Dual-Circuit Brake System Fail-Operational Redundancy
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Solution Overview
Problem
In vehicles with partially, highly, or fully automated driving, a single fault in the braking system can lead to a delay in the vehicle driver taking control, compromising safety as conventional braking systems only provide an auxiliary braking effect, which is less than the service braking effect, and may not ensure immediate vehicle control.
Innovation Solution
A braking system with two independent brake circuits, each with a pressure generating device and energy source, allowing for the generation of a service braking effect even if one circuit fails, ensuring the system remains operational (fail-operational) and capable of switching to a functional circuit, thus maintaining the desired braking effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single brake circuit is used, then the device complexity is low, but the reliability deteriorates because a single fault compromises safety and delays driver control
Solution Approach 1:
The braking system is divided into two independent brake circuits (first brake circuit and second brake circuit), each capable of independently providing service braking effect. This segmentation ensures that a fault in one circuit does not compromise the entire braking system, thereby improving reliability while maintaining manageable complexity through modular design
Solution Approach 2:
Each brake circuit is equipped with its own pressure generating device and energy source, creating local independence. The first brake circuit has a first pressure generating device and first energy source, while the second brake circuit has a second pressure generating device and second energy source. This local quality ensures that each circuit can function independently, improving system reliability
2Reliability
If an auxiliary braking effect is provided in case of fault, then the device complexity remains low, but the reliability deteriorates because the auxiliary braking effect is less than the service braking effect and may not ensure immediate vehicle control
Solution Approach 1:
The system is designed with a second brake circuit that is prepared in advance to provide full service braking effect if the first brake circuit fails. This preliminary preparation ensures that when a fault occurs, the system can immediately switch to the backup circuit without degradation in braking capability, maintaining full safety assurance
Solution Approach 2:
The patent implements a redundant brake circuit that acts as a cushion against potential failures. The second brake circuit serves as a protective buffer that can absorb the impact of a fault in the first circuit, ensuring continuous safe operation without compromising braking performance
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 proposed braking system ensures that the service braking effect is maintained even after a single fault occurs, allowing for safe vehicle operation without immediate driver intervention, and provides an auxiliary braking effect in case of a double fault, enhancing operational safety and warning the driver to take control.
Implementation Method 1
a first pressure generating device of a first brake circuit, supplied from a first energy source, is controlled in operation so that a desired braking effect is generated
Implementation Method 2
an arrangement of brake lines which fluidly connects a brake master cylinder to wheel brake cylinders
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The brake system (1) has two brake circuits with two pressure generating units, which are supplied with energy from two energy sources. A single error in the brake circuits is detected, where the faulty brake circuit is deactivated and a functional brake circuit is activated. A braking effect generated by the former pressure generating unit is greater than or equal to a predetermined operating braking effect, where another braking effect generated by the latter pressure generating unit is greater than or equal to the predetermined operating braking effect. An independent claim is included for a method for generating a braking force in a vehicle, particularly in a partial, high or fully automatically operated vehicle.