Redundant Electrohydraulic Braking for Driverless Failure Response
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Solution Overview
Problem
Current electrohydraulic power vehicle braking systems for autonomous driving lack redundancy, making them susceptible to complete failure without driver intervention, especially at higher automation levels (Levels 4 and 5), where driver intervention is not always possible.
Innovation Solution
The electrohydraulic power vehicle braking system incorporates two redundant power brake pressure generators connected to hydraulic wheel brakes, allowing selective actuation without driver intervention in case of a malfunction, with one generator directly connected to a depressurized brake fluid reservoir and the other connected via check and solenoid valves, ensuring continuous braking functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single power brake pressure generator is used, then the device complexity is reduced, but the reliability deteriorates due to susceptibility to complete failure
Solution Approach 1:
The braking system is divided into two independent power brake pressure generators, each capable of independently actuating the hydraulic wheel brakes. This segmentation creates redundancy where each generator can function autonomously, ensuring that if one fails, the other can maintain braking functionality without driver intervention.
Solution Approach 2:
The system incorporates a brake fluid reservoir that can supply brake fluid to both power brake pressure generators simultaneously. This prior cushioning ensures that even if one generator fails, the reservoir maintains sufficient fluid supply for the remaining generator to operate, preventing complete system failure.
2Reliability
If two redundant power brake pressure generators are implemented, then the reliability improves for autonomous driving, but the device complexity increases
Solution Approach 1:
Both power brake pressure generators are designed with identical functionality and connect to the same brake fluid reservoir and wheel brakes. This universality allows either generator to perform the complete braking function independently, maximizing redundancy while minimizing the need for additional specialized components.
Solution Approach 2:
The two power brake pressure generators share common components including the brake fluid reservoir, wheel brakes, and control systems. By merging these components, the system achieves redundancy in the critical pressure generation function while reducing overall complexity compared to having completely separate braking systems.
3Reliability
If the second power brake pressure generator is connected via check valve and solenoid valve, then the reliability improves through controlled fluid flow, but the device complexity increases
Solution Approach 1:
The check valve and solenoid valve act as intermediaries between the brake fluid reservoir and the second power brake pressure generator. The check valve ensures unidirectional flow to prevent contamination, while the solenoid valve provides controlled fluid supply. These intermediary components protect the critical pressure generation function while maintaining manageable complexity through standardized valve designs.
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 design ensures reliable and fail-safe braking without driver intervention, enabling safe autonomous driving at Levels 4 and 5 by allowing seamless switching between power brake pressure generators, maintaining braking performance and enabling anti-lock braking and vehicle dynamics control systems.
Implementation Method 1
The second power brake pressure generator is connected to the brake fluid reservoir by a check valve, through which a flow is possible in the direction from the brake fluid reservoir to the second power brake pressure generator
Implementation Method 2
The valve is, in particular, a solenoid valve
Implementation Method 3
two redundant power brake pressure generators to which one or multiple hydraulic wheel brake(s) is/are connected
Data Source
AI summary
An electrohydraulic power vehicle braking system for a motor vehicle driving autonomously on public roads is equipped with two redundant power brake pressure generators so that, in the event of independent driving and a failure of one power brake pressure generator, the other power brake pressure generator is able to decelerate the motor vehicle without driver intervention.