pressure connection for each wheel brake, wherein the brake booster is designed to be electrically actuatable, and a second electrohydraulic brake control device is provided which includes a second pressure regulating valve arrangement, in particular for adjusting wheel-specific brake pressures, and which is connected in series between the first brake control device and the wheel brakes.